Tripod-type constant velocity joint

Abstract

A tripod-type constant velocity joint (101) comprises a roller unit (20) and an outer joint member (30). A crowning part (23) is provided on the outer peripheral surface (22a) of a cylindrical part (22) of an outer roller (21) of the roller unit (20), the crowning part (23) being such that the cross-sectional shape thereof in a roller axial direction (Y1) is a crowning shape, and the crowning part (23) being elastically deformed when torque is transmitted. The crowning shape of the crowning part (23) is such that the protrusion height in a roller radial direction (X1) perpendicular to the roller axial direction (Y1) gradually decreases from a central part (23a) in the roller axial direction (Y1) toward edge parts (23b, 23c) positioned at boundaries between the central part (23) and reduced-diameter parts (24, 25) provided on both sides of the central part (23) in the roller axial direction (Y1).

Description

Tripod-type constant velocity joint

[0001] The present disclosure relates to a tripod-type constant velocity joint.

[0002] Patent Document 1 below discloses a tripod-type constant velocity universal joint. This tripod-type constant velocity universal joint includes an outer joint member, a tripod member serving as an inner joint member, and a cylindrical roller unit serving as a torque transmission member. The roller unit is provided on the outer periphery of each of the three leg shafts of the tripod member, and is accommodated in each of the three track grooves of the outer joint member. Each track groove of the outer joint member has a pair of roller guide surfaces parallel to each other, and the pair of roller guide surfaces are in contact with the outer peripheral surface of an annular outer ring that constitutes the roller unit.

[0003] Japanese Unexamined Patent Publication No. 2024-86274

[0004] In the roller unit described in Patent Document 1, since the outer peripheral surface of the outer ring is a flat surface, stress tends to concentrate on the edge between the flat surface and the chamfers on both sides thereof during torque transmission, which raises a concern about a decrease in the durability of the outer joint member. If the dimensions of the outer joint member are determined so as to prevent a decrease in durability, the outer joint member becomes large, which may hinder the downsizing of the tripod-type constant velocity universal joint.

[0005] The present disclosure aims to provide a technology effective for downsizing a tripod-type constant velocity joint.

[0006] One aspect of the present disclosure comprises an inner joint member having three legs, three roller units each rotatably attached to each of the three legs of the inner joint member, and an outer joint member having three roller grooves that house the inner joint member and house each of the three roller units so that they are movable in the axial direction and in the circumferential direction of the inner joint member, wherein each roller unit has a cylindrical outer roller, a cylindrical inner roller housed in the outer roller, and a plurality of rolling elements interposed between the outer roller and the inner roller, and either the outer circumferential surface of the cylindrical portion of the outer roller or the roller transfer surface of the roller groove is provided with a crowning portion whose cross-sectional shape in the roller axial direction is crowning and which elastically deforms when torque is transmitted. The crowning shape of the crowning portion is such that the height of the convexity in the roller radial direction perpendicular to the roller axis gradually decreases from the central portion in the roller axial direction toward the edge portion located at the boundary between the central portion and the reduced diameter portions provided on both sides of the central portion in the roller axial direction. This is a tripod-type constant velocity joint.

[0007] The tripod-type constant velocity joint according to the above embodiment is characterized in that either the outer circumferential surface of the cylindrical portion of the outer roller of the roller unit or the roller transfer surface of the roller groove of the outer joint member is provided with a crowning portion. The crowning portion has a crowning shape in the cross-sectional shape in the direction of the roller axis and is configured to elastically deform when torque is transmitted. The crowning shape is such that the height of the convexity gradually decreases from the center in the direction of the roller axis toward the edges on both sides.

[0008] With the tripod-type constant velocity joint configured as described above, by providing a crowning section, the shape change toward the edge can be made gentler compared to when the section is made flat, thereby suppressing stress concentration at the edge. As a result, when determining the dimensions of the outer joint member based on the stress at the edge, it becomes possible to keep the dimensions of the outer joint member small.

[0009] According to the above-described embodiment, it is possible to provide a technology that is effective in miniaturizing tripod-type constant velocity joints.

[0010] The symbols in parentheses in the claims indicate the correspondence with the specific means described in the embodiments described later, and do not limit the technical scope of this disclosure.

[0011] The above-mentioned objectives and other objectives, features and advantages of this disclosure will become clearer through the following detailed description, which will be explained with reference to the accompanying drawings. Figure 1 is an axial cross-sectional view of a constant velocity joint assembly according to Embodiment 1. Figure 2 is a cross-sectional view of the tripod-type constant velocity joint of Embodiment 1, viewed from the opening side of the outer joint member. Figure 3 is an enlarged cross-sectional view showing the peripheral portion of the outer roller of the roller unit of the outer joint member in Figure 2. Figure 4 is a schematic cross-sectional view of the cylindrical portion of the outer roller in Figure 3. Figure 5 is a graph showing the analysis results of the correlation between the cross-sectional position and surface pressure of the cylindrical portion of the outer roller in Figure 4. Figure 6 is a cross-sectional view of one of the reduced diameter portions of the outer roller in Figure 3. Figure 7 is a schematic cross-sectional view of the cylindrical portion of the outer roller according to the first modification example. Figure 8 is a schematic cross-sectional view of the cylindrical portion of the outer roller according to the second modification example.

[0012] Below, a tripod-type constant velocity joint, which is one embodiment of the above-described aspect, will be explained with reference to the drawings.

[0013] In this specification and drawings, unless otherwise specified, the axial direction of the outer joint member is indicated by arrow X, the leg axis direction of the leg portion of the inner joint member is indicated by arrow Y, and the circumferential direction of the inner joint member is indicated by arrow Z. Furthermore, the roller radial direction of the roller unit is indicated by arrow X1, and the roller axis direction of the roller unit is indicated by arrow Y1.

[0014] (Embodiment 1) 1. Overall Structure of the Tripod-Type Constant Velocity Joint 101 The tripod-type constant velocity joint 101 of Embodiment 1, as shown in Figure 1, is used, for example, in the power transmission shaft of a vehicle. The tripod-type constant velocity joint 101, together with the shaft 102 and the boot 103, forms a constant velocity joint assembly 1. This constant velocity joint assembly 1 is used at the connection points of the differential and the wheels (neither of which are shown).

[0015] As shown in Figure 1, the tripod-type constant velocity joint (hereinafter simply referred to as "constant velocity joint") 101 comprises an inner joint member 10, three roller units 20 (see Figure 2), and an outer joint member 30.

[0016] The inner joint member 10 is also called a "tripod." This inner joint member 10 has a boss 11 with a central hole 11a, and three leg portions 12 extending in the leg axis direction Y from three equally spaced positions in the circumferential direction of the outer surface of the boss 11. The leg axis direction Y is perpendicular to the rotation axis direction of the inner joint member 10. The boss 11 is fixed to the shaft 102 with a female spline formed on the inner surface of the central hole 11a fitted into a male spline formed on the outer surface of the shaft 102. This connects the inner joint member 10 and the shaft 102 in a torque-transmitting manner. The outer surface of each leg portion 12 is formed in a spherical convex shape. That is, the cross-sectional shape of the outer surface of the leg portion 12 in the leg axis direction Y is formed in an arc convex shape.

[0017] The roller unit 20 is formed in an annular shape. This roller unit 20 is housed in the roller groove 31 of the outer joint member 30 while attached to the outer circumference of each leg portion 12 of the inner joint member 10. This roller unit 20 is rotatable about the roller axis A (see Figure 2), slidable in the roller axial direction Y1 (see Figure 2) extending along the roller axis A, and is supported by the inner joint member 10 so as to be tiltable relative to the leg portions 12. Furthermore, this roller unit 20 is arranged to roll in the axial direction X along the roller groove 31 provided in the outer joint member 30.

[0018] The outer joint member 30 is also called the "outer race." This outer joint member 30 is formed by forging. This outer joint member 30 is formed in a closed-bottom cylindrical shape with an opening 30a at one end in its axial direction X (left-right direction in Figure 1). Alternatively, this outer joint member 30 may be formed in a cylindrical shape that penetrates in the axial direction. The outer joint member 30 houses the inner joint member 10 inside the cylinder. Furthermore, on the inner circumferential surface of the outer joint member 30, three roller grooves 31 are formed at equal intervals in the circumferential direction, extending linearly in the axial direction from the opening 30a side toward the back side (left side in Figure 1). Each of the three roller grooves 31 houses each of the three roller units 20 so that they can move in the axial direction X of the outer joint member 30 and in the circumferential direction Z of the inner joint member 10 (see Figure 2).

[0019] With an angle applied to the shaft 102 and the outer joint member 30, torque is transmitted between the shaft 102 and the outer joint member 30 via the inner joint member 10 and the roller unit 20. At this time, the angle formed by the shaft 102 and the outer joint member 30 is referred to as the "joint angle" of the constant velocity joint 101.

[0020] The boot 103 is formed in a bellows-like shape. This boot 103 is attached to the outer circumferential surface of the outer joint member 30 so as to close the opening 30a of the outer joint member 30. This boot 103 has a sealing function that prevents the grease contained inside the outer joint member 30 from leaking out through the opening 30a of the outer joint member 30.

[0021] 2. Structure of the roller unit 20 As shown in Figure 2, the roller unit 20 includes a cylindrical outer roller 21, a cylindrical inner roller 27 housed in the outer roller 21, a plurality of rolling elements 28 interposed between the outer roller 21 and the inner roller 27, and an annular retaining ring 29 that engages with the inner circumferential surface of the outer roller 21. This roller unit 20 has a structure in which two rollers (outer roller 21 and inner roller 27) are arranged radially on top of each other, and is generally referred to as a "double roller type". Both the outer roller 21 and the inner roller 27 are formed by grinding and polishing.

[0022] The inner roller 27 is configured such that its inner circumferential surface contacts the outer circumferential surface of the leg portion 12 of the inner joint member 10. The rolling element 28 is a cylindrical member called a "needle". The retaining ring 29 is a retaining member that prevents the inner roller 27 and rolling element 28 from coming off the outer roller 21 in the axial direction. This retaining ring 29 is also called a "snap ring". In Figure 2, an example is shown where the retaining ring 29 is provided on only one side of the inner roller 27 and rolling element 28 in the axial direction, but instead, the retaining ring 29 may be provided on both sides of the inner roller 27 and rolling element 28 in the axial direction.

[0023] 3. Contact structure of the outer roller 21 and the outer joint member 30 As shown in Figure 3, the outer roller 21 has a cylindrical portion 22 and two reduced-diameter portions 24 and 25 provided on both sides of the cylindrical portion 22 in the roller axis direction Y1. The reduced-diameter portion 24 is formed on the tip side (upper side in Figure 3) of the leg portion 12 of the inner joint member 10. In this embodiment, the reduced-diameter portion 24 has a flat cross-sectional shape in the roller axis direction Y1. The reduced-diameter portion 25 is formed on the root side (lower side in Figure 3) of the leg portion 12 of the inner joint member 10.

[0024] In contrast, the roller groove 31 of the outer joint member 30 has a roller transfer surface 32 which is a flat surface that abuts against the outer peripheral surface 22a of the cylindrical portion 22 of the outer roller 21, two opposing surfaces 33 and 34 which face each of the two reduced diameter portions 24 and 25 of the outer roller 21, and an opposing surface 35 which faces the end surface 26 on the reduced diameter portion 24 side of the outer roller 21. In this embodiment, both of the two opposing surfaces 33 and 34 have a cross-sectional shape in the roller axis direction Y1 which is an inclined straight line with respect to the roller axis direction Y1.

[0025] In the roller groove 31 of the outer joint member 30, the opposing surface 33 is configured to be a non-contact surface that does not contact the reduced diameter portion 24 of the outer roller 21. In contrast, the opposing surface 34 is configured to be a contact surface that contacts the reduced diameter portion 25 of the outer roller 21. That is, the opposing surface 34 is also a contact surface 34 for the reduced diameter portion 25. The opposing surface 35 is configured to be a contact surface that contacts the end face 26 of the outer roller 21, instead of the opposing surface 33 being a non-contact surface for the reduced diameter portion 24. This configuration is effective in ensuring the wall thickness of the outer joint member 30. The outer roller 21 is configured to contact the outer joint member 30 at the outer peripheral surface 22a of the cylindrical portion 22, the reduced diameter portion 25, and the end face 26. Alternatively, the structure of the outer roller 21 may be changed so that it contacts the outer joint member 30 at the reduced diameter portion 24 instead of the end face 26.

[0026] The roller unit 20 is configured such that when the outer joint member 30 rotates in the circumferential direction, the outer peripheral surface 22a of the cylindrical portion 22 of the outer roller 21 contacts one of the two roller transfer surfaces 32 (see Figure 2) of the roller groove 31, depending on the direction of rotation, thereby transmitting torque between the roller unit 20 and the outer joint member 30. In other words, when the rotation direction of the outer joint member 30 is switched, the surface of the two roller transfer surfaces 32 that contacts the outer peripheral surface 22a of the cylindrical portion 22 of the outer roller 21 is switched.

[0027] 4. Detailed Structure of the Cylindrical Part 22 of the Outer Roller 21 As shown in Figures 3 and 4, a crowning portion 23 is provided on the outer circumferential surface 22a of the cylindrical part 22 of the outer roller 21. The crowning portion 23 has a crowning shape in which the cross-sectional shape in the roller axis direction Y1 is convex, and is a part that elastically deforms so as to collapse when torque is transmitted. The crowning shape of the crowning portion 23 has a length L [mm] in the roller axis direction Y1, and the convex height in the roller radial direction X1 perpendicular to the roller axis direction Y1 (see "Convex Height CR [mm]" in Figure 4) gradually decreases from the central part 23a toward the edge parts 23b and 23c in the roller axis direction Y1. The edge parts 23b and 23c are located at the boundary between the central part 23a and the reduced diameter parts 24 and 25 on both sides of the central part 23a in the roller axis direction Y1. As shown in Figure 4, in this embodiment, the crowning shape of the crowning portion 23 is a shape consisting of a circular arc B1 with radius R1. The circular arc B1 is a form of a curved line.

[0028] In this embodiment, the height of the crowning portion 23 in the roller radial direction X1 is minute with respect to the length in the roller axial direction Y1. In this case, although the outer circumferential surface 22a of the outer roller 21 has the crowning portion 23, it becomes a surface that extends generally in a straight line along the roller axial direction Y1. Therefore, similar to the case where the outer circumferential surface 22a of the outer roller 21 is a flat surface, the movement of the outer roller 21 during torque transmission is mainly restricted to the roller axial direction Y1. This provides the effect of suppressing the occurrence of rolling phenomena in the roller unit 20.

[0029] Here, referring to the analysis results in Figure 5, the surface pressure received by the outer circumferential surface 22a of the cylindrical portion 22 of the outer roller 21 from the outer joint member 30 during torque transmission will be explained. In Figure 5, the horizontal axis of the graph represents the cross-sectional position [mm] in the roller axis direction Y1, and the horizontal axis of the graph represents the surface pressure [Pa] of the outer roller 21. The "Example" in which the crowning portion 23 of this embodiment uses the outer roller 21 is shown with a solid line, and the "Comparative Example" in which the crowning shape of the crowning portion 23 is changed to a flat shape is shown with a dashed line.

[0030] According to the analysis results in Figure 5, it was confirmed that by providing a crowning portion 23 on the outer circumferential surface 22a of the cylindrical portion 22 of the outer roller 21, it is possible to reduce the surface pressure of the two edge portions 23b and 23c of the outer roller 21 from surface pressure Sb [Pa] to surface pressure Sa [Pa] compared to the case where the crowning shape is flat. Therefore, by providing a crowning portion 23 on the outer circumferential surface 22a of the outer roller 21, it is possible to suppress stress concentration at the edges 23b and 23c. In addition, since the surface pressure at the edges 23b and 23c is the greatest on the outer circumferential surface 22a of the outer roller 21, it is possible to reduce the maximum value of the surface pressure on the outer circumferential surface 22a of the outer roller 21 by reducing the surface pressure at the edges 23b and 23c.

[0031] When the crowning shape of the crowning portion 23 is composed of a single arc B1, the surface pressure in the central portion 23a is affected by the convex height CR, and as the convex height CR increases, the surface pressure increases. Therefore, in order to suppress the increase in surface pressure in the central portion 23a, it is preferable to adopt a crowning shape for the crowning portion 23 such that the relationship between the length L [mm] of the roller axis direction Y1 and the convex height CR [mm] in the roller radial direction X1 perpendicular to the roller axis direction Y1 satisfies the following equation (1).

[0032] 90 ≤ L / CR ≤ 360 ... (1)

[0033] (1) By adopting a crowning shape that satisfies equation (1), it becomes possible to keep the maximum surface pressure on the outer peripheral surface 22a of the outer roller 21 low, and also to reduce the surface pressure on the central part 23a of the crowning part 23.

[0034] 5. Detailed Structure of the Reduced Diameter Portion 25 of the Outer Roller 21 As shown in Figure 6, the reduced diameter portion 25 of the outer roller 21 has a convex cross-sectional shape in the roller axis direction Y1. That is, the convex cross-sectional shape of this reduced diameter portion 25 is composed of an arc B2, which is the cross-sectional shape of the first region 25a, and an inclined straight line C, which is the cross-sectional shape of the second region 25b. The arc B2 is the arc of a circle with a radius of curvature R2. The inclined straight line C is a straight line extending from one end of the arc B2 toward the cylindrical portion 22, and is a straight line that forms an inclination angle θ with the outer circumferential surface 22a of the cylindrical portion 22 of the outer roller 21. By making the cross-sectional shape of the second region 25b an inclined straight line C, a gap can be formed between it and the contact surface 34 of the outer joint member 30. As a result, the reduced diameter portion 25 is configured to contact the contact surface 34 of the outer joint member 30 only in the first region 25a, and not in the second region 25b.

[0035] In this embodiment, the cross-sectional shape of the reduced-diameter portion 25 on the outer roller 21 side is a convex line, and the cross-sectional shape of the contact surface 34 on the outer joint member 30 side is an inclined straight line, so that the reduced-diameter portion 25 and the contact surface 34 are geometrically in contact with each other via a convex line and an inclined straight line. As a result, even if there is variation in the inclination angle of the contact surface 34 during the manufacturing process of the outer joint member 30, the contact position of the reduced-diameter portion 25 with respect to the contact surface 34 is less likely to change. Consequently, it is possible to suppress variations in sliding resistance during torque transmission between the outer roller 21 and the outer joint member 30 and stabilize performance.

[0036] In addition, in the outer roller 21 of this embodiment, the cross-sectional shape of the reduced diameter portion 25 in the roller axis direction Y1 may be changed from a convex line to an inclined straight line as needed.

[0037] 6. Effects Next, the effects of Embodiment 1 described above will be explained.

[0038] The constant velocity joint 101 of the above-described embodiment 1 is characterized in that the outer peripheral surface 22a of the cylindrical portion 22 of the outer roller 21 of the roller unit 20 is provided with a crowning portion 23. The crowning portion 23 has a crowning shape in the cross-sectional shape in the roller axis direction Y1 and is configured to elastically deform when torque is transmitted. The crowning shape is such that the convex height CR gradually decreases from the central portion 23a in the roller axis direction Y1 toward the edge portions 23b and 23c on both sides.

[0039] By providing the crowning portion 23 with the above configuration, the shape change toward the edge portions 23b and 23c can be made gentler compared to the case where the portion is flat, thereby suppressing stress concentration at the edge portions 23b and 23c. As a result, when determining the dimensions of the outer joint member 30 based on the stress at the edge portions 23b and 23c, it becomes possible to keep the dimensions of the outer joint member 30 small.

[0040] Therefore, according to Embodiment 1, it becomes possible to miniaturize the constant velocity joint 101.

[0041] Furthermore, in the constant velocity joint 101 of Embodiment 1, the crowning portion 23 is provided on the outer roller 21 which is formed by grinding and polishing. Therefore, compared to the case where the crowning portion 23 is provided on the outer joint member 30 which is formed by forging, this is effective in ensuring the machining accuracy of the crowning portion 23.

[0042] The following describes other embodiments related to Embodiment 1 described above, with reference to the drawings. In the other embodiments, elements identical to those in Embodiment 1 are denoted by the same reference numerals, and the description of such identical elements is omitted.

[0043] (Embodiment 2) In Embodiment 2, the structure of the outer roller 21A shown in Figure 7 differs from that of the outer roller 21 in Embodiment 1 (see Figure 4). The structure of the other elements is the same as that of Embodiment 1.

[0044] 7. Structure of outer roller 21A As shown in FIG. 7, the crowning shape of the crowning portion 23 of the outer roller 21A is a shape consisting of two arcs B1, B3 and one straight line D. The arc B1 is an arc of a circle having a radius of curvature R1. The arc B3 is an arc of a circle having a radius of curvature R3. Both of the two arcs B1 and B3 are a form of curved line. The straight line D is a connecting straight line that connects between the two arcs B1 and B3, and extends in the roller axial direction Y1 at the central portion 23a of the crowning portion 23. Note that the radius of curvature R1 of the arc B1 and the radius of curvature R3 of the arc B3 may be the same value or may be different values.

[0045] According to the outer roller 21A of the second embodiment, similarly to the outer roller 21 of the first embodiment, the crowning shape of the crowning portion 23 can be a shape in which the convex height in the roller radial direction X1 substantially gradually decreases as going from the central portion 23a toward the edge portions 23b and 23c.

[0046] (Third Embodiment) In the third embodiment, the structure of an outer roller 21B shown in FIG. 8 is different from that of the outer roller 21A of the second embodiment (see FIG. 7). The structure of other elements is the same as that of the second embodiment.

[0047] 8. Structure of outer roller 21B As shown in FIG. 8, the crowning shape of the crowning portion 23 of the outer roller 21B is a shape consisting of two arcs B1 and B3. That is, in the outer roller 21A of the second embodiment, the straight line D (see FIG. 7) connecting between the two arcs B1 and B3 is omitted, and the two arcs B1 and B3 are directly connected at the connection point P of the central portion 23a.

[0048] According to the outer roller 21B of the third embodiment, similarly to the outer roller 21 of the first embodiment, the crowning shape of the crowning portion 23 can be a shape in which the convex height in the roller radial direction X1 substantially gradually decreases as going from the central portion 23a toward the edge portions 23b and 23c.

[0049] 9. Modified Forms Although this disclosure is described in accordance with the forms described above, it is understood that this disclosure is not limited to such forms or structures. This disclosure also includes various modifications and variations within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or less of those elements, fall within the scope and idea of ​​this disclosure.

[0050] In the above-described embodiment, an example was given in which a crowning portion 23 is provided on the outer peripheral surface 22a of the cylindrical portion 22 of the outer roller 21. However, instead, the outer peripheral surface 22a of the cylindrical portion 22 may be made a flat surface, and a portion corresponding to the crowning portion 23 may be provided on the roller transfer surface 32 of the roller groove 31 of the outer joint member 30.

[0051] In the above-described embodiment, the example shows the case where the curved line of the crowning shape of the crowning portion 23 is formed by one circular arc B1 or two circular arcs B1 and B3, but the number of circular arcs can be changed as needed. Furthermore, the curved line is not limited to circular arcs, and may be formed by, for example, part of an ellipse or other quadratic curves. In addition, the crowning shape may be formed by multiple straight lines with different angles of inclination.

[0052] In the above-described embodiment, a constant velocity joint 101 used in the power transmission shaft of a vehicle was given as an example, but this constant velocity joint 101 may also be applied to the steering shaft of a vehicle.

Claims

1. An inner joint member (10) having three legs (12), three roller units (20) each rotatably attached to each of the three legs of the inner joint member, and an outer joint member (30) housing the inner joint member and having three roller grooves (31) that house each of the three roller units so that they are movable in the axial direction (X) and in the circumferential direction (Z) of the inner joint member, wherein each roller unit has a cylindrical outer roller (21), a cylindrical inner roller (27) housed in the outer roller, and a plurality of rolling elements (28) interposed between the outer roller and the inner roller, and either the outer circumferential surface (22a) of the cylindrical portion (22) of the outer roller or the roller transfer surface (32) of the roller groove is provided with a crowning portion (23) whose cross-sectional shape in the roller axial direction (Y1) is crowning and which elastically deforms when torque is transmitted. A tripod-type constant velocity joint, wherein the crowning shape of the crowning portion has a shape in which the convex height (CR) in the roller radial direction (X1) perpendicular to the roller axis gradually decreases from the central portion (23a) in the roller axial direction toward the edge portions (23b, 23c) located at the boundary between the central portion and the reduced diameter portions (24, 25) provided on both sides of the central portion in the roller axial direction.

2. The tripod-type constant velocity joint according to claim 1, wherein the crowning shape includes one or more curved lines (B1, B3).

3. The tripod-type constant velocity joint according to claim 2, wherein the crowning shape includes a straight line (D) and curved lines extending from both sides of the straight line.

4. The tripod-type constant velocity joint according to claim 2 or 3, wherein the curved line consists of one or more circular arcs (B1, B3) with radii of curvature (R1, R3).

5. The crowning shape is such that the length (L) in the roller axis direction and the height of the protrusion satisfy the following equation (1), the tripod-type constant velocity joint according to claim 4. 90 ≤ L / CR ≤ 360 ... (1) 6. The tripod-type constant velocity joint according to claim 5, wherein the crowning portion is provided on the outer circumferential surface of the cylindrical portion of the outer roller.

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