Differential device for vehicle and vehicle

Abstract

The invention provides a vehicle differential device and a vehicle which can adjust differential limiting force with a simple structure. A differential device for a vehicle is provided with: a pair of side gears (34) disposed within a differential case (31); a plurality of friction plates (43) disposed on the outside in the axial direction with respect to the side gear (34); and pressing members (41, 42) that sandwich the plurality of friction plates (43) together with the side gears (34). The side gear (34) has: a gear section (34a) that meshes with the pinion gear (33); and a cylindrical portion (34b) extending radially outward from a radially inward portion of the gear portion (34a). The outer peripheral portion of the cylindrical portion (34b) is engaged with the inner peripheral portions of the pressing members (41, 42) via a helical spline (45).

Description

Technical Field

[0001] The technology disclosed herein belongs to the technical field related to a vehicle differential device and a vehicle. Background Art

[0002] Conventionally, a differential device having a differential limiting mechanism is known.

[0003] For example, Patent Document 1 discloses a differential device comprising: a differential case that is driven to rotate by the driving force of an engine; a differential gear mechanism that distributes the rotation of the differential case to the wheel side via a pair of side gears; a cone clutch that is formed between the differential case and a clutch member, is tightened by the meshing reaction force of the side gears, and limits the differential of the differential gear mechanism; and a cam mechanism that is arranged between the clutch member and the side gears, is actuated by the driving force, and presses the cone clutch.

[0004] The differential device of Patent Document 1 uses a helical spline as a cam mechanism.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 09-49560

[0008] Technical problem to be solved by the invention

[0009] However, from the viewpoint of improving the driving performance, it is being studied to make the differential limiting force for limiting the differential of the left and right drive wheels different during acceleration and deceleration. Patent document 1 discloses that when the vehicle is accelerated, the cone clutch is pressed against the differential case by the meshing reaction force from the pinion gear to the side gear and the outward meshing thrust reaction force from the helical spline, while when the vehicle is decelerated (when braking), the force pressing the cone clutch against the differential case is reduced by the inward meshing thrust reaction force from the helical spline.

[0010] However, the inventors of the present application and others have studied the differential device described in Patent Document 1 and found that the differential device described in Patent Document 1 does not take into account the reaction from the helical spline. That is, in the differential device described in Patent Document 1, in addition to the above-mentioned force, an inward reaction force is applied to the side gear by the reaction from the helical spline when the vehicle is accelerated. Since the inward reaction force applied to the side gear is equal to the above-mentioned meshing thrust reaction force, the force pressing the cone clutch is only the meshing reaction force from the pinion gear to the side gear. On the other hand, when the vehicle is decelerated, in addition to the above-mentioned force, an outward reaction force is applied to the side gear by the reaction from the helical spline, so the force pressing the cone clutch is only the meshing reaction force from the pinion gear to the side gear. Therefore, in the differential device described in Patent Document 1, the differential limiting force hardly changes during acceleration and deceleration.

[0011] Although electronic control is also being studied to adjust the differential limiting force, it is inevitable that the structure of the differential device will become complicated or the cost will increase. Summary of the invention

[0012] The technology disclosed herein has been accomplished in view of this point, and an object of the technology is to provide a differential device capable of adjusting the differential limiting force with a simple structure.

[0013] Technical means for solving technical problems

[0014] In order to solve the above-mentioned technical problems, in the first mode of the technology disclosed herein, a vehicle differential device mounted on a vehicle is used as an object, and its structure is as follows: a differential case, which is rotated by the driving force of a driving source; a pair of side gears, which are arranged coaxially with the rotating shaft of the differential case in the differential case; a pinion gear, which meshes with both sides of the pair of side gears; and a differential limiting mechanism, which is arranged on at least one side in the direction of the rotating shaft, and the differential limiting mechanism has: a plurality of friction plates, which are arranged relative to the plurality of friction plates in the direction of the rotating shaft. The side gear is arranged on the opposite side of the pinion; and a pressing component, which is arranged on the opposite side of the side gear across the multiple friction plates in the direction of the rotating axis, and clamps the multiple friction plates together with the side gear. The side gear located on the one side in the direction of the rotating axis has: a gear portion, which meshes with the pinion; and a barrel portion, which extends from a portion of the gear portion radially inside the rotating axis toward the opposite side of the pinion, and the barrel axis of the barrel portion is coaxial with the rotating axis, and the outer periphery of the barrel portion is meshed with the inner periphery of the pressing component via a helical spline.

[0015] According to this structure, when the force of the side of the pressing member away from the friction plate acts on the helical spline, the force of the side away from the friction plate is also input to the side gear due to the reaction from the helical spline. As a result, the force clamping the plurality of friction plates is reduced, and the friction force acting between the plurality of friction plates is reduced, so the differential limiting force is reduced. On the other hand, when the force of the side of the pressing member approaching the friction plate acts on the helical spline, the force of the side approaching the friction plate is also input to the side gear due to the reaction from the helical spline. As a result, the force clamping the plurality of friction plates is increased, and the friction force acting between the plurality of friction plates is increased, so the differential limiting force is increased. Since the direction of the force acting on the helical spline is opposite during acceleration and deceleration, the differential limiting force can be changed during acceleration and deceleration. In addition, if the angle of the spline teeth of the helical spline is adjusted, the magnitude of the differential limiting force can be adjusted, so the magnitude of the differential limiting force can also be easily adjusted. Therefore, the differential limiting force can be adjusted with a simple structure.

[0016] A second aspect of the technology disclosed herein is configured such that, in the first aspect, a portion of the plurality of friction plates is spline-fitted with the pressing member, and the remaining portion of the plurality of friction plates is fixed to the differential case.

[0017] According to this structure, the portion of the cylinder of the side gear that can be used for the helical spline can be expanded as much as possible. Therefore, even if the cylinder is shortened in the direction of the rotation axis, a sufficient force can be input to the side gear via the helical spline, so that the differential device can be made into a more compact structure.

[0018] A third aspect of the technology disclosed herein is configured such that, in the first aspect, a portion of the plurality of friction plates is spline-fitted to the cylindrical portion, and the remaining portion of the plurality of friction plates is fixed to the differential case.

[0019] According to this structure, since a part of the friction plate is integrated with the side gear, a relatively large thrust load can be input, thereby making it possible to expand the range of the adjustable differential limiting force as much as possible.

[0020] The fourth mode of the technology disclosed herein is structured as follows in the above-mentioned first mode: the differential limiting mechanism also has a disc spring, which inputs force toward the pressing component side in the direction of the rotation axis to the multiple friction plates, and the gear portion has a spring receiving portion, which is arranged on the side of the friction plate in the direction of the rotation axis and is recessed to the opposite side of the friction plate in the direction of the rotation axis, and the spring receiving portion receives the disc spring.

[0021] According to this structure, the initial torque can be applied to the friction plate by the disc spring. By arranging the disc spring in the spring receiving portion, the differential device can be restrained from expanding in the direction of the rotation axis by the disc spring. That is, a mechanism for applying the initial torque can be adopted, and the differential device can be made into a compact structure. In addition, by accommodating the disc spring in the spring receiving portion, the initial torque can be input to the friction plate independently of the meshing reaction force between the pinion and the side gear and the force via the helical spline. Thus, the size of the initial torque can be appropriately set.

[0022] A fifth aspect of the technology disclosed herein has a structure in which the differential limiting mechanism is disposed on both sides in the direction of the rotation axis.

[0023] According to this configuration, since the differential between the side gears can be limited, the differential limiting capability can be appropriately exhibited.

[0024] A sixth aspect of the technology disclosed herein, in any one of the first to fifth aspects, is configured such that the vehicle is a rear-wheel drive or all-wheel drive vehicle, and the vehicle differential device is used for differential control of rear wheels of the vehicle.

[0025] In particular, in the seventh mode of the technology disclosed herein, in the above-mentioned sixth mode, its structure is: the spline teeth of the helical spline are formed so that when the vehicle is accelerated, a force on the side away from the friction plate is input from the helical spline to the side gear, and on the other hand, when the vehicle is decelerated, a force on the side close to the friction plate is input from the helical spline to the side gear.

[0026] That is, from the perspective of the vehicle's straight-ahead stability, it is required to improve the stability of the vehicle in the yaw direction. When the vehicle is accelerated, the load applied to the rear wheels increases due to the sinking of the rear part of the vehicle, so the stability of the rear part of the vehicle in the yaw direction is high. On the other hand, when the vehicle is decelerated, the load applied to the rear wheels decreases due to the rise of the rear part of the vehicle, so the stability of the rear part of the vehicle in the yaw direction decreases. Therefore, compared with when the vehicle is accelerated, it is required to increase the differential limiting force when the vehicle is decelerated to improve the stability of the rear part of the vehicle in the yaw direction. In the above structure, when accelerating, the differential limiting force is reduced because the force on the side away from the friction plate is input to the side gear. On the other hand, when decelerating, the differential limiting force is increased because the force on the side close to the friction plate is input to the side gear. Therefore, the differential limiting force can be appropriately adjusted when the vehicle is accelerated and when the vehicle is decelerated.

[0027] The eighth aspect of the technology disclosed herein is directed to a vehicle. Specifically, the vehicle comprises: a front drive unit that drives the front wheels to rotate; and a rear drive unit that can drive the rear wheels to rotate independently of the front drive unit, and includes the vehicle differential device of the seventh aspect.

[0028] According to this configuration, the differential limiting force applied to the rear wheels can be appropriately adjusted during acceleration and deceleration of the vehicle, thereby improving the straight-ahead stability of the vehicle.

[0029] Effects of the Invention

[0030] As described above, according to the technology disclosed herein, a differential device capable of adjusting the differential limiting force can be configured with a simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of a vehicle including the differential device according to the first embodiment.

[0032] Figure 2 It is a cross-sectional view of the differential device.

[0033] Figure 3 yes Figure 2 Magnified view of region III.

[0034] Figure 4 This is a schematic diagram showing the force input to the friction plate during acceleration.

[0035] Figure 5 This is a schematic diagram showing the force input to the friction plate during deceleration.

[0036] Figure 6 This is a cross-sectional view of the differential device according to the second embodiment.

[0037] Explanation of symbols

[0038] 1 Vehicle

[0039] 2 front wheels

[0040] 3 rear wheels

[0041] 10Front drive unit

[0042] 20 rear drive unit

[0043] 21 Rear drive motor (drive source)

[0044] 30 Rear differential

[0045] 31 Differential housing

[0046] 33 small gear

[0047] 34 side gear

[0048] 34a Gear unit

[0049] 34b barrel

[0050] 34c Spring housing

[0051] 40 Differential limiting mechanism

[0052] 41 first pressing member

[0053] 42 second pressing member

[0054] 43 Friction plate

[0055] 44 coil spring

[0056] 45 first helical spline

[0057] 45a First inner spline tooth

[0058] 45b First outer spline tooth

[0059] 46 Second helical spline

[0060] 46a Second inner spline tooth

[0061] 46b Second outer spline tooth

[0062] 230 rear differential

[0063] 234 side gear

[0064] 234a Gear unit

[0065] 234b barrel

[0066] 240 Differential Limiting Mechanism

[0067] 245 first helical spline

[0068] 245a First inner spline tooth

[0069] 245b First outer spline tooth

[0070] 246 second helical spline

[0071] 246a Second inner spline tooth

[0072] 246b Second outer spline tooth

[0073] X axis of rotation. DETAILED DESCRIPTION

[0074] In the following description, "up", "down", "front", "back", "right", and "left" are based on the "up", "down", "front", "back", "right", and "left" observed by the occupants of the vehicle 1.

[0075] (Implementation Method 1)

[0076] (Overall structure of the vehicle)

[0077] Figure 1 The vehicle 1 having the rear differential device 30 according to the first embodiment is shown. The vehicle 1 is an electric vehicle. The vehicle 1 is an all-wheel drive vehicle in which both the front wheels 2 and the rear wheels 3 are driven and rotated. The vehicle 1 can independently rotate the front wheels 2 and the rear wheels 3. A front drive unit 10 for rotating the front wheels 2 is arranged at the front of the vehicle 1, and a rear drive unit 20 for rotating the rear wheels 3 is arranged at the rear of the vehicle 1. The vehicle 1 is not provided with a shaft such as a drive shaft for transmitting a driving force in the front-rear direction of the vehicle.

[0078] The front drive unit 10 includes a front drive motor 11, a front speed reducer 12, and a front differential device 13. The front drive motor 11 is a drive source for rotating the front wheels 2. The rotation of the front drive motor 11 is decelerated by the front speed reducer 12 and then transmitted to the front differential device 13. The front differential device 13 is connected to the left and right front wheels 2 via a front drive shaft 14. The front differential device 13 differentially drives the left and right front wheels 2 according to the driving state of the vehicle 1.

[0079] The rear drive unit 20 includes a rear drive motor 21, a rear speed reducer 22, and a rear differential device 30. The configuration of the rear drive unit 20 is symmetrical in the front-rear direction with respect to the configuration of the front drive unit 10. The rear drive motor 21 is a drive source for rotating the rear wheels 3. The rotation of the rear drive motor 21 is decelerated by the rear speed reducer 22 and then transmitted to the rear differential device 30. The rear differential device 30 is connected to the left and right rear wheels 3 via the rear drive shaft 24. The rear differential device 30 differentially drives the left and right rear wheels 3 according to the driving state of the vehicle 1.

[0080] In this embodiment, the rear differential device 30 is particularly elaborated, so the structure of the rear differential device 30 is described in detail below. In addition, the front drive motor 11, the front speed reducer 12, the front differential device 13, the rear drive motor 21 and the rear speed reducer 22 can adopt known structures.

[0081] (Rear differential)

[0082] Figure 2 The rear differential device 30 is schematically shown. The rear differential device 30 includes a differential case 31 , a pinion shaft 32 fixed to the differential case 31 , a pair of pinion gears 33 rotating around the pinion shaft 32 , and a pair of side gears 34 meshing with the pinion gears 33 .

[0083] The differential case 31 is rotated by the driving force of the rear drive motor 21. The differential case 31 receives the driving force from the rear speed reducer 22 via the final driven gear (not shown) and rotates around the rotation axis X. The rotation axis X extends straight in the vehicle width direction. In the following description, unless otherwise specified, "axial direction" means the extending direction of the rotation axis X, and "radial direction" means the direction orthogonal to the rotation axis X.

[0084] The pinion shaft 32 extends in a direction orthogonal to the rotation axis X. The center axis C of the pinion shaft 32 passes through the rotation axis X and is orthogonal to the rotation axis X. The pinion shaft 32 rotates around the rotation axis X together with the differential case 31 when the differential case 31 rotates.

[0085] Each pinion gear 33 is respectively arranged in the differential case 31. Each pinion gear 33 is respectively mounted on the pinion shaft 32 in a manner that it can rotate around the pinion shaft 32. One pinion gear 33 is arranged on one end side of the pinion shaft 32, and the other pinion gear 33 is arranged on the other end side of the pinion shaft 32 across the rotation axis X. When the differential case 31 rotates, each pinion gear 33 rotates around the rotation axis X together with the pinion shaft 32. The rotation radius of the pinion gear 33 on one side relative to the rotation axis X is the same as the rotation radius of the pinion gear 33 on the other side relative to the rotation axis X. Each pinion gear 33 is respectively meshed with both sides of a pair of side gears 34. A washer 33a is arranged between the pinion gear 33 and the differential case 31 in the radial direction.

[0086] Each side gear 34 is cylindrical. The cylindrical axis of each side gear 34 is coaxial with the rotation axis X. That is, each side gear 34 is arranged in the differential case 31 coaxially with the rotation axis X. The side gear 34 on one side and the side gear 34 on the other side are arranged mirror-symmetrically with respect to a plane passing through the central axis C and orthogonal to the rotation axis X.

[0087] Each side gear 34 has a gear portion 34a meshing with the pinion gear 33 and a barrel portion 34b extending from the radially inner portion of the gear portion 34a toward the opposite side of the pinion gear 33 in the axial direction (hereinafter referred to as the axially outer side). The rear drive shaft 24 is fastened to the inner circumferential surface of each gear portion 34a and the inner circumferential surface of each barrel portion 34b. A helical spline spline is formed on the outer circumferential surface of each barrel portion 34b. The barrel portion 34b of the right side gear 34 has a first inner spline tooth 45a of a first helical spline 45. The first inner spline tooth 45a is formed over the substantially entirety of the barrel portion 34b of the side gear 34 on the right side. The barrel portion 34b of the side gear 34 on the left side has a second inner spline tooth 46a of a second helical spline 46. The second inner spline tooth 46a is formed over the substantially entirety of the barrel portion 34b of the side gear 34 on the left side.

[0088] like Figure 2 and Figure 3As shown, the rear differential device 30 includes a differential limiting mechanism 40 that applies a differential limiting force to limit the differential of the left and right rear wheels 3. The differential limiting mechanism 40 transmits force to the side gear 34 connected to the other rear wheel 3 even when one of the left and right rear wheels 3 is idling, so that the other rear wheel 3 rotates. The differential limiting mechanisms 40 are respectively arranged on both sides in the axial direction. The right differential limiting mechanism 40 includes a plurality of friction plates 43, a first pressing member 41 that presses the friction plates 43 from the axial outer side, and a pair of disc springs 44 that presses the friction plates 43 from the axial pinion 33 side (hereinafter referred to as the axial inner side). The left differential limiting mechanism 40 includes a plurality of friction plates 43, a second pressing member 42 that presses the friction plates 43 from the axial outer side, and a pair of disc springs 44 that presses the friction plates 43 from the axial inner side. Each differential limiting mechanism 40 is arranged in the differential case 31.

[0089] The plurality of friction plates 43 include first friction plates 43a located relatively on the outside in the radial direction and second friction plates 43b located relatively on the inside in the radial direction. The first friction plates 43a and the second friction plates 43b are alternately arranged in the axial direction.

[0090] The first friction plate 43a is fixed to the differential case 31 so as not to rotate relative to the rotation axis X. The first friction plate 43a rotates together with the differential case 31 about the rotation axis X. The first friction plate 43a is movable in the axial direction.

[0091] like Figure 3 As shown, the thickness of the specific friction plate 43c located at the innermost side in the axial direction among the second friction plates 43b is thicker than that of the other second friction plates 43b. The thickness of the second friction plates 43b other than the specific friction plate 43c is the same as that of the first friction plate 43a. The second friction plate 43b including the specific friction plate 43c is spline-engaged with the first pressing member 41 and the second pressing member 42. The second friction plate 43b can move in the axial direction.

[0092] The first pressing member 41 is arranged on the opposite side of the right side gear 34 in the differential case 31 across the right friction plate 43 in the axial direction, that is, on the right side of the right friction plate 43. The first pressing member 41 is in the shape of a cylinder whose cylindrical shaft is coaxial with the rotation axis X. The first pressing member 41 is not fixed relative to the differential case 31 and can rotate relative to the differential case 31. The first pressing member 41 has a disc-shaped first pressing portion 41a that presses the friction plate 43, a first inner cylinder portion 41b that extends from a radially inner portion of the first pressing portion 41a toward the axial inner side (here, the left side), and a first outer cylinder portion 41c that extends from a radially inner portion of the first pressing portion 41a toward the axial outer side (here, the right side).

[0093] The first pressing portion 41a is in contact with the first friction plate 43a located on the far right. The first pressing portion 41a clamps the friction plate 43 on the right together with the side gear 34 on the left. A first spacer 41d is arranged between the right surface of the first pressing portion 41a and the differential case 31. The first spacer 41d abuts against the inner surface of the differential case 31. The first pressing portion 41a is almost unable to move axially outward by the first spacer 41d. Therefore, the first pressing member 41 hardly moves axially outward. In addition, "almost not moving axially outward" includes a situation where there is no relative movement at all.

[0094] The first inner tube portion 41b extends straight in the axial direction. The left end of the first inner tube portion 41b is located on the right side of the gear portion 34a of the right side gear 34. The radially outer portion of the first inner tube portion 41b is spline-fitted with the second friction plate 43b including the specific friction plate 43c.

[0095] The first outer tube portion 41 c extends straight in the axial direction and is accommodated in a first recessed portion that is formed in the differential case 31 and is recessed to the right.

[0096] The first pressing member 41 has, on its inner peripheral surface, first outer spline teeth 45b of the first helical spline 45. The first outer spline teeth 45b are formed integrally with the inner peripheral surface of the first pressing member 41 in the axial direction.

[0097] The second pressing member 42 is arranged on the opposite side of the left side gear 34 in the differential case 31 across the left friction plate 43 in the axial direction, that is, on the left side of the left friction plate 43. The second pressing member 42 is in the shape of a cylinder whose cylindrical shaft is coaxial with the rotation axis X. The second pressing member 42 is not fixed relative to the differential case 31 and can rotate relative to the differential case 31. The second pressing member 42 has a disc-shaped second pressing portion 42a that presses the friction plate 43, a second inner cylinder portion 42b that extends from a radially inner portion of the second pressing portion 42a toward the axial inner side (here, the right side), and a second outer cylinder portion 42c that extends from a radially inner portion of the second pressing portion 42a toward the axial outer side (here, the left side).

[0098] The second pressing portion 42a is in contact with the second friction plate 43b located on the far left. The second pressing portion 42a clamps the friction plate 43 on the left together with the side gear 34 on the left. A second spacer 42d is arranged between the right surface of the second pressing portion 42a and the differential case 31. The second spacer 42d abuts against the inner surface of the differential case 31. The second pressing portion 42a is almost unable to move axially outward through the second spacer 42d. Therefore, the second pressing component 42 hardly moves axially outward. In addition, "hardly moves axially outward" includes a situation where there is no relative movement at all.

[0099] The second inner tube portion 42b extends straight in the axial direction. The right end of the second inner tube portion 42b is located to the left of the gear portion 34a of the left side gear 34. The radially outer portion of the second inner tube portion 42b is spline-fitted with the second friction plates 43b including the specific friction plates 43c.

[0100] The second outer tube portion 42c extends straight in the axial direction. The second outer tube portion 42c is accommodated in a second recessed portion, which is formed in the differential case 31 and is recessed to the left. The axial length of the second outer tube portion 42c is longer than the axial length of the first outer tube portion 41c. The radial thickness of the second outer tube portion 42c is thinner than the radial thickness of the first outer tube portion 41c. The axial length of the second recessed portion is longer than the axial length of the first recessed portion. The radial length of the second recessed portion is shorter than the radial length of the first recessed portion.

[0101] The second pressing member 42 has second outer spline teeth 46b of the second helical spline 46 on the inner peripheral surface. The second outer spline teeth 46b are formed integrally on the inner peripheral surface of the second pressing member 42 over the axial direction.

[0102] like Figure 2 and Figure 3 As shown, each disc spring 44 is respectively accommodated in a spring accommodation portion 34c, which is formed in each gear portion 34a of each side gear 34. Each spring accommodation portion 34c is provided at an axially outer portion of each gear portion 34a and is recessed toward the axial inner side. Each disc spring 44 presses a specific friction plate 43c toward the axial outer side.

[0103] (Operation of the differential limiting mechanism)

[0104] The differential limiting mechanism 40 adjusts the differential limiting force by adjusting the spline teeth 45a, 45b, 46a, 46b of the first helical spline 45 and the second helical spline 46. In the first embodiment, the spline teeth 45a, 45b, 46a, 46b are adjusted so as to reduce the differential limiting force when the vehicle 1 is accelerating and increase the differential limiting force when the vehicle 1 is decelerating. Figure 4 and Figure 5 The operation of the differential limiting mechanism 40 will be described. In addition, since only the force transmission direction is bilaterally symmetrical between the right differential limiting mechanism 40 and the left differential limiting mechanism 40, the operation of the right differential limiting mechanism 40 will be described in detail below, and the detailed description of the left differential limiting mechanism 40 will be omitted. In addition, when the vehicle 1 moves forward, it is assumed that the differential case 31 rotates clockwise when viewed from the right. In addition, in the following description, it is assumed that the vehicle 1 moves forward in a straight line, and the pinion 33 does not rotate around the pinion shaft 32.

[0105] Figure 4 The force input to the friction plate 43 when the vehicle 1 is accelerated is schematically shown. First, when the vehicle 1 moves forward, the pinion gear 33 rotates around the rotation axis X together with the differential case 31, and a meshing reaction force F1 with the pinion gear 33 is generated on the side gear 34. The meshing reaction force F1 is a force directed toward the axial outside. In addition, an initial torque F2 is generated from the disc spring 44. The initial torque F2 is a force that presses the specific friction plate 43c toward the axial outside, and also acts on the side gear 34.

[0106] When the vehicle 1 accelerates, a rotation torque is applied to the side gear 34 in the same direction as the rotation direction when moving forward. At this time, the meshing thrust F3 toward the axial outside acts on the first pressing member 41 via the first helical spline 45. Since the first pressing member 41 does not move relative to the differential case 31 toward the axial outside, even if the meshing thrust F3 is generated, the first pressing member 41 hardly leaves the friction plate 43. On the other hand, due to the reaction from the first helical spline 45, the meshing thrust reaction force F4 toward the axial inside acts on the side gear 34. The magnitude of the meshing thrust reaction force F4 is the same as the magnitude of the meshing thrust F3.

[0107] The meshing reaction force F1 and the meshing thrust reaction force F4 act on the friction plate 43 from the side gear 34. Therefore, if the axial outer side is set as the positive side and the axial inner side is set as the negative side, the force FA of the side gear 34 pressing the friction plate 43 during acceleration becomes:

[0108] FA=F1-F4.

[0109] Figure 5 The force input to the friction plate 43 during deceleration of the vehicle 1 is schematically shown. Since the vehicle 1 moves forward, a meshing reaction force F1 is generated similarly to during acceleration.

[0110] When the vehicle 1 is decelerating, a rotation torque is applied to the side gear 34 in the direction opposite to the rotation direction when the vehicle 1 is moving forward. At this time, the meshing thrust F5 toward the axial inner side acts on the first pressing member 41 via the first helical spline 45. On the other hand, the meshing thrust reaction force F6 toward the axial outer side acts on the side gear 34 by the reaction from the first helical spline 45. The magnitude of the meshing thrust reaction force F6 is the same as the magnitude of the meshing thrust F5.

[0111] The meshing reaction force F1 and the meshing thrust reaction force F6 act on the friction plate 43 from the side gear 34. Therefore, if the axial outer side is set as the positive side and the axial inner side is set as the negative side, the force FC of the side gear 34 pressing the friction plate 43 during deceleration becomes:

[0112] FC=F1+F6.

[0113] Thus, when the vehicle 1 is accelerated, the force of the side gear 34 pressing the friction plate 43 becomes smaller than when the vehicle 1 is decelerated. Since the first pressing member 41 and the second pressing member 42 hardly move axially outward, the force of the side gear 34 pressing the friction plate 43 is directly input to the friction plate 43. When the force input to the friction plate 43 becomes smaller, the dynamic friction force between the first friction plate 43a and the second friction plate 43b becomes smaller, so the differential limiting force becomes smaller. On the contrary, when the force input to the friction plate 43 becomes larger, the dynamic friction force between the first friction plate 43a and the second friction plate 43b becomes larger, so the differential limiting force becomes larger. Therefore, the differential limiting mechanism 40 reduces the differential limiting force when the vehicle 1 is accelerated, and on the other hand, increases the differential limiting force when the vehicle 1 is decelerated.

[0114] In the differential limiting mechanism 40 on the left side, the spline teeth 46a, 46b of the second helical spline 46 are opposite to the spline teeth 45a, 45b of the first helical spline 45, and the force transmission direction is symmetrical. The size and angle of the spline teeth 46a, 46b of the second helical spline 46 are the same as the spline teeth 45a, 45b of the first helical spline 45. The meshing thrust and meshing thrust reaction force generated by the second helical spline 46 are the same as the meshing thrust F3, F5 and meshing thrust reaction force F4, F6 generated by the first helical spline 45. In addition, the "same" mentioned here includes not only the case of strict consistency, but also the case of a difference that is substantially considered to be the same.

[0115] (Effects of Embodiment 1)

[0116] In the first embodiment, the rear differential device 30 is provided with a differential limiting mechanism 40, which includes: a plurality of friction plates 43, which are respectively arranged axially outward relative to each side gear 34; a first pressing member 41 and a second pressing member 42, which are cylindrical and coaxial with the rotation axis X, and are respectively arranged on the opposite side of the side gear 34 with the plurality of friction plates 43 interposed therebetween in the axial direction, and sandwich the plurality of friction plates 43 together with the side gear 34. The pair of side gears 34 each include a gear portion 34a meshing with the pinion gear 33, and a cylindrical portion 34b extending from a radially inner portion of the gear portion 34a toward the axially outer side and having a cylindrical axis coaxial with the rotation axis X. The outer circumference of the cylinder 34b of one side gear 34 meshes with the inner circumference of the first pressing member 41 via the first helical spline 45, and the outer circumference of the cylinder 34b of the other side gear 34 meshes with the inner circumference of the second pressing member 42 via the second helical spline 46. When the force toward the axial outside acts on the first pressing member 41 and the second pressing member 42 via the first helical spline 45 and the second helical spline 46, the force toward the axial inside is input to the side gear 34 by the reaction from the first helical spline 45 and the second helical spline 46. As a result, the force clamping the plurality of friction plates 43 is reduced, and the friction force acting between the plurality of friction plates 43 is reduced, so that the differential limiting force is reduced. On the other hand, when the force toward the axial inside acts on the first pressing member 41 and the second pressing member 42 via the first helical spline 45 and the second helical spline 46, the force toward the axial outside is input to the side gear 34 by the reaction from the first helical spline 45 and the second helical spline 46. As a result, since the force clamping the plurality of friction plates 43 increases, the friction force acting between the plurality of friction plates 43 increases, and thus the differential limiting force increases. Since the directions of the forces acting on the first helical spline 45 and the second helical spline 46 are opposite when the vehicle 1 is accelerating and when it is decelerating, the differential limiting force can be changed when the vehicle 1 is accelerating and when it is decelerating. In addition, by adjusting the angles of the spline teeth 45a, 45b of the first helical spline 45 and the spline teeth 46a, 46b of the second helical spline 46, the magnitude of the differential limiting force can be adjusted, and thus the magnitude of the differential limiting force can also be easily adjusted. Therefore, the differential limiting force can be adjusted with a simple structure.

[0117] In particular, in the present embodiment 1, the spline teeth 45a, 45b, 46a, 46b of the first helical spline 45 and the second helical spline 46 of the rear differential device 30 are formed so that when the vehicle 1 accelerates, a meshing thrust reaction force toward the axial inside is input to each side gear 34 respectively, and on the other hand, when the vehicle 1 decelerates, a meshing thrust reaction force toward the axial outside is input to each side gear 34 respectively.

[0118] That is, in the first embodiment, the vehicle 1 is not provided with a shaft such as a drive shaft that transmits a driving force in the front-rear direction of the vehicle. Conventionally, the differential limiting force is increased by the shaft, the stability of the rear part of the vehicle in the yaw direction is improved, and the straight-ahead stability of the vehicle is improved. In the case where the above-mentioned shaft is not provided as in the vehicle 1, it is necessary to improve the stability in the yaw direction by improving the stability in the straight-ahead direction by other mechanisms. At the rear of the vehicle 1, when the vehicle 1 is accelerated, the load applied to the rear wheel 3 increases due to the sinking of the rear part of the vehicle 1, so the stability in the yaw direction is high. On the other hand, when the vehicle 1 is decelerated, the load applied to the rear wheel 3 decreases due to the floating of the rear part of the vehicle 1, so the stability in the yaw direction decreases. Therefore, compared with the acceleration of the vehicle 1, it is required to increase the differential limiting force when the vehicle 1 is decelerated to improve the stability in the yaw direction of the rear part of the vehicle 1. In the first embodiment, when accelerating, the meshing thrust reaction force toward the axial inner side is input to each side gear 34, so the differential limiting force is reduced. On the other hand, during deceleration, the differential limiting force increases because the meshing thrust reaction force toward the axial outside is input to each side gear 34. Therefore, the differential limiting force becomes higher during deceleration of the vehicle 1 than during acceleration of the vehicle 1, thereby improving the straight-ahead stability of the vehicle 1.

[0119] In the first embodiment, the second friction plate 43b among the plurality of friction plates 43 is spline-fitted with the first pressing member 41 and the second pressing member 42, and the first friction plate 43a among the plurality of friction plates is fixed to the differential case 31. As a result, the portion that can be used for the first inner spline teeth 45a and the second inner spline teeth 46a can be expanded as much as possible in the cylinder portion 34b of the side gear 34. As a result, even if the cylinder portion 34b is shortened in the rotation axis direction, a sufficient meshing thrust reaction force can be input to the side gear 34 through the first helical spline 45 and the second helical spline 46, so that the rear differential device 30 can be made into a more compact structure.

[0120] In the first embodiment, a pair of disc springs 44 are further provided for inputting axially outward forces to the plurality of friction plates 43, and each gear portion 34a has a spring receiving portion 34c, which is provided at the axially outward portion and is recessed toward the axially inward portion and receives the disc spring 44. The disc spring 44 can be used to apply an initial torque to the friction plate 43. By arranging the disc spring 44 in the spring receiving portion 34c, the disc spring 44 can suppress the rear differential device 30 from expanding in the rotation axis direction. That is, a mechanism for applying the initial torque can be adopted, and the rear differential device 30 can be made compact. In addition, by receiving the disc spring 44 in the spring receiving portion 34c, the initial torque can be input to the friction plate 43 independently of the meshing thrust reaction force F1 between the pinion gear 33 and the side gear 34 and the meshing thrust reaction force via the first helical spline 45 and the second helical spline 46. Thus, the magnitude of the initial torque can be appropriately set.

[0121] (Implementation Method 2)

[0122] Hereinafter, Embodiment 2 will be described in detail with reference to the drawings. In the following description, the same reference numerals are given to the parts common to Embodiment 1, and the detailed description thereof will be omitted.

[0123] (Differential limiting mechanism)

[0124] In the second embodiment, the structure of the differential limiting mechanism 240 of the rear differential device 230 is different from that of the first embodiment.

[0125] like Figure 6 As shown, in the second embodiment, the side gear 234 has a spline tooth 234d for spline engagement with the second friction plate 43b. The second friction plate 43b is engaged with the spline tooth 234d. The thickness of each second friction plate 43b is the same. The first friction plate 43a is fixed so as not to rotate relative to the differential case 31 around the rotation axis X as in the above-mentioned first embodiment. The first friction plate 43a rotates around the rotation axis X together with the differential case 31. The thickness of each first friction plate 43a is the same.

[0126] The first inner spline teeth 245a of the first helical spline 245 are provided in the right cylindrical portion 234b axially outward of the spline teeth 234d. The second inner spline teeth 246a of the second helical spline 246 are provided in the left cylindrical portion 234b axially outward of the spline teeth 234d.

[0127] The first pressing member 241 has no first inner tube portion, and includes a first pressing portion 241 a and a first outer tube portion 241 c. The first outer spline teeth 245 b of the first helical spline 245 are formed integrally with the inner peripheral surface of the first pressing member 241 in the axial direction.

[0128] The second pressing member 242 has no second inner tube portion, and includes a second pressing portion 242a and a second outer tube portion 242c. The second outer spline teeth 246b of the second helical spline 246 are formed integrally over the inner peripheral surface of the second pressing member 242 in the axial direction.

[0129] The disc spring 44 is located radially outward of the spline teeth 234 d in the gear portion 234 a of the side gear 234 .

[0130] The first helical spline 245 and the second helical spline 246 are similar to the first embodiment, and the spline teeth 245a, 245b, 246a, and 246d are formed so that when the vehicle is accelerated, the force toward the axial inside is input from the first helical spline 245 and the second helical spline 246 to each side gear 234, and when the vehicle is decelerated, the force toward the axial outside is input from the first helical spline 245 and the second helical spline 246 to each side gear 234. In the second embodiment, the first helical spline 245 and the second helical spline 246 are a multi-thread structure with two or more threads.

[0131] (Effects of Embodiment 2)

[0132] In the second embodiment, similarly to the first embodiment, the force applied to the friction plate 43 can be changed during acceleration and deceleration of the vehicle by the first helical spline 245 and the second helical spline 246. Therefore, the differential limiting force can be adjusted with a simple structure.

[0133] According to this structure, since the second friction plate 43b is integrated with the side gear 234, a relatively large meshing thrust reaction force can be input, thereby making it possible to expand the range of the adjustable differential limiting force as much as possible.

[0134] (Other Embodiments)

[0135] The technology disclosed herein is not limited to the above-described embodiments, and can be replaced within the scope of the gist of the claims.

[0136] In the above-mentioned first and second embodiments, the differential limiting mechanisms 40 and 240 are provided on both sides in the rotation axis direction, but the present invention is not limited thereto, and the differential limiting mechanisms 40 and 240 may be provided only on one side in the rotation axis direction, that is, on either the right side or the left side.

[0137] In the above-mentioned embodiments 1 and 2, the differential limiting mechanism 40 and 240 is mounted on the rear differential device 30 and 230. Without limitation thereto, the differential limiting mechanism may be mounted on the front differential device 13. In this case, in contrast to the rear differential device 30 and 230, the spline teeth of the first helical spline and the second helical spline are formed such that when the vehicle is accelerated, a force toward the axial outer side is input from the first helical spline and the second helical spline to each side gear 34 and 234, respectively, and on the other hand, when the vehicle is decelerated, a force toward the axial inner side is input from the first helical spline and the second helical spline to each side gear 34 and 234, respectively.

[0138] In the first embodiment, each side gear 34 has a spring receiving portion 34 c for receiving the disc spring 44. However, the present invention is not limited thereto, and each side gear 34 may not have a spring receiving portion 34 c, and a disc spring 44 may be disposed between the axially outer portion of the gear portion 34 a of each side gear 34 and the friction plate 43.

[0139] In the first embodiment, the second friction plate 43b is splined with the first inner tube portion 41b of the first pressing member 41 and the second inner tube portion 42b of the second pressing member 42. However, the first inner tube portion 41b and the second inner tube portion 42b may be formed with comb teeth, and the second friction plate 43b may be held by the comb teeth.

[0140] The above embodiments are merely exemplary and should not be construed to limit the scope of the present invention. The scope of the present invention is defined by the scope of the claims, and all modifications and changes within the scope of equivalence of the claims are included in the scope of the present invention.

[0141] Possibility of Industrial Application

[0142] The technology disclosed herein is useful for a vehicle differential device and a vehicle having the vehicle differential device.

Claims

1. A vehicle differential device, mounted on a vehicle, characterized in that: have: a differential case that is rotated by a driving force from a driving source; a pair of side gears disposed in the differential case coaxially with a rotation axis of the differential case; a pinion gear meshing with both sides of the pair of side gears; and a differential limiting mechanism, the differential limiting mechanism being arranged on at least one side in the direction of the rotation axis, The differential limiting mechanism comprises: a plurality of friction plates arranged on the opposite side of the pinion gear relative to the side gear in the direction of the rotation axis; as well as a pressing member, the pressing member being arranged on the opposite side of the side gear across the plurality of friction plates in the direction of the rotation axis and clamping the plurality of friction plates together with the side gear; The side gear located on the one side in the direction of the rotation axis has: a gear portion meshing with the pinion gear; and a cylindrical portion extending from a radially inner portion of the gear portion relative to the rotating shaft toward a side opposite to the pinion gear, and having a cylindrical axis coaxial with the rotating shaft, The outer peripheral portion of the cylindrical portion and the inner peripheral portion of the pressing member are meshed with each other via a helical spline.

2. The vehicle differential device according to claim 1, characterized in that: A portion of the plurality of friction plates is spline-engaged with the pressing member, The remaining portions of the plurality of friction plates are fixed to the differential case.

3. The vehicle differential device according to claim 1, characterized in that: A portion of the plurality of friction plates is spline-engaged with the cylinder portion, The remaining portions of the plurality of friction plates are fixed to the differential case.

4. The vehicle differential device according to claim 1, characterized in that: The differential limiting mechanism further includes a disc spring that inputs a force toward the pressing member side in the direction of the rotation axis to the plurality of friction plates. The gear portion has a spring housing portion which is provided at a portion on the friction plate side in the rotation axis direction and is recessed toward a side opposite to the friction plate in the rotation axis direction, and houses the disc spring.

5. The vehicle differential device according to claim 1, characterized in that: The differential limiting mechanisms are respectively arranged on both sides in the direction of the rotation axis.

6. The vehicle differential device according to any one of claims 1 to 5, characterized in that: The vehicle is a rear-wheel drive or all-wheel drive vehicle, The vehicle differential device is used for differential control of rear wheels of the vehicle.

7. The vehicle differential device according to claim 6, characterized in that: The spline teeth of the helical spline are formed such that when the vehicle accelerates, force is input from the helical spline to the side gear on a side away from the friction plate, and when the vehicle decelerates, force is input from the helical spline to the side gear on a side approaching the friction plate.

8. A vehicle, characterized in that: have: A front drive unit, the front drive unit driving the front wheels to rotate; as well as A rear drive unit capable of driving the rear wheels to rotate independently of the front drive unit, and comprising the vehicle differential device according to claim 7.

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