CN118669447A - Tripod constant velocity universal joint - Google Patents

Abstract

The invention provides a tripod constant velocity universal joint with improved durability and strength of tripod members. A hardened layer (17) is formed in the surface of the foot shaft (8) of the tripod member (5) in a region including a flange portion (15) provided on the shaft end side of the annular groove (11). The depth (K) of the annular groove (11) is equal to or less than the axial dimension (L) of the outer peripheral surface of the flange (15). The axial dimension (L) of the outer peripheral surface of the flange (15) is 0.8mm or more.

Description

Tripod constant velocity universal joint

Technical Field

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

Background

The constant velocity universal joint has the following configuration: the constant-velocity universal joint is roughly classified into a fixed type that allows only angular displacement of the two shafts and a sliding type that allows angular displacement and axial displacement of the two shafts, in which the two shafts are coupled to each other, and torque can be transmitted at a constant speed even when the two shafts take an operating angle. As a sliding type constant velocity universal joint, for example, a tripod type joint as described in patent document 1 below is known.

The tripod constant velocity universal joint includes an outer joint member, a tripod member disposed on an inner periphery of the outer joint member and having three leg shafts protruding radially outward, and three rollers mounted on outer peripheries of the respective leg shafts. As shown in fig. 8, the roller 102 is rotatably supported by the outer periphery of the footaxle 101 by sandwiching a plurality of needle rollers 103 between the outer periphery of the footaxle 101 of the tripod member 100 and the inner periphery of the roller 102. An outer washer 104 and an inner washer 105 are provided on both sides of the needle 103 in the axial direction of the foot shaft (the axial direction of the foot shaft 101, up-down direction in fig. 8). An annular groove 106 is provided on the outer peripheral surface near the shaft end of the foot shaft 101, and a retainer ring 107 is fitted in the annular groove 106.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2001-330049

Disclosure of Invention

Problems to be solved by the invention

When the tripod type constant velocity universal joint rotates in a state of taking the operating angle, as shown in fig. 9, when the roller 102 moves toward the shaft end side with respect to the foot shaft 101, the needle roller 103 moves toward the shaft end side of the foot shaft 101. The needle 103 is in contact with the outer washer 104, and the outer washer 104 is in contact with the retainer ring 107, so that the movement of the needle 103 toward the foot shaft end side is restricted. At this time, the retainer ring 107 abuts against a flange portion 108 provided on the shaft end side of the annular groove 106 in the foot shaft 101, and a load F' toward the shaft end side is applied to the flange portion 108. Under the load F', the corner 106a on the shaft end side of the groove bottom of the annular groove 106 is stressed, and therefore, the strength and durability of the flange 108 need to be ensured.

The tripod member 100 is generally formed of steel, and is subjected to a heat treatment such as carburizing, quenching, tempering, or the like in order to secure strength and durability. Due to this heat treatment, a hardened layer is formed on the surface of the foot shaft 101, and when the flange portion 108 is hardened, toughness may be lowered. When the tripod member 100 is handled in a single state before the roller 102 and the like are assembled, the flange 108 provided at the tip end portion of the foot shaft 101 is easily brought into contact with other components and devices. Therefore, when the flange portion 108 is hardened by the heat treatment as described above, damage such as breakage or chipping is likely to occur by contact with other members or equipment.

Accordingly, an object of the present invention is to improve durability and strength of a tripod member of a tripod type constant velocity universal joint.

Means for solving the problems

In order to solve the above problems, the present invention provides a tripod constant velocity universal joint comprising: an outer joint member having axially extending raceway grooves formed at three circumferential positions on an inner circumferential surface, each raceway groove having a pair of roller guide surfaces facing each other in a circumferential direction; a tripod member disposed on an inner periphery of the outer joint member and having a boss portion and three leg shafts protruding in a radial direction from an outer peripheral surface of the boss portion toward the track groove, the boss portion having a shaft hole; three rollers rotatably supported by the foot shaft and accommodated in the track grooves; a plurality of rolling elements interposed between an outer peripheral surface of the footshaft and an inner peripheral surface of the roller; an outer washer disposed closer to the shaft end side of the foot shaft than the rolling element; an annular groove formed on the outer peripheral surface of the foot shaft; and a retainer ring which is fitted in the annular groove and restricts movement of the outer washer toward the shaft end side of the foot shaft, wherein,

A hardened layer is formed in a region including a flange portion provided on the shaft end side of the annular groove in the surface of the foot shaft,

The depth K of the annular groove is less than or equal to the axial dimension L of the outer peripheral surface of the flange part,

The axial dimension L is more than 0.8 mm.

By suppressing the depth K of the annular groove to the axial dimension L or less of the outer peripheral surface of the flange portion in this way, even when the flange portion is deformed by the load at the time of contact with the retainer ring, stress applied to the corner portion on the shaft end side of the groove bottom of the annular groove can be suppressed, and thus durability can be improved.

In addition, even in the case where the hardened layer is formed in the region including the flange portion in the surface of the foot shaft, the strength of the flange portion is improved by securing the axial dimension of the outer peripheral surface of the flange portion to 0.8mm or more, so that damage to the flange portion can be prevented.

In the tripod type constant velocity universal joint described above, when the outer diameter of the foot shaft is Dj, the effective hardened layer depth t of the hardened layer is preferably t/(Dj/2) =0.035 to 0.14 when 513Hv is the limit hardness.

The magnitude of the axial dimension L of the outer peripheral surface of the flange portion of the foot shaft affects the circumscribed circle diameter SDj of the tripod member and the large inner diameter D1 (see fig. 1) of the outer joint member. That is, when the axial dimension L of the outer peripheral surface of the flange portion becomes large, the circumscribed circle diameter SDj of the tripod member becomes large as well. When the circumscribed circle diameter SDj of the tripod member is excessively large, the large inner diameter D1 of the outer joint member needs to be increased in order to avoid interference with the outermost diameter portion (the tip end of the foot shaft) of the outer joint member, but in this case, the tripod type constant velocity universal joint as a whole is increased in size.

Therefore, it is preferable to set the upper limit value of the axial dimension L of the outer peripheral surface of the flange portion while maintaining the design for realizing the light weight and the downsizing of the tripod type constant velocity universal joint. Specifically, it is preferable that the ratio dr/SDj between the outer diameter dr of the boss portion and the circumscribed circle diameter SDj of the tripod member is set to 0.65 to 0.70, the ratio D2/D1 between the large inner diameter D1 and the small inner diameter D2 of the outer coupling member is set to 0.66 to 0.72, and the ratio L/PCD between the axial dimension L of the outer peripheral surface of the flange portion and the pitch circle diameter PCD of the roller guide surface is set to 0.065 or less.

Preferably, a concave curved surface having an arc-shaped cross section is provided at a corner of the annular groove at the axial end side of the groove bottom. In particular, when the cross section of the retainer ring is circular, the radius of curvature R of the concave curved surface is preferably set to be equal to the radius D/2 of the cross section of the retainer ring. Specifically, the radius of curvature R of the concave curved surface is preferably set to (0.75 to 1.02) × (D/2). Accordingly, when a load is applied to the flange portion toward the foot shaft end side, the stress applied to the corner portion on the shaft end side of the groove bottom of the annular groove is relaxed, and therefore the durability is further improved.

Effects of the invention

As described above, according to the present invention, the durability and strength of the tripod member of the tripod type constant velocity universal joint, particularly the durability and strength of the flange portion at the tip end of the foot shaft and the periphery thereof can be improved.

Drawings

Fig. 1 is a cross-sectional view of a tripod type constant velocity universal joint according to an embodiment of the present invention in a direction perpendicular to an axial center.

Fig. 2 is a cross-sectional view taken along line X-X of fig. 1.

Fig. 3 is an enlarged view of the vicinity of the retainer ring of fig. 2.

Fig. 4 is a view of the vicinity of the retainer ring in fig. 3, which is further enlarged.

Fig. 5 is a cross-sectional view showing a state in which the constant velocity universal joint of fig. 1 takes an operating angle.

Fig. 6 is an enlarged view of the vicinity of the retainer ring of fig. 5.

Fig. 7 is a cross-sectional view of the front end of the foot axle.

Fig. 8 is a cross-sectional view of a tripod unit of a conventional tripod type constant velocity universal joint.

Fig. 9 is a sectional view showing a state in which the needle roller of the tripod unit of fig. 7 moves to the shaft end side.

Description of the reference numerals

1. Tripod constant velocity universal joint

2. Outer coupling member

3. Cup part

4. Raceway groove

4A, 4b roller guide surfaces

5. Tripod member

6. Boss portion

7. Internal spline

8. Foot shaft

10. Roller

11. Annular groove

12. Outer gasket

13. Inner gasket

14. Retainer ring

15. Flange part

16. Front end face

17. And (3) hardening the layer.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 and 2 show a tripod type constant velocity universal joint 1 according to an embodiment of the present invention. The tripod type constant velocity universal joint 1 (hereinafter, also simply referred to as "constant velocity universal joint 1") is one type of a sliding type constant velocity universal joint that allows angular displacement and axial displacement of both shafts on a driving side and a driven side, and is coupled to a fixed type constant velocity universal joint via an intermediate shaft 20 to constitute a drive shaft, for example. The drive shaft is mounted on an automobile, for example, and transmits rotational torque output from a drive source such as an engine or an electric motor mounted on a chassis to drive wheels. In this drive shaft, the tripod type constant velocity universal joint 1 is disposed on the drive source side, and the fixed type constant velocity universal joint is disposed on the drive wheel side.

The constant velocity universal joint 1 includes: an outer coupling member 2 having a cup portion 3 having a bottomed tubular shape; and a tripod unit as a coupling inner member disposed in the inner space of the cup portion 3. The tripod unit includes a tripod member 5 and a ring-shaped roller 10 as a torque transmitting member. Hereinafter, the terms "axial", "radial", and "circumferential" are used for the purpose of describing the directionality, but are not particularly limited, and they are the direction along the central axis of the cup 3, the radial direction of a circle centered on the central axis (the radial direction of the cup 3), and the circumferential direction of a circle centered on the central axis (the circumferential direction of the cup 3), respectively.

The tripod member 5 integrally has a cylindrical boss portion 6 and three leg shafts 8 arranged at equal intervals (120 ° intervals) in the circumferential direction and extending radially outward from the outer peripheral surface of the boss portion 6. An internal spline 7 is formed in the shaft hole of the boss portion 6, and an external spline 21 formed in the intermediate shaft 20 is coupled to the internal spline 7 so as to be able to transmit torque. The front end surface 16 provided at the outer diameter end of the foot shaft 8 is spherical and faces the inner peripheral surface (inner peripheral surface of the large diameter portion) of the track groove 4 of the outer joint member 2 in the radial direction.

A roller 10 is fitted to a cylindrical outer peripheral surface 8a of each leg shaft 8 provided in the tripod member 5, and a plurality of needle rollers 9 are disposed between the outer peripheral surface 8a and the roller 10. Thereby, the roller 10 is rotatably supported on the outer periphery of the foot shaft 8. Each needle roller 9 is disposed on the cylindrical outer peripheral surface 8a of the foot shaft 8 so as to be capable of rolling along the circumferential direction of the foot shaft 8.

Three track grooves 4 are provided at equal intervals (120 ° pitch) in the circumferential direction on the inner periphery of the cup portion 3 of the outer joint member 2, and the rollers 10 are accommodated in the track grooves 4. Each of the track grooves 4 has a pair of roller guide surfaces 4a, 4b that face each other and guide the outer peripheral surface of the roller 10, and is also formed in a straight line extending in the axial direction including the roller guide surfaces 4a, 4b. The contact manner of the roller 10 with the roller guide surfaces 4a, 4b is angular contact (two-point contact) or annular contact (one-point contact).

The following describes a structure for preventing the needle roller 9 and the roller 10 from coming off the foot shaft 8. In the following description, the axial direction of the foot shaft 8 (up-down direction in fig. 3) is referred to as "foot shaft axial direction", the shaft end side of the foot shaft 8 (upper side in fig. 3) is referred to as "foot shaft end side", and the opposite side thereof (lower side in fig. 3) is referred to as "foot shaft root side".

As shown in fig. 2, an annular outer washer 12 is disposed on the foot shaft end side of the needle roller 9, and an annular inner washer 13 is disposed on the foot shaft root side of the needle roller 9. The outer washer 12 is externally embedded near the shaft end of the foot shaft 8, and the inner washer 13 is externally embedded near the root of the foot shaft 8. As shown in fig. 3, the outer washer 12 includes a disk portion 12a extending in a direction perpendicular to the axial direction of the foot shaft, a cylindrical portion 12b extending from an outer peripheral end of the disk portion 12a toward the axial end side of the foot shaft (upper side in the drawing), and a protruding portion 12c protruding from an end portion of the cylindrical portion 12b toward the outer diameter side of the foot shaft 8 (right side in the drawing).

An annular groove 11 is formed in the outer peripheral surface near the shaft end of the foot shaft 8, and a retainer ring 14 is fitted in the annular groove 11. The cross section of the retainer ring 14 is circular, and the retainer ring 14 has an end ring shape (C shape) in which a part of the circumferential direction is discontinuous. The retainer ring 14 is pressed against the bottom of the annular groove 11 by its own elastic force. The inner peripheral portion of the retainer ring 14 is fitted into the annular groove 11, and the outer peripheral portion of the retainer ring 14 protrudes toward the outer diameter side from the cylindrical outer peripheral surface 8a of the foot shaft 8.

As shown in fig. 4, the annular groove 11 has a cylindrical surface 11a, a locking surface 11b provided on the foot shaft end side of the cylindrical surface 11a, and a tapered surface 11c provided on the foot shaft root side of the cylindrical surface 11 a. The cylindrical surface 11a is a minimum diameter portion of the annular groove 11. The locking surface 11b is a flat surface orthogonal to the axial direction of the foot shaft. The tapered surface 11c expands in diameter toward the foot shaft root side. The tapered surface 11c is provided at the foot shaft root side end of the annular groove 11, and is connected to the cylindrical outer peripheral surface 8a of the foot shaft 8.

The cylindrical surface 11a and the tapered surface 11c are smoothly connected via a concave curved surface 11d having an arc-shaped cross section. The cylindrical surface 11a and the locking surface 11b are smoothly connected via a concave curved surface 11e having an arc-shaped cross section. The radius of curvature R of the concave curved surface 11e is equal to the radius D/2 of the cross section of the retainer ring 14, specifically, is set so as to satisfy r= (0.75 to 1.02) × (D/2). In the illustrated example, the radius of curvature R of the concave curved surface 11e is slightly smaller than the radius D/2 of the retainer ring 14 (R < D/2).

The retainer ring 14 is pressed against the cylindrical surface 11a of the annular groove 11 by its own elastic force. The retainer ring 14 is restricted from moving toward the foot shaft end side by the engagement surface 11b, and is restricted from moving toward the foot shaft root side by the tapered surface 11 c. In the illustrated example, the retainer ring 14 contacts the annular groove 11 at three points, i.e., the cylindrical surface 11a, the locking surface 11b, and the tapered surface 11 c. However, because of dimensional tolerances of the respective members, the diameter D of the cross section of the retainer ring 14 and the inclination angle of the tapered surface 11c fluctuate, the retainer ring 14 may not contact either or both of the locking surface 11b and the tapered surface 11 c. In the present embodiment, the shape of the annular groove 11 is set so that the retainer ring 14 does not come up from the cylindrical surface 11a of the annular groove 11 even if dimensional tolerances occur in the respective members, but necessarily comes into contact with the cylindrical surface 11a.

As shown in fig. 5, when the constant velocity universal joint 1 rotates in a state of taking the operating angle, the rollers 10 roll around the axis of the foot shaft 8 while reciprocating in the foot shaft axis direction with respect to the foot shaft 8. When the roller 10 moves toward the shaft end side with respect to the footaxle 8 in this way, the needle roller 9 moves toward the shaft end side and contacts the outer washer 12, and the outer washer 12 contacts the retainer ring 14, thereby restricting the movement of the needle roller 9 toward the footaxle shaft end side (see fig. 6). At this time, the retainer ring 14 is in contact with the engagement surface 11b of the annular groove 11, and thus loads the flange portion 15 provided on the shaft end side of the annular groove 11 with a load F directed toward the shaft end side. The outer peripheral surface of the flange 15 is a cylindrical surface having the same diameter as the cylindrical outer peripheral surface 8a on which the needle roller 9 rolls.

In the present embodiment, the depth K of the annular groove 11 (the difference in radius between the cylindrical surface 11a of the annular groove 11 and the cylindrical outer peripheral surface 8a of the foot shaft 8) is suppressed to be equal to or smaller than the axial dimension L of the outer peripheral surface of the flange portion 15. Accordingly, when the load F is applied from the retainer ring 14 to the flange portion 15, the stress applied to the corner portion on the shaft end side of the groove bottom of the annular groove 11 can be suppressed, and therefore the durability of the tripod member 5 is improved. In the illustrated example, since the concave curved surface 11e having an arc-shaped cross section is provided at the corner of the groove bottom of the annular groove 11 on the shaft end side, stress applied to the portion can be further suppressed.

The tripod pin member 5 uses steel, such as chrome steel, chrome molybdenum steel, specifically, steel consisting of JIS G4053: 2016, the SCM420 and the SCr420 are integrally formed. The tripod member 5 is manufactured through a forging process, a turning process, a broaching process, a heat treatment process, and a grinding process.

In the forging step, a billet is put into a cavity of a forging die, and the die is filled with the billet by plastic working. Thus, a tripod member blank in which the boss portion 6 and the foot shaft 8 are formed is obtained. The reference numerals of the respective portions of the tripod member blank used below refer to the reference numerals of the respective portions of the tripod member 5 described above.

In the turning step, the cylindrical outer peripheral surface 8a of the pin shaft 8, the annular groove 11, the tip end surface 16, and the cylindrical inner peripheral surface (lower diameter of the internal spline 7) of the shaft hole in the tripod member blank are machined.

In the broaching step, the inner peripheral surface of the shaft hole of the turned tripod member blank is subjected to broaching to form the internal spline 7.

In the heat treatment step, the tripod member blank after the broaching step is subjected to carburizing and quenching, and a hardened layer 17 (cross-hatched area in fig. 7) having a higher hardness than the inside is formed on the surface of the tripod member blank. The hardened layer 17 is formed in a region including at least the flange portion 15 (scattered point region) in the surface of the foot shaft 8. For example, the hardened layer 17 is formed on the surface of the foot shaft 8 in a region including the cylindrical outer peripheral surface 8a on which the needle roller 9 rolls and a region on the foot shaft end side of the cylindrical outer peripheral surface 8a (the inner surface of the annular groove 11 and the outer peripheral surface of the flange portion 15). In the present embodiment, the hardened layer 17 is formed over the entire surface of the tripod member blank. The depth of the hardened layer 17 is deeper than the depth K of the annular groove 11. As a result, the hardened layer 17 is formed over the entire region of the flange portion 15 (over the entire region on the outer diameter side of the cylindrical surface 11a of the annular groove 11). In the present embodiment, when the effective hardened layer depth of the hardened layer 17 is set to t (see fig. 7) and the outer diameter of the foot shaft 8 is set to Dj (see fig. 2) at 513Hv, the effective hardened layer depth t of the hardened layer 17 is set so as to satisfy t/(Dj/2) =0.035 to 0.14. The heat treatment is not limited to carburizing, quenching and tempering, and may be other quenching treatments (e.g., induction hardening).

In the grinding step, the cylindrical outer peripheral surface 8a of the foot shaft of the heat-treated tripod member blank is finished by grinding. Through the above process, the tripod member 5 is formed.

The tripod member 5 manufactured through the above-described steps is stored in the standby space and then transported to the assembling step. In this way, when the tripod member 5 is handled as a single body, the flange portion 15 of the tripod member 5 may come into contact with other tripod members 5, devices, or the like. In the present embodiment, since the flange portion 15 is hardened by the hardened layer 17 as described above, and becomes a state of low toughness and brittleness, when the tripod member 5 is handled as a single body, the flange portion 15 is easily damaged when it comes into contact with other tripod members 5, equipment, and the like.

In the present embodiment, the axial dimension L of the outer peripheral surface of the flange 15 is 0.8mm or more. In this way, by setting the axial dimension L of the flange portion 15 to a large value, the strength of the flange portion 15 is improved, and therefore damage to the flange portion 15 can be prevented.

In the tripod type constant velocity universal joint 1 of the present embodiment, in order to balance strength and durability, and to be a lightweight and small tripod type constant velocity universal joint, various dimensional ratios shown below are managed in the same manner as the conventional tripod type constant velocity universal joint shown in the above-mentioned patent document 1.

(1) The ratio d/PCD of the shaft hole diameter d (see FIG. 1) provided in the tripod member 5 to the pitch diameter PCD (see FIG. 1) of the roller guide surfaces 4a, 4b of the track grooves 4 is set to 50 to 55%. The shaft hole diameter d is a diameter of a large diameter portion of the internal spline formed in the shaft hole of the boss portion 6, and is determined based on the allowable load capacity of the shaft member spline-fitted to the shaft hole. The pitch diameter PCD of the roller guide surfaces 4a, 4b is a diameter of a circle connecting the intersection point of the width direction center of the contact portion where each roller 10 contacts the roller guide surfaces 4a, 4b (in the example of the figure, the width direction center of the roller 10) and the axial center of each leg shaft 8, and is determined based on the width (thickness) and the outer diameter of the roller 10, specifically, the ratio of the thickness of the roller 10 to the outer diameter of the roller 10.

(2) The ratio dr/SDj of the outer diameter dr (see fig. 1) of the boss portion 6 of the tripod member 5 to the circumscribed circle diameter SDj (see fig. 1) of the tripod member 5 is set to 65 to 70%. The outer diameter dr of the boss portion 6 is determined based on the torsional strength required when the constant-speed universal joint 1 is loaded with a predetermined rotational torque. The circumscribed circle diameter SDj of the tripod member 5 is a diameter of a circle connecting spherical surfaces provided at the shaft ends of the footholds 8, and is determined based on the width of the roller 10, the large inner diameter D1 (see fig. 1) of the cup portion 3, and the like.

(3) The ratio D2/D1 of the large inner diameter D1 (see FIG. 1) of the cup 3 to the small inner diameter D2 (see FIG. 1) of the cup 3 is 66 to 72%. The large inner diameter D1 and the small inner diameter D2 of the cup portion 3 are set based on the outer diameter dr of the boss portion 6 of the tripod member 5, the circumscribed circle diameter SDj of the tripod member 5, and the pitch circle diameter PCD of the roller guide surfaces 4a, 4 b.

(4) The ratio Ls/Ds of the width Ls (see fig. 2) of the roller 10 to the outer diameter Ds (see fig. 2) of the roller 10 is set to 24 to 27%. The width Ls of the roller 10 and the outer diameter Ds of the roller 10 are set in consideration of the contact elliptic length and the contact surface pressure between the roller 10 and the roller guide surfaces 4a, 4b when the constant speed universal joint 1 is loaded with a predetermined torque.

(5) The ratio Dj/Ds of the diameter Dj (see FIG. 2) of the cylindrical outer peripheral surface 8a of the foot shaft 8 of the tripod member 5 to the outer diameter Ds of the roller 10 is set to 54 to 57%. The diameter Dj of the foot shaft 8 is set based on the required torsional strength.

(6) The ratio Dj/d of the shaft hole diameter d of the tripod member 5 to the diameter Dj of the foot shaft 8 is set to 83 to 86%. As described above, the shaft hole diameter d and the diameter Dj of the foot shaft 8 are set based on the required torsional strength.

(7) The ratio Ln/Dj of the length Ln (see FIG. 2) of the needle roller 9 to the diameter Dj of the foot shaft 8 is 47 to 50%. The needle length Ln is set in consideration of the maximum contact surface pressure of the bearing.

In the present embodiment, as described above, the axial dimension L of the outer peripheral surface of the flange portion 15 of the tripod member 5 is ensured to be 0.8mm or more. When the axial dimension L of the outer peripheral surface of the flange portion 15 becomes large, the circumscribed circular diameter SDj of the tripod member 5 becomes large as well. In this case, in order to avoid interference between the foot shaft 8 of the tripod member 5 and the large diameter portion of the outer joint member 2, the large inner diameter D1 of the outer joint member 2 needs to be increased, but in this case, the size of the entire constant velocity universal joint 1 increases.

Therefore, it is preferable to set the upper limit value of the axial dimension L of the outer peripheral surface of the flange portion 15 while maintaining the design for realizing the light weight and the small size of the constant velocity universal joint 1 shown in (1) to (7). Specifically, it is preferable that the ratio L/PCD of the axial dimension L of the outer peripheral surface of the flange portion 15 to the pitch diameter PCD of the roller guide surfaces 4a, 4b is set to 0.065 or less, in addition to the circumscribed circle diameter SDj of the tripod member 5 being set so as to satisfy the above (2) and the large inner diameter D1 of the outer joint member 2 being set so as to satisfy the above (3).

The present invention is not limited to the above-described embodiments. Hereinafter, other embodiments of the present invention will be described, but the same points as those of the above embodiments will not be described repeatedly.

The shape of the annular groove 11 is not limited to the above, and may be, for example, a rectangular cross-section. The cross section of the retainer ring 14 is not limited to a circular shape, and may be a non-circular shape such as a rectangular shape.

The inner washer 13 may also be omitted. In this case, the needle roller 9 is brought into direct contact with the root portion of the foot shaft 8 (the outer peripheral surface of the boss portion 6), whereby the movement of the needle roller 9 toward the foot shaft root portion side is restricted.

Claims (5)

1. A tripod constant velocity universal joint is provided with:

An outer joint member having axially extending raceway grooves formed at three circumferential positions on an inner circumferential surface, each raceway groove having a pair of roller guide surfaces facing each other in a circumferential direction;

A tripod member disposed on an inner periphery of the outer joint member and having a boss portion and three leg shafts protruding radially from an outer peripheral surface of the boss portion toward the track groove;

Three rollers rotatably supported by the foot shaft and accommodated in the track grooves;

A plurality of rolling elements interposed between an outer peripheral surface of the footshaft and an inner peripheral surface of the roller;

an outer washer disposed closer to the shaft end side of the foot shaft than the rolling element;

an annular groove formed on the outer peripheral surface of the foot shaft; and

A retainer ring which is fitted in the annular groove and restricts movement of the outer washer toward the shaft end side of the foot shaft,

Wherein,

A hardened layer is formed in a region including a flange portion provided on the shaft end side of the annular groove in the surface of the foot shaft,

The depth K of the annular groove is less than or equal to the axial dimension L of the outer peripheral surface of the flange part,

The axial dimension L of the outer peripheral surface of the flange part is more than 0.8 mm.

2. The tripod type constant velocity universal joint according to claim 1, wherein,

The effective hardening layer depth t of the hardening layer in the case of 513Hv being the limit hardness satisfies the condition that the outer diameter of the foot shaft is set to Dj

t/(Dj/2)＝0.035～0.14。

3. The tripod type constant velocity universal joint according to claim 1, wherein,

The ratio dr/SDj of the outer diameter dr of the boss portion to the circumscribed circle diameter SDj of the tripod member is set to 0.65 to 0.70,

The ratio D2/D1 of the large inner diameter D1 to the small inner diameter D2 of the outer coupling member is set to 0.66-0.72,

The ratio L/PCD of the axial dimension L of the outer peripheral surface of the flange portion to the pitch diameter PCD of the roller guide surface is set to 0.065 or less.

4. The tripod type constant velocity universal joint according to claim 1, wherein,

A concave curved surface having an arc-shaped cross section is provided at a corner of the groove bottom of the annular groove on the shaft end side.

5. The tripod type constant velocity universal joint according to claim 4, wherein,

The cross section of the check ring is circular,

When the diameter of the cross section of the retainer ring is D, the radius of curvature R of the concave curved surface is (0.75 to 1.02) × (D/2).