EP1554506A2

EP1554506A2 - Damper hydraulic bump stop for vehicle, damping system and method for using same

Info

Publication number: EP1554506A2
Application number: EP03778438A
Authority: EP
Inventors: Pierre De Frenne
Original assignee: Amortisseur Donerre
Current assignee: Amortisseur Donerre
Priority date: 2002-10-25
Filing date: 2003-10-23
Publication date: 2005-07-20
Also published as: AU2003285437A1; AU2003285437A8; FR2851808A1; WO2004040164A3; WO2004040164A2; WO2004040164B1; FR2851808B1

Abstract

The invention concerns a end-of-stroke hydraulic bumper stop for a damping system comprising a limit stop piston (10) integral with a cylinder rod (7) sliding in the damper body (1), including also a limit stop body (120) fixed at the upper end of the body (1), a cylindrical portion (103) of the limit stop piston (10) being urged to enclose and compress an oil volume (V) contained in an inner housing (12) of the limit stop body (120) upon compression displacement of the damper. A fraction of the oil volume (V) flows back between the piston (10) and the limit stop body (120), said fraction decreasing with the forward displacement of the limit stop piston (10), thereby generating a resistance to the increasing compression, as well as forming a high pressure oil film (F) between the piston (10) and the limit stop body (120) which lubricates the contact between the surfaces of those two components.

Description

Hydraulic shock absorber stop for vehicle, shock absorber system and method of use

The present invention relates to a hydraulic limit stop system for hydraulic shock absorbers of motor vehicles.

The function of an end-of-stroke stop is to dampen the stop of the damper cylinder rod when it sinks into the damper body and reaches the point of maximum compression. In fact, when the vehicle is in the reception phase of a bump or a hole, the jack rod sinks at high speed into the body of the shock absorber until, in certain cases, reaching the maximum of its travel. The presence of a stop must make it possible to prevent the shock absorber from abruptly "bottoming out". It is known in the prior art hydraulic shock absorbers provided with stops in damping material such as rubber, but this kind of stop resists poorly repeated and violent shocks.

It is known from patent application FR 0213644 in the name of the applicant, a shock absorber system provided with a rapid expansion system reacting to decreases or cancellations of the reaction force on the ground. Such a system is in particular provided with two pistons, an upper piston connected to a lower piston by means of an extension, the lower piston being integral with the jack rod. The upper piston forms, in its upper part, a hydraulic stop piston intended to trap and compress a volume of oil comprised in a stop body disposed at the upper end of the body of the shock absorber. The object of the present invention is to overcome the drawbacks of the prior art by proposing a stop allowing a progressive stop of the jack rod of the damper whatever the speed of insertion of the jack rod, which eliminates metal friction. against metal between the piston and the abutment body, and which retains damping characteristics which are substantially constant over time. This objective is achieved by a hydraulic limit stop for a shock absorber system comprising a stop piston integral with a jack rod sliding in the body of the shock absorber, also comprising a stop body fixed to the upper end of the shock absorber body, a cylindrical portion of the stop piston trapping and compressing a volume of oil contained in an open internal housing of the stop body during the compression movement of the shock absorber, characterized in that the internal housing of the abutment body is symmetrical in revolution and provided with a frustoconical inlet portion, followed by several frustoconical portions, of decreasing taper, the portion near the bottom of the housing being cylindrical with a diameter slightly greater than the diameter of the abutment piston, to allow , during the movement of driving the stop piston into the housing, that a fraction of the volume of oil contained in the body of bu tee can flow back between the piston and the abutment body, this fraction decreasing as the abutment piston advances, which makes it possible to generate an increasing resistance to sinking, which also allows the formation of 'a film of high pressure oil between the piston and the stop body which lubricates the contact between the surfaces of these two parts during alternating and repeated movements of the stop piston in the housing of the stop body.

According to another particularity, the abutment body is a cylinder of revolution with a diameter substantially equal to the inside diameter of the shock absorber body, a flat being formed from the lower end of the abutment body until a radial hole opening out on a second vertical bore located at the top of the stop body, in the center of the latter, the two holes communicating with each other, all of the two holes and the flat materializing a free passage for the oil from the body to the head of the shock absorber .

According to another particular feature, the stop piston is integrated into a rapid expansion system, the stop piston being linked to a lower piston by means of an extension, the lower piston being integral with the jack rod. According to another particular feature, the stop piston has at its lower end an enlarged portion, of diameter substantially equal to the inside diameter of the body of the shock absorber, and provided with a plurality of vertical channels forming a free passage for the oil. According to another particular feature, the stop piston has at its lower end an open housing, a threaded portion of which serves as a means of fixing the extension, a non-return piston being interposed between the bottom of the housing and the extension, the anti-piston return being provided with a plurality of vertical channels which communicate with channels connecting the housing to the outside of the stop piston when the non-return piston is in the open position, thus forming a free passage for the oil.

According to another particular feature, the stop piston is provided with radial horizontal channels connecting the internal housing to the periphery of the stop piston. According to another particular feature, the stop piston is provided with a plurality of vertical channels connecting the bottom of the housing to the horizontal surface constituting the end of the stop piston close to the stop body.

According to another particular feature, the end of the stop piston close to the stop body is of frustoconical shape.

Another object of the invention is to provide a hydraulic shock absorber system provided with the hydraulic limit stop according to the invention, characterized in that the tail of the shock absorber comprises a tail body, comprising at one end a thread allowing the fixing of a tube, the thread opening onto a substantially cylindrical housing, a piston being secured at one of its ends to a jack rod held in the tube and at its other end of a hook, said piston sliding in the housing, and in that a plurality of conical spring washers are interposed between the bottom of the housing and the piston, the expansion of said washers pushing the piston during the expansion phase of the damper, the piston driving the rod cylinder in its movement to allow the operation of the rapid expansion system. According to another particularity, the conical spring washers are mounted in opposition two by two.

According to another particular feature, the number of conical spring washers is between 5 and 10. Another object of the invention is to provide an oil damper system comprising a body in which slides a piston mounted on a first end of a first rod, the shock absorber system comprising a spring mounted co-axially with respect to the body to pass on the weight of the vehicle to a cup secured to the second end of the first rod, the piston consisting of a sub- upper piston and a lower sub-piston connected to each other by an extension, and delimiting an upper chamber, an intermediate chamber and a lower chamber, characterized in that the upper sub-piston comprises a recess in which a check valve is housed -return surmounted by a spring, which makes it possible to reduce or increase a free passage located between the upper chamber and the lower chamber, respectively when the weight reflected by the spring and the reaction force of the soil applied to the tail of the shock absorber system are significant, and when the sum of these forces tends to cancel or when these forces are weak, the opening of the passage allows rapid relaxation of the shock absorber system.

According to another particular feature, the passage of the rapid trigger is reduced or increased, thanks to an adjustment system located in the tail of the shock absorber system, by adjusting the position of the rod relative to the piston. According to another particular feature, the adjustment system consists of two inflation valves filled with pressurized air, each in connection with a cavity, the emptying or filling of said cavities by the inflation valves acting on a pneumatic piston connected to the rod.

Another object of the invention is to propose a method of using a rapid expansion damping system and hydraulic stop, characterized in that it consists in installing on the vehicle rapid expansion damping systems controlled by pressure pneumatic, this pressure can be modified using two valves and to be determined using these rapid expansion dampers provide optimum pressure values suited to the vehicle and the terrain encountered, and then to replace the pneumatically controlled rapid expansion damping system with a spring controlled rapid expansion system comprising a number of "Belleville" washers determined as a function force characteristics corresponding to the determined pneumatic pressure.

The invention, with its characteristics and advantages, will emerge more clearly on reading the description made with reference to the accompanying drawings in which: - Figure 1 shows a front view of a shock absorber system;

- Figure 2 shows a sectional view of the damper system according to the invention according to the plane A-A of the figure

1; - Figures 3 to 5 each show a detail view of Figure 2;

- Figure 6 shows a perspective view of the head of the damper system according to the invention;

- Figure 7 shows a sectional view of the head along the plane B-B of Figure 6;

- Figure 8 shows a perspective view of the compression valve of the damper system according to the invention;

- Figure 9 shows a perspective view of the low speed adjustment screw of the damper system according to the invention;

- Figure 10 shows a sectional view of the high speed adjustment screw of the shock absorber system according to the invention;

- Figure 1 1 shows a bottom view of the non-return piston of the shock absorber system according to the invention; - Figure 12 shows a sectional view of the inflation valve of the shock absorber system according to the invention;

- Figure 13 shows a front view of the stop body; - Figure 14 shows a sectional view of the abutment body according to the plane CC of Figure 15;

- Figure 15 shows a top view of the stop body;

- Figure 16 shows a front view of a first alternative embodiment of the stop piston, more particularly adapted to a damper located at the front of a vehicle;

- Figure 17 shows a sectional view of the variant of the stop piston according to the plane DD of Figure 16; - Figure 18 shows a top view of the stop piston shown in Figure 16;

- Figure 19 shows a front view of a second alternative embodiment of a stop piston, more particularly adapted to a shock absorber located at the rear of a vehicle;

- Figure 20 shows a sectional view along the plane EE of Figure 19 of the second variant of the stop piston according to the invention;

- Figure 21 shows a side view of the stop piston shown in Figure 19;

- Figure 22 is composed of two half-views each representing a state of depression of the stop piston in the stop body;

- Figure 23 shows a front view of the non-return piston; - Figure 24 shows a sectional view of the non-return piston according to the plane FF of Figure 24;

- Figure 25 shows a sectional view of a variant of the shock absorber tail.

The damper system of the present invention, visible in particular in Figures 1 to 5, comprises a substantially vertical cylindrical body (1). It is screwed at its upper end to a head (2), and at its lower end to a plug (6). The head (2), visible in particular in FIGS. 3 and 6, comprises a hook (21) making it possible to fix the shock absorber system according to the invention to the vehicle which it is desired to equip with the shock absorber system according to invention. The head (2) also comprises a reservoir (22), visible in particular in FIGS. 3, 6 and 7, comprising an opening (23) connected to the body (1) of the damper system by a channel (24). This opening (23) is provided for the insertion of adjustment screws, low speed (4) or high speed (5), of compression, embodiments of which are shown respectively in FIGS. 9 and 10. These adjustment screws (4, 5) more or less close the opening (23) during compression.

A stop body (120) having an inner housing (12) is fixed in the upper body (1) of the shock absorber. This abutment body, visible in particular in FIGS. 13, 14 and 15, is a cylinder of revolution with a vertical axis, an upper end of which forms a collar (121) intended to be clamped between the head (2) and the body ( 1) of the damper to allow positioning and maintenance of said abutment body (120). Near the collar (121), below it, is arranged a radial bore (122) which communicates with a vertical bore (123) located in the center of the upper surface of the abutment body (120). The assembly of these two holes forms a channel which allows the oil contained in the body (1) to flow back towards the head (2) of the damper, the latter being traversed by a channel (24). For this purpose, a flat (124) is produced on the outer surface of the abutment body, this flat (124) covering the height between the collar (121) and the lower end of the abutment body (120). The flat (124) is arranged in such a way that the bore (122) is pierced on the surface thereof, in an orthogonal direction. A space is thus created between the internal surface of the body (1) of the damper and the flat (124), which materializes a free passage for the oil from the channel (24) of the head (2) of the damper towards the upper chamber (S) of the body (1), via the holes (122, 123), so that the adjustment screw (4, 5) for compressing the head is connected to said upper chamber (S). A substantially cylindrical rod (7), held in a tube (71), slides in the body (1) using guides, not shown. The rod (7) ends at its upper end with a portion of substantially rectangular section (75), open at the top. The rectangular section of the rod (7) is less than its cylindrical section. The outside diameter of the tube (71) is smaller than the inside diameter of the body (1) of the damper system so that it can slide freely inside said body (1).

The tube (71) is screwed, at its upper end, to an annular piece (1 1) of outside diameter substantially equal to the inside diameter of the body (1) of the damper system. A projection (1 12) is formed on this annular part (11), in the axis of the tube (71). Said projection (112) is screwed into the lower part of an extension (8), itself screwed, in its upper part, into a stop piston (10) which is provided with a tapped portion (106). The stop piston (10) in its lower part (105) is provided with an enlarged annular portion (105). The outside diameter of this enlarged portion (105) of the stop piston (10) is substantially equal to the inside diameter of the body (1) of the shock absorber system.

The annular part (11) is crossed in the axis of the tube by a hole receiving, in its lower part, the upper end of the tube (71) and, in its projecting part (1 12), the upper end of the rod (7). The upper end of the rod (7) being of smaller section than the hole passing through the annular part (11), two vertical channels (113) are included on each side of the rectangular section part (75) of the rod

(7). A non-return valve (9) is inserted into a housing (104) of the stop piston (10) located at its enlarged part (105). This non-return valve (9) comprises a projection (92) around which is inserted a spring, not shown, which is held between the non-return valve (9) and the upper surface of said housing (104). This spring keeps the non-return valve (9) pressed against a compression valve (13) inserted in the top of the extension (8). This compression valve (13), visible in particular in FIG. 8, prevents, under normal conditions of use, that is to say when the weight and the reaction force are important, an important passage of oil in the shock absorber system.

The outside diameters of the extension (8) and of the main body of the stop piston (10) are smaller than the inside diameter of the body (1) of the damper system so that it can slide freely inside said body (1).

The tube (71) is screwed, at its lower end, to the body (32) of the tail (3) of the damper system. A hook (31) is screwed to the tail (3) to allow the shock absorber system to be fixed to the wheel of the vehicle to be fitted with said system.

The upper chamber (S) of the body (1) of the damper system is delimited, at the top, by the stop body (12), and at the bottom by the upper surface of the widened part (105) of the stop piston ( 10). Similarly, the lower surface of the enlarged part (105) of the stop piston (10) and the upper surface of the annular part (11) delimit the intermediate chamber (M) of the body (1). Finally, the lower surface of the annular part (11) and the upper surface of the plug (6) define the lower chamber (I) of the body (1). All the chambers (S, M, I), as well as the rod (7), are filled with oil. The enlarged part (105) of the stop piston (10) comprises a plurality of vertical channels (101) which allow the passage of oil between the upper chamber (S) and the intermediate chamber (M).

The non-return valve (9) also comprises a plurality of vertical channels (91) which make the connection between the extension (8) and the recess (104) of the stop piston (10). The stop piston (10) has channels (102, 108) which connect the housing (104) and the upper chamber (S).

The annular piece (11) comprises a plurality of vertical channels (11 1) located between the intermediate chamber (M) and the lower chamber (I), and closed by a preload washer (1 15) defining the compression characteristics of the system damper. Indeed, this washer (115) exerts a determined closing force that the oil pressure in the intermediate chamber (M) must overcome so that the oil is expelled towards the lower chamber (I), for the displacement of the stop piston (10) in the direction of compression.

A plurality of radial channels (72) are formed on the tube (71), at the level of the lower chamber (I). These radial channels (72) open onto vertical channels (73) formed between the tube (71) and the rod (7), which open, at their upper end, onto the channels (113) between the rectangular section (75 ) of the rod (7) and the projecting part (112) of the annular part (11).

When the reaction force and the weight become weak or when their sum tends to cancel out, the oil from the lower chamber (I) rises to the upper chamber through the radial channels (72) of the tube (71) then by the vertical channels (73) formed between the tube (71) and the rod (7). The oil then flows through the vertical channels (113) included on each side of the rectangular section (75) of the rod (7), then, through the extension (8), the compression valve (13 ), the vertical channels (91) of the non-return valve (9), the housing (104) of the stop piston (10), and finally the channels (102, 108) of the stop piston (10). If the oil exerts sufficient pressure, the compression valve (13), which comprises two openings (131, FIG. 8) with a diameter larger than the diameter of the channels (91) of the non-return valve (9), lifts , with the non-return valve (9), to allow a larger flow of oil to circulate in the housing (104) of the stop piston (10), from which the oil is then discharged through the radial channels (102) of the stop piston (10). In this way, the relaxation is therefore much faster, and the piston descends very quickly into its maximum elongation position, that is to say when the annular part (11) abuts against the plug (6).

The upper part of the tail (3) is integral with a cup (not shown) serving as a support for a spring (not shown) which reflects the weight of the vehicle supported by the head on the lower end of the rod (7) .

The tail (3) consists of the tail body (32) in which slides a pneumatic piston (33) guided by a tail guide (34). The fixing hook (31) is screwed into the pneumatic piston (33). Two cavities (35, 37) are respectively included between the tail body (32) and the tail piston (33), and between the tail piston (33) and the tail guide (34). Two spaces (36, 38), formed in the tail body (32) and each located opposite one of the cavities (35, 37), each allow to accommodate an inflation valve (15), visible in particular in FIG. 12. Each of the inflation valves (15) makes it possible to introduce air under several bars and thus makes it possible to vary the volume of the cavities (35, 37), which allows, by displacement of the piston (33) between the respective abutment surfaces (320, 340) of the tail body (32) and the tail guide (34), acting on the height of the rod (7) relative to the annular part (11 ). This system thus makes it possible to regulate the flow rate of oil passing from the vertical channels (73) formed between the tube (71) and the rod (7), to the vertical channels (113) included on each side of the part of rectangular section ( 75) of the rod (7), and therefore of regulating the speed of the trigger.

The hydraulic stop piston (10a, 10b), more particularly visible in particular in FIGS. 16, 17, 18, 19, 20 and 21, is a piston of which an upper part (103) is of cylindrical external shape surmounted by a portion (107) of frustoconical shape. The stop piston (10a, 10b) is intended to cooperate with the stop body (120). The abutment body (120) has at its lower end a housing (12) opening at the lower end of the abutment body (120) and closed at the opposite end. The internal surface of the housing (12) is a surface of continuous revolution composed of several sections (12a, 12b, 12c, 12d). The section (12d) furthest from the opening of the housing (12) is cylindrical in shape. The other three sections (12a, 12b, 12c) are of frustoconical shape, and the conicity of these three sections is different, this being all the greater the closer the section concerned is to the opening of the housing (12 ). The cylindrical section (12d) constitutes the smallest diameter of the housing (12). This diameter is very close to the outside diameter of the stop piston (10a, 10b), but slightly greater than the latter. Thus, when the jack rod (7) is inserted at high speed into the body (1), for example when the vehicle approaches the reception of a bump or a hole, the stop piston (10a, 10b) will penetrate inside the housing and come to trap a volume (V) of oil contained in the housing (12 ). As it progresses inside the housing (12), the stop piston (10a, 10b) will gradually compress the volume (V) of oil contained in the housing (12), thereby creating resistance to the progressive depression of the stop piston (10a, 10b). The progressiveness of the resistance to depression of the stop piston (10a, 10b) is ensured by virtue of the profile of the housing (12), as visible in FIG. 12. In fact, the conical sections (12a, 12b, 12c) close of the opening of the housing (12) create sufficient space between the external surface of the stop piston (10a, 10b) and the internal surface of the housing (12) for a part of the oil contained in the housing (12 ) may flow back out of it. As the stop piston (10a, 10b) progresses in the housing (12), the volume of refluxing oil becomes smaller and smaller, thus gradually increasing the resistance to depression of the stop piston (10a, 10b). When the piston approaches the cylindrical portion (12d) of the housing (12), the space remaining between these two parts, resulting from a difference between the internal diameter of the housing (12) and the external diameter of the stop piston (10a, 10b), allows the formation of an oil film (F) refluxing at very high pressure. This oil film (F) then plays the role of lubricant and makes it possible to avoid metal against metal friction during repeated movements of the stop piston (10a, 10b) inside the housing (12) of the stop body. (120). The very low compressibility of the oil allows very high resistance to be obtained at the end of the stroke.

Figures 6, 7 and 8 on the one hand, and Figures 9, 10 and 11 on the other hand, respectively represent a first and a second variant of the stop piston (10a, 10b). The first variant (10a) of the stop piston is more particularly adapted to a shock absorber intended for a wheel located at the rear of the vehicle. The second variant (10b) is more particularly adapted to a shock absorber intended for a wheel located at the front of the vehicle. The two stop pistons (10a, 10b) have many characteristics municipalities, including the cylindrical upper part (103), surmounted by a frustoconical portion (107). The lower part of the stop piston (10a, 10b) is a substantially cylindrical portion (105), of diameter slightly smaller than the inside diameter of the body (1) of the shock absorber. This cylindrical portion (105) is crossed by a plurality of vertical channels (101) allowing the passage of the oil. At the lower end of the stop piston (10a, 10b) is the open cylindrical housing (104). A portion close to the opening of the housing (104) has a thread (106) which allows the extension of the extension (8). A portion close to the bottom of the housing, of diameter adapted to the non-return piston (9), is visible in FIGS. 11, 23 and 24. The first variant of the stop piston (10a) comprises above the lower cylindrical portion (105) four radial holes which materialize four channels (102) connecting the housing (104) outside the stop piston. The second variant of the stop piston (10b) comprises four vertical bores (108) arranged on the same diameter of the upper surface of the frustoconical portion (107). These four holes (108) are equidistant and open into the housing (104). For the two variants of the stop piston (10a, 10b), the channels (respectively 102 and 108) are used for the transit of the oil during the expansion phase of the damper following the compression phase. The channels (102, 108) make it possible to double the flow rate passing through the channels (101) during the expansion phase, when the non-return piston (9) is in the open position. In the case of the stop piston (10a) of the first variant, the channels (102) are horizontal and the oil is discharged at the periphery of the stop piston (10a) during the expansion phase. In the case of the stop piston of the second variant (10b), the oil flowing in the channels (108) during the expansion phase opens into the housing (12) of the stop body (120). This has the effect of greatly reducing the resistance to the withdrawal movement of the stop piston (10b) caused by the volume of oil under high pressure contained in the housing (12), thus allowing rapid withdrawal of the stop piston (10b ).

A variant of a shock absorber system provided with a rapid expansion system and a hydraulic stop, visible in FIG. 25, consists in: use washers (39) conical springs in the tail (3) of the shock absorber. In this configuration, the tube (71) is screwed into a thread (320) located at one end of the tail body (32a). The tail body (32a) is of substantially tubular shape and the thread (320) opens into a housing (321) substantially cylindrical with a diameter greater than that of the thread (320). The housing (321) accommodates a piston (33a) provided with a thread (330) intended for fixing the jack rod (7). At one end of the piston (33a), opposite the internal thread (330), the hook (31) is screwed. Between the piston (33a) and the hook (31) is interposed a secondary piston (33b) which slides in a guide (34a) screwed on the tail body (32a). The secondary piston (33b) closes the housing (321) of the tail body (32a). Between the bottom of the housing (321) and the piston (33a) is interposed a plurality of washers (39) conical springs. These washers (39) conical springs, called "Belleville", are mounted in opposition two by two and are all identical. This assembly allows the addition of the elementary deflections of the washers (39). These spring washers (39) ensure an operation identical to that of the shock absorber system using the pneumatic piston (33), visible in FIG. 5. In fact, the conical spring washers (39) are compressed when an effort Compression is applied to the damper and relax when the ground reaction force tends to cancel out. By relaxing, the washers (39) push the piston (33a). The latter being integral with the cylinder rod (7), it causes a displacement of the cylinder rod (7) relative to the tube (71). This movement allows the rapid expansion system to operate. The number and dimensions of the washers (39) are variable and depend on many factors (position of the shock absorber, weight and type of vehicle, behavior of the desired shock absorber, etc.) The thickness of the washers (39) conical springs used depends on the admissible effort; the number of washers (39) will depend, among other factors, on their thickness and the desired travel. The number of washers (39) conical springs used will be for example eight. The diameter outside of the washers (39) will be slightly smaller than the inside diameter of the housing (321).

The first variant of rapid expansion consisting in using an air pressure disposed between the two cavities (35, 37), as shown in FIG. 12, to allow the speed of relaxation to be adjusted, is generally used in test and adaptation phases of the characteristics of the shock absorber to the vehicle and to the path encountered by the vehicle. Once the value of the pneumatic force has been determined in order to obtain an optimal result of rapid expansion, the pneumatic principle damper is replaced by a "Belleville" damper with washers, the physical characteristics of which have been determined as a function of the optimum pressure determined. on the pneumatic rapid expansion damper. This therefore makes it possible to have an easy, reliable test and development system which takes account of the realities on the ground and to quickly replace this test system with a mechanical system enduring for long-term use or in competition.

It should be obvious to those skilled in the art that the present invention allows embodiments in many other specific forms without departing from the scope of the invention as claimed. Therefore, the present embodiments should be considered by way of illustration but may be modified in the field defined by the scope of the appended claims.

Claims

1. Hydraulic end stop for a shock absorber system comprising a stop piston (10a, 10b) secured to a cylinder rod (7) sliding in the body (1) of the shock absorber, also comprising a stop body (120) fixed to the upper end of the body (1) of the shock absorber, a cylindrical portion (103) of the stop piston (10a, 10b) imprisoning and compressing a volume of oil (V) contained in a housing internal (12) open of the stop body (120) during the compression movement of the shock absorber, characterized in that the internal housing (124) of the stop body (120) is symmetrical of revolution and provided with a portion of frustoconical inlet (12a), followed by several frustoconical portions (12b, 12c), of decreasing conicities, the portion (12d) close to the bottom of the housing (12) being cylindrical with a diameter slightly greater than the diameter of the stop piston (10a, 10b), to allow, during the movement of the thrust piston (10a, 10b) into the housing (12), that a fraction of the volume of oil (V) contained in the thrust body (120) can flow back between the piston (10a, 10b) and the stop body (120), this fraction decreasing as the stop piston (10a, 10b) advances, which makes it possible to generate resistance to increasing depression, which also allows the formation of a film of oil (F) at high pressure between the piston (10a, 10b) and the thrust body (120) which lubricates the contact between the surfaces of these two parts during the alternating and repeated movements of the stop piston (10a, 10b) in the housing (12) of the stop body (120).

2. Hydraulic end stop for a shock absorber system according to claim 1, characterized in that the stop body (120) is a cylinder of revolution with a diameter substantially equal to the internal diameter of the body of the shock absorber, a flat (124) being made from the lower end of the stop body to a radial bore (122) opening onto a second vertical bore (123) located at the top of the stop body, at center of the latter, the two holes (122, 123) communicating with each other, all of the two holes and the flat (124) materializing a free passage for the oil from the body to the head of the shock absorber (2).

3. Hydraulic end stop for a shock absorber system according to claim 1 or 2, characterized in that the stop piston (10a,

10b) is integrated into a rapid expansion system, the stop piston (10a, 10b) being linked to a lower piston (5) via an extension (8), the lower piston (5) being integral with the cylinder rod (7).

4. Hydraulic end stop for a shock absorber system according to claim 3, characterized in that the stop piston comprises at its lower end an enlarged portion (105), of diameter substantially equal to the internal diameter of the body (1) of the shock absorber, and provided with a plurality of vertical channels (101) forming a free passage for the oil.

5. Hydraulic end stop for a shock absorber system according to claim 4, characterized in that the stop piston (10a, 10b) comprises at its lower end an open housing (104) of which a threaded portion (106) serves means for fixing the extension (8), a non-return piston (9) being interposed between the bottom of the housing (104) and the extension (8), the anti-return piston (9) being provided with a plurality vertical channels (90) which communicate with channels (102, 108) connecting the housing (104) to the exterior of the stop piston (10a, 10b) when the non-return piston (9) is in the open position, forming thus a free passage for the oil.

6. Hydraulic end stop for a shock absorber system according to claim 5, characterized in that the stop piston (10a) is provided with radial horizontal channels (102) connecting the interior housing (104) to the periphery of the piston stop (10a).

7. Hydraulic end stop for a shock absorber system according to claim 5, characterized in that the stop piston (10b) is provided with a plurality of vertical channels (108) connecting the bottom of the housing (104) to the horizontal surface constituting the end of the stop piston (10a, 10b) close to the stop body (120).

8. Hydraulic end stop for a shock absorber system according to one of claims 1 to 7, characterized in that the end of the stop piston (10a, 10b) close to the stop body (120) is of the shape frustoconical.

9. Hydraulic shock absorber system provided with the hydraulic end stop according to one of claims 1 to 8, characterized in that the tail (3) of the shock absorber comprises a tail body (32a), comprising one end a thread (320) allowing the fixing of a tube (71), the thread (320) opening onto a substantially cylindrical housing (321), a piston (33a) being secured to one of its ends of a cylinder rod (7) held to the tube (71) and at its other end a hook (31), said piston (33a) sliding in the housing (321), and in that a plurality of conical spring washers (39 ) are interposed between the bottom of the housing (321) and the piston (33a), the relaxation of said washers (39) pushing back the piston (33a) during the relaxation phase of the shock absorber, the piston (33a) driving the rod cylinder (7) in its movement to allow the operation of the quick release system.

10. Shock absorber system according to claim 9, characterized in that the conical spring washers (39) are mounted in opposition two by two.

11. Shock absorber system according to claim 10, characterized in that the number of conical spring washers (39) is between 5 and

10.

12. Oil shock absorber system comprising a body (1) in which slides a piston (8, 9, 10, 11) mounted on a first end of a first rod (7), the shock absorber system comprising a spring mounted co-axially with respect to the body (1) to transmit the weight of the vehicle on a cup secured to the second end of the first rod (7), the piston (8, 9, 10, 11) being made up of an upper sub-piston (10) and a lower sub-piston (11 ) connected together by an extension (8), and delimiting an upper chamber (S), an intermediate chamber (M) and a lower chamber (I), characterized in that the upper sub-piston (10) comprises a recess ( 104) in which is housed a non-return valve (9) surmounted by a spring, which makes it possible to reduce or increase a free passage (131) located between the upper chamber (S) and the lower chamber (I), respectively when the weight reflected by the spring and the ground reaction force applied to the tail (3) of the shock absorber system are significant, and when the sum of these forces tends to cancel out or when these forces are weak, opening of the passage (131) allowing rapid relaxation of the shock absorber system.

13. Oil shock absorber system according to claim 12, characterized in that the passage (131) of the quick release is reduced or increased, thanks to an adjustment system located in the tail (3) of the shock absorber system, by adjusting the position of the rod (7) relative to the piston (8, 9, 10, 11).

14. Oil shock absorber system according to claim 13, characterized in that the adjustment system consists of two inflation valves (15) filled with air under pressure, each in connection with a cavity (35, 37), emptying or filling said cavities (35, 37) by the inflation valves acting on a pneumatic piston (33) connected to the rod.

15. Method for using a quick release damper system and hydraulic stop, characterized in that it consists of installing on the vehicle quick release damping systems controlled by pneumatic pressure (35, 37), this pressure can be modified using two valves (15) and to determine, thanks to these quick release shock absorbers, optimal pressure values adapted to the vehicle and the terrain encountered, then to replace the pneumatically controlled quick release shock absorber system with a rebound system fast ordered by spring comprising a number of “Belleville” washers determined according to the force characteristics corresponding to the determined pneumatic pressure.