VALVE TIMING CHANGE DEVICE

Abstract

A valve timing change device changes a relative rotation phase between a camshaft and a housing rotor which interlocks with rotation of a crankshaft to change open/close timing of an exhaust valve driven by the camshaft to an advancing side or a retarding side. The valve timing change device includes a rotation member which is driven to rotate by being exerted a rotation driving force; an external gear which is interlocked with the rotation member; a first internal gear which is directly or indirectly meshed with the external gear and is rotated integrally with the housing rotor; and a second internal gear which is directly or indirectly meshed with the external gear and is rotated integrally with the camshaft, and has a number of teeth smaller than the number of teeth of the first internal gear.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority benefit of Japanese Patent Application No. 2019-025192, filed on Feb. 15, 2019. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND DISCLOSURE

Technical Field

[0002] The disclosure relates to a valve timing change device of an internal combustion engine, in particular, to a valve timing change device which is applied when open/close timing (valve timing) of an exhaust valve is changed.

Related Art

[0003] As a conventional valve timing change device, the following valve timing change device is known which includes a timing sprocket that interlocks with rotation of a crankshaft, a driven member which is rotated integrally with the camshaft on an exhaust side, a phase change mechanism which is interposed between the timing sprocket and the driven member to change a relative rotation phase between the timing sprocket and the driven member, and a torsion spring which energizes the camshaft on an exhaust side to an advancing side with respect to the timing sprocket (for example, see patent literature 1: Japanese Patent No. 6054760).

[0004] Here, the phase change mechanism includes an electric motor, and a speed reduction mechanism which reduces the speed of output of the electric motor. The torsion spring functions as a failsafe which energizes the exhaust-side camshaft to an advancing side with respect to the timing sprocket when the electric motor or the like breaks down.

[0005] However, in the above device, because the torsion spring is employed, upsizing of the device in order to ensure an arrangement space of the torsion spring, cost increasing associated with component increasing, upsizing of the electric motor to overcome an energizing force of the torsion spring and enable the phase change, or the like is caused. In addition, if the torsion spring is damaged due to breakage or the like, the failsafe function cannot be obtained.

[0006] The disclosure provides a valve timing change device which can achieve simplification of structure, cost reduction, downsizing and the like, and ensure a failsafe function when applied to a camshaft of an exhaust valve.

SUMMARY

[0007] In one embodiment, the valve timing change device changes a relative rotation phase between a camshaft and a housing rotor which interlocks with a rotation of a crankshaft to change an open/close timing of an exhaust valve driven by the camshaft to an advancing side or a retarding side. The valve timing change device includes a rotation member which is driven to rotate by being exerted a rotation driving force; an external gear which is interlocked with the rotation member; a first internal gear which is directly or indirectly meshed with the external gear and is rotated integrally with the housing rotor; and a second internal gear which is directly or indirectly meshed with the external gear and is rotated integrally with the camshaft, the second internal gear having a number of teeth smaller than the number of teeth of the first internal gear.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a perspective view schematically showing a configuration in which a valve timing change device according to the first embodiment of the disclosure is applied to a camshaft for engine exhaust.

[0009] FIG. 2 is a partial cross-sectional view showing a relationship between the valve timing change device according to the first embodiment and an electric motor.

[0010] FIG. 3 is an exploded perspective view obliquely viewed from the front showing a relationship between the valve timing change device according to the first embodiment and a camshaft.

[0011] FIG. 4 is an exploded perspective view obliquely viewed from the rear showing a relationship between the valve timing change device according to the first embodiment and a camshaft.

[0012] FIG. 5 is a perspective cross-sectional view in a state that the valve timing change device according to the first embodiment is assembled to a camshaft.

[0013] FIG. 6 is an exploded perspective view of the valve timing change device according to the first embodiment obliquely viewed from the front.

[0014] FIG. 7 is an exploded perspective view of the valve timing change device according to the first embodiment obliquely viewed from the rear.

[0015] FIG. 8 is an appearance perspective view of a valve timing change device according to the second embodiment of the disclosure obliquely viewed from the front.

[0016] FIG. 9 is a perspective cross-sectional view of the valve timing change device according to the second embodiment.

[0017] FIG. 10 is a cross-sectional view of the valve timing change device according to the second embodiment.

[0018] FIG. 11 is an exploded perspective view of the valve timing change device according to the second embodiment obliquely viewed from the front.

[0019] FIG. 12 is an exploded perspective view of the valve timing change device according to the second embodiment obliquely viewed from the rear.

[0020] FIG. 13 is an appearance perspective view of a valve timing change device according to the third embodiment of the disclosure obliquely viewed from the front.

[0021] FIG. 14 is a perspective cross-sectional view of the valve timing change device according to the third embodiment.

[0022] FIG. 15 is a cross-sectional view of the valve timing change device according to the third embodiment.

[0023] FIG. 16 is an exploded perspective view of the valve timing change device according to the third embodiment obliquely viewed from the front.

[0024] FIG. 17 is an exploded perspective view of the valve timing change device according to the third embodiment obliquely viewed from the rear.

DESCRIPTION OF THE EMBODIMENTS

[0025] Embodiments of the disclosure are described below with reference to the accompanying drawings. A valve timing change device of the disclosure is applied to an internal combustion engine 1. Here, as shown in FIG. 1, the engine 1 includes a camshaft 2 which drives an exhaust valve to open/close, a camshaft 3 which drives an intake valve to open/close, valve timing change devices M, M2, M3 which are mounted corresponding to the camshaft 2, a valve timing change device D which is mounted corresponding to the camshaft 3, and a timing chain 4 which interlocks rotation of the crankshafts with a sprocket 11a of the devices M, M2, M3 and a sprocket of the device D.

[0026] Here, the camshaft 2 is rotated in one direction (an R direction in FIG. 1) around an axis line S, and includes, as shown in FIG. 3, a flange-like fitting portion 2a, a screw hole 2b, an oil passage 2c, and a fitting hole 2d of a positioning pin P. Furthermore, the camshaft 3 is the same as the camshaft 2.

[0027] Besides, the valve timing change devices M, M2, M3 are appropriately driven and controlled by an electric motor 5, and thereby open/close timing (valve timing) of the exhaust valve driven by the camshaft 2 is changed. Furthermore, the valve timing change device D is also appropriately driven and controlled by an electric motor 6, and thereby open/close timing of the intake valve driven by the camshaft 3 is changed.

[0028] Here, as shown in FIG. 2, the electric motor 5 includes a housing 5a, and a rotation shaft 5b which is rotatably supported by the housing 5a. The housing 5a is fixed to a portion of the engine 1, for example, a cover member 1a. The rotation shaft 5b generates a rotation driving force around the axis line S of the camshaft 2, and a coupling piece 5c mounted to an end portion of the rotation shaft 5b is coupled to a rotation member forming a portion of the valve timing change devices M, M2, M3 to exert the rotation driving force. Furthermore, configuration and functions of the electric motor 6 are the same.

[0029] As shown in FIG. 2 and FIGS. 5-7, the valve timing change device M according to the first embodiment includes a housing rotor 10, a first internal gear 20, second internal gear 30, a rotor 40 acting as a spacer member, an external gear 50, a receiving member 60, a bearing 70, and a rotation member 80.

[0030] The housing rotor 10 includes a first housing 11 which is supported rotatably around the axis line S, and a second housing 12 which is bounded to the first housing 11 by screws b1.

[0031] The first housing 11 is formed in a substantially cylindrical shape using a metal material and includes the sprocket 11a, a cylindrical portion 11b, an inner peripheral surface 11c, an annular bottom wall surface 11d, oil passages 11e and 11f, an advancing side stopper 11g, a retarding side stopper 11h, and a plurality of screw holes 11j for the screws b1 to be screwed in.

[0032] The inner peripheral surface 11c is slidably in contact with an outer peripheral surface 31a of the second internal gear 30 so that the first housing 11 is rotatably supported around the axis line S. The bottom wall surface 11d is slidably in contact with an outer periphery region of a joining surface 34 of the second internal gear 30 so that the first housing 11 is positioned in a direction of the axis line S. The oil passage 11e is formed into a groove shape extending in parallel to the axis line S in the inner peripheral surface 11c, and leads lubricant oil to a sliding region of the outer peripheral surface of 31a of the second internal gear 30 and the inner peripheral surface 11c, the lubricant oil being led into the second internal gear 30 through the oil passage 2c of the camshaft 2 and an oil passage 45 of the rotor 40. The oil passage 11f is formed into a groove shape extending in a radial direction on a front end surface of the cylindrical portion 11b and leads the lubricant oil which is led into the housing rotor 10 to the outside of the housing rotor 10. The advancing side stopper 11g comes into contact with an advancing side contact portion 46 of the rotor 40 to position the camshaft 2 at a maximum advancing position. The retarding side stopper 11h comes into contact with a retarding side contact portion 47 of the rotor 40 to position the camshaft 2 at a maximum retarding position.

[0033] The second housing 12 is formed into a disc shape using a metal material and includes a circular opening portion 12a centered on the axis line S, and a plurality of circular holes 12b through which the screws b1 pass. The opening portion 12a leaves a gap around the rotation member 80 to expose an annular portion 81 and a coupling portion 82 which are end portions of the rotation member 80.

[0034] Besides, after the second internal gear 30 which is fitted with the rotor 40, the receiving member 60, the first internal gear 20, the external gear 50 and the rotation member 80 fitted with the bearing 70 are assembled with respect to the first housing 11, the second housing 12 is bounded to the first housing 11 by the screws b1, and thereby the housing rotor 10 which is rotated around the axis line S is formed.

[0035] Here, the housing rotor 10 is rotatably supported around the axis line S via the second internal gear 30, and thus the housing rotor 10, the external gear 50, and the first internal gear 20 can be positioned using the second internal gear 30 fixed to the camshaft 2 as a reference. In addition, a configuration including the first housing 11 and the second housing 12 is employed as the housing rotor 10, the above various components are accommodated in the first housing 11 and the second housing 12 is combined with respect to the first housing 11, and thereby the valve timing change device M can be easily assembled.

[0036] The first internal gear 20 is, as shown in FIG. 6 and FIG. 7, formed into a substantially annular shape by, for example, forging using a metal material, and includes a cylindrical portion 21 which is centred on the axis line S, a row of teeth 22, a flange portion 23, and a plurality of circular holes 24 through which the screws b1 pass.

[0037] The cylindrical portion 21 is formed to have an outer diameter dimension to be fitted to the inner peripheral surface 11c of the first housing 11. The row of teeth 22 has the number of teeth Z2 and is formed in an annular arrangement centered on the axis line S on an inner peripheral surface of the cylindrical portion 21. The row of teeth 22 is meshed with substantially one half of a front region of a row of teeth 51 of the external gear 50 in the direction of the axis line S. Here, "front" is the left of the direction of the axis line S in FIG. 2, that is, a side where the electric motor 5 is arranged. The flange portion 23 is formed into a flat plate shape perpendicular to the axis line S and is assembled by being clamped between the first housing 11 and the second housing 12. That is, the first internal gear 20 is fixed by the screws b1 to be meshed with the external gear 50 in a manner of rotating integrally with the housing rotor 10.

[0038] In addition, the first internal gear 20 is formed separately from the housing rotor 10 and later mounted to the housing rotor 10. Therefore, compared with a case in which the first internal gear 20 is formed integrally with the housing rotor 10, manufacturing is facilitated and productivity is improved.

[0039] The second internal gear 30 is, as shown in FIG. 6 and FIG. 7, formed into a cylindrical shape with bottom by, for example, forging using a metal material, and includes a cylindrical portion 31, a row of teeth 32, a bottom wall surface 33, the joining surface 34, a fitting hole 35, oil passages 36, 37, and an inner peripheral corner R portion 38.

[0040] The cylindrical portion 31 defines the outer peripheral surface 31a centered on the axis line S to be slidably in contact with the inner peripheral surface 11c of the first housing 11. The row of teeth 32 has the number of teeth Z3 smaller than the number of teeth Z2 of the first internal gear 20 and is formed into an annular arrangement centred on the axis line S on an inner peripheral surface of the cylindrical portion 31. The row of teeth 32 is meshed with substantially one half of a back region of a row of teeth 51 of the external gear 50 in the direction of the axis line S. Here, "back" is the right of the direction of the axis line S in FIG. 2, that is, a side where the camshaft 2 is arranged. The bottom wall surface 33 is formed as a flat surface perpendicular to the axis line S and is arranged in contact with the receiving member 60 to function as a bearing surface of a fastening bolt b2. The joining surface 34 is formed into a flat surface parallel to the bottom wall surface 33 so that the rotor 40 is joined. The fitting hole 35 is formed into a circular shape centered on the axis line S so that a cylindrical fitting portion 42 of the rotor 40 is fitted to the fitting hole 35. The oil passage 36 is formed as a groove extending in the radial direction on the bottom wall surface 33 and leads the lubricant oil passing through the oil passage 45 of the rotor 40 and the inner of the cylindrical fitting portion 42 into the second internal gear 30. The oil passage 37 is formed as a groove extending in the radial direction on a front end surface of the cylindrical portion 31 and leads the lubricant oil inside the second internal gear 30 to the oil passages 11e, 11f of the first housing 11. The inner periphery corner R portion 38 is formed to be curved in a region connected to the inner peripheral surface of the cylindrical portion 31 from a peripheral edge of the bottom wall surface 33, and is a region with no row of teeth 32 in the direction of the axis line S.

[0041] The rotor 40 is formed into a substantially flat plate shape using a metal material and includes, as shown in FIG. 6 and FIG. 7, a through hole 41, the cylindrical fitting portion 42, a fitting concave portion 43, a positioning hole 44, the oil passage 45, the advancing side contact portion 46, and the retarding side contact portion 47.

[0042] The through hole 41 is formed into a circular shape centred on the axis line S so that the fastening bolt b2 passes through with a gap through which the lubricant oil flows. The cylindrical fitting portion 42 defines a portion of the through hole 41 and is formed into a cylindrical shape centred on the axis line S so as to be fitted into the fitting hole 35 of the second internal gear 30 and not to block the oil passage 36 in the fitting state. The fitting concave portion 43 is formed into a circular shape centred on the axis line S so that the fitting portion 2a of the camshaft 2 is fitted to the fitting concave portion 43. The positioning hole 44 is formed so that the positioning pin P fixed to the fitting hole 2d of the camshaft 2 is fitted and the positioning hole 44 serves to determine an angular position around the axis line S. The oil passage 45 is formed as a groove which extends in the radial direction to communicate with the through hole 41 and communicate with the oil passage 2c of the camshaft 2 on a bottom wall surface of the fitting concave portion 43, and leads the lubricant oil supplied from the oil passage 2c of the camshaft 2 into the second internal gear 30 through the through hole 41. The advancing side contact portion 46 detachably comes into contact with the advancing side stopper 11g of the first housing 11. The retarding side contact portion 47 detachably comes into contact with the retarding side stopper 11h of the first housing 11.

[0043] Besides, the rotor 40 is assembled integrally with the second internal gear 30 in advance by fitting the cylindrical fitting portion 42 to the fitting hole 35. Then, in a state that the first housing 11 is rotatably mounted to the second internal gear 30, the rotor 40 is brought close to the camshaft 2, the positioning pin P is fitted into the positioning hole 44, and the fitting portion 2a is fitted into the fitting concave portion 43. In this way, the rotor 40 is joined to the camshaft 2. Thereafter, the fastening bolt b2 is screwed into the screw hole 2b through the through hole 41, and thereby the second internal gear 30 is fixed to the camshaft 2 via the rotor 40.

[0044] In addition, the rotor 40 is positioned at the maximum advancing position by the advancing side contact portion 46 coming into contact with the advancing side stopper 11g and is positioned at the maximum retarding position by the retarding side contact portion 47 coming into contact with the retarding side stopper 11h. That is, for the camshaft 2, a relative rotation range with respect to the housing rotor 10 is regulated via the rotor 40. In this way, a range of the rotation phase in which the valve timing can be changed, that is, an adjustable angle range from the maximum retarding position to the maximum advancing position can be regulated to a desired range.

[0045] Here, by employing the rotor 40 acting as a spacer member, when a shape of the fitting portion 2a of the camshaft 2 differs according to specification of the engine, the valve timing change device M can be applied to various engines simply by setting the rotor 40 corresponding to various camshafts 2.

[0046] As shown in FIG. 6 and FIG. 7, the external gear 50 is formed, using a metal material, into a thin-walled cylindrical shape with thickness being elastically deformable and includes the row of teeth 51 on an outer peripheral surface of the external gear 50. The row of teeth 51 has the number of teeth Z1 different from the number of teeth Z2 of the first internal gear 20, substantially one half of a front region in the direction of the axis line S is meshed with the row of teeth 22 of the first internal gear 20, and substantially one half of a back region in the direction of the axis line S is meshed with the row of teeth 32 of the second internal gear 30. Furthermore, in the embodiment, a case that the number of teeth Z1 is different from the number of teeth Z2 is shown, but the disclosure is not limited to this, and the number of teeth Z1 may be the same as the number of teeth Z2 as long as a condition that the number of teeth Z3 is smaller than the number of teeth Z2 is satisfied.

[0047] Besides, the external gear 50 is deformed into an elliptical shape by receiving a cam action of a cam portion 83 of the rotation member 80 via the bearing 70 to be directly meshed with the first internal gear 20 in two regions and directly meshed with the second internal gear 30 in two regions.

[0048] As shown in FIG. 6 and FIG. 7, the receiving member 60 is formed, using a metal material, into an annular shape forming a flat plat and has a thickness larger than a length dimension of the inner periphery corner R portion 38 of the second internal gear 30 in the direction of the axis line S. Besides, the receiving member 60 is assembled to come into contact with the bottom wall surface 33 of the second internal gear 30 and serves to receive an end surface of the external gear 50 in the direction of the axis line S and to restrain the external gear 50 from entering a side of the inner periphery corner R portion 38.

[0049] In this way, by employing the receiving member 60, an additional cutting operation or the like in the second internal gear 30 becomes unnecessary, and cost reduction can be achieved as a whole. Furthermore, in the second internal gear 30, when there is no inner periphery corner R portion 38 and an annular groove is formed in an inner periphery corner region or when the row of teeth 33 is formed in the entire region in the direction of the axis line S, the receiving member 60 may be abolished.

[0050] As shown in FIG. 2, the bearing 70 includes an annular inner ring 71, an annular outer ring 72, a plurality of rolling bodies 73 which is arranged between the inner ring 71 and the outer ring 72 in a freely rolling manner, and a retainer 74 for holding the plurality of rolling bodies 73.

[0051] The inner ring 71 is formed into an elastically deformable endless belt shape using a metal material and the cam portion 83 of the rotation member 80 is fitted into the inner side of the inner ring 71. The outer ring 72 is formed into an elastically deformable endless belt shape using a metal material and is fitted into the inner side of the external gear 50. The plurality of rolling bodies 73 is formed into a spherical shape using a metal material, clamped between the inner ring 71 and the outer ring 72, and held by the retainer 74 at equal intervals around the axis line S. The retainer 74 is formed into an elastically deformable endless belt shape using a metal material and holds the plurality of rolling bodies 73 at equal intervals in a freely rolling manner.

[0052] Besides, the inner ring 71 and the outer ring 72 of the bearing 70 are deformed into an elliptic shape along the cam portion 83 of the rotation member 80. In this way, the bearing 70 is interposed between the cam portion 83 of the rotation member 80 and the external gear 50 in a state of being elliptically deformed, and thus the external gear 50 can be smoothly and elliptically deformed along with rotation of the rotation member 80.

[0053] The rotation member 80 is, as shown in FIG. 6 and FIG. 7, formed into a substantially cylindrical shape using a metal material and includes an annular portion 81, a coupling portion 82, and the cam portion 83.

[0054] The annular portion 81 is formed into an annular shape centred on the axis line S. The coupling portion 82 is formed as a U-shaped rib opened toward a radial center perpendicular to the axis line S on the inner side of the annular portion 81 and is coupled to the coupling piece 5c which forms a portion of the rotation shaft 5b. Furthermore, the coupling portion 82 is fragile so as to cut off transmission of a rotational force with the rotation shaft 5b when an overload occurs, and thus the coupling portion 82 may be partially formed by a resin material. The cam portion 83 is formed into an elliptic shape in which an outer peripheral surface of the cam portion 83 defines an elliptic shape having a major axis in a linear direction perpendicular to the axis line S, and the cam portion 83 exerts a cam action which causes elliptic deformation to the external gear 50.

[0055] Besides, the rotation shaft 5b of the electric motor 5 is coupled to the rotation member 80 to exert the rotation driving force; in addition, the cam portion 83 exerts the cam action to the external gear 50 by the rotation of the rotation member 80. In this way, the external gear 50 which is in a state of being meshed with the first internal gear 20 and the second internal gear 30 is elliptically deformed and a meshing position of the external gear 50 is continuously changed around the axis line S.

[0056] A relationship between the number of teeth Z1 of the external gear 50, the number of teeth Z2 of the first internal gear 20, and the number of teeth Z3 of the second internal gear 30 (Z3<Z2) in the above configuration is described. Here, when the external gear 50 which is interlocked with the rotation member 80 rotationally driven by the electric motor 5 is taken as input, the second internal gear 30 which is rotated integrally with the camshaft 2 is taken as output, and the first internal gear 20 which is rotated integrally with the housing rotor 10 is fixed to calculate a speed ratio i using a gluing method, i=1-(Z2/Z3) is established.

[0057] Besides, because the number of teeth Z3 of the second internal gear 30 is set to be smaller than the number of teeth Z2 of the first internal gear 20, the value of the speed ratio i is always negative. That is, a rotation direction of the output side is opposite to a rotation direction of the input side, and the rotation direction of the output side with respect to the rotation of the input side can be determined only according to a relationship of the number of teeth between the number of teeth Z2 of the first internal gear 20 and the number of teeth Z3 of the second internal gear 30.

[0058] In the embodiment, for example, the number of teeth Z1 of the external gear 50 is set to 200, the number of teeth Z2 of the first internal gear 20 is set to 202, and the number of teeth Z3 of the second internal gear 30 is set to 200. In this case, the speed ratio i=1-(202/200)=-0.01. That is, as a speed reduction mechanism, a rotation speed of the input side is reduced to 1/100 and output as a reverse rotation. Therefore, power saving and downsizing of the electric motor 5 can be achieved.

[0059] Next, operations when the valve timing change device M according to the first embodiment is applied to the engine 1 are described. First, when the valve timing of the exhaust valve is not changed, the electric motor 5 is driven and controlled so as to exert the rotation driving force to the rotation member 80 in a rotation direction the same as the rotation direction of the camshaft 2 at a rotation speed the same as the rotation speed of the camshaft 2. Therefore, the external gear 50 and the first internal gear 20 are locked at a position where they are mutually meshed, and the external gear 50 and the second internal gear 30 are locked at a position where they are mutually meshed. In this way, the camshaft 2 and the housing rotor 10 are rotated integrally around the axis line S along one direction (the R direction in FIG. 1).

[0060] When the valve timing of the exhaust valve is changed, the electric motor 5 is driven and controlled so as to exert the rotation driving force to the rotation member 80 in the direction the same as the direction of the camshaft 2 at a rotation speed different from the rotation speed of the camshaft 2. For example, if the electric motor 5 is driven and controlled so as to exert the rotation driving force to the rotation member 80 in the direction the same as the direction of the camshaft 2 at a rotation speed faster than the rotation speed of the camshaft 2, the rotation member 80 on the input side is relatively rotated with respect to the camshaft 2 along one direction around the axis line S (a CW direction in FIG. 1), and the second internal gear 30 on the output side is relatively rotated with respect to the first internal gear 20 along another direction being a reverse direction (a CCW direction in FIG. 1). That is, by relatively rotating the rotation member 80 in one direction (the CW direction), a rotation phase of the camshaft 2 is retarded with respect to the housing rotor 10, and the open/close timing of the exhaust valve is changed to the retarding side.

[0061] On the other hand, if the electric motor 5 is driven and controlled so as to exert the rotation driving force to the rotation member 80 in the direction the same as the direction of the camshaft 2 at a rotation speed slower than the rotation speed of the camshaft 2, the rotation member 80 on the input side is relatively rotated with respect to the camshaft 2 along another direction around the axis line S (the CCW direction in FIG. 1), and the second internal gear 30 on the output side is relatively rotated with respect to the first internal gear 20 along one direction being a reverse direction (the CW direction in FIG. 1). That is, by relatively rotating the rotation member 80 in another direction (the CCW direction), the rotation phase of the camshaft 2 is advanced with respect to the housing rotor 10, and the open/close timing of the exhaust valve is changed to the advancing side.

[0062] Here, the rotation member 80 is set to perform an advancing operation when the rotation driving force is exerted by the electric motor 5 at the rotation speed slower than the rotation speed of the camshaft 2 in the direction (the CW direction) the same as the rotation direction (the R direction) of the camshaft 2. Therefore, if the electric motor 5 is inoperative provisionally, by cogging torque of the electric motor 5, friction forces, alternating torque of the camshaft 2 or the like, the electric motor 5 functions similarly as in the case that the rotation driving force is exerted to the rotation member 80 at the rotation speed slower than the rotation speed of the camshaft 2 in the direction the same as the direction of the camshaft 2.

[0063] That is, the rotation member 80 is relatively rotated with respect to the camshaft 2 along another direction around the axis line S (the CCW direction in FIG. 1), the rotation phase of the camshaft 2 is advanced with respect to the housing rotor 10, and the open/close timing of the exhaust valve is changed to the advancing side. Besides, the advancing side contact portion 46 of the rotor 40 comes into contact with the advancing side stopper 11g of the housing rotor 10, and the open/close timing of the exhaust valve is maintained at the maximum advancing position.

[0064] In this way, the open/close timing of the exhaust valve is positioned at the maximum advancing position, and thus valve overlap at the time of starting the engine 1 can be reduced, and blow-by in which intake air escapes to the exhaust side can be prevented to maintain starting performance. That is, when the electric motor 5 is broke down, the failsafe function in the engine 1 can be ensured.

[0065] Furthermore, in the above valve timing change device M, the lubricant oil stored in an oil pan of the engine 1 is supplied to the camshaft 2 by an oil pump or the like, led into the second internal gear 30 through the oil passages 2c, 45, the through hole 41 and the oil passage 36, led to the outside of the housing rotor 10 through the opening portion 12a and the oil passages 37, 11f, and flows through the cover member 1a to return to the oil pan. In this way, a lubricant action is also carried out reliably, and thus wear and deterioration of the sliding region can be suppressed and the valve timing can be changed smoothly.

[0066] As described above, according to the valve timing change device M of the first embodiment, a conventional torsion spring serving for a failsafe function is not necessary, and thus simplification of structure, cost reduction, downsizing and the like can be achieved, and a failsafe function can be ensured in the camshaft 2 of the exhaust valve.

[0067] FIGS. 8-12 show a valve timing change device M2 according to the second embodiment of the disclosure, and configurations the same as the above-described first embodiment are added with the same symbols and the description is omitted. The valve timing change device M2 according to the second embodiment includes a housing rotor 110, a first internal gear 120, a second internal gear 130, a rotor 140 acting as a spacer member, an external gear 150, a snap ring 160, a bearing 170, a rotation member 180, and a bearing 190.

[0068] The housing rotor 110 includes a first housing 111 which is supported rotatably around the axis line S, and a second housing 112 which is bounded to the first housing 11 by screws b1.

[0069] The first housing 111 is formed into a substantially cylindrical shape using a metal material and includes a sprocket 11a, a cylindrical portion 11b, an inner peripheral surface 111c, an annular bottom wall surface 111d, an advancing side stopper 111g, a retarding side stopper 111h, and a plurality of screw holes 11j for the screws b1 to be screwed in.

[0070] The inner peripheral surface 111c is slidably in contact with an outer peripheral surface 131a of the second internal gear 130 so that the first housing 111 is rotatably supported around the axis line S. The bottom wall surface 111d is slidably in contact with an outer periphery region of a joining surface 134 of the second internal gear 130 so that the first housing 111 is positioned in a direction of the axis line S. The advancing side stopper 111g comes into contact with an advancing side contact portion 144 of the rotor 140 to position the camshaft 2 at a maximum advancing position. The retarding side stopper 111h comes into contact with a retarding side contact portion 145 of the rotor 140 to position the camshaft 2 at a maximum retarding position.

[0071] The second housing 112 is formed into a substantially disc shape using a metal material and includes a cylindrical portion 112a centered on the axis line S, an annular inner wall surface 112b, an opening portion 112c, and a plurality of circular holes 112d through which the screws b1 pass.

[0072] The cylindrical portion 112a is formed in a manner that the bearing 190 which rotatably supports the rotation member 180 is fitted to an inner peripheral surface of the cylindrical portion 112a. The annular inner wall surface 112b is arranged adjacent to the bearing 190 which is fitted to a cylindrical portion 181 of the rotation member 180 and serves to restrain the bearing 190 from falling in the direction of the axis line S. The opening portion 112c leaves a gap around the rotation member 180 to expose the cylindrical portion 181 and a coupling portion 182 which are end portions of the rotation member 180.

[0073] Besides, after the second internal gear 130 into which the rotor 140 is fitted, the first internal gear 120, the external gear 150, the snap ring 160 and the rotation member 180 into which the bearings 170, 190 are fitted are assembled with respect to the first housing 111, the second housing 112 is combined with the first housing 111 by the screws b1, and thereby the housing rotor 110 which is rotated around the axis line S is formed.

[0074] Here, the housing rotor 110 is rotatably supported around the axis line S via the second internal gear 130, and thus the housing rotor 110, the external gear 150, and the first internal gear 120 can be positioned using the second internal gear 130 fixed to the camshaft 2 as a reference. In addition, a configuration including the first housing 111 and the second housing 112 is employed as the housing rotor 110, the above various components are accommodated in the first housing 111 and the second housing 112 is combined with respect to the first housing 111, and thereby the valve timing change device M2 can be easily assembled.

[0075] The first internal gear 120 is, as shown in FIG. 11 and FIG. 12, formed into a substantially annular shape by, for example, forging using a metal material, and includes a cylindrical portion 121 which is centered on the axis line S, a row of teeth 122, a flange portion 123, and a plurality of circular holes 124 through which the screws b1 pass.

[0076] The cylindrical portion 121 is formed to have an outer diameter dimension to be fitted to the inner peripheral surface 111c of the first housing 111. The row of teeth 122 has the number of teeth Z22 and is formed into an annular arrangement centered on the axis line S on an inner peripheral surface of the cylindrical portion 121. The row of teeth 122 is meshed with substantially one half of a front region of a row of teeth 151 of the external gear 150 in the direction of the axis line S. Here, "front" is the left of the direction of the axis line S in FIG. 10, that is, a side where the electric motor 5 is arranged. The flange portion 123 is formed into a flat plate shape perpendicular to the axis line S and is assembled by being clamped between the first housing 111 and the second housing 112.

[0077] That is, the first internal gear 120 is fixed by the screws b1 to be meshed with the external gear 150 in a manner of rotating integrally with the housing rotor 110. In addition, the first internal gear 120 is formed separately from the housing rotor 110 and later mounted to the housing rotor 110, and thus compared with a case in which the first internal gear 120 is formed integrally with the housing rotor 110, manufacturing is facilitated and productivity is improved.

[0078] The second internal gear 130 is, as shown in FIG. 11 and FIG. 12, formed into a cylindrical shape with a bottom by, for example, forging using a metal material, and includes a cylindrical portion 131, a row of teeth 132, a bottom wall surface 133, the joining surface 134, a through hole 135, a cylindrical fitting portion 136, and a positioning hole 137.

[0079] The cylindrical portion 131 defines the outer peripheral surface 131a centered on the axis line S to be slidably in contact with the inner peripheral surface 111c of the first housing 111.

[0080] The row of teeth 132 has the number of teeth Z23 smaller than the number of teeth Z22 of the first internal gear 120 and is formed into an annular arrangement centered on the axis line S on an inner peripheral surface of the cylindrical portion 131. The row of teeth 132 is meshed with substantially one half of a back region of the row of teeth 151 of the external gear 150 in the direction of the axis line S. Here, "back" is the right of the direction of the axis line S in FIG. 10, that is, a side where the camshaft 2 is arranged. The bottom wall surface 133 is formed as a flat surface perpendicular to the axis line S and functions as a bearing surface of a fastening bolt b2. The joining surface 134 is formed into a flat surface parallel to the bottom wall surface 133 so that the rotor 140 is joined. The through hole 135 is formed into a circular shape centered on the axis line S for the fastening bolt b2 to pass through. The cylindrical fitting portion 136 defines a portion of the through hole 135 and is formed into a cylindrical shape centered on the axis line S to be fitted into a fitting hole 141 of the rotor 140. The positioning hole 137 is formed so that a positioning pin P fixed to the fitting hole 2d of the camshaft 2 is fitted and the positioning hole 137 serves to determine an angular position around the axis line S.

[0081] The rotor 140 is formed into a substantially flat plate shape using a metal material and includes, as shown in FIG. 11 and FIG. 12, the fitting hole 141, a fitting concave portion 142, a positioning hole 143, the advancing-side contact portion 144, and the retarding-side contact portion 145.

[0082] The fitting hole 141 is formed into a circular shape centered on the axis line S so that the cylindrical fitting portion 136 of the second internal gear 130 is fitted to the fitting hole 141. The fitting concave portion 142 is formed into a circular shape centered on the axis line S so that the fitting portion 2a of the camshaft 2 is fitted fitting concave portion 142. The positioning hole 143 is formed so that the positioning pin P fixed to the fitting hole 2d of the camshaft 2 is fitted and the positioning hole 143 serves to determine the position around the axis line S. The advancing-side contact portion 144 detachably comes into contact with the advancing-side stopper 111g of the first housing 111. The retarding-side contact portion 145 detachably comes into contact with the retarding-side stopper 111h of the first housing 111.

[0083] Besides, the rotor 140 is assembled with the second internal gear 130 in advance by fitting the cylindrical fitting portion 136 to the fitting hole 141. Then, in a state that the first housing 111 is rotatably mounted to the second internal gear 130, the rotor 140 is brought close to the camshaft 2, the positioning pin P is fitted into the positioning holes 143 and 137, and the fitting portion 2a is joined to the fitting concave portion 142. In this way, the rotor 140 is joined to the camshaft 2. Thereafter, the fastening bolt b2 is screwed into the screw hole 2b through the through hole 135, and thereby the second internal gear 130 is fixed to the camshaft 2 via the rotor 140.

[0084] In addition, the rotor 140 is positioned at the maximum advancing position by the advancing side contact portion 144 coming into contact with the advancing side stopper 111g and is positioned at the maximum retarding position by the retarding side contact portion 145 coming into contact with the retarding side stopper 111h. That is, for the camshaft 2, a relative rotation range with respect to the housing rotor 110 is regulated via the rotor 140. In this way, a range of the rotation phase in which the valve timing can be changed, that is, an adjustable angle range from the maximum retarding position to the maximum advancing position can be regulated to a desired range.

[0085] Here, by employing the rotor 140 acting as a spacer member, when the shape of the fitting portion 2a of the camshaft 2 differs according to specification of the engine, the valve timing change device M2 can be applied to various engines simply by setting the rotor 140 corresponding to various camshafts 2.

[0086] The external gear 150 is, as shown in FIG. 11 and FIG. 12, formed into an annular shape with rigidity using a metal material and includes the row of teeth 151, an inner peripheral surface 152, an annular bottom wall surface 153, and an annular convex portion 154.

[0087] The row of teeth 151 is formed into an annular arrangement centered on the axis line S and has the number of teeth Z21 different from the number of teeth Z22 of the first internal gear 120. Substantially one half of the front region in the direction of the axis line S is meshed with the row of teeth 122 of the first internal gear 120, and substantially one half of the back region in the direction of the axis line S is meshed with the row of teeth 132 of the second internal gear 130. The inner peripheral surface 152 is formed into a cylindrical surface centered on the axis line S so that the outer ring 172 of the bearing 170 fitted to the rotation member 180 is fitted to the inner peripheral surface 152. The annular bottom wall surface 153 brings an end surface of the outer ring 172 of the bearing 170 fitted to the rotation member 180 into contact to determine the position in the direction of the axis line S. The annular convex portion 154 is slidably in contact with the bottom wall surface 133 of the second internal gear 130 and serves to separate the back of the row of teeth 151 from the bottom wall surface 133 by a predetermined amount. Furthermore, in the embodiment, a case that the number of teeth Z21 is different from the number of teeth Z22 is shown, but the disclosure is not limited to this, and the number of teeth Z21 may be the same as the number of teeth Z22 as long as a condition that the number of teeth Z23 is smaller than the number of teeth Z22 is satisfied.

[0088] Besides, the external gear 150 is directly meshed with the first internal gear 120 in a region and is directly meshed with the second internal gear 130 in a region by receiving an eccentricity action of an eccentric portion 183 of the rotation member 180 via the bearing 170.

[0089] The snap ring 160 is formed into a substantially C shape using a metal material and is fitted into an annular groove 185 of the rotation member 180 to regulate falling of the bearing 170 which is fitted to the eccentric portion 183 of the rotation member 180.

[0090] The bearing 170 is a radial bearing having rigidity and includes an inner ring 171, an outer ring 172, and a plurality of rolling bodies 173 arranged between the inner ring 171 and the outer ring 172 and held by a retainer. Besides, the bearing 170 is interposed between the eccentric portion 183 of the rotation member 180 and the inner peripheral surface 152 of the external gear 150 to rotatably support the external gear 150.

[0091] The rotation member 180 is, as shown in FIG. 11 and FIG. 12, formed into a substantially cylindrical shape using a metal material and includes the cylindrical portion 181, the coupling portion 182, the eccentric portion 183, a flange portion 184, and the annular groove 185.

[0092] The cylindrical portion 181 defines an outer peripheral surface centred on the axis line S so that an inner ring 191 of the bearing 190 is fitted to the cylindrical portion 181. The coupling portion 182 is formed as a U-shaped groove opened toward a radial center perpendicular to the axis line S on the inner side of the cylindrical portion 181 and is coupled to a coupling piece 5c which forms a portion of the rotation shaft 5b. The eccentric portion 183 defines an outer peripheral surface centered on an axis line which is radially shifted from the axis line S by a predetermined amount so that the inner ring 171 of the bearing 170 is fitted to the eccentric portion 183. That is, the eccentric portion 183 is fitted into the inner side of the external gear 150 via the bearing 170. The flange portion 184 is formed to have an outer diameter larger than the outer diameter of the cylindrical portion 181 and the eccentric portion 183 and positions the bearings 170, 190 in the direction of the axis line S. The annular groove 185 is formed in a manner that the snap ring 160 is mounted.

[0093] Besides, the rotation shaft 5a of the electric motor 5 is coupled to the rotation member 180 to exert the rotation driving force; in addition, the eccentric portion 183 exerts an eccentricity action of eccentrically rotating the external gear 150 and meshing the external gear 150 to the first internal gear 120 and the second internal gear 130 by rotating the rotation member 180 around the axis line S. In this way, the external gear 150 which is in a state of being meshed with the first internal gear 120 and the second internal gear 130 is eccentrically rotated and a meshing position of the external gear 150 is continuously changed around the axis line S.

[0094] The bearing 190 is a radial bearing having rigidity and includes the inner ring 191, the outer ring 192, and a plurality of rolling bodies 193 arranged between the inner ring 191 and the outer ring 192 and held by a retainer. Besides, the bearing 190 is interposed between the cylindrical portion 181 of the rotation member 180 and the cylindrical portion 112a of the housing rotor 110 to rotatably support the rotation member 180 around the axis line S with respect to the housing rotor 110.

[0095] A relationship between the number of teeth Z21 of the external gear 150, the number of teeth Z22 of the first internal gear 120, and the number of teeth Z23 of the second internal gear 130 (Z23<Z22) in the above configuration is described. Here, when the external gear 150 which is interlocked with the rotation member 180 rotationally driven by the electric motor 5 is taken as input, the second internal gear 130 which is rotated integrally with the camshaft 2 is taken as output, and the first internal gear 120 which is rotated integrally with the housing rotor 110 is fixed to calculate a speed ratio i using a gluing method, i=1-(Z22/Z23) is established.

[0096] Besides, because the number of teeth Z23 of the second internal gear 130 is set to be smaller than the number of teeth Z22 of the first internal gear 120, the value of the speed ratio i is always negative. That is, a rotation direction of the output side is opposite to a rotation direction of the input side, and the rotation direction of the output side with respect to the rotation of the input side can be determined only according to a relationship of the number of teeth between the number of teeth Z22 of the first internal gear 120 and the number of teeth Z23 of the second internal gear 130.

[0097] In the embodiment, for example, the number of teeth Z21 of the external gear 150 is set to 60, the number of teeth Z22 of the first internal gear 120 is set to 61, and the number of teeth Z23 of the second internal gear 130 is set to 60. In this case, the speed ratio i=1-(61/60)=-0.0166. That is, as a speed reduction mechanism, a rotation speed of the input side is reduced to about 1/60 and output as a reverse rotation. Therefore, power saving and downsizing of the electric motor 5 can be achieved.

[0098] Next, operations when the valve timing change device M2 according to the second embodiment is applied to the engine 1 are described. First, when the valve timing of the exhaust valve is not changed, the electric motor 5 is driven and controlled so as to exert the rotation driving force to the rotation member 180 in a rotation direction the same as a rotation direction of the camshaft 2 at a rotation speed the same as a rotation speed of the camshaft 2. Therefore, the external gear 150 and the first internal gear 120 are locked at a position where they are mutually meshed, and the external gear 150 and the second internal gear 130 are locked at a position where they are mutually meshed. In this way, the camshaft 2 and the housing rotor 110 are rotated integrally around the axis line S along one direction (the R direction in FIG. 1).

[0099] When the valve timing of the exhaust valve is changed, the electric motor 5 is driven and controlled so as to exert the rotation driving force to the rotation member 180 in the rotation direction the same as the rotation direction of the camshaft 2 at a rotation speed different from the rotation speed of the camshaft 2. For example, if the electric motor 5 is driven and controlled so as to exert the rotation driving force to the rotation member 180 in the rotation direction the same as the rotation direction of the camshaft 2 at a rotation speed faster than the rotation speed of the camshaft 2, the rotation member 180 on the input side is relatively rotated with respect to the camshaft 2 in one direction around the axis line S (the CW direction in FIG. 1), and the second internal gear 130 on the output side is relatively rotated with respect to the first internal gear 120 in another direction being a reverse operation (the CCW direction in FIG. 1). That is, by relatively rotating the rotation member 180 in one direction (the CW direction), a rotation phase of the camshaft 2 is retarded with respect to the housing rotor 110, and the open/close timing of the exhaust valve is changed to the retarding side.

[0100] On the other hand, if the electric motor 5 is driven and controlled so as to exert the rotation driving force to the rotation member 180 in the direction the same as the direction of the camshaft 2 at a rotation speed slower than the rotation speed of the camshaft 2, the rotation member 180 on the input side is relatively rotated with respect to the camshaft 2 in another direction around the axis line S (the CCW direction in FIG. 1), and the second internal gear 130 on the output side is relatively rotated with respect to the first internal gear 120 in one direction being a reverse direction (the CW direction in FIG. 1). That is, by relatively rotating the rotation member 180 in another direction (the CCW direction), the rotation phase of the camshaft 2 is advanced with respect to the housing rotor 110, and the open/close timing of the exhaust valve is changed to the advancing side.

[0101] Here, the rotation member 180 is set to perform an advancing operation when the rotation driving force is exerted by the electric motor 5 at the rotation speed slower than the rotation speed of the camshaft 2 in the direction (the CW direction) the same as the rotation direction (the R direction) of the camshaft 2. Therefore, if the electric motor 5 is inoperative, by cogging torque of the electric motor 5, friction forces, alternating torque of the camshaft 2, or the like, the electric motor 5 functions similarly as in the case of exerting the rotation driving force to the rotation member 180 at the rotation speed slower than the rotation speed of the camshaft 2 in the direction the same as the direction of the camshaft 2.

[0102] That is, the rotation member 180 is relatively rotated with respect to the camshaft 2 along another direction around the axis line S (the CCW direction in FIG. 1), and the rotation phase of the camshaft 2 is advanced with respect to the housing rotor 110, and the open/close timing of the exhaust valve is changed to the advancing side. Besides, the advancing side contact portion 144 of the rotor 140 comes into contact with the advancing side stopper 111g of the housing rotor 110, and the open/close timing of the exhaust valve is maintained at the maximum advancing position.

[0103] In this way, because the open/close timing of the exhaust valve is positioned at the maximum advancing position, valve overlap at the time of starting the engine 1 can be reduced, and blow-by in which intake air escapes to the exhaust side can be prevented to maintain the starting performance. That is, when the electric motor 5 is broke down, the failsafe function in the engine 1 can be ensured.

[0104] Furthermore, in the above valve timing change device M2, a supplying route of lubricant oil is arranged similar to the first embodiment, and thereby the lubricant oil which is stored in an oil pan of the engine 1 can be supplied into the housing rotor 110 through the camshaft 2, led to the outside of the housing rotor 110, and return to the oil pan through the cover member 1a. Thereby, a lubricant action is also carried out reliably, and thus wear and deterioration of the sliding region can be suppressed and the valve timing can be changed smoothly.

[0105] As described above, according to the valve timing change device M2 of the second embodiment, a conventional torsion spring serving for a failsafe function is not necessary, and thus simplification of structure, cost reduction, downsizing and the like can be achieved, and a failsafe function can be ensured in the camshaft 2 of the exhaust valve.

[0106] FIGS. 13-17 show a valve timing change device M3 according to the third embodiment of the disclosure, and configurations the same as the above-described first embodiment or second embodiment are added with the same symbols and the description is omitted.

[0107] The valve timing change device M3 according to the third embodiment includes a housing rotor 210, a first internal gear 220, a second internal gear 230, a rotor 240 acting as a spacer member, an external gear 250, planetary gears 260, a carrier 270, a bearing 280, and a support member 290.

[0108] The housing rotor 210 includes a first housing 211 which is supported rotatably around the axis line S, and a second housing 212 which is combined to the first housing 211 by screws b1. The first housing 211 is formed into a substantially cylindrical shape using a metal material and includes a sprocket 11a, a cylindrical portion 11b, an inner peripheral surface 211c, an annular bottom wall surface 211d, an advancing side stopper 211g, a retarding side stopper 211h, and a plurality of screw holes 11j for the screws b1 to be screwed in.

[0109] The inner peripheral surface 211c is slidably in contact with an outer peripheral surface 231a of the second internal gear 230 so that the first housing 211 is rotatably supported around the axis line S. The bottom wall surface 211d is slidably in contact with an outer periphery region of a joining surface 234 of the second internal gear 230 so that the first housing 211 is positioned in a direction of the axis line S. The advancing side stopper 211g comes into contact with an advancing side contact portion 244 of the rotor 240 to position the camshaft 2 at a maximum advancing position. The retarding side stopper 211h comes into contact with a retarding side contact portion 245 of the rotor 240 to position the camshaft 2 at a maximum retarding position.

[0110] The second housing 212 is formed into a substantially disc shape using a metal material and includes a cylindrical opening portion 212a centred on the axis line S, and a plurality of circular holes 212b through which the screws b1 pass. The opening portion 212a leaves a gap around the external gear 250 to expose an annular portion 254 and a coupling portion 255 which are end portions of the rotation member which is formed integrally with the external gear 250.

[0111] Besides, after the second internal gear 230 to which the rotor 240 is fitted, the first internal gear 220, the planetary gears 260 held by the carrier 270, and the external gear 250 into which the bearing 280 is fitted are assembled with respect to the first housing 211, and the support member 290 is assembled in the bearing 280 and the second internal gear 230, the second housing 212 is combined to the first housing 211 by the screws b1, and thereby the housing rotor 210 which is rotated around the axis line S is formed.

[0112] Here, the housing rotor 210 is rotatably supported around the axis line S via the second internal gear 230, and thus the housing rotor 210, the external gear 250, and the first internal gear 220 can be positioned using the second internal gear 230 fixed to the camshaft 2 as a reference. In addition, a configuration including the first housing 211 and the second housing 212 is employed as the housing rotor 210, the above various components are accommodated in the first housing 211 and the second housing 212 is combined with respect to the first housing 211, and thereby the valve timing change device M3 can be easily assembled.

[0113] The first internal gear 220 is, as shown in FIG. 16 and FIG. 17, formed into a substantially annular shape by, for example, forging using a metal material, and includes a cylindrical portion 221 which is centered on the axis line S, a row of teeth 222, a flange portion 223, a plurality of circular holes 224 through which the screws b1 pass.

[0114] The cylindrical portion 221 is formed to have an outer diameter dimension to be fitted into the inner peripheral surface 211c of the first housing 211. The row of teeth 222 has the number of teeth Z32 and is formed into an annular arrangement centered on the axis line S on an inner peripheral surface of the cylindrical portion 221. The row of teeth 222 is meshed with substantially one half of a front region of a row of teeth 261 of three planetary gears 260 in the direction of the axis line S. Here, "front" is the left of the direction of the axis line S in FIG. 15, that is, a side where the electric motor 5 is arranged. The flange portion 223 is formed into a flat plate shape perpendicular to the axis line S and is assembled by being clamped between the first housing 211 and the second housing 212.

[0115] That is, the first internal gear 220 is fixed by the screws b1 to be rotated integrally with the housing rotor 210 and is meshed with the external gear 250 via the planetary gear 260. In addition, the first internal gear 220 is formed separately from the housing rotor 210 and later mounted to the housing rotor 210, and thus compared with a case in which the first internal gear 220 is formed integrally with the housing rotor 210, manufacturing is facilitated and productivity is improved.

[0116] The second internal gear 230 is, as shown in FIG. 16 and FIG. 17, formed into a cylindrical shape with bottom by, for example forging using a metal material and includes a cylindrical portion 231, a row of teeth 232, a bottom wall surface 233, the joining surface 234, a through hole 235, a cylindrical fitting portion 236, a positioning hole 237, and a fitting concave portion 238.

[0117] The cylindrical portion 231 defines the outer peripheral surface 231a centered on the axis line S to be slidably in contact with the inner peripheral surface 211c of the first housing 211. The row of teeth 232 has the number of teeth Z33 smaller than the number of teeth Z32 of the first internal gear 220 and is formed into an annular arrangement centered on the axis line S on an inner peripheral surface of the cylindrical portion 231. The row of teeth 232 is meshed with substantially one half of a back region of a row of teeth 261 of the three planetary gears 260 in the direction of the axis line S. Here, "back" is the right of the direction of the axis line S in FIG. 15, that is, a side where the camshaft 2 is arranged. The bottom wall surface 233 is formed as a flat surface perpendicular to the axis line S and faces end surfaces of the carrier 270 and the planetary gears 260 with a gap disposed therebetween and receives an annular step portion 294 of the support member 290. The joining surface 234 is formed into a flat surface parallel to the bottom wall surface 233 so that the rotor 240 is joined. The through hole 235 is formed into a circular shape centred on the axis line S for the fastening bolt b2 to pass through. The cylindrical fitting portion 236 defines a portion of the through hole 235 and is formed into a cylindrical shape centered on the axis line S to be fitted into a fitting hole 241 of the rotor 240. The positioning hole 237 is formed so that the positioning pin P fixed to the fitting hole 2d of the camshaft 2 is fitted to the positioning hole 237, and the positioning hole 237 serves to determine an angular position around the axis line S. The fitting concave portion 238 is formed into a circular shape centered on the axis line S so that a cylindrical fitting portion 293 of the support member 290 is fitted to the fitting concave portion 238.

[0118] The rotor 240 is formed into a substantially flat plate shape using a metal material and includes, as shown in FIG. 16 and FIG. 17, the fitting hole 241, a fitting concave portion 242, a positioning hole 243, the advancing side contact portion 244, and the retarding side contact portion 245.

[0119] The fitting hole 241 is formed into a circular shape centered on the axis line S so that the cylindrical fitting portion 236 of the second internal gear 230 is fitted to the fitting hole 241. The fitting concave portion 242 is formed into a circular shape centered on the axis line S so that the fitting portion 2a of the camshaft 2 is fitted to the fitting concave portion 242. The positioning hole 243 is formed so that the positioning pin P fixed to the fitting hole 2d of the camshaft 2 is fitted, and the positioning hole 243 serves to determine the position around the axis line S. The advancing side contact portion 244 detachably comes into contact with the advancing side stopper 211g of the first housing 211. The retarding side contact portion 245 detachably comes into contact with the retarding side stopper 211h of the first housing 211.

[0120] The external gear 250 is, as shown in FIG. 16 and FIG. 17, formed into an annular shape with rigidity using a metal material and includes a row of teeth 251, an inner peripheral surface 252, an annular bottom wall surface 253, the annular convex portion 254, and the coupling portion 255.

[0121] The row of teeth 251 is formed into an annular arrangement centred on the axis line S and has the number of teeth Z31 different from the number of teeth Z32 of the first internal gear 220 and the number of teeth Z33 of the second internal gear 230. The row of teeth 251 is meshed with the row of teeth 261 of the three planetary gears 260. That is, the external gear 250 is indirectly meshed with the first internal gear 220 and the second internal gear 230 at three regions via the three planetary gears 260. The inner peripheral surface 252 is formed into a cylindrical surface centred on the axis line S so that an outer ring 282 of the bearing 280 fitted to the support member 290 is fitted to the inner peripheral surface 252. The annular bottom wall surface 253 brings an end surface of the outer ring 282 of the bearing 280 fitted to the support member 290 into contact to determine the position in the direction of the axis line S. The annular portion 254 is formed into a cylindrical shape in front of the row of teeth 251 in the direction of the axis line S and functions as a rotation member. That is, the rotation member is formed integrally with the external gear 250 as one portion of the external gear 250. The coupling portion 255 is formed as a notched groove in which an end portion of the annular portion 254 is notched in a radial direction perpendicular to the axis line S and is coupled to the coupling piece 5c which forms one portion of the rotation shaft 5b.

[0122] The planetary gear 260 is, as shown in FIG. 16 and FIG. 17, formed into a column shape having rigidity using a metal material and includes the row of teeth 261 and a bearing hole 262. The row of teeth 261 is formed into an annular arrangement centered on the bearing hole 262 and has the number of teeth Z34. Substantially one half of a front region in the direction of the axis line S is meshed with the row of teeth 222 of the first internal gear 220, and substantially one half of a back region in the direction of the axis line S is meshed with the row of teeth 232 of the second internal gear 230. The bearing hole 262 is formed into a cylindrical shape so that a support shaft 273 of the carrier 270 is slidably fitted.

[0123] The carrier 270 is formed using a metal material and includes, as shown in FIG. 16 and FIG. 17, a first ring plate 271, a second ring plate 272 having three circular holes, and three support shafts 273 fixed to the first ring plate 271. Besides, the planetary gears 260 are fitted to the three support shafts 273 respectively, and end portions of the three support shafts 273 are caulked through the circular holes of the second ring plate 272. Thereby, the carrier 270 is assembled and the planetary gears 260 are rotatably supported. Moreover, the planetary gears 260 are rotatably supported by the support shafts 273 of the carrier 270 and are revolvably supported around the axis line S via the carrier 270.

[0124] The bearing 280 is a radial bearing having rigidity and includes an inner ring 281, the outer ring 282, and a plurality of rolling bodies 283 arranged between the inner ring 281 and the outer ring 282 and held by a retainer. Besides, the bearing 280 is interposed between a cylindrical portion 291 of the support member 290 and the inner peripheral surface 252 of the external gear 250 to rotatably support the external gear 250 with respect to the support member 290.

[0125] The support member 290 is, as shown in FIG. 16 and FIG. 17, formed into a substantially cylindrical shape using a metal material and includes the cylindrical portion 291, a flange portion 292, the cylindrical fitting portion 293, the annular step portion 294, and a through hole 295.

[0126] The cylindrical portion 291 is formed into a cylindrical shape centred on the axis line S to fit the inner ring 281 of the bearing 280. The flange portion 292 has an outer diameter larger than the outer diameter of the cylindrical portion 291 and functions to clamp the bearing 280 fitted to the cylindrical portion 291 in cooperation with the annular bottom wall surface 253 of the external gear 250. The cylindrical fitting portion 293 is formed into a cylindrical shape centred on the axis line S to be fitted to the fitting concave portion 238 of the second internal gear 230. The annular step portion 294 comes into contact with the bottom wall surface 233 of the second internal gear 230 and functions to clamp the rotor 240 and the second internal gear 230 in cooperation with the fitting portion 2a. The through hole 295 is formed into a circular shape centred on the axis line S for the fastening bolt b2 to pass through.

[0127] In the above configuration, the rotor 240 is assembled with respect to the second internal gear 230 in advance by fitting the cylindrical fitting portion 236 to the fitting hole 241. Then, in a state that the first housing 211 is rotatably mounted to the second internal gear 230, the rotor 240 is brought close to the camshaft 2, the positioning pin P is fitted into the positioning holes 243, 237, and the fitting portion 2a is joined to the fitting concave portion 242. Thereby, the rotor 240 is joined to the camshaft 2. Thereafter, the cylindrical fitting portion 293 of the support member 290 is fitted to the fitting concave portion 238 of the second internal gear 230, and the fastening bolt b2 is screwed into the screw hole 2b through the through holes 295, 235, thereby fixing the second internal gear 230 to the camshaft 2 via the rotor 240.

[0128] In addition, the rotor 240 is positioned at the maximum advancing position by the advancing side contact portion 244 coming into contact with the advancing side stopper 211g and is positioned at the maximum retarding position by the retarding side contact portion 245 coming into contact with the retarding side stopper 211h. That is, for the camshaft 2, a relative rotation range with respect to the housing rotor 210 is regulated via the rotor 240. In this way, a range of the rotation phase in which the valve timing can be changed, that is, an adjustable angle range from the maximum retarding position to the maximum advancing position can be regulated to a desired range.

[0129] Here, by employing the rotor 240 acting as a spacer member, when the shape of the fitting portion 2a of the camshaft 2 differs according to specification of the engine, the valve timing change device M3 can be applied to various engines simply by setting the rotor 240 corresponding to various camshafts 2.

[0130] A relationship between the number of teeth Z31 of the external gear 250, the number of teeth Z32 of the first internal gear 220, the number of teeth Z33 of the second internal gear 230 (Z33<Z32), and the number of teeth Z34 of the planetary gear 260 in the above configuration is described. Here, when the external gear 250 which is rotationally driven by the electric motor 5 is taken as input, the second internal gear 230 which is rotated integrally with the camshaft 2 is taken as output, and the first internal gear 220 which is rotated integrally with the housing rotor 210 is fixed to calculate a speed ratio i using a gluing method, i=[1-(Z32/Z33)]/[1+(Z32/Z31)] is established.

[0131] Besides, because the number of teeth Z33 of the second internal gear 230 is set to be smaller than the number of teeth Z32 of the first internal gear 220, the value of the speed ratio i is always negative. That is, a rotation direction of the output side is opposite to a rotation direction of the input side, and the rotation direction of the output side with respect to the rotation of the input side can be determined only according to a relationship of the number of teeth between the number of teeth Z32 of the first internal gear 220 and the number of teeth Z33 of the second internal gear 230.

[0132] In the embodiment, for example, the number of teeth Z31 of the external gear 250 is set to 27, the number of teeth Z32 of the first internal gear 220 is set to 63, the number of teeth Z33 of the second internal gear 230 is set to 60, and the number of teeth Z34 of the planetary gear 260 is set to 18. In this case, the speed ratio i=1-(63/60)/[1+(63/27)]=-0.015. That is, as a speed reduction mechanism, a rotation speed of the input side is reduced to about 1/66.7 and output as a reverse rotation. Therefore, power saving and downsizing of the electric motor 5 can be achieved.

[0133] Next, operations when the valve timing change device M3 according to the first embodiment is applied to the engine 1 are described. First, when the valve timing of the exhaust valve is not changed, the electric motor 5 is driven and controlled so as to exert the rotation driving force to the external gear 250 in a rotation direction the same as a rotation direction of the camshaft 2 at a rotation speed the same as a rotation speed of the camshaft 2. Therefore, the external gear 250 and the first internal gear 220 are locked via the planetary gears 260 at a position where they are mutually meshed, and the external gear 250 and the second internal gear 230 are locked via the planetary gears 260 at a position where they are mutually meshed. In this way, the camshaft 2 and the housing rotor 210 are rotated integrally around the axis line S along one direction (the R direction in FIG. 1).

[0134] When the valve timing of the exhaust valve is changed, the electric motor 5 is driven and controlled so as to exert the rotation driving force to the external gear 250 in a direction the same as the direction of the camshaft 2 at a rotation speed different from the rotation speed of the camshaft 2. For example, if the electric motor 5 is driven and controlled so as to exert the rotation driving force to the external gear 250 in the direction the same as the direction of the camshaft 2 at a rotation speed faster than the rotation speed of the camshaft 2, the external gear 250 of the input side is relatively rotated with respect to the camshaft 2 in one direction around the axis line S (the CW direction in FIG. 1), and the second internal gear 230 of the output side is relatively rotated with respect to the first internal gear 220 in another direction being a reverse direction (the CCW direction in FIG. 1). That is, by relatively rotating the external gear 250 in one direction (the CW direction), a rotation phase of the camshaft 2 is retarded with respect to the housing rotor 210, and the open/close timing of the exhaust valve is changed to the retarding side.

[0135] On the other hand, if the electric motor 5 is driven and controlled so as to exert the rotation driving force to the external gear 250 in the direction the same as the direction of the camshaft 2 at a rotation speed slower than the rotation speed of the camshaft 2, the external gear 250 of the input side is relatively rotated with respect to the camshaft 2 in another direction around the axis line S (the CCW direction in FIG. 1), and the second internal gear 230 of the output side is relatively rotated with respect to the first internal gear 220 in one direction being a reverse direction (the CW direction in FIG. 1). That is, by relatively rotating the external gear 250 in another direction (the CCW direction), the rotation phase of the camshaft 2 is retarded with respect to the housing rotor 210, and the open/close timing of the exhaust valve is changed to the advancing side.

[0136] Here, the external gear 250 is set to perform an advancing operation when the rotation driving force is exerted by the electric motor 5 at the rotation speed slower than the rotation speed of the camshaft 2 in the direction (the CW direction) the same as the rotation direction (the R direction) of the camshaft 2. Therefore, if the electric motor 5 is inoperative, by cogging torque of the electric motor 5, friction forces, alternating torque of the camshaft 2, or the like, the electric motor 5 functions similarly as in the case that the rotation driving force is exerted to the external gear 250 at the rotation speed slower than the rotation speed of the camshaft 2 in the direction the same as the direction of the camshaft 2.

[0137] That is, the external gear 250 is relatively rotated with respect to the camshaft 2 in another direction around the axis line S (the CCW direction in FIG. 1), the rotation phase of the camshaft 2 is advanced with respect to the housing rotor 210, and the open/close timing of the exhaust valve is changed to the advancing side. Besides, the advancing side contact portion 244 of the rotor 240 comes into contact with the advancing side stopper 211g of the housing rotor 210, and the open/close timing of the exhaust valve is maintained at the maximum advancing position.

[0138] In this way, because the open/close timing of the exhaust valve is positioned at the maximum advancing position, valve overlap at the time of starting the engine 1 can be reduced, and blow-by in which intake air escapes to the exhaust side can be prevented to maintain starting performance. That is, when the electric motor 5 is broke down, the failsafe function in the engine 1 can be ensured.

[0139] Furthermore, in the above valve timing change device M3, a supplying route of lubricant oil is also arranged similar to the first embodiment, and thereby lubricant oil stored in an oil pan of the engine 1 can be supplied into the housing rotor 210 through the camshaft 2, led to the outside of the housing rotor 210, and return to the oil pan through the cover member 1a. Thereby, a lubricant action is also carried out reliably, and thus wear and deterioration of the sliding region can be suppressed and the valve timing can be changed smoothly.

[0140] As described above, according to the valve timing change device M3 of the third embodiment, a conventional torsion spring serving for a failsafe function is not necessary, and thus simplification of structure, cost reduction, downsizing and the like can be achieved, and a failsafe function can be ensured in the camshaft 2 of the exhaust valve.

[0141] In the above embodiment, as the speed reduction mechanism, a wave gear type speed reduction mechanism including the first internal gear 20, the second internal gear 30, and the external gear 50, a composite hypocycloid speed reduction mechanism including the first internal gear 120, the second internal gear 130, and the external gear 150, and a magical planetary gear speed reduction mechanism including the first internal gear 220, the second internal gear 230, the external gear 250, and the planetary gear 260 are shown, but the disclosure is not limited hereto and the disclosure can also be employed in a pin gear speed reduction mechanism, other reduction mechanisms, and the like.

[0142] In the above embodiment, two-part housing rotors 10, 110, 210 are shown as the housing rotor, but the disclosure is not limited hereto, and housing rotors of other forms may also be employed. In addition, in the first embodiment to the third embodiment, cases in which the bearings 70, 170, 190, 280 are employed are shown, but the disclosure is not limited hereto, and a configuration in which the bearings 70, 170, 190, 280 are appropriately abolished may be employed.

[0143] In the above embodiment, the cases are shown in which the valve timing change devices M, M2, M3 including the first internal gears 20, 120, 220 and the second internal gear 30, 130, 230 are applied to the camshaft 2 which opens/closes the exhaust valve of the engine 1; however, the valve timing change device D which is applied to the camshaft 3 which opens/closes the intake valve of the engine 1 can also be configured by making the number of teeth of a first internal gear smaller than the number of teeth of a second internal gear.

[0144] In this case, the rotation member or the external gear is set to perform an retarding operation when the rotation driving force is exerted by the electric motor 6 at a rotation speed slower than a rotation speed of the camshaft 3 in a direction (the CW direction) the same as a rotation direction (the R direction) of the camshaft 3. Therefore, if the electric motor 6 is inoperative, by cogging torque of the electric motor 6, friction forces, alternating torque of the camshaft 3, or the like, the electric motor 6 is rotated with respect to the rotation member or the external gear at the rotation speed slower than the rotation speed of the camshaft 3 in the direction the same as the direction of the camshaft 3, the rotation member or the external gear is relatively rotated with respect to the camshaft 3 in another direction around the axis line S (the CCW direction in FIG. 1), a rotation phase of the camshaft 3 is retarded with respect to the housing rotor, and the open/close timing of the intake valve is changed to the retarding side. Besides, a retarding side contact portion of the rotor comes into contact with a retarding side stopper of the housing rotor, and the open/close timing of the intake valve is maintained at the maximum retarding position.

[0145] In this way, because the open/close timing of the intake valve is positioned at the maximum retarding position, the valve overlap at the time of starting the engine 1 can be reduced, blowback of combustion gas to the intake side can be prevented, and the starting performance can be maintained. That is, when the electric motor 6 is broke down, the failsafe function in the engine 1 can be ensured. As described above, the valve timing change devices M, M2, M3 and the valve timing change device D can share components except that the numbers of teeth are different, and thus they contribute to cost reduction and the like of the entire engine on the whole.

[0146] In the above embodiment, the cases are shown in which the electric motor 5 is not included in the valve timing change devices M, M2, M3 as a portion of configuration elements; however, the electric motor 5 may also be included as a portion of the configuration elements.

[0147] As described above, the valve timing change device of the disclosure can ensure the failsafe function when applied to the camshaft of the exhaust valve while achieving simplification of the structure, cost reduction, downsizing and the like, and thus the valve timing change device can be applied not only as the valve timing change device of the engine, but also as other speed reduction mechanism, speed increasing mechanism, speed changing mechanism or the like.

[0148] Other Configurations

[0149] The valve timing change device of the disclosure changes a relative rotation phase between a camshaft and a housing rotor which interlocks with a rotation of a crankshaft to change an open/close timing of an exhaust valve driven by the camshaft to an advancing side or a retarding side. The valve timing change device includes a rotation member which is driven to rotate by being exerted a rotation driving force; an external gear which is interlocked with the rotation member; a first internal gear which is directly or indirectly meshed with the external gear and is rotated integrally with the housing rotor; and a second internal gear which is directly or indirectly meshed with the external gear and is rotated integrally with the camshaft, the second internal gear having a number of teeth smaller than the number of teeth of the first internal gear.

[0150] The above valve timing change device may employ a configuration in which the external gear is formed to be elastically deformable to be directly meshed with the first internal gear and the second internal gear, and the rotation member includes a cam portion which exerts, to the external gear, a cam action generating elliptic deformation for meshing with the external gear.

[0151] The above valve timing change device may employ a configuration in which the cam portion of the rotation member is fitted to the inner side of the external gear via a bearing that is elliptically deformable.

[0152] The above valve timing change device may employ a configuration in which the external gear is formed into an annular shape to be directly meshed with the first internal gear and the second internal gear; and the rotation member includes an eccentric portion which exerts an eccentricity action to mesh the external gear with the first internal gear and the second internal gear while making the external gear eccentric.

[0153] The above valve timing change device may employ a configuration in which the eccentric portion of the rotation member is fitted to an inner side of the external gear via a bearing.

[0154] The above valve timing change device may employ a configuration in which the number of teeth of the second internal gear is the same as the number of teeth of the external gear.

[0155] The above valve timing change device may employ a configuration in which the external gear is arranged to be indirectly meshed with the first internal gear and the second internal gear via a planetary gear, and the rotation member is integrally formed with the external gear as a portion of the external gear.

[0156] The above valve timing change device may employ a configuration in which the housing rotor is supported via the second internal gear to be capable of rotating around an axis line of the camshaft.

[0157] The above valve timing change device may employ a configuration in which a spacer member joined to the camshaft is included, the second internal gear is fixed to the camshaft via the spacer member, and the spacer member is formed in a manner that a relative rotation range is regulated with respect to the housing rotor.

[0158] The above valve timing change device may employ a configuration in which the housing rotor includes a first housing being cylindrical and having a sprocket on an outer periphery of the first housing, and a second housing being disc-shaped, bound to the first housing and having an opening portion for exposing an end portion of the rotation member.

[0159] The above valve timing change device may employ a configuration in which an electric motor which exerts a rotation driving force on the rotation member is included.

[0160] The above valve timing change device may employ a configuration in which the electric motor includes a housing, and a rotation shaft which is rotatably supported by the housing and is coupled to the rotation member, and the housing is fixed to a cover member of an engine.

[0161] According the valve timing change device made of the above configuration, the failsafe function when applied to the camshaft of the exhaust valve can be ensured while simplification of the structure, cost reduction, downsizing and the like are achieved.

[0162] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents.

Claims

1. A valve timing change device, which changes a relative rotation phase between a camshaft and a housing rotor which interlocking with a rotation of a crankshaft to change an open/close timing of an exhaust valve driven by the camshaft to an advancing side or a retarding side, the valve timing change device comprising: a rotation member which is driven to rotate by being exerted a rotation driving force; an external gear which is interlocked with the rotation member; a first internal gear which is directly or indirectly meshed with the external gear and is rotated integrally with the housing rotor; and a second internal gear which is directly or indirectly meshed with the external gear and is rotated integrally with the camshaft, the second internal gear having a number of teeth smaller than a number of teeth of the first internal gear.

2. The valve timing change device according to claim 1, wherein the external gear is formed to be elastically deformable to be directly meshed with the first internal gear and the second internal gear; and the rotation member comprises a cam portion which exerts, to the external gear, a cam action generating elliptic deformation for meshing with the external gear.

3. The valve timing change device according to claim 2, wherein the cam portion of the rotation member is fitted to an inner side of the external gear via a bearing that is elliptically deformable.

4. The valve timing change device according to claim 1, wherein the external gear is formed into an annular shape to be directly meshed with the first internal gear and the second internal gear; and the rotation member comprises an eccentric portion which exerts an eccentricity action to mesh the external gear with the first internal gear and the second internal gear while making the external gear eccentric.

5. The valve timing change device according to claim 4, wherein the eccentric portion of the rotation member is fitted to an inner side of the external gear via a bearing.

6. The valve timing change device according to claim 1, wherein the number of teeth of the second internal gear is the same as the number of teeth of the external gear.

7. The valve timing change device according to claim 1, wherein the external gear is arranged to be indirectly meshed with the first internal gear and the second internal gear via a planetary gear; and the rotation member is integrally formed with the external gear as a portion of the external gear.

8. The valve timing change device according to claim 1, wherein the housing rotor is rotatably supported around an axis line of the camshaft via the second internal gear.

9. The valve timing change device according to claim 1, comprising a spacer member which is joined to the camshaft, wherein the second internal gear is fixed to the camshaft via the spacer member, and the spacer member is formed in a manner that a relative rotation range is regulated with respect to the housing rotor.

10. The valve timing change device according to claim 1, wherein the housing rotor comprises: a first housing which is cylindrical and has a sprocket on an outer periphery of the first housing, and a second housing which is disc-shaped, bound to the first housing and has an opening portion for exposing an end portion of the rotation member.

11. The valve timing change device according to claim 1, comprising an electric motor which exerts the rotation driving force on the rotation member.

12. The valve timing change device according to claim 11, wherein the electric motor comprises a housing, and a rotation shaft which is rotatably supported by the housing and is coupled to the rotation member, and the housing is fixed to a cover member of an engine.