Differential device

Abstract

To provide a differential device that can make a torque bias ratio during left and right turning of a vehicle come close to each other.SOLUTION: A differential device 1 is equipped with: a differential case 7; a differential gear 11; a pair of output gears 13 and 15; and a differential restricting part 5 that has a conical case side sliding surface 39 and a gear side sliding surface 29 sliding with each other respectively provided between the differential case 7 and the pair of output gears 13 and 15, and restricts a differential motion of the pair of output gears 13 and 15. On the case side sliding surface 39, there are provided radial grooves 43 that are radially extended from an axis side toward an outside in a diametrical direction and in which a lubricant flows. On the gear side sliding surface 29, a spiral groove 45 that is spirally wound in an axial direction and in which the lubricant flows is provided. In the spiral groove 45, a winding direction on the gear side sliding surface 29 is set so as to make a torque bias ratio at right turning of a vehicle and a torque bias ratio at left turning of the vehicle come close to each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, a differential device includes a rotatably arranged differential case, a differential gear supported rotatably on the differential case and revolving with the rotation of the differential case, and a pair of output gears that mesh with the differential gear and can rotate relatively. Also, a differential device that includes differential limiting units that are provided between the differential case and the pair of output gears and limit the differential between the pair of output gears is known (see Patent Document 1).

[0003] In this differential device, the differential limiting portion has a conical case-side sliding surface provided on the differential case side and a conical gear-side sliding surface provided on the output gear side. The differential limiting portion limits the differential movement of the pair of output gears by sliding between the case-side sliding surface and the gear-side sliding surface. In this differential limiting portion, multiple intersecting grooves through which lubricating oil flows are formed on at least one of the case-side sliding surface and the gear-side sliding surface, thereby maintaining the lubrication of the differential limiting portion.

[0004] Meanwhile, another type of differential device is known in which a case-side sliding surface is provided with a plurality of radial grooves extending radially outward from the axis side and through which lubricating oil flows (see Patent Document 2). In this differential device, the lubricating oil flows through the radial grooves, thereby maintaining the lubrication of the differential limiting section. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-89075 [Patent Document 2] Patent Publication No. 2021-191961 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the differential devices as disclosed in the above-mentioned Patent Documents 1 and 2, the torque bias ratio indicating the differential limiting characteristic of the differential limiting part is different when the vehicle turns left or right. If the torque bias ratio is different when the vehicle turns left or right, some operators who operate the vehicle may feel uncomfortable.

[0007] In the differential devices of Patent Documents 1 and 2, grooves through which lubricating oil flows are formed on the sliding surface of the differential limiting section, but the grooves are designed only to improve the lubrication of the differential limiting section. In other words, with the grooves as in Patent Documents 1 and 2, the torque bias ratios when the vehicle turns left and right do not approach each other.

[0008] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a differential device capable of bringing the torque bias ratios closer together when the vehicle is turning left or right. [Means for solving the problem]

[0009] The differential device according to this embodiment includes a rotatably arranged differential case, a differential gear supported on the differential case so as to be rotatable about its axis and revolving due to the rotation of the differential case, a pair of output gears that mesh with the differential gear and can rotate relatively, and a conical case-side sliding surface and a gear-side sliding surface that are provided between the differential case and the pair of output gears, respectively, and that slide against each other. A differential limiting unit is provided to limit the differential between the pair of output gears, and the case-side sliding surface has a plurality of radial grooves extending radially from the axial center side toward the radially outward, through which lubricating oil flows, and the gear-side sliding surface has a spiral groove wound in the axial direction and through which lubricating oil flows. The spiral groove has a winding direction on the gear-side sliding surface so as to bring the torque bias ratio when the vehicle turns right and the torque bias ratio when the vehicle turns left closer to each other. Effect of the Invention

[0010] According to the present invention, it is possible to provide a differential device that can bring the torque bias ratios closer together when the vehicle turns left or right. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view of the differential device according to the embodiment. [Diagram 2] FIG. 2 is a perspective view of a pair of output gears and a tapered ring of the differential device according to the embodiment. [Diagram 3] FIG. 4 is an enlarged view of a main portion of a tapered ring of the differential device according to the embodiment. [Figure 4] FIG. 2 is an enlarged view of a main portion of an output gear of the differential device according to the embodiment. [Diagram 5] 1 is a side view of a differential device according to an embodiment of the present invention, in which the spiral grooves of a pair of output gears are both right-handed. FIG. [Figure 6] 1 is a side view of a differential device according to an embodiment of the present invention, in which one of a pair of output gears has a left-handed spiral groove and the other has a right-handed spiral groove. FIG. [Figure 7] 1 is a side view of a differential device according to an embodiment of the present invention, in which one of a pair of output gears has a right-handed spiral groove and the other has a left-handed spiral groove. FIG. [Figure 8] 1 is a side view of a differential device according to an embodiment of the present invention, in which the spiral grooves of a pair of output gears are both right-handed. FIG. [Figure 9] FIG. 6 is a diagram showing TBR when a vehicle turns left or right in the case of the spiral groove shown in FIG. 5. [Figure 10] FIG. 7 is a diagram showing TBR when a vehicle turns left or right in the case of the spiral groove shown in FIG. 6. [Figure 11] FIG. 8 is a diagram showing TBR when a vehicle turns left or right in the case of the spiral groove shown in FIG. 7. [Figure 12] FIG. 9 is a diagram showing TBR when a vehicle turns left or right in the case of the spiral groove shown in FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The differential device according to the present embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios.

[0013] 1, a differential device 1 according to this embodiment is disposed between a drive source (not shown), such as an engine or an electric motor, and left and right wheels (not shown). Driving force from the drive source is transmitted to the differential device 1 via a transmission (not shown), and the driving force is distributed to the left and right wheels via a pair of output shafts (not shown).

[0014] As shown in FIGS. 1 to 4, the differential device 1 includes a differential mechanism 3 and a differential limiting section 5. The differential mechanism 3 and the differential limiting section 5 include a differential lock section 5a and a differential lock section 5b.

[0015] The differential mechanism 3 includes a differential case 7, a pinion shaft 9, a differential gear 11, and a pair of output gears 13 and 15.

[0016] The differential case 7 is rotatably supported by a stationary member (not shown) such as a carrier via bearings (not shown) at the outer periphery of each of bosses 17, 19 formed on both axial sides. The differential case 7 is formed with a flange portion 21 to which a ring gear (not shown) is fixed. The ring gear fixed to the flange portion 21 meshes with a power transmission gear (not shown) that transmits a driving force, and the driving force is transmitted to rotate the differential case 7. A pinion shaft 9, a differential gear 11, a pair of output gears 13, 15, etc. are housed and arranged inside the differential case 7.

[0017] The pinion shaft 9 has an end engaged with a hole formed in the differential case 7 and is prevented from coming off and rotating by a pin 23, and is rotated integrally with the differential case 7. Differential gears 11 are supported on both axial ends of the pinion shaft 9, respectively.

[0018] A plurality of differential gears 11 (two in this example) are arranged at equal intervals in the circumferential direction of the differential case 7, each supported on the shaft end side of the pinion shaft 9 and revolving with the rotation of the differential case 7. The differential gear 11 transmits driving force to the pair of output gears 13, 15, and is rotatably supported by the pinion shaft 9 so as to be rotationally driven when a differential rotation occurs between the pair of meshed output gears 13, 15.

[0019] The pair of output gears 13, 15 are accommodated in the differential case 7 so as to be capable of relative rotation. Each of the pair of output gears 13, 15 includes a gear member 25 and an output member 27. In the pair of output gears 13, 15, the gear member 25 and the output member 27 are formed symmetrically, so that only one of them will be mainly described below, and a description of the other will be omitted.

[0020] The gear member 25 is formed in an annular shape, and a gear portion that meshes with the differential gear 11 is formed on the outer circumferential side. The gear member 25 meshes with the differential gear 11, thereby transmitting driving force from the differential gear 11 to the pair of output gears 13, 15. In addition, when a differential rotation occurs between the pair of output gears 13, 15, the gear member 25 rotates the differential gear 11.

[0021] The output member 27 is formed in a concave ring shape capable of accommodating a part of the gear member 25 in the axial direction so that the output member 27 can be arranged close to the gear member 25 in the axial direction. A gear-side sliding surface 29 inclined in the axial direction is provided in a portion of the output member 27 located radially outward of the gear member 25. On the inner peripheral side of the output member 27, spline-shaped output portions 31 and 33 are formed in the pair of output gears 13 and 15, which can be connected to the pair of output shafts so as to be rotatable together. The output member 27 outputs the driving force input from the differential case 7 to the pair of output gears 13 and 15 to the left and right wheels via the pair of output shafts.

[0022] A cam portion 35 that converts rotational torque into axial thrust force is provided between the gear member 25 and the output member 27 in the axial direction. The cam portion 35 is composed of a plurality of engaging recesses provided on the inner peripheral side of the gear member 25 and a plurality of engaging protrusions that are provided on the outer peripheral side of the output member 27 and can engage with the plurality of engaging recesses. The cam portion 35 enables the gear member 25 and the output member 27 to rotate integrally by engaging the plurality of engaging recesses with the plurality of engaging protrusions.

[0023] On the other hand, in cam portion 35, the engagement surface in the rotational direction between the multiple engagement recesses and the multiple engagement protrusions is a cam surface inclined at a predetermined angle. When a driving force (driving torque) is input to differential case 7, the cam surface in cam portion 35 is actuated by the driving force branched from differential gear 11 and input to the pair of output gears 13, 15, causing cam portion 35 to move output member 27 outward in the axial direction. The axial movement of output member 27 by cam portion 35 can increase and strengthen the differential limiting force in differential limiting unit 5 arranged between differential case 7 and the pair of output gears 13, 15.

[0024] The differential limiting portion 5 is disposed between the differential case 7 and the pair of output gears 13, 15. The differential limiting portion 5 has a tapered ring 37 and an output member 27 which slide against each other.

[0025] The tapered rings 37 are disposed at positions corresponding to the gear-side sliding surfaces 29 of the output members 27 of the pair of output gears 13, 15 with respect to the differential case 7. The tapered ring 37 rotates integrally with the differential case 7 by engaging a plurality of convex portions formed in the circumferential direction on the inner peripheral side with concave portions formed on the inner wall surface of the differential case 7. A case-side sliding surface 39 that is conically inclined in the axial direction and can slide against the gear-side sliding surface 29 is provided at a portion of the tapered ring 37 located at the gear-side sliding surface 29.

[0026] The case side sliding surface 39 of the tapered ring 37 slides against the gear side sliding surface 29 of the output member 27 of the pair of output gears 13, 15 which is moved axially by a meshing reaction force with the differential gear 11 according to the magnitude of the driving force (driving torque) input to the differential case 7. At this time, the sliding friction between the case side sliding surface 39 and the gear side sliding surface 29, which is the differential limiting force of the differential limiting unit 5, is increased and strengthened by the cam thrust force of the cam unit 35.

[0027] The differential limiting unit 5 transmits friction torque between the differential case 7 and the pair of output gears 13, 15 in response to the magnitude of the cam thrust force, thereby limiting the differential of the differential mechanism 3. Such a differential limiting unit 5 is a cone clutch type among torque-sensitive friction clutches. A preload is applied to the differential limiting unit 5 by a biasing member 41.

[0028] The biasing member 41 is made of a disc spring, and is disposed axially between the gear member 25 and the output member 27. The biasing member 41 biases the gear member 25 axially inward (toward the differential gear 11), and biases the output member 27 axially outward (toward the differential limiting unit 5). By disposing the biasing member 41 between the gear member 25 and the output member 27, a preload is applied to the differential limiting unit 5, and the intermittent characteristic of the differential limiting unit 5 can be stabilized.

[0029] In order to improve lubrication in the differential limiting section 5, a radial groove 43 is formed on the case side sliding surface 39, and a spiral groove 45 is formed on the gear side sliding surface 29.

[0030] The radial grooves 43 are provided on the case side sliding surface 39 of the tapered ring 37. The radial grooves 43 extend radially outward from the axial center side on the case side sliding surface 39, and a plurality of radial grooves 43 are arranged in the circumferential direction. Due to the rotation of the differential case 7 and the pair of output gears 13, 15, lubricating oil flows into the radial grooves 43 from the inner diameter side, flows through the radial grooves 43, and then flows out from the outer diameter side.

[0031] The spiral groove 45 is provided on the gear-side sliding surface 29 of the pair of output gears 13, 15. The spiral groove 45 is wound spirally in the axial direction on the gear-side sliding surface 29, and both axial ends are open on both axial side surfaces of the output gears 13, 15. Due to the rotation of the differential case 7 and the pair of output gears 13, 15, lubricating oil flows into the spiral groove 45 from an opening on the axial outer side, flows through the spiral groove 45, and then flows out from an opening on the axial inner side.

[0032] Here, the differential limiting characteristic of the differential 1 is evaluated by the torque ratio (torque bias ratio: TBR) of the pair of output gears 13, 15. The TBR is expressed as the ratio of the torque on the low rotation side to the torque on the high rotation side. The locking ratio of the differential limiting unit 5 required to achieve the target TBR is calculated by the formula (TBR-1) / (TBR+1). In the differential 1, when the input torque is T and the locking ratio of the differential limiting unit 5 is C, the clutch torque of the differential limiting unit 5 can be calculated by the formula T×C.

[0033] In the conventional differential device, the TBR when the vehicle turns right is different from the TBR when the vehicle turns left. If the TBR is different when the vehicle turns left and right, some operators may feel uncomfortable when operating the vehicle. Therefore, it was discovered that the TBR when the vehicle turns left and right can be made closer by setting the winding direction of the spiral groove 45 of the pair of output gears 13, 15 in the differential limiting unit 5.

[0034] Here, the flow of lubricating oil in the winding direction of the spiral groove 45 in the differential limiting unit 5 and the rotation direction of the pair of output gears 13, 15 will be described. Note that here, the pair of output gears 13, 15 shown in FIG. 2 will be used for the description. In the pair of output gears 13, 15, both spiral grooves 45, 45 are inclined rightward from the lower side to the upper side with respect to the axial direction, and this is referred to as a right-handed winding direction. Note that hereinafter, the winding direction of the spiral groove 45 in the opposite direction is referred to as a left-handed winding direction.

[0035] For example, when the vehicle turns right, the output gear 13 rotates upward in Fig. 2, and the output gear 15 rotates downward in Fig. 2. At this time, due to the radial grooves 43 of the tapered ring 37, the lubricating oil flows from the left side to the right side in Fig. 2 in the output gear 13, and the lubricating oil flows from the right side to the left side in Fig. 2 in the output gear 15. The lubricating oil flowing into the pair of output gears 13, 15 flows in the rotation direction of the pair of output gears 13, 15. Therefore, in the output gear 13, the lubricating oil flows upward in Fig. 2, and in the output gear 15, the lubricating oil flows downward in Fig. 2.

[0036] In the right-handed spiral groove 45, the lubricating oil is inclined in the output gear 13 so as to spread in the axial direction with respect to the flow of the lubricating oil, so that the lubricating oil is easily spread to the differential limiting section 5. On the other hand, in the right-handed spiral groove 45, the lubricating oil is inclined in the output gear 15 so as to return in the axial direction with respect to the flow of the lubricating oil, so that the lubricating oil is not easily spread to the differential limiting section 5. When the vehicle turns left, the spreadability of the lubricating oil is reversed in the pair of output gears 13, 15. In addition, when the winding direction of the spiral groove 45 is left-handed, the spreadability of the lubricating oil when the vehicle turns left or right is reversed to that of the right-handed spiral groove 45.

[0037] Combinations of the winding directions of the spiral groove 45 in the pair of output gears 13, 15 are shown in Figs. 5 to 8. In Fig. 5, the winding direction of the spiral groove 45 of the pair of output gears 13, 15 is clockwise. In Fig. 6, the winding direction of the spiral groove 45 of the output gear 13 is counterclockwise, and the winding direction of the spiral groove 45 of the output gear 15 is clockwise. In Fig. 7, the winding direction of the spiral groove 45 of the output gear 13 is clockwise, and the winding direction of the spiral groove 45 of the output gear 15 is counterclockwise. In Fig. 8, the winding direction of the spiral groove 45 of the pair of output gears 13, 15 is counterclockwise.

[0038] The measurement results of the TBR when the vehicle turns left and right for the combinations of the spiral grooves 45 of Figs. 5 to 8 are shown in Figs. 9 to 12. In the measurement, the TBR when the vehicle turns left and right was detected three times, and the average value was taken as the TBR when the vehicle turns left and right. As is clear from Figs. 9 to 12, the TBR when the vehicle turns left and right was close in all combinations. The difference between the TBRs when the vehicle turns left and right was within 0.1 in all combinations. In addition, the TBR when the vehicle turns left and right was the closest value for the combination in which the winding directions of the spiral grooves 45 of the pair of output gears 13, 15 were counterclockwise. From the above, by setting the winding directions of the spiral grooves 45 of the pair of output gears 13, 15, the TBRs when the vehicle turns left and right can be made close to each other, and the discomfort of the operator can be reduced.

[0039] Here, the TBR during left and right turning of the vehicle can be made closer by changing the extension direction of the radial groove 43 on the case side sliding surface 39. The extension direction of the radial groove 43 shown in FIG. 2 is along an extension line extending from the center of the tapered ring 37 toward the outside in the radial direction. In contrast, when changing the extension direction of the radial groove 43, for example, the radial groove 43 is extended toward the outside in the radial direction from an eccentric position shifted from the center position of the tapered ring 37. By changing the extension direction of the radial groove 43, the spreadability of the lubricating oil in the differential limiting unit 5 changes, and the TBR during left and right turning of the vehicle can be made closer. Note that, in the spiral groove 45, by changing the inclination angle with respect to the axial direction (the number of turns with respect to the gear side sliding surface 29), the spreadability of the lubricating oil in the differential limiting unit 5 changes, and the TBR during left and right turning of the vehicle can be made closer.

[0040] Such a differential device 1 includes a rotatably arranged differential case 7, a differential gear 11 supported rotatably on the differential case 7 and revolving with the rotation of the differential case 7, and a pair of output gears 13, 15 meshing with the differential gear 11 and capable of relative rotation. In addition, a differential limiting unit 5 is provided between the differential case 7 and the pair of output gears 13, 15, and has a conical case-side sliding surface 39 and a gear-side sliding surface 29 that slide against each other, and limits the differential between the pair of output gears 13, 15. Furthermore, the case-side sliding surface 39 is provided with a plurality of radial grooves 43 extending radially from the axial center side toward the radially outward, through which lubricating oil flows. In addition, the gear-side sliding surface 29 is provided with a spiral groove 45 that is wound helically in the axial direction and through which lubricating oil flows. The spiral groove 45 has a winding direction on the gear-side sliding surface 29 set so as to bring the torque bias ratio when the vehicle turns right closer to the torque bias ratio when the vehicle turns left.

[0041] In the pair of output gears 13, 15, the spread of the lubricating oil in the differential limiting unit 5 can be changed by setting the winding direction of the spiral groove 45 on the gear side sliding surface 29. Therefore, by changing the setting of the winding direction of the spiral groove 45, the torque bias ratios when the vehicle turns left or right can be made closer to each other, and the discomfort felt by the operator can be reduced.

[0042] Therefore, in such a differential device 1, the torque bias ratios can be made closer to each other when the vehicle is turning left or right.

[0043] Further, the extending direction of the radial grooves 43 on the case-side sliding surface 39 is set so as to bring the torque bias ratio when the vehicle turns right closer to the torque bias ratio when the vehicle turns left.

[0044] Therefore, by changing the extending direction of the radial grooves 43, the spread of the lubricating oil in the differential limiting section 5 changes, and the TBR during left and right turning of the vehicle can be made closer to each other.

[0045] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment.

[0046] For example, in the differential device according to this embodiment, the case side sliding surface is provided on a tapered ring arranged so as to be able to rotate integrally with the differential case, but this is not limited thereto, and the case side sliding surface may be provided on the inner wall surface of the differential case without using a tapered ring.

[0047] Further, the output gear is configured by a gear member and an output member, but is not limited to this, and the output gear may be configured by one continuous member. [Explanation of symbols]

[0048] 1 Differential device 5. Limited slip differential 7 Differential Case 11 Differential gear 13,15 Output gear 29 Gear side sliding surface 39 Case side sliding surface 43 Radial Groove 45 Spiral groove

Claims

1. A rotatably disposed differential case; A differential gear that is rotatably supported by the differential case and revolves with the rotation of the differential case; a pair of output gears meshing with the differential gear and relatively rotatable; A differential limiting unit is provided between the differential case and the pair of output gears, and has a conical case side sliding surface and a gear side sliding surface that slide against each other, and limits the differential between the pair of output gears. Equipped with The case-side sliding surface is provided with a plurality of radial grooves extending radially from the axial center side toward the outside in the radial direction, through which lubricating oil flows; The gear-side sliding surface is provided with a spiral groove that is wound in a spiral shape in the axial direction and through which lubricating oil flows, A differential device in which the spiral groove has a winding direction on the gear side sliding surface set so as to bring the torque bias ratio when the vehicle turns right closer to the torque bias ratio when the vehicle turns left.

2. 2. The differential device according to claim 1, wherein the radial grooves have an extension direction on the case-side sliding surface set so as to bring a torque bias ratio closer to a torque bias ratio when the vehicle turns right and a torque bias ratio when the vehicle turns left.

Images