Valve module for use in a pressure line of a hydraulic actuation system

Abstract

Valve module (7) for use in a pressure line of a hydraulic actuation system, characterized by a valve body (13) with a high-pressure inlet (10) and a high-pressure outlet (11) for insertion into the pressure line (5) and a low-pressure outlet (12) for connection to a liquid reservoir (4), in which an axially movable piston (16) is mounted, which closes the low-pressure outlet (12) at a working pressure and opens the low-pressure outlet (12) for connection to the liquid reservoir (4) when a negative pressure or vacuum occurs.

Description

[0001] The invention relates to a valve module for use in a pressure line of a hydraulic actuation system and a hydraulic clutch actuation system, in particular for a motor vehicle, according to the preamble of claim 7.

[0002] Known clutch actuation systems consist of a master cylinder connected to a slave cylinder via a pressure line. The master cylinder is coupled to a fluid reservoir and actuated by an actuating element, such as an accelerator pedal. When the master cylinder is actuated, hydraulic fluid is pumped from the master cylinder via the pressure line into the slave cylinder, which actuates the clutch via a release bearing. As can be seen from Fig. 6, the clutch is actuated by a piston of the slave cylinder 6, which is moved by the pumped hydraulic fluid. The piston of the slave cylinder 6 presses against a release bearing 21, which acts on the clutch. In the slave cylinder 6, there is a free play S1 between the piston and the retaining ring 23 of the release bearing 21, with a second play S2 between the piston and a seal carrier 24. If a negative pressure occurs in the pressure line due to these existing play effects S1, S2, which are in Fig. 6b, as illustrated by arrows A and B, the clutch is not actuated correctly, causing a wobbling movement of the clutch. Similar clutch actuation systems are already known from DE 44 42 090 A1 and DE 10 2004 040 209 A1.

[0003] The invention is based on the object of specifying a piston-cylinder arrangement in which a reliable operation of the actuating system is always guaranteed regardless of the pressures occurring in the pressure line.

[0004] According to the invention, this object is achieved by a valve module for use in the pressure line comprising a valve body with a high-pressure inlet and a high-pressure outlet, as well as a low-pressure outlet for connection to a fluid reservoir, in which an axially movable piston is mounted. The piston closes the low-pressure outlet at a working pressure and opens the low-pressure outlet for connection to the fluid reservoir when a negative pressure occurs. Such a valve module has the advantage that a constant hydraulic fluid pressure is maintained at all times, even under fluctuating pressure conditions in the pressure line, so that the mechanical play that occurs in the hydraulic actuation system is largely eliminated.

[0005] Advantageously, a spring element preloaded against the piston is supported in the valve body. This spring element opens the low-pressure outlet when a negative pressure or vacuum occurs, allowing hydraulic fluid to flow from the fluid reservoir into the valve module and thus into the pressure line to maintain a constant working pressure.

[0006] In one embodiment, the low-pressure outlet is connected via a housing opening of the valve body to a flow channel extending over the high-pressure inlet and the high-pressure outlet. The low-pressure outlet is a separate component that is pressed into the housing opening of the valve body. This allows for a simple connection between the fluid reservoir and the pressure line.

[0007] In one embodiment, the spring element is attached to the low-pressure outlet via a spring retainer. This allows for easy installation of the spring element and the piston actuated by the spring element in the low-pressure outlet.

[0008] To prevent the hydraulic fluid from escaping into the environment of the actuation system, the low-pressure outlet is sealed against the valve body by a seal.

[0009] In one variant, the valve module is T-shaped. Using such a T-shaped connector, the valve module can be easily integrated into the pressure line.

[0010] A further development of the invention relates to a hydraulic clutch actuation system, in particular for a motor vehicle, in which a master cylinder is connected via a pressure line to a slave cylinder that actuates a clutch. The master cylinder is connected to a fluid reservoir and can be adjusted by an actuating element to displace hydraulic fluid from the master cylinder into the slave cylinder. To ensure that no play occurs in the slave cylinder under the wide range of pressures occurring in the pressure line, a valve module connected to the fluid reservoir is inserted into the pressure line and is designed according to at least one feature described in this patent application.

[0011] Advantageously, the low-pressure outlet of the valve module is directly connected to the fluid reservoir. This ensures rapid filling of the pressure line via the valve module when negative pressures occur, thus ensuring pressure equalization in the pressure line.

[0012] In one embodiment, a piston closes the valve module at atmospheric pressure in the pressure line. Thus, it is always assumed that when the accelerator pedal is actuated, which creates sufficient working pressure in the pressure line of the actuation system, the valve module's connection to the fluid reservoir is blocked.

[0013] The invention permits numerous embodiments. One of these will be explained in more detail with reference to the figures shown in the drawing.

[0014] They show: Fig. 1 an embodiment of the clutch actuation system according to the invention, Fig. 2 a perspective view of the valve module according to the invention, Fig. 3 a section through the valve module according to the invention, Fig. 4 a representation of the valve module according to the invention when an accelerator pedal is actuated, Fig. 5 a representation of the valve module according to the invention when the accelerator pedal is returned, Fig. 6 an embodiment of a slave cylinder of a clutch actuation system according to the prior art.

[0015] In Fig. Figure 1 shows an embodiment of the clutch actuation system according to the invention, which is used in a motor vehicle. The clutch actuation system 1 consists of a master cylinder 2, which is connected to a fluid reservoir 4 via a low-pressure line 3. The master cylinder 2 is coupled to a slave cylinder 6 via a pressure line 5. Arranged within the pressure line 5 is a valve module 7, which is coupled to the fluid reservoir 4 via a second low-pressure line 8. The master cylinder 2 is actuated by an accelerator pedal 9.

[0016] The valve module 7 is in Fig. 2 in a perspective view. The valve module 7 is T-shaped and has a valve inlet 10 and a valve outlet 11, with the valve inlet 10 facing the master cylinder 2, while the valve outlet 11 is assigned to the slave cylinder 6. The pressure line 5 is connected to the valve inlet 10 and the valve outlet 11, respectively. A low-pressure outlet 12 is formed perpendicular to this, to which the low-pressure line 8 for connecting the valve module 7 to the fluid reservoir 4 is connected.

[0017] Fig. 3 shows a section through the valve module 7 according to the invention. The valve module 7 consists of a valve body 13, on which the valve inlet 10 and the valve outlet 11 are each formed, which are connected via a flow channel 14. The valve body 13 has a nozzle 15 perpendicular to the valve inlet and outlet 10, 11, which is connected to the flow channel 14 via an opening 20. The nozzle 15 is an integral component of the valve body 13. The low-pressure outlet 12 is pressed into this nozzle 15. An axially movable piston 16 is arranged in the low-pressure outlet 12 and is mounted on a spring element 17 that is preloaded against the nozzle 15. The low-pressure outlet 12 is fastened to the nozzle 15 via a spring clamp 18. A circumferential O-ring 19 is provided between the nozzle 15 and the low-pressure outlet 12 for sealing.

[0018] The functioning of the valve module 7 according to the invention is to be explained with reference to the Fig. 4 and Fig. 5 will be explained. In Fig. 4 indicates the state of the valve module 7 when the accelerator pedal 9 actuates the master cylinder 2. The hydraulic fluid from the master cylinder 2 is pressed into the pressure line 5 and passed on to the slave cylinder 6 to actuate the clutch. The pressure F H within the pressure line 5 increases. The pressure of the hydraulic fluid occurring in the pressure line 5 causes the piston 16 to be pressed against the low-pressure outlet 12 by the spring element 17, thus closing it. This interrupts the connection to the fluid reservoir 4, as indicated by arrow P1. If the accelerator pedal 9 is returned from its actuated position ( Fig.5), a vacuum effect is created in the pressure line 5 depending on the return speed of the accelerator pedal 9. Due to the existing vacuum, the piston 16 is moved out of the low-pressure connection 12 and thus opens it at a certain vacuum pressure, allowing hydraulic fluid to flow from the fluid reservoir 4 into the flow channel 14 of the valve module 7 (arrow P2). The path of the hydraulic fluid from the fluid reservoir 4 is indicated by the arrow P3. By filling the pressure line 5 with hydraulic fluid, the pressure of the hydraulic fluid increases back to the normal state and the play S1, S2 in the slave cylinder 6 is reliably prevented.

[0019] Due to the solution described, pressure fluctuations in the pressure line 5 that occur when the accelerator pedal 9 is returned are reliably prevented, thereby preventing play in the slave cylinder 6 when the clutch is actuated and ensuring reliable actuation of the clutch. List of reference symbols 1 clutch actuation system 2 master cylinders 3 Low pressure line 4 Liquid reservoir 5 Pressure line 6 slave cylinders 7 Valve module 8 Low pressure line 9 Accelerator pedal 10 Valve inlet 11 Valve outlet 12 Low pressure outlet 13 Valve body 14 Flow channel 15 nozzles 16 pistons 17 Spring element 18 spring clamp 19 O-ring 20 Opening 21 release bearing 22 pistons 23 Retaining ring 24 seal carriers

Claims

[1] Valve module (7) for use in a pressure line of a hydraulic actuation system, characterized by a valve body (13) with a high-pressure inlet (10) and a high-pressure outlet (11) for insertion into the pressure line (5) and a low-pressure outlet (12) for connection to a liquid reservoir (4), in which an axially movable piston (16) is mounted, which closes the low-pressure outlet (12) at a working pressure and opens the low-pressure outlet (12) for connection to the liquid reservoir (4) when a negative pressure or vacuum occurs. [2] Valve module according to claim 1, characterized by that a spring element (17) pre-tensioned against the piston is supported on the valve body (13). [3] Valve module according to claim 2, characterized bythat the low-pressure outlet (12) is connected via an opening (20) to a flow channel (14) of the valve body (13) extending between the high-pressure inlet (10) and the high-pressure outlet (11). [4] Valve module according to claim 1, 2 or 3, characterized by that the spring element (17) is attached to the low-pressure outlet (12) via a spring holder (18). [5] Valve module according to at least one of the preceding claims, characterized by that the low-pressure outlet (12) is sealed against the valve body (13) by a seal (19). [6] Valve module according to at least one of the preceding claims, characterized by a T-shaped design. [7] Hydraulic clutch actuation system for a motor vehicle, in which a master cylinder (2) is connected via a pressure line (5) to a clutch-actuating slave cylinder (6), wherein the master cylinder (2) is connected to a fluid reservoir (4) and is adjustable by an actuating member (9) for displacing a hydraulic fluid from the master cylinder (2) into the slave cylinder (6), characterized by that a valve module (7) connected to the liquid reservoir (4) according to at least one of the preceding claims is inserted into the pressure line (5). [8] Hydraulic clutch actuation system according to claim 7, characterized by that a low-pressure outlet (12) of the valve module (7) is directly connected to the liquid reservoir (4). [9] Hydraulic clutch actuation system according to claim 7 or 8, characterized bythat a piston (16) of the valve module (7) closes the low-pressure outlet (12) at atmospheric pressure in the pressure line (5).

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