JP5312373B2 - Differential pressure relief structure of differential case in differential gear - Google Patents

Description

  The present invention provides a surface pressure relief structure for a differential case in a differential.

  3A is an enlarged view showing a meshing portion between the pinion gear 104 and the side gear 105 of the differential device 100 according to the conventional example, and FIG. 3B is a cross-sectional view taken along line AA in FIG. (C) is the figure which looked at the pinion gear 104 of (b) from the differential case 102 side.

In the differential 100 for a vehicle, when rotational torque is input to the differential case 102 via the final gear 101 and the differential case 102 rotates around the rotation axis X, the pinion shaft 103 rotates integrally with the differential case 102 to the pinion shaft. Torque is transmitted to the pinion gear 104 supported at 103, and further, the torque transmitted to the pinion gear 104 is transmitted to the side gear 105 with which the pinion gear 104 is engaged.
Then, due to the torque transmitted to the side gear 105, the side gear 105 and the axle shaft 106 connected to the side gear 105 rotate around the rotation axis X.

  For example, when the vehicle is traveling forward, the differential case 102 receives the rotational torque transmitted from the final gear 101 and rotates counterclockwise around the rotational axis X, as shown in FIG. The pinion gear 104 revolves around the rotation axis X in response to the torque transmitted from the joint surface with the pinion shaft 103, and the side gear 105 receives the torque transmitted from the meshing surface with the pinion gear 104 in response to the rotation axis X. Spins counterclockwise around.

  Here, the force (pressing force) that the pinion gear 104 receives when torque is transmitted from the joint surface with the pinion shaft 103 acts in the rotation direction of the differential case 102, and the pinion gear 104 transmits torque to the side gear 105. At this time, the force (reaction force) received from the meshing surface with the side gear 105 acts in a direction opposite to the rotation direction of the differential case 102.

As shown in FIG. 3A, the pressing force that the pinion gear 104 receives from the joint surface with the pinion shaft 103 is the same over the entire length of the joint length L1 between the pinion shaft 103 and the pinion gear 104. When the magnitude and direction of the pressing force are expressed with reference to the axis (axial center) Y of the pinion shaft 103, as shown in FIGS. 3B and 3C, a vector F1 passing through the center point C1 of the joining length L1. Can be expressed as
In FIG. 3A, the vector F1 extends toward the back side of the page.

Further, the force (reaction force) that the pinion gear 104 receives from the meshing surface with the side gear 105 extends over the entire length L2 of the meshing surface between the pinion gear 104 and the side gear 105, as shown in FIG. Although the magnitude and direction of the reaction force are the same with respect to the axis (axis) Y, as shown in FIGS. 3B and 3C, the center point of the length L2 of the meshing surface is the same. It can be represented by a vector F2 passing through C2.
In FIG. 3A, the vector F2 extends toward the front side of the page.

In the case of the differential device 100 according to the conventional example, the pinion gear 104 and the side gear 105 are gears (bevel gears) whose tooth surfaces are inclined with respect to the axis Y, as shown in FIG. Is inclined at a predetermined angle θ with respect to the axis Y of the pinion shaft 103.
Therefore, the center point C1 of the joining length L1 between the pinion shaft 103 and the pinion gear 104 and the center point C2 of the length L2 of the meshing surface between the pinion gear 104 and the side gear 105 are in the axial direction of the axis Y of the pinion shaft 103. The center point C2 is offset from the center side of the differential case 102 by ΔL.

In this case, as shown in FIG. 3B, the pressing force F1 acting in the rotation direction of the differential case 102 is outside the reaction force F2 when viewed from the rotation axis X that is the revolution axis of the pinion gear 104. Therefore, the pressing force (transmitted torque) received by the pinion gear 104 from the pinion shaft 103 acts as a moment with respect to the revolution direction of the pinion gear 104, and the pinion gear 104 is inclined with respect to the axis Y. End up.
For example, in the case of forward travel, the pinion gear 104 is inclined in a direction in which the portion surrounded by the symbol B in FIG. 3B is pressed against the inner peripheral surface 102a of the differential case 102.

In this state, when the differential rotation of the left and right axle shafts 106 and 106 occurs and the pinion gear 104 rotates around the axis Y, the contact surface 104a of the pinion gear 104 is curved by the thrust force caused by the rotation. When the pinion gear 104 is inclined with respect to the axis Y, the portion surrounded by the symbol B in the figure is strongly pressed against the inner peripheral surface 102a of the differential case 102, The surface pressure that this part receives is increased.
That is, a state in which the distribution of the surface pressure received by the differential case 102 from the contact surface 104a of the pinion gear 104 is non-uniform in the circumferential direction around the axis Y, that is, a so-called local surface pressure is generated.

  If the pinion gear 104 continues to rotate in this state, seizure, galling, abnormal wear, etc. may occur.

  In Patent Document 1, in order to prevent the pinion gear from inclining with respect to the axis Y and prevent local surface pressure, the pinion gear is provided with an extending portion extending to the differential case side, and the pinion gear is provided inside the differential case. There is disclosed a structure in which a wall portion surrounding the extension portion of the gear is provided, and the inclination of the pinion gear is prevented between the wall portion and the extension portion.

JP 2009-115141 A

  However, in the case of Patent Document 1, it is necessary to process the differential case, which increases the manufacturing cost.

  In view of this, there is a demand for a local surface pressure not to be generated on the contact surface of the differential case with the pinion gear with a simpler configuration.

The present invention includes a differential case, a shaft mounted in the differential case, a pinion gear rotatably supported on the shaft and having an outer surface formed in a spherical shape, a side gear meshing with the pinion gear, In the differential device in which the pinion gear and the side gear are each bevel gears, the portion supported by the shaft of the pinion gear extends to the side opposite to the outer surface and is supported by the shaft of the pinion gear The surface pressure relief structure in the differential device is configured such that the center point of the axial length of the shaft and the center point of the longitudinal length of the meshing tooth surface of the pinion gear and the side gear coincide with each other in the axial direction.

According to the present invention, the center point of the axial length of the portion supported by the pinion shaft of the pinion gear and the center point of the longitudinal length of the meshing tooth surface of the pinion gear and the side gear are Since they match in the axial direction, the pressing force that the pinion gear receives from the pinion shaft and the reaction force that the pinion gear receives from the meshing tooth surface with the side gear cancel each other, and no force is generated to tilt the pinion gear. .
Therefore, the outer peripheral surface of the pinion gear is pressed against the differential case with an equal force, and local surface pressure can be prevented from being generated on the contact surface of the differential case with the pinion gear.

It is sectional drawing of the differential gear concerning embodiment. It is a principal part enlarged view of FIG. It is a principal part enlarged view of the differential gear concerning a prior art example.

Embodiments of the present invention will be described below.
FIG. 1 is a cross-sectional view of a differential device 1 according to an embodiment.
FIG. 2A is an enlarged view showing a portion of one pinion gear 6 in the differential shown in FIG. 1, and an extension portion 6b is an end portion of a conventional pinion gear indicated by a dotted line in the drawing. It is a figure explaining extending only the length L3 to the axial direction of the axis | shaft Y rather than the position of this. 2B is a cross-sectional view taken along line AA in FIG. 2A, and FIG. 2C is a plan view of the pinion gear 6 of FIG. 2A viewed from the differential case 2 side.

As shown in FIG. 1, in a differential housing 3 provided at a lower portion of a transmission case (not shown), a differential case 2 of a differential device 1 is rotatably supported via a bearing 4.
A final gear 8 is fixed to the outer periphery of the differential case 2, and when rotation is input to the final gear 8, the final gear 8 and the differential case 2 rotate integrally around the rotation axis X.

The differential case 2 is formed in a hollow shape in which a pinion shaft 5, a pinion gear 6, and a side gear 7 are housed. A cylindrical shaft portion in which the bearing 4 is press-fitted into the outer periphery is formed in the differential case 2. 22 is provided extending in the left-right direction (rotation axis X direction).
The axle shafts 9 are respectively inserted in the left and right shaft portions 22 from the axial direction, and the axle shaft 9 is rotatably supported by the shaft portions 22.

  In the differential case 2, the tip end portion 9 a of the axle shaft 9 is spline-fitted into the through hole 71 of the side gear 7, and the side gear 7 and the axle shaft 9 are coupled to be rotatable about the rotation axis X. .

The differential case 2 is provided with shaft holes 2 a and 2 a penetrating in a direction orthogonal to the rotation axis X at positions symmetrical with respect to the internal space S of the differential case 2.
The shaft holes 2a and 2a are positioned on an axis Y orthogonal to the rotation axis X, and the one end 5a side and the other end 5b side of the pinion shaft 5 are inserted.
One end 5a side and the other end 5b side of the pinion shaft 5 are fixed to the differential case 2 with pins (not shown), and the pinion shaft 5 is prohibited from rotating about the axis Y.
The pinion shaft 5 is positioned between the side gears 7 and 7 in the differential case 2 and is disposed along the axis Y.

In the differential case 2, a pinion gear 6 is extrapolated and supported rotatably on the pinion shaft 5.
Two pinion gears 6 are provided at an interval in the axial direction of the axis Y, and the pinion gears 6 and 6 are arranged in a state in which the tooth portions 62 face each other. In the pinion shaft 5, the pinion gear 6 is provided such that the axis of the pinion gear 6 coincides with the axis of the pinion shaft 5.

In the differential case 2, side gears 7 are located on both sides of the pinion gear 6 in the axial direction of the rotation axis X.
The two side gears 7 are provided with an interval in the axial direction of the rotation axis X with the tooth portions 72 facing each other. The pinion gear 6 and the side gear 7 have the tooth portions 62 and 72. Are assembled in a state of meshing.

  Here, in the embodiment, the differential case 2 has a substantially spherical shape, and its internal space S is limited. Therefore, as shown in FIG. 2A, gears (bevel gears) whose outer peripheral tooth surfaces are inclined at a predetermined angle θ with respect to the axis Y are used as the pinion gear 6 and the side gear 7.

As shown in FIG. 2, a through hole 61 through which the pinion shaft 5 passes is provided at the center of the pinion gear 6, and the inner peripheral surface of the through hole 61 is joined and supported to the pinion shaft 5 over the entire circumference. Has been. A portion where the inner peripheral surface of the through hole 61 and the outer peripheral surface 5c of the pinion shaft 5 are in contact with a joint portion of the pinion gear 6 and the pinion shaft 5 (portion supported by the pinion shaft 5 of the pinion gear 6). It has become.
A tooth portion 62 is provided on the outer periphery of the pinion gear 6 so as to surround the through hole 61 when viewed from the axial direction of the axis Y.

A contact surface 6 a that contacts the contact portion 21 of the differential case 2 is provided on the surface of the pinion gear 6 that faces the differential case 2 that is positioned away from the rotation axis X.
The contact surface 6a has a substantially spherical shape protruding toward the differential case 2 side, and the axis Y side protrudes toward the differential case 2 side from the outer peripheral side.

  In the embodiment, the pinion gear 6 moves to the differential case 2 side by the thrust force that acts when the pinion gear 6 rotates around the axis Y or when the differential case 2 rotates around the rotation axis X. Yes.

Therefore, the washer 10 is located between the contact surface 6a of the pinion gear 6 and the contact portion 21 of the differential case 2, and this washer 10 receives the thrust force of the pinion gear 6. .
The washer 10 is provided by being extrapolated to the pinion shaft 5, and has a spherical shape in accordance with the shape of the contact surface 6 a of the pinion gear 6.

  The contact portion 21 of the differential case 2 slightly protrudes toward the pinion gear 6 side from the inner peripheral surface 2b of the differential case 2 along the axial direction of the axis Y. The inner peripheral surface 21a that is the surface of the contact portion 21 that faces the pinion gear 6 has a spherical shape that is recessed in a direction away from the pinion gear 6, and is aligned with the contact surface 6a of the pinion gear 6. ing.

On the inner diameter side of the pinion gear 6 (on the axis Y side relative to the tooth portion 62), an extending portion 6b extending toward the rotating shaft X (in the direction away from the contact surface 6a) is provided. The axial length L1 of the portion supported by the pinion shaft 5 is secured.
Here, the extension length L3 in the axial direction of the axis Y of the extension portion 6b is a length at which the extension portion 6b is positioned on the rotation axis X side with respect to the lower surface 62a on the inner diameter side of the tooth portion 62. A center point C1 in the axis Y direction of the axial length L1 of the portion of the pinion gear 6 supported by the pinion shaft 5 and the center of the length L2 in the longitudinal direction of the meshing tooth surfaces of the pinion gear 6 and the side gear 7 The point C2 has a length that coincides with the axial direction of the axis Y.

The inner diameter side of the pinion gear 6 according to the embodiment is longer in the direction away from the contact surface 6a than the inner diameter side of the conventional pinion gear 104 (see FIG. 3A) by the extension portion 6b. ing.
In FIGS. 2A and 2B, hatching different from the pinion gear 6 is attached to the extension portion 6 b in order to facilitate the identification of the extension portion 6 b, but the pinion gear 6 And the extending portion 6b are integrally formed.

In the case of FIG. 2A, the center point C2 passes through the center point C1 and is located on the line segment IM1 orthogonal to the axis Y. The center point C1 and the center point C2 are Match in the axial direction.
When the differential case 2 rotates about the rotation axis X, the pressing force F1 received by the pinion gear 6 from the pinion shaft 5 and the reaction force F2 received by the side gear 7 are offset to tilt the pinion gear 6 with respect to the axis Y. This is to prevent the generation of a rotational moment.

Next, the operation of the present invention will be described by taking the case of forward traveling of the vehicle as an example.
As shown in FIG. 1, when rotational torque is input to the final gear 8 from a transmission mechanism portion of an automatic transmission (not shown), the differential case 2 rotates around the rotation axis X in the direction indicated by the arrow in the figure.
Then, torque is transmitted from the pinion shaft 5 rotating integrally with the differential case 2 to the pinion gear 6, and the pinion gear 6 revolves around the rotation axis X.
Further, the torque transmitted to the pinion gear 6 is transmitted to the side gear 7 with which the pinion gear 6 meshes, and the side gear 7 rotates around the rotation axis X together with the axle shaft 9.

Here, the magnitude and direction of the force (pressing force) that the pinion gear 6 receives when torque is transmitted from the joint with the pinion shaft 5 can be expressed by the pinion shaft 5 of the pinion gear 6 in terms of the axis Y. It can be represented by a vector F1 passing through the center point C1 of the axial length L1 of the supported part (see (b) and (c) of FIG. 2).
In FIG. 2A, the vector F1 extends toward the back side of the page.

In addition, when the pinion gear 6 transmits torque to the side gear 7, the magnitude and direction of the force (reaction force) received from the meshing surface with the side gear 7 are expressed with respect to the axis Y, and the pinion gear 6 and the side gear 7 It can be represented by a vector F2 passing through the center point C2 of the length L2 in the longitudinal direction of the meshing tooth surface (see (b) and (c) of FIG. 2).
In FIG. 2A, the vector F2 extends toward the front side of the page.

  In the embodiment, the center point C1 of the axial length L1 of the portion of the pinion gear 6 supported by the pinion shaft 5 and the center point C2 of the length L2 in the longitudinal direction of the meshing tooth surfaces of the pinion gear 6 and the side gear 7 are described. And the extension length L3 of the extension portion 6b (the axial length L1 of the portion supported by the pinion shaft 5 of the pinion gear 6) is set so that these are matched in the axial direction of the axis Y ( (See (a) of FIG. 2).

  Therefore, as shown in FIG. 2B, the pressing force F1 and the reaction force F2 can be expressed by vectors F1 and F2 extending in the opposite directions from the same position in the longitudinal direction of the axis Y. Since the reaction forces F2 have the same magnitude, the pressing force F1 and the reaction force F2 received by the pinion gear 6 cancel each other, and no moment is generated to tilt the pinion gear 6 with respect to the axis Y. .

  In this state, the differential rotation of the left and right axle shafts 9 and 9 occurs, and the thrust force acting when the pinion gear 6 rotates around the axis Y or when rotating around the rotation axis X of the differential case 2 is Even if the contact surface 6 a of the pinion gear 6 is pressed against the contact portion 21 of the differential case 2, the pinion gear 6 does not tilt with respect to the axis Y, so that the contact portion 21 of the differential case 2 contacts the pinion gear 6. It is suitably prevented that the distribution of the surface pressure received from the surface 6a becomes nonuniform in the circumferential direction around the axis Y, that is, the local surface pressure.

  Here, the pinion shaft 5 in the embodiment corresponds to the shaft in the invention, and the contact surface 6a in the embodiment corresponds to the outer surface in the invention.

As described above, in the embodiment, the differential case 2 whose inner peripheral surface is spherical, the pinion shaft 5 mounted in the differential case 2, and the pinion shaft 5 are pivotally supported so that the contact surface 6a is a spherical surface. A pinion gear 6 formed in the shape of a pinion gear 6 and a side gear 7 meshing with the pinion gear 6 in the differential case 2, and the pinion gear 6 assembled with the pinion shaft 5 and the shaft centers of the pinion shaft 5 being aligned. In the differential device 1 in which the contact surface 6a which is the surface facing the contact portion 21 of the differential case 2 is slidably joined to the inner peripheral surface 21a of the contact portion 21 in the axial direction, the pinion gear 6 is An extension portion 6 b is formed by extending in the axial direction of the axis Y, and the center point C 1 of the axial length L 1 of the portion supported by the pinion shaft 5 of the pinion gear 6, and the pinion gear 6 and the side gear 7. Tooth A center point C2 in the longitudinal direction length L2 of the tooth surface meshing 2,72, and a structure in which matched in the axial direction of the shaft Y.
With this configuration, the input position of the pressing force F1 that the pinion gear 6 receives from the pinion shaft 5 and the input position of the reaction force F2 that the pinion gear 6 receives from the meshing tooth surface with the side gear 7 are in the axial direction of the axis Y. Since there is a positional relationship in which the pressing force F1 and the reaction force F2 cancel each other, no force to tilt the pinion gear 6 is generated.
Therefore, the contact surface 6a of the pinion gear 6 is pressed against the inner peripheral surface 21a of the contact portion 21 of the differential case 2 with a substantially uniform force over the entire circumference around the axis Y. The local surface pressure acting on the inner peripheral surface 21a of the 21 can be relieved, or the local surface can be prevented from being generated.
As a result, the differential rotation of the axle shaft 9 causes the pinion gear 6 to rotate around the axis Y, and the contact surface 6a of the pinion gear 6 is pushed toward the contact portion 21 of the differential case 2 by the thrust force caused by the rotation. At this time, seizure, galling, abnormal wear, and the like of the contact portion 21 due to the local surface pressure can be suitably prevented.
Further, the friction received by the contact portion 21 which is a spherical receiving portion on the differential case 2 side is reduced, and wear deterioration of the differential case can be suppressed.

Further, in the pinion gear 6, the inner diameter side, which is the portion supported by the pinion shaft 5 of the inner diameter side pinion gear 6 where the tooth portion 62 is not formed, extends in the axial direction of the axis Y over the entire circumference around the axis Y. It was set as the structure extended on the opposite side to the contact part 21 of the differential case 2. As shown in FIG.
Thereby, it can prevent suitably that the magnitude | size of the differential case 2 expands to the axial direction (direction of the axis | shaft Y) of the pinion shaft 5. FIG.

  In particular, since the extending portion 6b is formed integrally with the pinion gear 6, the manufacturing cost does not increase because the extending portion 6b is provided.

In the above-described embodiment, the center point C1 of the axial length L1 of the portion of the pinion gear 6 supported by the pinion shaft 5 and the length of the meshing tooth surfaces of the tooth portions 62 and 72 of the pinion gear 6 and the side gear 7 are as follows. In order to match the center point C2 in the length L2 in the direction in the axial direction of the axis Y, the inner diameter side that is the portion supported by the pinion shaft 5 of the pinion gear 6 is referred to as the contact portion 21 of the differential case 2 The case where the extending portion 6b is formed by extending to the opposite side has been described as an example.
The present invention is not limited to this mode. For example, in FIG. 3A, the longitudinal length of the meshing tooth surfaces of the teeth of the pinion gear 104 and the side gear 105 is extended so that the pinion gear 104 and the side gear are extended. The center point C2 in the longitudinal length L2 of the meshing tooth surfaces of the 105 tooth portions may coincide with the center point C1.
Thus, not only when the position of the center point C1 is moved to the center point C2 side in the axial direction of the axis Y as in the above embodiment, but also the position of the center point C2 is moved to the center point C1 side. Thus, by making the positions of the center point C1 and the center point C2 coincide with each other in the axial direction of the axis Y, the same operation and effect as in the case of the above-described embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 Differential device 2 Differential case 21 Contact part 21a Inner peripheral surface 22 Shaft part 3 Differential housing 4 Bearing 5 Pinion shaft 6 Pinion gear 6a Contact surface 61 Through-hole 62 Tooth part 7 Side gear 71 Through-hole 72 Tooth part 8 Final gear 9 ASKUL shaft 10 washer C1 center point C2 center point F1 pressing force F2 reaction force S internal space X rotation axis

Claims (1)

Differential case,
A shaft mounted in the differential case;
A pinion gear that is rotatably supported by the shaft and has a spherical outer surface;
A side gear meshing with the pinion gear ,
In the differential device in which the pinion gear and the side gear are bevel gears, respectively .
A portion of the pinion gear supported by the shaft extends to the opposite side of the outer surface, and a center point of the axial length of the portion of the pinion gear supported by the shaft; and A differential pressure reducing structure for a differential case in a differential gear , wherein a center point of a longitudinal length of a meshing tooth surface of a pinion gear and a side gear is matched in the axial direction .

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