WO2016097495A1

WO2016097495A1 - Sealing device for hydraulic cylinder

Info

Publication number: WO2016097495A1
Application number: PCT/FR2014/053348
Authority: WO
Inventors: Christophe Mollier; Alessio PRATO; Diego Rossi
Original assignee: Valeo Embrayages
Priority date: 2014-12-15
Filing date: 2014-12-15
Publication date: 2016-06-23
Also published as: KR20170094545A; KR102314506B1

Abstract

The invention relates, on the one hand, to a sealing device for a hydraulic cylinder (1) of the type comprising a pressure chamber (10) formed in its internal wall facing a piston (2) and into which a fluidic supply duct (11) opens, said device comprising on the one hand at least one annular seal (3) bearing a main lip (31) in contact, respectively, with the piston (2) and the wall of the chamber (10) and, on the other hand, a valve housed in said chamber and collaborating with the supply duct (11), characterized in that said annular seal (3) is furthermore secured to at least one elastically deformable auxiliary lip (32) that closes off the supply duct (11) that is able to open in the event of a relative depression in the chamber (10) and, on the other hand, to the use of this device in a motor vehicle clutch system. (Figure 2C)

Description

SEALING DEVICE FOR HYDRAULIC CYLINDER

The invention relates to a low-pressure opening sealing device for hydraulic cylinder.

More specifically, the invention relates to an improvement to the sealing devices used in the hydraulic clutch control cylinders of motor vehicles.

In known manner, the hydraulic cylinders and, in particular, the so-called "emitter" cylinders which are used in the clutch controls, comprise a pressure chamber formed in their inner wall facing a piston and in which directly, or indirectly via a longitudinal groove or necking, a fluid supply conduit.

These cylinders are further provided with a sealing device comprising, on the one hand, at least one annular seal in contact respectively with the piston and the wall of the pressure chamber and, on the other hand, a valve cooperating with the fluid supply duct.

Such a cylinder is described, in particular, in FR 2,623,255 A1 where the valve is attached to the piston. In FR 2 841 310 A1, the profile and the constituent material of the piston have been modified to have an integrated valve means.

These two embodiments are complex, expensive and unreliable because they require the fixing of the valves on the piston.

Furthermore, by analyzing the dynamic behavior of the clutch control system, it has been observed that there is a hysteresis phenomenon between the forward stroke of the piston (disengaging phase by pressing the pedal) and its return stroke (clutch phase by releasing the pedal). However, this phenomenon which generates a depression in the pressure chamber, is likely to induce a spurious air intake which disrupts the operation of the clutch system, in particular because of a significant change in the stroke of the clutch. clutch abutment, which significantly weakens the efficiency of the system. [0005] FR 2 924 185 A1 and FR 2 820 799 A1 sought to solve this problem by equipping the sealing devices with annular seals provided with an auxiliary lip forming a valve projecting towards the inside of the pressure chamber. .

However, the complex structure and profile of these joints pose mounting problems and, in particular, centering on the piston. In addition, because the lip does not provide its valve or valve function in direct contact with the supply duct, the accuracy and flexibility of its movement are not sufficient to ensure satisfactory operation in the presence low depressions.

The invention therefore aims to remedy this technical problem by significantly refining the sensitivity of the valve without degrading the robustness and reliability of the sealing device.

STATEMENT OF THE INVENTION

This object is achieved, according to the invention, by means of a sealing device characterized in that said annular seal is further secured to at least one elastically deformable auxiliary lip, directly closing the duct. and able to open it in case of relative depression in the room.

According to an advantageous characteristic, the auxiliary lip opens the supply duct when the relative vacuum is greater than or equal to 0.1 bar.

According to a specific variant, the annular seal has a U-shaped section in a section plane passing through the axis of the piston.

This seal comprises an anchor collar, a main lip and a body which connects the collar to the main lip. According to a first advantageous variant, the auxiliary lip is carried by the annular seal so as to constitute a single piece.

For example, the auxiliary lip may extend from the main lip, away from the anchor collar.

According to an advantageous characteristic, the end of the main lip and the end of the auxiliary lip are separated by a distance of between 2 and 4 mm.

Preferably, the main lip and the auxiliary lip are divergent and their angular difference is between 0 ° and 30 °.

According to a second variant, the annular seal is provided with an orifice communicating with said supply conduit and capable of being closed by said auxiliary lip.

For example, the auxiliary lip may extend from the anchor collar towards the main lip.

According to a characteristic of this variant, said orifice is defined by a groove formed peripherally through the annular seal.

According to another feature, the end of the auxiliary lip is brought into sealing contact against said orifice by a deported rib extending on the wall of the cylinder.

According to yet another variant, the auxiliary lip is carried by an attached ring in sealing contact with said annular seal.

Preferably, said auxiliary lip then extends against the main lip of the annular seal. According to a specific feature more particularly adapted to the above variant, said orifice is formed through the main lip. According to two distinct embodiments of the invention, the annular seal is housed either in a cavity in the wall of the chamber, or in a cavity formed on the periphery of the piston.

Another object of the invention is a use of a sealing device as defined above in a transmission system for a motor vehicle.

The improved sealing device according to the invention therefore comprises two dynamic lips whose own mechanical behavior is different and adapted respectively to specific integrated functions, on the one hand, seal and, on the other hand, flapper low pressure and without causing parasitic interference between these two functions.

This new configuration thus makes it possible to avoid the appearance of a negative relative pressure, whatever the origin of the air intake.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will become apparent from reading the description which follows, with reference to the accompanying figures and detailed below.

FIG. 1 represents an axial sectional view of an embodiment of a hydraulic cylinder equipped with a sealing device according to the invention.

FIGS. 2A to 2D show sectional detail views of a first embodiment of the sealing device integrated in the cylinder of FIG. 1, respectively, in the successive phases of operation.

FIGS. 3A, 3B and 3C show partial and sectional views of a second embodiment of the sealing device of the invention, respectively, in different positions of the piston. Figures 4A and 4B show detail sectional views of a first variant of the embodiment of the device of Figures 3A-3C, respectively in the closed position and opening. FIGS. 5A and 5B show detail sectional views of a second variant of the embodiment of the device of FIGS. 3A-3C, respectively in the closed and open position.

FIGS. 6A to 6D show partial and sectional views of a second embodiment of the sealing device integrated in the cylinder of FIG. 1, respectively, in the successive phases of operation.

For the sake of clarity, identical or similar elements are marked with identical reference signs throughout the figures.

Naturally, the embodiments illustrated by the figures presented above are given by way of non-limiting examples. It is explicitly foreseen that we can associate these different modes to combine them, at least partially.

DETAILED DESCRIPTION OF EMBODIMENTS

Figure 1 shows a hydraulic cylinder used, for example, as said cylinder "transmitter" in a clutch control system of a motor vehicle.

Such a cylinder is connected by a hydraulic circuit to a clutch pedal.

This circuit comprises, in particular, a fluid reservoir (not shown) and a fluid supply conduit 11 opening into a pressure chamber 10 formed in the inner wall of the cylinder 1 facing a piston 2 and into which a conduit 11 fluid supply, as shown in Figure 1.

In the embodiment shown, the conduit 11 communicates with the chamber 10 via a cylindrical channel 20 delimited between a section of the piston 2 of reduced diameter (or narrowed) and the inner wall of the cylinder 1. [0023] The cylinder 1 is, in addition, provided with a sealing device comprising at least one seal and, in the embodiment illustrated in Figure 1, two annular seals 3, 4 each carrying a main lip 31, 41 in contact, respectively, with the piston 2 and the wall of the chamber 10. In the embodiments of FIGS. 2A-2D, 3A-3B, 4A-4B and 5A-5B, the annular seal 3 is housed in a cavity 14 formed in the wall of the cylinder 1.

The seal 3 comprises a central body forming a spacer and providing the connection between, on the one hand, a deformable anchoring collar 34 which allows the seal 3 to be immobilized and wedged under stress in the cavity 14 and, on the other hand , the main lip 31. the annular seal 3 has a U-shaped section in a plane of section passing through the axis of the piston 2.

The sealing device also comprises a valve housed in or near the chamber 10 and which is intended to cooperate with the supply duct 11.

According to the invention, the annular seal 3 which is mounted most in front of the cylinder 1 is further secured to at least one auxiliary lip 32 resiliently deformable valve.

The lip 32, shown in detail and on a larger scale in FIGS. 2A to 2D and following, is intended to close the supply duct and to open it when a relative vacuum appears in the chamber 10.

To allow the communication of the chamber 10 with the conduit 11 at the onset of a small differential pressure, preferably greater than or equal to 0.1 bar, on either side of the lip 32, this last is performed with a flexibility and a length adapted and predetermined depending on the nature of its constituent material (preferably an elastomer).

In the case of one embodiment of the annular seal in one piece (as illustrated by Figures 2A-2D), the auxiliary lip 32 will be thinner and therefore less stiff than the main lip 31. The sensitivity of the lip 32 is increased by orienting it towards the chamber 10 and giving at its free end 32a an angular profile. Preferably, the end of the main lip 31 and the end 32a of the auxiliary lip 32 are separated by a distance of between 2 and 4 mm.

The main lip 31 and the auxiliary lip 32 are divergent and their angular difference is between 0 ° and 30 °. In the embodiment of Figures 1 and 2A to 2D, the auxiliary lip 32 is carried by the annular seal 3 so as to constitute a single piece.

The end of the duct 11 opens into the bore 12 located between the inner wall of the chamber 10 and the side wall of the piston 2.

The bore 12 has a very narrow section which is easily closed by the flexible auxiliary lip 32 in the closed position illustrated by FIG. 2A which corresponds to the extreme forward position of the piston 2.

In this position, the piston 2 is engaged in the pressure chamber 10 and the channel 20 is here located in front of the annular seal 3 so that the main lip 31 and the lip 32 are in sealing contact with the side wall of the piston 2. The interspace 30 between the two lips 31, 32 is isolated from the chamber 10 and the lip 32 is stabilized by the pressure balance.

In the position of Figure 2B, the piston 2 has moved back inside the cylinder 1 and the channel 20 is then facing the main lip 31 which communicates the interspace 30 between the two lips 31, 32 with the chamber 10. The lip 32 is here always in sealed contact with the piston 2. The depression is below the threshold (0, 1bar).

In Figure 2C, the piston is still in the position of Figure 2B but the lip 32 is here subjected to a differential pressure between its upstream face located on the side of the supply duct 11 and its downstream face of the 10. This pressure differential is greater than the threshold (0.1 bar) which causes the lip 32 to pivot forwards about an axis located substantially in its vicinity. zone of attachment to the body of the annular seal 3. This pivoting may be accompanied or be replaced by an elastic deformation of this lip.

In all cases, this displacement or this deformation of the lip 32 leads to the communication of the bore 12 and the duct 11 with the pressure chamber 10 via the intermediate space 30 between the two lips 31, 32.

This mechanism makes it possible to avoid parasitic air in the chamber 10.

As indicated above, the profile, the dimensions and the constituent material of the lip 32 are determined so that this opening can occur at a very low pressure differential and at least as soon as this differential reaches 0.1 bar. In Figure 2D, the piston 2 has further moved back relative to its position of Figures 2B and 2C and the lips 31, 32 are now both facing the channel 20 and the lip 32 has returned to its position. rest. In this extreme rear stop position of the piston 2 (which corresponds to the clutch pedal in the high position), the channel 20 is at the right of the bore 12 and there is recovery of the atmospheric pressure throughout the circuit.

Figures 3A, 3B and 3C correspond to a first embodiment of the sealing device of the invention wherein the annular seal 3 is provided with an orifice 33 communicating with the supply conduit 11 or being connected to this conduit. The orifice 33 is formed through the body of the seal 3 and can be closed by the auxiliary lip 32.

This orifice is optionally defined by a groove (not visible in the figures) formed peripherally on the periphery of the annular seal 3.

The lip 32 forming a valve is here secured to the anchoring flange 34 of the gasket 3 and extends towards the lip 31 against the body of the annular gasket 3.

The end of the auxiliary lip 32 is brought into sealing contact against the orifice 33 by virtue of a deported rib 13 extending into the cavity 14 where the gasket 3 is housed, as illustrated by FIG. 3C. Figure 3C corresponds to the retracted position of the piston 2 and the closure of the orifice 33.

FIG. 3B corresponds to the advanced position of the piston 2 and the opening of the orifice 33 (depression greater than the threshold of 0.1 bar) by pivoting of the lip 32 about an axis passing through the projecting end of the rib 13. In the latter position, the lip 31 is in sealing contact with the piston 2 and the bore 12, if it exists, is isolated. The duct 11 then communicates with the chamber 10 via the orifice 33 and the peripheral channel 20 of the piston 2 thus establishing an equilibrium of the pressures on either side of the junction 3.

Figures 4A and 4B correspond to a second embodiment of the sealing device of the invention wherein the annular seal 3 is always provided with an orifice 33.

However, the auxiliary lip 32 forming a valve is here carried by an attached ring 5 and comes, as in the embodiment of FIGS. 3A and 3B, in sealing contact with the body of the annular seal 3 through which the orifice 33 is made. .

The position of FIG. 4A corresponds to the recoil of the piston 2 and the closing of the orifice 33 while FIG. 4B corresponds to the opening of this orifice and to the equilibrium of the pressures between the chamber 10 and the conduit of FIG. 11. [0033] Figures 5A and 5B correspond to a variant of the embodiment of Figures 4A and 4B wherein the annular seal 3 is always provided with an orifice 33 but this orifice is here practiced through the main lip 31. In this case, the communication path between the chamber 10 and the conduit 11 passes necessarily through the bore 12, the orifice 33 and the channel 20 bypassing the lip 31. The auxiliary lip 32 extends here against the main lip 31 of the annular seal 3.

FIG. 5A corresponds to the extreme position of recoil of the piston 2 and the closing of the orifice 33. FIG. 5B corresponds to the advance of the piston and to the joint opening of the orifice 33 by pivoting of the lip 32 as soon as a differential pressure threshold equal to 0.1 bar appears, which then leads to restoring the equilibrium of the pressures between the chamber 10 and the duct 11. In another embodiment illustrated by FIGS. 6A-6D, the annular seal 3 is housed in a cavity 14 'formed here on the periphery of the front part of the piston 2.

The channel 20 is made in the wall of the cylinder 1 and no longer on the piston 2 and therefore communicates directly with the conduit 11. The auxiliary lip 32 forming a valve is here located in front of the main lip 31, unlike the first Embodiment of Figures 2A-2D.

In the closed position (FIG. 6A), the main lip 31 and the auxiliary lip 32 come into contact with the inner wall of the cylinder 1 by isolating the chamber 10 from the duct 11. As it retreats back into the cylinder 1 from the position of FIG. 6A, the piston 2 moves the sealing device backwards and makes it assume different states and positions which are illustrated in FIGS. 6B to 6D corresponding to the same states and positions as those described in FIG. reference to the first embodiment illustrated, respectively, in FIGS. 2B to 2D.

Claims

claims

1. Sealing device for a hydraulic cylinder (1) of the type comprising a pressure chamber (10) formed in its inner wall facing a piston

(2) and in which opens a conduit (11) for supplying fluid, said device comprising, on the one hand, at least one annular seal (3) carrying a main lip (31) in contact, respectively, with the piston (2) and the wall of the chamber (10) and, secondly, a valve housed in said chamber and cooperating with the supply conduit (11), characterized in that said annular seal (3) is, in in addition, integral with at least one auxiliary lip (32) elastically deformable, closing the supply duct (11) and able to open it in case of relative depression in the chamber (10).

2. Sealing device according to claim 1, characterized in that said auxiliary lip (32) opens the supply duct (11) when the relative vacuum is greater than or equal to 0.1 bar.

3. Sealing device according to claim 1 or 2, characterized in that said annular seal (3) has a U-shaped section in a section plane passing through the axis of the piston.

4. Sealing device according to one of the preceding claims, characterized in that said auxiliary lip (32) is carried by the annular seal (3) so as to constitute a single piece.

5. Sealing device according to claim 1 or 2, characterized in that the end of said main lip (31) and the end of the auxiliary lip (32) are separated by a distance of between 2 and 4 mm .

6. Sealing device according to claim 3 or 4, characterized in that the main lip (31) and the auxiliary lip (32) are divergent and their angular difference is between 0 ° and 30 °.

7. Sealing device according to one of the preceding claims, characterized in that the annular seal (3) is provided with an orifice (33) communicating with said supply duct (11) and capable of being closed by said auxiliary lip (32).

8. Sealing device according to the preceding claim, characterized in that said orifice (33) is defined by a groove formed peripherally through the annular seal (3).

9. Sealing device according to the preceding claim, characterized in that the end of said auxiliary lip (32) is brought into sealing contact against said orifice (33) by a deported rib (13) extending over the wall of the cylinder (1).

10. Sealing device according to one of the preceding claims, characterized in that said auxiliary lip (32) is carried by an insert ring (5) in sealing contact with said annular seal (3).

1 1. Sealing device according to the preceding claim, characterized in that said auxiliary lip (32) extends against the main lip (31) of the annular seal (3).

12. Sealing device according to claims 5 and 9, characterized in that said orifice (33) is formed through the main lip (31).

13. Sealing device according to one of the preceding claims, characterized in that said annular seal (3) is housed in a cavity (14) formed in the wall of the chamber (10).

14. Sealing device according to one of claims 1 to 12, characterized in that said annular seal (3) is housed in a cavity (14 ') formed on the periphery of the piston (2).

15. Use of a sealing device according to one of the preceding claims in a transmission system for a motor vehicle.