Differential device

Abstract

A differential device according to the present invention is provided with a differential case, a differential gear, a pair of output gears, a differential restriction section, and a cam section for operating the differential restriction section by means of a drive torque input to the output gears, and an operating member that is disposed so as to be axially movable, is engaged with the gear member so as to be integrally rotatable via the cam portion, and operates in a differential restriction portion, the cam portion having: a gear protrusion provided on the gear member; a working protrusion (39) provided on the working member and capable of engaging with an adjacent gear protrusion; and cam surfaces (41) which are provided on the surfaces facing each other in the direction of rotation of the gear protrusion and the working protrusion (39), and a corner (47) on the tip side of at least one of the gear protrusion and the working protrusion (39) has a retreat part (49) which is formed so as to retreat from the cam surfaces (41) while maintaining the contact area of the cam surfaces (41).

Description

Technical Field

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

[0002] Conventionally, a differential device includes: a differential case that is rotatably arranged; a differential gear that is rotatably supported by the differential case and revolves by the rotation of the differential case; and a pair of output gears that are relatively rotatable and mesh with the differential gears. In addition, a differential device is known that includes: a differential limiting portion that is slidably frictionally provided between the differential case and the output gears and limits the differential of the pair of output gears; and a cam portion that operates the differential limiting portion using a driving torque input to the output gears (see Patent Document 1).

[0003] In the differential device, the output gear has: a gear member that meshes with the differential gear; and an operating member that is configured to be axially movable and is integrally rotatably engaged with the gear member via the cam portion so that the differential limiting portion operates. The cam portion has: a gear convex portion that is provided on the gear member and protrudes in the axial direction and is arranged in plurality in the circumferential direction; and an operating convex portion that is provided on the operating member and protrudes in the axial direction and is arranged in plurality in the circumferential direction and can be engaged with adjacent gear convex portions. Cam surfaces are provided on the opposing surfaces of the gear convex portion and the operating convex portion 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 and input to a pair of output gears. The driving torque input to the pair of output gears causes the cam surface of the cam portion to operate and move the working member toward the differential limiting portion. The movement of the working member increases and strengthens the sliding friction in the differential limiting portion as a differential limiting force.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent document: Japanese Patent Application Publication No. 2019-124264 Summary of the invention

[0008] Technical issues

[0009] Incidentally, in the differential device as disclosed in Patent Document 1, when a pair of output gears rotate, the cam surface of the gear convex portion opposite to the rotation direction in the cam portion engages with the cam surface of the working convex portion. At this time, even if there are a few burrs or burrs remaining at the corners on the front end sides of the gear convex portion and the working convex portion, the rib-shaped portion will contact the cam surface before the cam surface. If the rib-shaped portion contacts the cam surface first, there is a possibility that the cam thrust generated in the cam portion is affected, and the differential limiting characteristics in the differential limiting portion may change.

[0010] Therefore, an object of the present invention is to provide a differential device capable of stabilizing the differential limiting characteristics in the differential limiting portion.

[0011] Technical Solution

[0012] The differential device of this embodiment comprises: a differential case, which is rotatably arranged; a differential gear, which is rotatably supported on the differential case and revolves through the rotation of the differential case; a pair of output gears that can rotate relative to each other and mesh with the differential gear; a differential limiting portion that can be slidably frictionally arranged between the differential case and the output gear and limits the differential of the pair of output gears; and a cam portion that uses the driving torque input to the output gear to operate the differential limiting portion, and the output gear has: a gear member that meshes with the differential gear; and a working member that is axially movable and is connected to the differential gear via the cam portion. The gear component can be rotatably engaged as a whole to enable the differential limiting portion to work, and the cam portion comprises: a gear convex portion, which is provided on the gear component and protrudes axially, and is arranged in plurality in the circumferential direction; a plurality of working convex portions, which are provided on the working component and protrude axially, and are arranged in plurality in the circumferential direction and can be engaged with adjacent gear convex portions; and a cam surface, which is respectively provided on the opposing surfaces of the gear convex portion and the working convex portion in the rotation direction in which they are fixed, and the corner portion on the front end side of at least one of the gear convex portion and the working convex portion has a receding portion, which is formed to maintain the abutment area of ​​the cam surface and retreat from the cam surface.

[0013] Effects of the Invention

[0014] According to the present invention, there is achieved an effect of providing a differential device capable of stabilizing the differential limiting characteristics in the differential limiting portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a cross-sectional view of the differential device according to the present embodiment.

[0016] Figure 2 It is a perspective view of a gear member of the differential device according to the present embodiment.

[0017] Figure 3 It is a perspective view of the operating components of the differential device according to the present embodiment.

[0018] Figure 4 yes Figure 3 An enlarged view of the main part.

[0019] Reference numerals

[0020] 1: differential device, 5: differential limiting portion, 7: differential case, 11: differential gear, 13, 15: output gear, 25: gear member, 27: working member, 35: cam portion, 37: gear convex portion, 39: working convex portion, 41: cam surface, 47: corner portion, 49: retreat portion, 51: ridge portion, 53: tangent line. DETAILED DESCRIPTION

[0021] The differential device of the present embodiment will be described in detail below using the drawings. In addition, the dimensional ratios in the drawings are exaggerated for the sake of convenience of description and may be different from the actual ratios.

[0022] like Figure 1 As shown, the differential device 1 of this embodiment is arranged between a driving source (not shown) such as an engine or an electric motor and left and right wheels (not shown). The driving force from the driving 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).

[0023] like Figures 1 to 4 As shown, the differential device 1 includes a differential mechanism 3 and a differential limiting unit 5 .

[0024] 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 .

[0025] The differential case 7 is rotatably supported by a stationary member (not shown) such as a planetary carrier via bearings (not shown) at the outer peripheries of the bosses 17 and 19 formed on both sides in the axial direction. A flange portion 21 for fixing a ring gear (not shown) is formed in the differential case 7. The ring gear fixed to the flange portion 21 meshes with a power transmission gear (not shown) for transmitting driving force, and drives the differential case 7 to rotate by transmitting driving force. The pinion shaft 9, the differential gear 11, a pair of output gears 13 and 15, etc. are accommodated and arranged in the differential case 7.

[0026] The pinion shaft 9 has its end engaged with a hole formed in the differential case 7, is prevented from falling out and rotating by the pin 23, and is driven to rotate integrally with the differential case 7. The differential gears 11 are supported on both shaft ends of the pinion shaft 9, respectively.

[0027] A plurality of differential gears 11 (two in this case) are arranged at equal intervals along the circumferential direction of the differential case 7, and are supported on the shaft end side of the pinion shaft 9, respectively, and revolve by the rotation of the differential case 7. The differential gear 11 is supported on the pinion shaft 9 in a rotatable manner so as to be driven to rotate when a rotation difference occurs between the meshing pair of output gears 13 and 15 while transmitting driving force to the pair of output gears 13 and 15.

[0028] The pair of output gears 13 and 15 are relatively rotatably accommodated in the differential case 7. The pair of output gears 13 and 15 are respectively composed of a gear member 25 and an operating member 27. In addition, in the pair of output gears 13 and 15, the gear member 25 and the operating member 27 are formed symmetrically, so the following mainly describes one of them, and omits the description of the other.

[0029] The gear member 25 is formed in an annular shape and has a gear portion formed on the outer peripheral side thereof that meshes with the differential gear 11. The gear member 25 meshes with the differential gear 11 to transmit driving force from the differential gear 11 to the pair of output gears 13 and 15. In addition, when a rotation difference occurs between the pair of output gears 13 and 15, the differential gear 11 is rotated.

[0030] The working member 27 is formed in a concave annular portion 28 so as to be arranged close to the gear member 25 in the axial direction and to be able to accommodate a part of the axial direction of the gear member 25. A sliding surface 29 inclined in a conical shape in the axial direction is provided in a portion of the working member 27 located radially outside the gear member 25. On the inner peripheral side of the working member 27, cylindrical output portions 31 and 33 having a spline shape that can be connected to a pair of output shafts to rotate integrally are formed in the pair of output gears 13 and 15. The working member 27 outputs the driving force input from the differential case 7 to the pair of output gears 13 and 15 to the left and right wheels via the pair of output shafts.

[0031] A cam portion 35 for converting a rotational torque into an axial thrust is provided between the gear member 25 and the working member 27 in the axial direction. 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 working protrusions 39 provided on the outer peripheral side of the cylindrical output portion of the working member 27 and capable of engaging between adjacent gear protrusions 37, 37. The cam portion 35 enables the gear member 25 and the working member 27 to rotate integrally by engaging the gear protrusions 37 and the working protrusions 39 in the rotation direction. A concave annular portion 28 is provided on the outer peripheral side of the plurality of working protrusions 39 so as to accommodate a part of the axial direction of the gear member 25, and the sliding portion 29 is located on the outer diameter side of the annular portion 28.

[0032] On the other hand, in the cam portion 35, the engagement surfaces of the plurality of gear protrusions 37 and the plurality of operating protrusions 39 in the rotation direction are cam surfaces 41 inclined at a predetermined angle. When the differential case 7 is input with driving force (driving torque), the cam surface 41 in the cam portion 35 is operated by the driving force branched from the differential gear 11 and input to the pair of output gears 13 and 15, so that the operating member 27 moves axially outward. By moving the operating member 27 in the axial direction through the cam portion 35, the differential limiting force in the differential limiting portion 5 disposed between the differential case 7 and the pair of output gears 13 and 15 can be increased and strengthened.

[0033] The differential limiting portion 5 is disposed between the differential case 7 and the pair of output gears 13 and 15. The differential limiting portion 5 includes a tapered ring 43 and an operating member 27 that slide against each other.

[0034] The tapered ring 43 is disposed at positions corresponding to the sliding surfaces 29 of the operating members 27 of the pair of output gears 13 and 15, respectively, relative to the differential case 7. The tapered ring 43 rotates integrally with the differential case 7 by engaging a plurality of convex portions formed on the inner circumference side along the circumferential direction with concave portions formed on the inner wall surface of the differential case 7.

[0035] The tapered ring 43 slides on the sliding surface 29 of the working member 27 of the pair of output gears 13 and 15 that moves in the axial direction due to the meshing reaction force with the differential gear 11, depending on 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, which serves as the differential limiting force of the differential limiting portion 5, and the sliding surface 29 is increased and strengthened by the cam thrust of the cam portion 35.

[0036] The differential limiting part 5 transmits the friction torque between the differential case 7 and the pair of output gears 13 and 15 according to the magnitude of the cam thrust, and limits the differential of the differential mechanism 3. Such a differential limiting part 5 is a cone clutch type among torque-sensitive friction clutches. The differential limiting part 5 is preloaded by the urging member 45.

[0037] The urging member 45 is composed of a coil spring and is arranged between the gear member 25 and the working member 27 in the axial direction. The urging member 45 urges the gear member 25 toward the axial inner side (differential gear 11 side) and urges the working member 27 toward the axial outer side (differential limiting portion 5 side). By arranging the urging member 45 between the gear member 25 and the working member 27, a preload can be applied to the differential limiting portion 5, and the intermittent characteristics of the differential limiting portion 5 can be stabilized.

[0038] In such a differential device 1, the cam surface 41 formed on the engagement surface of the plurality of gear convex parts 37 and the plurality of working convex parts 39 in the rotation direction of the cam portion 35 is engaged, thereby generating a cam thrust for axially moving the working member 27. In the corners on the front end sides of the gear convex parts 37 and the working convex parts 39, there may be rib-like parts such as burrs or flashes remaining, and the rib-like parts may protrude from the cam surface 41 in the rotation direction. In the engagement of the cam surface 41 of the gear convex part 37 and the working convex part 39, if the rib-like parts protrude from the cam surface 41, there is a possibility that the rib-like parts will contact the cam surface 41 of the other side before the cam surface 41 of the gear convex part 37 and the working convex part 39. If the rib-like parts contact the cam surface 41 first, there is a possibility that the cam thrust generated in the cam portion 35 is affected, and the differential limiting characteristics in the differential limiting part 5 are changed.

[0039] Therefore, the corner portion 47 on the front end side of at least one of the gear protrusion 37 and the operating protrusion 39 has a setback portion 49, which is formed to maintain the contact area of ​​the cam surface 41 and to be set back from the cam surface 41. In addition, in the following description, it is assumed that the setback portion 49 is provided at the corner portion 47 of the operating protrusion 39, but the setback portion 49 may be provided at the corner portion on the front end side of the gear protrusion 37.

[0040] At the corner 47 of the working cam 39, a setback portion 49 is provided which is formed to be set back from the cam surface 41 by chamfering or the like, so as to prevent the cam 41 from protruding in the rotation direction. By providing the setback portion 49 at the corner 47, a rib-like portion such as a burr or a flash protruding in the rotation direction from the cam surface 41 is not generated at the corner 47. Therefore, the gear cam 37 and the cam surface 41 of the working cam 39 can be stably contacted without the rib-like portion first contacting the cam surface 41. The setback portion 49 is provided relative to the corner 47 while maintaining the contact area of ​​the cam surface 41, so as to prevent the set cam thrust generated in the cam portion 35 from being affected. Therefore, the contact area between the gear cam 37 and the cam surface 41 of the working cam 39 is not reduced, and the cam thrust can be stably generated in the cam portion 35, and the differential limiting characteristic in the differential limiting portion 5 can be stabilized.

[0041] Three ridges are formed continuously in the corner 47 of the working convex portion 39. At least one ridge 51 of the three ridges is formed into a plane or a curved surface by chamfering or the like. The ridge 51 formed into a plane or a curved surface is a ridge that is discontinuous with the cam surface 41. Therefore, even if the ridge 51 is formed into a plane or a curved surface, the contact area of ​​the cam surface 41 is not affected. The ridge 51 formed into a plane or a 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 ridge-like portions such as burrs or flash from being generated in the portion of the ridge 51 that is continuous with the receding portion 49. In addition, when making the ridge continuous with the cam surface 41 continuous with the receding portion 49, it is sufficient to form the ridge continuous with the receding portion 49 as a plane or a curved surface in a manner that maintains the contact area of ​​the cam surface 41 so as to make it continuous with the receding portion 49.

[0042] The recessed portion 49 is formed as a plane or a curved surface so that the most protruding portion of the corner portion 47 is recessed from the cam surface 41 in the rotation direction, and is provided to be continuous with the cam surface 41. The plane or the curved surface of the recessed portion 49 is connected to the cam surface 41 via the tangent 53 in such a way that the angle formed with the cam surface 41 is an acute angle. Since the recessed portion 49 has a surface connected to the tangent 53 of the cam surface 41 at an acute angle, the surface of the recessed portion 49 does not protrude from the cam surface 41 in the rotation direction. Therefore, the gear protrusion 37 can be brought into stable contact with the cam surface 41 of the working protrusion 39. In addition, by forming the recessed portion 49 as a plane or a curved surface and connecting it to the cam surface 41, it is possible to prevent the generation of ridge-like portions such as burrs or flash in a wide range of the recessed portion 49.

[0043] The setback portion 49 is provided on at least the working member 27 side of the gear member 25 and the working member 27. Since the working member 27 is subjected to sliding friction with the tapered ring 43 (differential case 7), it is easily affected by the adverse effect of displacement caused by minute vibrations in the axial and radial directions. By providing the setback portion 49 on the side of the working member 27 that is easily affected, the contact state between the gear protrusion 37 and the cam surface 41 of the working protrusion 39 can be properly maintained. Therefore, the contact area between the gear protrusion 37 and the cam surface 41 of the working protrusion 39 can be ensured, and the differential limiting characteristics in the differential limiting portion 5 can be stabilized. In particular, as shown in the embodiment of the present application, in a structure in which the sliding portion 29 is arranged at a position away from the plurality of working protrusions 39 on the outer diameter side, the minute vibration of the cam portion 35 is amplified in the sliding portion 29 as the large diameter side, resulting in a fluctuation range of the differential limiting characteristics.

[0044] In such a differential device 1, there are provided a differential case 7 which is rotatably arranged, a differential gear 11 which supports the differential case 7 rotatably and revolves by the rotation of the differential case 7, and a pair of output gears 13 and 15 which are relatively rotatable and mesh with the differential gear 11. In addition, there are provided a differential limiting portion 5 which is provided between the differential case 7 and the output gears 13 and 15 in a sliding friction manner and limits the differential of the pair of output gears 13 and 15, and a cam portion 35 which operates the differential limiting portion 5 by using the driving torque input to the output gears 13 and 15. Furthermore, the output gears 13 and 15 have a gear member 25 which meshes with the differential gear 11, and an operating member 27 which is axially movable and is integrally rotatably engaged with the gear member 25 via the cam portion 35 to operate the differential limiting portion 5. In addition, the cam portion 35 includes: a gear convex portion 37, which is provided on the gear member 25, protrudes in the axial direction, and is arranged in a plurality in the circumferential direction; and an operating convex portion 39, which is provided on the operating member 27, protrudes in the axial direction, is arranged in a plurality in the circumferential direction, and can be engaged with adjacent gear convex portions 37, 37. Further, the cam portion 35 includes a cam surface 41, which is provided on the opposing surfaces of the gear convex portion 37 and the operating convex portion 39 in the rotational direction. In addition, a corner portion 47 on the front end side of at least one of the gear convex portion 37 and the operating convex portion 39 includes a retracted portion 49, which is formed to retract from the cam surface 41 while maintaining the contact area of ​​the cam surface 41.

[0045] Since the corner portion 47 has the recessed portion 49, a burr or burr-like portion protruding from the cam surface 41 in the rotation direction is not generated at the corner portion 47. Therefore, the burr-like portion does not contact the cam surface 41 first, and the gear convex portion 37 and the cam surface 41 of the working convex portion 39 can be stably contacted. Even if the recessed portion 49 is formed in 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 working convex portion 39 is not reduced, and the cam thrust can be stably generated in the cam portion 35, and the differential limiting characteristics in the differential limiting portion 5 can be stabilized.

[0046] Therefore, in such a differential device 1 , the differential limiting characteristics in the differential limiting portion 5 can be stabilized.

[0047] Furthermore, at least one ridge line portion 51 connected to the corner portion 47 is continuous with the receding portion 49 .

[0048] Therefore, it is possible to prevent ridge-like portions such as burrs and flash from being generated in the portion of the ridge line portion 51 that is continuous with the receding portion 49 .

[0049] Furthermore, the receding portion 49 has a surface connected to the tangent line 53 of the cam surface 41 at an acute angle.

[0050] Therefore, the surface of the receding portion 49 does not protrude from the cam surface 41 in the rotation direction, and the gear convex portion 37 and the cam surface 41 of the operating convex portion 39 can be brought into contact with each other stably.

[0051] In addition, the retreat portion 49 is formed as a flat surface or a curved surface, and is connected to the cam surface 41 .

[0052] Therefore, it is possible to prevent burrs or fins from being generated in a wide range of the flat or curved receding portion 49. In addition, the wear powder generated by the time difference can be suppressed from being retained and entering the cam surface 41 in the space on the surface side where the receding portion 49 is formed, so that stable contact with the cam surface 41 can be achieved.

[0053] In addition, a receding portion 49 is formed on the operating member 27 side.

[0054] By forming the setback portion 49 on the side of the working member 27 that is easily adversely affected, the contact state between the gear protrusion 37 and the cam surface 41 of the working protrusion 39 can be appropriately maintained. Therefore, the contact area between the gear protrusion 37 and the cam surface 41 of the working protrusion 39 can be ensured, and the differential limiting characteristics in the differential limiting portion 5 can be stabilized.

[0055] As mentioned above, although this embodiment was demonstrated, this embodiment is not limited to this, Various deformation|transformation is possible within the range of the summary of this embodiment.

[0056] For example, in the differential device of the present embodiment, the tapered ring arranged to rotate integrally with the differential case slides on the operating member, but the present invention is not limited thereto, and the inner wall surface of the differential case and the operating member may slide without using the tapered ring.

[0057] Furthermore, when the gear component 25 and the working component 27 are formed, the receding portion 49 can be formed by other suitable methods such as cutting, aligning the surface by stamping, laser processing, etching, etc.

Claims

1. A differential device, characterized in that: have: a differential case rotatably arranged; a differential gear supported by the differential case so as to be rotatable and to revolve orbitally by the rotation of the differential case; a pair of output gears capable of relative rotation and meshing with the differential gear; a differential limiting portion which is slidably and frictionally disposed between the differential case and the output gear and limits the differential of the pair of output gears; as well as a cam portion that operates the differential limiting portion using the driving torque input to the output gear, The output gear has: a gear member meshing with the differential gear; as well as an operating member which is arranged to be axially movable and is integrally rotatably engaged with the gear member via the cam portion to operate the differential limiting portion, The cam portion comprises: a gear convex portion, which is provided on the gear member and protrudes in the axial direction, and is arranged in plurality in the circumferential direction; a working convex portion, which is provided on the working member and protrudes in the axial direction, and is arranged in plurality in the circumferential direction, and can be engaged with the adjacent gear convex portion; and cam surfaces, which are respectively provided on the opposing surfaces of the gear convex portion and the working convex portion in the rotational direction. A corner portion on the front end side of at least one of the gear protrusion and the operation protrusion has a recessed portion, and the recessed portion is formed so as to be recessed from the cam surface while maintaining a contact area with the cam surface.

2. The differential device according to claim 1, characterized in that: At least one ridge line portion connected to the corner portion is continuous with the receding portion.

3. The differential device according to claim 1 or 2, characterized in that: The recessed portion has a surface connected at an acute angle to a tangent line of the cam surface.

4. The differential device according to claim 1 or 2, characterized in that: The retreat portion is formed as a flat surface or a curved surface and is connected to the cam surface.

5. The differential device according to claim 1 or 2, characterized in that: The retreat portion is formed on the working member side.

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