DEVICE FOR DETERMINING A POSITION OF A MOVING PART AND METHOD FOR THE OPERATION THEREOF

Abstract

A device for determining a position of a moving part, having a position detector for detecting a position of the moving part relative to a reference position, wherein the position detector has a transmitter which is fixedly connected with the moving part. The position detector is designed such that it is operable in a position detection state for detecting the position of the moving part relative to the reference position and in a power saving state to save power. A capacitive sensor includes the transmitter, and the transmitter and the remainder of the capacitive sensor are designed to coordinate with each other and are arranged in such a way that in the power-saving state of the position detector, a movement of the moving part relative to the reference position is detected by the capacitive sensor and the position detector is transferred automatically from a power-saving state to a position-detecting state.

Description

[0001] This nonprovisional application is a continuation of International Application No. PCT/EP2019/055978, which was filed on Mar. 11, 2019, and which claims priority to German Patent Application No. 10 2018 107 416.6, which was filed in Germany on Mar. 28, 2018, and which are both herein incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

[0002] The present invention relates to a device for determining a position of a moving part and a method for operating such a device.

Description of the Background Art

[0003] Such devices for determining a position of a moving part and methods for their operation are already known from the prior art in numerous design variants.

[0004] For example, EP 2 383 558 A1 discloses an inductive angle sensor for determining torque and relative angular position with respect to a reference position, comprising means for detecting angles and differential angles as well as means for indexing when passing through the reference position with a permanent magnet and a Hall sensor. In order to create an inexpensive and compactly producible torque sensor for angle determination and indexing, it is proposed that the Hall sensor be assigned a flux guide plate which, in the reference position, guides the flux of the permanent magnet to the Hall sensor.

SUMMARY OF THE INVENTION

[0005] It is therefore an object of the present invention to provide a device for determining a position of a moving part and a method for its operation in which power-saving operation is possible.

[0006] This object is achieved by a device for determining a position of a moving part, according to which a position detector is designed in such a way that it is operable in a position detection state to detect the position of the moving part relative to the reference position and in a power-saving state to save power, wherein said device comprises a capacitive sensor which includes the transmitter, and the transmitter and the remainder of the capacitive sensor are formed to coordinate with one another and are arranged in such a manner that in the power-saving state of the position detector, a movement of the moving part relative to the reference position is detectable by means of the capacitive sensor and the position detector can be automatically transferred from its power-saving state to its position detection state as a function of this detection.

[0007] Furthermore, this object is achieved by a method according to which the position detector is automatically transferred from its power-saving state to its position detection state by means of the capacitive sensor as a function of the detection of a movement of the moving part relative to the reference position. In this way, an automatic transfer of the position detector from the power-saving state to the position detection state is made possible as soon as it is required to obtain a position detection by means of the position detector, namely as soon as the moving part has started moving.

[0008] A significant advantage of the invention is in particular that a power-saving operation of the device for determining a position of a moving part is provided. This is particularly advantageous in modern motor vehicles that have a high degree of electrification. The invention is particularly advantageous, for example, for electric vehicles in which the power consumption is a very significant variable. By means of the invention, it is possible for the capacitive sensor to automatically transfer, quasi wake up, the position detector from an power-saving state of the position detector to a position detection state of the position detector in order to save power. This waking up can be achieved with almost no current flow.

[0009] An advantageous development of the device according to the invention provides that the position detector is designed as an inductive and/or magnetic and/or optical sensor. This involves measuring principles known to the person skilled in the art and suitable for determining a position of a moving part relative to a reference position. The aforementioned sensors are therefore tried and tested sensors that are available in a large number of designs. For example, it is conceivable that sensors that are different from one another, that is to say sensor principles that are different from one another, are used simultaneously according to the invention. On the one hand, this results in redundancy. On the other hand, an undesired interaction between several sensors can be effectively prevented.

[0010] A particularly advantageous development of the aforementioned embodiment of the device according to the invention provides that the position detector is designed as an inductive sensor with a transmission coil and a plurality of sensor coils and the capacitive sensor comprises the transmission coil and the sensor coils of the inductive sensor for capacitive evaluation. As a result, the device according to the invention can be implemented in a particularly simple manner in terms of construction and circuitry.

[0011] An alternative advantageous development of the device according to the invention provides that the capacitive sensor has a plurality of transmitter electrodes and one sensor electrode, wherein the transmitter electrodes and the sensor electrode of the capacitive sensor are designed independently of the position detector. In this way, it is possible to design the capacitive sensor in a way that is matched to the function of the capacitive sensor. For example, capacitively effective areas of the capacitive sensor can be made correspondingly larger, so that larger output signals and thus simplified evaluation of these output signals is made possible.

[0012] In principle, the device for determining a position of a moving part can be freely selected within wide, suitable limits in terms of type, mode of operation, shape, material, dimensions and number. Accordingly, the device according to the invention and the inventive method for its operation can be adapted to a large number of applications and installation situations.

[0013] A particularly advantageous development of the device according to the invention provides that the device is designed to determine an angle of rotation and/or a torque of the moving part designed as a rotating part, comprising a position detector designed as an angle detector for detecting an angular position of the rotating part relative to a reference position and at least one indexer for indexing at a predetermined rotation, preferably a 360.degree. rotation, of the rotating part relative to the reference position, wherein the angle detector comprises a transmitter that is non-rotatably connected to the rotating part and is formed as a rotor with a base body for attachment to the rotating part and with a plurality of vanes extending radially outwardly from the base body, and wherein at least one of the vanes of the rotor has a marker detectable by means of the indexer. Many technical applications involve position detection, i.e. angle detection and/or torque detection, for rotating parts. This applies in particular to the field of motor vehicles. Purely by way of example, reference should only be made here to the steering shaft and the detection of the steering angle and/or the detection of the steering torque. In applications in which position detection is required in a measuring range with angles of rotation of more than 360.degree., an indexer is also required accordingly. However, other indexing angle ranges are also possible so that, for example, an index signal is generated every 180.degree..

[0014] In principle, the type, shape, material, dimensions, arrangement and number of the vanes of the rotor can be freely selected within wide, suitable limits. For example, it is conceivable that a plurality of vanes of the rotor have a marker that can be detected by means of the indexer. Advantageously, only a single vane has a marker that can be detected by means of the indexer. As a result, one-to-one indexing is implemented in a simple manner.

[0015] Another advantageous embodiment of the inventive device provides that the indexer is constructed as an inductive and/or capacitive and/or magnetic and/or optical sensor.

[0016] Correspondingly, for example, the use of an angle detector that operates according to a first sensor principle and the use of an indexer that operates according to a second sensor principle, which differs from the first sensor principle, enable effective prevention of undesired interaction between the angle detector on the one hand and the indexer on the other. Furthermore, using a variety of sensor concepts make it easier to meet high requirements with regard to functional safety.

[0017] A particularly advantageous development of the inventive device provides that in a detection area of the indexer, a single vane has an opening which is delimited by a circumferential edge, or all vanes except for a single vane have an opening delimited by a circumferential edge. In this way, the device according to the invention can be implemented particularly easily. For example, the angle detector can be designed as an inductive sensor and the indexer as a capacitive sensor, and a single vane can have an opening delimited by a circumferential edge or all of the vanes except for a single vane can have an opening delimited by a circumferential edge.

[0018] A further advantageous development of the inventive device provides that a single vane extends radially further outward from the base body than the other vanes into a detection area of the indexer, or all vanes except a single vane extend radially further outward from the base body than that single vane into a detection area of the indexer. On the one hand, this indicates a possible alternative to the aforementioned embodiment. On the other hand, with a plurality of indexer, this embodiment of the device according to the invention can be combined, for example, with the aforementioned embodiment. This results in redundancy on the side of the at least one indexer. For example, the angle detector can be designed as an inductive sensor and the indexer as an optical sensor, and a single vane can extend radially further outward from the base body than the other vanes, or all of the vanes except for one single vane can extend radially outward from the base body than the single vane.

[0019] Another advantageous development of the device according to the invention provides that the angle detector and the indexer are each designed as an inductive sensor and that a stator of the indexer has at least one sensor coil, wherein the sensor coil and the at least one marker of the rotor are designed to be coordinated with one another and are arranged relative to one another in such a manner that the sensor coil only acts as a sensor coil for the indexer. As a result, a further alternative or additional design of the device according to the invention is provided. On the other hand, another advantage of this development is that the precise and robust sensor principle of inductive sensor technology is used both for the angle detector and for the indexer.

[0020] A particularly advantageous development of the aforementioned embodiment of the device according to the invention provides that the angle detector has a first operating frequency and the indexer has a second operating frequency, wherein the first operating frequency and the second operating frequency are different from one another. In this way, undesired interaction between the angle detector on the one hand and the indexer on the other is effectively prevented, despite using an inductive sensor in each case for the angle detector and the indexer.

[0021] The angle detector and the indexer can each be at least partially arranged on a common printed circuit board, provides that the printed circuit board is designed as a multilayer printed circuit board and the angle detector is arranged on at least a first layer of the printed circuit board and the indexer is arranged on at least a second layer of the printed circuit board that is different from the first layer. This further simplifies the construction of the device according to the invention. Also, the space requirement is further reduced by using a multilayer printed circuit board, and the device according to the invention can be made even more compact.

[0022] An advantageous further development of the last-named embodiment provides that at least one of the at least one second layers is designed as a shield. In this way, undesired interaction between the angle detector arranged at least partially on the at least one first layer and the indexer arranged at least partially on the at least one second layer is reduced or even prevented. The shield can also be designed to protect the angle detector and/or the indexer from undesired interactions with third-party components or third-party devices.

[0023] A particularly advantageous development of the inventive device provides that the transmitter electrodes and the sensor electrode of the capacitive sensor are each designed as at least one circular sector, the circular sectors being arranged concentrically about an axis of rotation of the rotor. This makes it possible, for example, to arrange sufficiently large, capacitively effective areas of the capacitive sensor, namely the aforementioned circular sectors, in a structurally simple manner in operative connection with the rotor.

[0024] An alternative advantageous development of the device according to the invention provides that the transmitter electrodes and the sensor electrode of the capacitive sensor are each designed as at least one circular segment, the circular segments being arranged concentrically about an axis of rotation of the rotor. In this way it is possible to arrange the capacitive sensor, namely the circular segments, outside or inside of structures of the position detector that are arranged in a ring around the axis of rotation of the rotor.

[0025] A particularly advantageous further development of the aforementioned embodiment provides that the indexer comprises two directly adjacent circular segments and the rotor, wherein the rotor and these two directly adjacent circular segments are suitably designed and arranged relative to the reference position for indexing at a predetermined rotation, preferably a 360.degree. rotation, of the rotating part. This means that an additional indexer is not required. Accordingly, the number of components and the associated outlay for design and circuitry is reduced.

[0026] Another advantageous development of the device according to the invention provides that the position detector and the capacitive sensor are each arranged at least partially on a common printed circuit board and the printed circuit board is designed as a multilayer printed circuit board. Analogous to the above, this results, inter alia, in the advantage that the structure of the device according to the invention is further simplified. On the other hand, the space requirement is further reduced by using a multilayer printed circuit board and the device according to the invention can be made even more compact. However, it is also conceivable that the position detector are arranged on at least one first layer of the printed circuit board and the capacitive sensor is arranged on at least one third layer of the printed circuit board that is different from the first layer.

[0027] An advantageous development of the method according to the invention provides that the position detector is automatically transferred from its position detection state to its power-saving state by means of the position detector as a function of the detection of a movement of the moving part relative to the reference position. In this way, an automatic transfer of the position detector from the position detection state to the power-saving state is also made possible, as soon as the moving part stops moving.

[0028] Another advantageous development of the method according to the invention provides that the capacitive sensor is used in the position detection state of the position detector to detect the position of the moving part relative to the reference position. As a result, redundancy in the position detection of the moving part in the position detection state of the position detector can be implemented in a simple manner in terms of construction and circuitry.

[0029] Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0031] FIG. 1 shows an exemplary embodiment of the device according to the invention in a partial plan view, without a transmitter,

[0032] FIG. 2 shows the embodiment according to FIG. 1 in a partial plan view of a transmitter embodied as a first rotor,

[0033] FIG. 3 is an exemplary illustration of a multilayer printed circuit board in the first embodiment,

[0034] FIG. 4 shows a current flow in the exemplary embodiment shown by way of example,

[0035] FIG. 5 is an exemplary embodiment of the device according to the invention in a partial plan view of a second rotor as an alternative to the first rotor,

[0036] FIG. 6a shows the exemplary embodiment in a partial side view,

[0037] FIG. 6b shows the exemplary embodiment in a further partial side view,

[0038] FIG. 7 shows an exemplary embodiment of the device according to the invention in a partial plan view, without a transmitter,

[0039] FIG. 8 shows an exemplary embodiment of the device according to the invention in a partial plan view, without a transmitter and

[0040] FIG. 9 shows the exemplary embodiment in a partial plan view of a third rotor as an alternative to the first and the second rotor.

DETAILED DESCRIPTION

[0041] FIG. 1 shows a first embodiment of a device according to the invention in a partial view. The device is designed to determine an angle of rotation and a torque of a rotating part, namely a steering shaft of a power steering system (not shown) for a motor vehicle. The device comprises two angle detector, each designed as an inductive sensor, for detecting an angular position of the rotating part relative to a reference position and an indexer designed as a capacitive sensor for indexing during a 360.degree. rotation of the rotating part relative to the reference position, wherein the angle detector each have a rotor that is fixedly connected to the rotating part, comprising a base body for attachment to the rotating part and a plurality of vanes extending radially outward from the base body. Correspondingly, the moving part is a part rotating about an axis of rotation and the respective position detector are designed as angle detector. Furthermore, the transmitter is embodied as the rotor.

[0042] FIG. 1 only partially shows one of the two angle detector, namely its stator 1, with an annular transmitter coil 1.1 and a total of three sensor coils 1.2, 1.3 and 1.4, which are identical to each other but are each arranged rotated with respect to each other at a certain angle about the axis of rotation of the rotating part. The rotor 2 that corresponds thereto is shown with the base body 2.1 and the vanes 2.2 in FIG. 2. The reference position is symbolized in FIG. 2 by means of a dot 5. The indexer and the rotating part, i.e. the steering shaft, are not shown. The axis of rotation is symbolized in FIGS. 1 and 2 by a cross 3, wherein the axis of rotation 3 runs perpendicular to the image planes of FIGS. 1 and 2.

[0043] The rotating part, i.e. the steering shaft, is divided into two parts in a manner known to those skilled in the art, wherein one part of the steering shaft is non-rotatably connected with one of the angle detector, namely with its rotor 2, and the other part of the steering shaft is non-rotatably connected with the other of the angle detector, namely with its rotor. The indexer is assigned to one of the two parts of the steering shaft. The two parts of the steering shaft are connected to one another in a force-transmitting manner known to those skilled in the art by means of a torsion bar. FIG. 2 shows only the rotor 2 of the angle detector, which is assigned with the indexer to the same part of the steering shaft. Each rotor 2 is made in one piece from a sheet metal suitable for inductive coupling. The rotor 2 shown in FIG. 2 has a total of nine vanes 2.2 which extend radially outward from the base body 2.1. A gap 4 is formed in each case between the individual vanes 2.2. The vanes 2.2 are arranged uniformly around the circumference of the base body 2.1 of the rotor 2. As can be seen from FIG. 2, one of the vanes 2.2 of the rotor 2 has an opening 6 which is delimited by a circumferential edge. This opening 6 is a marker 6 that can be detected by means of the indexer.

[0044] The rotor of the other, not shown, angle detector has a total of eighteen vanes. This rotor has no marker detectable by an indexer or of the indexer, for example in the form of an opening delimited by a circumferential edge in one of its vanes. By means of a differential angle determination known well to those skilled in the art between the angle detector partially shown in FIG. 2 and said non-shown angle detector, the torque with which the steering shaft is acted upon can be determined. The angle of rotation of the steering shaft is determined by means of the angle detector, namely stator 1 and rotor 2, each shown partially in FIGS. 1 and 2. The indexer also serves to detect angles of rotation of 360.degree. and more. This is necessary, for example, for commercial vehicles such as trucks or the like.

[0045] In addition to the rotor, for example rotor 2, each of the angle detector also has a stator, for example stator 1. The stator 1 is constructed in a manner known to the person skilled in the art and includes the transmission coil 1.1 and the three sensor coils 1.2, 1.3, 1.4. In the present exemplary embodiment, the respective stator 1 is arranged on a single multilayer printed circuit board 8, which is shown by way of example in FIG. 3. The multilayer printed circuit board 8 has a total of six layers, which are designated in FIG. 3 with a, b, c, d, e and f. The individual layers a to f are applied to printed circuit board material, which is symbolized in FIG. 3 by means of different textures for the purpose of better clarity. The stator 1 of the angle detector partially shown in FIG. 1 is arranged on layers a and b of the printed circuit board 8 and the stator of the angle detector, not shown in FIG. 1, is arranged on layers e and f of the printed circuit board 8. On the one hand, the indexer embodied as a capacitive sensor is arranged on layers c and d of the printed circuit board 8. On the other hand, the layers c and d of the printed circuit board 8 are also designed as a shield, by means of which undesired interaction between the angle detector designed as inductive sensors is at least reduced, the stators 1 of which are arranged on layers a and b and on layers e and f of the printed circuit board 8. In FIG. 3, only layers a to f are shown, but not the stators 1 and the indexer designed as a capacitive sensor.

[0046] Furthermore, the respective angle detector is designed such that it can be operated in a position detection state designed as an angle detection state for detecting the angle of the rotating part relative to the reference position 5 and in a power-saving state for power saving, wherein the device has an additional capacitive sensor comprising the rotor 2, and the rotor 2 and the remainder of the additional capacitive sensor are designed to be coordinated with one another and are arranged in such a manner that in the power-saving state of the respective angle detector, a movement of the rotating part relative to the reference position 5 can be detected by means of the additional capacitive sensor, and the respective angle detector can be transferred automatically from its power-saving state to its angle detection state as a function of this detection. The two angle detecting means, for example, the angle detector partially shown in each case in FIGS. 1 and 2 with the stator 1 and the rotor 2, can thus be automatically transferred by means of the additional capacitive sensor from the respective power-saving state to the respective angle detection state.

[0047] In the first exemplary embodiment, as already explained above, the respective position detector designed as angle detector is designed as an inductive sensor, for example the angle detector shown with the stator 1, the transmission coil 1.1 and the three sensor coils 1.2, 1.3 and 1.4, wherein the additional capacitive sensor includes the transmitter coil 1.1 and the sensor coils 1.2, 1.3 and 1.4 of the stator 1 for capacitive evaluation. The additional capacitive sensor according to the present first exemplary embodiment does not have sensor structures that are separate from this angle detector. Accordingly, the angle detector shown and the additional capacitive sensor are each arranged on the common printed circuit board 8.

[0048] The device according to the invention is explained in more detail below in accordance with the first exemplary embodiment and with reference to FIGS. 1 to 4.

[0049] When the steering shaft rotates, for example due to a steering intervention by a vehicle driver of the motor vehicle, the steering shaft rotates relative to the reference position 5, so that the angle of rotation of the steering shaft can be determined in a manner known to those skilled in the art by means of the one angle detector partially shown in FIGS. 1 and 2. On the other hand, the two parts of the steering shaft twist towards each other, which leads to a torsion of the torsion bar, so that by determining the differential angle between the angle detected by means of the aforementioned angle detector and the angle detected by means of the not-shown angle detector in a manner known to those skilled in the art, the torque introduced in the steering shaft can be determined. When determining the angle by means of the angle detector partially shown in FIGS. 1 and 2, the opening 6 arranged in the one vane 2.2, i.e. the marker detectable by means of the indexer, is not a hindrance, since the current flow relevant for the inductive sensor follows the geometry shown in FIG. 4. As can be seen from this, the current flows along the outer contour of the rotor 2 shown in the image plane of FIGS. 2 and 4. The current flow required for the inductive sensor system is therefore not impeded by the opening 6.

[0050] The opening 6, that is to say the marker, can be detected by means of the indexer designed as a capacitive sensor. Correspondingly, the indexer can be used to detect 360.degree. rotations of the rotating part, that is to say the steering shaft, and thus also to detect angles of rotation of the steering shaft of 360.degree. and more. For example, this can always take place when the vane 2.2 of the rotor 2 passes the reference position 5 with the opening 6.

[0051] If the steering shaft does not rotate, for example, for the duration of a predetermined time interval, then the respective position detector designed as angle detector is automatically transferred from its position detection state to its power-saving state. In the power-saving state of the two angle detector, position detection, that is to say detection of the angle of rotation, takes place only by means of the additional capacitive sensor.

[0052] In contrast to the position detection state of this angle detector, which is designed as an angle detection state, instead of inductive sensing, capacitive sensing takes place in the power-saving state, wherein for example the capacitive coupling of two of the sensor coils to one another, i.e. 1.2 and 1.3 or 1.2 and 1.4 or 1.3 and 1.4, are detected and evaluated in a manner known to those skilled in the art. For this purpose, the two sensor coils, for example the transmission coils 1.2 and 1.3, are each switched as transmitter electrodes. The remaining sensor coil 1.4 is then used as a sensor electrode. The transmitter electrodes, for example 1.2 and 1.3, are connected to different potentials; the transmitter electrodes, for example 1.2 and 1.3, are preferably each connected to one of the supply voltages of the angle detector. However, the use of divided or multiplied potentials that result from the two supply voltages is also conceivable. Depending on the rotational position of the rotor 2 about the axis of rotation 3, the capacitance between the transmitter electrode 1.2 and the sensor electrode 1.4 of the additional capacitive sensor on the one hand and between the transmitter electrode 1.3 and the sensor electrode 1.4 of the additional capacitive sensor on the other is different. For example, see FIGS. 6a and 6b in which the coupling of the aforesaid pairs by means of the illustrated rotor 2 exemplifies two mutually different rotational positions of the rotor 2, and thus the steering shaft. This difference can then be used in a manner known to the person skilled in the art to determine the position, that is to say, for example, to determine the angle.

[0053] To increase the accuracy of the position determination, that is to say the position detection, the individual sensor coils 1.2, 1.3 and 1.4 can be used alternately as transmitter electrodes and as a sensor electrode, for example via a multiplex process. Accordingly, a total of three measurement results would be achieved in the present first exemplary embodiment.

[0054] In other embodiments, it is possible that the three sensor coils 1.2, 1.3 and 1.4 are used as transmitter electrodes and the transmitter coil 1.1 is used as the sensor electrode of the additional capacitive sensor. For example, a time-division multiplex process can be used for this.

[0055] Furthermore, it is also possible that, for example, the annular transmission coil 1.1 with an electrode 1.5 arranged in an interior delimited by the sensor coils 1.2, 1.3 and 1.4 forms the additional capacitive sensor. See FIG. 1. In this case, the sensor coils 1.2, 1.3 and 1.4 form intermediate capacitances which, as a function of the rotational position of the rotor 2, receive different proportions of a transmission signal from the transmitter electrode 1.1 and/or the transmitter electrode 1.5 of the additional capacitive sensor. In principle, this is also possible by simultaneously emitting a magnetic field to be inductively sensed by means of the angle detector designed as inductive sensors.

[0056] By evaluating the capacitive coupling, conclusions can be drawn about a change in the rotational position of the rotor 2 and thus of the steering shaft. This can be done with very little power expenditure during the power-saving state. Triggered by the aforementioned detection, the more power-intensive inductive angle detections can then be started during the position detection state.

[0057] In the following, further embodiments of the invention are shown by way of example. Components that are the same or have the same effect as the first exemplary embodiment are provided with the same reference numbers. The further exemplary embodiments are each explained only to the extent of the differences from the preceding exemplary embodiments. Otherwise, reference is made to the explanations about the previous exemplary embodiments.

[0058] FIG. 5 shows a second embodiment of the inventive device, wherein the second embodiment is different from the first embodiment by means of the rotor.

[0059] The second exemplary embodiment essentially corresponds to the first exemplary embodiment, so that reference is made to the above statements as far as possible. In contrast to the first exemplary embodiment, all of the vanes 2.2 except for a single vane 2.2 of the rotor 2 have an opening 6 delimited by a circumferential edge. The rotor 2 of the second exemplary embodiment is thus formed inversely to the rotor 2 of the first exemplary embodiment. Correspondingly, in the second exemplary embodiment, the single vane 2.2 without opening 6 acts as a marker that can be detected by means of the indexer. Otherwise, the structure and the mode of operation of the second exemplary embodiment correspond to those of the first exemplary embodiment.

[0060] FIG. 7 illustrates a third embodiment of the device according to the invention. In contrast to the first and second embodiment, the additional capacitive sensor has a structure 7 with a plurality of transmitter electrodes 7.1, 7.2 and 7.3 and a sensor electrode 7.4, wherein the transmitter electrodes 7.1, 7.2 and 7.3 and the sensor electrode 7.4 of the additional capacitive sensor are designed independently of the position detector, that is, independently of the two angle detector. This means that the transmitter coil 1.1 and the sensor coils 1.2, 1.3 and 1.4 of the stator 1 of the shown angle detector are not capacitively evaluated, but instead, a separate structure of the additional capacitive sensor, namely the structure 7, is used. According to the third embodiment, the transmitter electrodes 7.1, 7.2 and 7.3 and the sensor electrode 7.4 of the additional capacitive sensor 7 are each formed as two circular sectors, wherein said circular sectors are concentrically arranged about the rotation axis 3 of the rotor 2. In the present exemplary embodiment, the two circular sectors, which are each assigned to the transmitter electrode 7.1, 7.2 and 7.3 and the sensor electrode 7.4, are arranged opposite one another and are connected to one another in an electrically conductive manner. See FIG. 7. For example, the same supply connections can be used for the additional capacitive sensor during the power-saving state of the two angle detector, which is generally referred to as so-called pin sharing.

[0061] This separate structure 7 of the additional capacitive sensor can for example be arranged at least partially on the printed circuit board 8 together with the structures of the two angle detector and the indexer, wherein the additional capacitive sensor is arranged in at least one layer of the printed circuit board 8, not shown, that is different from the first and second layer.

[0062] The capacitive coupling between all electrodes 7.1, 7.2, 7.3 and 7.4 that are not connected to one another can now be detected cyclically and evaluated in a manner known to those skilled in the art, which in turn depends on the rotational position of the rotor 2 about the axis of rotation 3, i.e. about the axis of rotation of the steering shaft.

[0063] In a fourth embodiment of the inventive device shown in FIGS. 8 and 9, the transmitter electrodes 7.1, 7.2 and 7.3 and the sensor electrode 7.4 of the additional capacitive sensor are in each case formed as two mutually opposite circular segments and are electrically conductive connected, wherein the circular segments are arranged concentrically about the axis of rotation 3 of the rotor 2. As can be seen in FIG. 9, the rotor 2 of this embodiment is modified such that a vane 2.2 of the rotor 2, as compared to the remaining vanes 2.2 of the rotor 2, extends radially outwardly.

[0064] By means of this design of the additional capacitive sensor and the rotor 2 according to the fourth exemplary embodiment, it is possible, for example, that the indexer comprises two directly adjacent circular segments, for example the circular segments 7.1 and 7.2, and the rotor 2, wherein the rotor 2 and these two directly adjacent circular segments are suitably designed and arranged for indexing during a 360.degree. rotation of the rotating part, i.e. the steering shaft, relative to the reference position 5. Correspondingly, an additional indexer, for example the indexer designed as a capacitive sensor of the first, second and third exemplary embodiment, is unnecessary. In contrast to the present fourth exemplary embodiment, it is also possible for a plurality of index positions to be detectable in the aforementioned manner. For this, a corresponding modification of the rotor is then required.

[0065] The invention is not limited to the present exemplary embodiments. For example, the angle of rotation and/or torque of other rotating parts can also be advantageously determined by means of the device according to the invention. Instead of detecting the angle of rotation and the torque, it is possible to detect only the angle of rotation or the torque. In addition to angles of rotation, the invention also includes other types of position detection, for example in the case of linearly moving parts. The invention can also be used in other fields of application apart from the automotive industry.

[0066] As already explained, the at least one angle detector and the at least one indexer can be freely selected within wide, suitable limits. This also applies to the sensor principle used. The at least one angle detector is preferably designed as an inductive and/or magnetic and/or optical sensor. The same applies, if present, to the at least one indexer. Accordingly, various combinations of sensor principles can be used simultaneously, for example for a plurality of angle detector and/or a plurality of indexer.

[0067] For example, it is conceivable that a single vane extends radially further outward from the base body than the other vanes into a detection area of the indexer, or that all vanes except for a single vane extend radially further outward from the base body than the single vane into a detection area of the indexer. In this case, the angle detector can be designed as an inductive sensor and the indexer as an optical sensor, and a single vane can extend radially further outward from the base body than the other vanes or all vanes except for one single vane can extend radially further outward from the base body than the single vane. For example, the optical sensor could be arranged offset radially outward relative to the rotor in such a way that the optical sensor can detect the marker detectable by means of the optical sensor, that is to say, the only longer or the only shorter vane of the rotor.

[0068] In another embodiment of the device according to the invention, it could be that the angle detector and the indexer are each designed as an inductive sensor, and that a stator of the indexer has at least one sensor coil, wherein the sensor coil and the at least one marker of the rotor are designed to be coordinated with each other and are arranged relative to one another in such a manner that the sensor coil only acts as a sensor coil for the indexer. For example, the sensor coil for detecting the marker could be designed to be locally limited in such a way that this sensor coil, in contrast to at least one further sensor coil of the angle detector, has a detection area which comprises only one vane and a gap adjacent to this vane according to one of the above embodiments. In the case of a rotor according to FIG. 2, a substantially constant voltage would therefore always be induced in this sensor coil when the rotating part rotates. Only when the vane with the opening passes through the detection area would a voltage deviating from the otherwise-induced voltage be induced in the sensor coil. The same would apply to an embodiment in which a rotor according to FIG. 5 would be used. Only when the vane without an opening passes through the detection area would a voltage deviating from the otherwise-induced voltage be induced in the sensor coil.

[0069] In particular in the two last-named embodiments of the device according to the invention in which a plurality of inductive sensors are used, it is advantageous that the angle detector has a first operating frequency and the indexer has a second operating frequency, wherein the first operating frequency and the second operating frequency are different from one another. For example, the first operating frequency could be 3-4 MHz and the second operating frequency could be 6-8 MHz. Due to the significant deviation of the first from the second operating frequency, undesired interaction between the two inductive sensors would be effectively prevented. This development of the arrangement according to the invention could also be used advantageously in the case of a plurality of inductive angle detector.

[0070] The components of the at least one angle detector and of the at least one indexer do not necessarily have to be arranged at least partially on a single printed circuit board, in particular a multilayer printed circuit board. Depending on the requirements of the individual case, the components of the at least one angle detector and of the at least one indexer can also be arranged on printed circuit boards or the like, which are different from one another, in one or more layers. The same applies to the capacitive sensor for the automatic transfer of the position detector from its power-saving state to its position detection state. In addition, an indexer is not absolutely necessary.

[0071] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.

Claims

1. A device for determining a position of a moving part, the device comprising: a position detector to detect a position of the moving part relative to a reference position, the position detector having a transmitter fixedly connected to the moving part, the position detector being designed such that it is operated in a position detection state for detecting the position of the moving part relative to the reference position and in a power-saving state to save power; and a capacitive sensor comprising the transmitter, and the transmitter and the remainder of the capacitive sensor are formed to be coordinated with each other and are arranged such that in the power-saving state of the position detector, a movement of the moving part relative to the reference position is detectable via the capacitive sensor and, as a function of this detection, the position detector is automatically transferred from its power-saving state to its position-detecting state.

2. The device according to claim 1, wherein the position detector is designed as an inductive and/or magnetic and/or optical sensor.

3. The device according to claim 2, wherein the position detector is formed as an inductive sensor with a transmitter coil and a plurality of sensor coils and wherein the capacitive sensor at least partially includes the transmitter coil and the sensor coils of the inductive sensor for capacitive evaluation.

4. The device according to claim 1, wherein the capacitive sensor has a plurality of transmitter electrodes and a sensor electrode, wherein the transmitter electrodes and the sensor electrode of the capacitive sensor are formed at least partially independent of the position detector.

5. The device according to claim 1, wherein the device is configured to determine a rotation angle and/or torque of the moving part formed as a rotating part, comprising a position detector formed as an angle detector for detecting an angular position of the rotating part relative to a reference position and at least one indexer for indexing at a predetermined rotation, preferably a 360.degree. rotation, of the rotating part relative to the reference position, wherein the angle detector has a transmitter which is non-rotatably connected with the rotating part and which is formed as a rotor with a base body for attachment to the rotating part and a plurality of vanes extending radially outwardly from the base body, and wherein at least one of the vanes of the rotor has a marker that is detected via the indexer.

6. The device according to claim 5, wherein the transmitter electrodes and the sensor electrode of the capacitive sensor are each designed as at least one circular sector, wherein the circular sectors are arranged concentrically about an axis of rotation of the rotor.

7. The device according to claim 5, wherein the transmitter electrodes and the sensor electrode of the capacitive sensor are each designed as at least one circular segment, and wherein the circular segments are arranged concentrically about an axis of rotation of the rotor.

8. The device according to claim 7, wherein the indexer includes two directly adjacent circular segments and the rotor, wherein the rotor and the two directly adjacent circular segments are suitably configured and arranged for indexing at a predetermined rotation, preferably a 360.degree. rotation, of the rotating part relative to the reference position.

9. The device according to claim 1, wherein the position detector and the capacitive sensor are each at least partially arranged on a common printed circuit board and wherein the printed circuit board is designed as a multilayer printed circuit board.

10. A method comprising: providing a device according to claim 1; and automatically transferring the position detector from a power-saving state to a position detection state via the capacitive sensor as a function of the detection of a movement of the moving part relative to the reference position.

11. The method according to claim 10, wherein the position detector is automatically transferred from its position detection state to its power-saving state via the position detector as a function of the detection of a movement of the moving part relative to the reference position.

12. The method according to claim 10, wherein the capacitive sensor is used in the position detection state of the position detector to detect the position of the moving part relative to the reference position.