Differential gear

Abstract

To provide a rolling bearing which supports a case member rotatably relative to an input member even when rotation of the input member is stopped, and to provide a differential gear which easily maintains a good lubrication state of a one-way clutch over the entire periphery.SOLUTION: A differential gear 1 includes: an input member 8; a case member 9; a one-way clutch 10 which transmits torque between the input member 8 and the case member 9 only when the input member 8 rotates relative to the case member 9 in a normal rotation direction; at least one rolling bearing 33a, 33b, 38a, 38b; at least one pinion gear 11; and a pair of side gears 12. An inner ring member 48 forming the one way clutch 10 has a scraping groove 52 in at least one portion in a circumferential direction of a side surface located close to the rolling bearings 33a, 33b, 38a, 38b with respect to an axial direction.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a differential device for distributing the power of a drive source to a pair of wheels.

Background Art

[0002] In a vehicle drive device, the torque of a drive source such as an engine or a drive motor is transmitted to a differential device (differential gear) via a speed reduction mechanism including a transmission and a power transmission mechanism such as a propeller shaft, and is distributed to a pair of wheels by the differential device.

[0003] There is room for improvement in a vehicle drive device as described above in terms of improving fuel efficiency or electricity consumption performance. That is, when the accelerator is turned off during the running of a vehicle equipped with the vehicle drive device and the vehicle tries to coast, losses occur in the meshing portion of the speed reduction mechanism, the drive source, etc., so the coasting distance may be shortened.

[0004] International Publication No. 2022 / 215449 describes a differential device including an input member having a torque input portion to which torque from a power transmission mechanism is input, a case member rotatably supporting a pinion gear and a pair of side gears that mesh with each other, and a one-way clutch disposed between the input member and the case member and transmitting torque between the input member and the case member only when the input member tries to relatively rotate in the forward rotation direction with respect to the case member. Note that the forward rotation direction refers to the rotation direction of the input member with respect to the case member when torque is transmitted from the drive source to the wheels to move the vehicle forward.

[0005] According to the differential device described in International Publication No. 2022 / 215449, when a vehicle in forward travel switches from a non-inertial running state to an inertial running state, that is, when the rotational speed of the input member in the forward rotation direction decreases and becomes slower than the rotational speed of the case member in the forward rotation direction, when the input member rotates relative to the case member in the reverse rotation direction, the one-way clutch switches from the engaged state to the disengaged state, and the case member becomes rotatable relative to the input member. In short, the wheels are disconnected from the power transmission mechanism and the drive source. As a result, the travel distance due to inertial running can be increased, and the fuel consumption performance or electricity consumption performance of the vehicle can be improved.

[0006] Also, International Publication No. 2022 / 215449 describes a structure of a one-way clutch incorporated in a differential device, which includes an outer diameter side engagement surface on the input member side, an inner diameter side engagement surface on the case member side, and an engaging element disposed between the outer diameter side engagement surface and the inner diameter side engagement surface. In such a one-way clutch, when the input member (outer diameter side engagement surface) attempts to rotate relative to the case member (inner diameter side engagement surface) in the forward rotation direction, the engaging element engages with each of the outer diameter side engagement surface and the inner diameter side engagement surface to enter the engaged state, whereas when the input member (outer diameter side engagement surface) attempts to rotate relative to the case member (inner diameter side engagement surface) in the reverse rotation direction, the engagement of the engaging element with each of the outer diameter side engagement surface and the inner diameter side engagement surface is disengaged to enter the disengaged state.

[0007] Also, International Publication No. 2022 / 215449 describes a structure of the one-way clutch having the above structure, which further includes an inner ring member having an inner diameter side engagement surface on its outer peripheral surface, and the inner ring member is externally fitted and fixed to the case member.

[0008] Furthermore, International Publication No. 2022 / 215449 describes a structure including two thrust needle bearings and two radial needle bearings as bearings for rotatably supporting the case member inside the input member in the radial direction.

[0009] The two thrust needle bearings are arranged at portions on both sides of the inner ring member in the axial direction among the portions between the input member and the case member, and the outer diameter of each is smaller than the inner diameter of the inner ring member.

[0010] One of the two radial needle bearings is arranged on one axial side of one of the two thrust needle bearings among the portions between the input member and the case member, and has an outer diameter smaller than the outer diameter of the thrust needle bearing on one axial side.

[0011] The other of the two radial needle bearings is arranged on the other axial side of the other thrust needle bearing among the portions between the input member and the case member, and has an outer diameter smaller than the outer diameter of the thrust needle bearing on the other axial side.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0013] In the conventional differential device described in International Publication No. 2022 / 215449, the lubrication of the one-way clutch, each thrust needle bearing, and each radial needle bearing is performed by lubricating oil supplied to the portion between the input member and the case member. The lubricating oil supplied to the portion between the input member and the case member moves downward due to the action of gravity and accumulates at the lower part of the said portion.

[0014] In a conventional differential device, when the rotation of the input member stops during the coasting of the vehicle, among the outer diameter side engaging surface provided on the inner peripheral surface of the input member, the raceway surface provided on the thrust race supported and fixed to the input member among the thrust needle bearings, and the outer ring raceway of the radial needle bearing, there is a possibility that the portions located above the liquid level of the lubricating oil accumulated in the gap portion cannot be sufficiently lubricated.

[0015] An object of the present disclosure is to provide a differential device that can rotatably support a case member with respect to an input member even when the rotation of the input member stops, and can easily maintain a good lubrication state of a one-way clutch over the entire circumference.

Means for Solving the Problems

[0016] The differential device according to the first aspect of the present disclosure is an input member having a torque input portion, a case member coaxially arranged inside the input member in the radial direction and capable of relative rotation with respect to the input member, an outer diameter side engaging surface formed directly or via another member on the inner peripheral surface of the input member, an inner diameter side engaging surface formed on the outer peripheral surface of the inner ring member coupled and fixed to the case member, and an engaging element disposed between the outer diameter side engaging surface and the inner diameter side engaging surface, and when the input member attempts to rotate relative to the case member in the forward rotation direction, the engaging element meshes with the outer diameter side engaging surface and the inner diameter side engaging surface, and a one-way clutch that transmits torque between the input member and the case member based on this, at least one rolling bearing disposed in a portion axially deviated from the inner ring member among the portions between the input member and the case member and having an outer diameter smaller than the inner diameter of the inner ring member, at least one pinion gear supported by the case member so as to be capable of rotating about an axis orthogonal to the central axis of the case member, Coaxial with the central axis of the input member, a pair of side gears are supported so as to be rotatable relative to the input member and the case member, and mesh with the pinion gear. comprising The inner ring member has a scraping groove at at least one location in the circumferential direction of the side surface closer to the rolling bearing in the axial direction.

[0017] The differential device according to the second aspect of the present disclosure is the differential device according to the first aspect of the present disclosure, The at least one rolling bearing includes a thrust rolling bearing and a radial rolling bearing disposed on the side farther from the inner ring member than the thrust rolling bearing in the axial direction and radially inside the thrust rolling bearing. The thrust rolling bearing has at least one thrust race and a plurality of rolling elements. The at least one thrust race has notches provided at a plurality of locations in the circumferential direction of the outer peripheral surface, a thrust race surface provided on one of the side surfaces on both axial sides and rolling-contact with the rolling surfaces of the plurality of rolling elements, and oil grooves provided at a plurality of locations on the other side surface on both axial sides, which is the side surface facing the inner surface of the input member or the case member, crossing the side surface in the radial direction and having radially outer ends opening into the notches and being in the same phase as the notches in the circumferential direction.

Advantages of the Invention

[0018] According to the differential device of one aspect of the present disclosure, even when the rotation of the input member stops, it is easy to maintain the lubrication state of the rolling bearing that rotatably supports the case member with respect to the input member and the one-way clutch well over the entire circumference.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0020] An example of an embodiment of the present disclosure will be described with reference to FIGS. 1 to 8(b).

[0021] FIG. 1 shows an automotive drive device 2 incorporating the differential device 1 of this example. The automotive drive device 2 increases the output torque of a drive source 3 such as an engine or a drive motor by a power transmission mechanism 4 and then transmits it to the differential device 1, which distributes it to a pair of drive shafts 5 by the differential device 1. Thereby, a pair of wheels 6 connected to the tip ends of the pair of drive shafts 5 are rotationally driven.

[0022] The power transmission mechanism 4 can increase the torque input from the drive source 3 and output it from the output gear 4a that constitutes the torque output portion. Note that the power transmission mechanism 4 can include a transmission or a propeller shaft in an appropriate form such as an automatic transmission (AT), a continuously variable transmission (CVT) such as a belt type or a toroidal type, an automated manual transmission (AMT), a dual clutch transmission (DCT), or a manual transmission (MT).

[0023] In this example, each wheel 6 that constitutes a pair of wheels 6 functions as a drive wheel only when the vehicle is traveling non-inertially in the forward direction in an all-wheel drive (AWD) vehicle. This point will be further described later.

[0024] The differential device 1 of this example includes a housing 7, an input member 8, a case member 9, a one-way clutch 10, at least one pair of rolling bearings 33a, 33b, 38a, 38b, a pinion gear 11, and a pair of side gears 12.

[0025] Regarding the differential device 1, the axial direction, the circumferential direction, and the radial direction refer to the axial direction, the circumferential direction, and the radial direction of the input member 8 unless otherwise specified. The axial direction, the circumferential direction, and the radial direction of the input member 8 coincide with the axial direction, the circumferential direction, and the radial direction of the case member 9, and also coincide with the axial direction, the circumferential direction, and the radial direction of the pair of side gears 12. One side regarding the axial direction refers to the right side in FIGS. 2 to 4(b), and the other side regarding the axial direction refers to the left side in FIGS. 2 to 4(b).

[0026] The housing 7 is supported and fixed to the vehicle body and does not rotate during use.

[0027] The input member 8 has a ring gear 13 that constitutes a torque input portion. The ring gear 13 is provided on the outer peripheral surface of the input member 8 and meshes with an output gear 4a that constitutes a torque output portion of the power transmission mechanism 4. In this example, the input member 8 has a stepped cylindrical shape and includes, in order from one axial side, an input small-diameter cylindrical portion 14a, an input connection portion 15a, an input large-diameter cylindrical portion 16, an input connection portion 15b, and an input small-diameter cylindrical portion 14b.

[0028] The input small-diameter cylindrical portion 14a on one axial side has a cylindrical shape.

[0029] The input connection portion 15a on one axial side has a substantially conical cylindrical shape that is inclined such that the inner diameter and the outer diameter increase from one axial side toward the other axial side, and connects the end portion on the other axial side in the axial direction of the input small-diameter cylindrical portion 14a on one axial side and the end portion on one axial side in the axial direction of the input large-diameter cylindrical portion 16. That is, the end portion on one axial side of the input connection portion 15a is connected to the end portion on the other axial side in the axial direction of the input small-diameter cylindrical portion 14a, and the end portion on the other axial side in the axial direction of the input connection portion 15a is connected to the end portion on one axial side in the axial direction of the input large-diameter cylindrical portion 16.

[0030] The input large-diameter cylindrical portion 16 has a cylindrical shape. A ring gear 13 is provided on the outer peripheral surface of the input large-diameter cylindrical portion 16. In this example, the ring gear 13 is constituted by a helical gear. However, the ring gear 13 can also be constituted by a spur gear or a bevel gear. Alternatively, the torque input portion to which torque from the power transmission mechanism 4 is input can also be constituted by a pulley for passing a belt or a sprocket for passing a chain.

[0031] The input connection portion 15b on the other axial side has a substantially hollow circular plate shape and connects the end portion on the other axial side in the axial direction of the input large-diameter cylindrical portion 16 and the end portion on one axial side in the axial direction of the input small-diameter cylindrical portion 14b on the other axial side. That is, the end portion on the outer side in the radial direction of the input connection portion 15b is connected to the end portion on the other axial side in the axial direction of the input large-diameter cylindrical portion 16, and the end portion on the inner side in the radial direction of the input connection portion 15b is connected to the end portion on one axial side in the axial direction of the input small-diameter cylindrical portion 14b.

[0032] The input small-diameter cylindrical portion 14b on the other side in the axial direction has a cylindrical shape.

[0033] The input member 8 is rotatably supported with respect to the housing 7 by a pair of tapered roller bearings 17a and 17b provided with a face combination (DF) type contact angle. Specifically, a tapered roller bearing 17a on one side in the axial direction is disposed between the outer peripheral surface of the input small-diameter cylindrical portion 14a on one side in the axial direction and the inner peripheral surface of the housing 7, and a tapered roller bearing 17b on the other side in the axial direction is disposed between the outer peripheral surface of the input small-diameter cylindrical portion 14b on the other side in the axial direction and the inner peripheral surface of the housing 7, thereby rotatably supporting the input member 8 inside the housing 7.

[0034] In this example, the input member 8 is formed by coupling and fixing a first element 18 having an input small-diameter cylindrical portion 14a on one side in the axial direction, an input connection portion 15a on one side in the axial direction, and an input large-diameter cylindrical portion 16, and a second element 19 having an input connection portion 15b on the other side in the axial direction and an input small-diameter cylindrical portion 14b on the other side in the axial direction with bolts 20. That is, bolts 20 inserted through through-holes provided at a plurality of circumferential positions of the input connection portion 15b of the second element 19 are screwed into screw holes opened on the side surface on the other side in the axial direction of the input large-diameter cylindrical portion 16 of the first element 18, and the input member 8 is constituted by coupling the first element 18 and the second element 19.

[0035] In this example, the input member 8 has an oil hole 58 for supplying lubricating oil to the one-way clutch 10. The oil hole 58 is provided so as to axially penetrate at least one circumferential position in the radial position that axially overlaps the one-way clutch 10 disposed radially inside the input large-diameter cylindrical portion 16 in the input connection portion 15b on the other side in the axial direction. In this example, the oil holes 58 are provided at eight equally spaced circumferential positions of the input connection portion 15b.

[0036] The case member 9 is disposed coaxially with the input member 8 inside the radial direction of the input member 8 and is capable of relative rotation with respect to the input member 8. That is, the central axis O8 of the input member 8 and the central axis O9 of the case member 9 coincide with each other. In this example, the case member 9 is configured in a stepped cylindrical shape and is supported inside the radial direction of the input member 8 so as to be capable of relative rotation with respect to the input member 8. The case member 9 includes, in order from one axial side, a case small-diameter cylindrical portion 21a, a case connection portion 22a, a case large-diameter cylindrical portion 23, a case connection portion 22b, and a case small-diameter cylindrical portion 21b.

[0037] The case small-diameter cylindrical portion 21a on one axial side has a cylindrical shape.

[0038] The case connection portion 22a on one axial side has a substantially hollow circular plate shape and connects the end portion on the other axial side of the case small-diameter cylindrical portion 21a on one axial side and the end portion on one axial side of the case large-diameter cylindrical portion 23. That is, the inner end portion in the radial direction of the case connection portion 22a is connected to the end portion on the other axial side of the case small-diameter cylindrical portion 21a, and the outer end portion in the radial direction of the case connection portion 22a is connected to the end portion on one axial side of the case large-diameter cylindrical portion 23.

[0039] The case large-diameter cylindrical portion 23 has a substantially cylindrical shape. The case member 9 has at least one support hole 24 penetrating the case member 9 in the radial direction. The support holes 24 are provided in the same number as the number of pinion gears 11. In this example, since two pinion gears 11 are provided, two support holes 24 are provided in the case member 9. The two support holes 24 are formed at two locations on opposite sides in the radial direction of the axial intermediate portion of the case large-diameter cylindrical portion 23 so as to penetrate in the radial direction. The axial both ends of the support shaft 25 for supporting the two pinion gears 11 are fitted and supported in the two support holes 24 without play in the radial direction.

[0040] The large-diameter cylindrical portion 23 of the case has a through-hole 26 that axially penetrates a portion adjacent to one (lower side in FIGS. 2 and 3) of the support holes 24 on one axial side, and has a concave hole 27 that opens to the inner peripheral surface of the one support hole 24 in a portion adjacent to the other axial side of the one support hole 24. At both axial ends of the pin 28, the ends are press-fitted and inserted into the through-hole 26 and the concave hole 27. Further, the intermediate portion in the axial direction of the pin 28 is inserted into a through-hole 29 that radially penetrates the end portion on one axial side (lower side in FIGS. 2 and 3) of the support shaft 25 without rattling, thereby preventing the axial movement and rotation of the support shaft 25 with respect to each support hole 24.

[0041] The large-diameter cylindrical portion 23 of the case has window holes 30 that radially penetrate at at least one position, for example, two positions on the radially opposite sides, that are deviated from the respective support holes 24 in the circumferential direction, in a portion from one axial end to the intermediate portion in the axial direction. When assembling the differential device 1, the pinion gear 11 and the side gear 12 are arranged inside the large-diameter cylindrical portion 23 of the case through the window holes 30.

[0042] The case member 9 has a fitting surface portion 31 in a portion of the outer peripheral surface that is axially deviated from the radially outer opening of the support hole 24. Specifically, in this example, the fitting surface portion 31 is provided on the outer peripheral surface of the end portion on the other axial side of the large-diameter cylindrical portion 23 of the case. In this example, the large-diameter cylindrical portion 23 of the case bends radially outward from the end portion on one axial side of the fitting surface portion 31 and has a stepped surface 32 facing the other axial side.

[0043] The case connection portion 22b on the other axial side has a substantially hollow circular plate shape and connects the end portion on the other axial side of the large-diameter cylindrical portion 23 of the case and the end portion on one axial side of the small-diameter cylindrical portion 21b of the case on the other axial side. That is, the radially outer end portion of the case connection portion 22b is connected to the end portion on the other axial side of the large-diameter cylindrical portion 23 of the case, and the radially inner end portion of the case connection portion 22b is connected to the end portion on one axial side of the small-diameter cylindrical portion 21b of the case.

[0044] The small-diameter cylindrical portion 21b of the case on the other axial side has a cylindrical shape.

[0045] In this example, the case member 9 is made of a ferroalloy such as chrome molybdenum steel (SCM material), and the surface hardness is adjusted to a predetermined range by heat treatment. Specifically, the surface of the case member 9 preferably has a surface hardness of HV300 or more and HV350 or less, although it is not limited thereto.

[0046] At least one of the rolling bearings 33a, 33b, 38a, 38b is disposed at a portion axially displaced from the inner ring member 48 constituting the one-way clutch 10 among the portions between the input member 8 and the case member 9. In other words, the case member 9 is rotatably supported radially inward of the input member 8 by at least one of the rolling bearings 33a, 33b, 38a, 38b disposed at a portion axially displaced from the inner ring member 48. The rolling bearings 33a, 33b, 38a, 38b have an outer diameter smaller than the inner diameter of the inner ring member 48.

[0047] In this example, the case member 9 is rotatably supported radially inward of the input member 8 by a first thrust needle bearing 33a and a first radial needle bearing 38a disposed on one axial side of the inner ring member 48 and a second thrust needle bearing 33b and a second radial needle bearing 38a disposed on the other axial side of the inner ring member 48 among the portions between the input member 8 and the case member 9.

[0048] When implementing the present disclosure, the type and number of rolling bearings for rotatably supporting the case member radially inward of the input member are not limited to this example. For example, ball bearings, tapered roller bearings, spherical bearings, etc. can also be used as the rolling bearings. Also, the number of rolling bearings can be three or less or five or more.

[0049] The first thrust needle bearing 38a is disposed between the side surface on the other axial side of the input connection portion 15a of the input member 8 and the side surface on one axial side of the case connection portion 22a of the case member 9. Among the first thrust needle bearings 38a, the outer diameter of the thrust race 39, which is the maximum outer diameter portion, is smaller than the inner diameter of the end portion on one axial side of the inner ring member 48.

[0050] The second thrust needle bearing 38b is disposed between the side surface on one axial side of the input connection portion 15b of the input member 8 and the side surface on the other axial side of the case connection portion 22b of the case member 9. Among the second thrust needle bearings 38b, the outer diameter of the thrust race 39, which is the maximum outer diameter portion, is smaller than the inner diameter of the end portion on the other axial side of the inner ring member 48.

[0051] Each of the first thrust needle bearing 38a and the second thrust needle bearing 38b includes at least one thrust race 39, 45 and a plurality of needles 40. In this example, each of the first thrust needle bearing 38a and the second thrust needle bearing 38b includes a pair of thrust races 39, 45 that sandwich a plurality of needles 40 from both axial sides. Also, in this example, each of the first thrust needle bearing 38a and the second thrust needle bearing 38b includes a cage 44 that rotatably holds a plurality of needles 40.

[0052] Of the pair of thrust races 39, 45, one thrust race 39 supported and fixed on the input member 8 side has notches 41 provided at a plurality of circumferential locations on the outer peripheral surface, a thrust race surface 42 provided on the side surface closer to the inner ring member 48 in the axial direction, and, among the side surfaces on the side farther from the inner ring member 48 in the axial direction, at a plurality of locations that are in the same phase as the notches 41 in the circumferential direction, oil grooves 43 that cross the side surface in the radial direction and have outer ends in the radial direction opening into the notches 41. In this example, the thrust race 39 is configured in a hollow circular plate shape. Also, in this example, the notches 41 and the oil grooves 43 are provided at 18 circumferentially equally spaced locations on the thrust race 39.

[0053] Of the pair of thrust races 39 and 45, the other thrust race 45 supported and fixed on the case member 9 side is formed by bending a metal plate, and is configured in an annular shape as a whole with a substantially L-shaped cross section, and has a thrust raceway surface 46 on the side far from the inner ring member 48 in the axial direction.

[0054] The plurality of needles 40 are sandwiched between the thrust raceway surface 42 of the thrust race 39 and the thrust raceway surface 46 of the thrust race 45 in a state of being rotatably arranged by the cage 44.

[0055] In this example, the first thrust needle bearing 38a is brought into contact with the axially other side surface of the input connection portion 15a of the input member 8 at the axially one side surface which is the side provided with the plurality of oil grooves 43 in one of the thrust races 39, and the axially other side surface which is the surface opposite to the side provided with the thrust raceway surface 46 in the thrust race 45 is brought into contact with the axially one side surface of the case connection portion 22a of the case member 9 and is installed in this state. The second thrust needle bearing 38b is brought into contact with the axially one side surface of the input connection portion 15b of the input member 8 at the axially other side surface which is the side provided with the plurality of oil grooves 43 in one of the thrust races 39, and the axially one side surface which is the surface opposite to the side provided with the thrust raceway surface 46 in the thrust race 45 is brought into contact with the axially other side surface of the case connection portion 22b of the case member 9 and is installed in this state.

[0056] When implementing the present disclosure, the thrust race having the notch and the oil groove can also be supported and fixed to the case member. Alternatively, notches and oil grooves can be provided in both the thrust race supported and fixed to the input member and the thrust race supported and fixed to the case member.

[0057] The first radial needle bearing 33a is disposed on one axial side of the first thrust needle bearing 38a and radially inside the first thrust needle bearing 38a among the portions between the input member 8 and the case member 9. That is, the outer diameter of the first radial needle bearing 33a is smaller than the outer diameter of the first thrust needle bearing 38a.

[0058] More specifically, the first radial needle bearing 33a is disposed between the inner peripheral surface of the input small-diameter cylindrical portion 14a of the input member 8 and the outer peripheral surface of the case small-diameter cylindrical portion 21a of the case member 9.

[0059] The second radial needle bearing 33b is disposed on the other axial side of the second thrust needle bearing 38b and radially inside the second thrust needle bearing 38b among the portions between the input member 8 and the case member 9. That is, the outer diameter of the second radial needle bearing 33b is smaller than the outer diameter of the second thrust needle bearing 38b.

[0060] More specifically, the second radial needle bearing 33b is disposed between the inner peripheral surface of the input small-diameter cylindrical portion 14b of the input member 8 and the outer peripheral surface of the case small-diameter cylindrical portion 21b of the case member 9.

[0061] In this example, each of the first radial needle bearing 33a and the second radial needle bearing 33b includes an outer ring 34 fitted inside the input small-diameter cylindrical portions 14a, 14b, an inner ring 35 fitted outside the case small-diameter cylindrical portions 21a, 21b, a plurality of needles 36 disposed between the inner peripheral surface of the outer ring 34 and the outer peripheral surface of the inner ring 35, and a cage 37 that holds the plurality of needles 36.

[0062] The one-way clutch 10 is disposed between the input member 8 and the case member 9, and transmits torque between the input member 8 and the case member 9 only when the input member 8 attempts to rotate relative to the case member 9 in the forward rotation direction. Note that the forward rotation direction refers to the relative rotation direction of the input member 8 with respect to the case member 9 when torque is transmitted from the drive source 3 to the wheels 6 to move the vehicle forward.

[0063] In this example, the one-way clutch 10 is disposed between the input large-diameter cylindrical portion 16 of the input member 8 and the case large-diameter cylindrical portion 23 of the case member 9.

[0064] The one-way clutch 10 has an outer-diameter-side engaging surface 47 formed directly on the inner peripheral surface of the input member 8 or via another member, an inner-diameter-side engaging surface 49 formed on the outer peripheral surface of the inner ring member 48 coupled and fixed to the case member 9, and a plurality of engaging elements 50 disposed between the outer-diameter-side engaging surface 47 and the inner-diameter-side engaging surface 49. When the input member 8 attempts to rotate relative to the case member 9 in the forward rotation direction, torque is transmitted between the input member 8 and the case member 9 based on the engagement of the engaging elements 50 with the outer-diameter-side engaging surface 47 and the inner-diameter-side engaging surface 49.

[0065] When implementing the present disclosure, the one-way clutch can be configured by a mechanism that switches between a connected state in which torque is transmitted and a disconnected state in which torque is not transmitted based on the engagement and disengagement of a plurality of engaging elements with respect to an outer-diameter-side engaging surface and an inner-diameter-side engaging surface, such as a sprag clutch or a roller clutch. In this example, the one-way clutch 10 is configured by a sprag clutch. That is, in this example, each of the plurality of engaging elements 50 is configured by a sprag.

[0066] In this example, the outer-diameter-side engaging surface 47 is formed directly on the inner peripheral surface of the input large-diameter cylindrical portion 16 of the input member 8. However, when implementing the present disclosure, the outer-diameter-side engaging surface can also be provided on the inner peripheral surface of the input member via another member. For example, the outer-diameter-side engaging surface can be formed on the inner peripheral surface of an outer ring member that is fitted and fixed to the input member.

[0067] The hardness of the inner-diameter-side engaging surface 49 of the inner ring member 48 is harder than the hardness of the surface of the case member 9. Specifically, although not limited thereto, the inner-diameter-side engaging surface 49 preferably has a surface hardness of HV650 or more and HV750 or less, and an effective hardened layer depth of 0.5 mm or more and 0.9 mm or less.

[0068] In this example, the inner ring member 48 is entirely formed in an annular shape and has a substantially rectangular cross-sectional shape. The inner ring member 48 is made of an iron alloy such as chromium molybdenum steel (SCM material), and through heat treatment, the hardness of the surface of the inner diameter side engaging surface 49 provided on the outer peripheral surface is adjusted to a predetermined range.

[0069] The material constituting the inner ring member 48 can be the same as or different from the material constituting the case member 9. When the inner ring member 48 is made of the same material as the material constituting the case member 9, by adjusting heat treatment conditions such as the carbon concentration of the atmosphere gas, heating time, and heating temperature, the hardness of the surface of the inner diameter side engaging surface 49 is made harder than the hardness of the surface of the case member 9.

[0070] In any case, at least the hardness of the surface of the inner diameter side engaging surface 49 of the inner ring member 48 is adjusted to a predetermined range that is harder than the hardness of the surface of the case member 9. In this example, the hardness of the entire surface of the inner ring member 48 including the inner diameter side engaging surface 49 is adjusted to a predetermined range that is harder than the hardness of the surface of the case member 9.

[0071] The inner ring member 48 has a stepped surface 51 facing the one axial side at a portion near the end on one axial side of the inner peripheral surface.

[0072] The inner ring member 48 has a scraping groove 52 at at least one location in the circumferential direction of the side surface closer to the rolling bearings 33a, 33b, 38a, and 38b in the axial direction.

[0073] The scraping groove 52 extends in the radial direction, and the radially outer end opens to the outer peripheral surface of the inner ring member 48. In this example, the radially inner end of the scraping groove 52 does not open to the inner peripheral surface of the inner ring member 48. However, the radially inner end of the scraping groove can also be opened to the inner peripheral surface of the inner ring member.

[0074] In this example, the scraping grooves 52 are provided at a plurality of circumferential positions on each of the side surfaces on both axial sides of the inner ring member 48. More specifically, the scraping grooves 52 are provided at 18 circumferentially equally spaced positions on the side surfaces on both axial sides of the inner ring member 48.

[0075] The inner ring member 48 is externally fitted to the fitting surface portion 31 of the case member 9. Specifically, in this example, the portion of the inner circumferential surface of the inner ring member 48 that is located on the other axial side with respect to the stepped surface 51 is externally fitted to the fitting surface portion 31 of the case member 9 by press-fitting, and the stepped surface 51 of the inner ring member 48 is in contact with the stepped surface 32 of the case member 9.

[0076] In this state, the inner ring member 48 is welded and fixed to the case member 9 at the end portions on the opposite side of each support hole 24 of the case member 9 in the axial direction, that is, at the end portions on the other axial side. Specifically, at least one circumferential position of the radially inner end portion of the side surface on the other axial side of the inner ring member 48 is welded and fixed to the case member 9 by a welding bead 53 (only shown in FIG. 3). When implementing the present disclosure, the method of coupling and fixing the inner ring member to the case member is not limited to the method of this example, and any fixing method such as caulking fixation or bolt fixation can be adopted.

[0077] In this example, the one-way clutch 10 further includes a retainer 54 and a biasing spring 55.

[0078] The engaging elements 50 are arranged in a state of being held by the retainer 54 at a plurality of circumferential positions in the cylindrical space between the outer diameter side engaging surface 47 and the inner diameter side engaging surface 49.

[0079] The biasing spring 55 biases each engaging element 50 in a direction in which the engaging element 50 meshes with the outer diameter side engaging surface 47 and the inner diameter side engaging surface 49.

[0080] When the input member 8 attempts to rotate relative to the case member 9 in the forward rotation direction, each engaging element 50 swings in a predetermined direction and meshes with the outer diameter side engaging surface 47 and the inner diameter side engaging surface 49. As a result, the one-way clutch 10 switches to a locked state where it is in a connected state, and it becomes possible to transmit torque between the input member 8 and the case member 9. That is, the case member 9 can rotate integrally with the input member 8.

[0081] On the other hand, when the input member 8 attempts to rotate relative to the case member 9 in the reverse rotation direction, the engaging element 50 swings in a direction opposite to the predetermined direction, and the one-way clutch 10 switches to an overrunning state where the engagement of the engaging element 50 with the outer diameter side engaging surface 47 and the inner diameter side engaging surface 49 is disengaged. As a result, torque transmission between the input member 8 and the case member 9 becomes impossible. That is, the input member 8 idles relative to the case member 9, or the case member 9 idles relative to the input member 8.

[0082] The pinion gear 11 is supported with respect to the case member 9 so as to be able to rotate about an axis orthogonal to the central axis O9 of the case member 9. In this example, two pinion gears 11 are provided, and each pinion gear 11 is constituted by a bevel gear. That is, the pinion gear 11 has a substantially frustum shape and has a plurality of teeth on its outer peripheral surface. Further, the pinion gear 11 has a central hole 56 penetrating in the axial direction of the pinion gear 11 at its center. The pinion gear 11 is rotatably supported around a support shaft 25 whose both axial end portions are internally fitted and supported in two support holes 24 of the case member 9.

[0083] A pair of side gears 12 are supported coaxially with the central axis O8 of the input member 8 so as to be rotatable relative to the input member 8 and the case member 9, and mesh with the pinion gear 11. The side gears 12 constituting the pair of side gears 12 are constituted by bevel gears. That is, the side gear 12 has a substantially frustum shape and has a plurality of teeth on its outer peripheral surface that mesh with the teeth of the pinion gear 11. Further, the side gear 12 has a spline hole 57 penetrating axially at its center. The side gear 12 is disposed inside the case large-diameter cylindrical portion 23 of the case member 9 and is fixedly coupled to the base end portion of the drive shaft 5 so as to be able to transmit torque. That is, the spline shaft portion provided at the base end portion of the drive shaft 5 is spline-engaged with the spline hole 57.

[0084] <When the vehicle is coasting forward> When the vehicle is to be moved forward, with the shift lever switched to the forward drive range, when torque in the direction of moving the vehicle forward is output from the drive source 3 based on an operation of the accelerator by the driver or the like, the torque is increased by the power transmission mechanism 4 and then transmitted to the input member 8. As a result, when the input member 8 tries to rotate relative to the case member 9 in the forward rotation direction, the one-way clutch 10 switches to the connected state, and the input member 8 and the case member 9 rotate integrally.

[0085] When the case member 9 rotates, the two pinion gears 11 rotate about the central axis O9 of the case member 9, that is, revolve, and further, based on the meshing of the teeth of the pinion gear 11 and the teeth of the side gear 12, the pair of side gears 12 rotate about their own central axes arranged coaxially with the central axis O8 of the input member 8. As a result, the pair of drive shafts 5 fixedly coupled to the pair of side gears 12 are rotationally driven, and the pair of wheels 6 are rotationally driven in the direction of moving the vehicle forward.

[0086] <When the vehicle is coasting forward> With the vehicle moving forward as described above, in order to perform coasting driving or sailing driving, etc., which are called inertial driving, when the accelerator is turned off and the input of torque from the drive source 3 to the input member 8 stops, the rotational speed of the input member 8 in the forward rotation direction decreases and becomes slower than the rotational speed of the case member 9 in the forward rotation direction. That is, the input member 8 rotates relative to the case member 9 in the reverse rotation direction. As a result, the one-way clutch 10 switches to the disengaged state, and the case member 9 idles relative to the input member 8.

[0087] In short, a pair of wheels 6 is disconnected from the power transmission mechanism 4 and the drive source 3. Therefore, the driving distance by inertial driving can be lengthened. In other words, the speed reduction during inertial driving can be made gentle. As a result, the fuel consumption performance and electricity consumption performance of the vehicle can be improved.

[0088] <When the vehicle is moving backward> In the vehicle equipped with the driving device 2 for an automobile of this example, at least one pair of wheels different from the pair of wheels 6 is rotationally driven in the direction in which the vehicle moves backward to move the vehicle backward. In this example, the pair of wheels 6 cannot be rotationally driven in the direction in which the vehicle moves backward.

[0089] That is, in order to move the vehicle backward, when the shift lever is switched to the reverse driving range and the torque output from the drive source 3 is increased by the power transmission mechanism 4 and then transmitted to the input member 8 based on the driver's operation of the accelerator, etc., the input member 8 tries to rotate relative to the case member 9 in the reverse rotation direction. As a result, the one-way clutch 10 switches to the disengaged state, and the case member 9 idles relative to the input member 8. In short, since a pair of wheels 6 is disconnected from the power transmission mechanism 4 and the drive source 3, it is not rotationally driven in the direction in which the vehicle moves backward.

[0090] Note that in any driving state, the difference in rotational speed between the pair of wheels 6 that occurs during turning driving, etc., is absorbed by the two pinion gears 11 rotating, that is, revolving, around the support shaft 25.

[0091] In the differential device 1 of this example, even when the rotation of the input member 8 stops during coasting, it is easy to maintain a good lubrication state of the rolling bearings 33a, 33b, 38a, 38b for rotatably supporting the case member 9 with respect to the input member 8 and the one-way clutch 10 over the entire circumference.

[0092] That is, in the differential device 1 of this example, even when the rotation of the input member 8 stops during coasting, the case member 9 and the inner ring member 48 rotate, and through the oil hole 58 provided in the input connection portion 15b of the input member 8, it is supplied to the portion between the input member 8 and the case member 9, and the lubricating oil accumulated in the lower portion of the portion can be scraped up by the scraping grooves 52 provided on the side surfaces on both axial sides of the inner ring member 48.

[0093] The lubricating oil scraped up by the scraping grooves 52 moves from the lower part to the upper part of the portion between the input member 8 and the case member 9 while being held by the scraping grooves 52 as shown by the dashed arrow α1 in FIG. 2, and is flung off by the action of the centrifugal force accompanying the rotation of the inner ring member 48.

[0094] A part of the flung-off lubricating oil adheres to the inner peripheral surface of the input large-diameter cylindrical portion 16 of the input member 8, and lubricates the portion of the outer diameter side engagement surface 47 provided on the inner peripheral surface of the input large-diameter cylindrical portion 16 that is located above the liquid level S of the lubricating oil accumulated in the lower part of the portion between the input member 8 and the case member 9. The lubricating oil adhering to the outer diameter side engagement surface 47 moves so as to drip onto the surface of the engaging element 50 and the inner diameter side engagement surface 49, and lubricates these surfaces. The inner diameter side engagement surface 49 is also lubricated when the inner diameter side engagement surface 49 passes through the lubricating oil accumulated in the lower part of the portion between the input member 8 and the case member 9 as the inner ring member 48 rotates.

[0095] Also, as shown by the dashed arrow α2, a part of the splashed lubricating oil moves toward both axial sides, passes through the installation locations of the first thrust needle bearing 38a and the second thrust needle bearing 38b and the installation locations of the first radial needle bearing 33a and the second radial needle bearing 33b in sequence, lubricates the first thrust needle bearing 38a and the second thrust needle bearing 38b and the first radial needle bearing 33a and the second radial needle bearing 33b, and then returns to the lower part of the portion between the housing 7 and the input member 8. The lubricating oil returned to the lower part of the portion between the housing 7 and the input member 8 is supplied again to the lower part of the portion between the input member 8 and the case member 9 through the oil hole 58 and is scraped up by the scraping groove 52.

[0096] As can be understood from the above description, in the differential device 1 of this example, when the entirety of the first thrust needle bearing 38a and the second thrust needle bearing 38b and the first radial needle bearing 33a and the second radial needle bearing 33b arranged in the portion between the input member 8 and the case member 9 is located above the liquid level S of the lubricating oil accumulated in the lower part of the portion between the input member 8 and the case member 9, that is, when the first thrust needle bearing 38a and the second thrust needle bearing 38b and the first radial needle bearing 33a and the second radial needle bearing 33b are not immersed in the lubricating oil, as long as the lower part of the inner ring member 48 is immersed in the lubricating oil accumulated in the lower part of the portion between the input member 8 and the case member 9, by scraping up the lubricating oil with the scraping grooves 52 provided on the side surfaces on both axial sides of the inner ring member 48, the first thrust needle bearing 38a and the second thrust needle bearing 38b and the first radial needle bearing 33a and the second radial needle bearing 33b can be continuously supplied with lubricating oil. Therefore, it is easy to maintain the lubrication state of the one-way clutch 10, the two radial needle bearings 33a, 33b, and the two thrust needle bearings 38a, 38b well over the entire circumference.

[0097] Furthermore, in this example, as shown by the arrow α2 in FIG. 2, when the lubricating oil flowing through passes through the installation locations of the first thrust needle bearing 38a and the second thrust needle bearing 38b, a part of it passes through the notch 41 and the oil groove 43 of the thrust race 39, and the remainder passes through the portion between the thrust races 39 and 45. That is, a part of the lubricating oil passes through the installation locations of the first thrust needle bearing 38a and the second thrust needle bearing 38b without being used for lubricating the rolling contact portions between the needles 40 and the thrust raceway surfaces 42 and 46. Therefore, even when the relative rotational speed of the case member 9 with respect to the input member 8 is high, since a sufficient supply amount of lubricating oil to the first radial needle bearing 33a and the second radial needle bearing 33b is ensured, seizure of the first radial needle bearing 33a and the second radial needle bearing 33b can be prevented, and the durability of the differential device 1 can be improved.

[0098] In this example, the inner diameter side engaging surface 49 of the one-way clutch 10 is not directly formed on the outer peripheral surface of the case member 9, but is formed on the outer peripheral surface of an inner ring member 48 which is configured separately from the case member 9 and is coupled and fixed to the case member 9, and the hardness of the inner diameter side engaging surface 49 of the inner ring member 48 is harder than the hardness of the surface of the case member 9. Therefore, it is easier to ensure the desired performance for each of the case member 9 and the inner ring member 48.

[0099] That is, in this example, by making the hardness of the inner diameter side engaging surface 49 where a plurality of engaging elements 50 mesh in a state where the one-way clutch 10 is switched to the connected state sufficiently hard, the durability of the inner ring member 48 can be easily ensured. Also, by sufficiently ensuring the toughness of the case member 9, damage due to stress concentration at the shape change portion existing in the case member 9 can be effectively prevented. Therefore, the durability of the case member 9 can be easily ensured.

[0100] In this example, the inner ring member 48 is externally fitted to the fitting surface portion 31 of the case member 9, and the end portion on the side far from the support hole 24 in the axial direction is welded and fixed to the case member 9. Therefore, even if deformation due to welding occurs in the peripheral portion of the welded fixed portion of the case member 9, it is possible to effectively prevent the deformation from reaching the respective support holes 24. Accordingly, it is possible to effectively prevent inconveniences such as the central axis of the support shaft 25 supported at both axial ends by the respective support holes 24 tilting with respect to the virtual plane orthogonal to the central axis O9 of the case member 9.

[0101] When implementing the differential device of the present disclosure, a structure provided with a clutch device that is disposed between the input member and the case member and that can switch the connection / disconnection state between the input member and the case member can be adopted.

[0102] In a differential device having such a structure, with the clutch device in the disengaged state with the shift lever switched to the forward travel range, when the vehicle coasts, that is, when the input member rotates relative to the case member in the reverse direction, the one-way clutch switches to the disengaged state, and the case member can be idled relative to the input member. Also, with the clutch device in the engaged state with the shift lever switched to the reverse travel range, when the vehicle is traveling in reverse, the input member and the case member can be integrally rotated by the torque input to the input member from the drive source via the power transmission mechanism. Thereby, a pair of wheels connected to the differential device can be rotationally driven in the direction in which the vehicle is traveling in reverse.

Explanation of Reference Numerals

[0103] 1 Differential device 2 Driving device for automobile 3 Drive source 4 Power transmission mechanism 4a Output gear 5 Drive shaft 6 Wheel 7 Housing 8 Input member 9 Case member 10 One-way clutch 11 Pinion gear 12 Side gear 13 Ring gear 14a, 14b Input small-diameter cylindrical part 15a, 15b Input connection part 16 Input large-diameter cylindrical part 17a, 17b Tapered roller bearing 18 First element 19 Second element 20 Bolt 21a, 21b Case small-diameter cylindrical part 22a, 22b Case connection part 23 Case large-diameter cylindrical part 24 Support hole 25 Support shaft 26 Through hole 27 Concave hole 28 Pin 29 Through hole 30 Window hole 31 Fitting surface part 32 Step surface 33a First radial needle bearing 33b Second radial needle bearing 34 Outer ring 35 Inner ring 36 Needle 37 Retainer 38a First thrust needle bearing 38b Second thrust needle bearing 39 Thrust race 40 Needle 41 Notch 42 Thrust raceway surface 43 Oil groove 44 Retainer 45 Thrust race 46 Thrust raceway surface 47 Outer diameter side engagement surface 48 Inner ring member 49 Inner diameter side engagement surface 50 Engager 51 Step surface 52 Scraper groove 53 Weld bead 54 Retainer 55 Biasing Spring 56 Central Hole 57 Spline Hole 58 Oil Hole

Claims

1. An input member having a torque input portion; A case member coaxially arranged inside the input member in the radial direction and capable of relative rotation with respect to the input member; An outer diameter side engaging surface formed directly on the inner peripheral surface of the input member or via another member, an inner diameter side engaging surface formed on the outer peripheral surface of the inner ring member coupled and fixed to the case member, and an engaging element disposed between the outer diameter side engaging surface and the inner diameter side engaging surface. When the input member attempts to rotate relative to the case member in the forward rotation direction, the engaging element engages with the outer diameter side engaging surface and the inner diameter side engaging surface, and based on this, a one-way clutch that transmits torque between the input member and the case member; At least one rolling bearing disposed in a portion axially disengaged from the inner ring member among the portions between the input member and the case member and having an outer diameter smaller than the inner diameter of the inner ring member; At least one pinion gear supported by the case member so as to be rotatable about an axis orthogonal to the central axis of the case member; A pair of side gears coaxially arranged with the central axis of the input member, supported so as to be capable of relative rotation with respect to the input member and the case member, and meshing with the pinion gear; Comprising; The inner ring member has a scraping groove at at least one location in the circumferential direction of the side surface closer to the rolling bearing in the axial direction; Differential device.

2. The at least one rolling bearing includes a thrust rolling bearing and a radial rolling bearing arranged on the side farther from the inner ring member than the thrust rolling bearing in the axial direction and radially inside the thrust rolling bearing; The thrust rolling bearing has at least one thrust race and a plurality of rolling elements; The at least one thrust race has notches provided at a plurality of locations in the circumferential direction of the outer peripheral surface, a thrust raceway surface provided on one of the side surfaces on both axial sides and in rolling contact with the rolling surfaces of the plurality of rolling elements, and on the other side surface on both axial sides, among the side surfaces facing the inner surface of the input member or the case member, at a plurality of locations in phase with the notches in the circumferential direction, oil grooves provided so as to cross the side surface in the radial direction and having radially outer ends opening into the notches; The differential device according to Claim 1.

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