Vehicle differential and vehicle

Abstract

To provide a vehicle differential that allows adjustment of differential limiting torque with a simple configuration. [Solution] The rear differential 30 comprises a differential case 40 that rotates in response to the driving force of a rear drive motor 21, a pair of side gears 60 coaxial with the rotation axis O of the differential case, a pinion gear 52 that meshes with both of the pair of side gears, and a differential limiting mechanism 70 that generates a differential limiting torque T that limits the differential of the rear wheels 3 of the vehicle 1. The differential limiting mechanism has a plurality of friction plates 80 that are pressed axially by the side gears. Of the friction plates, the case-side friction plate 81 is provided on the differential case, and the gear-side friction plate 82 is provided on the side gears. The case-side friction plate and the gear-side friction plate are arranged side by side in the axial direction and generate a differential limiting torque by sliding against each other. The first sliding diameter EA between the first case-side friction plate 81A and the first gear-side friction plate 82A and the second sliding diameter EB between the second case-side friction plate 81B and the second gear-side friction plate 82B are different from each other.

Description

Technical Field

[0001] The present disclosure relates to a differential device for a vehicle and a vehicle.

Background Art

[0002] A differential device for a vehicle provided with a differential limiting mechanism is known. For example, the differential device for a vehicle disclosed in Patent Document 1 includes a differential case that is rotationally driven 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 fastened by receiving the meshing reaction force of the side gears, and limits the differential of the differential gear mechanism, and a cam mechanism that is provided between the clutch member and the side gear and presses the cone clutch by receiving the driving force.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the differential limiting torque by the differential limiting mechanism is large, the straight-ahead stability of the vehicle is improved, but the vehicle becomes difficult to turn. When the differential limiting torque by the differential limiting mechanism is small, the vehicle becomes easy to turn, but the straight-ahead stability of the vehicle decreases. In a differential device for a vehicle, it is desired to adjust the differential limiting torque by the differential limiting mechanism in order to balance the straight-ahead stability of the vehicle and the ease of turning of the vehicle.

[0005] The present disclosure aims to provide a differential device for a vehicle capable of adjusting the differential limiting torque with a simple configuration.

Means for Solving the Problems

[0006] The vehicle differential according to this disclosure is a vehicle differential mounted on a vehicle, comprising: a differential case that rotates in response to the driving force of a drive source; a pair of side gears disposed within the differential case and coaxial with the rotation axis of the differential case; a pinion gear disposed within the differential case and meshing with both of the pair of side gears; and a differential limiting mechanism that generates a differential limiting torque to limit the differential of the vehicle's wheels, wherein the differential limiting mechanism has a plurality of friction plates pressed by the side gears in the axial direction from which the rotation axis extends, and a portion of the plurality of friction plates is provided on the differential case. The case-side friction plates consist of a plurality of case-side friction plates, the other parts of which are gear-side friction plates provided on the side gear, the case-side friction plates and the gear-side friction plates are arranged side by side in the axial direction and generate the differential limiting torque by sliding against each other, the case-side friction plates include a first case-side friction plate and a second case-side friction plate, the gear-side friction plates include a first gear-side friction plate and a second gear-side friction plate, and the first sliding diameter between the first case-side friction plate and the first gear-side friction plate and the second sliding diameter between the second case-side friction plate and the second gear-side friction plate are different from each other.

[0007] The first sliding diameter between the first case-side friction plate and the first gear-side friction plate, and the second sliding diameter between the second case-side friction plate and the second gear-side friction plate, are made to be different from each other. If the first sliding diameter is smaller than the second sliding diameter, the differential limiting torque will be smaller compared to the case where the first sliding diameter is equal to the second sliding diameter. If the first sliding diameter is larger than the second sliding diameter, the differential limiting torque will be larger compared to the case where the first sliding diameter is equal to the second sliding diameter.

[0008] In this way, by adjusting the first and second sliding diameters, the differential limiting torque for limiting the differential movement of the vehicle's wheels can be adjusted.

[0009] In summary, a vehicle differential gear capable of adjusting the differential limiting torque can be provided with a simple configuration.

[0010] In one embodiment, the first inner diameter of the first case-side friction plate and the second inner diameter of the second case-side friction plate are different from each other.

[0011] The first and second sliding diameters can be easily adjusted.

[0012] In one embodiment, the first outer diameter of the first gear-side friction plate and the second outer diameter of the second gear-side friction plate are different from each other.

[0013] The first and second sliding diameters can be easily adjusted.

[0014] In one embodiment, the differential limiting mechanism includes a first differential limiting mechanism provided on one side of the pinion gear in the axial direction, and a second differential limiting mechanism provided on the other side of the pinion gear in the axial direction, wherein the first differential limiting mechanism has a first case-side friction plate and a first gear-side friction plate, and a second case-side friction plate and a second gear-side friction plate, and in the first differential limiting mechanism, the first sliding diameter between the first case-side friction plate and the first gear-side friction plate and the second sliding diameter between the second case-side friction plate and the second gear-side friction plate are different from each other.

[0015] The differential limiting torque for the wheel corresponding to the first differential limiting mechanism can be adjusted.

[0016] In one embodiment, the differential limiting mechanism includes a first differential limiting mechanism provided on one side of the pinion gear in the axial direction, and a second differential limiting mechanism provided on the other side of the pinion gear in the axial direction, wherein the first differential limiting mechanism has a first case-side friction plate and a first gear-side friction plate, and the second differential limiting mechanism has a second case-side friction plate and a second gear-side friction plate, wherein the first sliding diameter between the first case-side friction plate and the first gear-side friction plate in the first differential limiting mechanism and the second sliding diameter between the second case-side friction plate and the second gear-side friction plate in the second differential limiting mechanism are different from each other.

[0017] The differential limiting torque for the right wheel and the differential limiting torque for the left wheel can be made different from each other.

[0018] In one embodiment, the side gear has a gear body that meshes with the pinion gear and a pressing body that sandwiches a plurality of the friction plates together with the gear body, and the gear body and the pressing body are engaged with each other, and the gear-side friction plate is provided on the pressing body.

[0019] The plurality of friction plates can be easily pressed by the gear body and the pressing body.

[0020] In one embodiment, the vehicle is rear-wheel drive or all-wheel drive and is used for differential control of the rear wheels of the vehicle.

[0021] By adjusting the differential limiting torque for the rear wheels, the straight-line stability of the vehicle can be improved.

[0022] The vehicle according to the present disclosure includes a front drive unit that rotates the front wheels and a rear drive unit that rotates the rear wheels independently of the front drive unit and has the differential device for the vehicle.

[0023] A vehicle with improved straight-line stability by adjusting the differential limiting torque for the rear wheels can be provided.

Effects of the Invention

[0024] According to the present disclosure, a differential device for a vehicle capable of adjusting the differential limiting torque with a simple configuration can be provided.

Brief Description of the Drawings

[0025] [Figure 1] FIG. 1 schematically shows a vehicle according to the first embodiment. [Figure 2] FIG. 2 shows a cross-sectional view of the rear differential device according to the first embodiment as viewed in the front-rear direction. [Figure 3]Figure 3 shows an enlarged cross-sectional view of the friction plate in region III of the differential limiting mechanism according to the first embodiment. [Figure 4] Figure 4 shows the case-side friction plate according to the first embodiment, viewed from the direction of arrow IV. [Figure 5] Figure 5 shows the gear-side friction plate according to the first embodiment, viewed from the direction of arrow V. [Figure 6] Figure 6 shows a conceptual diagram of the sliding diameter between the friction plates according to the first embodiment. [Figure 7] Figure 7 shows a conceptual diagram of the sliding diameter between friction plates according to the second embodiment. [Figure 8] Figure 8 shows a conceptual diagram of the sliding diameter between the friction plates according to the third embodiment. [Figure 9] Figure 9 shows the rear differential according to the fourth embodiment. [Modes for carrying out the invention]

[0026] The embodiments of this disclosure will be described in detail below with reference to the drawings. The following description of preferred embodiments is illustrative in nature and is not intended to limit the disclosure, its applications or uses in any way.

[0027] In the following explanation, front, rear, left, right, up, and down are based on the perspective of an occupant riding in vehicle 1.

[0028] <First Embodiment> The first embodiment will be described.

[0029] (vehicle) Figure 1 shows a schematic diagram of vehicle 1. In this example, vehicle 1 is an electric vehicle. As shown in Figure 1, vehicle 1 comprises front wheels 2, rear wheels 3, a front drive unit 10, and a rear drive unit 20. Vehicle 1 is an all-wheel drive system in which both the front wheels 2 and the rear wheels 3 are driven. Vehicle 1 can rotate the front wheels 2 and the rear wheels 3 independently of each other.

[0030] The front drive unit 10 is located at the front of the vehicle 1. The rear drive unit 20 is located at the rear of the vehicle 1. The front drive unit 10 rotates the front wheels 2 independently of the rear drive unit 20. The rear drive unit 20 rotates the rear wheels 3 independently of the front drive unit 10. The vehicle 1 is not provided with a shaft (such as a propeller shaft) that transmits driving force in the front-rear direction.

[0031] The front drive unit 10 includes a front drive motor 11, a front reduction gear 12, and a front differential 13. The front drive motor 11 is the drive source for rotating the front wheels 2. The rotation of the front drive motor 11 is reduced by the front reduction gear 12 and then transmitted to the front differential 13. The front differential 13 is connected to the left and right front wheels 2 via a front drive shaft 14. The front differential 13 differentially rotates the left and right front wheels 2 according to the driving state of the vehicle 1.

[0032] The rear drive unit 20 includes a rear drive motor 21, a rear reduction gear 22, and a rear differential 30. The arrangement of the rear drive unit 20 is symmetrical in the front-rear direction with respect to the arrangement of the front drive unit 10. The rear drive motor 21 is a drive source for rotating the rear wheels 3. The rear drive motor 21 is an example of a drive source. The rotation of the rear drive motor 21 is reduced by the rear reduction gear 22 and then transmitted to the rear differential 30. The rear differential 30 is an example of a differential for a vehicle. The rear differential 30 is connected to the left and right rear wheels 3 via a rear drive shaft 24. The rear differential 30 differentials the left and right rear wheels 3 according to the driving state of the vehicle 1. The rear wheels 3 are an example of wheels.

[0033] In this embodiment, particular improvements have been made to the rear differential 30, so the rear differential 30 will be described in detail below.

[0034] (Rear differential) Figure 2 shows a cross-sectional view of the rear differential 30 in the front-rear direction. The rear differential 30 is used for differential control of the left and right rear wheels 3 of the vehicle 1. As shown in Figure 2, the rear differential 30 is mounted at the rear of the vehicle 1. The rear differential 30 comprises a differential case 40, a pinion shaft 51, a pair of pinion gears 52, a pair of side gears 60, and a differential limiting mechanism 70.

[0035] The differential case 40 rotates in response to the driving force of the rear drive motor 21, which acts as the drive source. The driving force of the rear drive motor 21 is transmitted to the differential case 40 of the rear differential gear 30 via the rear reduction gear 22. The differential case 40 rotates around the rotation axis O, receiving the driving force from the rear reduction gear 22 via the final driven gear (not shown). The rotation axis O extends in the vehicle width direction (left-right direction).

[0036] In the following explanation, axial direction X refers to the direction in which the axis of rotation O extends. Axial direction X is the vehicle width direction (left-right direction). The side of axial direction X that is on the side of the central axis C (described later) is called the inner side of axial direction X. The side of axial direction X that is opposite to the central axis C (described later) is called the outer side of axial direction X. Radial direction R refers to the direction perpendicular to the axis of rotation O. Radial direction R includes the vertical and longitudinal directions. The side of radial direction R that is on the side of the axis of rotation O is called the inner side of radial direction R. The side of radial direction R that is opposite to the axis of rotation O is called the outer side of radial direction R.

[0037] The pinion shaft 51 is fixed inside the differential case 40. The central axis C of the pinion shaft 51 extends in the radial direction R perpendicular to the axis of rotation O. The central axis C of the pinion shaft 51 extends in the radial direction R so as to straddle the axis of rotation O. The axis of rotation O passes through the center of the pinion shaft 51 in the longitudinal direction. The pinion shaft 51 rotates together with the differential case 40 around the axis of rotation O when the differential case 40 rotates around the axis of rotation O. The pinion shaft 51 rotates around the axis of rotation O with its central point in the longitudinal direction. Both ends of the pinion shaft 51 in the longitudinal direction pivot around the axis of rotation O.

[0038] A pair (two) of pinion gears 52 are arranged inside the differential case 40. The pinion gears 52 are attached to both ends of the pinion shaft 51 in the longitudinal direction (radial direction R). One pinion gear 52 is attached to one end of the pinion shaft 51. The other pinion gear 52 is attached to the other end of the pinion shaft 51. One pinion gear 52 and the other pinion gear 52 are positioned on opposite sides of each other in the radial direction R, with the rotation axis O in between.

[0039] The pinion gear 52 is rotatable around the central axis C of the pinion shaft 51 relative to the pinion shaft 51. When the differential case 40 rotates around the axis O, the pinion gear 52 pivots together with the pinion shaft 51 around the axis O. The pivot radius of one pinion gear 52 relative to the axis O is the same as the pivot radius of the other pinion gear 52 relative to the axis O.

[0040] The pinion gear 52 meshes with both of the pair of side gears 60, which will be described later. A washer 53 is positioned between the pinion gear 52 and the differential case 40 in the radial direction R.

[0041] A pair (two) of side gears 60 are arranged inside the differential case 40. The side gears 60 are roughly cylindrical in shape. The cylindrical shaft of the side gear 60 is coaxial with the rotation axis O of the differential case 40. The side gears 60 are positioned axially outward X from the pinion gear 52. One side gear 60 and the other side gear 60 are arranged mirror-symmetrically with respect to a plane that passes through the central axis C and is perpendicular to the rotation axis O.

[0042] The pair of side gears 60 mesh with the pinion gear 52. The pinion gear 52 meshes with both of the pair of side gears 60.

[0043] The side gear 60 is not fixed to the differential case 40. The side gear 60 is rotatable around the rotation axis O relative to the differential case 40.

[0044] The side gear 60 includes a gear body 61 and a pressing body 62. The gear body 61 includes a gear portion 61a and a cylindrical portion 61b. The gear portion 61a of the gear body 61 in the side gear 60 meshes with the pinion gear 52. The cylindrical portion 61b extends from the radially inner portion R of the gear portion 61a toward the opposite side of the pinion gear 52 in the axial direction X (outward in the axial direction X).

[0045] The rear drive shaft 24 (see Figure 1) is fastened to the inner circumferential surface of the gear portion 61a and the inner circumferential surface of the cylindrical portion 61b. An inner spline 64 (for example, a helical spline) is formed on the outer circumferential surface of the cylindrical portion 61b (see Figure 3).

[0046] The pressing body 62 is positioned axially X outward from the gear portion 61a of the gear body 61. The pressing body 62 is positioned radially R outward from the cylindrical portion 61b of the gear body 61. The pressing body 62 is positioned on the opposite side of the gear portion 61a of the gear body 61 in the axial direction X, with multiple friction plates 80 in the differential limiting mechanism 70 described later in between.

[0047] The pressing body 62 is substantially cylindrical. The cylindrical shaft of the pressing body 62 is coaxial with the rotation axis O of the differential case 40. The pressing body 62 includes a pressing portion 62a, an inner cylindrical portion 62b, and an outer cylindrical portion 62c. The pressing portion 62a of the pressing body 62, together with the gear portion 61a of the gear body 61, clamps a plurality of friction plates 80 in the axial direction X. The plurality of friction plates 80 are pressed in the axial direction X by the pressing portion 62a of the pressing body 62 and the gear portion 61a of the gear body 61. The pressing portion 62a is disc-shaped with a hole in the center. The pressing portion 62a is in contact with the outermost friction plate 80 in the axial direction X. The radially R outer portion of the end face of the gear portion 61a of the gear body 61, which is axially X outer, is in contact with the innermost friction plate 80 in the axial direction X. A spacer 62d is positioned between the outer surface of the pressing portion 62a in the axial direction X and the differential case 40.

[0048] The inner cylindrical portion 62b extends radially inward from the radially R-inward portion of the pressing portion 62a. A disc spring 62e is positioned between the axially X-inward end of the inner cylindrical portion 62b and the recess in the radially R-inward portion of the axially X-outward end face of the gear portion 61a of the gear body 61.

[0049] The outer cylindrical portion 62c extends radially outward from the radially inner portion R of the pressing portion 62a. The outer cylindrical portion 62c is housed in a recess formed within the differential case 40.

[0050] An outer spline 63 (e.g., a helical spline) is formed on the inner circumferential surface of the pressing body 62 (see Figure 3). As described above, an inner spline 64 (e.g., a helical spline) is formed on the outer circumferential surface of the cylindrical portion 61b of the gear body 61.

[0051] The gear body 61 and the pressing body 62 are engaged with each other. More specifically, the inner spline 64 on the outer circumferential surface of the cylindrical portion 61b of the gear body 61 and the outer spline 63 on the inner circumferential surface of the pressing body 62 are spline-fitted with each other. The pressing body 62 is restricted from rotating around the rotation axis O relative to the gear body 61. The pressing body 62 is permitted to move in the axial direction X relative to the gear body 61.

[0052] (Friction plate of differential limiting mechanism) Figure 3 shows an enlarged cross-sectional view of the friction plate 80 of the differential limiting mechanism 70 in region III. Figure 4 shows the case-side friction plate 81, which will be described later, as seen by arrow IV. Figure 5 shows the gear-side friction plate 82, which will be described later, as seen by arrow V.

[0053] As shown in Figure 3, the differential limiting mechanism 70 generates a differential limiting torque T to limit the differential between the left and right rear wheels 3 of the vehicle 1. The differential limiting mechanism 70 has a plurality of friction plates 80. The friction plates 80 are plate-shaped with the axial direction X as the thickness direction. When viewed in the axial direction X, the friction plates 80 are ring-shaped with a hole in the center. The axis of the friction plates 80 is coaxial with the rotation axis O of the differential case 40. The plurality of friction plates 80 are arranged side by side in the axial direction X.

[0054] Multiple friction plates 80 are pressed in the axial direction X by the side gear 60. The multiple friction plates 80 are positioned in the axial direction X between the gear portion 61a of the gear body 61 and the pressing portion 62a of the pressing body 62. The multiple friction plates 80 are clamped in the axial direction X by the gear portion 61a of the gear body 61 and the pressing portion 62a of the pressing body 62, and are pressed in the axial direction X.

[0055] A portion of the multiple friction plates 80 are multiple case-side friction plates 81. The remaining portion of the multiple friction plates 80 are multiple gear-side friction plates 82.

[0056] As shown in Figures 3 and 4, the case-side friction plate 81 is provided in the differential case 40. The differential case 40 has a cylindrical wall portion 41 formed therein. The cylindrical wall portion 41 is circular when viewed in the axial direction X. The cylindrical wall portion 41 extends in the axial direction X. The inner circumferential surface 41a of the cylindrical wall portion 41 is provided with a plurality of grooves 41b that are recessed radially outward R. The grooves 41b extend in the axial direction X. The plurality of grooves 41b are arranged in a line around the rotation axis O.

[0057] The outer circumferential surface 81a of the case-side friction plate 81 is provided with a plurality of protrusions 81b that project radially outward in the direction R. The outer circumferential surface 81a of the case-side friction plate 81 faces the inner circumferential surface 41a of the cylindrical wall portion 41. The protrusions 81b of the case-side friction plate 81 are fitted into grooves 41b of the cylindrical wall portion 41.

[0058] The case-side friction plate 81 is restricted from rotating around the rotation axis O relative to the cylindrical wall portion 41 of the differential case 40. The case-side friction plate 81 is permitted to move in the axial direction X relative to the cylindrical wall portion 41 of the differential case 40.

[0059] As shown in Figures 3 and 5, the gear-side friction plate 82 is provided on the side gear 60. Specifically, the gear-side friction plate 82 is provided on the pressing body 62 of the side gear 60. The outer circumferential surface 62f of the inner cylindrical portion 62b of the pressing body 62 in the side gear 60 is provided with a plurality of grooves 62g that are recessed radially R inward. The grooves 62g extend in the axial direction X. The plurality of grooves 62g are arranged in a line around the rotation axis O.

[0060] The inner circumferential surface 82a of the gear-side friction plate 82 is provided with a plurality of protrusions 82b that project radially inward in the direction R. The inner circumferential surface 82a of the gear-side friction plate 82 faces the outer circumferential surface 62f of the inner cylindrical portion 62b of the pressing body 62. The protrusions 82b of the gear-side friction plate 82 are fitted into grooves 62g of the inner cylindrical portion 62b of the pressing body 62.

[0061] The gear-side friction plate 82 is restricted from rotating around the rotation axis O relative to the pressing body 62 of the side gear 60. The gear-side friction plate 82 is permitted to move in the axial direction X relative to the pressing body 62 of the side gear 60.

[0062] The inner diameter of the case-side friction plate 81 is smaller than the outer diameter of the gear-side friction plate 82. The outer diameter of the gear-side friction plate 82 is larger than the inner diameter of the case-side friction plate 81. The radially inner portion of the case-side friction plate 81 and the radially outer portion of the gear-side friction plate 82 slide against each other around the rotation axis O. Note that the outer diameters of the case-side friction plate 81 and the gear-side friction plate 82 may be the same, and the inner diameters of the case-side friction plate 81 and the gear-side friction plate 82 may be the same.

[0063] As shown in Figure 3, the specific friction plate 80a (one gear-side friction plate 82 in this example) that is furthest inward in the axial direction X of the friction plates 80 is thicker than the other friction plates 80. The specific friction plate 80a contacts the gear portion 61a of the gear body 61 and the disc spring 62e. The other friction plates 80, excluding the specific friction plate 80a, are all the same thickness.

[0064] The case-side friction plate 81 and the gear-side friction plate 82 are arranged alternately in the axial direction X. The case-side friction plate 81 and the gear-side friction plate 82 slide against each other around the rotation axis O, generating a differential limiting torque T (see Figures 4 and 5). The differential limiting torque T will be described later.

[0065] Returning to Figure 2, the differential limiting mechanism 70 includes a first differential limiting mechanism 71 and a second differential limiting mechanism 72. The first differential limiting mechanism 71 corresponds to the right rear wheel 3. The second differential limiting mechanism 72 corresponds to the left rear wheel 3. The first differential limiting mechanism 71 is located on one side of the axial direction X (right side in Figure 2) relative to the pinion gear 52. The second differential limiting mechanism 72 is located on the other side of the axial direction X (left side in Figure 2) relative to the pinion gear 52.

[0066] In this example, the first differential limiting mechanism 71 and the second differential limiting mechanism 72 are arranged mirror-symmetrically with respect to a plane that passes through the central axis C and is perpendicular to the axis of rotation O.

[0067] (Sliding diameter between friction plates) Figure 6 shows a conceptual diagram of the sliding diameter between the friction plates 80. For clarity, the thickness of a specific friction plate 80a is shown to be the same as the thickness of the other friction plates 80. Also for clarity, compared to Figure 3, the inner and outer diameters of the case-side friction plate 81 are shown larger, and the inner and outer diameters of the gear-side friction plate 82 are shown smaller. The case-side friction plate 81 includes the first case-side friction plate 81A and the second case-side friction plate 81B. The gear-side friction plate 82 includes the first gear-side friction plate 82A and the second gear-side friction plate 82B.

[0068] In this example, there are eight friction plates 80 (including a specific friction plate 80a). There are four case-side friction plates 81 and four gear-side friction plates 82. Of the four case-side friction plates 81, there is one first case-side friction plate 81A and three second case-side friction plates 81B. Of the four gear-side friction plates 82, there is one first gear-side friction plate 82A and three second gear-side friction plates 82B.

[0069] The first case-side friction plate 81A and the first gear-side friction plate 82A are adjacent to each other in the axial direction X. The first case-side friction plate 81A and the first gear-side friction plate 82A slide against each other around the rotation axis O on the first sliding surface 83A. The second case-side friction plate 81B and the second gear-side friction plate 82B are adjacent to each other in the axial direction X. The second case-side friction plate 81B and the second gear-side friction plate 82B slide against each other around the rotation axis O on the second sliding surface 83B.

[0070] As described above, the friction plate 80 is ring-shaped with a hole in the center when viewed in the axial direction X. The first case-side friction plate 81A has a first inner diameter dA. The second case-side friction plate 81B has a second inner diameter dB. The first gear-side friction plate 82A has a first outer diameter DA. The second gear-side friction plate 82B has a second outer diameter DB. Note that the inner diameter and outer diameter are based on the axis of rotation O and may be defined as diameter or radius.

[0071] The first inner diameter dA of the first case-side friction plate 81A and the second inner diameter dB of the second case-side friction plate 81B are different from each other. In this example, the first inner diameter dA of the first case-side friction plate 81A is smaller than the second inner diameter dB of the second case-side friction plate 81B.

[0072] The first outer diameter DA of the first gear-side friction plate 82A and the second outer diameter DB of the second gear-side friction plate 82B are the same.

[0073] The first sliding diameter EA between the first case-side friction plate 81A and the first gear-side friction plate 82A, and the second sliding diameter EB between the second case-side friction plate 81B and the second gear-side friction plate 82B, are different from each other. The first sliding diameter EA is smaller than the second sliding diameter EB.

[0074] The first sliding diameter EA corresponds to the center position of the radial R on the first sliding surface 83A. The first sliding diameter EA corresponds to the midpoint between the inner end and the outer end of the radial R on the first sliding surface 83A. The first sliding diameter EA is the median value between the first inner diameter dA and the first outer diameter DA.

[0075] The second sliding diameter EB corresponds to the center position of the radial R on the second sliding surface 83B. The second sliding diameter EB corresponds to the midpoint between the inner and outer ends of the radial R on the second sliding surface 83B. The second sliding diameter EB is the midpoint between the second inner diameter dB and the second outer diameter DB.

[0076] The first sliding diameter EA and the second sliding diameter EB are also called the effective sliding diameters, respectively.

[0077] Here, the differential limiting torque T acts in the circumferential direction around the rotation axis O (see Figures 4 and 5). The differential limiting torque T is obtained by multiplying the friction force acting on the sliding surfaces (first sliding surface 83A, second sliding surface 83B) between the case-side friction plate 81 (first case-side friction plate 81A, second case-side friction plate 81B) and the gear-side friction plate 82 (first gear-side friction plate 82A, second gear-side friction plate 82B), the number of such sliding surfaces, and the sliding diameters (first sliding diameter EA, second sliding diameter EB) by each other.

[0078] Reducing the sliding diameter (first sliding diameter EA, second sliding diameter EB) reduces the differential limiting torque T. Increasing the sliding diameter (first sliding diameter EA, second sliding diameter EB) increases the differential limiting torque T.

[0079] In this example, since the first sliding diameter EA is smaller than the second sliding diameter EB, the differential limiting torque T is smaller compared to the case where the first sliding diameter EA is equal to the second sliding diameter EB. If the first sliding diameter EA were larger than the second sliding diameter EB, the differential limiting torque T would be larger compared to the case where the first sliding diameter EA is equal to the second sliding diameter EB.

[0080] In this example, the first differential limiting mechanism 71 and the second differential limiting mechanism 72 of the differential limiting mechanism 70 have the same configuration. The first differential limiting mechanism 71 has a first case-side friction plate 81A and a first gear-side friction plate 82A, and a second case-side friction plate 81B and a second gear-side friction plate 82B. The second differential limiting mechanism 72 has a first case-side friction plate 81A and a first gear-side friction plate 82A, and a second case-side friction plate 81B and a second gear-side friction plate 82B.

[0081] In the first differential limiting mechanism 71, the first sliding diameter EA between the first case-side friction plate 81A and the first gear-side friction plate 82A and the second sliding diameter EB between the second case-side friction plate 81B and the second gear-side friction plate 82B are different from each other. In the second differential limiting mechanism 72, the first sliding diameter EA between the first case-side friction plate 81A and the first gear-side friction plate 82A and the second sliding diameter EB between the second case-side friction plate 81B and the second gear-side friction plate 82B are different from each other.

[0082] (Effects and Benefits) In the rear differential 30, the first sliding diameter EA between the first case-side friction plate 81A and the first gear-side friction plate 82A, and the second sliding diameter EB between the second case-side friction plate 81B and the second gear-side friction plate 82B are made different from each other. If the first sliding diameter EA is smaller than the second sliding diameter EB, the differential limiting torque T is smaller compared to the case where the first sliding diameter EA is equal to the second sliding diameter EB. If the first sliding diameter EA is larger than the second sliding diameter EB, the differential limiting torque T is larger compared to the case where the first sliding diameter EA is equal to the second sliding diameter EB.

[0083] In this way, the rear differential gear 30 can adjust the differential limiting torque T for limiting the differential of the rear wheels 3 of the vehicle 1 by adjusting the first sliding diameter EA and the second sliding diameter EB.

[0084] In summary, a rear differential 30 with an adjustable differential limiting torque T can be provided with a simple configuration.

[0085] By adjusting the differential limiting torque T for the rear wheels 3 of vehicle 1 using the rear differential 30, the balance between the straight-line stability of vehicle 1 and its ability to turn can be adjusted.

[0086] Since only the first sliding diameter EA and the second sliding diameter EB need to be changed, the number of types of parts in the rear differential 30 can be reduced.

[0087] The first inner diameter dA of the first case-side friction plate 81A and the second inner diameter dB of the second case-side friction plate 81B are different from each other. The first sliding diameter EA and the second sliding diameter EB can be easily adjusted.

[0088] The differential limiting torque T for the right rear wheel 3 on the side corresponding to the first differential limiting mechanism 71 can be adjusted. Similarly, the differential limiting torque T for the left rear wheel 3 on the side corresponding to the second differential limiting mechanism 72 can be adjusted.

[0089] The side gear 60 has a gear body 61 that meshes with the pinion gear 52, and a pressing body 62 that clamps a plurality of friction plates 80 together with the gear body 61. The gear body 61 and the pressing body 62 make it easier to press the plurality of friction plates 80.

[0090] Vehicle 1 is an all-wheel drive vehicle, and the rear differential 30 is used for differential control of the rear wheels 3. By adjusting the differential limiting torque T for the rear wheels 3, the straight-line stability of vehicle 1 can be improved.

[0091] Vehicle 1 comprises a front drive unit 10 that rotates the front wheels 2, and a rear drive unit 20 that rotates the rear wheels 3 independently of the front drive unit 10 and has a rear differential 30. By adjusting the differential limiting torque T for the rear wheels 3, a vehicle 1 with improved straight-line stability can be provided.

[0092] <Second Embodiment> A second embodiment will now be described. In the following description, components similar to those in the above embodiment will be denoted by the same reference numerals, and detailed explanations will be omitted. Figure 7 is a conceptual diagram showing the sliding diameter between the friction plates 80.

[0093] The first inner diameter dA of the first case-side friction plate 81A and the second inner diameter dB of the second case-side friction plate 81B are the same. The first outer diameter DA of the first gear-side friction plate 82A and the second outer diameter DB of the second gear-side friction plate 82B are different. In this example, the first outer diameter DA of the first gear-side friction plate 82A is larger than the second outer diameter DB of the second gear-side friction plate 82B.

[0094] The first sliding diameter EA between the first case-side friction plate 81A and the first gear-side friction plate 82A, and the second sliding diameter EB between the second case-side friction plate 81B and the second gear-side friction plate 82B, are different from each other. The first sliding diameter EA is larger than the second sliding diameter EB.

[0095] The other components are the same as those in the above embodiment.

[0096] The first sliding diameter EA and the second sliding diameter EB can be easily adjusted.

[0097] <Third Embodiment> A third embodiment will now be described. In the following description, components similar to those in the above embodiments will be denoted by the same reference numerals, and detailed explanations will be omitted. Figure 8 shows a conceptual diagram of the sliding diameter between the friction plates 80.

[0098] Of the differential limiting mechanisms 70, the first differential limiting mechanism 71 and the second differential limiting mechanism 72 have different configurations.

[0099] The first differential limiting mechanism 71 has a first case-side friction plate 81A and a first gear-side friction plate 82A. The second differential limiting mechanism 72 has a second case-side friction plate 81B and a second gear-side friction plate 82B.

[0100] The first sliding diameter EA between the first case-side friction plate 81A and the first gear-side friction plate 82A in the first differential limiting mechanism 71, and the second sliding diameter EB between the second case-side friction plate 81B and the second gear-side friction plate 82B in the second differential limiting mechanism 72, are different from each other.

[0101] In this example, the first inner diameter dA of the first case-side friction plate 81A is smaller than the second inner diameter dB of the second case-side friction plate 81B. Furthermore, the first outer diameter DA of the first gear-side friction plate 82A is smaller than the second outer diameter DB of the second gear-side friction plate 82B. The first sliding diameter EA is smaller than the second sliding diameter EB.

[0102] The other components are the same as those in the above embodiment.

[0103] The differential limiting torque T for the right rear wheel 3 (wheel) corresponding to the first differential limiting mechanism 71 and the differential limiting torque T for the left rear wheel 3 (wheel) corresponding to the second differential limiting mechanism 72 can be made different from each other.

[0104] <Fourth Embodiment> A fourth embodiment will now be described. In the following description, components similar to those in the above embodiments will be denoted by the same reference numerals, and detailed descriptions will be omitted. Figure 9 shows the rear differential 30.

[0105] The side gear 60 has a gear body 61. The side gear 60 does not have a pressing body 62. Multiple friction plates 80 are clamped and pressed in the axial direction X by the gear portion 61a of the gear body 61 and the wall portion of the differential case 40. The gear-side friction plate 82 is provided on the outer circumferential surface of the cylindrical portion 61b of the gear body 61 in the side gear 60. Specifically, the protruding portion 82b of the gear-side friction plate 82 is fitted into grooves (extending in the axial direction X and arranged around the rotation axis O) provided on the outer circumferential surface of the cylindrical portion 61b of the gear body 61.

[0106] The other components are the same as those in the above embodiment.

[0107] <Other Embodiments> Although this disclosure has been described above with reference to preferred embodiments, this description is not limiting, and various modifications, substitutions, or combinations are, of course, possible.

[0108] The first inner diameter dA of the first case-side friction plate 81A may be made larger than the second inner diameter dB of the second case-side friction plate 81B. The first outer diameter DA of the first gear-side friction plate 82A may be made smaller than the second outer diameter DB of the second gear-side friction plate 82B.

[0109] The differential limiting mechanism 70 may be provided on either one side or the other side of the axial direction X relative to the pinion gear 52.

[0110] In the above embodiment, the differential limiting mechanism 70 was provided only in the rear differential 30, but is not limited to this, and may be provided in both the rear differential 30 and the front differential 13, or even in the front differential 13 only.

[0111] Instead of grooves for holding the friction plate 80, comb teeth may be used. The friction plate 80 may be provided in the differential case 40 or side gear 60 with a configuration different from grooves and comb teeth.

[0112] In the above embodiment, a rear differential 30 equipped with a differential limiting mechanism 70 was used for differential control of the left and right rear wheels 3 of the vehicle 1, but the embodiment is not limited to this. A front differential 13 equipped with a differential limiting mechanism 70 may be used for differential control of the left and right front wheels 2 of the vehicle 1.

[0113] Vehicle 1 may be a rear-wheel drive system in which the rear wheels 3 are driven by rotation. Vehicle 1 may also be a front-wheel drive system in which the front wheels 2 are driven by rotation. In these cases, the rear differential 30 and the front differential 13 may be connected by a propeller shaft.

[0114] Vehicle 1 may be driven by an engine. In this case, the differential case 40 rotates by receiving the driving force from the engine, which is the driving source. [Industrial applicability]

[0115] This disclosure is extremely useful and highly industrially applicable because it applies to vehicle differentials and vehicles. [Explanation of Symbols]

[0116] O Rotation axis X-axis direction T Differential limiting torque dA First inner diameter dB 2nd inner diameter DA First outer diameter DB 2nd outer diameter EA First sliding diameter EB 2nd sliding diameter 1 vehicle 2 Front wheels 3 Rear wheel (wheel) 10 Front drive unit 20 Rear drive unit 21 Rear drive motor (drive source) 30. Rear differential (vehicle differential) 40 Differential Case 52 Pinion Gear 60 Side Gear 61 Gear body 62 Pressing body 70 Differential limiting mechanism 71 First differential limiting mechanism 72 Second Differential Limiting Mechanism 80 Friction plate 81 Case-side friction plate 81A First case side friction plate 81B Second case side friction plate 82 Gear-side friction plate 82A First gear side friction plate 82B Second gear side friction plate

Claims

1. A differential gear for vehicles that is mounted on a vehicle, A differential case that rotates under the driving force of the drive source, A pair of side gears are arranged inside the differential case and are coaxial with the rotation axis of the differential case, A pinion gear is disposed within the differential case and meshes with both of the pair of side gears, The vehicle comprises a differential limiting mechanism that generates a differential limiting torque to limit the differential movement of the vehicle's wheels, The differential limiting mechanism has a plurality of friction plates that are pressed by the side gear in the axial direction from which the rotating shaft extends, Some of the multiple friction plates are multiple case-side friction plates provided in the differential case. The other part of the plurality of friction plates is a plurality of gear-side friction plates provided on the side gear, The case-side friction plate and the gear-side friction plate are arranged side by side in the axial direction and generate the differential limiting torque by sliding against each other. The case-side friction plate includes a first case-side friction plate and a second case-side friction plate. The gear-side friction plate includes a first gear-side friction plate and a second gear-side friction plate. A differential gear for a vehicle, wherein the first sliding diameter between the first case-side friction plate and the first gear-side friction plate and the second sliding diameter between the second case-side friction plate and the second gear-side friction plate are different from each other.

2. The differential for a vehicle according to claim 1, wherein the first inner diameter of the first case-side friction plate and the second inner diameter of the second case-side friction plate are different from each other.

3. The differential for a vehicle according to claim 1, wherein the first outer diameter of the first gear-side friction plate and the second outer diameter of the second gear-side friction plate are different from each other.

4. The differential limiting mechanism includes a first differential limiting mechanism provided on one side of the pinion gear in the axial direction, and a second differential limiting mechanism provided on the other side of the pinion gear in the axial direction. The first differential limiting mechanism includes the first case-side friction plate and the first gear-side friction plate, and the second case-side friction plate and the second gear-side friction plate. A differential for a vehicle according to any one of claims 1 to 3, wherein the first sliding diameter between the first case-side friction plate and the first gear-side friction plate and the second sliding diameter between the second case-side friction plate and the second gear-side friction plate are different from each other.

5. The differential limiting mechanism includes a first differential limiting mechanism provided on one side of the pinion gear in the axial direction, and a second differential limiting mechanism provided on the other side of the pinion gear in the axial direction. The first differential limiting mechanism includes the first case-side friction plate and the first gear-side friction plate. The second differential limiting mechanism includes the second case-side friction plate and the second gear-side friction plate. A differential for a vehicle according to any one of claims 1 to 3, wherein the first sliding diameter between the first case-side friction plate and the first gear-side friction plate in the first differential limiting mechanism and the second sliding diameter between the second case-side friction plate and the second gear-side friction plate in the second differential limiting mechanism are different from each other.

6. The side gear comprises a gear body that meshes with the pinion gear, and a pressing body that, together with the gear body, clamps a plurality of friction plates. The gear body and the pressing body are engaged with each other, The gear-side friction plate is provided on the pressing body, as described in any one of claims 1 to 3, for a vehicle differential.

7. The aforementioned vehicle is either rear-wheel drive or all-wheel drive. A vehicle differential according to any one of claims 1 to 3, used for differential control of the rear wheels of the aforementioned vehicle.

8. A front drive unit that rotates the front wheels, A vehicle comprising a rear drive unit that rotates the rear wheels independently of the front drive unit and has a vehicle differential as described in claim 7.

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