Hydraulic end-of-stroke stop for progressive inertia suspension.

Abstract

The invention relates to a hydraulic suspension end stop (1) for a motor vehicle, comprising a compression chamber (2) designed to compress under the effect of a compressive force applied by a piston (3) moving under load, the compression chamber (2) being connected to a reservoir (4) by an inertial fluid circuit (5), the compression of the compression chamber (2) expelling fluid towards the reservoir (4) via the inertial circuit (5), the inertial circuit (5) allowing the fluid to move with a variable hydraulic inertia depending on the distance (D1) traveled by the piston (3) during the application of the stop (1). (Figure 2)

Description

Title of the invention: Hydraulic end-of-stroke stop for suspension with progressive inertia.

[0001] The technical field concerns suspension end stops as well as motor vehicles equipped with such hydraulic end stops.

[0002] Motor vehicles comprise, for each wheel, a suspension comprising a suspension spring and a telescopic shock absorber which brakes the movements of the wheel. The suspension further comprises an end-of-travel stop provided to quickly stop the travel of a suspension in the event of a significant impact suffered by the suspension due to an obstacle, for example. The stops are important because they allow the stiffness of a shock absorber to be adapted to improve the filtering of vibrations coming from small amplitudes, the remaining energy, resulting from a high speed generating a strong travel, being managed by the end-of-travel stop.

[0003] Conventionally, an end-of-travel stop is generally made of an elastomer buffer, which provides poor comfort to the vehicle. Also, to improve comfort, there are hydraulic inertial stops which allow the suspension to be stopped more gradually at the end of the travel. An inertial stop typically comprises a piston compressing a chamber filled with a liquid which expels hydraulic fluid into an inertia pipe towards a fluid reservoir. An inertial stop is thus capable of producing a hydraulic inertia force, that is to say that it opposes a hydraulic inertia in response to a request. This hydraulic inertia, denoted I, can be calculated from the following formula:

[0004] (Sp^ I = pLs\ — )

[0005] in which p is the density of the fluid used, s is the section of the inertia pipe, Sp is the section of the piston of the stop and finally L represents the length of the inertia pipe.

[0006] While inertial stops provide a definite increase in comfort, they are not always suitable for all types of roads and / or all obstacles, and compromises must be made to obtain acceptable comfort. In fact, known inertial stops generally have a fixed inertia that does not allow the behavior of the stop to be adapted to the road and to the obstacles encountered on the vehicle's path. Thus, while inertial stops provide good filtering of jolts, in certain situations, the filtering is carried out to the detriment of body handling. For example, known inertial stops cause very significant body surges that can cause problems on certain bad roads. roads or speed bump type obstacles. Experience has shown that most of the disadvantages of an inertial stop originate from the fact that their response is independent of the suspension travel.

[0007] Thus, there is a need for a solution to improve the behavior of an inertial stop by making it possible to modify the inertia of the inertial stop.

[0008] The object of the present invention is to overcome the problems set out above. In this technical context, one aim of the present invention is to provide a hydraulic end-of-travel stop having variable inertia depending on the stress.

[0009] To this end, the present invention relates to a hydraulic end-of-travel stop for a motor vehicle suspension, comprising a compression chamber designed to compress under the effect of a compression force applied by a piston moving under the effect of a stress, the compression chamber being connected to a reservoir by an inertial circuit, the compression of the compression chamber expelling fluid towards the reservoir by the inertial circuit, the inertial circuit allowing the displacement of the fluid with a variable hydraulic inertia depending on the distance traveled by the piston during the stress on the stop.

[0010] The invention finally relates to a motor vehicle comprising at least one end-of-travel stop according to the invention.

[0011] Thus, the hydraulic stop according to the invention makes it possible to modulate the inertia as a function of the distance traveled by the piston, that is to say as a function of the stress. Thus, the hydraulic inertia of the stop according to the invention is not fixed but automatically adapted to offer better behavior and in particular by improving road holding. During the same stress, the inertia varies while the piston moves to compress the compression chamber. Thus, the stop according to the invention offers more progressive behavior than a known inertial stop.

[0012] According to one embodiment of the invention, the hydraulic inertia of the inertial circuit varies as a function of the distance traveled by the piston by modifying the length of the inertial circuit traveled by the fluid.

[0013] Advantageously, the length of the inertial circuit traveled by the fluid increases when the distance traveled by the piston increases.

[0014] According to one possibility, the inertial circuit has a plurality of orifices designed to put the inertial circuit and the reservoir into fluid communication, the length of the inertial circuit traversed by the fluid being modifiable by the obstruction or the opening of at least one of the orifices. Thus, the obturation as a function of the position of the piston makes it possible to adapt the inertia during a reaction to a stress.

[0015] According to one embodiment of the stop, the piston separates the compression chamber and the reservoir arranged around a main axis, the inertial circuit being arranged at least partly around the reservoir and around the compression chamber.

[0016] Advantageously, the reservoir comprises a cylinder extending from the piston to a lower end closed by a flexible membrane, the cylinder being movable with the piston in a body of the stop between a rest position and a maximum compression position, the position of the lower end defining the length of the inertial circuit through which the fluid can travel.

[0017] Advantageously, the inertial circuit is arranged around the body of the stop winding from the membrane towards the piston when the latter is in the rest position.

[0018] According to one possibility, the stop comprises a mechanical stopper arranged in the compression chamber making it possible to limit the compression of the compression chamber.

[0019] The invention will be better understood on reading the detailed description which follows, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0020] [Fig-1] [Fig. 1] represents a longitudinal sectional view of an end-of-travel stop according to the invention in which the piston is in the rest position;

[0021] [Fig.2] [Fig.2] represents a longitudinal sectional view of the end-of-travel stop of [Fig.l] showing the piston in an intermediate position between the rest position and the maximum compression position;

[0022] [Fig.3] [Fig.3] represents a sectional view of the end stop of [Fig.l] showing the piston in the maximum compression position.

[0023] In these figures, the same references are used to designate the same elements.

[0024] A hydraulic end-of-travel stop 1 according to the invention, illustrated in FIGS. 1 to 3, is intended to equip a motor vehicle suspension.

[0025] The hydraulic stop 1 comprises a compression chamber 2 designed to compress under the effect of a compression force and printed by a piston 3 moving under the effect of a stress, symbolized by the arrow F in the figures. The compression chamber 2 is connected to a reservoir 4 by an inertial circuit 5 of hydraulic fluid. The compression of the compression chamber 2 expels fluid towards the reservoir 4 by the inertial circuit 5. In the hydraulic stop 1 according to the invention, the inertial circuit 5 allows the displacement of the fluid with a variable hydraulic inertia depending on the distance traveled by the piston 3 during the stress of the hydraulic stop 1 according to the invention. In other words, the inertia of the inertial circuit 5 depends on the position of the piston 3 in the body 10.

[0026] In the embodiment illustrated in the figures, the piston 3 separates the compression chamber 2 and the reservoir 4 which are both arranged around a main axis A. The reservoir 4 comprises a cylinder 6 which extends from the piston 3 and to a lower end 7 closed by a flexible membrane 8. The cylinder 6 forms a side wall of the reservoir 4. As illustrated in the figures, the cylinder 6 extends beyond the lower end 7 and is integral with an interface 9 connecting the stop 1 to an axle of the vehicle, in order to transmit the stresses of the road to the stop 1. The cylinder 6 is fitted in a hollow cylindrical body 10 and closed at one of its ends, in order to be movable in the body 10 between a rest position, illustrated in [Fig.l], and a maximum compression position, illustrated in [Fig.3]. As illustrated in the figures, the body 10 further delimits the compression chamber 2 between the piston 3 and the closed end of the body 10..

[0027] In the maximum compression position, the piston 3 is in contact with a mechanical stopper 11, arranged in the compression chamber 2, designed to limit the compression of the compression chamber 2. According to one possibility, the stopper 11 is made of elastomer to allow damping of the movement of the piston 3 when the latter comes into contact with the stopper 11.

[0028] In the hydraulic stop 1 according to the invention, the hydraulic inertia of the inertial circuit 5 varies as a function of the distance traveled by the piston 3 by modifying the length of the inertial circuit 5 through which the fluid can travel, i.e. the length traveled by the fluid in the inertial circuit 5 during the movement of the piston 3 compressing the compression chamber 2 following a stress up to the reservoir 4. In order to optimize the road behavior of a vehicle according to the invention, the length of the inertial circuit 5 through which the fluid can travel increases when the distance traveled by the piston 3 increases. Thus, the inertia of the stop 1 according to the invention is progressive and varies, in this case increases, during the reaction of the stop 1 reacting to a stress.

[0029] In the example illustrated in the figures, the inertial circuit 5 is arranged at least partly around the reservoir and around the compression chamber 2. For this purpose, the inertial circuit 5 is composed of a first part 12 formed of a first tube 13 wound in a spiral around the compression chamber 2, as well as a second part 14 formed of a second tube 15 wound in a spiral around the reservoir 4.

[0030] In the example illustrated in the figures, the first 13 and second 15 tubes have similar diameters. Alternatively, not illustrated, the two diameters are different.

[0031] The first part 12 extends from an upper end 16 of the compression chamber 2, arranged opposite the piston 3, and wraps around the body 10, that is to say around the compression chamber 2 towards the piston 3 in the rest position. second part 14 extends from a lower end 18, located between the interface 9 and the lower end 7 of the cylinder 6. The second part 14 wraps around the body 10 and the reservoir 4 towards the piston 3 in the rest position. Thus, the inertial circuit 5 wraps from the flexible membrane 8 towards the piston 3 when the latter is in the rest position. The first 12 and second 14 parts are connected by a tube portion 20 allowing the fluid to circulate from the compression chamber 2 in the first part 12 then in the second part 14 towards the reservoir 4.

[0032] In the embodiment illustrated in the figures, the inertial circuit 5 has a plurality of orifices 17 designed to put the inertial circuit 5 and the reservoir 4 into fluid communication. Each orifice 17 is positioned so that the distance traveled between the orifice 17 and the lower end 7 is specific to each orifice 17. For example, each orifice 17 is arranged so that from one orifice 17 to the next the fluid circulating in the inertial circuit 5 travels at least one spiral turn around the reservoir 4. Advantageously, the orifices 17 are aligned on the body 10 of the hydraulic stop 1, preferably aligned in a direction parallel to the main axis A.

[0033] In order to put the inertial circuit 5 and the reservoir 4 into fluid communication, the cylinder 6 is provided with at least one port 19 that can be positioned opposite at least one orifice 17 by a movement of the piston 3. Thus, depending on the position of the piston 3 in the body 10, a port 19 opens at least one orifice 17, while other orifices 17 are closed by the cylinder 6. Thus, the length of the inertial circuit 5 through which the fluid can travel is determined by the orifice(s) 17 open on the reservoir 4, which depends on the position of the piston 3 in the body 10. The position of the piston 3 in the body 10 is obviously linked to the distance traveled by the piston 3, from the rest position, during the stress.

[0034] For example, as illustrated in [Fig.l], the piston 3 is in the rest position, indicated by the reference L0. In this position, the port 19 opens at least the first 5 orifices 17 located on the first five spiral turns of the second part 14. The distance traveled by the fluid in the inertial circuit 5 is then minimal.

[0035] When the hydraulic stop is stressed, the piston 3 moves, causing the reservoir 4 to move and a movement of fluid in the inertial circuit 5. As illustrated in [Fig. 2], during the stress, the piston 3 moves and is now at the mark L1 indicated in Figures 2 and 3. With the piston 3, the lower end 7 of the cylinder 6 of the reservoir 4 moves in the body 10 and the light 19 is found opposite new orifices 17 while some of the orifices 17 open in the rest position are now closed. The distance traveled by the fluid in the inertial circuit 5 is now increased by the length corresponding to several turns of the spiral, in this case two turns of the spiral indicated by the arrow DI extending between the marks L0 and LL. The inertia corresponding to the inertial circuit 5, proportional to the travel length of the inertial circuit 5 is then greater than the minimum inertia.

[0036] When the piston 3 comes to rest on the stopper 11, at the mark Lmax, as illustrated in [Fig. 3], the port 19 is in a position which only allows the fluid to pass towards the reservoir 4 through a minimum number of orifices 17, so that the length which the fluid can travel through the inertial circuit 5 is increased compared to the rest position in [Fig. 1], by a distance corresponding to a maximum number of spiral turns, as indicated by the distance Dmax in [Fig. 3]. The distance Dmax also measures the distance between the marks LO and Lmax. Thus, just before coming to rest on the stopper 11, the inertia of the inertial circuit 5, proportional to the length which the fluid can travel through in the inertial circuit 5, is at its maximum.

[0037] Finally, in order to allow the return to the rest position once the stress on the stop 1 has ended, the piston 3 is, for example, provided with channels, not shown, allowing the rapid movement of the fluid from the reservoir 4 to the compression chamber 2 when the piston 3 is moved to its rest position. The channels are then provided with means for restricting the circulation of the fluid, such as one-way valves, not shown and only allowing the passage of the fluid in one direction, in this case from the reservoir 4 to the compression chamber 2. Once the stress has ended, the flexible membrane 8, deformed by the increased quantity of fluid present in the reservoir 4, then exerts pressure on the fluid present in the reservoir 4 to expel it towards the compression chamber 2 through, for example, the one-way channels.

[0038] Thus, the hydraulic stop 1 according to the invention is capable of modulating its response as a function of the stress it undergoes. The distance traveled by the piston during a stress modifies the inertia of the stop 1 by adapting the distance traveled by the hydraulic fluid in the inertial circuit 5. The stop 1 according to the invention therefore exhibits progressive behavior.

[0039] The invention is not limited to the embodiment of the hydraulic end-of-travel stop described above, only by way of example, but other embodiments can be designed by those skilled in the art without departing from the scope and scope of the present invention.

Claims

Claims

1. Hydraulic end-of-travel stop (1) for a motor vehicle suspension, comprising a compression chamber (2) designed to compress under the effect of a compression force applied by a piston (3) moving under the effect of a stress, the compression chamber (2) being connected to a reservoir (4) by an inertial circuit (5), the compression of the compression chamber (2) expelling fluid towards the reservoir (4) by the inertial circuit (5), the inertial circuit (5) allowing the displacement of the fluid with a variable hydraulic inertia depending on the distance (Dl, Dmax) traveled by the piston (3) during the stress on the stop (1), the hydraulic inertia of the inertial circuit (5) varying as a function of the distance (Dl, Dmax) traveled by the piston (3) by modifying the length of the inertial circuit (5) traveled by the fluid,characterized in that the inertial circuit (5) has a plurality of orifices (17) designed to put the inertial circuit (5) and the reservoir (4) into fluid communication, the length of the inertial circuit (5) through which the fluid can pass being modifiable by the obstruction or opening of at least one of the orifices (17),

2. Stop (1) according to claim 1, characterized in that the length of the inertial circuit (5) traveled by the fluid increases when the distance (Dl, Dmax) traveled by the piston (3) increases.

3. Stop (1) according to one of claims 1 or 2, characterized in that the piston (3) separates the compression chamber (2) and the reservoir (4) arranged around a main axis (A), the inertial circuit (5) being arranged at least partly around the reservoir (4) and around the compression chamber (2).

4. Stop (1) according to claim 3, characterized in that the reservoir (4) comprises a cylinder (6) extending from the piston (3) and up to a lower end (7) closed by a flexible membrane (8), the cylinder (6) being movable with the piston (3) in a body (10) of the stop (1) between a rest position (LO) and a maximum compression position (Lmax), the position of the lower end (18) defining the length of the inertial circuit (5) through which the fluid can travel.

5. Stop (1) according to claim 4, characterized in that the inertial circuit (5) is arranged around the body (10) of the stop (1) 8 winding from the flexible membrane (8) towards the piston (3) when the latter is in the rest position (LO).

6. Stop (1) according to one of claims 1 to 5, characterized in that it comprises a mechanical stop (11) arranged in the compression chamber (2) making it possible to limit the compression of the compression chamber (2).

7. Motor vehicle comprising at least one end-of-travel stop (1) according to one of claims 1 to 6.

Images