DE102005041418B4 - Hydraulic cylinder, in particular master cylinder of a hydraulic clutch release system - Google Patents

Abstract

It is proposed a master cylinder of a hydraulic clutch release system, with a guided in a cylinder housing piston which is movable by means of a piston rod, wherein at least one mitbewegbares sealing element is provided on the piston.

Description

The present invention relates to a master cylinder, in particular a hydraulic clutch release system, with a guided in a cylinder housing piston which is movable by means of a piston rod.

Hydraulic cylinders for actuating a hydraulic system are sufficiently known from the prior art. For example, the clutch of a vehicle can be hydraulically actuated by a clutch release system with a donor and a slave cylinder. The master cylinder comprises a guided in a fluid-flow cylinder housing piston which is movable via a piston rod. Typically, the cylinder housing is made of plastic and has an inlet connection and a pressure connection and designed as a blind hole pressure chamber in which the piston is provided axially displaceable. The pressure chamber is formed by a guide sleeve which surrounds the piston. The piston is attached to the outer end stop facing the end of the piston rod, so that the piston can be actuated accordingly.

It has been found that, especially in the region of the piston rod facing the end of the piston dirt particles can get into the pressure chamber. This can cause damage to the friction surfaces between the piston and the inner wall of the guide sleeve. This can disadvantageously lead to malfunction in the known hydraulic cylinder.

Accordingly, the present invention seeks to propose a hydraulic cylinder of the type mentioned, in which the penetration of unwanted foreign particles is prevented in the pressure chamber.

This object is achieved in that a master cylinder of a hydraulic Kupplungsausrücksystems is proposed with a piston guided in a cylinder housing, wherein in the cylinder housing a guide sleeve is fixed, in which the piston is movable by means of a piston rod, wherein at least one mitbewegbares on the piston Sealing element is provided, which is fixed in the axial direction on the piston rod facing the end of the piston.

Due to the moving along due to the movement of the piston sealing element can be reliably avoided that dirt particles or the like can penetrate into the gap between the piston and the inner wall of the cylinder housing, so that the life of the hydraulic system is extended. Furthermore, there is the advantage that no additional space is required by the provided on the piston sealing element, so that a compact design of the hydraulic cylinder is made possible. Overall, a particularly robust hydraulic cylinder can thereby be realized, which can be operated in particular under unfavorable boundary or environmental conditions without further notice.

In the context of an advantageous embodiment of the present invention it can be provided that the sealing element, e.g. is formed as a lip seal or the like with a base body and at least one sealing lip preferably formed thereon. Since the piston generally has an approximately circular cross-section, a lip seal can preferably be used as a sealing element, which rests against the entire lateral surface of the piston. The intended moving seal is particularly advantageous because the lip seal moves with the component to be sealed and thus ensures that the sealing function is ensured in any position of the component to be sealed.

According to one embodiment of the present invention, the base body can be fastened to the piston in such a way that the sealing lip slides sealingly along the inner wall of the cylinder housing forming the sealing space, wherein each sealing lip is preferably aligned in its extended position in the direction of movement of the piston. The lip sealing ring may preferably be arranged in the region of the piston rod facing the end of the piston. The arrangement of the sealing element at this position of the piston is particularly advantageous because the piston of the master cylinder is predominantly in the unactuated state, in which the piston is in the fully extended position, so that the penetration of dirt particles in the pressure chamber by that in the region Piston stop point located sealing element is avoided because the gap is completely covered by the sealing lip. Should the piston be in a different position, for example in the retracted position in the clutch actuation, the penetration of dirt particles in the master cylinder can be prevented by the piston is fully retracted when engaging, so that the sealing lip of the lip seal is also moved and possibly penetrated dirt particles are conveyed out of the master cylinder again.

A possible embodiment of the present invention may provide a form-locking connection with the piston as a fastening of the sealing element. In this way are none additional fasteners necessary because the sealing element is held due to its outer shape to the correspondingly complementarily shaped mounting portion of the piston. There are also other types of attachment conceivable.

One possibility for a positive connection can be realized in that the piston has at its end facing the piston rod a radial undercut or the like, in which the sealing element is releasably held. Preferably, the main body of the sealing element can be accommodated in the undercut, so that the sealing lip can be guided along the inner wall of the cylinder housing.

The sealing element is fixed in the axial direction on the piston rod end facing the piston. In this type of attachment formed as a lip seal sealing element, for example, to the piston with the body z. B. be sprayed. However, it is also conceivable that a releasable attachment is used.

A next embodiment of the present invention may provide that a piston clamp is used to fasten the sealing element, which is provided in addition to fixing the piston rod to the piston. For example, the sealing element may be fastened substantially between the piston rod end facing the piston and the piston clip in a recess formed by these components. This type of attachment is particularly cost-effective, since only existing components are used for attaching the sealing element.

As the material for the sealing member used, a thermoplastic elastomer or the like may preferably be used. On the other hand, the use of inexpensive EPDM is advantageous, which is also referred to as ethylene-propylene-diene. This material is characterized in particular by the fact that it is particularly cost-effective, so that the manufacturing costs of the sealing element in the master cylinder are particularly low.

A further embodiment of the invention may provide that at least one further sealing element is provided on the hydraulic cylinder in order to further improve the sealing function of the master cylinder. The further sealing element may, for example, be fastened to the cylinder housing side with a first end and to the piston rod side with a second end. Preferably, an external rubber bellows or a protective cap can be used as a sealing element. Furthermore, it is conceivable that at least one sealing element fixed z. B. is provided on the inner wall of the cylinder housing.

It is particularly advantageous if a piston stop serving as the end of the guide sleeve of the cylinder housing of the master cylinder is divided into segments is particularly advantageous. In this way, the sealing lip of the co-moving sealing element can carry dirt particles through the interstices of the divided guide sleeve to the environment.

Due to the structure of the master cylinder with the moving moving sealing element, a modular system is realized, so that the master cylinder either with or without z. B. lip seal, depending on the desired application, executed or can be used.

Another advantage of the master cylinder results from the fact that it is irrelevant in the use of a moving along sealing element, whether possibly a short piston rod and a consequent large swivel angle of the piston rod occurs. This is therefore not a problem, since in the master cylinder quasi an internal sealing element is used, which ensures the sealing function regardless of the piston rod movement.

• 1 eine geschnittene Teilansicht einer ersten Ausführungsform eines Geberzylinders;
• 2 eine geschnittene Teilansicht einer zweiten Ausführungsform des Geberzylinders; und
• 3 eine geschnittene Teilansicht einer dritten Ausführungsform des Geberzylinders.

Hereinafter, the present invention will be explained in more detail with reference to the drawings. Show it:

• 1 a sectional partial view of a first embodiment of a master cylinder;
• 2 a sectional partial view of a second embodiment of the master cylinder; and
• 3 a sectional partial view of a third embodiment of the master cylinder.

In the 1 to 3 different embodiments of a master cylinder are shown. In these embodiments of the present invention, the hydraulic cylinder is a master cylinder 1 a hydraulic release system, which is not shown, formed.

The master cylinder 1 has in all embodiments, a plastic-made cylinder housing 2 on, on which an inlet connection 3 , which is in communication with a pressure medium reservoir, not shown, and a likewise not shown pressure port is provided, to which a pressure line can be connected.

On the cylinder housing 2 is a guide sleeve 4 fastened, in which the piston 5 is movably guided. The piston 5 is at one end with a piston rod 6 connected to the piston 5 is pressed. Inside the cylinder housing 2 becomes a pressure room 7 formed by the movable piston 5 is limited. For pressure-chamber-side sealing of the piston 5 includes the master cylinder 1 a primary seal 8th and a secondary seal 9 , which are each formed as a stationary U-ring seal. The primary seal 8th is outside on the pressure room 7 radially stepped portion on the inner wall of the cylinder housing 2 guided. When the master cylinder is actuated, the primary seal is located 8th on the lateral surface of the piston 5 sealingly. The secondary seal 9 is on a shoulder of the guide sleeve 4 supported and is also located on the lateral surface of the piston 5 at.

On the piston 5 is provided mitbewegbares and not stationary sealing element. This prevents being in the area of the piston rod 6 facing the end of the piston 5 Dirt particles from the environment in the master cylinder 1 can penetrate. As a sealing element is a lip seal 10 . 10 ' . 10 " with a basic body 11 . 11 ' 11 " and at least one sealing lip formed thereon 12 . 12 ' . 12 " intended.

According to a in 1 illustrated first embodiment is provided that the sealing lip ring 10 radially to the piston 5 is linked. For this purpose, the piston 5 a radial undercut 13 on, in which the main body 11 is recorded positively. The on the main body 11 attached sealing lip 12 extends in the extension direction of the piston 5 , The orientation of the sealing lip 12 . 12 ' 12 " is identical in all embodiments, since thus possibly provided dirt particles in the operation of the master cylinder 1 from the master cylinder 1 with the sealing lip 12 . 12 ' 12 " to get promoted.

In 2 is a second embodiment of the master cylinder 1 shown in which the lip seal 10 ' axially on the piston 5 is attached. For this purpose, the main body 11 'of the lip sealing ring 10 ' on one of the piston rod 6 facing the end of the piston 5 be molded so that the sealing lip 12 ' having the above-described orientation and sealing on the inner wall of the guide sleeve 4 slides.

In 3 is a third embodiment of the master cylinder 1 shown. In this embodiment, the lip seal ring 10 " between the piston 5 and a piston clamp 14 held. This is the lip seal 10 " between the piston rod 6 facing the end of the piston 5 and the piston clamp 14 in a recess formed in this way 15 attached. The main body 11 " of the lip seal 10 " is in the recess 15 held, leaving the sealing lip 12 " on the inner wall of the guide sleeve 4 during the movement of the piston 5 can slide along.

The respective sealing lip 12 . 12 ' . 12 " of the lip seal 10 . 10 ' . 10 " is only slightly on the inner wall of the guide sleeve in all embodiments 4 so that the displacement forces to move the piston 5 are minimal.

Preferably, this can be used as a piston stop 16 serving end of the guide sleeve 4 be segmented so that dirt particles in the simplest way by the moving lip seal 10 . 10 ' . 10 " can be removed, wherein, at least in the vertical direction, a flat connection is realized to the outside.

LIST OF REFERENCE NUMBERS

1

Master cylinder

2

cylinder housing

3

inflow connection

4

guide sleeve

5

piston

6

piston rod

7

pressure chamber

8th

primary seal

9

secondary seal

10, 10 ', 10 "

Lip seal ring

11, 11 ', 11 "

body

12, 12 ', 12 "

sealing lip

13

undercut

14

piston clamp

15

recess

16

piston stop

Claims (10)

Master cylinder (1) of a hydraulic clutch release system, with a guided in a cylinder housing (2) piston (5), wherein in the cylinder housing (2) has a guide sleeve (4) is fixed, in which the piston (5) by means of a piston rod (6) is movable, and wherein on the piston (5) at least one mitbewegbares sealing element is provided, characterized in that the sealing element in the axial direction on the piston rod (6) facing the end of the piston (5) is fixed. Master cylinder after Claim 1 , characterized in that the sealing element as a lip seal (10, 10 ', 10 ") with a base body (11, 11', 11") and at least one sealing lip formed thereon (12, 12 ', 12 ") is formed. Master cylinder after Claim 2 , characterized in that the base body (11, 11 ', 11 ") is fixed to the piston (5) such that the sealing lip (12, 12', 12") slides sealingly along approximately the inner wall of the cylinder housing (2) , wherein the sealing lip (12, 12 ', 12 ") extends in the direction of the extension movement of the piston (5) and in the region of the piston rod (6) facing the end of the piston (5) is fixed. Master cylinder after one of the Claims 1 to 3 , characterized in that the sealing element is positively secured to the piston (5). Master cylinder after one of the Claims 1 to 4 , characterized in that the sealing element is releasably held. Master cylinder after one of the Claims 1 to 5 , characterized in that the sealing element is held by means of a piston (5) fixed to the piston clamp (14) for securing the piston rod (6). Master cylinder after Claim 6 , characterized in that the sealing element substantially between the piston rod (6) facing the end of the piston (5) and the piston clip (14) is fixed in a recess formed (15). Master cylinder after one of the Claims 1 to 7 , characterized in that a thermoplastic elastomer is provided as a material for the sealing element. Master cylinder after one of the Claims 1 to 8th , characterized in that at least one further sealing element is provided, which is fastened with a first end of the cylinder housing side and with a second end piston rod side. Master cylinder after one of the Claims 1 to 9 , characterized in that a piston stop (16) serving as the end of the guide sleeve (4) of the cylinder housing (2) is divided into segments.

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