Piston-cylinder unit

Abstract

Piston-cylinder unit (1) with a cylinder (2) and a piston (3) arranged in the cylinder (2) and displaceable relative to the cylinder (2), with a sealing element (7) connected to the piston (3), wherein the piston (3) has a receptacle (8) into which a projecting element (9) of the sealing element (7) engages, wherein the sealing element (7) has a base body (13) from which the projecting element (9) protrudes, wherein two sealing lips (14) protrude from the base body (13), which protrude essentially in a V-shape with a base (15) between the two sealing lips (14), wherein on the wall (16) of the cylinder (2) a holding element (17) protrudes in the direction of the sealing element (7), which protrudes in the direction of the base (15) between the V-shaped projecting sealing lips (14), characterized in that the holding element (17) acts as a stop between sealing element (7) and the cylinder (2) and stops the movement of the sealing element (7),wherein the base (15) of the sealing element (7) abuts the holding element (17).

Description

[0001] The invention relates to a piston-cylinder unit with a sealing arrangement, in particular for a pressure medium actuating device of a motor vehicle.

[0002] Piston-cylinder units are used to actuate clutches or transmissions in motor vehicles when a pressure medium actuation device, such as a hydraulic actuation device, is used. In some devices, a movable piston is inserted into a stationary cylinder, with a sealing element arranged on the piston to seal the cylinder chamber when the piston is displaced. This not only leads to overpressure situations, but also to negative pressure situations in the cylinder chamber, in which the sealing element lifts off the walls to be sealed or in which the sealing element can be sucked in. Even if the sealing element is attached to the piston in a form-fitting manner, the negative pressure situation can still cause the sealing element to be pulled out of the piston holder, so that it is no longer positioned correctly and can therefore no longer seal properly.A piston-cylinder unit according to the preamble of claim 1 is known from JP 2010-084 895 A. Further prior art is disclosed in DE 101 95 732 T5, DE 10 2013 214 370 A1, DE 37 20 410 A1 and DE 196 35 101 A1.

[0003] It is the object of the invention to create a piston-cylinder unit which allows a secure arrangement of the sealing element and ensures a permanent seal and is nevertheless simple and cost-effective in construction.

[0004] The object of the invention is solved with the features of claim 1.

[0005] An embodiment of the invention relates to a piston-cylinder unit with a cylinder and a piston arranged in the cylinder and displaceable relative to the cylinder, with a sealing element connected to the piston, wherein the piston has a receptacle into which a projecting element of the sealing element engages, wherein the sealing element has a base body from which the projecting element protrudes, wherein two sealing lips protrude from the base body, which protrude essentially in a V-shape, with a base between the two sealing lips, wherein on the wall of the cylinder a holding element protrudes in the direction of the sealing element, which protrudes in the direction of the base between the V-shaped projecting sealing lips.This ensures that the retaining element limits the travel of the sealing element to such an extent that the protruding element remains in its corresponding receptacle at all times. This ensures that even if the sealing element is sucked in, it is not pulled so far out of the receptacle that it can no longer reliably perform its sealing function.

[0006] It is particularly advantageous if the retaining element protrudes from the wall in the direction in which the projecting element of the sealing element protrudes toward the piston. This ensures that the sealing element is securely held.

[0007] It is also advantageous if the receptacle tapers axially toward its opening. This allows for a positive connection.

[0008] Furthermore, it is advantageous if the projecting element extends from its base to its tip, with the projecting element widening from base to tip. This also provides good security.

[0009] It is also advantageous if the protruding element has a region of largest cross-section, with the region of largest cross-section being located axially between the base and the tip. This allows for good insertion and secure retention.

[0010] It is also particularly useful if the axial distance between the base between the sealing lips and the retaining element is shorter than the penetration depth of the projecting element into the receptacle.

[0011] It is particularly advantageous if the retaining element is formed integrally with the cylinder wall. This allows for attachment by injection molding, which is particularly cost-effective.

[0012] It is particularly advantageous if the sealing element has a radially outer groove, with a seal carrier arranged in the radially outer groove. This ensures reliable sealing function.

[0013] It is also advantageous if the sealing element has a radially inner groove, wherein a seal carrier is arranged in the radially inner groove.

[0014] It is particularly advantageous if a seal carrier is connected to the piston, which has a receptacle for receiving the protruding element. This allows for an advantageous design that provides an optimized shape for the seal carrier, while reducing the machining requirements of the piston.

[0015] It is also advantageous if the cylinder is a ring cylinder and the piston is a ring piston, with the sealing element being an annular sealing element. Thus, the piston-cylinder unit can serve, for example, as a concentric ring arrangement, for example, as a master or slave cylinder.

[0016] The present invention is explained in more detail below using preferred embodiments in conjunction with the associated figures:

[0017] Showing: Fig. 1 a schematic sectional view of a piston-cylinder unit according to the invention in a first operating state, and Fig. 2 a schematic sectional view of a piston-cylinder unit according to the invention in a second operating state.

[0018] The Fig. Figure 1 shows a section of a piston-cylinder unit 1 of a clutch release element, such as, in particular, a concentric slave cylinder. The piston-cylinder unit 1 is shown in a first operating state, such as the rest state.

[0019] The piston-cylinder unit 1 has a cylinder 2 in which a piston is axially displaceably received. Preferably, the cylinder 2 is designed as a ring element with an annular space as the cylinder chamber, with the piston 3 being designed as an annular piston.

[0020] The piston can be axially displaced in the cylinder 2 and enlarges or reduces the cylinder chamber 4 of the cylinder 2. On the side of the piston 3 facing away from the cylinder chamber 4, a release bearing 5 is provided, wherein the bearing inner ring 6 of the release bearing 5 is in an actuating connection with the piston 3.

[0021] On the side of the piston 3 facing the cylinder chamber 4, a sealing element 7, in particular designed as a grooved sealing ring, is arranged. The piston 3 has a recess 8 on this side facing the cylinder chamber 4 as a receptacle, into which a projecting element 9 engages, which protrudes from the sealing element 7 in the axial direction. As a result, the sealing element 7 is positively connected to the piston 3. It is in Fig. 1 that the receptacle 8 tapers in the axial direction toward its opening. It can also be seen that the projecting element 9 extends from its base to its tip, with the projecting element 9 widening from the base to the tip.

[0022] The receptacle 8 and the projecting element 9 are designed in such a way that the projecting element 9 has a region of the largest cross-section, the region of the largest cross-section being arranged in the axial direction between the base 10 and the tip 11.

[0023] In the region of the base 10 of the protruding element 9, a seal carrier 12 is provided, which is arranged in a radially outer groove 21 of the sealing element 7, and the seal carrier 12 is also arranged in a radially inner groove 22 of the sealing element 7. The seal carrier is preferably connected to the piston 3, which has the receptacle 8 for receiving the protruding element 9.

[0024] The sealing element 7 has a base body 13, from which the projecting element 9 protrudes. Furthermore, two sealing lips 14 protrude from the base body 13, which protrude in a substantially V-shape. A base 15 is provided between the two sealing lips 14. A projecting retaining element 17 is formed on the wall 16 of the cylinder 2 opposite the base 15, and protrudes toward the sealing element 7.

[0025] The retaining element 17 protrudes from the wall 16 toward the base 15 between the V-shaped sealing lips of the sealing element 7. Thus, the retaining element 17 protrudes from the wall 16 in the direction in which the projecting element 9 of the sealing element 7 protrudes toward the piston 3. The distance between the base 15 and the tip 18 of the retaining element 17 is shorter than the depth to which the projecting element 9 engages the receptacle 8. If the sealing element 7 is sucked in the axial direction toward the wall 16, the base 15 abuts the retaining element 17 before the projecting element 9 slides out of the receptacle 8.

[0026] When pressurized, the enclosed volume of the cylinder chamber 4 between the cylinder 2, also called the housing, and the sealing element 7 is filled with an operating medium, and the piston 3 moves axially away from the wall 16, also called the pressure chamber floor. The sealing lips 14 are pressed toward the side walls of the cylinder 2.

[0027] In another operating case, the operating medium is sucked from the pressure chamber and the piston 3 moves in the axial direction back to the wall 16. The stop between the housing surface 20 and the piston surface 19 limits the travel of the piston 3 in the axial direction.

[0028] In Fig.Figure 2 shows the piston-cylinder unit 1 in an operating state that exhibits a so-called vacuum effect. The piston is displaced toward the wall 16, and the base 15 of the sealing element 7 abuts the retaining element 17. This retaining element 17 serves as a stop between the sealing element and the cylinder 2 and stops the movement of the sealing element 7, while the piston 3 is already stationary due to the piston surface 19 striking the housing surface 2. Further suction pulls the sealing element partially out of its connection, as the engagement of the protruding element in the receptacle is called, and the stop on the cylinder secures it against complete disengagement.

[0029] It is preferred if the cylinder 2 is an annular cylinder and the piston 3 is an annular piston. It is advantageous if the sealing element 7 is an annular sealing element, such as a sealing ring. The retaining element 17 is preferably an annular web that protrudes from the wall 16. List of reference symbols 1 piston-cylinder unit 2 cylinders 3 pistons 4 cylinder chamber 5 release bearings 6 Bearing inner ring 7 Sealing element 8 Recording 9 protruding element 10 Reason 11 top 12 seal carriers 13 basic bodies 14 Sealing lip 15 Reason 16 wall 17 Holding element 18 lace 19 Piston area 20 housing area 21 groove 22 grooves

Claims

[1] Piston-cylinder unit (1) with a cylinder (2) and a piston (3) arranged in the cylinder (2) and displaceable relative to the cylinder (2), with a sealing element (7) connected to the piston (3), wherein the piston (3) has a receptacle (8) into which a projecting element (9) of the sealing element (7) engages, wherein the sealing element (7) has a base body (13) from which the projecting element (9) protrudes, wherein two sealing lips (14) protrude from the base body (13), which protrude essentially in a V-shape with a base (15) between the two sealing lips (14), wherein on the wall (16) of the cylinder (2) a holding element (17) protrudes in the direction of the sealing element (7), which protrudes in the direction of the base (15) between the V-shaped projecting sealing lips (14), characterized bythat the holding element (17) serves as a stop between the sealing element (7) and the cylinder (2) and stops the movement of the sealing element (7), wherein the base (15) of the sealing element (7) abuts the holding element (17). [2] Piston-cylinder unit according to claim 1, characterized by that the holding element (17) projects from the wall (16) in the direction in which the projecting element (9) of the sealing element (7) projects towards the piston (3). [3] Piston-cylinder unit according to claim 1 or 2, characterized by that the receptacle (8) tapers in the axial direction towards its opening. [4] Piston-cylinder unit according to claim 1, 2 or 3, characterized by that the projecting element (9) extends from its base to its tip, wherein the projecting element widens from the base to the tip. [5] Piston-cylinder unit according to claim 4, characterized bythat the projecting element (9) has a region of largest cross-section, wherein the region of largest cross-section is arranged in the axial direction between the base and the tip. [6] Piston-cylinder unit according to at least one of the preceding claims, characterized by that the axial distance between the base (15) between the sealing lips (14) and the holding element (17) is shorter than the penetration depth of the projecting element (9) into the receptacle (8). [7] Piston-cylinder unit according to at least one of the preceding claims, characterized by that the holding element (17) is formed in one piece with the wall (16) of the cylinder (2). [8] Piston-cylinder unit according to at least one of the preceding claims, characterized by that the sealing element (7) has a radially outer groove, wherein a seal carrier (12) is arranged in the radially outer groove (21). [9] Piston-cylinder unit according to at least one of the preceding claims, characterized by that the sealing element (7) has a radially inner groove, wherein a seal carrier (12) is arranged in the radially inner groove (22). [10] Piston-cylinder unit according to at least one of the preceding claims, characterized by that a seal carrier (12) is connected to the piston (3), which has the receptacle for receiving the projecting element. [11] Piston-cylinder unit according to at least one of the preceding claims, characterized by that the cylinder (2) is an annular cylinder and the piston (3) is an annular piston, wherein the sealing element (7) is an annular sealing element.

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