DECOUPLING DEVICE AND DECOUPLING SYSTEM

Description

[0001] The invention relates to a device for decoupling an engine from a drive train of a motor vehicle, in particular a motor vehicle with an electric axle. Such devices are used, for example, to enable so-called "sailing" while driving, a driving mode in which an engine is switched off and disconnected from the drive train of the motor vehicle. In this mode, the available kinetic energy is used to propel the vehicle, and energy losses due to drag are avoided. In hybrid vehicles, i.e., those that have an electric motor for driving the motor vehicle in addition to an internal combustion engine, the sailing mode is part of the drive concept, to which the engine control unit can automatically switch.

[0002] Such a decoupling device typically features a switchable clutch actuated by a hydraulic cylinder. The cylinder is thus moved into a decoupling position by hydraulic pressure and returned to its original position, for example, via a spring. Such decoupling devices can, in principle, be used in conjunction with claw clutches, single-disk clutches, multi-disk clutches, cone clutches, switchable freewheels, and other types of switchable clutches. They are also suitable for use in both wet and dry areas of a clutch.

[0003] However, the use of decoupling devices reset by a mechanical spring, as described above, can lead to low and fluctuating cylinder actuation speeds, particularly at low pressure. These can arise, for example, from fluctuations in the spring force of the mechanical spring, for example, due to unavoidable tolerances. A decoupling device according to the preamble of claim 1 is known from DE 10 2016 000708 A1. Further prior art is disclosed in CN 108 603 588 A, DE 10 2008 011898 A1, and DE 10 2019 100397 A1.

[0004] It is therefore an object of the invention to provide a hydraulic decoupling device and a decoupling system containing the same, which enables a high and at the same time constant actuating speed even at low pressure.

[0005] This object is achieved according to the invention by a decoupling device having the features of claim 1. Advantageous embodiments are specified in the subclaims.

[0006] A decoupling device according to the invention for separating an engine from a drive train has a piston which is movably mounted in a housing parallel to a longitudinal axis L of the housing and which has an arm for the indirect or direct actuation of a coupling element, wherein a first region of the piston is operatively connected to a first pressure chamber such that when pressure is applied to the first pressure chamber, the piston is displaced in a first direction parallel to the longitudinal axis L, wherein a second pressure chamber is present which is operatively connected to a second region of the piston such that when pressure is applied to the second pressure chamber, the piston is displaced in a second direction parallel to the longitudinal axis L, which is opposite to the first direction.

[0007] In the decoupling device, each of the pressure chambers can be equipped with a pressure connection.

[0008] The piston of the decoupling device can in particular be designed as an annular piston which extends around the longitudinal axis L.

[0009] According to one embodiment of the decoupling device, the first region is located at a first longitudinal end of the piston and the second region is located at a second longitudinal end of the piston.

[0010] In the aforementioned embodiment, the arm is attached or formed centrally on the piston with respect to the direction of the longitudinal axis L.

[0011] According to the decoupling device, the first region is located at a first longitudinal end of the piston and the second region is formed by a recess in a jacket surface of the piston.

[0012] In this embodiment, the recess is formed on a radially outer half of the piston's lateral surface, seen with respect to the longitudinal axis L.

[0013] The invention also relates to a decoupling system comprising a decoupling device according to one of the preceding embodiments, as well as a first ball bearing located radially inside the piston and on which the arm of the piston is mounted.

[0014] The decoupling system may further comprise a claw on which the first ball bearing rests radially inward and which is designed to actuate a coupling element with a free end.

[0015] Furthermore, the decoupling system can have a second ball bearing on which the housing is supported radially outwardly.

[0016] The invention will now be described by way of non-limiting examples with reference to the accompanying drawings. In the drawings: Fig. 1 a representation of a decoupling system according to the state of the art; Fig. 2 a first embodiment of the invention; and Fig. 3 a second embodiment of the invention.

[0017] With reference to Figure 1 A decoupling system 100 according to the prior art will now be described. As can be seen in the figure, the decoupling system 100 comprises a housing 1 with a housing cover 2, which is mounted on a drive shaft 3. A piston 4 is mounted in the housing 1 such that it can move in a straight line parallel to a longitudinal axis L of the decoupling system 100, which is also the longitudinal axis L of the drive shaft 3.

[0018] The piston 4 is connected here via a first ball bearing 15 to a claw 17, which serves to actuate a clutch element 11. As can be seen, to secure the first ball bearing 15, a snap ring 18, 19 is placed between the ball bearing 15 and the piston 4 and between the ball bearing 15 and the claw 17, respectively. The housing 1, in turn, is supported on the drive shaft 3 via a second ball bearing 16. A first end 4c of the piston 4 is connected to a first pressure chamber 7 via a first sealing ring 13, which is designed here as a grooved sealing ring.

[0019] When the decoupling system 100 according to the prior art is actuated, a hydraulic fluid is supplied to the first pressure chamber 7 via a first pressure connection 9, whereby the first end 4c of the piston 4 is pressurized and the piston moves to the right in the figure parallel to the longitudinal axis L. As a result, the first ball bearing 15 and thus claw 17, to which the first ball bearing 15 is coupled radially inward with respect to the longitudinal axis L, are carried along in the longitudinal movement. The ball bearing 15 can be, for example, a deep groove ball bearing. The claw 17 then presses on a coupling element 11, for example a fixed claw, and actuates it.

[0020] A spring 5, which in the illustration is a compression spring, serves to reset the piston 4. This spring acts to force the piston 4 back to its initial position in the depressurized state.

[0021] With reference now to Figure 2A first embodiment of the invention is described. The same or corresponding elements as in Figure 1are designated by the same reference numerals. A bearing of the housing 1 on the drive shaft 3 is therefore not discussed further in the description of the embodiments of the invention. In addition to the first pressure chamber 7, which here is integrated into the housing cover 2 and is operatively connected to a first region 4a of the piston 4, here to the first end 4c of the piston 4 (here via the first sealing ring 13), a second pressure chamber 8 is present, which is integrated, for example, into a housing attachment 1a. The housing attachment 1a can be formed integrally with the housing 1 or fastened thereto. The second pressure chamber 8 is located here parallel in the axial direction to the first pressure chamber 7 and has the same cross-section.To actuate the piston 4, the second pressure chamber 8 is operatively connected to a second region 4b of the piston 4, here to a second end 4d of the piston 4, so that hydraulic fluid supplied via a second pressure connection 10 acts on the second end 4d of the piston 4. As can be seen, the pressure generated by the hydraulic fluid in the second pressure chamber 8 acts to move the piston 4 in the opposite direction to the displacement of the piston 4 by hydraulic fluid in the first pressure chamber 7, i.e., in the return direction.

[0022] When the decoupling device 100 is in use, both pressure chambers 7, 8 are filled with fluid and are sealed between the housing cover 2, the housing attachment 1a, and the piston 4 by means of sealing rings 13, 14, which here are also designed as grooved sealing rings. The arm 6, which can be formed integrally with the piston 4 or fastened to it, is formed or fastened centrally on the piston 4 with respect to the longitudinal axis L in the embodiment shown. An end 6a of the arm 6 remote from the piston is designed such that it can form a force-fitting and / or form-fitting connection with the first ball bearing 15, specifically on its radially outer side. The radially inner side of the bearing 15 is in turn connected to a claw 17, with a snap ring 18, 19 securing the ball bearing 15 to the arm 6 and to the claw 17, respectively.

[0023] If the piston 4 is now pressurized via the first pressure chamber 7 and the first pressure connection 9, it is moved in the axial direction in the representation of the Figure 2 shifted to the right, with the hydraulic fluid simultaneously escaping from the second pressure chamber 8 via the second pressure connection 10. The movement of the piston 4 is transmitted to the claw 17 via the arm 6 and the first ball bearing 15, so that the latter presses on the coupling element 11 and accordingly closes a clutch connected to the coupling element 11.

[0024] The coupling is opened in the reverse order. An advantage of this design is the very precise and accurate control of the uncoupling device (e.g., via an electrically controlled pump not shown in the figure) with a short actuation speed.

[0025] In this embodiment, the housing 1 or the housing cover 2 can also be mounted on the drive shaft 3 via a second ball bearing 16.

[0026] With reference to the Figures 3a and 3b A second embodiment of the invention will now be described, wherein the representation of the Figure 3a shows an opening state of the clutch, whereas the representation of the Figure 3b illustrates a closed state of the clutch. The mounting of the housing 1 on the second ball bearing 16 as well as the arm 6 and its connection to the claw 17 are not shown in these figures, but can be designed the same or similar to the first embodiment. In the detailed views of the Figures 3a and 3b Thus, only the function of the double-acting piston 4 is shown in the second embodiment.

[0027] As can be seen, the pressure is applied to the second region 4b laterally on the piston 4, more precisely via a recess 4e in a circumferential surface 4f of the piston 4, and not in the axial direction from the second end 4d, as is the case in the first embodiment. The piston 4 here has three sealing rings 13, 14, 20, whereby the first sealing ring 13 is an A-ring seal for an internal seal to the first pressure chamber 7, and the third sealing ring 20 is an X-sealing ring for the external seal to the first pressure chamber 7 and for the simultaneous internal seal to the second pressure chamber 8. The second sealing ring 14, which is designed as an A-ring seal and is located in the housing 1, serves to provide the external seal on the second pressure chamber 8. The third sealing ring 20 has a dual function. In principle, however, other seal designs are also suitable.

[0028] Now, the first pressure chamber 7 is pressurized via the first pressure port 9 and the piston 4 is displaced axially to the right, closing the clutch. At the same time, fluid escapes from the second pressure chamber 8 via the second pressure port 10. Conversely, to open the clutch, the second pressure chamber 8 is pressurized and the piston 4 is displaced axially to the left.

[0029] In this embodiment, a sliding band 21 is intended to ensure the precise axial guidance of the piston 4. However, with suitable lubrication, this can also be omitted.

[0030] The in the embodiments of the Figures 2 and 3 The decoupling devices 100 shown can be part of a respective decoupling system 1000, which can include the ball bearings 15, 16 and the claw 17 in addition to the decoupling devices 100. All ball bearings 15, 16 can be designed, for example, as deep groove ball bearings. List of reference symbols

[0031] 1 Housing 1a Housing attachment 2 Housing cover 3 Drive shaft 4 Piston 4a First area 4b Second area 4c First end 4d Second end 4e Recess 4f Shell surface 5 Spring 6 Arm 6a End remote from piston 7 First pressure chamber 8 Second pressure chamber 9 First pressure connection 10 Second pressure connection 11 Coupling element 12 Immovable coupling element 13 First sealing ring 14 Second sealing ring 15 First ball bearing 16 Second ball bearing 17 Claw 17a Free end 18 Snap ring 19 Snap ring 20 Third sealing ring 21 Sliding band

Claims

1. A decoupling device (100) for separating a motor from a drive train, comprising a piston (4), which is movably mounted in a housing (1) parallel to a longitudinal axis L of the housing (1) and which comprises an arm (6) for actuating the direct or indirect actuation of a coupling element (11), a first region (4a) of the piston (4) being operatively connected to a first pressure chamber (7) such that when pressure is applied to the first pressure chamber (7) the piston (4) is moved in a first direction parallel to the longitudinal axis L, a second pressure chamber (8) being present, which is operatively connected to a second region (4b) of the piston (4) such that when pressure is applied to the second pressure chamber (8) the piston (4) is moved in a second direction parallel to the longitudinal axis L, which is opposite the first direction, and the first region (4a) being located at a first longitudinal end (4c) of the piston (4) and the second region (4b) being established by a recess (4e) in a lateral surface (4f) of the piston (4), characterised in that the recess (4e) is formed on a radially outer half of the lateral surface (4f) of the piston when viewed in relation to the longitudinal axis L.

2. The decoupling device (100) according to claim 1, characterised in that each of the pressure chambers (7, 8) is equipped with one pressure connection (9, 10).

3. The decoupling device (100) according to claim 1 or 2, characterised in that the piston (4) is formed as an annular piston which extends about the longitudinal axis L.

4. The decoupling system (1000) comprising a decoupling device (100) according to any of the preceding claims and a first ball bearing (15) which is situated radially inside the piston (4) and on which the arm (6) of the piston (4) is mounted.

5. The decoupling system (1000) according to claim 4, characterised in that it comprises a claw (17) on which the first ball bearing (15) rests radially on the inside and which is configured to actuate the coupling element (11) with one free end (17a).

6. The decoupling system (1000) according to any of claims 4 or 5, characterised in that it comprises a second ball bearing (16) on which the housing (1) is supported radially on the outside.