JP5349756B2 - Constant velocity universal joint - Google Patents

Abstract

The present invention provides a constant velocity universal joint having a recess-projection engagement configuration in which backlash at a shaft connecting region does not easily occur, and an inner joint component and a shaft can be firmly connected. In the constant velocity universal joint of the present invention, the inner joint component and the shaft 5 fitted into an axis hole 22 of the inner joint component are connected by the recess-projection engagement configuration. Engagement contacting regions 38 of projections 35 and recesses 36 corresponding thereto are in close contact over the whole region.

Description

  The present invention relates to a fixed or sliding constant velocity universal joint that is used in a power transmission system of an automobile or various industrial machines, and is incorporated in a drive shaft or a propeller shaft used in, for example, an FF vehicle, a 4WD vehicle, or an FR vehicle. In particular, the present invention relates to a constant velocity universal joint having an uneven fitting structure for connecting an inner joint member and a shaft.

  For example, a drive shaft of an automobile has a structure in which a sliding constant velocity universal joint is attached to one shaft end of the shaft and a fixed constant velocity universal joint is attached to the other shaft end.

  A tripod type constant velocity universal joint (TJ), which is one of the sliding type constant velocity universal joints used as a coupling for drive shafts, has three track grooves formed in the axial direction on the inner peripheral surface. The outer joint member (outer ring) having an axial roller guide surface on each side of each track groove, the inner joint member (tripod member) having three leg shafts projecting in the radial direction, and the inner joint member A rolling element (roller) rotatably accommodated between the leg shaft and the roller guide surface of the outer joint member is configured as a main member.

  In addition, a Barfield type constant velocity universal joint (BJ), which is one of fixed type constant velocity universal joints, is an outer joint member in which a plurality of track grooves are formed along the axial direction at equal intervals in the circumferential direction on the inner spherical surface ( An outer ring, an inner joint member (inner ring) formed on the outer spherical surface along the axial direction with a plurality of track grooves paired with the track grooves of the outer joint member, and a track groove of the outer joint member; The main members are a plurality of balls that transmit torque by being interposed between the track grooves of the inner joint member, and a cage that is interposed between the inner spherical surface of the outer joint member and the outer spherical surface of the inner joint member. Configured as

  A structure in which the shaft end of the shaft is press-fitted into the inner diameter of the shaft hole of the inner joint member is employed as a connection structure between the sliding constant velocity universal joint or the fixed constant velocity universal joint and the shaft. A female spline is formed as irregularities along the axial direction on the inner diameter of the shaft hole of the inner joint member, and a male spline is also formed on the outer diameter of the shaft end of the shaft.

  The inner hole of the inner joint member in which the female spline is formed and the outer diameter of the shaft end of the shaft in which the male spline is formed are subjected to a hardening process by, for example, induction hardening or carburizing hardening to form a hardened layer. Yes. By forming this hardened layer, the strength of the inner diameter of the shaft hole of the inner joint member and the outer diameter of the shaft end of the shaft is ensured.

  The shaft is fitted to the inner joint member by press-fitting the shaft end outer diameter of the shaft into the shaft hole inner diameter of the inner joint member and meshing the male spline and the female spline. Torque can be transmitted between the shaft and the inner joint member by spline fitting (see, for example, FIG. 2 of Patent Document 1).

Further, in such a connection structure of the inner joint member and the shaft, the retaining ring having a round cross section attached to the shaft end portion of the shaft comes into contact with a locking surface provided on the inner joint member. Some have been stopped (see, for example, Patent Document 2).
JP 2003-314580 A JP-A-8-68426

  By the way, in the fitting structure of the inner joint member of the constant velocity universal joint and the shaft, a female spline that has been hardened is formed on the inner diameter of the shaft hole of the inner joint member, and the outer end diameter of the shaft is hardened. By forming the male spline, the shaft end outer diameter of the shaft is press-fitted into the shaft hole inner diameter of the inner joint member to be fitted with the spline.

  However, since the fitting structure between the inner joint member and the shaft is a concave-convex fitting between the hardened female spline and the hardened male spline, there is a problem that rattling is likely to occur. When there is backlash, it is difficult to reliably transmit the rotational torque, and when the torque is intermittently applied, the spline tooth surfaces rub against each other, which may reduce the fatigue strength of the spline. In addition, there is a possibility that abnormal noise may occur due to the play.

  In addition, if a retaining ring is provided in the connecting structure of the inner joint member and the shaft, a groove processing for fitting the retaining ring of the shaft and a locking surface processing of the inner joint member are required, which increases the number of steps and increases the stoppage. Since a ring is necessary, the number of parts is increased, leading to an increase in product cost.

  Therefore, the present invention has been proposed in view of the above-described problems, and the object of the present invention is to provide a concave-convex fitting that makes it difficult to generate backlash at the shaft connecting portion and can firmly connect the inner joint member and the shaft. An object of the present invention is to provide a constant velocity universal joint having a structure.

The wheel bearing device of the present invention includes an outer joint member, an inner joint member inserted into the outer joint member, and a torque transmission member that transmits torque by being interposed between the outer joint member and the inner joint member. In the constant velocity universal joint, on either one of the outer diameter surface of the shaft and the inner diameter surface of the shaft hole of the inner joint member, a convex portion having an end surface on the press-fitting start end side as a surface orthogonal to the axial direction is provided. This convex part is press-fitted in the other along the axial direction, and the other part is cut by the press-fitted convex part to form a concave part in which the entire contact area with the convex part is in close contact with the convex part and the concave part. The inner joint member and the shaft that is inserted into the shaft hole of the inner joint member are connected by the concave-convex fitting structure, and the close contact of the convex portion and the concave portion in the entire fitting contact portion presses the convex portion into the other. It is characterized by having been completed.

According to the constant velocity universal joint of the present invention, since the entire fitting contact portion between the convex portion and the concave portion of the mating member fitted to the convex portion is in close contact, in this fitting structure, the radial direction and the circumference There is no gap in which play occurs in the direction. This is because when the shape of the convex portion is transferred to the concave portion forming surface on the counterpart side, the convex portion bites into the concave portion forming surface on the counterpart side, so that the shaft hole is slightly expanded in diameter. This is because the axial hole is allowed to return to its original diameter when the axial movement is allowed and the axial movement stops.

  As a constant velocity universal joint, even if a ball is used as a torque transmission member, an outer joint member formed with three track grooves having roller guide surfaces facing in the circumferential direction and a radial projection protruded. A tripod member as an inner joint member having three leg shafts, and a roller as a torque transmission member rotatably fitted on the leg shaft and inserted into the track groove, the roller being the roller It may be one that can move in the axial direction of the outer joint member along the guide surface (tripod type constant velocity universal joint). Also, a ball that uses a torque transmission member may be a fixed type such as a Barfield type constant velocity universal joint (BJ) or an undercut free type constant velocity universal joint (UJ), or a cross groove type, etc. A sliding type such as a quick universal joint (LJ) or a double offset type constant velocity universal joint (DOJ) may be used. That is, the Barfield type constant velocity universal joint (BJ), the undercut free type constant velocity universal joint (UJ), and the double offset type constant velocity universal joint (DOJ) have a plurality of guide grooves extending in the axial direction on the inner diameter surface. The outer ring as the outer joint member formed, the inner ring as the inner member formed with a plurality of axially extending guide grooves on the outer diameter surface, the guide groove of the outer ring and the guide groove of the inner ring are formed in cooperation. And a cage having a pocket for holding the torque transmission ball. The cross groove type constant velocity universal joint (LJ) has a circumferential axis with respect to the axis. An outer ring as an outer joint member in which guide grooves twisted in one of the directions and guide grooves twisted in the other in the circumferential direction are alternately provided on the inner peripheral surface, and each guide groove of the outer ring is paired to form a ball track And An inner ring of the inner member provided alternately on the outer peripheral surface of the guide groove of the outer ring forming a, in which a cage for holding the torque transmitting balls.

  The shaft is provided with a convex portion, and at least the hardness of the axial end portion of the convex portion is made higher than the inner diameter portion of the inner joint member so that the shaft extends into the axial hole of the inner joint member. By press-fitting from the part side, a concave part that closely fits to the convex part may be formed on the inner surface of the shaft hole of the inner joint member. Further, a convex portion is provided on the inner diameter surface of the shaft hole of the inner joint member, and at least the hardness of the end portion in the axial direction of the convex portion is made higher than the outer diameter portion of the shaft so that the convex portion on the inner joint member side is By press-fitting into the shaft from the axial end portion side, a concave portion that closely fits to the convex portion may be formed on the outer diameter surface of the shaft at the convex portion.

  It is preferable that the shaft is provided with a pocket portion that accommodates the protruding portion generated by forming the concave portion by the press-fitting. At this time, it is possible to provide the shaft with a pocket portion that accommodates the protruding portion that is generated by forming the concave portion by press fitting, or to provide the pocket portion on the inner diameter surface of the shaft hole of the inner joint member. Here, the protruding portion is the material of the capacity of the concave portion into which the concave portion fitting portion of the convex portion is fitted (fitted), and is extruded from the formed concave portion, or cut to form the concave portion. It is comprised from what was extruded, what was extruded, and what was cut.

  Further, a pocket portion for accommodating the protruding portion is provided on the press-fitting start end side of the convex portion of the shaft, and a collar portion for alignment with the shaft hole of the inner joint member is provided on the non-convex portion side of the pocket portion. Is preferred.

  Further, any portion in the protruding direction of the convex portion corresponds to the position of the concave portion forming surface before the concave portion is formed. At this time, the maximum diameter dimension of the arc connecting the vertices of the plurality of protrusions is made larger than the inner diameter dimension of the shaft hole of the inner joint member, and the maximum outer diameter dimension of the shaft outer diameter surface between the protrusions is set on the inner joint member. The inner diameter dimension of the shaft hole is made smaller, or the minimum diameter dimension of the arc connecting the apexes of the projections of the shaft hole is made smaller than the outer diameter dimension of the inner joint member fitting insertion portion of the shaft. In some cases, the minimum inner diameter dimension of the inner diameter surface is made larger than the outer diameter dimension of the inner joint member fitting insertion portion of the shaft.

  It is preferable that the circumferential thickness of the protruding portion intermediate portion of the convex portion is smaller than the circumferential dimension at a position corresponding to the intermediate portion between the convex portions adjacent in the circumferential direction. By setting in this way, the sum of the circumferential thicknesses of the projecting direction intermediate portions of the convex portions is the position corresponding to the intermediate portion in the mating convex portion that fits between the convex portions adjacent in the circumferential direction. Smaller than the sum of the circumferential thicknesses.

  It is also preferable to provide a concavo-convex portion along the axial direction in at least a part of the convex portion in the axial direction. Moreover, the uneven | corrugated | grooved part along the axial direction by the side of the said convex part may be formed in a sawtooth shape.

  In the concave / convex fitting structure of the present invention, no gap is formed in which the play occurs in the radial direction and the circumferential direction. Therefore, all of the fitting parts contribute to rotational torque transmission, and stable rotational torque transmission is possible. It is possible to avoid a decrease in fatigue strength of the spline due to the friction of the tooth surfaces, and it is excellent in durability. Moreover, no abnormal noise is generated. Furthermore, since it is in close contact with each other in the radial direction and the circumferential direction, the strength of the torque transmitting portion is improved, and the constant velocity universal joint can be made lightweight and compact.

  A convex portion provided on either the outer diameter surface of the shaft or the inner diameter surface of the shaft hole of the inner joint member is press-fitted into the other along the axial direction, and the convex portion is closely fitted to the convex portion on the other side. A concave portion to be formed can be formed. For this reason, an uneven | corrugated fitting structure can be formed reliably. Moreover, it is not necessary to form a spline portion or the like on the member where the recess is formed, and it is excellent in productivity and does not require the phase alignment between the splines. Damage to the tooth surface can be avoided and a stable fitting state can be maintained.

  In addition, when the convex portion is provided on the shaft and the hardness on the convex portion side is made higher than the inner diameter portion of the shaft hole of the inner joint member, the concave portion is formed on the inner diameter surface of the inner joint member at the time of press-fitting. It becomes easy. Further, the shaft side hardness can be increased, and the torsional strength of the shaft can be improved. In addition, if a convex portion is provided on the inner diameter surface of the shaft hole of the inner joint member and the hardness of the axial end portion on the convex portion side is higher than the outer diameter portion of the shaft, It becomes easy to form a recess on the outer diameter surface. Since it is not necessary to perform hardness treatment (heat treatment) on the shaft side, the shaft productivity is excellent.

  By providing a pocket portion that accommodates the protruding portion generated by the depression formation by press-fitting, the protruding portion can be held (maintained) in this pocket, and the protruding portion is not mixed into the constant velocity universal joint. In other words, the protruding portion can be kept stored in the pocket portion, and it is not necessary to perform the removal processing of the protruding portion, the number of assembling work can be reduced, and the assembling workability can be improved and the cost can be reduced. Can be planned.

  In addition, by providing a collar for alignment on the axially anti-convex part side of the pocket part, the protruding part in the pocket part does not protrude to the collar part side, and the storage of the protruding part becomes more stable. . Moreover, since the collar portion is used for alignment, the shaft can be press-fitted into the inner joint member while preventing misalignment. For this reason, the inner joint member and the shaft can be connected with high accuracy, and stable torque transmission is possible.

  In addition, by arranging any part in the protruding direction of the convex part on the concave surface where the concave part is formed, the convex part bites into the concave part forming surface during press-fitting, and the concave part is reliably formed. can do.

  The convex part on the side where the concave part is formed by making the circumferential thickness of the intermediate part in the protruding direction of the convex part smaller than the dimension at the position corresponding to the intermediate part between the convex parts adjacent in the circumferential direction ( The thickness in the circumferential direction of the projecting intermediate portion of the convex portion between the concave portions formed can be increased. For this reason, the shear area of the convex part of the other party (the convex part having low hardness between the concave parts due to the formation of the concave parts) can be increased, and the torsional strength can be ensured. Moreover, since the tooth thickness of the convex portion on the higher hardness side is small, the press-fitting load can be reduced and the press-fitting property can be improved.

  By providing a concavo-convex portion along the axial direction in at least a part of the axial direction on the convex side, the axial direction on the side having a small hardness (the side on which the concave portion to which the convex is fitted) is formed when press-fitted. The concavo-convex part along the line bites in along the axial direction. By this bite-in, it is possible to configure the shaft in the axial direction to prevent the inner joint member from coming off. Moreover, since the sawtooth bites into the side having a small hardness by making the uneven portion serrated, a stronger retaining mechanism is obtained. For this reason, the stable connection state can be maintained and the quality improvement of the constant velocity universal joint can be achieved. In addition, since the concave and convex portions along the axial direction can be configured to prevent slipping, there is no need to provide a retaining ring fitting groove and inner joint member on the shaft, reducing the number of processing steps and the number of parts. Thus, the production cost can be reduced and the assembly workability can be improved.

  Embodiments of the present invention are described in detail below. In addition, although the following embodiment illustrates the case where it applies to a fixed type (Burfield type) constant velocity universal joint (BJ), other fixed type constant velocity universal joints, for example, an undercut free type constant velocity universal joint ( UJ) and sliding type constant velocity universal joints such as cross groove type constant velocity universal joints (LJ), double offset type constant velocity universal joints (DOJ), tripod type constant velocity universal joints (TJ) ) Is also applicable.

  FIG. 1 illustrates the overall configuration of a Barfield type constant velocity universal joint using the concave-convex fitting structure of the first embodiment. The constant velocity universal joint includes an outer ring 1 as an outer joint member, an inner ring 2 as an inner joint member into which the outer ring 1 is inserted, and a torque transmission member that is interposed between the outer ring 1 and the inner ring 2 to transmit torque. And a cage 4 that is interposed between the outer ring 1 and the inner ring 2 and holds the ball 3 as main members. When this fixed type constant velocity universal joint is applied to a drive shaft, the outer ring 1 is coupled to a wheel bearing device (not shown), and the shaft 5 is coupled to the inner ring 2 by the concave-convex fitting structure M according to the present invention. Thus, torque is transmitted at a constant speed even when the rotation axes of the outer ring 1 and the inner ring 2 are angled.

  The outer ring 1 includes a mouse portion 6 and a stem portion 7. The stem portion 7 is coupled to the wheel bearing device so as to be able to transmit torque. The mouse portion 6 has a bowl shape opened at one end, and a plurality of track grooves 9 extending in the axial direction are formed on the inner spherical surface 8 at equal intervals in the circumferential direction. The track groove 9 extends to the open end of the mouse portion 6. In the inner ring 2, a plurality of track grooves 11 extending in the axial direction are formed on the outer spherical surface 10 at equal intervals in the circumferential direction. The track groove 11 is cut in the axial direction of the inner ring 2.

  The track groove 9 of the outer ring 1 and the track groove 11 of the inner ring 2 form a pair so that the ball 3 as a torque transmitting element can roll on the ball track constituted by each pair of track grooves 9 and 11. It is incorporated. The ball 3 is interposed between the track groove 9 of the outer ring 1 and the track groove 11 of the inner ring 2 and transmits torque. The cage 4 is slidably interposed between the outer ring 1 and the inner ring 2, is in contact with the inner spherical surface 8 of the outer ring 1 at the outer spherical surface 4a, and is in contact with the outer spherical surface 10 of the inner ring 2 at the inner spherical surface 4b.

  As described above, the inner ring 2 is coupled to the shaft 5 so that torque can be transmitted by press-fitting the end portion 5a of the shaft 5 into the shaft hole 22 thereof. That is, the shaft 5 and the inner ring 2 are connected via the concave-convex fitting structure M according to the first embodiment of the present invention. The inner diameter surface 37 (see FIG. 2) of the shaft hole 22 of the inner ring 2 is formed by cold forging finishing, but may be formed by turning or polishing finishing.

  As shown in FIG. 3, the concave-convex fitting structure M includes, for example, a convex portion 35 provided on the shaft 5 side and extending in the axial direction, and a concave portion 36 formed in the inner diameter surface 37 of the shaft hole 22 of the inner ring 2. Thus, the entire fitting contact portion 38 between the convex portion 35 and the concave portion 36 of the inner ring 2 fitted to the convex portion 35 is in close contact. A plurality of convex portions 35 are arranged at a predetermined pitch along the circumferential direction, and a plurality of concave portions 36 into which the convex portions 35 are fitted to the inner diameter surface 37 of the inner ring 2 are formed along the circumferential direction. That is, the convex part 35 and the concave part 36 fitted to this are tight-fitted over the entire circumference in the circumferential direction.

  In this case, any part in the protruding direction of the convex portion (in the drawing, the intermediate portion in the protruding direction) corresponds to the position of the concave portion forming surface before the concave portion is formed. That is, each convex portion 35 has a triangular shape (mountain shape) having a convex round-shaped cross section, and the fitting contact portion 38 between each convex portion 35 and the concave portion 36 of the inner ring 2 is shown in FIG. It is the range A shown in b), which is the range from the mid-section of the mountain in the cross section to the summit. A gap 40 is formed on the inner diameter side of the inner ring surface 37 of the inner ring 2 between the adjacent convex portions 35 in the circumferential direction. Note that, as shown in the figure, the intermediate portion in the protruding direction of the convex portion 35 may not correspond to the position of the concave portion forming surface before forming the concave portion, but may correspond to a part (for example, the tip portion).

  In the present invention, the concave / convex fitting structure M is in close contact with the entire fitting contact portion 38 between the convex portion 35 and the concave portion 36 of the inner ring 2, so in the concave / convex fitting structure M, in the radial direction and the circumferential direction. There is no gap in which play occurs. For this reason, all of the fitting parts contribute to rotational torque transmission, and stable rotational torque transmission is possible. A decrease in the fatigue strength of the spline due to friction of the tooth surfaces of the spline can be avoided, and the durability is excellent. Moreover, no abnormal noise is generated. Furthermore, since it is in close contact with each other in the radial direction and the circumferential direction, the strength of the torque transmitting portion is improved, and the constant velocity universal joint can be made lightweight and compact.

  Next, the fitting method of the uneven fitting structure M will be described. In this case, as shown in FIGS. 4 and 5, the outer diameter portion of the end portion 5a of the shaft 5 is subjected to a thermosetting process, and the cured layer S is composed of a convex portion 41a and a concave portion 41b along the axial direction. A spline 41 is formed. For this reason, the convex part 41a of the spline 41 is cured, and the convex part 41a becomes the convex part 35 of the concave-convex fitting structure M. At this time, the inner surface 37 of the shaft hole 22 of the inner ring 2 is an uncured portion that is not subjected to heat curing. In FIGS. 4 and 5, the hatched portion indicated by a broken line indicates the hardened layer S. The hardness difference between the hardened layer S and the uncured portion of the inner diameter surface 37 of the shaft hole 22 of the inner ring 2 is 30 points or more in HRC. The module of the spline 41 of the shaft 5 is a small tooth of 0.5 or less. Here, the module is a pitch circle diameter divided by the number of teeth. As shown in FIGS. 2 and 3, the inner ring 2 has a hardened layer S1 (cross-hatched portion) formed by induction hardening on the outer spherical surface between the track grooves and the track grooves. Uncured.

  At this time, any portion in the protruding direction of the convex portion 35 corresponds to the position of the concave portion forming surface (in this case, the inner diameter surface 37 of the shaft hole 22 of the inner ring 2) before the concave portion is formed. That is, as shown in FIG. 2, the inner diameter dimension D of the inner diameter surface 37 of the shaft hole 22 is the maximum outer diameter dimension of the convex section 55, that is, the circle connecting the vertices of the convex section 35 that is the convex section 41 a of the spline 41. It is smaller than the maximum diameter dimension (circumscribed circle diameter) D1, and is set larger than the maximum outer diameter dimension of the shaft outer diameter surface between adjacent convex portions, that is, the maximum diameter dimension D2 of the circle connecting the bottoms of the concave portions 41b of the spline 41. The That is, D2 <D <D1.

  The spline 41 can be formed by various processing methods such as rolling processing, cutting processing, press processing, and drawing processing, which are known publicly known means. Moreover, various heat processing, such as induction hardening and carburizing hardening, can be employ | adopted as a thermosetting process.

  Then, as shown in FIG. 2, the shaft 5 is inserted (press-fitted) into the inner ring 2 in a state where the axis of the inner ring 2 and the axis of the shaft 5 are aligned. At this time, the diameter D of the inner diameter surface 37 of the shaft hole 22, the maximum outer diameter D1 of the convex portion 35, and the maximum outer diameter D2 of the concave portion of the spline 41 are as described above. Since the hardness of the portion 35 is 30 points or more larger than the hardness of the inner diameter surface 37 of the shaft hole 22, if the shaft 5 is press-fitted into the shaft hole 22 of the inner ring 2, the convex portion 35 will bite into the inner diameter surface 37. The convex portion 35 forms the concave portion 36 into which the convex portion 35 is fitted along the axial direction.

  As a result, as shown in FIGS. 3A and 3B, a fitting state in which the entire fitting contact portion 38 between the convex portion 35 of the end portion 5a of the shaft 5 and the concave portion 36 of the inner ring 2 is in close contact is configured. can do. In other words, the shape of the convex portion 35 is transferred to the concave portion forming surface (in this case, the inner diameter surface 37 of the shaft hole 22). At this time, the convex portion 35 bites into the inner diameter surface 37 of the shaft hole 22, so that the shaft hole 22 is slightly expanded in diameter, allowing the convex portion 35 to move in the axial direction, and the axial direction. If the movement stops, the diameter of the shaft hole 22 is reduced to return to the original diameter. In other words, when the convex portion 35 is press-fitted, the inner ring 2 is elastically deformed in the radial direction, and a preload corresponding to this elastic deformation is applied to the tooth surface of the convex portion 35 (the surface of the fitting contact portion 38). For this reason, the uneven | corrugated fitting structure M which the fitting contact part 38 whole region of the convex part 35 and the recessed part 36 of the inner ring | wheel 2 closely_contact | adheres can be formed reliably. Moreover, it is not necessary to form a spline portion or the like on the member in which the concave portion 36 is formed, which is excellent in productivity, and does not require the phase alignment between the splines. The tooth surface can be prevented from being damaged, and a stable fitting state can be maintained. The hardness on the shaft 5 side can be increased and the torsional strength of the shaft 5 can be improved.

  As in the above-described embodiment, the spline 41 formed on the shaft 5 uses small teeth with a module of 0.5 or less, so that the moldability of the spline 41 can be improved and the press-fit load can be reduced. Can be planned. In addition, since the convex part 35 can be comprised with the spline normally formed in this kind of shaft, this convex part 35 can be easily formed at low cost.

  Further, when the concave portion 36 is formed by press-fitting the shaft 5 into the inner ring 2, work hardening occurs on the concave portion 36 side. Here, work hardening means that when plastic deformation (plastic processing) is applied to an object, the resistance to deformation increases as the degree of deformation increases, and it becomes harder than a material that has not undergone deformation. For this reason, the inner diameter surface 37 of the inner ring 2 on the concave portion 36 side is hardened by the plastic deformation that occurs during the press-fitting, and the rotational torque transmission performance can be improved.

  By the way, in the spline 41 shown in FIG. 3, the pitch of the convex portions 41a and the pitch of the concave portions 41b are set to be the same. For this reason, in the said embodiment, as shown in FIG.3 (b), it corresponds to the circumferential direction thickness L of the protrusion direction intermediate part of the convex part 35, and the said intermediate part between the convex parts 35 adjacent to the circumferential direction. The circumferential dimension L0 at the position is substantially the same.

  On the other hand, as shown in FIG. 6, the circumferential thickness L2 of the projecting direction intermediate portion of the convex portion 35 is set to a circumferential dimension at a position corresponding to the intermediate portion between the convex portions 35 adjacent in the circumferential direction. It may be smaller than L1. That is, in the spline 41 formed on the shaft 5, the circumferential thickness (tooth thickness) L <b> 2 of the intermediate portion in the protruding direction of the convex portion 35 is set to the convex portion 43 on the opposite side, that is, the inner ring 2 side. This is smaller than the circumferential thickness (tooth thickness) L1 of the intermediate portion in the protruding direction.

  Therefore, the total tooth thickness (ΣB1 + B2 + B3 +...) Of the convex portions (convex teeth) 35 on the shaft 5 side is smaller than the total tooth thickness (ΣA1 + A2 + A3 +...) Of the convex portions 43 on the entire circumference on the inner ring 2 side. It is set. As a result, the shear area of the convex portion 43 on the inner ring 2 side can be increased, and the torsional strength can be ensured. And since the tooth thickness of the convex part 35 is small, a press-fit load can be made small and a press-fit property can be aimed at. When making the sum total of the circumferential thickness of the convex part 35 smaller than the sum total of the circumferential direction thickness in the other convex part 43, the circumferential direction thickness L2 of all the convex parts 35 is the convex part adjacent to the circumferential direction. It is not necessary to make it smaller than the circumferential dimension L1 between 35. That is, among the plurality of convex portions 35, even if the circumferential thickness of the arbitrary convex portion 35 is the same as the circumferential dimension between the convex portions adjacent in the circumferential direction, it is larger than the circumferential dimension. However, it is sufficient if the sum is small. In addition, the convex part 35 in FIG. 6 is made into the cross-sectional trapezoid (Mt. Fuji shape).

  Next, FIG. 7 shows a second embodiment, and this concave / convex fitting structure M has a convex portion 35 of the shaft 5, that is, a convex portion 41 a of the spline 41, and a concave / convex portion 55 extending in the axial direction partially in the axial direction. Is formed. In this case, the uneven portion 55 is formed in a sawtooth shape along the axial direction. In this case, the convex portion (convex tooth) 55a has a cross-sectional shape of a right triangle having the pocket side as an inclined surface.

  As shown in FIG. 9, if the shaft 5 provided with the concavo-convex portion 55 is press-fitted into the shaft hole 22 of the inner ring 2 by aligning the axial center of the inner ring 2 and the shaft 5, a convex portion on the shaft 5 side. In this case, the concave / convex portion 55 bites into the bottom of the concave portion 36 formed on the inner ring 2 side. That is, the diameter of the shaft hole 22 of the inner ring 2 that has been expanded at the time of press-fitting is increased, but when the press-fitting is completed, the diameter is reduced to return to the original state. For this reason, a pressing force (diameter reducing force) acts on the concave and convex portion 55 from the inner diameter side of the shaft hole 22 of the inner ring 2 as shown by the arrow in FIG. The convex part 55a of the part 55 bites in.

  By providing the projections and depressions 55 along the axial direction in at least a part of the projections 35 in the axial direction, the side having a small hardness when pressed-in (the depressions 36 into which the projections 35 are fitted is formed. The concavo-convex portion 55 along the axial direction bites in the axial direction. By this bite-in, it is possible to constitute an axial stopper of the shaft 5 with respect to the inner joint member. Further, by making the concave and convex portion 55 serrated, the sawtooth bites more into the side having a low hardness, so that a stronger retaining mechanism is obtained. For this reason, the stable connection state can be maintained and the quality improvement of the constant velocity universal joint can be achieved. Moreover, since the concave and convex portions 55 along the axial direction can be configured to prevent slipping, it is not necessary to provide a retaining surface for the retaining ring fitting groove and the inner joint member on the shaft 5, and the number of processing steps and the number of parts can be reduced. Can be reduced, and production costs can be reduced and assembly workability can be improved.

  By the way, if the shaft 5 is press-fitted into the inner ring 2, the material protrudes from the concave portion 36 formed by the convex portion 35, and the protruding portion 45 as shown in FIG. 10 of the third embodiment is formed. . The protruding portion 45 is the material of the capacity of the concave portion 36 into which the concave portion fitting portion 38 of the convex portion 35 is fitted (fitted), and is pushed out from the formed concave portion 36 to form the concave portion 36. It is composed of what has been cut or both extruded and cut.

  For this reason, in the constant velocity universal joint shown in FIG. 1, after the shaft 5 is assembled to the inner ring 2, it is necessary to remove the protruding portion 45. Therefore, in another embodiment shown in FIG. 10, a pocket portion 50 that accommodates the protruding portion 45 is provided in the shaft 5.

  That is, the pocket portion 50 is formed by providing the circumferential groove 51 at the axial end edge of the spline 41 of the shaft 5. As shown in FIG. 11, in the circumferential groove 51, the side wall 51a on the spline 41 side is a plane orthogonal to the axial direction, and the side surface 51b on the anti-spline side faces from the groove bottom 51c to the anti-spline side. This is a tapered surface that expands in diameter.

  Further, a disc-shaped flange 52 for alignment is provided on the side opposite to the spline from the side surface 51b. The outer diameter of the flange 52 is set to be the same as the hole diameter of the shaft hole 22 or slightly smaller than the hole diameter D of the shaft hole 22. In this case, a minute gap t is provided between the outer diameter surface 52 a of the flange 52 and the inner diameter surface 37 of the shaft hole 22.

  Even in the case of the inner ring 2 shown in FIG. 10, as shown in FIG. 12, if the shaft center of the inner ring 2 and the shaft center of the shaft 5 are aligned and the shaft 5 is press-fitted into the shaft hole 22 of the inner ring 2. The concave portion 36 is formed on the inner ring 2 side by the convex portion 35 on the shaft 5 side. At this time, the protruding portion 45 generated is housed in the pocket portion 50 while curling as shown in FIG.

  In this way, by providing the pocket portion 50 for storing the protruding portion 45 generated by forming the concave portion by the press-fitting, the protruding portion 45 can be held (maintained) in the pocket portion 50, and the constant velocity universal joint is provided. There is no misunderstanding. That is, the protruding portion 45 can be kept stored in the pocket portion 50, and it is not necessary to perform the removal process of the protruding portion 45, the number of assembling work can be reduced, and the assembling workability can be improved. Cost reduction can be achieved.

  Further, by providing a collar portion 52 for alignment with the shaft hole 22 of the inner ring 2 on the side opposite to the convex portion of the pocket portion 50, the protruding portion 45 in the pocket portion 50 does not protrude to the collar portion 52 side. , The storage of the protruding portion 45 becomes more stable. Moreover, since the flange portion 52 is used for alignment, the shaft portion can be press-fitted into the shaft hole 22 of the inner ring 2 while preventing misalignment. For this reason, the inner ring 2 and the shaft 5 can be connected with high accuracy, and stable torque transmission is possible.

  Since the flange 52 is used for aligning during press-fitting, the outer diameter is preferably set to be slightly smaller than the hole diameter of the inner ring 2. That is, if the outer diameter dimension of the flange 52 is the same as the hole diameter of the inner ring 2 or larger than the hole diameter of the inner ring 2, the flange 52 itself is press-fitted into the shaft hole of the inner ring 2. At this time, if the center is misaligned, the convex portion 35 of the concave-convex fitting structure M is press-fit as it is, and the shaft 5 and the inner ring 2 are connected in a state where the axis of the shaft 5 and the axis of the inner ring 2 do not match. Will be. Moreover, if the outer diameter dimension of the collar part 52 is too smaller than the hole diameter of a shaft hole, it will not function for centering. For this reason, it is preferable that the minute gap t between the outer diameter surface 52a of the flange portion 52 and the inner diameter surface of the shaft hole is set to about 0.01 mm to 0.2 mm.

Since the other structure of the constant velocity universal joint shown in FIG. 10 is the same as that of the constant velocity universal joint shown in FIG. 1, the same members as those in FIG. For this reason, the constant velocity universal joint shown in FIG. 10 has the same effect as the constant velocity universal joint shown in FIG.

  Incidentally, as shown in FIGS. 13 and 14, small concave portions 60 disposed at a predetermined pitch along the circumferential direction may be provided on the inner diameter surface of the shaft hole 22 of the inner ring 2. The small recess 60 needs to be smaller than the volume of the recess 36. Thus, by providing the small recessed part 60, the press fit property of the convex part 35 can be improved. That is, by providing the small concave portion 60, the capacity of the protruding portion 45 formed when the convex portion 35 is press-fitted can be reduced, and the press-fit resistance can be reduced. Moreover, since the protrusion part 45 can be decreased, the volume of the pocket part 50 can be made small and the workability of the pocket part 50 and the improvement of the intensity | strength of the shaft 5 can be aimed at. In addition, although the shape of the small recessed part 60 is a semi-elliptical shape in the example of a figure, other various things, such as a rectangle, can be employ | adopted and a number can also be set arbitrarily.

  The constant velocity universal joint may be a sliding type constant velocity universal joint using a tripod trunnion as shown in FIGS. 15 (a), 15 (b) and 15 (c). The inner joint member includes a boss portion 65 and a shaft portion 62 projecting from the boss portion 65 in the outer diameter direction at a pitch of 120 degrees along the circumferential direction. The shaft 5 is inserted into the shaft hole 63 of the boss portion 65. Inserted. Further, a roller (not shown) as a torque transmission member is attached to the shaft portion 62.

  Therefore, the inner diameter surface of the shaft hole 63 of the boss portion 65 is an uncured portion, and as shown in FIG. 4, the outer diameter surface is subjected to a curing process and a spline 41 is formed at the shaft end portion. The formed shaft 5 is press-fitted into the shaft hole 63 of the boss portion 65. In addition, it is preferable to provide the hardened layer S2 on the outer surface of the inner joint member of the tripod type constant velocity universal joint as shown in FIGS.

  By this press-fitting, the concave portion 36 fitted to the convex portion 35 can be formed on the inner diameter surface of the shaft hole 63 of the boss portion 65 at the convex portion 35 constituted by the convex teeth 41 a of the spline 41. Even in this case, the entire fitting contact portion 38 between the convex portion 35 and the concave portion 36 of the shaft 5 is in close contact. For this reason, the inner ring 2 and the shaft 5 can be connected with high accuracy, and stable torque transmission is possible.

  By the way, in each said embodiment, while forming the spline 41 which comprises the convex part 35 in the shaft 5 side, it hardens | cures with respect to the spline 41 of this shaft 5, and the internal diameter surface of the inner ring | wheel 2 is unhardened (raw material) ). On the other hand, as shown in FIG. 16 and FIG. 17 of the fourth embodiment, the spline 61 (consisting of ridges 61 a and ridges 61 b) in which the inner diameter surface of the shaft hole 22 of the inner ring 2 is cured. And the shaft 5 may not be subjected to a curing process. The spline 61 can also be formed by various processing methods such as broaching, cutting, pressing, and drawing, which are publicly known means. Further, various heat treatments such as induction hardening and carburizing and quenching can be employed as the thermosetting treatment.

  In this case, the intermediate portion in the protruding direction of the convex portion 35 corresponds to the position of the concave portion forming surface (the outer diameter surface of the shaft 5) before the concave portion is formed. That is, the minimum diameter (minimum inner diameter dimension of the convex portion 35) D4 connecting the vertices of the convex portions 35 that are the convex portions 61a of the spline 61 is smaller than the outer diameter D3 of the shaft 5, and the bottom of the concave portion 61b of the spline 61 The minimum outer diameter dimension (inner diameter dimension of the inner diameter surface of the shaft hole between the convex portions) D5 is set larger than the outer diameter dimension D3 of the shaft 5. That is, D4 <D3 <D5.

  In this case, if the shaft 5 is press-fitted into the shaft hole 22 of the inner ring 2, the concave portion 36 in which the convex portion 35 is fitted to the outer diameter surface 66 of the shaft 5 can be formed by the convex portion 35 on the inner ring 2 side. Accordingly, it is possible to configure a fitting state in which the entire fitting contact portion 38 between the convex portion 35 on the inner ring 2 side and the concave portion 36 of the shaft 5 is in close contact.

  Here, the fitting contact portion 38 between the convex portion 35 and the concave portion 36 of the shaft 5 is a range B shown in FIG. 17B, and is a range from the middle of the mountain shape to the top of the mountain in the cross section. Further, a gap 62 is formed on the outer diameter side of the outer peripheral surface of the shaft 5 between the adjacent convex portions 35 in the circumferential direction.

  Even in this case, since the protruding portion is formed by press-fitting, it is preferable to provide a pocket portion for storing the protruding portion. Unlike the one shown in FIG. 10, the protruding portion is formed on the shaft side, so the pocket portion is provided on the inner ring 2 side.

  Even if the convex portion 35 of the concave-convex fitting structure M is formed on the inner ring 2 side in this way, the outer diameter of the shaft 5 is aligned when the inner ring 2 is press-fitted into the end portion of the shaft 5. A buttocks may be provided. Thereby, press-fitting with high accuracy becomes possible. Moreover, you may provide uneven | corrugated | grooved parts, such as a sawtooth shape which exhibits a retaining function in the inner ring | wheel 2 side. By the way, in the inner rings of other embodiments (other than the tripod type constant velocity universal joint) other than the first embodiment, the hardened layer S1 is not shown, but the hardened layer S1 is provided as shown in FIGS. It is preferable to do so.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the embodiment, and various modifications are possible. For example, as the shape of the convex portion 35 of the concave-convex fitting structure, FIG. In the embodiment shown in FIG. 6, the cross section is triangular, and in the embodiment shown in FIG. 6, the cross section is trapezoidal (Mt. Fuji), but other shapes such as a semicircular shape, a semielliptical shape, and a rectangular shape are adopted. Further, the area and number of the convex portions 35, the circumferential arrangement pitch, and the like can be arbitrarily changed. That is, the splines 41 and 61 are formed, and the convex portions (convex teeth) 41a and 61a of the splines 41 and 61 do not need to be the convex portions 35 of the concave-convex fitting structure M. Alternatively, a curved corrugated mating surface may be formed. In short, the convex portion 35 disposed along the axial direction can be press-fitted into the mating side, and the concave portion 36 can be formed on the mating side with the convex portion 35 so as to closely fit the convex portion 35. It is only necessary that the entire fitting contact portion 38 between the portion 35 and the corresponding recess 36 is in close contact, and that rotational torque can be transmitted between the inner ring 2 and the shaft 5.

  Further, the shaft hole 22 of the inner ring 2 may be a deformed hole such as a polygonal hole other than a circular hole, and the cross-sectional shape of the end portion 5a of the shaft 5 fitted into the shaft hole 22 is also a polygon other than a circular cross section. An irregular cross section such as For this reason, for example, the shaft hole 22 of the inner ring 2 can be a circular hole, the cross-sectional shape of the end 5a of the shaft 5 can be a polygon other than a circle, and the edge can be the convex portion 35.

  As the shape of the pocket portion 50, in the above-described embodiment, the circumferential groove 51 has a side surface 51b on the side opposite to the spline that is a tapered surface that expands from the groove bottom 51c toward the side opposite to the spline. It is sufficient that the protruding portion 45 to be generated can be accommodated (accommodated), and as long as the capacity of the pocket portion 50 can be accommodated to the protruding portion 45 that is generated. .

  In the case where the uneven portion 55 is provided, in FIG. 7, it is provided in the intermediate portion in the axial direction of the spline 41, but it may be provided on the shaft end surface side of the spline 41, conversely, on the opposite shaft end surface side, The spline 41 may be provided along the entire length in the axial direction. Moreover, the number and shape of the convex part (convex tooth) 55a of each uneven | corrugated | grooved part 55 are also arbitrary. That is, as the concavo-convex portion 55, the concavo-convex portion 55 may be provided on the entire convex portion 35, or may be provided on an arbitrary convex portion 35 among the total convex portions 35. As shown in FIG. 10 and the like, an uneven portion 55 may be provided on the shaft 5 having the pocket portion 50. In the embodiment, the concave and convex portion 55 is provided in the convex portion 41 a of the spline 41 constituting the convex portion 35, but the concave and convex portion 55 may be provided in the concave portion 41 b of the spline 41.

  Moreover, in the said embodiment, although the thermosetting process was performed with respect to the convex part 35 and the convex corresponding | compatible part side was made into the non-hardened part, the hardness of the convex part 35 was made higher than the site | part in which a recessed part is formed, hardness difference is made. If it can be applied, both of them may be heat treated or both may not be heat treated. Furthermore, since only the press-fitting start end portion of the convex portion 35 needs to be harder than the portion where the concave portion 36 is formed during press-fitting, it is not necessary to increase the overall hardness of the convex portion 35. Furthermore, although the gap 40 is formed in FIG. 2 and the like, the gap between the convex portions 35 may bite into the inner diameter surface 37 of the inner ring 2. As described above, the hardness difference between the convex portion 35 side and the concave portion forming surface formed by the convex portion 35 is preferably 30 points or more by HRC, but the convex portion 35 can be press-fitted. If there is, it may be less than 30 points. Examples of the heat treatment method include induction hardening, carburizing and quenching, tempering, and normalizing. In the case where the concave portion 36 is formed on the inner diameter surface of the inner ring 2 by the convex portion 35 of the shaft 5 at the time of press-fitting, when the inner ring 2 is carburized and quenched, the inner surface is subjected to a carbon-proof treatment so that the hardness is higher than the convex portion 35 of the shaft 5. It becomes easy to form a low layer on the inner diameter surface of the inner ring 2. Further, when the concave portion 36 is formed on the shaft 5 by the convex portion 35 of the inner diameter of the inner ring 2 at the time of press-fitting, the shaft 5 is subjected to normalization treatment or tempering treatment, thereby ensuring the torsional strength of the shaft 5. The hardness of the outer diameter surface can be made lower than the convex portion 35 of the inner diameter of the inner ring 2.

  Although the end surface (press-fit start end) of the convex portion 35 is a surface orthogonal to the axial direction in the embodiment, it may be inclined at a predetermined angle with respect to the axial direction. In this case, it may be inclined from the inner diameter side toward the outer diameter side toward the anti-convex portion side or inclined toward the convex portion side. In addition, when press-fitting the convex portion 35, even if the side where the concave portion 36 is formed is fixed and the side where the convex portion 35 is formed is moved, the side where the convex portion 35 is formed is reversed. It may be fixed and the side where the recess 36 is formed may be moved or both may be moved.

It is sectional drawing of the constant velocity universal joint using the uneven | corrugated fitting structure which shows 1st Embodiment of this invention. It is sectional drawing of the decomposition | disassembly state of the said uneven | corrugated fitting structure. The uneven | corrugated fitting structure of the said constant velocity universal joint is shown, (a) is an expanded sectional view, (b) It is the X section enlarged view of (a). It is a principal part side view of the shaft connected with the said constant velocity universal joint. It is a front view of the shaft. It is a principal part expanded sectional view which shows the modification of an uneven | corrugated fitting structure. It is sectional drawing of the uneven | corrugated fitting structure which shows 2nd Embodiment of this invention. It is a principal part expanded sectional view of the uneven | corrugated fitting structure of the said FIG. It is sectional drawing of the decomposition | disassembly state of the said FIG. It is sectional drawing of the uneven | corrugated fitting structure which shows 3rd Embodiment of this invention. It is a principal part expanded sectional view of the uneven | corrugated fitting structure shown in the said FIG. It is sectional drawing of the assembly state of the uneven | corrugated fitting structure shown in the said FIG. It is sectional drawing of the other inner ring | wheel which comprises the uneven | corrugated fitting structure of this invention. It is a principal part expanded sectional view of the inner ring | wheel of the constant velocity universal joint shown in the said FIG. The inner joint member of the tripod type constant velocity universal joint using the uneven | corrugated fitting structure of this invention is shown, (a) is a front view, (b) is sectional drawing, (c) is Z- of (b). It is Z sectional drawing. It is sectional drawing of the uneven | corrugated fitting structure which shows 4th Embodiment of this invention. It is the Y section enlarged view of FIG.

Explanation of symbols

5 Shaft 22 Shaft hole 35 Convex part 36 Concave part 37 Inner diameter surface 38 Concave fitting part 45 Projection part 50 Pocket part 52 Eave part 55 Concave part 63 Concave part 65 Boss part

Claims (16)

In a constant velocity universal joint provided with an outer joint member, an inner joint member inserted into the outer joint member, and a torque transmission member that transmits torque by being interposed between the outer joint member and the inner joint member,
One of the outer diameter surface of the shaft and the inner diameter surface of the shaft hole of the inner joint member is provided with a convex portion whose end surface on the press-fitting start end side is a surface orthogonal to the axial direction. A concave-convex fitting structure comprising a convex part and a concave part is formed by pressing into the other along the convex part and cutting the other with the press-fitted convex part to form a concave part where the entire fitting contact part with the convex part is in close contact with the other. The inner joint member and the shaft that is inserted into the shaft hole of the inner joint member are connected, and the close contact of the convex portion and the concave portion in the entire fitting contact portion is completed by press-fitting the convex portion into the other. Characteristic constant velocity universal joint.   The constant velocity universal joint includes an outer ring as an outer joint member in which a plurality of guide grooves extending in the axial direction are formed on the inner diameter surface, and an inner ring as an inner member in which the plurality of guide grooves extending in the axial direction are formed on the outer diameter surface. And a constant velocity provided with a torque transmission ball disposed on a ball track formed by cooperation of the guide groove of the outer ring and the guide groove of the inner ring, and a cage having a pocket for holding the torque transmission ball. 2. The constant velocity universal joint according to claim 1, wherein a ball is used for the torque transmission member.   The constant velocity universal joint includes an outer ring as an outer joint member in which guide grooves twisted in one circumferential direction with respect to the axis and guide grooves twisted in the other circumferential direction are alternately provided on the inner peripheral surface; A cross groove having an inner ring as an inner member in which a pair of outer ring guide grooves are alternately formed on the outer peripheral surface, and a cage for holding a torque transmission ball. 2. The constant velocity universal joint according to claim 1, wherein said constant velocity universal joint is a ball, and a ball is used as said torque transmission member.   An outer joint member having three track grooves having roller guide surfaces facing in the circumferential direction, a tripod member as an inner joint member having three leg shafts projecting in the radial direction, And a roller as a torque transmission member that is rotatably fitted and is inserted into the track groove, and the roller is movable in the axial direction of the outer joint member along the roller guide surface. The constant velocity universal joint according to claim 1. 2. The constant velocity universal joint according to claim 1, wherein a convex portion is provided on the shaft, and hardness of at least an axial end portion of the convex portion is made higher than that of the inner diameter portion of the inner joint member. 2. The constant velocity universal joint according to claim 1, wherein a convex portion is provided on the inner diameter surface of the shaft hole of the inner joint member, and at least the hardness of the axial end portion of the convex portion is higher than that of the outer diameter portion of the shaft. .   6. The constant velocity universal joint according to claim 5, wherein a pocket portion for accommodating a protruding portion generated by forming the concave portion by the press-fitting is provided on the shaft.   The constant velocity universal joint according to claim 6, wherein a pocket portion for accommodating a protruding portion generated by forming the concave portion by the press-fitting is provided on an inner diameter surface of the shaft hole of the inner joint member.   The pocket portion for storing the protruding portion is provided on the press-fitting start end side of the convex portion of the shaft, and the collar portion for alignment with the shaft hole of the inner joint member is provided on the anti-convex portion side of the pocket portion. The constant velocity universal joint according to claim 7, characterized in that:   The constant velocity universal joint according to any one of claims 1 to 9, wherein any portion in the protruding direction of the convex portion corresponds to the position of the concave portion forming surface before the concave portion is formed.   The maximum diameter dimension of the arc connecting the vertices of the plurality of protrusions is made larger than the inner diameter dimension of the shaft hole of the inner joint member, and the maximum outer diameter dimension of the shaft outer diameter surface between adjacent protrusions is set to the axis of the inner joint member. The constant velocity universal joint according to claim 10, wherein the constant velocity universal joint is smaller than an inner diameter of the hole.   The minimum diameter dimension of the arc connecting the vertices of the plurality of convex portions of the shaft hole is made smaller than the outer diameter size of the inner joint member insertion portion of the shaft, and the maximum inner diameter dimension of the inner diameter surface of the shaft hole between adjacent convex portions is increased. The constant velocity universal joint according to claim 10, characterized in that it is larger than the outer diameter of the inner joint member fitting portion of the shaft.   The circumferential thickness of the projecting direction intermediate portion of the convex portion is smaller than the circumferential dimension at a position corresponding to the intermediate portion between the convex portions adjacent in the circumferential direction. Any one of 12 constant velocity universal joints.   The sum of the circumferential thicknesses of the projecting direction intermediate portions of the convex portions is the sum of the circumferential thicknesses at positions corresponding to the intermediate portions of the mating convex portions that fit between the convex portions adjacent in the circumferential direction. The constant velocity universal joint according to any one of claims 1 to 13, wherein the constant velocity universal joint is also made smaller.   The constant velocity universal joint according to any one of claims 1 to 14, wherein an uneven portion along the axial direction is provided on at least a part of the convex portion side in the axial direction.   The constant velocity universal joint according to claim 15, wherein the concave and convex portions along the axial direction on the convex portion side are formed in a sawtooth shape.

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