Constant velocity universal joint

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a constant velocity universal joint suitable for applications that dislike rotary backlash, and is particularly suitable for an automobile steering device.

【0002】

[Conventional technology]

For example, as conceptually shown in FIG. 10, in an automobile steering device, the rotational torque applied to the steering wheel (handle) 20 is from the main shaft (main shaft) 21 of the steering column to the intermediate shaft (intermediate shaft) 22. It is input to the gear shaft (pinion shaft, etc.) 24 of the steering gear 23 via the steering gear 23, and is further converted into a linear motion by the mechanism of the steering gear 23, so that the steering force is changed to the wheel 26 via the link mechanism (knuckle, etc.) 25. Is reported as. There are many types of steering gears 23 such as a rack and pinion type, a ball screw type, and a worm roller type. Recently, the rack and pinion type has become the mainstream because of its high rigidity and light weight. The intermediate shaft 22 is arranged at an angle with respect to the main shaft 21 and the gear shaft 24, and for the purpose of absorbing impact energy at the time of collision, the main shaft 21 and the gear shaft 24 are provided via universal joints 27 and 28. Are connected to each.

【0003】

As universal joints (27, 28) used in steering devices, cardan joints (universal joints using a cross shaft) have been the mainstream in the past, but the angle of the joints has been increased (relationship with vehicle layout, etc.). In addition, in order to improve the operability of the joint part (relationship with the steering feeling, etc.), there is an increasing tendency to use a constant velocity universal joint instead of the cardan joint.

【0004】

However, the constant velocity universal joint with a general configuration has a slight clearance (internal gap) between the torque transmission ball and the ball track, and when the rotation direction changes, there is a rotational backlash (rattling in the circumferential direction) inside the joint. Is inevitable. Therefore, if the constant-velocity universal joint having a general configuration is used as it is in the steering device, there is a problem that the steering stability at the time of steering and the feeling of directness and sharpness are impaired.

【0005】

Further, in automobile applications, constant velocity universal joints have many achievements for drive shafts, and in general, constant velocity universal joints having a general configuration have design specifications that can satisfy the required characteristics for drive shafts. However, in the steering device, the torque applied to the joint is smaller than that of the drive shaft, and the rotation speed of the joint is also low. There is room for improvement from the viewpoint of reducing joint weight and manufacturing cost.

【0006】

[Problems to be Solved by the Invention]

In view of the above-mentioned problems, the applicant has developed various constant-velocity universal joints that are lightweight, compact, and low-cost, and are particularly suitable for steering devices, and have already applied for them. 7-339319, Japanese Patent Application No. 9-351010, etc.). The present invention aims to further reduce the cost of this type of constant velocity universal joint and to achieve a high angle.

【0007】

[Means for solving problems]

In order to solve the above problems, the present invention forms an outer joint member in which a curved guide groove is formed axially on a spherical inner diameter surface and a curved guide groove axially formed on a spherical outer diameter surface. The inner joint member, the guide groove of the outer joint member, and the guide groove of the inner joint member facing the guide groove are formed in cooperation with each other, and the ball track and the ball track are reduced in a wedge shape in one direction in the axial direction. It is provided with an arranged torque transmission ball, a cage for holding the torque transmission ball, and a preload applying means for closing a gap between the torque transmission ball and the ball track, and at least one of an outer joint member and an inner joint member. Provided is a constant velocity universal joint in which the surface of the guide groove is formed by plastic processing.

【0008】

By making the guide groove a molded surface by plastic working, the conventional grinding process of the guide groove becomes unnecessary, and the manufacturing cost can be reduced accordingly. In particular, by finishing the guide groove by cold forging, it is possible to secure the required accuracy of the guide groove in addition to reducing the manufacturing cost.

【0009】

The preload applying means is provided inside between the torque transmission ball and the ball track by giving a relative displacement between any two components of the outer joint member, the inner joint member, the cage, and the torque transmission ball. It closes the gap. The preload applying means is, for example, interposed between an axial gap provided between the inner joint member and the cage and between the inner joint member and the cage, and the inner joint member is offset in the offset direction of the center of the guide groove. It can be composed of an elastic member that presses and biases in the opposite direction to the above. In this case, the inner joint member receives the pressing force of the elastic member and is displaced relative to the axial direction in the anti-offset direction of the guide groove to press the torque transmission ball, and guides the torque transmission ball and the inner / outer joint member. It stops at the position where there is no internal gap between it and the groove (ball track). As a result, a constant preload in the axial direction is applied to the torque transmission ball, and rotational backlash (rattling in the circumferential direction) is eliminated.

【0010】

An undercut-free area can be provided in the guide groove of the outer joint member and the inner joint member. As a result, the joint operating angle can be increased.

【0011】

Further, the opening side region of the inner diameter surface of the outer joint member can be a cylindrical surface that matches the outer diameter surface of the cage. This facilitates the incorporation of the cage into the outer joint member.

【0012】

The constant velocity universal joint of the present invention is particularly suitable for an automobile steering device because it has no rotational backlash, is lightweight, compact, has a low cost, and can have a high operating angle.

【0013】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

【0014】

The constant velocity universal joint shown in FIGS. 1 and 2 connects the intermediate shaft (22) and the gear shaft (24) of the steering gear (23) in an angularly displaceable manner in, for example, the steering device of an automobile shown in FIG. Is.

【0015】

In the constant velocity universal joint of this embodiment, for example, an outer joint member 1 in which three curved guide grooves 1b are formed in the axial direction on a spherical inner diameter surface 1a and, for example, three on a spherical outer diameter surface 2a. A ball formed by the inner joint member 2 having the curved guide groove 2b formed in the axial direction, the guide groove 1b of the outer joint member 1 and the guide groove 2b of the inner joint member 2 facing the guide groove 2b. For example, three torque transmission balls 3 arranged on the truck, a cage 4 for holding the torque transmission balls 3, and an interposition between the outer diameter surface 2a of the inner joint member 2 and the inner diameter surface 4a of the cage 4. The elastic member 5 is provided.

【0016】

As shown in FIG. 4, in this embodiment, the outer joint member 1 has a cup shape with one end open, and is used to connect a gear shaft (for example, a pinion shaft) of a steering gear (for example, a rack and pinion type steering gear). The yoke 1c is integrally formed at the other end. By integrally forming the yoke 1c with the outer joint member 1, the number of parts can be reduced and the assembly man-hours can be reduced.

【0017】

The center O1 of the guide groove 1b is offset in the axial direction (to the inner side of the joint in this embodiment) by a predetermined distance f1 with respect to the spherical center O1'of the inner diameter surface 1a. Further, the opening side region of the inner diameter surface 1a is a cylindrical surface 1a1. The inner diameter (radius) D1 of the cylindrical surface 1a1 is set to a diameter that can include the outer diameter of the cage 4 described later {direction in FIG. 6 (a)}.

【0018】

The outer joint member 1 is preformed from a steel material by hot forging or subhot forging into a substantially predetermined shape, and the inner diameter surface 1a and the guide groove 1b are formed by cold forging. The inner diameter surface 1a is further subjected to post-processing (grinding, etc.) to ensure accuracy, but the guide groove 1b is finally finished by the above cold forging process. Therefore, in the completed state as a product, the surface of the guide groove 1b is a molded surface by cold forging. Compared with the conventional method, post-processing (grinding, etc.) of the guide groove is not required, so that the manufacturing cost of the outer joint member can be reduced.

【0019】

As shown in FIG. 5, in this embodiment, the inner joint member 2 is integrally formed with a shaft portion 2c that also serves as an intermediate shaft (22: see FIG. 10). By integrally forming the shaft portion 2c with the inner joint member 2, the number of parts can be reduced and the assembly man-hours can be reduced. The center O2 of the guide groove 2b is offset in the axial direction (to the opening side of the joint in this embodiment) by a predetermined distance f2 with respect to the spherical center O2'of the outer diameter surface 2a. The offset direction of the guide groove 2b is opposite to that of the guide groove 1b of the outer joint member 1 (the guide groove 1b is offset to the inner side and the guide groove 2b is offset to the opening side).

【0020】

The inner joint member 2 is preformed from a steel material by hot forging or subhot forging into a substantially predetermined shape, and the outer diameter surface 2a and the guide groove 2b are formed by cold forging. The outer diameter surface 2a is further subjected to post-processing (grinding, etc.) to ensure accuracy, but the guide groove 2b is finally finished by the above cold forging process. Therefore, in the completed state as a product, the surface of the guide groove 2b is a molded surface by cold forging. Compared with the conventional method, post-processing (grinding, etc.) of the guide groove is not required, so that the manufacturing cost of the inner joint member can be reduced.

【0021】

As shown in FIG. 6, in this embodiment, the cage 4 includes three window-shaped pockets 4b that house the torque transfer balls 3. The inner diameter surface 4a of the cage 4 has a cylindrical surface 4a1 on the opening side region and a conical surface 4a2 on the inner side region. The inner diameter (radius) D5 of the cylindrical surface 4a1 is set to D5> D2 with respect to the outer diameter (radius) D2 of the outer diameter surface 2a of the inner joint member 2. The inner region may be a spherical surface or a cylindrical surface. The outer diameter surface 4c of the cage 4 is a spherical surface having a radius D4. The cage 4 may be formed of a metal material, but may also be formed of a resin material in order to further reduce the weight and cost.

【0022】

In this embodiment, as the elastic member 5, a split ring that can be freely reduced or expanded in diameter as shown in FIG. 7 is adopted. The elastic member 5 is made of spring steel or the like, and has one split opening 5a and three claws 5b protruding in the axial direction. The tip of each claw portion 5b is a concave spherical spherical portion 5c having the same curvature as the outer diameter surface 2a of the inner joint member 2. The elastic member 5 may be formed of an elastic material such as resin or rubber. Further, the elastic member 5 may be an integral ring without the split opening 5a. In that case, a structure may be used to obtain the required elastic force by the elasticity of the claw portion (5b), or a structure to obtain the required elastic force by using an elastic ring such as a corrugated leaf spring, a rubber ring, or a resin ring in combination. Is also good. Further, the tip end portion (5c) of each claw portion (5b) may have a shape that makes line contact with the outer diameter surface 2a of the inner joint member 2, for example, a conical shape (conical surface portion).

【0023】

In the constant velocity universal joint of this embodiment, the cage 4 is incorporated into the inner diameter surface 1a of the outer joint member 1, the torque transmission ball 3 is incorporated into the pocket 4b of the cage 4, and the inner joint member 2 is incorporated into the cage 4. The elastic member 5 is assembled into the inner diameter surface 4a (cylindrical surface 4a1) of the cage 4 and fixed by the retaining ring 6 to prevent it from coming off. Since the opening side region of the inner diameter surface 1a of the outer joint member 1 is a cylindrical surface 1a1 that can include the outer diameter of the cage 4 {direction in FIG. 6 (a)}, the cage 4 can be easily attached to the outer joint member 1. Can be incorporated into. Further, the torque transmission ball 3 can be directly incorporated into the pocket 4b from the inner diameter side of the cage 4. Further, since the opening side region of the inner diameter surface 4a of the cage 4 is the cylindrical surface 4a1 having a radius D5 (> D2) and the center O2 of the guide groove 2b of the inner joint member 2 is offset to the opening side. With the axis of the inner joint member 2 aligned with the axes of the cage 4 and the outer joint member 1, advance the inner joint member 2 in the axial direction and incorporate it inside the inner diameter surface 4a of the cage 4 and the torque transmission ball 3. be able to. The elastic member 5 is incorporated into the inner diameter surface 4a (cylindrical surface 4a1) of the cage 4, and the outer diameter surface 2a of the inner joint member 2 is directed toward the inner side of the joint by the spherical surface portion (or conical surface portion) 5c in the axial direction. Press and urge to, and fix it with the retaining ring 6 to prevent it from coming off. Instead of the retaining ring 6, the elastic member 5 is crimped to the cylindrical surface 4a1 of the cage 4, fixed (welded, etc.), and unevenly engaged (for example, the protruding portion provided on the elastic member 5 is the cylinder of the cage 4. It may be fixed by means such as (engage with the engaging groove provided on the surface 4a1).

【0024】

When the outer joint member 1, the inner joint member 2, the torque transmission ball 3, the cage 4, and the elastic member 5 are assembled in the manner as described above, the constant velocity universal joint of this embodiment shown in FIGS. 1 and 2 is completed. To do. The center O1 of the guide groove 1b of the outer joint member 1 and the center O2 of the guide groove 2b of the inner joint member 2 are equidistant f in the axial direction with respect to the joint center surface O including the center O3 of the torque transmission ball 3. It is offset to the side (center O1 is the inner side of the joint and center O2 is the opening side of the joint). Therefore, the ball track formed by the guide groove 1b and the guide groove 2b in cooperation with each other has a wide inner portion and a shape gradually reduced in a wedge shape toward the opening side. Further, the boot 10 is attached to the outer circumference of the outer joint member 1 and the outer circumference of the shaft portion 2c of the inner joint member 2, and is tightened and fixed by the boot bands 11 and 12.

【0025】

As shown enlarged in FIG. 3, an axial gap S is provided between the inner diameter surface 4a (conical surface 4a2) of the cage 4 and the outer diameter surface 2a of the inner joint member 2 to hold the inner joint member 2. Axial relative displacement to vessel 4 (and outer joint member 1) is allowed. The axial gap S and the elastic member 5 constitute a preload applying means.

【0026】

Due to the elastic force E of the elastic member 5 interposed between the outer diameter surface 2a of the inner joint member 2 and the inner diameter surface 4a (cylindrical surface 4a1) of the cage 4, the outer diameter surface 2a of the inner joint member 2 becomes a guide groove 2b. The center O2 is pressed and urged in the direction opposite to the offset direction (opening side of the joint) (back side of the joint). The inner joint member 2 receives the pressing force E of the elastic member 5 and is displaced relative to the axial direction in the anti-offset direction of the center O2 (the inner side of the joint) to press the torque transmission ball 3 and press the torque transmission ball 3. It stops at a position where there is no internal gap between the outer / inner joint members 1 and 2 and the guide grooves 1b and 2b. As a result, a constant preload E in the axial direction is applied to the torque transmission ball 3, and rotational backlash (rattling in the circumferential direction) is eliminated.

【0027】

FIG. 8 shows another embodiment of the present invention. In this embodiment, undercut-free regions 1b1 and 2b1 are provided in the guide groove 1b of the outer joint member 1 and the guide groove 2b of the inner joint member 2, respectively. For example, the region 1b1 is provided on the inner side of the joint from the center line O1 of the guide groove 1b, and is parallel to the axis of the outer joint member 1. Further, the region 2b1 is provided on the opening side of the joint from the center line O2 of the guide groove 2b, and is parallel to the axis of the inner joint member 2. By providing the undercut-free areas 1b1 and 2b1, the operating angle of the joint can be increased.

【0028】

FIG. 9 shows another embodiment of the present invention. In this embodiment, the entire region of the inner diameter surface 4a of the cage 4 is formed on a cylindrical surface, the elastic member 5 described above is attached to the opening side region 4a1 of the inner diameter surface 4a, and the inner region 4a2 of the inner diameter surface 4a is mounted. Auxiliary ring 7 is attached to'. The auxiliary ring 7 is, for example, an integral ring having a claw portion 7b and a spherical portion (or a conical surface portion) 7c similar to the elastic member 5 described above, and is fitted in the inner region 4a2'and is prevented from coming off by the retaining ring 8. It is fixed. An axial gap S is provided between the spherical surface portion (or conical surface portion) 7c of the auxiliary ring 7 and the outer diameter surface 2a of the inner joint member 2. The axial gap S and the elastic member 5 constitute a preload applying means. Compared with the above-described embodiment, there is an advantage that the shape of the cage 4 can be simplified.

【0029】

In the steering device of the automobile shown in FIG. 10, a universal joint (28) similar to the above-described embodiment is used as the universal joint (28) for connecting the spindle (21) and the intermediate shaft (22) in an angular displacement. be able to.

【0030】

[Effect of the invention]

The present invention has the following effects.

【0031】

(1) Torque transmission Since it is equipped with a preload applying means that closes the gap between the ball and the ball track, there is no rotational backlash (rattling in the circumferential direction).

【0032】

(2) By sooting the surface of at least one of the outer joint member and the inner joint member as a molded surface by plastic working, it is possible to reduce the manufacturing cost by eliminating the need for grinding of the guide groove. In particular, by finishing the guide groove by cold forging, it is possible to secure the required accuracy of the guide groove in addition to reducing the manufacturing cost.

【0033】

(3) By providing an undercut-free area in the guide groove of the outer joint member and the inner joint member, it is possible to increase the joint operating angle.

【0034】

(4) By making the opening side region of the inner diameter surface of the outer joint member a cylindrical surface that matches the outer diameter surface of the cage, it is possible to facilitate the incorporation of the cage into the outer joint member.

【0035】

(5) The constant velocity universal joint of the present invention has no rotational backlash, is lightweight and compact, is low in cost, and can take a high operating angle. Therefore, it can be steered especially when it is used in an automobile steering device. It contributes to the improvement of stability, steering feeling, etc., and the degree of freedom in vehicle layout.

[Simple explanation of drawings]

[Figure 1]

It is a vertical cross-sectional view of the constant velocity universal joint which concerns on embodiment of this invention.

[Figure 2]

FIG. 1 is a cross-sectional view of OO in FIG. 1 (boots omitted).

[Fig. 3]

It is an enlarged vertical sectional view of a main part in FIG.

[Fig. 4]

It is a vertical cross-sectional view (partial side surface) of the outer joint member.

[Fig. 5]

It is a vertical cross-sectional view (partial side surface) of an inner joint member.

[Fig. 6]

It is a vertical cross-sectional view of the cage {Fig. 6 (a)} and a right arrow view of Fig. 6 (a) {Fig. 6 (b)}.

[Fig. 7]

It is the front view {FIG. 7 (a)} of the elastic member, and the bb sectional view {FIG. 7 (b)} of FIG. 7 (a).

[Fig. 8]

FIG. 5 is an enlarged cross-sectional view of a main part of a constant velocity universal joint according to another embodiment of the present invention.

[Fig. 9]

FIG. 5 is an enlarged cross-sectional view of a main part of a constant velocity universal joint according to another embodiment of the present invention.

[Fig. 10]

It is a figure which shows an example of the steering device of an automobile conceptually.

[Explanation of symbols]

1 Outer joint member 1a inner diameter surface 1b Guide groove 2 Inner joint member 2a outer diameter surface 2b guide groove 3 Torque transmission ball 4 cage 5 Elastic member S-axis clearance