Hydraulic release device for a clutch, and clutch device having such a release device

Abstract

The invention relates to a release device (10) for a clutch device (100) of a motor vehicle (1), having: an annular piston (11) which is received in an annular release element housing (12) such that when hydraulic pressure is applied it can slide in the axial direction in relation to a centre axis Z of the release element housing (12), wherein: the annular piston (11) has a radially inner lateral face (11a) and a radially outer lateral face (11b); the radially outer lateral face (11b) is adjacent to the annular release element housing (12) and is sealed with respect to the annular release element housing (12) by a first grooved sealing ring (13) and a second grooved sealing ring (14); in the release element housing (12) an inlet opening (12a) is provided for the passage of hydraulic fluid; and the inlet opening (12a) is located between the first grooved sealing ring (13) and the second grooved sealing ring (14). The first grooved sealing ring (13) and the second grooved sealing ring (14) engage on the radially outer lateral face (11b) of the annular piston (11) and form, together with the outer lateral face (11b) and the release element housing (12), a pressure chamber (12b) for the hydraulic fluid.

Description

[0001] Hydraulic release device for a clutch device and clutch device with such a release device

[0002] The invention relates to a hydraulic release device for actuating a clutch device, in particular a separating clutch in a motor vehicle with a hybrid or electric drive, and to a clutch device with such a release device.

[0003] Disconnect clutches are used in both hybrid drives and electric vehicles and are used to disconnect the electric motor from the combustion engine or to change gears in electric motors. For the associated release devices used to disengage or engage such a disconnect clutch, proper functionality of the release device is particularly important with regard to functional safety (FUSI). Furthermore, strict environmental aspects must also be considered, which is why components of the disconnect clutch and the release device should be produced cost-effectively and with low CO2 emissions.

[0004] Clutch devices containing such a separating clutch, which can be installed, for example, in a wet clutch chamber, are typically constructed of a closed releaser housing, often made of a polymer, pistons, grooved sealing rings with associated sheet metal retaining rings, O-rings, and a release bearing with a bearing disc (also known as a shim disc). As with conventional hydraulic release devices, a pressure buildup moves the piston axially within the releaser housing, in this case actuating the separating clutch.

[0005] Such release devices are generally subject to problems such as internal seal twisting, leakage, and pressure fluctuations. Furthermore, the release device typically consists of numerous individual components, resulting in high production costs.

[0006] It is therefore an object of the present invention to provide a release device for a clutch, in particular a separating clutch, which has a reduced number of components, can be produced cost-effectively and has a low susceptibility to errors.

[0007] This object is achieved according to the invention by a release device according to claim 1 and a clutch device according to claim 8. Preferred embodiments are specified in the subclaims.

[0008] A release device for a clutch device of a motor vehicle, an annular piston which is received in an annular releaser housing such that it can slide in the axial direction with respect to a center axis Z of the releaser housing when hydraulic pressure is applied. The annular piston has a radially inner side surface and a radially outer side surface, wherein the radially outer side surface borders the annular releaser housing and is sealed against the annular releaser housing with a first grooved sealing ring and a second grooved sealing ring. An inlet opening is provided in the releaser housing for the passage of hydraulic fluid, wherein the inlet opening is positioned between the first grooved sealing ring and the second grooved sealing ring, and wherein the first grooved sealing ring and the second grooved sealing ring engage the radially outer side surface of the annular piston and, together with the releaser housing, define a pressure chamber for the hydraulic fluid.

[0009] In general, it should be noted that in the context of the present invention, when directional terms such as “axial”, “radial” or “circumferential” are used, these always refer to the central axis Z, unless otherwise stated.

[0010] The release device according to the invention extends in a ring around the central axis Z, which can coincide with a rotational axis of the clutch when the release device is used in a separating clutch. The annular release housing, together with the radially outer side surface of the annular piston and the two grooved sealing rings, forms a pressure chamber for the hydraulic fluid, which can flow into the pressure chamber via the inlet opening in order to move the annular piston in the axial direction with respect to the central axis Z. For this purpose, at least a portion of the radially outer side surface of the annular piston is designed to be flat in the axial direction. The pressure chamber is thus arranged purely laterally with respect to the annular piston. This simplifies the construction of both the annular piston and the release housing. The release housing can be designed with small radial dimensions with respect to the central axis, thereby saving both material and manufacturing costs.

[0011] The annular piston can have at least a first region with a first outer diameter D and a second region with a second outer diameter d, wherein the first outer diameter D is larger than the second outer diameter d. The first region can transition into the second region via a shoulder or step. The shoulder or step can comprise a particularly rectangular edge which can serve as a receiving seat for one of the two grooved sealing rings. The first and second grooved sealing rings can be arranged in the first region, i.e. in the region with the smaller outer diameter. The second region with the larger outer diameter D forms a radially outward projection against which one of the grooved sealing rings can bear to delimit the pressure chamber. In particular, the annular piston can be designed with only this one shoulder or step, thereby providing an annular piston that is very easy to manufacture.

[0012] According to one embodiment of the invention, the releaser housing delimits the annular piston exclusively on its outer side surface. In other words, the releaser housing comprises an annular wall, but no base wall, which extends essentially perpendicular to the center axis Z. It is therefore a releaser housing which is open on both end faces, i.e. on the sides that run perpendicular to the center axis Z, or is largely open (at least approximately 80% of the area of ​​the respective end face). When the release device is actuated, i.e. when the pressure chamber is filled with pressurized hydraulic fluid, the annular piston moves in the axial direction next to the releaser housing. This results in a release device design that is particularly space-saving, particularly in the radial direction, while at the same time the design of the releaser housing is simplified.According to a further advantageous embodiment of the invention, the inlet opening is designed as a pipe socket, wherein a receptacle for the first grooved sealing ring is delimited in an axial direction by the pipe socket. The term "pipe socket" in the context of the present invention refers to a short tubular supply line to the pressure chamber. The pipe socket is preferably formed integrally with the releaser housing. Furthermore, the pipe socket can preferably extend radially, which in this context means that a central axis of the pipe socket runs perpendicular to the central axis Z. The pipe socket or a radial wall thereof can be part of a receptacle for the first grooved sealing ring, which serves to delimit the pressure chamber in an axial direction.

[0013] The annular piston can be movable relative to the first grooved sealing ring during a reciprocating movement in the axial direction. This means that the first grooved sealing ring remains firmly in its seat during an axial movement of the annular piston, and the outer side surface of the annular piston slides along the first grooved sealing ring. This design further supports the simplicity of the annular piston's design.

[0014] According to a further embodiment, the second grooved seal can have a static sealing lip and a dynamic sealing lip, with the static sealing lip abutting the radially outer side surface of the annular piston and the dynamic sealing lip abutting the releaser housing. In this embodiment, the second grooved seal moves together with the annular piston during an axial stroke, with the dynamic sealing lip sliding along the releaser housing.

[0015] In this case, a radially inner shoulder can be formed on the radially inner side surface of the annular piston, which serves as a contact surface for a release bearing. The radially inner shoulder can, in particular, be rectangular, forming a transition from a first region of the radially inner side surface to a second region of the radially inner side surface. The first region borders an axial end face of the annular piston and has a larger radius with respect to the center axis than the second region.

[0016] The invention also relates to a clutch device comprising a clutch and a release device according to at least one of the preceding embodiments, wherein the clutch is operatively connected to the release device via a release bearing. The clutch device further comprises an annular housing that at least partially surrounds the release housing and is arranged concentrically therewith, wherein the annular housing forms an outer pressure chamber with a radial outer side of the release housing.

[0017] The expression "at least partially surrounds" means that the annular housing of the clutch device has at least one recess in which the release device, i.e., the releaser housing and the annular piston, are at least partially accommodated. In the clutch device according to the invention, the annular piston is surrounded on its outer side surface at least in one axial section by the releaser housing, which in turn is surrounded at least in one axial section by the annular housing. The two housings can cooperate to accommodate the release device.

[0018] The annular housing of the clutch device, together with the radial outer side of the releaser housing, forms an outer pressure chamber, which is radially upstream of the pressure chamber formed by the releaser housing and the outer side surface of the annular piston. The pressure chamber of the releaser housing thus also forms an inner pressure chamber. During operation of the clutch device, pressurized hydraulic fluid flows from the outer pressure chamber via the inlet opening in the releaser housing to the inner pressure chamber on the annular piston side. In other words, the inlet opening leads from the outer pressure chamber to the radially inner pressure chamber.

[0019] The clutch, which is operatively connected to the release device via a release bearing, can be a multi-plate clutch, for example. In particular, it can be a wet clutch, which is accommodated in a wet chamber that also contains the release device. As is generally known, wet clutches are those that form part of a hydraulic circuit of a transmission in which they are installed. In particular, the clutch can be a separating clutch of an electric or hybrid vehicle. According to one embodiment of the clutch device according to the invention, an inlet to the outer pressure chamber is formed in the annular housing in a radially outer side wall, which in the circumferential direction relative to the center axis Z encloses an angle of between 0° and 30° with the inlet opening of the release housing.In other words, the inlet of the outer pressure chamber is located circumferentially close to the inlet opening of the pressure chamber.

[0020] Furthermore, the inlet can also be arranged at the same height or approximately at the same height as the inlet opening in the axial direction. In other words, a central axis of the inlet opening or the pipe socket can coincide with a central axis of the inlet, or the two axes can be parallel to each other, preferably offset from each other by only a small distance in the axial direction. The inlet opening and the inlet are located radially opposite each other, at least in sections, across the internal pressure chamber. This allows the flow path of the hydraulic fluid to be kept short.

[0021] The housing has an outer side wall, a bottom wall, and an inner side wall, with the outer side wall being connected to the inner side wall via the bottom wall, and the bottom wall being adjacent to and in contact with an axial end of the releaser housing. The axial end is the axial end of the annular piston remote from the clutch. Unlike in the prior art, the annular piston is therefore not delimited at the axial end remote from the clutch by the releaser housing of the release device, but directly by the housing of the clutch device. The releaser housing itself can therefore be designed simply and with minimal material usage. The releaser housing and the housing of the clutch device thus work together to hold the release device in the clutch device. Compared to the prior art, fewer components are required, resulting in lower manufacturing costs while achieving the same function.

[0022] The invention is explained in more detail below using a non-limiting embodiment with reference to the drawing. The drawing shows:

[0023] Fig. 1 shows a basic structure of a clutch device with a release device according to the prior art in cross section;

[0024] Fig. 2 shows a coupling device according to an embodiment of the invention in cross section;

[0025] Fig. 3a, 3b are respective cross-sectional views of the clutch device of Fig. 2 in the engaged and disengaged state;

[0026] Fig. 4a, 4b are respective cross-sectional views of the release device of Fig. 2 in the engaged and disengaged state, respectively.

[0027] The figures are merely schematic in nature and serve solely to facilitate understanding of the invention. Identical or analogous elements are provided with the same reference numerals.

[0028] Figure 1 generally shows a prior art clutch device 1 in a cross-sectional view. The clutch device 1 comprises a clutch 2, an annular housing 3, and a release device 10, which is at least partially accommodated in the housing 3. The clutch 2 is a separating clutch, such as those used in motor vehicles with hybrid drive or in electric vehicles to separate an electric motor from an internal combustion engine, or to enable a gear change in a purely electric vehicle.

[0029] The release device 10 has a release housing 12 in which an annular piston 11 is slidably received and which, in turn, is seated in the annular housing 3. The release housing 12 is sealed to the annular housing 3 with O-rings 4. Since the clutch 2 of the present embodiment is a wet separating clutch, the clutch 2 is located in a wet chamber 5, in which the release device 10 is also located.

[0030] A pressure chamber 12b is formed in the releaser housing 12, to which pressurized hydraulic fluid can be supplied via an inlet opening 12a. As can be seen, the pressure chamber 12b is sealed to the outside, i.e., against the wet chamber 5, on the annular piston 11 and on the releaser housing 12 by grooved sealing rings 13, 14. Sheet metal retaining rings 16 are used to mechanically support the grooved sealing rings 13, 14.

[0031] The annular housing 3, the annular piston 11 accommodated therein and the release housing 12 extend in a ring shape around a central axis Z. When hydraulic fluid flows into the pressure chamber 12b via the inlet opening 12a, the annular piston 11 moves to the left in the axial direction with respect to the central axis Z, which corresponds to a stroke movement, and closes the clutch 2. As soon as the clutch 2 is closed, the full torque of an engine (not shown in the figures) can be transmitted. When the hydraulic pressure in the pressure chamber 12b decreases again, the annular piston 11 moves back to its starting position (to the right in the illustration) and the clutch 2 is opened. In this position, no torque can be transmitted. The clutch 2 presses the annular piston 11 back to its starting position.

[0032] With reference now to Figure 2, an embodiment of a coupling device 1 according to the invention is described, wherein analog components and functions are no longer discussed separately in detail.

[0033] The clutch device 1 according to the invention also comprises the clutch 2, the annular housing 3, and the release device 10 with the annular piston 11 accommodated therein. While the annular housing 3 can be made, in particular cast, from a metal, for example aluminum or steel, the release housing 12 of the release device 10 can be made from a polymer. Analogous to the prior art, O-rings 4 are inserted between the release housing 12 and the annular housing 3 to seal against the wet chamber 5. Unlike the prior art, in the clutch device 1 according to the invention, the pressure chamber 12b is arranged exclusively to the side of the annular piston 11.The annular piston 11 has an inner side surface 11a and an outer side surface 11b, with a first grooved sealing ring 13 and a second grooved sealing ring 14 engaging the radially outer side surface 11b and forming the pressure chamber 12b together with the outer side surface 11b and a radially outer surface 12d of the releaser housing 12. As can be seen, the inlet opening 12a to the pressure chamber 12b is designed here as a short pipe socket, which projects into the pressure chamber 12b and is positioned in the axial direction between the first grooved sealing ring 13 and the second grooved sealing ring 14.

[0034] The release housing 12 is considerably smaller than that of the prior art, covering the annular piston 11 on its radially outer side surface 11b. The release housing 12 thus forms an open housing without a bottom. This creates a cost-effective and material-saving clutch device 1 that also requires little installation space.

[0035] With reference to Figures 3a and 3b, which show a cross-sectional view of the clutch device 1 according to the invention in the engaged state (Figure 3a) and in the disengaged state (Figure 3b), the clutch device 1 and its function are explained in more detail.

[0036] The annular housing 3 comprises a radially outer side wall 3c, a bottom wall 3d and a radially inner side wall 3e. An outer pressure chamber 3a is formed between the release housing 12 and the radially outer side wall 3c of the annular housing 3, into which an inlet 3b opens, which here extends as a radial bore through the outer side wall 3c of the annular housing 3. As can be seen in Figure 3a, the annular piston 11 rests with an axial end region 11g in an initial state directly against the annular housing 3, specifically against a bottom wall 3d thereof.

[0037] As can be seen in the sectional views of Figures 3a and 3b, the inlet 3b is only slightly offset in the axial direction from the inlet opening 12a of the release housing 12, whereby they are arranged here at the same angle in the circumferential direction, so that the inlet opening 12a and the inlet 3b are partially positioned one below the other.

[0038] The annular piston 11 has at least a first region 11c with a first outer diameter D and a second region 11d with a second outer diameter d, wherein the first outer diameter D is larger than the second outer diameter d. The first region 11c transitions into the second region 11d at an outer shoulder 11e.

[0039] The illustration in Figure 3b differs from that in Figure 3a in that the release device 10 in Figure 3b is shown in the disengaged state, in which the annular piston 11 is displaced to the left in the direction of the hollow arrow compared to the illustration in Figure 3a, and thus actuates the clutch 2 via the release bearing 15. The release housing 12 continues to bear with an axial end 12e against the bottom wall 3d of the annular housing 3, but the axial end region 11g of the annular piston 11 is now spaced from the bottom wall 3d.

[0040] With reference now to Figures 4a and 4b, the release device 10 according to the invention will be described in more detail. As can be seen, the first and second groove sealing rings 13; 14 are arranged in the second region 11d of the annular piston

[0041] 11. The outer shoulder 11e serves as the seat of the second grooved sealing ring 14, which rests against the annular piston 11 with a static sealing lip 14a and against the releaser housing 12 with a dynamic sealing lip 14b. The first grooved sealing ring 13 is received in a receptacle 12c of the releaser housing 12. As can be seen, the inlet opening 12a of the releaser housing 12, designed as a tubular nozzle, forms a contact wall for the first grooved sealing ring 13, which is a static seal. The inner side surface 11a of the annular piston 11 forms a radially inner shoulder 11f which serves to form a support for the release bearing 15.

[0042] In Figure 4a, the release device 10 is shown in the initial position, while in Figure 4b it is shown in the disengaged state, wherein the annular piston 11 is offset by the stroke H. As can be seen from a comparison of the two figures, the first groove sealing ring 13 remains in its place during a movement of the annular piston 11, while the second groove sealing ring 14 is carried along with the annular piston 11 during its disengagement movement.

[0043] In summary, it should be noted that in the embodiments according to the invention, the release housing 12 is "halved" and thus "opened" compared to the prior art. The annular piston 11 is adapted to the available installation space and can be manufactured in a simple geometric shape. Since the first grooved sealing ring 13 is designed as a stationary seal, there is only one dynamic / moving seal, namely the second grooved sealing ring 14. The supply of the hydraulic fluid remains essentially unchanged. The installation space required for the release device is reduced compared to the prior art, thereby saving further costs. Since no dynamic seal is required on the radial inner side surface 11a of the annular piston 11, no problems arise with twisting of such an internal seal, as is often the case in the prior art.

[0044] List of reference symbols

[0045] Coupling device

[0046] coupling

[0047] Housing a outer pressure chamber b inlet c outer side wall d bottom wall e inner side wall

[0048] O-ring

[0049] Wet chamber 0 Release device 1 Annular piston 1a inner side surface 1b outer side surface 1c first area 1d second area 1e outer shoulder 1f inner shoulder 1g axial end area 2 Release housing 2a inlet opening 2b pressure chamber 2c receptacle 2d radial outer side 2e axial end 3 first grooved sealing ring 4 second grooved sealing ring 4a static sealing lip 4b dynamic sealing lip 15 Release bearing

[0050] 16 sheet metal retaining ring

[0051] Z center axis

[0052] D Outer diameter first area d Outer diameter second area

Claims

Patent claims 1 . Release device (10) for a clutch device (100) of a motor vehicle (1), comprising: an annular piston (11) which is accommodated in an annular release housing (12) such that it can slide in the axial direction with respect to a center axis Z of the release housing (12) when a hydraulic pressure is applied, wherein the annular piston (11) has a radially inner side surface (11a) and a radially outer side surface (11b), wherein the radially outer side surface (11b) adjoins the annular release housing (12) and is sealed against the annular release housing (12) by a first groove sealing ring (13) and a second groove sealing ring (14), wherein an inlet opening (12a) for the passage of hydraulic fluid is provided in the release housing (12), wherein the inlet opening (12a) is located between the first groove sealing ring (13) and the second groove sealing ring (14), characterized in thatthat the first groove sealing ring (13) and the second groove sealing ring (14) engage the radially outer side surface (11 b) of the annular piston (11 ) and, together with the outer side surface (11 b) and the release housing (12), delimit a pressure chamber (12 b) for the hydraulic fluid.

2. Release device (10) according to claim 1, characterized in that the annular piston (11) has at least a first region (11c) with a first outer diameter D and a second region (11d) with a second outer diameter d, wherein the first outer diameter D is larger than the second outer diameter d, wherein the first region (11c) merges into the second region (11d) via an outer shoulder (11e) and wherein the first and second groove sealing rings (13; 14) are arranged in the second region (11d).

3. Release device (10) according to claim 1 or 2, characterized in that the release housing (12) delimits the annular piston (11) exclusively on its outer side surface (11 b).

4. Release device (10) according to one of the preceding claims, characterized in that the inlet opening (12a) is designed as a pipe socket, wherein a receptacle (12c) for the first groove sealing ring (13) is delimited in an axial direction by the pipe socket.

5. Release device (10) according to claim 4, characterized in that the annular piston (11) is movable relative to the first groove sealing ring (13) during a stroke movement in the axial direction.

6. Release device (10) according to one of the preceding claims, characterized in that the second groove sealing ring (14) has a static sealing lip (14a) and a dynamic sealing lip (14b), wherein the static sealing lip (14a) bears against the radially outer side surface (11b) and the dynamic sealing lip (14b) bears against the release housing (12).

7. Release device (10) according to one of the preceding claims, characterized in that a radially inner shoulder (11f) is formed on the radially inner side surface (11a) of the annular piston (11), which shoulder serves as a contact surface for a release bearing (15).

8. Clutch device (1), comprising a clutch (2) and a release device (10) according to one of the preceding claims, wherein the clutch (2) is operatively connected to the release device (10) via a release bearing (15), wherein the clutch device (1) has an annular housing (3) which at least partially surrounds the release housing (12) and is arranged concentrically thereto, wherein the annular housing (3) forms an outer pressure chamber (3a) with a radial outer side (12d) of the release housing (12).

9. Coupling device (1) according to claim 8, characterized in that in the housing (3) an inlet (3b) is formed by an outer side wall (3c) of the housing (3) to the outer pressure chamber (3a), which in the circumferential direction relative to the center axis Z encloses an angle between 0° and 30° with the inlet opening (12a) of the release housing (12).

10. Clutch device (1) according to claim 8, characterized in that the housing (3) has the outer side wall (3c), a bottom wall (3d) and an inner side wall (3e), wherein the outer side wall (3c) is connected to the inner side wall (3e) via the bottom wall (3d) and wherein the bottom wall (3d) adjoins and bears against an axial end (12e) of the release housing (12).

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