Differential gear device

Abstract

To prevent or suppress the deformation of a ring gear.SOLUTION: A differential gear device includes a differential case, and a ring gear fixed to the differential case. In this case, on the outer peripheral face of the differential case, an outward flange is provided protruded to the radial outside toward the ring gear, and on the inner peripheral face of the ring gear, an inward flange is provided offset to one side in the axial direction, protruded to the radial inside toward the differential case. In addition, the outward flange and the inward flange are opposed to each other in the axial direction and fastened to each other with a plurality of bolts. The inward flange is thicker at its outer peripheral portion located on the radial outside with respect to the inner peripheral portion, than at its inner peripheral portion opposed to the outward flange.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a differential gear device. [Background technology]

[0002] Patent Document 1 describes a differential gear device. The differential gear device includes a differential case and and a ring gear fixed to the differential case. The differential case has an outward flange on its outer circumferential surface. The ring gear has an inward flange on its inner circumferential surface, and the outward flange and the inward flange are fastened to each other by a plurality of bolts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2010-144911 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above differential gear device, the inward flange of the ring gear is offset to one side in the axial direction on the ring gear. That is, on the inner peripheral surface of the ring gear, the inward flange is disposed toward one side, not in the center in the axial direction. With this configuration, the position where the inward flange supports the ring gear is biased toward one side in the axial direction with respect to the meshing load acting on the ring gear. Therefore, when the meshing load acts on the ring gear, the ring gear is likely to be displaced radially inward (tooth tilt) and deform (tooth deflection) on the other axial side away from the inward flange. This specification provides a technology that can prevent or suppress deformation of the ring gear. [Means for solving the problem]

[0005] The differential gear device according to the technology disclosed in this specification includes a differential case and a ring gear fixed to the differential case. In this case, an outward flange protruding radially outward toward the ring gear is provided on the outer peripheral surface of the differential case, and an inward flange protruding radially inward toward the differential case is provided on the inner peripheral surface of the ring gear, offset to one side in the axial direction. In addition, the outward flange and the inward flange face each other in the axial direction and are fastened to each other by a plurality of bolts. In addition, the thickness of the inward flange is greater at an outer peripheral portion located radially outward from the inner peripheral portion than at an inner peripheral portion facing the outward flange.

[0006] In the above-described configuration, the outer peripheral portion of the inward flange provided on the ring gear, i.e., the portion located at the base of the inward flange, is formed thicker than the inner peripheral portion thereof. With this configuration, even if the position of the inward flange is offset in the axial direction, it is possible to prevent or suppress displacement or deformation of the other axial side of the ring gear due to the load acting on the ring gear during meshing. [Brief description of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing a configuration of a differential gear device 10. FIG. [Diagram 2] 1 shows an enlarged view of part II in FIG. [Diagram 3] FIG. 4 is a diagram illustrating a load acting on a ring gear. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES

[0008] A differential gear device 10 according to an embodiment will be described with reference to the drawings. The differential gear device 10 according to the embodiment is a differential gear device for a vehicle. Note that in this specification, only the essential parts related to the technology disclosed in the present technology will be described, and a detailed description of the differential gear device 10 will be omitted.

[0009] As shown in FIGS. 1 and 2, the differential gear device 10 includes a differential case 12 and a ring gear 14 fixed to the differential case 12.

[0010] The differential case 12 accommodates a plurality of gears therein. The plurality of gears includes a plurality of pinion gears and two side gears.

[0011] An outward flange 13 that protrudes radially outward toward the ring gear 14 is provided on the outer peripheral surface 12b of the differential case 12. The outward flange 13 has an annular plate shape and goes around the outer peripheral surface 12b of the differential case 12 in the circumferential direction.

[0012] The ring gear 14 is a gear member having an annular shape. The ring gear 14 is disposed so as to surround the differential case 12 from the radially outer side. A tooth surface constituting a plurality of teeth is formed on an outer peripheral surface 14b of the ring gear 14. The plurality of teeth of the ring gear 14 are helical teeth. However, the teeth of the ring gear 14 are not limited to helical teeth, and may be spur teeth.

[0013] An inward flange 15 that protrudes radially inward toward the differential case 12 is provided on the inner peripheral surface 14a of the ring gear 14. The inward flange 15 has an annular plate shape and goes around the inner peripheral surface 14a of the ring gear 14 in the circumferential direction. The inward flange 15 is offset to one side in the axial direction on the inner peripheral surface 14a of the ring gear 14. The inward flange 15 faces the outward flange 13 of the differential case 12 in the axial direction.

[0014] The outward flange 13 of the differential case 12 is provided with a plurality of fastening holes 13h. The plurality of fastening holes 13h are so-called drilled holes, and pass through the outward flange 13 in the axial direction. Similarly, the inward flange 15 of the ring gear 14 is also provided with a plurality of fastening holes 15h. The plurality of fastening holes 15h are threaded through holes, and pass through the inward flange 15 in the axial direction. The plurality of fastening holes 15h of the inward flange 15 are arranged to match the plurality of fastening holes 13h of the outward flange 13.

[0015] The outward flange 13 and the inward flange 15 are fastened to each other by a plurality of bolts 16. Specifically, the plurality of bolts 16 pass through a washer 17, the outward flange 13, and the inward flange 15 in this order from the other side of the ring gear 14, to fix the differential case 12 and the ring gear 14 to each other.

[0016] The inward flange 15 of the ring gear 14 will be mainly described in detail with reference to Figures 2 and 3. As shown in Figures 2 and 3, the inward flange 15 has an inner peripheral portion 15a and an outer peripheral portion 15b located radially outward from the inner peripheral portion 15a. The inner peripheral portion 15a of the inward flange 15 faces the outward flange 13 of the differential case 12 in the axial direction. The thickness T1 of the inner peripheral portion 15a of the inward flange 15 is approximately constant over the entire inner peripheral portion 15a. The thickness T2 of the outer peripheral portion 15b of the inward flange 15 is larger than that of the inner peripheral portion 15a of the inward flange 15.

[0017] The inward flange 15 has a standing surface 15c on a surface facing the outward flange 13. The standing surface 15c is located at the boundary between the inner peripheral portion 15a and the outer peripheral portion 15b, and extends in the axial direction. The standing surface 15c forms a step between the inner peripheral portion 15a and the outer peripheral portion 15b, and the thickness of the inward flange 15 changes discontinuously between the inner peripheral portion 15a and the outer peripheral portion 15b. The standing surface 15c extends along the outer peripheral surface 13e of the outward flange 13 of the differential case 12. Although not particularly limited, the dimension of the standing surface 15c in the axial direction (i.e., the height of the step) is smaller than the dimension of the outward flange 13 of the differential case 12 in the axial direction (i.e., the thickness of the outward flange 13).

[0018] As described above, in the differential gear device 10 of this embodiment, the inward flange 15 of the ring gear 14 is offset to one side in the axial direction on the ring gear 14. That is, on the inner peripheral surface 14a of the ring gear 14, the inward flange 15 is disposed not in the center position in the axial direction but toward one side. With this configuration, the position where the inward flange 15 supports the ring gear 14 is biased toward one side in the axial direction with respect to the meshing loads (thrust load Fa and radial load Fb shown in FIG. 3) acting on the ring gear 14. Therefore, when the meshing loads Fa and Fb act on the ring gear 14, the ring gear 14 is likely to be displaced (tooth inclination) and deformed (tooth deflection) toward the radial inside on the other axial side away from the inward flange 15 (see arrow D shown in FIG. 3).

[0019] In view of the above, in this embodiment, outer peripheral portion 15b of inward flange 15 provided on ring gear 14, i.e., the portion located at the base of inward flange 15, is formed thicker than inner peripheral portion 15a. With this configuration, even if the position of inward flange 15 is offset in the axial direction, it is possible to prevent or suppress displacement or deformation (see arrow D in FIG. 3) on the other axial side of ring gear 14 due to loads Fa, Fb acting on ring gear 14 during meshing.

[0020] In particular, in this embodiment, because the ring gear 14 is a helical gear, a thrust load Fa parallel to the axial direction and a radial load Fb parallel to the radial direction act on the ring gear 14 when the ring gear 14 meshes. The two loads Fa and Fb make the ring gear 14 susceptible to large radial inward displacement and deformation. By employing the present technology for such a configuration, it is possible to better prevent or suppress displacement and deformation of the ring gear 14 on the other axial side. [Explanation of symbols]

[0021] 10: differential gear device, 12: differential case, 13: outward flange, 14: ring gear, 15: inward flange, 15a: inner peripheral portion, 15b: outer peripheral portion, 16: bolt

Claims

[Claim 1] A differential case and A ring gear fixed to the differential case; Equipped with An outward flange protruding radially outward toward the ring gear is provided on the outer circumferential surface of the differential case, An inward flange protruding radially inward toward the differential case is provided on the inner peripheral surface of the ring gear and offset to one side in the axial direction, the outward flange and the inward flange face each other in the axial direction and are fastened to each other by a plurality of bolts, a thickness of the inward flange is greater at an outer circumferential portion located radially outward from the inner circumferential portion facing the outward flange than at an inner circumferential portion facing the outward flange; Differential gearing.

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