DIFFERENTIAL DEVICE

Abstract

A differential device featuring improved durability of a differential housing is provided. One aspect of the present disclosure is a differential device comprising: a ring gear onto which a driving force is applied; and a differential housing comprising a flange section to which the ring gear is connected. The flange section comprises, along a rotational axis of the differential housing: a first outer circumferential portion to which the ring gear is welded; a second outer circumferential portion adjacent to the first outer circumferential portion and whose radius is smaller than that of the first outer circumferential portion; and a third outer circumferential portion adjacent to the second outer circumferential portion.The second outer circumferential part includes, on a side closer to the third outer circumferential part, a section with a smaller radius than on a side closer to the first outer circumferential part.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a differential device. BACKGROUND STATE OF THE ART

[0002] Patent document 1 describes a differential device obtained by welding together a differential housing, which contains a differential mechanism, and a ring gear. Power from a motor vehicle's drive source is transmitted to the ring gear, causing it to rotate, which in turn rotates the differential housing connected to the ring gear. The rotation of the differential housing causes axles coupled to the differential mechanism to rotate. DOCUMENTS ON THE STATE OF TECHNOLOGY PATENT DOCUMENTS

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2021-8898 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] When a torque is applied to rotate the ring gear and the differential housing, stress is concentrated near a welded section between the differential housing and the ring gear, and the differential housing may be susceptible to damage as a result.

[0005] The present disclosure provides a differential device which exhibits improved durability of a differential housing. MEANS TO SOLVE THE PROBLEMS

[0006] One aspect of the present disclosure is a differential device comprising: a ring gear onto which a driving force is applied; and a differential housing comprising a flange section to which the ring gear is connected.

[0007] The flange section comprises, along one axis of rotation of the differential housing: a first outer circumferential part to which the ring gear is welded; a second outer circumferential part which is adjacent to the first outer circumferential part and whose radius is smaller than that of the first outer circumferential part; and a third outer circumferential part which is adjacent to the second outer circumferential part.

[0008] The second outer circumferential part includes, on a side closer to the third outer circumferential part, a section with a smaller radius than on a side closer to the first outer circumferential part.

[0009] In the differential device configured as described in the present disclosure, the stiffness on the side closer to the third outer circumferential part is lower than on the side closer to the first outer circumferential part. Consequently, when the driving force is transmitted from the ring gear to the differential housing, a greater stress concentration is created on the side closer to the third outer circumferential part than on the side closer to the first outer circumferential part. This reduces the stress concentration near a welded part where welding to the ring gear has been performed, thus preventing damage to the differential housing. As a result, the differential device of the present disclosure exhibits improved durability of the differential housing.

[0010] In one aspect of the present disclosure, the second outer circumferential part can be inclined such that its radius along the direction of rotation decreases approximately to that of the third outer circumferential part.

[0011] In the differential device configured as described in the present disclosure, if a corner section is formed on an end section of the second outer circumferential section on the side closer to the first outer circumferential section, the radius of curvature of this corner section can be made larger than if the second outer circumferential section is not inclined. Consequently, in the differential device of the present disclosure, when the driving force is transmitted from the ring gear to the differential housing, the stress concentration near the welded section of the first outer circumferential section, where the welding to the ring gear has been carried out, can be further reduced, thus further preventing damage to the differential housing. This allows the differential device of the present disclosure to exhibit a further improved durability of the differential housing.

[0012] In one aspect of the present disclosure, the second outer circumferential part may further comprise a flat part which is adjacent to the third outer circumferential part and whose radius does not vary along the direction of rotation.

[0013] In the differential device configured as described in the present disclosure, the corner part is formed at an end part of the second outer circumferential part on the side closer to the third outer circumferential part, and the radius of curvature of this corner part can be made larger than in a case where the second outer circumferential part is inclined over its entire area. Accordingly, in the differential device of the present disclosure, a stress concentration near this corner part can be reduced, thereby preventing damage to the differential housing. This allows the differential device of the present disclosure to exhibit a further improved durability of the differential housing.

[0014] In one aspect of the present disclosure, in the flange section, a length along a direction perpendicular to the axis of rotation from the second outer circumferential part to the third outer circumferential part may be longer than a length along the direction perpendicular to the axis of rotation from the first outer circumferential part to the second outer circumferential part.

[0015] In the differential device configured as described in the present disclosure, if the corner part is formed on the end part of the second outer circumferential part on the side closer to the third outer circumferential part, the radius of curvature of this corner part can be made larger. Accordingly, in the differential device of the present disclosure, the stress concentration at this corner part can be reduced, thereby preventing damage to the differential housing. This allows the differential device of the present disclosure to exhibit a further improved durability of the differential housing.

[0016] In one aspect of the present disclosure, the flange section may further comprise a side part which forms a side surface between the first outer circumferential part and the second outer circumferential part. The side part may be designed to be planar.

[0017] The differential device configured in this way according to the present disclosure is provided without any kink points or steps which cause a stress concentration, so that a residual stress which occurs after welding can be reduced.

[0018] In one aspect of the present disclosure, the ring gear can comprise, along the axis of rotation: a first inner circumferential part welded to the first outer circumferential part; a second inner circumferential part adjacent to the first inner circumferential part and whose radius is larger than that of the first outer circumferential part; and a third inner circumferential part adjacent to the second inner circumferential part and fitted onto the third outer circumferential part. The second inner circumferential part can be inclined such that its radius along the axis of rotation is approximately less than that of the third inner circumferential part.

[0019] In the differential device configured as described in the present disclosure, the corner part is formed on an end part of the second inner circumferential part on the side closer to the first inner circumferential part, and the radius of curvature of this corner part can be made smaller. Consequently, in the differential device of the present disclosure, when the driving force is transmitted from the ring gear to the differential housing, it is possible to increase the stress exerted on the ring gear, thereby reducing the stress exerted on the differential housing. Accordingly, damage to the differential housing can be prevented in the differential device of the present disclosure, and the durability of the differential housing can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a sectional view showing a configuration of a differential device. Fig. Figure 2 is a sectional view showing a configuration of a flange section and an annular section of a first embodiment. Fig. Figure 3 is a sectional view showing a state in which the flange section and the annular section of the first embodiment are attached to each other. Fig. Figure 4 is a sectional view showing a configuration of a flange section and an annular section of a second embodiment. Fig. Figure 5 is a sectional view showing a configuration of a flange section and an annular section of a third embodiment. Fig. Figure 6 is a sectional view showing a configuration of a flanged section and an annular section of a fourth embodiment. Fig. Figure 7 is a sectional view showing a configuration of a flanged section and an annular section of a fifth embodiment. EXPLANATION OF THE REFERENCE SYMBOLS

[0020] 1...Differential device, 2...Differential housing, 4...Ring gear, 24...Flange section, 51...First outer circumferential part, 52...Second outer circumferential part, 53...Third outer circumferential part. MODE FOR EXECUTING THE INVENTION [1. First embodiment]

[0021] A first embodiment of the present disclosure is described below with reference to the drawings. [1-1. Configuration of the differential device]

[0022] One in Fig. 1 The differential device shown is a device which is installed in a motor vehicle and which transmits power from a drive source (e.g. an engine) of the motor vehicle to axles of the motor vehicle not shown.

[0023] The differential device 1 comprises a differential housing 2, a differential mechanism 3 and a ring gear 4.

[0024] The differential housing 2 comprises a housing section 21, a first sleeve 22, a second sleeve 23, and a flange section 24. The differential housing 2 is connected to the ring gear 4 at the flange section 24, causing it to rotate integrally with the ring gear 4. A rotation axis C1 of the differential housing 2 is hereinafter referred to as a housing rotation axis C1.

[0025] The housing section 21 is a body part of the differential housing 2 and accommodates the differential mechanism 3 within it.

[0026] The first sleeve 22 is a cylindrical section coupled to the housing section 21, allowing a first axle to be inserted into it. The first sleeve 22 extends from the housing section 21 along the housing rotation axis C1 towards the outer edge of the differential housing 2. The first axle is inserted into the first sleeve 22 such that a first end of the first axle is located within an inner space of the housing section 21.

[0027] The second sleeve 23 is a cylindrical section which is coupled to the housing section 21 on the side opposite to the side on which the first sleeve 22 is arranged above the housing section 21, and which allows a second axle to be inserted into it. The second sleeve 23 extends from the housing section 21 along the housing rotation axis C1 towards the outside of the differential housing 2. The second axle is inserted into the second sleeve 23 such that a first end of the second axle is located within the inner space of the housing section 21.

[0028] The differential mechanism 3 comprises a first pinion gear 31, a second pinion gear 32, a pinion shaft 33, a first lateral gear 34, and a second lateral gear 35. The differential mechanism 3 is arranged within the differential housing 2. In particular, the first pinion gear 31, the second pinion gear 32, the pinion shaft 33, the first lateral gear 34, and the second lateral gear 35 are accommodated in the housing section 21 of the differential housing 2.

[0029] The first pinion gear 31 and the second pinion gear 32 are each a bevel gear which has an axis of rotation perpendicular to the housing axis of rotation C1.

[0030] The axis of rotation of the first pinion gear 31 and the axis of rotation of the second pinion gear 32 coincide. The first pinion gear 31 and the second pinion gear 32 are arranged such that they face each other. In the following, the axis of rotation of the first pinion gear 31 and the axis of rotation of the second pinion gear 32 are collectively referred to as a pinion gear axis of rotation C2.

[0031] The pinion shaft 33 holds the first pinion gear 31 and the second pinion gear 32, respectively, in a rotatable manner. The central axis of the pinion shaft 33 (i.e., the pinion gear rotation axis C2) is perpendicular to the housing rotation axis C1. The pinion shaft 33 is fixed to the housing section 21 and does not rotate relative to the differential housing 2. That is, the pinion shaft 33 rotates together with the housing section 21 about the housing rotation axis C1.

[0032] The first side gear 34 and the second side gear 35 are each a bevel gear which has an axis of rotation which coincides with the housing axis of rotation C1.

[0033] The axis of rotation of the first lateral gear 34 and the axis of rotation of the second lateral gear 35 coincide. The first lateral gear 34 and the second lateral gear 35 are arranged such that they face each other.

[0034] The first lateral gear 34 is toothed at the first end of the first axle such that it meshes with the first pinion gear 31 and the second pinion gear 32. The second lateral gear 35 is toothed at the first end of the second axle such that it meshes with the first pinion gear 31 and the second pinion gear 32.

[0035] The first side gear 34 and the second side gear 35 rotate together with the differential housing 2 and are simultaneously rotated relative to the differential housing 2 by the rotation transmitted by the first pinion gear 31 and the second pinion gear 32.

[0036] The first axle and the second axle rotate differently due to the coupled differential mechanism 3, while rotating in accordance with a direction of rotation of the differential housing 2.

[0037] The flange section 24 is an annular section that projects radially outwards from the housing section 21. The flange section 24 projects, with respect to a plane containing the pinion gear axis of rotation C2 and perpendicular to the housing axis of rotation C1, on the side of the housing section 21 where the first lateral gear 34 is located. The flange section 24 is attached to the annular gear 4 by a method combining fitting and welding, as described below.

[0038] The flange section 24 is formed in the differential housing 2 such that it projects along the housing rotation axis C1 in a direction away from the pinion shaft 33. This results in an annular recess 26 being formed between the differential housing 2 and the flange section 24.

[0039] The ring gear 4 is a helical gear which has an axis of rotation that coincides with the housing axis of rotation C1.

[0040] The ring gear 4 comprises a tooth section 41 with a cylindrical shape, which has several teeth formed on its outer circumferential surface, and an annular section 42 with a ring shape, which projects from an inner circumferential surface of the tooth section 41 in the direction of the axis of rotation of the ring gear 4.

[0041] The ring gear 4 meshes with a drive gear, which is rotated by a rotary force from the drive source, and such a drive force is introduced into the ring gear 4 from the drive source. The ring gear 4 is attached to the differential housing 2, which is arranged within it. This allows the ring gear 4 to rotate the differential housing 2 by the rotary force transmitted from the drive source. [1-2. Configuration of the flange section and the annular section]

[0042] As in Fig. As shown in Figure 2, an outer circumferential surface 50 of the flange section 24 comprises a first outer circumferential part 51, a second outer circumferential part 52, a third outer circumferential part 53 and a fourth outer circumferential part 54, which are arranged in this order from the side furthest from the pinion gear rotation axis C2 along a direction D1 parallel to the housing rotation axis C1.

[0043] The first outer circumferential part 51 is formed such that its radius (i.e. its distance from the housing rotation axis C1) does not vary along the direction D1.

[0044] The second outer circumferential part 52 is formed such that its radius is smaller than that of the first outer circumferential part 51. The second outer circumferential part 52 comprises a first curved part 52a, a tapered part 52b, a flat part 52c and a second curved part 52d, which are arranged in this order from the side furthest from the pinion gear axis of rotation C2 along the direction D1.

[0045] The first curved part 52a is an arc in a section of the flange section 24 taken along the direction D1.

[0046] The tapered section 52b is inclined such that its radius decreases as it approaches the pinion gear axis of rotation C2 along direction D1. Accordingly, in the section of the flange section 24 taken along direction D1, the tapered section 52b is a straight line which is inclined such that it lies closer to the housing axis of rotation C1 as it approaches the pinion gear axis of rotation C2.

[0047] The flat section 52c is shaped such that its radius does not vary along direction D1. Accordingly, the flat section 52c in the portion of the flange section 24 taken along direction D1 is a straight line parallel to the housing rotation axis C1.

[0048] The second curved part 52d is an arc in the section of the flange section 24 taken along the direction D1.

[0049] The third outer circumferential section 53 is formed such that its radius is larger than that of the second outer circumferential section 52. Furthermore, the third outer circumferential section 53 is formed such that its radius does not vary along direction D1. In the present embodiment, the radius of the first outer circumferential section 51 and the radius of the third outer circumferential section 53 are equal to each other. However, the radius of the first outer circumferential section 51 and the radius of the third outer circumferential section 53 need not necessarily be equal to each other.

[0050] The fourth outer circumferential section 54 is inclined such that its radius decreases as it approaches the pinion gear axis of rotation C2 along direction D1. Accordingly, in the section of the flange section 24 taken along direction D1, the fourth outer circumferential section 54 is a straight line which is inclined such that it lies closer to the housing axis of rotation C1 as it approaches the pinion gear axis of rotation C2.

[0051] The flange section 24 comprises a first side part 55, which forms a side surface between the first outer circumferential part 51 and the second outer circumferential part 52, and a second side part 56, which forms a side surface between the second outer circumferential part 52 and the third outer circumferential part 53.

[0052] The first side part 55 is a surface which is perpendicular to the first outer circumferential part 51. Accordingly, the first side part 55 in the section of the flange section 24 taken along direction D1 is a straight line which is perpendicular to the housing rotation axis C1.

[0053] The second side part 56 is a surface which is perpendicular to the third outer circumferential part 53. Accordingly, the second side part 56 in the section of the flange section 24 taken along direction D1 is a straight line which is perpendicular to the housing rotation axis C1.

[0054] The length from the second outer circumferential part 52 to the third outer circumferential part 53 along a direction perpendicular to the direction D1 (i.e., the length of the second side part 56) is longer than the length from the first outer circumferential part 51 to the second outer circumferential part 52 along the direction perpendicular to the direction D1 (i.e., the length of the first side part 55).

[0055] The flange section 24 comprises a third side part 57, which is continuous in direction D1 with a first end part of the outer circumferential surface 50 (i.e., with the first outer circumferential part 51). The flange section 24 comprises a fourth side part 58, which is continuous in direction D1 with a second end part of the outer circumferential surface 50 (i.e., with the fourth outer circumferential part 54). The third side part 57 and the fourth side part 58 are surfaces that are perpendicular to the housing axis of rotation C1.

[0056] An inner circumferential surface 60 of the annular section 42 comprises a first inner circumferential part 61, a second inner circumferential part 62, a third inner circumferential part 63, a fourth inner circumferential part 64 and a fifth inner circumferential part 65, which are arranged in this order from the side furthest from the pinion gear rotation axis C2 along the direction D1 parallel to the housing rotation axis C1.

[0057] The first inner circumferential part 61, the second inner circumferential part 62, the third inner circumferential part 63 and the fourth inner circumferential part 64 are equal in length along the direction D1 to the first outer circumferential part 51, the second outer circumferential part 52, the third outer circumferential part 53 and the fourth outer circumferential part 54.

[0058] The first inner circumferential part 61 is formed such that its radius (i.e. its distance from the axis of rotation of the ring gear 4) does not vary along the direction D1.

[0059] The second inner circumferential part 62 comprises a curved part 62a and a tapered part 62b, which are arranged in this order from the side furthest from the pinion gear axis of rotation C2 along the direction D1.

[0060] The curved part 62a is an arc in a section of the ring-shaped part 42 taken along the direction D1.

[0061] The tapered section 62b is inclined such that its radius decreases as it approaches the pinion gear axis of rotation C2 along direction D1. Accordingly, in the section of the annular part 42 along direction D1, the tapered section 62b is a straight line which is inclined such that it lies closer to the housing axis of rotation C1 as it approaches the pinion gear axis of rotation C2.

[0062] The third inner circumferential section 63 is designed such that its radius does not vary along direction D1. In the present embodiment, the radius of the first inner circumferential section 61 and the radius of the third inner circumferential section 63 are equal to each other. The radius of the first inner circumferential section 61 is set to be equal to the radius of the first outer circumferential section 51, and the radius of the third inner circumferential section 63 is set to be equal to the radius of the third outer circumferential section 53.

[0063] The fourth inner circumferential part 64 is an arc in the section of the ring-shaped part 42 taken along the direction D1.

[0064] The fifth inner circumferential part 65 comprises a tapered part 65a and a flat part 65b, which are arranged in this order from the side furthest from the pinion gear axis of rotation C2 along the direction D1.

[0065] The tapered part 65a is a straight line which is inclined such that it lies closer to the housing axis of rotation C1 when it approaches the pinion gear axis of rotation C2 in the section of the annular part 42 taken along the direction D1.

[0066] The flat part 65b is shaped such that its radius does not vary along direction D1. Accordingly, in the section of the annular part 42 taken along direction D1, the flat part 65b is a straight line parallel to the housing rotation axis C1.

[0067] The annular section 42 comprises a first side part 66, which forms a side surface between the first inner circumferential part 61 and the second inner circumferential part 62, and a second side part 67, which forms a side surface between the fourth inner circumferential part 64 and the fifth inner circumferential part 65.

[0068] The first side part 66 is a surface perpendicular to the first inner circumferential part 61. Accordingly, the first side part 66, in the section of the annular section 42 measured along direction D1, is a straight line perpendicular to the housing rotation axis C1. The second side part 67 is a surface perpendicular to the housing rotation axis C1.

[0069] The annular section 42 includes a third side part 68, which is continuous in the direction D1 with a first end part of the inner circumferential surface 60 (i.e., with the first inner circumferential part 61). The annular section 42 includes a fourth side part 69, which is continuous in the direction D1 with a second end part of the inner circumferential surface 60 (i.e., with the fifth inner circumferential part 65). The third side part 68 and the fourth side part 69 are surfaces that are perpendicular to the housing rotation axis C1.

[0070] Next, a method for attaching the annular section 42 of the ring gear 4 to the flange section 24 of the differential housing 2 is described.

[0071] As in Fig. As shown in Figure 3, the third inner circumferential portion 63 of the annular section 42 of the ring gear 4 is first fitted onto the third outer circumferential portion 53 of the flange section 24, and the second side portion 67 of the annular section 42 is brought into contact with the fourth side portion 58 of the flange section 24. This causes the first outer circumferential portion 51 and the third outer circumferential portion 53 of the flange section 24 to come into contact with the first inner circumferential portion 61 and the third inner circumferential portion 63 of the annular section 42, respectively, thereby positioning the annular section 42 radially and axially with respect to the flange section 24. Meanwhile, a cavity 70 is formed between the second outer circumferential portion 52 of the flange section 24 and the second inner circumferential portion 62 of the annular section 42.

[0072] A laser is then applied to an area on the third side 57 of the flange section 24 and the third side 68 of the annular section 42, where the first outer circumferential part 51 of the flange section 24 and the first inner circumferential part 61 of the annular section 42 are in contact, thereby welding the first outer circumferential part 51 of the flange section 24 and the first inner circumferential part 61 of the annular section 42 together, as indicated by a welded part 72. This causes the annular section 42 of the ring gear 4 to be attached to the flange section 2 of the differential housing 2.

[0073] The second outer circumferential section 52 comprises a corner section formed at an end of the second outer circumferential section 52 on the side closer to the first outer circumferential section 51, and a linear section adjacent to the corner section on the side of the corner section closer to the third outer circumferential section 53, which is formed such that it is linear in the segment measured along direction D1. The second outer circumferential section 52 includes, on the side that is closer to the third outer circumferential section 53 relative to the corner section, a portion in which its radius is smaller than that of the corner section. The first curved portion 52a corresponds to the corner section, and the tapered portion 52b and the flat portion 52c correspond to the linear portion. [1-3. Effects]

[0074] The first embodiment described in detail above produces the effects shown below. (1a) In the differential device 1, the radius of the first curved part 52a is larger than the radius on the side closer to the third outer circumferential part 53. That is, the second outer circumferential part 52 comprises, on the side closer to the third outer circumferential part 53, a portion with a smaller radius than on the side closer to the first outer circumferential part 51. Accordingly, in the differential device 1, the stiffness on the side closer to the third outer circumferential part 53 is less than the stiffness in the first curved part 52a.Consequently, in the differential device 1, when the drive force is transmitted from the ring gear 4 to the differential housing 2, stress is concentrated on the side closer to the third outer circumferential part 53 than on the side closer to the first outer circumferential part 51. This reduces the stress concentration near the welded part 72, where the welding to the ring gear 4 has been carried out, in the first outer circumferential part 51, thus preventing damage to the differential housing 2. This allows the differential device 1 to exhibit improved durability of the differential housing 2. (1b) In the differential device 1, if the first curved part 52a is formed on the end part of the second outer circumferential part 52 on the side closer to the first outer circumferential part 51, the radius of curvature of this first curved part 52a can be larger than if the second outer circumferential part 52 is not inclined. Consequently, in the differential device 1, when the driving force is transmitted from the ring gear 4 to the differential housing 2, the stress concentration near the welded part 72, where the welding to the ring gear 4 has been carried out, in the first outer circumferential part 51 can be further reduced, thus further preventing damage to the differential housing 2. This allows the differential device 1 to have a further improved durability of the differential housing 2. (1c) In the differential device 1, if the second curved part 52d is formed at an end part of the second outer circumferential part 52 on the side closer to the third outer circumferential part 53, the radius of curvature of this second curved part 52d can be made larger than if the second outer circumferential part 52 is inclined over its entire area. Accordingly, in the differential device 1, a stress concentration near the second curved part 52d can be reduced, thereby preventing damage to the differential housing 2. This allows the differential device 1 to exhibit further improved durability of the differential housing 2. (1d) In the differential device 1, since the length of the second side part 56 is longer than the length of the first side part 55, the radius of curvature of the second curved part 52d can be made larger if it is formed on the end part of the second outer circumferential part 52 on the side closer to the third outer circumferential part 53. Accordingly, the stress concentration on the second curved part 52d in the differential device 1 can be reduced, thus preventing damage to the differential housing 2. This allows the differential device 1 to exhibit further improved durability of the differential housing 2. (1e) In the differential device 1, the first side part 55 is formed in such a way that it is planar, so that any residual stress occurring after welding can be reduced. (1f) In the differential device 1, if the curved part 62a is formed on the end of the second inner circumferential part 62 on the side closer to the first inner circumferential part 61, the radius of curvature of the curved part 62a can be made smaller. Consequently, in the differential device 1, when the driving force is transmitted from the ring gear 4 to the differential housing, it is possible to increase the stress exerted on the ring gear 4, thereby reducing the stress exerted on the differential housing 2. Accordingly, damage to the differential housing 2 can be prevented in the differential device 1, and the durability of the differential housing 2 can be further improved.

[0075] In the embodiment described above, direction D1 corresponds to a direction of rotation, the first side part 55 corresponds to a side part, and the flat part 52c and the second curved part 52d correspond to "a part with a smaller radius". [2. Second embodiment]

[0076] A second embodiment of the present disclosure is described below with reference to the drawings. Differences from the first embodiment are described in the second embodiment. The common elements are identified by the same reference numerals.

[0077] The differential device 1 of the second embodiment differs from that of the first embodiment in that the configuration of the second outer circumferential part 52 of the flange section 24 has been modified.

[0078] As in Fig. As shown in Figure 4, the second outer circumferential part 52 of the second embodiment comprises the first curved part 52a, a tapered part 52e and a second curved part 52f, which are arranged in this order from the side furthest from the pinion gear axis of rotation C2 along the direction D1.

[0079] The tapered section 52e is inclined such that its radius decreases as it approaches the pinion gear axis of rotation C2 along direction D1. Accordingly, in the section of the flange section 24 taken along direction D1, the tapered section 52e is a straight line which is inclined such that it lies closer to the housing axis of rotation C1 as it approaches the pinion gear axis of rotation C2.

[0080] The second curved part 52f is an arc taken along the direction D1 in the section of the flange section 24.

[0081] The second outer circumferential section 52 comprises a corner section formed at the end of the second outer circumferential section 52 on the side closer to the first outer circumferential section 51, and a straight section adjacent to the corner section on the side of the corner section closer to the third outer circumferential section 53, and which is formed such that it is straight in the segment measured along direction D1. The second outer circumferential section 52 includes, on the side that is closer to the third outer circumferential section 53 relative to the corner section, a portion in which its radius is smaller than that of the corner section. The first curved portion 52a corresponds to the corner section, and the tapered portion 52e corresponds to the straight portion.

[0082] The second embodiment described in detail above produces the following effect.

[0083] In the differential device 1, if the first curved section 52a is formed on the end of the second outer circumferential section 52 on the side closer to the first outer circumferential section 51, the radius of curvature of this first curved section 52a can be larger than if the second outer circumferential section 52 is not inclined. Consequently, when the drive force is transmitted from the ring gear 4 to the differential housing 2 in the differential device 1, the stress concentration near the welded section 72, where the welding to the ring gear 4 has been carried out, can be reduced in the first outer circumferential section 51, thus preventing damage to the differential housing 2. This allows the differential device 1 to exhibit improved durability of the differential housing 2.

[0084] In the embodiment described above, the second curved part 52f corresponds to “a part with a smaller radius”. [3. Third embodiment]

[0085] A third embodiment of the present disclosure is described below with reference to the drawings. Differences between the third embodiment and the first embodiment are described. The common elements are identified by the same reference numerals.

[0086] The differential device 1 of the third embodiment differs from that of the first embodiment in that the configuration of the second outer circumferential part 52 and the second side part 56 of the flange section 24 has been modified.

[0087] As in Fig. As shown in Figure 5, the second outer circumferential part 52 of the second embodiment comprises the first curved part 52a, a first tapered part 52b, a flat part 52g and a second curved part 52h, which are arranged in this order from the side furthest from the pinion gear axis of rotation C2 along the direction D1.

[0088] The flat section 52g is shaped such that its radius does not vary along direction D1. Accordingly, the flat section 52g in the portion of the flange section 24 taken along direction D1 is a straight line parallel to the housing rotation axis C1.

[0089] The second curved part 52h is an arc in the section of flange section 24 taken along the direction D1.

[0090] The second side section 56 is inclined such that its radius increases as it approaches the pinion gear axis of rotation C2 along direction D1. Accordingly, the second side section 56 is a straight line inclined such that it has a greater distance from the housing axis of rotation C1 as it approaches the pinion gear axis of rotation C2 in the section of the flange section 24 taken along direction D1.

[0091] The second outer circumferential section 52 comprises a corner section formed at the end of the second outer circumferential section 52 on the side closer to the first outer circumferential section 51, and a linear section adjacent to the corner section on the side of the corner section closer to the third outer circumferential section 53, which is formed such that it is linear in the segment along direction D1. The second outer circumferential section 52 includes, on the side that is closer to the third outer circumferential section 53 relative to the corner section, a portion in which its radius is smaller than that of the corner section. The first curved portion 52a corresponds to the corner section, and the tapered portion 52b and the flat portion 52g correspond to the linear portion.

[0092] The third embodiment, described in detail above, produces the effects shown below. (3a) In the differential device 1, if the second curved part 52h is formed on the end part of the second outer circumferential part 52 on the side closer to the third outer circumferential part 53, the radius of curvature of this second curved part 52h can be made larger than if the second outer circumferential part 52 is inclined over its entire area. Accordingly, in the differential device 1, a stress concentration near the second curved part 52h can be reduced, thereby preventing damage to the differential housing 2. This allows the differential device 1 to exhibit further improved durability of the differential housing 2. (3b) In the differential device 1, if the second curved part 52h is formed on the end part of the second outer circumferential part 52 on the side closer to the third outer circumferential part 53, the radius of curvature of this second curved part 52h can be made larger than if the second side part 56 is perpendicular to the third outer circumferential part 53. Accordingly, in the differential device 1, a stress concentration near the second curved part 52h can be reduced, thereby preventing damage to the differential housing 2. This allows the differential device 1 to exhibit further improved durability of the differential housing 2.

[0093] In the embodiment described above, the flat part 52g and the second curved part 52h correspond to "a part with a smaller radius". [4. Fourth embodiment]

[0094] A fourth embodiment of the present disclosure is described below with reference to the drawings. Differences between the fourth embodiment and the second embodiment are described. The common elements are identified by the same reference numerals.

[0095] The differential device 1 of the fourth embodiment differs from that of the second embodiment in that the configuration of the second outer circumferential part 52 and the second side part 56 of the flange section 24 has been modified.

[0096] As in Fig. As shown in Figure 6, the second outer circumferential part 52 of the second embodiment comprises the first curved part 52a, a first tapered part 52i and a second curved part 52j, which are arranged in this order from the side furthest from the pinion gear axis of rotation C2 along the direction D1.

[0097] The first tapered section 52i is inclined such that its radius decreases as it approaches the pinion gear axis of rotation C2 along direction D1. Accordingly, in the section of the flange section 24 taken along direction D1, the first tapered section 52i is a straight line which is inclined such that it lies closer to the housing axis of rotation C1 as it approaches the pinion gear axis of rotation C2.

[0098] The second curved part 52j is an arc in the section of the flange section 24 taken along the direction D1.

[0099] The second side section 56 is inclined such that its radius increases as it approaches the pinion gear axis of rotation C2 along direction D1. Accordingly, in the section of the flange section 24 taken along direction D1, the second side section 56 is a straight line which is inclined such that it is further away from the housing axis of rotation C1 as it approaches the pinion gear axis of rotation C2.

[0100] The second outer circumferential section 52 comprises a corner section formed at the end of the second outer circumferential section 52 on the side closer to the first outer circumferential section 51, and a straight section adjacent to the corner section on the side of the corner section closer to the third outer circumferential section 53, and which is formed such that it is straight in the segment measured along direction D1. The second outer circumferential section 52 includes, on the side that is closer to the third outer circumferential section 53 relative to the corner section, a portion in which its radius is smaller than that of the corner section. The first curved portion 52a corresponds to the corner section, and the first tapered portion 52i corresponds to the straight portion.

[0101] The fourth embodiment, described in detail above, produces the following effect.

[0102] In the differential device 1, if the second curved part 52j is formed on the end part of the second outer circumferential part 52 on the side closer to the third outer circumferential part 53, the radius of curvature of this second curved part 52j can be larger than if the second side part 56 is perpendicular to the third outer circumferential part 53. Accordingly, the stress concentration near the second curved part 52j in the differential device 1 can be reduced, thus preventing damage to the differential housing 2. This allows the differential device 1 to exhibit further improved durability of the differential housing 2.

[0103] In the embodiment described above, the second curved part 52j corresponds to "a part with a smaller radius". [5. Fifth embodiment]

[0104] A fifth embodiment of the present disclosure is described below with reference to the drawings. Differences between the fifth embodiment and the first embodiment are described. The common elements are identified by the same reference numerals.

[0105] The differential device 1 of the fifth embodiment differs from that of the first embodiment in that the configuration of the second outer circumferential part 52 of the flange section 24 has been modified.

[0106] As in Fig. As shown in Figure 7, the second outer circumferential part 52 of the fifth embodiment comprises a first curved part 52k, a first flat part 52l, a side part 52m, a second flat part 52n and the second curved part 52d, which are arranged in this order from the side furthest from the pinion gear axis of rotation C2 along the direction D1.

[0107] The first curved part 52k is an arc in the section of flange section 24 taken along the direction D1.

[0108] The first flat section 52l is formed such that its radius does not vary along direction D1. Accordingly, the first flat section 52l in the portion of the flange section 24 taken along direction D1 is a straight line parallel to the housing rotation axis C1.

[0109] The side part 52m is a surface which is perpendicular to the first outer circumferential part 51. Accordingly, the side part 52m in the section of the flange section 24 taken along direction D1 is a straight line which is perpendicular to the housing rotation axis C1.

[0110] The second flat part 52n is formed such that its radius does not vary along direction D1. Accordingly, the second flat part 52n, in the section of the flange section 24 taken along direction D1, is a straight line parallel to the housing rotation axis C1.

[0111] The second outer circumferential section 52 comprises a corner section formed at the end of the second outer circumferential section 52 on the side closer to the first outer circumferential section 51, and a linear section adjacent to the corner section on the side of the corner section closer to the third outer circumferential section 53, which is formed such that it is linear in the segment along direction D1. The second outer circumferential section 52 includes, on the side closer to the third outer circumferential section 53 relative to the corner section, a section in which its radius is smaller than that of the corner section. The first curved section 52k corresponds to the corner section, and the first flat section 52l and the second flat section 52n correspond to the linear section.

[0112] The fifth embodiment, described in detail above, produces the following effect.

[0113] In the differential device 1, the radius of the first curved part 52k is larger than the radius of the second flat part 52n, which is located on the side that is closer to the third outer circumferential part 53 relative to the first curved part 52k. That is, in the flange section 24, the radius of the first flat part 52l is larger than that of the second flat part 52n. Accordingly, in the differential device 1, the stiffness in the second flat part 52n is lower than the stiffness in the first curved part 52k.Consequently, in the differential device 1, when the driving force is transmitted from the ring gear 4 to the differential housing 2, a stress is concentrated on the side that is closer to the third outer circumferential part 53 relative to the first curved part 52k, and a stress concentration near the welded part 72, where the welding to the ring gear 4 has been carried out, can be reduced in the first outer circumferential part 51, thus preventing damage to the differential housing 2. This allows the differential device 1 to exhibit improved durability of the differential housing 2.

[0114] In the embodiment described above, the second flat part 52n and the second curved part 52d correspond to “a part with a smaller radius”. [6. Other embodiments]

[0115] Although the embodiments of the present disclosure have been described so far, the present disclosure is not limited to the embodiments described above and can be implemented in various modified modes. (6a) In the embodiments described above, one mode is specified in which the differential device 1 is installed in the motor vehicle; however, the differential device 1 can also be used in various other mechanical devices besides the motor vehicle. (6b) In the embodiments described above, two or more functions comprising a single element can be implemented by a plurality of elements, and a single function comprising a single element can be implemented by a plurality of elements. Two or more functions comprising a plurality of elements can be implemented by a single element, and a single function implemented by a plurality of elements can be implemented by a single element. Part of the configuration in the embodiments described above can be omitted. At least part of the configuration in the embodiments described above can be added to or replaced by the configuration in other embodiments. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2021-8898

[0003]

Claims

[1] Differential device comprising: a ring gear onto which a driving force is applied; and a differential housing which includes a flange section to which the ring gear is connected, wherein the flange section extends along a rotational axis direction of the differential housing: a first outer circumferential part to which the ring gear is welded; a second outer circumferential part, which is adjacent to the first outer circumferential part and whose radius is smaller than that of the first outer circumferential part; and a third outer circumferential part, which is adjacent to the second outer circumferential part, and wherein the second outer circumferential part includes a portion with a smaller radius on a side closer to the third outer circumferential part than on a side closer to the first outer circumferential part. [2] Differential device according to claim 1, wherein the second outer circumferential part is inclined such that its radius along the axis of rotation is approximately less than that of the third outer circumferential part. [3] Differential device according to claim 2, wherein the second outer circumferential part further comprises a flat part which is adjacent to the third outer circumferential part and whose radius does not vary along the direction of rotation. [4] Differential device according to claim 2, wherein in the flange section a length along a direction perpendicular to the axis of rotation from the second outer circumferential part to the third outer circumferential part is longer than a length along the direction perpendicular to the axis of rotation from the first outer circumferential part to the second outer circumferential part. [5] Differential device according to claim 1 or 2, wherein the flange section further comprises a side part which forms a side surface between the first outer circumferential part and the second outer circumferential part, and wherein the side part is formed in such a way that it is planar. [6] Differential device according to claim 1 or 2, the ring gear encompasses along the direction of rotation: a first inner circumferential part, which is welded to the first outer circumferential part; a second inner circumferential part, which is adjacent to the first inner circumferential part and whose radius is larger than that of the first outer circumferential part; and a third inner circumferential part, which is adjacent to the second inner circumferential part and which is fitted onto the third outer circumferential part, and wherein the second inner circumferential part is inclined such that its radius along the direction of rotation is approximately less than that of the third inner circumferential part.

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