Differential gear unit, a vehicle comprising a differential gear unit, and a method for operating a differential gear unit

Abstract

A differential gear unit includes an annular ring gear having a rotational axis in an axial direction; side gears respectively distribute torque to drive shafts; differential pinion gears are rotatably arranged on a pinion pin, where the pinion gears respectively engage the side gears. A decoupling element inside the ring gear is rotatably arranged in relation to the ring gear. The pinion pin is connected to and extends diametrically across the decoupling element. A clutch sleeve slides relative to the ring gear and the decoupling element. The clutch sleeve, upon axial displacement, disconnects the ring gear from the decoupling element in a first position, allowing rotational movement of the decoupling element relative to the ring gear; connects the ring gear to the decoupling element in a second position, preventing the rotational movement of the decoupling element; and connects the ring gear to a park-lock structure in a third position.

Claims

1. A differential gear unit for a vehicle, wherein the differential gear unit comprises: an annular ring gear arranged to rotate around a rotational axis extending in an axial direction; a first side gear configured for distributing a first output torque to a first drive shaft, and a second side gear configured for distributing a second output torque to a second drive shaft; at least a first differential pinion gear and a second differential pinion gear rotatably arranged on a pinion pin, wherein the at least first differential pinion gear and second differential pinion gear are configured for engaging the first side gear and the second side gear; wherein the differential gear unit further comprises a decoupling element arranged radially inside the ring gear, the decoupling element comprising a radially outer toothed surface, wherein the decoupling element is rotatably arranged in relation to the ring gear, wherein the pinion pin is connected to and extending diametrically across the decoupling element, wherein the differential gear unit further comprises a clutch sleeve slidably arranged relative to the ring gear and the decoupling element in the axial direction, the clutch sleeve comprising a sleeve body arranged radially outside a hub structure of the ring gear, the sleeve body having a first toothed surface, the first toothed surface being arranged on a radially inner surface of the sleeve body, wherein the clutch sleeve upon displacement in the axial direction is configured for: disconnecting the ring gear from the decoupling element in a first axial position, allowing rotational movement of the decoupling element relative to the ring gear; connecting the ring gear to the decoupling element in a second axial position, preventing rotational movement of the decoupling element relative to the ring gear; and connecting the ring gear to a park-lock structure in a third axial position, and wherein the radially outer toothed surface of the decoupling element is configured for being disengaged from the first toothed surface in the first axial position and engaging the first toothed surface in the second axial position and third axial position.

2. The differential gear unit according to claim 1, wherein the clutch sleeve in the third axial position is configured for connecting the ring gear to the park-lock structure and the decoupling element, preventing rotational movement of the decoupling element relative to the ring gear and rotational movement of the ring gear relative to the park-lock structure.

3. The differential gear unit according to claim 1, wherein the ring gear comprises the hub structure, wherein the decoupling element is arranged radially inside the hub structure and rotatably arranged in relation to an internal surface of the hub structure.

4. The differential gear unit according to claim 1, wherein the sleeve body comprises a second toothed surface, wherein the second toothed surface is arranged on a radially outer surface of the sleeve body, wherein the park-lock structure comprises a toothed area configured for being disengaged from the second toothed surface in the first axial position and second axial position and engaging the second toothed surface in the third axial position.

5. The differential gear unit according to claim 1, wherein the decoupling element has a collar configuration, and wherein the clutch sleeve has a collar configuration.

6. The differential gear unit according to claim 1, wherein the ring gear comprises the hub structure, wherein the decoupling element is arranged radially inside the hub structure and rotatably arranged in relation to an internal surface of the hub structure, and wherein the park-lock structure has a ring or arc configuration, wherein the park-lock structure is arranged radially outside the hub structure, wherein the park-lock structure is connected to a differential housing.

7. The differential gear unit according to claim 1, wherein the first and second side gears and the at least first differential pinion gear and second differential pinion gear are positioned radially inside the decoupling element; wherein the decoupling element via the at least first differential pinion gear and second differential pinion gear is configured for transferring input torque from the ring gear to the first side gear and second side gear.

8. The differential gear unit according to claim 1, wherein the differential gear unit further comprises an actuating unit in engagement with the clutch sleeve, wherein the actuating unit is adapted for displacing the clutch sleeve relative to the ring gear and the decoupling element, in the axial direction, between the first axial position, the second axial position, and the third axial position.

9. A vehicle comprising the differential gear unit according to claim 1.

10. A differential gear unit for a vehicle, wherein the differential gear unit comprises: an annular ring gear arranged to rotate around a rotational axis extending in an axial direction, the ring gear comprising a hub structure, the hub structure comprising one or more grooves extending in the axial direction; a first side gear configured for distributing a first output torque to a first drive shaft, and a second side gear configured for distributing a second output torque to a second drive shaft; at least a first differential pinion gear and a second differential pinion gear rotatably arranged on a pinion pin, wherein the at least first differential pinion gear and second differential pinion gear are configured for engaging the first side gear and the second side gear; wherein the differential gear unit further comprises a decoupling element arranged radially inside the hub structure of the ring gear and rotatably arranged in relation to an internal surface of the hub structure, the decoupling element comprising a radially outer toothed surface, wherein the decoupling element is rotatably arranged in relation to the ring gear, wherein the pinion pin is connected to and extending diametrically across the decoupling element, wherein the differential gear unit further comprises a clutch sleeve slidably arranged relative to the ring gear and the decoupling element in the axial direction, the clutch sleeve comprising a sleeve body with a first toothed surface having one or more radially protruding tooth elements, the first toothed surface being arranged on a radially inner surface of the sleeve body, wherein the clutch sleeve upon displacement in the axial direction is configured for: disconnecting the ring gear from the decoupling element in a first axial position, allowing rotational movement of the decoupling element relative to the ring gear; connecting the ring gear to the decoupling element in a second axial position, preventing rotational movement of the decoupling element relative to the ring gear; and connecting the ring gear to a park-lock structure in a third axial position, and wherein the one or more grooves are configured for receiving the one or more radially protruding tooth elements of the first toothed surface, wherein the one or more radially protruding tooth elements of the first toothed surface are configured for preventing rotational movement of the clutch sleeve relative the hub structure through engagement with the one or more grooves, wherein the radially outer toothed surface of the decoupling element is configured for being disengaged from the first toothed surface in the first axial position and the one or more radially protruding tooth elements of the first toothed surface are configured for engaging the radially outer toothed surface in the second axial position and third axial position.

11. The differential gear unit according to claim 10, wherein the clutch sleeve in the third axial position is configured for connecting the ring gear to the park-lock structure and the decoupling element, preventing rotational movement of the decoupling element relative to the ring gear and rotational movement of the ring gear relative to the park-lock structure.

12. A method for operating a differential gear unit for a vehicle, wherein the differential gear unit comprises: an annular ring gear arranged to rotate around a rotational axis extending in an axial direction; a first side gear configured for distributing a first output torque to a first drive shaft, and a second side gear configured for distributing a second output torque to a second drive shaft; at least a first differential pinion gear and a second differential pinion gear rotatably arranged on a pinion pin, wherein the at least first differential pinion gear and second differential pinion gear are configured for engaging the first side gear and the second side gear; wherein the differential gear unit further comprises a decoupling element arranged radially inside the ring gear, the decoupling element comprising a radially outer toothed surface, wherein the decoupling element is rotatably arranged in relation to the ring gear, wherein the pinion pin is connected to and extending diametrically across the decoupling element, wherein the differential gear unit further comprises a clutch sleeve slidably arranged relative to the ring gear and the decoupling element in the axial direction, the clutch sleeve comprising a sleeve body arranged radially outside a hub structure of the ring gear, the sleeve body having a first toothed surface, the first toothed surface being arranged on a radially inner surface of the sleeve body, wherein the method comprises the steps: displacing the clutch sleeve in the axial direction to a first axial position for disconnecting the ring gear from the decoupling element, wherein in the first axial position rotational movement of the decoupling element relative to the ring gear is allowed; displacing the clutch sleeve in the axial direction to a second axial position for connecting the first toothed surface of the clutch sleeve to the radially outer toothed surface of the decoupling element, wherein in the second axial position rotational movement of the decoupling element relative to the ring gear is prevented; displacing the clutch sleeve in the axial direction to a third axial position for connecting the first toothed surface of the clutch sleeve to a park-lock structure.

13. The method according to claim 12, wherein the method further comprises the step: connecting the ring gear to the park-lock structure and the decoupling element with the clutch sleeve in the third axial position for preventing rotational movement of the decoupling element relative to the ring gear and rotational movement of the ring gear relative to the park-lock structure.

14. The method according to claim 12, wherein the differential gear unit further comprises an actuating unit in engagement with the clutch sleeve, wherein the method further comprises the step: displacing the clutch sleeve relative to the ring gear and the decoupling element in the axial direction with the actuating unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure will be described in detail in the following, with reference to the attached drawings, in which

(2) FIG. 1 shows schematically in an exploded perspective view, a differential gear unit according to the disclosure,

(3) FIG. 2A-2B show schematically in perspective views, the differential gear unit according to the disclosure,

(4) FIG. 3A-3C show schematically in cross-sectional views, the differential gear unit in different operating positions according to the disclosure,

(5) FIG. 4 shows schematically in an exploded perspective view, a differential gear unit according to an alternative embodiment of the disclosure,

(6) FIG. 5A-5B show schematically in perspective views, the differential gear unit according to the alternative embodiment of the disclosure, and

(7) FIG. 6A-6C show schematically in cross-sectional views, the differential gear unit in different operating positions according to the alternative embodiment of the disclosure.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(8) Various aspects of the disclosure will hereinafter be described in conjunction with the appended drawings to illustrate and not to limit the disclosure, wherein like designations denote like elements, and variations of the described aspects are not restricted to the specifically shown embodiments, but are applicable on other variations of the disclosure.

(9) FIGS. 1, 2A-2B, and 3A-3C schematically show a differential gear unit 1 for a vehicle according to a first embodiment, and FIGS. 4, 5A-5B, and 6A-6C schematically show a differential gear unit 1 for a vehicle according to an alternative embodiment. The differential gear unit 1 of the respective illustrated embodiments comprise an annular ring gear 2 arranged to rotate around a rotational axis A extending in an axial direction DA. The ring gear 2 comprises an external surface 2c, and a hub structure 2a with an internal surface 2b. The external surface 2c is arranged as a toothed surface for driving engagement with a non-illustrated rotating input drive shaft, where the toothed surface of the ring gear 2 is meshing with a toothed surface of for example an input drive shaft pinion gear. In alternative non-illustrated embodiments, the toothed surface may instead be arranged on other parts of the ring gear 2.

(10) The differential gear unit 1 of the illustrated embodiments further comprises side gears and differential pinion gears of the bevel gear type. A first side gear 3a is configured for distributing a first output torque T.sub.O1 to a first drive shaft S.sub.1, and a second side gear 3b is configured for distributing a second output torque T.sub.O2 to a second drive shaft S.sub.2. The first side gear 3a and the second side gear 3b are arranged on opposite sides of the ring gear 2 in the axial direction DA. At least a first differential pinion gear 4a and a second differential pinion gear 4b are configured for engaging the first side gear 3a and the second side gear 3b, and in the embodiments illustrated in FIGS. 1, 2A-2B, 3A-3C, 4, 5A-5B, and 6A-6C, the differential gear unit 1 comprises two differential pinion gears. However, the differential gear unit 1 may instead be arranged with three or more differential pinion gears. The differential pinion gears are as illustrated in the figures in a conventional manner arranged with toothed surfaces that are engaging toothed surfaces of the side gears. The first differential pinion gear 4a and the second differential pinion gear 4b are rotatably arranged on a pinion pin 5, and the differential pinion gears are configured for transferring torque from the ring gear 2 to the side gears.

(11) The differential gear unit 1 further comprises a decoupling element 6 arranged radially inside the ring gear 2, as illustrated in for example FIGS. 3A-3C and 6A-6C. The decoupling element 6 is rotatably arranged in relation to the ring gear 2, and the pinion pin 5 is connected to and extending diametrically across the decoupling element 6. The decoupling element 6 has in the illustrated embodiments a collar-like configuration. The decoupling element 6 is at least partly arranged radially inside the hub structure 2a of the ring gear 2, and an outer surface 6a of the decoupling element 6 is rotatably arranged in relation to the internal surface 2b of the ring gear 2. One or more inner bearings 14 may be arranged between the outer surface 6a of the decoupling element 6 and the internal surface 2b of the ring gear 2, as schematically illustrated in for example FIGS. 1 and 4. The pinion pin 5 is depending on operational states of the differential gear unit 1 arranged for transferring torque from the ring gear 2 to the respective differential pinion gears, as will be further described below. Upon rotation of the ring gear 2 by for example the input drive shaft pinion gear, the pinion pin 5 could through the attachment to the decoupling element 6, and the arrangement of the decoupling element 6 in relation to the ring gear 2, be arranged to rotate with the ring gear 2, depending on the operational state of the differential gear unit 1. The rotational movement of the pinion pin 5 with the ring gear 2 via the decoupling element 6 is used for transferring the torque to the first side gear 3a and the second side gear 3b via the first differential pinion gear 4a and the second differential pinion gear 4b. With the configuration of the differential gear unit 1, the side gears and the differential pinion gears are positioned radially inside the ring gear 2, as indicated in for example FIGS. 2A-2B and 5A-5B. The pinion pin 5 is thus configured for transferring an input torque T.sub.1 from the ring gear 2 to the side gears via the differential pinion gears.

(12) The decoupling element 6 comprises diametrically opposite openings 6c for holding the pinion pin 5 in position relative to the decoupling element 6. With this arrangement, the pinion pin 5 is positioned diametrically across the decoupling element 6, as understood from for example FIGS. 1, 2A-2B, 4 and 5A-5B. Instead of the openings 6c, the decoupling element 6 may be arranged with slots or similar arrangements for holding the pinion pin 5.

(13) The differential gear unit 1 further comprises a clutch sleeve 7 slidably arranged relative to the ring gear 2 and the decoupling element 6 in the axial direction DA. With this configuration, the clutch sleeve 7 is allowed to slide axially in different operational positions in relation to the ring gear 2 and the decoupling element 6. Upon displacement in the axial direction DA, the clutch sleeve 7 is configured for being positioned in a first axial position P.sub.A1, a second axial position P.sub.A2, and a third axial position P.sub.A3. In the embodiments illustrated in FIGS. 1, 2A-2B, 3A-3C, 4, 5A-5B, and 6A-6C, the clutch sleeve 7 has a collar-like configuration. It should however be understood that the clutch sleeve 7 may have other suitable shapes and configurations. The differential gear unit 1 further comprises an actuating unit 9 in engagement with the clutch sleeve 7. The actuating unit 9 is used for displacing the clutch sleeve 7 relative to the ring gear 2 and the decoupling element 6 in the axial direction DA, and the actuating unit 9 is suitably connected to a control unit 13 for operating the differential gear unit 9 into the different axial positions, as schematically shown in FIGS. 3A-3C and 6A-6C. The actuating unit 9 may be of any suitable type, such as for example a linear actuator, a solenoid, or an electric motor.

(14) Different axial positions of the clutch sleeve are schematically illustrated in FIGS. 3A-3C and 6A-6C. In a first axial position P.sub.A1, as illustrated in FIGS. 3A and 6A, the ring gear 2 is disconnected from the decoupling element 6, and in the first axial position P.sub.A1 rotational movement of the decoupling element 6 relative to the ring gear 2 is allowed. In a second axial position P.sub.A2, as illustrated in FIGS. 3B and 6B, the ring gear 2 is connected to the decoupling element 6, and in the second axial position P.sub.A2 rotational movement of the decoupling element 6 relative to the ring gear 2 is prevented. In a third axial position P.sub.A3, as illustrated in FIGS. 3C and 6C, the ring gear 2 is connected to a park-lock structure 8, and in the third axial position P.sub.A3, the ring gear is prevented from rotating relative to the park-lock structure 8.

(15) In the embodiments illustrated in FIGS. 3C and 6C, the clutch sleeve 7 is in the third axial position P.sub.A3 not only configured for connecting the ring gear 2 to the park-lock structure 8, but also configured for simultaneously connecting the ring gear 2 to the decoupling element 6. This configuration prevents rotational movement of the decoupling element 6 relative to the ring gear 2, and rotational movement of the ring gear 2 relative to the park-lock structure 8. Thus, both the decoupling element 6 and the ring gear 2 are prevented from rotating relative to the park-lock structure 8 for an efficient park-locking function, where the wheels of the vehicle are prevented from rotating.

(16) The clutch sleeve 7 comprises a sleeve body 7a with a first toothed surface 7b, as shown in for example FIGS. 1 and 4. The clutch sleeve 7 has in the illustrated embodiments a collar-like configuration and the sleeve body 7a is arranged radially outside the hub structure 2a, as understood from FIGS. 3A-3C and 6A-6C. The first toothed surface 7b is arranged on a radially inner surface 7d of the sleeve body 7a.

(17) The hub structure 2a comprises one or more grooves 10 extending in the axial direction DA. The one or more grooves 10 are configured for receiving one or more radially protruding tooth elements 11 of the first toothed surface 7b. As understood from FIGS. 3A-3C and 6A-6C, the radially protruding tooth elements 11 are through engagement with the grooves 10 configured for preventing rotational movement of the clutch sleeve 7 relative the hub structure 2a. The decoupling element 6 comprises a radially outer toothed surface 6b with one or more radially protruding tooth elements 15, as shown in for example FIGS. 1 and 4. The one or more radially protruding tooth elements 11 of the first toothed surface 7b are further configured for engaging the one or more radially protruding tooth elements 15 of the radially outer toothed surface 6b in the second axial position P.sub.A2 and third axial position P.sub.A3. The decoupling element 6 may be provided with a track, a groove, or similar arrangement for the tooth elements 11 of the first toothed surface 7b, preventing the tooth elements 11 from engaging the decoupling element 6 in the first axial position P.sub.A1, allowing the decoupling element 6 to rotate relative to the ring gear 2.

(18) The radially outer toothed surface 6b and the first toothed surface 7b are disengaged from each other in the first axial position P.sub.A1, as shown in FIGS. 3A and 6A. When the radially outer toothed surface 6b and the first toothed surface 7b are disengaged from each other in the first axial position P.sub.A1, the decoupling element 6 is free to rotate relative to the ring gear 2 and torque is prevented from being transferred from the ring gear 2 to the differential pinion gears via the decoupling element 6. The radially outer toothed surface 6b and the first toothed surface 7b are in engagement with each other in the second axial position P.sub.A2 and in the third axial position P.sub.A3 via the radially protruding tooth elements 11 of the first toothed surface 7b and the radially protruding tooth elements 15 of the radially outer toothed surface 6b, as shown in FIGS. 3B-3C and 6B-6C. When the radially outer toothed surface 6b and the first toothed surface 7b are in engagement with each other in the second and third axial positions, the rotational movement of the decoupling element 6 relative to the ring gear 2 is prevented and torque can be transferred from the ring gear 2 to the differential pinion gears and the side gears via the decoupling element 6.

(19) The sleeve body 7a further comprises a second toothed surface 7c with one or more protruding tooth elements 16, as shown in for example FIGS. 1 and 4. The second toothed surface 7c is arranged on a radially outer surface 7e of the sleeve body 7a. The park-lock structure 8 comprises a toothed area 8a with one or more protruding tooth elements 17, as shown in for example FIGS. 1 and 4. The second toothed surface 7c and the toothed area 8a are disengaged from each other in the first axial position P.sub.A1 and in the second axial position P.sub.A2, as shown in FIGS. 3A-3B and 6A-6B. When the second toothed surface 7c and the toothed area 8 are disengaged from each other in the first and second axial positions, the ring gear 2 is free to rotate relative to the park-lock structure 8 and in these axial positions, the park-lock function is deactivated. The second toothed surface 7c and the toothed area 8 are in engagement with each other in the third axial position P.sub.A3, as shown in FIGS. 3C and 6C. When the second toothed surface 7c and the toothed area 8 are in engagement with each other in the third axial position P.sub.A3, the ring gear 2 is prevented from rotating relative to the park-lock structure 8 and in this axial position, the park-lock function is activated.

(20) As understood from FIGS. 3A-3C and 6A-6C, the one or more protruding tooth elements 16 of the second toothed surface 7c are configured for engaging the one or more protruding tooth elements 17 of the toothed area 8a in the third axial position P.sub.A3.

(21) In the embodiment illustrated in FIGS. 1, 2A-2B, and 3A-3C, the park-lock structure 8 has a ring-like configuration. The park-lock structure 8 is arranged radially outside the hub structure 2a, as shown in for example FIGS. 3A-3C. In the embodiment illustrated in FIGS. 4, 5A-5B, and 6A-6C, the park-lock structure 8 has an arc-like configuration. The park-lock structure 8 is arranged radially outside the hub structure 2a, as shown in for example FIGS. 6A-6C. The park-lock structure 8 is suitably connected to a differential housing 12, or similar structure of a vehicle drivetrain. It should however be understood that the park lock structure 8 may have any suitable shape, design, and configuration for engaging the clutch sleeve 7.

(22) The side gears 3a, 3b and the at least first differential pinion gear 4a and second differential pinion gear 4b are positioned radially inside the decoupling element 6, as shown in FIGS. 2A-2B, 3A-3C, 5A-5B, and 6A-6C. The decoupling element 6 is via the at least first differential pinion gear 4a and second differential pinion gear 4b configured for transferring input torque T.sub.1 from the ring gear 2 to the first side gear 3a and second side gear 3b.

(23) As described above, the actuating unit 9 is in engagement with the clutch sleeve 7 and suitably controlled with the control unit 13. The actuating unit 9 is adapted for displacing the clutch sleeve 7 relative to the ring gear 2 and the decoupling element 6, in the axial direction DA, between the first axial position P.sub.A1, the second axial position P.sub.A2, and the third axial position P.sub.A3.

(24) As shown in for example FIGS. 1 and 4, the differential gear unit 1 further comprises a first bearing flange 18a arranged in connection to a first side of the ring gear 2, and a second bearing flange 18b arranged in connection to a second side of the ring gear 2. The first bearing flange 18a, the second bearing flange 18b, are configured for at least partly enclosing the first side gear 3a, the second side gear 3b, the first differential pinion gear 4a, and the second differential pinion gear 4b. The bearing flanges are arranged as cover structures for keeping lubrication in place and for holding bearings. The first bearing flange 18a and the second bearing flange 18b may have any suitable configuration, and each bearing flange may be provided with one or more seals in connection to its corresponding side gear. The first bearing flange 18a and the second bearing flange 18b are suitably symmetrical in shape for a cost efficient and simple construction of the differential gear unit 1. As shown in FIG. 1, the first bearing flange 18a is arranged with a first bearing surface 19a for holding a first bearing 20a. The second bearing flange 18b is arranged with a second bearing surface 19b for holding a second bearing 20b. Each of the first bearing flange 18a and the second bearing flange 18b is suitably connected to the ring gear 2 with one or more welds or other fastening means.

(25) To operate the differential gear unit 1, the actuating unit 9 is displacing the clutch sleeve 7 relative to the ring gear 2 and the decoupling element 6, in the axial direction DA, between the first axial position Pal, the second axial position P.sub.A2, and the third axial position P.sub.A3. The different axial positions may be operated in any sequence, depending on the driving conditions of the vehicle.

(26) By displacing the clutch sleeve 7 of the illustrated embodiments in the axial direction DA to the first axial position Pal, the ring gear 2 is disconnected from the decoupling element 6, as illustrated in FIGS. 3A and 6A. The first axial position P.sub.A1 is reached from the second axial position P.sub.A2, or from the third axial position P.sub.A3 via the second axial position P.sub.A2, as understood from FIGS. 3A-3C and 6A-6C. In the first axial position Pal, rotational movement of the decoupling element 6 relative to the ring gear 2 is allowed, and thus no torque is transferred from the ring gear 2 to the differential pinion gears and the side gears due to the non-engagement of the radially protruding tooth elements 11 of the clutch sleeve 7 and the radially protruding tooth elements 15 of the decoupling element 6. The first axial position P.sub.A1 is used during driving of the vehicle when there is no need to transfer torque from a propulsion unit, such as an internal combustion engine and/or an electric motor, to the wheels of the vehicle, for example when the vehicle is allowed to roll without any torque transfer.

(27) By displacing the clutch sleeve 7 of the illustrated embodiments in the axial direction DA to the second axial position P.sub.A2, the ring gear 2 is connected to the decoupling element 6, as illustrated in FIGS. 3B and 6B. The second axial position P.sub.A2 is reached from the first axial position Pal, or from the third axial position P.sub.A3, as understood from FIGS. 3A-3C and 6A-6C. In the second axial position P.sub.A2, rotational movement of the decoupling element 6 relative to the ring gear 2 is prevented, and thus torque is transferred from the ring gear 2 to the differential pinion gears and the side gears due to the engagement of the radially protruding tooth elements 11 of the clutch sleeve 7 with the radially protruding tooth elements 15 of the decoupling element 6. The second axial position P.sub.A2 is used during driving of the vehicle when there is a need to transfer torque from the propulsion unit to the wheels of the vehicle.

(28) By displacing the clutch sleeve 7 of the illustrated embodiments in the axial direction DA to the third axial position P.sub.A3, the ring gear 2 is connected both to the decoupling element 6 and to the park-lock structure 8, as illustrated in FIGS. 3C and 6C. The third axial position P.sub.A3 is reached from the second axial position P.sub.A2, or from the first axial position P.sub.A1 via the second axial position P.sub.A2, as understood from FIGS. 3A-3C and 6A-6C. In the third axial position P.sub.A3, rotational movement of the decoupling element 6 relative to the ring gear 2 is prevented, and rotational movement of the ring gear 2 relative to the park-lock structure is prevented. Thus, the park-lock functionality is enabled through the engagement of the radially protruding tooth elements 11 of the clutch sleeve 7 with the radially protruding tooth elements 15 of the decoupling element 6, in combination with the engagement of the protruding tooth elements 16 of the clutch sleeve 7 with the protruding tooth elements 17 of the park-lock structure 8. In the third axial position P.sub.A3, the ring gear 2 is connected to both the park-lock structure 8 and the decoupling element 6 for preventing rotational movement of the decoupling element 6 relative to the ring gear 2 and rotational movement of the ring gear 2 relative to the park-lock structure 8. The decoupling element 6 and the ring gear 2 are prevented from rotating relative to the park-lock structure 8 for an efficient park-locking function. The third axial position P.sub.A3 is used during non-driving of the vehicle when there is a need to prevent the vehicle from rolling, such as when the vehicle is parked.

(29) It will be appreciated that the above description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. While specific examples have been described in the specification and illustrated in the drawings, it will be understood by those of ordinary skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure as defined in the claims. Furthermore, modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular examples illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out the teachings of the present disclosure, but that the scope of the present disclosure will include any embodiments falling within the foregoing description and the appended claims. Reference signs mentioned in the claims should not be seen as limiting the extent of the matter protected by the claims, and their sole function is to make claims easier to understand.

REFERENCE SIGNS

(30) 1: Differential gear unit 2: Ring gear 2a: Hub structure 2b: Internal surface 2c: External surface 3a: First side gear 3b: Second side gear 4a: First differential pinion gear 4b: Second differential pinion gear 5: Pinion pin 6: Decoupling element 6a: Outer surface 6b: Outer toothed surface 6c: Opening 7: Clutch sleeve 7a: Sleeve body 7b: First toothed surface 7c: Second toothed surface 7d: Radially inner surface 7e: Radially outer surface 8: Park-lock structure 8a: Toothed area 9: Actuating unit 10: Groove 11: Tooth elements, First toothed surface 12: Differential housing 13: Control unit 14: Inner bearing 15: Tooth elements, Outer toothed surface 16: Tooth elements, Second toothed surface 17: Tooth elements, Toothed area 18a: First bearing flange 18b: Second bearing flange 19a: First bearing surface 19b: Second bearing surface 20a First bearing 20b Second bearing DA: Axial direction P.sub.A1: First axial position P.sub.A2: Second axial position P.sub.A3: Third axial position S.sub.1: First drive shaft S.sub.2: Second drive shaft T.sub.1: Input torque T.sub.O1: First output torque T.sub.O2: Second output torque