JP2001193752A - Constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability and strength. SOLUTION: A tripod member 20 is manufactured of a steel material having a carbon content of 0.15-0.40 wt.% in the main processes of forging, machining, carburization hardening and tempering, and grinding on the outer periphery 22a of a leg shaft 22, in sequence. A softening property resistance value R for the leg shaft 22 and other portions of the tripod member 20 after completion is limited within 705<R <=820, preferably 710<=R<=810. An outside joint member 10 is manufactured of a steel material having a carbon content of 0.15-0.40 wt.% in the main processes of forging, machining, carburization hardening and tempering, and grinding on a shaft portion 10a, in sequence. A softening property resistance value R for the outside joint member 10 after completion is limited within 705<R<=820, preferably 710<=R<=810.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant velocity universal joint used for a power transmission device of an automobile or various industrial machines, and more particularly to a tripod type constant velocity universal joint.

[0002]

2. Description of the Related Art For example, as one element of a power transmission device for transmitting rotational power from an automobile engine to wheels (as a coupling for connecting a drive shaft or a propeller shaft),
A tripod type constant velocity universal joint is used.

In general, a tripod type constant velocity universal joint has an outer joint member having three axial track grooves formed on an inner peripheral portion thereof and having an axial roller guide surface on both sides of each track groove, and a radius. It has three leg axes protruding in the directions,
A tripod member in which a roller is rotatably disposed on each leg shaft is mainly configured. When the leg shaft of the tripod member and the roller guide surface of the outer joint member engage in the rotational direction via the roller, rotational torque is transmitted at a constant speed from the driving side to the driven side. In addition, the relative axial displacement and angular displacement between the outer joint member and the tripod member are absorbed by each roller rolling on the roller guide surface while rotating with respect to the leg axis, When the outer joint member and the tripod member transmit rotational torque while maintaining an operating angle, the axial displacement of each leg shaft with respect to the roller guide surface due to the change in the rotational direction phase is absorbed.

As a tripod type constant velocity universal joint, there is a type in which the above roller is mounted on a cylindrical outer peripheral surface of a leg shaft via a plurality of needle rollers, but the outer joint member and the tripod member take an operating angle while taking an operating angle. When transmitting rotational torque,
Since the rollers and the roller guide surface obliquely intersect with each other with the inclination of the leg shaft, slippage occurs between the two, and the sliding resistance at that time hinders the smooth rolling of each roller. There is a problem that the induced thrust increases. Also,
Due to the sliding resistance between each roller and the roller guide surface, there is a problem that the sliding resistance when the outer joint member and the tripod member are relatively displaced in the axial direction increases.

Therefore, in order to eliminate the oblique state between the roller and the roller guide surface and to reduce induced thrust and slide resistance, a mechanism (roller mechanism) that allows the roller to swing freely with respect to the leg shaft is provided. Various proposed tripod type constant velocity universal joints have been proposed and put into practical use. As a tripod-type constant velocity universal joint of this kind, for example, a configuration including an outer roller guided on a roller guide surface and an inner roller rotatably supported on the outer peripheral surface of a leg shaft via a plurality of needle rollers. It has been known. This configuration is further described below.
Can be roughly divided into the following modes.

The outer peripheral surface of the outer roller has a convex spherical shape (a “true spherical surface” having a center of curvature on the axis of the leg axis, and a so-called “torus surface” in which the center of curvature is offset from the axis of the leg axis toward the outer diameter side). The inner peripheral surface is cylindrical, the outer peripheral surface of the inner roller is convex, and the slip between the cylindrical inner peripheral surface of the outer roller and the convex outer peripheral surface of the inner roller is
The outer roller can be swung freely.
No. 1529).

The outer peripheral surface of the outer roller has a convex spherical shape (true spherical surface,
Includes both torus surfaces. ), The inner peripheral surface is in line contact with the outer peripheral surface of the inner roller, the outer peripheral surface of the inner roller is convex spherical, and the outer peripheral surface is slipped by the slip between the inner peripheral surface of the outer roller and the convex spherical outer peripheral surface of the inner roller. In order to make the roller swing freely and further reduce the induced thrust and slide resistance, the load component that directs the inner peripheral surface of the outer roller to the tip of the leg shaft at the contact position with the outer peripheral surface of the inner roller (For example, JP-A-9-14280).

The roller guide surface is flat, the outer surface of the outer roller is cylindrical, the inner surface is concave, the outer surface of the inner roller is convex, and the inner surface of the outer roller is convex and the inner surface is convex. The outer roller can be swung freely by sliding between the spherical outer surface (Japanese Patent Application No. 8-4073,
Japanese Patent Application No. 8-138335).

In addition to the above arrangement, the roller guide surface and the axis of the leg shaft are non-parallel to each other with an operating angle of 0 ° (JP-A-11-13779).

Further, as a tripod type constant velocity universal joint of this type, a roller assembly is formed by forming an outer peripheral surface of a leg shaft into a convex spherical shape and assembling a roller with a support ring via a plurality of needle rollers. A configuration is known in which a cylindrical inner peripheral surface of a ring is externally fitted to a convex spherical outer peripheral surface of a leg shaft (Japanese Patent Publication No. 7-117108, Patent 2623).
No. 216). According to this configuration, the sliding between the cylindrical inner peripheral surface of the support ring and the convex spherical outer peripheral surface of the leg shaft allows the roller assembly including the roller to swing freely.

Further, the present applicant has proposed a method for reducing the induced thrust and sliding resistance in this type of tripod type constant velocity universal joint more effectively by providing a roller guided on a roller guide surface and an outer peripheral surface of a leg shaft. A support ring that is fitted to the outside and rotatably supports the roller, the inner peripheral surface of the support ring is an arc-shaped convex cross section, and the outer peripheral surface of the leg shaft is straight in a vertical cross section, and An application has already been filed for a configuration that comes into contact with the inner peripheral surface of the support ring in a direction perpendicular to the axis of the joint, and that forms a clearance between the inner peripheral surface of the support ring in the axial direction of the joint. (Japanese Patent Application No. 11-0559040). According to this configuration,
Sliding between the inner peripheral surface of the arc-shaped convex cross section of the support ring and the straight outer peripheral surface of the leg shaft allows the roller assembly including the roller to swing freely.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a tripod-type constant velocity universal joint having a roller mechanism as described above, in which the rolling fatigue life of components and the strength against torsional fatigue and the like are increased. , Providing tripod type constant velocity universal joints with superior durability and strength while maintaining the current size, and more compact tripod type constant velocity universal while ensuring durability and strength equal to or higher than the current product It is intended to provide a joint.

[0013]

In order to solve the above-mentioned problems, the present invention has three track grooves formed in the inner peripheral portion in the axial direction, and has axial roller guide surfaces on both sides of each track groove. Outer joint member having a radially projecting 3
A tripod member having a plurality of leg shafts, and a roller mechanism mounted on each leg shaft of the tripod member, wherein the roller mechanism swings freely with respect to the leg shaft and moves outward along the roller guide surface. In a constant velocity universal joint having a roller guided in a direction parallel to an axis of the joint member, at least one
Provided is a configuration in which the softening resistance characteristic value (R) of two components is regulated within a predetermined range.

As a result of many experiments, the present applicant has found that the durability of the components of the constant velocity universal joint, particularly the durability of the tripod member and the outer joint member, can be improved with high accuracy by using the softening resistance characteristic value R. We found that we could manage.

Taking a tripod member as an example, factors that affect its durability include rolling fatigue of the outer peripheral surface of the leg shaft,
Examples include torsional fatigue at the base end of the leg shaft, and torsional fatigue at the serration (or spline). The outer peripheral surface of the leg shaft
Rolling contact with the outer peripheral surface of the needle roller or rolling and sliding contact with the inner peripheral surface of the support ring of the roller assembly causes rolling fatigue. At the base end and serrations of the leg shaft, torsional stress concentrates during torque transmission,
Moreover, since these portions are usually left unground, torsional fatigue becomes a problem. In the case of the outer joint member as an example, factors affecting the durability include rolling fatigue of the roller guide surface of the track groove. Since the roller guide surface is in rolling and sliding contact with the outer peripheral surface of the roller, rolling fatigue is a problem. Further, since the outer joint member receives a joint load via the roller, cracking strength is also a problem. Further, with respect to the components constituting the roller mechanism, there is a problem of rolling fatigue at a portion where rolling contact or sliding contact with a mating member occurs.

In general, it is well known that the fatigue strength of a steel material has a correlation with the surface hardness, and a heat treatment or the like is performed on the steel material to form a surface hardened layer, and the surface hardness of the hardened surface is controlled. Thus, required fatigue strength is ensured. However, according to the results of experiments conducted by the present applicant, fatigue strength is more closely correlated with the softening resistance characteristic in the region from the surface to a predetermined depth (the property that the material is hard to soften even at a certain high temperature) than the surface hardness. Was found to have The softening resistance characteristic can be correctly evaluated by the maximum hardness in a region within 0.5 mm in depth from a predetermined surface (softening resistance characteristic value R), and the softening resistance characteristic value R is evaluated for fatigue strength. It turns out that it can be used as an index. Here, “softening resistance characteristic value R”
Is expressed as the value of the maximum Vickers hardness Hv in a region within 0.5 mm in depth from the surface after quenching the components and then tempering at 200 ° C. for 2 hours. By regulating the softening resistance characteristic value R within a predetermined range, the rolling fatigue life of the component parts can be increased, and the strength against torsional fatigue and the like can be increased.

The component parts have a carbon content of 0.15 to 0.40
In the case where the surface layer is formed of steel by weight% and a surface layer is formed immediately below a predetermined surface by carburizing, quenching and tempering, the softening resistance characteristic value R is regulated within a range of 705 <R ≦ 820, preferably 710 ≦ R ≦ 815. Thereby, a desired result can be obtained.

The component parts have a carbon content of 0.15 to 0.40
Also in the case of forming the surface layer by carbonitriding, quenching and tempering just below a predetermined surface, the softening resistance characteristic value R is set to 705 <R ≦ 820, preferably 710 ≦ R ≦ 81.
By restricting within the range of 5, desirable results can be obtained.

Further, the component parts have a carbon content of 0.45 to 0.45.
When formed from 0.60 wt% steel and the surface layer is formed immediately below a predetermined surface by induction hardening and tempering, the softening resistance characteristic value R is 630 <R ≦ 820, preferably 640 ≦ R.
By restricting within the range of ≦ 810, a desired result can be obtained.

The roller mechanism of the constant velocity universal joint according to the present invention includes a roller guided on a roller guide surface, and a support ring externally fitted on the outer peripheral surface of the leg shaft and rotatably supporting the roller. The inner peripheral surface of the ring has an arc-shaped convex cross section, the outer peripheral surface of the leg shaft has a straight shape in a vertical cross section, and contacts the inner peripheral surface of the support ring in a direction perpendicular to the axis of the joint in a cross section, and In addition, it is possible to adopt a configuration in which a clearance is formed between the joint ring and the inner peripheral surface of the support ring in the axial direction of the joint. In this configuration, the roller assembly including the roller and the support ring is moved relative to the leg shaft.
Swing and swing as a unit. Here, the swinging of the neck means that the axes of the support ring and the roller are inclined with respect to the axis of the leg axis in a plane including the axis of the leg axis.

The cross-sectional shape of the leg shaft may be such that it makes contact with the inner peripheral surface of the support ring in a direction perpendicular to the axis of the joint and forms a clearance with the inner peripheral surface of the support ring in the axial direction of the joint. In other words, the shape means a shape in which the surface portions of the tripod member facing each other in the axial direction are retracted in the mutual direction, that is, on the smaller diameter side than the virtual cylindrical surface. One specific example is a substantially elliptical shape. The “substantially elliptical shape” includes not only an elliptical shape as it is literally but also a shape generally called an oval shape, an oval shape, or the like.

By adopting the above-described cross-sectional shape of the leg shaft, which has been conventionally circular, when the joint takes an operating angle, the leg shaft is inclined with respect to the outer joint member without changing the attitude of the roller assembly. be able to. In addition, since the contact ellipse between the outer peripheral surface of the leg shaft and the support ring approaches a point from the conventional horizontally long shape (see FIG. 1C), the friction moment for tilting the roller assembly is reduced. Therefore, the attitude of the roller assembly is always stable, and the roller can be smoothly rolled because the roller is held parallel to the roller guide surface. This contributes to a reduction in slide resistance and a reduction in induced thrust.

The roller assembly plays a role of transmitting torque by being interposed between the leg shaft and the outer joint member. The direction of torque transmission in this kind of constant velocity universal joint is always the axis of the joint. Since the direction is perpendicular to the direction of transmission, the transmission of torque is possible by the contact between the leg shaft and the support ring in the direction of transmission of the torque, and even if there is a clearance between the two in the axial direction of the joint, the transmission of torque is possible. There is no hindrance.

In the above configuration, the generatrix of the inner peripheral surface of the support ring can be constituted by the arc portion at the center and the escape portions at both ends. It is preferable that the radius of curvature of the arc portion is set to a value that allows the inclination of the leg axis of about 2 to 3 °. In addition, a plurality of rolling elements can be arranged between the support ring and the roller to make the support ring and the roller relatively rotatable,
A needle roller can be used as the rolling element. Further, the outer peripheral surface of the roller may be formed in a spherical shape (true spherical surface or torus surface), and the spherical outer peripheral surface of the roller may be in angular contact with the roller guide surface of the outer joint member. By making angular contact between the roller and the roller guide surface, the roller is less likely to oscillate and its posture is further stabilized, so that when the roller moves in the axial direction of the outer joint member, the roller smoothly moves on the roller guide surface with less resistance. To roll. As a specific configuration for realizing such an angular contact, a cross-sectional shape of the roller guide surface may be a tapered shape or a gothic arch shape.

On the other hand, in the case of the constant velocity universal joint having the above configuration, the contact surface pressure of the contact portion between the outer peripheral surface of the leg shaft and the inner peripheral surface of the support ring becomes higher than in other configurations, and the outer peripheral surface of the leg shaft is increased. Rolling fatigue life tends to decrease. Further, stress concentration tends to occur at the base end of the leg shaft as compared with other configurations, and the fatigue strength of the base end tends to decrease. Therefore, as described above, the softening resistance characteristic value R of the outer peripheral surface and the base end surface of the leg shaft is regulated to a predetermined range, the rolling fatigue life of the outer peripheral surface is increased, and the torsional fatigue strength of the base end is improved. Is particularly useful in a constant velocity universal joint having this configuration.

The roller mechanism of the constant velocity universal joint according to the present invention includes a roller guided on a roller guide surface, and a support ring which is fitted on the outer peripheral surface of the leg shaft and rotatably supports the roller. The outer peripheral surface of the leg shaft is convex spherical, and the inner peripheral surface of the support ring is cylindrical or conical. In this configuration, the roller assembly including the roller and the support ring swings as a unit with respect to the leg axis.

Further, as a roller mechanism of the constant velocity universal joint of the present invention, an outer roller guided by a roller guide surface, and an inner roller rotatably supported by a leg shaft and fitted to an inner peripheral surface of the outer roller. The outer peripheral surface of the inner roller is convex spherical, and the inner peripheral surface of the outer roller is shaped to generate a load component directed toward the tip of the leg shaft at the position of contact with the outer peripheral surface of the inner roller. Can be adopted. In this configuration, the outer roller swings about the leg axis. Here, the neck swing means that the axis of the outer roller is inclined with respect to the axis of the leg axis in a plane including the axis of the leg axis.

More specifically, various shapes shown in Japanese Patent Application Laid-Open No. 9-14280 by the present applicant can be adopted as the shape of the inner peripheral surface of the outer roller. That is,
As the shape of the inner peripheral surface of the outer roller, a cone having a diameter gradually reduced toward the distal end of the leg shaft, and a point offset to the proximal end side of the leg shaft with respect to the center line of the outer peripheral surface of the leg shaft with respect to the generating line center. A concave spherical surface (Japanese Patent Application Laid-Open No. 9-14280, shape in FIG. 3), a convex spherical surface having a point offset to the distal end side of the leg axis with respect to the generatrix center of the outer peripheral surface of the leg axis (Japanese Patent Application Laid-Open No. 9-14280)
No. 4, the shape of FIG. 4), a combined surface of a conical tapered surface and a convex spherical surface whose diameter is reduced toward the tip end side of the leg shaft (JP-A-9-14280)
Various shapes can be employed, such as the shape shown in FIG. 5 and the combined surface of a cylindrical surface and a convex spherical surface (Japanese Patent Application Laid-Open No. 9-14280, the shape shown in FIG. 6). However, from the viewpoint of simplifying the manufacturing process, it is preferable that the inner peripheral surface of the outer roller has a conical shape whose diameter gradually decreases toward the tip of the leg shaft. In this case, setting the inclination angle of the inner peripheral surface of the support to a value within the range of 0.1 ° to 3 °, preferably 0.1 ° to 1 ° effectively reduces the induced thrust and stabilizes the thrust. It is desirable from the viewpoint of conversion.

In the above construction, minute concave portions may be formed at random on contact surfaces such as the outer peripheral surface of the leg shaft and the roller guide surface. The minute recesses formed in the contact surface serve as oil reservoirs and promote the formation of an oil film on the contact surface, so that lubricity is improved and rolling contact fatigue life of the contact surface is improved. The minute concave portion is, for example, about several tens μm in size and about 1 μm in depth. By changing the polishing conditions for the contact surface, it is possible to form minute recesses of any size, depth, and number. When it is difficult to selectively form the minute concave portion only on the contact surface, the minute concave portion may be formed including the peripheral portion of the contact surface of the component or on the entire surface.

Further, a solid lubricating film having a chemical conversion film as a base layer may be formed on the contact surface such as the outer peripheral surface of the leg shaft and the roller guide surface. The solid lubricating coating reduces the frictional resistance of the contact surface and improves the lubricity, so that the rolling contact fatigue life of the contact surface is improved. The chemical conversion coating serving as an underlayer is formed for the purpose of increasing the adhesion of the solid lubricating coating to the contact surface. Examples of the chemical conversion coating include a manganese phosphate coating, an iron phosphate coating, and a zinc phosphate coating. Further, examples of the solid lubricating film include a molybdenum disulfide film, a PTFE film, and the like. Since the surface roughness of the contact surface (base material surface) before the treatment affects the effect after the treatment, the surface roughness of the contact surface is set to Ra 0.2 to Ra so that an appropriate oil sump action can be obtained. 0.8
It is desirable to finish. When it is difficult to selectively perform the coating treatment only on the contact surface, the coating treatment may be performed on the entire surface including the peripheral portion of the contact surface of the component.

Further, the contact surface such as the outer peripheral surface of the leg shaft and the roller guide surface may be subjected to room-temperature sulfurizing treatment. The sulfurization treatment is
This is a surface treatment method in which sulfur penetrates into the surface of steel to generate iron sulfide. By performing the sulfurizing treatment, the friction resistance of the surface is reduced, so that the initial conformability is improved, the rolling fatigue life is improved, and the NVH characteristics are also stabilized. Also,
According to the normal temperature sulfurizing treatment, for example, 30 to 40 ° C. × 10
Since the treatment is performed for 30 minutes, the hardness of the surface hardened layer does not decrease. Since the surface roughness of the contact surface before the treatment affects the effect after the treatment, the surface roughness of the contact surface is finished to Ra 0.2 to 0.8 so that the action of the appropriate oil sump can be obtained. It is desirable to keep.

[0032]

Embodiments of the present invention will be described below.

FIG. 1 and FIG. 2 show a first embodiment of the present invention. FIG. 1A shows a cross section of the joint,
1 (B) shows a cross section perpendicular to the leg axis, FIG. 1 (C) shows a cross section of the support ring, and FIG. 2 shows a longitudinal cross section of the joint at an operating angle (θ).

As shown in FIG. 1, the constant velocity universal joint mainly comprises an outer joint member 10 and a tripod member 20. One of two shafts to be connected is connected to the outer joint member 10, and the other is a tripod member. 20.

The outer joint member 10 has three track grooves 12 extending in the axial direction on the inner peripheral portion. The roller guide surfaces 1 are respectively provided on circumferentially opposite side walls of each track groove 12.
4 are formed. The tripod member 20 has three radially protruding leg shafts 22, and a roller 34 is mounted on each leg shaft 22, and the rollers 34 are housed in the track grooves 12 of the outer joint member 10. . The outer peripheral surface 34 a of the roller 34 is a convex curved surface that matches the roller guide surface 14.

Here, the outer peripheral surface 34a of the roller 34 is a convex curved surface having an arc having a center of curvature at a position radially away from the axis of the leg shaft 22 as a generating line.
Has a gothic arch shape, whereby the outer peripheral surface 34a of the roller 34 and the roller guide surface 14 form an angular contact. In FIG. 1A, two contact positions are indicated by alternate long and short dash lines. Even if the cross-sectional shape of the roller guide surface 14 is tapered with respect to the outer peripheral surface of the spherical roller, angular contact between the two can be realized. By adopting a configuration in which the outer peripheral surface 34a of the roller 34 and the roller guide surface 14 form an angular contact, the roller is less likely to oscillate, and the posture is stabilized. When the angular contact is not used, for example, the roller guide surface 14 is formed by a part of a cylindrical surface whose axis is parallel to the axis of the outer joint member 10, and its cross-sectional shape is formed by a bus bar of the outer peripheral surface 34 a of the roller 34. May be an arc corresponding to.

A support ring 32 is attached to the outer peripheral surface 22a of the leg shaft 22.
Is fitted outside. The support ring 32 and the roller 34 are assembled (unitized) via a plurality of needle rollers 36 to form a roller assembly that can rotate relatively. That is, the cylindrical outer peripheral surface of the support ring 32 is defined as an inner raceway surface, and the cylindrical inner peripheral surface of the roller 34 is defined as an outer raceway surface.
Intersect freely to roll. As shown in FIG.
The needle roller 36 is incorporated in a so-called full roller state without a retainer, in which as many rollers as possible are inserted. Reference numerals 33 and 35 denote a pair of washers mounted in an annular groove formed in the inner peripheral surface of the roller 34 to prevent the needle roller 36 from falling off.

The outer peripheral surface 22a of the leg shaft 22 has a longitudinal section {FIG.
(A)} has a straight shape parallel to the axis of the leg shaft 22, and a cross section {FIG. 1 (B)} has an elliptical shape whose major axis is orthogonal to the axis of the joint. The cross-sectional shape of the leg shaft is
The thickness of the tripod member 20 as viewed in the axial direction is reduced, and the tripod member 20 has a substantially elliptical shape. In other words, the cross-sectional shape of the leg shaft is
The surfaces of the tripod members facing each other in the axial direction are retracted in the mutual direction, that is, on the smaller diameter side than the virtual cylindrical surface.

The inner peripheral surface 32c of the support ring 32 has an arc-shaped convex cross section. That is, the generatrix of the inner peripheral surface 32c has the radius r
{FIG. 1 (C)}. This and the leg shaft 22
Has a substantially elliptical cross section as described above,
Since a predetermined clearance is provided between the support ring 32 and the support ring 32, the support ring 32 can not only move in the axial direction of the leg shaft 22, but also swing with respect to the leg shaft 22. It is free. Further, since the support ring 32 and the roller 34 are relatively rotatably assembled (unitized) via the needle roller 36 as described above, the leg shaft 22
On the other hand, the support ring 32 and the roller 34 are in a relationship in which they can swing as a unit. Here, the swing means that the axes of the support ring 32 and the roller 34 are inclined with respect to the axis of the leg shaft 22 in a plane including the axis of the leg shaft 22 (see FIG. 2).

In the case of this type of conventional joint, since the outer peripheral surface of the leg shaft is in contact with the inner peripheral surface of the support ring over the entire circumference, the contact ellipse has a horizontally elongated shape extending in the circumferential direction. for that reason,
When the leg axle is inclined with respect to the outer joint member, a frictional moment is generated which acts to incline the support ring and thus the roller with the movement of the axle. On the other hand, in the embodiment shown in FIG. 1, the cross section of the leg shaft 22 is substantially elliptical, and the cross section of the inner peripheral surface 32c of the support ring 32 is an arc-shaped convex cross section. As shown by the broken line in C),
The contact ellipse of both becomes close to a point, and at the same time the area becomes smaller. Therefore, the roller assembly (32, 3
4, 36) is greatly reduced as compared with the conventional one, and the posture stability of the roller 34 is further improved.

In the above configuration, the tripod member 20 is formed from a steel material having a carbon content of 0.15 to 0.40 wt% by forging, machining, carburizing, quenching and tempering, and grinding the outer peripheral surface 22a of the leg shaft 22. It is manufactured through
Softening characteristic resistance value R based on outer peripheral surface 22a of leg shaft 22 and other surfaces in tripod member 20 after completion
705 <R ≦ 820, preferably 710 ≦ R ≦ 81
It is regulated within the range of 0. Therefore, the tripod member 20 has a long rolling fatigue life of the outer peripheral surface 22a of the leg shaft 22, a high torsional fatigue strength of the base end of the leg shaft 22 and the serration portion (or spline portion), and excellent durability. And has strength.

It should be noted that the use of carbonitriding and quenching and tempering instead of carburizing and quenching and tempering in the above process is more effective in improving rolling fatigue life, torsional fatigue strength and the like.

Further, the amount of residual austenite in the surface layer formed by carburizing and quenching and tempering (carburized layer) or the surface layer formed by carbonitriding and quenching and tempering (carbonitrided layer) is properly adjusted within the range of 20 to 40 vol%. This improves the surface crack sensitivity and further increases the rolling fatigue life.

Alternatively, the tripod member 20 is forged from a steel material having a carbon content of 0.45 to 0.60 wt%.
Machining → induction hardening and tempering → outer peripheral surface 22 of leg shaft 22
It can also be manufactured through the main process of grinding process a. In this case, the softening characteristic resistance value R of the completed tripod member 20 based on the outer peripheral surface 22a of the leg shaft 22 and other surfaces is 630 <R ≦ 820, preferably 64.
It is restricted within the range of 0 ≦ R ≦ 810. Therefore, the tripod member 20 has a long rolling fatigue life of the outer peripheral surface 22a of the leg shaft 22, a high torsional fatigue strength of the base end of the leg shaft 22 and the serration portion (or spline portion), and excellent durability. And has strength. The induction quenching and tempering may be performed over the entire outer periphery 22a of the leg shaft 22 and the entire periphery of the base end, or may be performed on a plane including the axis of the leg shaft 22 and orthogonal to the axis of the tripod member 20. May be locally performed only in a peripheral area centered at. In the case of carburizing and quenching and tempering and carbonitriding and quenching and tempering, such local treatment can be performed by performing carbon prevention and nitrification prevention.

The outer joint member 10 has a carbon content of 0.15 to 0.15.
It is manufactured from a 0.40 wt% steel material through a main process of forging, machining, carburizing, quenching and tempering, and grinding of the shaft portion 10a (see FIG. 2A). Instead of carburizing and quenching and tempering, carbonitriding and quenching and tempering or induction quenching and tempering may be employed. Since the regulation of the softening resistance characteristic value R and other matters conform to those of the tripod member 20, repeated description is omitted.

Further, on the outer peripheral surface 22a of the leg shaft 22 of the tripod member 20 and the roller guide surface 14 of the outer joint member 10, a solid lubricating film having the above-mentioned minute concave portion and the chemical conversion coating film as a base layer may be formed. good. Further, a normal temperature sulfurizing treatment may be performed.

Further, after the above-described main steps, at least one of the outer peripheral surface 22a, the base end, and the serration (or spline) of the leg shaft 22 of the tripod member 20, the roller guide of the outer joint member 10 is provided. Surface 14 and shaft 10a (especially serration or spline)
May be subjected to a shot peening process. By performing the shot peening treatment, the surface texture is refined and residual compressive stress is generated on the surface. Therefore, the rolling fatigue life is improved, and the strength against torsional fatigue and the like is improved. When a carburized layer or a carbonitrided layer is formed, the retained austenite in the surface layer undergoes martensitic transformation due to the high collision energy of shot particles. As a result, the residual compressive stress further increases, and at the same time, fine dimples are formed on the surface to form an oil reservoir, which is more effective in improving wear resistance, rolling fatigue life and torsional fatigue strength. In particular, the tendency is remarkable in a carbonitrided layer having a large amount of retained austenite.

In the constant velocity universal joint of this embodiment, the material of the tripod member 20 and the outer joint member 10 and the properties of the surface and the lower layer thereof are optimized, and the rolling fatigue life and strength against torsional fatigue and the like are improved. As a result, it has superior durability and strength as compared with the current constant velocity universal joint of the same size. Further, it is possible to further reduce the size while securing durability and strength equal to or higher than the current product.

FIGS. 3 and 4 show a second embodiment of the present invention. In the second embodiment, the generatrix of the inner peripheral surface 32c of the support ring 32 is formed by a single arc in the first embodiment, whereas the center arc 32a It differs only in that it is formed in combination with the escape portions 32b on both sides. The escape portion 32b is shown in FIG.
This is a portion for avoiding interference with the leg shaft 22 when the operating angle (θ) is taken as shown in (C), and the diameter gradually increases from the end of the arc portion 32 a toward the end of the support ring 32. Consist of straight lines or curves. Here, an example is shown in which the relief portion 32b is a part of a conical surface having a cone angle α = 50 °. The circular arc portion 32a is connected to the leg shaft 22 with respect to the support ring 32.
For example, 30 m
The radius of curvature (r) is as large as about m. In the tripod-type constant velocity universal joint, the tripod member 20 swings about the center of the outer joint member 10 three times when the outer joint member 10 makes one rotation. At this time, the amount of eccentricity represented by the symbol e {FIG. 2 (A)} increases in proportion to the operating angle (θ).
Then, the three leg shafts 22 are separated from each other by 120 °, but when the operating angle (θ) is taken, as shown in FIG.
Considering the vertical leg shaft 22 shown at the top of the figure as a basis, the other two leg shafts 22 are slightly inclined from their axes at the operating angle 0 shown by the dashed line. The inclination is about 2 to 3 ° when the operating angle (θ) is, for example, about 23 °. Since this inclination is naturally allowed by the curvature of the circular arc portion 32a of the inner peripheral surface 32c of the support ring 32, it is possible to prevent the surface pressure at the contact portion between the leg shaft 22 and the support ring 32 from becoming excessively high. it can. FIG. 2 (B)
3A schematically illustrates three leg shafts 22 of the tripod member 20 viewed from the left side surface of FIG. 2A, and a solid line indicates the leg shaft.

Also in this embodiment, the tripod member 20 and the outer joint member 10 are optimized in their material, surface and lower layer properties, and are improved in rolling fatigue life and strength against torsional fatigue and the like. ing. Therefore, the constant velocity universal joint of this embodiment has excellent durability and strength as compared with the current constant velocity universal joint of the same size. Also,
It is possible to achieve more compactness while securing durability and strength equal to or higher than the current product.

FIGS. 5 and 6 show a third embodiment of the present invention. FIG. 5 shows that the operating angle of the joint is 0 °,
In addition, it shows a state when no rotational torque is applied to the joint.

The tripod type constant velocity universal joint of this embodiment has an outer joint member 1 connected to one of two shafts to be connected.
And a tripod member 2 coupled to the other.

The outer joint member 1 has a substantially cup-like appearance, and three track grooves 1a extending in the axial direction are formed at equal circumferential positions on the inner peripheral portion. Roller guide surfaces 1a1 are provided on both sides of each track groove 1a.

The tripod member 2 has a radially projecting 3
The leg shafts 2a are provided at equally circumferential positions. The outer peripheral surface 2a1 of each leg shaft 2a is formed in a convex spherical shape.
A roller assembly A in which a support ring 3, a plurality of needle rollers 4, and a roller 5 are assembled is mounted.

As shown in an enlarged manner in FIG. 5B, the roller assembly A has a cylindrical outer peripheral surface 3 a of the support ring 3.
A plurality of needle rollers 4 are rotatably interposed between the inner peripheral surface 5 a of the roller 5 and the inner peripheral surface 5 a of the roller 5.
The two ends of the support ring 3 and the needle roller 4 are locked by a pair of snap rings 6 fitted on the support ring 3, and the support ring 3 and the needle roller 4 move in the axial direction with respect to the roller 5 (in the direction of the axis Z of the leg shaft 2 a in the axial direction Z). Movement). There is a slight axial gap δ between both end faces of the support ring 3 and both end faces of the needle roller 4 and the pair of snap support rings 6. In the drawing, the size of the axial gap δ is considerably exaggerated from the actual size. Further, the end face of the support ring 3 and the snap support ring 6
And the axial gap between the end face of the needle roller 4 and the snap support ring 6 may be set to the same value or different values depending on the design. In the drawing, the two cases are shown as the axial gap δ without distinction. Further, there is a slight radial gap between the outer peripheral surface 3 a of the support ring 3 and the inner peripheral surface 5 a of the roller 5 and the rolling surface of the needle roller 4.

The inner peripheral surface 3b of the support ring 3 is fitted to the spherical outer peripheral surface 2a1 of the leg shaft 2a. In this embodiment, the inner peripheral surface 3b of the support ring 3 has a conical shape whose diameter gradually decreases toward the distal end of the leg shaft 2a, and the outer peripheral surface 2a1 of the leg shaft 2a.
Line contact with This allows the roller assembly A to swing with respect to the leg shaft 2a. Support ring 3
Of the inner peripheral surface 3b is as small as, for example, 0.1 ° to 3 °, preferably 0.1 ° to 1 °. In this embodiment, α = 0.5 ° is set. I have. In the drawing, the degree of inclination of the inner peripheral surface 3b is exaggerated.

The generatrix of the outer peripheral surface 5b of the roller 5 is
Is an arc centered on a point offset outward from the center of the circle.

In this embodiment, the cross-sectional shape of the roller guide surface 1a1 of the outer joint member 1 is a two-arc (gothic arch). Therefore, the roller guide surface 1a
1 and the outer peripheral surface 5b of the roller 5 make angular contact at two points p and q. The angular contact points p and q include the center of the outer peripheral surface 5b of the roller 5 and are located at the opposite sides of the center line orthogonal to the axis Z of the leg shaft 2a by the same distance in the axis Z direction. Incidentally, the cross-sectional shape of the roller guide surface 1a1 may be V-shaped or parabolic. Also, in this embodiment, the roller guide surface 1 is provided in the track groove 1a.
a1 is provided in the vicinity of the shoulder surface 1a2.
Thus, the end surface 5c of the roller 5 on the tip end side of the leg shaft is guided.

Since the inner peripheral surface 3b of the support ring 3 has a conical shape whose diameter gradually decreases toward the tip of the leg shaft, when a rotational torque is applied to this joint, as shown in FIG. The degree of inclination of the peripheral surface 3b is exaggerated more than in FIG. 5), and the contact position S between the inner peripheral surface 3b of the support ring 3 and the outer peripheral surface 2a1 of the leg shaft 2a is directed toward the tip of the leg shaft. The generated load component F is generated. This load component F acts to push up the support ring 3 and the needle roller 4 toward the tip end of the leg shaft, so that the support ring 3 and the needle roller 4 are pressed against the washer 6 on the tip end of the leg shaft. Therefore, the inner peripheral surface 3b of the support ring 3 and the outer peripheral surface 2a of the leg shaft 2a
The contact position S with 1 is stabilized. Also, this load component F
Acts to push up the roller 5 toward the tip end of the leg shaft via the support ring 3 and the needle roller 4, thereby stabilizing the attitude of the roller 5 with respect to the roller guide surface 1a1.
Such stabilization of the contact position S and stabilization of the attitude of the roller 5 effectively reduce and stabilize the induced thrust. Note that the inner peripheral surface 3b of the support ring 3 may be cylindrical.

As in the first and second embodiments, the tripod member 2 and the outer joint member 1 have their materials, surface and lower layer properties optimized to improve the rolling fatigue life and torsional fatigue. Is improved. for that reason,
The constant velocity universal joint of the third embodiment has superior durability and strength as compared with the current constant velocity universal joint of the same size.
In addition, while ensuring durability and strength equal to or higher than the current product,
It is possible to achieve more compactness.

FIG. 7 shows a fourth embodiment of the present invention. FIG. 7 shows a state when the operating angle of the joint is 0 °.

As shown in FIG. 7, the constant velocity universal joint of this embodiment comprises an outer joint member 1 'connected to one of the two shafts to be connected and a tripod member 2' connected to the other. ing. The outer joint member 1 'has a generally cup-shaped appearance, and three track grooves 1a' extending in the axial direction are formed at circumferentially equal positions on the inner peripheral portion. Each track groove 1a '
Are provided with roller guide surfaces 1a'1 on both sides. The tripod member 2 'has three leg shafts 2a' protruding in the radial direction at circumferentially equidistant positions. An inner roller 3 'is rotatably fitted to the cylindrical outer peripheral surface of each leg shaft 2a' via a plurality of needle rollers 7 ', and an outer roller 4' is rotatably fitted to the outside thereof. ing.

As shown in FIG. 7B in an enlarged manner, the needle roller 7 'and the inner roller 3' are provided with a retaining ring 8 'and a retaining ring, one end of which is attached to the tip of the leg shaft 2a'. 9 ', and the other end is locked by a washer 10' attached to the base end of the leg shaft 2a ', thereby restricting the movement of the leg shaft 2a' in the axis Z direction. In practice, there is a slight axial gap δ ′ between the needle roller 7 ′ and the inner roller 3 ′ and the retaining ring 8 ′ and the washer 10 ′. In the drawing, the size of the axial gap δ ′ is greatly exaggerated than it actually is. There is a slight radial gap between the outer peripheral surface of the leg shaft 2a 'and the inner peripheral surface 3a' of the inner roller 3 'and the needle roller 7'. The inner peripheral surface 3a 'of the inner roller 3' is cylindrical,
The outer peripheral surface 3b 'has a convex spherical shape. In this embodiment,
The generatrix of the outer peripheral surface 3b 'is the radial center O of the inner roller 3'.
This is an arc having a radius r1 centered on a point O1 ′ offset outward by a predetermined amount from 2 ′. The radius r1 is smaller than the maximum radius r2 of the outer peripheral surface 3b '.

The outer roller 4 'is fitted on the outer peripheral surface 3b' of the inner roller 3 '. In this embodiment, the inner peripheral surface 4a 'of the outer roller 4' has a conical shape whose diameter gradually decreases toward the tip end of the leg shaft 2a ', and the outer peripheral surface 3a of the inner roller 3'.
Line contact with b '. Thereby, swinging swing of the outer roller 4 'with respect to the leg shaft 2a' is permitted. Inner peripheral surface 4a '
Is slightly as 0.1 ° to 3 °, for example.
In this embodiment, it is set to 0.3 ° to 0.7 °.
In the drawing, the inclination of the inner peripheral surface 4a 'is considerably exaggerated. The generatrix of the outer peripheral surface 4b 'of the outer roller 4' is a point O1 '
This is an arc having a radius r3 centered at a point O3 ′ offset further outside.

In this embodiment, the outer joint member 1 '
The cross-sectional shape of the roller guide surface 1a'1 has a two-arc shape (gothic arch shape). Therefore, the roller guide surface 1a'1 and the outer peripheral surface 4b 'of the outer roller 4' make angular contact at two points p 'and q'. The angular contact points p 'and q' are located on the outer peripheral surface 4 of the outer roller 4 '.
It is located at a position that includes the center O3 ′ of b ′ and is at the same distance away from the center line orthogonal to the axis Z of the leg shaft 2a ′ by the same distance in the axis Z direction. Incidentally, the cross-sectional shape of the roller guide surface 1a'1 may be V-shaped or parabolic.

Since the inner peripheral surface 4a 'of the outer roller 4' has a conical shape whose diameter gradually decreases toward the tip of the leg shaft, as shown in FIG. 7C, the outer peripheral surface of the inner roller 3 ' 3b '
A load component F directed toward the tip of the leg shaft is generated at a contact position S ′ with the shaft. The load component F acts to push up the outer roller 4 ′ toward the tip of the leg shaft, and reduces the contact surface pressure of the portion B on the non-load side roller guide surface 1 a ′ 1. Also,
At the contact position S ', a force directed toward the base end of the leg shaft (downward in the figure) is generated as a reaction force of the load component F. This reaction force acts to push down the inner roller 3 ′ to the base end side of the leg shaft, and the leg shaft 2 of the inner roller 3 ′ and the needle roller 7 ′.
Axial movement with respect to a ′ is suppressed. As a result, FIG.
As shown in (B), the inner roller 3 ′ and the needle roller 7 ′ are pressed against the lower washer 10 ′, and the fluctuation of the contact position S ′ due to the axial gap δ ′ is suppressed. The reduction of the contact surface pressure of the portion B on the roller guide surface 1a'1 on the non-load side and the contact position S '
In combination with the stabilization, the induced thrust is effectively reduced and stabilized. The inner peripheral surface 4 of the outer roller 4 '
a ′ may be cylindrical.

The tripod member 2 'and the outer joint member 1'
In the same manner as in the first, second and third embodiments, the properties of the materials, surfaces and lower layers thereof are optimized, and the rolling fatigue life is improved and the strength against torsional fatigue and the like is improved. I have. Therefore, the constant velocity universal joint of the fourth embodiment has superior durability and strength as compared with the current constant velocity universal joint of the same size. Further, it is possible to further reduce the size while securing durability and strength equal to or higher than the current product.

The present invention is not limited to the constant velocity universal joint having the above-described configuration. For example, the roller guide surface may be flat, the outer surface of the outer roller may be cylindrical, the inner surface may be concave, and the inner roller may be concave. The outer peripheral surface of the outer roller is a convex sphere, and the slip between the concave spherical inner peripheral surface of the outer roller and the convex spherical outer peripheral surface of the inner roller,
Constant velocity universal joints (Japanese Patent Application Nos. 8-4073 and 8-138335) that allow the outer roller to swing freely and swing the roller guide surface and the axis of the leg shaft at an angle of 0 °. Constant velocity universal joints which are not parallel to each other in the state
No. 779).

[0069]

EXAMPLES Tables 1 and 2 show the results of tests performed on tripod members of the constant velocity universal joint according to the first embodiment.

[0070]

[Table 1]

[0071]

[Table 2]

First, tripod members were formed using steel materials having various main component contents (samples No. 1 to No. 1).
7) After carburizing and quenching at 950 ° C for 8 hours, 200 °
After tempering for C × 2 hours, the softening characteristic resistance value R (the maximum Vickers hardness Hv in a region within a depth of 0.5 mm from the outer peripheral surface) of the outer peripheral surface of the leg shaft was actually measured. Table 1 shows the results. In addition, after carburizing, quenching and tempering,
Grinding has been performed, and the above “depth 0.5 mm” is based on the surface after the grinding. Next, the durability and the forgeability of each sample were evaluated. Table 2 shows the relationship between the evaluation of the six types of samples and the measured and estimated values of the softening resistance characteristic value R (Hv) (estimated values will be described later). In the evaluation items, ◎ indicates that the target characteristics were sufficiently satisfied, ○ indicates that the target characteristics were satisfied, and Δ indicates that the target characteristics were not satisfied.

From the results shown in Table 2, in the case of the carburized, quenched and tempered product, the durability and forging process were performed by regulating the softening characteristic resistance value R within the range of 705 <R ≦ 820, preferably 710 ≦ R ≦ 815. It was confirmed that satisfactory results were obtained for both sexes. If the softening characteristic resistance value R is 705 or less, favorable results cannot be obtained in terms of durability, and if the softening characteristic resistance value R exceeds 820, favorable results cannot be obtained in terms of forgeability.

On the other hand, the carbon content of the base material that affects the hardness of the core is 0.15 to 0.40 from the viewpoint of securing the fatigue strength.
It is preferably within the range of wt%. If the carbon content of the base material is lower than 0.15% by weight, the time required for carburizing is prolonged, and at the same time, the hardness of the core is insufficient and satisfactory fatigue strength cannot be obtained. Conversely, when the carbon content is 0.1.
If the content is more than 4 wt%, the hardness of the core portion is unnecessarily increased, and the toughness is significantly reduced, and at the same time, the strain is increased.

As described above, when the components such as the trunnion member and the outer joint member are carburized, quenched and tempered, these components are formed of steel having a carbon content of 0.15 to 0.40 wt%, and the softening resistance is reduced. When the characteristic value R is 705 <R ≦ 82
It is desirable to limit the range to 0, preferably 710 ≦ R ≦ 815, whereby the rolling fatigue life, the fatigue strength, and the like can be increased, the durability can be improved, and at the same time, the forgeability can be ensured. Further, by regulating the softening resistance characteristic value R to the above range, the hardenability of the material is improved,
Since deep baking can be performed more than before, it is more effective in improving fatigue strength and the like.

The above-described softening resistance characteristic value R may be obtained by actual measurement, but can be estimated relatively accurately using the regression equation (a) shown below. R (estimated value) = 713.4 + {20.7 × Si (%)} + {12.3 × Mn (%)} + {6.4 × Ni (%)} − {14.8 × Cr (%)} + {159.0 × Mo (% )} (A) The regression equation (a) represents the softening characteristic resistance values R (actually measured values) of the 17 types of samples (samples No. 1 to No. 17) shown in Table 1 and the main component element content ( (wt%). In this example, Si, Mn, Ni, Cr, and Mo are selected as the main constituent elements, and carbon C is excluded from the variables because the content of each sample becomes uniform by carburization.

As shown in Table 2, the estimated value of the softening characteristic resistance value R obtained by the regression equation (a) closely approximates the actually measured value, and this estimated value R is 705 <R ≦ 820, preferably Is regulated within the range of 710 ≦ R ≦ 815,
Durability and forgeability can be easily and relatively accurately evaluated.

The components such as the trunnion member and the outer joint member may be carbonitrided, quenched and tempered. In this case, the carbon content of the base material and the softening resistance characteristic value R (actual or estimated value) are determined. The same effects as described above can be obtained by restricting in the same manner as in the case of carburizing, quenching and tempering. Further, in the carbonitrided, quenched, and tempered product, the amount of retained austenite in the surface layer (carbonitrided layer) is appropriately increased, and crack sensitivity is improved. Therefore, the rolling fatigue life is more effective. In addition, the surface hardness of the base end portion and the serration portion of the leg shaft is increased, and the torsional fatigue strength and the like are also improved.

When carburizing and quenching and tempering and carbonitriding and quenching and tempering are performed, various steel materials shown in Table 5 can be used in addition to the steel materials shown in Table 1.

[0080]

[Table 5]

Tables 3 and 4 below show the results of other tests performed on the tripod member of the constant velocity universal joint according to the first embodiment. First, tripod members were formed using steel materials having various main component contents (Sample Nos.
No. 18) After induction hardening at 10 KHz × 170 KW × 3 seconds, tempering was performed at 200 ° C. × 2 hours, and the softening characteristic resistance value R of the outer peripheral surface of the leg shaft (0.5 m deep from the outer peripheral surface)
The maximum Vickers hardness Hv) in the area within m was actually measured. Table 3 shows the results. The outer peripheral surface of the leg shaft is subjected to grinding after induction hardening and tempering, and the above “depth 0.5 mm” is based on the surface after the grinding. Next, the durability and the forgeability of each sample were evaluated. Table 4 shows the relationship between the evaluation of the seven types of samples and the actually measured values and the estimated values (the estimated values will be described later) of the softening resistance characteristic value R (Hv). In the evaluation items, ◎ indicates that the target characteristics were sufficiently satisfied, ○ indicates that the target characteristics were satisfied, and Δ indicates that the target characteristics were not satisfied.

[0082]

[Table 3]

[0083]

[Table 4]

From the results shown in Table 4, in the case of the induction hardened and tempered product, the durability and the forging process were performed by regulating the softening characteristic resistance value R within the range of 630 <R ≦ 820, preferably 640 ≦ R ≦ 810. It was confirmed that satisfactory results were obtained for both sexes. Softening characteristic resistance value R is 630
If it is below, a favorable result in terms of durability cannot be obtained,
On the other hand, if the softening characteristic resistance value R exceeds 820, a favorable result cannot be obtained in terms of forgeability.

On the other hand, in order to obtain sufficient surface hardness by induction hardening, the carbon content of the base material is set to 0.45 to 0.6.
It is necessary to be within the range of 0 wt%.

As described above, when components such as the trunnion member and the outer joint member are to be induction hardened and tempered,
These parts are formed of steel having a carbon content of 0.45 to 0.60% by weight, and the softening resistance characteristic value R is 630 <R ≦ 8.
20, preferably within the range of 640 ≦ R ≦ 810, and more preferably within the range of 640 ≦ R ≦ 810, thereby increasing the rolling fatigue life and fatigue strength to improve the durability. At the same time, forgeability can be ensured. In addition, since a residual compressive stress is generated on the surface by the induction quenching and tempering, it is more effective in improving the rolling fatigue life and fatigue strength.

The above-described softening resistance characteristic value R may be obtained by actual measurement, but can be estimated with relatively high accuracy using the following regression equation (b). R (estimated value) = 378.0 + {516.2 × C (%)} + {83.2 × Si (%)} + {31.8 × Mn (%)} + {29.1 × Ni (%)} − {132.6 × Cr (% )} + {167.9 × Mo (%)} (b) The regression equation (b) represents the softening characteristic resistance value R (actual measurement value) of the 18 types of samples (sample Nos. 1 to 18) shown in Table 3. It was obtained by performing multiple regression analysis with the main component element content (%) of each sample. In this example, C, Si, Mn, Ni, Cr, and Mo are selected as main component elements.

As shown in Table 3, the estimated value of the softening characteristic resistance value R obtained by the regression equation (b) closely approximates the actually measured value, and this estimated value R is 630 <R ≦ 820, preferably Is regulated within the range of 640 ≦ R ≦ 810,
Durability and forgeability can be easily and relatively accurately evaluated.

In the case of induction hardening and tempering, various steel materials shown in Table 6 can be used in addition to the steel materials shown in Table 3.

[0090]

[Table 6]

The above is the result of a test performed on the trunnion member. Similar results were obtained for other components such as the outer joint member, the roller, and the support ring. Similar results were obtained for the constant velocity universal joints of the second, third, and fourth embodiments.

[0092]

According to the present invention, the materials of the components, especially the tripod member and the outer joint member, the properties of the surface and the lower layer thereof are optimized, and the strength against rolling fatigue life and torsional fatigue is improved. , Providing tripod type constant velocity universal joints with superior durability and strength while maintaining the current size, and more compact tripod type constant velocity universal while ensuring durability and strength equal to or higher than the current product Fittings can be provided.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, and FIG.
1 is an end view showing a part of the cross section, FIG. 1B is a cross sectional view perpendicular to the leg axis in FIG. 1A, and FIG. 1C is a cross sectional view of a support ring for explaining a contact ellipse. .

2 (A) is a longitudinal sectional view of the constant velocity universal joint shown in FIG. 1 and shows a state where an operating angle is set, and FIG. 2 (B) is a view showing FIG.
It is a typical side view of a tripod member in (A).

FIG. 3 shows a second embodiment of the present invention, and FIG.
FIG. 3B is an end view showing a part of the cross section, FIG. 3B is a cross sectional view perpendicular to the leg axis in FIG. 3A, and FIG.

FIG. 4 is an enlarged sectional view of a support ring in FIG. 3;

5A and 5B show a third embodiment of the present invention. FIG. 5A is an end view showing a part of the cross section, and FIG. 5B is an enlarged cross-sectional view of a main part of FIG. 5A. .

6 is a diagram for explaining a load component F generated at a contact position between a support ring and a leg shaft in FIG. 5;

7A and 7B show a fourth embodiment of the present invention. FIG. 7A is a cross-sectional view, FIG. 7B is an enlarged cross-sectional view of a main part of FIG. 7A, and FIG. FIG. 7 is a diagram for describing a load component F generated at a contact position between an outer roller and an inner roller.

[Explanation of symbols]

 Reference Signs List 10 outer joint member 12 track groove 14 roller guide surface 20 tripod member 22 leg shaft 32 support ring 32a arc portion 32b relief portion 34 roller 36 needle roller

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 24, 2000 (2000.1.2
4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0070

[Correction method] Change

[Correction contents]

[0070]

[Table 1]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0071

[Correction method] Change

[Correction contents]

[0071]

[Table 2]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name]

[Correction method] Change

[Correction contents]

[0082]

[Table 3]

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0083

[Correction method] Change

[Correction contents]

[0083]

[Table 4]

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0080

[Correction method] Change

[Correction contents]

[0080]

[Table 5]

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0090

[Correction method] Change

[Correction contents]

[0090]

[Table 6]

Claims (14)

[Claims] An outer joint member having three axial track grooves formed on an inner peripheral portion thereof and having an axial roller guide surface on both sides of each track groove, and a radially projecting three groove groove.
A tripod member having two leg shafts, and a roller mechanism attached to each leg shaft of the tripod member,
A constant velocity universal joint having a roller that is swingable with respect to the leg shaft and is guided along a direction parallel to an axis of an outer joint member along the roller guide surface; A constant velocity universal joint characterized in that a softening resistance characteristic value (R) of a component is regulated within a predetermined range. 2. The method according to claim 1, wherein the component has a carbon content of 0.15 to 0.15.
It is made of 0.40 wt% steel, has a surface layer formed by carburizing, quenching and tempering just below a predetermined surface, and has a softening resistance characteristic value (R) of 7 in Vickers hardness (Hv).
2. The constant velocity universal joint according to claim 1, wherein 05 <R ≦ 820. 3. The component according to claim 1, wherein said component has a carbon content of 0.15 to 0.15.
It is made of 0.40 wt% steel, has a surface layer formed by carbonitriding, quenching and tempering immediately below a predetermined surface, and the softening resistance characteristic value R is 705 <R ≦ 820 in Vickers hardness (Hv). The constant velocity universal joint according to claim 1, wherein 4. The method according to claim 1, wherein the component has a carbon content of 0.45 to 0.45.
It is made of 0.60 wt% steel, has a surface layer formed by induction hardening and tempering immediately below a predetermined surface, and
The softening resistance characteristic value is 630 in Vickers hardness (Hv).
The constant velocity universal joint according to claim 1, wherein <R ≦ 820. 5. The roller mechanism according to claim 1, wherein the roller mechanism includes a roller guided by the roller guide surface, and a support ring externally fitted to an outer peripheral surface of the leg shaft and rotatably supporting the roller. The inner peripheral surface is an arc-shaped convex cross section, the outer peripheral surface of the leg shaft has a straight shape in a vertical cross section, and contacts the inner peripheral surface of the support ring in a direction orthogonal to the axis of the joint in a transverse cross section, The constant velocity universal joint according to any one of claims 1 to 4, wherein a clearance is formed between the joint and the inner peripheral surface of the support ring in the axial direction of the joint. 6. The constant velocity universal joint according to claim 5, wherein a cross section of the leg shaft has a substantially elliptical shape having a major axis perpendicular to an axis of the joint. 7. The leg shaft includes a roller guided by the roller guide surface, and a support ring that is fitted to an outer peripheral surface of the leg shaft and rotatably supports the roller. 5. The constant velocity universal joint according to claim 1, wherein an outer peripheral surface of the support ring has a convex spherical shape, and an inner peripheral surface of the support ring has a cylindrical or conical shape. 8. The roller mechanism has an outer roller guided by the roller guide surface, and an inner roller rotatably supported by the leg shaft and fitted to an inner peripheral surface of the outer roller. The outer peripheral surface of the inner roller has a convex spherical shape, and the inner peripheral surface of the outer roller is shaped so as to generate a load component directed toward the tip of the leg shaft at the position of contact with the outer peripheral surface of the inner roller. The constant velocity universal joint according to claim 1. 9. The constant velocity universal joint according to claim 8, wherein the inner peripheral surface of the outer roller has a conical shape whose diameter is gradually reduced toward the tip end of the leg shaft. 10. The constant velocity universal joint according to claim 1, wherein the component is a tripod member. 11. The constant velocity universal joint according to claim 1, wherein the component is an outer joint member. 12. The constant velocity universal joint according to claim 1, wherein minute concave portions are formed at random on a predetermined surface of said component. 13. The constant velocity universal joint according to claim 1, wherein a solid lubricating coating having a chemical conversion coating as a base layer is formed on a predetermined surface of the component. 14. The constant velocity universal joint according to claim 1, wherein a predetermined surface of the component part is subjected to a normal temperature sulfurizing treatment.