Differential gear mechanism

Abstract

To realize a differential gear mechanism which can inhibit deterioration of durability of a case part and an output shaft even if a load transmitted from an outer peripheral gear to a case part is relatively large.SOLUTION: A differential gear mechanism 10 includes: a case part 30 which houses a differential gear set; a cylindrical part 40 connected to the case part 30; and an outer peripheral gear 45 formed on an outer peripheral surface 40a of the cylindrical part 40. The cylindrical part 40 is disposed at the outer side in a radial direction R relative to the case part 30, connected to the case part 30 through a connection part 60 which is formed so as to protrude from an outer peripheral surface of the case part 30 to the outer side in the radial direction R. Openings 62 penetrating through the connection part 60 in an axial direction L are formed at multiple positions in a circumferential direction C at the connection part 60.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a differential gear mechanism.

Background Art

[0002] A differential gear mechanism is known that includes a case portion having through holes through which each of a pair of output shafts passes. Hereinafter, the reference numerals shown in parentheses in the description of the background art are those of Patent Document 1. Patent Document 1 discloses a differential gear mechanism (10) including a case portion (14) having through holes through which each of a pair of output shafts (60) passes, and an outer peripheral gear (28) connected to the case portion (14).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a differential gear mechanism such as Patent Document 1, spiral grooves for guiding lubricating oil are formed on the inner peripheral surface of the through hole of the case portion facing the outer peripheral surface of the output shaft, suppressing the occurrence of wear and seizure. However, when the load transmitted from the outer peripheral gear to the case portion is relatively large, the case portion tilts with respect to the output shaft, resulting in a problem that the durability of the portions where the load is concentrated on the through hole of the case portion and the outer peripheral surface of the output shaft decreases.

[0005] Therefore, even when the load transmitted from the outer peripheral gear to the case portion is relatively large, it is desired to realize a differential gear mechanism that can suppress a decrease in the durability of the case portion and the output shaft.

Means for Solving the Problems

[0006] The characteristic configuration of the differential gear mechanism in view of the above is A differential gear set consisting of multiple differential gears that mesh with each other, A case portion for housing the differential gear set, A cylindrical part connected to the case portion, The outer gear formed on the outer surface of the cylindrical portion, A differential gear mechanism equipped with, The differential gear set is configured to distribute the rotation of the outer gear to a pair of output shafts. The direction along the rotation axis of the case portion is defined as the axial direction, the direction perpendicular to the axial direction is defined as the radial direction, and the direction around the rotation axis is defined as the circumferential direction. The cylindrical portion is positioned radially outward from the case portion and connected to the case portion via a connecting portion formed to protrude radially outward from the outer circumferential surface of the case portion. The case portion is provided with through holes through which each of the pair of output shafts passes in the axial direction. The pair of through holes are arranged separately on both sides in the axial direction, flanking the differential gear set. Each of the pair of through holes has an inner surface facing the outer surface of the output shaft, The key feature is that multiple openings are formed in the circumferential direction of the connecting portion, with openings penetrating in the axial direction.

[0007] This distinctive configuration allows the connecting portion between the cylindrical part and the case part to bend more easily compared to a configuration without multiple openings. This reduces the magnitude of loads transmitted from the outer gear to the case part in directions other than rotation. Consequently, the bending of the case part reduces the load acting between the through hole and the output shaft, thereby suppressing damage to the case part and output shaft and reducing their durability. When the through hole in the case part and the output shaft are in direct contact, wear on the case part and output shaft, as well as seizure between the case part and the output shaft, can be minimized.

[0008] Further features and advantages of the technology relating to this disclosure will become clearer from the following description of exemplary and non-limiting embodiments, with reference to the drawings. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view of a differential gear mechanism according to the first embodiment. [Figure 2] Figure 1 is a perspective view of the differential gear mechanism. [Figure 3] Figure 2 is a perspective view of the connecting portion and the cylindrical portion. [Figure 4] Figure 2 is a perspective view of the case section. [Figure 5] This is a perspective view of the differential gear mechanism according to the second embodiment. [Figure 6] Figure 5 is a perspective view of the cylindrical part shown. [Figure 7] Figure 5 is a perspective view of the connecting section and the case section. [Figure 8] This is a perspective view of a differential gear mechanism according to a third embodiment. [Modes for carrying out the invention]

[0010] [First Embodiment] Hereinafter, a differential gear mechanism 10 according to the first embodiment will be described with reference to the drawings. Figure 1 is a cross-sectional view of the differential gear mechanism 10. The differential gear mechanism 10 is interposed between, for example, a vehicle drive source (not shown) and a pair of left and right drive wheels. The differential gear mechanism 10 has a differential gear set 20 consisting of a plurality of differential gears 22, 24 that mesh with each other, and a case portion 30 that houses the differential gear set 20. The differential gear mechanism 10 also includes a cylindrical portion 40 connected to the case portion 30 and an outer peripheral gear 45 formed on the outer peripheral surface 40a of the cylindrical portion 40. In this embodiment, the outer peripheral gear 45 is a helical gear.

[0011] The differential gear set 20 is configured to distribute the rotation of the outer peripheral gear 45 to the pair of output shafts 50. In the present embodiment, the outer peripheral gear 45 is an input element of the differential gear mechanism 10, and the pair of output shafts 50 are output elements of the differential gear mechanism 10. Further, the pair of output shafts 50 are each connected to a driving wheel (not shown). Here, the direction along the rotation axis X1 of the case portion 30 is defined as the axial direction L, the direction orthogonal to the axial direction L is defined as the radial direction R, and the direction around the rotation axis X1 is defined as the circumferential direction C. The case portion 30 rotates around the rotation axis X1 in conjunction with the rotation of the outer peripheral gear 45.

[0012] In the present embodiment, the differential gear set 20 includes a first bevel gear 22 rotatably supported by a shaft member 31 held by the case portion 30 so as to extend along the radial direction R, and a pair of second bevel gears 24 that are divided and arranged on both sides of the shaft member 31 in the axial direction L and mesh with the first bevel gear 22, respectively. In the illustrated example, a pair of first bevel gears 22 are provided and rotatably supported with respect to the shaft member 31 in a state of being spaced apart from each other along the radial direction R and facing each other. The shaft member 31 is supported by the case portion 30 so as to rotate integrally with the case portion 30. The shaft member 31 is inserted into shaft insertion holes 32 which are a pair of through holes formed in the case portion 30 along the radial direction R. Further, the shaft member 31 is locked to the case portion 30 by a locking member 33. The locking member 33 is a rod-shaped pin extending along the axial direction L.

[0013] In the present embodiment, the pair of second bevel gears 24 are rotation elements after distribution in the differential gear mechanism 10. The pair of second bevel gears 24 are arranged so as to be spaced apart from each other in the axial direction L and face each other with the shaft member 31 interposed therebetween. The pair of second bevel gears 24 are each configured to rotate in the circumferential direction C in the internal space of the case portion 30. In the present embodiment, the first bevel gear 22 (in this example, the pair of first bevel gears 22) and the pair of second bevel gears 24 correspond to differential gears. <​​In this embodiment, the differential gear mechanism 10 is connected to a pair of output shafts 50. The pair of output shafts 50 are connected to the differential gear mechanism 10 so as to extend from both sides of the differential gear mechanism 10 in the axial direction L. A pair of second bevel gears 24 are connected to the pair of output shafts 50. Specifically, one second bevel gear 24 is connected to one output shaft 50, and the other second bevel gear 24 is connected to the other output shaft 50. Thereby, the rotation of the case portion 30 due to the driving force input to the outer peripheral gear 45 can be appropriately distributed to the pair of output shafts 50.

[0015] In this embodiment, splines 24c are respectively formed on the inner peripheral surfaces of the pair of second bevel gears 24. Corresponding to this spline 24c, splines 50c are also respectively formed on the outer peripheral surfaces of the ends of the pair of output shafts 50 on the side of the second bevel gears 24. By the engagement of these splines, the pair of second bevel gears 24 and the pair of output shafts 50 rotate integrally with each other.

[0016] The case portion 30 includes through holes 35 through which each of the pair of output shafts 50 penetrates in the axial direction L. The pair of through holes 35 are arranged separately on both sides of the differential gear set 20 in the axial direction L with the differential gear set 20 interposed therebetween. Each of the pair of through holes 35 includes an inner peripheral surface 35b facing the outer peripheral surface 50a of the output shaft 50. In this embodiment, the inner peripheral surfaces 35b of the pair of through holes 35 are in contact with the outer peripheral surfaces 50a of the output shafts 50 respectively. In the illustrated example, the pair of through holes 35 are coaxially arranged. Spiral grooves 36 for guiding lubricating oil into the interior of the case portion 30 are formed on the inner peripheral surfaces 35b of the through holes 35.

[0017] In this embodiment, the case portion 30 includes a pair of cylindrical portions 34 formed to surround a pair of through holes 35. Each of the pair of cylindrical portions 34 is formed in a cylindrical shape that extends in the axial direction L. Furthermore, each of the pair of cylindrical portions 34 is formed to extend in the axial direction L from the case portion 30 (specifically, the portion of the case portion 30 that forms the housing chamber for the differential gear set 20). Each of these cylindrical portions 34 is rotatably supported by the housing 70, which is a non-rotating member, via differential case bearings 72, so as to be rotatable around the axial direction L. As a result, the case portion 30 and the outer gear 45 are rotatably supported by the housing 70 so as to be rotatable around the rotation axis X1.

[0018] Figure 2 is a perspective view of the differential gear mechanism 10. In Figure 2, the differential gear set 20, shaft member 31, and locking member 33 are omitted. Figure 3 is a perspective view of the integrally formed connecting portion 60 and cylindrical portion 40. Figure 4 is a perspective view of the case portion 30. The cylindrical portion 40, on which the outer peripheral gear 45 is formed on the outer peripheral surface 40a, is positioned radially outward from the case portion 30 in the direction R, and is connected to the case portion 30 via a connecting portion 60 that is formed to protrude radially outward from the outer peripheral surface 30a of the case portion 30 in the direction R.

[0019] In this embodiment, the connecting portion 60 and the cylindrical portion 40 are integrally formed. Also in this embodiment, the cylindrical portion 40 is a separate component from the case portion 30, and the inner circumferential surface 60b of the connecting portion 60 and the outer circumferential surface 30a of the case portion 30 are welded together. As a result, the outer gear 45 and the case portion 30 rotate integrally around the rotation axis X1. The case portion 30 is formed to cover at least a part of the differential gear set 20. Also in this embodiment, the case portion 30 is provided with case openings 38 at multiple locations (two locations in this example) in the circumferential direction C. The case openings 38 are openings for assembling the first bevel gear 22 and the second bevel gear 24 to the case portion 30. In the illustrated example, the multiple case openings 38 are arranged at equal intervals in the circumferential direction C.

[0020] Multiple openings 62 penetrating in the axial direction L are formed at several locations (three in this example) in the circumferential direction C of the connecting portion 60. In this embodiment, these multiple openings 62 have equal (including identical) lengths in the circumferential direction C and are arranged at equal intervals in the circumferential direction C. Furthermore, the openings 62 are formed in an arc shape parallel to the outer circumferential surface 40a of the cylindrical portion 40. The area occupied by the openings 62 is within the range of 15 to 60% of the entire area in the circumferential direction C. Within this range, the connecting portion 60 connecting the cylindrical portion 40 and the case portion 30 can bend appropriately.

[0021] The differential gear mechanism 10 of this embodiment comprises a differential gear set 20 consisting of a plurality of differential gears 22, 24 that mesh with each other, a case portion 30 housing the differential gear set 20, a cylindrical portion 40 connected to the case portion 30, and an outer peripheral gear 45 formed on the outer peripheral surface 40a of the cylindrical portion 40. The differential gear set 20 is configured to distribute the rotation of the outer peripheral gear 45 to a pair of output shafts 50, with the direction along the rotation axis X1 of the case portion 30 being the axial direction L, the direction perpendicular to the axial direction L being the radial direction R, and the direction around the rotation axis X1 being the circumferential direction C, and the cylindrical The part 40 is positioned radially outward from the case part 30 in the radial direction R and is connected to the case part 30 via a connecting part 60 formed to protrude radially outward from the outer peripheral surface 30a of the case part 30 in the radial direction R. The case part 30 has through holes 35 through which each of the pair of output shafts 50 passes in the axial direction L. The pair of through holes 35 are arranged separately on both sides of the differential gear set 20 in the axial direction L, and each of the pair of through holes 35 has an inner peripheral surface 35b facing the outer peripheral surface 50a of the output shaft 50. Multiple openings 62 that pass through in the axial direction L are formed at multiple locations in the circumferential direction C of the connecting part 60.

[0022] In this way, the connecting portion 60 that connects the cylindrical portion 40 and the case portion 30 can be made more flexible compared to a configuration without multiple openings 62. This makes it possible to reduce the magnitude of loads other than rotational loads transmitted from the outer gear 45 to the case portion 30. Consequently, the load acting between the through hole 35 and the output shaft 50 can be reduced due to the bending of the case portion 30, thereby suppressing damage to the case portion 30 and the output shaft 50 and reducing their durability. When the through hole 35 of the case portion 30 and the output shaft 50 are in direct contact, wear of the case portion 30 and the output shaft 50, and seizure between the case portion 30 and the output shaft 50 can be reduced.

[0023] Furthermore, in the differential gear mechanism 10 of this embodiment, the multiple openings 62 have equal lengths in the circumferential direction C and are arranged at equal intervals in the circumferential direction C. This makes it possible to minimize the bias in the circumferential direction C of the load transmitted from the outer gear 45 to the case portion 30. Consequently, it is also easier to minimize the deflection of the case portion 30.

[0024] Furthermore, in the differential gear mechanism 10 of this embodiment, the opening 62 is formed in an arc shape parallel to the outer circumferential surface 40a of the cylindrical portion 40. In this way, the opening 62 can be properly formed even when the radial radius R dimension of the connecting portion 60 is relatively small.

[0025] [Second Embodiment] The differential gear mechanism 10 according to the second embodiment will be described below with reference to the drawings. In this embodiment, the configuration of the connecting portion 60 differs from that of the first embodiment. The following description will focus on the differences from the first embodiment. Points that are not specifically described are the same as those of the first embodiment. Figure 5 is a perspective view of the differential gear mechanism 10 of this embodiment. Figure 6 is a perspective view of the cylindrical portion 40, and Figure 7 is a perspective view of the integrally formed connecting portion 60 and case portion 30.

[0026] In this embodiment, the connecting portion 60 is formed integrally with the case portion 30. In this embodiment, the connecting portion 60 also includes protruding portions 64 and recessed portions 66. The protruding portions 64 are provided at multiple locations (three locations in this example) in the circumferential direction C and are formed to protrude radially outward from the case portion 30 in the radial direction R. The recessed portions 66 are formed between two adjacent protruding portions 64. The outer circumferential surface 64a of the protruding portions 64 is welded to the cylindrical portion 40, and the recessed portions 66 of the connecting portion 60 form an opening 62. The area occupied by the protruding portions 64 is in the range of 40 to 85% of the entire area in the circumferential direction C. In the illustrated example, the recessed portions 66 are located at three locations in the circumferential direction C of the connecting portion 60, with equal lengths in the circumferential direction C and arranged at equal intervals in the circumferential direction C. Furthermore, the outer circumferential surface 64a of the protruding portion 64 is welded to the inner circumferential surface 40b of the cylindrical portion 40.

[0027] In the differential gear mechanism 10 of this embodiment, the connecting portion 60 includes multiple protruding portions 64 provided at multiple locations in the circumferential direction C and formed to project radially outward from the case portion 30 in the radial direction R, and a recessed portion 66 formed between two adjacent protruding portions 64. The outer circumferential surface 64a of the protruding portions 64 is welded to the cylindrical portion 40, and the recessed portion 66 of the connecting portion 60 is an opening 62. In this way, a differential gear mechanism 10 having an opening 62 can be constructed at low cost.

[0028] [Third Embodiment] The differential gear mechanism 10 according to the third embodiment will be described below with reference to the drawings. In this embodiment, the arrangement of the opening 62 differs from that of the second embodiment. The following description will focus on the differences from the second embodiment. Points that are not specifically described are the same as those in the second embodiment. Figure 8 is a perspective view of the differential gear mechanism 10 of this embodiment.

[0029] In this embodiment, as in the first and second embodiments, the opening 62 is positioned offset from the case opening 38 in the circumferential direction C. That is, the center position of the opening 62 in the circumferential direction C is offset from the center position of the case opening 38 in the circumferential direction C. As shown in Figure 8, the multiple openings 62 have equal lengths in the circumferential direction C and are arranged at equal intervals in the circumferential direction C. Similarly, the multiple case openings 38 have equal lengths in the circumferential direction C and are arranged at equal intervals in the circumferential direction C. In the illustrated example, the concave portion 66 is positioned offset from the case opening 38 in the circumferential direction C. Also, the protruding portion 64 is positioned at the same location in the circumferential direction C as the case opening 38. Since there are two openings 62 and two case openings 38, the openings 62 and 38 are positioned offset from each other by 90 degrees in the circumferential direction C. Thus, in this embodiment, unlike the first and second embodiments, the same number of openings 62 and case openings 38 are provided, and the openings 62 and case openings 38 (specifically, the center positions of the openings 62 and the case openings 38 in the circumferential direction C) are alternately arranged in the circumferential direction C. In the illustrated example, the openings 62 and case openings 38 are arranged alternately in the circumferential direction C at equal intervals. Preferably, the openings 62 are positioned so that their arrangement areas in the circumferential direction C do not overlap with those of the case openings 38.

[0030] In the differential gear mechanism 10 of this embodiment, the case portion 30 is provided with case openings 38 at multiple locations in the circumferential direction C, and the opening 62 is positioned offset from the case openings 38 in the circumferential direction C. This makes it easier to avoid the deformation of the cylindrical portion 40 and the deformation of the case portion 30 concentrating at the same location in the circumferential direction C. Therefore, it is easier to keep the overall deformation of the differential gear mechanism 10 small.

[0031] [Other Embodiments] Next, other embodiments of the differential gear mechanism 10 will be described.

[0032] (1) In the above embodiment, the differential gear set 20 was described as having a configuration in which a first bevel gear 22 and a second bevel gear 24 are present. However, the differential gear set 20 may be configured as a planetary gear mechanism, for example. In this case, the gears constituting the planetary gear mechanism correspond to the "differential gears".

[0033] (2) In the above embodiment, a configuration in which the cylindrical portion 40 and the case portion 30 are separate members was described as an example. However, the configuration is not limited to such a configuration, and the cylindrical portion 40 and the case portion 30 may be integrally formed from the same member. Also, the connecting portion 60 may be made of a separate member from both the case portion 30 and the cylindrical portion 40. Furthermore, the welding points between the connecting portion 60 and the case portion 30 or the cylindrical portion 40 do not have to be on their inner or outer surfaces. Also, the connecting portion 60 may be connected to the case portion 30 or the cylindrical portion 40 by bolts or the like instead of welding.

[0034] (3) In the above embodiment, a configuration was described in which the inner circumferential surfaces 35b of the pair of through holes 35 are in contact with the outer circumferential surface 50a of the output shaft 50. However, the configuration is not limited to such a configuration, and for example, the output shaft 50 may be supported by the case portion 30 via bearings such as ball bearings or bushings, and the inner circumferential surfaces 35b of the through holes 35 may face the outer circumferential surface 50a of the output shaft 50 with a gap between them.

[0035] (4) In the above embodiment, a configuration was described as in which a plurality of openings 62 have equal lengths in the circumferential direction C, are arranged at equal intervals in the circumferential direction C, and are formed in an arc shape parallel to the outer circumferential surface 40a of the cylindrical portion 40. However, the configuration is not limited to such a configuration, and for example, round through holes or square through holes may be arranged at uneven intervals in the circumferential direction C.

[0036] (5) In the above embodiment, a configuration in which a case opening 38 for assembling the first bevel gear 22 and the second bevel gear 24 to the case portion 30 is provided in the case portion 30 was described as an example. However, the configuration is not limited to such a configuration, and for example, the case portion 30 may be configured in which there is no case opening 38.

[0037] (6) In the above embodiment, a configuration in which the opening 62 is positioned offset from the case opening 38 in the circumferential direction C was described as an example. However, the configuration is not limited to such a configuration, and at least one of the multiple openings 62 may be positioned at the same location as the case opening 38 in the circumferential direction C.

[0038] (7) The configurations disclosed in the embodiments described above can be applied in combination with configurations disclosed in other embodiments, as long as they do not cause any inconsistencies. With regard to other configurations, the embodiments disclosed herein are merely illustrative in all respects. Therefore, various modifications can be made as appropriate without departing from the spirit of this disclosure. [Industrial applicability]

[0039] The technology described herein can be used in vehicles equipped with a differential gear mechanism. [Explanation of symbols]

[0040] 10: Differential gear mechanism, 20: Differential gear set, 22: First bevel gear (differential gear), 24: Second bevel gear (differential gear), 30: Case section, 35: Through hole, 35b: Inner circumferential surface, 38: Case opening, 40: Cylindrical section, 45: Outer gear, 50: Output shaft, 50a: Outer circumferential surface, 60: Connecting section, 62: Opening, 64: Protruding section, 66: Concave section

Claims

1. A differential gear set consisting of multiple differential gears that mesh with each other, A case portion for housing the differential gear set, A cylindrical part connected to the case portion, The outer gear formed on the outer surface of the cylindrical portion, A differential gear mechanism equipped with, The differential gear set is configured to distribute the rotation of the outer gear to a pair of output shafts. The direction along the rotation axis of the case portion is defined as the axial direction, the direction perpendicular to the axial direction is defined as the radial direction, and the direction around the rotation axis is defined as the circumferential direction. The cylindrical portion is positioned radially outward from the case portion and connected to the case portion via a connecting portion formed to protrude radially outward from the outer circumferential surface of the case portion. The case portion is provided with through holes through which each of the pair of output shafts passes in the axial direction. The pair of through holes are arranged separately on both sides in the axial direction, flanking the differential gear set. Each of the pair of through holes has an inner surface facing the outer surface of the output shaft, Multiple openings are formed in the circumferential direction of the connecting portion, and the openings penetrate in the axial direction. The connecting portion comprises a plurality of protruding portions provided at multiple locations in the circumferential direction and formed to project radially outward from the case portion, and a concave portion formed between two adjacent protruding portions. The outer circumferential surface of the protruding portion is welded to the cylindrical portion. A differential gear mechanism in which the concave portion of the connecting portion is the opening.

2. The case portion is provided with case openings at multiple locations in the circumferential direction. The differential gear mechanism according to claim 1, wherein the opening is positioned offset from the case opening in the circumferential direction.

3. A differential gear set consisting of multiple differential gears that mesh with each other, A case portion for housing the differential gear set, A cylindrical part connected to the case portion, The outer gear formed on the outer surface of the cylindrical portion, A differential gear mechanism equipped with, The differential gear set is configured to distribute the rotation of the outer gear to a pair of output shafts. The direction along the rotation axis of the case portion is defined as the axial direction, the direction perpendicular to the axial direction is defined as the radial direction, and the direction around the rotation axis is defined as the circumferential direction. The cylindrical portion is positioned radially outward from the case portion and connected to the case portion via a connecting portion formed to protrude radially outward from the outer circumferential surface of the case portion. The case portion is provided with through holes through which each of the pair of output shafts passes in the axial direction. The pair of through holes are arranged separately on both sides in the axial direction, flanking the differential gear set. Each of the pair of through holes has an inner surface facing the outer surface of the output shaft, Multiple openings are formed in the circumferential direction of the connecting portion, and the openings penetrate in the axial direction. The case portion is provided with case openings at multiple locations in the circumferential direction. The opening is a differential gear mechanism located at a position offset from the case opening in the circumferential direction.

4. The connecting portion includes a plate-shaped portion formed in a plate shape that extends in the radial and circumferential directions, The differential gear mechanism according to any one of claims 1 to 3, wherein multiple openings penetrating in the axial direction are formed at multiple locations in the circumferential direction of the plate-like portion.

5. A differential gear mechanism according to any one of claims 1 to 4, wherein the plurality of openings have equal lengths in the circumferential direction and are arranged at equal intervals in the circumferential direction.

6. The differential gear mechanism according to any one of claims 1 to 5, wherein the opening is formed in an arc shape parallel to the outer circumferential surface of the cylindrical portion.

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