Differential

Abstract

[Problem] To provide a differential device that, without the use of an axle spacer, allows easy positioning of a pair of output shafts during assembly of a vehicle. [Solution] A differential device 1 comprises: a first linking member 2 that has a straight spline protrusion 211 on the inner periphery thereof; a second linking member 3 that has a straight spline protrusion 311 on the inner periphery thereof; a first side gear 4; and a second side gear 5. The first side gear 4 comprises: a first cylindrical section 41 that is engaged by helical spline coupling with the first linking member 2; and a first wall section 42 that extends radially inward. The second side gear 5 comprises: a second cylindrical section 51 that is engaged by helical spline coupling with the second linking member 3; and a second wall section 52 that extends radially inward. The first wall section 42 of the first side gear 4 protrudes further radially inward than the straight spline protrusion 211 of the first linking member 2, and the second wall section 51 of the second side gear 5 protrudes further radially inward than the straight spline protrusion 311 of the second linking member 3.

Description

[Technical field]

[0001] The present invention relates to a differential device for a vehicle that distributes driving force of a drive source to a pair of output shafts while allowing differential motion. [Background technology]

[0002] Conventionally, a differential device that distributes the driving force of a vehicle's driving source to a pair of output shafts while allowing differential rotation has a differential limiting function that suppresses differential rotation between the output shafts. A vehicle equipped with such a differential device can transmit driving force to the left wheel even when the right wheel slips, for example, thereby improving running stability. The present applicant has proposed differential devices equipped with a differential limiting function in Patent Documents 1 and 2.

[0003] The differential device described in Patent Document 1 includes a first side gear and a second side gear arranged side by side in the axial direction, a plurality of pinion gear sets formed by meshing a first pinion gear meshed with the first side gear and a second pinion gear meshed with the second side gear, and a differential case that holds the plurality of pinion gear sets. The first pinion gear and the second pinion gear, and the first side gear and the second side gear are helical gears that generate an axial thrust force by meshing. When torque is transmitted from the differential case to the pair of output shafts, the end faces of the first side gear and the second side gear are pressed against a washer arranged in the differential case by the thrust force, generating a frictional force that suppresses the differential rotation of the pair of output shafts.

[0004] In addition to the above configuration, the differential device described in Patent Document 2 further includes a first connecting member helically splined to the first side gear and a second connecting member helically splined to the second side gear in order to increase the differential limiting force. When torque is transmitted from the differential case to the pair of output shafts, the differential limiting force is increased by the thrust force additionally generated by the helical spline connection.

[0005] Furthermore, in the differential gear described in Patent Document 1, an axle spacer is disposed between the first side gear and the second side gear. Left and right axle shafts, which are a pair of output shafts that are inserted into the first side gear and the second side gear, respectively, are abutted against both end faces of this axle spacer during assembly of the vehicle. This positions the left and right axle shafts, making it possible to easily assemble the vehicle. On the other hand, the differential gear described in Patent Document 2 does not have such an axle spacer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2015-203483 A [Patent Document 2] Patent Publication No. 2021-173389 Summary of the Invention [Problem to be solved by the invention]

[0007] The axle spacer of the differential described in Patent Document 1 contributes to easier vehicle assembly as described above, but serves no function after the vehicle is assembled, and instead impedes the flow of lubricating oil inside the differential case. In addition, the differential described in Patent Document 2 does not have an axle spacer, which makes it possible to reduce the number of parts and assembly steps of the differential, but it is not possible to position the pair of output shafts (left and right axle shafts) by abutting them against the axle spacer during vehicle assembly.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a differential gear that makes it possible to easily position a pair of output shafts during assembly of a vehicle without using an axle spacer. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides a differential device for distributing a driving force of a vehicle to a first output shaft and a second output shaft, the differential device comprising: a cylindrical first connecting member having a plurality of straight spline projections on an inner circumference to which the first output shaft is straight spline-connected; a cylindrical second connecting member having a plurality of straight spline projections on an inner circumference to which the second output shaft is straight spline-connected; a first side gear combined with the first connecting member; a second side gear combined with the second connecting member; a plurality of pinion gear sets formed by meshing a first pinion gear meshing with the first side gear and a second pinion gear meshing with the second side gear; a differential case for holding the plurality of pinion gear sets; and a center washer disposed between the first side gear and the second side gear and restricted in its relative rotation with the differential case, the first side gear being disposed on an outer periphery of the first connecting member and being helical-splined with the first connecting member. the second side gear has a second cylindrical portion disposed on an outer periphery of the second connecting member and helically splined to the second connecting member, and a second wall portion extending from one end of the second cylindrical portion on the center washer side to the inner diameter side, the second wall portion protruding to the inner diameter side beyond the multiple straight spline projections of the second connecting member, and the center washer generates a frictional force between the first wall portion of the first side gear and the second wall portion of the second side gear by a thrust force generated by the helical spline connection during driving when torque is transmitted from the first side gear and the second side gear to the first connecting member and the second connecting member. Effect of the Invention

[0010] According to the differential device of the present invention, it is possible to easily perform axial positioning of the first output shaft and the second output shaft during assembly of the vehicle without using an axle spacer. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing a configuration example of a differential gear according to an embodiment of the present invention; [Diagram 2] FIG. [Diagram 3] FIG. 2 is an explanatory diagram showing a first connecting member, a second connecting member, a first side gear, a second side gear, a center washer, a first side washer, and a second side washer spaced apart in the axial direction. [Figure 4] FIG. 4 is a cross-sectional view showing a configuration example of a differential device according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [Embodiment Mode] An embodiment of the present invention will be described with reference to Figures 1 to 3. Note that the embodiment described below is shown as a preferred specific example for carrying out the present invention, and while there are some parts that specifically exemplify various technical matters that are technically preferable, the technical scope of the present invention is not limited to this specific embodiment.

[0013] Fig. 1 is a cross-sectional view showing a configuration example of a differential gear according to an embodiment of the present invention, Fig. 2 is an exploded perspective view of the differential gear.

[0014] This differential gear 1 is mounted on a vehicle and is used to distribute the driving force of a driving source to a first output shaft 91 and a second output shaft 92 while allowing differential force distribution. In Fig. 1, the first output shaft 91 and the second output shaft 92 are indicated by imaginary lines. The driving source is, for example, an internal combustion engine, or an electric motor, or a combination of an engine and an electric motor.

[0015] The differential device 1 includes a cylindrical first connecting member 2 that rotates integrally with a first output shaft 91, a cylindrical second connecting member 3 that rotates integrally with a second output shaft 92, a first side gear 4 combined with the first connecting member 2, a second side gear 5 combined with the second connecting member 3, a plurality of pinion gear sets 6, a differential case 7 that holds the plurality of pinion gear sets 6, and a center washer 80, a first side washer 81, and a second side washer 82 that are held in the differential case 7 so as not to rotate relative to each other.

[0016] A ring gear 11, shown by an imaginary line in FIG. 1, is fixed to the differential case 7 by a plurality of bolts 12. The differential case 7 rotates about a rotation axis O by the driving force of a driving source input from the ring gear 11. The first connecting member 2, the second connecting member 3, the first side gear 4, and the second side gear 5 are rotatable relative to the differential case 7 about the rotation axis O. Hereinafter, a direction parallel to the rotation axis O is referred to as an axial direction. Also, a direction perpendicular to the rotation axis O is referred to as a radial direction.

[0017] The differential case 7 has a cylindrical case body 71 with a bottom and a case cover body 72 arranged to close the opening of the case body 71, and the case body 71 and the case cover body 72 are joined by a plurality of bolts 73. The case body 71 integrally includes a cylindrical tube portion 711, a disk-shaped first side wall portion 712 formed so as to extend radially inward from an end portion on one axial side of the tube portion 711, a cylindrical first extension portion 713 extending axially from the center of the first side wall portion 712, and a first flange portion 714 formed so as to extend radially outward from an end portion on the other axial side of the tube portion 711. An oil hole 712a for circulating lubricating oil is formed in the first side wall portion 712.

[0018] Case cover 72 integrally includes a disk-shaped second side wall portion 721, a cylindrical second extension portion 722 extending axially from the center of second side wall portion 721, and a second flange portion 723 formed by projecting radially outward from second side wall portion 721. Second side wall portion 721 is formed with an oil hole 721a for circulating lubricating oil.

[0019] The bolts 12 for fixing the ring gear 11 are inserted through the first flange portion 714 of the case body 71 and the second flange portion 723 of the case cover body 72. The differential case 7 and the ring gear 11 are housed in a differential carrier (not shown), and the ring gear 11 meshes with a pinion gear in the differential carrier. Bearings (not shown) are disposed on the outer periphery of the first extension portion 713 and the second extension portion 722, and the differential case 7 is supported by these bearings so as to be rotatable relative to the differential carrier. Lubricating oil (differential oil) is sealed in the differential carrier.

[0020] The center washer 80 is held by the tubular portion 711 of the case body 71. The first side washer 81 is held by the first side wall portion 712 of the case body 71, and the second side washer 82 is held by the second side wall portion 721 of the case cover 72. The center washer 80 is disposed between the first side gear 4 and the second side gear 5. The first side washer 81 is disposed at a position where the first connecting member 2 and the first side gear 4 are sandwiched between the center washer 80 and the first side washer 81. The second side washer 82 is disposed at a position where the second connecting member 3 and the second side gear 5 are sandwiched between the center washer 80 and the second side washer 82.

[0021] As shown in FIG. 2, the center washer 80, the first side washer 81, and the second side washer 82 each have a disk-shaped disk portion 801, 811, and 821, and a plurality of protrusions 802, 812, and 822 protruding radially outward from the outer edge of the disk-shaped disk portion 801, 811, and 821. The center washer 80 is restricted from rotating relative to the differential case 7 by the engagement of the plurality of protrusions 802 with the cylindrical portion 711 of the case main body 71. The first side washer 81 is restricted from rotating relative to the differential case 7 by the engagement of the plurality of protrusions 812 with the first side wall portion 712 of the case main body 71. The second side washer 82 is restricted from rotating relative to the differential case 7 by the engagement of the plurality of protrusions 822 with the second side wall portion 721 of the case cover body 72.

[0022] In this embodiment, four pinion gear sets 6 are housed in the differential case 7. Each pinion gear set 6 is configured by meshing one first pinion gear 61 with two second pinion gears 62. The first pinion gear 61 has a large diameter gear portion 611 and a small diameter gear portion 612 having different pitch circle diameters. The two second pinion gears 62 have an axial length shorter than that of the first pinion gear 61, and are meshed with the small diameter gear portion 612 of the first pinion gear 61.

[0023] The case body 71 is formed with four bores 70 each holding one of the four pinion gear sets 6. The inner surface of each bore 70 includes a sliding surface 70a on which the tooth tips of the first pinion gear 61 slide, and a sliding surface 70b on which the tooth tips of the second pinion gear 62 slide. When the vehicle is traveling straight, the first pinion gear 61 and the second pinion gear 62 rotate (revolve) together with the differential case 7 without rotating within the bore 70. When the first output shaft 91 and the second output shaft 92 rotate differentially during turning of the vehicle, the first pinion gear 61 and the second pinion gear 62 rotate together with the differential case 7 while rotating within the bore 70.

[0024] FIG. 3 is an explanatory diagram showing the first connecting member 2, the second connecting member 3, the first side gear 4, the second side gear 5, the center washer 80, the first side washer 81, and the second side washer 82 spaced apart in the axial direction.

[0025] The first connecting member 2 integrally includes a first cylindrical base portion 21 formed in a cylindrical shape, an annular first outer peripheral wall portion 22 formed to protrude radially outward from an end portion of the first cylindrical base portion 21 on the first side washer 81 side, and an annular first support wall portion 23 formed adjacent to the first outer peripheral wall portion 22 to protrude radially outward from the first cylindrical base portion 21. A straight spline fitting portion 212 having a plurality of straight spline projections 211 extending in the axial direction is formed on the inner circumference of the first cylindrical base portion 21. A helical spline fitting portion 214 having a plurality of helical spline projections 213 inclined with respect to the axial direction is formed on the outer circumference of the first cylindrical base portion 21. An annular recess 20 for machining the plurality of helical spline projections 213 is formed between the helical spline fitting portion 214 and the first support wall portion 23.

[0026] Similarly, the second connecting member 3 integrally includes a second cylindrical base portion 31 formed in a cylindrical shape, an annular second outer peripheral wall portion 32 formed to protrude radially outward from an end portion of the second cylindrical base portion 31 on the second side washer 82 side, and an annular second support wall portion 33 formed adjacent to the second outer peripheral wall portion 32 to protrude radially outward from the second cylindrical base portion 31. A straight spline fitting portion 312 having a plurality of straight spline projections 311 extending in the axial direction is formed on the inner circumference of the second cylindrical base portion 31. A helical spline fitting portion 314 having a plurality of helical spline projections 313 inclined with respect to the axial direction is formed on the outer circumference of the second cylindrical base portion 31. An annular recess 30 for machining the plurality of helical spline projections 313 is formed between the helical spline fitting portion 314 and the second support wall portion 33.

[0027] The first output shaft 91 is inserted into the first cylindrical base portion 21 and is straight spline-connected to the multiple straight spline protrusions 211 of the straight spline fitting portion 212. The second output shaft 92 is inserted into the second cylindrical base portion 31 and is straight spline-connected to the multiple straight spline protrusions 311 of the straight spline fitting portion 312.

[0028] The first side gear 4 integrally comprises a first cylindrical portion 41 that is disposed on the outer periphery of the first connecting member 2 and is helically splined to the first connecting member 2, and a first wall portion 42 that extends from one end of the first cylindrical portion 41 on the center washer 80 side toward the inner diameter side. A helical spline fitting portion 412 having a plurality of helical spline projections 411 inclined with respect to the axial direction is formed on the inner periphery of the first cylindrical portion 41. A helical gear portion 414 having a plurality of helical teeth 413 inclined with respect to the axial direction is formed on the outer periphery of the first cylindrical portion 41.

[0029] Similarly, the second side gear 5 integrally includes a second cylindrical portion 51 that is disposed on the outer periphery of the second connecting member 3 and is helically splined to the second connecting member 3, and a second wall portion 52 that extends from one end of the second cylindrical portion 51 on the center washer 80 side toward the inner diameter side. A helical spline fitting portion 512 having a plurality of helical spline projections 511 inclined with respect to the axial direction is formed on the inner periphery of the second cylindrical portion 51. A helical gear portion 514 having a plurality of helical teeth 513 inclined with respect to the axial direction is formed on the outer periphery of the second cylindrical portion 51.

[0030] The helical spline fitting portion 412 of the first side gear 4 fits with the helical spline fitting portion 214 of the first connecting member 2, and the multiple helical spline projections 411 of the first side gear 4 mesh with the multiple helical spline projections 213 of the first connecting member 2. The helical gear portion 414 of the first side gear 4 meshes with the large diameter gear portion 611 of the first pinion gear 61. When torque is transmitted from the differential case 7 to the first output shaft 91, an axial thrust force is generated in the helical spline fitting portion 412 and the helical gear portion 414 of the first side gear 4 and the helical spline fitting portion 214 of the first connecting member 2.

[0031] Similarly, the helical spline fitting portion 512 of the second side gear 5 fits with the helical spline fitting portion 314 of the second connecting member 3, and the multiple helical spline projections 511 of the second side gear 5 mesh with the multiple helical spline projections 313 of the second connecting member 3. The helical gear portion 514 of the second side gear 5 meshes with the second pinion gear 62. When torque is transmitted from the differential case 7 to the second output shaft 92, an axial thrust force is generated in the helical spline fitting portion 512 and the helical gear portion 514 of the second side gear 5 and the helical spline fitting portion 314 of the second connecting member 3.

[0032] As shown in FIG. 3, the first outer peripheral wall portion 22 of the first connecting member 2 has an end surface 22a on the center washer 80 side that faces an end surface 41a of the first cylindrical portion 41 of the first side gear 4 on the opposite side to the center washer 80 (the first side washer 81 side) in the axial direction. The end surface 22a of the first outer peripheral wall portion 22 and the end surface 41a of the first cylindrical portion 41 are flat surfaces perpendicular to the axial direction. An inner peripheral surface 41b of the end portion of the first cylindrical portion 41 of the first side gear 4 on the first side washer 81 side faces an outer peripheral surface 23a of the first support wall portion 23 of the first connecting member 2 in the radial direction. The outer peripheral surface 23a of the first support wall portion 23 contacts the inner peripheral surface 41b of the first cylindrical portion 41, thereby stabilizing the posture of the first side gear 4 relative to the first connecting member 2.

[0033] The second outer peripheral wall portion 32 of the second connecting member 3 has an end face 32a on the center washer 80 side that faces an end face 51a of the second cylindrical portion 51 of the second side gear 5 on the opposite side to the center washer 80 (the second side washer 82 side) in the axial direction. The end face 32a of the second outer peripheral wall portion 32 and the end face 51a of the second cylindrical portion 51 are flat surfaces perpendicular to the axial direction. An inner peripheral surface 51b of the end portion on the second side washer 82 side of the second cylindrical portion 51 of the second side gear 5 faces an outer peripheral surface 33a of the second support wall portion 33 of the second connecting member 3 in the radial direction. The outer peripheral surface 33a of the second support wall portion 33 contacts the inner peripheral surface 51b of the second cylindrical portion 51, thereby stabilizing the posture of the second side gear 5 with respect to the second connecting member 3.

[0034] The surface of the first connecting member 2 on the first side washer 81 side includes a contact surface 2a that generates a frictional force by frictional contact with the first side washer 81, and a non-contact surface 2b that does not contact the first side washer 81. The contact surface 2a and the non-contact surface 2b are annular flat surfaces perpendicular to the axial direction, and the contact surface 2a is formed on the outer circumferential side of the non-contact surface 2b. The contact surface 2a protrudes toward the first side washer 81 side beyond the non-contact surface 2b. An end surface 21a on the center washer 80 side of the first cylindrical base portion 21 of the first connecting member 2 faces the first wall portion 42 of the first side gear 4 in the axial direction.

[0035] Similarly, the surface of the second connecting member 3 on the second side washer 82 side includes a contact surface 3a that generates a frictional force by frictional contact with the second side washer 82, and a non-contact surface 3b that does not contact the second side washer 82. The contact surface 3a and the non-contact surface 3b are annular flat surfaces perpendicular to the axial direction, and the contact surface 3a is formed on the outer circumferential side of the non-contact surface 3b. The contact surface 3a protrudes toward the second side washer 82 side beyond the non-contact surface 3b. An end surface 31a on the center washer 80 side of the second cylindrical base portion 31 of the second connecting member 3 faces the second wall portion 52 of the second side gear 5 in the axial direction.

[0036] The first wall portion 42 of the first side gear 4 protrudes radially inward beyond the straight spline projections 211 of the first connecting member 2. When a vehicle on which the differential gear 1 is mounted is assembled, the first output shaft 91 is inserted into the first extending portion 713 of the differential case 7 and the inside of the first connecting member 2, and abuts against the first wall portion 42 of the first side gear 4. A through hole 420 is formed in the center of the first side gear 4, passing through the first wall portion 42 in the axial direction. As shown in FIG. 3, the inner diameter of the through hole 420 of the first side gear 4 is defined as D 11 The inner diameter of the straight spline fitting portion 212 of the first connecting member 2 is D 12 Then, the inner diameter D of the through hole 420 11 is the inner diameter D of the straight spline fitting portion 212 12 Less than.

[0037] The surface of the first wall portion 42 of the first side gear 4 opposite to the center washer 80 includes a first opposing surface 42a opposing the end surface 21a of the first cylindrical body portion 21 of the first connecting member 2, and a first abutting surface 42b against which a tip end surface 91a (see FIG. 1) of the first output shaft 91 abuts. The first abutting surface 42b is formed in a portion of the first wall portion 42 protruding radially inward from the straight spline projections 211 of the first connecting member 2. The first abutting surface 42b is subjected to a finishing process in order to improve the dimensional accuracy of the first output shaft 91 when the tip end surface 91a of the first output shaft 91 abuts against the first opposing surface 42a. As a result, the first abutting surface 42b is slightly offset toward the center washer 80 side from the first opposing surface 42a.

[0038] Similarly, the second wall portion 52 of the second side gear 5 protrudes radially inward beyond the straight spline projections 311 of the second connecting member 3. When a vehicle on which the differential gear 1 is mounted is assembled, the second output shaft 92 is inserted into the second extension portion 722 of the differential case 7 and the inside of the second connecting member 3, and abuts against the second wall portion 52 of the second side gear 5. A through hole 520 is formed in the center of the second side gear 5, passing through the second wall portion 52 in the axial direction. As shown in FIG. 3, the inner diameter of the through hole 520 of the second side gear 5 is defined as D 21 The inner diameter of the straight spline fitting portion 312 of the second connecting member 3 is D 22 Then, the inner diameter D of the through hole 520 21 is the inner diameter of the straight spline fitting portion 312. 22 Less than.

[0039] The surface of the second wall portion 52 of the second side gear 5 opposite to the center washer 80 includes a second opposing surface 52a opposing the end surface 31a of the second cylindrical body portion 31 of the second connecting member 3, and a second abutting surface 52b against which a tip surface 92a (see FIG. 1) of the second output shaft 92 abuts. The second abutting surface 52b is formed in a portion of the second wall portion 52 protruding toward the inner diameter side from the straight spline projections 311 of the second connecting member 3. The second abutting surface 52b is subjected to a finishing process in order to improve the dimensional accuracy of the second output shaft 92 when the tip surface 92a of the second output shaft 92 abuts against the second opposing surface 52a. As a result, the second abutting surface 52b is slightly offset toward the center washer 80 side from the second opposing surface 52a.

[0040] The first output shaft 91 temporarily abuts against the first wall portion 42 of the first side gear 4 during assembly of the vehicle, but is located at a position axially spaced from the first wall portion 42 of the first side gear 4 when assembly is completed, and does not contact the first wall portion 42. Similarly, the second output shaft 92 temporarily abuts against the second wall portion 52 of the second side gear 5 during assembly of the vehicle, but is located at a position axially spaced from the second wall portion 52 of the second side gear 5 when assembly is completed, and does not contact the second wall portion 52.

[0041] When the vehicle is driving, accelerating in the forward direction or moving forward at a constant speed, torque is transmitted from the first side gear 4 to the first connecting member 2, and from the second side gear 5 to the second connecting member 3. On the other hand, when the vehicle is coasting, decelerating by engine braking or regenerative braking of the electric motor while moving forward, torque is transmitted from the first connecting member 2 to the first side gear 4, and from the second connecting member 3 to the second side gear 5. However, the torque transmitted between the first side gear 4 and the second side gear 5 and the first connecting member 2 and the second connecting member 3 during coasting is relatively smaller than the torque transmitted during driving.

[0042] FIG. 3 shows the axial thrust force F generated in the first connecting member 2, the second connecting member 3, the first side gear 4, and the second side gear 5 during driving. 11 ~F 16The direction of the thrust force F generated in the axial direction in the first connecting member 2, the second connecting member 3, the first side gear 4, and the second side gear 5 during coasting is shown by the solid black arrows. 21 ~F 26 The direction of the thrust force F toward the center washer 80 is indicated by a white arrow. During driving, the helical gear portion 414 of the first side gear 4 meshes with the large diameter gear portion 611 of the first pinion gear 61, so that the first side gear 4 is subjected to a thrust force F 11 At the same time, the helical gear portion 514 of the second side gear 5 meshes with the second pinion gear 62, so that a thrust force F 12 occurs.

[0043] During driving, the helical spline fitting portion 412 of the first side gear 4 and the helical spline fitting portion 214 of the first connecting member 2 are fitted together, so that a thrust force F 13 At the same time, a thrust force F is applied to the first connecting member 2 toward the first side washer 81. 14 Furthermore, during driving, the helical spline fitting portion 512 of the second side gear 5 and the helical spline fitting portion 314 of the second connecting member 3 are fitted together, so that a thrust force F 15 At the same time, a thrust force F is applied to the second connecting member 3 toward the second side washer 82. 16 occurs.

[0044] The surface of the first wall portion 42 of the first side gear 4 facing the center washer 80 in the axial direction is formed with an abutment surface 42c that abuts against the center washer 80 during driving. The surface of the second wall portion 52 of the second side gear 5 facing the center washer 80 in the axial direction is formed with an abutment surface 52c that abuts against the center washer 80 during driving.

[0045] The center washer 80 is provided to counter the thrust force F generated in the first side gear 4 by the engagement between the first side gear 4 and the first pinion gear 61 during driving. 11 , and a thrust force F generated in the first side gear 4 by the helical spline connection between the first side gear 4 and the first connecting member 2. 13 This generates a frictional force between the first wall portion 42 of the first side gear 4 .

[0046] The center washer 80 is provided to absorb the thrust force F generated in the second side gear 5 by the engagement between the second side gear 5 and the second pinion gear 62 during driving. 12 , and a thrust force F generated in the second side gear 5 by the helical spline connection between the second side gear 5 and the second connecting member 3. 15 This generates a frictional force between the second wall portion 52 of the second side gear 5 .

[0047] The first side washer 81 is configured to absorb the thrust force F generated in the first connecting member 2 by the helical spline engagement between the first side gear 4 and the first connecting member 2 during driving. 14 This generates a frictional force between the second side gear 5 and the first connecting member 2. The second side washer 82 is adapted to reduce the thrust force F generated in the second connecting member 3 by the helical spline engagement between the second side gear 5 and the second connecting member 3 during driving. 16 This generates a friction force between the second connecting member 3 and the thrust force F 11 ~F 16 The frictional force generated by this acts as a differential limiting force that suppresses the differential rotation between the first output shaft 91 and the second output shaft 92 during driving.

[0048] On the other hand, during coasting, the first side gear 4 and the first pinion gear 61 mesh with each other, so that a thrust force F 21 The first outer peripheral wall portion 22 of the first connecting member 2 is subjected to this thrust force F 21The end surface 41a of the first cylindrical portion 41 receives the thrust force, and the contact surface 2a of the first connecting member 2 contacts the first side washer 81, generating a friction force. However, the thrust force F generated in the first side gear 4 and the first connecting member 2 by the helical spline connection between the first side gear 4 and the first connecting member 2 is 23 and thrust force F 24 The end surface 41a of the first cylindrical portion 41 of the first side gear 4 comes into contact with the end surface 22a of the first outer circumferential wall portion 22 of the first connecting member 2, whereby the two forces are cancelled out by each other.

[0049] During coasting, the second side gear 5 and the second pinion gear 62 mesh with each other, so that a thrust force F 22 The second outer peripheral wall portion 32 of the second connecting member 3 is subjected to this thrust force F 22 The second cylindrical portion 51 receives the thrust force from the end surface 51a, and the contact surface 3a of the second connecting member 3 contacts the second side washer 82, generating a friction force. However, the thrust force F generated in the second side gear 5 and the second connecting member 3 by the helical spline connection between the second side gear 5 and the second connecting member 3 is 25 and thrust force F 26 The end surface 51a of the second cylindrical portion 51 of the second side gear 5 comes into contact with the end surface 32a of the second outer circumferential wall portion 32 of the second connecting member 3, whereby the two forces are cancelled out by each other.

[0050] In this way, during coasting, the thrust force F generated by the helical spline connection between the first side gear 4 and the first connecting member 2 is 23 and thrust force F 24 The thrust force F generated by the helical spline connection between the second side gear 5 and the second connecting member 3 is 25 and thrust force F 26 Therefore, even if the torque transmitted between the first side gear 4 and the second side gear 5 and the first connecting member 2 and the second connecting member 3 is the same during driving and coasting, the differential limiting force generated during coasting is smaller than the differential limiting force generated during driving, and the magnitude of the differential limiting force generated during driving and coasting is different.

[0051] During driving, a thrust force F is generated by the meshing of the first side gear 4 and the first pinion gear 61. 11 and a thrust force F due to the helical spline connection between the first side gear 4 and the first connecting member 2. 13 The resultant force of these forces presses the first wall portion 42 of the first side gear 4 against the center washer 80. For this reason, if the contact area between the first side gear 4 and the center washer 80 were small, heat generation and wear would occur easily at the contact surface, but in this embodiment, the first wall portion 42 of the first side gear 4 protrudes radially inward beyond the multiple straight spline protrusions 211 of the first connecting member 2, ensuring a large contact surface 42c of the first wall portion 42 that contacts the center washer 80. This suppresses heat generation and wear due to friction between the first wall portion 42 of the first side gear 4 and the center washer 80.

[0052] During driving, a thrust force F 21 and a thrust force F due to the helical spline connection between the second side gear 5 and the second connecting member 3. 25 The resultant force of these forces presses the second wall portion 52 of the second side gear 5 against the center washer 80. In this embodiment, the second wall portion 52 of the second side gear 5 protrudes radially inward beyond the multiple straight spline projections 311 of the second connecting member 3, ensuring a large contact surface 52c of the second wall portion 52 that contacts the center washer 80. This suppresses heat generation and wear due to friction between the second wall portion 52 of the second side gear 5 and the center washer 80.

[0053] The through hole 420 of the first side gear 4 and the through hole 520 of the second side gear 5 function as oil holes through which the lubricating oil flows in the differential case 7. The inner diameter D0 of the center washer 80 is the inner diameter D 11 , and the inner diameter D of the through hole 520 21and has a size that does not impede the flow of lubricating oil through the through holes 420, 520. The through hole 420 of the first side gear 4 and the through hole 520 of the second side gear 5 are also used to discharge chips generated when cutting the multiple helical spline projections 411, 511 during manufacture of the first side gear 4 and the second side gear 5.

[0054] The inner diameter D0 of the center washer 80 is equal to the inner diameter D 12 , and the inner diameter D of the straight spline fitting portion 312 of the second connecting member 3 22 This ensures a large contact area between the first wall portion 42 of the first side gear 4 and the second wall portion 52 of the second side gear 5 and the center washer 80.

[0055] As shown in FIG. 3, the axial length between the end surface 21a of the first cylindrical body portion 21 and the end surface 22a of the first outer peripheral wall portion 22 of the first connecting member 2 is L 11 The axial length between the end surface 41a of the first cylindrical portion 41 and the first opposing surface 42a of the first wall portion 42 in the first side gear 4 is defined as L 12 Then, L 12 L 11 As a result, a gap is always formed between the end face 21a of the first tubular base portion 21 and the first opposing surface 42a of the first wall portion 42, and the first connecting member 2 does not come into contact with the first wall portion 42 of the first side gear 4. As a result, it is not necessary to perform a turning process or the like on the end face 21a of the first tubular base portion 21 and the first opposing surface 42a of the first wall portion 42, and they may be, for example, as a forged surface.

[0056] Similarly, the axial length between the end face 31a of the second cylindrical body portion 31 and the end face 32a of the second outer circumferential wall portion 32 of the third connecting member 3 is L 21 The axial length between the end surface 51a of the second cylindrical portion 51 and the second opposing surface 52a of the second wall portion 52 in the second side gear 5 is L 22 Then, L 22 L 21As a result, a gap is always formed between the end face 31a of the second tubular base portion 31 and the second opposing surface 52a of the second wall portion 52, and the second connecting member 3 does not come into contact with the second wall portion 52 of the second side gear 5. As a result, it is not necessary to perform a turning process or the like on the end face 31a of the second tubular base portion 31 and the second opposing surface 52a of the second wall portion 52, and they may be, for example, as a forged surface.

[0057] FIG. 4 is a cross-sectional view showing a differential gear 1A according to a comparative example. In this differential gear 1A, the first side gear 4 is not provided with the first wall portion 42, and the second side gear 5 is not provided with the second wall portion 52. Meanwhile, the first connecting member 2 is provided with the first wall portion 24 extending from the end portion of the first cylindrical base portion 21 on the center washer 80 side to the inner diameter side, and the second connecting member 3 is provided with the second wall portion 34 extending from the end portion of the second cylindrical base portion 31 on the center washer 80 side to the inner diameter side. Since the other configurations are the same as those of the differential gear 1 according to the above embodiment, in FIG. 4, the same reference numerals as those in FIG. 2 are used for the components common to the differential gear 1, and the duplicated description will be omitted.

[0058] In the differential gear 1A according to the comparative example, it is possible to abut the first output shaft 91 against the first wall portion 24 of the first connecting member 2 and the second output shaft 92 against the second wall portion 34 of the third connecting member 3 during assembly of the vehicle. However, the contact area between the first side gear 4 and the second side gear 5 and the center washer 80 during driving is smaller than that in the case of the differential gear 1 according to the embodiment, and heat generation and wear are likely to occur on the contact surfaces between the first side gear 4 and the second side gear 5 and the center washer 80. In addition, the first wall portion 24 and the second wall portion 34 do not perform any function after the vehicle is assembled.

[0059] In contrast, in the differential device 1 of this embodiment, the first side gear 4 is provided with a first wall portion 42, and the second side gear 5 is provided with a second wall portion 52, making it easy to position the first output shaft 91 and the second output shaft 92 when assembling the vehicle, and the first wall portion 42 and the second wall portion 52 make it possible to increase the contact area between the first side gear 4 and the second side gear 5 and the center washer 80, thereby suppressing heat generation and wear.

[0060] Furthermore, according to the differential device 1 of this embodiment, the through hole 420 of the first side gear 4 and the through hole 520 of the second side gear 5 function as oil holes through which lubricating oil flows within the differential case 7, thereby improving lubrication and suppressing heat generation and wear of the friction sliding parts in the differential case 7.

[0061] Furthermore, according to the differential device 1 of this embodiment, the first connecting member 2 does not contact the first wall portion 42 of the first side gear 4, and the second connecting member 3 does not contact the second wall portion 52 of the second side gear 5, so processing of the end face 21a of the first tubular base portion 21, the end face 31a of the second tubular base portion 31, the first opposing surface 42a of the first wall portion 42, and the second opposing surface 52a of the second wall portion 52 can be omitted, and processing costs can be reduced.

[0062] (Additional Note) The present invention has been described above based on the embodiment, but the invention according to the claims is not limited to this embodiment. It should be noted that not all of the combinations of features described in the embodiment are essential to the means for solving the problems of the invention. The present invention can be modified as appropriate by omitting some components or adding or replacing components without departing from the spirit of the invention. [Explanation of symbols]

[0063] 1...Differential device 2...First connecting member 21...First cylindrical body portion 211...Straight spline protrusion 213...Helical spline protrusion 22...First outer peripheral wall part 22a...end face 3...Second connecting member 31...Second cylindrical body portion 311...Straight spline protrusion 313…Helical spline protrusion 32…Second outer peripheral wall part 32a...end face 4…1st side gear 41…First cylindrical section 41a...end face 411…Helical spline protrusion 42...First wall part 420...Through hole 5…Second side gear 51...Second cylindrical section 51a...end face 511...Helical spline protrusion 52…Second wall part 520...Through hole 6...Pinion gear set 61…1st pinion gear 62…Second pinion gear 7…Differential case 80...Center washer 91…First output shaft 92…Second output shaft

Claims

1. A differential device that distributes a driving force of a vehicle to a first output shaft and a second output shaft, a cylindrical first connecting member having a plurality of straight spline protrusions on an inner circumference to which the first output shaft is straight spline-connected; a cylindrical second connecting member having a plurality of straight spline protrusions on an inner periphery to which the second output shaft is straight spline-connected; a first side gear combined with the first connecting member; a second side gear combined with the second connecting member; a plurality of pinion gear sets each including a first pinion gear meshed with the first side gear and a second pinion gear meshed with the second side gear; A differential case that holds the plurality of pinion gear sets; a center washer disposed between the first side gear and the second side gear and restricted in its relative rotation with respect to the differential case; the first side gear has a first cylindrical portion disposed on an outer periphery of the first connecting member and helically spline-connected to the first connecting member, and a first wall portion extending from one end of the first cylindrical portion on the center washer side to an inner diameter side, the first wall portion protruding to an inner diameter side beyond the plurality of straight spline projections of the first connecting member, the second side gear has a second cylindrical portion disposed on an outer periphery of the second connecting member and helically spline-connected to the second connecting member, and a second wall portion extending from one end of the second cylindrical portion on the center washer side to an inner diameter side, the second wall portion protruding to an inner diameter side beyond the plurality of straight spline projections of the second connecting member, the center washer generates a frictional force between the first wall portion of the first side gear and the second wall portion of the second side gear due to a thrust force generated by the helical spline connection during driving in which torque is transmitted from the first side gear and the second side gear to the first connecting member and the second connecting member. Differential device.

2. a through hole is formed in a center portion of the first side gear, the through hole passing through the first wall portion in an axial direction; A through hole is formed in a center portion of the second side gear, the through hole passing through the second wall portion in the axial direction. The differential device according to claim 1 .

3. the first connecting member has an annular first outer peripheral wall portion axially opposed to an end face of the first cylindrical portion of the first side gear opposite to the center washer, the second connecting member has an annular second outer circumferential wall portion axially opposed to an end face of the second cylindrical portion of the second side gear opposite to the center washer, During coasting in which torque is transmitted from the first connecting member and the second connecting member to the first side gear and the second side gear, the end face of the first cylindrical portion and the first outer peripheral wall portion come into contact with each other, and the end face of the second cylindrical portion and the second outer peripheral wall portion come into contact with each other, the first connecting member and the first wall portion do not come into contact with each other, and the second connecting member and the second wall portion do not come into contact with each other.

3. The differential device according to claim 1 or 2.

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