JP2002235766A - Tripod type constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high service life tripod type constant velocity universal joint capable of surely preventing the fall-off of a tripod member, regardless of the shape of an outside joint member, and realizing the prevention at low cost. SOLUTION: This tripod type constant velocity universal joint is provided with the outside joint member 10 having track grooves 12 on the inner periphery and forming roller guide surfaces 14 on side walls facing each other of each track groove 12, the tripod member 20 having leg shafts 22 projecting radially and rollers 34 which are rotatably mounted on the outer periphery of each leg shaft 22 and are stored within the track grooves 12 of the outside joint member 10. The roller guide surfaces 14 are cured by heat treatment, leaving the vicinity of the opening part of the outside joint member 10, and projecting parts 46 to interfere with rollers 34 are formed by the plastic deformation in an uncured part 44 in the vicinity of the opening part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art For example, in a drive shaft for transmitting rotational power from an automobile engine to wheels, one end thereof is connected to a differential through a sliding type constant velocity universal joint, and the other end is a fixed type constant velocity universal joint. Connected to the wheels via As a sliding type constant velocity universal joint used at one end of a drive shaft, for example, a tripod type constant velocity universal joint is known.

As shown in FIG. 7, this tripod type constant velocity universal joint has a tripod member 20 having three leg shafts 220 protruding in the radial direction on the inner periphery of an outer joint member 100.
0 is accommodated. A roller 340 is rotatably mounted on the outer periphery of each leg shaft 220, and the roller 340 is accommodated in three track grooves 120 formed on the inner periphery of the outer joint member 100.
By axially guiding the roller 340 with the zero roller guide surface 140, axial displacement (plunging) between the two axes on the driving side and the driven side is allowed.

[0004] By the way, for example, in a process of assembling a drive shaft to a vehicle body, there is a case where the drive shaft has to be inclined or made vertical. At this time, if the tripod-type constant velocity universal joint is raised, the tripod member 200 may fall off from the inner periphery of the outer joint member 100 by weight. The clip 500 is attached to the inner periphery of the opening of the opening 100. That is, the circlip 500 is engaged with the circular engagement groove 160 formed on the inner peripheral surface of the outer joint member 100, and the circlip 500 interferes with the roller 340.
00 is prevented.

[0005]

In recent years, a so-called flower-shaped outer joint member, that is, FIG.
As shown in FIG. 10, the use of the outer joint member 100 ′ having a small diameter by narrowing a portion between the adjacent rollers 340 is increasing. However, in this type of flower-shaped outer joint member 100 ′, a circular engagement groove cannot be formed along the inner periphery 120 of the large-diameter portion 190.

FIG. 8 shows a countermeasure against the slippage in this case.
As shown in FIG. 9, an arc-shaped engagement groove 160 is formed on the inner periphery of each small diameter portion 180, and an annular circlip 500 is fitted into this engagement groove 160. As shown in FIG. The clip 500 is fitted into the engagement groove 160 on the inner periphery of the small diameter portion 180 and the circlip 500 is connected to the outer joint member 10.
0, or a straight shape that smoothly connects the engaging groove 160 of the small diameter portion 180 to the inner periphery of the large diameter portion 190, as shown in FIG. Insert the circlip 500 into the engagement groove 160
, And an arc portion 520 corresponding to the inner periphery of the large-diameter portion 190 are known.

However, in the countermeasure shown in FIG. 8, the circlip 500 moves the roller 340 in the axial direction of the leg shaft 220.
Since it interferes with the roller 340 in the vicinity of the center of curvature of the outer periphery, the allowable plunging amount between the two axes becomes smaller than that in the structure of FIG. There is a problem that. Further, in the retaining structure of FIG. 9, the molding cost of the deformed clip 500 increases, and the circlip 500 interferes with the roller 340 near the center of curvature of the roller 340 as described above.
The axial dimension of the outer joint member 100 becomes longer. Further, in the structure shown in FIG.
Since 0 is an irregular shape, there is a problem that these processing costs and processing steps are increased.

Therefore, the present invention provides a tripod type having a long life which can reliably prevent the tripod member from coming off without being influenced by the shape of the outer joint member such as a cylindrical type or a flower type, and can realize this at low cost. The purpose is to provide constant velocity universal joints.

[0009]

In order to achieve the above object,
In the present invention, the inner circumference has three track grooves in the axial direction,
An outer joint member having roller guide surfaces formed on opposing side walls of each track groove, a tripod member having three leg shafts protruding in the radial direction, and rotating through a plurality of needle rollers on an outer periphery of each leg shaft. A tripod-type constant velocity universal joint that is freely mounted and includes a roller housed in a track groove of the outer joint member, and guides the roller by a roller guide surface. The remaining portion was cured by heat treatment, and a protruding portion capable of interfering with the roller was formed in the uncured portion near the opening by plastic deformation.

In the tripod type constant velocity universal joint, since the roller transmits torque while rolling on the roller guide surface in the axial direction, the roller guide surface is required to have a long rolling fatigue life. When the roller guide surface is hardened by the heat treatment as described above, the rolling fatigue life can be increased, and the joint life and torque capacity can be increased.

If a protrusion is formed on the roller guide surface near the opening of the outer joint member by plastic deformation so as to be able to interfere with the roller, the roller interferes with the protrusion when the roller moves to the vicinity of the opening of the outer joint member. Therefore, further movement to the opening side is restricted, and the tripod member is prevented from coming off.
This protrusion can be easily and inexpensively formed by plastically deforming the roller guide surface by caulking or the like. Since the plastic deformation of the roller guide surface can be performed irrespective of the inner peripheral shape of the outer joint member, a good retaining effect can be obtained regardless of the outer shape (cylindrical or flower shape) of the outer joint member.

Although the roller guide surface is hardened by the heat treatment as described above, if the hardening process is also performed on the portion where the protrusion is formed, there is a concern that the base material may be cracked at the time of plastic deformation due to insufficient ductility. In this case, by performing heat treatment except for the vicinity of the opening of the outer joint member, an uncured portion having a lower hardness and a higher ductility than the hardened roller guide surface is formed near the opening, and this uncured portion is plastically deformed. If the projection is formed by deformation, it is possible to avoid base material cracking due to plastic deformation. In order to reliably prevent base material cracking, the surface hardness of the uncured portion is desirably set to a Rockwell hardness (C scale test: the same applies hereinafter) of HRc 40 or less.

It is desirable that at least one projecting portion is formed in each track groove so that a reliable retaining effect can be obtained even when an operating angle is set between the two shafts.

As the heat treatment of the roller guide surface, various hardening treatments can be applied. Among them, induction quenching is particularly advantageous in that local heating can be performed, the depth of the hardened layer can be freely selected, and the performance of the base material can be maintained because it can be controlled so as not to significantly affect the heat other than the hardened layer. Having. Therefore, it is suitable as a heat treatment method for curing the roller guide surface except for the vicinity of the opening of the outer joint member as described above.

In the tripod type constant velocity universal joint, the gap between the roller and the roller guide surface, that is, the difference between the roller diameter and the distance between the opposing guide surfaces is approximately 0.2.
mm. Therefore, if the protrusion width of the protrusion to the leg shaft inner diameter side is set to 0.5 mm or more, the protrusion can be surely interfered with the roller.

A drive shaft using a tripod type constant velocity universal joint is composed of a tripod type constant velocity universal joint, a fixed type constant velocity universal joint, and a shaft interposed between the two joints. In this drive shaft, when the tripod type constant velocity universal joint is placed on the upper side, the weight of the shaft and the fixed type constant velocity universal joint acts on the tripod member in addition to its own weight as a force in the direction of coming off from the outer joint member. Since the pulling force at this time is 490 N or less, the protrusion is 490 N in order to reliably prevent the tripod member from coming off.
It is desirable to have the above pull-out strength.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Explanation will be given based on FIG.

As shown in FIGS. 1 and 2, the tripod type constant velocity universal joint mainly includes an outer joint member 10 and a tripod member 20. One of the two shafts to be connected is connected to the outer joint member 10 and the other is a tripod member 20 having three radially protruding leg shafts 22.
Is linked to

The outer joint member 10 has a generally cup-like appearance, and three track grooves 12 extending in the axial direction are formed in the inner peripheral portion at circumferentially equal positions. Roller guide surfaces 14 are respectively provided on circumferentially opposite side walls of each track groove 12.
Are formed. A roller 34 is attached to each leg 22 of the tripod member 20, and the roller 34 is housed in the track groove 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.

In this embodiment, the outer peripheral surface 3 of the roller 34
Reference numeral 4a denotes 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 and having a generatrix as a generatrix. The cross-sectional shape of the roller guide surface 14 is a Gothic arch shape. Surface 34a and roller guide surface 14
And make an angular contact. Even when the cross-sectional shape of the roller guide surface 14 is tapered with respect to the spherical roller outer peripheral surface 34a, angular contact between the two can be realized. By adopting a configuration in which the roller outer peripheral surface 34a and the roller guide surface 14 form an angular contact, the roller is less likely to oscillate, so that 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 the cross-sectional shape thereof is
4 may be an arc corresponding to the generatrix of the outer peripheral surface 34a.

A support ring 32 is fitted on the outer peripheral surface of the leg shaft 22. The support ring 32 and the roller 34 are unitized via a plurality of needle rollers (needle rollers) 36, and constitute a roller assembly in which the roller 34 can rotate relative to the support ring 32. That is, the cylindrical outer peripheral surface of the support ring 32 is used as the inner raceway surface, and the roller 3
With the cylindrical inner peripheral surface of No. 4 as an outer raceway surface, a needle roller 36 is rotatably interposed between these inner and outer raceway surfaces. The needle roller 36 has as many rollers as possible,
It is installed in a so-called full roller state without a retainer. Reference numeral 38 denotes a pair of washers for preventing the needle roller 36 from falling off. Washer 38
Is mounted in an annular groove formed on the inner peripheral surface of the roller 34,
The inner diameter of the washer 38 is larger than the outer diameter of the leg shaft 22 so as not to interfere with the leg shaft 22 when the roller 34 swings.

The inner peripheral surface 32c of the support ring 32 has an arc-shaped convex cross section. The inner peripheral surface 32c of the support ring 32 is externally fitted to the outer peripheral surface of the leg shaft 22 (for example, a straight shape parallel to the axis, and the cross section is an ellipse or a perfect circle). Not only is it possible to move in the axial direction of 22, but also to swing freely with respect to the leg shaft 22. Since the support ring 32 and the roller 34 are relatively rotatably assembled (unitized) via the needle roller 36 as described above, the support ring 32 and the roller 34 swing as a unit with respect to the leg shaft 22. In a movable relationship. 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.

When the leg shaft 22 of the tripod member 20 and the roller guide surface 14 of the outer joint member 10 are rotationally engaged via the roller 34, rotational torque is transmitted from the driving side to the driven side at a constant speed. You. Further, each roller 34 rolls on the roller guide surface 14 while rotating with respect to the leg shaft 22, so that the outer joint member 10 and the tripod member 20 are rotated.
The relative axial displacement and angular displacement between the outer joint member 10 and the tripod member 20 at the same time as transmitting the rotational torque while taking the operating angle are caused by the change in the rotational direction phase. The axial displacement of each leg shaft 22 with respect to the roller guide surface 14 is absorbed.

In a general tripod type constant velocity universal joint,
When the outer joint member 10 and the tripod member 20 transmit rotational torque while taking an operating angle, the rollers 34 and the roller guide surface 14 are obliquely intersected with each other with the inclination of the leg shaft 22. A problem arises in that induced thrust and slide resistance caused by slippage during the sliding are generated. On the other hand, by enabling the swing of the roller 34 with respect to the leg shaft 22 as in the present embodiment, the oblique state between the roller 34 and the roller guide surface 14 is eliminated, and the induced thrust and slide resistance are reduced. Reduction can be achieved.

The outer joint member 10 is made of, for example, a carbon steel material having a carbon content of 0.15 to 0.60 wt% (for example, S5
From 3C), forging → machining → heat treatment → shaft 10a
It is manufactured through the main process of grinding (see FIG. 2).

The heat treatment step includes a step of hardening the roller guide surface 14. In this step, as shown in FIG. 3, the roller guide surface 14 is hardened to HRc 55 or more by heat treatment such as quenching (the formation region of the hardened layer 42 is indicated by a dotted pattern), and the roller guide surface 14 is sufficiently hard to withstand the rolling of the roller 34. A long rolling fatigue life is imparted to the roller guide surface 14. A portion of the roller guide surface 14 near the opening of the outer joint member 10 is not subjected to the heat treatment, and forms an uncured uncured portion 44 (an area where the uncured portion 44 is formed in the axial direction is represented by S). The surface hardness of the uncured portion 44 is set to HRc 40 or less in order to prevent the occurrence of cracks when forming the projecting portion 46 described later. Since the roller 34 does not roll in the roller guide surface 14 near the opening of the outer joint member 10 where the uncured portion 44 is formed in a normal use state, even if the heat treatment is omitted, no particular problem occurs. Absent. The uncured portion 44 may be left as unquenched to leave a raw material, or may be subjected to a suitable heat treatment within a range in which the surface hardness does not exceed HRc40, and may be refined.

Since the uncured portion 44 is formed only in a part of the roller guide surface 14 as described above, the heat treatment includes
Induction quenching, in which local heating is easy and which can be controlled so as not to significantly affect a portion other than the hardened layer, is preferable.

As shown in FIGS. 3 and 4, the uncured portion 4
4 has a protrusion 46 protruding toward the inner diameter side of the leg shaft 22 by plastic deformation. The projecting portion 46 hits, for example, the vicinity of the opening of the roller guide surface 14 with a jig, and
It can be formed by caulking to the inner diameter side.
Thus, the protrusion 46 is provided on the roller guide surface 14 near the opening.
Forming the roller 34 that has reached the vicinity of the opening.
Interferes with the protruding portion 46, and further movement toward the opening side is restricted, so that the outer joint member 10 of the tripod member 20 is
Can be reliably prevented from coming off. Regardless of the phase of the tripod member 20 in the rotational direction, it is desirable to form at least one protrusion 46 in each track groove 12 in order to obtain a reliable retaining effect.

In FIG. 1, the projecting portion 46 is connected to the outer peripheral surface 14 of the roller.
Are arranged near the center of curvature of the projection, but if this is formed by displacing the center of curvature in any of the leg axis directions, the protrusion 4
Since the roller 6 interferes with the roller 34 at both ends in the leg axis direction, the plunging amount between the two axes can be increased.

As shown in FIG. 5, the projection 46 is
A plurality of stages (two stages in the illustrated example) can be arranged in the axial direction, and in this case, the pull-out force shared by each protrusion 46 is reduced, so that a higher pull-out resistance can be obtained in the entire joint.
The cross-sectional shape of the protruding portion 46 is not limited to a rectangular shape as shown in FIG. 4, but may be a circular shape (FIG. 6A) or a triangular shape (FIG. 6).
(B)].

In a normal tripod type constant velocity universal joint, a gap between the roller 34 and the roller guide surface 14, that is, a dimensional difference between a roller diameter and a distance between the roller guide surfaces 14 facing each other is about 0.2 mm. . Therefore, as shown in FIG. 4, by setting the protrusion width T of the protrusion 46 (the protrusion width from the roller guide surface 14) to 0.5 mm or more, the tripod member 20 can be reliably prevented from coming off.

When the above-mentioned tripod type constant velocity universal joint is used for a drive shaft, a shaft (not shown) is attached to the tripod member 20, and a fixed type such as a zepper type constant velocity universal joint (ball fixed joint) is attached to the other end of the shaft. A constant velocity universal joint is attached. The drive shaft is assembled to the body of the automobile in an assembled state in which the two kinds of constant velocity universal joints and the shaft are assembled. In this assembly, the outer joint member 10 of the tripod type constant velocity universal joint is placed upward. Then, the tripod member 20 acts on its own weight and the weight of the shaft and the fixed type constant velocity universal joint. At this time, the force for pulling out the tripod member 20 from the outer joint member 10 is 490 N at the maximum.
A pull-out strength of 90 N or more is required.

The pull-out strength can be adjusted by changing the number of protrusions 46 provided in each track groove 12 as described above. In addition, it can be adjusted by changing the axial length U of the projecting portion 46. For example, as shown in FIG. 1, when the projecting portions 46 are provided one by one on the opposing roller guide surfaces 14, the axial direction of the projecting portion 46 can be adjusted. Length U is 1m
It was found that a pull-out strength of 490 N or more can be obtained when the distance is at least m.

The case where the present invention is applied to the tripod type constant velocity universal joint exemplified in FIGS. 1 and 2 has been described above. However, the present invention is not limited to this, and various types of tripod type constant velocity universal joints can be applied. Can be applied.

For example, the following mechanism is known as a mechanism which allows the roller 34 to swing freely with respect to the leg shaft 22. The present invention can be applied to any of the following mechanisms. is there.

Outer roller (the roller 34 of the present embodiment)
), The so-called “torus surface” in which the outer peripheral surface of a convex spherical surface (corresponding to “.
), The inner peripheral surface is cylindrical, the outer peripheral surface of the inner roller (corresponding to the support ring 32 of the present embodiment) is a convex spherical surface, the cylindrical inner peripheral surface of the outer roller and the convex spherical surface of the inner roller. (See Japanese Patent Publication No. 3-1529, etc.) that allows the outer roller to swing freely by sliding between itself and the outer peripheral surface.

The outer peripheral surface of the outer roller has a convex spherical shape (including both a true spherical surface and a torus surface), the inner peripheral surface has a shape in linear contact with the inner roller, and the outer peripheral surface of the inner roller has a convex spherical shape. By sliding between the surface and the convex spherical outer surface of the inner roller, the outer roller can swing freely and swing,
Further, in order to further reduce induced thrust and slide resistance, the inner peripheral surface of the outer roller is shaped to generate a load component directed toward the tip end of the leg shaft at the position of contact with the outer peripheral surface of the inner roller (Japanese Patent Laid-Open Publication No. No. 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 concave. One in which the outer roller can swing freely by sliding between the outer peripheral surface (Japanese Patent Application No. 8-4073, Japanese Patent Application No. 8-138335).

In addition to the above configuration, the roller guide surface and the axis of the leg shaft are not parallel to each other with an operating angle of 0 ° (JP-A-11-13779).

The outer peripheral surface of the leg shaft is formed in a convex spherical shape, and the roller is assembled to the support ring via a plurality of needle rollers to form a roller assembly, and the cylindrical inner peripheral surface of the support ring is formed in a convex shape of the leg shaft. Those which are externally fitted to a spherical outer peripheral surface (Japanese Patent Publication No. 7-117108, Japanese Patent No. 2623216, etc.).

A roller guided on a roller guide surface,
A support ring that is fitted over the outer peripheral surface of the leg shaft and rotatably supports the roller, the inner peripheral surface of the support ring has an arc-shaped convex cross section, and the outer peripheral surface of the leg shaft has a straight shape in a vertical cross section. In the cross-section, it comes into contact with the inner peripheral surface of the support ring in a direction perpendicular to the axis of the joint, and forms a clearance between the inner peripheral surface of the support ring in the axial direction of the joint. (Japanese Patent Application No. 11-59040).

The present invention is not limited to the above-described swinging type, but can be similarly applied to a tripod type constant velocity universal joint in which rollers do not swing.

[0043]

As described above, according to the present invention, a high surface hardness is obtained on the roller guide surface on which the roller rolls, so that the life of the joint can be improved by increasing the rolling fatigue life and the like. Further, of the roller guide surface, a protruding portion is provided near the opening of the outer joint member, and the protruding portion interferes with the roller moved to the vicinity of the opening, so that the tripod member can be reliably prevented from coming off. Moreover, since the protruding portion is formed by plastic deformation, a high retaining effect can be obtained simply and at low cost. Since the protruding portion is formed in the uncured portion of the roller guide surface, it does not crack or the like during plastic deformation and has good workability.

[Brief description of the drawings]

FIG. 1 is an end view (front view) of a tripod type constant velocity universal joint according to the present invention.

FIG. 2 is a longitudinal sectional view of the tripod type constant velocity universal joint shown in FIG.

FIG. 3 is an enlarged longitudinal sectional view of a main part of FIG. 2;

FIG. 4 is a front view of the outer joint member.

FIG. 5 is a front view showing another embodiment of the protrusion.

FIG. 6 is a front view showing another embodiment of the protruding portion.

FIG. 7 is an end view (front view) of a conventional tripod type constant velocity universal joint.

FIG. 8 is an end view (front view) showing an example of a conventional retaining structure.
It is.

FIG. 9 is an end view showing an example of a conventional retaining structure (front view).
It is.

FIG. 10 is an end view (front view) showing a conventional retaining structure example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Outer joint member 12 Track groove 14 Roller guide surface 20 Tripod member 22 Leg axis 32 Support ring 34 Roller 36 Needle roller 44 Uncured part 46 Projecting part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Taku Itagaki 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture (72) Inventor Hisaaki Kura 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture

Claims (6)

[Claims] 1. An outer joint member having three axial track grooves on an inner periphery thereof and a roller guide surface formed on a side wall facing each track groove, and three radially protruding leg shafts. A tripod-type constant velocity universal joint, comprising: a tripod member having an outer joint member rotatably mounted on an outer periphery of each leg shaft; and a roller housed in a track groove of the outer joint member, wherein the roller is guided by a roller guide surface. A tripod-type constant velocity wherein the guide surface is hardened by heat treatment while leaving the vicinity of the opening of the outer joint member, and a protruding portion capable of interfering with the roller is formed by plastic deformation in an unhardened portion near the opening. Universal joint. 2. The tripod type constant velocity universal joint according to claim 1, wherein at least one projecting portion is formed in each track groove. 3. The tripod type constant velocity universal joint according to claim 1, wherein the roller guide surface is hardened by induction hardening. 4. The tripod-type constant velocity universal joint according to claim 1, wherein the surface hardness of the uncured portion is HRc 40 or less. 5. The tripod-type constant velocity universal joint according to claim 1, wherein the protrusion width of the protrusion is 0.5 mm or more. 6. The tripod-type constant velocity universal joint according to claim 1, wherein the protrusion has a pull-out strength of 490 N or more.