JP5623243B2 - Constant velocity universal joint - Google Patents

Description

  The present invention relates to a constant velocity universal joint in which an inner member of a joint is spline-fitted with a shaft.

  For example, there are two types of constant velocity universal joints, such as fixed constant velocity universal joints and sliding constant velocity universal joints, that are built into drive shafts and propeller shafts that transmit rotational force from automobile engines to wheels at constant speed. is there. These constant velocity universal joints have a structure in which two shafts on the driving side and the driven side are connected and the rotational torque can be transmitted at a constant speed even if the two shafts have an operating angle.

  The drive shaft that transmits power from the engine of the automobile to the drive wheel must cope with the angular displacement and axial displacement caused by the change in the relative positional relationship between the differential and the wheel. Side) is equipped with a sliding type constant velocity universal joint that can handle angular displacement and axial displacement, and a fixed constant velocity universal joint with a large operating angle on the drive wheel side (outboard side). It has a structure in which joints are connected by a shaft. As a connection structure between the inner member of the constant velocity universal joint and the shaft, spline coupling (including serration coupling; the same applies hereinafter) is used.

  By the way, in recent automobiles, it is important to reduce the backlash in the circumferential direction of each coupling portion of the power transmission system as a countermeasure against NVH (Noise Vibration Harshness) such as noise and vibration and from the viewpoint of driving responsiveness of the automobile. Is being viewed. Therefore, in the drive shaft, it is desirable that the spline fitting portion between the inner member of the constant velocity universal joint and the shaft is used as a fastening allowance. However, if the tightening allowance is too large, the pressure input during spline fitting increases, the spline part may flutter and excessive stress concentration occurs, and the shaft strength and shaft life may be reduced.

  In view of this, a device has been devised in which the pressure input is not increased while twisting the spline portion of the shaft so as to secure a fitting tightening allowance of the spline. However, the stress at the end of the shaft increases depending on the rotation direction, which may cause a decrease in shaft strength and a decrease in shaft life (see Patent Document 1).

  The problems of the above prior art will be described with reference to FIGS. 17 and 18 show a Rzeppa constant velocity universal joint 101 which is a fixed type constant velocity universal joint. The constant velocity universal joint 101 includes an outer joint member 103, an inner joint member 102, a ball 104 and a cage 105. A plurality of track grooves 107 are formed in the spherical inner peripheral surface 106 of the outer joint member 103 at equal intervals in the circumferential direction and along the axial direction. Track grooves 109 facing the track grooves 107 of the outer joint member 103 are formed on the spherical outer peripheral surface 108 of the inner joint member 102 at equal intervals in the circumferential direction and along the axial direction. A plurality of balls 104 that transmit torque are interposed between the track grooves 107 of the outer joint member 103 and the track grooves 109 of the inner joint member 102. A cage 105 that holds the ball 104 is disposed between the spherical inner peripheral surface 106 of the outer joint member 103 and the spherical outer peripheral surface 108 of the inner joint member 102. The outer periphery of the outer joint member 103 and the outer periphery of the shaft 110 that is spline-fitted to the inner joint member 102 are covered with a boot 111, and grease is enclosed as a lubricant inside the joint.

  As shown in FIG. 17, the centers of curvature of the spherical inner peripheral surface 106 of the outer joint member 103 and the spherical outer peripheral surface 108 of the inner joint member 102 are both formed at the center O of the joint. On the other hand, the center of curvature A of the track groove 107 of the outer joint member 103 and the center of curvature B of the track groove 109 of the inner joint member 102 are offset by an equal distance in the axial direction with respect to the center O of the joint. . As a result, when the joint takes an operating angle, the ball 104 is always guided on a plane that bisects the angle formed by the two axes of the outer joint member 103 and the inner joint member 102 and rotates at a constant speed between the two axes. Torque is transmitted.

  FIG. 19 is an enlarged front view of the inner joint member 102. A female spline 113 is formed in the inner diameter hole 112 of the inner joint member 102. Further, as shown in FIG. 20, a male spline 115 is formed at the shaft end portion 114 of the shaft 110. In both the male spline 115 and the female spline 113, the pitch circle of the spline is a perfect circle. FIG. 22 shows an enlarged cross section of the spline fitting portion. As shown in this figure, the male spline 115 formed on the shaft 110 and the female spline 113 formed on the inner joint member 102 have the same pitch circle diameter PCD. The female spline 113 formed in the inner diameter hole 112 of the inner joint member 102 extends parallel to the axis, while the male spline 115 formed at the shaft end 114 of the shaft 110 has a twist angle γ (see FIG. 21). The value of the twist angle γ is about 10 minutes. Therefore, as shown in FIG. 21, when the male spline 115 (shown by a broken line) of the shaft 110 is press-fitted into the female spline 113 (shown by a solid line) of the inner joint member 102, the tooth surface 115a of the male spline 115 and the female spline 113 are shown. The portion hatched between the tooth surfaces 113 a becomes a tightening margin and compressive stress is generated, and the compressive stress increases at both ends 102 a of the inner joint member 102. When a rotational torque is applied between the shaft 110 and the inner joint member 102, a rotational torque is applied in addition to the above compressive stress. Therefore, the stress at both ends 102a of the inner joint member 102 is increased, the shaft strength is reduced, and the shaft life is reduced. There is a risk of lowering.

  Further, Patent Documents 2 to 4 propose a shape that can provide a high backlash effect while securing the shaft strength, but the shape is complicated and the workability may be significantly reduced.

Japanese Utility Model Publication No. 6-33220 JP 2007-247771 A JP 2007-247770 A JP 2007-247769 A

  The present invention has been proposed in view of the above-described problems, and the object of the present invention is to provide a spline fitting portion between an inner member and a shaft that provides a high backlash effect while taking a conventional processing method. It is providing the constant velocity universal joint which has this.

  As a result of various studies to achieve the above-mentioned object, the present inventors have conceived a novel means of basically performing backlashing using the entire elastic deformation of the inner member.

In order to achieve the above object, the present invention provides a constant velocity universal joint in which an inner member of a joint is spline-fitted with a shaft and is positioned and fixed in the axial direction, and the pitch of at least one of the inner member and the shaft is splined. A circle is formed in an irregular shape with respect to the pitch circle of the round spline, and a plurality of circumferential splines of the spline fitting portion are formed by a radial difference between the pitch circle diameter of the one spline and the pitch circle diameter of the other spline. portion partially has a tightening margin to, characterized in Rukoto this interference portion is formed over the entire length of the axial width of the inner member. Specifically, the tightening margin is about 0.01 mm to 0.03 mm.

  With the above configuration, the overall elastic deformation of the inner member is basically used, and the fastening margins of the spline fitting portion are partially formed at a plurality of locations in the circumferential direction. The pressure input at the time of assembling the members can be kept low, and the circumferential play can be reliably suppressed. Moreover, since the fastening margin part of a spline fitting part is formed over the full length of the axial direction width | variety of an inner member, the circumferential play can be suppressed reliably.

  Specifically, the spline having the irregular shape is formed on the inner member, and a round spline is formed on the shaft. On the contrary, the irregularly shaped spline is formed on the shaft, and the inner member is formed with a round spline. A round spline is defined as one in which the pitch circle of the spline is a perfect circle. With the above configuration, in the spline processing, the inner member side can be broached, while the shaft side is subjected to rolling processing in the case of a round spline, and in the case of an irregular shape such as a triangular shape or a polygonal shape Can be pressed, and both can be easily manufactured by a commonly used processing method.

  Further, the irregularly shaped splines are formed on both the inner member and the shaft, and the irregularly shaped tops of both members are fitted to each other while being shifted from each other in the circumferential direction.

  The irregular shape is a triangular shape or a polygonal shape. The radius difference between the pitch circle diameter of the male spline and the pitch circle diameter of the female spline is about 0.01 mm to 0.03 mm. Particularly preferred is about 0.01 mm to 0.02 mm. Because of the configuration in which tightening margins are generated partially at multiple locations in the circumferential direction of the spline fitting part, pressure input during spline fitting can be suppressed, so the above radius difference can be up to about 0.04 mm. Can be. Thereby, circumferential backlash can be reliably suppressed. In addition, with the above configuration, even when the same material and heat treatment as in the past are used, the pressure input when the shaft and the inner member are spline-fitted can be kept low, and circumferential play can be reliably suppressed.

  The spline of the shaft has a twist angle in the axial direction. Thereby, the pressure input at the time of spline fitting can further be suppressed.

  The inner member is an inner joint member of a constant velocity universal joint having a ball or a tripod member of a tripod type constant velocity universal joint.

  According to the present invention, basically, the overall elastic deformation of the inner member is utilized, and the tightening margins of the spline fitting portion are partially formed at a plurality of locations in the circumferential direction. The pressure input at the time of assembling the direction member can be kept low, and the circumferential play can be reliably suppressed. Furthermore, since the fastening allowance portion of the spline fitting portion is formed over the entire length in the axial direction of the inner member, the circumferential play can be further suppressed.

  In spline processing, the inner member side can be broached, while the shaft side is rolled for round splines and pressed for irregular shapes such as triangles and polygons. Processing can be performed, and both can be easily manufactured by the processing method used normally. Furthermore, even with the same material and heat treatment as in the prior art, the pressure input during the spline fitting of the shaft and the inner member can be kept low, and the circumferential play can be reliably suppressed.

It is a longitudinal cross-sectional view of the constant velocity universal joint of the 1st Embodiment of this invention. It is a front view of the constant velocity universal joint of the 1st Embodiment of this invention. It is the front view which expanded the inner side coupling member. It is the figure which expanded the shaft. It is a figure which shows the fitting state of the spline of 1st Embodiment. It is a figure which shows the fitting state of the spline of 2nd Embodiment. It is a figure which shows the fitting state of the spline of 3rd Embodiment. It is a figure which shows the fitting state of the spline of 4th Embodiment. It is a longitudinal cross-sectional view of the constant velocity universal joint of 5th Embodiment. It is the front view which expanded the tripod member. It is the figure which expanded the shaft. It is a figure which shows the fitting state of the spline of 5th Embodiment. It is a figure which shows the fitting state of the spline of 6th Embodiment. It is a figure which shows the fitting state of the spline of 7th Embodiment. It is a figure which shows the fitting state of the spline of 8th Embodiment. It is a figure which shows the heat processing deformation | transformation of a tripod member. It is a longitudinal cross-sectional view of the conventional constant velocity universal joint. It is a front view of the conventional constant velocity universal joint. It is the front view which expanded the inner joint member of the conventional constant velocity universal joint. It is the figure which expanded the shaft of the conventional constant velocity universal joint. It is explanatory drawing which shows the fitting state of the conventional spline. It is a cross-sectional view which shows the fitting state of the conventional spline.

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

  A first embodiment of the present invention will be described with reference to FIGS. The constant velocity universal joint 1 of this embodiment is a Rzeppa type constant velocity universal joint which is a fixed type constant velocity universal joint. As shown in FIGS. 1 and 2, the constant velocity universal joint 1 includes an outer joint member 3, an inner joint member 2 as an inner member, a ball 4, and a cage 5. Six track grooves 7 are formed on the spherical inner peripheral surface 6 of the outer joint member 3 at equal intervals in the circumferential direction and along the axial direction. Track grooves 9 facing the track grooves 7 of the outer joint member 3 are formed in the spherical outer peripheral surface 8 of the inner joint member 2 at equal intervals in the circumferential direction and along the axial direction. Six balls 4 for transmitting torque are interposed between the track grooves 7 of the outer joint member 3 and the track grooves 9 of the inner joint member 2. A cage 5 that holds the ball 4 is disposed between the spherical inner peripheral surface 6 of the outer joint member 3 and the spherical outer peripheral surface 8 of the inner joint member 2. The outer periphery of the outer joint member 3 and the outer periphery of the shaft 10 splined to the inner joint member 2 are covered with a boot 11, and grease is enclosed as a lubricant inside the joint.

  As shown in FIG. 1, the centers of curvature of the spherical inner peripheral surface 6 of the outer joint member 3 and the spherical outer peripheral surface 8 of the inner joint member 2 are both formed at the center O of the joint. On the other hand, the center of curvature A of the track groove 7 of the outer joint member 3 and the center of curvature B of the track groove 9 of the inner joint member 2 are offset by an equal distance in the axial direction with respect to the center O of the joint. . As a result, when the joint takes an operating angle, the ball 4 is always guided on a plane that bisects the angle formed by the two axes of the outer joint member 3 and the inner joint member 2, and rotates at a constant speed between the two axes. Torque is transmitted.

  FIG. 3 is an enlarged front view of the inner joint member 2. A female spline 13 is formed in the inner diameter hole 12 of the inner joint member 2. As a spline having an irregularly shaped pitch circle with respect to the pitch circle of the round spline, the pitch circle of the female spline 13 is formed in a triangular shape having a small diameter difference (a rice ball shape) having a top portion 13b, and the top portion 13b. The radius difference of the intermediate part between the top parts 13b and 13b is about 0.01 mm-0.03 mm. The female spline 13 of the inner joint member 2 has a triangular pitch circle shape as described above, and extends parallel to the axis.

  FIG. 4 shows the shaft 10. A male spline 15 is formed at the shaft end 14 of the shaft 10. The male spline 15 is a round spline and extends parallel to the axis.

  FIG. 5 shows a state in which a male spline 15 of the shaft 10 (illustration of the tooth surface is omitted and the other embodiments are the same) is press-fitted into the female spline 13 of the inner joint member 2 (the tooth surface is not illustrated and the other embodiments are the same) Indicates. The pitch circle diameter PCDi of the female spline 13 of the inner joint member 2 is indicated by a solid line, and the pitch circle diameter PCDs of the male spline 15 of the shaft 10 is indicated by a broken line. As described above, the pitch circle diameter PCDi of the female spline 13 of the inner joint member 2 is formed into a slight diameter difference triangular shape (summary shape) having the top portion 13b, and the top portion 13b and the intermediate portion between the top portions 13b and 13b. The radius difference is about 0.01 mm to 0.03 mm. The triangle shape of the female spline 13 is exaggerated for easy understanding of the present embodiment and other embodiments described later. In this embodiment, each top portion 13 b is disposed at the groove bottom of the track groove 9. The triangular female spline 13 of the inner joint member 2 can be easily manufactured by broaching as in the prior art. On the other hand, the male spline 15 of the shaft 10 is a round spline. Since it is a round spline, it can be easily manufactured by rolling as in the prior art.

  When the male spline 15 of the shaft 10 is press-fitted into the female spline 13 of the inner joint member 2, the inner joint member 2 is basically based on the radial difference δ between the pitch circle diameter PCDs of the male spline 15 and the pitch circle diameter PCDi of the female spline 13. Is elastically deformed as a whole, and fastening margins 16 (illustrated by hatching) are partially generated at three locations in the circumferential direction. The radius difference between the pitch circle diameter PCDs of the male spline 15 and the pitch circle diameter PCDi of the female spline 13 is about 0.01 mm to 0.03 mm. Particularly preferred is about 0.01 mm to 0.02 mm. In the present embodiment, the pitch circle diameter PCDi of the female spline 13 is larger than the pitch circle diameter PCDs of the male spline 15 at the top portion 13b of the pitch circle of the female spline 13, and the gap is fitted. However, it is also possible to give a slight tightening margin at the top portion 13b, and the same applies to other embodiments described later. Since the interference margins 16 are partially generated at three locations in the circumferential direction of the spline fitting portion, pressure input during the spline fitting can be suppressed. Therefore, the pitch circle diameter PCDs of the male spline 15 and the female The radius difference of the pitch circle diameter PCDi of the spline 13 can be made up to about 0.04 mm. Thereby, circumferential backlash can be reliably suppressed. In addition, since the tightening allowance 16 is formed over the entire length of the inner joint member 2 in the axial direction, it is possible to avoid an increase in pressure input when the spline is engaged, spattering of the spline, and excessive stress concentration. And can increase the shaft life.

  In the present embodiment, the male spline 15 of the shaft 10 is a round spline extending in parallel to the axis, but the male spline 15 may be given a twist angle in the axial direction. The twist angle in this case is desirably smaller than the twist angle γ (about 10 minutes) shown in FIG. By applying a twist angle to the male spline 15 in the axial direction, it is possible to further suppress the pressure input when the spline is fitted. In addition, a round spline having a twist angle can be easily manufactured by rolling as in the conventional case.

  Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment and third and fourth embodiments to be described later, portions having the same functions as those of the first embodiment described above are denoted by the same reference numerals, and redundant description is omitted.

  This embodiment is different from the first embodiment in that a round spline is formed on the inner joint member 2 side and a triangular spline is formed on the shaft 10 side. The pitch circle diameter PCDi of the female spline 13 of the inner joint member 2 is indicated by a solid line, and the pitch circle diameter PCDs of the male spline 15 of the shaft 10 is indicated by a broken line. The pitch circle of the female spline 13 of the inner joint member 2 is a perfect circle and is a round spline. The pitch circle of the male spline 15 of the shaft 10 is formed in a triangular shape having a small diameter difference (a rice ball shape) having a top portion 15b, and the radius difference between the top portion 15b and the middle portion between the top portions 15b and 15b is 0.01 mm to 0 mm. 0.03 mm. Each top portion 15 b is disposed at the groove bottom of the track groove 9. Also in this embodiment, the fastening margin portion 16 is formed over the entire length of the inner joint member 2 in the axial direction, thereby avoiding an increase in pressure input when the spline is fitted, spatter of the spline portion, and excessive stress concentration. It is possible to increase the shaft strength and the shaft life.

  The processing of the male spline 15 having the triangular pitch circle of the shaft 10 can be easily manufactured not by rolling but by pressing. This pressing is performed by a conventional processing method while applying vibration to a mold having a molding surface corresponding to the triangular male spline 15.

  A third embodiment of the present invention will be described with reference to FIG. This embodiment is different from the first embodiment in that the female spline 13 formed on the inner joint member 2 is a pentagon having a slight diameter difference as a spline having a deformed pitch circle with respect to the pitch circle of the round spline. The shape is different. The pitch circle diameter PCDi of the female spline 13 of the inner joint member 2 is formed in a pentagonal shape having a slight diameter difference having a top portion 13b, and the radius difference between the top portion 13b and the middle portion between the top portions 13b and 13b is 0.01 mm to It is 0.03 mm. Similar to the above-described embodiment, when the male spline 15 of the shaft 10 is press-fitted into the female spline 13 of the inner joint member 2, due to the radial difference between the pitch circle diameter PCDs of the male spline 15 and the pitch circle diameter PCDi of the female spline 13, The inner joint member 2 is elastically deformed as a whole, and fastening margins 16 (shown by hatching) are generated at five locations in the circumferential direction. Since the tightening margin 16 is formed over the entire length of the inner joint member 2 in the axial direction, it is possible to avoid an increase in pressure input at the time of spline fitting, spattering of the spline part, and excessive stress concentration. The lifetime can be increased.

  A fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, the male spline 15 of the shaft 10 is also formed in a triangular shape (a rice ball shape) as compared with the first embodiment, and the top 15b of the pitch circle of the triangular male spline 15 and the inner joint member 2 are formed. The tops 13b of the pitch circles of the triangular female splines 13 are press-fitted with being shifted from each other in the circumferential direction. The apex 15b of the pitch circle diameter PCDs of the triangular male spline 15 of the shaft 10 and the radius difference between the intermediate portions between the apexes 15b and 15b and the apex 13b of the pitch circle diameter PCDi of the triangular female spline 13 of the inner joint member 2 And the radius difference of the intermediate part between the top parts 13b and 13b is about 0.01 mm-0.03 mm in all. When the male spline 15 of the shaft 10 is press-fitted into the female spline 13 of the inner joint member 2, the inner joint member 2 as a whole is caused by the difference in the pitch circle diameter PCDs of the male spline 15 and the pitch circle diameter PCDi of the female spline 13. Elastic deformation occurs, and fastening margins 16 (illustrated by hatching) are generated at six locations in the circumferential direction.

  A fifth embodiment of the present invention will be described with reference to FIGS. This embodiment is applied to a tripod type constant velocity universal joint. The constant velocity universal joint 21 includes an outer joint member 23, a tripod member 22 as an inward member, a rolling element 24, and a spherical roller 25. Three track grooves 26 in the axial direction are formed on the inner peripheral portion of the outer joint member 23, and roller guide surfaces 27 in the axial direction are formed on both sides of each track groove 26. The tripod member 22 has three leg shafts 22b formed radially from its boss portion 22a. A spherical roller 25 is fitted to the leg shaft 22 b via a large number of rolling elements 24, and washers 28 and 29 are interposed at both ends of the rolling element 24, and the washer 29 is positioned by a retaining ring 30. Thus, the row of rolling elements 24 is guided on the leg shaft 22b, and the spherical roller 25 is rotatable on the rolling element 24 and is movable in the axial direction of the leg shaft 22b. The spherical roller 25 is rotatably accommodated on the roller guide surface 27 of the outer joint member 23.

  As described above, when the roller guide surface 27 of the outer joint member 23 and the three leg shafts 22b of the tripod member 22 are engaged with each other in the rotational direction via the spherical roller 25, rotational torque is generated from the driving side to the driven side. It is transmitted at a constant speed. Further, each spherical roller 25 rolls on the roller guide surface 27 while rotating with respect to the leg shaft 22b, so that relative axial displacement and angular displacement between the outer joint member 23 and the tripod member 22 are reduced. Absorbed.

  As shown in FIG. 9, a female spline 33 is formed in the inner diameter hole 32 of the boss portion 22 a of the tripod member 22. The female spline 33 and the male spline 35 of the shaft 31 are fitted.

  FIG. 10 is an enlarged front view of the tripod member 22. A female spline 33 is formed in the inner diameter hole 32 of the tripod member 22. As a spline having a deformed pitch circle with respect to the pitch circle of the round spline, the pitch circle of the female spline 33 is formed in a triangular shape having a small diameter difference (a rice ball shape) having a top portion 33b, and the top portion 33b. The radius difference of the intermediate part between the top parts 33b and 33b is about 0.01 mm-0.03 mm. The female spline 33 of the tripod member 22 has a triangular pitch circle shape as described above, and extends parallel to the axis.

  FIG. 11 shows the shaft 31. A male spline 35 is formed at the shaft end 34 of the shaft 31. The male spline 35 is a round spline and extends parallel to the axis.

  In FIG. 12, the pitch circle diameter PCDt of the female spline 33 of the tripod member 22 is indicated by a solid line, and the pitch circle diameter PCDs of the male spline 35 of the shaft 31 is indicated by a broken line. The PCDt of the female spline 33 is formed in a triangular shape with a small diameter difference (a rice ball shape) having a top portion 33b, and the radius difference between the top portion 33b and the middle portion between the top portions 33b and 33b is about 0.01 mm to 0.03 mm. It has become. Similar to the first embodiment, the female spline 33 of the tripod member 22 is a triangular PCDt and extends parallel to the axis. In this embodiment, each top part 33b is arrange | positioned at the boss | hub part 22a of the center position of the leg axis | shaft 22b. The male spline 35 of the shaft 31 is a round spline and extends parallel to the axial direction.

  In the present embodiment, the male spline 35 of the shaft 31 is a round spline extending in parallel to the axis, but the male spline 35 may be provided with a twist angle in the axial direction. In this case, the twist angle is desirably smaller than the twist angle γ (about 10 minutes) shown in FIG. By applying a twist angle to the male spline 35 in the axial direction, it is possible to further suppress the pressure input during the spline fitting. In addition, a round spline having a twist angle can be easily manufactured by rolling as in the conventional case.

  When the male spline 35 of the shaft 31 is press-fitted into the female spline 33 of the tripod member 22, the boss portion 22 a of the tripod member 22 is entirely formed due to the radial difference between the pitch circle diameter PCDs of the male spline 35 and the pitch circle diameter PCDt of the female spline 33. Elastically deformed, and fastening margins 36 (illustrated by hatching) are generated at three locations in the circumferential direction. Since the tightening margin 36 is formed over the entire length of the tripod member 22 in the axial direction, an increase in pressure input at the time of spline fitting, spattering of the spline part and excessive stress concentration can be avoided, and the shaft strength and shaft life can be avoided. Can be increased.

  Since the tripod member 22 has a very large shape, the female spline 33 is deformed into a triangular shape (rice ball shape) after the heat treatment. The modification is shown in FIG. The pitch circle diameter PCDt (1) of the female spline 33 before heat treatment is indicated by a broken line, and the pitch circle diameter PCDt (2) of the female spline 33 after heat treatment is indicated by a solid line. In the present embodiment, by making use of this characteristic of the tripod member 22, the fitting with the round spline of the shaft 31 is set so as to have a tightening margin of about 0.01 mm to 0.03 mm at three locations in the circumferential direction. be able to. In this embodiment, taking advantage of the deformation characteristics of the tripod member 22, each top 33b of the female spline 33 is disposed on the boss 22a at the center position of the leg shaft 22b. In addition, the shape of the female spline 33 of the tripod member 22 after the heat treatment can be set in advance so as to be a quadrangular shape, a pentagonal shape, a hexagonal shape, or the like.

  FIG. 13 shows a sixth embodiment of the present invention. In this embodiment and the seventh and eighth embodiments described later, portions having the same functions as those of the fifth embodiment described above are denoted by the same reference numerals, and redundant description is omitted.

  In the sixth embodiment, the relationship between the female spline 33 and the male spline 35 is the same as that of the second embodiment. A round spline is formed on the tripod member 22, and a triangular spline is formed on the shaft 31 side. The pitch circle diameter PCDt of the female spline 33 of the tripod member 22 is indicated by a solid line, and the pitch circle diameter PCDs of the male spline 35 of the shaft 31 is indicated by a broken line. The pitch circle of the male spline 35 of the shaft 31 is formed in a triangular shape having a small diameter difference (a rice ball shape) having a top portion 35b, and the radius difference between the top portion 35b and the middle portion between the top portions 35b and 35b is 0.01 mm to 0 mm. 0.03 mm. Each top portion 35b is disposed on the boss portion 22a at the center position of the leg shaft 22b. Also in this embodiment, the tightening allowance 36 is partially formed in the circumferential direction of the boss 22a of the tripod member 22 and formed over the entire length of the tripod member 22 in the axial direction. Increase in pressure input, spline parting and excessive stress concentration can be avoided, and shaft strength and shaft life can be increased.

  FIG. 14 shows a seventh embodiment of the present invention. In this embodiment, the relationship between the female spline 33 and the male spline 35 is the same as that of the third embodiment. In this embodiment, the female spline 33 formed on the tripod member 22 has a pentagonal shape with a slight difference in diameter as a spline having a deformed pitch circle with respect to the pitch circle of the round spline. The pitch circle diameter PCDt of the female spline 33 of the tripod member 22 is formed in a pentagonal shape having a slight diameter difference having a top portion 33b, and the radius difference between the top portion 33b and the middle portion between the top portions 33b and 33b is 0.01 mm to 0 mm. 0.03 mm. Similar to the above-described embodiment, when the male spline 35 of the shaft 31 is press-fitted into the female spline 33 of the tripod member 22, the tripod is separated by the radial difference between the pitch circle diameter PCDs of the male spline 35 and the pitch circle diameter PCDt of the female spline 33. The member 22 is elastically deformed as a whole, and fastening margins 36 (shown by hatching) are generated at five locations in the circumferential direction. The fastening margin portion 36 is partially formed in the circumferential direction of the boss portion 22a of the tripod member 22 and is formed over the entire length in the axial direction of the tripod member 22. Therefore, an increase in pressure input during spline fitting, spline It is possible to avoid flaking of parts and excessive stress concentration, and to increase shaft strength and shaft life.

  FIG. 15 shows an eighth embodiment of the present invention. In this embodiment, the relationship between the female spline 33 and the male spline 35 is the same as that of the fourth embodiment. In this embodiment, the male spline 35 of the shaft 31 is also formed in a triangular shape (a rice ball shape), and the top 35b of the pitch circle of the triangular male spline 35 and the pitch circle of the triangular female spline 33 of the tripod member 22 are formed. The top portion 33b of the steel plate is press-fitted while being shifted from each other in the circumferential direction. The apex 35b of the pitch circle diameter PCDs of the triangular male spline 35 of the shaft 31, the radius difference between the intermediate portions between the apexes 35b and 35b, and the apex 33b of the pitch circle diameter PCDi of the triangular female spline 33 of the tripod member 22 The radius difference between the top portions 33b and 33b is about 0.01 mm to 0.03 mm. When the male spline 35 of the shaft 31 is press-fitted into the female spline 33 of the tripod member 22, the tripod member 22 is elastically deformed as a whole due to the difference in pitch circle diameter PCDs of the male spline 35 and the pitch circle diameter PCDi of the female spline 33. Then, tightening margins 36 (illustrated by hatching) are generated at six locations in the circumferential direction.

  In the above embodiments, the spline having a deformed pitch circle with respect to the pitch circle of the round spline has been shown a triangular shape with a slight difference in diameter (a rice ball shape) or a pentagonal shape, but is not limited to this. Alternatively, a rectangular shape, a hexagonal shape, or a polygonal shape constituted by a gentle curve can be appropriately implemented. In short, what is essential is that the fastening allowance of the spline fitting portion is basically formed at a plurality of locations in the circumferential direction by utilizing the overall elastic deformation of the inner member. It may be a simple shape. In any of the embodiments, the dimensional relationship between the pitch circle diameter of the male spline and the pitch circle diameter of the female spline at the top of the pitch circle of the odd-shaped spline can be a gap or provide a slight tightening allowance. It is also possible.

  In the above embodiment, the Rzeppa type constant velocity universal joint and the tripod type constant velocity universal joint are shown. However, the present invention is not limited to this, and other types such as a double offset type constant velocity universal joint and a cross groove type constant velocity universal joint are also shown. It can also be applied to constant velocity universal joints. Further, the number of balls is not limited to six, and can be similarly applied to eight or other constant velocity universal joints.

DESCRIPTION OF SYMBOLS 1 Constant velocity universal joint 2 Inner joint member 3 Outer joint member 4 Ball 5 Cage 6 Spherical inner peripheral surface 7 Track groove 8 Spherical outer peripheral surface 9 Track groove 10 Shaft 12 Inner diameter hole 13 Female spline 13b Top 15b Top 21 Constant velocity universal joint 22 Tripod member 23 Outer joint member 24 Rolling element 25 Spherical roller 31 Shaft 33 Female spline 35 Male spline A, B Track groove curvature center O Joint center δ Radius difference PCD Spline pitch circle diameter

Claims (10)

In the constant velocity universal joint in which the inner member of the joint is splined to the shaft and positioned and fixed in the axial direction, the pitch circle of at least one of the inner member and the shaft is smaller than the pitch circle of the round spline. is formed in a deformed shape, the radius difference between the pitch circle diameter of the pitch circle diameter and the other splines of that one of the splines, partially have an interference to a plurality of positions in the circumferential direction of the spline fitting portion, the constant velocity universal joint interference unit is characterized that you have been formed over the entire length of the axial width of the inner member.   The constant velocity universal joint according to claim 1, wherein the tightening margin is 0.01 mm to 0.03 mm.   3. The constant velocity universal joint according to claim 1, wherein the irregularly shaped spline is formed on an inner member, and the shaft is formed with a round spline. 4.   3. The constant velocity universal joint according to claim 1, wherein the deformed spline is formed on a shaft, and the inner member is formed with a round spline. 4.   3. The deformed spline is formed on either the inner member or the shaft, and the deformed tops of the two members are fitted to each other while being shifted from each other in the circumferential direction. Constant velocity universal joint.   The constant velocity universal joint according to any one of claims 1 to 5, wherein the deformed shape is a triangular shape.   The constant velocity universal joint according to any one of claims 1 to 5, wherein the deformed shape is a polygonal shape.   4. The constant velocity universal joint according to claim 1, wherein the spline of the shaft has a twist angle in the axial direction.   The constant velocity universal joint according to any one of claims 1 to 8, wherein the inner member is an inner joint member of a constant velocity universal joint having a ball. The constant velocity universal joint according to any one of claims 1 to 8, wherein the inner member is a tripod member of a tripod type constant velocity universal joint.

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