clutch assembly

Abstract

The invention relates to a clutch assembly comprising at least one controllable friction clutch (3, 3') for variably transmitting torque between a clutch input (4, 4') and a clutch output (5, 5'); and a hydraulic actuator assembly (6) for operating the friction clutch (3, 3'), the actuator assembly (6) comprising a hydraulic pump (10), hydraulic chambers (12, 12') in which hydraulic pressure for the friction clutch (3, 3') is generated by the hydraulic pump (10), and a return flow element (13) with a throttle (11) allowing hydraulic fluid to flow from the hydraulic chambers (12, 12') to the housing chamber (8) when the hydraulic pump (10) is stopped, the hydraulic fluid (9) defining a filling level (F) in the housing chamber (8), the outflow opening (14) of the return flow element (13) being located below the filling level (F) of the hydraulic fluid (9) in a steady state.

Description

[Technical Field]

[0001] The present invention relates to a hydraulically operable clutch assembly, particularly for an automotive powertrain. [Background technology]

[0002] EP 1 282 560 A1 discloses a shaft module with two separate friction multi-plate clutches. An angle drive is provided to introduce torque and rotates a hollow shaft. The friction multi-plate clutches are located at the ends of the hollow shaft and can be operated by ball ramp assemblies, each controlled by an electric motor.

[0003] US Patent Application Publication No. 2010 / 0094519, which corresponds to German Patent Application Publication No. 102009005378, discloses an all-wheel drivetrain for a motor vehicle with a permanently driven front axle and a rear axle that can be driven on demand. Torque distribution between the front and rear axles is achieved via a distributor transmission with a friction multi-plate clutch that can be controlled by an electronic control unit and a longitudinal drive shaft. At the rear axle, the introduced torque can be transmitted to both half shafts by a second friction multi-plate clutch.

[0004] WO 2010081743 A1 discloses a hydraulic actuation device for connecting a drive shaft in a motor vehicle powertrain, which comprises a pump for generating hydraulic pressure, a pressure accumulator and two hydraulic actuation units for actuating each associated clutch.

[0005] WO 2017157479 discloses an electric drive for driving a drive shaft of a motor vehicle. The electric drive includes an electric machine, a powertrain unit, and a double clutch unit. The double clutch unit has two sets of discs that can be independently operated by hydraulic actuators to transmit torque to each half shaft.

[0006] From WO 2019 / 174716 a powertrain is known which comprises an electric motor and two half shafts each having a controllable friction clutch for adjusting the transferable torque.

[0007] In hydraulic actuator systems, the required volume flow can be achieved by a motor-pump unit through motor speed regulation or current regulation. Systems with speed regulation are used in particular in units sold by the applicant under the names "Booster Rear Drive Unit" or "Twin AWD". Systems with current regulation are used in particular in units sold by the applicant under the name "Twinster". Depending on the configuration of the hydraulic regulation system, pressure fluctuations may occur due to the formation of bubbles in the hydraulic fluid. This may result in inaccurate torque distribution in the vehicle powertrain. Summary of the Invention [Problem to be solved by the invention]

[0008] The problem underlying the present invention is therefore to propose a hydraulically operable clutch assembly, in particular for torque transmission in motor vehicle powertrains, which ensures precise torque regulation, in particular even during relatively long operation periods. [Means for solving the problem]

[0009] To achieve this object, a clutch assembly, in particular for a powertrain of a motor vehicle, is proposed, which comprises: at least one controllable friction clutch with a clutch input and a clutch output; a hydraulic actuator assembly, which comprises a hydraulic pump, a hydraulic chamber connected to the hydraulic pump, in which hydraulic pressure for loading the controllable friction clutch can be generated by the hydraulic pump, and a return flow element with a throttle, which allows hydraulic fluid to flow from the hydraulic chamber to a reservoir, the hydraulic fluid determining the filling level in the reservoir in a steady state; and the actuator assembly, wherein the outflow opening of the return flow element is located below the filling level of the hydraulic fluid in the steady state.

[0010] The advantage of this clutch assembly is that the hydraulic system configuration with the return flow element and the throttle reduces the tendency for bubbles to form in the hydraulic fluid, so that the hydraulic pressure remains at least approximately constant when the pump is constantly driven. This allows the actuation force of the friction clutch to be precisely adjusted even during relatively long periods of cessation, or the target torque to be transmitted to be maintained without pressure drops. Overall, this allows for precise and targeted torque regulation in the corresponding powertrain for the clutch assembly, especially during relatively long periods of clutch actuation, and correspondingly high driving stability.

[0011] Clutch assemblies with controllable friction clutches are used, particularly in automotive powertrains, to transmit torque to a downstream powertrain in response to demand and driving conditions. The friction clutch can be actuated by an actuator between an open position where no torque is transmitted, a closed position where full torque is transmitted, and an intermediate position for variable torque transmission. For example, such a clutch assembly may have a clutch for transmitting torque to a subsequent drive shaft or to the inside of a drive shaft as needed. The clutch assembly may also be configured with two clutches to transmit torque from one drive shaft to two half shafts or to adjust the torque depending on height.

[0012] According to one embodiment, a lubricant is provided for lubricating and / or cooling a controllable friction clutch, and the lubricant for the friction clutch and the hydraulic fluid for the actuator assembly are hydraulically separated from each other. The hydraulic systems for lubricating and cooling the friction clutch and for operating the friction clutch are formed separately from each other, and the corresponding hydraulic chambers are sealed from each other.

[0013] In a stationary state, the hydraulic fluid present in the reservoir of the actuator assembly may be, for example, less than 400 ml and / or more than 200 ml. The hydraulic chamber or reservoir may be configured to taper downwards in the assembled state of the clutch assembly. The horizontal cross-sectional area of ​​the lower region of the reservoir may be smaller than the horizontal cross-sectional area of ​​the upper region of the reservoir. The suction area of ​​the hydraulic pump is preferably located at the lowest point of the hydraulic system, thereby ensuring reliable hydraulic pumping at all times, even when the vehicle is tilted. When the vehicle is on a straight and / or tilted plane, the outflow opening of the return flow element preferably opens into the lower region of the reservoir and / or preferably at least 10 mm below the filling level of the hydraulic fluid in the assembled state.

[0014] The hydraulic pump may be configured as a one-way pump, which can be driven in one direction of rotation to pump hydraulic fluid. When the pump is stopped, the hydraulic system is depressurized, and hydraulic fluid can then flow via the throttle and the return channel into the depressurized housing chamber. Alternatively, the hydraulic pump may be configured as a bidirectional pump, which, when driven in a first direction of rotation, pumps hydraulic fluid from the reservoir to the friction clutch to engage it, and, when driven in a second direction of rotation, pumps hydraulic fluid from the friction clutch back to the reservoir to disengage it.

[0015] In one embodiment, the return flow element can be connected to an upper housing section or a return flow line formed therein, allowing liquid to flow downward from the chamber into the return flow element and through the return flow element to a pressure-free housing section or reservoir located below. In this case, a high pressure is applied in the hydraulic chamber, which forces the hydraulic liquid into the return flow element. Preferably, an impingement wall is provided in the reservoir, against which the hydraulic liquid flowing out of the return flow element at a high flow rate can impinge, thereby minimizing the tendency for bubbles to form. Upstream of the restriction, hydraulic energy in the form of a high pressure is converted by the restriction into a high flow rate. The hydraulic liquid impinges on the impingement wall at a high velocity, where it is essentially pressureless or at the ambient pressure of the reservoir.

[0016] The return flow element may be sleeve-shaped or tubular. The outlet openings and / or passages of the return flow element may have a diameter at least six times larger than the smallest opening of the throttle. The flow velocity through the return flow element may, in particular, be 30 m / s or less. The reduced pressure between the inlet and outlet openings of the return flow element may, for example, be less than 5 bar.

[0017] According to a possible embodiment, the return flow element may have a lateral outlet opening, the bore axis of which may form an angle of 45° to 135° with the longitudinal axis of the tubular return flow element. In this configuration, the free end of the return flow element is preferably closed. For this purpose, the return flow element may be provided with a closing element against which the incoming hydraulic liquid impinges at a high flow rate and thus exits through the lateral opening at a relatively low flow rate. In this embodiment, the throttle is preferably arranged near the upper housing section located above it, so that the liquid flows through the throttle into the passage.

[0018] In an alternative embodiment, the return flow element may have an end outlet opening with a hole, which is provided with a throttle, i.e., is spaced apart from the upper housing section above it. In this case, no side openings are provided. In this configuration, the outlet opening of the return flow element is preferably directed toward the housing wall in the reservoir, which acts as an impingement plate. The distance between the outlet opening and the housing wall is preferably 1 to 5 mm.

[0019] The length of the passage is at least twice the diameter of the passage and / or the diameter of the outlet opening, which may be, for example, between 3.5 mm and 10 mm.

[0020] The hydraulic pump may be configured to be capable of generating a hydraulic pressure greater than 25 bar.

[0021] An exemplary embodiment for distributing torque introduced by the longitudinal drive shaft to the two halfshafts may include an angle drive, which in particular includes a drive pinion drivable by the longitudinal drive shaft and a ring gear meshing with the drive pinion, which may be arranged concentrically with both friction clutches. A first friction clutch is provided for transmitting a first torque to the first halfshaft, and a second friction clutch is provided for transmitting a second torque to the second halfshaft. In this configuration, a throttle is used as an adjusting element in the hydraulic system, whereby the pressure generated by the pump and the throttle acts uniformly on both clutches. In this way, both clutches transmit torque, thereby achieving a lateral decoupling function between the two halfshafts.

[0022] In particular, when considering the lateral blocking function of a "Twin AWD" unit (Twin All Wheel Drive Unit), a constant hydraulic pressure is required as the output value even when the actuator motor maintains a constant rotational speed (input value) for a relatively long period of time. The clutch assembly is suitable for such applications because it can maintain a constant hydraulic pressure. In this way, the operating force acting on both friction clutches, and therefore the torque to be transmitted, can be maintained constant. This effectively prevents pressure reduction in the hydraulic system when the actuator motor is operated at a constant rotational speed.

[0023] Next, a preferred embodiment will be described with reference to the drawings. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic diagram showing an assembly according to the present invention; [Figure 2] 2 is a graph showing an exemplary pressure profile over time during operation of the assembly according to FIG. 1; [Figure 3] 1 is a schematic diagram showing an alternative embodiment of the assembly according to the invention; [Figure 4A]4A is a cross-sectional view of another embodiment of an assembly according to the present invention taken along section line 4A-4A of FIG. 4B. [Figure 4B] 4B is a cross-sectional view of the assembly of FIG. 4A taken along section line 4B-4B. [Figure 4C] FIG. 4C is a cross-sectional view of the assembly of FIGS. 4A and 4B taken along a cutting plane passing through the shaft axis. [Figure 5] 10 is a partial view of another variant embodiment of the assembly according to the invention; FIG. [Figure 6A] 10 is a partial view of another variant embodiment of the assembly according to the invention; FIG. [Figure 6B] FIG. 6B is an enlarged view of the return flow element of FIG. 6A shown as an individual part. DETAILED DESCRIPTION OF THE INVENTION

[0025] Figure 1 shows a clutch assembly 2 according to the invention in a first embodiment, and Figure 2 shows a graph illustrating an exemplary pressure profile for such a clutch assembly. Both figures will be explained together below.

[0026] The clutch assembly 2 comprises a controllable friction clutch 3 for transmitting torque between a clutch input 4 and a clutch output 5, a hydraulic actuator device 6 for operating or controlling the friction clutch 3, and a housing 7 in which a reservoir 8 is filled with hydraulic fluid 9. Such a clutch assembly 2 with a controllable friction clutch 3 can be used in particular in a motor vehicle powertrain for transmitting torque to a downstream powertrain in the output path depending on demand and driving conditions.

[0027] The actuator assembly 6 comprises a hydraulic pump 10, a hydraulic chamber 12 in which hydraulic pressure for loading the controllable friction clutch 3 is generated during operation of the hydraulic pump, and a return flow element 13 with a throttle 11. The return flow element 13 is hydraulically connected to the hydraulic chamber 12 so that liquid from the chamber can flow through the return flow element into a pressureless housing chamber or reservoir 8 located below. An outlet opening 14 of the return flow element 13 is located below the filling level F of the hydraulic liquid 9. Optionally, a housing wall 16 can be provided against which the hydraulic liquid flowing out of the return flow element 13 at a high flow rate can impinge. In this way, the tendency to generate bubbles can be particularly reduced.

[0028] 2 shows an exemplary pressure profile Pa of the assembly according to the invention over time t. It can be seen that when the pump 10 is activated or the speed n is suddenly increased, the pressure buildup from zero to the target pressure Pt occurs very quickly, i.e., in a time range that can in particular be less than 200 milliseconds. Furthermore, it can be seen that after the target pressure Pt is quickly reached, the pressure Pa remains stable or almost constant and does not decrease over time t, provided that the speed n is constant. No uncontrollable pressure collapse occurs, which may occur due to the presence of air bubbles in the oil.

[0029] The optional hydraulic assembly is described in further detail below. A filter 18 may be provided in the line 17 between the actuator 6 and the throttle 11. A higher pressure exists upstream of the throttle 11 in the flow direction than downstream of it. The return flow element 13 may be sleeve-shaped or tubular, with the opening diameter of the throttle 11 being smaller than the inner diameter of the return flow element 13 or its outlet opening 14, in particular smaller than one-sixth of the inner diameter. The flow velocity through the return flow element may be, for example, up to 30 m / s. The reduced pressure between the inlet and outlet openings of the return flow element may be, for example, less than 5 bar. The hydraulic actuator assembly 6 may be designed for a total volume of hydraulic fluid in the reservoir 8 at rest, which may be, for example, less than 400 ml and more than 200 ml.

[0030] In this case, the hydraulic pump 10 is configured as a unidirectional pump that can be driven in one direction of rotation by a controllable motor 15 to pump hydraulic fluid from the oil pan to the hydraulic chamber 12. The required volumetric flow can be achieved by adjusting the rotation speed of the pump motor 15. A filter 19 can be optionally provided in the supply line between the oil pan and the pump 10. When the pump 10 is stopped, the hydraulic system is depressurized, and the hydraulic fluid 9 can flow via the throttle 11 and the return line 13 to the pressureless reservoir 8 or the oil pan. Additionally, oil can also be forced to flow out via the pump 10; i.e., the counterpressure present in the system passively reverses the rotation of the pump after stopping, allowing the oil to flow back in the opposite direction to the active pumping direction. The unit consisting of the pump 10 and the motor 15 may also be called a motor-pump unit. However, configurations without a separate drive are also possible, for example in which the pump is passively driven via a rotary drive shaft in the powertrain of the vehicle. According to another embodiment not shown here, the hydraulic pump can also be configured as a bidirectional pump, which, when driven in a first direction of rotation, pumps hydraulic fluid into hydraulic chamber 12 to operate clutch 3 in the engagement direction, and, when driven in the opposite direction of rotation, pumps hydraulic fluid out of hydraulic chamber 12 to operate clutch 3 in the disengagement direction.

[0031] The actuator assembly 6 may further include a piston-cylinder unit 20 having a hydraulic chamber 12 and an actuating piston 22 slidably mounted within the hydraulic chamber 12. The actuating piston 22 is connected to an operating member 23 of the friction clutch 3. When pressure in the hydraulic chamber 12 is increased, the piston 22 is moved toward the operating member 23, causing the clutch to transmit torque. The desired torque can be variably adjusted as needed via the hydraulic pressure generated by the pump 10. In this case, the piston-cylinder unit includes a spring 24 that loads or preloads the piston 22 against the hydraulic pressure of the pump 10. When the pump 10 is stopped, the spring 24 pushes the piston 22 toward the hydraulic chamber 12, thereby reopening the clutch 3.

[0032] FIG. 3 shows a clutch assembly 2 according to the invention in a slightly modified configuration that corresponds substantially to that of FIG. 1. In this respect, reference may be made to the above description for common features. In this case, identical or corresponding parts are designated by the same reference numerals. The only difference is that the actuator assembly 6, in the embodiment according to FIG. 2, has a second actuation unit 20' that operates the second clutch 3'. Both actuation units 20, 20' are hydraulically connected to the pump 10 and are actuated by this pump. A clutch assembly 2 with two friction clutches 3, 3' can be used in particular in an output distribution unit for transmitting torque from one input shaft to two output shafts. In this case, the same pressure is applied to both actuation units 20, 20' of both clutches 3, 3', and thus the same torque is applied to both half shafts.

[0033] Figures 4A to 4C show a clutch assembly 2 according to the invention in another embodiment which largely corresponds to the schematic configuration shown in Figure 3. Insofar as this is the case, reference is made to the above description for commonalities, in which case identical or corresponding parts are given the same reference numerals.

[0034] The assembly shown in FIGS. 4A-4C includes an input shaft 25 with a connecting element 26 for introducing torque and a drive pinion 27 for driving the intermediate shaft. The input shaft 25 is rotatably supported within the housing 7 by bearing means 28, 28' about a rotation axis A25. The pinion 27 meshes with a ring gear 29, which is non-rotatably connected to an intermediate shaft 30. Together, the pinion and ring gear form an angular drive. The intermediate shaft 30 is rotatably supported by bearing means 32, 32' about a rotation axis A30 that intersects the input shaft rotation axis A25 at a distance. A first end of the intermediate shaft 30 is drivingly connected to a first controllable friction clutch 3 for transmitting torque to a first half shaft (not shown). A second end of the intermediate shaft 30 is drivingly connected to a second controllable friction clutch 3' for driving a second half shaft (not shown). The clutches 3, 3' are similar in structure and function, so only one of them will be described below.

[0035] The friction clutch 3, 3' has a clutch input part 4, 4' non-rotatably connected to the intermediate shaft 30, a clutch output part 5, 5' to be connected to the associated half shaft for torque transmission, and a disc set 35, 35' for transmitting torque between the input part and the output part. Each disc set 35, 35' includes an inner disc non-rotatable relative to the clutch input part 4, 4' but axially movable, and an outer disc non-rotatable relative to the clutch output part 5, 5' but axially movable, the inner discs and outer discs being arranged alternately in the axial direction. The clutch output parts 5, 5' are configured as clutch drums or outer disc carriers with shaft sections 33, 33' and are rotatably supported in the housing 7 via respective bearing means 34, 34'.

[0036] Each of the two clutches 3, 3' can be actuated by an associated actuating unit 20, 20', both of which are hydraulically actuated by a pump 10. The same hydraulic pressure is applied to both actuating units 20, 20', so that both clutches 3, 3' transmit the same torque to their respective half shafts. Since both actuating units 20, 20' are identical in terms of their structure and function, they will be described together below.

[0037] The actuating units 20, 20' are functionally similar, as shown diagrammatically in FIGS. 1 and 3. The actuating units are hydraulically operated and each have a ring-shaped piston 22, 22', which is axially slidably mounted in the associated ring-shaped hydraulic chamber 12, 12' in the housing 7. The hydraulic chambers 12, 12' are hydraulically connected to the pump 10 via corresponding lines 21. During pump operation, hydraulic pressure can be generated in the hydraulic chambers 12, 12', which causes the pistons 22, 22' mounted therein to move axially toward the halfshafts. The axial force transmitted by the pistons 22, 22' is transmitted to the respective actuating members 23, 23' via thrust bearings 36, 36'. The thrust bearings 36, 36' are used to rotationally isolate the operating members 23, 23', which rotate with the clutch outputs 5, 5', from the actuating units 20, 20' or pistons 22, 22', which are fixedly arranged in the housing 7. Return springs 24, 24' may be provided to return the actuators 6, 6' or pistons 22, 22'. The return springs 24, 24' are arranged to load the pistons 22, 22' axially away from the disc sets 35, 35' when the actuators are not operated, thereby disengaging the respective clutches 3, 3'.

[0038] When the pump 10 is stopped, the pressure in the hydraulic chambers 12, 12' drops, and the hydraulic fluid is returned via the line 17 and the return flow element 13 to the reservoir 8. As can be seen particularly in FIG. 4A, in the installed state of the clutch assembly 2, the reservoir 8 has a downwardly tapering region 37, in which the outlet opening 14 of the return flow element 13 is located. The horizontal cross-sectional area of ​​this lower region 37 of the housing chamber 8 is smaller than the horizontal cross-sectional area of ​​an upper region 38 of the housing chamber. In the installed state, the outlet opening 14 of the return flow element is located at least 10 mm, preferably at least 20 mm, below the hydraulic fluid filling level F. Furthermore, the outlet opening 14 is oriented toward the opposing collision wall 16, thereby stabilizing the outflowing hydraulic fluid. Since the suction region 39 of the hydraulic pump 10 is located at the lowest point in the hydraulic system, reliable hydraulic pumping is always guaranteed, even when the vehicle is tilted. The volume of hydraulic fluid in the reservoir 8 may be less than 400 ml and more than 200 ml.

[0039] In this embodiment, the throttle 11 is arranged in the upper section of the return flow element 13, in particular near the supply 17 to the throttle 11 or to the actuation unit 20, 20', which is formed in or within the upper housing section. The opening diameter of the throttle 11 is significantly smaller than the inner diameter of the return flow element 13 or the inner diameter of the outlet opening 14 of the return flow element, for example smaller than 1 / 6 of the inner diameter. The flow velocity of the hydraulic liquid through the subsequent return flow element 13 may be less than 30 m / s, and the reduced pressure between the inlet and outlet openings of the return flow element may be less than 5 bar.

[0040] Figure 5 shows the clutch assembly 2 according to the invention in a variant embodiment that corresponds substantially to the embodiment according to Figures 4A to 4C, insofar as this is the case, reference is made to the above description with respect to commonalities, in which case identical or corresponding parts are provided with the same reference numerals.

[0041] A special feature of the configuration according to Fig. 5 is that the return-flow element 13 is shorter and opens into the upper region 38 of the reservoir 8. In this case, the outlet opening 14 is directed towards the impingement wall 16 and is arranged at a smaller distance from the impingement wall, which may be, for example, less than 5 mm. The throttle 11 can be arranged correspondingly in the lower section of the return-flow element 13, in particular in a hole at the free end of the return-flow element. In this configuration, hydraulic fluid flows through the passage 41 of the return-flow element 13 to the throttle 11 and through the throttle towards the impingement wall 16 at a high flow rate into the pressureless reservoir 8. All other details correspond to the configuration according to Figs. 4A to 4C, for which reference is made to the description of Figs. 4A to 4C.

[0042] Figure 6A shows the clutch assembly 2 according to the invention in another variant embodiment which corresponds substantially to the embodiment according to Figures 4A to 4C or 5. Insofar as this is the case, reference is made to the above description with respect to commonalities, in which case identical or corresponding parts are provided with the same reference numerals.

[0043] The basic configuration of the return-flow element 13 is similar to that shown in FIG. 5, i.e., the return-flow element 13 opens into the upper region 38 of the reservoir 8. A further special feature of the configuration according to FIG. 6A is that the throttle 11 is arranged in the upper section of the return-flow element 13, and the return-flow element 13, shown alone in FIG. 6B, has a lateral outlet opening 14. The bore axis of the lateral opening extends perpendicular to the longitudinal axis of the return-flow element 13, but this is not limiting. The free end of the return-flow element 13 is closed by a closure element 40 attached to the end opening of the return-flow element. In this configuration, hydraulic fluid leaving the throttle 11 impinges on the closure element 40 with a high flow velocity and therefore flows out through the lateral opening 14 with a low flow velocity. In this case, the oil flow from the throttle 11 is controlled from the return-flow element 13 and guided into the housing chamber via the lateral outlet opening, where the oil stabilizes and is channeled. All other details correspond to the configuration according to FIG. 3, to which reference is made to the description of FIG.

[0044] The advantage of the clutch assembly shown in the figures is that the hydraulic fluid has a reduced tendency to generate bubbles, so that the hydraulic pressure remains at least approximately constant when the pump 10 is constantly driven. This allows the actuation force of the friction clutches 3, 3' to be precisely adjusted, even during relatively long periods of cessation of operation, or the target torque to be transmitted to be maintained without pressure drops. Overall, this allows for a fast, precise and targeted torque adjustment in the corresponding powertrain for the clutch assembly 2, and correspondingly high driving stability, especially during relatively long periods of clutch operation. [Explanation of symbols]

[0045] 2 Clutch Assembly 3 Friction clutch 4 Clutch input section 5 Clutch output section 6 Actuator Assembly 7. Housing 8 Housing Room 9 Hydraulic Fluid 10 Hydraulic Pump 11 Aperture 12 hydraulic chamber 13 Return flow element 14 Outlet opening 15 Motor 16 Collision Wall 17 Conduit 18 Filters 19 Filters 20 Piston-cylinder unit 21 Pipeline 22,22' piston 23,23' Operating member 24,24' spring 25 input shaft 26 Connecting Elements 27 Drive pinion 28 Bearing means 29 Ring gear 30 Intermediate shaft 32 Bearing means 33,33' shaft division 34,34' bearing means 35,35' disc set 36,36' Thrust bearing 37 Housing Area 38 Housing Area 39 Suction area 40 Closure member 41 Passage A axis D diameter F Fill level n rotation speed P pressure t time

Claims

1. 1. A clutch assembly comprising: at least one controllable friction clutch (3, 3') for variably transmitting torque between a clutch input (4, 4') and a clutch output (5, 5'); a hydraulic actuator assembly (6) for operating the friction clutch (3, 3'), the actuator assembly (6) comprising a hydraulic pump (10), hydraulic chambers (12, 12') hydraulically connected to the hydraulic pump (10), and a return flow element (13) with a throttle (11) for allowing hydraulic fluid to flow from the hydraulic chambers (12, 12') to a reservoir (8); the hydraulic fluid (9) has an actuator assembly (6) that defines a filling level (F) in the reservoir (8), the outlet opening (14) of the return flow element (13) being located at least 10 mm below the filling level (F) of the hydraulic fluid (9); the outlet opening (14) of the return flow element (13) is formed as a lateral outlet opening branching off laterally from the passage (41) of the return flow element (13), Clutch assembly.

2. A clutch assembly as described in claim 1, wherein the orifice (11) is positioned above the outlet opening (14) within the passage (41), a closing member (40) is provided at the end of the passage (41) below the outlet opening (14), and the length of the passage (41) between the orifice (11) and the closing member (40) is at least twice the diameter (D41) of the passage (41) and / or the diameter of the outlet opening (14).

3. A clutch assembly comprising: at least one controllable friction clutch (3, 3') for variably transmitting torque between a clutch input (4, 4') and a clutch output (5, 5'); a hydraulic actuator assembly (6) for operating the friction clutch (3, 3'), the actuator assembly (6) comprising a hydraulic pump (10), hydraulic chambers (12, 12') hydraulically connected to the hydraulic pump (10), and a return flow element (13) with a throttle (11) allowing hydraulic fluid to flow from the hydraulic chambers (12, 12') to a reservoir (8), the hydraulic fluid (9) defining a fill level (F) in the reservoir (8); the outlet opening (14) of the return flow element (13) is located at least 10 mm below the filling level (F) of the hydraulic liquid (9), The hydraulic pump (10) is configured to generate a hydraulic pressure higher than 25 bar; The return flow element (13) has a passage (41) having a diameter (D41) at least three times larger than the smallest opening diameter (D11) of the restriction (11), The flow velocity behind the throttle (11) in the return flow element (13) is 30 m / s or less; the throttle (11) is arranged in a lower section of the return flow element (13) and is fitted in a hole at the free end of the return flow element (13), the outlet opening (14) of the return flow element (13) is directed towards a casing wall (16), and the distance between the outlet opening (14) and the casing wall (16) is between 1 mm and 5 mm. Clutch assembly.

4. 4. A clutch assembly according to claim 1 or 3, wherein a lubricant is provided for lubricating and / or cooling the controllable friction clutch (3, 3'), and the lubricant of the friction clutch (3, 3') and the hydraulic fluid (9) of the actuator assembly (6) are different fluids that are hydraulically separated from each other.

5. 3. A clutch assembly according to claim 2, wherein the outlet opening (14) of the return flow element (13) is located in a lower region (37) of the reservoir (8), the reservoir (8) being tapered downwards in the assembled state of the clutch assembly (2), so that the horizontal cross-sectional area of ​​the lower region (37) of the reservoir (8) is smaller than the horizontal cross-sectional area of ​​the upper region (38) of the reservoir (8), and the volume of the hydraulic fluid (9) in the reservoir (8) is less than 400 ml and more than 200 ml.

6. 4. A clutch assembly according to claim 1 or 3, wherein the pressure in the return flow element (13) between the throttle (11) and the outlet opening (14) is less than 5 bar.

7. 4. The clutch assembly according to claim 1, wherein the hydraulic pump (10) is operable to pump the hydraulic fluid (9) to the actuation unit (20, 20′) of the friction clutch (3, 3′) in a direction to engage the friction clutch, and when not operated, allows the hydraulic fluid to flow from the actuation unit (20, 20′) back to the reservoir (8), thereby disengaging the friction clutch (3, 3′).

8. 4. A clutch assembly according to claim 2 or 3, wherein the return flow element (13) is tubular, the throttle (11) is arranged in the return flow element (13), and the diameter (D41) of the passage (41) is between 3.5 mm and 10 mm.

9. 4. A clutch assembly according to claim 1 or 3, further comprising a first controllable friction clutch (3, 3') for transmitting a first torque to the first half shaft and a second controllable friction clutch (3, 3') for transmitting a second torque to the second half shaft.

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