Positive-locking coupling unit and differential gear with such a positive-locking coupling unit

Abstract

A positive-locking coupling unit (1) for a transmission of a drive train of a motor vehicle comprising a first coupling element (2) and at least a second coupling element (3), wherein the first coupling element (2) can be actuated into different switching positions via an actuator unit (4), namely into at least one coupled switching position and one decoupled switching position, wherein at least one emergency decoupling function unit (5) can also be actuated via the actuator unit (4), via which, in the event of a fault of the coupling unit (1), the first coupling element (2) can be transferred from the coupled switching position to the decoupled switching position, wherein the emergency decoupling function unit (5) can be actuated via an electrical circuit of the actuator unit (4) or a magnetic field of the actuator unit (4), and differential gears (11) with at least one such positive-locking coupling unit (1).

Description

Field of invention

[0001] The present invention relates to a positive-locking coupling unit for a transmission of a drive train of a motor vehicle and to a differential transmission with at least one such positive-locking coupling unit. State of the art

[0002] Hybrid and electric vehicles with more than one drive unit usually have at least one decoupling system installed to decouple a drive unit as needed.

[0003] For example, single-speed electric axles typically have gear ratios of 8 to 12, and electric motors used today have maximum speeds between 12,000 and 20,000 revolutions per minute. This means that, for example, hybrid vehicles with an internal combustion engine and an electric motor, which generally travel at higher speeds, require a decoupling system that isolates the electric motor from the drivetrain to prevent over-revving.An electric vehicle with only one primary drive source does not need a decoupling system, since the maximum electric speed corresponds to the maximum speed of the vehicle, whereas electric vehicles with, for example, two drive sources, namely a primary electrically driven axle as the main drive and a secondary electric axle as an auxiliary drive, also have a decoupling system to decouple the unneeded electric machine (secondary electrically driven axle) as needed, in order to increase the efficiency of the entire drive when the drive via the primary drive axle is sufficient.

[0004] When using a dual-clutch differential, implementing a decoupling function is very simple by fully opening both clutches.

[0005] A decoupling system can also be implemented in axles with conventional bevel gear differentials. One simple option is to use a dog clutch at defined interfaces between, for example, a drive shaft and a side gear of the differential. However, a common problem is that the decoupling system is often unable to open against higher residual torques in the drivetrain. Ideally, the decoupling system should always be able to open in the event of a fault, such as an Active Short Circuit (ASC), which in turn means that the decoupling system would need to be able to open against several hundred Newton meters of torque. Summary of the invention

[0006] It is an object of the invention to address the above-mentioned problem and to provide a positive-locking coupling unit for a motor vehicle transmission which, in a simple, component-optimized design, has an emergency decoupling unit.

[0007] Furthermore, it is an object of the present invention to provide a differential gear with such a positive-locking clutch unit, which is constructed in a simple manner and can also be opened under high applied torque.

[0008] This need can be met by the subject matter of the present invention according to independent claims 1 and 4. Advantageous embodiments of the present invention are described in the dependent claims.

[0009] The positive-locking coupling unit according to the invention is suitable for use in a gearbox of a drive train of a motor vehicle.

[0010] According to the invention, the positive-locking coupling unit comprises a first coupling element, at least a second coupling element and an actuator unit, wherein the first coupling element can be actuated via the actuator unit into different switching positions, namely into at least one coupled switching position and one decoupled switching position.

[0011] According to the present invention, at least one emergency decoupling function unit can be actuated via the actuator unit, wherein the emergency decoupling function unit can be actuated via an electrical circuit of the actuator unit or a magnetic field of the actuator unit.

[0012] In the event of a fault in the coupling unit, the emergency decoupling function allows the first coupling element to be moved from the coupled switching position to the decoupled switching position.

[0013] A fault condition can be understood as follows: the first clutch element remains in the closed position due to frictional engagement in the gear teeth, as residual torque still exists between the drive motor and the vehicle's wheels, even though the primary actuator unit is attempting to forcefully engage the first clutch element into the open position. Because the actuation force may be insufficient, the emergency decoupling function can, in the event of a clutch unit fault, transfer the first clutch element from the engaged position to the disengaged position.

[0014] In an advantageous embodiment, the emergency decoupling functional unit has a bolt which can be guided into a cam on the first coupling element by actuation via the actuator unit, wherein the first coupling element can be moved from the coupled switching position to the decoupled switching position by the interaction of the bolt and cam.

[0015] Furthermore preferably, the actuator unit comprises an electromagnetic actuator with a coil and an armature as well as a spring, wherein the first coupling element can be moved into the coupled switching position via the armature against a spring force of the spring when the coil is energized and can be moved into the decoupled switching position via the spring force of the spring when the coil is not energized.

[0016] The differential gear according to the invention comprises at least one positive-locking coupling unit according to the invention, wherein the positive-locking coupling unit is functionally arranged between a side gear and a half-shaft of a drive axle of a motor vehicle. According to the invention, the first coupling element (2) is axially movable but rotationally fixed on the half-shaft, and the second coupling element is formed over the side gear of the differential gear according to the invention.

[0017] The first coupling element of the positive-locking coupling unit can preferably be actuated via the actuator unit into the coupled switching position, namely a switching position in which the side wheel is effectively connected to the half-shaft, and the decoupled switching position, namely a switching position in which the side wheel is decoupled from the half-shaft.

[0018] According to the present invention, an emergency decoupling function unit for decoupling the side wheel from the half-shaft can also be actuated via the actuator unit of the positive-locking coupling unit. Brief description of the drawings

[0019] The invention is described below by way of example with reference to the drawings. Fig. Figure 1 shows a schematic detailed cross-sectional view of a first design variant of a differential gear. Fig. Figure 2 shows a schematic detailed cross-sectional view of a second design variant of a differential gear. Detailed description of the invention

[0020] In Fig. Figure 1 schematically depicts a detail of a differential gear 11 in a first embodiment. The differential gear 11 comprises a differential cage with a toothed section, two planet gears, and two side gears 12. The side gears 12 are each axially fixed but rotatable on a half-shaft 13 of a motor vehicle axle. The half-shafts 13 are arranged coaxially with a differential cage rotation axis 14. The differential cage is driven via the toothed section by a drive unit, namely an electric motor, and is mounted in a differential housing. The two planet gears are rotatably mounted in the differential cage. The planet gears mesh with the two side gears 12. The planet gears rotate with the rotating differential cage and can thus drive the half-shafts 13 of the motor vehicle axle via the side gears 12.

[0021] A positive-locking coupling unit 1 is functionally arranged between the illustrated side wheel 12 and the illustrated half-shaft 13.

[0022] The positive-locking coupling unit 1 has an axially movable first coupling element 2, namely a sliding sleeve 2a, arranged non-rotatably on the half-shaft 13, an axially fixed second coupling element 3, rotatably arranged on the half-shaft 13, in this case formed by the side wheel 12, and an actuator unit 4.

[0023] The sliding sleeve 2a has a face-mounted toothing, namely a first claw toothing 15a, in the axial direction, which serves for connection with the side gear 12, more precisely a second claw toothing 15b, which is formed on the side gear 12 in the axial direction. Furthermore, the sliding sleeve 2a has a radial first sliding toothing, which serves for connection with the half-shaft 13, more precisely a radial second sliding toothing, which is formed on the half-shaft 13. Coupling or decoupling of the half-shaft 13 from the drive unit is thus achieved by an axial displacement of the sliding sleeve 2a on the half-shaft 13.

[0024] The direction specification “axial” describes a direction along or parallel to the differential cage rotation axis 14. The direction specification “radial” describes a direction perpendicular to the differential cage rotation axis 14.

[0025] The sliding sleeve 2a can be actuated via the actuator unit 4 into a coupled switching position, namely a switching position in which the side wheel 12 is effectively connected to the half-shaft 13, and a decoupled switching position, namely a switching position in which the side wheel 12 is decoupled from the half-shaft 13.

[0026] The actuator unit 4 comprises an electromagnetic actuator with a coil 8 and an armature 9 as well as a spring 10, wherein the sliding sleeve 2a can be displaced into the coupled switching position by means of an axial displacement of the armature 9 against a spring force of the spring 10 when the coil 8 is energized (with respect to Fig. 1 and Fig. 2 to the right) and, when coil 8 is not energized, is pushed towards the decoupled switching position by the spring force of spring 10 (in relation to Fig. 1 and Fig. 2 to the left).

[0027] An emergency decoupling function unit 5 can also be actuated via the actuator unit 4 for (supportive) decoupling of the side wheel 12 from the half-shaft 13. This emergency decoupling function unit 5 ensures the required decoupling of the side wheel 12, and thus of the drive unit, from the half-shaft 13, even in the event of a fault and high applied torques.

[0028] In the first embodiment, the emergency decoupling unit 5 comprises an electromagnetic solenoid 17 with a coil and an armature designed as a bolt 6. The bolt 6 can be guided radially into a cam 7 on the sliding sleeve 2a by actuation via the actuator unit 4, whereby the interaction of bolt 6 and cam 7 allows the sliding sleeve 2a to be moved from the coupled switching position to the decoupled switching position. The cam 7 is designed such that the bolt 6 of the solenoid 17 can only engage it when the sliding sleeve 2a is in the coupled switching position.

[0029] In the case of the first design variant according to Fig. The emergency decoupling unit 5 can be actuated via a circuit of the actuator unit 4. When the coil 8 of the actuator unit 4 is energized, the coil of the solenoid 17 of the emergency decoupling unit 5 is also energized. Energizing the coil 8 of the actuator unit 4 actuates the sliding sleeve 2a into the coupled switching position. Energizing the coil of the solenoid 17 causes the bolt 6 (armature) of the solenoid 17 of the emergency decoupling unit 5 to retract radially and not engage the cam 7 on the sliding sleeve 2a.In the event of a fault, for example an “ASC” (“Active Short Circuit”), the coil 8 of the actuator unit 4 and thus the coil of the lifting magnet 17 of the emergency decoupling function unit 5 is no longer energized, causing the armature 9 of the electromagnetic actuator of the actuator unit 4 to retract and the bolt 6 of the lifting magnet 17 of the emergency decoupling function unit 5 to move into an extended position and, if the sliding sleeve 2a is in the appropriate switching position, engage in the cam 7 on the sliding sleeve 2a.The sliding sleeve 2a may not be able to be moved from the coupled switching position to the decoupled switching position solely by the spring force of the spring 10 due to an excessively high residual torque – in this case, the sliding sleeve 2a is in a position suitable for the engagement of the bolt 6 of the solenoid 17 in the cam 7 on the sliding sleeve 2a, and the axial displacement of the sliding sleeve 2a from the coupled switching position to the decoupled switching position via the spring force of the spring 10 can be supported by the emergency decoupling unit 5 by the bolt 6 of the solenoid 17 of the emergency decoupling unit 5 engaging in the correspondingly designed cam 7 on the sliding sleeve 2a.

[0030] The emergency decoupling function unit 5 can only become effective if the vehicle is moving or if the sliding sleeve 2a is rotating.

[0031] In Fig. Figure 2 schematically depicts a detail of a differential gear 11 in a second embodiment. The second embodiment of the differential gear 11 differs from the first embodiment of the differential gear 11 in the actuation and design of the emergency decoupling unit 5.

[0032] In the second embodiment, the emergency decoupling unit 5 comprises a permanent magnet 18 and a bolt 6. The bolt 6 is radially adjustable against the housing of the differential gear 11 and can be moved into a first position and a second position by axially displacing the permanent magnet 18. Actuating the actuator unit 4, the bolt 6 can be moved from its first position to its second position and thus into a cam 7 on the sliding sleeve 2a. The interaction of the bolt 6 and the cam 7 allows the sliding sleeve 2a to be moved from the coupled switching position to the decoupled switching position. The cam 7 is designed such that the bolt 6 can only engage it when the sliding sleeve 2a is in the coupled switching position.

[0033] In the case of the second design variant according to Fig. The emergency decoupling unit 5 can be actuated via a magnetic field of the actuator unit 4. When current is energized to the coil 8 of the actuator unit 4, a magnetic field is generated. Depending on the direction of current flowing through the coil 8 of the electromagnetic actuator of the actuator unit 4, the permanent magnet 18 is either attracted or repelled by this magnetic field and can thus be axially displaced. When the coil 8 of the actuator unit 4 is not energized, the permanent magnet 18 remains in its current position.

[0034] By energizing the coil 8 of the actuator unit 4, regardless of the current direction, an axial adjustment of the armature 9 of the actuator unit 4 and thus of the sliding sleeve 2a occurs from the decoupled switching position to the coupled switching position. Fig. In the upper part (above the differential cage rotation axis 14 as a dividing plane), an actuation of the emergency decoupling function unit 5 is shown by energizing the coil 8 of the actuator unit 4 in a first current direction; in the lower part (below the differential cage rotation axis 14 as a dividing plane), an actuation of the emergency decoupling function unit 5 is shown by energizing the coil 8 of the actuator unit 4 in a second current direction.

[0035] When current is applied in the first current direction (upper part of the Fig. 2) the permanent magnet 18 is attracted by the developing magnetic field of the actuator unit 4 and the bolt 6 of the emergency decoupling functional unit 5 remains in the first position, namely a position in which the bolt 6 does not engage in the cam 7 on the sliding sleeve 2a.

[0036] When current is applied in the second current direction (lower part of the Fig.2) The permanent magnet 18 is repelled by the developing magnetic field of the actuator unit 4 and pushed axially onto a bolt cam 19 on the bolt 6. This moves the bolt 6 from the first position to the second position, namely to a position in which the bolt 6 can engage in the cam 7 on the sliding sleeve 2a.The sliding sleeve 2a may not be able to be moved from the coupled switching position to the decoupled switching position solely by the spring force of the spring 10 due to an excessively high residual torque – in this case, the sliding sleeve 2a is in a position suitable for the engagement of the bolt 6 in the cam 7 on the sliding sleeve 2a, and the axial displacement of the sliding sleeve 2a from the coupled switching position to the decoupled switching position via the spring force of the spring 10 can be supported by the emergency decoupling functional unit 5, by the bolt 6 of the emergency decoupling functional unit 5 engaging in the correspondingly designed cam 7 on the sliding sleeve 2a. Reference symbol list 1 Form-fitting coupling unit 2 First coupling element 3 Second coupling element 4 actuator units 5 Emergency decoupling functional unit 6 bolts 7 Backdrop 8 coil 9 anchors 10 springs 11 Differential gear 12 Side wheel 13 Semi-axis 14 Differential cage pivot axis 15a First claw teeth 15b Second claw teeth 17 Electromagnetic lifting magnet 18 permanent magnets 19 bolt set

Claims

[1] Positive-locking coupling unit (1) for a transmission of a drive train of a motor vehicle comprising a first coupling element (2) and at least a second coupling element (3), wherein the first coupling element (2) can be actuated into different switching positions via an actuator unit (4), namely into at least one coupled switching position and one decoupled switching position, characterized by , that at least one emergency decoupling function unit (5) can be actuated via the actuator unit (4), via which, in the event of a fault of the coupling unit (1), the first coupling element (2) can be transferred from the coupled switching position to the decoupled switching position, wherein the emergency decoupling function unit (5) can be actuated via a circuit of the actuator unit (4) or a magnetic field of the actuator unit (4). [2] Positive locking coupling unit (1) according to claim 1, characterized by, that the emergency decoupling functional unit (5) has a bolt (6) which can be guided into a cam (7) on the first coupling element (2) by actuation via the actuator unit (4), wherein the first coupling element (2) can be moved from the coupled switching position to the decoupled switching position by the interaction of bolt (6) and cam (7). [3] Positive locking coupling unit (1) according to claim 1 or 2, characterized by , that the actuator unit (4) has an electromagnetic actuator with a coil (8) and an armature (9) and a spring (10), wherein the first coupling element (2) can be moved into the coupled switching position via the armature (9) against a spring force of the spring (10) when the coil (8) is energized and can be moved into the decoupled switching position via the spring force of the spring (10) when the coil (8) is not energized. [4] Differential gear (11) for a motor vehicle comprising a positive-locking coupling unit (1) according to one of claims 1 to 3, wherein the positive-locking coupling unit (1) is functionally arranged between a side wheel (12) and a half-shaft (13) of an axle of the motor vehicle and wherein the first coupling element (2) is arranged axially movable but rotationally fixed on the half-shaft (13) and the second coupling element (3) is formed over the side wheel (12) of the differential gear. [5] Differential gear according to claim 4, characterized by, that the first coupling element (2) can be actuated via the actuator unit (4) into the coupled switching position, namely a switching position in which the side wheel (12) is effectively connected to the half-shaft (13) and a decoupled switching position, namely a switching position in which the side wheel (12) is decoupled from the half-shaft (13), and wherein the emergency decoupling function unit (5) for emergency decoupling of the side wheel (12) from the half-shaft (13) can also be actuated via the actuator unit (4).

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