Differential limiting device

Abstract

[Problem] The purpose of the present invention is to provide a differential limiting device that suppresses relative rotation of a pair of output rotating members of a differential device, and that is capable of suppressing an increase in length of a stem part of a joint member connected to one output rotating member. [Solution] A differential device 11 has a differential case 112 and a pair of side gears 115, 116. A differential limiting device 10 suppresses relative rotation of the pair of side gears 115, 116. The differential limiting device 10 is provided with: a joint member 910 of a constant velocity universal joint 91 connected to one side gear 116 in a relatively non-rotatable manner; a clutch mechanism 2 having a clutch 20 for suppressing relative rotation between the joint member 910 and the differential case 112; and an operation mechanism 3 for operating the clutch mechanism 2. The joint member 910 has a cup part 911 formed in a bottomed cylindrical shape, and a shaft-like stem part 912 connected to the side gear 116. The clutch 20 is disposed on an outer periphery of the cup part 912.

Description

limited slip differential

[0001] The present invention relates to a limited slip differential device mounted on a vehicle.

[0002] Conventionally, a differential gear is installed in a vehicle, which is disposed between the left and right wheels and distributes the driving force of a drive source to the left and right wheels while allowing differential rotation between them. Some such differential gears have a differential limiting function that suppresses differential rotation between the left and right wheels to improve driving stability, for example, when traveling on a low-μ road.

[0003] The differential devices described in Patent Documents 1 and 2 include a differential case to which the driving force of a driving source such as an engine is transmitted, a pinion shaft held in the differential case, a plurality of pinion gears journaled on the pinion shaft, a pair of left and right side gears meshed with the plurality of pinion gears, and a differential limiting mechanism that suppresses relative rotation between one of the pair of left and right side gears and the differential case.

[0004] In the differential device described in Patent Document 1, the limited slip differential mechanism is configured with a multi-plate clutch and a hydraulic actuator. In the differential device described in Patent Document 2, the limited slip differential mechanism is configured with a dog clutch and an electromagnetic actuator. In the differential devices described in Patent Documents 1 and 2, the limited slip differential mechanism is disposed on the outer periphery of a shaft-shaped stem portion of a joint member of a constant velocity universal joint that is connected to one of the side gears so as not to rotate relative to the other.

[0005] The differential and wheels are typically connected by a drive shaft, such as that described in Patent Document 3. The drive shaft described in Patent Document 3 includes a differential-side constant velocity universal joint drivingly connected to the differential, a wheel-side constant velocity universal joint drivingly connected to the wheels, and an intermediate shaft that swingably connects these constant velocity universal joints. The differential-side constant velocity universal joint is a tripod type, including a joint member integrally formed with a bottomed cylindrical cup portion and a shaft-shaped stem portion, and a tripod member disposed inside the cup portion, with the stem portion non-rotatably connected to one of the side gears of the differential. The wheel-side constant velocity universal joint is a Rzeppa type, in which an outer race and an inner race are connected to each other by a plurality of balls held in a cage so as to transmit driving force. The differential-side constant velocity universal joint and the wheel-side constant velocity universal joint are positioned at different heights relative to the road surface, and the intermediate shaft is inclined with respect to the axial direction of each of the differential-side and wheel-side constant velocity universal joints.

[0006] Japanese Patent Laid-Open No. 11-201261 ​​Japanese Patent Laid-Open No. 2020-46065 Japanese Patent Laid-Open No. 2019-11786

[0007] In the differential devices described in Patent Documents 1 and 2, the limited slip differential mechanism is disposed on the outer periphery of the shaft-shaped stem of the joint member, which increases the axial length of the stem. As the stem length increases, the distance in the vehicle width direction between the two constant velocity universal joints at both ends of the drive shaft decreases, increasing the inclination angle of the intermediate shaft relative to the axial direction of the two constant velocity universal joints. When the inclination angle of the intermediate shaft increases, wear is more likely to occur at the sliding points of the two constant velocity universal joints, reducing durability.

[0008] Therefore, the present invention aims to provide a differential limiting device that is combined with a differential device that distributes and outputs the vehicle driving force input to an input rotating member to a pair of output rotating members, suppresses the relative rotation of the pair of output rotating members, and is capable of suppressing an increase in the length of the stem portion of the coupling member connected to one of the output rotating members.

[0009] In order to achieve the above-mentioned object, the present invention provides a limited slip differential device that is combined with a differential gear that distributes and outputs the driving force of a vehicle input to an input rotating member to a pair of output rotating members, and that suppresses relative rotation of the pair of output rotating members, the limited slip differential device comprising: a coupling member of a constant velocity universal joint that is connected to one of the pair of output rotating members so as not to rotate relative to the other output rotating member; a clutch mechanism having a clutch that suppresses relative rotation between the coupling member and the input rotating member or the other output rotating member of the pair of output rotating members; and an operating mechanism that operates the clutch mechanism, wherein the coupling member has a cup portion formed in a cylindrical shape with a bottom, and an axial stem portion extending axially from the cup portion, the stem portion being connected to one of the output rotating members, and the clutch being disposed on the outer periphery of the cup portion.

[0010] According to the limited slip differential device of the present invention, it is possible to suppress an increase in the length of the stem portion of the coupling member connected to one of the output rotary members.

[0011] Fig. 2 is a schematic diagram showing an example of the general configuration of a vehicle equipped with a limited slip differential device according to a first embodiment of the present invention. Fig. 3 is a cross-sectional view showing an example of the configuration of a limited slip differential device and a differential device. Fig. 4 is an enlarged view showing an enlarged portion of Fig. 2. Fig. 5 is a cross-sectional view of a constant velocity universal joint and a joint connecting member. Fig. 6 is a schematic diagram showing an example of the general configuration of a vehicle equipped with a limited slip differential device according to a second embodiment of the present invention.

[0012] [First embodiment] A first embodiment of the present invention will be described with reference to Figures 1 to 4. Note that the embodiment described below is shown as a preferred specific example for carrying out the present invention, and although various technically preferable technical matters are specifically exemplified in some parts, the technical scope of the present invention is not limited to this specific embodiment.

[0013] Fig. 1 is a schematic diagram showing an example of the general configuration of a vehicle 1 equipped with a limited slip differential device 10 according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view showing an example of the configuration of the limited slip differential device 10 and a differential device 11 adjacent to the limited slip differential device 10. Fig. 3 is an enlarged view showing a portion of Fig. 2.

[0014] Vehicle 1 has limited slip differential 10, differential 11 to which limited slip differential 10 is combined, drive source 12 that generates drive force, propeller shaft 13, cross joint 14, and pinion gear shaft 15 that transmit the drive force of drive source 12 to differential 11, left and right wheels 16, 17, and left and right hub units 161, 171 provided corresponding to left and right wheels 16, 17, respectively. Vehicle 1 also has a left drive shaft 8 connected to left hub unit 161, and a right drive shaft 9 connected to right hub unit 171. Limited slip differential 10 and differential 11 are disposed between left and right wheels 16, 17 in the vehicle width direction of vehicle 1.

[0015] The drive source 12 is, for example, an engine or an electric motor, and generates drive force for running the vehicle 1. The drive force of the drive source 12 is transmitted from a propeller shaft 13 to the differential device 11 via a cross joint 14 and a pinion gear shaft 15, and is then distributed to left and right wheels 16 and 17 via left and right drive shafts 8 and 9 and hub units 161 and 171.

[0016] The left drive shaft 8 has an intermediate shaft 80 and constant velocity universal joints 81, 82 provided at both ends of the intermediate shaft 80. One constant velocity universal joint 81 on the differential device 11 side is a sliding type constant velocity universal joint that can absorb fluctuations in the distance between the constant velocity universal joints 81, 82 that accompany the up and down movement of the vehicle 1 while traveling. The other constant velocity universal joint 82 on the left wheel 16 side is a fixed type constant velocity universal joint that does not change the position of the end of the intermediate shaft 80 relative to the constant velocity universal joint 82 in the direction of the rotational axis of the left wheel 16 even if the operating angle fluctuates.

[0017] Similarly, the right drive shaft 9 has an intermediate shaft 90 and constant velocity universal joints 91, 92 provided at both ends of the intermediate shaft 90. One constant velocity universal joint 91 on the differential device 11 side is a sliding type constant velocity universal joint, and the other constant velocity universal joint 92 on the right wheel 17 side is a fixed type constant velocity universal joint. In this embodiment, the constant velocity universal joints 81, 91 on the differential device 11 side are tripod type constant velocity universal joints, and the constant velocity universal joints 82, 92 on the left wheel 16 and right wheel 17 sides are Rzeppa type constant velocity universal joints. The intermediate shafts 80, 90 are normally inclined with respect to the horizontal direction so that the ends on the differential device 11 side are vertically higher than the ends on the left and right wheel 16, 17 sides.

[0018] The differential device 11 has a ring gear 111 meshed with the pinion gear shaft 15, a differential case 112 that rotates integrally with the ring gear 111, a pinion shaft 113 fixed to the differential case 112, a pair of pinion gears 114 journaled on the pinion shaft 113, a pair of left and right side gears 115, 116 meshed with the pair of pinion gears 114, and a housing 117 that accommodates the ring gear 111 and the differential case 112 together with a portion of the pinion gear shaft 15.

[0019] As shown in FIG. 2 , the pinion gear shaft 15 is supported by a bearing 151 held by the housing 117. The differential case 112 is rotatably supported by bearings 118 at both left and right ends relative to the housing 117. Differential oil is sealed inside the housing 117, and the differential oil lubricates the meshing between the pinion gear shaft 15 and the ring gear 111 and the meshing between the pinion gear 114 and the side gear 115. Oil seals 119 that prevent leakage of the differential oil are disposed between the left and right ends of the differential case 112 and the housing 117. In addition, an O-ring 110 that prevents leakage of the differential oil is disposed between the right end of the differential case 112 and a clutch mechanism 2 (described later).

[0020] A driving force is input to the differential case 112 via the pinion gear shaft 15 and the ring gear 111. The differential device 11 distributes the driving force input to the differential case 112 to a pair of side gears 115, 116 and outputs the distributed driving force. A coupling member 810 of one constant velocity universal joint 81 of the left drive shaft 8 is connected to the left side gear 115 so as to be non-rotatable relative to the left side gear 115. A coupling member 910 of one constant velocity universal joint 91 of the right drive shaft 9 is connected to the right side gear 116 so as not to be rotatable relative to the right side gear 116. In this embodiment, the differential case 112 corresponds to the input rotating member of the present invention, and the side gears 115, 116 correspond to the output rotating members of the present invention.

[0021] The limited slip differential device 10 suppresses relative rotation between the differential case 112 and the right side gear 116 and the coupling member 910, thereby suppressing relative rotation between the left and right side gears 115, 116. By suppressing relative rotation between the differential case 112 and the right side gear 116, rotation of the pair of pinion gears 114 about the pinion shaft 113 is suppressed, thereby suppressing relative rotation between the left and right side gears 115, 116, and ultimately suppressing differential rotation between the left wheel 16 and the right wheel 17, thereby improving the straight-line stability of the vehicle 1.

[0022] Next, a detailed description will be given of the configuration of the limited slip differential 10. The limited slip differential 10 is configured to include a joint member 910 of a constant velocity universal joint 91 on the right drive shaft 9. In this embodiment, the limited slip differential 10 is described as being disposed on the right side of the differential 11 in the vehicle width direction, but the limited slip differential 10 may also be disposed on the left side of the differential 11.

[0023] The differential limiting device 10 includes a coupling member 910 of a constant velocity universal joint 91, a clutch mechanism 2 having a clutch 20 that suppresses relative rotation between a differential case 112 and the coupling member 910, an operating mechanism 3 that operates the clutch mechanism 2, a motor 30 that is the power source of the operating mechanism 3, a reduction mechanism 4 that reduces the output rotation of the motor 30 and transmits it to the operating mechanism 3, a case 5 that houses at least a portion of the clutch mechanism 2, first to fourth bearings 61 to 64, and first to seventh sealing members 71 to 77.

[0024] The joint member 910 of the constant velocity universal joint 91 integrally includes a cup portion 911 formed in a cylindrical shape with a bottom and a shaft-shaped stem portion 912. The cup portion 911 opens horizontally toward the right wheel 17. The stem portion 912 is located closer to the differential device 11 than the cup portion 911, and a portion of the stem portion 912 protrudes into the housing 117 of the differential device 11. At least a portion of the cup portion 911 is housed in the case 5.

[0025] A splined fitting portion 912a is provided at the tip end of the stem portion 912. The splined fitting portion 912a is splined into a fitting hole 116a formed in the center of the side gear 116 of the differential device 11. The splined fitting portion 912a of the stem portion 912 is splined into the fitting hole 116a of the side gear 116, so that the coupling member 910 is connected to the side gear 116 so as not to rotate relative to it.

[0026] In addition, the joint member 810 of one of the constant velocity universal joints 81 on the left drive shaft 8 also has a cup portion 811 and a stem portion 812 integrally formed therewith, as described above, and a spline fitting portion 812a provided at the tip of the stem portion 812 is spline-fitted into a fitting hole 115a of the left side gear 115, thereby connecting the left side gear 115 so as not to rotate relative to the side gear 115.

[0027] The coupling member 810 of the constant velocity universal joint 81 on the left drive shaft 8 and the coupling member 910 of the constant velocity universal joint 91 on the right drive shaft 9 are capable of relative rotation about a common rotation axis O. Hereinafter, the direction parallel to the rotation axis O will be referred to as the axial direction. The stem portion 812 of the coupling member 810 extends in the axial direction from the bottom of the cup portion 811 toward the side gear 115. The stem portion 912 of the coupling member 910 extends in the axial direction from the bottom of the cup portion 911 toward the side gear 116.

[0028] The clutch mechanism 2 includes a clutch 20, a connecting rotating member 21 that is connected to the differential case 112 so as not to rotate relative to the differential case 112, a joint connecting member 22 that is arranged on the outer periphery of the joint member 910 and whose relative rotation with respect to the joint member 910 and axial movement relative to the joint member 910 are restricted, and a pressure plate 23 and a support plate 24 that sandwich the clutch 20 in the axial direction.

[0029] The clutch 20 is disposed on the outer periphery of the cup portion 911 of the coupling member 910. In this embodiment, the clutch 20 is a multi-plate clutch having a plurality of outer clutch plates 201 and a plurality of inner clutch plates 202 arranged in the axial direction. The frictional sliding between the plurality of outer clutch plates 201 and the plurality of inner clutch plates 202 is lubricated by clutch oil. Clutch oil and differential oil have different characteristics. Clutch oil is a low-viscosity lubricating oil that is less viscous than differential oil, and both the clutch oil and differential oil contain additives suitable for their respective applications.

[0030] The actuation mechanism 3 presses the clutch 20 in the axial direction to generate a frictional force between the outer clutch plates 201 and the inner clutch plates 202. This frictional force serves as a differential limiting force that suppresses relative rotation between the left and right side gears 115, 116.

[0031] The connecting rotation member 21 integrally includes a connecting portion 211 that is connected to the differential case 112 so as not to rotate relative to the differential case 112, a small-diameter cylindrical portion 212 that is arranged on the outer periphery of the stem portion 912 of the joint member 910, a large-diameter cylindrical portion 213 that is arranged on the outer periphery of the cup portion 911 of the joint member 910, and a disk portion 214 that is located between the small-diameter cylindrical portion 212 and the large-diameter cylindrical portion 213. The clutch 20 is arranged alongside the large-diameter cylindrical portion 213 in the radial direction perpendicular to the axial direction.

[0032] The connecting portion 211 of the connecting rotating member 21 is spline-fitted to the end of the differential case 112 on the limited slip differential 10 side. The small-diameter cylindrical portion 212 has an inner diameter larger than the outer diameter of the stem portion 912, and an annular space is formed between the small-diameter cylindrical portion 212 and the stem portion 912. A first bearing 61 and first and second seal members 71, 72 are arranged between an inner circumferential surface 212a of the small-diameter cylindrical portion 212 and an outer circumferential surface 912b of the stem portion 912. The first bearing 61 is a radial roller bearing and is arranged closer to the differential device 11 than the first seal member 71.

[0033] The small-diameter cylindrical portion 212 has a through-hole 212c that penetrates between the inner circumferential surface 212a and the outer circumferential surface 212b and opens between the first seal member 71 and the second seal member 72. The first seal member 71 prevents leakage of differential oil from the differential device 11. The second seal member 72 keeps the space between the large-diameter cylindrical portion 213 and the disk portion 214 of the connecting rotation member 21 and the cup portion 911 of the coupling member 910 liquid-tight, thereby preventing leakage of clutch oil.

[0034] The large diameter cylindrical portion 213 has an inner diameter larger than the outer diameter of the small diameter cylindrical portion 212 and the outer diameter of the cup portion 911. The second bearing 62 is disposed between the large diameter cylindrical portion 213 and the cup portion 911. The large diameter cylindrical portion 213 is formed with spline engagement portions 213a with which the multiple inner clutch plates 202 are engaged so as to be axially movable but not rotatable relative to each other.

[0035] The joint connecting member 22 has a connecting portion 221 connected to the cup portion 911 of the joint member 910 so as not to rotate relative to the joint member 910, an engaging portion 222 with which a plurality of outer clutch plates 201 are engaged so as not to rotate relative to the joint member 910, a side wall portion 223 between the connecting portion 221 and the engaging portion 222, a disk portion 224 extending radially inward from the end of the engaging portion 222 on the differential device 11 side, and a cylindrical portion 225 extending axially from the inner diameter side end of the disk portion 224 towards the differential device 11 side.

[0036] The connecting portion 221 and the engaging portion 222 are both cylindrical and are aligned in the axial direction on the outer periphery of the cup portion 911 of the joint member 910. The engaging portion 222 has a larger diameter than the connecting portion 221 and is provided closer to the differential device 11 than the connecting portion 221. The pressing plate 23 and the receiving plate 24 are connected to the engaging portion 222 so as to be axially movable but not rotatable relative to the engaging portion 222. The pressing plate 23 is disposed between the side wall portion 223 and the clutch 20, and the receiving plate 24 is disposed between the disk portion 224 and the clutch 20.

[0037] For ease of assembling the clutch 20, the pressure plate 23, and the support plate 24, the joint connecting member 22 is made up of two members, a side wall portion 223 and an engaging portion 222, which are joined by welding. Note that the welding position is not limited to between the side wall portion 223 and the engaging portion 222, but may be, for example, between the engaging portion 222 and the disk portion 224. Furthermore, the two members may be joined by means of not only welding but also bolts, for example.

[0038] 4 is a cross-sectional view of the constant velocity universal joint 91 and the joint connecting member 22 taken along a cross section perpendicular to the rotation axis O. The constant velocity universal joint 91 has a tripod member 913, which is an inner member arranged inside the joint member 910, and three roller units 914 attached to the tripod member 913. The tripod member 913 and the three roller units 914 are housed together with a part of the intermediate shaft 90 in a housing hole 911a formed in a cup portion 911 of the joint member 910. As shown in FIG. 2, a resin boot 900 having a bellows structure is attached between the tip end of the cup portion 911 and the intermediate shaft 90.

[0039] The tripod member 913 integrally includes a boss 913a into which the intermediate shaft 90 is fitted so as not to rotate relative to the boss 913a, and three leg shafts 913b extending radially from the boss 913a. Each roller unit 914 includes a cylindrical inner roller 914a swingably fitted onto the leg shaft 913b, an outer roller 914b that is coaxially rotatable relative to the inner roller 914a, and a plurality of rolling elements 914c interposed between the inner roller 914a and the outer roller 914b.

[0040] A raceway surface 911b on which the outer roller 914b rolls is formed and extends in the axial direction on the inner surface of the accommodation hole 911a. When the tripod member 913 is displaced in the axial direction relative to the joint member 910, the outer roller 914b rolls on the raceway surface 911b. The length of the raceway surface 911b is set so as not to hinder the axial movement of the tripod member 913 relative to the joint member 910 even when the right wheel 17 moves up and down relative to the body of the vehicle 1.

[0041] When the joint member 910 and the intermediate shaft 90 rotate with the intermediate shaft 90 tilted with respect to the rotation axis O, the tripod member 913 swings relative to the roller unit 914. During this swing, the trunnion 913b slides on the inner surface of the inner roller 914a. The operating angle, which is the angle of inclination of the intermediate shaft 90 with respect to the rotation axis O, is, for example, 10° to 15° when the intermediate shaft 90 is mounted on the vehicle 1. Note that FIGS. 2 to 4 show a state in which the operating angle is 0°.

[0042] The coupling portion 221 of the joint connecting member 22 has irregularities on its inner peripheral surface that engage with irregularities on the outer peripheral surface of the cup portion 911, thereby restricting relative rotation with the joint part 910. The outer peripheral surface of the cup portion 911 in a cross section perpendicular to the rotation axis O is generally hexagonal, with six recesses 911c and six protrusions 911d formed therein. The inner peripheral surface of the coupling portion 221 of the joint connecting member 22 in the same cross section is also generally hexagonal, with six recesses 221a and six protrusions 221b formed in the coupling portion 221. The six protrusions 221b of the coupling portion 221 engage with the six recesses 911c of the cup portion 911, respectively, and the six recesses 221a engage with the six protrusions 911d of the cup portion 911, respectively, thereby restricting relative rotation with the joint part 910.

[0043] Alternatively, the connecting portion 221 of the joint connecting member 22 and the cup portion 911 on the inside of the connecting portion 221 may be formed cylindrically, and a plurality of spline protrusions extending in the axial direction may be formed on the inner surface of the connecting portion 221 and the outer surface of the cup portion 911, and the cup portion 911 may be spline-fitted into the connecting portion 221 to restrict relative rotation between the joint connecting member 22 and the joint member 910.

[0044] The joint connecting member 22 is restricted from moving in the axial direction relative to the joint part 910. In order to restrict the axial movement of the joint connecting member 22 relative to the joint part 910, a part of the connecting portion 221 may be crimped to the cup portion 911, or the connecting portion 221 may be welded to the cup portion 911. Alternatively, the axial movement of the joint connecting member 22 relative to the joint part 910 may be restricted by press-fitting the cup portion 911 into the connecting portion 221.

[0045] A third seal member 73 that liquid-tightly seals the clutch 20 is disposed between the connecting rotation member 21 and the joint connecting member 22. The third seal member 73 is attached to the inside of the cylindrical portion 225 of the joint connecting member 22, and is in elastic contact with the outer circumferential surface 212b of the small diameter cylindrical portion 212. In addition, a fourth seal member 74 that liquid-tightly seals the clutch 20 is disposed between the connecting portion 221 of the joint connecting member 22 and the cup portion 911 of the joint member 910.

[0046] The clutch 20 is disposed between the engaging portion 222 of the joint connecting member 22 and the large-diameter cylindrical portion 213 of the connecting rotation member 21. The engaging portion 222 is formed with spline engaging portions 222a with which the outer clutch plates 201, the pressure plate 23, and the support plate 24 are engaged so as to be axially movable but not rotatable relative to each other.

[0047] The case 5 has a case body 51 that opens toward the differential device 11, and a case lid 52 that is provided to close the opening of the case body 51. The case body 51 and the case lid 52 are attached to the housing 117 of the differential device 11 with a plurality of bolts 53. The limited slip differential 10 can be removed from the differential device 11 together with the drive shaft 9 by loosening the plurality of bolts 53. In other words, the limited slip differential 10 is detachable from the differential device 11.

[0048] The case 5 accommodates a motor 30. As shown in Fig. 1, the motor 30 has a motor body 301 fixed to the case body 51, an output shaft 302 that rotates relative to the motor body 301, and an output gear 303 provided at the tip of the output shaft 302. Current is supplied to the motor body 301 from the control device 100.

[0049] The reduction mechanism 4 is composed of a reduction gear 40 supported by the case 5. The reduction gear 40 has a large-diameter gear portion 41, a small-diameter gear portion 42, and a connecting shaft 43 that connects the large-diameter gear portion 41 and the small-diameter gear portion 42 so that they rotate together. The large-diameter gear portion 41 meshes with the output gear 303 of the motor 30. One axial end of the connecting shaft 43 is supported by the case main body 51, and the other axial end is supported by the case cover 52. The large-diameter gear portion 41 and the small-diameter gear portion 42 are provided between both ends of the connecting shaft 43. The rotation of the connecting shaft 43 and the meshing of the large-diameter gear portion 41 and the small-diameter gear portion 42 are lubricated by grease sealed in the case 5.

[0050] The operating mechanism 3 includes a fixed cam member 31 that is prevented from rotating relative to the case 5, a rotating cam member 32 that rotates relative to the fixed cam member 31 by the torque of the motor 30 transmitted by the reduction mechanism 4, a plurality of cam balls 33 arranged between the fixed cam member 31 and the rotating cam member 32, a piston 34 that presses the clutch 20, a bearing 35 arranged between the rotating cam member 32 and the piston 34, a return spring 36 that urges the piston 34 in a direction away from the clutch 20, and a locking pin 37 that engages with the fixed cam member 31 to prevent the fixed cam member 31 from rotating.

[0051] The fixed cam member 31 and the rotating cam member 32 are formed with a plurality of cam grooves 31a, 32a in which a plurality of cam balls 33 roll, respectively. The cam grooves 31a, 32a are arc-shaped about the rotation axis O and are inclined grooves whose axial depth gradually changes depending on the rolling position of the cam balls 33. The rotating cam member 32 has a gear portion 321 that meshes with the small-diameter gear portion 42 of the reduction gear 40, and is rotated by the torque of the motor 30 amplified by the reduction mechanism 4. When the rotating cam member 32 rotates relative to the fixed cam member 31, the cam balls 33 roll in the cam grooves 31a, 32a, and the rotating cam member 32 moves axially relative to the fixed cam member 31.

[0052] The piston 34 has a disk-shaped base portion 341 centered on the rotation axis O, and a plurality of boss portions 342 provided to protrude in the axial direction from the base portion 341. The boss portions 342 are inserted into through holes 223a formed in the side wall portion 223 of the joint connecting member 22, and their tips face the pressing plate 23. When the rotating cam member 32 rotates and moves in a direction away from the fixed cam member 31, the resulting thrust is transmitted to the piston 34 via the bearing 35, and the plurality of boss portions 342 of the piston 34 press the clutch 20 via the pressing plate 23. The boss portions 342 are cylindrical, and a seal member 343 that prevents clutch oil from leaking from the through holes 223a is attached to the outer periphery of each boss portion 342.

[0053] The actuating mechanism 3 is disposed on the outer periphery of the connecting portion 221 of the joint connecting member 22. In other words, the connecting portion 221 of the joint connecting member 22 and the actuating mechanism 3 are aligned in the radial direction perpendicular to the rotation axis O. This ensures the length of the connecting portion 221 in the axial direction while preventing the case 5 and the joint member 910 from becoming larger. The clutch 20 and the actuating mechanism 3 are disposed on the outer periphery of the cup portion 911 and aligned in the axial direction so that the clutch 20 is closer to the stem portion 912 than the actuating mechanism 3.

[0054] The fixed cam member 31 has an engaging portion 311 that engages with the anti-rotation pin 37. The anti-rotation pin 37 is press-fit into a fitting hole 511 formed in the case body 51. The fixed cam member 31 also has a cylindrical protrusion 312 that extends toward the side opposite to the rotating cam member 32, and a third bearing 63 is disposed between the protrusion 312 and the connecting portion 221 of the joint connecting member 22. The third bearing 63 rotatably supports the joint member 910 via the connecting portion 221 of the joint connecting member 22. Axial movement of the third bearing 63 relative to the joint connecting member 22 is restricted by a retaining ring 25 fitted into the connecting portion 221.

[0055] The case 5 houses the joint connecting member 22 together with part of the cup portion 911 of the joint part 910. The case lid 52 has a cylindrical bearing holder 521 that faces radially the cylindrical portion 225 of the joint connecting member 22, and a fourth bearing 64 is held between the bearing holder 521 and the cylindrical portion 225 of the joint connecting member 22. The fourth bearing 64 is held by the bearing holder 521, and rotatably supports the joint part 910 via the joint connecting member 22.

[0056] The fourth bearing 64 is restricted from axial movement away from the differential device 11 by the locking projection 521a provided on the bearing holder 521, and is restricted from axial movement toward the differential device 11 by the retaining ring 26 attached to the cylindrical portion 225 of the joint connecting member 22. In other words, the fourth bearing 64 restricts axial movement of the joint member 910 relative to the case 5.

[0057] The third bearing 63 and the fourth bearing 64 are ball bearings in which spherical rolling elements 633, 643 are disposed between outer rings 631, 641 and inner rings 632, 642, and are also sealed bearings in which seals 634, 644 are disposed between the outer rings 631, 641 and inner rings 632, 642. Because the third bearing 63 and the fourth bearing 64 are sealed bearings, leakage of grease from the case 5 is suppressed. In addition, leakage of grease from the case 5 is also suppressed by a fifth seal member 75 disposed between the protrusion 312 of the fixed cam member 31 and the case main body 51, a sixth seal member 76 disposed between the outer ring 631 of the third bearing 63 and the protrusion 312 of the fixed cam member 31, and a seventh seal member 77 disposed between the inner ring 632 of the third bearing 63 and the connecting portion 221 of the joint connecting member 22.

[0058] According to the first embodiment described above, the configuration in which the clutch 20 is disposed on the outer periphery of the cup portion 911 of the joint member 910 makes it possible to shorten the axial length of the joint member 910 compared to cases in which a limited slip differential mechanism is disposed on the outer periphery of a stem portion of a joint member of a constant velocity universal joint, as described in, for example, Patent Documents 1 and 2. This makes it possible to keep the operating angle of the intermediate shaft 90 small, reducing wear on sliding portions within the constant velocity universal joint 91 while the vehicle 1 is traveling and improving durability.

[0059] In other words, if the joint member 910 were to be longer, the distance between the pair of constant velocity universal joints 91, 92 provided on both ends of the drive shaft 9 would be shorter, and the inclination of the intermediate shaft 90 with respect to the axial direction of the joint member 910 would increase, causing the trunnion shaft 913b of the tripod member 913, which is the inner member of the constant velocity universal joint 91, to swing significantly relative to the inner roller 914a, and wear would be more likely to occur due to the sliding caused by this swinging. However, according to the first embodiment, the increase in the length of the joint member 910 can be suppressed, and therefore wear can be suppressed.

[0060] Furthermore, according to the first embodiment, the space in which the clutch 20 is disposed can be liquid-tightly sealed by the second and third sealing members 72, 73, and the sealing member 343 disposed on the outer periphery of the boss portion 342 of the piston 34, so that clutch oil with characteristics suitable for lubricating the multiple outer clutch plates 201 and inner clutch plates 202 can be used, thereby improving the durability and friction characteristics of the clutch 20.

[0061] Furthermore, according to the first embodiment, the axial movement of the coupling member 910 relative to the case 5 is restricted by the fourth bearing 64, so that the differential limiting device 10, together with the drive shaft 9, can be easily attached and detached to and from the differential device 11.

[0062] Furthermore, according to the first embodiment, the actuating mechanism 3 is arranged on the outer periphery of the cup portion 911 of the coupling part 910, aligned with the clutch 20 in the axial direction, and therefore it is possible to suppress an increase in the length of the cup portion 911 due to the arrangement of the actuating mechanism 3.

[0063] Furthermore, according to the first embodiment, the actuation mechanism 3 is disposed on the outer periphery of the connecting portion 221 of the joint connecting member 22, which ensures a sufficient length of the connecting portion 221 and makes it possible to improve the coaxiality between the joint part 910 and the joint connecting member 22. Furthermore, the connecting portion 221 of the joint connecting member 22 has irregularities on its inner circumferential surface that engage with irregularities on the outer circumferential surface of the cup portion 911, thereby restricting relative rotation with the joint part 910. Therefore, even if the differential limiting force becomes large, the mounting rigidity of the joint connecting member 22 to the joint part 910 can be sufficiently ensured.

[0064] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 5. In the second embodiment, the configuration of a differential 18 combined with a limited slip differential 10 differs from that of the differential 11 according to the first embodiment. In Fig. 5, components corresponding to those described in the first embodiment are designated by the same reference numerals as those in Fig. 1, and detailed description thereof will be omitted.

[0065] In the first embodiment, the differential device 11 has been described as having a differential case 112 as an input rotating member and side gears 115, 116 as a pair of output rotating members. However, the differential device 18 according to the second embodiment has a differential case 182 as an input rotating member that rotates integrally with a ring gear 181 meshed with the pinion gear shaft 15, and a planetary carrier 183 and a sun gear 184 as a pair of output rotating members. A coupling member 810 of the constant velocity universal joint 81 is connected to the planetary carrier 183 so as not to rotate relative to the planetary carrier 183. A coupling member 910 of the constant velocity universal joint 91 is connected to the sun gear 184 so as not to rotate relative to the planetary carrier 183.

[0066] The differential device 18 also has a plurality of pinion gear sets 185. Each pinion gear set 185 has an outer planetary gear 186 and an inner planetary gear 187 that mesh with each other. The planetary carrier 183 rotatably supports the outer planetary gear 186 and the inner planetary gear 187 of each pinion gear set 185. The outer planetary gear 186 meshes with an internal gear 182a formed on the inner periphery of the differential case 182, and the inner planetary gear 187 meshes with the sun gear 184. In Figure 5, the outer planetary gear 186 and the inner planetary gear 187 are shown aligned in the vertical direction, but the outer planetary gear 186 and the inner planetary gear 187 are arranged between the internal gear 182a and the sun gear 184 so that a portion of them is aligned in the circumferential direction of the planetary carrier 183.

[0067] The planetary carrier 183 is housed in a differential case 182 together with a plurality of pinion gear sets 185. The ring gear 181 and the differential case 182 are housed in a housing 188 supported on the body of the vehicle 1.

[0068] When the vehicle 1 is traveling straight ahead and the left wheel 16 and the right wheel 17 rotate at the same rotational speed, the outer planetary gear 186 and the inner planetary gear 187 rotate integrally with the planetary carrier 183 without rotating on their own axes, and the driving force input to the differential case 182 is output from the planetary carrier 183 and the sun gear 184. When a difference in rotational speed occurs between the left wheel 16 and the right wheel 17, the outer planetary gear 186 and the inner planetary gear 187 transmit the driving force while rotating on their own axes, and the driving force input to the differential case 182 is output from the planetary carrier 183 and the sun gear 184.

[0069] The planetary carrier 183 has a first side wall portion 183a disposed on one axial side of the plurality of pinion gear sets 185, and a second side wall portion 183b disposed on the other axial side of the plurality of pinion gear sets 185. The coupling member 810 of the constant velocity universal joint 81 is fitted to the first side wall portion 183a so as to be non-rotatable relative to the first side wall portion 183a. The connecting rotation member 21 of the clutch mechanism 2 in the limited slip differential 10 is fitted to the second side wall portion 183b so as not to be rotatable relative to the second side wall portion 183b.

[0070] When the clutch 20 is pressed by the operating mechanism 3 to generate a frictional force, the relative rotation is suppressed between the coupling member 910 of the constant velocity universal joint 91 connected to the sun gear 184 and the planetary carrier 183 connected to the connecting rotation member 21. In other words, in the present embodiment, the relative rotation between the sun gear 184, which is one of the output rotation members connected to the coupling member 910 so as not to rotate relative to each other, and the planetary carrier 183, which is the other output rotation member connected to the connecting rotation member 21 so as not to rotate relative to each other, is suppressed by the frictional force of the clutch 20.

[0071] The second embodiment also provides the same effects as the first embodiment.

[0072] (Note) While the present invention has been described above based on the first and second embodiments, these embodiments do not limit the scope of the claimed invention. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. Furthermore, the present invention can be implemented by appropriately modifying it, omitting some components or adding or substituting components, without departing from the spirit of the invention. For example, the following modifications are possible.

[0073] In the above embodiment, the rotation of the motor 30 is decelerated by the speed reducing mechanism 4, and the clutch 20 is pressed by operating a cam mechanism made up of the fixed cam member 31, the rotating cam member 32, and the plurality of cam balls 33. However, the present invention is not limited to this, and the clutch 20 may be pressed by hydraulic pressure, for example. In this case, the actuation mechanism is made up of a piston that presses the clutch 20 and a hydraulic cylinder that applies hydraulic pressure to the piston.

[0074] In the above embodiment, the clutch 20 is a multi-plate clutch, but this is not limiting and a dog clutch in which a pair of meshing members mesh may be used. When the clutch mechanism is configured as a dog clutch, when the clutch is activated, the left wheel 16 and the right wheel 17 are placed in a differential lock state in which they cannot rotate relative to each other.

[0075] REFERENCE SIGNS LIST 1...Vehicle 10...Limited differential device 11...Differential device 112...Differential case (input rotating member) 115, 116...Side gear (output rotating member) 183...Planetary carrier (output rotating member) 184...Sun gear (output rotating member) 2...Clutch mechanism 20...Clutch 201...Outer clutch plate 202...Inner clutch plate 21...Coupling rotating member 211...Coupling portion 212...Small diameter cylindrical portion 213...Large diameter cylindrical portion 22...Joint coupling member 221...Coupling portion 222...Engaging portion 3...Operating mechanism 5...Case 64...Fourth bearing 72-74...Second to fourth seal members 91...Constant velocity universal joint 910...Joint member 911...Cup portion 912...Stem portion

Claims

1. A differential limiting device combined with a differential gear which distributes the driving force of a vehicle input to an input rotating member to a pair of output rotating members and outputs it, and suppresses relative rotation of the pair of output rotating members, comprising: a coupling member of a constant velocity universal joint which is connected to one of the pair of output rotating members so as not to rotate relative to the other output rotating member of the pair of output rotating members, a clutch mechanism having a clutch which suppresses relative rotation between the coupling member and the input rotating member or the other output rotating member of the pair of output rotating members, and an operating mechanism which operates the clutch mechanism, wherein the coupling member has a cup portion formed in a cylindrical shape with a bottom, and a shaft-shaped stem portion extending axially from the cup portion, the stem portion is connected to the one output rotating member, and the clutch is disposed on the outer periphery of the cup portion.

2. The differential limiting device as claimed in claim 1, wherein the clutch mechanism has a connecting rotating member connected to the input rotating member or the other output rotating member, the connecting rotating member having a connecting portion connected to the input rotating member or the other output rotating member so as not to rotate relative to the input rotating member or the other output rotating member, a small diameter cylindrical portion arranged on the outer periphery of the stem portion, and a large diameter cylindrical portion arranged on the outer periphery of the cup portion, the clutch is arranged radially aligned with the large diameter cylindrical portion, and a seal member is arranged between the small diameter cylindrical portion and the stem portion to keep the space between the cup portion and the large diameter cylindrical portion liquid-tight.

3. The differential limiting device according to claim 2, wherein the clutch mechanism has a coupling member that is disposed on the outer periphery of the coupling member and whose relative rotation with respect to the coupling member and whose axial movement with respect to the coupling member is restricted, and the clutch is disposed between the coupling member and the large diameter cylindrical portion of the coupling rotation member.

4. The limited slip differential device according to claim 3, wherein a seal member for sealing said clutch liquid-tightly is disposed between said joint connecting member and said connecting rotary member.

5. The differential limiting device as claimed in claim 1, wherein the clutch is a multi-plate clutch having a plurality of clutch plates arranged in the axial direction, the operating mechanism presses the clutch in the axial direction to generate frictional force between the plurality of clutch plates, and the clutch and the operating mechanism are arranged in the axial direction on the outer periphery of the cup portion so that the clutch is closer to the stem than the operating mechanism.

6. A differential limiting device as claimed in claim 5, wherein the clutch mechanism has a coupling member arranged on the outer periphery of the coupling member and restricted in its relative rotation with respect to the coupling member and its axial movement with respect to the coupling member, the coupling member having a connecting portion connected to the cup portion of the coupling member so as to be non-rotatable relative to the coupling member, and an engaging portion with which some of the plurality of clutch plates engage so as not to be able to rotate relative to the coupling member, and the operating mechanism is arranged on the outer periphery of the connecting portion.

7. The differential limiting device as set forth in claim 6, wherein the coupling portion of the joint connecting member has projections and recesses on its inner peripheral surface that engage with projections and recesses on the outer peripheral surface of the cup portion, thereby restricting relative rotation with the joint member.

8. A differential limiting device as claimed in claim 6 or 7, wherein the clutch mechanism has a connecting rotating member connected to the input rotating member or the other of the output rotating members so as not to rotate relative to each other, the connecting rotating member having a large diameter cylindrical portion arranged on the outer periphery of the cup portion, and the clutch is arranged between the large diameter cylindrical portion and the engaging portion of the joint connecting member.

9. A differential limiting device as claimed in any one of claims 1 to 4, comprising: a case that houses at least a part of the clutch mechanism together with at least a part of the cup portion; and a bearing that is held by the case and supports the coupling member rotatably relative to the case, wherein axial movement of the coupling member relative to the case is regulated by the bearing.

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