JP2001234941A - Constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the induced thrust and sliding resistance of constant velocity universal joint. SOLUTION: This constant velocity universal joint is equipped with an external joint member 10 provided with three track grooves 12 having roller guide surfaces 14 arranged facing one another in the circumferential direction, a tripod member 20 furnished with three legs 22 protruding in the radial direction, rollers 34 inserted in the track grooves 12, and rings 32 fitted on the legs 22 for supporting the rollers 34 rotatably, and is arranged so that the rollers 34 are movable in the axial direction of the external joint member 10 along the guide surfaces 14, wherein the inside surface of each ring 32 is shaped cylindrically while the peripheral surface of each leg 22 is given a longitudinal cross-section in curved shape and such a crosswise section contacting with the inside surface of the ring 32 in the direction perpendicularly intersecting the axis of the joint and forming a gap with respect to the peripheral surface of the ring 32 in the axial direction of the joint.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slide type tripod type constant velocity universal joint. In general, a constant velocity universal joint is a type of universal joint that connects two shafts on a driving side and a driven side and can transmit rotational force at a constant speed even if there is an angle between the two shafts. The one that allows relative axial displacement between the two axes by plunging the joint, the tripod type connects a tripod member with three radially protruding legs to one axis. A hollow cylindrical outer joint member having three track grooves extending in the axial direction is connected to the other shaft, and the leg shaft of the tripod member is accommodated in the track groove of the outer joint member to transmit torque. It is like that.

[0002]

2. Description of the Related Art An example of a sliding tripod type constant velocity universal joint will be described with reference to FIG. 11. Referring to FIG. 11, three cylindrical track grooves 2 are formed in the inner peripheral surface of an outer joint member 1 in the axial direction.
An annular roller rotatably fitted via a plurality of needle rollers 6 to a cylindrical outer peripheral surface of three leg shafts 5 protruding in the radial direction of a tripod member 4 inserted into the outer joint member 1. 7
Is inserted into the track groove 2. Each track groove 2
A pair of roller guide surfaces 3 which are circumferentially opposed to each other are concave curved surfaces (partially cylindrical surfaces) parallel to the axis of the outer joint member 1, and 3
The outer peripheral surface of each roller 7 of the leg shaft 5 is a convex curved surface (partially spherical surface) adapted to the roller guide surface 3. Each roller 7 is movable in the axial direction of the outer joint member 1 along the track groove 2 while rotating around the leg shaft 5 while engaging with the roller guide surface 3 of the corresponding track groove 2.

[0003] As shown in FIG. 11 (B), when the joint transmits the rotational force with the operating angle θ, the roller 7 and the roller guide surface 3 are inclined with respect to each other as shown in FIG. 11 (C). It becomes an intersecting relationship. In this case, the roller 7 tends to roll in the direction indicated by the arrow t in FIG. 11B, while the track groove 2 is a partial cylindrical surface parallel to the axis of the outer joint member 1. Move while being constrained by the track groove 2. As a result, the roller guide surface 3
Friction occurs between the roller and the roller 7 to generate sliding resistance, and the sliding friction generates an induced thrust in the axial direction. Such slide resistance and induced thrust cause vibration and noise of the vehicle body, affect the NVH performance of the vehicle, and reduce the degree of freedom in designing the underbody of the vehicle.

As a slide type tripod type constant velocity universal joint designed to reduce such slide resistance and induced thrust, for example, a structure shown in FIG. 12 is known.
That is, as shown, the leg shaft 5 of the tripod member 4
Is formed into a true spherical surface, and the cylindrical inner circumferential surface of the cylindrical ring 8 is slidably fitted on the true spherical surface. Ring 8
And the roller 7 constitute a roller assembly that is relatively rotatable via a rolling element. The needle rollers 6 are arranged in a so-called full roller state between the cylindrical outer peripheral surface of the ring 8 and the cylindrical inner peripheral surface of the roller 7, and are prevented from falling off by an annular washer 9. The roller 7 is accommodated in the track groove 2 of the outer joint member 1 and is movable in the axial direction of the outer joint member 1 while rolling on the roller guide surface 3 of the track groove 2.

[0005] The outer peripheral surface of the leg shaft 5 is a true spherical surface having a center of curvature on the axis of the leg shaft 5, and the roller assemblies (7, 8) swing around the center of curvature. Since the roller assembly is swingable, the roller 7 keeps a posture parallel to the axis of the outer joint member 1 when transmitting torque when the outer joint member 1 and the tripod member 4 are at an operating angle. As described above, the roller is guided by the roller guide surface 3 of the outer joint member 1, and rolls correctly on the roller guide surface 3 in the same posture. Therefore, the sliding friction during the operation angle operation is reduced, and the generation of slide resistance and induced thrust is suppressed.

[0006]

It is known to use a tripod-type constant velocity universal joint for transmitting rotational force from an automobile engine to wheels at a constant speed. The sliding tripod type constant velocity universal joint has a spherical roller attached to the leg shaft of the tripod member, and is a full-roller type without a needle roller as a rolling element between the outer peripheral surface of the leg shaft and the inner peripheral surface of the spherical roller. Used. When torque is transmitted in an angled state, induced thrust is generated during rotation due to mutual friction between internal components, and slide resistance is generated when the shaft is forcibly expanded and contracted in the axial direction even in a stopped state. . As typical NVH phenomena of an automobile involving these induced thrust and slide resistance, there is a lateral vibration of a running vehicle in relation to the former, and an idling vibration phenomenon of a D range at a stop in an AT car in relation to the latter.

The point of solving the problem of NVH in automobiles is to reduce the magnitude of induced thrust and slide resistance of the joint. Generally, the induced thrust and slide resistance of a joint tend to depend on the magnitude of the operating angle. For this reason, when applied to a drive shaft of an automobile, it leads to design restrictions that the operating angle cannot be increased. Therefore, in order to increase the degree of freedom in designing a vehicle underbody, there has been a problem of stabilizing induced thrust and slide resistance at a low level.

Therefore, an object of the present invention is to further reduce and stabilize the induced thrust and slide resistance.

[0009]

According to the first aspect of the present invention, there is provided an outer joint member having three track grooves having roller guide surfaces disposed circumferentially opposed to each other, and three radially protruding joint members. A tripod member having a leg shaft, a roller inserted into the track groove, and a ring that is fitted to the leg shaft and rotatably supports the roller, wherein the roller extends along the roller guide surface. In the constant velocity universal joint that can move in the axial direction of the outer joint member, the inner peripheral surface of the ring is cylindrical, and the outer peripheral surface of the leg shaft is curved in a vertical cross section, and in a cross section. A constant velocity universal joint, wherein the constant velocity universal joint is configured to contact the inner peripheral surface of the ring in a direction orthogonal to the axis of the joint and to form a clearance between the inner peripheral surface of the ring and the axial direction of the joint. It is.

The cross-sectional shape of the leg shaft may be such that it contacts the inner peripheral surface of the ring in a direction perpendicular to the axis of the joint and forms a clearance with the inner peripheral surface of the 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 an ellipse (claim 2).

[0011] By adopting the above cross-sectional shape of the leg shaft, which was conventionally circular, when the joint takes an operating angle,
The leg shaft can be inclined with respect to the outer joint member without changing the attitude of the roller assembly. Moreover, as is clear from comparison of FIGS. 3 and 7 with FIG. 12C, the contact ellipse between the outer peripheral surface of the leg shaft and the ring approaches the point from the lateral length, and therefore the frictional 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.
Further, there is an advantage that the bending strength of the leg shaft is improved by increasing the section modulus of the base portion of the leg shaft. The inner peripheral surface of the ring does not need to be cylindrical over the entire length, and only the central portion that contacts the leg shaft is cylindrical, and both ends are formed with relief portions to avoid interference when the leg shaft is inclined. Is also good.

The roller assembly plays a role of transmitting torque by being interposed between the leg shaft and the outer joint member. In this kind of constant velocity universal joint, the direction of torque transmission is always orthogonal to the axis of the joint. The torque can be transmitted by the contact between the leg shaft and the ring in the torque transmission direction, and even if there is a clearance between the two in the axial direction of the joint, torque transmission will not be hindered. Never do.

According to a second aspect of the present invention, in the constant velocity universal joint according to the first aspect, the cross section of the leg shaft is formed in an elliptical shape whose major axis is perpendicular to the axis of the joint. Here, the elliptical shape is not limited to a literal ellipse, but includes a shape generally called an oval shape, an oval shape, or the like.

More specifically, by adopting the cross-sectional shape of the leg shaft as described in the third to fifth aspects, the contact surface pressure with the ring is reduced, and a decrease in the strength of the leg shaft can be avoided. Moreover, since the leg shaft can be tilted without tilting the ring, the roller guide surface can be smoothly rolled without tilting the roller. Therefore, a flange that may be provided in the track groove of the outer joint member for the purpose of restricting the inclination of the roller can be omitted. By omitting the flange, not only the weight of the outer joint member can be reduced, the processing can be simplified, but also there is no slide resistance caused by the sliding contact between the roller and the flange, so that the slide resistance can be further reduced. A reduction in induced thrust is achieved.

According to a sixth aspect of the present invention, in the constant velocity universal joint according to any one of the first to fifth aspects, the radius of curvature of the curved shape in the longitudinal section of the leg shaft is set to 1.1a to 8.7a. Features. As a result, the inclination of the leg shaft caused by the whirling of the center of the trunnion, which is peculiar to the tripod type constant velocity universal joint, can be absorbed, so that the factor that causes the roller assembly to incline in the joint cross section is eliminated, and the NVH performance of the automobile is improved. Contribute.

According to a seventh aspect of the present invention, in the constant velocity universal joint according to any one of the first to sixth aspects, only a predetermined range including a region of the outer peripheral surface of the leg shaft that is in contact with the inner peripheral surface of the ring is ground. It is characterized by the following. It is preferable that the predetermined range is set somewhat wider than the contact area in consideration of a processing error or the like. Then, a portion other than the predetermined range may be left as forged without being subjected to grinding, thereby making it possible to reduce processing time and cost.

According to an eighth aspect of the present invention, in the constant velocity universal joint according to any one of the first to seventh aspects, the outer peripheral surface of the roller and the roller guide surface of the outer joint member are in angular contact. . Since the roller and the roller guide surface make an angular contact, 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, there is less resistance on the roller guide surface. Rolls smoothly. Such angular
As an example of a specific configuration for realizing the contact, the generatrix of the outer peripheral surface of the roller may be a convex arc, and the cross-sectional shape of the roller guide surface may be a tapered shape or a Gothic arch shape.

In the constant velocity universal joint according to any one of claims 1 to 8, a plurality of rolling elements are arranged between the ring and the roller to make the ring and the roller relatively rotatable, so that the roller is a leg shaft. Can be smoothly rotated around, and slide resistance is reduced. Needle rollers (claim 9) or balls (claim 10) can be used as the rolling elements.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment shown in FIGS. 1 to 4 will be described. Here, FIG. 1 (A) is an end view of the joint with a partial cross section, FIG. 1 (B) shows a cross section perpendicular to the leg axis, and FIG. 2 shows the joint in an operating angle θ. 1 shows a longitudinal section. As shown in the drawing, the constant velocity universal joint 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 connected to the tripod member 20.

As shown in FIG. 1, the outer joint member 10
Has three track grooves 12 extending in the axial direction on the inner peripheral surface. Roller guide surfaces 14 are formed on circumferentially opposite side walls of each track groove 12. Tripod member 2
0 has three leg shafts 22 projecting in the radial direction, and a roller 34 is attached to each leg shaft 22.
Is accommodated in the track groove 12 of the outer joint member 10.
The outer peripheral surface of the roller 34 has a cross-sectional shape that matches the roller guide surface 14.

The outer peripheral surface of the roller 34 is a convex curved surface having a circular arc having a center of curvature at a position radially away from the axis, and the roller guide surface 14 has a Gothic arch shape in cross section. The roller 34 and the roller guide surface 14 form an angular contact. FIG. 1 (A)
The two hit positions are indicated by dashed lines. Although not shown, 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 roller 34 and the roller guide surface 14 form an angular contact, the roller 34 is less likely to oscillate, so that the posture is stabilized. When the angular contact is not adopted, 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 of the roller 34. May be an arc corresponding to.

A ring 32 is fitted on the outer peripheral surface of the leg shaft 22. The ring 32 and the roller 34 are unitized via a plurality of needle rollers 36, and constitute a roller assembly that can be relatively rotated. That is, with the cylindrical outer peripheral surface of the ring 32 as the inner raceway surface and the cylindrical inner peripheral surface of the roller 34 as the outer raceway surface, the needle rollers 36 are rollably interposed between the inner and outer raceway surfaces. As shown in FIG. 1 (B), the needle rollers 36 have as many rollers as possible.
It is installed in a so-called full roller state without a retainer. Reference numerals 33 and 35 denote a pair of washers mounted in an annular groove formed on the inner peripheral surface of the roller 34 for preventing the needle rollers 36 from falling off. These washers 33, 35 have a cut at one location in the circumferential direction (FIG. 4).
(See (B)), the elastically reduced diameter is inserted into the roller 34, and is mounted in the annular groove by using a force to expand elastically.

The outer peripheral surface of the leg shaft 22 has a vertical section (FIG. 1A).
Alternatively, when viewed in FIG. 2 (A), the central portion is a convex curve bulging outward, for example, a convex arc having a radius of curvature R, and when viewed in a cross section (FIG. 1 (B)), the long axis is the axis of the joint. Is an elliptical shape orthogonal to. In other words, the cross-sectional shape of the leg shaft is
The surfaces of the tripod member 20 that face each other in the axial direction are retracted in the mutual direction, that is, on the smaller diameter side than the virtual cylindrical surface.

As shown in FIG. 3, the inner peripheral surface of the ring 32 is cylindrical. Because of this and the vertical cross-sectional shape of the leg shaft 22 is convex as described above, the ring 32 can not only move in the axial direction of the leg shaft 22,
It is swingable about the leg shaft 22. Since the ring 32 and the roller 34 are unitarily rotatable via the needle rollers 36 as described above, the ring 32 and the roller 34 can be swung about the leg shaft 22 as a unit. It is in. Here, the swing means the leg shaft 22.
2 means that the axis of the ring 32 and the roller 34 is inclined with respect to the axis of the leg shaft 22 in a plane including the axis of FIG.
(A)).

Although it is possible to make the inner peripheral surface of the ring 32 substantially cylindrical over the entire length, here, the ring 3
The generatrix on the inner peripheral surface of No. 2 is formed by a combination of a central cylindrical portion 32a and escape portions 32b on both sides thereof. Escape part 32
b is a portion for avoiding interference with the leg shaft 22 when the operation angle θ is set as shown in FIGS. 2A and 4A, and is a portion from the end of the cylindrical portion 32a to the end of the ring 32. It is composed of a straight line or a curve gradually increasing in diameter toward. here,
The case where the relief portion 32b is a part of a conical surface with a cone angle α = 50 ° is illustrated.

In the tripod type constant velocity universal joint, mechanically,
When the outer joint member 10 makes one rotation, the tripod member 20
Swings about the center of the outer joint member 10 three times. At this time, the amount of eccentricity represented by the symbol e (FIG. 2A) increases in proportion to the operating angle θ. And the three leg shafts 22 are 12
Although they are separated by 0 °, when the operating angle θ is taken, FIG.
As shown in (B), considering the vertical leg shaft 22 appearing on the upper side of FIG.
Are slightly tilted from their axes when the operating angle is 0 as indicated by the two-dot chain line. The inclination is that the operating angle θ is about 23 °, for example.
In this case, the angle is about 2 to 3 °. Since this inclination is naturally allowed by the curvature of the outer peripheral surface of the leg shaft 22, it is possible to prevent the surface pressure at the contact portion between the leg shaft 22 and the ring 32 from becoming excessively high. Note that FIG.
(A) schematically shows three leg shafts 22 of the tripod member 20 viewed from the left side surface, and a solid line represents the leg shaft.

In the case of the conventional joint shown in FIG.
12C is in contact with the inner circumferential surface of the ring 8 over the entire circumference, so that the contact ellipse has a horizontally elongated shape extending in the circumferential direction as shown by a broken line in FIG. Therefore, when the leg shaft 5 is tilted with respect to the outer joint member 1, a frictional moment is generated which acts to tilt the ring 8 and thus the roller 7 with the movement of the leg shaft 5. On the other hand, in the embodiment shown in FIG. 1, the cross section of the leg shaft 22 is elliptical, and the inner peripheral surface of the ring 32 is cylindrical. As shown by, the point becomes close to a point, and at the same time, the area decreases. Therefore, when transmitting the torque in the state where the operating angle is set, the roller assembly (32, 3) is required.
4) The force for inclining the roller 34 is greatly reduced as compared with the conventional one, and the stability of the attitude of the roller 34 is further improved.

Further, in the conventional joint shown in FIG. 12, for the purpose of restricting the inclination of the roller 7, the end face of the roller 7 is located on the deep side of the track groove 2, that is, on the large diameter side in the cross section of the outer joint member 1. An opposing collar is formed. However, in the above embodiments, and in the examples described below,
Since the factor of tilting the roller 34 is reduced, it is not always necessary to provide such a flange, and the flange can be omitted. As a result, even if the roller 34 is temporarily shaken for some reason, there is no fear that the roller 34 comes into contact with the flange to generate sliding friction.

[0029] FIGS. 5 to 7 illustrate the above-described embodiment.
Ball 36 'as a rolling element in place of the needle roller 36
The embodiment used is shown. With the use of ball 36 '
Track surfaces are provided on the outer peripheral surface of the ring 32 and the inner peripheral surface of the roller 34.
And instead of having no washers 33 and 35
Of the ball 36 'in the ring 32' and the roller 34 '
1 except that holes 33 'and 35' are provided.
The chair is basically the same as that already described in connection with FIG.
There is no place.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to carry out the present invention, as shown in FIG.
2 contacts with each other to transmit torque, so that it is necessary to reduce surface pressure at a contact portion between the two. Hereinafter, specific examples for that purpose will be described. FIG.
In (B), the vertical direction of the paper is the torque transmission direction, and the horizontal direction of the paper is the non-load side.

When the joint transmits the torque with the operating angle θ, the leg shaft 22 reciprocates within the range of the operating angle θ with respect to the ring 32, as shown by the two-dot chain line in FIG. .
At this time, on the non-load side, the leg shaft 22 and the ring 32
Because there is a relatively large clearance between the legs 32, the leg shaft 22 can swing without interfering with the ring 32.
However, on the load side, as the operating angle θ increases and the inclination of the leg shaft 22 increases, the apparent curvature of the leg shaft 22 increases as indicated by the two-dot chain line in FIG. When the curvature becomes larger than the inner diameter of the ring 32, the leg shaft 22 and the ring 32 come to two points. Then, thereafter, only the leg shaft 22 cannot be freely tilted, and the ring 32 and, consequently, the roller assemblies (32, 34) are tilted. Therefore, the cross-sectional shape of the leg shaft 22, particularly the shape on the load side, is determined so that only the leg shaft 22 can be tilted without interfering with the ring 32 within a predetermined angle range.

Specifically, the maximum operating angle θmax is set to 25 °
As shown in FIG. 8, when the major axis radius a and the minor axis radius b of the elliptical cross section of the leg shaft 22 and the radius of curvature R of the outer peripheral surface in the vertical cross section of the leg shaft 22 are set as follows: ,
The ring 32 does not tilt even when the joint has the maximum operating angle, and the contact ellipse between the leg shaft 22 and the ring 32 can be close to a circle (minimum ellipse) when the operating angle is 0 °. b / a = 0.841R = 2.380a The recommended range of the radius of curvature R is 0.5R to 1.5R, that is, 1.190.
a to 3.570a, the ellipticity b /
a becomes 0.983-0.669.

With the above setting, however, the shape is possible, but there is a concern that the surface pressure between the leg shaft 22 and the ring 32 is too high when the vehicle is actually used. Therefore, if low vibration is required in a normal operating angle range for automotive applications, if the operating angle is reduced to such an extent that the roller assembly (32, 34) does not tilt, the surface pressure is reduced, and actual use is possible. For example, if the normal operating angle θ is in the range of more than 10 ° and less than 20 °, the radius of curvature R of the inner peripheral surface of the ring, the optimum value of the ellipse and b / a, and the recommended range are as shown in Table 1.

[0034]

[Table 1]

As described above, the elliptical cross section of the leg shaft 22 is
The smaller the ellipticity b / a, the larger the operating angle
Without tilting the roller assembly (32, 34)
The leg shaft 22 can tilt, but the surface pressure of the contact portion
And the strength of the leg shaft 22 also decreases. Therefore, FIG.
In this embodiment, the cross-sectional shape of the leg shaft 22 is connected to the ring 32.
Ellipticity b only for the touching area, that is, the contact area β₁
/ A₁And maximum operation for other non-contact areas
Ellipticity b that does not interfere with the angle_Two/ A_TwoComposite ellipse
It is a shape. For example, the normal operation angle θmax
Is set to 15 °, and the radius of curvature R of the outer peripheral surface of the leg shaft 22 is set to 3.8.
88a, the ellipticity b of the contact area ₁/ A₁To 0.
894, and the ellipticity b of the non-contact area_Two/ A_Two0.70
4 is assumed. In FIG. 9, the contact area β
Although shown, the cross section of the leg shaft 22 is symmetrical.
Needless to say, there is also a contact area above the figure.
No.

In the embodiment shown in FIG. 10, the contact area β is not formed by a single ellipse, but by an ellipticity (b /
a) is continuously changed. For example, in the same manner as described above, when the normal operation angle θmax is set to 15 ° and the radius of curvature R of the outer peripheral surface of the leg shaft 22 is set to 3.888a, the ellipticity at the position intersecting with the long axis is set to 1.0 in the contact area. The ellipticity is gradually reduced as the distance from the position increases, and the ellipticity is set to 0.704 in the non-contact area. Alternatively, the ellipticity may be gradually reduced from 1.0 to 0.704 from the long axis to the short axis regardless of the contact area and the non-contact area. FIG. 10 illustrates a case where the ellipticity is set to 1.0 at a position intersecting with the long axis of the contact area, and the radius of curvature is gradually reduced at predetermined angles as away from the position, for example, as illustrated.

As described above, since the cross-sectional shape of the leg shaft 22 is elliptical, the load-side contact area (β) requiring accuracy is required.
Only the area to be ground may be set, and the other non-contact area may be processed to a shape withdrawn to the inner diameter side from a regular ellipse (indicated by a two-dot chain line in FIG. 10), so as to allow grinding relief. It is not always necessary to form the grinding relief portion by positively performing cutting or other processing, and it may be formed in the shape at the time of forging the leg shaft, and may be left in forged finish. It also leads to shortening and cost reduction.

[0038]

The present invention relates to an outer joint member having three track grooves formed with circumferentially opposed roller guide surfaces, and a tripod member having three radially projecting leg shafts. And a roller inserted into the track groove, and a ring that is externally fitted to the leg shaft and rotatably supports the roller, wherein the roller extends in the axial direction of the outer joint member along the roller guide surface. In a movable constant velocity universal joint, the inner peripheral surface of the ring is cylindrical, and
The outer peripheral surface of the leg shaft has a curved shape in the longitudinal section, and in the transverse section, contacts the inner peripheral surface of the ring in a direction orthogonal to the axis of the joint and the inner peripheral surface of the ring in the axial direction of the joint. Since the clearance is formed between the outer joint member and the surface, the leg shaft can be inclined with respect to the outer joint member without changing the attitude of the roller assembly when the joint takes an operating angle. In addition, since the contact ellipse between the outer peripheral surface of the leg shaft and the ring approaches the point from the horizontal direction, 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. Further, there is an advantage that the bending strength of the leg shaft is improved by increasing the section modulus of the base portion of the leg shaft.

The constant velocity universal joint of the present invention can contribute to the improvement of the NVH performance of a vehicle, particularly when applied to a drive shaft of a vehicle, in which the magnitude of the slide resistance and the induced thrust is involved, and the freedom of designing the underbody of the vehicle. The degree increases.

[Brief description of the drawings]

FIG. 1A is an end view of a constant velocity universal joint with a partial cross section, and FIG. 1B is a cross section perpendicular to a leg axis.

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

FIG. 3 is an enlarged sectional view of a ring.

FIG. 4A is a cross-sectional view of a tripod member and a roller assembly. (B) is a plan view.

5 (A) is an end view of a constant velocity universal joint with a partial cross section, FIG. 5 (B) is a cross section perpendicular to a leg axis,

FIG. 6 is a longitudinal sectional view of the constant velocity universal joint, showing a state where an operating angle is set.

FIG. 7 is an enlarged sectional view of a ring.

FIG. 8 is a transverse sectional view of a leg shaft.

FIG. 9 is a cross-sectional view of a leg shaft.

FIG. 10 is a transverse sectional view of a leg shaft.

11A is a cross-sectional view of a conventional constant velocity universal joint, FIG.
FIG. 2B is a longitudinal sectional view, and FIG. 2C is a schematic perspective view showing a relationship between a roller and a roller guide surface.

12A is a cross-sectional view of another conventional constant velocity universal joint, FIG. 12B is a cross-sectional view perpendicular to a leg axis, and FIG. 12C is a cross-sectional view of a ring for explaining a contact ellipse. .

[Explanation of symbols]

 Reference Signs List 10 outer joint member 12 track groove 14 roller guide surface 20 tripod member 22 leg axis a long axis radius b short axis radius R radius of curvature 32, 32 'ring 32a, 32a' cylindrical part 32b, 32b 'relief part 34, 34' roller 36 Needle roller (rolling element) 36 'Ball (rolling element)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeyoshi Ishiguro 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture, Japan (72) Inventor Kenji Terada 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture, Japan (72) Inventor Hisakura Kura 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture Inside NTN Corporation

Claims (10)

[Claims] 1. An outer joint member having three track grooves formed with circumferentially opposed roller guide surfaces, a tripod member having three radially protruding legs, and the track. A roller inserted into the groove, and a ring externally fitted to the leg shaft and rotatably supporting the roller, wherein the roller is movable in the axial direction of the outer joint member along the roller guide surface. In a speed universal joint, an inner peripheral surface of the ring is cylindrical, and an outer peripheral surface of a leg shaft is curved in a vertical cross section, and in a transverse cross section, the ring is a direction orthogonal to an axis of the joint. A constant velocity universal joint, wherein a clearance is formed between the inner peripheral surface of the ring and the inner peripheral surface of the ring in contact with the inner peripheral surface of the ring. 2. The constant velocity universal joint according to claim 1, wherein the cross section of the leg shaft has an elliptical shape whose major axis is perpendicular to the axis of the joint. 3. The method according to claim 2, wherein b / a is 0.50 to 0.98, where a is the major axis radius of the elliptical cross section of the leg axis and b is the minor axis radius. The described constant velocity universal joint. 4. When the major axis radius is a and the minor axis radius is b, the ellipticity b / a is set so that the area in contact with the inner peripheral surface of the ring is larger than the other areas. The constant velocity universal joint according to claim 2, wherein the joint is made larger. 5. The ellipticity b / a gradually decreases from a portion in contact with the ring to a portion intersecting with the minor axis, where a is the major axis radius of the elliptical cross section of the leg axis and b is the minor axis radius. The constant velocity universal joint according to claim 2, wherein 6. The constant velocity universal joint according to claim 1, wherein the radius of curvature of the curved shape in the longitudinal section of the leg shaft is set to 1.1a to 8.7a. 7. The constant velocity universal joint according to claim 1, wherein only a portion of the outer peripheral surface of the leg shaft that contacts the ring is ground. 8. The constant velocity universal joint according to claim 1, wherein an outer peripheral surface of the roller is in angular contact with a roller guide surface of the outer joint member. 9. The constant velocity universal joint according to claim 1, wherein a plurality of needle rollers are arranged between the ring and the roller to make the ring and the roller relatively rotatable. 10. The constant velocity universal joint according to claim 1, wherein a plurality of balls are arranged between the ring and the roller to make the ring and the roller relatively rotatable.