阅读说明：本技术 带有配备有压力限制阀门的行程末尾止挡的减振器 (Shock absorber with end-of-stroke stop equipped with pressure limiting valve ) 是由 A·卡瓦雷克 J·M·阿莱格尔 C·蒙泰伊 F·里盖勒 F·甘冈 于 2020-02-10 设计创作，主要内容包括：本发明涉及一种液压悬架减振器,所述液压悬架减振器包括减振器活塞,所述减振器活塞在内部管件(2)中滑动,并且所述减振器活塞在所述减振器的压缩期间向着命名为前方方向的轴向方向移动,所述减振器活塞延伸出止挡活塞(10),所述止挡活塞在所述减振器的行程末尾进入配备有穿孔(18)的止挡腔室(16)中,同时把流体压送出该止挡腔室(16)以使所述行程末尾减速,所述止挡腔室(16)包括侧穿孔(44),所述侧穿孔布置在所述止挡活塞(10)在所述止挡腔室(16)中的预限定行程(C0)之后,所述侧穿孔配备有用于限制该止挡腔室(16)中的压力的阀门(34)。(The invention relates to a hydraulic suspension damper comprising a damper piston which slides in an inner tube (2), and the shock absorber piston moves in an axial direction named the forward direction during compression of the shock absorber, the shock absorber piston extends beyond a stop piston (10) which, at the end of the shock absorber stroke, enters a stop chamber (16) provided with a through-hole (18), simultaneously pumping fluid out of the stop chamber (16) to decelerate the end of stroke, the stop chamber (16) including a side perforation (44), the side bore is arranged after a predefined stroke (C0) of the stop piston (10) in the stop chamber (16), the side bore is provided with a valve (34) for limiting the pressure in the stop chamber (16).)

1. Hydraulic suspension shock absorber comprising a shock absorber piston (4) sliding in an inner tube (2) and moving in an axial direction denominated forward direction (AV) during compression of the hydraulic suspension shock absorber, the shock absorber piston (4) extending a stop piston (10) entering a stop chamber (16) equipped with a through-hole (18) at the end of the stroke of the hydraulic suspension shock absorber while forcing fluid out of the stop chamber (16) to decelerate the end of the stroke, the stop chamber (16) comprising a side through-hole (44) arranged after a predefined stroke (C0) of the stop piston (10) in the stop chamber (16), the side through-hole being equipped with a valve (34) for limiting the pressure in the stop chamber (16), characterized in that the stop piston (10) is an annular piston comprising the perforation (18), which annular piston is fitted around the stop tube (12) while closing a stop chamber (16) arranged around the stop tube (12).

2. Hydraulic suspension shock absorber according to claim 1, characterized in that said valve (34) comprises a ball (36) urged by a calibrated spring (38) to close said side perforation (44).

3. Hydraulic suspension shock absorber according to claim 2, characterized in that said valve (34) comprises a sleeve (40) which implements an external guide for said ball (36) and said calibration spring (38).

4. Hydraulic suspension shock absorber according to any of the preceding claims, characterized in that the valve (34) is fixed inside the stop tube (12).

5. The hydraulic suspension shock absorber according to claim 3 and any one of the other claims, characterized in that the sleeve (40) of the valve (34) is fixed inside a tubular support (30) which is fitted in the stop tube (12).

6. Hydraulic suspension shock absorber according to any of the preceding claims, characterized in that the predefined stroke (C0) is between 15mm and 25 mm.

7. Hydraulic suspension damper according to any one of the preceding claims, characterized in that it comprises a calibration spring (38) for calibrating the valve (34), said calibration spring corresponding to an opening pressure for opening the valve (34), said opening pressure providing a retarding force between 200 and 400daN for retarding the stop piston (10).

8. Hydraulic suspension damper according to any one of the preceding claims, characterized in that it comprises a calibration spring (38) for calibrating the valve (34), said calibration spring corresponding to an opening pressure for opening the valve (34), said opening pressure being provided by a minimum compression speed of between 1.5m/s and 2.5 m/s.

9. A motor vehicle comprising a suspension damper, characterized in that it comprises a hydraulic suspension damper according to any one of the preceding claims.

Technical Field

The present invention relates to a hydraulic damper arranged with an end-of-stroke stop, and to a motor vehicle equipped with a damper of this type.

Background

Motor vehicles typically include a suspension for each wheel, the suspension including a suspension spring and a telescopic hydraulic shock absorber which decelerates the motion of the suspension. In particular, the shock absorber may comprise an end-of-stroke hydraulic stop which strongly decelerates the movement before the end of the stroke to avoid shocks on the rigid stop.

One known type of adjustable end-of-stroke hydraulic stop is shown in particular by document US-A-3207270, which comprises A rod which receives the axial thrust of the movement to be decelerated and causes the piston to slide in A cylinder having A series of perforations distributed over its length. A manual control system arranged outside the cylinder is able to adjust the closure of these perforations in order to adapt the deceleration level of the stop.

However, the adjustment of this type of stop does not include any automatic action capable of adapting to different loads.

Another known type of stop for a vehicle suspension damper is shown in particular by the document FR-a1-3050000, which comprises a jack-rod member comprising a damper piston at its lower end to implement the main damping, said damper piston extending downwards out of a bushing which at the end of the compression stroke fits around the inner tube of the stop.

The bushing comprises a series of perforations distributed axially and closed in succession during the introduction of the tube into the bushing in order to decelerate more and more the transfer of the fluid (coming from the outer chamber formed around the bushing) towards the chamber (inside the tube and in front of the piston). An increasingly higher deceleration of the shock absorber at the end of the compression stroke is obtained.

The thrust spring is arranged below the main piston, pressing slightly before the end of the stroke of said shock absorber on a nested plug (boisseau) axially sliding in a stop tube comprising additional perforations at different heights.

A control chamber arranged in the stop tube and below the nested plug comprises a restricted passage for the outward communication of fluid, so as to slow down the descending movement of the nested plug under the action of the thrust spring and the re-ascending movement of the nested plug under the action of the return spring.

In this way, when a large jump of the suspension is accidentally carried out for a lightly loaded vehicle, the rapid pressing of the thrust spring against the nested plug does not cause the nested plug (decelerated by the fluid of the regulating chamber) to descend in a slow dynamic. The perforations of the stop tube remain open to provide greater flexibility for the end-of-stroke stop, which results in greater comfort.

In the case of a loaded vehicle, the thrust spring frequently presses against the plug insert, which frequently causes the plug insert to drop, which closes the bore of the stop tube and at the same time hardens the end-of-stroke stop more strongly. Safety is obtained by avoiding the rear contact (piloting) of the suspension of the loaded vehicle. However, this type of stop comprising an adjustable nested plug controlled by the pressure of the thrust spring can present problems, in particular in the case of lightly loaded vehicles that do not move the nested plug, for the small amplitude of movement remaining at the beginning of the end-of-stroke stop, there is a high speed.

This occurs in particular when reaching the lateral road abutment forming the speed bump. A greater deceleration force is thereby obtained, which degrades comfort.

Furthermore, the nested plug system with the spring is relatively complex to implement, which causes costs.

Disclosure of Invention

The object of the invention is in particular to avoid these disadvantages of the prior art.

To this end, the invention provides a hydraulic suspension shock absorber comprising a shock absorber piston which slides in an inner tube and which during compression of the shock absorber moves in an axial direction denominated the forward direction, the shock absorber piston extending out of a stop piston which at the end of the stroke of the shock absorber enters a stop chamber equipped with a through-hole and at the same time forces fluid out of the stop chamber to decelerate the end of the stroke, the stop chamber being characterized in that it comprises a side through-hole arranged after a predefined stroke of the stop piston in the stop chamber, the side through-hole being equipped with a valve for limiting the pressure in the stop chamber.

The advantage of this shock absorber is that for light load vehicles, the valve opens when a small movement occurs at a higher speed at the beginning of the end-of-travel stop, limiting the pressure in the stop chamber. Once the perforation is exceeded, the valve is deactivated (neutralis), and the end of travel stops normal operation.

For large amplitude movements that occur at lower speeds, the pressure does not rise much at the beginning of the end of the stroke, the valve does not open, and the stop operates normally. An automatic adaptation of the end-of-travel stop is obtained in a simple and economical manner, which ensures comfort.

The hydraulic shock absorber according to the invention may also comprise one or more of the following features which may be combined with each other.

Advantageously, the valve comprises a ball which is urged by a calibrated spring to close the side perforation.

In this case, the valve advantageously comprises a sleeve (douille) which carries out an external guidance for the ball and the calibration spring.

In particular, the stop piston may be an annular piston comprising the perforation, which annular piston fits around the stop tube while closing a stop chamber arranged around the stop tube.

In this case, the valve is advantageously fixed inside the stop tube.

In particular, the sleeve of the valve can be fixed inside a tubular support which fits in the stop tube.

Advantageously, said predefined stroke is between 15mm and 25 mm.

Advantageously, the shock absorber comprises a calibration spring for calibrating the valve, said calibration spring corresponding to an opening pressure for opening the valve, the opening pressure providing a deceleration force for decelerating the stop piston between 200daN and 400 daN.

Advantageously, said shock absorber comprises a calibration spring for calibrating said valve, said calibration spring corresponding to an opening pressure for opening the valve, the opening pressure being provided by a minimum compression speed between 1.5m/s and 2.5 m/s.

The present invention is also directed to a motor vehicle including a suspension damper having any of the above features.

Drawings

The invention will be better understood and other features and advantages thereof will be more apparent from a reading of the detailed description given hereinafter by way of example and the accompanying drawings in which:

Figure 1 shows, in an axial section, a front portion of a shock absorber according to the prior art, near an end-of-stroke stop;

figure 2 shows the shock absorber according to the prior art, in the intermediate position of the end-of-stroke stop;

figure 3 shows the front part of the shock absorber according to the invention, near the end-of-stroke stop; and

figure 4 is a graph providing an example of the deceleration values of the shock absorber.

Detailed Description

Fig. 1 shows a telescopic shock absorber which operates in compression along a main axis towards a side usually denominated as front (indicated by arrow AV).

The shock absorber comprises a cylindrical inner tube 2 which houses a piston 4 (fixed at the end of a shock absorber rod 20) which slides sealingly and axially in the body to delimit a front chamber 6 and a rear chamber 22.

Piston 4 includes a reduced fluid passage 8 between front and rear chambers 6, 22 that decelerates its motion according to the direction of fluid passage and the velocity of the fluid relative to the velocity of shock rod 20.

The compensation chamber forms an annular volume arranged between the inner tube 2 and an outer envelope, not shown, which contains a pressurized gas and receives a fluid forced by a volume (which moves during compression operation and during the admission of the shock absorber rod 20 into said shock absorber).

The piston 4 extends at the front side beyond a circular bushing 10 which, before the end of the stroke, fits around an end-of-stroke stop tube 12 while closing an annular outer stop chamber 16 formed around the tube. The stopper tube 12 internally defines an inner chamber 26 and is fixed by its front end with a cap 14 which closes the front end of the inner tube 2.

The bush 10 comprises an annular outer boss 24 ensuring the guidance thereof in the inner tubular element 2, and a series of radial perforations 18, axially aligned and of increasing diameter towards the front.

Figure 2 shows the advancement of the liner 10 around the stop tube 12 in the outer stop chamber 16 with fluid forced from the calibrated cross-section bore 18 to the inner chamber 26 to effect a gradual deceleration of the advancement of the shock rod 20. The fluid then passes from the inner chamber 26 to the rear volume 22 of the piston 4 through its own reduced passage 8.

At the same time, as the rod 20 advances, the perforations 18 of the bush 10 progressively close, which progressively reduces the overall passage section of the fluid from the stop chamber 16 to the inner chamber 26 and increases the decelerating force, which becomes very great near the end of said stroke.

An increasingly gradual deceleration of shock absorber rod 20 is obtained, determined by the diameter and position of the through-hole 18 of the adapter sleeve 10.

Fig. 3 shows a valve 34 fixed inside a tubular support 30 which fits into the stopper tube 12 and is secured in position axially by a rear shoulder 32 which presses against the rear end of the stopper tube.

The valve 34 comprises, in radial succession from the outside: a radial perforation 44 passing through both the stopper tube 12 and the tubular support 30; a sphere 36; then, a compression-working helical calibration spring 38 is applied, which presses outwards on the ball to close the radial perforation.

A sleeve 40, fixed radially in the tubular support 30, which forms a guide for the guide spring 38 and the ball 36, comprises an internal shoulder towards the centre of the shock absorber, comprising a central perforation 42, which constrains the end of the spring to enable it to exert pressure on the ball.

Movement of the bushing 10 around the stop tube 12 before the predefined stroke C0 opens the radial bore 44, and the valve 34 may operate in an unloaded mode when the pressure in the stop chamber 16 exceeds a threshold (capable of retracting the ball 36 while compressing the calibration spring 38).

After the predefined stroke C0, the bushing 10 passes beyond the radial perforation 44 while closing it, the operation of the end-of-stroke stop no longer being dependent on the valve 34.

Fig. 4 shows the deceleration force F (on the vertical axis, in daN) for decelerating the attack stop as a function of the stroke C (in mm) from the start of the end-of-stroke stop for different displacement speeds (in m/s) of the piston 4. The predefined stroke C0 is 20 mm.

In particular, for a small speed of 0.1m/s, the force F is very weak up to a stop travel of about 35mm, said force then rising to about 200 daN. Conversely, for a greater speed of 5m/s, the force F rises rapidly to reach 500daN at 20mm, said force ending finally with about 700 daN. For speed values between 1.5m/s and 2.5m/s, at a stroke of 20mm, the force F exceeds 300daN, which is uncomfortable. This condition is obtained, for example, when reaching a bump-forming speed bump on the road, which provides a greater compression speed of the shock absorber with a smaller movement.

In this case, above a minimum force F0 of 300daN, the pressure in the stop chamber 16 is sufficiently great to open the valve 34 while compressing the spring 38. A correction 50 to the curve is obtained which limits the force F to 300daN up to the predefined travel C0. After this predefined stroke C0, the bushing 10 closes the perforation 44 of the valve 34, and the curve returns to its normal form.

In a variant, the pressure-limiting valve 34 can be arranged on other types of end-of-stroke stops, for example comprising a stop piston which enters a stop tube provided with a perforation to effect deceleration of the end of stroke of the stop piston.

By means of the simple valve 34, which comprises very few constituent elements, the uncomfortable operating region 52, which is limited by the maximum value of the predefined stroke C0 and the minimum value of the force F0 (which is in particular between 200daN and 400 daN), is simply, effectively and economically avoided.