Differential device

Abstract

To provide a differential device capable of stabilizing differential limiting characteristics in a differential limiting portion.SOLUTION: A differential device is equipped with a differential case, a differential gear, a pair of output gears, a differential limiting portion, and a cam portion that actuates the differential limiting portion with driving torque inputted in the output gears. The output gear has a gear member, and an actuating member that is disposed so as to move in an axial direction, is engaged with the gear member through the cam portion so as to integrally rotate, and actuates the differential limiting portion. The cam portion has a gear projecting portion provided on the gear member, an actuation projecting portion 39 that is provided on the actuation member and can engage with the adjacent gear projecting portion, and cam surfaces 41 that are respectively provided on opposite surfaces in rotating directions of the gear projecting portion and the actuation projecting portion 39. A corner portion 47 on a tip end side of at least one of the gear projecting portion and the actuation projecting portion 39 has a retracting portion 49 that is formed so as to hold an abutting area of the cam surface 41 and retract from the cam surface 41.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a differential device. [Background technology]

[0002] Conventionally, a differential device includes a rotatably arranged differential case, a differential gear supported rotatably on the differential case and revolving with the rotation of the differential case, and a pair of output gears that mesh with the differential gear and can rotate relatively. Also, a differential limiting unit that is provided between the differential case and the output gear and allows sliding friction to limit the differential between the pair of output gears, and a cam unit that operates the differential limiting unit with a driving torque input to the output gear (see Patent Document 1).

[0003] In this differential device, the output gear has a gear member that meshes with the differential gear, and an operating member that is arranged to be axially movable and engages with the gear member via a cam portion so as to be rotatable together to operate the differential limiting portion. The cam portion has gear protrusions that are provided on the gear member and protrude in the axial direction and are arranged in a plurality of circumferential directions, and operating protrusions that are provided on the operating member and protrude in the axial direction and are arranged in a plurality of circumferential directions and can engage with adjacent gear protrusions. Cam surfaces are provided on the opposing surfaces of the gear protrusions and the operating protrusions in the rotational direction.

[0004] In such a differential device, when a driving torque is input to the differential case, the driving torque is branched from the differential gear to a pair of output gears and input. The driving torque input to the pair of output gears operates the cam surface of the cam portion to move the operating member toward the differential limiting portion. The movement of the operating member increases and strengthens the sliding friction, which is the differential limiting force in the differential limiting portion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-124264 A Summary of the Invention [Problem to be solved by the invention]

[0006] In a differential device such as that disclosed in Patent Document 1, when a pair of output gears rotate, the cam surface of the gear protrusions facing each other in the direction of rotation engages with the cam surface of the operating protrusions in the cam portion. If there are even slight burrs or other edge-like portions remaining on the corners of the tips of the gear protrusions and the operating protrusions, the edge-like portions will come into contact with the cam surfaces before the cam surfaces come into contact with each other. If the edge-like portions come into contact with the cam surfaces first, it may affect the cam thrust force generated in the cam portion, and the differential limiting characteristics of the differential limiting portion may change.

[0007] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a differential device that can stabilize the differential limiting characteristics in the differential limiting portion. [Means for solving the problem]

[0008] The differential device according to the present embodiment includes a rotatably arranged differential case, a differential gear supported on the differential case so as to be rotatable and revolving with the rotation of the differential case, a pair of output gears meshing with the differential gear and relatively rotatable, a differential limiting section provided between the differential case and the output gear so as to be capable of sliding friction and limiting the differential between the pair of output gears, and a cam section that operates the differential limiting section with a driving torque input to the output gear, and the output gear includes a gear member that meshes with the differential gear, and a gear member that is arranged axially movable and a cam section that is connected between the gear member and the cam section. and an operating member which is engaged with the gear member so as to be rotatable together via the cam portion and which operates the differential limiting portion, and the cam portion has gear convex portions which are provided on the gear member and protrude in the axial direction and are arranged in a circumferential direction in a plurality of locations, operating convex portions which are provided on the operating member and protrude in the axial direction and are arranged in a plurality of locations in the circumferential direction and are engageable with adjacent gear convex portions, and cam surfaces which are provided on opposing surfaces of the gear convex portions and the operating convex portions in the rotational direction, and a corner portion on the tip side of at least one of the gear convex portions and the operating convex portions has a retraction portion which is formed to retract from the cam surface while maintaining the contact area of ​​the cam surface. Effect of the Invention

[0009] Advantageous Effects of Invention According to the present invention, it is possible to provide a differential device capable of stabilizing the differential limiting characteristics in the differential limiting portion. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a cross-sectional view of the differential device according to the embodiment. [Diagram 2] FIG. 2 is a perspective view of a gear member of the differential device according to the embodiment. [Diagram 3] FIG. 2 is a perspective view of an operating member of the differential device according to the embodiment. [Figure 4] FIG. 4 is an enlarged view of a main part of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The differential device according to the present embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios.

[0012] 1, a differential device 1 according to this embodiment is disposed between a drive source (not shown), such as an engine or an electric motor, and left and right wheels (not shown). Driving force from the drive source is transmitted to the differential device 1 via a transmission (not shown), and the driving force is distributed to the left and right wheels via a pair of output shafts (not shown).

[0013] As shown in FIGS. 1 to 4, the differential device 1 includes a differential mechanism 3 and a differential limiting section 5. The differential mechanism 3 and the differential limiting section 5 include a differential lock section 5a and a differential lock section 5b.

[0014] The differential mechanism 3 includes a differential case 7, a pinion shaft 9, a differential gear 11, and a pair of output gears 13 and 15.

[0015] The differential case 7 is rotatably supported by a stationary member (not shown) such as a carrier via bearings (not shown) at the outer periphery of each of bosses 17, 19 formed on both axial sides. The differential case 7 is formed with a flange portion 21 to which a ring gear (not shown) is fixed. The ring gear fixed to the flange portion 21 meshes with a power transmission gear (not shown) that transmits a driving force, and the driving force is transmitted to rotate the differential case 7. A pinion shaft 9, a differential gear 11, a pair of output gears 13, 15, etc. are housed and arranged inside the differential case 7.

[0016] The pinion shaft 9 has an end engaged with a hole formed in the differential case 7 and is prevented from coming off and rotating by a pin 23, and is rotated integrally with the differential case 7. Differential gears 11 are supported on both axial ends of the pinion shaft 9, respectively.

[0017] A plurality of differential gears 11 (two in this example) are arranged at equal intervals in the circumferential direction of the differential case 7, each supported on the shaft end side of the pinion shaft 9 and revolving with the rotation of the differential case 7. The differential gear 11 transmits driving force to the pair of output gears 13, 15, and is rotatably supported by the pinion shaft 9 so as to be rotationally driven when a differential rotation occurs between the pair of meshed output gears 13, 15.

[0018] The pair of output gears 13, 15 are accommodated in the differential case 7 so as to be capable of relative rotation. Each of the pair of output gears 13, 15 includes a gear member 25 and an operating member 27. In the pair of output gears 13, 15, the gear member 25 and the operating member 27 are formed symmetrically, so that only one of them will be mainly described below, and a description of the other will be omitted.

[0019] The gear member 25 is formed in an annular shape, and a gear portion that meshes with the differential gear 11 is formed on the outer circumferential side. The gear member 25 meshes with the differential gear 11, thereby transmitting driving force from the differential gear 11 to the pair of output gears 13, 15. In addition, when a differential rotation occurs between the pair of output gears 13, 15, the gear member 25 rotates the differential gear 11.

[0020] The actuating member 27 is formed in a concave ring shape capable of accommodating a part of the gear member 25 in the axial direction so that the actuating member 27 can be arranged close to the gear member 25 in the axial direction. A sliding surface 29 inclined conically in the axial direction is provided on a portion of the actuating member 27 located radially outward of the gear member 25. On the inner peripheral side of the actuating member 27, spline-shaped output portions 31, 33 are formed in the pair of output gears 13, 15, which can be connected to the pair of output shafts so as to be rotatable together. The actuating member 27 outputs the driving force input from the differential case 7 to the pair of output gears 13, 15 to the left and right wheels via the pair of output shafts.

[0021] A cam portion 35 for converting rotational torque into an axial thrust force is provided between the gear member 25 and the operating member 27. The cam portion 35 is composed of a plurality of gear protrusions 37 provided on the inner peripheral side of the gear member 25 and a plurality of operating protrusions 39 provided on the outer peripheral side of the operating member 27 and engageable between adjacent gear protrusions 37, 37. The cam portion 35 engages the gear protrusions 37 and the operating protrusions 39 in the rotational direction, thereby enabling the gear member 25 and the operating member 27 to rotate integrally.

[0022] On the other hand, in cam portion 35, the engagement surfaces in the rotational direction between the multiple gear protrusions 37 and the multiple operating protrusions 39 are each inclined at a predetermined angle to form cam surfaces 41. When a driving force (driving torque) is input to the differential case 7, the cam surface 41 in cam portion 35 is actuated by the driving force branched off from differential gear 11 and input to the pair of output gears 13, 15, causing cam portion 35 to move operating member 27 outward in the axial direction. The axial movement of operating member 27 by cam portion 35 can increase and strengthen the differential limiting force in differential limiting unit 5 arranged between the differential case 7 and the pair of output gears 13, 15.

[0023] The differential limiting portion 5 is disposed between the differential case 7 and the pair of output gears 13, 15. The differential limiting portion 5 has a tapered ring 43 and an operating member 27 which slide against each other.

[0024] The tapered rings 43 are disposed on the differential case 7 at positions corresponding to the sliding surfaces 29 of the operating members 27 of the pair of output gears 13, 15. The tapered ring 43 rotates integrally with the differential case 7 by engaging multiple protrusions formed in the circumferential direction on the inner peripheral side with recesses formed on the inner wall surface of the differential case 7.

[0025] The tapered ring 43 slides against the sliding surface 29 of the operating member 27 of the pair of output gears 13, 15 that is moved axially by a meshing reaction force with the differential gear 11 according to the magnitude of the driving force (driving torque) input to the differential case 7. At this time, the sliding friction between the tapered ring 43 and the sliding surface 29, which is the differential limiting force of the differential limiting unit 5, is increased and strengthened by the cam thrust force of the cam portion 35.

[0026] The differential limiting unit 5 transmits friction torque between the differential case 7 and the pair of output gears 13, 15 in response to the magnitude of the cam thrust force, thereby limiting the differential of the differential mechanism 3. Such a differential limiting unit 5 is a cone clutch type among torque-sensitive friction clutches. A preload is applied to the differential limiting unit 5 by a biasing member 45.

[0027] The biasing member 45 is made of a disc spring, and is disposed axially between the gear member 25 and the operating member 27. The biasing member 45 biases the gear member 25 axially inward (toward the differential gear 11), and biases the operating member 27 axially outward (toward the differential limiting unit 5). By disposing the biasing member 45 between the gear member 25 and the operating member 27, a preload is applied to the differential limiting unit 5, and the on-off characteristic of the differential limiting unit 5 can be stabilized.

[0028] In such a differential device 1, the cam portion 35 generates a cam thrust force that moves the operating member 27 in the axial direction by engaging with the cam surface 41 formed on the engagement surface of the multiple gear protrusions 37 and the multiple operating protrusions 39 in the rotational direction. Edge-like parts such as burrs and burrs may remain on the corners on the tip side of the gear protrusions 37 and the operating protrusions 39, and the edge-like parts may protrude in the rotational direction from the cam surface 41. When the gear protrusions 37 and the cam surface 41 of the operating protrusions 39 engage with each other, if the edge-like parts protrude from the cam surface 41, there is a possibility that the edge-like parts may contact the cam surface 41 of the other side before their own cam surface 41. If the edge-like parts contact the cam surface 41 first, it may affect the cam thrust force generated in the cam portion 35, and the differential limiting characteristic in the differential limiting unit 5 may change.

[0029] Therefore, corner portion 47 on the tip side of at least one of gear protrusion 37 and actuating protrusion 39 has receding portion 49 formed to recede from cam surface 41 while maintaining the contact area of ​​cam surface 41. Note that, in the following description, it is assumed that receding portion 49 is provided at corner portion 47 of actuating protrusion 39, but receding portion 49 may be provided at corner portion on the tip side of gear protrusion 37.

[0030] A recessed portion 49 is provided at the corner 47 of the operating convex portion 39, which is formed by chamfering so as to be recessed from the cam surface 41 so as not to protrude from the cam surface 41 in the rotation direction. By providing the recessed portion 49 at the corner 47, an edge-like portion such as a burr or a burr protruding from the cam surface 41 in the rotation direction is not generated at the corner 47. Therefore, the edge-like portion does not contact the cam surface 41 first, and the gear convex portion 37 and the cam surface 41 of the operating convex portion 39 can be stably contacted. The recessed portion 49 is provided at the corner 47 while maintaining the contact area of ​​the cam surface 41 so as not to affect the set cam thrust force generated by the cam portion 35. Therefore, the contact area of ​​the gear convex portion 37 and the cam surface 41 of the operating convex portion 39 is not reduced, and the cam thrust force can be stably generated at the cam portion 35, and the differential limiting characteristic in the differential limiting portion 5 can be stabilized.

[0031] Three ridges are formed continuously at the corner 47 of the operating convex portion 39. At least one of the three ridges, 51, is formed with a flat or curved surface by chamfering or the like. The ridge 51 formed with a flat or curved surface is not continuous with the cam surface 41. Therefore, even if the ridge 51 is formed with a flat or curved surface, it does not affect the contact area of ​​the cam surface 41. The ridge 51 formed with a flat or curved surface is formed continuously with the receding portion 49. By making the ridge 51 continuous with the receding portion 49, it is possible to prevent edge-like portions such as burrs and burrs from occurring in the portion of the ridge 51 that is continuous with the receding portion 49. When the ridge that is continuous with the cam surface 41 is made continuous with the receding portion 49, it is sufficient to make it continuous with the receding portion 49 by forming it with a flat or curved surface so as to maintain the contact area of ​​the cam surface 41.

[0032] The receding portion 49 is formed with a flat or curved surface so that the most protruding portion of the corner portion 47 recedes from the cam surface 41 in the rotational direction, and is provided so as to be continuous with the cam surface 41. The flat or curved surface of the receding portion 49 is connected to the cam surface 41 via a tangent 53 so that the angle between the receding portion 49 and the cam surface 41 is an acute angle. Since the receding portion 49 has a surface that is connected at an acute angle to the tangent 53 of the cam surface 41, the surface of the receding portion 49 does not protrude from the cam surface 41 in the rotational direction. Therefore, the gear protrusion 37 and the cam surface 41 of the operating protrusion 39 can be stably contacted. In addition, by forming the receding portion 49 with a flat or curved surface and connecting it to the cam surface 41, the generation of edge-like portions such as burrs and burrs can be prevented over a wide range of the receding portion 49.

[0033] The receding portion 49 is provided at least on the side of the gear member 25 and the operating member 27. The operating member 27 is subject to sliding friction between the tapered ring 43 (differential case 7) and is therefore susceptible to adverse effects of misalignment due to minute vibrations in the axial and radial directions. By providing the receding portion 49 on the side of the operating member 27, which is susceptible to adverse effects, the abutment state between the gear protrusions 37 and the cam surfaces 41 of the operating protrusions 39 can be properly maintained. This makes it possible to ensure the abutment area between the gear protrusions 37 and the cam surfaces 41 of the operating protrusions 39, and stabilize the differential limiting characteristics in the differential limiting unit 5.

[0034] Such a differential device 1 includes a rotatably arranged differential case 7, a differential gear 11 supported rotatably on the differential case 7 and revolving with the rotation of the differential case 7, and a pair of output gears 13, 15 meshing with the differential gear 11 and capable of relative rotation. The differential limiting unit 5 is provided between the differential case 7 and the output gears 13, 15 so as to be capable of sliding friction and limiting the differential between the pair of output gears 13, 15, and a cam portion 35 that operates the differential limiting unit 5 with the driving torque input to the output gears 13, 15. The output gears 13, 15 further include a gear member 25 that meshes with the differential gear 11, and an operating member 27 that is arranged axially movable and engaged with the gear member 25 via the cam portion 35 so as to be integrally rotatable, thereby operating the differential limiting unit 5. Further, the cam portion 35 has gear protrusions 37 provided on the gear member 25, protruding in the axial direction, and arranged in a plurality of circumferential directions, and actuating protrusions 39 provided on the actuating member 27, protruding in the axial direction, and arranged in a plurality of circumferential directions, capable of engaging with adjacent gear protrusions 37, 37. Further, the cam portion 35 has cam surfaces 41 provided on the opposing surfaces of the gear protrusions 37 and the actuating protrusions 39 in the rotational direction. A corner portion 47 on the tip side of at least one of the gear protrusions 37 and the actuating protrusions 39 has a retraction portion 49 formed to retract from the cam surface 41 while maintaining the contact area of ​​the cam surface 41.

[0035] Since the corner portion 47 has the recessed portion 49, no edge-like portion such as a burr or a burr protruding from the cam surface 41 in the rotation direction is generated at the corner portion 47. Therefore, the edge-like portion does not contact the cam surface 41 first, and the gear convex portion 37 and the cam surface 41 of the operating convex portion 39 can be stably contacted. Even if the recessed portion 49 is formed at the corner portion 47, the contact area of ​​the cam surface 41 is maintained. Therefore, the contact area of ​​the gear convex portion 37 and the cam surface 41 of the operating convex portion 39 does not decrease, and a cam thrust force can be stably generated at the cam portion 35, and the differential limiting characteristic in the differential limiting portion 5 can be stabilized.

[0036] Therefore, in such a differential device 1, the differential limiting characteristic in the differential limiting section 5 can be stabilized.

[0037] At least one ridge portion 51 connected to the corner portion 47 is continuous with the recessed portion 49 .

[0038] Therefore, it is possible to prevent the generation of edge-like portions such as burrs and burrs at the portion of the ridge line 51 continuing to the recessed portion 49 .

[0039] Further, the receding portion 49 has a surface that is connected at an acute angle to a tangent line 53 of the cam surface 41 .

[0040] Therefore, the face of the retracting portion 49 does not protrude beyond the cam face 41 in the rotational direction, and the gear protrusion 37 and the cam face 41 of the operating protrusion 39 can be brought into stable contact with each other.

[0041] Further, the recessed portion 49 is formed of a flat surface or a curved surface, and is connected to the cam surface 41 .

[0042] Therefore, the occurrence of edge portions such as burrs and burrs can be prevented over a wide range of the recessed portion 49 formed with a flat or curved surface.

[0043] Moreover, the receding portion 49 is formed on the operating member 27 side.

[0044] By forming the recessed portion 49 on the side of the operating member 27 that is more susceptible to adverse effects, it is possible to properly maintain the abutment state between the gear protrusion 37 and the cam surface 41 of the operating protrusion 39. As a result, it is possible to ensure the abutment area between the gear protrusion 37 and the cam surface 41 of the operating protrusion 39, and it is possible to stabilize the differential limiting characteristic in the differential limiting unit 5.

[0045] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment.

[0046] For example, in the differential device according to this embodiment, a tapered ring arranged to rotate integrally with the differential case slides against the operating member, but this is not limited to this, and the inner wall surface of the differential case and the operating member may slide against each other without using a tapered ring. [Explanation of symbols]

[0047] 1 Differential device 5. Limited slip differential 7 Differential Case 11 Differential gear 13,15 Output gear 25 Gear Materials 27 Actuating member 35 Cam section 37 Gear protrusion 39 Operating protrusion 41 Cam surface 47 Corner 49 Retreat 51 Ridge 53 Tangent line

Claims

1. A rotatably disposed differential case; A differential gear that is rotatably supported by the differential case and revolves with the rotation of the differential case; a pair of output gears meshing with the differential gear and relatively rotatable; A differential limiting unit that is provided between the differential case and the output gear so as to be capable of sliding and frictionally moving and limits the differential between the pair of output gears; a cam portion that operates the differential limiting portion by a driving torque input to the output gear; Equipped with the output gear has a gear member that meshes with the differential gear, and an operating member that is arranged to be movable in the axial direction, is engaged with the gear member via the cam portion so as to be integrally rotatable, and operates the differential limiting portion, the cam portion includes a gear protrusion provided on the gear member, protruding in the axial direction and arranged in a circumferential direction; an operating protrusion provided on the operating member, protruding in the axial direction and arranged in a circumferential direction and capable of engaging with adjacent gear protrusions; and a cam surface provided on each of the opposing surfaces of the gear protrusion and the operating protrusion in the rotational direction; A differential device in which a corner portion on the tip side of at least one of the gear convex portion and the operating convex portion has a retraction portion formed to retract from the cam surface while maintaining the contact area of ​​the cam surface.

2. 2. The differential device according to claim 1, wherein at least one ridge portion connected to the corner portion is continuous with the recessed portion.

3. 3. The differential device according to claim 1, wherein the recessed portion has a surface that is connected at an acute angle to a tangent to the cam surface.

4. 3. The differential device according to claim 1, wherein the recessed portion is formed as a flat surface or a curved surface and is connected to the cam surface.

5. 3. The differential device according to claim 1, wherein the recessed portion is formed on the side of the operating member.

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