Tripod-type constant velocity joint

Abstract

A tripod-type constant velocity joint (101) comprises a roller unit (20) and an outer joint member (30). An outer roller (21) of the roller unit (20) has a cylindrical section (22) and two reduced-diameter sections (24, 25) that are provided to both sides of the cylindrical section in a cylinder axis direction (Y1). A roller groove (31) of the outer joint member (30) has a roller rolling surface (32) that is a flat surface in contact with an outer circumferential surface (22a) of the cylindrical section (22) of the outer roller (21), and two facing surfaces (33, 34) that respectively face the two reduced-diameter sections (24, 25) of the outer roller (21). One of the two facing surfaces (33, 34) is a contact surface (34) that is in contact with the reduced-diameter section (25). The cross-sectional shape, in the cylinder axis direction (Y1), of the reduced-diameter section (25) of the outer roller 21 forms a convex line, and the cross-sectional shape, in the cylinder axis direction (Y1), of the contact surface (34) of the outer joint member (30) forms a slanted straight line.

Description

Tripod type constant velocity joint

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

[0002] The following Patent Document 1 discloses a tripod type constant velocity universal joint. This tripod type constant velocity universal joint includes an outer joint member, a tripod member as an inner joint member, and a cylindrical roller unit as a torque transmission member. The roller unit is provided on the outer periphery of each of three leg shafts of the tripod member, and is accommodated in each of 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 circumferential surface of an annular outer ring that constitutes the roller unit.

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

[0004] In the roller unit described in Patent Document 1, in order to suppress movement of the outer ring in the leg shaft direction, inclined surfaces are provided on both sides of the outer circumferential surface of the outer ring, and inclined surfaces are provided on the roller guide surfaces of the outer joint member so as to wrap around the inclined surfaces on the outer ring side. However, variations may occur in the angle of the inclined surfaces during the manufacturing process of the outer joint member. In such a case, the contact position of the inclined surface on the outer ring side with respect to the inclined surface on the outer joint member side changes, which may cause a problem that the performance is unstable due to variations in sliding resistance during torque transmission between the outer ring and the outer joint member.

[0005] The present disclosure aims to provide a technique effective for stabilizing the performance of 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, the outer roller having a cylindrical portion and two reduced-diameter portions provided on both sides of the cylindrical portion in the roller axial direction, the roller groove of the outer joint member having a roller transfer surface which is a flat surface that abuts the outer circumferential surface of the cylindrical portion of the outer roller, and two opposing surfaces which each face the two reduced-diameter portions of the outer roller, at least one of the two opposing surfaces being a contact surface that abuts the reduced-diameter portion. The tripod-type constant velocity joint is such that either the reduced diameter portion of the outer roller or the contact surface of the outer joint member has a convex cross-sectional shape in the direction of the roller axis, and the other of the reduced diameter portion of the outer roller or the contact surface of the outer joint member has an inclined straight cross-sectional shape in the direction of the roller axis.

[0007] The tripod-type constant velocity joint described above is characterized in that the cross-sectional shape in the roller axis direction of either the reduced diameter portion of the outer roller of the roller unit or the contact surface of the roller groove of the outer joint member is a convex line, and the cross-sectional shape in the roller axis direction of the other is an inclined straight line. The contact surface of the roller groove is the surface that contacts the reduced diameter portion of the outer roller.

[0008] The tripod-type constant velocity joint with the above configuration is characterized by a structure in which the reduced diameter portion of the outer roller and the contact surface of the outer joint member are geometrically in contact with each other via a convex line and an inclined straight line. As a result, even if variations occur in the inclination angle of the contact surface during the manufacturing process, the contact position of the reduced diameter portion with respect to the contact surface is less likely to change. Consequently, it is possible to suppress variations in sliding resistance during torque transmission between the outer roller and the outer joint member and stabilize performance.

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

[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 and other purposes, 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 reduced-diameter portion of the outer roller in Figure 3. Figure 7 is a cross-sectional view of one reduced-diameter portion of the outer roller according to a modified 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] In addition, in the outer roller 21 of this embodiment, the crowning portion 23 on the outer circumferential surface 22a of the cylindrical portion 22 may be omitted as needed, and the cross-sectional shape of the outer circumferential surface 22a of the cylindrical portion 22 in the roller axis direction Y1 may be changed to be straight.

[0035] 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.

[0036] 6. Effects Next, the effects of Embodiment 1 described above will be explained.

[0037] The constant velocity joint 101 of the above-described embodiment 1 is characterized in that the cross-sectional shape of the reduced diameter portion 25 of the outer roller 21 of the roller unit 20 in the direction of the roller axis Y1 is a convex line, and the cross-sectional shape of the contact surface 34 of the roller groove 31 of the outer joint member 30 in the direction of the roller axis Y1 is an inclined straight line. The contact surface 34 of the roller groove 31 is the surface that contacts the reduced diameter portion 25 of the outer roller 21.

[0038] In the constant velocity joint 101 with the above configuration, 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 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. As a result, 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.

[0039] Therefore, according to Embodiment 1, it becomes possible to stabilize the performance of the constant velocity joint 101.

[0040] 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.

[0041] (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 6). The structure of the other elements is the same as that of Embodiment 1.

[0042] 7. Detailed Structure of the Reduced Diameter Portion 25 of the Outer Roller 21A As shown in Figure 7, the reduced diameter portion 25 of the outer roller 21A has a convex cross-sectional shape in the roller axis direction Y1, similar to the outer roller 21 of Embodiment 1. On the other hand, the convex cross-sectional shape of this reduced diameter portion 25 is composed of a first circular arc B2, which is the cross-sectional shape of the first region 25a, and a second circular arc B3, which is the cross-sectional shape of the second region 25b. The first circular arc B2 is the arc of a circle with a radius of a first radius of curvature R2. The second circular arc B3 extends from one end of the first circular arc B2 toward the cylindrical portion 22, and is the arc of a circle with a radius of a second radius of curvature R3, which is larger than the first radius of curvature R2. By making the cross-sectional shape of the second region 25b the second circular arc B3, 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 roller groove 31 of the outer joint member 30 only in the first region 25a, and not in the second region 25b.

[0043] According to the outer roller 21A of Embodiment 2, similar to the outer roller 21 of Embodiment 1, the reduced diameter portion 25 of the outer roller 21A and the contact surface 34 of the outer joint member 30 can be made to contact geometrically with a convex line and an inclined straight line.

[0044] 8. Modified Embodiments The present disclosure has been described based on the above-described embodiments, but it should be understood that the present disclosure is not limited to the said embodiments or structures. The present disclosure also encompasses various modifications and variations within the equivalent scope. In addition, various combinations and forms, as well as other combinations and forms that include only one element, more than one element, or less than one element thereof, also fall within the scope and spirit of the present disclosure.

[0045] In the above-described embodiment, an example is illustrated where the cross-sectional shape of the reduced diameter portion 25 of the outer roller 21 is a convex line, and the cross-sectional shape of the contact surface 34 of the outer joint member 30 is an inclined straight line. However, alternatively, the cross-sectional shape of the reduced diameter portion 25 of the outer roller 21 may be an inclined straight line, and the cross-sectional shape of the contact surface 34 of the outer joint member 30 may be a convex line.

[0046] In the above-described embodiment, an example is illustrated where the convex line of the cross-sectional shape of the reduced diameter portion 25 of the outer roller 21 includes one circular arc B2 or two circular arcs B2 and B3. However, the number of circular arcs can be appropriately changed as needed. In addition, the curved line is not limited to a circular arc, and may be formed by, for example, a part of an ellipse or another quadratic curve.

[0047] In the above-described embodiment, the constant velocity joint 101 used for a power transmission shaft of a vehicle is illustrated as an example. However, the constant velocity joint 101 may also be applied to a steering shaft (steering system) 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) that houses the inner joint member and has 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, wherein the outer roller has a cylindrical portion (22) and two reduced diameter portions (24, 25) provided on both sides of the cylindrical portion in the roller axial direction (Y1), The roller groove of the outer joint member has a roller transfer surface (32) which is a flat surface that abuts against the outer peripheral surface (22a) of the cylindrical portion of the outer roller, and two opposing surfaces (33, 34) which each face the two reduced diameter portions of the outer roller, and at least one of the two opposing surfaces is a contact surface (34) that abuts against the reduced diameter portion, and either the reduced diameter portion of the outer roller or the contact surface of the outer joint member has a convex cross-sectional shape in the direction of the roller axis, and the other of the reduced diameter portion of the outer roller or the contact surface of the outer joint member has a sloping straight cross-sectional shape in the direction of the roller axis, in a tripod-type constant velocity joint (101).

2. The tripod-type constant velocity joint according to claim 1, wherein the reduced diameter portion of the outer roller has a convex cross-sectional shape in the direction of the roller axis, and the contact surface of the outer joint member has an inclined straight cross-sectional shape in the direction of the roller axis.

3. The tripod-type constant velocity joint according to claim 2, wherein the convex line has a shape that includes one or more curved lines (B2, B3).

4. The tripod-type constant velocity joint according to claim 3, wherein the convex line has a shape consisting of the curved line and an inclined straight line (C) extending from one end of the curved line toward the cylindrical portion.

5. The tripod-type constant velocity joint according to claim 3, wherein the curved line comprises a first circular arc (B2) having a radius of a first radius of curvature (R2), and a second circular arc (B3) extending from one end of the first circular arc toward the cylindrical portion and having a radius of a second radius of curvature (R3) that is larger than the first radius of curvature.

6. The tripod-type constant velocity joint according to any one of claims 1 to 5, wherein the two opposing surfaces of the outer joint member include non-contact surfaces (33) that do not contact the reduced diameter portion, and the cross-sectional shape of the non-contact surface in the direction of the roller axis is an inclined straight line.

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