FR2889566A1 - Mechanical actuator for motor vehicle transmission, has covers mounted relative to enclosure to form stop for stopping piston in two stable positions, and ring and shoulder forming stop for stopping another piston in two stable positions - Google Patents

Abstract

The actuator has a rod (24) projecting outside an enclosure (12) delimiting an inner volume (20), and a piston (22) mounted movable relative to the enclosure along a rod axis and axially dividing the volume into two chambers. Two driving units have springs (50, 54) returning two pistons (22, 30) towards the base of a tank. Distal and proximal cylindrical covers (38, 40) are mounted relative to the enclosure to form a stop for axially stopping the piston (22) in two stable positions. A ring (41) and a shoulder (43) form a stop for axially stopping the piston (30) in two stable positions. An independent claim is also included for an automatic shifting device for a motor vehicle and including a transmission and an actuator.

Description

The present invention relates to a mechanical actuator of the type comprising:

  an enclosure delimiting an interior volume pierced by an opening, a rod extending into the interior volume and projecting out of the enclosure through the opening; a first piston integral with the rod mounted to move relative to the enclosure according to the axis of the rod and axially dividing the internal volume into two chambers, - first axial positioning means of the first piston 10 comprising: - first axial thrust means of the first piston in a selective manner in two opposite directions, - a first set of at least one stop of the first piston, positioned in the chamber so as to axially stop the first piston at two stable positions defined by the position of the first set of stops in the chamber.

  The first set of stops is generally constituted by two stops integral with the chamber disposed on either side of the piston so that the latter is supported on one of the stops in a stable position.

  For some applications, more than two stable positions are required. This is for example the case of the automatic gearshift devices for a motor vehicle, where the speed selection grid usually comprises four levels: reverse / first and second speeds / third and fourth speeds / fifth and sixth speeds.

  Two actuators in series are used. This solution is quite complex and requires a large volume.

  The object of the invention is a compact mechanical actuator capable of providing more than two stable positions.

  For this purpose, the subject of the invention is a mechanical actuator of the aforementioned type, characterized in that: the first set of abutments is mounted movably relative to the enclosure along the axis of the rod; axial positioning means of the first set of stops in two stable positions relative to the enclosure.

  Thanks to the axial positioning of the stops according to the invention, the rod can take up to two new stable positions. The actuator thus allows in this case the rod to take in all up to four stable positions.

  A mechanical actuator according to the invention may further comprise one or more of the following features: the second positioning means comprise second axial thrust means of the first set of stops in a selective manner in two opposite directions, and a second second set of at least one stop of the first set of stops, positioned in the chamber so as to stop axially the first set of stops at two stable positions defined by the position of the second set of stops in the chamber; - The actuator comprises a second piston mounted movably relative to the chamber along the axis of the rod and secured to the first set of stops, the first and second pistons together defining three chambers in the interior volume of the enclosure; - the stem carries two collars; the second piston defines a passage opening of the rod and is slidably mounted on the rod between the two collars; the first thrusting means comprise a first pipe for supplying pressurized fluid into the chamber farthest from the opening of the chamber, and a first spring for moving the first piston relative to the first set of stops; - The second thrust means comprises a second fluid inlet pipe under pressure in the chamber between the pistons, and a second axial spacing spring of the second piston relative to the opening of the chamber; the actuator comprises a first electrical fluid passage valve towards the first pipe which can take a first position which alone causes the positioning of the first piston in one of its two stable positions relative to the first set of stops, and a second position driving alone the positioning of the first piston in the other stable position relative to the first set of stops, and a second electric fluid passage valve to the first pipe can take a first position alone causing the positioning of the first set of stops in one of its two stable positions relative to the enclosure, and a second position alone causing the positioning of the first set of stops in the other stable position relative to the enclosure; the actuator comprises a pipe connecting the chamber furthest from the opening of the chamber to the chamber closest to this opening.

  The invention also relates to a device for automatic shift for a motor vehicle characterized in that it comprises a gearbox and an actuator according to the invention for selecting a speed of the box.

  The invention will be better understood with the aid of the description which follows, given solely by way of example and with reference to the appended drawings, in which: FIG. 1 is a sectional view of a mechanical actuator according to the invention, - Figure 2 is a block diagram of an automatic shift device for a motor vehicle, comprising the actuator of Figure 1, and - Figures 3 to 6 are sectional figures of the actuator of Figure 1 illustrating the stable positions it can take.

  The actuator, designated by the general reference 10 in FIG. 1, comprises an enclosure 12 consisting of a tank 14 and a lid 16, covering the tank 14 and pierced with a circular opening 18.

  The tank 14 and the lid 16 together define an interior volume 20 composed of three coaxial cylindrical portions of axis X, placed end to end. The X axis also passes through the center of the opening 18. The diameter of the cylindrical portions decreases toward the bottom of the tank, that is to say towards the opposite side to the opening 18.

  The actuator 10 comprises a first piston 22 mounted to move relative to the chamber along the axis X. The first piston 22 is a disk mounted to slide tightly in the cylindrical portion of the inner volume 20 of smaller diameter. It thus divides axially the interior volume 20 into two chambers.

  The actuator further comprises a rod 24, integral with the first piston 22, extending in the inner volume 20 along the axis X and projecting out of the enclosure through the opening 18.

  Two flanges 26, 28 are carried by the rod in the inner volume 20. The flange closest to the opening 18 is called the proximal flange 28, while the other flange is called the distal flange 26.

  The actuator 10 further comprises a second piston 30. This second piston 30 has a profile in axial section in the form of H. In other words, it consists of a hollow cylinder 32, in the middle of which a disc 34 is disposed. The hollow cylinder 32 and the central disc 34 are integral with each other. An opening 36 for passage of the rod 24 is formed in the disk 34. This opening 36 is bordered, respectively on two opposite faces of the disk 34, by two sleeves 38, 40. The sleeve closest to the opening 18 is said proximal sleeve 40, while the other sleeve is said distal sleeve 38. The piston 30 is mounted on the rod 24 in a sealed manner between the two flanges 26, 28. Thus, by cooperating with the flanges 26, 28, the sleeves 38. , 40 form a first set of stops stops the rod 24, and therefore the first piston 22.

  The second piston 30 is slidably mounted in the third portion of the inner volume 20 facing the opening 18, the diameter of the hollow cylinder 32 corresponding to the diameter of the third portion in which it slides in a sealed manner. The actuator 10 comprises a ring 41 disposed inside the enclosure 12, against the cover 16, stopping the second piston 30 in its stroke towards the cover 16. The same piston 30 is stopped in the other direction by a shoulder 43 in the tank 14, resulting from the difference in diameter between the second and the third part of the internal volume 20.

  Thus, the ring 41 and the shoulder 43 form a second set of stops of the second piston 30.

  The interior volume 20 is thus divided by the first and second pistons 22, 30 into three chambers. The chamber farthest from the opening 18 of the cover 16 is called the distal chamber 42, while the chamber contiguous to this opening 18 is called the proximal chamber 44. The third chamber, interposed between the two preceding and delimited axially on each side by the pistons 22, 30 is called the intermediate chamber 46.

  The actuator 10 also comprises first axial thrust means of the first piston 22 in a selective manner in two opposite directions, along the X axis, as well as second axial thrust means of the second piston 30 in a manner selective in two opposite directions, also along the axis X. The first thrust means comprise a first pipe 48 for supplying fluid under pressure in the distal chamber 42. This first pipe 48 is formed in the tank 14 of the 12. The first thrust means also comprise a spring 50 wound around the X axis bearing, on one side, on the first piston 22 and, on the other side, on the second piston 30. spring 50 tends to return the piston 22 to the bottom of the tank 14, in other words to bring the rod 24 towards the inside of the chamber 12.

  Similarly, the second thrust means comprise a pipe 52, formed in the tank 14, for introducing the pressurized fluid into the intermediate chamber 46, and a second spring 54. The second spring 54 is wound around the X axis and rests, on one side, against the second piston 30 and, on the other side, against the cover 16. It makes it possible to push the second piston 30 towards the bottom of the tank 14.

  The actuator 10 further comprises a pipe 56, formed in the tank 14, for connecting the distal chamber 42 to the proximal chamber 44.

  In order to avoid overpressure, for example in the event of blockage of the rod 24, the actuator 10 is provided with first and second pressure limiters 58, 60, associated respectively with the first pipe 48 and the second pipe 52.

  The first pressure limiter 58 comprises a first channel 61 formed in the tank 14 and connected by a first constriction 62 to the first pipe 48. A first ball 64 is inserted into the first channel 61 and pushed against the constriction 62 by a spring 66. The first channel 61 is also connected to the second conduit 58.

  Thus, during an overpressure in the first pipe 48, the ball is detached from the throttle 62 so as to allow a fluid discharge between the first pipe 48 and the second pipe 52.

  Similarly, the second pressure limiter 60 includes a second channel 68 connected by a second constriction 70 to the second conduit 52. A second ball 72 is inserted into the second channel 68 and pushed against the constriction 70 by a spring 74. The second channel 68 is also connected to the proximal chamber 44 by a duct 76 formed in the cover 16.

  Thus, during an overpressure in the second pipe 52, the second ball 72 is detached from the constriction 70 so as to allow discharge to the first pipe 48, via the proximal chamber 44 of the connecting pipe 56 and the distal chamber 42.

  The device, represented in FIG. 2, for automatic shifting of the motor vehicle is designated by the general reference 80.

  It comprises the actuator 10 of FIG. 1 and a pump 82 for pressurizing a fluid stored in a tank 83. Each of the first and second fluid lines 48, 52 is connected to the pump 82 respectively by first and second second valves 84, 86. Each of the valves 84, 86 can take a first position causing the passage of pressurized fluid from the pump 83, respectively to the first pipe 48 or the second pipe 52. Each valve 84, 86 can also take a second position causing the evacuation of the fluid contained in the first pipe 48 or the second pipe 52 respectively to the tank 83.

  Thus, the first position of the first valve 84 alone causes the positioning of the first piston 22 in the stable position obtained when the distal flange 26 bears against the distal sleeve 38, while the second position alone causes the positioning the first piston 22 in the other stable position obtained when the proximal collar 28 bears against the proximal sleeve 40.

  Similarly, the first position of the second valve 86 alone causes the positioning of the second piston 30 in the stable position obtained when it bears against the ring 41, while the second position alone causes the positioning of the second piston 30 in the other stable position obtained when it bears against the shoulder 43.

  The gearshift device 80 further comprises a gearbox 88 whose jaw engagement linkage 90 is connected to the rod 24 of the actuator 10 in order to select a group of one or two speeds among: reverse gear / first and second speeds / third and fourth speeds / fifth and sixth speeds.

  The device 80 further comprises a passage actuator 92 connected to the linkage 90 for selecting a speed in each group. The passage actuator 92 comprises a jack 94 which can take two positions in order to rotate the rod 24 about its axis X. With reference to FIGS. 3 to 6, the operation of the actuator 10 of FIG. 1 will now be described.

  In the following, the introduction of the fluid into a pipe is obtained by placing the respective valve in its first position.

  On the contrary, the absence of fluid introduction into a pipe is achieved by placing the respective valve in its second position.

  The first position of the actuator (FIG. 3) is obtained when it is not powered, that is to say when no fluid is introduced into the first and second conduits 48, 52.

  In this position, the first spring 50 pushes the first piston 22, and thus the rod 24, away from the second piston 30 and the second spring 54 pushes the second piston 30 against the shoulder 43. The rod 24 is therefore in its position as deep as possible in the enclosure 12.

  FIG. 4 shows the second position taken by the rod 24. This position is obtained by introducing the fluid under pressure into the first pipe 48 so that it fills the distal chamber 42. The fluid then pushes the first piston 22 towards the opening 18 until the rod 24 is stopped by the distal sleeve 38 of the second piston 30.

  Due to the connecting line 56, the proximal chamber 44 also fills with fluid. The fluid thus exerts a counter-pressure on the second piston 30, which, combined with the force provided by the second spring 54, keeps the second piston 30 against the shoulder 43.

  The third position of the rod 24 is shown in FIG. 5. It is obtained by introducing the fluid only into the second pipe 52. The fluid then fills the intermediate chamber 46 and pushes the second piston 30 against the ring 41.

  The first spring 50 contributes, with the pressure exerted by the fluid in the intermediate chamber 46, to maintain the first piston 20 as far as possible from the second piston 30, that is to say when the proximal collar 28 is kept in contact the proximal sleeve 40.

  Finally, the fourth position of the rod 24 shown in FIG. 6 is the position in which the rod 24 is the most out of the enclosure 12.

  This position is obtained by simultaneously introducing the fluid under pressure into the three chambers 42, 44, 46 simultaneously.

  The fluid contained in the distal chamber 42 then pushes, on the one hand, the first piston 20 towards the second piston 30 and, on the other hand, with the aid of the fluid contained in the intermediate chamber 46, the second piston 30 against the ring 41.

Claims (9)

  1. Mechanical actuator of the type comprising: - an enclosure (12) defining an interior volume (20) pierced by an opening (18), - a rod (24) extending into the interior volume (20) and protruding out of the enclosure (12) through the opening (18), - a first piston (22) integral with the rod (24) movably mounted relative to the enclosure (12) along the axis (X) of the stem (24). ) and axially dividing the inner volume (20) into two chambers, first axial positioning means of the first piston (22) comprising: - first axial thrust means (48, 50) of the first piston in a selective manner in two opposite directions, - a first set of at least one stop (38, 40) of the first piston (22), positioned in the chamber (12) so as to axially stop the first piston (22) at two positions defined by the position of the first set of abutments (38, 40) in the enclosure (12), characterized in that the first set of abutments (38, 40) ) is mounted movably relative to the enclosure (12) along the axis (X) of the rod (24), and in that the actuator comprises second axial positioning means (41, 43, 52, 54). the first set of stops (38, 40) in two stable positions relative to the enclosure (12).   2. An actuator according to claim 1, characterized in that the second positioning means comprise: second axial thrust means (52, 54) of the first set of stops (38, 40) in a selective manner in two opposite directions and a second set of at least one stop (41, 43) of the first set of abutments (38, 40), positioned in the enclosure (12) so as to axially arrest the first set of abutments ( 38, 40) at two stable positions defined by the position of the second set of stops (41, 43) in the enclosure (12).   3. Actuator according to claim 2, characterized in that it comprises a second piston (30) movably mounted relative to the enclosure (12) along the axis (X) of the rod (24) and integral with the first set stop (38, 40), the first and second pistons (22, 30) together defining three chambers (42, 44, 46) in the interior volume (20) of the enclosure (12).   4. Actuator according to claim 3, characterized in that: -the rod (24) carries two flanges (26, 28), - the second piston (30) defines an opening (36) for passage of the rod (24) and is slidably mounted on the rod (24) between the two flanges (26, 28).   5. Actuator according to any one of claims 1 to 4, characterized in that the first thrust means comprise: a first conduit (48) for supplying fluid under pressure in the chamber (42) furthest from the opening (18) of the enclosure (12), and - a first spring (50) spacing the first piston (22) relative to the first set of stops (38, 40).   6. Actuator according to any one of claims 3 to 5, characterized in that the second thrust means comprise: - a second pipe (52) for supplying fluid under pressure in the chamber (46) between the pistons ( 22, 30), and - a second spring (54) axially spacing the second piston (30) relative to the opening (18) of the enclosure (12).   7. Actuator according to claims 5 and 6 taken together, characterized in that it comprises: - a first electrical valve (84) fluid passage to the first pipe (48) can take a first position alone driving the positioning of the first piston (22) in one of its two stable positions relative to the first set of stops (38, 40), and a second position alone causing the positioning of the first piston (22) in the other stable position relative to at the first set of abutments (38, 40), and - a second fluid passage valve (86) to the first conduit (52) which can assume a first position which alone causes the first set of abutments (38, 40) in one of its two stable positions relative to the enclosure (12), and a second position alone causing the positioning of the first set of stops (38, 40) in the other stable position relative to the enclosure (12).   8. Actuator according to claim 6 or 7, characterized in that it comprises a pipe (56) connecting the chamber (42) farthest from the opening (18) of the chamber (12) to the chamber (44) closest to this opening.   9. automatic shift device for a motor vehicle, characterized in that it comprises a gearbox (88) and an actuator (10) according to any one of claims 1 to 8 for the selection of a speed .