Ball assembly device and method for fixed-type constant-velocity universal joint

Abstract

An inner joint member 3 is tilted from the side where the operation angle θ is small to the side where the operation angle θ is large, at least one of a plurality of pockets 5a of a cage 5 is exposed from an outer joint member 2, and balls are incorporated into the pockets 5a. The inner joint member 3 is then tilted from the side where the operation angle θ is large to the side where the operation angle θ is small, and the balls 4 are inserted between a track groove 7 of the outer joint member 2 and a track groove 9 of the inner joint member 3. At this time, a cage pressing part 23 that turns while maintaining a tilting angle α that is 1 / 2 the operation angle θis brought into contact with the cage 5 in the tilting direction centered on the tilt center of the inner joint member 3.

Description

Ball Incorporation Device and Method for Fixed Constant Velocity Universal Joint

[0001] The present invention relates to a ball incorporation device and method for a fixed constant velocity universal joint.

[0002] Patent Document 1 below shows an automatic assembly device for a fixed constant velocity universal joint. In this automatic assembly device, after incorporating a combination of an inner joint member and a cage (hereinafter referred to as a "cassette") into the inner periphery of an outer joint member, balls are incorporated one by one into the pockets of the cage. The incorporation of balls into the pockets of the cage is performed in the following procedure.

[0003] (1) As shown in FIG. 17, with the inner joint member 102, outer joint member 107, and cage 104 arranged coaxially, an inner ring rocking pin 127 is inserted into the inner periphery of the inner joint member 102. (2) As shown in FIG. 18, the inner joint member 102 is tilted with respect to the outer joint member 107 by the inner ring rocking pin 127 to expose one of the pockets 103 of the cage 104 from the outer joint member 107. A ball 108 supplied from a ball supply cylinder 131 is incorporated into this pocket 103. (3) By returning the inner joint member 102 to its original position (operating angle 0°) with the inner ring rocking pin 127, the ball 108 is made to enter the ball track formed by the track groove 106 of the outer joint member 107 and the track groove 101 of the inner joint member 102. The above procedure is repeated to incorporate the balls 108 into all the ball tracks.

[0004] In a state where all the balls are incorporated into the constant velocity universal joint, the positions of the cage and the balls are stabilized on the bisecting plane of the operating angle, so that even when the operating angle changes, the balls move smoothly within the ball track. On the other hand, in the ball incorporation step of (3) above, since not all the balls are incorporated into the constant velocity universal joint, depending on the internal specifications of the constant velocity universal joint, particularly the shape of the track groove, when the inner joint member is tilted in the direction of returning to its original position, the ball may not smoothly enter the ball track.

[0005] For example, paragraph 0056 and Figure 14 of Patent Document 2 below describe a technique to resolve the problem of ball jamming between the ball and the track groove by pressing the end of the cage with a cage pushing lever at the initial movement of the tilt lever that tilts the inner joint member back to its original position after the ball has been assembled into one of the pockets of the cage, thereby causing the ball to enter the track groove of the outer joint member.

[0006] Japanese Patent Publication No. 62-37519, Japanese Patent Publication No. 2024-82470

[0007] However, even when applying the technology described in Patent Document 2 to return the tilted inner joint member to its original position after tilting the inner joint member to insert the ball into the cage pocket, the ball may not move smoothly within the ball track.

[0008] Therefore, the present invention aims to enable the smooth assembly of a ball into a ball track during the ball assembly process of a fixed constant velocity universal joint.

[0009] To solve the above problems, the present invention provides a method for assembling balls into a fixed constant velocity universal joint, comprising: an outer joint member having a plurality of track grooves formed on its spherical inner circumferential surface; an inner joint member having a plurality of track grooves formed on its spherical outer circumferential surface; a plurality of balls disposed between the track grooves of the outer joint member and the track grooves of the inner joint member; and a cage having a spherical outer circumferential surface that slides against the spherical inner circumferential surface of the outer joint member, a spherical inner circumferential surface that slides against the spherical outer circumferential surface of the inner joint member, and a plurality of pockets for housing the plurality of balls, comprising the steps of: tilting the inner joint member with respect to the outer joint member from a side with a small operating angle to a side with a large operating angle to expose at least one of the plurality of pockets of the cage from the outer joint member; assembling a ball into the pocket exposed from the outer joint member; and tilting the inner joint member with respect to the outer joint member from a side with a large operating angle to a side with a small operating angle to insert the ball between the track grooves of the outer joint member and the track grooves of the inner joint member. The present invention provides a ball assembly method for a fixed constant velocity universal joint, wherein, when the inner joint member is tilted relative to the outer joint member from the side with a larger operating angle to the side with a smaller operating angle, a cage retaining portion that rotates while maintaining a tilt angle of half the operating angle is brought into contact with the cage from the rear side in the tilting direction.

[0010] When the inner joint member is tilted from the side with a large operating angle to the side with a small operating angle, the cage should ideally be positioned at a tilt angle of half the operating angle. However, since not all balls are installed during the ball installation process, it does not fully synchronize with the inner joint member and tends to tilt with a delay from the tilt angle of half the operating angle. Therefore, as described above, after installing the balls in the cage pockets, when tilting the inner joint member to the side with a smaller operating angle, the cage retainer, which rotates while maintaining an angle of half the operating angle, is brought into contact with the cage from the rear side in the direction of tilting. This maintains the cage at a tilt angle of half the operating angle. As a result, the balls held in the cage pockets are always positioned on the plane that bisects the operating angle, allowing the balls to move smoothly within the ball track. Furthermore, "tilting direction" refers to the circumferential direction centered on the tilting center. When a part is tilted to one side in the tilting direction, the same direction (one side in the tilting direction) is called the "leading side in the tilting direction," and the opposite direction (the other side in the tilting direction) is called the "rear side in the tilting direction."

[0011] In the above method, it is preferable to keep the cage retainer in contact with the cage from the rear side in the tilting direction from the time the inner joint member is tilted relative to the outer joint member from the side with a larger operating angle to the side with a smaller operating angle until the operating angle becomes 0°. This ensures that the ball is always positioned on the plane that bisects the operating angle when it enters the ball track or moves within the ball track, thereby stabilizing the ball's behavior.

[0012] When the inner joint member is tilted relative to the outer joint member from the side with a smaller operating angle to the side with a larger operating angle, the cage will attempt to tilt ahead of half the operating angle due to frictional force between it and the inner joint member. In this case, the cage's tilt angle becomes larger than the original tilt angle (half the operating angle), so when the inner joint member is tilted to an operating angle in which a ball can be inserted, not only the pocket into which the next ball will be inserted, but also the pocket adjacent to this pocket may be exposed from the outer joint member. If a ball is already inserted in this pocket, the exposure of this pocket from the outer joint member may cause the ball to fall out of this pocket.

[0013] Therefore, when tilting the inner joint member from the side with a smaller operating angle to the side with a larger operating angle relative to the outer joint member, it is preferable to bring the cage retaining portion into contact with the cage from the side that precedes the tilting direction. In this way, by bringing the cage retaining portion, which rotates at a tilting angle of half the operating angle, into contact with the cage from the side that precedes the tilting direction, it is possible to restrict the cage's tilting angle from becoming greater than half the operating angle, thereby avoiding a situation where multiple pockets are exposed from the outer joint member and preventing the previously assembled ball from falling out.

[0014] When assembling the first ball into the subassembly consisting of the outer joint member, the inner joint member, and the cage, there are no balls incorporated into the cage, and the tilting of the cage is not restricted by the balls. As a result, the tilt angle of the cage tends to become unstable when the inner joint member is tilted. Therefore, when assembling the first ball, it is particularly preferable to control the tilt angle of the cage by bringing the cage retaining portion into contact with the cage as described above.

[0015] The above method can be applied to a fixed constant velocity universal joint in which the track groove of the outer joint member has a first track groove portion having a ball trajectory centerline in the shape of an arc that is convex to the outer diameter side, and a second track groove portion that is continuous with the first track groove portion on one axial side and has a ball trajectory centerline in the shape of an arc that is convex to the inner diameter side, and the track groove of the inner joint member has a first track groove portion having a ball trajectory centerline in the shape of an arc that is convex to the outer diameter side, and a second track groove portion that is continuous with the first track groove portion on the other axial side and has a ball trajectory centerline in the shape of an arc that is convex to the inner diameter side.

[0016] In this case, in the finished product with balls installed in all pockets, the balls are always positioned on the bisecting plane of the operating angle. Therefore, the balls are positioned between the first track groove of the outer joint member, which has a convex arc shape on the outer diameter side, and the first track groove of the inner joint member, or between the second track groove of the outer joint member, which has a convex arc shape on the inner diameter side, and the second track groove of the inner joint member. However, if the balls deviate from the bisecting plane of the operating angle during the ball installation process, the balls may end up between the second track groove of the outer joint member, which has a convex arc shape on the inner diameter side, and the first track groove of the inner joint member, which has a convex arc shape on the outer diameter side, potentially causing the balls to become jammed between them.

[0017] Therefore, when applying the present invention to a fixed constant velocity universal joint having a track groove of the shape described above, it is preferable to tilt the inner joint member from the side with a larger operating angle to the side with a smaller operating angle relative to the outer joint member, and to keep the cage retaining portion in contact with the cage from the rear side in the tilting direction until the ball incorporated into the pocket exposed from the outer joint member enters the track groove of the outer joint member and crosses the boundary between the first track groove portion and the second track groove portion.

[0018] In this way, by keeping the cage retainer in contact with the cage until the ball overcomes the second track groove of the outer joint member, which has a convex arc shape on the inner diameter side, and positioning the ball on the plane that bisects the operating angle, it is possible to prevent the ball from getting jammed between the second track groove of the outer joint member, which has a convex arc shape on the inner diameter side, and the first track groove of the inner joint member, which has a convex arc shape on the outer diameter side.

[0019] The above method can be realized using a ball assembly device for a fixed constant velocity universal joint comprising: an outer joint member having a plurality of track grooves formed on its spherical inner circumferential surface; an inner joint member having a plurality of track grooves formed on its spherical outer circumferential surface; a plurality of balls positioned between the track grooves of the outer joint member and the track grooves of the inner joint member; and a cage having a spherical outer circumferential surface that slides against the spherical inner circumferential surface of the outer joint member, a spherical inner circumferential surface that slides against the spherical outer circumferential surface of the inner joint member, and a cage having a plurality of pockets for housing the plurality of balls, wherein the ball assembly device comprises: an outer ring fixing part for fixing the outer joint member; an inner ring tilting part for tilting the inner joint member relative to the outer joint member; and a cage retaining part that rotates around the tilting center of the inner ring tilting part while maintaining a tilting angle of 1 / 2 of the tilting angle of the inner ring tilting part, and is capable of contacting the cage in the tilting direction.

[0020] As described above, when the inner joint member is tilted from the side with a large operating angle to the side with a small operating angle, the cage tends to lag behind the tilt angle of half the operating angle. Therefore, it is preferable that the cage retaining portion has a first contact portion that can contact the cage from the rear side in the tilting direction when the inner joint member is tilted from the side with a large operating angle to the side with a small operating angle at the inner ring tilting portion. By bringing the above-mentioned first contact portion into contact with the cage from the rear side in the tilting direction when the inner joint member is tilted from the side with a large operating angle to the side with a small operating angle, it is possible to restrict the cage from lagging behind the tilt angle of half the operating angle.

[0021] Furthermore, it is preferable that the above-described device has a second contact portion in the cage retaining portion that can contact the cage from the leading side in the tilting direction when the inner joint member is tilted from the side with a larger operating angle to the side with a smaller operating angle by the inner ring tilting portion. In this case, when the inner joint member is tilted relative to the outer joint member from the side with a larger operating angle to the side with a smaller operating angle, the first and second contact portions of the cage retaining portion contact the cage from both the rear and leading sides in the tilting direction. As a result, the cage is restricted from lagging or leading the tilting angle of half the operating angle, so that the ball can be reliably positioned on the plane that divides the operating angle into two equal parts.

[0022] As described above, according to the present invention, in the ball assembly process of a fixed constant velocity universal joint, the ball can be smoothly assembled into the ball track.

[0023] This is an axial cross-sectional view of a fixed constant velocity universal joint. This is a front view of the fixed constant velocity universal joint as seen from the axial direction. This is an axial cross-sectional view of the outer joint member of the fixed constant velocity universal joint. This is a front view of the outer joint member as seen from the axial direction. This is a side view of the inner joint member of the fixed constant velocity universal joint. This is a front view of the inner joint member as seen from the axial direction. This is a cross-sectional view of the outer joint member. This is a cross-sectional view of the inner joint member. This is a cross-sectional view of the fixed constant velocity universal joint when it has reached its maximum operating angle. This is a diagram showing the assembly procedure of the fixed constant velocity universal joint. This is a partial cross-sectional view showing a ball assembly device according to one embodiment of the present invention, with a sub-assembly consisting of an outer joint member, an inner joint member, and a cage set in it. This is a perspective view of the ball assembly device and sub-assembly. This is a partial cross-sectional view of the ball assembly device and sub-assembly, showing the inner joint member tilted to expose the pocket from the outer joint member. This is a partial cross-sectional view of the ball assembly device and sub-assembly shown above, illustrating the state in which the inner joint member is tilted from the side with a large operating angle to the side with a small operating angle to insert the ball into the track groove of the outer joint member. This is a partial cross-sectional view of the ball assembly device and sub-assembly shown above, illustrating the state in which the inner joint member is returned to its original position until the operating angle is 0°. This is a partial cross-sectional view of the ball assembly device and sub-assembly according to another embodiment. This is a cross-sectional view showing the state in which the sub-assembly is set in a conventional ball assembly device. This is a cross-sectional view showing the state in which the ball is assembled by tilting the inner joint member in the ball assembly device of Figure 17.

[0024] Embodiments of the present invention will be described below with reference to the drawings.

[0025] The fixed constant velocity universal joint 1 shown in Figures 1 and 2 is a track groove crossing type fixed constant velocity universal joint and has an outer joint member 2, an inner joint member 3, a ball 4, and a cage 5. The outer joint member 2 has a cup shape with one side open in the axial direction and the other side closed in the axial direction. Hereinafter, in the axial direction N-N of the fixed constant velocity universal joint 1 with an operating angle of 0°, the open side of the outer joint member 2 (right side in Figure 1) will be referred to as the "open side," and the closed side (left side in Figure 1) will be referred to as the "inside side."

[0026] Eight track grooves 7 are formed on the spherical inner surface 6 of the outer joint member 2. Eight track grooves 9 are formed on the spherical outer surface 8 of the inner joint member 3. The spherical inner surface 6 of the outer joint member 2 is interlocked with the spherical outer surface 12 of the cage 5. The spherical outer surface 8 of the inner joint member 3 is interlocked with the spherical inner surface 13 of the cage 5. The cage 5 is provided with eight pockets 5a, and one ball 4 is housed in each pocket.

[0027] As shown in Figure 3, the ball trajectory centerline X of the track groove 7 of the outer joint member 2 is inclined circumferentially with respect to the joint axis N-N. Specifically, the plane M containing the ball trajectory centerline X of the track groove 7 of the outer joint member 2 and the joint center O is inclined by an angle γ with respect to the joint axis N-N. As shown in Figure 5, the ball trajectory centerline Y of the track groove 9 of the inner joint member 3 is inclined circumferentially with respect to the joint axis N-N. Specifically, the plane Q containing the ball trajectory centerline Y of the track groove 9 of the inner joint member 3 and the joint center O is inclined by an angle γ with respect to the joint axis N-N.

[0028] The ball trajectory centerlines X of adjacent track grooves 7 in the outer joint member 2 are inclined circumferentially on the opposite side of the axis N-N (see Figures 3 and 4). The ball trajectory centerlines Y of adjacent track grooves 9 in the inner joint member 3 are inclined circumferentially on the opposite side of the axis N-N (see Figures 5 and 6). The ball trajectory centerlines X and Y of the radially opposing track grooves 7 of the outer joint member 2 and track grooves 9 of the inner joint member 3 are inclined circumferentially on the opposite side of the axis N-N, and one ball 4 is placed at each of their intersections.

[0029] As shown in Figure 7, the track groove 7 of the outer joint member 2 has a first track groove portion 7a provided in the axial region including the joint center O, and a second track groove portion 7b provided on the opening side of the first track groove portion 7a. The ball trajectory centerline Xa of the first track groove portion 7a is a circular arc shape that is convex toward the outer diameter side with Oo1 as the center of curvature, and the radius of curvature is Ro1. The center of curvature Oo1 has no axial offset with respect to the joint center O, and is offset by Fy radially toward the side approaching the ball trajectory centerline Xa (i.e., the side where the radius of curvature becomes smaller) with respect to the joint center O. The ball trajectory centerline Xb of the second track groove portion 7b is a circular arc shape that is convex toward the inner diameter side with Oo2 as the center of curvature, and the radius of curvature is Ro2. The ball trajectory centerline Xa of the first track groove 7a and the ball trajectory centerline Xb of the second track groove 7b are smoothly continuous, and their connection point A is positioned on the opening side of the joint center O.

[0030] As shown in Figure 8, the track groove 9 of the inner joint member 3 has a first track groove portion 9a provided in the axial region including the joint center O, and a second track groove portion 9b provided behind the first track groove portion 9a. The ball trajectory centerline Y of the track groove 9 of the inner joint member 3 and the ball trajectory centerline X (see Figure 7) of the track groove 7 of the outer joint member 2 have a shape that is mirror-symmetric with respect to a plane P (see Figure 8) that passes through the joint center O and is perpendicular to the axis N-N (see Figure 9). The ball trajectory centerline Ya of the first track groove portion 9a is a circular arc shape that is convex toward the outer diameter side with Oi1 as the center of curvature, and the radius of curvature is Ri1. The center of curvature Oi1 has no axial offset with respect to the joint center O, and is offset by Fy radially toward the side approaching the ball trajectory centerline Ya (i.e., the side where the radius of curvature becomes smaller) with respect to the joint center O. The ball trajectory centerline Yb of the second track groove 9b is a circular arc shape that is convex toward the inner diameter side with Oi2 as the center of curvature, and its radius of curvature is Ri2. The ball trajectory centerline Ya of the first track groove 9a and the ball trajectory centerline Yb of the second track groove 9b are smoothly continuous, and their connection point B is located behind the joint center O.

[0031] As shown in Figure 9, when the fixed constant velocity universal joint 1 takes an operating angle θ, the centers of all the balls 4 are positioned on a plane C (the bisecting plane of the operating angle θ) that forms an angle of θ / 2 with respect to a plane P that includes the joint center O and is perpendicular to the axis of the outer joint member 2. The balls 4 are held between the first track groove 7a of the outer joint member 2, which has an arc shape that is convex on the outer diameter side, and the first track groove 9a of the inner joint member 3 (see Figure 1), or between the second track groove 7b of the outer joint member 2, which has an arc shape that is convex on the inner diameter side, and the second track groove 9b of the inner joint member 3 (see Figure 9).

[0032] In this embodiment, the fixed constant velocity universal joint 1 described above is automatically assembled according to the procedure shown in Figure 10. The assembly procedure of the fixed constant velocity universal joint 1 will be described below, focusing on the ball assembly process according to the embodiment of the present invention.

[0033] First, in the outer ring supply process 11, the outer joint member 2 is brought into the automatic assembly device. Then, in the phase alignment process 12, the outer joint member 2 is rotated around its axis as needed so that the track groove 7 of the outer joint member 2 is positioned in a predetermined phase. The outer joint member 2, with the track groove 7 now aligned, is then transferred to the cassette insertion process 13.

[0034] Meanwhile, in the cassette supply process 14, the cassette, consisting of the inner joint member 3 and the cage 5, is fed into the automatic assembly device. The cassette is formed by incorporating the inner joint member 3 into the inner circumference of the cage 5, and fitting the spherical inner surface of the cage 5 with the spherical outer surface of the inner joint member 3 to form a single unit. Then, in the phase alignment process 15, the circumferential positions of the pocket 5a of the cage 5 and the track groove 9 of the inner joint member 3 are aligned. The cassette, with the phase alignment of the pocket 5a and the track groove 9 thus completed, is transferred to the cassette insertion process 13.

[0035] In the cassette insertion process 13, the cassette is assembled onto the inner circumference of the outer joint member 2 by a cassette insertion device to form a subassembly of the outer joint member 2, the inner joint member 3, and the cage 5. In the subassembly discharged from the cassette insertion process 13, the spherical outer surface of the cage 5 and the spherical inner surface of the outer joint member 2 are fitted together, and the spherical inner surface of the cage 5 and the spherical outer surface of the inner joint member 3 are fitted together, so that the axes of the outer joint member 2, the inner joint member 3, and the cage 5 are aligned.

[0036] Subsequently, the sub-assembly is transported to the ball assembly process 16, where the balls 4 are assembled one by one into the ball track formed by the track groove 7 of the outer joint member 2 and the track groove 9 of the inner joint member 3 facing it. In this embodiment, the sub-assembly transported to the ball assembly process 16 does not have any balls 4 assembled into it, and all the balls 4 are assembled in this ball assembly process 16. After that, the fixed constant velocity universal joint is discharged from the automatic assembly device after passing through the inspection process 17.

[0037] The ball assembly process 16 described above will be explained in detail below.

[0038] As shown in Figures 11 and 12, the ball assembly device used in the ball assembly process 16 includes an outer ring fixing part 21, a tilting drive part 24, a lifting drive part (not shown) for raising and lowering the tilting drive part 24, and a ball supply part (not shown).

[0039] The outer ring fixing portion 21 is for fixing the outer joint member 2 and, for example, has a chuck mechanism that presses the outer circumferential surface of the outer joint member 2 inward from three equally spaced locations in the circumferential direction.

[0040] The tilting drive unit 24 includes an inner ring tilting unit 22, a cage holding unit 23, a driving means 25 such as an electric motor, and a transmission mechanism 26.

[0041] The inner ring tilting portion 22 is inserted into the inner circumference of the inner joint member 3. The tilting center D of the inner ring tilting portion 22 coincides with the tilting center of the inner joint member 3 set in the outer ring fixing portion 21 (a straight line passing through the joint center O and perpendicular to the axes of both joint members 2 and 3) (see Figure 13).

[0042] The cage pressing portion 23 has a contact portion 23a (first contact portion) that contacts the end face 5b on the opening side of the cage 5. The cage pressing portion 23 is rotatable around the tilting center D of the inner ring tilting portion 22.

[0043] The transmission mechanism 26 transmits the driving force of the driving means 25 to the inner ring tilting portion 22 and the cage pressing portion 23. By the transmission mechanism 26, the tilting angle α of the cage pressing portion 23 shown in FIG. 13 is maintained at 1 / 2 of the tilting angle of the inner ring tilting portion 22, that is, the operating angle θ between the axis L3 of the inner joint member 3 and the axis L2 of the outer joint member 2. The transmission mechanism 26 of the present embodiment has a first connection portion 26a that connects the driving means 25 and the inner ring tilting portion 22, a second connection portion 26b that connects the driving means 25 and the cage pressing portion 23, and a speed reducer 26c provided between the first connection portion 26a and the second connection portion 26b. The speed reducer 26c is, for example, a gear speed reducer, and the reduction ratio is 1 / 2.

[0044] In the ball incorporation step 16, first, the sub-assembly of the outer joint member 2, the inner joint member 3, and the cage 5 conveyed from the cassette insertion step 13 is set in the outer ring fixing portion 21 of the ball incorporation device, and the outer joint member 2 is fixed (see FIG. 11). At this time, the track grooves 7, 9 and the pockets 5a into which the balls 4 are to be incorporated are arranged in accordance with the phase of the ball supply portion.

[0045] Next, the tilting drive portion 24 is lowered by the lifting drive portion, and the inner ring tilting portion 22 is inserted into the inner periphery of the inner joint member 3 (see the arrow in FIG. 11). In the present embodiment, the outer peripheral surface of the inner ring rotating portion 22 is a cylindrical surface, and this cylindrical surface fits with the ridges (small diameter portions) of the female spline provided on the inner joint member 3 with a slight gap (see FIG. 13). The inner ring tilting portion 22 and the inner joint member 3 are not fixed. At this time, the lower end of the contact portion 23a of the cage pressing portion 23 contacts the end face 5b on the opening side of the cage 5 or faces it with a slight gap (see FIG. 12).

[0046] Next, the drive means 25 is driven to tilt the inner ring tilting part 22, causing the inner joint member 3 attached thereto to tilt relative to the outer joint member 2 from the side with a smaller operating angle θ to the side with a larger operating angle θ (see Figure 13). At this time, the cage 5 attempts to follow the inner joint member 3, but the contact portion 23a of the cage retaining portion 23 contacts the end face 5b on the opening side of the cage 5 from the side leading in the tilting direction. More specifically, the contact portion 23a of the cage retaining portion 23 contacts the first circumferential region of the end face 5b on the opening side of the cage 5, which is located on the opening side of the outer joint member 2, that is, the circumferential region to the right of the axis L5 of the cage 5 in Figure 13. In the illustrated example, the contact portion 23a contacts the part of the end face 5b on the opening side of the cage 5 that is located on the opening side (the rightmost end in Figure 13). This restricts the tilting angle α of the cage 5 from becoming greater than half of the operating angle θ.

[0047] Then, as shown in Figure 13, when at least one of the pockets 5a of the cage 5 into which the ball 4 will be inserted is exposed from the outer joint member 2, the drive means 25 is stopped. For example, when the cage 5 is rotated in a plane passing through the circumferential center of the pocket 5a, only the pocket 5a into which the ball 4 will be inserted is exposed from the outer joint member 2. Also, when the cage 5 is rotated in a plane passing through the circumferential center of the column between the pockets 5a, the pocket 5a into which the ball 4 will be inserted and the adjacent pocket 5a are exposed from the outer joint member 2. At this time, by keeping the cage 5 in contact with the cage retaining portion 23 and maintaining the tilt angle of the cage 5 at 1 / 2 of the operating angle θ, the above-mentioned pocket 5a is exposed from the outer joint member 2 to the extent that the ball 4 can pass through, but the other pockets 5a are either not exposed from the outer joint member 2, or even if partially exposed, the ball 4 cannot pass through. In this way, the balls 4 supplied from the ball supply unit are incorporated into the pocket 5a exposed from the outer joint member 2 (see arrow in Figure 13).

[0048] Next, drive the drive means 25 to tilt the inner ring tilting portion 22, and tilt the inner joint member 3 attached thereto in the direction in which the operating angle θ decreases (see FIG. 14). At this time, while tilting the inner joint member 3 with the inner ring tilting portion 22, the contact portion 23a of the cage retainer portion 23 is brought into contact with the end face 5b on the opening side of the cage 5 from the rear side in the tilting direction. Thereby, since the tilting angle α of the cage 5 can be restricted from becoming larger than 1 / 2 of the operating angle θ, it is possible to prevent the situation where the ball 4 deviates from the bisecting plane of the operating angle θ. Thereby, when the ball 4 enters the ball track formed by the track grooves 7 and 9, or when the ball 4 advances deeper into the ball track, the behavior of the ball 4 can be stabilized.

[0049] At this time, after the ball 4 enters the track groove 7 of the outer joint member 2, until it crosses the second track groove portion 7b having an arc shape convex toward the inner diameter side in the track groove 7, the behavior of the ball 4 is particularly likely to become unstable. Therefore, it is preferable to always bring the contact portion 23a of the cage retainer portion 23 into contact with the cage 5 from the rear side in the tilting direction to control the tilting angle of the cage 5. In the present embodiment, after starting to tilt the inner joint member 3 from the side where the operating angle θ is large to the side where it is small, until the operating angle becomes 0° (see FIG. 15), the contact portion 23a of the cage retainer portion 23 is continuously brought into contact with the end face 5b of the cage 5 from the rear side in the tilting direction.

[0050] Thereafter, rotate the sub-assembly around the axis, and then arrange the track grooves 7 and 9 and the pockets 5a into which the balls 4 are to be incorporated in the phase of the ball supply unit. Then, by repeating the same procedure as above, the balls 4 are incorporated into the track grooves 7 and 9 and the pockets 5a. By repeating the above, the balls 4 are incorporated into all the track grooves 7 and 9 and the pockets 5a.

[0051] When the inner joint member 3 is tilted by the inner ring tilting part 22 to expose the pocket 5a of the cage 5 from the outer joint member 2 in order to install the second and subsequent balls 4 (see Figure 13), if a pocket 5a in which a ball 4 has already been installed is exposed from the outer joint member 2, there is a risk that this ball 4 may fall out of the pocket 5a. In this embodiment, when the inner joint member 3 is tilted by the inner ring tilting part 22, the cage retaining part 23 is brought into contact with the cage 5 from the leading side in the tilting direction, thereby restricting the tilting angle α of the cage 5 from becoming greater than half of the operating angle θ. As a result, pockets 5a other than the pocket 5a in which a ball 4 will be installed are not exposed to the outer joint member 2, and thus the ball 4 installed in these pockets 5a can be prevented from falling out.

[0052] The present invention is not limited to the embodiments described above. Other embodiments of the present invention will be described below, but points that are the same as those described above will not be repeated.

[0053] The embodiment shown in Figure 16 differs from the above embodiment in that the cage retaining portion 23 has a first contact portion 23a and a second contact portion 23b. The second contact portion 23b contacts the cage 5 from the leading side in the tilting direction when the inner joint member 3 is tilted from the side with a larger operating angle to the side with a smaller operating angle. In this embodiment, the second contact portion 23b contacts a second circumferential region of the end face 5b on the opening side of the cage 5, which is located on the inner side of the outer joint member 2 when the inner joint member 3 is tilted by the inner ring tilting portion 22, that is, the circumferential region to the left of the axis L5 of the cage 5 in Figure 16. In the illustrated example, the first contact portion 23a contacts the portion of the end face 5b on the opening side of the cage 5 that is located closest to the opening when the inner joint member 3 is tilted by the inner ring tilting portion 22 (the right end in Figure 16), and the second contact portion 23b contacts the portion located furthest inward (the left end in Figure 16).

[0054] As described above, the cage retaining portion 23 has a first contact portion 23a and a second contact portion 23b, so that when the inner joint member 3 is tilted from the side with a large operating angle to the side with a small operating angle, the first contact portion 23a and the second contact portion 23b contact the cage 5 from the rear side and the leading side in the tilting direction. This restricts the tilting angle α of the cage 5 from becoming greater or less than half of the operating angle θ, so that the tilting angle α of the cage 5 can be reliably maintained at half of the operating angle θ.

[0055] In the above embodiment, the inner ring tilting portion 22 and the cage retaining portion 23 are shown to be tilted by a common driving means 25. However, the invention is not limited to this, and the inner ring tilting portion 22 and the cage retaining portion 23 may be tilted by separate driving means.

[0056] The above embodiment shows a case where the present invention is applied to the assembly of all balls, but it is not limited to this. For example, the present invention may also be applied to the assembly of only the first ball, which exhibits unstable behavior during assembly, or to the assembly of only the first and second balls.

[0057] In the above embodiment, the cage retaining portion 23 is shown to contact the cage 5 both when tilting and returning the inner joint member 3, but it is not limited to this. For example, after the ball 4 is assembled into the pocket 5a, the cage retaining portion 23 may be brought into contact with the cage 5 only when returning the inner joint member 3 (tilting it from the side with a larger operating angle θ to the side with a smaller operating angle θ).

[0058] The ball assembly device and method of the present invention are not limited to the fixed constant velocity universal joints to which they can be applied. For example, the number of balls in a constant velocity universal joint is not limited to eight, but may be six. Furthermore, the present invention may be applied to a track groove crossing type fixed constant velocity universal joint in which the track grooves 7 and 9 of the outer joint member 2 and inner joint member 3 do not have a second track groove portion 7b and 9b that is convex on the inner diameter side, but only a first track groove portion 7a and 9a that is convex on the outer diameter side. Furthermore, the present invention may be applied to a fixed constant velocity universal joint having a track groove in which the ball trajectory centerline is parallel to the plane containing the axis, not limited to the track groove crossing type.

[0059] 1 Fixed constant velocity universal joint 2 Outer joint member 3 Inner joint member 4 Ball 5 Cage 6 Spherical inner surface 7 Track groove 7a First track groove portion 7b Second track groove portion 8 Spherical outer surface 9 Track groove 9a First track groove portion 9b Second track groove portion 21 Outer ring fixing portion 22 Inner ring tilting portion 23 Cage retaining portion 23a First contact portion 23b Second contact portion 24 Tilt drive portion 25 Drive means 26 Transmission mechanism X Ball trajectory center line of the track groove of the outer joint member Xa Ball trajectory center line of the first track groove portion Xb Ball trajectory center line of the second track groove portion Y Ball trajectory center line of the track groove of the inner joint member Ya Ball trajectory center line of the first track groove portion Yb Ball trajectory center line of the second track groove portion α Tilt angle of the cage θ Operating angle (tilting angle of the inner joint member)

Claims

1. A ball assembly device for a fixed constant velocity universal joint, comprising: an outer joint member having a plurality of track grooves formed on its spherical inner circumferential surface; an inner joint member having a plurality of track grooves formed on its spherical outer circumferential surface; a plurality of balls positioned between the track grooves of the outer joint member and the track grooves of the inner joint member; and a cage having a spherical outer circumferential surface that slides against the spherical inner circumferential surface of the outer joint member, a spherical inner circumferential surface that slides against the spherical outer circumferential surface of the inner joint member, and a plurality of pockets for housing the plurality of balls, wherein the ball assembly device further comprises: an outer ring fixing part for fixing the outer joint member; an inner ring tilting part for tilting the inner joint member relative to the outer joint member; and a cage retaining part that rotates around the tilting center of the inner ring tilting part while maintaining a tilting angle of 1 / 2 of the tilting angle of the inner ring tilting part, and is capable of contacting the cage in the tilting direction.

2. The ball assembly device for a fixed constant velocity universal joint according to claim 1, wherein the cage retaining portion has a first contact portion that can contact the cage from the rear side in the tilting direction when the inner joint member is tilted from the side with a large operating angle to the side with a small operating angle by the inner ring tilting portion.

3. The ball assembly device for a fixed constant velocity universal joint according to claim 2, wherein the cage retaining portion has a second contact portion that can contact the cage from the leading side in the tilting direction when the inner joint member is tilted by the inner ring tilting portion from the side with a larger operating angle to the side with a smaller operating angle.

4. A method for assembling balls into a fixed constant velocity universal joint, comprising: an outer joint member having a plurality of track grooves formed on its spherical inner surface; an inner joint member having a plurality of track grooves formed on its spherical outer surface; a plurality of balls positioned between the track grooves of the outer joint member and the track grooves of the inner joint member; and a cage having a spherical outer surface that slides against the spherical inner surface of the outer joint member, a spherical inner surface that slides against the spherical outer surface of the inner joint member, and a plurality of pockets for housing the plurality of balls, comprising the steps of: tilting the inner joint member from a side with a small operating angle to a side with a large operating angle relative to the outer joint member, exposing at least one of the plurality of pockets of the cage from the outer joint member; assembling a ball into the pocket exposed from the outer joint member; and tilting the inner joint member from a side with a large operating angle to a side with a small operating angle relative to the outer joint member, causing the ball to enter between the track grooves of the outer joint member and the track grooves of the inner joint member. A method for incorporating a ball into a fixed constant velocity universal joint, wherein when the inner joint member is tilted relative to the outer joint member from the side with a larger operating angle to the side with a smaller operating angle, a cage retaining portion that rotates while maintaining a tilt angle of half the operating angle is brought into contact with the cage from the rear side in the tilting direction.

5. The method for assembling a ball into a fixed constant velocity universal joint according to claim 4, wherein the cage retaining portion is kept in contact with the cage from the rear side in the tilting direction from the start of tilting the inner joint member from the side with a larger operating angle to the side with a smaller operating angle relative to the outer joint member until the operating angle becomes 0°.

6. The method for assembling a ball into a fixed constant velocity universal joint according to claim 4, wherein when the inner joint member is tilted relative to the outer joint member from the side with a smaller operating angle to the side with a larger operating angle, the cage retaining portion is brought into contact with the cage from the side that is ahead in the tilting direction.

7. A method for installing a ball in a fixed constant velocity universal joint according to claim 4, applicable to the installation of the first ball.

8. The method for installing a ball in a fixed constant velocity universal joint according to claim 4, wherein the track groove of the outer joint member has a first track groove portion having a ball trajectory centerline in the shape of an arc that is convex to the outer diameter side, and a second track groove portion that is continuous with the first track groove portion on one axial side and has a ball trajectory centerline in the shape of an arc that is convex to the inner diameter side, and the track groove of the inner joint member has a first track groove portion having a ball trajectory centerline in the shape of an arc that is convex to the outer diameter side, and a second track groove portion that is continuous with the first track groove portion on the other axial side and has a ball trajectory centerline in the shape of an arc that is convex to the inner diameter side, and when the inner joint member is tilted with respect to the outer joint member from the side with a large operating angle to the side with a small operating angle, the cage retaining portion is kept in contact with the cage from the rear side in the tilting direction until the ball installed in the pocket exposed from the outer joint member enters the track groove of the outer joint member and crosses the boundary between the first track groove portion and the second track groove portion.

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