JP4515377B2 - Fixed type constant velocity universal joint - Google Patents

Description

  The present invention relates to a fixed type constant velocity universal joint capable of a high bending angle and used for power transmission of automobiles and various industrial machines.

  A fixed type constant velocity universal joint is generally used for an axle connecting portion of a drive shaft of an automobile and a shaft bending connecting portion of a steering shaft. As this fixed type constant velocity universal joint, conventionally, a zepper type constant velocity universal joint and an undercut free type (hereinafter referred to as UJ type) constant velocity universal joint are known. The Zepper type constant velocity universal joint is an arc having the same radius centered at a point where the ball center locus of each guide groove of the outer ring and the inner ring is equidistant from the joint center in both directions on the joint axis. That is, the ball center trajectory is a meridian of a pair of isobaric spheres centered on a point that is equidistant from the joint center on both sides in the axial direction (see Patent Document 1). Further, the center of the inner spherical surface of the outer ring and the center of the outer spherical surface of the inner ring coincide with the center of the joint.

 On the other hand, the UJ type constant velocity universal joint was invented in order to make the operating angle higher than the maximum bending angle of the Zepper type constant velocity universal joint. Of the arc of the meridian of the mold, the opening side portion of the outer ring is a straight line parallel to the joint axis from the cross section perpendicular to the axis passing through the joint center (see Patent Document 2).

US Patent No. 2046584 JP-A-53-65547

  In the fixed type constant velocity universal joint as described above, the maximum bending angle is limited by the interference between the end of the outer ring and the shaft connected to the inner ring. Due to this limitation, the maximum bending angle of the above-mentioned Zepper type constant velocity universal joint is limited to about 48 °, and the maximum bending angle of the UJ type constant velocity universal joint is limited to about 52 °.

  An object of the present invention is to provide a fixed type constant velocity universal joint capable of realizing a higher operating angle than conventional ones.

  In order to solve the above problems, the present invention provides an outer ring having a plurality of guide grooves extending in the axial direction on the inner peripheral spherical surface, an inner ring having a plurality of guide grooves extending in the axial direction on the outer peripheral spherical surface, and a guide groove for the outer ring. In a fixed type constant velocity universal joint comprising a torque transmitting ball disposed on each of a plurality of ball tracks formed in cooperation with a guide groove of an inner ring, and a cage for holding the ball, The ball center locus of the guide groove of the outer ring includes a linear portion having a gradient with respect to the center axis, and the ball center locus of the guide groove of the inner ring is a straight portion of the ball center locus of the guide groove of the outer ring with respect to the center axis. A ball center trajectory of the guide groove of the outer ring, comprising a straight line portion having an equal gradient and a different gradient, and an arc portion centered on the outer peripheral spherical surface of the inner ring extending from both ends of the straight line portion. And the guide groove of the inner ring And the length of the straight part of the ball center locus of the guide groove of the outer ring is equal to the length of the straight part of the ball center locus of the guide ring of the inner ring. It is shorter than the length.

  Thus, in the fixed type constant velocity universal joint of the present invention, the length of the linear portion of the ball center locus of the guide groove of the outer ring is made shorter than the length of the linear portion of the ball center locus of the guide groove of the inner ring, The maximum bending angle limited by the interference between the one end portion of the outer ring and the shaft connected to the inner ring can be widened.

  In the present invention, since the ball center locus of the guide groove of the outer ring is constituted by a straight line portion, the guide groove of the outer ring can be easily processed. Therefore, the manufacturing cost can be reduced as compared with the outer ring of the constant velocity universal joint having a curved guide groove.

  For example, the inner peripheral surface and the outer peripheral surface of the cage may have a spherical shape centered on the joint center. Alternatively, when the spherical shape is centered on a point offset by an equal distance on the opposite side in the axial direction across the joint center, a wider operating range of the joint can be obtained.

  When the joint is bent at a wide angle, the ball comes off the guide groove of the outer ring. At this time, if the ball guide surface of the cage window is parallel to the radial direction, the ball falls out and loses the function of the constant velocity universal joint. If the outside diameter side window opening dimension of the cage window that accommodates the ball is made smaller than the diameter of the ball, the ball does not fall off and is always held on the guide groove side of the inner ring. Can be avoided.

  As described above, when the ball guide surface of the cage is narrowed inward on the outer diameter side, the ball cannot be inserted into the window inner surface from the cage outer diameter side when the joint is assembled. It will be inserted into the window from the side. Then, since the inner ring must be inserted into the cage in the axial direction, the inner diameter surface that leads from one end surface of the cage to the window that accommodates the ball needs to be a cylindrical surface. After inserting the inner ring into the inner circumference of the cage, a guide ring for slidingly guiding the spherical outer circumferential surface of the inner ring to the cylindrical surface of the inner circumference of the cage, and a retaining ring for retaining the guide ring are attached. Prevent the inner ring from being removed from the cage.

  On the other hand, if the outside diameter side window opening dimension of the cage is made smaller than the ball diameter by a member separate from the cage, the ball can be inserted into the cage window from the outside diameter side. .

  Further, when the portion corresponding to the straight portion of the ball center locus of the inner ring guide groove and the portion corresponding to the arc portion are formed by separate members, a straight guide groove and an arc guide groove are formed in the inner ring. Since a complicated process can be divided and performed, manufacturing is facilitated.

  As described above, according to the present invention, it is possible to obtain a fixed type constant velocity universal joint capable of realizing a higher working angle than the conventional one.

  A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2 show a fixed type constant velocity universal joint 10 according to a first embodiment of the present invention. FIG. 1 shows a state where the operating angle is 0 °, and FIG. 2 shows a limit operating angle (about 60 °). It is in the state taken. The fixed type constant velocity universal joint includes a cylindrical outer ring 1 having both ends opened in the axial direction on the inner circumferential spherical surface 1a and eight curved guide grooves formed on the outer circumferential spherical surface 2a. 2b is formed in the axial direction, and has an inner ring 2 having a spline (or serration) hole 2c, a shaft 3 connected to the inner ring 2 by fitting one end of the spline hole 2c, a guide groove 1b of the outer ring 1 and an inner ring Two guide grooves 2b cooperate to form torque transmitting balls 4 arranged one by one on eight ball tracks, and a cage 5 for holding the balls 4. In the present embodiment, the case where the number of ball tracks is eight is shown, but any other number may be set.

  The centers of curvature of the outer peripheral spherical surface 5a and the inner peripheral spherical surface 5b of the cage 5 are all coincident with the joint center. Further, the inner peripheral spherical surface 1a of the outer ring 1 and the outer peripheral spherical surface 2a of the inner ring 2 are in sliding contact with the outer peripheral spherical surface 5a and the inner peripheral spherical surface 5b of the cage 5, respectively, and both centers coincide with the joint center.

  FIG. 3 shows an enlarged view of the ball center locus of the guide groove in FIG. A ball center locus C1 (hereinafter referred to as an outer ring ball center locus C1) of the guide groove 1b of the outer ring 1 is a linear portion ab (inclination angle: −θ) slightly inclined with respect to the center axis H. Further, a ball center locus C2 of the guide groove 2b of the inner ring 2 (hereinafter referred to as an inner ring ball center locus C2) is a straight portion cd (inclination) having the same magnitude as the straight portion ab with respect to the central axis H and having a different gradient. Angle: θ) and arc portions ce and df extending a predetermined length from both ends of the straight line portion cd. The arc portions ce and df are arcs having a radius R with the center of the outer peripheral spherical surface 2a of the inner ring 2 being the center of the joint O in the present embodiment. The outer ring ball center locus C1 and the inner ring ball center locus C2 need only have the straight portion ab and the straight portion cd having the same magnitude and different gradient with respect to the central axis H. For example, the straight portion ab is the center. It may be set so that it has a positive inclination angle (θ) with respect to the axis H and the linear portion cd has a negative inclination angle (−θ) with respect to the central axis H. Further, the straight line part ab and the straight line part cd intersect on the axis-perpendicular section V of the joint center. Furthermore, the length L1 of the straight line part ab is shorter than the length L2 of the straight line part cd (L1 <L2).

  Further, in the present invention, since the entire outer ring ball center locus C1 is composed of the straight portion ab, the processing of the guide groove 1b of the outer ring 1 can be easily performed by, for example, turning or cold forging. Therefore, it can be manufactured at a lower cost than the processing of the guide groove having a curved center locus. Further, since the inner ring 2 also has the straight portion cd, the entire guide groove can be manufactured at a lower cost than a spherical zeppa type constant velocity universal joint.

  As shown in FIG. 1, in the case where the two axes are not angularly displaced, that is, in a state where the rotation axes of the two axes are in a straight line, the center of all the torque transmission balls 4 includes a joint center O and is in a plane perpendicular to the rotation axis. It is in. When the outer ring 1 and the inner ring 2 are displaced by, for example, an angle φ, the cage 5 causes the torque transmitting ball 4 to be oriented in a plane that bisects the angle φ, thereby ensuring constant velocity of the joint. (See FIG. 2).

  The cage 5 is formed of an annular member, and the same number of windows 6 as the balls 4 are formed through the peripheral wall of the cage 5 by grinding or milling. The window 6 has a rectangular shape, for example, and is formed at equal intervals in the circumferential direction of the cage 5.

  As shown in FIG. 4 in an enlarged manner, the inner peripheral surface leading to the window 6 from one end face of the cage 5, in this embodiment, from the end face on the shaft 3 protruding side (right side in the figure) is as shown in FIG. The cylindrical surface 5c has a constant inner diameter over a predetermined width, and a retaining ring 7 (circlip) is fitted into a groove 5d formed in the cylindrical surface 5c. A guide ring 8 is fitted into a narrow annular wedge space formed inside the retaining ring 7 and up to the window 6 of the cage 5. The guide ring 8 has an inner peripheral surface fitted to the spherical outer peripheral surface 2 a of the inner ring 2 and an outer peripheral surface fitted to the cylindrical inner peripheral surface 5 c of the cage 5. Further, the outer end face (right side in the figure) of the guide ring 8 abuts on the inner surface (left end face in the figure) of the retaining ring 7, and there is a constant gap between the inner end (left end in the figure) and the window 6. The gap is secured.

  As shown in FIG. 4B, the ball guide surface of the window 6 of the cage 5 has a narrow outer diameter side. That is, in the axial cross section at the maximum diameter portion of the ball 4 shown in FIGS. 4A and 4B, the inner diameter side of the ball guide surface is slightly wider or the same size as the ball diameter and parallel to each other. Although it is the straight line shape 6a in the radial direction, the outer diameter side of the ball guide surface is tapered so as to be narrower than the ball diameter. The tapered portion may be formed by an inclined straight line, but in order to reduce the contact surface pressure with the ball, it is preferable to form a concave arc portion 6b that matches the outer peripheral curvature of the ball.

  The fixed type constant velocity universal joint according to the present invention is configured as described above, and the straight portion ab of the outer ring ball center locus C1 is shorter than the straight portion cd of the inner ring ball center locus C2 (L1 <L2, see FIG. 3). Therefore, a wide operating angle can be taken in the state of the maximum bending angle shown in FIG. On the other hand, when the straight portion ab of the outer ring ball center locus C1 is longer than the straight portion cd of the inner ring ball center locus C2 (L1> L2), as shown by the broken line, the operating angle is smaller than the product of the present invention. Become.

  Another advantage of L1 <L2 is that when the ball 4 passes through the inflection points of the arc portions ce, df and the straight portion cd in the inner ring ball center locus C2, the ball 4 has already guided the outer ring 1. Since it is out of the groove 1b, even if there is a step in the production of the guide groove 1b at the inflection point, it does not become an obstacle.

  Even when a large operating angle is taken, the arcs ce and df of the inner ring ball center locus C2 are arcs centered on the outer peripheral spherical surface 2a of the inner ring 2, that is, the joint center O in this embodiment, and therefore the ball 4 The center position is not far from the joint center. Further, by making the window opening dimension of the outer diameter side of the window 6 of the cage 5 smaller than the ball diameter, the ball 4 protruding outward from the outer ring 1 at a high operating angle is brought to the guide groove 2b side of the inner ring 2. You can keep it. Accordingly, it is possible to prevent the ball 4 from dropping from the cage 5 even at a high operating angle. Note that, at a high operating angle, the ball that is detached from the outer ring 1 does not play a role of transmitting torque, but torque is transmitted by another ball held in the guide groove 1 b of the outer ring 1.

  As shown in FIG. 2, the straight line portion ab of the outer ring ball center locus C1 and the straight line portion cd of the inner ring ball center locus C2 intersect on the axis-perpendicular section V of the joint center, and the straight portion ab and the straight line portion cd are The ball 4 can be held in the cross section V, that is, the cross-section perpendicular to the axis V of the joint center O by forming a straight line having the same magnitude and different gradient with respect to the central axis. By holding the balls 4 at a fixed position, the cage 5 can be held within the axis perpendicular to the joint center O at a joint operating angle of 0 °.

  The first embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the fixed type constant velocity universal joint 20 according to the second embodiment of the present invention shown in FIG. 5, the concave arc portion 6b of the window 6 of the cage 5 is formed by the cage 5 and a separate member 5e. . Thereby, it becomes possible to insert the ball 4 into the window 6 of the cage 5 from the outer diameter side.

  In the fixed type constant velocity universal joint 30 according to the third embodiment of the present invention shown in FIG. 6, a portion corresponding to the straight line portion cd of the inner ring ball center locus C2 and portions corresponding to the arc portions ce and df are respectively provided. It is formed by separate members 21, 22 and 23. Thereby, since the complicated process which forms the guide groove 2b which consists of a linear part and a circular arc part in the outer periphery of the inner ring | wheel 2 can be divided | segmented and performed, manufacture is simplified.

In the fixed type constant velocity universal joint 40 according to the fourth embodiment of the present invention shown in FIG. 7, the curvature centers O ₁ and O ₂ of the outer peripheral spherical surface 5a and the inner peripheral spherical surface 5b of the cage 5 are at the joint center O. On the other hand, they are offset by an equal distance on the opposite side in the axial direction. Thus, by offsetting the centers of curvature O ₁ and O ₂ of the outer peripheral spherical surface 5a and the inner peripheral spherical surface 5b of the cage 5, the operating angle of the joint can be made wider.

It is sectional drawing which shows the state of the operating angle of 0 degree of the fixed type constant velocity universal joint 10 which concerns on the 1st Embodiment of this invention. 3 is a cross-sectional view showing a state of a limit operating angle (about 60 °) of the fixed type constant velocity universal joint 10. It is the figure which expanded and showed the ball center locus | trajectory of the guide groove. (A) is an enlarged sectional view around the ball, (B) is a sectional view exaggerating the ball guide surface of the cage window. It is sectional drawing of the fixed type constant velocity universal joint 20 which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the fixed type constant velocity universal joint 30 which concerns on the 3rd Embodiment of this invention. It is sectional drawing of the fixed type constant velocity universal joint 40 which concerns on the 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Inner ring 3 Shaft 4 Torque transmission ball 5 Cage 6 Window 7 Retaining ring 8 Guide ring 10 Fixed type constant velocity universal joint C1 Ball center locus of outer ring guide groove (outer ring ball center locus)
C2 Ball center locus of inner ring guide groove (Inner ring ball center locus)
ab Straight part of outer ring ball center locus cd Straight part of inner ring ball center locus ce, df Arc part of inner ring ball center locus H Center axis O Joint center V

Claims (7)

An outer ring having a plurality of guide grooves extending in the axial direction on the inner peripheral spherical surface, an inner ring having a plurality of guide grooves extending in the axial direction on the outer peripheral spherical surface, and a guide groove of the outer ring and a guide groove of the inner ring cooperate with each other. In a fixed type constant velocity universal joint comprising a torque transmitting ball arranged one by one on a plurality of ball tracks to be formed, and a cage for holding the ball,
The ball center locus of the guide groove of the outer ring includes a linear portion having a gradient with respect to a center axis, and the ball center locus of the guide groove of the inner ring is a straight portion of the ball center locus of the guide groove of the outer ring with respect to the center axis. And a circular arc centered on the center of the outer peripheral spherical surface of the inner ring extending from both ends of the linear part, and the ball center of the guide groove of the outer ring The straight line portion of the locus and the straight line portion of the ball center locus of the guide groove of the inner ring intersect on a cross section perpendicular to the axis of the joint center,
A fixed type constant velocity universal joint characterized in that the length of the straight portion of the ball center locus of the guide groove of the outer ring is shorter than the length of the straight portion of the ball center locus of the guide groove of the inner ring.   The fixed type constant velocity universal joint according to claim 1, wherein an inner peripheral surface and an outer peripheral surface of the cage are spherical in shape with a joint center as a center.   2. The fixed type constant velocity universal joint according to claim 1, wherein the inner peripheral surface and the outer peripheral surface of the cage have a spherical shape centered on a point offset by an equal distance on the opposite side in the axial direction across the joint center.   The fixed type constant velocity universal joint according to claim 1, wherein an outside diameter side window opening size of a window for accommodating the ball of the cage is smaller than a diameter of the ball.   A cylindrical inner surface extending from one end surface of the cage to the window, a guide ring for slidingly guiding the spherical outer peripheral surface of the inner ring to the cylindrical surface, and a stopper for preventing the guide ring from coming off The fixed type constant velocity universal joint according to claim 1, further comprising a ring.   2. The fixed type constant velocity universal joint according to claim 1, wherein an outside diameter side window opening dimension of the cage is made smaller than a diameter of the ball by a member separate from the cage. 2. The fixed type constant velocity universal joint according to claim 1, wherein a portion corresponding to the straight portion of the ball center locus of the guide groove of the inner ring and a portion corresponding to the arc portion are formed by separate members.

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