Differential device

Abstract

[Problem] To provide a differential device with which the device can be reduced in size while having: a friction clutch that suppresses differential rotation of a pair of output rotating members by means of a frictional force; and an engagement member that prevents relative rotation of the pair of output rotating members by engagement of teeth. [Solution] A differential device 1 comprises: an input rotating member 2 that rotates around a rotation axis O; a pair of output rotating members 31, 32 that are accommodated in the input rotating member 2 and rotate around the rotation axis O; a plurality of differential gears 33, 34 that enable differential rotation of the pair of output rotating members 31, 32; an engagement member 4 that has dog teeth 41 capable of engaging with the output rotating member 32, and that engages with the output rotating member 32 to prevent the output rotating member 32 from rotating relative to the input rotating member 2; and a friction clutch 5 that suppresses differential rotation between the output rotating member 32 and the input rotating member 3 by means of a frictional force. The engagement member 4 is disposed inside the friction clutch 5 in a radial direction perpendicular to the rotation axis O.

Description

Differential device

[0001] The present invention relates to a differential device used to distribute driving force between left and right wheels of a vehicle.

[0002] In a vehicle, the driving force of a drive source such as an engine is distributed to the left and right wheels by a differential gear mechanism that includes a pair of left and right side gears that are output rotating members, and multiple pinion gears that mesh with the left and right side gears.This differential gear mechanism enables the left and right wheels to rotate differentially when cornering.

[0003] The differential devices described in Patent Documents 1 and 2 include, in addition to a differential gear mechanism, a friction clutch that suppresses differential rotation between the left and right wheels by friction force, a dog clutch that prohibits differential rotation between the left and right wheels by meshing its teeth, and a cam mechanism for operating the friction clutch and the dog clutch. By suppressing or prohibiting differential rotation between the left and right wheels, for example, even if one of the left and right wheels slips, driving force can be transmitted to the other wheel, improving off-road performance. In the differential devices described in Patent Documents 1 and 2, the friction clutch, dog clutch, and cam mechanism are arranged side by side in an axial direction parallel to the vehicle width direction.

[0004] US Patent Publication No. 2019 / 0348675 International Publication No. 2019 / 111294

[0005] The differential devices described in Patent Documents 1 and 2 are equipped with a friction clutch and a dog clutch, which increases the size of the device in the vehicle width direction, which reduces the mountability of the device on a vehicle.

[0006] Therefore, an object of the present invention is to provide a differential device that can be made smaller in size while having a friction clutch that suppresses differential rotation of a pair of output rotating members by frictional force, and an engaging member that prevents the pair of output rotating members from rotating relative to each other by meshing their teeth.

[0007] In order to achieve the above-mentioned object, the present invention provides a differential device comprising: a case-shaped input rotating member to which driving force from a driving source is input and which rotates about a rotation axis due to the driving force; a pair of output rotating members housed in the input rotating member and rotating about the rotation axis; a plurality of differential gears housed in the input rotating member and enabling differential rotation of the pair of output rotating members; a meshing member having dog teeth that can mesh with one of the pair of output rotating members, and which moves axially relative to the input rotating member so that the dog teeth mesh with the one output rotating member, thereby preventing the one output rotating member from rotating relatively to the input rotating member; and a friction clutch that is arranged between the one output rotating member and the input rotating member and suppresses differential rotation between the one output rotating member and the input rotating member by frictional force, wherein the meshing member is arranged inside the friction clutch in a radial direction perpendicular to the rotation axis.

[0008] The differential device according to the present invention allows for a reduction in the size of the device.

[0009] FIG. 1 is a cross-sectional view showing an example of the configuration of a differential gear according to an embodiment of the present invention. FIG. 2 is a partially enlarged view showing a portion of FIG. 1. FIG. 3 is a structural diagram showing opposing surfaces of a rotating cam member that face the first driven cam member and the second driven cam member. FIG. 4 is a perspective cross-sectional view of the rotating cam member, showing a cross section taken along line A-A in FIG. 3. FIG. 5 is a structural diagram showing opposing surfaces of a first driven cam member that face the rotating cam member. FIG. 6 is a structural diagram showing opposing surfaces of a second driven cam member that face the rotating cam member. FIG. 7A is an explanatory diagram schematically showing a state in which the first thrust generating mechanism and the second thrust generating mechanism are both inactive. FIG. 7B is an explanatory diagram schematically showing an operating state of the second thrust generating mechanism. FIG. 7C is an explanatory diagram schematically showing an operating state of the first thrust generating mechanism. FIG. 7D is an explanatory diagram schematically showing an operating state of the first thrust generating mechanism.

[0010] [Embodiments] The following describes embodiments of the present invention with reference to the drawings. The embodiments described below are shown as preferred specific examples for carrying out the present invention, and although some of the embodiments specifically exemplify various technically preferred aspects, the technical scope of the present invention is not limited to these specific embodiments.

[0011] Fig. 1 is a cross-sectional view showing an example of the configuration of a differential device 1 according to an embodiment of the present invention. Fig. 2 is a partially enlarged view showing a portion of Fig. 1. In the following description, for convenience, the left side of Figs. 1 and 2 will be referred to as "left" and the right side will be referred to as "right," but this "left" and "right" do not necessarily refer to the left and right with respect to the forward direction of the vehicle.

[0012] A differential gear 1 is mounted on a vehicle and is used to distribute driving force from a driving source such as an engine or an electric motor to left and right wheels. FIG. 1 shows the differential gear 1, a differential carrier 10, left and right tubes 11 and 12 attached to the differential carrier 10, left and right axle shafts 13 and 14 housed in the tubes 11 and 12, respectively, a pinion gear shaft 16 rotatably supported by bearings 15 on the differential carrier 10, a ring gear 17 meshed with the pinion gear shaft 16, and bearings 18 and 19 supporting the differential gear 1 on the differential carrier 10. The differential gear 1 distributes the driving force of the driving source input from the pinion gear shaft 16 to the left and right axle shafts 13 and 14 while allowing differential movement. Lubricating oil (not shown) is sealed inside the differential carrier 10.

[0013] The differential device 1 includes a case-shaped input rotary member 2 that rotates about a rotation axis O by the driving force of a drive source, a pinion shaft 30 fixed to the input rotary member 2, a pair of output rotary members 31, 32 to which left and right axle shafts 13, 14 are respectively connected so as not to rotate relative to each other, and a plurality of differential gears 33, 34 that enable differential rotation of the output rotary members 31, 32. The output rotary members 31, 32 and the differential gears 33, 34 constitute a differential gear mechanism 3.

[0014] The output rotating members 31, 32 and the differential gears 33, 34 are housed in the input rotating member 2. The output rotating members 31, 32 rotate about a rotation axis O. The differential gears 33, 34 are journaled on the pinion shaft 30. In this embodiment, the differential gears 33, 34 are bevel gears. The output rotating members 31, 32 are meshed with the differential gears 33, 34. The left axle shaft 13 is spline-fitted into a fitting hole 310 formed in the left output rotating member 31 of the pair of output rotating members 31, 32. The right axle shaft 14 is spline-fitted into a fitting hole 320 formed in the right output rotating member 32.

[0015] Hereinafter, a direction parallel to the rotation axis O will be referred to as the axial direction, and a direction perpendicular to the rotation axis O will be referred to as the radial direction. The pinion shaft 30 is disposed between the output rotation members 31, 32 and extends in the radial direction.

[0016] The input rotational member 2 has a hollow case member 21 that is open on one axial side, and a lid member 22 that closes the opening of the case member 21. The case member 21 is formed, for example, by casting. The lid member 22 is formed, for example, by forging. The lid member 22 is fixed to the case member 21 and rotates integrally with the case member 21. The case member 21 has a flange portion 211 to which a ring gear 17 is fixed. The ring gear 17 is fixed to the flange portion 211 with a plurality of bolts 171. Driving force of a drive source is input to the input rotational member 2 from the ring gear 17. The ring gear 17 may also be fixed to the case member 21 by welding.

[0017] The case member 21 is formed with an insertion hole 212 through which the left axle shaft 13 is inserted, and holding holes 213 and 214 that respectively hold both ends of the pinion shaft 30. Movement of the pinion shaft 30 relative to the case member 21 is regulated by a pin 210 that is press-fitted into the case member 21 along the axial direction.

[0018] A washer 351 is disposed between the left output rotary member 31 and the case member 21. Washers 352 and 353 are disposed between the differential gears 33 and 34 and the case member 21. The left output rotary member 31 integrally includes gear teeth 311 that mesh with the differential gears 33 and 34, and a cylindrical boss portion 312 that is fitted into the insertion hole 212 of the case member 21.

[0019] The cover member 22 integrally includes a large-diameter cylindrical portion 221, a small-diameter cylindrical portion 222, an annular plate-shaped wall portion 223, and an outer cylindrical portion 224 extending axially from the outer peripheral end of the wall portion 223. The outer and inner diameters of the large-diameter cylindrical portion 221 are larger than the outer and inner diameters of the small-diameter cylindrical portion 222. The right axle shaft 14 is inserted inside the large-diameter cylindrical portion 221 and the small-diameter cylindrical portion 222. The wall portion 223 is formed to protrude radially outward from the large-diameter cylindrical portion 221. One axial end of the outer cylindrical portion 224 is welded to the case member 21. A washer 354 is disposed between the right output rotation member 32 and one axial end of the large-diameter cylindrical portion 221.

[0020] The input rotating member 2 has a case member 21 rotatably supported relative to the differential carrier 10 by a bearing 18, and a small-diameter cylindrical portion 222 of the cover member 22 rotatably supported relative to the differential carrier 10 by a bearing 19. The bearings 18, 19 are tapered roller bearings and include inner rings 181, 191 and outer rings 182, 192, a plurality of partially conical rolling elements 183, 193 arranged between the inner rings 181, 191 and the outer rings 182, 192, and cages 184, 194 that hold the plurality of rolling elements 183, 193. Shims 180, 190 for adjusting the gap are arranged between the outer rings 182, 192 and the differential carrier 10, respectively.

[0021] The differential device 1 also includes a meshing member 4 that disables the right output rotary member 32 from rotating relative to the input rotary member 2, and a friction clutch 5 that uses friction force to suppress differential rotation between the right output rotary member 32 and the input rotary member 2. The right output rotary member 32 and the left output rotary member 31 are connected by differential gears 33, 34, and therefore, the meshing member 4 disables the right output rotary member 32 from rotating relative to the input rotary member 2, thereby also preventing the left output rotary member 31 from rotating relative to the input rotary member 2. The friction clutch 5 also suppresses differential rotation between the right output rotary member 32 and the input rotary member 2, thereby suppressing differential rotation between the left output rotary member 31 and the input rotary member 2. Disabling or suppressing differential rotation between the output rotary members 31, 32 and the input rotary member 2 suppresses spinning of the left and right wheels, improving the vehicle's off-road performance and enabling stable travel on rough roads and low-μ roads, for example.

[0022] The meshing member 4 is disposed on the outer periphery of the large-diameter cylindrical portion 221 of the cover member 22, and is spline-fitted to be axially movable relative to the large-diameter cylindrical portion 221 but non-rotatable relative thereto. The meshing member 4 is disposed between the output rotational member 32 and the wall portion 223 of the cover member 22. As shown in FIG. 2 , the meshing member 4 has a plurality of dog teeth 41 that can mesh with the output rotational member 32. The meshing member 4 moves axially relative to the input rotational member 2, causing the plurality of dog teeth 41 to mesh with the output rotational member 32, thereby preventing the output rotational member 32 from rotating relative to the input rotational member 2.

[0023] The friction clutch 5 is disposed between the output rotary member 32 and the outer cylindrical portion 224 of the cover member 22. The friction clutch 5 has a plurality of outer clutch plates 51 that are axially movable but not rotatable relative to the input rotary member 2, a plurality of inner clutch plates 52 that are axially movable but not rotatable relative to the output rotary member 32, and a pressure plate 53 disposed opposite the cover member 22. The outer clutch plates 51 and the inner clutch plates 52 are disposed alternately along the axial direction. The pressure plate 53 is aligned with the outer clutch plates 51 and inner clutch plates 52 in the axial direction and is axially movable but not rotatable relative to the input rotary member 2.

[0024] The output rotating member 32 integrally has gear teeth 321 that mesh with the differential gears 33, 34, a cylindrical boss portion 322 that is fitted into the large-diameter cylindrical portion 221 of the cover member 22, an outer peripheral spline fitting portion 323 that has external splines 323a that engage with multiple inner clutch plates 52, and a meshing portion 324 that has multiple meshing teeth 324a that mesh with multiple dog teeth 41 of the meshing member 4.

[0025] In the radial direction perpendicular to the rotation axis O, the meshing member 4 is disposed inside the friction clutch 5. The meshing portion 324 of the output rotation member 32 is provided inside the outer circumferential spline fitting portion 323 in the radial direction.

[0026] The differential device 1 also includes a first pressing member 61 that presses the meshing member 4 in the axial direction, a second pressing member 62 that presses the friction clutch 5 in the axial direction, a first driven cam member 63 that is arranged in line with the first pressing member 61 in the axial direction, a second driven cam member 64 that is arranged in line with the second pressing member 62 in the axial direction, a rotating cam member 65 that is arranged opposite the first driven cam member 63 and the second driven cam member 64 in the axial direction, and a plurality of cam balls that are arranged between the second driven cam member 64 and the rotating cam member 65. The rotating cam member 65 includes a first thrust bearing 661 and a retainer 662, a first thrust bearing 67 disposed between the first pressing member 61 and the first driven cam member 63, a second thrust bearing 68 disposed between the second pressing member 62 and the second driven cam member 64, a first biasing member 691 that elastically biases the first pressing member 61 toward the first thrust bearing 67, a second biasing member 692 that elastically biases the second pressing member 62 toward the second thrust bearing 68, and a bearing 60 disposed between the rotating cam member 65 and the cover member 22. The cam balls 661 are spherical. The retainer 662 holds the plurality of cam balls 661 at equal intervals in the circumferential direction.

[0027] In this embodiment, the first pressing member 61 integrally includes a cylindrical shaft portion 611 and a head portion 612 having a larger diameter than the shaft portion 611. The differential device 1 includes a plurality of first pressing members 61. The plurality of first pressing members 61 are aligned with the first thrust bearing 67 in the axial direction and are disposed on the outer periphery of the large-diameter cylindrical portion 221 of the cover member 22.

[0028] A plurality of first through holes 223a are formed in the wall portion 223 of the cover member 22, through which the shaft portions 611 of the plurality of first pressing members 61 are inserted. The first through holes 223a are formed so as to axially penetrate from the inside to the outside of the input rotation member 2. The plurality of first pressing members 61 are axially movable relative to the input rotation member 2. The heads 612 of the first pressing members 61 are disposed outside the input rotation member 2 together with the first biasing member 691.

[0029] The interlocking member 4 has mating holes 42 formed therein into which one ends of the shaft portions 611 of the plurality of first pressing members 61 are press-fitted. The plurality of first pressing members 61 are fixed to the interlocking member 4 by press-fitting the shaft portions 611 into the mating holes 42. However, the method of fixing the interlocking member 4 and the first pressing members 61 is not limited to this, and the first pressing members 61 may be fixed to the interlocking member 4 by a locking member such as a snap ring, for example.

[0030] The meshing member 4 moves in the axial direction together with the plurality of first pressing members 61. When the meshing member 4 moves toward the output rotation member 32, the dog teeth 41 of the meshing member 4 mesh with the meshing portions 324 of the output rotation member 32, and the meshing member 4 and the output rotation member 32 become unable to rotate relative to each other.

[0031] The first biasing member 691 is a disc spring with multiple notches 691 a formed therein. The shaft 611 of the first pressing member 61 is inserted into the notches 691 a of the first biasing member 691. The first biasing member 691 abuts against the heads 612 of the multiple first pressing members 61, and biases the heads 612 of the multiple first pressing members 61 so as to move them axially away from the wall 223 of the cover member 22.

[0032] The first thrust bearing 67 has a plurality of needle rollers 671, a cage 672 that holds the plurality of needle rollers 671, and an annular plate-shaped thrust race 673 on which the plurality of needle rollers 671 roll. The heads 612 of the plurality of first pressing members 61 abut against the thrust race 673.

[0033] The second pressing member 62 integrally includes a flat base portion 621 and a plurality of cylindrical protrusions 622 extending in the axial direction. The axial base ends of the protrusions 622 are continuous with the base portion 621. The base portion 621 is formed in an annular shape, is aligned with the second thrust bearings 68 in the axial direction, and is disposed on the outer periphery of the plurality of first pressing members 61. The wall portion 223 of the cover member 22 is formed with a plurality of second through holes 223b, through which the plurality of protrusions 622 of the second pressing member 62 are respectively inserted. The second through holes 223b are formed to axially penetrate the input rotating member 2 from the inside to the outside. The base portion 621, together with the second biasing member 692, is disposed outside the input rotating member 2.

[0034] The multiple protrusions 622 of the second pressing member 62 axially face the pressure plates 53 of the friction clutch 5. The second pressing member 62 is axially movable relative to the input rotary member 2, and when the second pressing member 62 moves toward the friction clutch 5, the multiple outer clutch plates 51 and the multiple inner clutch plates 52 come into frictional contact with each other, generating a friction force that suppresses differential rotation between the output rotary member 32 and the input rotary member 2. The frictional sliding between the outer clutch plates 51 and the inner clutch plates 52 is lubricated by lubricating oil.

[0035] The second biasing member 692 is a disc spring with a plurality of notches 692 a formed therein. The protrusions 622 of the second pressing member 62 are inserted into the notches 692 a of the second biasing member 692. The second biasing member 692 abuts against the base portion 621 of the second pressing member 62, and biases the base portion 621 so as to move it away from the wall portion 223 of the cover member 22 in the axial direction.

[0036] The second thrust bearing 68 has a plurality of needle rollers 681 and a cage 682 that holds the plurality of needle rollers 681. The plurality of needle rollers 681 roll on the base portion 621 of the second pressing member 62.

[0037] The first driven cam member 63 is disposed radially inside the second driven cam member 64. The first driven cam member 63 and the second driven cam member 64 are engaged with each other so as to be relatively movable in the axial direction but not rotatable relative to each other. More specifically, the second driven cam member 64 is spline-fitted to the inside of the first driven cam member 63. The first driven cam member 63 and the second driven cam member 64 move in the axial direction relative to the differential carrier 10 as the rotating cam member 65 rotates relative to the differential carrier 10.

[0038] The differential device 1 includes, as components for rotating the rotating cam member 65 relative to the differential carrier 10, an electric motor 71 fixed to the differential carrier 10, a reduction gear 72 having a large-diameter gear portion 721 and a small-diameter gear portion 722, a support member 73 that supports the reduction gear 72 rotatably relative to the differential carrier 10, and a control device 8 that controls the electric motor 71. The reduction gear 72 has a disk-shaped plate portion 723 inside the large-diameter gear portion 721. The pitch circle diameter of the large-diameter gear portion 721 of the reduction gear 72 is formed larger than the pitch circle diameter of the small-diameter gear portion 722.

[0039] The control device 8 can recognize the operating state of a mode select switch 9 operated by the vehicle driver. The mode select switch 9 can select among a normal mode in which the meshing member 4 is not meshed with the meshing portion 324 of the output rotation member 32 and the friction clutch 5 is not pressed, an auto mode in which the friction clutch 5 generates a friction force appropriate for the vehicle running state, and a lock mode in which the meshing member 4 is meshed with the meshing portion 324 of the output rotation member 32 so that the left and right output rotation members 31, 32 cannot rotate relative to each other.

[0040] The electric motor 71 has a motor case 711 fixed to the differential carrier 10 and an output rotary shaft 712 on which a gear portion 712a is formed. The motor case 711 accommodates a stator 71a fixed to the motor case 711, a rotor 71b that rotates integrally with the output rotary shaft 712 relative to the stator 71a, and a position detector 71c that detects the position of the rotor 71b relative to the stator 71a. The position detector 71c is, for example, an encoder or a resolver. When a current is supplied from the control device 8 to the electric motor 71, the output rotary shaft 712 rotates relative to the motor case 711. The gear portion 712a of the output rotary shaft 712 meshes with the large-diameter gear portion 721 of the reduction gear 72.

[0041] The second driven cam member 64 has an engaging portion 641 that engages with the support member 73, and is prevented from rotating relative to the differential carrier 10 by the support member 73. The second driven cam member 64 is also movable in the axial direction along the support member 73 while the engaging portion 641 is engaged with the support member 73. The first driven cam member 63 is spline-fitted to the second driven cam member 64, and is therefore movable in the axial direction but unable to rotate relative to the differential carrier 10, similar to the second driven cam member 64.

[0042] The bearing 60 supports the rotating cam member 65 rotatably relative to the input rotating member 2. The bearing 60 is an angular contact ball bearing, and includes an inner ring 601, an outer ring 602, a plurality of spherical rolling elements 603 arranged between the inner ring 601 and the outer ring 602, and a cage 604 that holds the plurality of rolling elements 603. The inner ring 601 is fitted onto the small diameter cylindrical portion 222 of the cover member 22, and is aligned in the axial direction with the inner ring 191 of the bearing 19. Axial movement of the inner ring 601 in a direction away from the large diameter cylindrical portion 221 is restricted by the inner ring 191 of the bearing 19.

[0043] The rotating cam member 65 meshes with the small diameter gear portion 722 of the reduction gear 72 and rotates at a slower speed than the reduction gear 72. Axial movement of the rotating cam member 65 in a direction away from the first driven cam member 63 and the second driven cam member 64 is restricted by the bearing 60.

[0044] Fig. 3 is a configuration diagram showing the opposing surfaces of the rotating cam member 65 that face the first driven cam member 63 and the second driven cam member 64. Fig. 4 is a perspective cross-sectional view of the rotating cam member 65, showing the cross section taken along line A-A in Fig. 3.

[0045] The rotating cam member 65 integrally includes a first cam portion 651 axially facing the first driven cam member 63, a second cam portion 652 axially facing the second driven cam member 64, and a gear portion 653 that meshes with the small diameter gear portion 722 of the reduction gear 72. A bearing fitting portion 650 into which the outer ring 602 of the bearing 60 fits is formed at the inner peripheral end of the rotating cam member 65.

[0046] The first cam portion 651 is provided on the inner peripheral side of the second cam portion 652. The gear portion 653 is provided on the outer peripheral side of the second cam portion 652. The gear portion 653 has an arc shape when viewed in the axial direction. The gear portion 653 has a protrusion 653a on the surface facing the plate portion 723 of the reduction gear 72, the protrusion 653a abutting against the plate portion 723. The protrusion 653a determines the axial position of the gear portion 653 relative to the reduction gear 72.

[0047] A plurality of cam sliding surfaces 651a are formed on the first cam portion 651. The cam sliding surfaces 651a are formed in an arc shape extending along the circumferential direction of the rotating cam member 65. In this embodiment, five cam sliding surfaces 651a are formed on the first cam portion 651. Each cam sliding surface 651a has a vertical surface 651b and a seat surface 651d that are perpendicular to the axial direction, and an inclined surface 651c formed between the vertical surface 651b and the seat surface 651d. The inclined surface 651c is inclined with respect to the axial direction. The seat surface 651d is formed closer to the first driven cam member 63 in the axial direction than the vertical surface 651b.

[0048] The second cam portion 652 has a plurality of cam grooves 652b extending in an arc shape, recessed in the axial direction from an opposing surface 652a that faces the second driven cam member 64. The cam grooves 652b have deep groove portions 652c that have a constant axial depth from the opposing surface 652a, and inclined groove portions 652d whose axial depth from the opposing surface 652a gradually decreases from the deep groove portions 652c. The depth of the inclined groove portions 652d becomes shallower the farther away from the deep groove portions 652c.

[0049] In this embodiment, five cam grooves 652b are formed in the second cam portion 652. In the radial direction of the rotating cam member 65, the multiple cam grooves 652b are formed on the outer sides of the multiple cam sliding surfaces 651a.

[0050] FIG. 5 is a structural diagram showing the opposing surface of the first driven cam member 63 that faces the rotating cam member 65. Similar to the first cam portion 651 of the rotating cam member 65, the first driven cam member 63 is formed with a plurality of cam sliding surfaces 63a. Each cam sliding surface 63a is formed in an arc shape so as to face the cam sliding surface 651a of the first cam portion 651 in the axial direction, and includes a vertical surface 63b and a seating surface 63d that are perpendicular to the axial direction, and an inclined surface 63c formed between the vertical surface 63b and the seating surface 63d and inclined with respect to the axial direction. The seating surface 63d is formed closer to the rotating cam member 65 than the vertical surface 63b in the axial direction. A spline fitting portion 631 is provided on the outer peripheral end of the first driven cam member 63.

[0051] FIG. 6 is a structural diagram showing the opposing surface of the second driven cam member 64 that faces the rotating cam member 65. The second driven cam member 64 has a plurality of cam grooves 64b recessed in the axial direction from the opposing surface 64a that faces the rotating cam member 65, and extending in an arc shape along the circumferential direction of the second driven cam member 64. Each cam groove 64b has a deep groove portion 64c whose axial depth from the opposing surface 64a is constant, and an inclined groove portion 64d whose axial depth from the opposing surface 64a gradually decreases from the deep groove portion 64c. The depth of the inclined groove portion 64d decreases with increasing distance from the deep groove portion 64c. The inner peripheral end of the second driven cam member 64 is provided with a spline fitting portion 642 that fits with the spline fitting portion 631 of the first driven cam member 63.

[0052] The first driven cam member 63, the first thrust bearing 67, and the first cam portion 651 of the rotating cam member 65 constitute a first thrust generating mechanism 6A that applies an axial thrust to the plurality of first pressing members 61. The second driven cam member 64, the second thrust bearing 68, and the second cam portion 652 of the rotating cam member 65 constitute a second thrust generating mechanism 6B that applies an axial thrust to the second pressing member 62. In the radial direction of the differential device 1, the first thrust generating mechanism 6A is provided inside the second thrust generating mechanism 6B.

[0053] The first thrust generating mechanism 6A is a sliding cam mechanism that applies axial thrust to the plurality of first pressing members 61 by relative rotation between the first driven cam member 63 and the rotating cam member 65. The second thrust generating mechanism 6B is a ball cam mechanism that applies axial thrust to the second pressing members 62 by the cam ball 661 rolling in the inclined groove portion 652d of the cam groove 652b of the rotating cam member 65 and the inclined groove portion 64d of the cam groove 64b of the second driven cam member 64.

[0054] 7A to 7D are explanatory diagrams for explaining the operation of the first thrust generating mechanism 6A and the second thrust generating mechanism 6B. FIG. 7A schematically shows a state in which the first thrust generating mechanism 6A and the second thrust generating mechanism 6B are both inactive. FIG. 7B schematically shows a state in which the second thrust generating mechanism 6B is active. FIGS. 7C and 7D schematically show a state in which the first thrust generating mechanism 6A is active. In FIGS. 7A to 7D, the up-down direction in the drawings corresponds to the axial direction of the differential device 1.

[0055] When the first thrust generating mechanism 6A is in an inoperative state, the entire base surface 651d of the cam sliding surface 651a of the rotating cam member 65 faces the vertical surface 63b of the cam sliding surface 63a of the first driven cam member 63 in the axial direction, and the entire base surface 63d of the cam sliding surface 63a of the first driven cam member 63 faces the vertical surface 651b of the cam sliding surface 651a of the rotating cam member 65 in the axial direction. When the first thrust generating mechanism 6A is in an inoperative state, the biasing force of the first biasing member 691 causes the first driven cam member 63 to be positioned farthest axially from the wall portion 223 of the cover member 22, and the plurality of dog teeth 41 of the meshing member 4 do not mesh with the meshing portion 324 of the output rotation member 32.

[0056] When the second thrust generating mechanism 6B is in an inoperative state, the cam ball 661 is positioned in the deep groove portion 652c of the cam groove 652b of the rotating cam member 65 and the deep groove portion 64c of the cam groove 64b of the second driven cam member 64. When the second thrust generating mechanism 6B is in an inoperative state, the biasing force of the second biasing member 692 causes the second driven cam member 64 to be positioned at the farthest axial position from the wall portion 223 of the cover member 22, and the friction clutch 5 is not pressed in the axial direction.

[0057] As shown in FIG. 7A , when the first thrust generating mechanism 6A and the second thrust generating mechanism 6B are both in an inoperative state, the relative rotation of the left and right output rotating members 31, 32 is not impeded by the meshing member 4 or the friction clutch 5, and the driving forces transmitted to the left and right wheels are approximately equal.

[0058] Figure 7B shows a state in which the rotating cam member 65 has moved to the left side of the drawing from the state shown in Figure 7A. In this state, the cam ball 661 rolls and moves into the inclined groove portion 652d of the cam groove 652b of the rotating cam member 65 and the inclined groove portion 64d of the second driven cam member 64, generating an axial cam thrust, as indicated by the arrow in Figure 7B, on the second driven cam member 64. This cam thrust then causes the second pressing member 62 to press the friction clutch 5 in the axial direction, generating frictional forces between the outer clutch plates 51 and the inner clutch plates 52. Meanwhile, the first driven cam member 63 maintains a state in which the entire seat surface 63d of the cam sliding surface 63a faces the vertical surface 651b of the cam sliding surface 651a of the rotating cam member 65 in the axial direction, and the second thrust generating mechanism 6B remains in an inoperative state.

[0059] 7C shows a state in which the rotating cam member 65 has moved to the right from the state shown in FIG. 7A , and the inclined surface 651 c of the cam sliding surface 651 a of the rotating cam member 65 is in contact with the inclined surface 63 c of the cam sliding surface 63 a of the first driven cam member 63. In this state, the inclined surface 651 c of the cam sliding surface 651 a of the rotating cam member 65 slides over the inclined surface 63 c of the cam sliding surface 63 a of the first driven cam member 63, thereby generating a cam thrust in the axial direction, as indicated by the arrow in FIG. 7C , on the first driven cam member 63. This cam thrust then causes the multiple first pressing members 61 to press the meshing members 4 toward the meshing portions 324 of the output rotation member 32, and the meshing members 4 mesh with the meshing portions 324. On the other hand, the second thrust generating mechanism 6B remains in an inoperative state with the cam ball 661 positioned in the deep groove portions 652c, 64c of the cam grooves 652b, 64b.

[0060] 7D shows a state in which the rotating cam member 65 has moved further to the right from the state shown in FIG. 7C, and the seat surface 651d of the cam sliding surface 651a of the rotating cam member 65 comes into contact with the seat surface 63d of the cam sliding surface 63a of the first driven cam member 63. In this state, no cam thrust is generated in the first driven cam member 63, but movement of the meshing member 4 in a direction away from the meshing portion 324 of the output rotation member 32 is prevented, and the state in which the dog teeth 41 of the meshing member 4 are engaged with the meshing teeth 324a of the meshing portion 324 is maintained. Note that the second thrust generating mechanism 6B remains in an inactive state.

[0061] When the normal mode is selected by the mode select switch 9, the control device 8 controls the electric motor 71 to position the rotating cam member 65 relative to the first driven cam member 63 and the second driven cam member 64 as shown in Figure 7A, and puts both the first thrust generating mechanism 6A and the second thrust generating mechanism 6B in an inoperative state. Also, when the auto mode is selected by the mode select switch 9, the control device 8 activates the second thrust generating mechanism 6B in accordance with the vehicle running state, causing the friction clutch 5 to generate friction force.

[0062] Furthermore, when the lock mode is selected by the mode select switch 9, the control device 8 controls the electric motor 71 to operate the first thrust generating mechanism 6A, and causes the meshing member 4 to mesh with the meshing portion 324 of the output rotating member 32. Since the seat surface 651d of the cam sliding surface 651a of the first cam portion 651 and the seat surface 63d of the cam sliding surface 63a of the first driven cam member 63 are both flat surfaces perpendicular to the axial direction, even if the dog teeth 41 of the meshing member 4 receive an axial meshing reaction force from the meshing teeth 324a of the meshing portion 324, this meshing reaction force does not act as torque to rotate the rotating cam member 65.

[0063] Therefore, when the vehicle is traveling in the locked mode, it is possible to cut off the current supplied to the electric motor 71. Even when the current supply to the electric motor 71 is cut off, the base surface 651d of the cam sliding surface 651a of the rotating cam member 65 and the base surface 63d of the cam sliding surface 63a of the first driven cam member 63 are maintained in contact with each other due to the rotational resistance of the rotating cam member 65, the reduction gear 72, and the rotor 71b of the electric motor 71.

[0064] The control device 8 detects that the seat surface 651d of the cam sliding surface 651a of the rotating cam member 65 and the seat surface 63d of the cam sliding surface 63a of the first driven cam member 63 are in contact with each other, for example, based on the detection value of the position detector 71c of the electric motor 71, and sets the current supplied to the electric motor 71 to zero. This makes it possible to reduce the current consumption of the electric motor 71. When it is detected that the rotor 71b of the electric motor 71 has rotated relative to the stator 71a due to vibrations or the like while the vehicle is traveling in the locked mode, the control device 8 temporarily supplies current to the electric motor 71 to return the position of the rotor 71b, and then cuts off the current supply to the electric motor 71 again.

[0065] (Effects of the Embodiment) According to the present embodiment described above, the arrangement in which the meshing members 4 are disposed inside the friction clutch 5 shortens the axial length of the differential device 1 and makes it possible to reduce the device size, compared to when the meshing members 4 and the friction clutch 5 are disposed side by side in the axial direction. Furthermore, the arrangement in which the meshing portions 324 of the output rotating member 32 are provided inside the outer-periphery spline fitting portion 323 and the arrangement in which the first thrust generating mechanism 6A is disposed inside the second thrust generating mechanism 6B also shortens the axial length of the differential device 1 and makes it possible to reduce the device size. Furthermore, because the current supplied to the electric motor 71 can be shut off when the vehicle is traveling in the locked mode, it is possible to reduce the power consumption of the electric motor 71.

[0066] (Note) While the present invention has been described above based on the embodiments, the invention according to the claims is not limited to these embodiments. 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 appropriately modified and implemented by omitting some components or adding or substituting components within the scope of the spirit of the invention. Furthermore, the present invention can also be modified, for example, as follows:

[0067] In the above embodiment, the case where the output rotating member 32 integrally has the gear teeth 321, the boss portion 322, the outer peripheral spline fitting portion 323, and the meshing portion 324 has been described. However, this is not limited to this. For example, the output rotating member 32 may be configured by combining a first member integrally having the gear teeth 321 and the boss portion 322 with a second member having the outer peripheral spline fitting portion 323 and the meshing portion 324 in such a way that they cannot rotate relative to each other.

[0068] In the above embodiment, the friction clutch 5 and meshing member 4 are disposed in correspondence with the right output rotation member 32 of the left and right output rotation members 31, 32, but this is not limiting, and the friction clutch 5 and meshing member 4 may be disposed in correspondence with the left output rotation member 31. In other words, it is sufficient that the friction clutch 5 and meshing member 4 are disposed in correspondence with either one of the left and right output rotation members 31, 32.

[0069] In the above embodiment, a case has been described in which a plurality of first pressing members 61 are fixed to the interlocking member 4 by press-fitting, but this is not limiting. Similarly to the second pressing member 62, a single first pressing member may be formed by combining a flat base portion with a plurality of cylindrical protrusions extending in the axial direction, and this single first pressing member may be used to press the interlocking member 4.

[0070] In the above embodiment, a case has been described in which the current supplied to the electric motor 71 is cut off when the vehicle is running in the locked mode, but this is not limited to this. Alternatively, a small current sufficient to suppress the rotation of the rotor 71b relative to the stator 71a of the electric motor 71 may be continuously supplied to the electric motor 71.

[0071] DESCRIPTION OF SYMBOLS 1...Differential device 2...Input rotating member 31, 32...Output rotating member 323...Outer peripheral spline fitting portion 323a...External spline 324...Meshing portion 324a...Meshing teeth 33, 34...Differential gear 4...Meshing member 41...Dog teeth 5...Friction clutch 51...Outer clutch plate 52...Inner clutch plate 6A...First thrust generating mechanism 6B...Second thrust generating mechanism 60...Bearing 61...First pressing member 62...Second pressing member 63...First driven cam member 63a...Cam sliding surface 63b...Vertical surface 63c...Inclined surface 63d...Pedestal surface 64...Second driven cam member 64b...Cam groove 64c...Deep groove portion 64d...Inclined groove portion 65...Rotating cam member 651a...Cam sliding surface 651b...vertical surface 651c...inclined surface 651d...base surface 652b...cam groove 652c...deep groove portion 652d...inclined groove portion 661...cam ball O...rotation axis

Claims

1. A case-shaped input rotating member receives the driving force from a drive source and rotates about the axis of rotation due to the driving force, A pair of output rotating members housed in the input rotating member and rotating about the rotation axis, A plurality of differential gears housed in the input rotating member, enabling differential rotation of the pair of output rotating members, A meshing member having a dog tooth capable of meshing with one of the pair of output rotating members, wherein the dog tooth meshes with the one output rotating member when it moves axially relative to the input rotating member, thereby preventing the one output rotating member from rotating relative to the input rotating member, The system includes a friction clutch positioned between the one output rotating member and the input rotating member, which suppresses differential rotation between the one output rotating member and the input rotating member by frictional force, The meshing member and the friction clutch are aligned in the radial direction perpendicular to the axis of rotation and overlap in the axial direction, and in the radial direction the meshing member is positioned inside the friction clutch. Differential device.

2. The friction clutch comprises a plurality of outer clutch plates that are axially movable with respect to the input rotating member but not rotatable relative to it, and a plurality of inner clutch plates that are axially movable with respect to one of the output rotating members but not rotatable relative to it. The aforementioned output rotating member has an outer circumferential spline fitting portion in which an outer spline is formed that engages with the plurality of inner clutch plates, and a meshing portion in which meshing teeth are formed that mesh with the dog teeth of the meshing member. The meshing portion is provided in the portion corresponding to the radially inner side of the outer spline fitting portion. The differential device according to claim 1.

3. The system comprises a first pressing member for pressing the meshing member in the axial direction, a second pressing member for pressing the friction clutch in the axial direction, a first thrust generating mechanism for applying axial thrust to the first pressing member, and a second thrust generating mechanism for applying axial thrust to the second pressing member. The first thrust generation mechanism is provided in the portion of the second thrust generation mechanism that is radially inward. The differential device according to claim 2.

4. The first thrust generating mechanism is a sliding cam mechanism that applies axial thrust to the first pressing member by the relative rotation of a rotating cam member having a cam sliding surface having an inclined surface inclined with respect to the axial direction and a base surface perpendicular to the axial direction, and a first driven cam member arranged opposite to the rotating cam member. As a portion of the first driven cam member slides along the inclined surface, the first pressing member presses the meshing member toward the meshing portion of the one output rotating member, and as a portion of the first driven cam member contacts the base surface, the state in which the dog teeth of the meshing member are meshed with the meshing teeth of the meshing portion is maintained. The differential device according to claim 3.

5. The second thrust generation mechanism is a ball cam mechanism that imparts axial thrust to the second pressing member by having a spherical rolling element roll in the inclined groove portion of a cam groove formed in the rotating cam member at an angle with respect to the axial direction. In the radial direction perpendicular to the axis of rotation, the cam groove is formed on the outside of the cam sliding surface. The differential device according to claim 4.

6. The rotating cam member is provided with a bearing that rotatably supports it with respect to the input rotating member, The movement of the rotating cam member in a direction away from the first driven cam member is restricted by the bearing. The differential device according to claim 5.

7. The second thrust generating mechanism has a second driven cam member positioned opposite the rotating cam member, In the radial direction perpendicular to the axis of rotation, the first driven cam member is positioned inside the second driven cam member. The differential device according to claim 5 or 6.

8. The first driven cam member and the second driven cam member are engaged in such a manner that they are axially movable but not rotatable relative to each other. The differential according to claim 7.