JP4901530B2 - Constant velocity universal joint - Google Patents

Description

The present invention relates to a constant velocity universal joint, and more particularly to a fixed type constant velocity which is used in a power transmission system of an automobile or various industrial machines and allows only an operating angular displacement between two axes of a driving side and a driven side. It relates to a universal joint.

  For example, fixed type constant velocity universal joints (Zepper type constant velocity universal joints: BJ) used as coupling joints for automobile drive shafts, etc., form a curved track groove in the axial direction on the spherical inner surface. The outer joint member, the inner joint member in which a curved track groove is formed on the spherical outer diameter surface in the axial direction, the track groove of the outer joint member, and the track groove of the corresponding inner joint member cooperate with each other. A plurality of torque transmission balls arranged on a ball track formed in this manner, and a cage (cage) having a pocket for holding the torque transmission balls.

  In addition, the wheel base may be lengthened from the viewpoint of improving the collision safety of automobiles, but in order to prevent the turning radius of the vehicle from increasing accordingly, the steering angle of the front wheels is increased by increasing the angle of the fixed type constant velocity universal joint. There is a need for an increase. To meet this need for higher angles, an undercut-free type fixed constant velocity universal joint (UJ) is used in which the shape of the track groove on the opening side of the outer joint member is a straight shape parallel to the axial direction. In this type of constant velocity universal joint, both the track grooves of the outer joint member and the inner joint member have no undercut and have a structure capable of taking a large operating angle.

  In recent years, such constant velocity universal joints are required to be light and compact. In order to reduce weight and size, the thickness of each component (outer ring, inner ring, cage, etc.) in the constant velocity universal joint may be reduced (thin). Conventionally, the fitting start position of both the inner ring tooth mold (spline) and the shaft tooth mold (spline) is located on the inner side of the joint from the inlet ring chamfer (chamfered portion) of the inner ring tooth mold. There is one that is designed to be small and light (Patent Document 1).

That is, in the one described in Patent Document 1, the maximum applied force is loaded at the thick portion of the inner ring by positioning the fitting start position (maximum applied force point) on the inner side of the joint with respect to the inlet chamfer (chamfered portion). Thus, the strength of the inner ring can be improved, and the torque transmission capacity of the constant velocity universal joint can be increased, and the accompanying reduction in size and weight can be achieved. However, since the fitting start position is located on the inside of the joint, the fitting length is shortened, and the spline strength of the inner ring or the shaft may be reduced.
Japanese Patent No. 3188001

  As shown in FIG. 4, the conventional inner ring 50 has a curved track groove 52 formed in a spherical outer diameter surface in the axial direction and a chamfer 51 provided on the inlet side. The chamfer 51 is a tapered surface inclined from the outer diameter side toward the inner diameter side toward the inside in the axial direction at the inlet end. For this reason, when the thickness of the inner ring 50 is reduced, the thickness of the A portion is particularly reduced, and the A portion is inferior in strength. For this reason, when a high operating angle is taken in this constant velocity universal joint, the A portion becomes the starting point of breakage and there is a possibility that sufficient strength cannot be secured.

  In view of the above problems, the present invention can reduce the weight and size without shortening the fitting length between the inner ring and the shaft, and can maintain sufficient inner ring strength even under a high torque load. Provide fittings.

The constant velocity universal joint of the present invention includes an outer joint member in which a plurality of track grooves are formed on the inner diameter surface, and an inner joint member in which a plurality of track grooves that are paired with the track grooves of the outer joint member are formed on the outer diameter surface. Between the track groove of the outer joint member and the track groove of the inner joint member, and between the inner surface of the outer joint member and the outer surface of the inner joint member. In the constant velocity universal joint provided with a cage for holding the ball, a taper portion inclined from the outer diameter side toward the inner diameter side toward the inside in the axial direction is formed at the inlet end portion of the inner joint member. The outer edge in the axial direction of the part has a convex round shape.

In the constant velocity universal joint of the present invention, the axially outer end edge of the tapered portion at the inlet end of the inner joint member has a convex round shape. For this reason, in the inner joint member (inner ring), the outer edge in the axial direction is a stress concentration portion, but since this portion is a convex round shape, the stress in the stress concentration portion of the inner joint member can be relieved.

The radius of curvature of the outer edge of the convex round shape in the axial direction is preferably 0.3 mm to 3.0 mm, and the number of balls can be 5 to 8.

  According to the constant velocity universal joint of the present invention, the stress at the stress concentration portion of the inner ring can be relieved, so that sufficient inner ring strength can be ensured even under a high torque load even if the wall thickness of the entire inner ring is reduced (thinned). For this reason, the entire constant velocity universal joint can be reduced in weight and size.

Stress can be effectively relieved by setting the radius of curvature of the axially outer edge of the convex round shape to 0.3 mm to 3.0 mm. In addition, 5 to 8 torque transmission balls can be used. In particular, in a constant velocity universal joint having 8 torque transmission balls, strength, load capacity and durability are secured while further increasing. Compact and lightweight can be realized.

  Embodiments of the present invention will be described below with reference to FIGS.

  FIG. 3 shows a constant velocity universal joint (Zeper type constant velocity universal joint: BJ). This constant velocity universal joint (the outer joint member 3 in which the curved track groove 2 is formed in the axial direction on the spherical inner diameter surface 1 and the curved track groove 5 in the spherical outer diameter surface 4 in the axial direction. A plurality of torque transmitting balls disposed on a ball track formed by cooperation of the inner joint member 6 formed on the inner joint member 6, the track groove 2 of the outer joint member 3 and the corresponding track groove 5 of the inner joint member 6. 7 and a cage 9 having a pocket 8 for holding the torque transmission ball 7.

  The inner joint member 6 is spline-fitted by inserting the shaft 10 into the center hole (inner diameter hole), and torque can be transmitted between the two by the spline fitting. For this reason, a spline portion 12 is formed on the inner diameter surface 11 of the inner joint member (inner ring) 6.

  The shaft 10 is prevented from coming off from the inner joint member 6 by a retaining ring 13. The outer joint member 3 includes a mouth portion 3a in which the track groove 2 is formed, and a stem portion 3b protruding from the bottom wall of the mouth portion 3a.

  As shown in FIGS. 1 and 2, the inner diameter surface 11 of the inner joint member 6 has a tapered portion (chamfer) 15 formed at one end (inlet side) and a circumferential direction at the other end (back side). A notch 16 is formed. The retaining ring 13 attached to the insertion tip of the shaft 10 is fitted into the circumferential notch 16.

As shown in FIG. 2, the tapered portion 15 is inclined from the outer diameter side toward the inner diameter side toward the inside in the axial direction, and the axial outer end edge 17 has a convex round shape. The radius of curvature of the outer edge 17 in the axial direction is, for example, about 0.3 mm to 3.0 mm.

Incidentally, in the inner joint member (inner ring) 6, the portion A shown in FIG. 1 is a stress concentration portion, but in the present invention, the axial outer end edge 17 in the tapered portion 15 at the inlet end of the inner joint member 6 is provided. Since it has a convex round shape, the stress of the stress concentration portion A of the inner ring 6 can be relieved. For this reason, even if the wall thickness of the entire inner ring is reduced (thinned), sufficient inner ring strength can be ensured even under a high torque load, and the entire constant velocity universal joint can be reduced in weight and size.

  In particular, stress relaxation can be effectively achieved by setting the radius of curvature R of the outer edge 17 in the axial direction to about 0.3 mm to 3.0 mm. That is, if it is less than 0.3 mm, the radius of curvature is too small to achieve stress relaxation. Conversely, if it exceeds 3.0 mm, the function as a chamfer cannot be exhibited. Further, the inclination angle θ of the taper portion 15 is set to 25 ° to 45 °.

  By the way, in this constant velocity universal joint, five to eight torque transmission balls 7 can be used. In particular, by using a constant velocity universal joint including eight torque transmission balls 7, it is possible to achieve further compactness and weight reduction while ensuring strength, load capacity and durability.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, as a constant velocity universal joint, It may be an undercut free type fixed constant velocity universal joint (UJ) in which the track groove shape is a straight shape parallel to the axial direction.

It is sectional drawing of the inner side coupling member of the constant velocity universal joint which shows embodiment of this invention. It is a principal part expanded sectional view of the said inner side coupling member. It is sectional drawing of the said constant velocity universal joint. It is an expanded sectional view of the inner ring of the conventional constant velocity universal joint.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner diameter surface 2 Track groove 4 Outer diameter surface 5 Track groove 7 Torque transmission ball 9 Cage 15 Tapered part 17 Axial outer edge

Claims (3)

An outer joint member in which a plurality of track grooves are formed on the inner diameter surface, an inner joint member in which a plurality of track grooves paired with the track grooves of the outer joint member are formed on the outer diameter surface, and a track groove in the outer joint member; A plurality of balls that are interposed between the track grooves of the inner joint member and transmit torque, and a cage that is interposed between the inner diameter surface of the outer joint member and the outer diameter surface of the inner joint member and holds the balls. In the constant velocity universal joint provided,
A taper portion that is inclined from the outer diameter side toward the inner diameter side toward the inside in the axial direction is formed at the inlet end portion of the inner joint member, and the axial outer end edge of the taper portion has a convex round shape. Constant velocity universal joint. 2. The constant velocity universal joint according to claim 1, wherein the radius of curvature of the outer edge in the axial direction of the convex round shape is 0.3 mm to 3.0 mm.   3. The constant velocity universal joint according to claim 1, wherein the number of balls is five to eight.

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