JP2024118388A - Drive shaft - Google Patents

Abstract

To propose a drive shaft that has high strength and easily increases a torque transmission capacity, in a structure in which a fixed constant velocity universal joint and a slidable constant velocity universal joint are attached to both ends of a hollow intermediate shaft.SOLUTION: An intermediate shaft is hollow throughout; a shaft part is coaxially formed integrally with an inner race of a fixed constant velocity universal joint, with one end opening of the intermediate shaft externally fitted to the shaft part; and the shaft part is coaxially formed integrally with a tripod of a slidable constant velocity universal joint, with the other end opening of the intermediate shaft externally fitted to the shaft part.SELECTED DRAWING: Figure 1

Description

The present invention relates to a drive shaft having constant velocity universal joints attached to both ends of a hollow shaft.

A drive shaft used in the drive system of an automobile generally has a structure in which a fixed type constant velocity universal joint and a sliding type constant velocity universal joint are attached to both ends of an intermediate shaft. Recently, the intermediate shaft has been made hollow in order to reduce weight and rotational inertia (for example, see Patent Document 1).

A conventional drive shaft using an integral hollow intermediate shaft will be described in detail with reference to FIG. 4. This drive shaft 101 is a drive shaft for front wheels, and is connected to a sliding type constant velocity universal joint 103 on the inboard side and a fixed type constant velocity universal joint 104 on the outboard side. A tripod type constant velocity universal joint is shown as the sliding type constant velocity universal joint 103, and a Rzeppa type constant velocity universal joint using eight balls is shown as the fixed type constant velocity universal joint 104. The sliding type constant velocity universal joint 103 is composed of an outer joint member 105, a tripod member 106 as an inner joint member, and rollers 107, and the rollers 107 are rotatably fitted to three trunnions 108 formed on the tripod member 106. The rollers 107 are rollably accommodated in track grooves 109 formed on the outer joint member 105.

The tripod member 106 and one end of the hollow shaft 102 are fitted together by a spline 130 (which also includes serrations; the same applies below), and are fixed in the axial direction by a retaining ring 111. Both ends of a boot 120 are attached to the outer periphery of the outer joint member 105 and the outer periphery of the hollow shaft 102, sealing the inside of the joint. Grease is enclosed inside the joint as a lubricant.

On the other hand, the fixed type constant velocity universal joint 104 comprises an outer joint member 112, an inner joint member 113, balls 114, and a cage 115. Eight track grooves 116 curved in an axial direction are formed on a spherical inner peripheral surface 118 of the outer joint member 112. Track grooves 117 facing the track grooves 116 of the outer joint member 112 are formed on a spherical outer peripheral surface 119 of the inner joint member 113, and balls 114 are disposed between both track grooves 116, 117.

The balls 114 are housed in a cage 115, and the inner and outer peripheral surfaces of the cage 115 are fitted into a spherical outer peripheral surface 119 of the inner joint member (inner race) 113 and a spherical inner peripheral surface 118 of the outer joint member 112, respectively. The other end of the hollow shaft 102 is fitted into the inner joint member 113 by a spline 131 and fixed in the axial direction by a retaining ring 122. Both ends of a boot 121 are attached to the outer periphery of the outer joint member 112 and the outer periphery of the hollow shaft 102, sealing the inside of the joint.

JP 2007-315463 A

However, since a large-diameter opening is provided in the inner joint member (inner race) 113 or the tripod member 106, and the hollow shaft 102 fits into the opening, it is necessary to secure a large thickness (thick in the radial direction) around the opening for strength, and if a sufficient thickness is not secured, this part is likely to become the weakest part. In addition, due to the relationship between the opening and the peripheral wall thickness, it is difficult to reduce the weight and size of the inner race or the tripod. Furthermore, in order to increase the torque transmission capacity, it is necessary to increase the diameter of the hollow shaft 102, but this is accompanied by a large diameter of the opening, which is in conflict with securing a wall thickness around the opening, and therefore it is difficult to increase the diameter.

In view of the above-mentioned problems, the present invention aims to provide a drive shaft that has high strength and easily increases its torque transmission capacity in a structure in which a fixed type constant velocity universal joint and a sliding type constant velocity universal joint are attached to both ends of a hollow intermediate shaft.

In order to solve the above problems, in the drive shaft of the present invention, the intermediate shaft is hollow throughout, and the shaft portion is coaxially formed integrally with the inner race of the fixed type constant velocity universal joint, with one end opening of the intermediate shaft being externally fitted onto the shaft portion, and the shaft portion is coaxially formed integrally with the tripod of the sliding type constant velocity universal joint, with the other end opening of the intermediate shaft being externally fitted onto the shaft portion.

According to the present invention, the shaft portion is integrated with the inner race and the shaft portion is integrated with the tripod, and an intermediate shaft is externally fitted onto each of the shaft portions, thereby making it possible to provide a drive shaft that ensures the strength of the fitting portions while also being lightweight and allowing easy increase in torque transmission capacity.

1 is a cross-sectional view of a drive shaft according to a first embodiment of the present invention. FIG. FIG. 1 is a perspective view of a tripod according to a first embodiment of the present invention. FIG. 2 is a perspective view of an inner race according to the first embodiment of the present invention. FIG. 1 is a cross-sectional view of a conventional drive shaft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS.

Figure 1 shows a cross-sectional view of the entire drive shaft 1. The drive shaft 1 is constituted by an intermediate shaft 2 that is hollow over its entire length and is disposed in the center, with a fixed type constant velocity universal joint 3 attached to the end on the right hand side of the figure and a sliding type constant velocity universal joint 8 attached to the end on the left hand side of the figure.

The inner race 6, which is a main part of the fixed type constant velocity universal joint 3, will be described with reference to Fig. 3. Six track grooves 31 are formed in a barrel-shaped body 32, and balls 5 roll in the respective track grooves 31. Similarly, the balls 5 also roll in track grooves (not shown) provided on the inside of the outer joint member 4. The movement of each ball 5 is controlled by a cage 7. A shaft portion 30, which is a mounting shaft, is formed coaxially with the body 32. That is, the body 32 does not have a conventional fitting opening.

One end of the intermediate shaft 2 is fitted and fixed to the outside of this shaft portion 30. Specific fixing methods may include press-fitting only, adding plastic fastening processing during press-fitting, or adding various types of welding such as electron beam welding after press-fitting. Although not shown in the figure, the shaft portion 30 is provided with splines including serrations. Note that the structure other than the shaft portion 30 follows that of a conventional fixed type constant velocity universal joint. In this way, a closed die forging method is preferably used to integrally form the shaft portion coaxially with the body portion of the inner race.

Next, the tripod 10, which is a main part of the sliding type constant velocity universal joint 8, will be described with reference to Figure 2. Three legs 21 extend radially from a barrel-shaped body 22. Rollers 12 (not shown) are rotatably attached to the legs 21. The rollers 12 slide within track grooves 11 on the inner surface of the outer component member 9. A shaft portion 20, which is an attachment shaft, is formed coaxially with the body 22 and is provided with a spline including serrations. In other words, the body 22 does not have a conventional fitting opening.

The other end of the intermediate shaft 2 is fitted and fixed to the outside of this shaft portion 20. As a specific fixing method, it may be only press-fitting, or plastic fastening processing may be added during press-fitting, or various welding such as electron beam welding may be added after press-fitting. The structure other than the shaft portion 20 follows that of a conventional Zepper type constant velocity universal joint. In order to integrally form the shaft portion coaxially with the body portion of the tripod, it is preferable to adopt a closed die forging method.

As described above, the end of the intermediate shaft 2 is externally fitted onto the shaft portions 20, 30 of the inner race 6 and the tripod 10, respectively, to form the drive shaft 1. In such a drive shaft 1, since there are no openings in the inner race or the tripod as in the past, there is no concern that the periphery of the fitting portion will be the weakest part, and it is easy to reduce the weight and size of the inner race, the tripod, and the entire joint while maintaining the strength and transmission torque capacity. It is also easy to increase the fitting diameter between each shaft portion and the intermediate shaft in order to increase the transmission torque capacity. Of course, since the intermediate shaft 2 can be made hollow over the entire area, it is also possible to ensure a reduction in weight.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and even if the scope of the present invention is changed and deviated from the spirit of the present invention, the present invention still includes the changes.

Reference Signs List 1 Drive shaft 2 Intermediate shaft 3 Fixed type constant velocity universal joint 6 Inner race 8 Sliding type constant velocity universal joint 10 Tripod 20, 30 Shaft portion 22, 32 Body portion

Claims (1)

In a drive shaft in which a fixed type constant velocity universal joint and a sliding type constant velocity universal joint are attached to both ends of an intermediate shaft,
The intermediate shaft is hollow throughout;
A shaft portion is integrally formed coaxially with an inner race of the fixed type constant velocity universal joint, and one end opening of the intermediate shaft is externally fitted onto the shaft portion,
A shaft portion is integrally formed coaxially with the tripod of the sliding type constant velocity universal joint, and the other end opening of the intermediate shaft is externally fitted onto the shaft portion.
A drive shaft characterized by: