JP4973930B2 - Sliding tripod type constant velocity joint - Google Patents

Description

  The present invention relates to a sliding tripod type constant velocity joint.

  As a conventional sliding tripod type constant velocity joint, there is one in which a roller can swing with respect to a tripod shaft portion in order to reduce induced thrust force. For example, in Japanese Patent Laid-Open No. 3-172619 (Patent Document 1), the inner peripheral surface of the inner roller constituting the roller is cylindrical, and the outer peripheral surface of the tripod shaft portion is spherically convex. Thereby, the roller can swing with respect to the tripod shaft portion, and can slide in the axial direction between the inner roller and the tripod shaft portion. The direction in which the outer roller constituting the roller tries to roll on the roller groove always coincides with the direction in which the roller groove extends. As a result, no slip occurs between the outer roller and the roller groove, and the induced thrust force can be reduced. This induced thrust force causes generation of vibrations and noise of the vehicle body and affects the NVH performance of the vehicle.

  In Japanese Patent Laid-Open No. 2000-320563 (Patent Document 2), the axial cross-sectional shape of the inner peripheral surface of the inner roller is an arc-shaped convex shape, and the outer peripheral surface of the tripod shaft portion is an elliptic cylinder. Accordingly, the roller can swing with respect to the tripod shaft portion, and can slide in the axial direction between the inner roller and the tripod shaft portion.

Japanese Patent Laid-Open No. 2002-213478 (Patent Document 3) and Japanese Patent Laid-Open No. 2002-327773 (Patent Document 4) disclose that the inner circumferential surface of the inner roller has an arcuate cross-sectional shape, and the tripod shaft portion By making the outer peripheral surface convex in a spherical shape, the inner roller can swing with respect to the tripod shaft. However, since the inner roller and the tripod shaft are restricted in relative movement in the axial direction, the inner roller can be moved relative to the needle roller and outer roller in the axial direction.
Japanese Patent Laid-Open No. 3-172619 JP 2000-320563 A JP 2002-213478 A JP 2002-327773 A

  Here, in the sliding tripod type constant velocity joint described in Patent Document 1, the inner diameter of the cylindrical inner peripheral surface of the inner roller is substantially the same as the outer diameter of the spherical convex surface of the tripod shaft portion. For this reason, when the constant velocity joint rotates, the contact portion between the inner roller of the cylindrical inner peripheral surface and the spherical convex tripod shaft is an elliptical range that is long in the circumferential direction. The wider the elliptical contact range, the larger the moment is exerted by the friction generated between the roller and the tripod shaft when the roller swings relative to the tripod shaft. This friction moment acts so that the roller is less likely to swing with respect to the tripod shaft. That is, the greater the friction moment, the higher the possibility that the roller will move with the tripod shaft. As a result, there is a possibility that the direction in which the outer roller tries to roll the roller groove does not coincide with the direction in which the roller groove extends. If it does so, a slip generate | occur | produces between an outer roller and a roller groove | channel, and an induced thrust force may arise. Therefore, it is required to narrow the elliptical contact range.

  Further, in the sliding tripod constant velocity joint described in Patent Document 2, the axial cross-sectional shape of the inner peripheral surface of the inner roller is an arc-shaped convex shape, and the tripod shaft portion is an elliptic cylinder. For this reason, in the torque transmission site | part of an inner roller and a tripod shaft part, it becomes convex contact. Therefore, the contact surface pressure between the inner roller and the tripod shaft portion increases, and there is a risk that the service life may be reduced. That is, a configuration that can reduce the surface pressure of the contact portion between the inner roller and the tripod shaft is desired.

  In the sliding tripod constant velocity joints described in Patent Documents 3 and 4, the contact range between the inner roller and the tripod shaft portion is the same as that of Patent Document 1 described above. Therefore, it is required to narrow the elliptical contact range. Further, in Patent Documents 3 and 4, since the relative movement in the axial direction between the inner roller and the tripod shaft is restricted, the inner roller can be moved relative to the needle roller and the outer roller in the axial direction. It is said. However, in this case, some of the needle rollers generate sliding friction with the inner roller. This may adversely affect the rolling of the entire needle roller in the circumferential direction. Therefore, it is desirable that the sliding in the axial direction is performed between the inner roller and the tripod shaft as in Patent Document 1 or 2.

  The present invention has been made in view of such circumstances, and while reducing the contact surface pressure between the inner roller and the tripod shaft, the elliptical contact range is narrowed, and the inner roller and the tripod shaft An object of the present invention is to provide a sliding tripod type constant velocity joint that can slide in the axial direction.

  The sliding tripod constant velocity joint of the present invention has a cylindrical shape, an outer ring in which three roller grooves extending in the axial direction are formed on the inner peripheral surface, a boss connected to the shaft, and a boss A tripod having three tripod shafts that are erected so as to extend radially outward of the boss portion from the outer peripheral surface of the boss portion, and an annular tripod that rotates relative to the tripod shaft And a roller that is swingable and supported by the tripod shaft portion so as to be slidable in the extending direction of the tripod shaft portion, and that is rotatably fitted in the roller groove.

The outer peripheral surface of the tripod shaft portion is formed in an arc-convex shape in the radial cross section of the boss portion, and the roller includes an outer roller that is inserted into the roller groove so that the shaft center is orthogonal to the extending direction of the roller groove. The tube has a cylindrical shape , the axial cross-sectional shape of the inner peripheral surface thereof is formed in an arc concave shape so as to be relatively movable in the extending direction of the tripod shaft portion with respect to the tripod shaft portion, and is relatively rotated with respect to the outer roller. And an inner roller that is coaxially disposed radially inward of the outer roller and is restricted from axial movement relative to the outer roller.
The maximum inner diameter D1 of the inner roller is set to be larger than the diameter d1 of the maximum circumscribed circle in the cross section in the direction orthogonal to the tripod shaft, and a radial gap is formed between the outer peripheral surface of the tripod shaft and the inner peripheral surface of the inner roller. Is formed.

  According to the sliding tripod type constant velocity joint of the present invention, the axial sectional shape of the inner peripheral surface of the inner roller is such that the inner roller can move relative to the tripod shaft in the extending direction of the tripod shaft. Is formed in an arc concave shape. Therefore, the inner roller and the tripod shaft can be moved relative to each other in the axial direction. On the other hand, the inner roller is restricted from moving in the axial direction with respect to the outer roller.

  Furthermore, according to the sliding tripod constant velocity joint of the present invention, the axial sectional shape of the inner peripheral surface of the inner roller is an arc concave shape, and the extending sectional shape of the outer peripheral surface of the tripod shaft portion is an arc convex shape. . Furthermore, the maximum inner diameter D1 of the inner roller is set to be larger than the diameter d1 of the maximum circumscribed circle in the cross-section in the direction perpendicular to the stretch of the tripod shaft portion. That is, according to the relative position in the axial direction between the inner roller and the tripod shaft, the circumferential length of the elliptical range where the inner roller and tripod shaft are in contact (the length corresponding to the major axis of the elliptical contact range). Will be different. Therefore, as compared with Patent Document 1, there is always a case where the circumferential length of the elliptical contact range is shortened. Thereby, the friction moment generated when the constant velocity joint rotates can be reduced, and as a result, the induced thrust force can be reduced.

  Further, one of the inner roller and the tripod shaft portion is concave and the other is convex, and the convex portions are not in contact with each other as in Patent Document 2. Therefore, compared with patent document 2, both surface pressure can be reduced and the improvement of a lifetime can be aimed at.

  Here, the extension direction position where the maximum circumscribed circle in the extension orthogonal cross section of the tripod shaft portion is located is defined as the shaft portion reference position, and from the shaft portion reference position with respect to the distance from the shaft portion reference position to the tip side of the tripod shaft portion. The amount of diameter reduction of the circumscribed circle that decreases toward the distal end side is defined as the first diameter reduction ratio of the shaft portion, and the shaft portion reference position to the base end side with respect to the distance from the shaft portion reference position to the base end side of the tripod shaft portion The amount of diameter reduction of the circumscribed circle that decreases toward the head is defined as the shaft portion second diameter reduction ratio. The axial position where the maximum inner diameter is located on the inner peripheral surface of the inner roller is defined as the roller reference position, and from the roller reference position with respect to the distance from the roller reference position to one end side of the inner roller corresponding to the tip side of the tripod shaft portion. The amount of reduction in the inner diameter that is reduced toward the one end side is defined as the roller first reduction ratio, and the roller reference relative to the distance from the roller reference position to the other end side of the inner roller corresponding to the base end side of the tripod shaft portion The diameter reduction amount of the inner diameter that is reduced from the position toward the other end side is defined as a roller second reduction ratio.

  In the sliding tripod type constant velocity joint of the present invention, the first shaft diameter reduction ratio is set larger than the first roller diameter reduction ratio, and the second shaft diameter reduction ratio is the second roller diameter reduction ratio. It is better to set a larger value. Thereby, an inner roller and a tripod shaft part can be relatively moved to an axial direction reliably.

  In the sliding tripod constant velocity joint of the present invention, the radial cross-sectional shape of the boss portion on the outer peripheral surface of the tripod shaft portion is a circular arc, and the axial direction of the inner roller on the inner peripheral surface of the inner roller The cross-sectional shape is an arc concave shape, and the radius ra of the radial cross section of the boss portion on the outer peripheral surface of the tripod shaft portion and the radius Ra of the axial cross section of the inner roller on the inner peripheral surface of the inner roller are expressed by Equation (1). Satisfy the relationship. Thereby, the inner roller can reliably move relative to the tripod shaft portion in the extending direction of the tripod shaft portion.

  In this way, when the outer peripheral surface side of the tripod shaft portion is an arc convex shape and the inner peripheral surface side of the inner roller is an arc concave shape, the radius Ra of the inner roller axial cross section on the inner peripheral surface of the inner roller, The maximum inner diameter D1 of the inner peripheral surface of the roller may satisfy the relationship of the formula (2). Thereby, the relative movement amount of the tripod shaft portion and the inner roller in the extending direction of the tripod shaft portion can be secured sufficiently large. Furthermore, the opening diameter of the inner roller can be made relatively large. Therefore, it becomes easy to insert the tripod shaft portion on the inner peripheral side of the inner roller.

  In addition, when the outer peripheral surface side of the tripod shaft portion is an arc convex shape and the inner peripheral surface side of the inner roller is an arc concave shape, the radius ra of the radial section of the boss portion on the outer peripheral surface of the tripod shaft portion, and the inner roller It is preferable that the maximum inner diameter D1 of the inner peripheral surface satisfies the relationship of Expression (3). Thereby, the relative movement amount of the tripod shaft portion and the inner roller in the extending direction of the tripod shaft portion can be secured sufficiently large.

  In addition, when the outer peripheral surface side of the tripod shaft portion is an arc convex shape and the inner peripheral surface side of the inner roller is an arc concave shape, the radius ra of the radial section of the boss portion on the outer peripheral surface of the tripod shaft portion, and the inner roller The radius Ra of the inner roller axial cross section on the inner peripheral surface and the maximum inner diameter D1 of the inner peripheral surface of the inner roller satisfy the relationship of Expression (4). Thereby, the relative movement amount of the tripod shaft portion and the inner roller in the extending direction of the tripod shaft portion can be ensured more reliably. Furthermore, the opening diameter of the inner roller can be made relatively large. Therefore, it becomes easy to insert the tripod shaft portion on the inner peripheral side of the inner roller.

  In the above-described sliding tripod type constant velocity joint of the present invention, the outer peripheral surface side of the tripod shaft portion has an arc convex shape, and the inner peripheral surface side of the inner roller has an arc concave shape. Also good. That is, in the sliding tripod constant velocity joint of the present invention, the radial cross-sectional shape of the boss portion on the outer peripheral surface of the tripod shaft portion is formed in an elliptical shape in which the extending direction of the tripod shaft portion is a short diameter, and the inner roller The axial direction cross-sectional shape of the inner roller on the inner peripheral surface may be a circular arc concave shape. Also in this case, the inner roller can reliably move relative to the tripod shaft portion in the extending direction of the tripod shaft portion.

  In addition to the above, in the sliding tripod type constant velocity joint of the present invention, the radial cross-sectional shape of the boss portion on the outer peripheral surface of the tripod shaft portion is an arc convex shape, and the inner peripheral surface on the inner peripheral surface of the inner roller is The cross-sectional shape in the axial direction of the roller may be formed in an elliptical shape having the major axis in the axial direction of the inner roller. Also in this case, the inner roller can reliably move relative to the tripod shaft portion in the extending direction of the tripod shaft portion. Furthermore, the opening diameter of the inner roller can be made relatively large. Therefore, it becomes easy to insert the tripod shaft portion on the inner peripheral side of the inner roller.

  In addition to the above, in the sliding tripod constant velocity joint of the present invention, the radial cross-sectional shape of the boss portion on the outer peripheral surface of the tripod shaft portion is an ellipse whose extending direction of the tripod shaft portion is the minor axis. The axial direction cross-sectional shape of the inner roller formed on the inner peripheral surface of the inner roller may be formed in an elliptical shape having a major axis in the axial direction of the inner roller. Also in this case, the inner roller can reliably move relative to the tripod shaft portion in the extending direction of the tripod shaft portion. Furthermore, the opening diameter of the inner roller can be made relatively large. Therefore, it becomes easy to insert the tripod shaft portion on the inner peripheral side of the inner roller.

  Here, in the above description, the cross-sectional shape in the stretching direction of the tripod shaft portion and the cross-sectional shape in the axial direction of the inner roller have been described. Next, the cross-sectional shape in the orthogonal direction of the tripod shaft and the radial cross-sectional shape of the inner roller will be described.

  That is, in the sliding tripod type constant velocity joint of the present invention, the cross-sectional shape in the extending orthogonal direction of the tripod shaft portion on the outer peripheral surface of the tripod shaft portion may be formed in a perfect circle. Thereby, the processing of the outer peripheral surface of the tripod shaft portion is facilitated, and the cost can be reduced.

  In addition to the perfect circle, the cross-sectional shape of the tripod shaft portion on the outer peripheral surface of the tripod shaft portion is formed in an elliptical shape in which the axial direction side of the boss portion has a short diameter and the circumferential direction side of the boss portion has a long diameter. You may do it. Thereby, the circumferential direction length of the elliptical range which an inner roller and a tripod shaft part contact can be shortened. Therefore, the friction moment generated when the constant velocity joint rotates can be further reduced, and as a result, the induced thrust force can be further reduced.

  In addition to the perfect circle and ellipse, the cross-sectional shape of the tripod shaft portion on the outer peripheral surface of the tripod shaft portion in the direction perpendicular to the stretching direction is such that the axial direction side of the boss portion is the short direction and the circumferential direction side of the boss portion is the longitudinal direction. The cross-sectional shape of the tripod shaft portion in the longitudinal direction at both end faces in the longitudinal direction is a circular arc, and the radius rb of the cross-section in the orthogonal direction of the tripod shaft portion at both end surfaces in the longitudinal direction and the stretch orthogonal direction of the tripod shaft portion. You may make it satisfy | fill the relationship of Formula (5) with the diameter d1 of the largest circumscribed circle in a direction cross section.

  In the case of rb = d1 / 2, it is almost the same as the case of the perfect circle described above. In the case of rb <d1 / 2, the circumferential length of the elliptical range in which the inner roller and the tripod shaft are in contact can be made shorter. Therefore, the friction moment generated when the constant velocity joint rotates can be further reduced, and as a result, the induced thrust force can be further reduced.

  In addition, forming in the shape of the arc concave shape, the arc convex shape, the ellipse, the perfect circle, etc. in the above means that it is designed in the corresponding shape and formed based on the design dimension. Therefore, it does not mean that the resulting shape is formed as a result due to a manufacturing error or the like. For example, being formed into an ellipse means being designed into an ellipse and processed based on the design dimensions. In other words, the term “formed in an ellipse” does not include a shape that is formed in an ellipse due to a manufacturing error or the like.

  According to the sliding tripod type constant velocity joint of the present invention, the contact surface pressure between the inner roller and the tripod shaft portion is reduced, the oval contact range is narrowed, and the gap between the inner roller and the tripod shaft portion is reduced. Can slide in the axial direction.

  Next, the present invention will be described in more detail with reference to embodiments. Here, the sliding tripod type constant velocity joint (hereinafter, simply referred to as “constant velocity joint”) of the present embodiment will be described by taking as an example a case where it is used for coupling a power transmission shaft of a vehicle. For example, it is a case where it uses for the connection part of the shaft part connected with the differential gear, and shafts, such as a drive shaft.

<First embodiment>
(Configuration of constant velocity joint 1)
The configuration of the constant velocity joint 1 of the first embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view (diameter cross-sectional view) in which a part of the constant velocity joint 1 is cut in the radial direction.

  As shown in FIG. 1, the constant velocity joint 1 includes an outer ring 10 connected to a differential gear (not shown), a tripod 20 connected to a shaft (not shown), an outer ring 10, and a tripod 20. It is comprised from the roller 30 interposed.

  The outer ring 10 is formed in a cylindrical shape (for example, a bottomed cylindrical shape), and one end side is connected to the differential gear. Three roller grooves 11 extending in the outer ring axial direction (front-rear direction in FIG. 1) are formed at equal intervals in the circumferential direction of the outer ring shaft on the inner peripheral surface of the cylindrical portion of the outer ring 10.

  The tripod 20 is disposed inside the cylindrical portion of the outer ring 10. The tripod 20 includes a boss portion 21 and three tripod shaft portions 22. The boss portion 21 has a cylindrical shape, and an inner peripheral spline 21a is formed on the inner peripheral side. The inner peripheral spline 21a is fitted and connected to the outer peripheral spline at the end of the drive shaft (not shown).

  Each tripod shaft portion 22 is erected so as to extend from the outer peripheral surface of the boss portion 21 outward in the radial direction of the boss portion 21. These tripod shaft portions 22 are formed at equal intervals (120 ° intervals) in the circumferential direction of the boss portion 21. And the tip part of each tripod shaft part 22 is inserted in each roller groove 11 of outer ring 10. The detailed shape of tripod shaft 22 will be described later.

  The roller 30 has an annular shape as a whole. The roller 30 is disposed on the outer peripheral side of the tripod shaft portion 22. The roller 30 is supported by the tripod shaft 22 so as to be rotatable and swingable with respect to the tripod shaft 22. Further, the roller 30 is supported by the tripod shaft portion 22 so as to be slidable in the extending direction of the tripod shaft portion 22. And the roller 30 is inserted in the roller groove | channel 11 so that rolling is possible. The roller 30 includes an outer roller 31, an inner roller 32, a needle roller 33, and retaining rings 34 and 35.

  The outer roller 31 is formed in a cylindrical shape. The outer peripheral surface of the outer roller 31 has a shape corresponding to the roller groove 11, that is, a shape obtained by inverting the roller groove 11. The outer roller 31 is inserted into the roller groove 11 so that its axis is perpendicular to the extending direction of the roller groove 11. Further, the inner peripheral surface of the outer roller 31 is formed into a cylindrical shape, that is, substantially the same diameter over the axial direction of the outer roller 31. However, retaining ring grooves 31 a and 31 b are formed on both inner openings of the outer roller 31 over the entire circumference.

  The inner roller 32 is formed in a cylindrical shape. The axial length of the inner roller 32 corresponds to the distance between the retaining ring grooves 31 a and 31 b formed in the outer roller 31. The outer peripheral surface of the inner roller 32 is cylindrical, that is, has the same diameter over the entire axial direction of the inner roller 32. The outer diameter of the inner roller 32 is formed to be smaller than the inner diameter of the outer roller 31. The inner roller 32 is spaced apart from the inner side of the outer roller 31 in the radial direction. In the gap between the inner roller 32 and the outer roller 31, a plurality of needle rollers 33 are arranged over the entire circumference. The inner roller 32 can rotate relative to the outer roller 31 through the needle roller 33. Further, the inner roller 32 is coaxially disposed radially inward with respect to the outer roller 31. Moreover, the axial cross-sectional shape of the inner roller 32 in the inner peripheral surface 32a of the inner roller 32 is formed in a circular arc concave shape. Details of the inner peripheral surface 32a of the inner roller 32 will be described later.

  The retaining rings 34 and 35 are C-shaped with cut portions. That is, the retaining rings 34 and 35 have a shape that can be reduced in diameter. These retaining rings 34 and 35 are fitted into retaining ring grooves 31a and 31b of the outer roller 31, respectively. The retaining rings 34 and 35 are engaged with the inner roller 32 and the needle roller 33 in the axial direction of the roller 30. That is, the retaining rings 34 and 35 restrict the inner roller 32 and the needle roller 33 from moving relative to the outer roller 31 in the axial direction.

(Detailed shape of tripod shaft 22)
Next, the detailed shape of the tripod shaft part 22 will be described with reference to FIGS. FIG. 2 shows only the tripod shaft portion 22 and the inner roller 32. Specifically, FIG. 2A is a sectional view of the tripod shaft portion 22 and the inner roller 32 in the extending direction of the tripod shaft portion 22 (also an axial sectional view of the inner roller 32). FIG.2 (b) is AA sectional drawing of Fig.2 (a). That is, FIG. 2B is a cross-sectional view in the direction orthogonal to the tripod shaft 22 of the tripod shaft 22 and the inner roller 32 (also a cross-sectional view in the direction orthogonal to the axis of the inner roller 32).

  Here, the radial cross section of the boss portion 21 on the outer peripheral surface 22a of the tripod shaft portion 22 as shown in FIG. 2A is referred to as a “first longitudinal section of the tripod shaft portion 22”. Although not shown, a section in the shaft axis direction on the outer peripheral surface 22a of the tripod shaft portion 22 is referred to as a “second longitudinal section of the tripod shaft portion 22”. A cross section in the direction perpendicular to the extension of the tripod shaft portion 22 on the outer peripheral surface 22a of the tripod shaft portion 22 as shown in FIG. 2B is referred to as a “cross section of the tripod shaft portion 22”. The central portion of the tripod shaft portion 22 in the extending direction passing through the axis of the tripod shaft portion 22 is defined as o1.

  As shown in FIG. 2B, the tripod shaft portion 22 has a top surface 22b and a constricted portion 22c on the boss portion 21 side.

  The cross-sectional shape of the tripod shaft portion 22 is formed by cutting out the upper and lower surfaces of a perfect circle in FIG. That is, the cross-sectional shape of the tripod shaft portion 22 is such that the axial direction side (shaft axial direction side) of the boss portion 21 is the short side direction, and the circumferential direction side (torque transmission direction side) of the boss portion 21 is the longitudinal direction. . The width in the short direction is w1 over the entire extending direction of the tripod shaft portion 22.

  On the other hand, as shown in FIG. 2A, the longitudinal width is d1, which is the largest in the center of the tripod shaft portion 22 in the extending direction. That is, the diameter of the maximum circumscribed circle of the cross section of the tripod shaft portion 22 is d1. Accordingly, in the cross section of the tripod shaft portion 22, the short-side width w1 and the longest maximum width d1 have the relationship of Expression (6).

  The longitudinal width decreases from the central portion in the extending direction of the tripod shaft portion 22 toward the distal end side, and decreases from the central portion toward the proximal end side. Specifically, both end surfaces in the longitudinal direction of the cross-sectional shape of the tripod shaft portion 22 are formed in a circular arc shape. The relationship between the arc-convex radius rb of the cross-sectional shape and the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 22 is expressed by Equation (7). Furthermore, the diameter d2 of the circumscribed circle on the top surface 22b of the tripod shaft part 22 and the diameter d3 of the circumscribed circle on the lower surface 22d of the tripod shaft part 22 are the same. In other words, the relationship between the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 22, the diameter d2 of the circumscribed circle of the top surface 22b, and the diameter d3 of the circumscribed circle of the lower surface 22d is expressed by Equation (8). Here, the axial distance between the top surface 22b and the bottom surface 22d is t1. Note that the top surface 22b of the tripod shaft portion 22 is actually a slightly convex curved surface, and the circumscribed circle of the top surface 22b is the top surface 22b and the outer peripheral surface 22a of the tripod shaft portion 22. This corresponds to the outer diameter of the boundary portion.

  Further, the first vertical cross-sectional shape of the tripod shaft portion 22 is formed in a circular arc shape. The relationship between the arc convex radius ra of the first vertical cross-sectional shape and the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 22 is expressed by Equation (9). That is, as shown in FIG. 2A, the arc-convex center point o <b> 3 having the first vertical cross-sectional shape is shifted from the center point o <b> 1 of the tripod shaft part 22 toward the outer peripheral surface 22 a side.

  Further, as shown in FIG. 2B, the cross-sectional shape of the tripod shaft portion 22 is a shape obtained by cutting the upper and lower surfaces of FIG. Is linear.

(Detailed shape of inner roller 32)
Next, the detailed shape of the inner roller 32 will be described with reference to FIGS. Here, an axial section of the inner roller 32 on the inner circumferential surface 32a of the inner roller 32 as shown in FIG. 2A is referred to as a “longitudinal section of the inner roller 32”. Further, a radial section of the inner roller 32 on the inner peripheral surface 32a of the inner roller 32 as shown in FIG. 2B is referred to as a “cross section of the inner roller 32”. The central portion of the inner roller 32 in the axial direction passing through the axis of the inner roller 32 is O2.

  A cross-sectional shape of the inner roller 32 is formed in a perfect circle over the entire axial direction of the inner roller 32. As shown in FIG. 2A, the cross section of the inner roller 32 is D1 having the largest central portion in the axial direction of the inner roller 32. That is, the maximum inner diameter of the inner roller 32 is D1. The maximum inner diameter D1 of the inner roller 32 is larger than the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 22. That is, the relationship between the maximum inner diameter D1 of the inner roller 32 and the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 22 is the relationship of Expression (10).

  And the longitudinal cross-sectional shape of the inner roller 32 becomes small toward the one opening 32b (lower opening of FIG. 2 (a)) from the axial direction center part of the inner roller 32, and the other opening 32c (FIG. 2 (a) upper opening). Specifically, the longitudinal cross-sectional shape of the inner roller 32 is an arc concave shape. The relationship between the radius Ra of the circular arc concave shape of the inner roller 32 and the maximum inner diameter D1 of the inner roller 32 is expressed by the equation (11). That is, as shown in FIG. 2A, the arc concave center point O <b> 4 of the longitudinal cross-sectional shape of the inner roller 32 is shifted from the center point o <b> 2 of the inner roller 32 to the far side from the corresponding inner peripheral surface.

  Furthermore, the diameter D2 of the one opening 32b of the inner roller 32 and the diameter D3 of the other opening 32c are the same. Further, the diameters D2 and D3 of the openings 32b and 32c of the inner roller 32 are smaller than the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 22. Further, the diameters D <b> 2 and D <b> 3 of the openings 32 b and 32 c of the inner roller 32 are made larger than the lateral width w <b> 1 of the cross-sectional shape of the tripod shaft part 22. That is, the relationship between the diameter d1 of the maximum circumscribed circle of the tripod shaft part 22, the transverse width w1 of the cross-sectional shape of the tripod shaft part 22, the diameter D2 of the one opening 32b, and the diameter D3 of the other opening 32c is 12).

  And the relationship of Formula (13) can be derived from the relationship of Formula (9), (10), and (11). Furthermore, the axial width of the inner roller 32 is T1. The relationship between the axial width T1 of the inner roller 32 and the axial distance t1 between the top surface 22b and the lower surface 22d of the tripod shaft portion 22 is expressed by Equation (14).

  That is, the following can be said from the relationship of Expression (13). First, the position in the extending direction where the maximum circumscribed circle in the cross section of the tripod shaft portion 22 is located is defined as the shaft portion reference position. Subsequently, the diameter of the circumscribed circle that decreases in diameter from the shaft reference position toward the tip side with respect to the distance from the shaft reference position to the tip side (top surface 22b side) of the tripod shaft portion 22 is set to the first shaft portion. It is defined as the diameter reduction rate. Subsequently, the amount of reduction in the diameter of the circumscribed circle that is reduced in diameter from the shaft reference position to the base end side with respect to the distance from the shaft reference position to the base end side (lower surface 22d side) of the tripod shaft portion 22 is set to the shaft portion first. It is defined as the double diameter reduction rate.

  Further, an axial position where the maximum inner diameter is located on the inner peripheral surface 32a of the inner roller 32 is defined as a roller reference position. Subsequently, with respect to the distance from the roller reference position to one end side (the other opening 32c side) corresponding to the tip end side of the tripod shaft portion 22, the diameter of the inner diameter is reduced from the roller reference position toward the one end side of the inner roller 32. The amount is defined as the roller first diameter reduction rate. Next, the inner diameter that decreases from the roller reference position toward the other end side with respect to the distance from the roller reference position to the other end side (one opening 32b side) of the inner roller 32 corresponding to the base end side of the tripod shaft portion 22. The amount of diameter reduction is defined as the roller second diameter reduction rate.

  When defined in this way, the relationship of the expression (13) is such that the shaft first diameter reduction rate is set larger than the roller first diameter reduction rate, and the shaft portion second diameter reduction rate is the roller first diameter reduction rate. The relationship is set to be larger than the double diameter reduction rate.

(Assembly of tripod shaft 22 and inner roller 32)
Next, assembly of the tripod shaft portion 22 and the inner roller 32 will be described with reference to FIG. FIG. 3 is a view showing a state in which the inner roller 32 is assembled to the tripod shaft portion 22. Here, from Expression (12), the diameters D2 and D3 of the openings 32b and 32c of the inner roller 32 are smaller than the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 22. Therefore, the tripod shaft portion 22 cannot be inserted on the inner peripheral side of the inner roller 32 with the tripod shaft portion 22 and the inner roller 32 positioned coaxially. Therefore, as shown in FIG. 3, the axis of the tripod shaft 22 and the axis of the inner roller 32 are arranged so as to intersect with each other at an inclination, or arranged so as to be twisted. In this state, the tripod shaft portion 22 is inserted on the inner peripheral side of the inner roller 32.

  Here, from the equation (12), the transverse width w1 of the cross-sectional shape of the tripod shaft portion 22 is made smaller than the diameter D3 of the other opening 32c of the inner roller 32. Furthermore, from equation (13), the arc convex radius ra of the first longitudinal section of the tripod shaft portion 22 is made smaller than the arc concave radius Ra of the cross section of the inner roller 32. Further, the arc convex radius ra of the first vertical cross-sectional shape of the tripod shaft portion 22 is smaller than the radius D1 / 2 of the maximum inner diameter D1 of the inner roller 32 and the arc concave radius of the cross-sectional shape of the inner roller 32 is. Ra is set larger than the radius D1 / 2 of the maximum inner diameter D1 of the inner roller 32. Furthermore, the axial distance t1 between the top surface 22b and the lower surface 22d of the tripod shaft portion 22 is made smaller than the axial width T1 of the inner roller 32.

  Then, the outer peripheral surface 22a of the tripod shaft portion 22 and the inner peripheral surface 32a of the inner roller 32 are shaped as described above, so that the tripod shaft portion 22 is reliably and easily disposed on the inner peripheral side of the inner roller 32. Can be inserted.

(Operation of constant velocity joint 1)
Next, the operation of the constant velocity joint 1 Specifically, the mutual operation of the tripod shaft portion 22 and the inner roller 32 will be described. Here, the inner roller 32 is restricted by the retaining rings 34 and 35 so that it cannot move relative to the outer roller 31 in the axial direction.

  On the other hand, from equation (10), the maximum inner diameter D1 of the inner roller 32 is made larger than the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 22. Further, from the equation (13), the shaft first reduction ratio is set to be larger than the roller first reduction ratio, and the shaft second reduction ratio is set to be larger than the roller second reduction ratio. It becomes a relationship. That is, in the state where the tripod shaft 22 is inserted on the inner peripheral side of the inner roller 32, a radial clearance is formed between the outer peripheral surface 22 a of the tripod shaft 22 and the inner peripheral surface 32 a of the inner roller 32. Yes. Therefore, the tripod shaft portion 22 can be relatively moved in the axial direction on the inner peripheral side of the inner roller 32. Further, the tripod shaft portion 22 can swing and rotate with respect to the inner roller 32.

  From the formula (12), the diameters D2 and D3 of the openings 32b and 32c of the inner roller 32 are made smaller than the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 22. Therefore, as shown by the broken lines in FIG. 1 and FIG. 2A, the tripod shaft portion 22 does not detach from the inner peripheral side of the inner roller 32.

  Thus, the inner roller 32 is supported by the tripod shaft portion 22 so as to be able to rotate and swing with respect to the tripod shaft portion 22 and to be slidable in the extending direction of the tripod shaft portion 22. .

(Contact state between tripod shaft 22 and inner roller 32)
Next, the contact state between the tripod shaft 22 and the inner roller 32 when the constant velocity joint 1 rotates will be described. As shown in FIG. 2B, when the constant velocity joint 1 rotates, both end surfaces in the longitudinal direction of the cross-sectional shape of the tripod shaft portion 22 come into contact with the inner peripheral surface 32 a of the inner roller 32. At this time, the contact range between the two becomes an elliptical range long in the circumferential direction of the inner roller 32. Here, from the formulas (7) and (10), the arc-convex radius rb that is both end surfaces in the longitudinal direction of the cross-sectional shape of the tripod shaft portion 22 is smaller than the radius D1 / 2 of the maximum inner diameter D1 of the inner roller 32. Has been. Therefore, the major axis of the elliptical contact range of both is shorter than that of Patent Document 1. Thereby, when the tripod shaft part 22 rocks | fluctuates with respect to the inner roller 32, the friction moment which arises between the tripod shaft part 22 and the inner roller 32 can be reduced. As a result, the induced thrust force can be reduced.

  Furthermore, the first longitudinal cross-sectional shape of the tripod shaft portion 22 is an arc convex shape, and the vertical cross-sectional shape of the inner roller 32 is an arc concave shape, so that the tripod shaft portion 22 and the inner roller 32 Contact surface pressure is reduced. Therefore, the lifetime of both can be improved.

<Second embodiment>
Next, the constant velocity joint 1 of 2nd embodiment is demonstrated with reference to FIG. FIG. 4 is an axial sectional view of the tripod shaft 122 and the inner roller 32. Here, the constant velocity joint 1 in the second embodiment is different from the constant velocity joint 1 in the first embodiment in the tripod shaft portion 122. More specifically, only the radial cross section of the boss portion 21 on the outer peripheral surface 122 a of the tripod shaft portion 122, that is, the first vertical cross-sectional shape of the tripod shaft portion 122 is different. Therefore, only the first vertical cross-sectional shape of the tripod shaft 122 will be described, and the other components will be denoted by the same reference numerals and description thereof will be omitted.

  The first vertical cross-sectional shape of the tripod shaft part 122 is formed in a circular arc shape. The arc-shaped radius ra of the first vertical cross-sectional shape is half of the diameter d1 of the maximum circumscribed circle of the tripod shaft 122. That is, the relationship between the arc convex radius ra of the first vertical cross-sectional shape and the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 22 is the relationship of Expression (15). That is, as shown in FIG. 2A, the arc-convex center point o <b> 3 having the first vertical cross-sectional shape is shifted from the center point o <b> 1 of the tripod shaft part 22 toward the outer peripheral surface 22 a side.

  Even in this case, substantially the same effects as those of the first embodiment can be obtained. However, when the tripod shaft 122 and the inner roller 32 are assembled, the assemblability is inferior compared to the case of the first embodiment.

<Third embodiment>
Next, the constant velocity joint 1 of 3rd embodiment is demonstrated with reference to FIG. FIG. 5 is an axial sectional view of the tripod shaft portion 222 and the inner roller 32. Here, the constant velocity joint 1 in the third embodiment is different from the constant velocity joint 1 in the first embodiment in a tripod shaft portion 222. More specifically, only the radial cross section of the boss portion 21 on the outer peripheral surface 222 a of the tripod shaft portion 222, that is, only the first vertical cross-sectional shape of the tripod shaft portion 222 is different. Therefore, only the first vertical cross-sectional shape of the tripod shaft portion 222 will be described, and the other components will be denoted by the same reference numerals and description thereof will be omitted.

  The first longitudinal cross-sectional shape of the tripod shaft part 222 is formed in an elliptical shape in which the extending direction of the tripod shaft part 222 has a minor axis. Specifically, the elliptical minor axis d4 is smaller than the diameter of the maximum circumscribed circle of the tripod shaft part 222, that is, d1 corresponding to the elliptical major axis. Further, the elliptical minor axis d4 is set larger than the axial width T1 of the inner roller 32. That is, the relationship among the elliptical minor axis d4, the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 222, and the axial width T1 of the inner roller 32 is expressed by Equation (16).

  Even in this case, substantially the same effects as those of the first embodiment can be obtained. And the assembly property at the time of the assembly | attachment of the tripod shaft part 222 and the inner roller 32 is the same as that of 1st embodiment.

<Fourth embodiment>
Next, the constant velocity joint 1 of 4th embodiment is demonstrated with reference to FIG. FIG. 6 is an axial sectional view of the tripod shaft 122 and the inner roller 332. Here, the constant velocity joint 1 in the fourth embodiment is different from the constant velocity joint 1 in the second embodiment in the inner roller 332. More specifically, only the axial section of the inner roller 332 on the inner peripheral surface 332 a of the inner roller 332, that is, the longitudinal sectional shape of the inner roller 332 is different. Therefore, only the longitudinal cross-sectional shape of the inner roller 332 will be described, and the other components will be denoted by the same reference numerals and description thereof will be omitted.

  The longitudinal cross-sectional shape of the inner roller 332 is formed in an elliptical shape having a major axis in the axial direction of the inner roller 332. That is, the elliptical minor axis is the maximum inner diameter D1 of the inner roller 332.

  When it does in this way, there can exist an effect similar to 2nd embodiment substantially. The assembling property when assembling the tripod shaft 122 and the inner roller 332 is also the same as in the second embodiment.

<Fifth embodiment>
Next, the constant velocity joint 1 of 5th embodiment is demonstrated with reference to FIG. FIG. 7 is an axial cross-sectional view of the tripod shaft portion 422 and the inner roller 232. Here, the constant velocity joint 1 in the fifth embodiment is different in the inner roller 432 from the constant velocity joint 1 in the third embodiment. More specifically, only the axial section of the inner roller 432 on the inner peripheral surface 432 a of the inner roller 432, that is, the longitudinal sectional shape of the inner roller 432 is different. Therefore, only the longitudinal sectional shape of the inner roller 432 will be described, and the other components will be denoted by the same reference numerals and description thereof will be omitted.

  The longitudinal cross-sectional shape of the inner roller 432 is formed in an elliptical shape having the major axis in the axial direction of the inner roller 432. That is, the elliptical minor axis is the maximum inner diameter D1 of the inner roller 432. In this case, substantially the same effect as the third embodiment can be obtained. And the assembly property at the time of the assembly | attachment of the tripod shaft part 222 and the inner roller 432 is the same as that of 3rd embodiment.

<Sixth embodiment>
Next, the constant velocity joint 1 of 6th embodiment is demonstrated with reference to FIG. FIG. 8 is a radial sectional view of the tripod shaft 522 and the inner roller 32. Here, the constant velocity joint 1 in the sixth embodiment is different from the constant velocity joint 1 in the first embodiment in the tripod shaft portion 522. More specifically, only the cross section in the extending orthogonal direction on the outer peripheral surface 532a of the tripod shaft portion 522, that is, the cross-sectional shape of the tripod shaft portion 522 is different. More specifically, only the both end surfaces in the longitudinal direction in the cross-sectional shape of the tripod shaft portion 522 are different. Therefore, only the both end faces in the longitudinal direction in the cross-sectional shape of the tripod shaft portion 522 will be described, and the other components will be denoted by the same reference numerals and description thereof will be omitted.

  Both end surfaces in the longitudinal direction in the cross-sectional shape of the tripod shaft part 522 are formed in a circular arc shape. The radius rb of the arcuate convex shape in the cross-sectional shape is set smaller than the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 522. That is, the relationship between the arc-convex radius rb having the cross-sectional shape and the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 22 is expressed by Equation (17).

  By doing in this way, the circumferential direction length of the elliptical range which the inner roller 32 and the tripod shaft part 522 contact can be made shorter. Therefore, the friction moment generated when the constant velocity joint 1 rotates can be further reduced, and as a result, the induced thrust force can be further reduced.

<Seventh embodiment>
Next, the constant velocity joint 1 of 7th embodiment is demonstrated with reference to FIG. FIG. 9 is a radial cross-sectional view of the tripod shaft 622 and the inner roller 32. Here, the constant velocity joint 1 in the seventh embodiment is different from the constant velocity joint 1 in the first embodiment in the tripod shaft portion 622. More specifically, only the cross-section in the extending orthogonal direction on the outer peripheral surface 632a of the tripod shaft portion 622, that is, both end surfaces in the longitudinal direction in the cross-sectional shape of the tripod shaft portion 622 are different. Therefore, only the both end surfaces in the longitudinal direction in the cross-sectional shape of the tripod shaft portion 622 will be described, and the other components will be denoted by the same reference numerals and description thereof will be omitted.

  Both end surfaces in the longitudinal direction in the cross-sectional shape of the tripod shaft portion 622 are formed in an elliptical shape. Specifically, the shaft axial direction side (the axial direction side of the boss portion 21) has an elliptical short diameter, and the torque transmission direction side (the circumferential direction side of the boss portion 21) has an elliptical long diameter. That is, the diameter d1 of the maximum circumscribed circle of the tripod shaft portion 622 becomes the elliptical major axis, and the minor axis w2 of the ellipse is set smaller than the diameter d1 of the maximum circumcircle of the tripod shaft portion 622.

  By doing in this way, the circumferential direction length of the elliptical range which the inner roller 32 and the tripod shaft part 622 contact can be made shorter. Therefore, the friction moment generated when the constant velocity joint 1 rotates can be further reduced, and as a result, the induced thrust force can be further reduced.

<Eighth embodiment>
Next, the constant velocity joint 1 of the eighth embodiment will be described with reference to FIG. FIG. 10 is a radial cross-sectional view of the tripod shaft portion 722 and the inner roller 32. Here, the constant velocity joint 1 in the eighth embodiment is different from the constant velocity joint 1 of the first embodiment in the tripod shaft portion 722. More specifically, the cross section in the extending orthogonal direction on the outer peripheral surface 732a of the tripod shaft portion 722, that is, the cross-sectional shape of the tripod shaft portion 722 is different. Therefore, only the cross-sectional shape of the tripod shaft portion 722 will be described, and the other components will be denoted by the same reference numerals and description thereof will be omitted.

  The cross-sectional shape of the tripod shaft part 722 is formed in a perfect circle. The maximum diameter in the cross-sectional shape of the tripod shaft portion 722 is the diameter d1 of the maximum circumscribed circle.

  Even in this case, substantially the same effects as those of the first embodiment can be obtained. However, when the tripod shaft 722 and the inner roller 32 are assembled, the assemblability is inferior compared to the case of the first embodiment.

It is sectional drawing (diameter direction sectional drawing) which cut | disconnected a part of constant velocity joint 1 in 1st embodiment to radial direction. It is a figure regarding only the tripod shaft part 22 and the inner roller 32 in the first embodiment. It is a figure which shows the state which attaches the inner roller 32 to the tripod shaft part 22. FIG. It is an axial sectional view of the tripod shaft part 122 and the inner roller 32 in the second embodiment. It is an axial sectional view of tripod shaft part 222 and inner roller 32 in a third embodiment. It is an axial direction sectional view of tripod shaft part 122 and inner roller 332 in a fourth embodiment. It is an axial direction sectional view of tripod shaft part 422 and inner roller 232 in a fifth embodiment. It is radial direction sectional drawing of the tripod shaft part 522 and the inner roller 32 in 6th embodiment. It is radial direction sectional drawing of the tripod shaft part 622 and the inner roller 32 in 7th embodiment. It is radial direction sectional drawing of the tripod shaft part 722 and the inner roller 32 in 8th embodiment.

Explanation of symbols

1: Constant velocity joint,
10: outer ring, 11: roller groove,
20: Tripod, 21: Boss part, 21a: Inner circumference spline,
22, 122, 222: tripod shaft, 22a, 122a, 222a: outer peripheral surface,
22b: top surface, 22c: constriction, 22d: bottom surface,
30: roller, 31: outer roller, 31a, 31b: retaining ring groove,
32, 332, 432, 522, 622, 722: inner rollers,
32a, 332a, 432a, 522a, 622a, 722a: inner peripheral surface,
32b: one opening, 32c: the other opening,
33: Needle roller,
34, 35: Retaining ring

Claims (12)

An outer ring having a cylindrical shape and formed with three roller grooves extending in the axial direction on the inner peripheral surface;
A boss portion connected to the shaft, and three tripod shaft portions that are erected so as to extend radially outward of the boss portion from the outer peripheral surface of the boss portion and are inserted into the roller grooves, respectively. Tripod,
It has an annular shape, is rotatable and swingable with respect to the tripod shaft portion, is supported by the tripod shaft portion so as to be slidable in the extending direction of the tripod shaft portion, and is fitted into the roller groove so as to be able to roll. Roller
A sliding tripod type constant velocity joint comprising:
The outer peripheral surface of the tripod shaft part is formed in an arc-convex shape in the radial cross section of the boss part,
The roller is
An outer roller fitted into the roller groove so that its axial center is orthogonal to the extending direction of the roller groove;
Made cylindrical, the so respect tripod shaft portion allows relative movement in the extending direction of the tripod shaft parts, an axial cross-sectional shape of the inner peripheral surface thereof is formed in an arc concave shape, to the outer roller An inner roller that is relatively rotatable, is coaxially disposed radially inward of the outer roller, and is restricted from axial movement relative to the outer roller;
Equipped with a,
The maximum inner diameter D1 of the inner roller is set to be larger than the diameter d1 of the maximum circumscribed circle in the cross-section in the orthogonal direction of the tripod shaft,
The outer peripheral surface and the inner between the circumferential surface, sliding tripod shape constant velocity joint, wherein Rukoto radial gap is formed in said roller of said tripod shaft part. The extension direction position where the maximum circumscribed circle in the extension orthogonal direction cross section of the tripod shaft part is located is defined as an axial reference position,
A diameter reduction amount of a circumscribed circle that reduces the diameter from the shaft reference position toward the tip side with respect to a distance from the shaft reference position to the tip side of the tripod shaft portion is defined as a shaft portion first reduction ratio;
The amount of diameter reduction of a circumscribed circle whose diameter is reduced from the shaft reference position toward the base end with respect to the distance from the shaft reference position to the base end side of the tripod shaft is defined as a shaft portion second reduction ratio. And
An axial position where the maximum inner diameter is located on the inner peripheral surface of the inner roller is defined as a roller reference position,
The diameter of the inner diameter of the inner roller that is reduced from the roller reference position toward the one end side with respect to the distance from the roller reference position to the one end side of the inner roller corresponding to the tip side of the tripod shaft portion is reduced to the first roller reduction. Defined as diameter,
A diameter reduction amount of an inner diameter that is reduced from the roller reference position toward the other end side with respect to a distance from the roller reference position to the other end side of the inner roller corresponding to the base end side of the tripod shaft portion. Defined as the second reduction ratio,
The shaft portion first diameter reduction rate is set larger than the roller first diameter reduction rate,
2. The sliding tripod constant velocity joint according to claim 1, wherein the second shaft diameter reduction ratio is set to be larger than the second roller diameter reduction ratio. The radial cross-sectional shape of the boss portion on the outer peripheral surface of the tripod shaft portion is an arc convex shape,
The axial cross-sectional shape of the inner roller on the inner peripheral surface of the inner roller is an arc concave shape,
The radius ra of the radial cross section of the boss portion on the outer peripheral surface of the tripod shaft portion and the radius Ra of the axial cross section of the inner roller on the inner peripheral surface of the inner roller satisfy the relationship of Equation (1). Item 3. A sliding tripod constant velocity joint according to item 1 or 2.

4. The sliding according to claim 3, wherein a radius Ra of an axial section of the inner roller on the inner peripheral surface of the inner roller and a maximum inner diameter D <b> 1 of the inner peripheral surface of the inner roller satisfy the relationship of Expression (2). Tripod type constant velocity joint.

The sliding according to claim 3, wherein a radius ra of a radial section of the boss portion on the outer peripheral surface of the tripod shaft portion and a maximum inner diameter D1 of the inner peripheral surface of the inner roller satisfy the relationship of Expression (3). Tripod type constant velocity joint.

A radius ra of the radial section of the boss portion on the outer peripheral surface of the tripod shaft portion, a radius Ra of the axial section of the inner roller on the inner peripheral surface of the inner roller, and a maximum inner diameter of the inner peripheral surface of the inner roller The sliding tripod constant velocity joint according to claim 3, wherein D1 satisfies the relationship of Expression (4).

The radial cross-sectional shape of the boss part on the outer peripheral surface of the tripod shaft part is formed in an elliptical shape in which the extending direction of the tripod shaft part has a short diameter,
3. The sliding tripod constant velocity joint according to claim 1, wherein an axial sectional shape of the inner roller on an inner peripheral surface of the inner roller is a circular arc concave shape. 4. The radial cross-sectional shape of the boss portion on the outer peripheral surface of the tripod shaft portion is an arc convex shape,
3. The sliding tripod constant velocity joint according to claim 1, wherein an axial cross-sectional shape of the inner roller on an inner peripheral surface of the inner roller is formed in an elliptical shape having a major axis in the axial direction of the inner roller. . The radial cross-sectional shape of the boss part on the outer peripheral surface of the tripod shaft part is formed in an elliptical shape in which the extending direction of the tripod shaft part has a short diameter,
3. The sliding tripod constant velocity joint according to claim 1, wherein an axial cross-sectional shape of the inner roller on an inner peripheral surface of the inner roller is formed in an elliptical shape having a major axis in the axial direction of the inner roller. .   The sliding tripod constant velocity joint according to any one of claims 1 to 9, wherein a cross-sectional shape in the extending orthogonal direction of the tripod shaft portion on the outer peripheral surface of the tripod shaft portion is formed in a perfect circle.   The cross-sectional shape in the extending orthogonal direction of the tripod shaft portion on the outer peripheral surface of the tripod shaft portion is formed in an elliptical shape in which the axial direction side of the boss portion has a short diameter and the circumferential direction side of the boss portion has a long diameter. The sliding tripod constant velocity joint according to any one of claims 9 to 10. The stretched orthogonal cross-sectional shape of the tripod shaft portion on the outer peripheral surface of the tripod shaft portion is such that the axial direction side of the boss portion is a short direction and the circumferential side of the boss portion is a longitudinal direction,
The stretched orthogonal cross-sectional shape of the tripod shaft portion on both end faces in the longitudinal direction is a circular arc convex shape,
The radius rb of the stretched orthogonal direction cross section of the tripod shaft part at both end surfaces in the longitudinal direction and the diameter d1 of the maximum circumscribed circle in the stretched orthogonal direction cross section of the tripod shaft part satisfy the relationship of Expression (5). The sliding tripod type constant velocity joint as described in any one of 1-9.

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