Drive unit

Abstract

To provide a vehicle drive for transmitting driving force from a driving source, the vehicle drive capable of suppressing an increase in arrangement space and achieving the weight reduction.SOLUTION: A vehicle drive 1 transmits the rotation of an assist motor 2 to an axle 6 of a drive wheel through a deceleration gear 4 and a differential gear 5. On the input route of the rotation of the assist motor 2 from the deceleration gear 4 to the differential gear 5, a two-way clutch 38 is provided that can transmit the rotation of the assist motor 2 in a first direction and the rotation of it in a second direction to the differential gear 5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drive device for a vehicle, for transmitting driving force from a drive source. [Background technology]

[0002] In recent years, a wide variety of drive devices that transmit the driving force of electric motors have been developed for driving devices for vehicles such as automobiles. Patent Document 1 describes a drive device that uses an electric motor as a drive source and that aims to reduce energy loss when used in a vehicle or the like during reverse driving or during deceleration regenerative driving in which the electric motor regenerates. The drive device in Patent Document 1 is attached to the axle of the driving wheels, and is structured using a two-way clutch instead of the conventional structure using a switching gear, thereby preventing the device from becoming larger and reducing its weight. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-1401 A Summary of the Invention [Problem to be solved by the invention]

[0004] The two-way clutch used in the drive unit described in Patent Document 1 has two one-way clutches arranged side by side in the axial direction, and the locking direction of these one-way clutches is switched by operating a selector plate, so an external device such as an actuator for operating the selector plate is required. Therefore, the drive unit described in Patent Document 1 may increase the weight of the entire unit and the installation space in the vehicle. This may make it difficult to achieve the recent strict requirements for weight reduction and space saving.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and has an objective of providing a drive device for a vehicle for transmitting driving force from a drive source, which can suppress an increase in installation space and achieve weight reduction. [Means for solving the problem]

[0006] In order to solve the above problems, the driving device of the present invention comprises: A drive device for a vehicle that transmits rotation of a drive shaft of a drive source to an axle of a drive wheel via a reduction mechanism and a differential gear device, a two-way clutch capable of transmitting rotation of the drive shaft in a first direction and rotation of the drive shaft in a second direction to the differential gear device is provided on an input path of rotation of the drive shaft from the reduction mechanism to the differential gear device; The differential gear device includes a differential case that is rotatably provided around the axle and that houses a gear mechanism connected to the axle, The rotation of the drive shaft is transmitted from the reduction mechanism to the differential case via a connecting gear arranged coaxially with the axle and connected to the reduction mechanism, The two-way clutch includes a first annular member that rotates integrally with the connecting gear and is arranged to be rotatable relative to the differential case, a second annular member that is arranged coaxially with the first annular member and rotatable relative to the first annular member and rotates integrally with the differential case, and a ratchet mechanism that can engage the first annular member and the second annular member to transmit torque. The ratchet mechanism includes a tooth portion provided on the first annular member; a plurality of first claw members provided on the second annular member and meshing with the teeth to lock the relative rotation of the first annular member with respect to the second annular member in a first rotation direction and allow the relative rotation in a second rotation direction; a plurality of second claw members provided on the second annular member, each paired with the first claw member, and meshing with the tooth portion to lock the relative rotation of the first annular member with respect to the second annular member in the second rotation direction and allow the relative rotation in the first rotation direction; Each of the first claw members rotates due to centrifugal force acting due to rotation of the second annular member, and when the centrifugal force exceeds a predetermined magnitude, the first claw members are disengaged from the tooth portion. the law of nature, Each of the second claw members maintains a state of meshing with the tooth portion even when a centrifugal force exceeding the predetermined magnitude acts on the second claw members. It is characterized by the above. Effect of the Invention

[0007] According to the present invention, it is possible to provide a drive device for a vehicle for transmitting driving force from a drive source, which can suppress an increase in installation space and achieve weight reduction. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a skeleton diagram showing the configuration of a drive device according to an embodiment. [Diagram 2] FIG. 2 is an enlarged cross-sectional view taken along the axial direction of the differential gear portion. [Diagram 3] FIG. 3 is a front view of the two-way clutch as viewed from one axial side, showing a state in which both directions of rotation of the inner ring relative to the outer ring are locked. [Figure 4] FIG. 4 is a front view of the two-way clutch as viewed from one axial side, showing a state in which one direction of rotation of the inner ring relative to the outer ring is locked. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A drive device according to an embodiment of the present invention will now be described with reference to the drawings. The drive unit according to this embodiment is a type mounted on a vehicle, and transmits driving force from an electric motor as a drive source to the axles of the drive wheels via a differential gear to drive the drive wheels. The electric motor in this embodiment is an assist motor for assisting the main power of an engine or the like.

[0010] First, the directions related to the drive device according to the embodiment are defined. In the embodiment, the axial direction refers to the axial direction of the axle of the drive wheel, and the axial, radial, and circumferential directions refer to the axial, radial, and circumferential directions of the axle of the drive wheel. Regarding the axial direction, in Figs. 1 and 2, the left side of the paper is one axial side, and the right side of the paper is the other axial side, and in Figs. 3 and 4, the front side of the paper is one axial side, and the back side of the paper is the other axial side. Regarding the circumferential direction, in Figs. 3 and 4, the direction rotating clockwise toward the paper is one circumferential direction, and the direction rotating counterclockwise toward the paper is the other circumferential direction.

[0011] FIG. 1 is a skeleton diagram showing the configuration of a drive device according to this embodiment. The drive device 1 of this embodiment includes a drive source section 3 including an assist motor 2 which is a drive source, a reduction gear section 4 which reduces the rotation of the assist motor 2, and a wheel drive section 8 which transmits the driving force of the assist motor 2 transmitted from the reduction gear section 4 to an axle 6 via a differential gear section 5, and drives wheels 7L, 7R which are drive wheels connected to both ends of the axle 6. 1 shows a schematic diagram of a state in which the drive unit 1 of this embodiment is mounted on a vehicle (not shown). Therefore, the axial direction in Figs. 1 and 2 is the vehicle width direction, one axial side is the left side in the vehicle width direction, and the other axial side is the right side in the vehicle width direction.

[0012] The first shaft 9, which is the drive shaft of the assist motor 2, is disposed parallel to the axle 6 of the wheel drive unit 8. In other words, the first shaft 9 is disposed along the vehicle width direction. A first connecting gear 10 is provided on the first shaft 9 for transmitting the drive force of the assist motor 2, i.e., the rotation of the assist motor 2, to the reduction gear unit 4. The first connecting gear 10 is provided integrally with the first shaft 9.

[0013] The reduction gear unit 4 includes a second shaft 11 arranged in parallel with the first shaft 9. The second shaft 11 includes a second connection gear 12 that meshes with the first connection gear 10 of the first shaft 9. The second connection gear 12 is integral with the second shaft 11 and has a larger diameter than the first connection gear 10 of the first shaft 9. Therefore, the rotation of the assist motor 2 is reduced in speed and transmitted to the second shaft 11 via the first connection gear 10 and the second connection gear 12. The second shaft 11 is further provided with a third connection gear 14. The third connection gear 14 is integral with the second shaft 11. The second connection gear 12 and the third connection gear 14 are arranged in this order in the axial direction from one axial side to the other axial side. The diameter of the third connection gear 14 is smaller than the diameter of the second connection gear 12.

[0014] The wheel drive unit 8 includes a fourth connection gear 16 that meshes with the third connection gear 14 of the second shaft 11 and is connected to the differential gear unit 5. The fourth connection gear 16 is disposed coaxially with the axle 6 and has a larger diameter than the third connection gear 14. The rotation of the assist motor 2 transmitted to the second shaft 11 is reduced in speed and transmitted to the differential gear unit 5 via the third connection gear 14 and the fourth connection gear 16. The detailed configurations of the fourth connection gear 16 and the differential gear unit 5 will be described later.

[0015] The axle 6 is made up of a first axle 6L, the left wheel 7L of which is connected to one axial end, and a second axle 6R, the right wheel 7R of which is connected to the other axial end. The driving force of the assist motor 2 is transmitted to each of the first axle 6L and the second axle 6R via a differential gear unit 5. This drives the left and right wheels 7L and 7R.

[0016] FIG. 2 is an enlarged cross-sectional view of the differential gear portion 5 taken along the axial direction. The differential gear unit 5 includes a differential case 22 that accommodates the differential gear mechanism 18 in an internal space 20. The differential case 22 includes a cylindrical portion 24 extending in the axial direction, an annular member 64 that covers one axial end of the cylindrical portion 24, and a bottom portion 28 that covers the other axial end of the cylindrical portion 24. The cylindrical portion 24 is arranged coaxially with the axle 6. The annular member 64 has a predetermined axial thickness and is fixed to one axial end face of the cylindrical portion 24 by a plurality of fixing bolts 66. The annular member 64 is arranged coaxially with the cylindrical portion 24 and has a larger outer diameter than the cylindrical portion 24. The bottom portion 28 is formed in a truncated cone shape that bulges toward the other axial direction. The bottom portion 28 is formed integrally with the cylindrical portion 24. The internal space 20 is formed by the cylindrical portion 24, the annular member 64, and the bottom portion 28. The differential case 22 is provided so as to be rotatable about the axle 6.

[0017] The annular member 64 of the differential case 22 has a first through hole 30 in the center and a first cylindrical portion 32 protruding from the edge of the first through hole 30 in one axial direction. The first axle 6L is disposed through the inner periphery of the first through hole 30 and the first cylindrical portion 32. The inner periphery of the first through hole 30 and the first cylindrical portion 32 and the outer periphery of the first axle 6L face each other with a gap in the radial direction. That is, the inner periphery of the first through hole 30 and the first cylindrical portion 32 are not in contact with the outer periphery of the first axle 6L.

[0018] The bottom 28 of the differential case 22 is provided with a second through hole 34 in the center, and a second cylindrical portion 36 protruding from the edge of the second through hole 34 toward the other axial direction. The second axle 6R is disposed through the inner periphery of the second through hole 34 and the second cylindrical portion 36. The inner periphery of the second through hole 34 and the second cylindrical portion 36 and the outer periphery of the second axle 6R face each other with a gap in the radial direction. That is, the inner periphery of the second through hole 34 and the second cylindrical portion 36 are not in contact with the outer periphery of the second axle 6R.

[0019] The differential gear mechanism 18 has the same configuration as a known differential gear mechanism, so detailed description and illustration are omitted, but for example, it has the following configuration. That is, in the internal space 20 of the differential case 22, a pinion shaft (not shown) that extends in a direction perpendicular to the axle 6 and is fixed to the differential case 22 and rotates integrally with the differential case 22, a pair of pinions (not shown) each rotatably provided on the pinion shaft, a side gear (not shown) provided at the other axial end of the first axle 6L and meshing with the pair of pinions (not shown), and a side gear (not shown) provided at one axial end of the second axle 6R and meshing with the pair of pinions. Such a differential gear mechanism 18 absorbs the rotation difference between the left and right wheels 7L and 7R when the vehicle turns, for example.

[0020] In the drive device 1 of this embodiment, a two-way clutch 38 is provided on an input path of the driving force of the assist motor 2 from the fourth connecting gear 16 to the differential gear unit 5. Specifically, the two-way clutch 38 is provided in the differential gear unit 5. The configuration of the wheel drive unit 8 including the two-way clutch 38 will be described in detail below.

[0021] As shown in FIG. 2, a flange portion 40 is formed on the outer peripheral surface of the cylindrical portion 24 of the differential case 22, extending radially outward from the other axial end. The flange portion 40 is formed coaxially with the axle 6. The flange portion 40 has bolt holes 42 penetrating in the axial direction formed at predetermined intervals in the circumferential direction. An annular clutch fixing portion 44 is fixed to one axial side of the flange portion 40. The clutch fixing portion 44 is composed of an annular portion 46 axially facing the flange portion 40 and a cylindrical portion 48 extending from the outer diameter side edge of the annular portion 46 toward one axial side. The annular portion 46 and the cylindrical portion 48 are arranged coaxially with the axle 6. The annular portion 46 has a predetermined thickness in the axial direction. The annular portion 46 has bolt holes 50 penetrating in the axial direction formed at predetermined intervals in the circumferential direction in correspondence with the bolt holes 42 of the flange portion 40. The clutch fixing portion 44 is fixed to the flange portion 40 of the differential case 22 by a fixing bolt 52 that screws into the bolt hole 42 of the flange portion 40 and the bolt hole 50 of the annular portion 46, with the other axial side surface of the annular portion 46 in contact with the one axial side surface of the flange portion 40.

[0022] The cylindrical portion 48 of the clutch fixing portion 44 extends to the vicinity of an axial position corresponding to one axial end face of the cylindrical portion 24 of the differential case 22. In detail, the one axial end face of the cylindrical portion 48 of the clutch fixing portion 44 is located on the other axial side of the one axial end face of the cylindrical portion 24 of the differential case 22. An annular space 54 that is open to one axial side and coaxial with the axle 6 is formed by the one axial side surface of the annular portion 46 of the clutch fixing portion 44, the inner peripheral surface of the cylindrical portion 48 of the clutch fixing portion 44, and the outer peripheral surface of the cylindrical portion 24 of the differential case 22. The two-way clutch 38 is provided in the annular space 54.

[0023] Fig. 3 is a front view of the two-way clutch 38 seen from one axial side, showing a state in which both directions of rotation of the inner ring 56 relative to the outer ring 55 are locked. Also, Fig. 4 is a front view of the two-way clutch 38 seen from one axial side, showing a state in which one direction of rotation of the inner ring 56 relative to the outer ring 55 is locked. 3 and 4, the two-way clutch 38 provided in the drive unit 1 of this embodiment has an annular inner ring 56, an annular outer ring 55 spaced radially outward from the inner ring 56, coaxial with the inner ring 56 and rotatable relative to the inner ring 56, and a torque transmission mechanism that enables torque transmission between the inner ring 56 and the outer ring 55. The torque transmission mechanism in this embodiment is a ratchet mechanism. The inner ring 56 and the outer ring 55 are arranged coaxially with the axle 6.

[0024] The outer ring 55 is a cylindrical member having a predetermined length in the axial direction, and holds a plurality of claw mechanisms, which will be described later. As shown in FIG. 2, the outer ring 55 is fitted and fixed to the inner circumferential surface of the cylindrical portion 48 of the clutch fixing portion 44. The other axial end face of the outer ring 55 contacts the one axial side face of the annular portion 46 of the clutch fixing portion 44. A circumferential groove 57 is provided in the inner circumferential surface of the cylindrical portion 48 of the clutch fixing portion 44 near the end on the one axial side, and a retaining ring 58 is attached to the circumferential groove 57. The outer diameter side edge of the one axial end face of the outer ring 55 contacts the other axial side face of the retaining ring 58. This prevents the outer ring 55 from slipping out of the annular space 54 in the one axial direction. Since the outer ring 55 is fixed to the clutch fixing portion 44 in this manner, the outer ring 55 and the differential case 22 rotate together.

[0025] The inner ring 56 is a cylindrical member having a predetermined length in the axial direction, and is disposed between the inner peripheral surface of the outer ring 55 and the outer peripheral surface of the cylindrical portion 24 of the differential case 22. The outer peripheral surface of the inner ring 56 and the inner peripheral surface of the outer ring 55 face each other in the radial direction with a predetermined gap therebetween. A rolling bearing 60 is fitted to the outer peripheral surface of the cylindrical portion 24 of the differential case 22, and the inner ring 56 is fitted to the outer peripheral surface of the rolling bearing 60. That is, the inner ring 56 is rotatably fitted to the outer peripheral surface of the cylindrical portion 24 of the differential case 22 via the rolling bearing 60.

[0026] A sliding member 62 is interposed between the end face on the other axial side of the inner ring 56 and the surface on one axial side of the annular portion 46 of the clutch fixing portion 44. This allows the end face on the other axial side of the inner ring 56 to slide smoothly against the surface on one axial side of the annular portion 46 of the clutch fixing portion 44. In addition, with this configuration, it is possible to reduce the meshing impact when the first claw member 15 or the second claw member 17 meshes with the tooth portion 13 of the inner ring 56, as described later. The inner ring 56 has an axial dimension longer than the outer ring 55, and the end face on one axial side of the inner ring 56 is located at an axial position corresponding to the end face on one axial side of the cylindrical portion 24 of the differential case 22.

[0027] The annular member 64 of the differential case 22 has an outer diameter larger than that of the cylindrical portion 24 of the differential case 22, and the outer peripheral edge of the annular member 64 is located radially outward from the outer peripheral surface of the inner ring 56. Therefore, the surface on the other axial side of the annular member 64 and the end surface on one axial side of the inner ring 56 face each other in the axial direction. A sliding member 68 is interposed between the surface on the other axial side of the annular member 64 and the end surface on one axial side of the inner ring 56. As a result, the end surface on one axial side of the inner ring 56 slides smoothly against the surface on the other axial side of the annular member 64, and the inner ring 56 is supported in the axial direction by the annular member 64 and the annular portion 46 of the clutch fixing portion 44. In addition, with this configuration, it is possible to reduce the meshing impact when the first claw member 15 or the second claw member 17 meshes with the tooth portion 13 of the inner ring 56 as described later.

[0028] The fourth connecting gear 16 is connected to the inner ring 56. The fourth connecting gear 16 has a cylindrical main body 70 and an inward flange 72 extending radially inward from one axial end of the main body 70. A plurality of teeth 74 that mesh with the third connecting gear 14 of the second shaft 11 are provided on the outer periphery of the main body 70. Here, the teeth 74 are helical teeth. That is, the fourth connecting gear 16 and the third connecting gear 14 are helical gears. The main body 70 is disposed radially outward of the clutch fixing portion 44 of the differential case 22. The inner circumferential surface of the main body 70 of the fourth connecting gear 16 and the outer circumferential surface of the cylindrical portion 48 of the clutch fixing portion 44 face each other in the radial direction with a small gap therebetween. Alternatively, the inner circumferential surface of the main body 70 and the outer circumferential surface of the cylindrical portion 48 of the clutch fixing portion 44 are configured to slide smoothly.

[0029] The inward flange portion 72 of the fourth connecting gear 16 is disposed on one axial side of the clutch fixing portion 44. The other axial side surface of the inward flange portion 72 faces one axial side end surface of the cylindrical portion 48 of the clutch fixing portion 44 and one axial side end surface of the outer ring 55 of the two-way clutch 38 in the axial direction. The inward flange portion 72 is fitted and fixed to the inner ring 56 of the two-way clutch 38. Specifically, the inner peripheral portion of the inward flange portion 72 is fitted to one axial side end portion of the outer peripheral surface of the inner ring 56 of the two-way clutch 38 so as not to rotate relative to the inner ring 56. As a result, the fourth connecting gear 16 and the inner ring 56 of the two-way clutch 38 rotate together. The inner diameter side edge portion of the surface on one axial side of the inward flange portion 72 faces the outer diameter side edge portion of the surface on the other axial side of the annular member 64 in the axial direction and slides smoothly against the surface on the other axial side of the annular member 64 via the sliding member 68.

[0030] With this configuration, the differential gear unit 5 of this embodiment transmits the rotation of the assist motor 2 transmitted from the third connecting gear 14 to the fourth connecting gear 16 of the second shaft 11, i.e., the driving force of the assist motor 2, to the differential case 22 via the two-way clutch 38. The rotation of the assist motor 2 transmitted to the differential case 22 is transmitted to the axles 6, i.e., the first axle 6L and the second axle 6R, via the differential gear mechanism 18.

[0031] Next, the structure of the two-way clutch 38 will be described. As shown in Figs. 3 and 4, the inner peripheral portion of the outer ring 55 is provided with a first claw member 15 and a second claw member 17 adjacent to one circumferential side of the first claw member 15 and paired with the first claw member 15. The first claw member 15 and the second claw member 17 constitute one claw mechanism. That is, the outer ring 55 is provided with a claw mechanism including the first claw member 15 and the second claw member 17 which are aligned in sequence from the other circumferential side to the one circumferential side as viewed from one axial side. The outer ring 55 is provided with a plurality of such claw mechanisms at predetermined intervals in the circumferential direction.

[0032] A large number of teeth 13 are formed at a predetermined interval around the outer periphery of the inner ring 56. Each tooth 13 protrudes radially outward and extends in the axial direction. The inner circumferential surface of the outer ring 55 and the outer periphery of the inner ring 56, i.e., the teeth 13, face each other in the radial direction with a predetermined space therebetween. The teeth 13 form ratchet teeth with which the first pawl member 15 and the second pawl member 17 mesh. Specifically, a side surface on one circumferential side of each tooth 13 forms a first meshing portion 13a that meshes with the first pawl member 15, and a side surface on the other circumferential side of each tooth 13 forms a second meshing portion 13b that meshes with the second pawl member 17.

[0033] The first claw member 15 is held by a first holding portion 19, which is a recessed portion that opens inward and is provided on the inner peripheral surface of the outer ring 55. The first claw member 15 has a cylindrical portion 21 that extends in the axial direction and a claw portion 23 that extends from the cylindrical portion 21 toward the other circumferential direction. The cylindrical portion 21 of the first claw member 15 is held by the first holding portion 19 so as to be rotatable. That is, the first claw member 15 is held by the first holding portion 19 so that the claw portion 23 can swing radially around the cylindrical portion 21. The first claw member 15 has a rotation center at the cylindrical portion 21, but a center of gravity at the claw portion 23. That is, the claw portion 23 of the first claw member 15 has a mass such that the center of gravity is at the claw portion 23. The claw portion 23 of the first claw member 15 is constantly biased radially inward, that is, in the direction of meshing with the teeth portion 13, by a spring 25 which may be a coil type or of any other type.

[0034] When the claw portions 23 of the first claw members 15 swing radially inward, the claw portions 23 mesh with the first meshing portions 13a of the teeth portion 13 of the inner ring 56, thereby bringing the first claw members 15 into mesh with the teeth portion 13. By meshing with the teeth portion 13, the first claw members 15 lock the clockwise rotation of the inner ring 56 relative to the outer ring 55, i.e., in one circumferential direction. On the other hand, when the inner ring 56 rotates counterclockwise relative to the outer ring 55, i.e., in the other circumferential direction, the claw portions 23 of the first claw members 15 are pushed radially outward by the teeth portion 13 of the inner ring 56 against the biasing force of the spring 25, thereby allowing the rotation of the inner ring 56.

[0035] The second claw member 17 is held by the second holding portion 27, which is a recessed portion that opens inward and is provided on the inner peripheral surface of the outer ring 55. The second claw member 17 has a predetermined circumferential length and is composed of a central portion 29 having a partially cylindrical outer peripheral surface, a claw portion 31 that protrudes from the central portion 29 to one side in the circumferential direction, and a protruding portion 33 that protrudes from the central portion 29 to the other side in the circumferential direction. The second claw member 17 has the central portion 29 rotatably held by the second holding portion 27. That is, the second claw member 17 is held by the second holding portion 27 so that the claw portion 31 can swing radially around the central portion 29. The second claw member 17 is configured so that the center of rotation is the central portion 29 and the center of gravity is also located at the central portion 29. The second holding portion 27 is provided with a relief portion 35 through which the protruding portion 33 of the second claw member 17 can swing radially. The claw portion 31 of the second claw member 17 is constantly biased radially inward, that is, in the direction of meshing with the teeth portion 13 of the inner ring 56, by a spring 37 which may be a coil type or of any other type.

[0036] In this manner, in this embodiment, the pair of first claw member 15 and second claw member 17 have different shapes. Also, the center of gravity and center of rotation of first claw member 15 are in different positions, whereas the center of gravity and center of rotation of second claw member 17 are in the same position.

[0037] When the claw portion 31 of the second claw member 17 swings radially inward, the claw portion 31 meshes with the second meshing portion 13b of the toothed portion 13 of the inner ring 56, thereby meshing the second claw member 17 with the toothed portion 13. By meshing with the toothed portion 13, the second claw member 17 locks the counterclockwise rotation of the inner ring 56 relative to the outer ring 55, i.e., in the other circumferential direction. On the other hand, when the inner ring 56 rotates clockwise relative to the outer ring 55, i.e., in one circumferential direction, the second claw member 17 is pushed radially outward by the toothed portion 13 of the inner ring 56 against the biasing force of the spring 37, allowing the rotation of the inner ring 56.

[0038] In this way, the first and second pawl members 15 and 17 held by the outer ring 55, the springs 25, 37, and the multiple teeth 13 formed on the inner ring 56 form the ratchet mechanism of the two-way clutch 38.

[0039] The two-way clutch 38 of this embodiment is configured so that when the rotational speed of the outer ring 55 exceeds a predetermined speed, the meshing between the first pawl member 15 and the teeth 13 of the inner ring 56 is released. That is, when the rotational speed of the outer ring 55 exceeds a predetermined speed, the first pawl member 15 rotates against the spring 25 by centrifugal force as described below, and the pawl portion 23 is positioned radially outward from the teeth 13. The configuration of the ratchet mechanism of the two-way clutch 38 will be described in further detail below, together with the operation of the first pawl member 15 and the second pawl member 17.

[0040] In the two-way clutch 38 of this embodiment, the first pawl member 15 and the second pawl member 17 operate as follows. When the driving force of the assist motor 2 is transmitted to the outer ring 55 and the outer ring 55 starts to rotate in one circumferential direction or the other circumferential direction, the centrifugal force caused by the rotation of the outer ring 55 acts on the first claw member 15 and the second claw member 17. When the centrifugal force acts, the first claw member 15, whose center of gravity is in the claw portion 23, tends to rotate or swing in a direction in which the claw portion 23 faces radially outward around the cylindrical portion 21. Then, the spring 25 biasing the first claw member 15 is pressed radially outward by the claw portion 23, that is, in a direction of compression. When the rotation speed of the outer ring 55 increases and the centrifugal force acting thereon increases, the spring 25 is compressed by the claw portion 23 of the rotating first claw member 15. When the rotation speed of the outer ring 55 becomes faster than a predetermined rotation speed and the centrifugal force acting on the first claw member 15 becomes greater than a predetermined magnitude F1, the spring 25 is significantly compressed by the claw portion 23, and the claw portion 23 is positioned entirely radially outward from the tooth portion 13. That is, in this state, the first claw member 15 and the tooth portion 13 are in a non-meshing state. The predetermined rotation speed of the outer ring 55 at which a centrifugal force of the predetermined magnitude F1 is generated is defined as R1.

[0041] On the other hand, even if a centrifugal force due to the rotation of the outer ring 55 acts on the second claw member 17, the force that causes the claw portion 31 to swing radially outward is smaller than that of the claw portion 23 of the first claw member 15, because the center of gravity of the second claw member 17 is at the central portion 29. And the spring 37 biasing the second claw member 17 is not significantly compressed even if a centrifugal force larger than a predetermined magnitude F1 acts on the second claw member 17, and the second claw member 17 and the tooth portion 13 maintain their meshed state.

[0042] In this way, the position of the center of gravity of the first claw member 15 and the elastic force of the spring 25 are configured so that when the rotational speed of the outer ring 55 exceeds the predetermined speed R1 and a centrifugal force greater than F1 acts on the first claw member 15, the spring 25 is compressed by the claw portion 23 and the claw portion 23 is displaced radially outward beyond the tooth portion 13. On the other hand, the position of the center of gravity of the second claw member 17 and the elastic force of the spring 37 are configured so that the meshing state between the second claw member 17 and the tooth portion 13 is maintained even if the rotational speed of the outer ring 55 exceeds the predetermined speed R1 and a centrifugal force greater than F1 acts on the second claw member 17.

[0043] The position of the center of gravity of the first claw member 15, the position of the center of gravity of the second claw member 17, the elastic force of the spring 25, the elastic force of the spring 37, the centrifugal force of the predetermined magnitude F1, and the predetermined rotational speed R1 of the outer wheel 55 when the centrifugal force of the predetermined magnitude F1 is generated are appropriately designed taking into consideration the magnitude of the torque to be transmitted, the vehicle speed, etc.

[0044] Next, the operation of the drive device 1 according to this embodiment will be described. First, a case where a vehicle (not shown) equipped with the drive unit 1 according to this embodiment moves forward will be described. When the vehicle moves forward from a stopped state, the assist motor 2 starts to drive, and when the driving force of the assist motor 2, i.e., the rotation of the assist motor 2, is transmitted from the first shaft 9 to the fourth connecting gear 16 of the wheel drive unit 8 via the reduction gear unit 4, the fourth connecting gear 16 rotates counterclockwise in FIG. 3, i.e., in the other circumferential direction. At this time, the inner ring 56 of the two-way clutch 38 rotates integrally with the fourth connecting gear 16 in the other circumferential direction. When the assist motor 2 is stopped and rotating at a low speed, i.e., when the vehicle is stopped and the vehicle speed is in the low speed range, the two-way clutch 38 is in a state in which the first claw member 15 and the second claw member 17 are engaged with the tooth portion 13 by the biasing forces of the springs 25 and 37, respectively, as shown in FIG. 3. That is, the inner ring 56 is locked in both rotation directions relative to the outer ring 55 (hereinafter, the state of the two-way clutch shown in FIG. 3 is referred to as the "first state"). In this state, when the inner wheel 56 rotates in the other circumferential direction, the outer wheel 55 rotates integrally with the inner wheel 56 in the other circumferential direction. Until the rotational speed of the outer wheel 55 reaches R1, the outer wheel 55 rotates integrally with the inner wheel 56, and torque is transmitted from the inner wheel 56 to the outer wheel 55. The driving force of the assist motor 2 transmitted to the outer wheel 55 is transmitted to the first axle 6L and the second axle 6R via the differential gear unit 5, and the vehicle moves forward.

[0045] As the rotation speed of the assist motor 2 increases, the vehicle speed increases. When the vehicle speed reaches a medium or high speed range and the rotation speed of the outer wheel 55 of the two-way clutch 38 exceeds R1, the centrifugal force acting on the first claw member 15 exceeds a predetermined magnitude F1, and the meshing between the first claw member 15 and the toothed portion 13 is released as shown in FIG. 4. On the other hand, the second claw member 17 maintains meshing with the toothed portion 13. That is, the inner wheel 56 is locked only in the other circumferential direction relative to the outer wheel 55 (hereinafter, the state of the two-way clutch 38 shown in FIG. 4 is referred to as the "second state"). In this state, when the rotation speed of the inner wheel 56 on the drive side further increases, torque continues to be transmitted from the inner wheel 56 to the outer wheel 55, and the vehicle accelerates.

[0046] On the other hand, when the rotation speed of the outer wheel 55 is faster than the rotation speed of the inner wheel 56, the outer wheel 55 spins freely relative to the inner wheel 56, and no torque is transmitted from the inner wheel 56 to the outer wheel 55. In other words, when the vehicle is in the medium or high vehicle speed range and the vehicle is inertial running, the two-way clutch 38 blocks the transmission of regenerative force from the outer wheel 55 on the driven side to the assist motor 2. This makes it possible to prevent energy loss due to excessive power generation caused by surplus regenerative force.

[0047] When the vehicle is traveling forward at a medium to high speed range, that is, when the outer ring 55 is rotating in the other circumferential direction, if the assist motor 2 starts to drive from a stop, the inner ring 56 rotates in the other circumferential direction. Here, an axial force acts in the other axial direction on the fourth connecting gear 16 because the fourth connecting gear 16 has helical teeth. Therefore, an axial force also acts on the inner ring 56 in the other axial direction, and the inner ring 56 is pressed against the annular portion 46 of the clutch fixing portion 44, and the respective rotational speeds of the outer ring 55 and the inner ring 56 are synchronized due to friction caused by the sliding member 62. After the rotations of the outer ring 55 and the inner ring 56 are synchronized, the pawl member 29 meshes with the tooth portion 13 of the inner ring 56.

[0048] When the vehicle speed decelerates from the medium or high speed range to the low speed range and the rotational speed of the outer wheel 55 of the driven-side two-way clutch 38 drops to a predetermined rotational speed R1, the centrifugal force acting on the first pawl member 15 decreases to a predetermined magnitude F1, and the first pawl member 15 is again brought into mesh with the teeth portion 13 by the biasing force of the spring 25. That is, the two-way clutch 38 switches to the first state shown in Fig. 3. When the vehicle speed decelerates in this state, regenerative force is input from the outer wheel 55 via the inner wheel 56 to the assist motor 2, and the necessary regenerative power is generated by the assist motor 2.

[0049] Here, the two-way clutch 38 is switched from the first state shown in Fig. 3 to the second state shown in Fig. 4, or from the second state to the first state, by centrifugal force acting on the outer wheel 55. Therefore, the drive unit 1 of this embodiment does not need to be provided with an external device for switching the lock direction of the inner wheel 56 relative to the outer wheel 55 of the two-way clutch 38. Therefore, according to this embodiment, it is possible to realize a drive unit 1 that can suppress an increase in the arrangement space and achieve weight reduction in a drive unit for a vehicle that transmits driving force from a drive source.

[0050] Next, a case where a vehicle (not shown) moves backward will be described. When the vehicle moves backward, the assist motor 2 rotates in the opposite direction to when the vehicle moves forward. Therefore, when the driving force of the assist motor 2, i.e., the rotation of the assist motor 2, is transmitted from the first shaft 9 to the fourth connecting gear 16 of the wheel drive unit 8 via the reduction gear unit 4, the fourth connecting gear 16 rotates in the clockwise direction in FIG. 3, i.e., in one circumferential direction. At this time, the two-way clutch 38 is in the first state shown in FIG. 3. When the inner wheel 56 rotates in one circumferential direction in this state, the outer wheel 55 rotates together with the inner wheel 56 in one circumferential direction, and torque is transmitted from the inner wheel 56 to the outer wheel 55. The driving force of the assist motor 2 transmitted to the outer wheel 55 is transmitted to the first axle 6L and the second axle 6R via the differential gear unit 5, and the vehicle moves backward. When the vehicle moves backward, the speed of the vehicle is within the low speed range, so the two-way clutch 38 is maintained in the first state.

[0051] In this way, according to this embodiment, the engagement and disengagement between the first claw member 15 and the toothed portion 13 can be controlled by the centrifugal force acting on the first claw member 15 of the two-way clutch 38, in other words, by the rotational speed of the outer ring 55 on which the first claw member 15 is provided. Therefore, it is not necessary to provide a separate device for switching between engagement and disengagement between the first claw member 15 and the toothed portion 13. Therefore, according to this embodiment, in a drive device for a vehicle for transmitting driving force from a drive source, it is possible to realize a drive device that can suppress an increase in the arrangement space and achieve weight reduction.

[0052] The drive device 1 of the present invention is not limited to the above embodiment and can be modified. For example, the pawl mechanism of the two-way clutch may be provided on the inner ring side, and teeth that mesh with the pawl mechanism may be provided on the inner peripheral surface of the outer ring, connecting the outer ring and the differential gear unit. The number of pawl mechanisms of the two-way clutch may be changed as appropriate depending on the torque capacity to be transmitted. [Explanation of symbols]

[0053] 1 Drive unit 2 Assist motor 3. Driving unit 4 Reduction gear section 5 Differential gear section 6 axles 7L, 7R wheels 8 Wheel drive unit 13 Teeth 15 First claw member 16 4th connecting gear 17 Second claw member 18 Differential mechanism 22 Differential case 23 Claw 25 Spring 31 Claw part 37 Spring 38 Two-way clutch 44 Clutch fixing part 55 Outer ring 56 Inner Circle

Claims

1. A drive device for a vehicle that transmits rotation of a drive shaft of a drive source to an axle of a drive wheel via a reduction mechanism and a differential gear device, a two-way clutch capable of transmitting rotation of the drive shaft in a first direction and rotation of the drive shaft in a second direction to the differential gear device is provided on an input path of rotation of the drive shaft from the reduction mechanism to the differential gear device, The differential gear device includes a differential case that is rotatably provided around the axle and that houses a gear mechanism connected to the axle, The rotation of the drive shaft is transmitted from the reduction mechanism to the differential case via a connecting gear arranged coaxially with the axle and connected to the reduction mechanism, The two-way clutch includes a first annular member that rotates integrally with the connecting gear and is arranged to be rotatable relative to the differential case, a second annular member that is arranged coaxially with the first annular member and rotatable relative to the first annular member and rotates integrally with the differential case, and a ratchet mechanism that can engage the first annular member and the second annular member to transmit torque. The ratchet mechanism includes a tooth portion provided on the first annular member; a plurality of first claw members provided on the second annular member and meshing with the teeth to lock the relative rotation of the first annular member with respect to the second annular member in a first rotation direction and allow the relative rotation in a second rotation direction; a plurality of second claw members provided on the second annular member, each paired with a first claw member, and meshing with the tooth portion to lock the relative rotation of the first annular member with respect to the second annular member in the second rotation direction and allow the relative rotation in the first rotation direction, Each of the first claw members rotates due to a centrifugal force acting due to the rotation of the second annular member, and when the centrifugal force exceeds a predetermined magnitude, the first claw members are disengaged from the tooth portion, The drive device according to claim 1, wherein each of the second claw members maintains a state of meshing with the tooth portion even when a centrifugal force exceeding the predetermined magnitude is applied thereto.

2. Each of the first claw members is rotatably held by the second annular member, and has a first rotation center portion that is a rotation center of the first claw member, and a first claw portion that is formed integrally with the first rotation center portion and meshes with the tooth portion, 2. The drive device according to claim 1, wherein the first claw member has a center of gravity located on a side of the first claw portion.

3. the first claw member is biased in a direction of meshing with the tooth portion by a first elastic member held by the second annular member, 3. The drive unit according to claim 2, wherein the elastic force of the first elastic member is such that meshing with the teeth portion is released when a centrifugal force exceeding the predetermined magnitude acts on the first elastic member.

4. the second claw member is biased in a direction of meshing with the tooth portion by a second elastic member held by the second annular member, 4. The drive unit according to claim 3, wherein the elastic force of the second elastic member is large enough to maintain meshing with the teeth even when a centrifugal force exceeding the predetermined magnitude acts on the second elastic member.

5. 5. The drive unit according to claim 1, wherein a sliding member is interposed at both axial ends of the first annular member.

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