FR3084424A1 - DAMPING DEVICE COMPRISING AN ARRANGEMENT OF ATMOSPHERIC CHAMBERS - Google Patents

Abstract

The invention relates to a damping device (1), in particular for a cycle, comprising a hollow cylindrical damper body (2) comprising a main chamber containing a damping fluid, said main chamber being divided into two working chambers distinct (12, 13), a pin mounted sliding through an axial passage formed in at least one of the ends of the damping body, at least one piston mounted integral with the pin, a seal formed at the axial passage, characterized in that the damping device (1) comprises two additional chambers in fluid communication with each other via a connecting channel, one of the additional chambers being located between the main chamber and the end carrying the seal, at least one of the additional chambers or the connecting channel being connected to means for maintaining atmospheric pressure.

Description

DAMPING DEVICE INCLUDING A

ARRANGEMENT OF ATMOSPHERIC ROOMS

TECHNICAL FIELD OF THE INVENTION [001] The invention relates to the field of suspensions for vehicles, and in particular for cycles and the like.

The invention relates more particularly to a damping device in particular for a cycle, comprising a hollow cylindrical damper body having first and second ends axially opposite one another, at least one being provided with an axial passage for the passage and guiding of an axis, said damper body comprising a main chamber containing a damping fluid, said main chamber being divided into two separate working chambers, one constituting a compression chamber and the other constituting an expansion chamber, an axis mounted sliding through the axial passage, at least one piston mounted integral with the axis inside the main chamber, a seal provided at of the axial passage, between the axis and the damper body.

STATE OF THE ART [003] Conventionally in itself, a suspension is composed of a damping device (or shock absorbers) intended to dissipate energy, conventionally provided by hydraulic rolling, and an elastic device s' opposing the movement of the wheel and guaranteeing its return to the point of equilibrium.

Current cycle dampers face several problems.

First, the hydraulic shock absorbers dissipate energy through the rolling of the oil, causing an increase in system temperature. If the thermal regulation of the system is not well managed, the damper changes behavior and the oil can irreversibly lose its intrinsic properties.

Then, the hydraulic shock absorbers incorporate seals that must operate under high hydraulic and pneumatic pressure, the seals generate significant friction on different moving parts (rod and internal floating piston), which are very harmful for the good shock absorber operation. They limit the sensitivity of the shock absorber and therefore reduce the grip and comfort performance when it is used on a vehicle suspension, and in particular on a cycle suspension. The shock absorber also presents a risk of leakage linked to overpressure, wear, possible intrinsic faults in the seal, etc. However, the presence of leakage is problematic because it can generate stresses in the body (deformations, fatigue , vibrations, noise, etc.) and cavitation phenomena (deterioration of the oil, deterioration of the piston on the low pressure side, etc.).

The invention aims to remedy these problems by proposing a damping device offering improved sensitivity and a risk of leakage eliminated.

The invention also aims to provide a damping device offering improved thermal regulation.

OBJECT OF THE INVENTION To this end, and according to a first aspect, the invention provides a damping device, in particular for a cycle, comprising a hollow cylindrical damper body comprising at least one end provided with a axial passage for the passage and guidance of an axis, said damper body comprising a main chamber containing a damping fluid, said main chamber being divided into two separate working chambers, one constituting a compression chamber and the other constituting an expansion chamber, a pin mounted sliding through the axial passage, at least one piston mounted integral with the axis inside the main chamber, a seal formed at the axial passage, between the axle and the shock body. The damping device is remarkable in that it comprises two additional chambers in fluid communication with each other via a connecting channel, one of the additional chambers being located between the main chamber and the end carrying the seal, at least one of the additional chambers or the connecting channel being connected to means for maintaining atmospheric pressure.

[0010]

By creating additional spaces isolating the external seals from high pressures and a fluidic connection (atmospheric connection) between the two spaces to discharge excess fluid from one to the other, and guaranteeing a pressure equal to the external pressure at within the two spaces via means for maintaining atmospheric pressure such as for example a floating piston or a membrane in contact with the outside, the seals, and in particular the seal subjected to high pressure, are not subject to no pressure delta unlike those to which the shock absorbers of the prior art are subjected. The seals can then be very largely reduced, or even eliminated and replaced by seals of the "scraper" type whose sole function is to prevent dust from entering inside the damper body. The risk of leakage is thus eliminated and the friction due to the seals is very largely reduced and the grip and comfort performance of the vehicle then considerably improved. These spaces / additional rooms will be designated as atmospheric rooms.

Advantageously, the additional bedrooms extend on either side of the main bedroom.

According to a particular embodiment, the damping device comprises two pistons integral with Tax, each piston delimiting one of the working chambers with the adjoining additional chamber.

According to a particular configuration, the axis is a hollow axis having passage openings opening into the additional chambers, said axis forming the connecting channel. In this configuration, provision may be made for the means for maintaining atmospheric pressure to comprise a floating piston situated inside the axis and in contact with atmospheric pressure so as to maintain the additional chambers and the connecting channel at a atmospheric pressure.

Advantageously, each end has an axial passage provided with a seal arranged between the axis and the damper body, the axis being slidably mounted through said passages, each additional chamber being adjacent to the one of the ends of the shock absorber body and one of the working chambers.

According to another embodiment, the axis carries a single piston which forms an assembly forming a valve delimiting the working chambers from one another.

In another particular configuration, the additional chambers and the connecting channel being formed within the same wall of the damper body.

Advantageously, the means for maintaining atmospheric pressure comprise a floating piston or a membrane in contact with atmospheric pressure so as to maintain the additional chambers and the connecting channel at atmospheric pressure.

Advantageously, the device comprises at least one discharge valve arranged to compensate for internal fluid leaks generated at the axis, between the working chambers and their adjoining additional chamber, during the movement of the latter.

Advantageously, the discharge valve is formed in the wall defining the working chamber constituting the compression chamber and the additional chamber adjoining it. The wall could be a piston in the case of the configuration of a two-piston pin damping device.

BRIEF DESCRIPTION OF THE FIGURES Other objects and advantages of the invention will appear during the following description, made with reference to the accompanying drawings, in which:

- the. Figure 1 shows a schematic longitudinal sectional view of a damping device according to a first embodiment of the invention;

- Figures 2a and 2b show the hydraulic path taken by the fluid contained in the atmospheric chambers respectively during the compression phase and the expansion phase;

- Figures 3a and 3b show an alternative embodiment of the damping device of Figure 1, respectively in the compression phase and in the expansion phase;

FIG. 4 represents a schematic view in longitudinal section of a damping device according to a second embodiment of the invention;

- Figures 5 and 6 show the position of compensation valves in an architecture with double piston and single piston respectively.

For clarity, identical or similar elements of the various embodiments are identified by identical reference signs in all of the figures.

DETAILED DESCRIPTION OF THE FIGURES In connection with FIGS. 1 and 2, there is described a damping device 1 for cycle suspension of the through axle type. This damping device is intended to be installed, in particular but not exclusively, on a quadrilateral fork of the type described in application WO2016 / 207570 in the name of the Applicant.

As illustrated in Figures 1 and 2, the damping device 1 illustrated comprises a hollow damper body 2, of generally cylindrical shape, having a first end 3 called end high pressure side (HP) and a second end 4 said end at the low pressure side (LP), axially opposite one another, and each provided with an axial through passage 5, 6 for the passage and the guiding of an axis 7 carrying two pistons 8, 9 and sliding mounted inside the hollow body. Each end is provided with a seal 10, 11 located at their respective through passage.

The two pistons 8, 9 define with the damper body 2 a main chamber containing an oil-type damping fluid. The main chamber is divided into two working chambers 12, 13 by a valve assembly 14. The chamber delimited by the valve assembly 14 and the piston 9 located closest to the high pressure end 3, constitutes a compression 13 while the chamber delimited by the valve assembly 14 and the piston 8 closest to the low pressure end 4 constitutes an expansion chamber 12.

The valve forming assembly delimiting the working chambers 12, 13 is arranged to form a rolling center 14 intended to laminate and brake the passage of the damping fluid flowing between the two working chambers under the action of movement of the axis 7 and the pistons 8, 9, the movement varying the volume of the working chambers.

During the round-trip phases through the rolling center 14, the compression piston 9 moves the fluid towards the rolling center during the compression phases, the expansion piston 8 playing the same role during the expansion phases. In this configuration of the damping device, the pistons have the sole role of moving the damping fluid through the rolling center 14.

In the embodiment, the rolling center is integrated within the damper body 2. It can of course be provided an embodiment in which it is offset, the compression and expansion chambers then being separated one from the other by a simple wall forming a partition.

According to the invention, the damping device 1 comprises two additional chambers 15, located on either side of the pistons 9, 8. More particularly, it comprises a first additional chamber 15 located between the piston 9 delimiting the compression chamber (called "compression piston") and the high pressure seal 11 and a second additional chamber 16 located between the piston 8 delimiting the expansion chamber (called "expansion piston") and the seal 10 low pressure.

The additional chambers are in fluid communication with each other via a connecting channel. In the illustrated embodiment, the through axis 7 carrying the pistons forms the connecting channel.

In order to maintain the two additional chambers 15, 16 and the connecting channel at atmospheric pressure, the damping device 1 comprises means for maintaining atmospheric pressure. When Taxe traversant 7 is used as an atmospheric connection, the means for maintaining atmospheric pressure comprise a floating piston 17 located within it, in a portion of said axis which passes through the additional high pressure chamber 15, said floating piston 17 being in contact itself. even, advantageously directly, with atmospheric pressure. The floating piston 17, designated as an atmospheric piston, by virtue of its possible displacement within the through axis 7, thus makes it possible to guarantee an atmospheric pressure within the additional chambers 15, 16 and their connecting channel. It receives all forms of overpressure, due to the expansion of the fluid or possible overpressures coming from the compression and expansion chambers for example (considering an imperfect seal at the pistons). The advantage of a floating piston and thru-axle arrangement used as an atmospheric connection makes it possible to limit the number of parts and therefore have a positive impact on the weight, cost and reliability of the damping device.

The damping device according to the invention thus has four chambers, two of the chambers being the conventional expansion / compression chambers in which the laminated fluid circulates, the other two additional chambers having the role of isolating the seals sealing of the working chambers and ensuring recovery of internal leaks.

Hereinafter will be designated the first and second additional chambers respectively atmospheric chamber high pressure side (HP) and atmospheric chamber low pressure side (BP).

Figures 2a and 2b show the hydraulic path taken by the fluid contained in the atmospheric chambers during the phase of compression and expansion respectively. Thus during a compression phase, the expansion piston 8 expels the fluid from the atmospheric chamber 16 on the low pressure side to the atmospheric compression chamber 15 via the through axis 7 of the damper. This fluid, not laminated, circulates in the axis 7, from the compression chamber towards the expansion chamber, or vice versa, by crossing the laminating center 14 at its center, by assimilating the calories released by the laminated fluid, then ends its course in the. high pressure atmospheric chamber 15 where it takes advantage of the large exchange surface with the outside to evacuate the accumulated calories (Figure 2a). The fluid freely travels the reverse path during the expansion phase (Figure 2b). The fluid contained in the atmospheric chambers nt 15, 16 thus has the additional role of evacuating the calories released by the laminated fiuide.

The architecture of a double piston damper as illustrated in FIGS. 1 and 2 has numerous advantages, namely atmospheric chambers at atmospheric pressure, atmospheric connection and means for maintaining atmospheric pressure.

First, the atmospheric chambers being directly created by the volumes outside the pistons, the body of the damper does not need a particular design, unlike a piston architecture which will be described more far with reference to figure 4.

Secondly, because of their location (between the seals and the working chambers), the atmospheric chambers also ensure the confinement of high pressures in the compression / expansion chambers, thus making it possible to have the low pressure atmospheric chambers. The friction of the scraper seals directly dependent on the pressure to be supported (the higher the pressure, the greater the friction of the seal), the bare assembly used for the cooling of the damper also allows very little friction at the joints, and therefore considerably improve the sensitivity of the shock absorber. The adjustment of the pistons in the damper body is also improved, since perfect sealing is not necessary, each piston being surrounded by two oil chambers (a working chamber and an atmospheric chamber), also allowing '' improve the sensitivity of the shock absorber.

Third, the atmospheric chambers see their volumes constantly evolve when the axis of the damper moves. The atmospheric connection is then the site of a permanent flow of non-laminated fluid, and therefore cold. It is then possible to use this stream of cold fluid to cool the rolling fluid which heats it. This considerably increases the rate of heat dissipation and therefore reduces the operating temperature. The main advantage is to maintain the good properties of the fluid and thus the proper functioning of the shock absorber over time and under high stress. The atmospheric chambers thus ensure the most stable temperature possible within the damper.

When the axis of the damper is not traversing as shown in Figure 3, the movement of the piston induces a change in volume which it is necessary to compensate. The majority of shock absorbers are then equipped with an internal floating piston, called PPI, or equivalent device such as a bladder, which allows the variation of the volume of fluid. The internal floating piston is on the one hand in contact with the fluid, and on the other hand in contact with a compressible fluid (gas) whose pressure must necessarily be greater than or equal to the pressure of the rolling fluid. Thanks to the double piston architecture, a constant rolling volume can be kept, the volume variation being created between the atmospheric chambers. We can then use the atmospheric piston 17 to play the role of internal floating piston. So that the atmospheric piston 17 does not undergo too great displacements necessary for the volume compensation, it will be associated with a large surface which will be called atmospheric lung (or ATM lung). The main advantage of the ATM lung is that it works at atmospheric pressure. The friction generated by the seals is then very greatly reduced, which induces better sensitivity (grip and comfort) and much better reliability (no leakage possible). It should be noted that the fluid current induced by the variation in the volumes of the atmospheric chambers can of course, as before, be used as cooling. In the example illustrated in FIGS. 3a (shock absorber in compression phase) and 3b (shock absorber in relaxation phase), the ATM Lung has been designed as an extension of the body in order to limit the number of parts. This is of course an exemplary embodiment, the ATM lung being able to be deported via any fluid transport system such as for example a dunte.

Figure 4 shows another example of configuration of a damping device IA according to the invention in which the axis 7A, slidably mounted through the damping body 2A, comprises a single piston 8A and the body 2A damping advantageously has a double shell architecture, with an external shell 20B surrounding an internal shell 20A.

In this configuration, the assembly forming a valve 14A delimiting the expansion and compression chambers 12, 13 is formed by the piston 8A carried by the axis 7A. The atmospheric chambers 15, 16 are in turn formed within the same wall of the damper body 2A, on either side of the expansion and compression chambers 12,

13. The spaces provided for this purpose within the wall of the damper body 2A are arranged at the end walls, so as to extend between the seals of the end concerned and the associated adjacent work. These spaces are also arranged so that the fluid contained in the atmospheric chambers is in contact with the axis 7A. The atmospheric chambers 15, 16 are placed in fluid communication with each other by a connecting channel 9A formed in the longitudinal wall of the damper body 2A. In the illustrated embodiment, the connecting channel 9A is formed by the space present between the internal shell 20A and the external shell 20B.

During the round trip phases of the axis, high pressure and low pressure internal leaks appear between the compression and expansion chambers and the adjoining atmospheric chambers. These internal leaks f are shown on the single piston damping device, Figure 6. They also exist in two piston damping devices. High pressure internal leaks pass into the atmospheric chamber adjoining the compression chamber. Once in the additional chamber, the excess fluid is instantly compensated for by the displacement of the atmospheric piston, which guarantees the atmospheric pressure in the atmospheric chamber on the high pressure side. These leaks then create a depression on the low pressure side of the shock absorber. This vacuum is however compensated by the low pressure leak from the atmospheric chamber on the low pressure side when there is a vacuum on the low pressure side of the damper. These low pressure leaks take some time to pass into the working chamber. If the back and forth movements of the pistons are too fast compared to the "leak speed", a so-called dynamic depression phenomenon is created because the leaks do not have time to be compensated. This phenomenon can then generate forces in the damper body (deformations, fatigue, vibrations, noise, etc.) and cavitation phenomena (deterioration of the oil, deterioration of the piston on the LP side, etc.). In order to compensate for a low pressure “leakage speed” that is too slow, provision is made to equip the damping device according to the invention with discharge valves (lamellae, balls, valve, etc.), also called “compensating valves”. low pressure ". They are located to the right of internal leaks, on the body for single piston architectures, and on the pistons themselves for double piston architectures. Thus arranged, the valves allow almost instantaneous low pressure compensation. Figures 5 and 6 show a diagram of the location of the valves 23 in a double piston (Figure 5) and single piston (Figure 6) architecture respectively. The arrows fl designate the internal high pressure leaks, while the arrows f2 designate the internal low pressure leaks obtained by compensation via the compensation valve.

The invention is described in the foregoing by way of example. It is understood that a person skilled in the art is able to carry out different variant embodiments of the invention without going beyond the ambit of the invention.

Claims (11)

1. Damping device (1, IA), in particular for cycle, comprising: - a hollow cylindrical damper body (2A) comprising at least one end provided with an axial passage (5, 6) for the passage and the guiding of an axis, said damper body (2A, 2A) comprising a main chamber containing a damping fluid, said main chamber being divided into two separate working chambers, one constituting a compression chamber (12) and the other constituting an expansion chamber (13), - an axis (7, 7A) slidably mounted through the axial passage, - at least one piston mounted integral with the axis inside the main chamber, - a seal (10, 11) formed at the axial passage, between the axis (7, 7A) and the damper body (2, 2A), characterized in that the damping device (1 , IA) comprises two additional chambers in fluid communication with each other via a connecting channel (7, 9A), one of the additional chambers being located between the main chamber and the end carrying the seal , at least one of the additional chambers or the connecting channel being connected (e) to means for maintaining atmospheric pressure. 2. Damping device (1, IA) according to claim 1, characterized in that the additional chambers extend on either side of the main chamber. 3. Damping device (1, IA) according to claim 2, characterized in that it comprises two pistons integral with the axis (7), each piston delimiting one of the working chambers with the adjoining additional chamber. 4. Damping device (1, IA) according to any one of claims 1 to 3, characterized in that the axis (7) is a hollow axis which has passage openings opening into the additional chambers, said axis forming the connecting channel. 5. Damping device according to any one of claims 1 to 4, characterized in that each end of the damping body (2, 2A) has an axial passage provided with a seal (10, 11) disposed between the axis (7, 7A) and the damper body (2, 2A), the axis being slidably mounted through said passages, each additional chamber being attached to one of the ends of the damper body and one of the working rooms. 6. Damping device (1, IA) according to claim 1, characterized in that the axis (7A) carries a single piston which forms an assembly forming a valve defining the working chambers from one another . 7. Damping device (1, IA) according to the preceding claim, characterized in that the additional chambers (15, 16) and the connecting channel (9A) are formed within the same wall of the damper body ( 2A). 8. Damping device (1, IA) according to any one of the preceding claims, characterized in that the means for maintaining atmospheric pressure comprise a floating piston (17) or a membrane in contact with atmospheric pressure so as to maintain the additional chambers and the connecting channel at atmospheric pressure. 9. Damping device (1, IA) according to the preceding claim when it depends on claim 4, characterized in that the means for maintaining atmospheric pressure are located inside the axis (7). 10. Damping device (1, IA) according to any one of claims 1 to 8, characterized in that it comprises at least one discharge valve (23) arranged to compensate for the internal leaks of fluid generated at the axis, between the working chambers and their adjoining additional chamber, during the sliding movement of the latter. 11. Damping device (1, IA) according to the preceding claim, characterized in that the unloading valve (23) is formed in the wall delimiting the working chamber constituting the compression chamber and the additional chamber adjoining it- this.