Differential gear
The differential gear design with a spring having differing end diameters and concentric surface contacts addresses the issue of radial load resistance and seizure resistance, ensuring effective load support and reduced friction.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2024-12-11
- Publication Date
- 2026-06-23
AI Technical Summary
Existing differential gears cannot effectively withstand radial loads while maintaining seizure resistance, as the contact between the side gear and differential case is prone to surface contact, which decreases seizure resistance when surface pressure and sliding speed are high.
A differential gear design incorporating a spring with a cylindrical portion centered on the axis, where the diameters of the ends differ, and the inner and outer circumferential surfaces contact on concentric circles, allowing for non-surface contact and supporting radial loads.
The differential gear can withstand radial loads while suppressing a decrease in seizure resistance by ensuring that the contact areas between the spring and other components are not circumferential, maintaining effective lubrication and reducing friction.
Smart Images
Figure 2026102388000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a differential gear including a side gear that rotates about an axis, a differential case that houses the side gear, a drive shaft connected to the side gear, and a spring provided between the side gear and the differential case or between the drive shaft and the differential case.
Background Art
[0002] A differential gear including a side gear that rotates about an axis, a differential case that houses the side gear, and a spring provided between the side gear and the differential case is known. For example, the one described in Patent Document 1 is such a differential gear. In the differential gear described in Patent Document 1, a load receiving portion composed of a washer and a disc spring is provided between the back surface of the bevel gear portion of the side gear facing each other in the axial direction and the inner wall surface of the differential case. The load receiving portion is provided with ribs and lubricating oil grooves for supplying lubricating oil.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] The load receiving portion in the differential gear described in Patent Document 1 can receive an axial load (=axial load), but cannot receive a radial load (=radial load). In order to receive a radial load, for example, it is conceivable to separately provide a tolerance ring between the shaft portion of the side gear and the inner wall surface of the differential case. Since the contact between the shaft portion of the side gear and the inner wall surface of the differential case and the tolerance ring is surface contact, there is a risk that the seizure resistance will decrease when the surface pressure and sliding speed of the contact surface are high.
[0005] The present invention was made against the above circumstances, and its objective is to provide a differential gear that can withstand radial loads between the side gear and the differential case, or between the drive shaft and the differential case, while suppressing a decrease in seizure resistance. [Means for solving the problem]
[0006] The gist of the present invention is a differential gear comprising: a side gear that rotates about an axis; a differential case housing the side gear; a drive shaft connected to the side gear; and a spring provided between the side gear and the differential case or between the drive shaft and the differential case, wherein (a) the spring has a cylindrical portion centered on the axis; (b) in the axial direction, the diameters of one end and the other end of the cylindrical portion are different; (c) the inner circumferential surface of the cylindrical portion contacts the outer circumferential surface of at least one of the side gear and the drive shaft on a first circumference centered on the axis; and (d) the outer circumferential surface of the cylindrical portion contacts the inner wall surface of the differential case on a second circumference centered on the axis. [Effects of the Invention]
[0007] According to the differential gear of the present invention, (a) the spring has a cylindrical portion centered on the axis, (b) the diameters of one end and the other end of the cylindrical portion are different in the axial direction, (c) the inner circumferential surface of the cylindrical portion contacts the outer circumferential surface of at least one of the side gear and the drive shaft on a first circumference centered on the axis, and (d) the outer circumferential surface of the cylindrical portion contacts the inner wall surface of the differential case on a second circumference centered on the axis. A spring having such configurations (a) to (d) can withstand a radial load between the outer circumferential surface of at least one of the side gear and the drive shaft and the inner wall surface of the differential case in a differential gear. Furthermore, with the configurations of (c) to (d), the contact areas where the cylindrical portion of the spring slides against the outer circumferential surface of at least one of the side gear and drive shaft, and the contact areas where the cylindrical portion of the spring slides against the inner wall surface of the differential case, are not circumferential contacts, i.e., surface contacts. As a result, the differential gear is able to withstand radial loads between at least one of the side gear and drive shaft and the inner wall surface of the differential case by the spring, while suppressing a decrease in seizure resistance. [Brief explanation of the drawing]
[0008] [Figure 1] This is a cross-sectional view of the differential gear according to Example 1, cut in the axial direction. [Figure 2] This is a cross-sectional view of the spring shown in Figure 1, cut in the axial direction. [Figure 3] This is a cross-sectional view of the spring of the differential gear according to Example 2, cut in the axial direction. [Figure 4] This is a cross-sectional view of the spring of the differential gear according to Example 3, cut in the axial direction. [Figure 5] This is a cross-sectional view of the spring of the differential gear according to Example 4, cut in the axial direction. [Figure 6] This is a cross-sectional view of the spring of the differential gear according to Example 5, cut in the axial direction. [Figure 7]Figure 6 is a cross-sectional view of the spring cut radially. [Figure 8] This is a cross-sectional view of the spring of the differential gear according to Example 6, cut in the axial direction. [Modes for carrying out the invention]
[0009] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. In each embodiment, the drawings have been simplified or modified as appropriate, and the dimensional ratios and shapes of each part are not necessarily depicted accurately. In this specification, "direction parallel to the axis CL," "radial direction centered on the axis CL," and "circumferential direction centered on the axis CL" will be simply referred to as "axis CL direction," "radial direction," and "circumferential direction," respectively. [Examples]
[0010] Figure 1 is a cross-sectional view of the differential gear 10 according to Embodiment 1, cut in the direction of the axis CL. Figure 2 is a cross-sectional view of the spring 80 shown in Figure 1, cut in the direction of the axis CL. Figures 1 and 2 illustrate the case where the rotational centerlines of the pair of side gears 30 (hereinafter simply referred to as "side gears 30") and the differential case 40 coincide along the axis CL. That is, the case where the side gears 30 and the differential case 40 are not relatively misaligned in either the axial direction CL or the radial direction. In Figure 2 (and similarly in Figures 3 to 6 and 8 described later), the differential case 40 and the side gears 30 after the assembly of the differential gear 10 are shown by dashed lines.
[0011] The differential gear 10 comprises a pair of differential pinions 20 (hereinafter simply referred to as "differential pinions 20"), a differential pinion shaft 22, a side gear 30, a differential case 40, a differential ring gear 42, and a spring 80 as components, with all components except the spring 80 being well-known. The differential case 40 is supported by a non-rotating member, a case 50 (for example, a transaxle case), via a bearing 52, and is rotatable about an axis CL. The differential case 40 houses the differential pinions 20, the differential pinion shaft 22, the side gear 30, and the spring 80. Since both ends of the cylindrical differential pinion shaft 22 are held by the differential case 40, the differential pinion shaft 22 rotates integrally with the differential case 40 about an axis CL. Each of the differential pinions 20 is a bevel gear, rotatably fitted onto the outer circumference of the differential pinion shaft 22. The side gears 30 mesh with each of the differential pinions 20 and are rotatable about axis CL; they are also bevel gears. The differential ring gear 42 is fixed to the differential case 40, for example, by bolts 44. The rotational centers of both the side gears 30 and the differential case 40 are axis CL. The differential gear 10 receives power input from the differential ring gear 42 and transmits equal driving torque to a pair of drive shafts 60, described later, while allowing an appropriate difference in rotational speed.
[0012] The side gear 30 has a cylindrical shaft portion 32 centered on the axis CL, and a bevel tooth portion 34, which is a bevel gear provided on one end 32a of the shaft portion 32 in the direction of the axis CL. In the direction of the axis CL, the inner side of the differential gear 10, that is, the mating side of the pair of side gears 30, is the teeth portion of the bevel tooth portion 34, and the opposite side is the back surface 34b of the bevel tooth portion 34. For example, the shaft portion 32 and the bevel tooth portion 34 are integrally constructed. "One end 32a of the shaft portion 32" refers to the other side of the pair of side gears 30 in the direction of the axis CL (i.e., the inner side of the differential gear 10). The other end 32b of the shaft portion 32 in the direction of the axis CL is the tip of the shaft portion 32. The differential pinion 20 and the side gear 30 mesh with each other, with the bevel gear of the differential pinion 20 meshing with the bevel gear of the side gear 30. A fitting portion is provided on the inner circumferential surface 32i of the shaft portion 32 of the side gear 30. A pair of drive shafts 60, each connected to a pair of left and right wheels (not shown), are inserted into the cylindrical portion 40c of the differential case 40, and the pair of drive shafts 60 are fitted to the fitting portions provided on the inner circumferential surface 32i of the shaft portion 32 so as not to rotate relative to each other.
[0013] The spring 80 is formed, for example, from a plate-like body of steel with a constant thickness. The spring 80 is formed, for example, by press-forming the plate-like body. The thickness of the plate-like body is determined experimentally or by design so that the cylindrical portion 82 and the outer disc-shaped portion 86, described later, function as elastic bodies. The spring 80 has a cylindrical portion 82, an inner disc-shaped portion 84, and an outer disc-shaped portion 86.
[0014] The cylindrical portion 82 is cylindrical with an axis CL as its center. One end 82a of the cylindrical portion 82 in the direction of the axis CL is the end of the side gear 30 on the bevel tooth portion 34 side. This end 82a corresponds to the "end located on the inside side of the differential gear" in this invention. The other end 82b of the cylindrical portion 82 in the direction of the axis CL is the end of the side gear 30 opposite to the bevel tooth portion 34. This other end 82b corresponds to the "end located on the outside side of the differential gear" in this invention. The outer peripheral disc portion 86 is disc-shaped extending outward, and the outer edge on the inner side of the outer peripheral disc portion 86 is connected to the one end 82a of the cylindrical portion 82. The inner peripheral disc portion 84 is disc-shaped extending inward. The outer edge on the outer side of the inner peripheral disc portion 84 is connected to the other end 82b. An opening 84o is provided at the outer edge of the inner circumference of the inner circumferential disc-shaped portion 84. The spring 80 is provided between the side gear 30 and the differential case 40.
[0015] In the direction of the axis CL, the diameters of one end 82a and the other end 82b are different. Specifically, the diameter of one end 82a is larger than the diameter of the other end 82b. In this embodiment, in a cross-sectional view cut in the direction of the axis CL, the direction from the other end 82b to the one end 82a of the cylindrical portion 82 is inclined at an angle θ1 [deg] (>0) with respect to the axis CL. The inner circumferential surfaces 82i of the cylindrical portion 82 and the outer circumferential surface 32o of the shaft portion 32, which face each other in the radial direction, are in contact on a circle centered on the axis CL that includes position P1a. "On the circle centered on the axis CL that includes position P1a" corresponds to "on the first circle centered on the axis CL" in the present invention. The outer circumferential surface 32o in this embodiment corresponds to "at least one outer circumferential surface of the side gear and the drive shaft" in the present invention. The outer circumferential surfaces 82o of the cylindrical portion 82 and the inner wall surface 40i of the differential case 40, which are radially opposite to each other, are in contact on a circumference centered on the axis CL including position P2a. "On a circumference centered on the axis CL including position P2a" corresponds to "on a second circumference centered on the axis CL" in the present invention. The cylindrical portion 82 functions as an elastic member that receives a radial load between the outer circumferential surface 32o and the inner wall surface 40i, between the contact portion on the circumference centered on the axis CL including position P1a and the contact portion on the circumference centered on the axis CL including position P2a.
[0016] The inner peripheral portion 86i and the outer peripheral portion 86o of the outer peripheral disk portion 86 are different in position in the direction of the axis CL. Specifically, in the direction of the axis CL, the outer peripheral portion 86o is spaced apart from the bevel gear portion 34 of the side gear 30 more than the inner peripheral portion 86i. In the present embodiment, in the cross-sectional view taken in the direction of the axis CL, the direction from the inner peripheral portion 86i to the outer peripheral portion 86o in the outer peripheral disk portion 86 is inclined by an angle θ2 [deg] (>0) toward the other end portion 82b side of the cylindrical portion 82 with respect to the direction perpendicular to the axis CL. The inner peripheral portion 86i and the rear surface 34b facing each other in the direction of the axis CL are in contact with each other on the circumference centered on the axis CL including the position P3a. "On the circumference centered on the axis CL including the position P3a" corresponds to "on the third circumference centered on the axis CL" in the present invention. The rear surface 34b of the present embodiment corresponds to "one of the side gear and the inner wall surface" in the present invention. The outer peripheral portion 86o and the inner wall surface 40i facing each other in the direction of the axis CL are in contact with each other on the circumference centered on the axis CL including the position P4a. "On the circumference centered on the axis CL including the position P4a" corresponds to "on the fourth circumference centered on the axis CL" in the present invention. The inner wall surface 40i of the present embodiment corresponds to "the other of the side gear and the inner wall surface" in the present invention. The outer peripheral disk portion 86 functions as an elastic member that receives the load in the direction of the axis CL between the contact portion on the circumference centered on the axis CL including the position P3a and the contact portion on the circumference centered on the axis CL including the position P4a between the rear surface 34b and the inner wall surface 40i.
[0017] Based on the magnitude of the radial load received by the spring 80, the magnitude of the load in the axial direction of the axis CL, and the magnitude of the tolerance (= relative positional deviation) between the axis CL and the rotation center line of the spring 80, the angles θ1 and θ2 in the spring 80 are set. For example, by setting the angle θ1 < angle θ2, the differential limiting effect in the differential gear 10 increases. The "differential limiting effect" is an effect that limits the rotational speed difference between the pair of drive shafts 60 in the differential gear 10 from becoming too large. When the side gear 30 and the differential case 40 are relatively displaced radially or axially in the direction of the axis CL, the positions P1a, P2a, P3a, and P4a change accordingly.
[0018] As described above, the inner peripheral disk-shaped portion 84 is disk-shaped and extends to the inner peripheral side. The diameter of the opening 84o of the inner peripheral disk-shaped portion 84 is larger than the inner diameter of the shaft portion 32 of the side gear 30 and smaller than the outer diameter of the shaft portion 32. For example, the inner peripheral disk-shaped portion 84 is adapted to contact the other end portion 32b of the shaft portion 32 in the side gear 30 on the circumference centered on the axis CL including the position P0. The position P0 is preset so that the cylindrical portion 82 and the outer peripheral disk-shaped portion 86 can each function as an elastic member.
[0019] For example, when assembling the differential gear 10, the spring 80 is assembled from the other end portion 32b side (= opposite side to the bevel gear portion 34) to the one end portion 32a side (= bevel gear portion 34 side) of the shaft portion 32 of the side gear 30. In this case, the inner peripheral disk-shaped portion 84 of the spring 80 contacts the other end portion 32b in the side gear 30 on the circumference centered on the axis CL including the position P0. When the inner peripheral disk-shaped portion 84 contacts the other end portion 32b, the further assembly of the spring 80 is stopped. That is, in the axial direction of the axis CL, the relative position between the spring 80 and the tip portion of the shaft portion 32 in the side gear 30 is determined. Thereby, in the axial direction of the axis CL, the relative position between the spring 80 and the side gear 30 is suppressed from being displaced more than necessary.
[0020] According to this embodiment, (a) the spring 80 has a cylindrical portion 82 centered on the axis CL, and a disc-shaped outer peripheral disc portion 86 connected to one end 82a of the cylindrical portion 82 in the direction of the axis CL and extending outward, (b) in the direction of the axis CL, the diameters of one end 82a and the other end 82b of the cylindrical portion 82 are different, (c) the inner circumferential surface 82i of the cylindrical portion 82 contacts the outer peripheral surface 32o on a circle centered on the axis CL including position P1a, and (d) circle The outer circumferential surface 82o of the cylindrical portion 82 is in contact with the inner wall surface 40i on a circumference centered on the axis CL including position P2a, (e) the inner circumferential portion 86i and the outer circumferential portion 86o of the outer disc-shaped portion 86 are at different positions in the direction of the axis CL, (f) the inner circumferential portion 86i is in contact with the back surface 34b on a circumference centered on the axis CL including position P3a, and (g) the outer circumferential portion 86o is in contact with the inner wall surface 40i on a circumference centered on the axis CL including position P4a. A spring 80 having such configurations (a) to (d) can withstand a radial load between the outer circumferential surface 32o and the inner wall surface 40i of the shaft portion 32 of the side gear 30 in the differential gear 10. Furthermore, with the configurations of (c) to (d), the contact portion where the cylindrical portion 82 of the spring 80 slides against the shaft portion 32, and the contact portion where the cylindrical portion 82 of the spring 80 slides against the inner wall surface 40i, are both in a manner where they contact on the circumference, i.e., not surface contact. A spring 80 having such configurations of (e) to (g) can withstand a load in the axial direction CL between the back surface 34b of the side gear 30 and the inner wall surface 40i in the differential gear 10. Furthermore, with the configurations of (f) to (g), the contact portion where the outer disc-shaped portion 86 of the spring 80 slides against the back surface 34b of the side gear 30, and the contact portion where the outer disc-shaped portion 86 of the spring 80 slides against the inner wall surface 40i, are both in a manner where they contact on the circumference, i.e., not surface contact. In other words, the contact areas where the cylindrical portion 82 of the spring 80 slides against the shaft portion 32 of the side gear 30, the contact areas where the cylindrical portion 82 of the spring 80 slides against the inner wall surface 40i, the contact areas where the outer disc-shaped portion 86 of the spring 80 slides against the back surface 34b of the side gear 30, and the contact areas where the outer disc-shaped portion 86 of the spring 80 slides against the inner wall surface 40i are all not surface contacts.Therefore, the differential gear 10 is able to withstand the radial and axial CL loads between the side gear 30 and the inner wall surface 40i, while suppressing a decrease in seizure resistance, and the spring 80 provides support.
[0021] According to this embodiment, (a) the side gear 30 has a cylindrical shaft portion 32 centered on the axis CL and an umbrella tooth portion 34 provided on one end 32a side of the shaft portion 32 in the direction of the axis CL, (b) the inner circumferential surface 82i of the cylindrical portion 82 is in contact with the outer circumferential surface 32o of the shaft portion 32, (c) the outer circumferential surface 82o of the cylindrical portion 82 is in contact with the inner wall surface 40i, and (d) the spring 80 is connected to one end 82a of the cylindrical portion 82 in the direction of the axis CL and has a disc-shaped inner circumferential disc portion 84 extending inward. When the spring 80 has an inner circumferential disc portion 84, it is less likely to shift relative to the side gear 30 and the inner wall surface 40i in the direction of the axis CL compared to when it does not have an inner circumferential disc portion 84. For example, when assembling the differential gear 10, if the spring 80 is installed from the other end 32b (opposite side to the bevel tooth portion 34) of the shaft portion 32 of the side gear 30 toward the one end 32a (towards the bevel tooth portion 34), the positioning of the spring 80 becomes easier. [Examples]
[0022] Figure 3 is a cross-sectional view of the spring 180 of the differential gear 110 according to Embodiment 2, cut in the direction of the axis CL. The differential gear 110 has substantially the same configuration as the differential gear 10 according to Embodiment 1 described above, but differs in that the spring 80 is replaced with a spring 180. In the cross-sectional view cut in the direction of the axis CL, the spring 80 was inclined at an angle θ2 with respect to the direction perpendicular to the axis CL, with respect to the other end 82b of the cylindrical portion 82, in the direction from the inner circumference 86i to the outer circumference 86o of the outer disc-shaped portion 86. In contrast, in the cross-sectional view cut in the direction of the axis CL, the spring 180 differs in that the direction from the inner circumference 86i to the outer circumference 86o of the outer disc-shaped portion 86 is inclined at an angle θ2 with respect to the direction perpendicular to the axis CL, with respect to the one end 82a of the cylindrical portion 82. Therefore, in this embodiment, we will focus on explaining the parts that differ from those in Embodiment 1, and parts that are substantially common in function with those in Embodiment 1 will be denoted by the same reference numerals, and their explanations will be omitted as appropriate.
[0023] The inner circumference 86i and outer circumference 86o of the outer disc-shaped portion 86 are located at different positions in the direction of the axis CL. Specifically, in the direction of the axis CL, the outer circumference 86o is closer to the bevel teeth 34 of the side gear 30 than the inner circumference 86i. In this embodiment, in a cross-sectional view cut in the direction of the axis CL, the direction from the inner circumference 86i to the outer circumference 86o is inclined toward one end 82a of the cylindrical portion 82 by an angle θ3 [deg] (>0) with respect to the direction perpendicular to the axis CL. The inner circumference 86i and the inner wall surface 40i, which face each other in the direction of the axis CL, are in contact on a circle centered on the axis CL that includes position P3b. "On the circle centered on the axis CL that includes position P3b" corresponds to "on the third circle centered on the axis CL" in the present invention. In this embodiment, the inner wall surface 40i corresponds to "one of the side gear and the inner wall surface" in the present invention. The outer peripheral portion 86o and the back surface 34b, which face each other in the axial direction CL, are in contact on a circle centered on the axis CL including position P4b. "On the circle centered on the axis CL including position P4b" corresponds to "on the fourth circle centered on the axis CL" in the present invention. In this embodiment, the back surface 34b corresponds to "the other of the side gear and the inner wall surface" in the present invention. The outer peripheral disc-shaped portion 86 functions as an elastic member that receives a load in the axial direction CL between the back surface 34b and the inner wall surface 40i, between a contact portion on the circle centered on the axis CL including position P3b and a contact portion on the circle centered on the axis CL including position P4b.
[0024] According to this embodiment, since it has the same configuration as the aforementioned Embodiment 1, it achieves the same effects as Embodiment 1 based on that configuration. [Examples]
[0025] Figure 4 is a cross-sectional view of the spring 280 of the differential gear 210 according to Embodiment 3, cut in the direction of the axis CL. The differential gear 210 has substantially the same configuration as the differential gear 10 according to Embodiment 1 described above, but differs in that the spring 80 is replaced with a spring 280. The spring 280 has substantially the same configuration as the spring 80, but differs in that it does not have an outer disc-shaped portion 86. Therefore, in this embodiment, we will mainly explain the parts that differ from Embodiment 1, and parts that are substantially common in function with Embodiment 1 will be given the same reference numerals and their explanations will be omitted as appropriate.
[0026] The spring 280 has a cylindrical portion 82 and an inner circumferential disc portion 84, but does not have an outer circumferential disc portion 86. Because the spring 280 has a cylindrical portion 82, it functions as an elastic member that receives a radial load, but because it does not have an outer circumferential disc portion 86, it does not function as an elastic member that receives a load in the axial direction CL.
[0027] According to this embodiment, since it has the same configuration as the aforementioned Embodiment 1, it achieves the same effects as Embodiment 1 based on that configuration. [Examples]
[0028] Figure 5 is a cross-sectional view of the spring 380 of the differential gear 310 according to Embodiment 4, cut in the direction of the axis CL. The differential gear 310 has substantially the same configuration as the differential gear 210 according to Embodiment 3 described above, but differs in that the spring 280 is replaced with a spring 380. The spring 380 has substantially the same configuration as the spring 280, but differs in that it does not have an inner circumferential disc-shaped portion 84. Therefore, in this embodiment, we will mainly describe the parts that differ from Embodiment 3, and parts that are substantially common in function with Embodiment 3 will be given the same reference numerals and their descriptions will be omitted as appropriate.
[0029] The spring 380 has a cylindrical portion 82 and does not have an inner circumferential disc portion 84 or an outer circumferential disc portion 86. Because the spring 380 has a cylindrical portion 82, it functions as an elastic member that receives a radial load, but because it does not have an outer circumferential disc portion 86, it does not function as an elastic member that receives a load in the axial direction CL.
[0030] According to this embodiment, since it has the same configuration as the aforementioned Embodiment 3, it achieves the same effects as Embodiment 3 based on that configuration. [Examples]
[0031] Figure 6 is a cross-sectional view of the spring 480 of the differential gear 410 according to Embodiment 5, cut in the direction of the axis CL. Figure 6 is an enlarged view of a part of the spring 480. Figure 7 is a cross-sectional view of the spring 480 shown in Figure 6, cut radially, and is a cross-sectional view taken along the cutting line VII-VII shown in Figure 6. Figure 6 is a cross-sectional view taken along the cutting line VI-VI shown in Figure 7. The differential gear 410 has substantially the same configuration as the differential gear 10 according to Embodiment 1 described above, but differs in that the spring 80 is replaced with a spring 480. The spring 480 has substantially the same configuration as the spring 80, but differs in that it has multiple protrusions 482t1, 482t2, 486t1, 486t2. Therefore, in this embodiment, the explanation will focus on the parts that differ from Embodiment 1, and parts that are substantially common in function with Embodiment 1 will be given the same reference numerals and their explanations will be omitted as appropriate.
[0032] The inner circumferential surface 82i of the cylindrical portion 82 is provided with a plurality of projections 482t1 that protrude inward. Each of the plurality of projections 482t1 protrudes radially inward and extends in the direction of the axis CL. The plurality of projections 482t1 intermittently make line contact or point contact with the outer circumferential surface 32o on the circumference of a circle centered on the axis CL including position P1c. "On the circumference of a circle centered on the axis CL including position P1c" corresponds to "on the first circumference centered on the axis CL" in the present invention. For example, in the circumferential direction, the plurality of projections 482t1 are provided at equal angular intervals (12 degrees in this embodiment) on the circumference of a circle centered on the axis CL including position P1c. The plurality of projections 482t1 correspond to "a plurality of projections provided on the inner circumferential surface of the cylindrical portion" in the present invention.
[0033] The outer circumferential surface 82o of the cylindrical portion 82 is provided with a plurality of protrusions 482t2 that project outward. Each of the plurality of protrusions 482t2 projects radially outward and extends in the direction of the axis CL. The plurality of protrusions 482t2 intermittently make line contact or point contact with the inner wall surface 40i on the circumference of a circle centered on the axis CL including position P2c. "On the circumference of a circle centered on the axis CL including position P2c" corresponds to "on the second circumference centered on the axis CL" in the present invention. For example, in the circumferential direction, the plurality of protrusions 482t2 are provided at equal angular intervals (12 degrees in this embodiment) on the circumference of a circle centered on the axis CL including position P2c. The plurality of protrusions 482t2 correspond to "a plurality of protrusions provided on the outer circumferential surface of the cylindrical portion" in the present invention.
[0034] The inner circumference 86i of the outer disc-shaped portion 86 is provided with a plurality of protrusions 486t1 that project toward the rear surface 34b in the direction of the axis CL. Each of the plurality of protrusions 486t1 projects toward the rear surface 34b in the direction of the axis CL and extends radially. The plurality of protrusions 486t1 intermittently make line contact or point contact with the rear surface 34b on the circumference centered on the axis CL including position P3c. "On the circumference centered on the axis CL including position P3c" corresponds to "on the third circumference centered on the axis CL" in the present invention. For example, in the circumferential direction, the plurality of protrusions 486t1 are provided at equal angular intervals on the circumference centered on the axis CL including position P3c. In this embodiment, the rear surface 34b corresponds to "one of the side gear and the inner wall surface" in the present invention. The plurality of protrusions 486t1 correspond to "a plurality of protrusions provided on the inner circumference of the outer disc-shaped portion" in the present invention.
[0035] The outer circumference 86o of the outer disc-shaped portion 86 is provided with a plurality of protrusions 486t2 that project toward the inner wall surface 40i in the direction of the axis CL. Each of the plurality of protrusions 486t2 projects toward the inner wall surface 40i in the direction of the axis CL and extends radially. The plurality of protrusions 486t2 intermittently make line contact or point contact with the inner wall surface 40i on the circumference of a circle centered on the axis CL including position P4c. "On the circumference of a circle centered on the axis CL including position P4c" corresponds to "on the fourth circumference centered on the axis CL" in the present invention. For example, in the circumferential direction, the plurality of protrusions 486t2 are provided at equal angular intervals on the circumference of a circle centered on the axis CL including position P4c. Note that the inner wall surface 40i in this embodiment corresponds to "the other side of the side gear and the inner wall surface" in the present invention. The plurality of protrusions 486t2 correspond to "a plurality of protrusions provided on the outer circumference of the outer disc-shaped portion" in the present invention.
[0036] According to this embodiment, since it has the same configuration as the aforementioned Embodiment 1, it achieves the same effects as Embodiment 1 based on that configuration.
[0037] According to this embodiment, (a) a plurality of protrusions 482t1 are provided on the inner circumferential surface 82i of the cylindrical portion 82, (b) the plurality of protrusions 482t1 intermittently make line contact or point contact with the outer circumferential surface 32o, (c) a plurality of protrusions 482t2 are provided on the outer circumferential surface 82o of the cylindrical portion 82, (d) the plurality of protrusions 482t2 intermittently make line contact or point contact with the inner wall surface 40i, (e) a plurality of protrusions 486t1 are provided on the inner circumferential portion 86i, (f) the plurality of protrusions 486t1 intermittently make line contact or point contact with the back surface 34b, (g) a plurality of protrusions 486t2 are provided on the outer circumferential portion 86o, and (h) the plurality of protrusions 486t2 intermittently make line contact or point contact with the inner wall surface 40i. In configurations (a) to (d), the contact portion where the cylindrical portion 82 of the spring 480 slides against the shaft portion 32, and the contact portion where the cylindrical portion 82 of the spring 480 slides against the inner wall surface 40i, are both in intermittent contact on the circumference. In this intermittent contact configuration, compared to configurations where there is no such contact, the decrease in seizure resistance between the cylindrical portion 82 of the spring 480 and the shaft portion 32 of the side gear 30 is suppressed, as is the decrease in seizure resistance between the cylindrical portion 82 of the spring 480 and the inner wall surface 40i. In configurations (e) to (h), the contact portion where the outer disc portion 86 of the spring 480 slides against the back surface 34b of the side gear 30, and the contact portion where the outer disc portion 86 of the spring 480 slides against the inner wall surface 40i, are both in intermittent contact on the circumference. In this intermittent contact configuration, compared to configurations without such intermittent contact, the reduction in seizure resistance between the outer disc-shaped portion 86 of the spring 480 and the back surface 34b of the side gear 30 is suppressed, as is the reduction in seizure resistance between the outer disc-shaped portion 86 of the spring 480 and the inner wall surface 40i. Furthermore, when multiple protrusions 482t1, 482t2, 486t1, and 486t2 are provided, lubricating oil with a cooling function is more easily retained on the surface of the cylindrical portion 82 and the outer disc-shaped portion 86 compared to configurations without such protrusions, thus improving seizure resistance. In this way, the differential gear 410 has its seizure resistance suppressed while the radial and axial CL loads between the side gear 30 and the inner wall surface 40i are supported by the spring 480. [Examples]
[0038] Figure 8 is a cross-sectional view of the spring 580 of the differential gear 510 according to Embodiment 6, cut in the direction of the axis CL. The differential gear 510 has substantially the same configuration as the differential gear 10 according to Embodiment 1 described above, but differs in that the spring 80 is replaced with a spring 580. The spring 580 has substantially the same configuration as the spring 80, but differs in that it does not have an inner circumferential disc-shaped portion 84, and the spring 580 is provided between the drive shaft 60 and the differential case 40. Therefore, in this embodiment, the explanation will focus on the parts that differ from Embodiment 1, and parts that are substantially common in function with Embodiment 1 will be given the same reference numerals and their explanations will be omitted as appropriate.
[0039] The spring 580 has a cylindrical portion 82 and an outer disc-shaped portion 86. In a cross-sectional view taken in the direction of the axis CL, the direction from the other end 82b to the one end 82a of the cylindrical portion 82 of the spring 580 is inclined with respect to the axis CL. The inner circumferential surface 82i of the cylindrical portion 82 and the outer circumferential surface 60o of the drive shaft 60, which are facing each other in the radial direction, are in contact on a circle centered on the axis CL that includes position P1d. "On a circle centered on the axis CL that includes position P1d" corresponds to "on a first circle centered on the axis CL" in the present invention. In this embodiment, the outer circumferential surface 60o corresponds to "at least one outer circumferential surface of the side gear and the drive shaft" in the present invention. The outer circumferential surface 82o and the inner wall surface 40i of the cylindrical portion 82, which are facing each other in the radial direction, are in contact on a circle centered on the axis CL that includes position P2d. "On the circumference centered on axis CL including position P2d" corresponds to "on the second circumference centered on axis CL" in the present invention. The cylindrical portion 82 of the spring 580 functions as an elastic member that receives a radial load between the outer surface 60o and the inner wall surface 40i.
[0040] The inner circumference 86i and outer circumference 86o of the outer disc-shaped portion 86 of the spring 580 are located at different positions in the direction of the axis CL. In a cross-sectional view taken in the direction of the axis CL, the direction from the inner circumference 86i to the outer circumference 86o is inclined toward the other end 82b of the cylindrical portion 82 with respect to the direction perpendicular to the axis CL. The inner circumference 86i and the other end 32b of the shaft portion 32, which face each other in the direction of the axis CL, are in contact on a circumference centered on the axis CL including position P3d. "On a circumference centered on the axis CL including position P3d" corresponds to "on a third circumference centered on the axis CL" in the present invention. In this embodiment, the other end 32b corresponds to "one of the side gear and the inner wall surface" in the present invention. The outer circumference 86o and the inner wall surface 40i, which face each other in the direction of the axis CL, are in contact on a circumference centered on the axis CL including position P4d. "On the circumference centered on axis CL including position P4d" corresponds to "on the fourth circumference centered on axis CL" in the present invention. In this embodiment, the inner wall surface 40i corresponds to "the other side of the side gear and the inner wall surface" in the present invention. The outer disc-shaped portion 86 of the spring 580 functions as an elastic member that receives a load in the direction of axis CL between the other end 32b of the shaft portion 32 and the inner wall surface 40i.
[0041] According to this embodiment, (a) the spring 580 has a cylindrical portion 82 that is cylindrical in shape with respect to the axis CL, and a disc-shaped outer peripheral disc portion 86 that is connected to one end 82a of the cylindrical portion 82 in the direction of the axis CL and extends outward, (b) in the direction of the axis CL, the diameters of one end 82a and the other end 82b of the cylindrical portion 82 are different, (c) the inner circumferential surface 82i of the cylindrical portion 82 is in contact with the outer peripheral surface 60o on a circle centered on the axis CL including position P1d, and (d) cylindrical The outer circumferential surface 82o of part 82 contacts the inner wall surface 40i on a circumference centered on the axis CL including position P2d, (e) the inner circumferential portion 86i and the outer circumferential portion 86o of the outer circumferential disc-shaped part 86 are at different positions in the direction of the axis CL, (f) the inner circumferential portion 86i contacts the other end 32b of the shaft portion 32 on a circumference centered on the axis CL including position P3d, and (g) the outer circumferential portion 86o contacts the inner wall surface 40i on a circumference centered on the axis CL including position P4d. A spring 580 having such configurations (b) to (d) can withstand radial loads between the outer circumferential surface 60o and the inner wall surface 40i of the drive shaft 60 in the differential gear 510. Furthermore, with the configurations of (c) to (d), the contact portion where the cylindrical portion 82 of the spring 580 slides against the drive shaft 60, and the contact portion where the cylindrical portion 82 of the spring 580 slides against the inner wall surface 40i, are both in a manner where they contact on the circumference, i.e., not surface contact. A spring 580 having such configurations of (e) to (g) can withstand a load in the axial direction CL between the other end 32b of the shaft portion 32 of the side gear 30 and the inner wall surface 40i in the differential gear 510. Furthermore, with the configurations of (f) to (g), the contact portion where the outer disc-shaped portion 86 of the spring 580 slides against the shaft portion 32 of the side gear 30, and the contact portion where the outer disc-shaped portion 86 of the spring 580 slides against the inner wall surface 40i, are both in a manner where they contact on the circumference, i.e., not surface contact. In other words, the contact portion where the cylindrical portion 82 of the spring 580 slides against the drive shaft 60, the contact portion where the cylindrical portion 82 of the spring 580 slides against the inner wall surface 40i, the contact portion where the outer disc-shaped portion 86 of the spring 580 slides against the shaft portion 32 of the side gear 30, and the contact portion where the outer disc-shaped portion 86 of the spring 580 slides against the inner wall surface 40i are all not surface contacts.Therefore, the differential gear 510 is able to withstand the loads in the radial direction between the drive shaft 60 and the inner wall surface 40i, and the loads in the axial direction CL between the side gear 30 and the inner wall surface 40i, while suppressing a decrease in seizure resistance, and the loads are supported by the spring 580.
[0042] The above-described examples are embodiments of the present invention, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art, without departing from its spirit.
[0043] In the aforementioned embodiments 1 to 5, the diameter of one end 82a was larger than the diameter of the other end 82b, but the present invention is not limited to this embodiment. For example, the diameter of one end 82a may be smaller than the diameter of the other end 82b. In this embodiment, the inner circumferential surface 82i of the cylindrical portion 82 in the axial direction CL contacts the outer circumferential surface 32o on a circle centered on the axis CL, and the other end 82b of the outer circumferential surface 82o of the cylindrical portion 82 in the axial direction CL contacts the inner wall surface 40i on a circle centered on the axis CL. Similarly, in the aforementioned embodiment 6, the diameter of one end 82a may be smaller than the diameter of the other end 82b.
[0044] In the aforementioned Embodiment 1, in the cross-sectional view cut in the direction of the axis CL, the direction from the inner circumference 86i to the outer circumference 86o of the outer peripheral disc-shaped portion 86 of the spring 80 was inclined toward the other end 82b of the cylindrical portion 82 with respect to the direction perpendicular to the axis CL. In the aforementioned Embodiment 2, the direction from the inner circumference 86i to the outer circumference 86o of the spring 180 was inclined toward the one end 82a of the cylindrical portion 82 with respect to the direction perpendicular to the axis CL. Thus, the present invention is applicable to embodiments in which (a) the inner circumference 86i and the outer circumference 86o of the outer peripheral disc-shaped portion 86 are in different positions in the direction of the axis CL, (b) the inner circumference 86i contacts one of the back surface 34b and the inner wall surface 40i on a circumference centered on the axis CL, and (c) the outer circumference 86o contacts the other of the back surface 34b and the inner wall surface 40i on a circumference centered on the axis CL. Similarly, in the aforementioned embodiment 6, in the cross-sectional view cut in the direction of the axis CL, the direction from the inner circumference 86i to the outer circumference 86o of the spring 580 may be inclined toward one end 82a of the cylindrical portion 82 with respect to the direction perpendicular to the axis CL.
[0045] In the aforementioned Embodiment 5, all of the multiple protrusions 482t1, 482t2, 486t1, and 486t2 were provided, but the present invention is not limited to this embodiment. For example, the present invention is also applicable to an embodiment in which at least one of the multiple protrusions 482t1, 482t2, 486t1, and 486t2 is provided. When one of the multiple protrusions 482t1, 482t2, 486t1, and 486t2 is provided, to that extent, the spring 480 and either the outer circumferential surface 32o, the back surface 34b, or the inner wall surface 40i of the side gear 30 are in intermittent line contact or point contact, and to that extent, the decrease in the seizure resistance of the differential gear 410 is suppressed.
[0046] As in Example 5 for Example 1 described above, the present invention is also applicable to an embodiment in Example 6 described above in which at least one of the multiple protrusions 482t1, 482t2, 486t1, and 486t2 is provided on the cylindrical portion 82 or the outer disc portion 86 of the spring 580. Furthermore, as in Example 3 for Example 2 described above, the spring 580 may not have an outer disc portion 86 in an embodiment in Example 6 described above.
[0047] In the aforementioned embodiments 1 to 5, springs 80, 180, 280, 380, and 480 were provided between the side gear 30 and the differential case 40, and in the aforementioned embodiment 6, spring 580 was provided between the drive shaft 60 and the differential case 40. Thus, the "spring" in the present invention is provided between the side gear 30 and the differential case 40 or between the drive shaft 60 and the differential case 40. [Explanation of symbols]
[0048] 10, 110, 210, 310, 410, 510: Differential gear, 30: Side gear, 32: Shaft portion, 32b: Other end (side gear and one inner wall surface), 32o: Outer surface (side gear and at least one outer surface of the drive shaft), 34: Umbrella tooth portion, 34b: Rear (side gear and one inner wall surface, the other side gear and inner wall surface), 40: Differential case, 40i: Inner wall surface (side gear and the other inner wall surface, the side gear and one inner wall surface), 60: Drive shaft, 60o: Outer surface (side gear and at least one outer surface of the drive shaft), 80, 180, 280, 380, 480, 580: Spring, 82: Cylindrical portion, 82a: One end 82t1: part (one end of the cylindrical part, the end located on the inside side of the differential gear), 82b: other end (the other end of the cylindrical part, the end located on the outside side of the differential gear), 82i: inner surface (inner surface of the cylindrical part), 82o: outer surface (outer surface of the cylindrical part), 84: inner disc-shaped part, 86: outer disc-shaped part, 86i: inner part, 86o: outer part, 482t1: multiple protrusions (multiple protrusions provided on the inner surface of the cylindrical part), 482t2: multiple protrusions (multiple protrusions provided on the outer surface of the cylindrical part), 486t1: multiple protrusions (multiple protrusions provided on the inner part of the outer disc-shaped part), 486t2: multiple protrusions (multiple protrusions provided on the outer part of the outer disc-shaped part), CL: axis
Claims
1. A differential gear comprising: a side gear that rotates about an axis; a differential case housing the side gear; a drive shaft connected to the side gear; and a spring provided between the side gear and the differential case or between the drive shaft and the differential case, The spring has a cylindrical portion centered on the axis, In the axial direction, the diameters of one end and the other end of the cylindrical portion are different. The inner circumferential surface of the cylindrical portion contacts the outer circumferential surface of at least one of the side gear and the drive shaft on a first circumference centered on the axis. The outer circumferential surface of the cylindrical portion is in contact with the inner wall surface of the differential case on a second circumference centered on the axis. A differential gear characterized by the following features.
2. Multiple protrusions are provided on at least one of the inner circumferential surface and the outer circumferential surface of the cylindrical portion. The plurality of protrusions provided on the inner circumferential surface of the cylindrical portion intermittently contact the outer circumferential surface of at least one of the side gear and the drive shaft, or the plurality of protrusions provided on the outer circumferential surface of the cylindrical portion intermittently contact the inner wall surface. The differential gear according to feature 1.
3. The spring is connected to one end of the cylindrical portion in the axial direction and to the other end of the cylindrical portion located on the inside side of the differential gear, and has a disc-shaped outer peripheral disc portion extending outward. The inner circumference and outer circumference of the outer disc-shaped portion are located at different positions in the axial direction. The inner circumference of the outer disc-shaped portion contacts one of the side gears and the inner wall surface, which are opposite to each other in the axial direction, on a third circumference centered on the axis. The outer circumference of the outer disc-shaped portion is in contact with the other side gear and the inner wall surface, which are opposite to each other in the axial direction, on a fourth circumference centered on the axis. The differential gear according to feature 1.
4. Multiple protrusions are provided on at least one of the inner circumference and the outer circumference of the outer disc-shaped portion. The plurality of protrusions provided on the inner circumference of the outer disc-shaped portion intermittently contact one of the side gears and the inner wall surface that are opposite to each other in the axial direction, or the plurality of protrusions provided on the outer circumference of the outer disc-shaped portion intermittently contact the other of the side gears and the inner wall surface that are opposite to each other in the axial direction. The differential gear according to feature 3.
5. The side gear has a cylindrical shaft portion centered on the axis and an umbrella-shaped tooth portion provided on one end of the shaft portion in the axial direction. The inner circumferential surface of the cylindrical portion is in contact with the outer circumferential surface of the shaft portion. The outer circumferential surface of the cylindrical portion is in contact with the inner wall surface of the differential case. The spring is connected to one end of the cylindrical portion in the axial direction and to the other end of the cylindrical portion located on the outside side of the differential gear, and has a disc-shaped inner disc portion extending inward. A differential gear according to any one of claims 1 to 4.