This application claims priority to Japanese Patent Application No. 2020-049710 filed on Mar. 19, 2020, incorporated herein by reference in its entirety.
The disclosure relates to a method for assembling a constant velocity joint.
There has been a cross-groove constant velocity joint disclosed in, for example, Japanese Unexamined Patent Application Publication No. 7-71468 (JP 7-71468 A). In the related-art cross-groove constant velocity joint, both side faces of each outer ball groove of an outer joint member are inclined along a central axis of the outer joint member at a position near an opening end face of the outer joint member, thereby providing straight portions parallel to the central axis.
There has also been a constant velocity joint disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2018-71654 (JP 2018-71654 A). In the related-art constant velocity joint, outer ball grooves and inner ball grooves are arranged such that an inclination direction of the outer ball groove relative to a central axis of an outer joint member is opposite to an inclination direction of the inner ball groove relative to a central axis of an inner joint member. In the related-art constant velocity joint, the inner ball groove has a relief portion to allow a ball to move out of the inner ball groove to one side in a central axis direction of the inner joint member.
In general, cross-groove constant velocity joints are assembled by mounting balls, a cage, and an inner joint member from an opening, that is, an inlet opening of an outer joint member similarly to the cross-groove constant velocity joint disclosed in JP 7-71468 A. In the cross-groove constant velocity joint disclosed in JP 7-71468 A, a unit including the balls and the cage or the inner joint member is mounted into the outer ball grooves via the straight portions provided in the outer ball grooves. Thus, the strength of the cage is secured, and good assemblability is attained.
In the constant velocity joint disclosed in JP 2018-71654 A, the ball needs to move to one side along the central axis of the inner joint member, that is, to the inlet opening of the outer joint member via the relief portion. Therefore, when the inner joint member is mounted from the inlet opening of the outer joint member in the constant velocity joint disclosed in JP 2018-71654 A, the inner joint member needs to be mounted in a state in which the other side of the inner joint member on the central axis of the inner joint member faces the outer joint member. Since the outer ball grooves and the inner ball grooves are inclined in the opposite directions, it is difficult to mount the balls, the cage, and the inner joint member into the outer joint member with ease. Thus, there is a demand to improve the assemblability.
The disclosure provides a method for manufacturing a constant velocity joint with good assemblability.
One aspect of the disclosure relates to a method for assembling a constant velocity joint including an outer joint member, an inner joint member, a plurality of balls, and a cage. The outer joint member has outer ball grooves each of which extends in a direction in which the outer ball groove is inclined relative to a central axis of the outer joint member. The inner joint member has inner ball grooves each of which is inclined relative to a central axis of the inner joint member in a direction opposite to the direction in which the outer ball groove is inclined. The balls are supported in a rollable manner on the outer ball grooves and the inner ball grooves arranged to face each other by housing the inner joint member in the outer joint member, and the balls are configured to transmit a torque between the outer joint member and the inner joint member. The cage is arranged between an inner peripheral surface of the outer joint member and an outer peripheral surface of the inner joint member, and the cage has windows each configured to house one of the balls. The method includes a first step of inserting a unit in which the balls are housed in the windows of the cage from one side in a direction of the central axis of the outer joint member toward another side in the direction of the central axis of the outer joint member to allow the balls to roll along the outer ball grooves, and a second step of mounting the inner joint member while moving the inner joint member in the outer joint member along the direction of the central axis of the outer joint member.
According to this method, the inner joint member can be mounted in the outer joint member by arranging, in the outer ball grooves of the outer joint member, the balls of the unit in a rollable manner, and then causing the balls to enter the inner ball grooves. Thus, the balls, the cage, and the inner joint member can be easily mounted in the outer joint member, and the assemblability of the constant velocity joint can be improved.
Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein:
A constant velocity joint 100 is a cross-groove joint, and is slidable in a central axis direction of the joint. As illustrated in
As illustrated in
The outer ball groove 13 includes a finished portion 13a and a finishing relief portion 13b. The finished portion 13a serves as a rolling portion where the ball 30 rolls during a normal operation of the constant velocity joint 100. The finishing relief portion 13b serves as a machining relief in the finishing of the finished portion 13a. The finishing relief portion 13b is provided at a deep portion 10b opposite to a slide-in side of the outer joint member 10, that is, an inlet opening 10a of the housing 11 to adjoin the finished portion 13a in the inclination direction of the outer ball groove 13 (i.e., the direction in which the outer ball groove 13 is inclined). The outer ball grooves 13 are formed so that an inclination direction of one outer ball groove 13 relative to the central axis J1 (hereinafter referred to simply as “inclination direction of outer ball groove 13”) is opposite to an inclination direction of another outer ball groove 13 adjacent to the one outer ball groove 13 in a circumferential direction of the outer joint member 10. The outer ball groove 13 is described later in detail.
A plurality of inner ball grooves 21 is formed on the outer peripheral surface of the inner joint member 20 (see
As illustrated in
The cage 40 is arranged between the inner peripheral surface of the outer joint member 10 and the outer peripheral surface of the inner joint member 20. As illustrated in
The partition member 50 is a disc-shaped member fixed while being press-fitted to the flange 12 of the outer joint member 10. The partition member 50 separates an internal space of the outer joint member 10 from an external space. The internal space of the outer joint member 10 is filled with grease serving as a lubricant. The partition member 50 prevents leakage of the grease to the outside.
The outer ball groove 13 includes the finished portion 13a and the finishing relief portion 13b. In general, the outer ball groove 13 is roughly machined by using a small-diameter rough machining tool T1 as indicated by an alternate long and two short dashes line in
In this example, when the constant velocity joint 100 is assembled as described later, the inner joint member 20 is moved toward the inlet opening 10a along the central axis J1 of the outer joint member 10 as indicated by an arrow in
Specifically, as illustrated in
As illustrated in
When the angle θ2 is larger than the angle θ1 as illustrated in an enlarged view of
Thus, to form the finishing relief portion 13b of the outer ball groove 13, the inner ball groove 21 and the finishing relief portion 13b need to have the relationship in which the angle θ2 is larger than the angle θ1. With this configuration, when the inner joint member 20 is moved toward the inlet opening 10a of the outer joint member 10, the outer ball groove-side pressing force Fh1 (component force Fb1) acting on the ball 30 from the finishing relief portion 13b and the stepped portion 13c decreases along with the movement of the ball 30.
Thus, the ball 30 can smoothly climb over the stepped portion 13c. Thus, the ball 30 can be moved from the finishing relief portion 13b to the finished portion 13a in the outer ball groove 13 along with the movement of the inner joint member 20. Accordingly, the ball 30 can be supported in a rollable manner by the inner ball groove 21 and the outer ball groove 13, and the constant velocity joint 100 can be assembled.
Details of the inner ball groove 21 are described with reference to
In
The inner ball groove 21 has a rolling guide bottom face 21a, a first rolling guide side face 21b, and a second rolling guide side face 21c. The sectional shape of the inner ball groove 21 that is orthogonal to the groove direction is a concave shape. The rolling guide bottom face 21a is a bottom of the concave cross section. The first rolling guide side face 21b is one side face of the concave cross section. The second rolling guide side face 21c is the other side face of the concave cross section.
In
In
The inner joint member 20 has, in addition to the inner ball grooves 21, gate portions 22 that permit the balls 30 to access the inner ball grooves 21. Each gate portion 22 allows the ball 30 to exit from the inner ball groove 21 to one side in the direction of the central axis J2 of the inner joint member 20, or allows the ball 30 to enter the inner ball groove 21 from the one side.
The gate portion 22 is formed between the first rolling guide side face 21b and the one end face 20a of the inner joint member 20 in the direction of the central axis J2. On the assumption that the first rolling guide side face 21b is provided to reach the end face 20a, the gate portion 22 is formed by cutting off a portion of the imaginary first rolling guide side face 21b, the portion being connected to the end face 20a. The area where the gate portion 22 is formed is defined as a gate area 23.
Specifically, the gate portion 22 is a rolling guide side face configured to guide the ball 30 in an inclination direction opposite to the inclination direction of the inner ball groove 21 relative to the central axis J2 of the inner joint member 20. That is, in
The gate portion 22 of this example is formed only between the first rolling guide side face 21b and the end face 20a. That is, the gate portion 22 of this example is not formed between the first rolling guide side face 21b and the end face 20b, and is not formed between the second rolling guide side face 21c and each of the end face 20a and the end face 20b.
As described above, the finished portion 13a, the finishing relief portion 13b, and the stepped portion 13c of each outer ball groove 13 are formed in the outer joint member 10 of the constant velocity joint 100 so that the angle θ2 is larger than the angle θ1. Further, the inner ball grooves 21 having the gate portions 22 are formed in the inner joint member 20 of the constant velocity joint 100. Therefore, when the constant velocity joint 100 is assembled by housing the inner joint member 20, the balls 30, and the cage 40 in the outer joint member 10, the balls 30 housed in the individual windows 41 of the cage 40 can be caused to enter the inner ball grooves 21 by using the gate portions 22. This operation is described with reference to
When the constant velocity joint 100 is assembled as illustrated in
In this example, the inner joint member 20 is inserted into the deep portion 10b from the flange 12-side of the outer joint member 10, that is, the deep-side opening of the outer joint member 10. In this case, the inner joint member 20 is housed so that the end face 20a of the inner joint member 20 is oriented to the inlet opening 10a of the outer joint member 10. In this state, the inner joint member 20 is arranged so that the balls 30 are positioned in the gate area 23 as illustrated in
At this time, each ball 30 positioned in the gate area 23 rolls toward the inner ball groove 21 while being guided by the gate portion 22 and the outer ball groove 13 as illustrated in
If the inner ball groove 21 does not have the gate portion 22, the ball 30 guided by the outer ball groove 13 is sandwiched between the first rolling guide side face 21b of the inner ball groove 21 and a cage bar 42 of the cage 40. Therefore, the entry of the ball 30 into the inner ball groove 21 is restricted. In this case, it is necessary to increase the size of the window 41 of the cage 40, in other words, reduce the width of the cage bar 42.
In the constant velocity joint 100, the ball 30 positioned in the gate area 23 is guided by the gate portion 22 whose inclination direction is directed toward the same side as the side toward which the inclination direction of the outer ball groove 13 is directed. Thus, the ball 30 can easily enter the inner ball groove 21. That is, circumferential movement of the ball 30 housed in the window 41 is restricted by the cage bars 42 of the cage 40, but rolling (movement) of the ball 30 toward the inner ball groove 21 is permitted by the gate portion 22 guiding the ball 30 along the moving direction of the inner joint member 20. With the gate portion 22 of this example, it is possible to mount the inner joint member 20 without changing the size of the window 41 of the cage 40, that is, while securing the strength of the cage 40.
As illustrated in
When the inner joint member 20 moves in the state in which the ball 30 enters the inner ball groove 21, the ball 30 housed in the finishing relief portion 13b of the outer ball groove 13 starts to move as illustrated in
Along with the movement of the inner joint member 20, the ball 30 easily climbs over the stepped portion 13c to enter the finished portion 13a as illustrated in
As understood from the above description, according to the method for assembling the constant velocity joint 100, the inner joint member 20 can be mounted in the outer joint member 10 by arranging, in the outer ball grooves 13 of the outer joint member 10, the balls 30 housed in the windows 41 of the cage 40 in a rollable manner, and causing the balls 30 to enter the inner ball grooves 21 via the gate portions 22. Thus, the balls 30, the cage 40, and the inner joint member 20 can be easily mounted in the outer joint member 10, and the assemblability of the constant velocity joint 100 can be improved.
In this example, the outer joint member 10 has the conical cylinder shape in which the housing 11 has a large diameter and the flange 12 has a small diameter. The shape of the outer joint member 10 is not limited to the conical cylinder shape, and may be, for example, a cylindrical shape with two open ends. Alternatively, the shape of the outer joint member 10 may be, for example, a bottomed cylinder shape (so-called cup shape) in which one of two ends on the other side in the direction of the central axis J1 is closed.
Also in this case, the inner joint member 20 having the gate portions 22 in the inner ball grooves 21 is arranged at the deep portion 10b of the outer joint member 10 in the first step similarly to the above-mentioned example. In other words, in the first step, the inner joint member 20 is arranged on the other side in the direction of the central axis of the outer joint member 10 so as to be on an opposite side of the finishing relief portions 13b of the outer ball grooves 13 from the finished portions 13a of the outer ball grooves 13, before the unit in which the balls 30 are housed in the cage 40 is inserted into the outer joint member 10. The inner joint member 20 is moved toward the inlet opening 10a of the outer joint member 10 in a state in which the balls 30 retained by the cage 40 are housed in the finishing relief portions 13b of the outer ball grooves 13. Thus, the constant velocity joint 100 can be assembled. Since the constant velocity joint 100 can be assembled in this case as well, effects similar to those in the above-mentioned example are attained.
In the above-mentioned example, the gate portions 22 are provided in the inner ball grooves 21 of the inner joint member 20. However, the gate portions 22 may be omitted from the inner ball grooves 21. Even in the case where the gate portions 22 are not provided in the inner ball grooves 21, the inner joint member 20 can be mounted in the housing 11 of the outer joint member 10 by, for example, moving the inner joint member 20 from the deep portion 10b of the outer joint member 10 similarly to the above-mentioned example.
In the case where the gate portions 22 are not provided in the inner ball grooves 21, the entry of each ball 30 into the inner ball groove 21 is restricted because the ball 30 is sandwiched between the first rolling guide side face 21b of the inner ball groove 21 and the cage bar 42 of the cage 40. In this case, for example, the circumferential width of the cage bar 42 is reduced (that is, the size of the window 41 is increased). Thus, the inner joint member 20 can be mounted in the housing 11 of the outer joint member 10 by moving the inner joint member 20 from the deep portion 10b of the outer joint member 10 though the strength of the cage 40 may decrease.
Number | Date | Country | Kind |
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2020-049710 | Mar 2020 | JP | national |