JP2024046476A - Connection structure between differential gear and shaft - Google Patents

Abstract

[Problem] To provide a connection structure between a differential gear and a shaft that can suppress the occurrence of unpleasant phenomena such as vehicle vibration. [Solution] A connection structure between a differential gear 20 and an output shaft 50, in which (a) one end of the output shaft 50 is connected to a side gear 34 of the differential gear 20, (b) the other end of the output shaft 50 is connected to a constant velocity joint 80 that is slidable in the direction of a first axis C1 of the output shaft 50, (c) the output shaft 50 and the side gear 34 are connected via spline fitting, and (d) a recess 54 is provided on a tooth surface 52s of a fitting tooth 52a of the output shaft 50 that is spline fitted. [Selected Figure] Figure 1

Description

The present invention relates to a connection structure between a differential gear and a shaft, which allows an appropriate difference in rotational speed between a pair of drive wheels while the vehicle is turning.

A connection structure between the differential gear and the shaft in which the differential gear and one end of the shaft are loosely fitted, that is, freely fitted, by spline fitting, and the other end of the shaft is connected to a tripod type universal joint. It has been known. For example, that is what is described in Patent Document 1. Patent Document 1 describes that in a connection structure between a differential gear and a shaft, by providing a ball and a pressing member, play in the circumferential direction (=rotational direction) in spline fitting is reduced. It is also described that the shaft can be positioned in the axial direction by making the hole in the engaging portion of the shaft into which the ball is pressed into a mortar shape.

Japanese Patent Application Publication No. 2007-303546

However, even in the connection structure between the differential gear and the shaft described in Patent Document 1, the shaft has backlash in the axial direction relative to the differential gear. Also, even when the shaft is positioned in the axial direction by a retaining ring such as a snap ring, the shaft has backlash in the axial direction relative to the differential gear.

In constant velocity joints that can slide in the axial direction, such as tripod universal joints, when the joint parts are in a state where they have a cross angle, a sliding phenomenon (relative slip phenomenon) occurs between the guide grooves on the inner peripheral surface of the outer member located on the radially outer side and the rollers on the tripods of the inner member located on the radially inner side, which induces a thrust force in the axial direction. This thrust force generates vibrations in the shaft, which are transmitted to the differential gears and drive wheels connected to both ends of the shaft, and this may cause unpleasant phenomena such as vehicle vibrations.

The present invention has been made against the background of the above circumstances, and its purpose is to provide a connection structure between a differential gear and a shaft that can suppress the occurrence of unpleasant phenomena such as vehicle vibration. be.

The gist of the present invention is a connection structure between a differential gear and a shaft, in which (a) one end of the shaft is connected to a side gear of the differential gear, and (b) the other end of the shaft is connected to a side gear of the differential gear. , connected to a constant velocity joint that is slidable in the axial direction of the shaft, (c) the shaft and the side gear are connected via spline fitting, and (d) the spline fitting of the shaft The tooth surface of the fitting portion is provided with a recess.

According to the connection structure between the differential gear and the shaft of the present invention, a recess is provided on the tooth surface of the fitting portion of the shaft that is spline-fitted. Compared to a case where a recess is not provided on the tooth surface of the fitting portion of the shaft, when a recess is provided, lubricating oil is more easily retained, and frictional force in the axial direction of the shaft is reduced. As a result, the shaft is more likely to move in the axial direction due to the reduced frictional force against the side gear of the differential gear. This relative ease of movement of the shaft with respect to the side gear in the axial direction reduces the thrust force induced in the constant velocity joint connected to the other end of the shaft. The reduction in thrust force reduces vibration in the shaft, and therefore the transmission of vibration to the differential gear and drive wheels connected to both ends of the shaft is reduced. This suppresses the occurrence of unpleasant phenomena such as vehicle vibration.

1 is a diagram illustrating a connection structure between a differential gear and a shaft according to an embodiment. FIG. 2 is a diagram illustrating the shape of the tooth surface of the fitting teeth of the output shaft spline-fitted to the differential gear, and (a) is a diagram of the side gear connecting shaft cut along cutting line II-II shown in FIG. 1. FIG. 2(b) is a cross-sectional view of the shaft portion and the small-diameter shaft portion of the output shaft, and FIG. FIG. 3 is a sectional view of a small diameter shaft portion of the output shaft.

The following describes in detail the embodiments of the present invention with reference to the drawings. Note that in the following embodiments, the drawings have been simplified or modified as appropriate, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately.

Figure 1 is a diagram illustrating the connection structure between the differential gear 20 and the output shaft 50 according to the embodiment. The output shaft 50 corresponds to the "shaft" in the present invention.

The transaxle 10 is a unit that incorporates a transmission (not shown) and a final drive gear (not shown) in the same housing 70. The final drive gear is a gear that finally reduces the power from the transmission, increases the torque, and transmits it to the drive shaft (the rotating shaft that drives a pair of drive wheels), and is integrated with the differential gear 20.

The differential gear 20 receives driving force transmitted from, for example, an output shaft of an automatic transmission, and transmits equal driving torque to the pair of output shafts 50 and 60 while allowing an appropriate difference in rotational speed.

The differential gear 20 includes a differential case 22, a pair of pinions 24 and 26, and a pair of side gear connection shafts 30 and 40. The differential case 22 is supported by a housing 70, which is a non-rotating member, via a bearing, and is rotatable around the first axis C1. Since both ends of the cylindrical pinion shaft 28 are held by the differential case 22, the pinion shaft 28 rotates integrally with the differential case 22 about the first axis C1. Each of the pair of pinions 24 and 26 is, for example, a bevel gear, and is rotatably fitted onto the outer periphery of the pinion shaft 28. A differential ring gear (not shown) is fixed to the differential case 22 with, for example, bolts. Power from the transmission is transmitted to the differential case 22 via the differential ring gear.

The side gear connecting shaft 30 comprises a cylindrical shaft portion 32 extending in the direction of the first axis C1, and a side gear 34 provided at one end of the shaft portion 32. The side gear 34 meshes with each of the pair of pinions 24, 26 and is rotatable around the first axis C1, and is, for example, a bevel gear. Engagement teeth 32a are provided on the inner peripheral surface of the shaft portion 32. The first axis C1 corresponds to the "axis" in this invention, and the side gear 34 corresponds to the "side gear" in this invention.

The output shaft 50 includes a cylindrical small-diameter shaft portion 52 provided at one end and extending in the first axis C1 direction, and a cylindrical large-diameter shaft portion 56 provided at the other end and extending in the first axis C1 direction. and. Fitting teeth 52a are provided on the outer peripheral surface of the small diameter shaft portion 52. Three guide grooves 56a extending in the first axis C1 direction are provided on the inner circumferential surface of the large diameter shaft portion 56. The fitting teeth 52a of the output shaft 50 are spline-fitted to the fitting teeth 32a provided on the shaft portion 32 of the side gear connection shaft 30. In this way, the output shaft 50 and the side gear 34 are connected via spline fitting. This spline fit is a loose or free fit. Note that the fitting teeth 52a correspond to the "fitting portion" in the present invention.

The output shaft 50 is positioned in the first axis C1 direction relative to the shaft portion 32 of the side gear connecting shaft 30 by a retaining ring 68 such as a snap ring. When positioned by the retaining ring 68, the output shaft 50 has backlash in the first axis C1 direction relative to the shaft portion 32.

One end of the wheel drive shaft 90 is connected to the output shaft 50 by a constant velocity joint 80, and the other end is connected to one of a pair of drive wheels (not shown). The constant velocity joint 80 is, for example, a tripod-type universal joint. Three rollers 86 are provided at one end of the wheel drive shaft 90 via a tripod 84. The three rollers 86 are fitted into the guide grooves 56a provided on the inner circumferential surface of the large diameter shaft portion 56 of the output shaft 50. The portion where the three rollers 86 are fitted into the guide grooves 56a is the joint portion 82 of the constant velocity joint 80. In the joint portion 82, when the first axis C1 of the large diameter shaft portion 56 of the output shaft 50 and the second axis C2 of the wheel drive shaft 90 have an intersection angle θ [deg] (≠ 0), when the output shaft 50 rotates, each roller 86 is moved in the guide groove 56a in the direction of the first axis C1. The intersection angle θ is the angle between the first axis C1 and the second axis C2. This causes a sliding phenomenon between the guide groove 56a on the inner circumferential surface of the large diameter shaft portion 56 and the rollers 86 on one end of the wheel drive shaft 90, which induces a thrust force Fth (see FIG. 2B) in the direction of the first axis C1. This thrust force Fth generates vibrations in the output shaft 50 and the wheel drive shaft 90.

The side gear connection shaft 40 includes a cylindrical shaft portion 42 extending in the first axis C1 direction, and a side gear 44 provided at one end of the shaft portion 42. The side gear 44 meshes with the pair of pinions 24 and 26, and is rotatable about the first axis C1, and is, for example, a bevel gear. Fitting teeth 40a are provided on the inner peripheral surfaces of the shaft portion 42 and the side gear 44.

The output shaft 60 has a cylindrical shaft portion provided at one end thereof and extending in the direction of the first axis C1, and mating teeth 62a are provided on the outer circumferential surface of the shaft portion. The mating teeth 62a of the output shaft 60 are spline-fitted with mating teeth 40a provided on the shaft portion 42 of the side gear connecting shaft 40 and the side gear 44. The other end of the output shaft 60 is connected to the other of the pair of drive wheels via a wheel drive shaft (not shown).

The output shaft 50 and the wheel drive shaft 90, and the output shaft 60 and the wheel drive shaft (not shown) each constitute a pair of drive shafts.

FIG. 2 is a diagram illustrating the shape of the tooth surface 52s of the fitting tooth 52a of the output shaft 50 spline-fitted to the differential gear 20, and (a) is a diagram illustrating the shape of the tooth surface 52s along the cutting line II-II shown in FIG. 2(b) is a cross-sectional view of the shaft portion 32 of the side gear connecting shaft 30 and the small diameter shaft portion 52 of the output shaft 50, cut along the cutting line XX shown in FIG. 2(a). FIG. FIG. 3 is a cross-sectional view of the shaft portion 32 of the side gear connection shaft 30 and the small diameter shaft portion 52 of the output shaft 50 that are fitted together.

As shown in FIG. 2(a), the shaft portion 32 of the side gear connecting shaft 30 and the small diameter shaft portion 52 of the output shaft 50 are spline-fitted, for example, with a square spline.

As shown in FIG. 2B, at the spline-fitted portion, the tooth surface 32s of the shaft portion 32 of the side gear connecting shaft 30 and the tooth surface 52s of the mating tooth 52a of the output shaft 50 face each other. The unevenness of the tooth surface 52s is larger than that of the tooth surface 32s. Specifically, the tooth surface 32s has no unevenness, whereas the tooth surface 52s has periodic unevenness in the first axis C1 direction. Thus, the tooth surface 52s has a plurality of periodic recesses 54 in the first axis C1 direction. The recesses 54 are formed on the tooth surface 52s by various processing methods, such as cutting processing with a hob or grinding processing with a grindstone. In addition, surface hardening treatment such as induction hardening or carburizing is performed as necessary. By introducing lubricating oil between the tooth surface 32s and the tooth surface 52s, the friction force of the tooth surface 52s in the first axis C1 direction against the tooth surface 32s is reduced. Since the tooth surface 52s has a recess 54, lubricating oil is easily retained between the tooth surface 32s and the tooth surface 52s.

According to the connection structure between the differential gear 20 and the output shaft 50 of this embodiment, (a) one end of the output shaft 50 is connected to the side gear 34 provided on the side gear connection shaft 30 of the differential gear 20, (b) the other end of the output shaft 50 is connected to a constant velocity joint 80 that can slide in the first axis C1 direction of the output shaft 50, (c) the output shaft 50 and the side gear 34 are connected via a spline fit, and (d) the tooth surface 52s of the mating teeth 52a of the output shaft 50 that is spline fitted has a plurality of recesses 54 periodically provided in the first axis C1 direction. Compared to when the recesses 54 are not provided on the tooth surface 52s of the mating teeth 52a of the output shaft 50, when the recesses 54 are provided, lubricating oil is more easily retained, and the friction force in the first axis C1 direction of the output shaft 50 is reduced. The output shaft 50 is more likely to move in the first axis C1 direction due to the reduced friction force by the amount of backlash in the first axis C1 direction that the output shaft 50 has relative to the shaft portion 32 of the side gear connecting shaft 30. The output shaft 50 is more likely to move in the first axis C1 direction relative to the shaft portion 32 of the side gear connecting shaft 30 (i.e., the output shaft 50 is more likely to expand and contract in the first axis C1 direction relative to the shaft portion 32), which reduces the thrust force Fth induced in the constant velocity joint 80 connected to the other end of the output shaft 50. The reduced thrust force Fth reduces vibration in the output shaft 50 and the wheel drive shaft 90, and therefore reduces the transmission of vibration to the differential gear 20 and the drive wheels connected to the output shaft 50 and the wheel drive shaft 90, respectively. This suppresses the occurrence of unpleasant phenomena such as vehicle vibration.

The above describes in detail an embodiment of the present invention based on the drawings, but the present invention can also be applied in other aspects.

In the above embodiment, the fitting teeth 52a of the output shaft 50 were spline-fitted to the fitting teeth 32a provided on the shaft portion 32 of the side gear connecting shaft 30, but the present invention is not limited to this. do not have. For example, when the side gear connecting shaft 30 includes only the side gear 34 having a hollow portion on the inner circumferential side, the fitting teeth 52a of the output shaft 50 are spline-fitted to fitting teeth provided on the inner circumferential surface of the side gear 34. It may also be in a mode in which it is done.

In the above embodiment, the tooth surface 52s of the fitting tooth 52a has a plurality of recesses 54 periodically provided in the first axis C1 direction, but the present invention is not limited to this. For example, a plurality of recesses 54 may be provided aperiodically on the tooth surface 52s, or a single recess 54 (one location) may be provided. Even in such an embodiment, the lubricating oil is more easily retained when the recess 54 is provided than when the recess 54 is not provided, so that the lubricating oil is easily retained in the first axis C1 direction of the output shaft 50. Frictional forces are reduced. This reduces the transmission of the thrust force Fth induced in the constant velocity joint 80 to the differential gear 20 and the drive wheels, thereby suppressing the occurrence of unpleasant phenomena such as vehicle vibration.

In the above embodiment, the constant velocity joint 80 is a tripod type universal joint provided with three rollers 86 that can slide in the first axis C1 direction, but the present invention is not limited to this. The constant velocity joint 80 in the present invention may be any type that can slide in the first axis C1 direction, and may be, for example, a universal joint in which four guide grooves 56a are provided on the inner peripheral surface of the large diameter shaft portion 56 of the output shaft 50 and the rollers 86 are fitted into each of the four guide grooves 56a, or may be a cross groove type universal joint.

In the above embodiment, the spline engagement was in the form of a square spline, but it may also be in the form of an involute spline.

The above is merely an example of the present invention, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit of the invention.

20: differential gear, 34: side gear, 50: output shaft, 52a: mating teeth, 52s: tooth surface, 54: recess, 80: constant velocity joint, C1: first axis

Claims (1)

A connection structure between a differential gear and a shaft,
one end of the shaft is connected to a side gear of the differential gear,
The other end of the shaft is connected to a constant velocity joint that is slidable in the axial direction of the shaft,
The shaft and the side gear are connected via spline fitting,
A connection structure between a differential gear and a shaft, characterized in that a recess is provided in a tooth surface of a fitting portion of the spline-fitted shaft.

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