Patent application title: DEVICE FOR BURNING PRE-MIXED GAS
Yves Cazard (Saint-Jean-Les-Deux-Jumeaux, FR)
IPC8 Class: AF23D1402FI
Class name: Combustion mixer and flame holder
Publication date: 2016-03-10
Patent application number: 20160069563
A device for burning premixed gas, including a ventilator (1) for drawing
in the air/gas mixture, a gas-supply valve (2), a gas injector (3), and a
venturi (4) interposed between said injector (3) and the ventilator (1),
so as to create a negative pressure on the gas valve (2),
The venturi (4) includes a movable part (40) capable of moving under the
action of said ventilator (1) and a restoring spring (43), the
displacement of said movable part being capable modifying the
cross-sections of the passages (41, 42) for gas (G) and air (A).
1. A device for burning premixed gas comprising: a ventilator drawing in
an air/gas mixture, a gas-supply valve, a gas injector, and a venturi
interposed between said gas injector and said ventilator, so as to create
a negative pressure on said gas-supply valve, wherein said venturi
comprises a movable part moving under action of said ventilator and a
restoring spring, and wherein displacement of said movable part modifies
cross-sections of passages for gas and air.
2. Device according to claim 1, wherein said movable part comprises a planar wall being subjected to negative pressure exerted by said ventilator on one face of said planar wall, and, on an opposite face of said planar wall, projecting elements inserted into openings of a body, said movable part being guided in displacement, said body being connected to a supply means for gas or air, wherein cooperation of said projecting elements with said openings occurs through conical surfaces so that depth of insertion of said projecting elements into said openings changes dimensions of the passages, and wherein flow rates are modulated.
RELATED U.S. APPLICATIONS
 Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 Not applicable.
REFERENCE TO MICROFICHE APPENDIX
 Not applicable.
BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a device for burning premixed gas.
 2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
 A device for burning premixed gas operates with a constant air/gas ratio. It includes a venturi, which creates a negative pressure on the gas valve. This negative pressure is more or less important depending on the power being required.
 Such a device has however a drawback, knowing that the negative pressure changes according to the squared flow rate, it is difficult to obtain a sufficient negative-pressure signal when the flow rate is reduced beyond 5. Indeed, when the flow rate is divided by 5, the negative pressure is divided by 25.
 In order to cope with this drawback and to permit high modulation rates, it has been proposed to vary the suction cross-section of the combustion air and the gas in equal proportions. This is achieved through mechanical systems generally controlled by servo-motors or solenoids. Thanks to changes in cross-sections, the negative pressure remains high despite a reduction in flow rate.
SUMMARY OF THE INVENTION
 The present invention pretends to cope with the above drawback without using a control or any external power sources.
 The device for burning premixed gas according to the invention includes a ventilator for drawing in the air/gas mixture, a gas-supply valve, a gas injector and a venturi interposed between said injector and said ventilator, so as to create a negative pressure on said gas valve, and it is characterized in that said device comprises a movable part capable of moving under the action of said ventilator and a restoring spring, the displacement of said movable part being capable modifying the cross-sections of the gas and air passages.
 According to an additional feature of the device according to the invention, the movable part includes a planar wall capable of being subjected to the negative pressure exerted by the ventilator, and comprising, on its face opposite the one subjected to said negative pressure, projecting elements capable of being inserted into openings a body, in which said movable part is guided in displacement, comprises and which are connected to the gas or air supply means, the cooperation of said projecting elements with said openings occurring through conical surfaces, so that the depth of insertion of said projecting elements into said openings permits to change the dimensions of the passages, and thus to modulate the flow rates.
 The advantages and features of the device according to the invention will become clear from the following description, which relates to the attached drawing, which shows a non-restrictive embodiment of same.
BRIEF DESCRIPTION OF THE DRAWINGS
 FIG. 1 is a schematic view, representing the device for burning premixed gas according to the invention.
 FIG. 2 is a cross-sectional view, representing a schematic median cross-section of a portion of the same device.
DETAILED DESCRIPTION OF THE DRAWINGS
 When referring to FIG. 1, we can see that the device for burning premixed gas includes a centrifugal ventilator 1 for drawing in the air/gas mixture AG, a gas-control solenoid valve 2 controlled by a motor M, an injector 3 of gas G and a venturi 4.
 According to the invention, the venturi 4, which is also shown in FIG. 2, includes, in front of the ventilator 1, a part 40, or piston, movable under the action of the negative pressure generated by the ventilator 1, which is capable, depending on its position in the venturi 4, of modifying the cross-section of the passage 41 for gas G and the passage 42 for air A.
 To this end, the venturi 4 comprises two parts, besides the movable part or piston 40, a body 5 comprising three concentric tubular parts--an inner part 50, an outer part 51 and an intermediate part 52.
 The intermediate 52 and outer 51 concentric tubular parts are interconnected by material bridges 53, so as to create a tubular space 54. The intermediate 52 and inner 50 concentric tubular portions are, in turn, united by an end wall 55, which is only centrally drilled with a hole 56 ending into the inner tubular portion 50.
 The part 40 comprises a planar wall 44 bordered peripherally and at one side by a wall 45 aimed at being inserted into the space 54, and which has externally a tubular face 46 of a diameter that permits a close insertion of same without jamming into the outer tubular portion 5, and at the inner side a generally frustoconical face 47, the thickness at the base of which, on the side of the planar wall 44, is larger than the width of the space 54.
 The part 40 is thus movable axially within the outer tubular portion 51, guided by the inner face of the latter, while the depth of insertion of the wall 45 into the space 54, due to the obliquity of the face 47, modulates the size of the passage 42 between the space 54 and the space delimited by the walls 44 and 55, until this passage is eventually closed. It should be noted that stops 57 are interposed between the walls 44 and 55.
 Furthermore, the part 40 includes centrally an axis 48 inserted into the hole 56 and extending in the inner tubular portion 50.
 The hole 56 is of a frustoconical shape, flared towards the part 40, while the axis 48 is provided at its base with a cylindrical part 49 of a diameter slightly larger than the smallest one of the frustoconical hole 56, so as to permit, depending on the depth of insertion of the part 49 into this frustoconical hole 56, to modulate the width of the passage 41 and even to close it.
 It will be understood that depending on the position of the part 40 relative to the end wall 55, this permits to modulate the flow rates at the level of the passages 41 and 42.
 The space 54 is open to the outside, while the inner tubular portion 50 is connected to the injector 3 of gas G.
 Finally, the planar wall 44 is drilled peripherally, on the inner side of the wall 45, with openings O.
 In operation, the ventilator 1 creates a negative pressure at the level of the wall 44, and draws in the movable part or piston 40.
 This displacement opens the passages 41 and 42, and the air A and the gas G flow through the wall 44 through the openings O in order to be mixed.
 When the flow rate of the ventilator 1 increases, the movable part 40 is drawn in by the negative pressure created by the ventilator 1, and moves towards the latter, which permits to enlarge the cross-sections of the passages 41 of the gas G and the air A.
 When the flow rate decreases, the movable part 40 is restored by a spring 43 mounted on the axis 48, which reduces the passages 41 and 42.
 A venturi system 4 is thus obtained, which is automatically adapted depending on the operation of the ventilator 1.
Patent applications in class MIXER AND FLAME HOLDER
Patent applications in all subclasses MIXER AND FLAME HOLDER