Differential device, drive device for vehicle, and friction engagement device

Abstract

A differential device (100) comprises a friction engagement device (5) that engages and disengages a first rotary member (21) and a second rotary member (22) which constitute an output shaft (2). A first friction member (51) is supported by the first rotary member (21), and a second friction member (52) is supported by the second rotary member (22). A pressing mechanism (6) comprises a first pressing member (61) that is supported by a non-rotary member (NR) and is freely movable in an axial direction (L) relative to the non-rotary member (NR), a second pressing member (62) that is supported by a target rotary member (T), rotates integrally with the target rotary member (T), and is freely movable in the axial direction (L) relative to the target rotary member (T), a transmission member (63) that transmits an axial direction (L) pressing force from the first pressing member (61) to the second pressing member (62) while allowing relative rotation of the first pressing member (61) and the second pressing member (62), and a pressing drive device that presses the first pressing member (61) toward the second pressing member (62) side in the axial direction (L).

Description

Differential device, vehicle drive device, and friction engagement device

[0008]

[0001] The present invention relates to a differential device, a vehicle drive device, and a friction engagement device, which include an input member to which a driving force is input, an output shaft, and a differential gear mechanism that distributes the driving force input to the input member to the output shaft and a shaft different from the output shaft.

[0002] An example of such a technology is disclosed in Patent Document 1 below. In the following description of the background art, the reference numerals in Patent Document 1 are cited within parentheses.

[0003] The differential device of Patent Document 1 includes an engagement device (20) that engages and disengages a first rotating member (21) and a second rotating member (22) that constitute an output shaft.

[0004] Korean Patent Publication No. 10-2017-0123869

[0005] The above engagement device (20) is an engagement-type engagement device that engages and disengages the first rotating member (21) and the second rotating member (22) by axially moving a sleeve (23) with a fork (25).

[0006] Therefore, when engaging the first rotating member (21) and the second rotating member (22), it is necessary to appropriately adjust the engagement phase. On the other hand, when disengaging the first rotating member (21) and the second rotating member (22), it is necessary to bring their transmission torques close to zero. Therefore, in the differential device of Patent Document 1, it has been difficult to quickly perform the engagement operation and the disengagement operation of the engagement device (20).

[0007] Therefore, it is desired to realize a technology that can quickly perform the engagement operation and the disengagement operation of the engagement device.

[0008] In view of the above, the characteristic configuration of the differential is a differential comprising: an input member to which a driving force is input; an output shaft; and a differential gear mechanism that distributes the driving force input to the input member to the output shaft and an axis different from the output shaft, further comprising a friction engagement device for engaging and disengaging a first rotating member and a second rotating member constituting the first output shaft, wherein the direction along the rotation axis of the first output shaft is defined as the axial direction, the friction engagement device comprises a first friction member and a second friction member facing each other in the axial direction, and a pressing mechanism for pressing the first friction member and the second friction member in the axial direction, the first rotating member and the second rotating member are arranged coaxially in a state in which they can rotate relative to each other, the first friction member is supported by the first rotating member so as to rotate integrally with the first rotating member, the second friction member is supported by the second rotating member so as to rotate integrally with the second rotating member, and the pressing mechanism is The device comprises: a first pressing member supported by a non-rotating member and movable in the axial direction relative to the non-rotating member; a second pressing member supported by a target rotating member which is either the first rotating member or the second rotating member, rotating integrally with the target rotating member and movable in the axial direction relative to the target rotating member; a transmission member that transmits the axial pressing force from the first pressing member to the second pressing member while allowing relative rotation between the first pressing member and the second pressing member; and a pressing drive device that presses the first pressing member toward the second pressing member in the axial direction so that the second pressing member presses the first friction member and the second friction member in the axial direction.

[0009] This feature configuration allows for engagement between the first and second rotating members without considering the meshing phase, compared to a configuration with a meshing type engagement device. This enables rapid engagement of the friction engagement device. Furthermore, disengagement can be performed even when torque is being transmitted between the first and second rotating members. This enables rapid disengagement of the friction engagement device. In addition, the friction engagement device can be equipped with a function to interrupt unintended torque transmission. Moreover, this feature configuration includes a pressing mechanism with a first pressing member supported by a non-rotating member, and the first pressing member is pressed by a pressing drive device. This allows the pressing drive device to be supported on the side of the non-rotating member. Therefore, it is easier to mount the differential on a vehicle.

[0010] In view of the above, a characteristic configuration of a vehicle drive system is a vehicle drive system comprising the differential gear described above and a rotating electric machine that outputs the driving force input to the input member and functions as a driving force source for the wheels, wherein the axial arrangement region of the rotating electric machine and the axial arrangement region of the friction engagement device overlap with each other.

[0011] With this characteristic configuration, the output shaft is composed of a first rotating member and a second rotating member arranged coaxially, which tends to increase the axial dimension of the output shaft. However, because the axial arrangement region of the friction engagement device that engages and disengages the first and second rotating members overlaps with the axial arrangement region of the rotating electric machine, the overall axial dimension of the vehicle drive system can be kept small.

[0012] In view of the above, the characteristic configuration of the friction engagement device is a friction engagement device provided on the first output shaft of a differential gear mechanism that distributes the driving force input to an input member to a first output shaft and a second output shaft different from the first output shaft, which engages and disengages a first rotating member and a second rotating member constituting the first output shaft, comprising: a first friction member and a second friction member facing each other in the axial direction along the rotation axis of the first output shaft, and a pressing mechanism that presses the first friction member and the second friction member in the axial direction, wherein the first rotating member and the second rotating member are arranged coaxially in a state in which they can rotate relative to each other, the first friction member is supported by the first rotating member so as to rotate integrally with the first rotating member, the second friction member is supported by the second rotating member so as to rotate integrally with the second rotating member, and the pressing mechanism comprises a first pressing member supported by a non-rotating member and movable in the axial direction relative to the non-rotating member, The present invention comprises: a second pressing member supported by a target rotating member which is either the first rotating member or the second rotating member, which rotates integrally with the target rotating member and is movable in the axial direction relative to the target rotating member; a transmission member which transmits the axial pressing force from the first pressing member to the second pressing member while allowing relative rotation between the first pressing member and the second pressing member; and a pressing drive device which presses the first pressing member toward the second pressing member in the axial direction so that the second pressing member presses the first friction member and the second friction member in the axial direction.

[0013] This feature configuration allows for engagement between the first and second rotating members without considering the meshing phase, compared to, for example, a meshing-type engagement device. This enables rapid engagement of the friction engagement device. Furthermore, disengagement can be performed even when torque is being transmitted between the first and second rotating members. This enables rapid disengagement of the friction engagement device. In addition, the friction engagement device can be equipped with a function to interrupt unintended torque transmission. Moreover, this feature configuration includes a pressing mechanism comprising a first pressing member supported by a non-rotating member, and the first pressing member is pressed by a pressing drive device. This allows the pressing drive device to be supported on the side of the non-rotating member. Therefore, it is easier to mount the friction engagement device on a vehicle.

[0014] Figure 1 shows a differential device for a vehicle drive system equipped with a differential device according to the first embodiment. Figure 2 shows a differential device for a vehicle drive system equipped with a differential device according to the second embodiment, which shows a pressing drive device.

[0015] 1. In the following first embodiments, the differential gear 100 according to the first embodiment will be described with reference to Figures 1 to 3.

[0016] As shown in Figure 1, the differential gear 100 comprises an input member 1, a first output shaft 2, a differential gear mechanism 4, and a friction engagement device 5. In this embodiment, the differential gear 100 further comprises a case 9.

[0017] The input member 1 is a member to which driving force is input. In this embodiment, the input member 1 is the first gear G1.

[0018] The differential gear mechanism 4 is configured to distribute the driving force input to the input member 1 to the first output shaft 2 and the second output shaft 3, which is a different shaft from the first output shaft 2.

[0019] The first output shaft 2 is an "output shaft" comprising a first rotating member 21 and a second rotating member 22. The first rotating member 21 and the second rotating member 22 are arranged coaxially in a state where they can rotate relative to each other. In this embodiment, the first output shaft 2 and the second output shaft 3 are each driven and connected to a wheel W.

[0020] Herein, in this application, "driving connection" refers to a state in which two rotating elements are connected in a manner that can transmit driving force, and includes a state in which the two rotating elements are connected so as to rotate as a whole, or a state in which the two rotating elements are connected in a manner that can transmit driving force via one or more transmission members. Such transmission members include various members that transmit rotation at the same speed or at a variable speed, such as shafts, gear mechanisms, belts, chains, etc. In addition, the transmission members may also include engagement devices that selectively transmit rotation and driving force, such as friction engagement devices, meshing engagement devices, etc.

[0021] The friction engagement device 5 is a friction-type engagement device that engages and disengages the first rotating member 21 and the second rotating member 22 of the first output shaft 2. Here, the friction-type engagement device is configured so that the engagement state (engaged state / disengaged state) is controlled according to the engagement pressure of a pair of engagement elements. In the friction-type engagement device, the engagement state includes a "direct engagement state" and a "slip engagement state". The direct engagement state is a state in which a pair of engagement elements are engaged without differential rotation. The slip engagement state is a state in which a pair of engagement elements are engaged with differential rotation.

[0022] Case 9 houses the differential gear mechanism 4.

[0023] In the following explanation, the direction along the axis X, which is the rotational axis of the first output shaft 2, will be referred to as the "axial direction L". In the axial direction L, the side on which the first output shaft 2 is positioned relative to the differential gear mechanism 4 will be referred to as the "first axial side L1", and the side on which the second output shaft 3 is positioned relative to the differential gear mechanism 4 will be referred to as the "second axial side L2". The direction perpendicular to the axis X will be referred to as the "radial direction R".

[0024] In this embodiment, the differential gear mechanism 4 is a bevel gear type differential gear mechanism comprising a differential case 41, a pair of differential pinion gears 42, a first side gear 43, and a second side gear 44.

[0025] The differential case 41 houses a pair of differential pinion gears 42, a first side gear 43, and a second side gear 44. The differential case 41 is rotatably supported relative to the case 9. In this embodiment, the differential case 41 is connected to the first gear G1 so as to rotate integrally with it around the axis X.

[0026] The pair of differential pinion gears 42 are arranged to face each other in the radial direction R. The pair of differential pinion gears 42 are mounted on a pinion shaft 42a that is supported to rotate integrally with the differential case 41. Each of the pair of differential pinion gears 42 is configured to rotate freely (rotate) about the pinion shaft 42a and to rotate freely (revolve) about the rotation axis (here, axis X) of the differential case 41.

[0027] The first side gear 43 and the second side gear 44 mesh with a pair of differential pinion gears 42. The first side gear 43 is positioned on the first axial side L1 with respect to the pinion shaft 42a. The second side gear 44 is positioned on the second axial side L2 with respect to the pinion shaft 42a. In this embodiment, the first side gear 43 is connected to rotate integrally with the first rotating member 21 of the first output shaft 2. The second side gear 44 is connected to rotate integrally with the second output shaft 3.

[0028] As shown in Figure 1, in this embodiment, the differential gear 100 is provided in the vehicle drive unit D. The vehicle drive unit D comprises a rotating electric machine MG and a reduction gear RD.

[0029] In this embodiment, the case 9 houses the rotating electric machine MG and the reduction gear RD in addition to the differential gear mechanism 4.

[0030] The rotating electric machine MG is configured to output the driving force input to the input member 1. The rotating electric machine MG functions as a driving force source for the wheel W. The rotating electric machine MG has the function of a motor that generates power when power is supplied, and the function of a generator that generates power when power is supplied.

[0031] The rotating electric machine MG comprises a stator ST and a rotor RT. The stator ST is fixed to a non-rotating member (in this case, a case 9). The rotor RT is rotatably supported relative to the stator ST. In this embodiment, the rotor RT is connected to rotate integrally with the second gear G2.

[0032] In this embodiment, the axial L arrangement region of the rotating electric machine MG and the axial L arrangement region of the friction engagement device 5 overlap with each other.

[0033] The reduction gear RD is configured to reduce the rotation of the rotor RT and transmit it to the differential gear mechanism 4. In this embodiment, the reduction gear RD includes a third gear G3 and a fourth gear G4.

[0034] The third gear G3 meshes with the second gear G2. The third gear G3 is formed with a larger diameter than the second gear G2.

[0035] The fourth gear G4 is connected to the third gear G3 so as to rotate integrally with it. The fourth gear G4 meshes with the first gear G1. The fourth gear G4 is formed to have a smaller diameter than the first gear G1.

[0036] As shown in Figure 2, the friction engagement device 5 comprises a first friction member 51, a second friction member 52, and a pressing mechanism 6. In this embodiment, the friction engagement device 5 further comprises a housing 7.

[0037] The first friction member 51 and the second friction member 52 are arranged to face each other in the axial direction L. In this embodiment, the opposing surfaces of the first friction member 51 and the second friction member 52 are provided with a friction material that does not require oil lubrication. Here, the "friction material that does not require oil lubrication" is, for example, a so-called semi-dry type friction material that is impregnated with oil. In this embodiment, each of the first friction member 51 and the second friction member 52 is formed in a disc shape centered on the axis X. Multiple first friction members 51 and second friction members 52 are provided so as to be arranged alternately in the axial direction L.

[0038] The first friction member 51 is supported by the first rotating member 21 so as to rotate integrally with the first rotating member 21.

[0039] In this embodiment, the first rotating member 21 comprises a first shaft portion 211 and a first support portion 212. The first shaft portion 211 is formed in a cylindrical shape centered on the axis X. The first support portion 212 is configured to support the first friction member 51 so that it cannot rotate relative to the shaft X, but can slide freely in the axial direction L. In this embodiment, the first support portion 212 is formed in a cylindrical shape with a larger diameter than the first shaft portion 211. The first support portion 212 supports the first friction member 51 from the inside in the radial direction R. In this example, a plurality of splines extending in the axial direction L are formed on the outer circumference of the first support portion 212, distributed around the axis X. On the other hand, similar splines are also formed on the inner circumference of the first friction member 51, distributed around the axis X. These splines are engaged with each other.

[0040] The second friction member 52 is supported by the second rotating member 22 so as to rotate integrally with the second rotating member 22.

[0041] In this embodiment, the second rotating member 22 comprises a second shaft portion 221 and a second support portion 222. The second shaft portion 221 is formed in a cylindrical shape with an axis X as its center. The second support portion 222 is configured to support the second friction member 52 so that it cannot rotate relative to the shaft X, but can slide freely in the axial direction L. In this embodiment, the second support portion 222 is formed in a cylindrical shape that covers the first support portion 212 from the outside in the radial direction R. The second support portion 222 supports the second friction member 52 from the outside in the radial direction R. In this example, a plurality of splines extending in the axial direction L are formed on the inner circumference of the second support portion 222, distributed around the axis X. On the other hand, similar splines are also formed on the outer circumference of the second friction member 52, distributed around the axis X. These splines are engaged with each other.

[0042] The pressing mechanism 6 is configured to press the first friction member 51 and the second friction member 52 in the axial direction L. The pressing mechanism 6 comprises the first pressing member 61, the second pressing member 62, the transmission member 63, and the pressing drive device 64. In this embodiment, the pressing mechanism 6 further comprises a support member 60.

[0043] The first pressing member 61 is supported by the non-rotating member NR. The first pressing member 61 is configured to be movable in the axial direction L relative to the non-rotating member NR. In this embodiment, the first pressing member 61 is formed in a cylindrical shape with an axis X as its center. The first pressing member 61 is slidably positioned in the axial direction L within a sliding passage 60a provided in the support member 60. The support member 60 is fixed to the non-rotating member NR. In other words, in this embodiment, the first pressing member 61 is supported by the non-rotating member NR via the support member 60. In this embodiment, the support member 60 is formed in a cylindrical shape with an axis X as its center. The support member 60 is positioned to cover the first shaft portion 211 of the first rotating member 21 from the outside in the radial direction R.

[0044] The second pressing member 62 is supported by a target rotating member T which is either the first rotating member 21 or the second rotating member 22. The second pressing member 62 rotates integrally with the target rotating member T and is configured to be movable in the axial direction L with respect to the target rotating member T. In the present embodiment, the second pressing member 62 is formed in a disc shape centered on the axis X. And the second pressing member 62 is supported by the second support portion 222 of the second rotating member 22 so as not to be relatively rotatable about the axis X and to be slidable in the axial direction L. That is, in the present embodiment, the second rotating member 22 is the target rotating member T. In this example, a plurality of splines that engage with a plurality of splines on the inner peripheral portion of the second support portion 222 are formed dispersed around the axis X on the outer peripheral portion of the second pressing member 62.

[0045] It is preferable that the second pressing member 62 is arranged so as to contact the friction member supported by the rotating member serving as the target rotating member T from the second side L2 in the axial direction. In the present embodiment, the plurality of first friction members 51 and the plurality of second friction members 52 are alternately arranged so that the second friction member 52 supported by the second rotating member 22 is located on the most second side L2 in the axial direction. Therefore, in the present embodiment, the second rotating member 22 is used as the target rotating member T.

[0046] The transmission member 63 is a member that transmits the pressing force in the axial direction L from the first pressing member 61 to the second pressing member 62 while allowing relative rotation between the first pressing member 61 and the second pressing member 62. In the present embodiment, the transmission member 63 is a rolling bearing that supports the load in the axial direction L. And the transmission member 63 includes a rolling element 631, a first raceway ring 632, and a second raceway ring 633.

[0047] The rolling element 631 is rotatably supported by the first raceway ring 632 and the second raceway ring 633. In the present embodiment, the rolling element 631 is formed in a spherical shape.

[0048] The first raceway ring 632 supports the rolling element 631 from the second side L2 in the axial direction. In the present embodiment, the first raceway ring 632 is arranged so as to be pressed from the second side L2 in the axial direction by the first pressing member 61. Also, the first raceway ring 632 is supported by the support member 60 from the second side L2 in the axial direction via a spring 634.

[0049] The spring 634 is provided to bias the transmission member 63 (specifically, the first raceway ring 632) toward the first axial side L1, so as not to form an axial L gap between the second pressing member 62 and the transmission member 63 (specifically, the second raceway ring 633), and an axial L gap between the second pressing member 62 and the first friction member 51 or the second friction member 52 (here, the second friction member 52). Note that a configuration without the spring 634 may also be used. In the present embodiment, the spring 634 is a compression coil spring that expands and contracts in the axial direction L.

[0050] The second raceway ring 633 supports the rolling elements 631 from the first axial side L1. In the present embodiment, the second raceway ring 633 is arranged to contact the second pressing member 62 from the second axial side L2.

[0051] The pressing drive device 64 is a device that presses the first pressing member 61 toward the side of the second pressing member 62 in the axial direction L (here, the first axial side L1) so that the second pressing member 62 presses the first friction member 51 and the second friction member 52 in the axial direction L.

[0052] The housing 7 houses the first friction member 51, the second friction member 52, the first pressing member 61, the second pressing member 62, and the transmission member 63. In the present embodiment, the housing 7 further houses a part of the first shaft portion 211 of the first rotating member 21, the first support portion 212 of the first rotating member 21, a part of the second shaft portion 221 of the second rotating member 22, the second support portion 222 of the second rotating member 22, and the support member 60.

[0053] The housing 7 is configured separately from the case 9. The housing 7 is fixed to the case 9. In the present embodiment, the housing 7 is detachably fixed to the case 9 from the first axial side L1 by bolt fastening. In the present embodiment, the housing 7 is a non-rotating member NR.

[0054] As shown in FIG. 3, in the present embodiment, the pressing drive device 64 includes an oil reservoir 65, an oil pump 66, a hydraulic circuit 67, and a control valve 68. In the present embodiment, the oil reservoir 65, the oil pump 66, the hydraulic circuit 67, and the control valve 68 are arranged outside the housing 7.

[0055] The oil storage section 65 is configured to store oil. The oil storage section 65 is configured to be able to change its volume.

[0056] The oil pump 66 is a pump that generates hydraulic pressure by drawing oil from the oil reservoir 65. In this embodiment, the oil pump 66 is an electrically powered pump driven by an electric motor.

[0057] The hydraulic circuit 67 is configured to transmit hydraulic pressure generated by the oil pump 66 to the first pressing member 61. In this embodiment, the hydraulic circuit 67 is connected to an oil passage 60b provided in the support member 60 via a hydraulic pipe 67a (see Figure 2). The oil passage 60b communicates with the sliding passage 60a from the axial second side L2. The hydraulic pipe 67a is arranged to communicate the inside and outside of the housing 7. With this configuration, the pressing drive device 64 can be placed outside the housing 7, thereby increasing the degree of freedom in the placement of the pressing drive device 64.

[0058] The control valve 68 is a valve for controlling the hydraulic pressure of the hydraulic circuit 67. In this embodiment, the control valve 68 includes at least a first solenoid valve capable of maintaining hydraulic pressure and a second solenoid valve capable of reducing hydraulic pressure. The control valve 68 may further include a third solenoid valve capable of pressurizing hydraulic pressure.

[0059] The oil reservoir 65, oil pump 66, hydraulic circuit 67, and control valve 68 constitute a closed circuit. It is preferable that the hydraulic circuit 67 is equipped with a check valve, reservoir tank, etc.

[0060] 2. In the second embodiment and subsequent embodiments, the differential gear 100 according to the second embodiment will be described with reference to Figure 4. This embodiment differs from the first embodiment in that, in addition to the first friction engagement device 5A as the friction engagement device 5, it is equipped with a second friction engagement device 5B. The following description will focus on the differences from the first embodiment. Points that are not specifically described are the same as in the first embodiment.

[0061] As shown in Figure 4, in this embodiment, the second output shaft 3 comprises a third rotating member 31 and a fourth rotating member 32. The third rotating member 31 and the fourth rotating member 32 are arranged coaxially so as to be able to rotate relative to each other. The third rotating member 31 is connected to rotate integrally with the second side gear 44. The fourth rotating member 32 is driven and connected to the wheel W.

[0062] The second friction engagement device 5B is a friction-type engagement device that engages and disengages the third rotating member 31 and the fourth rotating member 32 of the second output shaft 3. In this embodiment, the second friction engagement device 5B includes a second housing 7B configured similarly to the first housing 7A, which serves as the housing 7 of the first friction engagement device 5A. The second housing 7B is configured to be symmetrical with respect to the first housing 7A with respect to a virtual plane perpendicular to the axis X. The second housing 7B is detachably fixed to the case 9 from the axial second side L2 by bolt fastening. Since the second friction engagement device 5B is configured similarly to the first friction engagement device 5A, a detailed explanation of the other configurations is omitted.

[0063] Thus, in this embodiment, the first friction engagement device 5A engages and disengages the first rotating member 21 and the second rotating member 22 of the first output shaft 2, and the second friction engagement device 5B engages and disengages the third rotating member 31 and the fourth rotating member 32 of the second output shaft 3. With this configuration, the torque transmitted to the pair of wheels W can be controlled independently by controlling the engagement force of the first friction engagement device 5A and the second friction engagement device 5B. Therefore, the differential gear 100 can be given the function of a torque vectoring mechanism.

[0064] 3. Other Embodiments (1) In the above embodiment, a configuration in which the first rotating member 21 of the first output shaft 2 is connected to the first side gear 43 so as to rotate integrally was described as an example. However, the invention is not limited to such a configuration, and the first rotating member 21 of the first output shaft 2 may be connected to the second side gear 44 so as to rotate integrally. In this configuration, it is preferable that the housing 7 is fixed to the case 9 from the axial second side L2.

[0065] (2) In the above embodiment, a configuration in which the second rotating member 22 is the target rotating member T was described as an example. However, the configuration is not limited to such a configuration, and the first rotating member 21 may be the target rotating member T. In this configuration, it is preferable that a plurality of first friction members 51 and a plurality of second friction members 52 are arranged alternately such that the first friction member 51 is located furthest to the second axial side L2, and the second pressing member 62 contacts the first friction member 51 from the second axial side L2.

[0066] (3) In the above embodiment, a configuration in which the differential gear mechanism 4 is a bevel gear type differential gear mechanism was described as an example. However, the configuration is not limited to such a configuration, and for example, the differential gear mechanism 4 may be a planetary gear type differential gear mechanism equipped with a sun gear, a carrier, and a ring gear.

[0067] (4) In the above embodiment, a configuration in which the housing 7 as a non-rotating member NR is fixed to the case 9 was described as an example. However, the configuration is not limited to such a configuration, and for example, the housing 7 may be integrally formed with the case 9.

[0068] (5) In the above embodiment, a configuration in which the pressing drive device 64 moves the first pressing member 61 in the axial direction L by hydraulic pressure was described as an example. However, the configuration is not limited to such a configuration, and for example, the pressing drive device 64 may include an electric motor and a linear motion conversion mechanism that converts the rotation of the electric motor into axial motion L of the first pressing member 61. Alternatively, the pressing drive device 64 may be configured to move the first pressing member 61 in the axial direction L by an electromagnetic actuator.

[0069] (6) In the above embodiment, a configuration in which the housing 7 is detachably fixed to the case 9 by bolt fastening was described as an example. However, the configuration is not limited to such a configuration, and for example, the housing 7 may be fixed to the case 9 by welding.

[0070] (7) In the above embodiment, the first rotating member 21 of the first output shaft 2 comprises a first shaft portion 211 and a first support portion 212 that supports the first friction member 51, and the second rotating member 22 of the first output shaft 2 comprises a second shaft portion 221 and a second support portion 222 that supports the second friction member 52. However, the configuration is not limited to such a configuration, and for example, the second rotating member 22 may not have a second shaft portion 221, and the second support portion 222 may be driven and connected to the wheel W via another shaft. Alternatively, the second shaft portion 221 may be driven and connected to the wheel W via another shaft. In other words, the first output shaft 2 only needs to be configured to support at least the first friction member 51 and the second friction member 52 of the friction engagement device 5.

[0071] (8) The configurations disclosed in each of the embodiments described above can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. With regard to other configurations, the embodiments disclosed herein are merely illustrative in all respects. Therefore, various modifications can be made as appropriate, without departing from the spirit of this disclosure.

[0072] 4. Summary of this embodiment Below, we will describe the outline of the differential (100) and vehicle drive system (D) described above.

[0073] The differential gear (100) comprises an input member (1) to which a driving force is input, an output shaft (2), and a differential gear mechanism (4) that distributes the driving force input to the input member (1) to the output shaft (2) and a shaft (3) different from the output shaft (2), further comprising a friction engagement device (5) that engages and disengages a first rotating member (21) and a second rotating member (22) constituting the output shaft (2), wherein the direction along the rotation axis (X) of the output shaft (2) is the axial direction (L), and the friction engagement device (5) comprises a first friction member (51) and a second friction member (52) facing each other in the axial direction (L), and a pressing mechanism (6) that presses the first friction member (51) and the second friction member (52) in the axial direction (L). The first rotating member (21) and the second rotating member (22) are arranged coaxially so as to be able to rotate relative to each other, the first friction member (51) is supported by the first rotating member (21) so as to rotate integrally with the first rotating member (21), the second friction member (52) is supported by the second rotating member (22) so as to rotate integrally with the second rotating member (22), the pressing mechanism (6) includes a first pressing member (61) supported by a non-rotating member (NR) and movable in the axial direction (L) relative to the non-rotating member (NR), and a second pressing member (62) supported by a target rotating member (T) which is either the first rotating member (21) or the second rotating member (22), rotates integrally with the target rotating member (T) and is movable in the axial direction (L) relative to the target rotating member (T), The device includes a transmission member (63) that transmits an axial (L) pressing force from the first pressing member (61) to the second pressing member (62) while allowing relative rotation between the first pressing member (61) and the second pressing member (62), and a pressing drive device (64) that presses the first pressing member (61) toward the second pressing member (62) in the axial (L) direction so that the second pressing member (62) presses the first friction member (51) and the second friction member (52) in the axial (L) direction.

[0074] With this configuration, for example, compared to a configuration with a meshing type engagement device, the engagement of the first rotating member (21) and the second rotating member (22) can be performed without considering the meshing phase. This allows the engagement operation of the friction engagement device (5) to be performed quickly. Furthermore, even when torque is being transmitted between the first rotating member (21) and the second rotating member (22), they can be disengaged. This allows the disengage operation of the friction engagement device (5) to be performed quickly. In addition, the friction engagement device (5) can be given a function to block unintended torque transmission. Moreover, with this configuration, the pressing mechanism (6) includes a first pressing member (61) supported by a non-rotating member (NR), and the first pressing member (61) is pressed by a pressing drive device (64). This allows the pressing drive device (64) to be supported on the side of the non-rotating member (NR). Therefore, it is easier to improve the mountability when mounting the differential (100) on a vehicle.

[0075] Here, the differential gear mechanism (4) is further housed in a case (9), and the friction engagement device (5) further comprises a housing (7) that houses the first friction member (51), the second friction member (52), the first pressing member (61), the second pressing member (62), and the transmission member (63), wherein the housing (7) is constructed separately from the case (9) and is preferably fixed to the case (9).

[0076] With this configuration, most of the friction engagement device (5) can be made into an assembly including the housing (7). Therefore, a differential gear mechanism (4) common to both a differential gear (100) equipped with a friction engagement device (5) and a differential gear (100) without a friction engagement device (5) can be used, while a differential gear (100) equipped with a friction engagement device (5) can be easily realized as needed.

[0077] Furthermore, it is preferable that the opposing surfaces of the first friction member (51) and the second friction member (52) are provided with a friction material that does not require oil lubrication.

[0078] With this configuration, there is no need to supply oil to the opposing surfaces of the first friction member (51) and the second friction member (52), so there is no need to consider the oil supply path, and the degree of freedom in arranging the friction engagement device (5) is increased. In addition, it is easier to minimize the loss of driving force due to drag between the first friction member (51) and the second friction member (52) caused by oil around the first friction member (51) and the second friction member (52).

[0079] Furthermore, the pressing drive device (64) comprises an oil reservoir (65) for storing oil, an oil pump (66) for drawing oil from the oil reservoir (65) to generate hydraulic pressure, a hydraulic circuit (67) for transmitting the hydraulic pressure generated by the oil pump (66) to the first pressing member (61), and a control valve (68) for controlling the hydraulic pressure of the hydraulic circuit (67). Preferably, the oil reservoir (65) is configured to be able to change volume, and the oil reservoir (65), the oil pump (66), the hydraulic circuit (67), and the control valve (68) constitute a closed circuit.

[0080] This configuration makes it easier to improve the responsiveness of the friction engagement device (5) in engaging and disengaging.

[0081] The vehicle drive system (D) comprises the differential gear (100) described above, and a rotating electric machine (MG) that outputs the driving force input to the input member (1) and functions as a driving force source for the wheels (W), wherein the axial (L) arrangement region of the rotating electric machine (MG) and the axial (L) arrangement region of the friction engagement device (5) overlap with each other.

[0082] In this configuration, since the output shaft (2) is composed of a first rotating member (21) and a second rotating member (22) arranged coaxially, the axial dimension (L) of the output shaft (2) tends to be large. However, since the axial (L) arrangement area of ​​the friction engagement device (5) that engages and disengages the first rotating member (21) and the second rotating member (22) overlaps with the axial (L) arrangement area of ​​the rotating electric machine (MG), the axial (L) dimension of the vehicle drive unit (D) as a whole can be kept small.

[0083] A friction engagement device (5) is provided on the first output shaft (2) of a differential gear mechanism (4) that distributes the driving force input to an input member (1) to a first output shaft (2) and a second output shaft (3) different from the first output shaft (2), and engages and disengages a first rotating member (21) and a second rotating member (22) that constitute the first output shaft (2), comprising: a first friction member (51) and a second friction member (52) facing each other in the axial direction (L) along the rotation axis (X) of the first output shaft (2); and a pressing mechanism (6) that presses the first friction member (51) and the second friction member (52) in the axial direction (L), wherein the first rotating member (21) and the second rotating member (22) are arranged coaxially in a state in which they can rotate relative to each other. The first friction member (51) is supported on the first rotating member (21) so as to rotate integrally with the first rotating member (21), the second friction member (52) is supported on the second rotating member (22) so as to rotate integrally with the second rotating member (22), and the pressing mechanism (6) comprises a first pressing member (61) supported on a non-rotating member (NR) and movable in the axial direction (L) relative to the non-rotating member (NR), and a second pressing member (62) supported on a target rotating member (T), which is either the first rotating member (21) or the second rotating member (22), and rotating integrally with the target rotating member (T) and movable in the axial direction (L) relative to the target rotating member (T), The device includes a transmission member (63) that transmits an axial (L) pressing force from the first pressing member (61) to the second pressing member (62) while allowing relative rotation between the first pressing member (61) and the second pressing member (62), and a pressing drive device (64) that presses the first pressing member (61) toward the second pressing member (62) in the axial (L) direction so that the second pressing member (62) presses the first friction member (51) and the second friction member (52) in the axial (L) direction.

[0084] With this configuration, for example, compared to a meshing type engagement device, the engagement of the first rotating member (21) and the second rotating member (22) can be performed without considering the meshing phase. This allows the engagement operation of the friction engagement device (5) to be performed quickly. Furthermore, even when torque is being transmitted between the first rotating member (21) and the second rotating member (22), they can be disengaged. This allows the disengagement operation of the friction engagement device (5) to be performed quickly. In addition, the friction engagement device (5) can be given a function to block unintended torque transmission. Moreover, with this configuration, the pressing mechanism (6) includes a first pressing member (61) supported by a non-rotating member (NR), and the first pressing member (61) is pressed by a pressing drive device (64). This allows the pressing drive device (64) to be supported on the side of the non-rotating member (NR). Therefore, it is easier to mount the friction engagement device (5) when it is mounted on a vehicle.

[0085] The technology disclosed herein can be used in a differential gear comprising an input member to which a driving force is input, a first output shaft, a second output shaft, and a differential gear mechanism that distributes the driving force input to the input member to the first output shaft and the second output shaft.

[0086] 100: Differential gear, 1: Input member, 2: First output shaft (output shaft), 21: First rotating member, 22: Second rotating member, 3: Second output shaft (shaft), 4: Differential gear mechanism, 5: Friction engagement device, 51: First friction member, 52: Second friction member, 6: Pressing mechanism, 61: First pressing member, 62: Second pressing member, 63: Transmission member, 64: Pressing drive device, 65: Oil reservoir, 66: Oil pump, 67: Hydraulic circuit, 68: Control valve, 7: Housing, 9: Case, D: Vehicle drive device, MG: Rotating electric machine, NR: Non-rotating member, T: Target rotating member, L: Axial direction

Claims

1. A differential gear comprising: an input member to which a driving force is input; an output shaft; and a differential gear mechanism for distributing the driving force input to the input member to the output shaft and an axis different from the output shaft, further comprising a friction engagement device for engaging and disengaging a first rotating member and a second rotating member constituting the output shaft, wherein the direction along the rotation axis of the output shaft is defined as the axial direction, the friction engagement device comprises a first friction member and a second friction member facing each other in the axial direction, and a pressing mechanism for pressing the first friction member and the second friction member in the axial direction, wherein the first rotating member and the second rotating member are arranged coaxially so as to be able to rotate relative to each other, the first friction member is supported by the first rotating member so as to rotate integrally with the first rotating member, the second friction member is supported by the second rotating member so as to rotate integrally with the second rotating member, and the pressing mechanism comprises a first pressing member supported by a non-rotating member and movable in the axial direction relative to the non-rotating member, A differential device comprising: a second pressing member supported by a target rotating member which is either the first rotating member or the second rotating member, and which rotates integrally with the target rotating member and is movable in the axial direction relative to the target rotating member; a transmission member that transmits the axial pressing force from the first pressing member to the second pressing member while allowing relative rotation between the first pressing member and the second pressing member; and a pressing drive device that presses the first pressing member toward the second pressing member in the axial direction so that the second pressing member presses the first friction member and the second friction member in the axial direction.

2. The differential gear according to claim 1, further comprising a case for housing the differential gear mechanism, wherein the friction engagement device further comprises a housing for housing the first friction member, the second friction member, the first pressing member, the second pressing member, and the transmission member, the housing being constructed separately from the case and fixed to the case.

3. The differential according to claim 1 or 2, wherein the opposing surfaces of the first friction member and the second friction member are provided with a friction material that does not require oil lubrication.

4. The differential device according to claim 1 or 2, wherein the pressing drive device comprises an oil reservoir for storing oil, an oil pump for drawing oil from the oil reservoir to generate hydraulic pressure, a hydraulic circuit for transmitting the hydraulic pressure generated by the oil pump to the first pressing member, and a control valve for controlling the hydraulic pressure of the hydraulic circuit, wherein the oil reservoir is configured to be able to change volume, and the oil reservoir, the oil pump, the hydraulic circuit, and the control valve constitute a closed circuit.

5. A vehicle drive system comprising a differential gear according to claim 1 or 2, and a rotating electric machine that outputs a driving force input to the input member and functions as a driving force source for the wheels, wherein the axial arrangement region of the rotating electric machine and the axial arrangement region of the friction engagement device overlap each other.

6. A friction engagement device provided on the first output shaft of a differential gear mechanism that distributes a driving force input to an input member to a first output shaft and a second output shaft different from the first output shaft, for engaging and disengaging a first rotating member and a second rotating member constituting the first output shaft, comprising: a first friction member and a second friction member facing each other in the axial direction, with the direction along the rotation axis of the first output shaft as the axial direction; and a pressing mechanism for pressing the first friction member and the second friction member in the axial direction, wherein the first rotating member and the second rotating member are arranged coaxially in a state in which they can rotate relative to each other; the first friction member is supported by the first rotating member so as to rotate integrally with the first rotating member; the second friction member is supported by the second rotating member so as to rotate integrally with the second rotating member; and the pressing mechanism comprises a first pressing member supported by a non-rotating member and movable in the axial direction relative to the non-rotating member, A friction engagement device comprising: a second pressing member supported by a target rotating member which is either the first rotating member or the second rotating member, and which rotates integrally with the target rotating member and is movable in the axial direction relative to the target rotating member; a transmission member that transmits the axial pressing force from the first pressing member to the second pressing member while allowing relative rotation between the first pressing member and the second pressing member; and a pressing drive device that presses the first pressing member toward the second pressing member in the axial direction so that the second pressing member presses the first friction member and the second friction member in the axial direction.

Images