Differential gear mechanism and its design method
The differential gear mechanism achieves compactness and strength by inclining tooth roots and varying pressure angles, addressing the limitations of conventional designs to ensure robust and efficient operation.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- AISIN CORP
- Filing Date
- 2023-08-04
- Publication Date
- 2026-06-23
Smart Images
Figure 0007878212000001 
Figure 0007878212000002 
Figure 0007878212000003
Abstract
Description
Technical Field
[0001] The present disclosure relates to a differential gear mechanism including a pair of side gears and a plurality of pinion gears meshing with the pair of side gears, and a design method thereof.
Background Art
[0002] Conventionally, a differential gear in which a pinion gear, which is a straight bevel gear rotatably supported by a pinion shaft fixed to a case, is meshed with a pair of side gears is known (see, for example, Patent Document 1). In this differential gear, in order to secure the thickness of the inner end portion (the end portion on the center side of the differential gear) of the pinion gear, the inner end portion of the tooth root of the pinion gear is inclined so as to be located on the tooth tip cone side rather than the tooth root cone of the pinion gear. Further, the inner end portion of the tooth tip of the gear tooth of the side gear is inclined so as to be located on the tooth root cone side rather than the tooth tip cone of the side gear, and extends along the inner end portion of the tooth root of the pinion gear.
[0003] Also conventionally, a differential mechanism including a pinion shaft fixed to a case, a pinion gear which is a bevel gear rotatably supported by the pinion shaft, and a pair of side gears which are bevel gears each meshing with the pinion gear is known (see, for example, Patent Document 2). In this differential mechanism, in order to shorten the axial length of the differential mechanism while suppressing a decrease in the strength of the side gears, the outer end portion (the end portion on the outer peripheral side) of the tooth root of each side gear is inclined so as to be located on the tooth tip cone side rather than the tooth root cone of the side gear. Further, the outer end portion of the tooth tip of the pinion gear teeth of the pinion gear is inclined so as to be located on the tooth root cone side rather than the tooth tip cone of the pinion gear, and extends along the outer end portion of the tooth root of the side gear.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
[0005] However, as described in Patent Document 1, if the inner end of the tooth root of a pinion gear is inclined to be located closer to the tip cone than the root cone of the pinion gear, the tooth thickness at the root of the pinion gear teeth becomes smaller at the inner end of the pinion gear (the end closer to the center of the differential gear), reducing the strength of the pinion gear. Therefore, without some countermeasures, it becomes difficult to reduce the diameter of the pinion gear and make the differential gear more compact while ensuring the strength of the pinion gear. Also, as described in Patent Document 2, if the outer end of the tooth root of a side gear is inclined to be located closer to the tip cone than the root cone of the side gear, the tooth thickness at the root of the gear teeth becomes smaller at the outer end of the side gear (differential mechanism), reducing the strength of the side gear. Therefore, without some countermeasures, it becomes difficult to shorten the axial length of the differential mechanism in the axial direction of the side gear while ensuring the strength of the side gear.
[0006] Therefore, the primary objective of this disclosure is to make a differential gear mechanism, which includes a pair of side gears and a plurality of pinion gears that mesh with the pair of side gears, more compact while ensuring sufficient strength of the side gears and pinion gears. [Means for solving the problem]
[0007] The differential gear mechanism of the present disclosure includes a pair of side gears, each a bevel gear having a plurality of side gear teeth, and a plurality of pinion gears, each a bevel gear having a plurality of pinion gear teeth, which mesh with the pair of side gears, wherein the outer end of the tooth root of the side gear is inclined to be located on the tip cone side of the side gear more than the tooth root cone of the side gear, and the inner end of the tooth tip of the side gear is located on the tooth root side of the side gear more than the tip cone of the side gear The pinion gear is inclined to be located on the conical side, the inner end of the tooth root of the pinion gear is inclined to be located on the tip cone side of the pinion gear more than the tooth root cone of the pinion gear, the outer end of the tooth tip of the pinion gear is inclined to be located on the tooth root cone side of the pinion gear more than the tooth tip cone of the pinion gear, the reference pressure angle is the angle between the radius line passing through the pitch point of the side gear tooth and the tangent to the tooth profile, and the angle between the radius line passing through the pitch point of the pinion gear tooth and the tangent to the tooth profile The reference pressure angle increases from the middle to the inner end of the tooth trace included between the inner end of the tooth tip of the side gear tooth and the outer end of the tooth tip of the pinion gear tooth in the tooth trace direction, and also increases from the middle to the outer end. The tooth thickness of the side gear on the pitch cone decreases from the middle to the inner end and increases from the middle to the outer end compared to a reference side gear where the intersection line between the tooth surface of the side gear tooth and the pitch cone is a straight line passing through the center of the differential gear mechanism and the reference pressure angle is constant in the tooth trace direction. The tooth thickness of the pinion gear on the pitch cone increases from the middle to the inner end and decreases from the middle to the outer end compared to a reference pinion gear where the intersection line between the tooth surface of the pinion gear tooth and the pitch cone is a straight line passing through the center and the reference pressure angle is constant in the tooth trace direction.
[0008] Furthermore, the differential gear mechanism design method of the present disclosure includes a pair of side gears, each of which is a bevel gear having a plurality of side gear teeth, and a plurality of pinion gears, each of which is a bevel gear having a plurality of pinion gear teeth, and which mesh with the pair of side gears, wherein the outer end of the tooth root of the side gear is inclined to be located on the tip cone side of the side gear more than the tooth root cone of the side gear, and the inner end of the tooth tip of the side gear is located on the tooth root cone side of the side gear more than the tip cone of the side gear A method for designing a differential gear mechanism, wherein the pinion gear is inclined such that the inner end of the tooth root of the pinion gear is located on the tip cone side of the pinion gear rather than the tooth root cone, and the outer end of the tooth tip of the pinion gear is located on the tooth root cone side of the pinion gear rather than the tip cone, wherein the reference pressure angle is the angle between the radius line passing through the pitch point of the side gear tooth and the tangent to the tooth profile, and the tangent between the radius line passing through the pitch point of the pinion gear tooth and the tangent to the tooth profile The reference pressure angle, which is the angle with respect to the line, is increased from the middle of the tooth trace between the inner end of the tooth tip of the side gear tooth and the outer end of the tooth tip of the pinion gear tooth in the tooth trace direction, and also increases from the middle of the tooth trace towards the outer end, and the tooth thickness on the pitch cone of the side gear is set such that the line of intersection between the tooth surface of the side gear tooth and the pitch cone is a straight line passing through the center of the differential gear mechanism, and the reference pressure angle is constant in the tooth trace direction. Compared to a dog gear, the tooth thickness of the pinion gear is made smaller from the middle portion toward the inner end and larger from the middle portion toward the outer end, and compared to a reference pinion gear in which the intersection line between the tooth surface of the pinion gear teeth and the pitch cone is a straight line passing through the center and the reference pressure angle is constant in the tooth trace direction, the tooth thickness of the pinion gear is made larger from the middle portion toward the inner end and smaller from the middle portion toward the outer end. [Brief explanation of the drawing]
[0009] [Figure 1] This is a schematic diagram showing the differential gear mechanism of the present disclosure. [Figure 2] This is a partial cross-sectional view showing the differential gear mechanism of the present disclosure. [Figure 3] This diagram shows the relationship between the conical distance and the reference pressure angle in the side gear and pinion gear of the differential gear mechanism of this disclosure. [Figure 4] This diagram shows the relationship between the conical distance and the tooth thickness on the pitch cone in the side gear of the differential gear mechanism of this disclosure. [Figure 5] This diagram shows the relationship between the conical distance and the tooth thickness on the pitch cone in the pinion gear of the differential gear mechanism of this disclosure. [Figure 6] This diagram shows the relationship between the conical distance and the tooth root thickness in the side gear of the differential gear mechanism of this disclosure. [Figure 7] This diagram shows the relationship between the conical distance and the tooth root thickness in the pinion gear of the differential gear mechanism of this disclosure. [Figure 8] This is an enlarged view showing the main part of the differential gear mechanism of this disclosure. [Figure 9] This is an enlarged view showing the main part of the differential gear mechanism of this disclosure. [Figure 10] This is an explanatory diagram illustrating the tooth tip sharpening that may occur in the pinion gear of the differential gear mechanism of the present disclosure. [Figure 11] This is an explanatory diagram illustrating the tooth root cutoff that may occur in the pinion gear of the differential gear mechanism of the present disclosure. [Figure 12] This is a schematic diagram showing the meshing state of the side gear and pinion gear in the differential gear mechanism of this disclosure. [Figure 13] This diagram illustrates the procedure for adjusting the pressure angle in the pinion gear of the differential gear mechanism of this disclosure. [Figure 14] This diagram illustrates the pressure angle adjustment amounts for the side gears and pinion gears of the differential gear mechanism of this disclosure. [Figure 15] This diagram illustrates the pressure angle adjustment amounts for the side gears and pinion gears of the differential gear mechanism of this disclosure. [Figure 16] This diagram illustrates the procedure for adjusting the pressure angle in the pinion gear of the differential gear mechanism of this disclosure.
Embodiments for Carrying Out the Invention
[0010] Next, embodiments for carrying out the invention of the present disclosure will be described with reference to the drawings.
[0011] FIG. 1 is a perspective view showing a differential gear mechanism 1 of the present disclosure, and FIG. 2 is a partial cross-sectional view showing a main part of the differential gear mechanism 1. The differential gear mechanism 1 shown in these drawings is included in a differential gear mounted on a vehicle together with a differential ring gear and a differential case (not shown). The differential gear mechanism 1 includes a pair of side gears 2 and a plurality (for example, 2 to 4 in this embodiment) of pinion gears 3 that mesh with the pair of side gears 2 respectively. The pair of side gears 2 are fixed to corresponding drive shafts (not shown) respectively. Also, corresponding ones of a plurality of pinion shafts that are supported by the differential case and extend radially so as to be orthogonal to the axial direction of the pair of side gears 2 are inserted into each pinion gear 3. Thereby, each pinion gear 3 is rotatably supported by the differential case via the pinion shaft.
[0012] Each side gear 2 is a bevel gear, and as shown in FIGS. 1 and 2, a plurality of side gear teeth 20 respectively formed so as to extend radially from the center O of the differential gear mechanism 1 through which the axes of each side gear 2 and each pinion gear 3 pass, and a plurality of tooth bottoms 25 located between adjacent side gear teeth 20 are included. As shown in FIG. 2, each side gear tooth 20 includes a pair of tooth surfaces 21 formed based on a spherical involute curve, and a tooth tip 23 formed between the pair of tooth surfaces 21. In this embodiment, the outer end portion 25o of the tooth bottom 25 of each side gear 2 (the region on the outer peripheral side of the side gear 2 with respect to the boundary B2 in FIG. 2) is inclined so as to be located on the tooth tip cone TC2 side of the side gear 2 rather than the tooth bottom cone RC2 of the side gear 2. Thereby, it becomes possible to suppress a decrease in the thickness of the outer peripheral portion of the side gear 2 and suppress a decrease in the strength of the side gear 2.
[0013] Each pinion gear 3 is a bevel gear and includes a plurality of pinion gear teeth 30 formed to extend radially from the center O of the differential gear mechanism 1 as shown in FIGS. 1 and 2, and a plurality of tooth bottoms 35 located between adjacent pinion gear teeth 30. As shown in FIG. 2, each pinion gear tooth 30 includes a pair of tooth surfaces 31 formed based on a spherical involute curve and a tooth tip 33 formed between the pair of tooth surfaces 31. In the present embodiment, the inner end portion 35i of the tooth bottom 35 of each pinion gear 3 (the region on the center O side from the boundary B3 in FIG. 2) is inclined so as to be located on the tooth tip cone TC3 side of the tooth bottom cone RC3 of the pinion gear 3. Thereby, it is possible to suppress a decrease in the thickness of the inner end portion (the end portion on the center O side) of the pinion gear 3 and ensure good strength of the pinion gear 3. Note that the side gear 2 and the pinion gear 3 are formed such that the tooth profile of one is formed by generation using the tooth profile of the other with their axial centers aligned in the meshed state, and they are in a conjugate relationship with each other in the meshed state.
[0014] Also, as shown in FIG. 2, the inner end portion 23i of the tooth tip 23 of each side gear tooth 20 is formed to extend along the inner end portion 35i of the tooth bottom 35 of the pinion gear 3. That is, the inner end portion 23i of the tooth tip 23 of each side gear tooth 20 is inclined so as to be located on the tooth bottom cone RC2 side of the tooth tip cone TC2 of the side gear 2. Further, as shown in FIG. 2, the outer end portion 33o of the tooth tip 33 of each pinion gear tooth 30 is formed to extend along the outer end portion 25o of the tooth bottom 25 of the side gear 2. That is, the outer end portion 33o of the tooth tip 33 of each pinion gear tooth 30 is inclined so as to be located on the tooth bottom cone RC3 side of the tooth tip cone TC3 of the pinion gear 3.
[0015] Here, as shown in Figure 2, if the outer end 25o of the tooth root 25 of the side gear 2 is inclined to be located on the tooth tip cone TC2 side of the tooth root cone RC2 of the side gear 2, the tooth thickness at the tooth root of each side gear tooth 20 becomes smaller on the outer circumference of the side gear 2, and the strength of each side gear tooth 20 and thus the side gear 2 decreases. Therefore, in order to shorten the axial length of the differential gear mechanism 1 in the axial direction of the side gear 2 (drive shaft), it is necessary to suppress the decrease in the strength of each side gear tooth 20, i.e., the side gear 2, while keeping the outer end 25o of the tooth root 25 inclined towards the tooth tip 23 side.
[0016] Furthermore, if the inner end 35i of the tooth root 35 of the pinion gear 3 is inclined to be located on the tooth tip cone TC3 side of the tooth root cone RC3 of the pinion gear 3, the tooth thickness at the tooth root of each pinion gear tooth 30 becomes smaller at the inner end (the end on the center O side) of the pinion gear 3, which reduces the strength of each pinion gear tooth 30 and, consequently, the pinion gear 3. Therefore, in order to reduce the diameter of the pinion gear 3 and make the differential gear mechanism 1 more compact, it is necessary to suppress the reduction in the strength of each pinion gear tooth 30, i.e., the pinion gear 3, while keeping the inner end 35i of the tooth root 35 inclined towards the tooth tip 33 side.
[0017] Based on these considerations, the inventors diligently conducted research to make the differential gear mechanism 1 more compact while ensuring sufficient strength for each side gear 2 and each pinion gear 3. In the process, they focused on the reference pressure angle at the pitch point of the side gear teeth 20 (the angle between the radius line passing through the pitch point and the tangent to the tooth surface (tooth profile)) and the reference pressure angle at the pitch point of the pinion gear teeth 30 (the angle between the radius line passing through the pitch point and the tangent to the tooth surface (tooth profile)). Furthermore, the present inventors have decided to vary the reference pressure angles of the side gear teeth 20 and the pinion gear teeth 30 (hereinafter referred to as "reference pressure angle α") that coincide with each other in the direction of the tooth trace (hereinafter referred to as "tooth trace direction") where the tooth trace is extended (the intersection line between the pitch cone PC2 of the side gear 2 and the tooth surface 21 of the side gear teeth 20 and the intersection line between the pitch cone PC3 of the pinion gear 3 and the tooth surface 31 of the pinion gear teeth 30).
[0018] In other words, in the differential gear mechanism 1, the reference pressure angle α of each side gear tooth 20 and each pinion gear tooth 30 gradually increases from the middle part M of the tooth trace toward the inner end (towards the center O), as shown in Figure 3, and also gradually increases from the middle part M toward the outer end (towards the outer circumference of the side gear 2). In this embodiment, the middle part M of the tooth trace is a point located near the midpoint of the tooth trace, between the inclined inner end 23i of the tooth tip 23 of the side gear tooth 20 and the inclined outer end 33o of the tooth tip 33 of the pinion gear tooth 30 in the direction of the tooth trace, that is, within the range S (the range between the two dashed lines in Figure 2) where the meshing of the side gear tooth 20 and the pinion gear tooth 30 is defined only by the tooth tip cone TC2 of the side gear 2 and the tooth tip cone TC3 of the pinion gear 3. In this embodiment, range S is approximately 40-60% of the meshing range between the side gear teeth 20 and the pinion gear teeth 30, in the tooth trace direction centered on the intermediate portion M.
[0019] The intermediate portion M may also be the midpoint of the tooth trace. Furthermore, in the example in Figure 2, the inner end 23i of the tooth tip 23 of the side gear 2 is located closer to the center O in the tooth trace direction than the outer end 33o of the tooth tip 33 of the pinion gear tooth 30, but this is not limited to this. For example, the inner end 23i of the tooth tip 23 of the side gear 2 may extend further outward (opposite side from the center O) in the tooth trace direction than the outer end 33o of the tooth tip 33 of the pinion gear tooth 30. In this case as well, the intermediate portion M can be defined to be included within the above range S. Moreover, the position of the outer peripheral end of the inner end 23i in the tooth trace direction and the position of the end of the outer end 33o on the center O side in the tooth trace direction may coincide. In this case, the intermediate portion M coincides with the position of the outer peripheral end of the inner end 23i in the tooth trace direction and the position of the end of the outer end 33o on the center O side in the tooth trace direction.
[0020] Furthermore, in the differential gear mechanism 1, in addition to changing the reference pressure angle α in the tooth trace direction as shown in Figure 3, the tooth thickness (arc tooth thickness) of the side gear 2 on the pitch cone PC2 is set to decrease from the intermediate part M toward the inner end (towards the center O) and increase from the intermediate part M toward the outer end (towards the outer circumference of the side gear 2), as shown by the solid line in Figure 4. Also, in the differential gear mechanism 1, the tooth thickness (arc tooth thickness) of the pinion gear 3 on the pitch cone PC3 is set to increase from the intermediate part M toward the inner end and decrease from the intermediate part M toward the outer end, as shown by the solid line in Figure 5.
[0021] The reference side gear is a straight bevel gear in which the intersection line between the tooth surface of the side gear teeth and the pitch cone is a straight line passing through the center of the differential gear mechanism, and the reference pressure angle α is constant in the tooth trace direction. In the reference side gear, the cross section of the side gear teeth cut by a sphere centered at the center of the differential gear mechanism is enlarged or reduced along the axis of the reference side gear by a similarity ratio corresponding to the distance from the center (radius of the sphere). Similarly, the reference pinion gear is a straight bevel gear in which the intersection line between the tooth surface of the pinion gear teeth and the pitch cone is a straight line passing through the center of the differential gear mechanism, and the reference pressure angle α is constant in the tooth trace direction. In the reference pinion gear, the cross section of the pinion gear teeth cut by a sphere centered at the center of the differential gear mechanism is enlarged or reduced along the axis of the reference pinion gear by a similarity ratio corresponding to the distance from the center (radius of the sphere). Furthermore, the intermediate portion of the tooth trace in the reference side gear and reference pinion gear is a single point located near the midpoint of the tooth trace, such that it is included within the range (range S) between the inclined inner end of the tooth tip of the side gear tooth and the inclined outer end of the tooth tip of the pinion gear tooth in the tooth trace direction. The intermediate portion M of the side gear 2 and pinion gear 3 coincides with the intermediate portion of the reference side gear and reference pinion gear.
[0022] As a result, as shown by the solid line in Figure 6, the tooth thickness (arc tooth thickness) at the outer end 25o (outer end than boundary B2) of the tooth root 25 of the side gear 2 is larger than when no adjustment is made to the tooth thickness on the reference pressure angle α and pitch cone PC2 (see dashed line in Figure 6). Also, as shown by the solid line in Figure 7, the tooth thickness (arc tooth thickness) at the inner end 35i (inner end than boundary B3) of the tooth root 35 of the pinion gear 3 is larger than when no adjustment is made to the tooth thickness on the reference pressure angle α and pitch cone PC3 (see dashed line in Figure 7).
[0023] Therefore, as shown in Figure 8, it is possible to ensure sufficient tooth thickness di2 at the tooth root of the side gear teeth 20 at the inner end of the side gear 2 (the end on the center O side), while increasing the tooth thickness do2 at the outer circumference of the side gear 2, as shown by the dotted line in Figure 9. Also, as shown in Figure 9, it is possible to ensure sufficient tooth thickness do3 at the tooth root of the pinion gear teeth 30 at the outer end of the pinion gear 3, while increasing the tooth thickness di3 at the tooth root of the pinion gear teeth 30 at the inner end of the pinion gear 3, as shown by the dotted line in Figure 8. As a result, it is possible to shorten the axial length of the differential gear mechanism 1 in the axial direction of the side gear 2 and reduce the diameter of the pinion gear 3, while ensuring good strength of the side gear 2 and pinion gear 3, thereby making the differential gear mechanism 1 more compact.
[0024] Incidentally, in side gear teeth 20 and pinion gear teeth 30 in which the tooth thickness on the reference pressure angle α and pitch cones PC2 and PC3 is varied in the tooth trace direction, there is a risk of tooth tip sharpening occurring in regions where the reference pressure angle α is relatively large, as shown by the dashed line in Figure 10 (Figure 10 shows pinion gear teeth 30 as an example). Also, in side gear teeth 20 and pinion gear teeth 30 in which the tooth thickness on the reference pressure angle α and pitch cones PC2 and PC3 is varied in the tooth trace direction, there is a risk of tooth root cutting occurring in regions where the reference pressure angle α is relatively small, as shown by the dashed line in Figure 11 (Figure 11 shows pinion gear teeth 30 as an example).
[0025] Furthermore, tooth tip sharpening or undercutting of the side gear teeth 20 and pinion gear teeth 30 can occur in any of the first, second, third, and fourth regions A1, A2, A3, and A4 in Figure 12. As shown in Figure 12, the first region A1 is the region on the inner side of the intermediate portion M in the tooth trace direction (the plane including the intermediate portion M and perpendicular to the tooth trace direction), and on the side of the tooth tip cone TC2 of the side gear 2 and the tooth root cone RC3 of the pinion gear 3, rather than the pitch cones PC2 and PC3 of the side gear 2 and pinion gear 3. The second region A2 is the region on the inner side of the intermediate portion M in the tooth trace direction, and on the side of the tooth root cone RC2 of the side gear 2 and the tooth tip cone TC3 of the pinion gear 3, rather than the pitch cones PC2 and PC3.
[0026] The third region A3 is the region on the outer side of the intermediate portion M in the tooth trace direction, and on the side of the tooth tip cone TC2 of the side gear 2 and the tooth root cone RC3 of the pinion gear 3, rather than the pitch cones PC2 and PC3. The fourth region A4 is the region on the inner side of the intermediate portion M in the tooth trace direction, and on the side of the tooth root cone RC2 of the side gear 2 and the tooth tip cone TC3 of the pinion gear 3, rather than the pitch cones PC2 and PC3. If tooth tip sharpening or cutting occurs on the side gear teeth 20 or pinion gear teeth 30 in at least one of the first to fourth regions A1-A4, it becomes impossible to ensure a good tooth height and meshing ratio of the side gear teeth 20 and pinion gear teeth 30.
[0027] Based on these considerations, in the differential gear mechanism 1, if, as a result of adjusting the reference pressure angle α and the tooth thickness on the pitch cone PC3 as described above, tooth tip sharpening occurs on the pinion gear tooth 30 in the second region A2 on the inner end side that does not include the inclined outer end 33o of the tooth tip 33 of the pinion gear tooth 30, the pressure angle (angle between the radius line passing through a point on the tooth surface 21 or 31 and the tangent to the tooth surface (tooth profile)) on the tooth surface 21 of each side gear tooth 20 and the tooth surface 31 of each pinion gear tooth 30 is adjusted within the range of the second region A2. In this case, the pressure angle on the tooth surface 31 included in the second region A2 of each pinion gear tooth 30 is adjusted to decrease from the pitch cone PC3 of the pinion gear 3 toward the tip cone TC3 of the pinion gear 3, as shown in Figure 13, on the inner end side of the intermediate portion M in the tooth trace direction, compared to the second reference pinion gear (see dashed line in Figure 13).
[0028] The second reference pinion gear is modified from the above-mentioned reference pinion gear by increasing the reference pressure angle α from the intermediate section M toward the inner end, as shown in Figure 3, and also increasing it from the intermediate section M toward the outer end. As shown in Figure 13, the pressure angle at the tooth surface of each pinion gear tooth on the inner end side of the second reference pinion gear is greater than the pressure angle at the tooth surface of the intermediate section M. Furthermore, the amount of pressure angle adjustment of the pinion gear 3 in the second region A2 (hereinafter referred to as "pressure angle adjustment amount") δ is set to a negative value that is zero on the pitch cone PC3, and decreases (the absolute value increases) from the pitch cone PC3 toward the tip cone TC3 of the pinion gear 3 toward the inner end side of the intermediate section M in the tooth trace direction. Note that the horizontal axis in Figure 14 shows the rotation angle of the pinion gear 3 (the same applies to Figure 15).
[0029] Furthermore, with respect to the side gear 2 which is conjugate to the pinion gear 3, the pressure angle on the tooth surface 21 included in the second region A2 of each side gear tooth 20 is adjusted so that, compared to the second reference side gear, it becomes smaller on the inner end side of the intermediate portion M in the tooth trace direction, and as it moves from the pitch cone PC2 of the side gear 2 toward the root cone RC2 of the side gear 2. The second reference side gear is adjusted so that, compared to the above-mentioned reference side gear, the reference pressure angle α increases as it moves from the intermediate portion M toward the inner end side, and also increases as it moves from the intermediate portion M toward the outer end side, as shown in Figure 3. The pressure angle on the tooth surface of each side gear tooth on the inner end side of the second reference side gear is also larger than the pressure angle on the tooth surface of the intermediate portion M. Furthermore, the pressure angle adjustment amount δ of the side gear 2 in the second region A2 is set to a negative value that becomes zero on the pitch cone PC2, as shown in Figure 14, and decreases (the absolute value increases) as it moves from the pitch cone PC2 towards the tooth root cone RC2 of the side gear 2, on the inner end side of the intermediate portion M in the tooth trace direction. As a result, it becomes possible to eliminate the sharpness of the tooth tips of the pinion gear teeth 30 in the second region A2 and to ensure good tooth height and meshing ratio of the side gear teeth 20 and pinion gear teeth 30. Note that the intermediate portion of the tooth traces of the second reference side gear and the second reference pinion gear coincides with the intermediate portion of the reference side gear and reference pinion gear, as well as the intermediate portion M of the side gear 2 and pinion gear 3.
[0030] Furthermore, as a result of adjusting the reference pressure angle α and the tooth thickness on the pitch cone PC2, for example, if tooth tip sharpening occurs on the side gear tooth 20 in the third region A3 on the outer end side that does not include the inclined inner end 23i of the tooth tip 23 of the side gear tooth 20, the pressure angle adjustment amount δ of the side gear 2 and pinion gear 3 in the third region A3 is set to a negative value that decreases (the absolute value increases) as it moves from the pitch cones PC2 and PC3 toward the tooth tip cone TC2 of the side gear 2 and the tooth root cone RC3 of the pinion gear 3, on the outer end side of the intermediate part M in the tooth trace direction, as shown in Figure 14. As a result, the pressure angle on the tooth surface 21 included in the third region A3 of each side gear tooth 20 is adjusted to decrease as it moves from the pitch cone PC2 of the side gear 2 toward the tooth root cone RC2 of the side gear 2, on the outer end side of the intermediate part M in the tooth trace direction, compared to the second reference side gear. Similarly, the pressure angle on the tooth surface 31 included in the third region A3 of each pinion gear tooth 30 is adjusted to decrease from the pitch cone PC3 of the pinion gear 3 toward the tip cone TC3 of the pinion gear 3, compared to the second reference pinion gear, on the outer end side of the intermediate portion M in the tooth trace direction. As a result, the sharpness of the tooth tips of the side gear teeth 20 in the third region A3 is eliminated, making it possible to ensure good tooth height and meshing ratio of the side gear teeth 20 and pinion gear teeth 30.
[0031] Furthermore, as a result of adjusting the reference pressure angle α and the tooth thickness on the pitch cone PC3, for example, if a cutback occurs at the tooth root of the pinion gear tooth 30 in the third region A3 on the outer end side that does not include the inner end 35i of the tooth root 35 of the pinion gear 3, the pressure angle adjustment amount δ within the range of the third region A3 becomes zero on the pitch cone PC3, as shown in Figure 15, and is set to a positive value that increases from the pitch cones PC2 and PC3 toward the tooth tip cone TC2 of the side gear 2 and the tooth root cone RC3 of the pinion gear 3 toward the outer end side of the intermediate part M in the tooth trace direction. As a result, the pressure angle on the tooth surface 31 included in the third region A3 of each pinion gear tooth 30 is adjusted to increase from the pitch cone PC3 of the pinion gear 3 toward the root cone RC3 of the pinion gear 3, compared to the second reference pinion gear (see dashed line in Figure 16), on the outer end side of the intermediate portion M in the tooth trace direction. Similarly, the pressure angle on the tooth surface 21 included in the third region A3 of each side gear tooth 20 is adjusted to increase from the pitch cone PC2 of the side gear 2 toward the tip cone TC2 of the side gear 2, compared to the second reference side gear, on the outer end side of the intermediate portion M in the tooth trace direction. As a result, it is possible to eliminate the cutting of the tooth root of the pinion gear tooth 30 in the third region A3 and ensure good tooth height and meshing ratio of the side gear tooth 20 and pinion gear tooth 30.
[0032] Furthermore, as a result of adjusting the reference pressure angle α and the tooth thickness on the pitch cone PC2, for example, if a cut-off occurs at the tooth root of the side gear tooth 20 in the second region A2 on the inner end side that does not include the inclined outer end 25o of the tooth root 25 of the side gear 2, the pressure angle adjustment amount δ in the second region A2 is set to a positive value that increases from the pitch cones PC2 and PC3 toward the tooth root cone RC2 of the side gear 2 and the tooth tip cone TC3 of the pinion gear 3, on the inner end side of the intermediate part M in the tooth trace direction, as shown in Figure 15. As a result, the pressure angle on the tooth surface 21 included in the second region A2 of each side gear tooth 20 is adjusted to increase from the pitch cone PC2 of the side gear 2 toward the tooth root cone RC2 of the side gear 2, on the inner end side of the intermediate part M in the tooth trace direction, compared to the second reference side gear. Similarly, the pressure angle on the tooth surface 31 included in the second region A2 of each pinion gear tooth 30 is adjusted to increase from the pitch cone PC3 of the pinion gear 3 toward the tip cone TC3 of the pinion gear 3, compared to the second reference pinion gear, on the inner end side of the intermediate portion M in the tooth trace direction. As a result, it is possible to eliminate the cutting down of the tooth roots of the side gear teeth 20 in the second region A2 and to ensure good tooth height and meshing ratio of the side gear teeth 20 and pinion gear teeth 30.
[0033] Furthermore, as a result of adjusting the reference pressure angle α and the tooth thickness on the pitch cone PC3, for example, if tooth tip sharpening occurs on the pinion gear tooth 30 in the fourth region A4 on the outer end side, including the inclined outer end 33o of the tooth tip 33 of the pinion gear tooth 30, then, similar to the case where tooth tip sharpening occurs on the pinion gear tooth 30 in the second region A2, the pressure angle on the tooth surface 31 included in the fourth region A4 of each pinion gear tooth 30 should be made smaller on the outer end side of the intermediate portion M in the tooth trace direction, compared to the second reference pinion gear, as it moves from the pitch cone PC3 of the pinion gear 3 towards the tooth tip cone TC3 of the pinion gear 3. In addition, the pressure angle on the tooth surface 21 included in the fourth region A4 of each side gear tooth 20 should be made smaller from the pitch cone PC2 of the side gear 2 toward the root cone RC2 of the side gear 2, compared to the second reference side gear, on the outer end side of the intermediate portion M in the tooth trace direction. As a result, the sharpness of the tooth tips of the pinion gear teeth 30 in the fourth region A4 can be eliminated, and the tooth height and meshing ratio of the side gear teeth 20 and pinion gear teeth 30 can be ensured to be good.
[0034] Furthermore, as a result of adjusting the reference pressure angle α and the tooth thickness on the pitch cone PC2, for example, if tooth tip sharpening occurs on the side gear tooth 20 in the first region A1 on the inner end side, including the inclined inner end 23i of the tooth tip 23 of the side gear tooth 20, the pressure angle on the tooth surface 21 included in the first region A1 of each side gear tooth 20 should be made smaller on the inner end side of the intermediate portion M in the tooth trace direction, compared to the second reference side gear, as it moves from the pitch cone PC2 of the side gear 2 toward the tooth tip cone TC2 of the side gear. In addition, the pressure angle on the tooth surface 31 included in the first region A1 of each pinion gear tooth 30 should be made smaller on the inner end side of the intermediate portion M in the tooth trace direction, compared to the second reference pinion gear, as it moves from the pitch cone PC3 of the pinion gear 3 toward the tooth root cone RC3 of the pinion gear 3. As a result, the sharpness of the tooth tips of the side gear teeth 20 in the first region A1 can be eliminated, making it possible to ensure good tooth height and meshing ratio of the side gear teeth 20 and pinion gear teeth 30.
[0035] Furthermore, as a result of adjusting the reference pressure angle α and the tooth thickness on the pitch cone PC2, for example, if a cutback occurs at the tooth root of the side gear tooth 20 in the fourth region A4 on the outer end side, including the inclined outer end 25o of the tooth root 25 of the side gear 2, then, similar to the case where a cutback occurs at the tooth root of the side gear tooth 20 in the second region A2, the pressure angle on the tooth surface 21 included in the fourth region A4 of each side gear tooth 20 should be increased from the pitch cone PC2 of the side gear 2 toward the tooth root cone RC2 of the side gear 2, compared to the second reference side gear, on the outer end side of the intermediate portion M in the tooth trace direction. In addition, the pressure angle on the tooth surface 31 included in the fourth region A4 of each pinion gear tooth 30 should be increased from the pitch cone PC3 of the pinion gear 3 toward the tip cone TC3 of the pinion gear 3, compared to the second reference pinion gear, on the outer end side of the intermediate portion M in the tooth trace direction. As a result, it becomes possible to eliminate the cutting down of the tooth roots of the side gear teeth 20 in the fourth region A4, and to ensure good tooth height and meshing ratio of the side gear teeth 20 and pinion gear teeth 30.
[0036] Furthermore, as a result of adjusting the reference pressure angle α and the tooth thickness on the pitch cone PC3, for example, if a cutback occurs at the tooth root of the pinion gear tooth 30 in the first region A1 on the inner end side including the inner end 35i of the tooth root 35 of the pinion gear 3, the pressure angle on the tooth surface 31 included in the first region A1 of each pinion gear tooth 30 should be increased from the pitch cone PC3 of the pinion gear 3 toward the tooth root cone RC3 of the pinion gear 3, compared to the second reference pinion gear, on the inner end side of the intermediate portion M in the tooth trace direction. In addition, the pressure angle on the tooth surface 21 included in the first region A1 of each side gear tooth 20 should be increased from the pitch cone PC2 of the side gear 2 toward the tip cone TC2 of the side gear 2, compared to the second reference side gear, on the inner end side of the intermediate portion M in the tooth trace direction. As a result, it becomes possible to eliminate the cutting of the tooth root of the pinion gear tooth 30 in the first region A1 and to ensure good tooth height and meshing ratio of the side gear tooth 20 and pinion gear tooth 30.
[0037] The intermediate portion M can be arbitrarily determined within the range S (the range between the two dashed lines in Figure 2). Furthermore, the intermediate portion M is not limited to a single point on the tooth trace, but may be secured for a predetermined length in the direction of the tooth trace. Moreover, in the differential gear mechanism 1, the tooth profiles of each side gear tooth 20 and each pinion gear tooth 30 before adjustment by the pressure angle adjustment amount δ are formed by a spherical involute curve, but are not limited to this. That is, the tooth profiles of each side gear tooth 20 and each pinion gear tooth 30 before adjustment by the pressure angle adjustment amount δ may be formed by, for example, an octoid curve, a trochoid curve, etc. Also, when designing the side gear 2 and pinion gear 3, tooth thickness adjustment may be performed after adjusting the reference pressure angle α and the pressure angle by the pressure angle adjustment amount δ.
[0038] As described above, the differential gear mechanism of the present disclosure is a differential gear mechanism (1) including a pair of bevel gears (2) each having a plurality of side gear teeth (20), and a plurality of pinion gears (3) each having a plurality of pinion gear teeth (30) that mesh with the pair of side gears (2), wherein the outer end (25o) of the tooth root (25) of the side gear (2) is inclined to be located on the side of the tooth tip cone (TC2) of the side gear (2) rather than the tooth root cone (RC2) of the side gear (2), and the tooth tip (2 3) The inner end portion (23i) of the pinion gear (3) is inclined to be located on the side of the root cone (RC2) of the side gear (2) more than the tip cone (TC2) of the side gear (2), the inner end portion (35i) of the root (35) of the pinion gear (3) is inclined to be located on the side of the tip cone (TC3) of the pinion gear (3) more than the root cone (RC3) of the pinion gear (3), and the outer end portion (33o) of the tip (33) of the pinion gear tooth (30) is located on the side of the root cone (RC3) of the pinion gear (3) more than the tip cone (TC3) of the pinion gear (3) The angle between the radius line passing through the pitch point of the side gear tooth (20) and the tangent to the tooth profile, and the angle between the radius line passing through the pitch point of the pinion gear tooth (30) and the tangent to the tooth profile, are inclined to be such that the reference pressure angle (α) increases from the middle portion (M) of the tooth trace included between the inner end (23i) of the tooth tip (23) of the side gear tooth (20) and the outer end (33o) of the tooth tip (33) of the pinion gear tooth (30) in the tooth trace direction, and increases from the middle portion (M) towards the inner end, and from the middle portion (M) towards the outer end. The tooth thickness of the side gear (2) on the pitch cone (PC2) is smaller from the intermediate portion (M) toward the inner end and larger from the intermediate portion (M) toward the outer end, compared to a reference side gear in which the intersection line between the tooth surface of the side gear tooth and the pitch cone is a straight line passing through the center of the differential gear mechanism and the reference pressure angle is constant in the tooth trace direction, and the tooth thickness of the pinion gear (3) on the pitch cone (PC3) is smaller from the intermediate portion (M) toward the inner end and larger from the intermediate portion (M) toward the outer end, and the tooth thickness of the pinion gear (3) on the pitch cone (PC3) is such that the intersection line between the tooth surface of the pinion gear tooth and the pitch cone is a straight line passing through the center,Furthermore, compared to a reference pinion gear in which the reference pressure angle is constant in the tooth trace direction, this gear's pressure angle increases from the intermediate portion (M) toward the inner end and decreases from the intermediate portion (M) toward the outer end.
[0039] In the differential gear mechanism of this disclosure, the outer end of the tooth root of the side gear, the inner end of the tooth tip of the side gear tooth, the inner end of the tooth root of the pinion gear, and the outer end of the tooth tip of the pinion gear tooth are inclined. This ensures sufficient wall thickness at the inner end of the pinion gear and shortens the axial length of the differential gear mechanism in the axial direction of the side gear. Furthermore, the reference pressure angle of the side gear tooth and the reference pressure angle of the pinion gear tooth increase from the middle of the tooth trace towards the inner end, and also increase from the middle towards the outer end. This makes it possible to increase the tooth thickness at the tooth root of the side gear teeth at the outer end (circumferential end) of the side gear compared to a reference side gear, while ensuring sufficient tooth thickness at the tooth root of the side gear teeth at the inner end (center end) of the side gear, while also increasing the tooth thickness at the tooth root of the side gear teeth at the outer end (circumferential end) of the side gear compared to a reference side gear where the reference pressure angle is constant in the tooth trace direction. Furthermore, by making the tooth thickness at the tooth root of the pinion gear teeth at the pitch cone of the pinion gear teeth at the inner end (circumferential end) of the pinion gear compared to a reference pinion gear, while ensuring sufficient tooth thickness at the tooth root of the pinion gear teeth at the outer end (circumferential end of the side gear), it is possible to increase the tooth thickness at the tooth root of the pinion gear teeth at the inner end (center end of the differential gear mechanism) of the pinion gear compared to a reference pinion gear where the reference pressure angle is constant in the tooth trace direction. As a result, while ensuring good strength for the side gear and pinion gear, it becomes possible to shorten the axial length of the differential gear mechanism in the axial direction of the side gear and reduce the diameter of the pinion gear, thereby making the differential gear mechanism more compact. The intermediate portion of the tooth trace can be arbitrarily determined within the range where the meshing between the side gear teeth and pinion gear teeth is defined only by the tip cones of the side gear and pinion gear, between the inclined inner end of the tooth tip of the side gear tooth and the inclined outer end of the tooth tip of the pinion gear tooth in the direction of the tooth trace. It may be a single point on the tooth trace, or it may be secured for a predetermined length in the direction of the tooth trace.
[0040] Furthermore, the first region (A1) is located on the inner end side of the intermediate portion (M) in the tooth trace direction, and on the side of the tip cone (TC2) of the side gear (2) and the root cone (RC3) of the pinion gear (3) rather than the pitch cones (PC2, PC3) of the side gear (2) and the pinion gear (3), and the first region (A1) is located on the inner end side of the intermediate portion (M) in the tooth trace direction, and on the side of the root cone (RC2) of the side gear (2) rather than the pitch cones (PC2, PC3) The second region (A2) on the tip cone (TC3) side of the pinion gear (3), the third region (A3) which is on the outer end side of the intermediate portion (M) in the tooth trace direction, and on the tip cone (TC2) side of the side gear (2) and the root cone (RC3) side of the pinion gear (3) rather than the pitch cones (PC2, PC3), and the inner end side of the intermediate portion (M) in the tooth trace direction, and the root of the side gear (2) rather than the pitch cones (PC2, PC3). In at least one of the cone (RC2) and the fourth region (A4) on the tip cone (TC3) side of the pinion gear (3), the pressure angle on the tooth surface (21) of the side gear tooth (20) is greater than that of a second reference side gear in which the reference pressure angle increases from the middle portion toward the inner end and also increases from the middle portion toward the outer end, compared to a second reference side gear in which the pressure angle on the tooth surface (21) of the side gear (2) is greater than that of the pitch cone (PC2, PC3) toward the root cone (RC2) side or the tip cone of the side gear (2). The pressure angle decreases as it approaches the cone (TC2) side, and the pressure angle on the tooth surface (31) of the pinion gear teeth (30) may decrease as it approaches the tip cone (TC3) side or the root cone (RC3) side of the pinion gear (3) from the pitch cone (PC2, PC3), compared to a second reference pinion gear in which the reference pressure angle increases as it approaches the inner end from the middle part and also increases as it approaches the outer end from the middle part.
[0041] This eliminates the sharpness of the tooth tips of the side gear teeth or pinion gear teeth, making it possible to ensure good tooth height and meshing ratio of the side gear teeth and pinion gear teeth.
[0042] Furthermore, the first region (A1) is located on the inner end side of the intermediate portion (M) in the tooth trace direction, and on the side of the tip cone (TC2) of the side gear (2) and the root cone (RC3) of the pinion gear (3) rather than the pitch cones (PC2, PC3) of the side gear (2) and the pinion gear (3), and the first region (A1) is located on the inner end side of the intermediate portion (M) in the tooth trace direction, and on the side of the root cone (RC2) of the side gear (2) rather than the pitch cones (PC2, PC3) The second region (A2) on the tip cone (TC3) side of the pinion gear (3), the third region (A3) which is on the outer end side of the intermediate portion (M) in the tooth trace direction, and on the tip cone (TC2) side of the side gear (2) and the root cone (RC3) side of the pinion gear (3) rather than the pitch cones (PC2, PC3), and the inner end side of the intermediate portion (M) in the tooth trace direction, and the root of the side gear (2) rather than the pitch cones (PC2, PC3). In at least one of the cone (RC2) and the fourth region (A4) on the tip cone (TC3) side of the pinion gear (3), the pressure angle on the tooth surface (21) of the side gear tooth (20) is greater than that of a second reference side gear in which the reference pressure angle increases from the middle portion toward the inner end and also increases from the middle portion toward the outer end, compared to a second reference side gear in which the pressure angle on the tooth surface (21) of the side gear (2) is greater than that of the pitch cone (PC2, PC3) toward the root cone (RC2) side or the tip cone of the side gear (2). The pressure angle may increase as it moves toward the cone (TC2) side, and the pressure angle on the tooth surface (21) of the pinion gear teeth (30) may increase as it moves from the pitch cone (PC2, PC3) toward the tip cone (TC3) side or the root cone (RC3) side of the pinion gear (3), compared to a second reference pinion gear in which the reference pressure angle increases as it moves from the intermediate portion toward the inner end side and also increases as it moves from the intermediate portion toward the outer end side.
[0043] This eliminates the need to cut down the tooth roots of the side gear teeth or pinion gear teeth, making it possible to ensure good tooth height and meshing ratio of the side gear teeth and pinion gear teeth.
[0044] The differential gear mechanism design method of the present disclosure includes a pair of side gears (2) which are bevel gears each having a plurality of side gear teeth (20), and a plurality of pinion gears (3) which are bevel gears each having a plurality of pinion gear teeth (30) and mesh with the pair of side gears (2), wherein the outer end (25o) of the tooth root (25) of the side gear (2) is inclined to be located on the tooth tip cone (TC2) side of the side gear (2) rather than the tooth root cone (RC2) of the side gear (2), and the inner end (23i) of the tooth tip (23) of the side gear A differential gear mechanism in which the side gear (2) is inclined so as to be located on the side of the root cone (RC2) of the side gear (2) more than the tip cone (TC2) of the side gear (2), the inner end (35i) of the root (35) of the pinion gear (3) is inclined so as to be located on the side of the tip cone (TC3) of the pinion gear (3) more than the root cone (RC3) of the pinion gear (3), and the outer end (33o) of the tip (33) of the pinion gear tooth (30) is inclined so as to be located on the side of the root cone (RC3) of the pinion gear (3) more than the tip cone (TC3) of the pinion gear (3) 1) A design method wherein the reference pressure angle (α), which is the angle between the radius line passing through the pitch point of the side gear tooth (20) and the tangent to the tooth profile, and the reference pressure angle (α), which is the angle between the radius line passing through the pitch point of the pinion gear tooth (30) and the tangent to the tooth profile, are increased from the middle portion (M) of the tooth trace included between the inner end (23i) of the tooth tip (23) of the side gear tooth (20) and the outer end (33o) of the tooth tip (33) of the pinion gear tooth (30) toward the inner end, and from the middle portion (M) toward the outer end The tooth thickness on the pitch cone (PC2) of the side gear (2) is made smaller as it moves from the intermediate portion (M) toward the inner end and larger as it moves from the intermediate portion (M) toward the outer end, compared to a reference side gear in which the intersection line between the tooth surface of the side gear tooth and the pitch cone is a straight line passing through the center of the differential gear mechanism and the reference pressure angle is constant in the tooth trace direction, and the tooth thickness on the pitch cone (PC3) of the pinion gear (3) is made smaller as it moves from the intermediate portion (M) toward the inner end and larger as it moves from the intermediate portion (M) toward the outer end, and the tooth thickness on the pitch cone (PC3) of the pinion gear (3) is made smaller as it moves from the tooth surface of the pinion gear tooth and the pitch cone is a straight line passing through the center,Furthermore, compared to a reference pinion gear in which the reference pressure angle is constant in the tooth trace direction, this gear increases the pressure angle from the intermediate portion (M) toward the inner end and decreases it toward the outer end.
[0045] This method makes it possible to make the differential gear mechanism more compact by shortening the axial length of the differential gear mechanism in the axial direction of the side gear and reducing the diameter of the pinion gear, while ensuring good strength of the side gear and pinion gear.
[0046] Furthermore, the first region (A1) is located on the inner end side of the intermediate portion (M) in the tooth trace direction, and on the side of the tip cone (TC2) of the side gear (2) and the root cone (RC3) of the pinion gear (3) rather than the pitch cones (PC2, PC3) of the side gear (2) and the pinion gear (3), and the first region (A1) is located on the inner end side of the intermediate portion (M) in the tooth trace direction, and on the side of the root cone (RC2) of the side gear (2) rather than the pitch cones (PC2, PC3) ) and the second region (A2) on the tip cone (TC3) side of the pinion gear (3), the third region (A3) which is on the outer end side of the intermediate portion (M) in the tooth trace direction and on the tip cone (TC2) side of the side gear (2) and the root cone (RC3) side of the pinion gear (3) rather than the pitch cone (PC2, PC3), and the inner end side of the intermediate portion (M) in the tooth trace direction and on the side gear (2) rather than the pitch cone (PC2, PC3) In at least one of the root cone (RC2) and the fourth region (A4) on the tip cone (TC3) side of the pinion gear (3), the pressure angle on the tooth surface (21) of the side gear tooth (20) is such that, compared to a second reference side gear in which the reference pressure angle increases from the middle portion toward the inner end and increases from the middle portion toward the outer end, the pitch cone (PC2, PC3) is on the root cone (RC2) side of the side gear (2) or The pressure angle may be made smaller as it moves toward the tip cone (TC2) side, and the pressure angle on the tooth surface (31) of the pinion gear tooth (30) may be made smaller as it moves from the pitch cone (PC2, PC3) toward the tip cone (TC3) side or the root cone (RC3) side of the pinion gear (3) compared to a second reference pinion gear in which the reference pressure angle increases as it moves from the middle part toward the inner end side and also increases as it moves from the middle part toward the outer end side.
[0047] Furthermore, a first region (A1) is located on the inner end side of the intermediate portion (M) in the tooth trace direction, and on the side of the tip cone (TC2) of the side gear (2) and the root cone (RC3) of the pinion gear (3) rather than the pitch cones (PC2, PC3) of the side gear (2) and the pinion gear (3), and a first region (A1) is located on the inner end side of the intermediate portion (M) in the tooth trace direction, and on the side of the root cone (RC2) of the side gear (2) rather than the pitch cones (PC2, PC3) ) and the second region (A2) on the tip cone (TC3) side of the pinion gear (3), the third region (A3) which is on the outer end side of the intermediate portion (M) in the tooth trace direction and on the tip cone (TC2) side of the side gear (2) and the root cone (RC3) side of the pinion gear (3) rather than the pitch cone (PC2, PC3), and the inner end side of the intermediate portion (M) in the tooth trace direction and on the side gear (2) rather than the pitch cone (PC2, PC3) In at least one of the root cone (RC2) and the fourth region (A4) on the tip cone (TC3) side of the pinion gear (3), the pressure angle on the tooth surface (21) of the side gear tooth (20) is such that, compared to a second reference side gear in which the reference pressure angle increases from the middle portion toward the inner end and increases from the middle portion toward the outer end, the pitch cone (PC2, PC3) is on the root cone (RC2) side of the side gear (2) or The pressure angle may be increased towards the tip cone (TC2) side, and the pressure angle on the tooth surface (21) of the pinion gear tooth (30) may be increased from the pitch cone (PC2, PC3) toward the tip cone (TC3) side or the root cone (RC3) side of the pinion gear (3) compared to a second reference pinion gear in which the reference pressure angle increases from the middle part toward the inner end side and also increases from the middle part toward the outer end side.
[0048] Furthermore, the invention disclosed herein is not limited in any way to the embodiments described above, and it goes without saying that various modifications can be made within the scope of this disclosure. Moreover, the embodiments described above are merely one specific form of the invention described in the summary of the invention, and do not limit the elements of the invention described in the summary of the invention. [Industrial applicability]
[0049] The invention disclosed herein is applicable to the manufacturing industry and the like of differential gear mechanisms comprising a pair of side gears and a plurality of pinion gears that mesh with the pair of side gears. [Explanation of symbols]
[0050] 1 Differential gear mechanism, 2 Side gear, 20 Side gear tooth, 21 Tooth surface, 23 Tooth tip, 23i Inner end, 25 Tooth root, 25o Outer end, 3 Pinion gear, 30 Pinion gear tooth, 31 Tooth surface, 33 Tooth tip, 33o Outer end, 35 Tooth root, 35i Inner end, di2, di3, do2, do3 Tooth thickness, M Intermediate part, PC2, PC3 Pitch cone, RC2, RC3 Tooth root cone, TC2, TC3 Tooth tip cone.
Claims
1. A differential gear mechanism comprising a pair of bevel gears, each having multiple side gear teeth, and a plurality of pinion gears, each having multiple pinion gear teeth, that mesh with the pair of side gears, The outer end of the tooth root of the side gear is inclined to be located on the tip cone side of the side gear rather than the tooth root cone of the side gear. The inner end of the tooth tip of the side gear tooth is inclined to be located on the tooth root cone side of the side gear, rather than on the tooth tip cone side of the side gear. The inner end of the tooth root of the pinion gear is inclined to be located on the tip cone side of the pinion gear, rather than on the root cone side of the pinion gear. The outer end of the tooth tip of the pinion gear tooth is inclined to be located on the root cone side of the pinion gear, rather than on the tip cone side of the pinion gear. The reference pressure angle, which is the angle between the radius line passing through the pitch point of the side gear tooth and the tangent to the tooth profile, and the reference pressure angle, which is the angle between the radius line passing through the pitch point of the pinion gear tooth and the tangent to the tooth profile, increases from the middle portion toward the inner end of the tooth trace included between the inner end of the tooth tip of the side gear tooth and the outer end of the tooth tip of the pinion gear tooth in the tooth trace direction, and also increases from the middle portion toward the outer end. A differential gear mechanism in which the tooth thickness of the side gear on the pitch cone decreases from the middle to the inner end and increases from the middle to the outer end, compared to a reference side gear in which the intersection line between the tooth surface of the side gear tooth and the pitch cone is a straight line passing through the center of the differential gear mechanism and the reference pressure angle is constant in the tooth trace direction, and the tooth thickness of the pinion gear on the pitch cone increases from the middle to the inner end and decreases from the middle to the outer end, compared to a reference pinion gear in which the intersection line between the tooth surface of the pinion gear tooth and the pitch cone is a straight line passing through the center and the reference pressure angle is constant in the tooth trace direction.
2. In the differential gear mechanism according to claim 1, A first region in the tooth trace direction that is on the inner end side of the intermediate portion and on the tip cone side of the side gear and the root cone side of the pinion gear, compared to the pitch cone of the side gear and the pinion gear; a second region in the tooth trace direction that is on the inner end side of the intermediate portion and on the root cone side of the side gear and the tip cone side of the pinion gear, compared to the pitch cone; a third region in the tooth trace direction that is on the outer end side of the intermediate portion and on the tip cone side of the side gear and the root cone side of the pinion gear, compared to the pitch cone; and a first region in the tooth trace direction that is on the inner end side of the intermediate portion and on the root cone side of the side gear and the tip cone side of the pinion gear, compared to the pitch cone. A differential gear mechanism in which, in at least one of the fourth region on the side, the pressure angle on the tooth surface of the side gear teeth decreases from the pitch cone toward the tooth root cone side or the tooth tip cone side of the side gear, compared to a second reference side gear in which the reference pressure angle increases from the intermediate portion toward the inner end and increases from the intermediate portion toward the outer end, and the pressure angle on the tooth surface of the pinion gear teeth decreases from the pitch cone toward the tooth tip cone side or the tooth root cone side of the pinion gear, compared to a second reference pinion gear in which the reference pressure angle increases from the intermediate portion toward the inner end and increases from the intermediate portion toward the outer end.
3. In the differential gear mechanism according to claim 1, A first region in the tooth trace direction that is on the inner end side of the intermediate portion and on the tip cone side of the side gear and the root cone side of the pinion gear, compared to the pitch cone of the side gear and the pinion gear; a second region in the tooth trace direction that is on the inner end side of the intermediate portion and on the root cone side of the side gear and the tip cone side of the pinion gear, compared to the pitch cone; a third region in the tooth trace direction that is on the outer end side of the intermediate portion and on the tip cone side of the side gear and the root cone side of the pinion gear, compared to the pitch cone; and a first region in the tooth trace direction that is on the inner end side of the intermediate portion and on the root cone side of the side gear and the tip cone side of the pinion gear, compared to the pitch cone. A differential gear mechanism in which, in at least one of the fourth region on the side, the pressure angle on the tooth surface of the side gear teeth increases from the pitch cone toward the root cone side or the tip cone side of the side gear, compared to a second reference side gear in which the reference pressure angle increases from the intermediate portion toward the inner end and increases from the intermediate portion toward the outer end, and the pressure angle on the tooth surface of the pinion gear teeth increases from the pitch cone toward the tip cone side or the root cone side of the pinion gear, compared to a second reference pinion gear in which the reference pressure angle increases from the intermediate portion toward the inner end and increases from the intermediate portion toward the outer end.
4. A differential gear mechanism design method comprising a pair of bevel gears, each having multiple side gear teeth, and a pair of bevel gears, each having multiple pinion gear teeth, that mesh with the pair of side gears, wherein the outer ends of the tooth roots of the side gears are inclined to be located on the tip cone side of the side gears more than the root cone of the side gears, the inner ends of the tooth tips of the side gear teeth are inclined to be located on the root cone side of the side gears more than the tip cone of the side gears, the inner ends of the tooth roots of the pinion gears are inclined to be located on the tip cone side of the pinion gears more than the root cone of the pinion gears, and the outer ends of the tooth tips of the pinion gear teeth are inclined to be located on the root cone side of the pinion gears more than the tip cone of the pinion gears, The reference pressure angle, which is the angle between the radius line passing through the pitch point of the side gear tooth and the tangent to the tooth profile, and the reference pressure angle, which is the angle between the radius line passing through the pitch point of the pinion gear tooth and the tangent to the tooth profile, are increased from the middle of the tooth trace included between the inner end of the tooth tip of the side gear tooth and the outer end of the tooth tip of the pinion gear tooth in the tooth trace direction, and also increased from the middle of the tooth trace towards the outer end. A method for designing a differential gear mechanism, wherein the tooth thickness of the side gear on the pitch cone is made smaller from the middle to the inner end and larger from the middle to the outer end compared to a reference side gear in which the intersection line between the tooth surface of the side gear tooth and the pitch cone is a straight line passing through the center of the differential gear mechanism and the reference pressure angle is constant in the tooth trace direction, and the tooth thickness of the pinion gear on the pitch cone is made larger from the middle to the inner end and smaller from the middle to the outer end compared to a reference pinion gear in which the intersection line between the tooth surface of the pinion gear tooth and the pitch cone is a straight line passing through the center and the reference pressure angle is constant in the tooth trace direction, and the tooth thickness of the pinion gear on the pitch cone is made larger from the middle to the inner end and smaller from the middle to the outer end compared to a reference pinion gear in which the intersection line between the tooth surface of the pinion gear tooth and the pitch cone is a straight line passing through the center and the reference pressure angle is constant in the tooth trace direction.
5. In the differential gear mechanism design method according to claim 4, A first region in the tooth trace direction that is on the inner end side of the intermediate portion and on the tip cone side of the side gear and the root cone side of the pinion gear, compared to the pitch cone of the side gear and the pinion gear; a second region in the tooth trace direction that is on the inner end side of the intermediate portion and on the root cone side of the side gear and the tip cone side of the pinion gear, compared to the pitch cone; a third region in the tooth trace direction that is on the outer end side of the intermediate portion and on the tip cone side of the side gear and the root cone side of the pinion gear, compared to the pitch cone; and a second region in the tooth trace direction that is on the inner end side of the intermediate portion and on the root cone side of the side gear and the tip cone side of the pinion gear, compared to the pitch cone. A method for designing a differential gear mechanism, wherein in at least one of the fourth region, the pressure angle on the tooth surface of the side gear teeth is made smaller from the pitch cone toward the tooth root cone side or the tooth tip cone side of the side gear compared to a second reference side gear in which the reference pressure angle increases from the intermediate portion toward the inner end and increases from the intermediate portion toward the outer end, and the pressure angle on the tooth surface of the pinion gear teeth is made smaller from the pitch cone toward the tooth tip cone side or the tooth root cone side of the pinion gear compared to a second reference pinion gear in which the reference pressure angle increases from the intermediate portion toward the inner end and increases from the intermediate portion toward the outer end,
6. In the differential gear mechanism design method according to claim 4, A first region in the tooth trace direction that is on the inner end side of the intermediate portion and on the tip cone side of the side gear and the root cone side of the pinion gear, compared to the pitch cone of the side gear and the pinion gear; a second region in the tooth trace direction that is on the inner end side of the intermediate portion and on the root cone side of the side gear and the tip cone side of the pinion gear, compared to the pitch cone; a third region in the tooth trace direction that is on the outer end side of the intermediate portion and on the tip cone side of the side gear and the root cone side of the pinion gear, compared to the pitch cone; and a second region in the tooth trace direction that is on the inner end side of the intermediate portion and on the root cone side of the side gear and the tip cone side of the pinion gear, compared to the pitch cone. A method for designing a differential gear mechanism, wherein in at least one of the fourth region, the pressure angle on the tooth surface of the side gear teeth is increased from the pitch cone toward the tooth root cone side or the tooth tip cone side of the side gear, compared to a second reference side gear in which the reference pressure angle increases from the intermediate portion toward the inner end and increases from the intermediate portion toward the outer end, and the pressure angle on the tooth surface of the pinion gear teeth is increased from the pitch cone toward the tooth tip cone side or the tooth root cone side of the pinion gear, compared to a second reference pinion gear in which the reference pressure angle increases from the intermediate portion toward the inner end and increases from the intermediate portion toward the outer end.