JP6928162B2 - Fixed constant velocity universal joint - Google Patents

Description

The present invention relates to a lightweight and compact fixed constant velocity universal joint provided with a ball drop prevention mechanism.

Generally, a drive shaft of an automobile is composed of an outboard side constant velocity universal joint attached to a wheel, an inboard side constant velocity universal joint attached to a differential gear, and an intermediate shaft connecting both constant velocity universal joints. Will be done. Normally, a fixed constant velocity universal joint that can take a large operating angle but does not displace in the axial direction is used for the constant velocity universal joint on the outboard side, and the maximum operating angle is compared for the constant velocity universal joint on the inboard side. Although it is small, a sliding constant velocity universal joint that can be displaced in the axial direction while maintaining an operating angle is used.

The drive shaft of an automobile includes a drive shaft for front wheels attached to the front wheels and a drive shaft for rear wheels attached to the rear wheels. Since the fixed constant velocity universal joint on the outboard side (wheel side) of the front wheel drive shaft is attached to the front wheel which is the steering wheel, a joint having a large maximum operating angle (for example, 45 ° or more) is used. On the other hand, since the fixed constant velocity universal joint on the outboard side of the rear wheel drive shaft is attached to the rear wheel that is not steered, it is sufficient that the maximum operating angle is smaller than that of the fixed constant velocity universal joint of the front wheel drive shaft. ..

Since the maximum operating angle of the rear wheel drive shaft is as small as 20 ° or less, the track groove of the outer joint member is shortened in the zepper type fixed constant velocity universal joint using eight balls, which is different from the conventional one. A fixed constant-velocity universal joint dedicated to a drive shaft for rear wheels has been proposed, which is remarkably lightweight and compact by setting internal specifications based on the design concept (Patent Document 1).

By the way, in the case of a fixed constant velocity universal joint used for a drive shaft for front wheels, the angle at which the ball is incorporated into the track groove of the outer joint member is large, so that the operating angle is usually smaller than the operating angle at which the ball falls off from the track groove of the outer joint member. At the operating angle, the opening side end of the outer joint member and the intermediate shaft interfere with each other to act as an angle stopper and prevent the ball from falling off.

When the length of the track groove of the outer joint member of the fixed constant velocity universal joint used for the rear wheel drive shaft is shortened, when the fixed constant velocity universal joint is assembled as the drive shaft and then the drive shaft is transported. When assembling the drive shaft to the vehicle, the fixed constant velocity universal joint may take an excessive operating angle and the ball may fall out of the track groove. As a means for preventing this, a method of interfering the tip end portion of the intermediate shaft with the cup bottom of the outer joint member has been proposed (Patent Documents 2 to 4).

Japanese Unexamined Patent Publication No. 2018-155320 Japanese Unexamined Patent Publication No. 3-113124 Japanese Unexamined Patent Publication No. 2005-186041 JP-A-2010-185541

Patent Document 1 proposes a basic configuration in which the track groove of the outer joint member of a fixed constant velocity universal joint used for a drive shaft for a rear wheel is shortened and the internal specifications are set with a design concept different from the conventional one. However, we are not paying attention to the prevention of the ball from falling off.

Patent Document 2 basically regulates the operating angle in order to use a fixed constant velocity universal joint used for a drive shaft for front wheels for a drive shaft for rear wheels. The shaft end of the intermediate shaft becomes longer than necessary, which increases the weight of the intermediate shaft. Even if the cup length of the outer joint member is shortened, the effect of weight reduction is diminished.

In Patent Document 3, the bottom portion of the outer joint member that interferes with the shaft end portion of the intermediate shaft is a separate member, which causes an increase in cost. In addition, the shaft end of the intermediate shaft becomes longer than necessary. In Patent Document 4, the bottom of the outer joint member is tapered. However, as an angle regulating stopper, the taper angle and length are used to control the angle of use of the constant velocity universal joint and the prevention of the ball from falling off. , Other bottom shapes and the length of the tip of the intermediate shaft need to be controlled. In this case, since the regulation angle varies depending on the position and angle of the taper, the cost is high for dimensional control.

In the ball dropout prevention mechanism of Patent Documents 2 to 4 in which the intermediate shaft and the bottom of the outer joint member interfere with each other to serve as an angle regulation stopper, the shape of the stem portion of the outer joint member for attaching the fixed constant velocity universal joint to the wheel bearing device. Affects. It is necessary to set the wall thickness between the base of the stem portion and the bottom of the outer joint member, which affects the strength, and the wall thickness between the shoulder and the bottom of the outer joint member to appropriate dimensions. When the cavity at the bottom of the outer joint member expands in the axial and radial directions, the distance between the center position of the joint and the back face position at the base of the stem becomes longer, leading to an increase in the weight of the fixed constant velocity universal joint. .. As described above, the constant velocity universal joint provided with the ball drop prevention mechanism of Patent Documents 2 to 4 still has problems to be solved in terms of cost, weight and compactness.

In view of the above problems, an object of the present invention is to make a fixed constant velocity universal joint provided with a ball drop prevention mechanism at low cost, and to make the joint as a whole lightweight and compact.

As a result of various studies to achieve the above object, the present inventors have found an indispensable internal specification among various internal specifications of a fixed constant velocity universal joint dedicated to a lightweight and compact drive shaft for rear wheels. The present invention was derived from a new idea of fusing this internal specification with the allowable tilting space of the cage for securing the ball incorporation angle and the dimensions and arrangement of the ball dropout prevention mechanism.

As a technical means for achieving the above-mentioned object, the present invention has eight curved track grooves extending in the axial direction on the spherical inner peripheral surface, and has an opening side and a back side separated in the axial direction. An outer joint member, an inner joint member in which eight curved track grooves extending in the axial direction are formed on a spherical outer peripheral surface, a track groove of the outer joint member, and a track groove of the inner joint member corresponding thereto. It has eight balls arranged between the two and eight pockets for accommodating the balls one by one, and is in sliding contact with the spherical inner peripheral surface of the outer joint member and the spherical outer peripheral surface of the inner joint member, respectively. A cage having a spherical outer peripheral surface and a spherical inner peripheral surface is provided, and the center of curvature of the curved track groove of the outer joint member and the center of curvature of the curved track groove of the inner joint member are axially oriented with respect to the joint center. are equidistantly offset on opposite sides, weight in the fixed constant velocity universal joint having a shaft coupled in a power transmitted to the inner joint member, the fixed type constant velocity universal joint, having a ball Lumpur captive The lightweight and compact configuration has a ratio W1o / D _BALL of the axial length W1o from the joint center to the end face of the outer joint member on the opening side and the diameter D _{BALL of the ball.} It is 0.35 to 0.52, the ratio Wc / D _BALL of the width Wc of the cage to the diameter D _{BALL of the} ball is 1.63 to 1.80, and the inner bottom portion of the outer joint member. In addition, an inclination allowable space of a cage for securing a ball mounting angle is formed, and the ball dropout prevention mechanism has a cylindrical shaft portion provided at an end portion of the shaft and a recess formed in the back side bottom portion. The cylindrical shaft portion and the angle-regulating stopper surface interfere with each other at an angle smaller than the ball incorporating angle and larger than the maximum operating angle when the joint is used. On the inner side of the outer joint member in the vertical cross section including the joint axis at an angle of 0 °, the circle C _C including the spherical outer peripheral surface of the cage and the groove bottom of the curved track groove of the outer joint member are formed. It is characterized in that the end face corner portion of the cylindrical shaft portion of the shaft is arranged within the range surrounded by the including circle C _T.

With the above configuration, a fixed constant velocity universal joint equipped with a ball drop prevention mechanism can be made lightweight and compact at low cost and as a whole joint. By applying this fixed constant velocity universal joint to the drive shaft for the rear wheels of automobiles, it is possible to realize remarkable cost reduction, light weight and compactness, and also when transporting the drive shaft for the rear wheels and assembling it to the vehicle. It is possible to prevent the ball from falling off at the time and facilitate the handling work of the drive shaft for the rear wheel.

Specifically, it is preferable that the cage stopper surface is provided in the tiltable allowable space of the cage formed at the inner bottom portion of the outer joint member to secure the ball incorporating angle. As a result, the corner of the end face on the back side of the cage can be brought into contact with the stopper surface of the cage to secure the ball incorporating angle, and the axial dimension of the outer joint member can be reduced to reduce the weight.

The above-mentioned angle-regulating stopper surface has a cylindrical surface portion centered on the joint axis, and the intersection of the angle-regulating stopper surface and the cage stopper surface forms a convex corner portion in a vertical cross section including the joint axis. It is preferable to do so. As a result, the angle-regulating stopper surface that constitutes the ball dropout prevention mechanism and the cage stopper surface that secures the ball incorporation angle can be brought close to each other, and a simple and compact arrangement can be realized.

The straight line R connecting the joint center O and the end face corner of the cylindrical shaft portion of the shaft and the joint axis in the vertical cross section including the joint axis when the fixed constant velocity universal joint has an operating angle of 0 °. The angle α formed is preferably 10 ° to 17 °. As a result, a compact ball dropout prevention mechanism can be configured.

It is desirable that the recess formed in the inner bottom portion of the outer joint member has a surface formed by forging, and the angle-regulating stopper surface on the inner circumference of the recess has a surface processed by lathe. As a result, processing man-hours can be omitted and costs can be reduced.

It is preferable that boots having no bellows are mounted between the outer joint member of the fixed constant velocity universal joint and the shaft. The regulation angle of the ball dropout prevention mechanism can prevent the boots from getting caught or coming off, making the boots more compact and reducing the amount of grease filled.

According to the present invention, a fixed constant velocity universal joint provided with a ball dropout prevention mechanism can be made at low cost and lightweight and compact as a whole joint. By applying this fixed constant velocity universal joint to the drive shaft for the rear wheels of automobiles, it is possible to realize remarkable cost reduction, light weight and compactness, and also when transporting the drive shaft for the rear wheels and assembling it to the vehicle. It is possible to prevent the ball from falling off at the time and facilitate the handling work of the drive shaft for the rear wheel.

It is a partial longitudinal sectional view which applied the fixed type constant velocity universal joint which concerns on 1st Embodiment of this invention to a drive shaft for a rear wheel of an automobile. (A) is a vertical cross-sectional view of a fixed constant velocity universal joint in line ANB of (B), and (B) is a cross-sectional view of a fixed constant velocity joint in line (B) of FIG. (A). Is. (A) is a vertical cross-sectional view showing a state in which a cage is assembled on the inner circumference of the outer joint member, and (B) is a right side view of (A). It is a vertical cross-sectional view which shows the state which incorporates a ball. It is a vertical cross-sectional view which shows the state which the angle is restricted by the ball dropout prevention mechanism. It is a vertical cross-sectional view which shows the specific example which adjusted the dimension and arrangement of a ball dropout prevention mechanism. It is a vertical cross-sectional view which shows the specific example which adjusted the dimension and arrangement of a ball dropout prevention mechanism. It is a vertical cross-sectional view which shows the specific example which adjusted the dimension and arrangement of a ball dropout prevention mechanism. It is the figure which summarized the dimension and arrangement of a ball dropout prevention mechanism. It is a vertical cross-sectional view in the state of the operating angle 0 ° of the fixed constant velocity universal joint to which a boot is attached. It is a vertical cross-sectional view in a state where a fixed constant velocity universal joint to which a boot is attached takes a regulation angle of a ball dropout prevention mechanism. It is a vertical cross-sectional view of the fixed type constant velocity universal joint which concerns on 2nd Embodiment. It is a vertical cross-sectional view in a state where the fixed constant velocity universal joint shown in FIG. 12 takes a regulation angle of a ball dropout prevention mechanism. It is a vertical cross-sectional view of the modification of the fixed type constant velocity universal joint which concerns on 2nd Embodiment. FIG. 14 is a vertical cross-sectional view of the fixed constant velocity universal joint shown in FIG. 14 in a state where the ball dropout prevention mechanism has a regulated angle.

An embodiment in which the fixed constant velocity universal joint according to the present invention is applied to a drive shaft for a rear wheel of an automobile will be described with reference to FIGS. 1 to 11. FIG. 1 is a partial vertical cross-sectional view of a drive shaft for rear wheels (hatching of the cross section is omitted). In FIG. 1, the central portion of the intermediate shaft 4 is cut and shortened due to the drawing space, and the sliding constant velocity universal joint 2 side and the fixed constant velocity universal joint 3 side are shifted in parallel on the drawing. Is illustrated. As shown in the figure, the rear wheel drive shaft 1 is provided with a sliding constant velocity universal joint 2 that allows both axial displacement and angular displacement on the inboard side (right side in the figure), and is provided on the outboard side (in the figure). A fixed constant velocity universal joint 3 that allows only angular displacement is provided on the left side), and both constant velocity universal joints 2 and 3 are connected by an intermediate shaft 4. The sliding constant velocity universal joint 2 on the inboard side is connected to a differential gear (not shown), and the fixed constant velocity universal joint 3 on the outboard side is connected to a hub wheel (not shown) of a wheel bearing.

Although the sliding constant velocity universal joint 2 is not the subject of the present invention, an outline will be described below. The sliding constant velocity universal joint 2 is a so-called double offset type constant velocity universal joint, and transmits torque between the outer joint member 21, the inner joint member 22, and the outer joint member 21 and the inner joint member 22. It includes eight balls 23 and a cage 24 for holding the eight balls 23. The outer joint member 21 has a stem portion 21b integrally, and a spline 21e to be inserted into a spline hole of the differential gear is provided on the outer periphery of the inboard side end portion of the stem portion 21b. The cylindrical inner peripheral surface 21c of the outer joint member 21 is provided with eight linear track grooves 21d extending in the axial direction.

A spline hole 22c into which the intermediate shaft 4 is inserted is provided at the axial center of the inner joint member 22. The spherical outer peripheral surface 22d of the inner joint member 22 is provided with eight linear track grooves 22e extending in the axial direction. One ball 23 is incorporated between the track groove 21d of the outer joint member 21 and the track groove 22e of the inner joint member 22 facing each other in the radial direction.

The cage 24 has eight pockets 24a for holding the balls 23. The outer peripheral surface of the cage 24 is provided with a spherical outer peripheral surface portion 24b that is in sliding contact with the cylindrical inner peripheral surface 21c of the outer joint member 21, and the inner peripheral surface of the cage 24 is provided with a spherical outer peripheral surface 22d of the inner joint member 22. A spherical inner peripheral surface portion 24d that is in sliding contact with the surface is provided.

And the curvature center O _24b of the spherical outer peripheral surface 24b of the retainer 24, the center of curvature O _24d of the spherical inner peripheral surface 24d of the retainer 24 is in an equal distance in the axial direction opposite to the offset relative to the joint center O ' .. As a result, at an arbitrary operating angle, the ball 23 held by the cage 24 is always guided in the bisector plane of the operating angle, and the constant velocity between the outer joint member 21 and the inner joint member 22 is maintained. Secured.

The boot 10 is mounted on the outer circumference of the outer joint member 21 and the outer circumference of the intermediate shaft 4 connected to the inner joint member 22, and the boot 10 has a bellows portion, and both ends thereof are tightened and fixed by a boot band. .. Grease as a lubricant is sealed inside the joint covered with the boot 10.

Next, the overall configuration of the fixed constant velocity universal joint in the present embodiment will be described with reference to FIGS. 1 and 2. 2 (A) is a vertical cross-sectional view of the fixed constant velocity universal joint 3 in the line ANB of FIG. 2 (B), and FIG. 2 (B) is the line PP of FIG. 2 (A). It is a cross-sectional view in. However, in FIG. 2B, the intermediate shaft 4 is not shown. Here, the shaft in the claims means the intermediate shaft 4. As shown in FIG. 1, the fixed constant velocity universal joint 3 has eight balls 33 that transmit torque between the outer joint member 31, the inner joint member 32, and the outer joint member 31 and the inner joint member 32. And a cage 34 that holds eight balls 33, and a cage stopper surface S that secures a ball incorporation angle on the inner bottom 31 g of the outer joint member 31 and an outboard side end of the intermediate shaft 4. A ball dropout prevention mechanism M is provided at the position of the portion. In the outer joint member 31 of the present embodiment, the tiltable allowable space K of the cage 34 that secures the ball incorporating angle is provided with the cage stopper surface S. The outer joint member 31 integrally has a stem portion 31b, and the stem portion 31b is connected to a hub ring (not shown) of a wheel bearing. Boots 15 having no bellows are mounted on the outer circumference of the outer joint member 31 and the outer circumference of the intermediate shaft 4 connected to the inner joint member 32.

As shown in FIG. 2, the outer joint member 31 has a cup-shaped mouse portion 31a having one side [inboard side, right side in FIG. 2A] open in the axial direction, and a shaft from the back bottom portion 31g of the mouse portion 31a. It integrally has a stem portion 31b extending in the other direction [outboard side, left side in FIG. 2 (A)]. Eight curved track grooves 31d are formed on the spherical inner peripheral surface 31c of the mouse portion 31a at equal intervals in the circumferential direction and along the axial direction. Each track groove 31d extends to the opening side end surface 31e of the mouse portion 31a of the outer joint member 31. A spline hole 32c into which the intermediate shaft 4 is inserted is provided at the axial center of the inner joint member 32 (the spline includes serrations; the same applies hereinafter). On the spherical outer peripheral surface 32d of the inner joint member 32, eight curved track grooves 32e facing the track grooves 31d of the outer joint member 31 are formed at equal intervals in the circumferential direction and along the axial direction. ..

Eight balls 33 that transmit torque are incorporated one by one between the track groove 31d of the outer joint member 31 and the track groove 32e of the inner joint member 32. A cage 34 for holding the ball 33 is arranged between the spherical inner peripheral surface 31c of the outer joint member 31 and the spherical outer peripheral surface 32d of the inner joint member 32. The cage 34 has eight pockets 34a for holding the balls 33. The eight pockets all have the same shape and are arranged at equal intervals in the circumferential direction. The spherical outer peripheral surface 34b of the cage 34 is in sliding contact with the spherical inner peripheral surface 31c of the outer joint member 31, and the spherical inner peripheral surface 34c of the cage 34 is in sliding contact with the spherical inner peripheral surface 32d of the inner joint member 32.

The cross-sectional shape of the track groove 31d of the outer joint member 31 and the track groove 32e of the inner joint member 32 is an elliptical shape or a Gothic arch shape, whereby the track grooves 31d, 32e and the ball 33 are 30 ° to 45 °. It is a so-called angular contact that makes contact with a degree of contact angle. The cross-sectional shape of the track grooves 31d and 32e may be an arc shape, and the track grooves 31d and 32e and the ball 33 may be so-called circular contacts.

And the curvature center O _31d of the track grooves 31d of the outer joint member 31, the center of curvature O _32e of the track grooves 32e of the inner joint member 32 is offset axially opposite equal distances f1 respect to the joint center O. _{In the illustrated example, the center of curvature O 31d} of the track groove 31d of the outer joint member 31 is offset to the inboard side (opening side) with respect to the joint center O, and the center of curvature O _32e of the track groove 32e of the inner joint member 32 is , It is offset to the outboard side (back side) with respect to the joint center O. On the other hand, the center of curvature of the spherical inner peripheral surface 31c of the outer joint member 31 and the center of curvature of the spherical outer peripheral surface 32d of the inner joint member 32 coincide with the joint center O, and the spherical inner peripheral surface 31c and the spherical outer circumference both coincide with each other. The center of curvature of the spherical outer peripheral surface 34b and the spherical inner peripheral surface 34c of the cage 34 that are in sliding contact with the surface 32d also coincides with the joint center O. As a result, at an arbitrary operating angle, the ball 33 held by the cage 34 is always guided in the bisector plane of the operating angle, and the constant velocity between the outer joint member 31 and the inner joint member 32 is maintained. Secured.

The spline 4a at the outboard side end of the intermediate shaft 4 fits into the spline hole 32c of the inner joint member 32 of the fixed constant velocity universal joint 3. As a result, the intermediate shaft 4 and the inner joint member 32 are connected so that torque can be transmitted. An annular concave groove is formed at the outboard side end of the intermediate shaft 4, and a retaining ring 11 is attached to the concave groove. By engaging the retaining ring 11 with the outboard side step portion of the inner joint member 32, the intermediate shaft 4 and the inner joint member 32 are prevented from coming off.

Next, a characteristic configuration of the fixed constant velocity universal joint 3 in the present embodiment will be described. This characteristic configuration finds indispensable internal specifications among various internal specifications of fixed constant velocity universal joints dedicated to lightweight and compact rear wheel drive shafts, and holds these internal specifications and secures the ball incorporation angle. It was made possible by a new idea of fusing the tilt allowable space K (retainer stopper surface S) of the vessel and the dimensions and arrangement of the ball dropout prevention mechanism M, such as a fixed type equipped with the ball dropout prevention mechanism M. The speed universal joint 3 is a low-cost, lightweight and compact joint as a whole.

Here, an outline of the internal load, operation, and internal specifications of the fixed constant velocity universal joint will be described. In a fixed constant velocity universal joint, a load is evenly applied to each ball when the operating angle is 0 °, but when the operating angle is taken, an uneven load is applied to each ball, and the larger the operating angle, the more each ball is loaded. The difference in the load applied to the ball becomes large. Therefore, in the case of a high operating angle, the maximum load applied to each ball becomes large, so that the members in contact with the balls (outer joint member, inner joint member and cage) can withstand the maximum load received from the balls. Thick wall thickness is required. Therefore, by dedicating the fixed constant velocity universal joint to the drive shaft for the rear wheels and reducing the maximum operating angle, the maximum load applied to the ball is reduced, and the strength of each member in contact with the ball is increased, so that the load capacity is increased. The wall thickness of each member can be reduced without causing a decrease in durability. As a result, it can be made smaller than the conventional product (a zipper type constant velocity universal joint with 8 balls with a high operating angle that can be applied to both front wheel drive shafts and rear wheel drive shafts), and is a fixed constant velocity. The universal joint can be made compact in the radial direction to reduce the weight.

In addition, by making the fixed constant velocity universal joint exclusively for the drive shaft for the rear wheel and reducing the maximum operating angle to 20 ° or less (the maximum operating angle of the conventional product is about 47 °), the ball moves in the axial direction with respect to the outer joint member. Since the amount is small and the length of the contact locus between the track groove and the ball is shortened, the axial length of the track groove of the outer joint member, particularly the axial length from the joint center to the opening side end face of the outer joint member. Can be shortened. As a result, the fixed constant velocity universal joint can be made compact in the axial direction to reduce the weight.

By the way, since the constant velocity universal joint is a mass-produced product, the joint size is usually set stepwise according to the torque load capacity, and the internal specifications are set (serialized) for each size. In order to reduce the weight and size of the constant velocity universal joint of each size, if the ball diameter is reduced, the surface pressure at the contact portion between the ball and the track groove increases, which directly leads to the reduction of the torque load capacity. Therefore, when considering a design change of a constant velocity universal joint, it is common that the ball diameter is not changed unless the number of balls is increased in order to maintain the torque load capacity. Therefore, by expressing the dimensions of each member as a ratio to the ball diameter, it is possible to express the internal specifications of the constant velocity universal joint according to the torque load capacity (that is, the joint size).

Since the fixed constant velocity universal joint 3 in the present embodiment is dedicated to the drive shaft for the rear wheels, the maximum operating angle can be set smaller than that of the conventional product that can also be used for the drive shaft for the front wheels. In this fixed constant velocity universal joint 3, it is set to 20 ° or less. This makes it possible to reduce the weight and size of the fixed constant velocity universal joint 3 while maintaining the load capacity. Hereinafter, various internal specifications of the fixed constant velocity universal joint 3 will be described.

The internal specifications of the fixed constant velocity universal joint 3 in the present embodiment will be specifically described with reference to Table 1 and FIG. The conventional product in Table 1 is an 8-ball zepper-type constant velocity universal joint having the same ball diameter and a maximum operating angle of 47 °.

The definition of each parameter is as follows.
(1) (pitch circle diameter of the ball) ball PCD PCD _BALL: connecting the center of curvature center of the track groove 32e of the center of curvature of the track grooves 31d of the outer joint member 31 O _31d or the inner joint member 32 O _32e and the ball 33 The length of the line segment (the length of the line segment _{connecting the center of curvature O 31d} of the track groove 31d of the outer joint member 31 and the center of the ball 33, and the center of curvature O _32e of the track groove 32e of the inner joint member 32 and the ball 33. It is equal to the length of the line segment connecting the center, and this dimension is called PCR), which is twice the value (PCD _BALL = 2 × PCR).
(2) the inner race track length (axial length of the track grooves of the inner joint member) W _I · _TRUCK: Strictly speaking, in the axial length of the contact path between the track grooves 32e and the ball 33 of the inner joint member 32 However, in the present specification, it refers to the axial length of the spherical outer peripheral surface 32d of the inner joint member 32, that is, the axial distance between the end faces extending from both ends of the spherical outer peripheral surface 32d in the axial direction toward the inner diameter side.
(3) (axial width of the inner joint member) inner width W _I: a maximum axial dimension of the inner joint member 32, in the illustrated example, the axis between the end faces of the groove bottom cylindrical portion 32a of the inner joint member 32 Directional distance.
(4) an inner ring wall thickness (thickness in the radial direction of the inner joint member) T _I: (through the joint center O, a plane perpendicular to the joint axis) joint central plane P of the groove bottom and the spline hole 32c of the track groove 32e in This is the radial distance from the pitch circle.
(5) Spline PCD (Pitch circle diameter of spline hole of inner joint member) PCD _SPL : Diameter of meshing pitch circle between spline hole 32c of inner joint member 32 and spline 4a of intermediate shaft 4.
(6) Outer ring outer diameter D _O : The maximum outer diameter of the outer joint member 31.
(7) Joint center to outer ring opening end face length W1 _O : Axial distance between the joint center O and the opening side end face of the outer joint member 31.
(8) cage thickness T _C: is the thickness in the radial direction in the joint center plane P of the cage 34.
(9) Cage width W _C : The maximum axial dimension of the cage 34, which is the axial distance between both end faces of the cage 34 in the illustrated example.

Next, the design concept leading to the above internal specifications will be described. In the fixed constant velocity universal joint 3, the maximum load applied to each ball 33 increases as the operating angle increases. Therefore, by reducing the maximum operating angle, the maximum load applied to each ball 33 decreases. As a result, the strength of the inner joint member 32 in contact with the ball 33 is increased, so that the thickness of the inner joint member 32 in the radial direction can be reduced while maintaining the same strength and durability as the conventional product [Table 1]. See (4)]. By thinning the inner joint member 32 in this way, the pitch circle diameter of the track groove 32e of the inner joint member 32, that is, the pitch circle diameter of the balls 33 arranged in the track groove 32e can be reduced [(Table 1 ((Table 1)). 1)]. As a result, the fixed constant velocity universal joint 3 can be made compact in the radial direction to reduce the weight.

By reducing the maximum operating angle, the maximum load applied to each ball 33 is reduced, and the strength of the cage 34 in contact with the ball 33 is increased. Therefore, while maintaining the same strength and durability as the conventional product, It is possible to reduce the wall thickness of the cage 34 in the radial direction [see (8) in Table 1]. Further, from the viewpoint that the amount of movement of the ball 33 in the radial direction in the pocket 34a of the cage 34 is small, it is possible to reduce the wall thickness in the radial direction of the cage 34. As described above, while the wall thickness T _C of the cage 34, by decreasing the pitch circle diameter PCD _BALL of the ball 33, the track grooves 31d, the depth of the 32e of the outer joint member 31 and the inner joint member 32 The fixed type constant velocity universal joint 3 can be made lighter and more compact while preventing the ball 33 from riding on the track groove edge portion.

By reducing the maximum operating angle, the amount of axial movement of the ball 33 is reduced, so that the axial length of the track groove 32e of the inner joint member 32 can be shortened [see (2) in Table 1]. As a result, the inner joint member 32 can be made compact in the axial direction to reduce the weight.

By reducing the maximum operating angle, the amount of axial movement of the ball 33 with respect to the outer joint member 31 becomes shorter, so that the axial length of the track groove 31d of the outer joint member 31, particularly from the joint center O of the track groove 31d. The axial length of the opening side portion, specifically, the axial length from the joint center O to the opening side end surface 31e of the outer joint member 31 can be shortened [see (7) in Table 1]. As a result, the outer joint member 31 can be made compact in the axial direction to reduce the weight.

As described above, since there is a margin in the strength of the cage 34, the axial width of the cage 34 can be reduced while maintaining the same strength and durability as the conventional product [see (9) in Table 1]. This makes it possible to make the cage 34 compact in the axial direction and reduce the weight.

As described above, since the wall thickness TI of the inner joint member 32 in the radial direction can be reduced, the diameter of the spline hole 32c of the inner joint member 32 can be increased [see (5) in Table 1]. As a result, the diameter of the intermediate shaft 4 inserted into the spline hole 32c can be increased to increase the torsional strength. Further, as described above, since the pitch circle diameter of the ball 33 can be reduced, the outer joint member 31 can be miniaturized. Thus, the ratio D _O / PCD _SPL between the pitch circle diameter PCD _SPL of the spline hole 32c of the outer diameter D _O and the inner joint member 32 of the outer joint member 31 can be made smaller than conventional [see (6) in Table 1 ]. As a result, the weight and compactness of the fixed constant velocity universal joint 3 and the strength improvement of the intermediate shaft 4 can be achieved at the same time.

Further, as described above, by increasing the diameter of the spline hole 32c of the inner joint member 32, the pitch circle diameter of the fitting portion between the spline hole 32c of the inner joint member 32 and the spline 4a of the intermediate shaft 4 becomes larger. Therefore, the surface pressure at the contact portion between the spline teeth is reduced. As a result, the axial length of the spline hole 32c of the inner joint member 32 can be shortened while maintaining the surface pressure per spline tooth, so that the axial width of the groove bottom tubular portion 32a of the inner joint member 32 can be reduced. Can be shortened. Thus, not only to shorten the axial length of the track grooves 32e of the inner joint member 32, by shortening the axial length of the spline hole 32c, and the axial width W _I of the entire inner joint member 32 It can be shortened [see (3) in Table 1].

The above is the design concept that led to the internal specifications of the fixed constant velocity universal joint 3. Then, as a result of various studies to integrate the dimensions and arrangement of the tiltable allowable space K (retainer stopper surface S) of the cage for securing the ball incorporation angle and the ball dropout prevention mechanism M, which will be described later, the ball dropout prevention mechanism is provided. In order to make the fixed constant velocity universal joint lightweight and compact as a whole, among the various internal specifications described above, in particular, the shaft from the joint center to the opening side end face of the outer joint member in Table 1 (7). The ratio W1 _O / D _{BALL of the} direction length W1 _O to the ball diameter D _BALL is 0.35 to 0.52, and the cage width W _{C in} Table 1 (9) and the ball diameter D. the ratio W _C / D _BALL of _BALL have found the conclusion that indispensable is to be 1.63 to 1.80.

In the present embodiment, the fixed constant velocity universal joint 3 is based on the above internal specifications, and includes an inclination allowable space K (retainer stopper surface S) of a cage that secures a ball incorporation angle and a ball dropout prevention mechanism M. ing.

A method of assembling the cage 34 on the inner circumference of the outer joint member 31 will be described with reference to FIG. FIG. 3A is a vertical cross-sectional view showing a state in which the cage 34 is assembled on the inner circumference of the outer joint member 31, and FIG. 3B is a right side view of FIG. 3A. Actually, the inner joint member 32 is already assembled in the cage 34, but in FIGS. 3 (A) and 3 (B), the inner joint member 32 is not shown.

Due to the internal specifications, the ratio W1o / D _BALL of the axial length W1o from the joint center O to the opening side end surface 31e of the outer joint member 31 and the diameter D _{BALL of the} ball is 0.35 to 0.52, the outer joint member The protrusion of the spherical inner peripheral surface 31c of 31 to the inner diameter side of the opening side end portion is reduced. As a result, the inner diameter of the opening of the outer joint member 31 becomes larger. Therefore, as shown in FIG. 3B, the inner diameter D _31c at the opening side end of the spherical inner peripheral surface 31c of the outer joint member 31 is set to the cage. It can be made larger than the _{outer diameter D 34b at the} central portion in the circumferential direction of the pocket 34a when the 34 is viewed from the axial direction. In FIG. 3B, the inner diameter D _31c of the outer joint member 31 and the outer diameter D _34b of the cage 34 are shown to be substantially the same, but in reality, the inner diameter D _{31c of the outer joint member 31 is shown.} Is slightly larger than the outer diameter D _{34b of the cage 34. Further, the circumferential length L 31c} of the spherical inner peripheral surface 31c of the outer joint member 31 in the region between the adjacent track grooves 31d is shorter than _{the circumferential length L 34a} of the pocket 34a of the cage 34.

Therefore, as shown in FIG. 3A, the outer joint member 31 and the cage 34 are arranged coaxially, and the pillar portion 34d provided between the pockets 34a of the cage 34 in the circumferential direction is provided as the outer joint member. The cage 34 can be incorporated into the inner circumference of the outer joint member 31 in a state of being arranged in the track groove 31d of 31. In this way, if the cage 34 and the outer joint member 31 are assembled in a state where their axes are aligned with each other, the cage 34 whose axis is orthogonal to the inner side of the outer joint member 31 as in the conventional product. Since it is not necessary to provide a space capable of accommodating the outer joint member 31, the bottom portion 31 g on the back side can be brought closer to the opening side, the axial dimension of the outer joint member 31 can be reduced, and the assembly process can be simplified.

After assembling the cage 34 and the inner joint member 32 on the inner circumference of the outer joint member 31, the ball 33 is incorporated. This will be described with reference to FIG. 4, which shows a state in which the ball 33 is incorporated. As shown in FIG. 4, the axial center of the outer joint member 31 is arranged in the vertical direction without inserting the intermediate shaft 4 into the spline hole 32c of the inner joint member 32. Then, when the outer joint member 31 and the inner joint member 32 are bent at an angle larger than the maximum operating angle, the end face corner portion 34c on the back side of the cage 34 comes into contact with the cage stopper surface S. With the end face corner 34c in contact with the cage stopper surface S, one of the pockets 34a of the cage 34 is exposed from the outer joint member 31, that is, with the opening side end of the track groove 31d of the outer joint member 31. A gap larger than _{the diameter D BALL of the} ball 33 is formed with the pocket 34a. The operating angle at this time is called the _{ball built-in angle θ MOUNT.} In the present embodiment, the ball assembling angle θ _MOUNT of the fixed constant velocity universal joint 3 is, for example, about 48 °, which is smaller than the ball assembling angle of the conventional product (for example, about 65 °). The ball 33 is incorporated into the exposed pocket 34a, and then the remaining pockets 34a are sequentially exposed in the same manner and the ball 33 is incorporated. After incorporating all the balls 33, the operating angle is returned to around 0 °, and the intermediate shaft 4 equipped with the boot 15 (see FIG. 1) is inserted into the spline hole 32c of the inner joint member 32 to drive the rear wheel drive shaft. Assemble as 1.

In the fixed constant velocity universal joint 3 of the present embodiment, as described above, the ratio W1o / D of the axial length W1o from the joint center O to the opening side end surface 31e of the outer joint member 31 and the ball diameter D _{BALL Since the BALL} is set to 0.35 to 0.52 and the cage 34 and the outer joint member 31 are assembled in a state where their axes are aligned with each other, the back bottom of the outer joint member 31 is moved toward the opening side. Therefore, the cage stopper surface S as described above can be formed. By setting the cage stopper surface S so that the minimum required ball incorporating angle θ _MOUNT can be secured, the axial dimension of the outer joint member 31 can be reduced to reduce the weight.

Next, the ball dropout prevention mechanism M will be described with reference to FIGS. 5 to 9. FIG. 5 is a vertical cross-sectional view showing a state in which the angle is regulated by the ball dropout prevention mechanism M, and FIGS. 6 to 8 are vertical cross-sectional views showing specific examples in which the dimensions and arrangement of the ball dropout prevention mechanism M are adjusted. Yes, FIG. 9 is a diagram summarizing the dimensions and arrangement of the ball dropout prevention mechanism M.

In the present embodiment, as described above, the fixed constant velocity universal joint 3 has a maximum operating angle of, for example, 20 ° or less, and a ball incorporating angle θ _MOUNT of, for example, about 48 °. After assembling the fixed constant velocity universal joint 3 as the rear wheel drive shaft 1, when transporting the rear wheel drive shaft 1 or when assembling the rear wheel drive shaft 1 to the vehicle, the fixed constant velocity universal joint 3 The fixed constant velocity universal joint 3 in the present embodiment is provided with a ball dropout prevention mechanism M in order to prevent the ball 33 from falling out of the track groove due to an excessive operating angle up to the ball incorporation angle θ _MOUNT. ..

As shown in FIG. 5, the ball dropout prevention mechanism M is formed in the cylindrical shaft portion 4b formed at the outboard side end portion of the intermediate shaft 4 and the recess 31h formed in the inner bottom portion 31g of the outer joint member 31. It is composed of a peripheral angle regulation stopper surface 31i. The angle regulation stopper surface 31i has a cylindrical surface portion 31 m centered on the joint axis. The end face angle portion 4c of the cylindrical shaft portion 4b and the angle regulation stopper surface 31i _{interfere with each other at an angle smaller than the ball incorporating angle θ MOUNT and} larger than the maximum operating angle when the joint is used, and regulate the angle. This regulation angle θ _LIMIT is, for example, 25 °. In this way, since the ball dropout prevention mechanism M regulates the regulation angle, the ball 33 is prevented from falling off from the opening side end of the track groove 31d of the outer joint member 31. As a result, the ball 33 can be prevented from falling off during transportation of the rear wheel drive shaft 1 or when assembled to the vehicle, and the handling work of the rear wheel drive shaft 1 can be facilitated.

The portion 31j where the angle regulation stopper surface 31i and the cage stopper surface S intersect forms a convex corner portion in the vertical cross section including the joint axis NN, and the angle regulation stopper surface 31i and the cage stopper surface S come close to each other. It realizes a simple and compact layout. On the machined surface, the rough shape of the cage stopper surface S and the recess 31h is formed by forging the outer joint member 31, and the portion that avoids the interference of the angle regulating stopper surface 31i and the recess 31h is appropriately formed by turning. NS. The recess 31h formed in the inner bottom portion 31g of the outer joint member 31 has a surface formed by forging, and the angle-regulating stopper surface 31i on the inner circumference of the recess 31h has a surface that has been turned. This is preferable because man-hours can be omitted and costs can be reduced.

Next, several specific examples in which the dimensions and arrangement of the ball dropout prevention mechanism M have been adjusted will be described with reference to FIGS. 6 to 8. The ratio W1o / D _BALL of the axial length W1o from the center of the joint to the end face on the opening side of the outer joint member and the diameter D _{BALL of the} ball is 0.35 to 0.52, and the width Wc of the cage and the width of the ball. fusion and internal specification the ratio Wc / D _bALL of the diameter D _bALL is 1.63 to 1.80, the dimension of the inclined allowable space K (the retainer stop surfaces S) and the ball captive M of the cage, the arrangement In order to make the fixed constant velocity universal joint equipped with the ball drop prevention mechanism lightweight and compact as a whole joint, the above-mentioned angle regulation stopper surface 31i and the cage stopper surface S are brought close to each other to make it simple and compact. The idea of arranging the ball was the key to recalling the dimensions and arrangement of the ball dropout prevention mechanism M, which will be described later.

As a result of various studies based on the above idea, a vertical cross section of the end face corner portion 4c of the cylindrical shaft portion 4b of the intermediate shaft 4 constituting the ball dropout prevention mechanism M, including the joint axis NN in a state where the operating angle is 0 °. On the inner side of the outer joint member 31, the range surrounded by the _{circle C C} including the spherical outer peripheral surface 34b of the cage 34 and the _{circle C T} including the groove bottom of the curved track groove 31d of the outer joint member 31. I arrived at the configuration to arrange. The ball dropout prevention mechanism M shown in FIGS. 6 to 8 has the above-mentioned configuration in common.

In the ball dropout prevention mechanism M shown in FIG. 6, the fixed constant velocity universal joint 3 has an operating angle of 0 °, and in a vertical cross section including the joint axis NN, the cylindrical shaft of the joint center O and the intermediate shaft 4 The angle α formed by the straight line R connecting the end face corner portion 4c of the portion 4b and the joint axis NN is set to 13 °. In this specific example, the dimensions and arrangement of the cage stopper surface S, the end surface corner portion 4c of the cylindrical shaft portion 4b of the intermediate shaft 4, and the angle regulation stopper surface 31i can be set with the greatest margin. The angle regulation stopper surface 31i has _{an inner diameter corresponding to the regulation angle θ LIMIT} (for example, 25 °).

In the ball dropout prevention mechanism M shown in FIG. 7, the fixed constant velocity universal joint 3 has an operating angle of 0 °, and in a vertical cross section including the joint axis NN, the cylindrical shaft of the joint center O and the intermediate shaft 4 The angle α formed by the straight line R connecting the end face corner portion 4c of the portion 4b and the joint axis NN is set to 10 °. Considering the strength of the processing center hole provided in the cylindrical shaft portion 4b of the intermediate shaft 4 and the cylindrical shaft portion 4b, the angle α = 10 ° is the lower limit. The inner diameter of the angle regulation stopper surface 31i is reduced by the amount that the angle α is reduced.

In the ball dropout prevention mechanism M shown in FIG. 8, in the state where the fixed constant velocity universal joint 3 has an operating angle of 0 ° and in the vertical cross section including the joint axis NN, the cylindrical shaft of the joint center O and the intermediate shaft 4 The angle α formed by the straight line R connecting the end face corner portion 4c of the portion 4b and the joint axis NN is set to 17 °. Since the inner diameter of the angle regulation stopper surface 31i is increased by the increase in the angle α, the angle α = 17 ° is the upper limit in order to secure the cage stopper surface S.

From the above, in the state where the fixed constant velocity universal joint 3 has an operating angle of 0 ° and in the vertical cross section including the joint axis NN, the joint center O and the end face corner portion 4c of the cylindrical shaft portion 4b of the intermediate shaft 4 The angle α formed by the straight line R connecting the two and the joint axis NN is preferably 10 ° to 17 °.

FIG. 9 summarizes the dimensions and arrangement of the end face corner portion 4c of the cylindrical shaft portion 4b of the intermediate shaft 4 constituting the ball dropout prevention mechanism M described above. As shown by cross-hatching in FIG. 9, the end face angle portion 4c (not shown in FIG. 9) of the cylindrical shaft portion 4b of the intermediate shaft 4 has a joint axis NN in a state where the operating angle is 0 °. On the inner side of the outer joint member 31 having a vertical cross section, the circle C _{C including the spherical outer peripheral surface 34b of the cage 34 and the circle C T} including the groove bottom of the curved track groove 31d of the outer joint member 31 are surrounded. It is preferable to arrange it within the above range. Moreover, the angle α is preferably 10 ° to 17 °. With the above configuration, the fixed constant velocity universal joint 3 provided with the ball dropout prevention mechanism M for exclusive use of the rear wheel drive shaft can be made lightweight and compact at low cost and as a whole joint.

In the fixed constant velocity universal joint 3 of the present embodiment, the intermediate shaft 4 has a solid shape and the cylindrical shaft portion 4b is integrally formed, but the present invention is not limited to this. For example, a structure in which a component forming a cylindrical shaft portion separate from the intermediate shaft is fitted and fixed to the intermediate shaft or welded and fixed may be used. Further, the intermediate shaft may be a hollow shaft, and similarly to the above, a structure in which a component forming a separate cylindrical shaft portion is fitted and fixed to the intermediate shaft or welded and fixed may be used.

The boot 15 mounted on the fixed constant velocity universal joint 3 will be described with reference to FIGS. 10 and 11. FIG. 10 is a vertical cross-sectional view of the fixed constant velocity universal joint 3 to which the boot 15 is mounted in a state where the operating angle is 0 °, and FIG. 11 is a state in which _{the regulation angle θ LIMIT of the ball dropout prevention mechanism M is taken.} It is a vertical sectional view.

As shown in FIG. 10, the boot 15 has a small diameter mounting portion 16 fitted in the boot mounting groove 4d on the outer periphery of the intermediate shaft 4 and a large diameter fitted in the boot mounting groove 31k on the outer periphery of the outer joint member 31. It includes a mounting portion 17, and a bent portion 18 that connects the small-diameter mounting portion 16 and the large-diameter mounting portion 17. The bent portion 18 includes a concave curved portion 18a that is curved in a concave shape that increases in diameter from the small diameter mounting portion 16 to the large diameter mounting portion 17, and a convex curved portion 18b that is connected to the concave curved portion 18a. It consists of and does not have a bellows. The convex curved portion 18b is connected to the large diameter mounting portion 17 via the step portion 18c. In the fixed constant velocity universal joint 3 of the present embodiment, the opening side end portion of the cage 34 protrudes from the opening side end surface 31e of the outer joint member 31, but the concave curved portion 18a of the boot 15 has an inner surface thereof. It is formed so as to lightly touch the opening-side end of the cage 34. The small-diameter mounting portion 16 is fitted in the boot mounting groove 4d on the outer periphery of the intermediate shaft 4, and is fastened and fixed by the boot band 19. The large-diameter mounting portion 17 is fitted in the boot mounting groove 31k on the outer periphery of the outer joint member 31, and is fastened and fixed by the boot band 20.

The boot 15 is made of an elastic resin material, and is formed of, for example, a thermoplastic elastomer material by blow molding, injection molding, or the like. The material constituting the boot 15 is not limited to the thermoplastic elastomer material, and conventionally used materials can be used.

As shown in FIG. 11, when the regulation angle θ _LIMIT of the ball dropout prevention mechanism M is taken, the bent portion 18 is deformed substantially linearly on the pulling side (lower side of FIG. 11) of the boot 15. The film length of the bent portion 18 is set in consideration of the _{regulation angle θ LIMIT.} On the other hand, on the compression side (upper side of FIG. 11) of the boot 15, the concave curved portion 18a of the bent portion 18 is deformed so as to be folded, and interference with the opening side end portion of the cage 34 does not occur. Although the boot 15 does not have a bellows portion, since the regulation angle θ _LIMIT (for example, about 25 °) of the ball dropout prevention mechanism M is set, it is possible to prevent the boot from getting caught or coming off, and the boot 15 is compact. It is possible to reduce the amount of grease filled.

In the fixed constant velocity universal joint 3 in the present embodiment, a boot 15 having no bellows portion is attached to the bent portion 18, but the present invention is not limited to this. Boots may be fitted with a bellows portion in which peaks and valleys are alternately and continuously formed in the axial direction between the large-diameter mounting portion and the small-diameter mounting portion.

In the present embodiment, in order to obtain strength and durability, a heat treatment cured layer is formed on the surfaces of the track groove 31d, the spherical inner peripheral surface 31c, the inner joint member 32, the cage 34, etc., which are constituent members of the outer joint member 31. However, illustration and description will be omitted.

Next, the fixed constant velocity universal joint according to the second embodiment will be described with reference to FIGS. 12 and 13. FIG. 12 is a vertical cross-sectional view of the fixed constant velocity universal joint according to the present embodiment, and FIG. 13 is a vertical sectional view of the fixed constant velocity universal joint of FIG. 12 in a state where the ball dropout prevention mechanism is at a regulated angle. Is.

The fixed constant velocity universal joint 3 ₁ of the present embodiment has the same internal specifications as the fixed constant velocity universal joint 3 of the first embodiment described above, and is a cage for ensuring the same ball incorporation angle. It is provided with an inclination allowable space K and a ball dropout prevention mechanism M. However, the tilt allowable space K of the cage 34 of the present embodiment does not include the cage stopper surface S to which the end face corner portion 34c of the cage 34 comes into contact when the ball is incorporated at an angle, and the cage 34 is tilted. The ball assembly angle is secured by the gap of the allowable space K. The fixed constant velocity universal joint 3 ₁ of the present embodiment has the differences described below as compared with the fixed constant velocity universal joint 3 of the first embodiment. Since the portion excluding this difference is the same as that of the fixed constant velocity universal joint 3 of the first embodiment, the same reference numerals are given to the portions having the same function, and the fixed type of the first embodiment is designated. The contents described for the constant velocity universal joint 3 shall apply mutatis mutandis.

12, as shown in FIG. 13, the fixed type constant velocity universal joint 3 ₁ of this embodiment, formed on the inner side bottom portion 31g of the outer joint member 31 _1, which is one configuration of a ball captive M The heat treatment-cured layer H1 is formed on the angle-regulating stopper surface 31i on the inner circumference of the recess 31h. The heat-treated cured layer H1 is shown with fine hatching. The ball dropout prevention mechanism M regulates the angle by interfering between the cylindrical shaft portion 4b provided at the end of the intermediate shaft 4 and the angle regulating stopper surface 31i on the inner circumference of the recess 31h formed in the back bottom portion 31g. Therefore, the regulation angle θ _LIMIT is governed by the size of the inner diameter of the recess 31h when the outer diameter of the cylindrical shaft portion 4b provided at the end of the intermediate shaft 4 is constant. Therefore, if the angle is regulated to a larger angle, _{the wall thickness of the inner bottom portion 31 g of the outer joint member 31 1} becomes thin, which also affects the strength, so that a very large angle cannot be provided.

Fixed type constant velocity universal joint 3 ₁ of this embodiment is made compact in the axial and radial directions, and reduce the weight, in particular, FIG. 12, the outer joint member 31 ₁ shown in FIG. 13, a cup-shaped The outer diameter of the back face portion 31n, which is a processing reference when machining the track groove 31d inside the mouse portion 31a and the spherical inner peripheral surface 31c, is designed to be small, and the outer diameter of the back face portion 31n and the angle regulation stopper surface 31i are combined. A thin-walled portion T is formed between the two. By heat-treating the inner circumference of the thin portion T, that is, the angle-regulating stopper surface 31i to form a hardened layer, the _{insufficient strength of the outer joint member 31 1} is compensated and the strength of the outer joint member 31 ₁ is maintained.

On the other hand, when the heat-treated cured layer H1 is not formed on the inner circumference of the thin-walled portion T, as shown in FIG. 13, when the regulation angle θ _LIMIT is taken, the cylindrical shaft portion at the end of the intermediate shaft 4 The 4b may come into contact with the angle regulating stopper surface 31i on the inner circumference of the recess 31h, and there is a concern about contact marks, which may affect the strength of _{the outer joint member 31 1 starting from the contact marks.} To supplement, the wheel hub of the wheel bearing to the outer joint member 31 ₁ of the stem portion 31b (not shown) is assembled, threaded portion of the shaft end of the stem portion 31b (see FIG. 1) screwed nuts clamping Will be done. Therefore, since the axial force of the nut on the outer joint member 31 ₁ of the back face portion 31n is loaded constantly and may impact on the strength of the outer joint member 31 _1, starting from the contact trace described above is feared ..

By forming a heat-treated hardened layer H1 is the inner periphery of the thin portion T of the angle regulating stopper surface 31i of the ball captive M, the strength of the outer joint member 31 ₁ is secured, also the recess 31h (angle regulation stopper surface 31i ) Can be set large and the regulation angle θ _LIMIT can be increased, so that the degree of freedom in designing the regulation angle θ _{LIMIT can be increased.}

The inner periphery of the track grooves 31d of the outer joint member 31 ₁ of the mouth portion 31a, a spherical inner peripheral surface 31c is induction hardening is applied to the surface, heat treatment hardened layer H2, H3 are formed. The heat-treated cured layers H2 and H3 are shown with fine hatching. The hardness of the heat-treated cured layers H2 and H3 is about HRC58 to 63. On the other hand, the hardness of the heat-treated cured layer H1 formed on the inner circumference of the thin-walled portion T of the angle-regulating stopper surface 31i is such that the corner of the end of the angle-regulating stopper surface 31i is cracked or the thin-walled portion T is burnt out. In consideration of the above, about HRC50, for example, HRC46 to HRC54 is desirable. Accordingly, the hardness of the angle regulating stopper surface 31i of the thin portion heat-treated hardened layer is formed on the T H1, the outer joint member 31 ₁ track groove 31d and the spherical inner peripheral surface 31c formed in the heat treatment hardened layer H2, H3 It is set lower than the hardness. Here, the hardness of the heat-treated cured layers H1, H2, and H3 is defined as the surface hardness. Hardness in the present specification and claims shall be used based on the above definition.

The heat treatment of the inner circumference of the thin portion T of the angle regulation stopper surface 31i can be utilized by appropriately adjusting and modifying the high-frequency heating coil for the heat treatment of the track groove 31d on the inner circumference of the mouse portion 31a and the spherical inner peripheral surface 31c. .. Thus, the inner periphery of the track grooves 31d of the outer joint member 31 ₁ of the mouth section 31a, can simultaneously heat treatment inner circumference of the heat treatment and the spherical inner peripheral surface 31c and the angle regulation stopper surface 31i, abbreviated annealing cost of the heat treatment work It can be suppressed.

The fixed constant velocity universal joint 3 ₁ of the present embodiment has the same internal specifications as the fixed constant velocity universal joint 3 of the first embodiment described above, and also allows the tilting of the cage to secure the same ball incorporation angle. An example is provided with a space K and a ball dropout prevention mechanism M. Therefore, the fixed type constant velocity universal joint 3 ₁ ring drive shaft only after having a ball captive M, at low cost, and can be lightweight and compact as a whole joint, further outer joint member 31 A remarkable effect that the strength of _{1 can be secured can be obtained.}

However, by forming the heat treatment cured layer H1 on the inner circumference of the angle regulation stopper surface 31i in the present embodiment, _{the strength of the outer joint member 31 1} is ensured, and the inner diameter of the recess 31h is set large to regulate the angle θ _LIMIT. As for the _{advantage that the degree of freedom in designing the regulation angle θ LIMIT} can be increased, the internal specifications of the fixed constant velocity universal joint 3 of the first embodiment described above and the ball incorporating angle can be adjusted. The same applies not only to the dimensions and arrangement of the tilt allowable space K (retainer stopper surface S) and the ball dropout prevention mechanism M to be secured, but also to those whose internal specifications, dimensions, and arrangement are appropriately adjusted and changed within a practical range. Can be applied to. The heat-treated cured layer H1 is not limited to the cylindrical surface portion 31m of the angle-regulating stopper surface 31i, and can be formed including an appropriate region such as the bottom portion of the recess 31h.

Figure 14 shows a modification of the fixed type constant velocity universal joint 3 ₁ of the second embodiment in FIG. 15. Fixed type constant velocity universal joint 3 ₂ of the present modification, the same dimensions shape of the outer diameter and the inner side bottom 31g of the back face portion 31n of the outer joint member 31 ₂ and the outer joint member 31 of the first embodiment, Designed for shape. _{The fixed constant velocity universal joint 3 2} of this modification is of a type in which the end face corner portion 34c on the back side of the cage 34 comes into contact with the cage stopper surface S when the ball is incorporated at an angle. The fixed constant velocity universal joint 3 ₂ of this modification has the differences described below as compared with the fixed constant velocity universal joint 3 of the first embodiment. Since the portion excluding this difference is the same as that of the fixed constant velocity universal joint 3 of the first embodiment, the same reference numerals are given to the portions having the same function, and the fixed type of the first embodiment is designated. The contents described for the constant velocity universal joint 3 shall apply mutatis mutandis. Also apply mutatis mutandis contents described fixed type constant velocity universal joint 3 ₁ of the second embodiment.

Heat treatment hardened layer H1 is formed on the inner periphery of the outer joint member 31 _{and second} angle regulation stopper surface 31i in this modification. Also in this modification, the inner circumference of the track grooves 31d of the outer joint member 31 _{and second} mouth portion 31a, a spherical inner peripheral surface 31c is induction hardening is performed, but heat treatment hardened layer H2, H3 are formed, illustrated Omit.

In the fixed constant velocity universal joint 3 ₂ of this modification, the internal specifications are the same as those of the fixed constant velocity universal joint 3 of the first embodiment described above, and the tilt allowable space K for ensuring the same ball assembling angle. An example is provided with (retainer stopper surface S) and a ball dropout prevention mechanism M. Therefore, the wheel drive shaft only fixed type constant velocity universal joint 3 ₂ after having a ball captive M, at low cost, and can be lightweight and compact as a whole joint, further outer joint member 31 A remarkable effect that the strength of _{2 can be secured can be obtained.}

However, also in this modified example, by forming a heat-treated hardened layer on the inner periphery of the angle regulation stopper surface 31i, strength of the outer joint member 31 ₂ is secured, also set a larger inner diameter of the recess 31h regulation angle θ _{Since the LIMIT} can be increased, the advantages of increasing the degree of freedom in designing the regulation angle θ _LIMIT include the internal specifications of the fixed constant velocity universal joint 3 of the first embodiment described above and the ball incorporating angle. Not only the dimensions and arrangement of the tilt permissible space K (retainer stopper surface S) and the ball dropout prevention mechanism M, but also those whose internal specifications, dimensions, and arrangement are appropriately adjusted and changed within a practical range. It can be applied in the same way.

The present invention is not limited to the above-described embodiments, and it goes without saying that the present invention can be carried out in various forms without departing from the gist of the present invention. Indicated by the scope of the claim and further includes the equal meaning described in the claims, and all modifications within the scope.

1 Rear wheel drive shaft 3 Fixed constant velocity joint 4 Intermediate shaft 4a Spline 4b Cylindrical shaft 4c End face corner 15 Boot 18 Bending 18a Concave curved 31 Outer joint member 31c Spherical inner peripheral surface 31d Track groove 31g Side bottom 31h Recess 31i Angle regulation stopper surface 31j Convex corner 32 Inner joint member 32d Spherical outer surface 32e Track groove 33 Ball 34 Cage 34b Spherical outer surface 34c Spherical inner peripheral surface C _C Circle including the spherical outer surface of the cage C _T Circle including the bottom of the curved track groove of the outer joint member D _BALL Ball diameter H1 Heat-treated hardened layer H2 Heat-treated hardened layer H3 Heat-treated hardened layer K Allowable space for inclination of cage M Ball dropout prevention mechanism N Joint axis O Joint center R Straight line connecting the joint center and the end face corner of the cylindrical shaft of the intermediate shaft S Cage stopper surface W1 _O Axial length from the joint center to the opening side end face of the outer joint member W _C Cage width α The angle between the straight line R and the joint axis

Claims (8)

Eight curved track grooves extending in the axial direction are formed on the inner peripheral surface of the sphere, and an outer joint member having an opening side and a back side separated in the axial direction and eight curves extending in the axial direction on the outer peripheral surface of the sphere. An inner joint member having a shaped track groove formed therein, eight balls arranged between the track groove of the outer joint member and the corresponding track groove of the inner joint member, and one ball. The outer side is provided with a cage having eight pockets for accommodating each of them, and having a spherical outer peripheral surface and a spherical inner peripheral surface that are in sliding contact with the spherical inner peripheral surface of the outer joint member and the spherical outer peripheral surface of the inner joint member, respectively. The center of curvature of the curved track groove of the joint member and the center of curvature of the curved track groove of the inner joint member are offset by equal distances on the opposite side of the joint center in the axial direction, and power can be transmitted to the inner joint member. In a fixed constant velocity universal joint with connected shafts
The fixed type constant velocity universal joint is made compact and lightweight configuration with a ball Lumpur captive,
In the lightweight and compact configuration, the ratio W1 _O / D _{BALL of the axial length (W1 O} ) from the joint center to the opening side end face of the outer joint member and the diameter of the ball (D _BALL ) is 0. 35 to 0.52,
The ratio W _C / D _BALL of said retainer having a width (W _C) and of the ball diameter (D _BALL) along with a 1.63 to 1.80,
At the bottom of the inner side of the outer joint member, a tiltable space for the cage that secures the ball assembly angle is formed.
The ball dropout prevention mechanism includes a cylindrical shaft portion provided at the end of the shaft and an angle-regulating stopper surface on the inner circumference of a recess formed in the back bottom portion, and the cylindrical shaft portion and the angle. The regulation stopper surface interferes with the ball at an angle smaller than the ball assembly angle and larger than the maximum operating angle when the joint is used.
On the inner side of the outer joint member in the vertical cross section including the joint axis at an operating angle of 0 °, a circle ( _CC ) including a spherical outer peripheral surface of the cage and a curved track groove of the outer joint member. A fixed constant velocity universal joint characterized in that an end face corner portion of the cylindrical shaft portion of the shaft is arranged within a range surrounded by a _{circle (CT} ) including a groove bottom. The fixed constant velocity universal joint according to claim 1, wherein an inclination allowable space of a cage for securing a ball incorporation angle formed on the inner bottom portion of the outer joint member is provided with a cage stopper surface. .. The angle-regulating stopper surface has a cylindrical surface portion centered on the joint axis, and the portion where the angle-regulating stopper surface intersects with the cage stopper surface forms a convex corner portion in a vertical cross section including the joint axis. The fixed constant velocity universal joint according to claim 2, wherein the joint is formed. A straight line (O) connecting the joint center (O) and the end face corner of the cylindrical shaft portion of the shaft in a vertical cross section including the joint axis when the fixed constant velocity universal joint has an operating angle of 0 °. The fixed constant velocity universal joint according to any one of claims 1 to 3, wherein an angle (α) formed by R) and the joint axis is 10 ° to 17 °. Claims 1 to 3 include that the recess formed in the inner bottom portion of the outer joint member has a surface formed by forging, and the angle-regulating stopper surface on the inner circumference of the recess has a surface processed. The fixed constant velocity universal joint according to any one of the items. The fixed type or the like according to any one of claims 1 to 5, wherein a resin boot having no bellows portion is mounted between the outer joint member of the fixed constant velocity universal joint and the shaft. Fast universal joint. The fixed constant velocity universal joint according to claim 1, wherein a heat treatment-cured layer is formed on the angle-regulating stopper surface of the ball dropout prevention mechanism. The seventh aspect of claim 7, wherein the hardness of the heat-treated cured layer formed on the angle-regulating stopper surface is lower than the hardness of the heat-treated cured layer formed on the track groove and the spherical inner peripheral surface of the outer joint member. Fixed constant velocity universal joint.

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