JP2014095404A - Stationary constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stationary constant velocity universal joint which is highly efficient with lower torque loss and less heat generation, excellent in durability, and capable of taking a high operating angle.SOLUTION: Track grooves 7 of an outside joint member 2 include first track groove parts 7a located on the corner side, and second track groove parts 7b located on the opening side. The first track groove parts each having a circular portion using a joint center O as a curvature center are inclined to an axis N-N of the joint in the peripheral direction, and the inclination directions of the first track groove parts adjacent to each other in the peripheral direction are opposite to each other. The second track groove parts each having a different shape from the first track groove part because of an increase in the effective track length are connected to the first track groove parts on the further opening side than the joint center O. Track grooves 9 of an inside joint member 3 are formed in mirror image symmetry to the track grooves of the outside joint member, pared therewith, on the basis of a joint center plane P in the state that an operating angle is 0°. Besides, onto the defined surfaces of the track grooves of the outside joint member, surface treatment is applied for reducing friction resistance to balls 4.

Description

  The present invention relates to a fixed type constant velocity universal joint, and more particularly, to a fixed type constant velocity universal joint that is used in a power transmission system of an automobile or various industrial machines and allows only angular displacement between two axes of a driving side and a driven side. About.

  For example, in a front drive shaft of an automobile, a sliding type constant velocity universal joint that allows angular displacement and axial displacement is normally incorporated on the inboard side (difference side), and the angle is on the outboard side (wheel side). A fixed constant velocity universal joint that allows only displacement is incorporated.

  FIG. 24 (a) shows a vertical sectional view of a Rzeppa constant velocity universal joint, which is an example of a fixed type constant velocity universal joint, at a working angle of 0 °, and FIG. The schematic diagram of the state which took the operating angle is shown. As shown in FIG. 24A, the constant velocity universal joint 101 mainly includes an outer joint member 102, an inner joint member 103, a ball 104, and a cage 105. Eight track grooves 107 are formed in the spherical inner peripheral surface 106 of the outer joint member 102 at equal intervals in the circumferential direction and along the axial direction, and the outer joint member is formed on the spherical outer peripheral surface 108 of the inner joint member 103. The track grooves 109 facing the track grooves 107 are formed at equal intervals in the circumferential direction and along the axial direction. A ball 104 for transmitting torque is interposed between the opposed track grooves 107 and 109, and the ball 104 is disposed between the spherical inner peripheral surface 106 of the outer joint member 102 and the spherical outer peripheral surface 108 of the inner joint member 103. It is held by the cage 105. The outer periphery of the outer joint member 102 and the outer periphery of the shaft connected to the inner joint member 103 are covered with boots, and the joint internal space covered with the boots is filled with grease as a lubricant (not shown).

  As shown in FIG. 24A, the spherical outer peripheral surface 112 of the cage 105 that fits with the spherical inner peripheral surface 106 of the outer joint member 102 and the cage 105 that fits with the spherical outer peripheral surface 108 of the inner joint member 103. The center of curvature of the spherical inner peripheral surface 113 is formed at the joint center O. On the other hand, the center of curvature Oo of the ball track center line x of the track groove 107 of the outer joint member 102 and the center of curvature Oi of the ball track center line y of the track groove 109 of the inner joint member 103 are in the joint center O. In contrast, they are offset equidistantly in the axial direction. Thus, when the joint takes an operating angle, the ball 104 is always guided on a plane that bisects the angle formed by the axes of the outer joint member 102 and the inner joint member 103. Therefore, the rotational torque is transmitted at a constant speed between the two shafts (between the outer joint member 102 and the inner joint member 103).

  As shown in FIG. 24B, the maximum operating angle θmax of the fixed type constant velocity universal joint 101 depends on the angle at which the inlet chamfer 110 provided at the open end of the outer joint member 102 and the shaft 111 interfere. The shaft diameter d of the shaft 111 is determined for each joint size in order to ensure an allowable transmission torque. If the entrance chamfer 110 is made large, the length of the track groove 107 (hereinafter referred to as an effective track length) of the outer joint member 102 with which the ball 104 abuts is insufficient, and the ball 104 falls out of the track groove 107 and rotational torque is increased. It becomes impossible to communicate. Therefore, how to set the inlet chamfer 110 while securing the effective track length of the outer joint member 102 is an important factor in securing the operating angle. In the Zepper type constant velocity universal joint 101, the center of curvature Oo of the ball track center line x of the track groove 107 of the outer joint member 102 is offset to the opening side, which is advantageous in terms of the maximum operating angle, The angle θmax is about 47 °.

  The 8-ball type Rzeppa constant velocity universal joint 101 has a smaller track offset, a larger number of balls, and a smaller diameter than the conventional 6-ball constant velocity universal joint. Lightweight, compact, and highly efficient constant velocity universal joints with low torque loss. However, as shown in FIG. 25, each wedge angle α formed between the opposing track grooves 107 and 109 (the contact point between the ball 104 and the track grooves 107 and 109 as shown in the figure) at an operating angle of 0 °. Is positioned toward the opening side of the outer joint member 102, and the spherical inner periphery of the outer joint member 102 is caused by the axial force W acting on the ball 104 from the track grooves 107 and 109. The load acting on the contact portion between the surface 106 and the spherical outer circumferential surface 112 of the cage 105 and the contact portion between the spherical outer circumferential surface 108 of the inner joint member 103 and the spherical inner circumferential surface 113 of the cage 105 is directed toward a certain direction. Occur. Therefore, as illustrated, the outer joint member 102 and the inner joint member 103 are in contact with the cage 105 at the part J and the part I, respectively, and there is a limit to further increase in efficiency and heat generation.

  Therefore, in order to achieve further higher efficiency and lower heat generation, a track groove intersecting type fixed constant velocity universal joint as shown in FIG. 26 has been proposed (for example, Patent Document 1). FIG. 26 is a longitudinal sectional view of the equivalent velocity universal joint in an operating angle of 0 °. As shown in FIG. 26, the constant velocity universal joint 121 mainly includes an outer joint member 122, an inner joint member 123, a ball 124, and a cage 125. Although not shown in detail, in this constant velocity universal joint 121, the plane including the ball track center line x of the eight track grooves 127 of the outer joint member 122 is inclined with respect to the joint axis nn. The inclination directions are formed in opposite directions by track grooves 127 adjacent in the circumferential direction. The ball trajectory center line y of the track groove 129 of the inner joint member 123 is a plane P including the joint center O at the operating angle of 0 ° (hereinafter, referred to as “joint center plane P at the operating angle of 0 °”). Is defined as a mirror image symmetry with respect to the ball trajectory center line x of the track groove 127 which forms a pair of the outer joint member 122.

  As shown in FIG. 26, the track groove 127 formed on the spherical inner peripheral surface 126 of the outer joint member 122 extends in an arc shape along the axial direction, and the center of curvature thereof is located at the joint center O. The track groove 129 formed on the spherical outer peripheral surface 128 of the inner joint member 123 extends in an arc shape along the axial direction, and the center of curvature thereof is located at the joint center O. Balls 124 that transmit torque are respectively interposed at the intersections between the track grooves 127 of the outer joint member 122 and the track grooves 129 of the inner joint member 123, and the balls 124 are spherical inner peripheral surfaces 126 of the outer joint member 122. And a retainer 125 disposed between the spherical outer peripheral surfaces 128 of the inner joint member 123. The center of curvature of the spherical outer peripheral surface 132 and the spherical inner peripheral surface 133 that are fitted to the spherical inner peripheral surface 126 of the outer joint member 122 and the spherical outer peripheral surface 128 of the inner joint member 123, respectively, of the cage 125 are joints. It is formed at the center O. In this constant velocity universal joint 121, when the opposing track grooves 127 and 129 intersect each other and the ball 124 is interposed at the intersecting portion, the joint takes an operating angle, so that the outer joint member 122 and the inner joint member 123 The ball 124 is always guided on a plane that bisects the angle formed by both axes. Therefore, rotational torque is transmitted at a constant speed between the two shafts.

  In the fixed constant velocity universal joint 121 of the track groove intersection type, the track grooves 127 and 129 of the outer joint member 122 and the inner joint member 123 are track grooves adjacent to each other in the circumferential direction, and are inclined in directions opposite to each other. Therefore, a force in the opposite direction from the ball 124 acts on a pocket portion (a portion that holds the ball 124) 125a adjacent to the circumferential direction of the cage 125. The cage 125 is stabilized at the joint center O position by the forces in the opposite directions. Therefore, the contact force between the spherical outer circumferential surface 132 of the cage 125 and the spherical inner circumferential surface 126 of the outer joint member 122 and the contact between the spherical inner circumferential surface 133 of the cage 125 and the spherical outer circumferential surface 128 of the inner joint member 123. The force is suppressed, and the joint operates smoothly at high loads and at high speeds. As a result, torque loss and heat generation are suppressed, and durability is improved.

  The fixed type constant velocity universal joint 121 is excellent as a low heat generation joint, but has the following problems. Details thereof will be described with reference to FIGS. As shown in FIG. 27A, when the joint takes a high operating angle θ, the center Ob of the ball 124 moves to a position of θ / 2 with respect to the joint center plane P in a state where the operating angle is 0 °. Since the ball 124 and the track groove 127 are angular contacts having a contact angle, the contact point between the ball 124 and the track groove 127 is located on the broken line shown in FIG. The axial position of the contact point between the ball 124 and the track groove 127 passes through the center Ob of the ball 124 and lies on a plane t perpendicular to the ball trajectory center line x. In the constant velocity universal joint 121, when the inlet chamfer 130 of the outer joint member 122 is enlarged, the ball 124 is dropped from the track groove 127 at a high operating angle θ beyond the inlet chamfer 130. This is because the center of curvature of the arc-shaped track groove 127 is arranged at the joint center O, and therefore the axial distance δ between the center Ob of the ball 124 and the contact point s is large, and the effective track length is This is because there is a shortage. Therefore, there is a problem that a high operating angle cannot be achieved.

JP 2009-250365 A

  In view of the above-described problems of the prior art, the present inventors set the track groove on the opening side from the joint center O to a straight line in order to increase the angle in the fixed constant velocity universal joint of the track groove intersecting type disclosed in Patent Document 1. We considered to make it. This constant velocity universal joint will be described with reference to a longitudinal sectional view shown in FIG. 22A and a front view [right side view of FIG. 22A] shown in FIG. As shown in FIG. 22 (a), in this constant velocity universal joint 141, the track groove 147 of the outer joint member 142 has its back side and opening side at the joint center plane at a working angle of 0 ° as a boundary. An arc-shaped track groove 147a and a linear track groove 147b having the joint center O as the center of curvature are provided. On the other hand, the track groove 149 of the inner joint member 143 has an arcuate track groove 149a and a straight track groove 149b with the joint center O as the center of curvature at the opening side and the back side of the joint center plane, respectively. It is said.

  As shown in FIG. 22 (b), the track grooves 147 and 149 are track grooves 147A, 147B and 149A, 149B that are inclined in the circumferential direction with respect to the axis of the joint and are inclined in the circumferential direction. They are in opposite directions. Then, balls 144 are arranged at the intersections of the track grooves 147A, 149A and 147B, 149B that form pairs of the outer joint member 142 and the inner joint member 143. Therefore, when the joint members 142 and 143 rotate relative to each other at an operating angle of 0 ° as shown in the figure, the wedge angle formed between the track grooves 147A and 149A and the direction between the opening 147B and 149B are formed. The direction in which the wedge angle opens is opposite to each other, and forces in opposite directions from the balls 144 act on the pocket portions 145 a adjacent to the circumferential direction of the cage 145. Due to the forces in the opposite directions, the cage 145 is stabilized at the joint center O position. Therefore, the contact force between the spherical outer circumferential surface 152 of the cage 145 and the spherical inner circumferential surface 146 of the outer joint member 142 and the contact between the spherical inner circumferential surface 153 of the cage 145 and the spherical outer circumferential surface 148 of the inner joint member 143. The force is suppressed, and the joint operates smoothly at high loads and at high speeds. As a result, torque loss and heat generation are suppressed, and durability is improved.

  As described above, in the track groove 147 of the outer joint member 142, when the linear track groove portion 147b is formed in the region on the opening side from the joint center plane, the effective track length is increased to increase the operating angle. be able to. However, with the above-described configuration, it has been found that there are problems in terms of suppressing torque loss and heat generation of the joints when taking frequently used operating angles. The reason for this will be described with reference to FIG.

  Since the track grooves 147 and 149 and the ball 144 are normally in contact with each other at a contact angle (about 30 ° to 45 °), the track grooves 147 and 149 and the ball 144 are connected to each other as shown in FIG. Contact is made on the side surfaces (positions indicated by broken lines in the figure) of the track grooves 147 and 149 slightly apart from the bottom of the groove 149. When the joint takes an operating angle, each ball 144 has a wedge angle component (not shown) due to the intersection of the track grooves 147 and 149 and a wedge angle due to the joint radial expansion between the groove bottoms of the track grooves 147 and 149. Both ingredients act. Among the wedge angle components, the wedge angle component due to the intersection of the track grooves 147 and 149 is such that the inclination directions of the track grooves 147 and 149 are alternately opposite to each other, and the balls 144 are transferred to the pocket portions 145a of the cage 145. Because forces in opposite directions are applied, they cancel each other out and balance the forces.

  However, as shown in FIG. 23, the wedge angle component due to the joint radial expansion between the groove bottoms of the track grooves 147 and 149 is 0 ° to 90 ° and 270 ° to 360 ° in FIG. The ball 144 in the phase range is positioned in the linear track groove portions 147b and 149b, and a force toward the opening acts on the ball 144 in the phase range due to the wedge angle component α1 that opens toward the opening. On the other hand, since the ball 144 in the phase range of 90 ° to 270 ° is positioned in the arc-shaped track groove portions 147a and 149a, the wedge angle component α2 generated by the radial expansion of the joint is 0 in the balls in this phase range. Therefore, the pushing force of the ball 144 is not generated. Therefore, for each ball 144, when the wedge angle component due to the intersection of the track grooves 147 and 149 and the wedge angle component due to the joint radial expansion between the groove bottoms of the track grooves 147 and 149 are combined, the cage 145 The forces acting from the balls 144 are not balanced in the pocket portions 145a, and the contact portion between the spherical outer peripheral surface 152 of the cage 145 and the spherical inner peripheral surface 146 of the outer joint member 142, and the spherical inner peripheral surface 153 of the cage 145 There arises a problem that the contact force at the contact portion with the spherical outer peripheral surface 148 of the inner joint member 143 cannot be reduced. In particular, it has been found that there is a significant problem in terms of torque loss and suppression of heat generation in the range of operating angles that are frequently used, including normal angles.

  In addition, the frictional resistance at the contact portion between the joint components is reduced not only within the range of operating angles including the service angle, but also within the range of operating angles with relatively low use frequency (high operating angle). If possible, it is possible to further increase the efficiency of the constant velocity universal joint by suppressing torque loss and heat generation. Therefore, it is considered that there is room for improvement in this respect.

  In view of the above circumstances, it is an object of the present invention to provide a fixed type constant velocity universal joint capable of taking a high operating angle while having low torque loss and heat generation, high efficiency and excellent durability. To do.

  As a result of various studies to achieve the above object, the inventors of the present invention have found that the track grooves intersect in the circumferential direction and reduce the torque loss and heat generation to achieve high efficiency and the center of the joint. An arc-shaped first track groove having a center of curvature with no offset in the axial direction covers a range of frequently used operating angles, while increasing the effective track length with respect to the maximum operating angle. A new idea of covering a range of a high operating angle that is less frequently used by the second track groove portion having a shape different from that of the groove portion has been reached. In addition to this, at least one of the contact portions (sliding contact portions) between the joint constituent members is provided with a means for reducing the frictional resistance at the contact portion in order to further increase the efficiency. Inspired.

  That is, the present invention devised to achieve the above object includes an outer joint member having a plurality of track grooves extending in the axial direction on a spherical inner peripheral surface and having an opening side and a back side that are separated in the axial direction. The inner joint member having a plurality of track grooves that are paired with the track grooves of the outer joint member on the spherical outer peripheral surface, and the torque is interposed between the track groove of the outer joint member and the track groove of the inner joint member. A plurality of balls for transmission, a pocket portion for holding the balls, and a spherical outer peripheral surface and a cage having a spherical inner peripheral surface which are fitted to the spherical inner peripheral surface of the outer joint member and the spherical outer peripheral surface of the inner joint member, respectively. In the fixed constant velocity universal joint provided, the track groove of the outer joint member is composed of a first track groove portion located on the back side and a second track groove portion located on the opening side, and the first track groove portion is formed at the center of the joint. And has an arc-shaped portion having a center of curvature with no offset in the axial direction, and is inclined in the circumferential direction with respect to the axis of the joint, and the inclined direction is opposite to each other in the first track groove portions adjacent in the circumferential direction. And the second track groove portion has a shape different from that of the first track groove portion to increase the effective track length with respect to the maximum operating angle, and is connected to the first track groove portion on the opening side of the joint center, The track groove of the inner joint member is formed mirror-symmetrically with the track groove that forms the pair of the outer joint member with respect to the joint center plane at the operating angle of 0 °. Spherical inner peripheral surface of joint member, track groove defining surface of inner joint member, spherical outer peripheral surface of inner joint member, outer surface of ball, spherical outer peripheral surface of cage, spherical inner peripheral surface of cage and cage Pocket part At least one surface selected from the group of defined surfaces is subjected to a surface treatment for reducing a frictional resistance with a counterpart member that moves relative to the surface in contact with the at least one surface.

  The “joint axis” in the present invention means a longitudinal axis serving as the center of rotation of the joint, and refers to the joint axis NN in an embodiment described later. In addition, the “joint center plane at an operating angle of 0 °” is synonymous with a plane including the joint center at an operating angle of 0 ° and extending in a direction orthogonal to the axis of the joint.

  In the present invention, in the track groove of the outer joint member, the second track groove portion for increasing the effective track length provided on the opening side is connected to the first track groove portion on the opening side from the joint center (inner side). In the track groove of the joint member, the second track groove portion provided on the back side is connected to the first track groove portion on the back side from the joint center). That is, in the fixed type constant velocity universal joint according to the present invention, it means that the formation range of the first track groove portion is expanded as compared with the constant velocity universal joint 141 described with reference to FIG. Therefore, high efficiency can be achieved by suppressing torque loss and heat generation in the normal operating angle range. In addition, if the form of the second track groove portion (inclination mode, curvature mode, etc. with respect to the joint axis) is appropriately selected, the length of the second track groove portion (effective track length) can be effectively increased to increase the operating angle. Can be achieved.

  Further, in the present invention, at least one surface selected from the group of surfaces listed above is subjected to a surface treatment for reducing the frictional resistance with the counterpart member that moves relative to the surface. If it does in this way, the frictional resistance in at least 1 contact part can be reduced among the contact parts of the members which exist (formed) in the constant velocity universal joint. Therefore, the effect of suppressing torque loss and heat generation is further increased, and further high efficiency can be realized. Therefore, according to the present invention, it is possible to realize a fixed type constant velocity universal joint that can take a high operating angle while having low torque loss and heat generation, high efficiency, and excellent durability. As the “surface treatment”, any treatment can be selected as long as it can reduce the frictional resistance with the counterpart member. Representative examples include lubricant film formation processing (lubricant coating) containing solid lubricant, barrel processing to form countless microrecesses as oil reservoirs, resin film formation processing (resin coating), shot peening and shot blasting, etc. Surface modification treatment can be performed.

  When the angle formed by the straight line connecting the connection point between the first track groove portion and the second track groove portion and the joint center with respect to the joint center plane in the state where the operating angle is 0 ° is β, this angle β is determined depending on the use condition, etc. Thus, the efficiency of the fixed type constant velocity universal joint can be appropriately realized. In particular, considering the normal operating angle range of constant velocity universal joints for automobiles, the angle β can be set to 3 to 10 ° so that it can be widely used for various types of vehicles. However, the angle β in the present invention is defined as the smallest angle among the angles formed by the straight line on the joint center plane in the state where the operating angle is 0 °.

  By disposing the center of curvature of the arc-shaped portion of the first track groove portion on the axis of the joint, the track groove depth can be made uniform and processing can be facilitated. Also, by offsetting the center of curvature of the arc-shaped portion of the first track groove portion in the radial direction from the axis of the joint, the track groove depth on the back side of the joint can be adjusted, and the optimum track groove depth can be adjusted. Can be secured.

  The centers of curvature of the spherical outer peripheral surface and the spherical inner peripheral surface of the cage can be arranged at positions offset to the opening side and the back side, respectively, with respect to the joint center. In this way, the thickness of the cage can be gradually increased toward the opening side, so that the strength of the cage can be secured particularly at a high operating angle, and the reliability of the joint can be improved.

  The second track groove portion 7b may have an arc-shaped portion. In this case, the arc-shaped portion is curved at a position radially outward from the first track groove portion and offset to the opening side from the joint center. It can have a center. Thereby, the effective track length can be increased and the maximum operating angle can be increased.

  The second track groove portion may have a linear portion, and this linear portion is preferably formed so as to be inclined so as to approach the joint axis as it goes to the opening side. In this way, since the size of the wedge angle of the linear track groove at the time of a high operating angle can be suppressed, the strength of the cage can be ensured. The entire area of the second track groove portion may be constituted by a linear portion. In this case, the second track groove portion can be formed as a tangent to the first track groove portion. In this way, since the first track groove portion and the second track groove portion can be formed in a simple form, the processing of the track grooves for both joint members can be facilitated, and the manufacturing cost can be reduced.

  In the above configuration, if the number of balls is 8, 10, or 12, a fixed, constant velocity universal joint that is light, compact, highly efficient and has a high operating angle, and eventually a drive shaft for an automobile is realized. can do.

  As described above, according to the present invention, a compact fixed type constant velocity universal joint capable of taking a high operating angle while having an extremely high efficiency with little torque loss and heat generation and an excellent durability life is realized. be able to.

(A) A figure is a fragmentary longitudinal cross-section of the fixed type constant velocity universal joint which concerns on 1st Embodiment of this invention, (b) figure is a front view of the fixed type constant velocity universal joint. (A) A figure is a fragmentary longitudinal cross-sectional view of the outer joint member which comprises the fixed type constant velocity universal joint shown in FIG. 1, (b) The figure is a front view of the outer joint member. FIGS. (A) to (c) are a rear view, a side view, and a front view, respectively, of an inner joint member that constitutes the fixed type constant velocity universal joint shown in FIG. It is a fragmentary longitudinal cross-section which shows the detail of the track groove of the outer joint member shown in FIG. It is a longitudinal cross-sectional view which shows the detail of the track groove of the inner joint member shown in FIG. It is an outline figure showing the state where a joint took the maximum operating angle. It is a schematic perspective view of an outer joint member. It is a schematic perspective view of an inner joint member. It is a schematic perspective view of the outer joint member which concerns on a modification. It is a schematic perspective view of the inner joint member which concerns on a modification. It is a schematic perspective view of a holder | retainer. It is a schematic perspective view of the holder | retainer which concerns on a modification. It is a schematic perspective view of the holder | retainer which concerns on a modification. FIG. 2 is a partial longitudinal sectional view of a drive shaft of an automobile provided with the fixed type constant velocity universal joint shown in FIG. 1. It is a longitudinal cross-sectional view of the outer joint member used with the fixed type constant velocity universal joint which concerns on 2nd Embodiment of this invention. It is a partial longitudinal cross-sectional view of the outer joint member used with the fixed type constant velocity universal joint which concerns on 3rd Embodiment of this invention. FIG. 17 is a schematic diagram illustrating a state in which the constant velocity universal joint including the outer joint member illustrated in FIG. 16 has a maximum operating angle. (A) is a schematic diagram showing a contact state between a ball and a track groove when the constant velocity universal joint shown in FIG. 17 takes a maximum operating angle, and (b) is an enlarged view of a main part of FIG. is there. (A) It is a figure which shows the wedge angle of the state where the constant velocity universal joint shown in FIG. 17 took the maximum operating angle. It is a fragmentary longitudinal cross-sectional view of the outer joint member used with the fixed type constant velocity universal joint which concerns on 4th Embodiment of this invention. It is a longitudinal cross-sectional view of the holder | retainer used with the fixed type constant velocity universal joint which concerns on 5th Embodiment of this invention. It is a figure explaining the technical knowledge in the process leading to the present invention. It is a figure explaining the technical knowledge in the process leading to the present invention. It is a longitudinal cross-sectional view of the fixed type constant velocity universal joint of a prior art. It is a longitudinal cross-sectional view which shows the state of the spherical contact of the constant velocity universal joint shown in FIG. It is a longitudinal cross-sectional view of the fixed type constant velocity universal joint of a prior art. (A) is a longitudinal sectional view showing a state in which the constant velocity universal joint shown in FIG. 26 has a high operating angle, and (b) is an enlarged view of a main part of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 (a) shows a partial longitudinal sectional view of a fixed type constant velocity universal joint 1 (hereinafter also simply referred to as “constant velocity universal joint 1”) according to the first embodiment of the present invention, and FIG. Fig. 1 shows a front view of the constant velocity universal joint 1 [a right side view of Fig. 1 (a)]. The constant velocity universal joint 1 mainly includes an outer joint member 2, an inner joint member 3, a ball 4 and a cage 5.

  As shown in FIGS. 2 (a) and 2 (b), eight track grooves 7 extending in the axial direction are formed on the spherical inner peripheral surface 6 of the outer joint member 2, and each track groove 7 is formed of a joint. The angle γ is inclined in the circumferential direction with respect to the axis NN, and the inclined direction is formed in opposite directions by the track grooves 7A and 7B adjacent in the circumferential direction. Further, as shown in FIGS. 3A to 3C, eight track grooves 9 extending in the axial direction are formed on the spherical outer peripheral surface 8 of the inner joint member 3. The angle γ is inclined in the circumferential direction with respect to the joint axis NN, and the inclined direction is formed in opposite directions by the track grooves 9A and 9B adjacent in the circumferential direction. One ball 4 is disposed at each intersection of the track grooves 7 and 9 that form a pair of the outer joint member 2 and the inner joint member 3. In FIG. 1 (a), for the track grooves 7 and 9, the cross sections in the plane M shown in FIG. 2 (a) and the plane Q shown in FIG. 3 (b) are rotated to the inclination angle γ = 0 °. It is shown in the state.

  In the following, the term “ball trajectory centerline” is used in order to accurately indicate the form of the track grooves 7 and 9 (inclined state, curved state, etc.). The center line of the ball trajectory means a locus drawn by the center of the ball 4 when the ball 4 moves along the track grooves 7 and 9. Therefore, the shape of the track grooves 7 and 9 is the same as the shape of the ball track center line.

  As shown in FIG. 1A and FIG. 2A, the track groove 7 of the outer joint member 2 has a ball track center line X. More specifically, the track groove 7 is provided on the back side, the first track groove portion 7a having an arc-shaped ball trajectory center line Xa with the joint center O as the center of curvature, and the first track groove portion provided on the opening side. And a second track groove portion 7b having an arc-shaped ball track center line Xb curved in the opposite direction to 7a. The ball track center line Xb of the second track groove portion 7b is connected to the ball track center line Xa of the first track groove portion 7a. Are connected smoothly. Further, as shown in FIGS. 1A and 3B, the track groove 9 of the inner joint member 3 has a ball track center line Y. The track groove 9 is provided on the opening side and has a first track groove portion 9a having an arc-shaped ball trajectory center line Ya with the joint center O as the center of curvature, and provided on the back side, opposite to the first track groove portion 9a. The second track groove portion 9b having an arc-shaped ball track center line Yb curved in the direction, and the ball track center line Yb of the second track groove portion 9b is smoothly connected to the ball track center line Ya of the first track groove portion 9a. Has been. Thus, the ball track center lines Xa and Ya of the first track groove portions 7a and 9a and the ball track center lines Xb and Yb of the second track groove portions 7b and 9b are different from each other.

  By arranging the centers of curvature of the ball track center lines Xa and Ya of the first track groove portions 7a and 9a on the joint center O, that is, the joint axis NN, the track groove depth can be made uniform. And processing can be facilitated.

  Although detailed illustration is omitted, the cross-sectional shape (axial orthogonal cross-section) of the track grooves 7 and 9 is formed in an elliptical shape or a Gothic arch shape, and the track grooves 7 and 9 and the ball 4 have a contact angle (30 The contact is a so-called angular contact having a contact angle of approximately 45 ° to 45 °. Accordingly, the ball 4 is in contact with the side surfaces of the track grooves 7 and 9 that are slightly separated from the bottoms of the track grooves 7 and 9.

  Here, the reference numerals of the track grooves will be supplemented. When referring to the entire track groove of the outer joint member 2, reference numeral 7 is attached, and reference numerals 7a and 7b are attached to the first and second track groove portions, respectively. When discriminating track grooves having different inclination directions, reference numeral 7A denotes a track groove inclined to one side in the circumferential direction with respect to the joint axis NN, and the other side in the circumferential direction with respect to the joint axis NN. Reference numeral 7B is given to the track groove inclined in the direction. Reference numerals 7Aa and 7Ba are attached to the first track groove portions of the track grooves 7A and 7B, and reference numerals 7Ab and 7Bb are attached to the second track groove portions of the track grooves 7A and 7B, respectively. The track grooves 9 of the inner joint member 3 to be described later are also given the same reference numerals.

  Referring to the partial longitudinal section of the outer joint member 2 shown in FIG. 2A and the front view of the outer joint member 2 shown in FIG. 2B [the right side surface of FIG. 2A], the outer joint member 2 The state in which the track grooves 7 are inclined in the circumferential direction with respect to the joint axis NN will be described. As shown in FIG. 2A, the plane M including the ball track center line X of the track groove 7A and the joint center O is inclined by an angle γ with respect to the joint axis NN. The track groove 7B adjacent to the track groove 7A in the circumferential direction is not shown in the figure, but the plane M including the ball track center line X and the joint center O has a track groove with respect to the joint axis NN. It is inclined by an angle γ in the direction opposite to the inclination direction of 7A. In the present embodiment, the entire region of the ball track center line X of the track groove 7A, that is, both the ball track center line Xa of the first track groove portion 7a and the ball track center line Xb of the second track groove portion 7b are formed on the plane M. Has been. However, the present invention is not limited to this, and a mode in which only the ball trajectory center line Xa of the first track groove portion 7a is included in the plane M can also be implemented. Therefore, the plane M including at least the ball track center line Xa of the first track groove portion 7a and the joint center O is inclined in the circumferential direction with respect to the joint axis NN, and the inclined direction is adjacent to the circumferential direction in the first direction. The track grooves 7a may be formed in opposite directions.

  Next, based on the rear view, the side view, and the front view of the inner joint member 3 shown in FIGS. 3A to 3C, the track groove 9 of the inner joint member 3 is circumferential with respect to the joint axis NN. The state inclined in the direction will be described. As shown in FIG. 3B, the plane Q including the ball track center line Y and the joint center O of the track groove 9A is inclined by an angle γ with respect to the joint axis NN. The track groove 9B adjacent to the track groove 9A in the circumferential direction is not shown in the figure, but the plane Q including the ball track center line Y and the joint center O has a track groove 9A with respect to the joint axis NN. It is inclined by an angle γ in the opposite direction to the inclination direction. The inclination angle γ is preferably set in the range of 4 ° to 12 ° in consideration of the operability of the constant velocity universal joint 1 and the spherical surface width F on the closest side of the track groove of the inner joint member 3.

  Similar to the outer joint member 2 described above, in this embodiment, the entire region of the ball track center line Y of the track groove 9A, that is, the ball track center line Ya of the first track groove portion 9a and the ball track center line of the second track groove portion 9b. Both Yb are formed on the plane Q. However, the present invention is not limited to this, and a mode in which only the ball trajectory center line Ya of the first track groove portion 9a is included in the plane Q can also be implemented. Accordingly, at least the first track groove portion 9a including the track center line Ya and the plane Q including the joint center O is inclined in the circumferential direction with respect to the joint axis NN, and the inclined direction is adjacent to the circumferential direction in the first track. It suffices if the grooves 9a are formed in opposite directions.

  From the above configuration, the track groove 9 of the inner joint member 3 is formed mirror-symmetrically with the track groove 7 that forms a pair of the outer joint member 2 with reference to the joint center plane P in the state where the operating angle is 0 °.

  Next, based on FIG. 4, the detail of the track groove seen from the longitudinal cross-section of the outer joint member 2 is demonstrated. 4 is a cross-sectional view of the track groove 7A shown in FIG. 2A viewed from a plane M including the ball track center line X and the joint center O, that is, the circumferential direction with respect to the joint axis NN. It is sectional drawing in the plane containing inclination-axis N'-N 'inclined only by angle (gamma). FIG. 4 shows only the track groove 7A among the track grooves 7A and 7B having different inclination directions.

  As shown in FIG. 4, a track groove 7 </ b> A having a ball track center line X is formed in the spherical inner peripheral surface 6 of the outer joint member 2 along the axial direction. The track groove 7A includes a first track groove portion 7Aa having an arc-shaped ball track center line Xa centering on the joint center O and a radially outer side of the first track groove portion 7Aa (the ball track center line Xa thereof), and The second track groove portion 7Ab has an arc-shaped ball trajectory center line Xb having a center of curvature at a point Oo1 offset from the joint center O to the opening side. Therefore, the arc-shaped ball track center line Xb of the second track groove portion 7Ab is curved in the direction opposite to the ball track center line Xa of the first track groove portion 7Aa. The opening-side end A of the ball track center line Xa of the first track groove portion 7Aa is a point where a straight line connecting the joint center O and the point Oo1 intersects with the ball track center line X. The ball track center line Xb of the track groove 7Ab is smoothly connected. Let L be the straight line connecting the end A and the joint center O.

  As shown in the figure, the angle β ′ formed by the perpendicular line K and the straight line L at the joint center O of the inclined axis N′-N ′ projected on the plane M [see FIG. 2A] is the axis N− of the joint. It is inclined with respect to N by an angle γ. The perpendicular line K is on the joint center plane P with an operating angle of 0 °. Therefore, the angle β formed by the straight line L with respect to the joint center plane P in the state where the operating angle is 0 ° has a relationship of sin β = sin β ′ × cos γ. In the above, the first track groove portion 7Aa and the second track groove portion 7Ab of the outer joint member 2 are each formed by a single arc, but the present invention is not limited thereto, and is formed by a plurality of arcs in consideration of the track groove depth and the like. May be.

  Similarly, details of the track grooves of the inner joint member 3 will be described with reference to FIG. FIG. 5 is a cross-sectional view of the track groove 9A shown in FIG. 3B viewed along a plane Q including the ball track center line Y and the joint center O, that is, an angle in the circumferential direction with respect to the joint axis NN. The cross section in the plane containing the inclination axis N′-N ′ inclined by γ is shown. FIG. 5 shows only the track groove 9A among the track grooves 9A and 9B having different inclination directions.

  A track groove 9 </ b> A having a ball track center line Y is formed in the spherical outer peripheral surface 8 of the inner joint member 3 along the axial direction. The track groove 9A includes a first track groove portion 9Aa having an arc-shaped ball track center line Ya centering on the joint center O, a radially outer side of the first track groove portion 9Aa (ball track center line Ya), and And a second track groove portion 9Ab having an arc-shaped ball trajectory center line Yb having a center of curvature at a point Oi1 offset from the joint center O to the back side. The rear end B of the ball track center line Ya of the first track groove 9Aa is a point where a straight line connecting the joint center O and the point Oi1 intersects the ball track center line Y. The ball track center line Yb of the track groove 9Ab is smoothly connected. Let R be the straight line connecting the end B and the joint center O.

  As shown in the figure, the angle β ′ formed by the perpendicular line K and the straight line R at the joint center O of the tilt axis N′-N ′ projected on the plane Q [see FIG. 3B] is the joint axis N−. It is inclined with respect to N by an angle γ. The perpendicular line K is on the joint center plane P with an operating angle of 0 °. Therefore, the angle β formed by the straight line R with respect to the joint center plane P in the state where the operating angle is 0 ° has a relationship of sin β = sin β ′ × cos γ. Similarly to the track groove of the outer joint member 2 described above, the first track groove portion 9Aa and the second track groove portion 9Ab of the inner joint member 3 may each be formed by a plurality of arcs in consideration of the track groove depth and the like. Good.

  Next, an angle β formed by the straight lines L and R with respect to the joint center plane P in a state where the operating angle is 0 ° will be described. When the operating angle θ is taken, the ball 4 moves by θ / 2 with respect to the plane P of the outer joint member 2 and the inner joint member 3. The angle β is determined from ½ of the frequently used operating angle, and the range of the track groove with which the ball 4 contacts is determined within the frequently used operating angle range. Here, the operating angle that is frequently used is defined. First, the common angle of the joint refers to an operating angle generated in a fixed type constant velocity universal joint of the front drive shaft when the steering is in a straight traveling state in an automobile when one person rides on a horizontal and flat road surface. The service angle is usually selected and determined between 2 ° and 15 ° according to the design conditions for each vehicle type. The frequently used operating angle is not the high operating angle that occurs when the above-mentioned automobile is turned right or left at an intersection, for example, but the operating angle that occurs in a fixed constant velocity universal joint on a continuous curved road or the like. Okay, this is also determined according to the design conditions for each model. The operating angle that is frequently used is targeted at a maximum of 20 °. Thereby, the angle β formed by the straight lines L and R with respect to the joint center plane P in the state where the operating angle is 0 ° is set to 3 ° to 10 °. However, the angle β is not limited to 3 ° to 10 °, and can be appropriately set according to the design conditions of the vehicle type. If the angle β is set to 3 ° to 10 °, it can be used for various types of vehicles.

  With the angle β described above, in the outer joint member 2, the end A (FIG. 4) of the ball track center line Xa of the first track groove portion 7Aa moves to the most opening side along the axial direction when the operating angle is frequently used. It becomes the center position of the ball 4 at that time. Similarly, in the inner joint member 3, the end B (FIG. 5) of the ball track center line Ya of the first track groove 9 </ b> Aa is moved to the innermost side along the axial direction at the operating angle where the usage frequency is high. It becomes the center position of the ball 4. Since it is set in this way, in the range of operating angles where the frequency of use is high, the ball 4 has the first track groove portions 7Aa and 9Aa of the outer joint member 2 and the inner joint member 3, and the inclination direction is opposite to these. It is located within the range of the first track groove portions 7Ba and 9Ba (see FIGS. 2 and 3). In this case, a force in the opposite direction from the ball 4 acts on the pocket portion 5a adjacent to the circumferential direction of the cage 5, so that the cage 5 is stabilized at the position of the joint center O (see FIG. 1). For this reason, the contact force between the spherical outer peripheral surface 12 of the cage 5 and the spherical inner peripheral surface 6 of the outer joint member 2 and the contact between the spherical inner peripheral surface 13 of the cage 5 and the spherical outer peripheral surface 8 of the inner joint member 3. As a result of the force being suppressed and the joint being able to operate smoothly during high loads and high speed rotation, torque loss and heat generation are suppressed, and durability is improved.

  In the constant velocity universal joint 1 of the present embodiment described above, the clearance between the pocket 5a of the cage 5 and the ball 4 may be set. In this case, the clearance width of the clearance is preferably set to about 0 to 40 μm. By setting the clearance, the ball 4 held in the pocket portion 5a of the cage 5 can be operated smoothly, and torque loss can be further reduced.

  FIG. 6 shows a state in which the constant velocity universal joint 1 of the present embodiment has a maximum operating angle. As described above, the track groove 7A of the outer joint member 2 has a curvature at a point Oo1 on the opening side, radially outward of the ball track center line Xa of the first track groove portion 7Aa and offset from the joint center O to the opening side. An arc-shaped second track groove portion 7Ab is provided at the center. The effective track length can be increased and the maximum operating angle can be increased by the presence of the second track groove portion 7Ab in the compact design. Therefore, as shown in the drawing, even when the maximum operating angle θmax is set to a high angle of about 50 °, the contact state between the ball 4 and the track groove 7A (the second track groove portion 7Ab) with the necessary and sufficient entrance chamfer 10 provided. Can be secured.

  In the range of the high operating angle, the balls 4 arranged in the circumferential direction are temporarily placed in the first track groove portions 7Aa, 9Aa (7Ba, 9Ba) and the second track groove portions 7Ab, 9Ab (7Bb, 9Bb). Separated positions. Accordingly, the force acting from the balls 4 on the pockets 5a of the cage 5 is not balanced, and the contact portion between the spherical outer circumferential surface 12 of the cage 5 and the spherical inner circumferential surface 6 of the outer joint member 2, and the cage Although the contact force is generated at the contact portion between the spherical inner peripheral surface 13 of the inner peripheral member 5 and the spherical outer peripheral surface 8 of the inner joint member 3, the constant velocity universal joint 1 of the present embodiment is less frequently used in the high operating angle range. Overall, torque loss and heat generation can be suppressed. Therefore, it is possible to realize a compact fixed type constant velocity universal joint that has a small torque loss and heat generation, is highly efficient, can take a high operating angle, and is excellent in strength and durability at a high operating angle.

  The constant velocity universal joint 1 according to the embodiment of the present invention employs the following technical means in addition to the above-described configuration.

  Specifically, as shown in FIG. 7, in the outer joint member 2, a track groove 7 (7A) which is a portion (surface) where the relative movement with the ball 4 is repeated in a state where the ball 4 as a counterpart member is in contact with the outer joint member 2. 7B) is subjected to a surface treatment for reducing the frictional resistance with the ball 4 (the portion to be subjected to the surface treatment is a portion indicated by hatching. FIGS. 8 to 13 referred to in the following description). The same applies to the above). Examples of surface treatments include, for example, formation of a lubricant film containing a solid lubricant (lubricant coating), barrel treatment for forming numerous indentations as a reservoir of lubricating oil, resin film formation treatment (resin coating), and shot peening. And surface modification treatment such as shot blasting can be performed.

  Note that the surface treatment described above is performed in place of or in addition to the track groove 7 of the outer joint member 2, as shown in FIG. These may be applied to the defining surface of the track groove 9 (9A, 9B), which is a portion where the relative movement of is repeated.

  Further, the above surface treatment may be performed in addition to or in place of the defining surface of the track groove 7 of the outer joint member 2 and / or the track groove 9 of the inner joint member 3, (1) of the outer joint member 2, Spherical inner peripheral surface 6 (see FIG. 9) where sliding contact with the cage 5 is repeated, (2) Of the inner joint member 3, spherical outer peripheral surface 8 (FIG. 10) where sliding contact with the cage 5 is repeated (3) The outer surface (not shown) of the ball 4 in which friction with the track groove 7 of the outer joint member 2, the track groove 9 of the inner joint member 3, and the pocket portion 5a of the cage 5 is repeated (4). A spherical outer peripheral surface 12 (see FIG. 11) in which the sliding contact with the outer joint member 2 is repeated in the cage 5, and (5) a spherical shape in which the sliding contact with the inner joint member 3 is repeated in the cage 5. Inner peripheral surface 13 (see FIG. 12), (6) Among the cages 5, 4 and defining surface of the pocket portion 5a friction is repeated in (see FIG. 13. However, as shown in the figure, it is only the surface facing in the axial direction) may be subjected to such. In short, the above surface treatment may be applied to at least one of the surfaces where friction with the mating member is repeated, and the surface to be subjected to the above surface treatment takes into consideration the required efficiency and cost. May be selected as appropriate. The surface treatment described above can be similarly employed in the constant velocity universal joint 1 according to another embodiment described later.

  By applying the surface treatment as described above, not only within the range of operating angles that include frequent use, but also within the range of operating angles that are relatively infrequent (high operating angle), joint components The frictional resistance at the contact portion can be reduced. Thereby, torque loss and heat generation can be further suppressed, and further increase in efficiency and life of the fixed type constant velocity universal joint 1 can be achieved.

  FIG. 14 shows a front drive shaft 20 of an automobile incorporating the fixed type constant velocity universal joint 1 of the present embodiment. The fixed type constant velocity universal joint 1 is connected to one end of an intermediate shaft 11, and a sliding type constant velocity universal joint (in the illustrated example, a tripod type constant velocity universal joint) 15 is connected to the other end. Between the outer peripheral surface of the fixed type constant velocity universal joint 1 and the outer peripheral surface of the shaft 11, and between the outer peripheral surface of the sliding type constant velocity universal joint 15 and the outer peripheral surface of the shaft 11, respectively, bellows-like boots 16a and 16b. Is fastened and fixed by a boot band 18 (18a, 18b, 18c, 18d). Grease as a lubricant is sealed inside the joint. Since the fixed type constant velocity universal joint 1 of the present embodiment is used, a lightweight and compact automobile drive shaft 20 is realized that has low torque loss and heat generation, high efficiency, and a high operating angle. An automobile equipped with the drive shaft 20 can suppress fuel consumption by improving transmission efficiency.

  The constant velocity universal joint 1 according to the first embodiment of the present invention has been described above. However, the constant velocity universal joint 1 described above can be variously modified without departing from the gist of the present invention. is there. Hereinafter, a constant velocity universal joint according to another embodiment of the present invention will be described. In the following, a configuration different from the above-described first embodiment will be mainly described, and substantially the same as the first embodiment. The same reference numerals are given to members / parts having similar functions, and duplicate explanations are omitted.

  FIG. 15 is a partial cross-sectional view of an outer joint member used in a fixed type constant velocity universal joint according to a second embodiment of the present invention. More specifically, similar to FIG. 4, the center of the ball track of the track groove 7A is shown. It is the fragmentary sectional view of the outside joint member seen in plane M [refer to Drawing 2 (a)] containing line X and joint center O. The main difference between the constant velocity universal joint of this embodiment and the constant velocity universal joint of the first embodiment described above is that the center of curvature of the arc-shaped ball track center line of the first track groove portion is set to the joint axis NN. On the other hand, it is offset in the radial direction, and the configuration of the arc-shaped ball trajectory center line of the second track groove is adjusted accordingly.

The above difference will be described in detail with reference to FIG. 15. In this embodiment, the center of curvature Oo3 of the ball track center line Xa of the first track groove portion 7a of the outer joint member 2 is set with respect to the joint axis NN. Thus, it is positioned at a point offset by f _{2 in} the radial direction (there is no axial offset with respect to the joint center O). That is, it is offset by f ₂ in the radial direction on the joint center plane P in a state where the operating angle including the perpendicular K is 0 °. Accordingly, the curvature center Oo4 of the ball track center line Xb of the second track groove portion 7b is smooth to the end A of the ball track center line Xa of the first track groove portion 7a. The position has been adjusted to connect to. With this configuration, the depth of the track groove on the back side of the joint can be adjusted. Although not shown in the figure, the inner periphery of the outer joint member 2 is mirror-image-symmetrical with the track groove 7 that forms a pair of the outer joint member 2 on the basis of the joint center plane P at an operating angle of 0 °. The inner joint member 3 having the track groove 9, the ball 4 and the cage 5 [see FIG. 1 and the like] are incorporated, thereby completing a fixed type constant velocity universal joint.

  FIG. 16 is a partial cross-sectional view of an outer joint member used in a fixed type constant velocity universal joint according to a third embodiment of the present invention. More specifically, similar to FIG. 4, the center of the ball track of the track groove 7A is shown. It is the fragmentary sectional view of the outside joint member seen in plane M [refer to Drawing 2 (a)] containing line X and joint center O. The main difference between the constant velocity universal joint of this embodiment and the constant velocity universal joint of the first embodiment described above is that the second track groove portion is linear. FIG. 16 shows only the track groove 7A out of the track grooves 7A and 7B having different inclination directions as in FIG.

  The above difference will be described in detail with reference to FIG. 16. The track groove 7A of the outer joint member 2 in this embodiment has a first track having an arc-shaped ball trajectory center line Xa with the joint center O as the center of curvature. It consists of a groove 7Aa and a second track groove 7Ab having a linear ball track center line Xb. The ball track center line Xb of the second track groove 7Ab is smoothly tangent to the ball track center line Xa of the first track groove 7Aa. It is connected to the. Then, at the opening side end portion A of the ball track center line Xa of the first track groove portion 7Aa, the straight ball track center line Xb of the second track groove portion 7Ab is smoothly connected as a tangent line, and the end portion A Is positioned closer to the opening side than the joint center O, so that the linear second track groove portion 7Ab (the ball track center line Xb thereof) becomes the joint axis NN [FIG. (See (a)). Then, on the inner periphery of the outer joint member 2, as shown in FIGS. 17 and 18, the track groove 7 that forms a pair of the outer joint member 2 with reference to the joint center plane P in a state where the operating angle is 0 °. (7A) and the inner joint member 3 having the mirror-symmetrical track groove 9, the ball 4 and the cage 5 are incorporated, thereby completing the fixed type constant velocity universal joint. By adopting the configuration of the present embodiment, it is possible to ensure the effective track length at the maximum operating angle and to prevent the wedge angle from becoming excessive.

  FIG. 17 shows a state in which the constant velocity universal joint including the outer joint member 2 shown in FIG. 16 takes the maximum operating angle. As described above, the second track groove portion 7Ab having the straight ball track center line Xb is formed on the opening side of the track groove 7A of the outer joint member 2 of this embodiment. In the compact design, the presence of the second track groove portion 7Ab can ensure an effective track length at the maximum operating angle and suppress an excessive wedge angle. Therefore, as shown in the drawing, even when the maximum operating angle θmax is set to a high angle of about 50 °, the contact state between the ball 4 and the second track groove portion 7Ab can be ensured with the necessary and sufficient entrance chamfer 10 provided. .

  Further, the contact state between the track groove and the ball at the maximum operating angle of the constant velocity universal joint according to the present embodiment will be described in detail with reference to FIGS. As shown in FIG. 18A, when the joint takes the maximum operating angle θmax, the center Ob of the ball 4 moves to a position of θmax / 2 with respect to the joint center plane P in the state where the operating angle is 0 °. At this time, the contact point S between the ball 4 and the second track groove 7Ab is closest to the entrance chamfer 10. Since the ball track center line Xb of the second track groove 7Ab having a linear shape is connected as a tangent to the end A of the ball track center line Xa of the first track groove portion 7Aa having a circular arc shape, the outer joint member As it goes to the opening side of 2, it is inclined in a direction approaching the axis NN of the joint. As shown in an enlarged view in FIG. 18B, the contact point S between the ball 4 and the track groove 7Ab passes through the center Ob of the ball 4 and is located on a plane T perpendicular to the ball trajectory center line Xb. To do. Since the ball trajectory center line Xb is linear, the axial distance δ between the center Ob of the ball 4 and the contact point S is smaller than that of the conventional constant velocity universal joint 121 shown in FIG. Therefore, the effective track length is increased accordingly. Therefore, in this embodiment, a track margin U can be secured between the edge portion of the inlet chamfer 10 and the contact point S in a state where the maximum operating angle is taken, and the ball 4 and the track groove 7A (second A sufficient contact state with the track groove 7Ab) can be ensured.

  Next, the state of the wedge angle at the maximum operating angle of the constant velocity universal joint according to the present embodiment will be described with reference to FIGS. First, as shown in FIG. 19A, when the constant velocity universal joint 1 of the present embodiment takes the maximum operating angle θmax, the wedge angle α formed between the track grooves 7A and 9A is set in the rotational direction. The phase angle becomes largest at 300 ° to 360 ° [see FIG. 22B]. Since the straight ball track center line Xb of the second track groove portion 7Ab of the outer joint member 2 is connected as a tangent at the end A of the arc-shaped ball track center line Xa of the first track groove portion 7Aa, the operating angle is 0. In the state of 0 °, the outer joint member 2 is inclined in a direction approaching the joint axis NN as it goes toward the opening side. On the other hand, the linear ball track center line Yb of the second track groove 9Ab of the inner joint member 3 is inclined in the direction opposite to the linear ball track center line Xb of the outer joint member 2. Therefore, the second track groove portions 7Ab and 9Ab are formed so that the outer joint member 2 becomes narrower (the radial separation distance therebetween) in the state where the operating angle is 0 °. For this reason, the wedge angle α at the maximum operating angle can be reduced. As a result, the force that the ball 4 sandwiched between the linear second track groove portions 7Ab, 9Ab tries to jump out decreases, the pocket load of the cage 5 decreases, and the cage 5 at a high operating angle. The strength of the can be ensured.

  The reason why the wedge angle α at the maximum operating angle can be reduced will be specifically described with reference to FIG. FIG. 19B shows the second track groove portions of the outer joint member 2 and the inner joint member 3 of the constant velocity universal joint 1 according to the present embodiment by 7 Ab and 9 Ab. And the 2nd track groove part of the outer joint member of the constant velocity universal joint which concerns on the process which employ | adopted the structure of this embodiment and the inner joint member which concerns on the comparative example 1 is shown by 7Ab ', 9Ab', The second track groove portions of the outer joint member and the inner joint member of the constant velocity universal joint are denoted by 7Ab ″ and 9Ab ″. Comparative Example 1 is a constant velocity universal joint in which second track groove portions 7Ab ′ and 9Ab ′ are formed such that the groove bottom extends in parallel with the joint axis NN in a state where the operating angle is 0 °. In Example 2, the radial separation distance between the groove bottoms gradually increases toward the opening side of the outer joint member in the state where the operating angle is 0 ° (the distance increases as the groove bottom moves toward the opening side of the outer joint member. This is a constant velocity universal joint in which second track groove portions 7Ab ″ and 9Ab ″ are formed.

  As described above, in the constant velocity universal joint 1 of the present embodiment, the radial distance between the groove bottoms of the second track groove portions 7Ab and 9Ab in the state where the operating angle is 0 ° is directed toward the opening side of the outer joint member 2. It is formed to gradually narrow. Therefore, the wedge angle α at the maximum operating angle becomes small. On the other hand, in the constant velocity universal joint of Comparative Example 1, the groove bottoms of the second track groove portions 7Ab ′ and 9Ab ′ are formed in parallel with the axis NN of the joint at an operating angle of 0 °. The wedge angle α ′ at the maximum operating angle is larger than the wedge angle α of the present embodiment. Furthermore, in the constant velocity universal joint of Comparative Example 2, the second track is such that the radial distance between the groove bottoms of the second track groove portion in the state where the operating angle is 0 ° gradually increases toward the opening side of the outer joint member. Since the grooves 7Ab ″ and 9Ab ″ are formed, the wedge angle α ″ at the maximum operating angle is larger than the wedge angle α ′ at the maximum operating angle of Comparative Example 1. From the above, the present embodiment In the constant velocity universal joint 1, the wedge angle α at the maximum operating angle can be made smaller than those of the constant velocity universal joints according to Comparative Example 1 and Comparative Example 2. Comparative Example 1 in terms of the effective track length. Although the number of the comparative example 2 is increased, as a practical fixed type constant velocity universal joint, the present embodiment capable of ensuring both the effective track length at the maximum operating angle and suppressing the wedge angle is preferable.

  FIG. 20 is a partial cross-sectional view of an outer joint member used in a fixed type constant velocity universal joint according to a fourth embodiment of the present invention. More specifically, similar to FIG. 4, the center of the ball track of the track groove 7A is shown. It is the fragmentary sectional view of the outside joint member seen in plane M [refer to Drawing 2 (a)] containing line X and joint center O. The main difference of the constant velocity universal joint of this embodiment from the constant velocity universal joint of the first embodiment described above is that, in addition to the configuration adopted in the third embodiment described above, the center of the arc-shaped ball trajectory of the first track groove portion The center of curvature of the line is offset in the radial direction with respect to the joint axis NN, and the configuration of the straight ball track center line of the second track groove is adjusted accordingly. That is, the constant velocity universal joint according to this embodiment has the feature points of the constant velocity universal joints according to the second and third embodiments described above.

Specifically, the opening end A of the ball track center line Xa of the first track groove portion 7Aa of the outer joint member 2 is the same as that of the first embodiment, but the ball track center line Xa of the first track groove portion 7Aa. Is located at a point offset in the radial direction by f _{2 with} respect to the joint axis NN (there is no axial offset with respect to the joint center O). Accordingly, the linear ball track center line Xb of the second track groove portion 7Ab is adjusted to be connected as a tangent to the opening side end portion A of the ball track center line Xa of the first track groove portion 7Aa. With this configuration, the depth of the track groove on the back side of the joint can be adjusted. And although illustration is abbreviate | omitted, on the inner periphery of the outer joint member 2 shown in FIG. 20, the track groove 7 used as the pair of this outer joint member 2 on the basis of the joint center plane P in the state of an operating angle of 0 degree, An inner joint member 3 having a mirror groove 9 having a mirror image symmetry, a ball 4 and a cage 5 [see FIG. 1 and the like] are incorporated, thereby completing a fixed type constant velocity universal joint.

  FIG. 21 shows a cross-sectional view of a cage used in a fixed type constant velocity universal joint according to a fifth embodiment of the present invention. The cage 5 shown in the figure is the fixed type according to the first embodiment described above in that the centers of curvature of the spherical outer peripheral surface 12 and the spherical inner peripheral surface 13 are offset in the axial direction with respect to the joint center O. The structure is different from that of the cage 5 used in the quick universal joint.

More specifically, as shown in FIG. 21, the center of curvature Oc1 of the spherical outer peripheral surface 12 of the cage 5 is offset from the joint center O by the dimension f ₃ on the opening side, and the spherical inner peripheral surface 13 center of curvature of Oc2 is offset by a dimension f ₃ on the rear side with respect to the joint center O. With such a configuration, the thickness of the cage 5 gradually increases toward the opening side, and the strength of the cage 5 particularly at a high operating angle can be improved. As described above, in the range of the high operating angle, the balls 4 arranged in the circumferential direction are divided into the first track groove portions 7Aa, 9Aa (7Ba, 9Ba) and the second track groove portions 7Ab, 9Ab (7Bb, 9Bb). Temporarily separated. In this case, a force is applied to the opening side from the ball 4 positioned in the second track groove portions 7Ab, 9Ab (7Bb, 9Bb) to the pocket portion 5a of the cage 5, but the meat of the cage 5 moves toward the opening side. Since the thickness is gradually increased, the strength of the cage 5 can be improved. Further, the depth of the track groove 7 on the back side (the first track groove portion 7a) can be increased. The cage 5 of this embodiment can be used by being incorporated in the fixed type constant velocity universal joint of each embodiment described above.

  In the above description, the present invention is applied to a fixed type constant velocity universal joint including eight balls 4. However, the present invention is a fixed type constant velocity universal joint in which the number of balls is ten or twelve. Also preferably applied.

  In the above description, the second track groove portion having an arc-shaped or linear ball track center line is formed in the track grooves 7 and 9 of the outer joint member 2 and the inner joint member 3, but the present invention is not limited to this. . In other words, the second track groove portion is different from the first track groove portion, and can have an appropriate shape (for example, an oval shape) as long as the effective track length can be increased to increase the working angle. .

  In the above, the case where the present invention is applied to a fixed type constant velocity universal joint in which track grooves are arranged at a constant pitch in the circumferential direction has been described. In addition, the present invention can be preferably applied. Further, in the fixed type constant velocity self-joint described above, the inclination angle γ of the track groove (first track groove portion) with respect to the joint axis NN is made equal in all the track grooves, but the present invention is not limited to this. If the inclination angles γ of the track grooves (first track groove portions) of the paired outer joint member and inner joint member are equal, the inclination angles γ are different between the track grooves (first track groove portions). It doesn't matter. In short, it is only necessary to set each inclination angle so that the axial force of the ball acting on all the pocket portions 5a in the circumferential direction of the cage 5 is balanced as a whole. Further, in the above, the present invention is applied to a fixed type constant velocity universal joint configured such that the track groove and the ball 4 are in contact with each other with a contact angle (angular contact), but the present invention is not limited thereto, The present invention can also be preferably applied to a fixed type constant velocity universal joint in which the cross-sectional shape of the track groove is formed in an arc shape and the track groove and the ball are in circular contact.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. The scope of the present invention is defined by the terms of the claims, and includes the equivalent meanings recited in the claims and all modifications within the scope.

DESCRIPTION OF SYMBOLS 1 Fixed type constant velocity universal joint 2 Outer joint member 3 Inner joint member 4 Ball 5 Cage 5a Pocket part 6 Spherical inner peripheral surface 7 Track groove 7a First track groove part 7b Second track groove part 8 Spherical outer peripheral surface 9 Track groove 9a First 1 track groove portion 9b second track groove portion 12 spherical outer peripheral surface 13 spherical inner peripheral surface A end (opening side end)
B end (back end)
K perpendicular line L straight line M plane (plane including the center line of the ball trajectory)
N Joint axis O Joint center P Joint center plane (joint center plane with 0 ° operating angle)
Q plane (plane including ball trajectory centerline)
R Straight line X Ball track center line Y Ball track center line γ Inclination angle β Angle θ Operating angle

Claims (8)

A plurality of track grooves extending in the axial direction are formed on the spherical inner peripheral surface, and an outer joint member having an opening side and a back side that are separated in the axial direction, and a plurality of pairs that form pairs with the track grooves of the outer joint member on the spherical outer peripheral surface An inner joint member in which track grooves are formed, a plurality of balls that are interposed between the track grooves of the outer joint member and the track grooves of the inner joint member, and a pocket portion that holds the balls, And a fixed constant velocity universal joint comprising a spherical inner peripheral surface of the outer joint member and a cage having a spherical outer peripheral surface and a spherical inner peripheral surface that are fitted to the spherical outer peripheral surface of the inner joint member, respectively.
The track groove of the outer joint member includes a first track groove portion located on the back side and a second track groove portion located on the opening side, and the first track groove portion has no offset in the axial direction with respect to the joint center. An arc-shaped portion having a center of curvature, and inclined in the circumferential direction with respect to the axis of the joint, and the inclined directions are formed in opposite directions in the first track groove portions adjacent in the circumferential direction, The second track groove has a shape different from that of the first track groove to increase the effective track length with respect to the maximum operating angle, and is connected to the first track groove on the opening side of the joint center,
The track groove of the inner joint member is formed mirror-symmetrically with the track groove forming a pair of the outer joint member with reference to a joint center plane in a state where the operating angle is 0 °,
Track groove defining surface of the outer joint member, spherical inner peripheral surface of the outer joint member, track groove defining surface of the inner joint member, spherical outer peripheral surface of the inner joint member, outer surface of the ball, A counterpart member that relatively moves in contact with at least one surface selected from the group of the spherical outer peripheral surface of the cage, the spherical inner peripheral surface of the cage and the defining surface of the pocket portion of the cage; A fixed type constant velocity universal joint, which has been subjected to a surface treatment to reduce frictional resistance.   The angle β formed by a straight line connecting a connection point between the first track groove portion and the second track groove portion and a joint center with respect to a joint center plane in a state where the operating angle is 0 ° is set to 3 ° to 10 °. The fixed type constant velocity universal joint according to 1.   The fixed constant velocity universal joint according to claim 1 or 2, wherein a center of curvature of the arc-shaped portion of the first track groove portion is disposed on an axis of the joint.   The fixed constant velocity universal joint according to claim 1 or 2, wherein a center of curvature of the arc-shaped portion of the first track groove portion is disposed at a position offset in a radial direction from an axis of the joint.   The fixed type as described in any one of Claims 1-4 which has arrange | positioned the curvature center of the spherical outer peripheral surface of the said holder | retainer, and a spherical inner peripheral surface in the position respectively offset to the back | inner side and the opening side with respect to the joint center. Constant velocity universal joint.   6. The second track groove portion has an arc-shaped portion, and the arc-shaped portion has a center of curvature at a position radially outward from the first track groove portion and offset toward the opening side from the joint center. The fixed type constant velocity universal joint as described in any one of the above.   The fixing according to any one of claims 1 to 5, wherein the second track groove portion has a linear portion, and the linear portion is inclined so as to approach the axis of the joint toward the opening side. Type constant velocity universal joint.   The fixed type constant velocity universal joint according to claim 7, wherein the entire area of the second track groove portion is formed by a linear portion and is formed as a tangent line of the first track groove portion.

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