JP2008075821A - Fixed type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To smoothly operate a fixed type constant velocity universal joint having an inner ring guide groove provided with two circular arcs of different center of curvature. <P>SOLUTION: A sub circular arc C22 is inscribed in a main circular arc C21 at a boundary P between the main circular arc C21 and the sub circular arc C22 which compose an inner ring ball center locus C2. Thereby, the inner ring ball center locus C2 is formed into a stepless smooth shape. That is, since the inner ring guide grove 2b is formed into a stepless smooth shape, a ball 4 is smoothly moved on the inner ring guide groove 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixed type constant velocity universal joint that connects a drive-side rotation shaft and a driven-side rotation shaft, and can transmit torque at a constant angular velocity even when both the shafts form an angle.

  Fixed type constant velocity universal joints are used for power transmission of various industrial machines including automobiles. For example, a fixed type constant velocity universal joint disclosed in Patent Document 1 is connected to an outer joint member, an inner joint member held on the inner periphery of the outer joint member so as to be able to transmit torque, and an inner joint member. A shaft projecting from the opening of the member; and torque transmitting balls arranged one by one on a plurality of ball tracks formed by cooperation of the guide groove of the outer joint member and the guide groove of the inner joint member.

  In this constant velocity universal joint, the center of curvature of the guide groove of the outer joint member and the center of curvature of the guide groove of the inner joint member are offset by an equal distance from the joint center to the opposite side in the axial direction. The transmission ball is held in place. The ball track formed by the cooperation of the guide groove of the outer joint member and the guide groove of the inner joint member has a wedge shape opened toward the joint opening side. In addition, the joint opening side said here means the side from which the shaft protruded from the opening of the outer joint member, and the opposite side in the axial direction is called the joint back side (the same applies to the following description).

JP 2006-84008 A

  In such a fixed type constant velocity universal joint, if the operating angle is increased, the ball must be taken out from the guide groove of the outer joint member. Japanese Patent Application No. 2005-140162 filed earlier by the present applicant proposes a fixed type constant velocity universal joint in which the joint back side portion of the guide groove of the inner joint member is an arc whose center of curvature is the joint center. As a result, even when a large operating angle is taken, the center position of the ball is not separated from the center of the joint, so even if the ball goes out of the guide groove of the outer joint member, the cage and the guide groove of the inner joint member A ball can be held between them.

  In the above high-angle constant velocity universal joint, the guide groove of the inner joint member is formed by two arcs having different centers of curvature. For this reason, a step is formed at the boundary between the two arcs, the ball does not move smoothly on the guide groove, and there is a risk of rattling when the joint is operated.

  In addition, as described above, the ball track is formed in a wedge shape that opens toward the joint opening side, so that the ball receives a drag force from the guide groove toward the joint opening side. Force to push out to the side. In order to securely hold the cage against this force, the inner peripheral spherical surface of the outer joint member holding the cage may be extended to the joint opening side to enlarge the region holding the cage. However, if the outer joint member is extended toward the joint opening side, the interference position between the shaft and the opening end of the outer joint member is accelerated, and the limit operating angle of the joint may be reduced.

  An object of the present invention is to smoothly operate a fixed type constant velocity universal joint having two arcs having different curvature centers in a guide groove.

  Another object of the present invention is to provide a fixed type constant velocity universal joint that can reliably hold a cage while maintaining an operating angle.

  In order to solve the above-described problems, the present invention includes an outer joint member in which a plurality of guide grooves extending in the axial direction are formed on a spherical inner peripheral surface, and a plurality of guide grooves extending in the axial direction on a spherical outer peripheral surface. A plurality of balls formed by cooperation of the formed inner joint member, the shaft connected to the inner joint member and protruding from the opening of the outer joint member, and the guide groove of the outer joint member and the guide groove of the inner joint member In a fixed type constant velocity universal joint provided with a track, one torque transmission ball disposed on each ball track, and a cage for holding the torque transmission ball, the ball track is spaced apart in the radial direction between the opposing guide grooves. A wedge shape narrowed toward the joint opening side, and the ball center locus in the guide groove of the inner joint member has a main arc and a sub-arc having a center of curvature different from the main arc and having a smaller radius of curvature than the main arc. With this The main arc and the secondary arc boundaries, sub arc, characterized in that inscribed in the main arc.

  As described above, in the fixed type constant velocity universal joint of the present invention, the auxiliary arc is inscribed in the main arc at the boundary between the main arc and the auxiliary arc constituting the ball center locus in the guide groove of the inner joint member. The ball center locus in the groove continues smoothly. That is, since the guide groove is formed in a smooth shape without a step, the ball can be smoothly moved on the guide groove.

  Further, the ball track was formed in a wedge shape in which the radial interval between the opposing guide grooves was narrowed toward the joint opening side. As a result, a force is applied to the ball to push the cage toward the inner side of the joint, and the cage is held in the inner side spherical surface of the outer joint member against this force. Even if the inner side spherical surface of this outer joint member is extended, it does not affect the operating angle of the joint. Therefore, the cage should be securely held inside the outer joint member while maintaining the operating angle of the joint. Can do.

  In this fixed type constant velocity universal joint, the ball center locus in the guide groove of the outer joint member has the same radius as the main arc, and is equidistant from the joint center to the opposite side in the axial direction with respect to the center of curvature of the main arc. When the arc is provided with the center of curvature at the offset point, the torque transmission ball can be held at a predetermined position when the operating angle of the joint is 0 °. Further, by arranging the center of curvature of the arc of the ball center locus in the guide groove of the outer joint member on the back side of the joint from the center of curvature of the main arc of the ball center locus in the guide groove of the inner joint member, the ball track is connected to the joint. It can be made into the wedge shape narrowed toward the opening side.

  In addition, if a secondary arc is formed on the back side of the main arc joint in the ball center trajectory in the guide groove of the inner joint member, the center position of the ball does not move away from the joint center even when a large operating angle is taken. Can be held on the guide groove side of the inner joint member. Therefore, the ball can be taken out from the guide groove of the outer joint member without dropping off, and the operating angle of the joint can be increased.

  As described above, according to the present invention, it is possible to smoothly operate the fixed type constant velocity universal joint having two arcs having different curvature centers in the guide groove.

  Further, according to the present invention, a fixed type constant velocity universal joint capable of reliably holding the cage while maintaining the operating angle is obtained.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows a fixed type constant velocity universal joint according to the present invention. FIG. 1 (A) shows a state where the operating angle is 0 °, and FIG. 1 (B) shows a state where the limit operating angle (60 °) is taken. is there. The fixed type constant velocity universal joint includes an outer joint member 1 in which a plurality of (for example, eight) curved guide grooves 1b are formed on the inner peripheral spherical surface 1a in the axial direction, and a plurality of (for example, eight) outer peripheral spherical surfaces 2a. ) And the inner joint member 2 having a spline (or serration) hole 2c and one end of the spline hole 2c of the inner joint member 2 are fitted to each other to open the outer joint member. The shaft 3 protruding from the portion, the guide groove 1b of the outer joint member 1 and the guide groove 2b of the inner joint member 2 are arranged one by one on a plurality of (for example, eight) ball tracks T formed in cooperation. The torque transmitting ball 4 and the cage 5 for holding the ball 4 are configured. The number of guide grooves is not limited to 8, and may be 9, 10, 11, 12,.

  A guide groove 1b (hereinafter referred to as an outer ring guide groove 1b) of the outer joint member 1 is formed in an arc shape, and a guide portion 1c opened radially outward is formed on the joint opening side. A guide groove 2b (hereinafter referred to as an inner ring guide groove 2b) of the inner joint member 2 includes a main arc portion 2b1 and a sub-arc portion 2b2 formed on the joint back side of the main arc portion 2b1.

Hereinafter, the shape of the inner ring guide groove 2b will be described based on the ball center locus of the inner ring guide groove 2b (hereinafter, the inner ring ball center locus C2) with reference to FIG. The inner ring ball center locus C2 includes a main arc C21 corresponding to the main arc portion 2b1 of the inner ring guide groove 2b and a sub arc C22 corresponding to the sub arc portion 2b2. The ball center locus (hereinafter, outer ring ball center locus, not shown) of the outer ring guide groove 1b is formed in an arc shape, and its radius of curvature is equal to the radius of curvature of the main arc C21 of the inner ring ball center locus C2. Further, the center of curvature O ₂ of the main arc C21 of the inner race ball centroid C2, the center of curvature O ₁ of the outer race ball center trajectory, equidistant only axially offset opposite side of the joint center O, and the center of curvature O ₂ is disposed on the joint opening side than the center of curvature O _1. Thereby, the ball track T has a wedge shape in which the radial interval between the guide grooves 1b and 2b facing the joint opening side is narrowed. Further, the centers of curvature O ₁ and O ₂ are equally offset in the direction in which the radius of curvature becomes longer. Thereby, since the groove depth of the outer ring guide groove 1b can be increased, it is possible to prevent the ball 4 from climbing up due to a torque load and to reduce the surface pressure that the inner ring guide groove 2b receives from the ball 4.

Secondary arc C22 curvature center O ₃ of the inner ring ball centroid C2 is offset in the direction of the radius of curvature is shorter than the radius of curvature of the main arc C21, and, connecting the center of curvature O ₂ of the boundary portion P and the main arc C21 Provided on a straight line. As a result, the secondary arc C22 of the inner ring ball center locus C2 is inscribed in the main arc C21 at the boundary P with the main arc C21. Therefore, the boundary between the main arc C21 and the secondary arc C22 has a smooth shape without a step. Can be formed. That is, since the inner ring guide groove 2b is formed in a smooth shape without a step, the ball 4 can be moved smoothly on the inner ring guide groove 2b, and the joint can be operated smoothly.

  The cage 5 is formed of an annular member, and the outer peripheral surface thereof is an outer peripheral spherical surface 5 a that is in sliding contact with the inner peripheral spherical surface 1 a of the outer joint member 1, and the inner peripheral surface is in sliding contact with the outer peripheral spherical surface 2 a of the inner joint member 2. The inner peripheral spherical surface 5b is used. The centers of curvature of the outer peripheral spherical surface 5a and the inner peripheral spherical surface 5b of the cage 5 are all joint centers O. The same number of windows 5c as the balls 4 are formed through the peripheral wall of the cage 5 by grinding or milling. The shape of the window 5c is, for example, a rectangle, and is formed at equal intervals in the circumferential direction of the cage 5.

  An inner diameter surface on the joint opening side of the cage 5 is a cylindrical surface 5d having a constant inner diameter over a predetermined width, and a retaining ring 7 (a circlip) is fitted into a groove 5d1 formed in the cylindrical surface 5d. The guide ring 6 is fitted into a narrow annular wedge space formed inside the retaining ring 7 and up to the window 5c of the cage 5. The guide ring 6 has an inner peripheral surface fitted to the spherical outer peripheral surface 2 a of the inner joint member 2 and an outer peripheral surface fitted to the cylindrical surface 5 d of the cage 5. Further, the outer end of the guide ring 6 comes into contact with the inner surface of the retaining ring 7. A certain gap is secured between the inner end of the guide ring 6 and the ball 4.

  The window 5 c of the cage 5 has an outer peripheral side window opening dimension smaller than the diameter of the ball 4. That is, the ball guide surfaces facing the axial direction of the cage 5 are linearly parallel to each other with an interval equal to the ball diameter, but the outer diameter side of the ball guide surface is slightly narrower than the ball diameter. It becomes a constriction before. 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 shape that matches the outer peripheral curvature of the ball.

The constant velocity universal joint according to the present invention is configured as described above, and when the outer joint member 1 and the inner joint member 2 are at the operating angle of 0 ° in FIG. The center O ₁ and the center of curvature O ₂ of the main arc C 21 of the inner ring ball center locus C ₂ are offset and are held in a plane including the joint center O and perpendicular to the rotation axis. Transmission takes place.

  In the state where the outer joint member 1 and the inner joint member 2 are bent to the limit operating angle θ as shown in FIG. 1B, the shaft 3 contacts the open end of the outer joint member 1. The torque transmission ball 4 is oriented in a plane that bisects the angle θ by the cage 5, thereby ensuring constant velocity of the joint.

  In the state shown in FIG. 1B, some of the balls 4 come out of the outer ring guide groove 1b and come into contact with the sub-arc part 2b2 of the inner ring guide groove 2b. At this time, as described above, the radius of curvature of the secondary arc C22 of the ball center locus C2 corresponding to the secondary arc portion 2b2 is shorter than the radius of curvature of the main arc C21. I'm not away. Therefore, the ball 4 can be held between the inner ring guide groove 2 b and the cage 5. Further, as described above, by setting the window opening size of the window 5c of the cage 5 to be smaller than the ball diameter, the ball 4 can be moved by the cage 5 to the inner ring guide groove 2b even outside the outer joint member 1. You can hold it to the side. As described above, the ball 4 can be taken out from the guide groove 1b of the outer joint member 1 without dropping off, and the operating angle of the joint can be increased. Further, by forming the guide portion 1c at the opening end of the outer ring guide groove 1b, when the ball 4 that has come out of the outer ring guide groove 1b returns to the outer ring guide groove 1b again, the ball 4 and the outer joint member 1 Interference can be avoided, and the joint can be operated smoothly.

  Further, since the ball track T forms a wedge shape which is closed toward the joint opening side, the ball 4 and the guide grooves 1b and 2b are in contact with each other at a portion on the joint opening side with respect to the plane connecting the ball centers. As a result, the ball 4 always receives a drag force directed from the guide grooves 1b and 2b toward the inner side of the joint. Along with this, a force directed toward the joint back side is applied to the cage 5, and the cage 5 is held and held in the joint back side region of the inner circumferential spherical surface 1 a of the outer joint member 1 against this force. The Even if the inner peripheral spherical surface 1a of the outer joint member 1 is extended to the back side of the joint, the operating angle of the joint is not affected. Therefore, the cage 5 can be reliably held while maintaining the operating angle of the joint. .

(A) is sectional drawing which shows the state in which the fixed type constant velocity universal joint which concerns on this invention is an operating angle of 0 degree, (B) is sectional drawing which shows the state which took the limit operating angle (60 degrees). Sectional drawing of the inner side coupling member 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer joint member 1a Inner spherical surface 1b Outer ring guide groove 1c Guide part 2 Inner joint member 2a Outer spherical surface 2b Inner ring guide groove 2b1 Main arc 2b2 Sub arc 3 Shaft 4 Ball 5 Cage C2 Inner ring ball center locus C21 Main arc part O ₂ Center of curvature C22 Subarc part O ₃ Center of curvature O Joint center O ₁ Center of curvature of outer ring ball center locus P Boundary part T Ball track

Claims (3)

Connected to the outer joint member formed with a plurality of guide grooves extending in the axial direction on the spherical inner peripheral surface, the inner joint member formed with the plurality of guide grooves extending in the axial direction on the spherical outer peripheral surface, and the inner joint member And a plurality of ball tracks formed by cooperation of the shaft protruding from the opening of the outer joint member, the guide groove of the outer joint member and the guide groove of the inner joint member, and one ball track. In a fixed type constant velocity universal joint including a torque transmission ball and a cage for holding the torque transmission ball,
The ball track has a wedge shape in which the radial interval between the opposing guide grooves is narrowed toward the joint opening side,
The ball center locus in the guide groove of the inner joint member includes a main arc and a sub-arc having a center of curvature different from that of the main arc and having a smaller radius of curvature than the main arc, and a boundary portion between the main arc and the sub-arc A fixed type constant velocity universal joint characterized in that the secondary arc is inscribed in the main arc.   The ball center trajectory in the guide groove of the outer joint member has the same radius as the main arc of the ball center trajectory in the guide groove of the inner joint member, and the axial center is opposite to the curvature center of the main arc from the joint center. An arc having a center of curvature at a point offset by a distance, and the curvature center of the arc of the ball center locus in the guide groove of the outer joint member is the curvature of the main arc of the ball center locus in the guide groove of the inner joint member The fixed type constant velocity universal joint according to claim 1, wherein the fixed type constant velocity universal joint according to claim 1, wherein the fixed type constant velocity universal joint is arranged on the deeper side of the joint than the center.   3. The fixed type constant velocity universal joint according to claim 1, wherein the secondary arc is formed on the inner side of the joint of the main arc in a ball center locus in the guide groove of the inner joint member.

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