Differential device

Abstract

The invention provides a differential device, in an output gear having a gear member and an output member, the inside and the outside of a differential case can be divided by a sealing member. A differential device (1) is provided with: a differential case (7) rotatably disposed; a differential gear (11) that is rotatably supported by the differential case (7) and that revolves as a result of the rotation of the differential case (7); and a pair of output gears (13, 15) that mesh with the differential gear (11) and are rotatable relative to each other, the output gears (13, 15) having: a gear member (37) that meshes with the differential gear (11); and an output member (39) that is disposed on the inner diameter side of the gear member (37) via an engagement section (57) so as to be rotatable integrally with the gear member (37), and a seal member (63) that partitions the inside and outside of the differential case (7) is disposed at an end of the output member (39).

Description

Technical Field

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

[0002] Conventionally, a differential device includes a rotatable differential case and differential gears rotatably supported by the differential case and caused to orbit by the rotation of the differential case. Furthermore, a differential device is known that includes a pair of output gears meshing with the differential gears and capable of relative rotation, and a pair of output shafts coupled to the inner diameter sides of the pair of output gears for integral rotation (see Patent Document 1).

[0003] In this differential device, a cover member is disposed on the output gear, serving as a sealing member that separates the inside and outside of the differential case. The cover member separates the inside and outside of the differential case, preventing oil flowing inside the differential case from leaking outward from the pair of output shafts.

[0004] On the other hand, as another differential device, a differential device in which the output gear includes a gear member and an output member is known (see Patent Document 2). In this differential device, the gear member meshes with the differential gear. The output member is arranged on the inner diameter side of the gear member via a cam portion as an engagement portion so as to be rotatable integrally with the gear member, and the output shaft is connected to the inner diameter side so as to be rotatable integrally with the gear member.

[0005] Prior art literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-166625

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-124264

[0008] However, in the differential device of Patent Document 2, the output gear is composed of two components: a gear member and an output member, with a gap between them. A sealing member of Patent Document 1 is disposed at the end of the output gear to demarcate the interior and exterior of the differential case. However, if only the sealing member of Patent Document 1 is disposed at the end of the output gear, the gap between the gear member and the output member communicates with the output shaft, making it impossible to demarcate the interior and exterior of the differential case. Summary of the Invention

[0009] Therefore, an object of the present invention is to provide a differential device in which, in an output gear including a gear member and an output member, the inside and outside of a differential case can be partitioned by a sealing member.

[0010] According to this embodiment, a differential device comprises: a differential case, which is configured in a rotatable manner; a differential gear, which is supported on the differential case in a rotatable manner and revolves through the rotation of the differential case; and a pair of output gears, which mesh with the differential gears and can rotate relative to each other, and the output gears have: a gear member, which meshes with the differential gear; and an output member, which is configured on the inner diameter side of the gear member via an engaging portion in a manner that can rotate integrally with the gear member, and a sealing member is configured at the end of the output member to divide the inside and outside of the differential case.

[0011] The effects of the present invention are as follows.

[0012] According to the present invention, it is possible to provide a differential device in which, in an output gear including a gear member and an output member, the inside and outside of a differential case can be partitioned by a sealing member. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a cross-sectional view of the differential device according to the present embodiment.

[0014] In the figure: 1—differential device, 7—differential housing, 11—differential gear, 13, 15—output gear, 37—gear member, 39—output member, 41—gear support portion, 43—seal support portion, 51—fixing portion, 57—engaging portion, 63—sealing member. DETAILED DESCRIPTION

[0015] Hereinafter, the differential device according to the present embodiment will be described in detail using the accompanying drawings. In addition, for the sake of convenience of explanation, the dimensional ratios in the drawings may be exaggerated and may differ from the actual ratios.

[0016] like Figure 1 As shown, the differential device 1 according to this embodiment is disposed between a drive source (not shown), such as an engine or 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).

[0017] like Figure 1 As shown, the differential device 1 includes a differential mechanism 3 and a differential limiting unit 5 .

[0018] 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 .

[0019] The differential case 7 is rotatably supported by a housing 25 via bearings 21 and 23 on the outer peripheries of bosses 17 and 19 formed on both axial sides. Lubricating oil is contained in the housing 25 to lubricate and cool the sliding and meshing parts on the outside of the differential case 7, as well as the sliding and meshing parts inside the differential case 7. Seal members 27 and 29 are disposed radially between the housing 25 and the pair of output gears 13 and 15 to partition the inside and outside of the housing 25.

[0020] The differential case 7 has a flange portion 31 to which a ring gear (not shown) is fixed. The ring gear fixed to the flange portion 31 meshes with a power transmission gear (not shown) that transmits driving force, thereby transmitting the driving force and driving the differential case 7 to rotate. The pinion shaft 9, the differential gear 11, and a pair of output gears 13 and 15 are housed and arranged within the differential case 7.

[0021] The pinion shaft 9 is driven and rotated integrally with the differential case 7 by engaging its end with a hole formed in the differential case 7 and securing it with a pin 33 to prevent it from falling out and preventing it from rotating. The pinion shaft 9 is housed in a thrust block 35 that axially positions the pair of output gears 13 and 15, with both shaft ends exposed. The differential gears 11 are supported on each of the pinion shaft ends.

[0022] A plurality of differential gears 11 (here, two) are arranged at equal intervals in the circumferential direction of the differential case 7. Each differential gear 11 is supported on the shaft end side of the pinion shaft 9 and is caused to revolve orbitally by the rotation of the differential case 7. The differential gear 11 transmits driving force to a pair of output gears 13 and 15 and is rotatably supported on the pinion shaft 9 so as to be driven to rotate when differential rotation occurs between the meshing pair of output gears 13 and 15.

[0023] The pair of output gears 13 and 15 are housed in the differential case 7 so as to be rotatable relative to each other. Each of the output gears 13 and 15 is composed of a gear member 37 and an output member 39. Furthermore, the gear member 37 and the output member 39 are formed symmetrically with each other in the pair of output gears 13 and 15. Therefore, the following description will focus on only one of them, and the description of the other will be omitted.

[0024] Gear member 37 is annular and has a gear portion formed on its outer periphery that meshes with differential gear 11. Gear member 37 meshes with differential gear 11, transmitting driving force from differential gear 11 to the pair of output gears 13 and 15. Furthermore, when the pair of output gears 13 and 15 generate differential rotation, the differential gear 11 rotates.

[0025] One axial end (axially inner side) of the output member 39 is formed into a concave annular shape, capable of accommodating a portion of the axial direction of the gear member 37, allowing for axial proximity to the gear member 37. The concave annular portion of the output member 39 forms a cylindrical gear support portion 41 that radially supports the gear member 37. The axial end of the gear support portion 41 forms a cylindrical seal support portion 43, the inner diameter of which is disposed with a seal member 63, described later. By positioning the seal support portion 43 on the inner diameter of the gear support portion 41, the gear support portion 41 and the seal support portion 43 overlap in the radial direction, thereby preventing the output member 39 from increasing in size in the axial direction. The axial length of the gear support portion 41 is set to be longer than the axial length of the seal support portion 43. Therefore, the gear support portion 41 can radially support the gear member 37 over a wide axial range, thereby stabilizing the radial support provided by the gear support portion 41 to the gear member 37.

[0026] A sliding surface 45 that is conically inclined in the axial direction is provided on the portion of the output member 39 that is located radially outside the gear member 37. On the inner circumferential side of the output member 39, a pair of output gears 13, 15 are formed with spline-shaped output portions 47, 49 that can be connected to a pair of output shafts (not shown) in a manner that rotates as a whole. A fixing portion 51 consisting of a groove that is continuous in the circumferential direction is provided on each of the output portions 47, 49, and a fixing member such as a C-shaped washer that is used to fix the pair of output shafts is engaged with the groove. A toothless portion 53 that is not provided with teeth on a portion of the circumference is provided on each of the output portions 47, 49. The toothless portion 53 prevents an increase in the internal pressure in the output portions 47, 49 when the pair of output shafts are connected to the output portions 47, 49. A seal groove 55 is provided continuously in the circumferential direction on the other axial end side (axially outward) of the output member 39. A seal member (not shown) such as an O-ring is disposed in this seal groove 55 to prevent grease or other lubricant applied to the output portions 47 and 49 from leaking to the outside. The seal member disposed in the seal groove 55 is in close contact with the outer circumference of the pair of output shafts connected to the output portions 47 and 49. The output member 39 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.

[0027] An engaging portion 57 is provided axially between the gear member 37 and the output member 39 to convert rotational torque into axial thrust. The engaging portion 57 comprises a plurality of engaging recesses provided on the inner circumference of the gear member 37 and a plurality of engaging protrusions provided on the outer circumference of the output member 39 and capable of engaging with the plurality of engaging recesses. By engaging the plurality of engaging recesses with the plurality of engaging protrusions, the engaging portion 57 enables the gear member 37 and the output member 39 to rotate integrally.

[0028] At least a portion of the axial direction of the engaging portion 57 is arranged to overlap with the fixing portion 51 in the radial direction. By arranging the engaging portion 57 and the fixing portion 51 to overlap in the radial direction, it is possible to ensure the rigidity of the transmission path of the driving force while saving space, thereby stabilizing the transmission of the driving force. Relative to the engaging portion 57, the sealing support portion 43 is arranged on the inner diameter side of the gear member 37, and the radial wall thickness is set to be thinner. By arranging the sealing support portion 43 at a position closer to the inner diameter side of the gear member 37 than the engaging portion 57, even if the wall thickness of the sealing support portion 43 is reduced, it will not affect the engagement of the engaging portion 57. Moreover, by setting the wall thickness of the sealing support portion 43 to be thinner than the engaging portion 57, the configuration space of the sealing member 63 described later can be ensured without enlarging it.

[0029] In the engagement portion 57, the rotationally engaging surfaces of the multiple engaging recesses and the multiple engaging protrusions form cam surfaces inclined at a predetermined angle. When driving force (driving torque) is input to the differential case 7, the driving force diverted from the differential gear 11 and input to the pair of output gears 13 and 15 engages the cam surfaces of the engagement portion 57, causing the output member 39 to move axially outward. The axial movement of the output member 39 caused by the cam surfaces of the engagement portion 57 increases and strengthens the differential limiting force of the differential limiting unit 5, which is positioned between the differential case 7 and the pair of output gears 13 and 15.

[0030] 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 59 and an output member 39 that slide against each other.

[0031] The tapered ring 59 is disposed at a position corresponding to the sliding surface 45 of the output member 39 of the pair of output gears 13 and 15 relative to the differential case 7. The tapered ring 59 rotates integrally with the differential case 7 by engaging a plurality of circumferentially formed protrusions on the inner circumference of the tapered ring 59 with recesses formed on the inner wall surface of the differential case 7.

[0032] The tapered ring 59 slides on the sliding surface 45 of the output member 39 of the pair of output gears 13 and 15, which 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 differential limiting force of the differential limiting unit 5, that is, the sliding friction between the tapered ring 59 and the sliding surface 45, is amplified and strengthened by the cam thrust of the cam surface of the engaging portion 57.

[0033] The differential limiting unit 5 transmits friction torque between the differential case 7 and the pair of output gears 13 and 15 in accordance with the magnitude of the cam thrust, thereby limiting the differential of the differential mechanism 3. This differential limiting unit 5 is a cone clutch type among torque-sensitive friction clutches. The differential limiting unit 5 is preloaded by a biasing member 61.

[0034] The urging member 61, comprised of a disc spring, is positioned axially between the gear member 37 and the output member 39. The urging member 61 urges the gear member 37 axially inward (toward the differential gear 11) and urges the output member 39 axially outward (toward the differential limiting unit 5). The placement of the urging member 61 between the gear member 37 and the output member 39 applies a preload to the differential limiting unit 5, stabilizing the intermittent characteristics of the differential limiting unit 5.

[0035] In this differential device 1, the pair of output gears 13 and 15 are composed of two components: a gear member 37 and an output member 39. A gap is formed between the gear member 37 and the output member 39. For example, a seal member 63 is disposed on one axial end (axially inward) of the gear member 37 to separate the interior and exterior of the differential case 7. In this case, the gap between the gear member 37 and the output member 39 communicates with the output portions 47 and 49, allowing lubricating oil circulating within the differential case 7 to flow toward the output portions 47 and 49 and leak to the exterior of the differential case 7.

[0036] Therefore, a sealing member 63 that divides the inside and outside of the differential case 7 is arranged on the sealing support portion 43 on the axial one end side (axial inner side) of the output member 39. The sealing member 63 is formed in the shape of a cover that can close the opening of the sealing support portion 43. The sealing member 63 is assembled on the sealing support portion 43 so that its outer surface is in close contact with the inner surface of the sealing support portion 43. By arranging the sealing member 63 on the axial one end side of the output member 39, the gap between the gear member 37 and the output member 39 will not be connected to the output parts 47, 49 (output shaft). Therefore, the lubricating oil circulating inside the differential case 7 will not flow out between the output parts 47, 49 and the output shaft (not shown), and will not leak to the outside of the differential case 7.

[0037] Such a differential device 1 includes a rotatable differential case 7 and a differential gear 11 rotatably supported by the differential case 7 and caused to revolve orbitally by the rotation of the differential case 7. Furthermore, a pair of output gears 13 and 15 are provided, which mesh with the differential gear 11 and are relatively rotatable. Furthermore, the output gears 13 and 15 include a gear member 37 meshing with the differential gear 11 and an output member 39 rotatably arranged on the inner diameter side of the gear member 37 via an engagement portion 57. Furthermore, a seal member 63 is provided at the end of the output member 39 to separate the inside and outside of the differential case 7.

[0038] By arranging the sealing member 63 at the end of the output member 39, the gap between the gear member 37 and the output member 39 does not communicate with the outside of the differential case 7. Therefore, the lubricating oil circulating inside the differential case 7 does not flow out toward the output shaft through the gap between the gear member 37 and the output member 39, and does not leak to the outside of the differential case 7.

[0039] Therefore, in such a differential device 1 , in the output gears 13 and 15 including the gear member 37 and the output member 39 , the inside and outside of the differential case 7 can be partitioned by the seal member 63 .

[0040] Furthermore, the output member 39 includes, on one axial end side, a cylindrical gear support portion 41 that radially supports the gear member 37 and a cylindrical seal support portion 43 in which a seal member 63 is disposed.

[0041] Therefore, the gear member 37 is stably supported by the gear support portion 41 of the output member 39 , and the seal member 63 is arranged on the seal support portion 43 of the output member 39 , thereby partitioning the inside and outside of the differential case 7 .

[0042] In addition, the seal support portion 43 is located on the inner diameter side of the gear support portion 41 .

[0043] Therefore, the gear support portion 41 and the seal support portion 43 are arranged to overlap in the radial direction, and it is possible to suppress an increase in the size of the output member 39 in the axial direction.

[0044] Furthermore, the axial length of the gear support portion 41 is set to be longer than the axial length of the seal support portion 43 .

[0045] Therefore, the gear support portion 41 can support the gear member 37 in the radial direction over a wide range in the axial direction, and the radial support of the gear member 37 by the gear support portion 41 can be stabilized.

[0046] Furthermore, the seal support portion 43 is disposed on the inner diameter side of the gear member 37 , and is set to have a smaller wall thickness in the radial direction than that of the engagement portion 57 .

[0047] Therefore, by arranging the seal support portion 43 closer to the inner diameter side of the gear member 37 than the engagement portion 57, even if the wall thickness of the seal support portion 43 is reduced, the engagement of the engagement portion 57 will not be affected. Furthermore, by setting the wall thickness of the seal support portion 43 to be thinner than the engagement portion 57, it is possible to ensure space for arranging the seal member 63 without increasing the size of the seal member 63.

[0048] Furthermore, a fixing portion 51 for fixing the output shaft is provided on the output member 39. The engaging portion 57 is arranged to overlap with at least a portion of the fixing portion 51 in the axial direction in the radial direction.

[0049] Therefore, by arranging the engagement portion 57 and the fixing portion 51 to overlap in the radial direction, it is possible to ensure high rigidity while saving space, and to stabilize the transmission of the driving force.

[0050] 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.

[0051] For example, in the differential device according to this embodiment, the differential limiting portion includes a tapered ring arranged to rotate integrally with the differential case. However, the differential limiting portion is not limited to this embodiment and may be configured such that the output member slides on the inner wall surface of the differential case without using a tapered ring. Alternatively, the differential limiting portion may be configured using a single flat disc-shaped plate or multiple plates arranged alternately.

[0052] The meshing combination of the differential gear and the pair of output gears is not limited to a bevel gear set, and various combinations such as a face gear set and a parallel shaft set with parallel shafts can also be used. In either case, at least the output gear includes a gear member and an output member.

Claims

1. A differential device comprising: a differential case configured to be rotatable; a differential gear supported by the differential case in a rotatable manner and revolving orbitally by the rotation of the differential case; as well as a pair of output gears meshing with the differential gear and capable of relative rotation, The output gear has: a gear member meshing with the differential gear; and an output member disposed on the inner diameter side of the gear member via an engagement portion so as to be rotatable integrally with the gear member, A sealing member that partitions the inside and outside of the differential case is disposed at an end portion of the output member.

2. The differential device according to claim 1, wherein: The output member has, on one axial end side, a cylindrical gear support portion that supports the gear member in a radial direction, and a cylindrical seal support portion in which the seal member is arranged.

3. The differential device according to claim 2, wherein: The seal support portion is located on the inner diameter side of the gear support portion.

4. The differential device according to claim 2 or 3, wherein: The axial length of the gear support portion is set to be longer than the axial length of the seal support portion.

5. The differential device according to claim 2 or 3, wherein: The seal support portion is disposed on the inner diameter side of the gear member, and is set to have a smaller wall thickness in the radial direction than that of the engagement portion.

6. The differential device according to any one of claims 1 to 3, wherein: The output member is provided with a fixing portion for fixing the output shaft. The engaging portion and at least a portion of the fixing portion in the axial direction are arranged to overlap in the radial direction.

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