JP2000257643A - Constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce induced thrust and slide resistance of a sliding tripod type constant velocity universal joint. SOLUTION: In a constant velocity universal joint provided with an outer side joint member 10 formed with three track grooves 12 having a roller guide surface 14 arranged to be opposed to each other in a circumferential direction, tripod member 20 provided with three leg shafts 22 protruded in a radial direction, rollers 34 inserted in the track groove 12, and rings 32 externally fitted to the leg shaft 22 to rotatably support the roller 34, to make the roller 34 movable in an axial direction of the outer side joint member 10 along the roller guide surface 14, a relatively rotatable roller assembly is constituted by interposing a plurality of balls 36 between the ring 32 and the roller 34, an internal peripheral surface of the ring 32 is formed in a circular arc-shaped protruded section, also an external peripheral surface of the leg shaft 22 is formed in straight shape in a vertical section and, in a cross section, so as to abut to the internal peripheral surface of the ring 32 in a direction orthogonal to an axial line of the joint also so as to form a clearance between the external peripheral surface and the internal peripheral surface of the ring 32 in an axial line direction of the joint.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sliding 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 when there is an angle between the two shafts. In this type, a relative axial displacement between two axes is made possible by expansion and contraction (plunging) of a joint, and a tripod type includes a tripod member having three leg shafts protruding in a radial direction. A hollow cylindrical outer joint member provided with three track grooves extending in the axial direction and connected to the other shaft is connected to the other shaft, and the leg shaft of the tripod member is engaged in the track groove of the outer joint member. The torque is transmitted.

[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. 5. Referring to FIG. 5, three cylindrical track grooves (2) are formed in the inner peripheral surface of an outer joint member (1) in the axial direction. And a plurality of needle rollers (6) on the cylindrical outer peripheral surface of three leg shafts (5) protruding in the radial direction of the tripod member (4) inserted into the outer joint member (1). An annular roller (7) which is rotatably fitted via a roller is inserted into the track groove (2). A pair of roller guide surfaces (3) facing each other in the circumferential direction of each track groove (2) are concave curved surfaces parallel to the axial direction, and the outer peripheral surface of each roller (7) of the three leg shafts (5) is The convex surface conforms to the roller guide surface (3). Each roller (7) is movable along the track groove (2) while rotating about the leg shaft (5) while engaging with the roller guide surface (3) of the corresponding track groove (2).

As shown in FIG. 5 (B), when the joint transmits an operating angle (θ) and transmits a rotational force, the roller (7) and the roller guide surface (3) are connected to each other by the roller (7). As shown in FIG. In this case, the roller (7)
5B rolls in the direction indicated by the arrow (t) in FIG. 5B, whereas the track groove (2) is a part of a cylindrical surface parallel to the axis of the outer joint member. 7)
Moves while being constrained by the track groove (2). As a result, slippage occurs between the roller guide surface (3) and the roller (7), causing slide resistance, and furthermore, the slippage causes 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 sliding tripod-type constant velocity universal joint designed to reduce such slide resistance and induced thrust, for example, a joint shown in FIG. 6 is known. That is, as shown in the figure, the outer peripheral surface of the leg shaft (5) of the tripod member (4) is made a true spherical surface, and the cylindrical ring (8) is formed on the true spherical surface.
Has an outer peripheral surface slidably fitted. The ring (8) and the roller (7) form a roller assembly that is relatively rotatable via rolling elements. 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). Is made. The roller (7) is housed in the track groove (2) of the outer joint member (1), and rolls on the roller guide surface (3) of the track groove (2) in the axial direction of the outer joint member (1). Can be moved.

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 and swingable, when the outer joint member (1) and the tripod member (4) transmit rotational force in an operating angle, the roller (7) becomes the outer joint member (1). Is guided by the roller guide surface (3) of the outer joint member (1) so as to maintain a posture parallel to the axis of the roller, and rolls correctly on the roller guide surface (3) in the same posture. Therefore, the sliding resistance during the operation angle operation is reduced, and the generation of the sliding resistance and the induced thrust is suppressed.

[0006]

It is known to use a sliding tripod type constant velocity universal joint for transmitting a 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 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 in 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.

However, in the conventional sliding-type tripod type constant velocity universal joint, since the rolling elements are needle rollers of the full-roller type, an eccentric load such as an edge load is applied to the rolling element surface due to skew of the rollers during rotation. Easy to work. Further, the contact state is not stable due to the internal clearance and the relationship of accuracy, and the edge load acts even if the spherical roller is inclined. Also,
Structurally, a relative slip also occurs between the end of the spherical roller and the leg shaft or washer. It is considered that phenomena such as skew, edge load, and relative slip govern the magnitude of the frictional force inside the joint.

Therefore, an object of the present invention is to reduce and stabilize induced thrust and slide resistance by minimizing these frictional forces.

[0010]

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 a constant velocity universal joint movable in the axial direction of an outer joint member, a plurality of balls are interposed between the ring and the roller to form a relatively rotatable roller assembly, and the inner peripheral surface of the ring is formed in an arc shape. While being formed in a convex cross section, the outer peripheral surface of the leg shaft has a straight shape in a vertical cross section, and in a transverse cross section, comes into contact with the inner peripheral surface of the ring in a direction perpendicular to the axis of the joint. A constant velocity universal joint being characterized in that so as to form a gap between the inner peripheral surface of the ring in the axial direction of the joint.

The cross-sectional shape of the leg shaft may be such that it makes contact with the inner peripheral surface of the ring in a direction perpendicular to the axis of the joint and forms a clearance between the leg shaft and 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).

By making the cross-sectional shape of the leg shaft, which has been conventionally circular, the above shape, the leg shaft is inclined with respect to the outer joint member without changing the attitude of the roller assembly when the joint takes an operating angle. be able to. In addition, since the contact ellipse between the outer peripheral surface of the leg shaft and the ring approaches the point from the lateral length (see FIGS. 1C and 6C), 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.

Although the roller assembly plays a role of transmitting torque by interposing 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 leg shaft and the ring are in contact with each other in the direction of torque transmission, torque transmission is possible, and even if there is a clearance between the two in the axial direction of the joint, torque transmission will not be hindered. Never come.

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 has a substantially elliptical shape whose major axis is perpendicular to the axis of the joint. The substantially elliptical shape is not limited to a literal ellipse, but includes a shape generally called an oval shape, an oval shape, or the like.

According to a third aspect of the present invention, in the constant velocity universal joint according to the first or second aspect, the generatrix of the inner peripheral surface of the ring is constituted by an arc portion at the center and a relief portion at both ends. Features. 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 °.

According to a fourth aspect of the present invention, in the constant velocity universal joint according to any one of the first to third aspects, balls are arranged in double rows between the ring and the roller.
By supporting the rollers with double rows of balls, the load capacity against moment load increases compared to the case of single rows,
Durability also improves.

According to a fifth aspect of the present invention, in the constant velocity universal joint according to any one of the first to fourth aspects, the outer peripheral surface of the roller is formed in a spherical shape, and the spherical outer peripheral surface of the roller is a roller of the outer joint member. It is characterized by angular contact with the guide surface. Since the roller and the roller guide surface make angular contact, the posture of the roller is further stabilized, so that when the roller moves in the axial direction of the outer joint member, the roller smoothly rolls on the roller guide surface with less resistance. . If a specific configuration for realizing such an angular contact is exemplified, the cross-sectional shape of the roller guide surface may be a tapered shape or a gothic arch shape.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment of the present invention shown in FIGS. 1 and 2 will be described. Here, FIG.
1 shows a cross section of the joint, FIG. 1 (B) shows a cross section perpendicular to the leg axis, and FIG. 2 shows a vertical cross section of the joint in a state where an operating angle (θ) is taken.

As shown in FIG. 1, the constant velocity universal joint comprises 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).

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). The tripod member (20) has three leg shafts (22) projecting in the radial direction, and a roller (34) is attached to each leg shaft (22), and the roller (34) is connected to the outer joint member. (10) Track groove (1)
It is housed in 2). The outer peripheral surface of the roller (34) is a convex curved surface conforming to the roller guide surface (14). Here, the outer peripheral surface 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. The roller guide surface (14) is constituted by a part of a cylindrical surface whose axis is parallel to the axis of the outer joint member (10),
The cross-sectional shape is an arc corresponding to the generatrix of the outer peripheral surface of the roller (34).

The spherical outer peripheral surface of the roller (34) and the roller guide surface (14) may form an angular contact. For example, such an angular contact is realized by making the cross-sectional shape of the roller guide surface (14) into a tapered shape or a gothic arch shape.

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 balls (36), and constitute a relatively rotatable roller assembly. That is, an inner raceway surface is formed on the outer peripheral surface of the ring (32), and an outer raceway surface is formed on the inner peripheral surface of the roller (34). Then, a ball (36) is rotatably interposed between the inner raceway surface of the ring (32) and the outer raceway surface of the roller (34). As shown in FIG. 1B, the ball (36) is incorporated in a so-called full ball state. Reference numerals 33 and 35 denote holes for assembling the ball (36).

The drawing shows a ring (32) and a roller (34).
Although the case where a plurality of balls (36) are arranged in a single row between them has been exemplified, it is also possible to arrange them in a plurality of rows.

The outer peripheral surface of the leg shaft (22) has a longitudinal section (FIG. 1).
(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 has a substantially arc shape with a reduced thickness in the axial direction of the tripod member (20). In other words, the cross-sectional shape of the leg shaft is such that the surfaces facing each other in the axial direction of the tripod member retreat in the mutual direction, that is, on the smaller diameter side than the virtual cylindrical surface.

The inner peripheral surface of the ring (32) has an arc-shaped convex cross section. That is, the generatrix of the inner peripheral surface is a convex arc having a radius r (FIG. 1C). Because of this, the cross-sectional shape of the leg shaft (22) is substantially elliptical as described above, and a predetermined clearance is provided between the leg shaft (22) and the ring (32). 32) not only can move in the axial direction of the leg shaft (22), but also can swing freely about the leg shaft (22). Also, as described above, the ring (32)
And the roller (34) are unitized so as to be relatively rotatable via the ball (36).
The ring (32) and the roller (34) are in a swingable relationship as a unit. Here, the swing means that the axes of the 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) (FIG. 2). reference).

In the case of the conventional joint shown in FIG. 6, since the outer peripheral surface of the leg shaft (5) is in contact with the inner peripheral surface of the ring (8) over the entire circumference, the contact ellipse is shown by a broken line in FIG. As shown in FIG. Therefore, when the leg shaft (5) is inclined with respect to the outer joint member (1), the leg (5) acts to tilt the ring (8) and, consequently, the roller (7) with the movement of the leg shaft (5). A friction moment occurs. In contrast, 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 of the ring (32) is cylindrical. As shown by the broken line in C), the contact ellipse of both is close to a point,
At the same time, the area is reduced. Therefore, the force for inclining the roller assembly (32, 34) is greatly reduced as compared with the conventional one, and the stability of the attitude of the roller (34) is further improved. Therefore, in some cases, the flange of the outer joint member for suppressing the inclination of the roller shown in FIG. 1A can be eliminated.

Next, a second embodiment of the present invention shown in FIGS. 3 and 4 will be described. In the second embodiment, the generatrix of the inner peripheral surface of the ring (32) is formed by a single arc in the first embodiment described above.
Central arc part (32a) and relief parts (32b) on both sides
Only in that it is formed in combination with. The escape portion (32b) is a portion for avoiding interference with the leg shaft (22) when the operating angle (θ) is taken as shown in FIG. 3 (C), and a ring is formed from the end of the arc portion (32a). It is composed of a straight line or a curve whose diameter gradually increases toward the end of (32). Here, an example is shown in which the relief portion (32b) is a part of a conical surface with a cone angle α = 50 °. Arc part (32a)
Has a large radius of curvature (R) of, for example, about 30 mm in order to allow a tilt of the leg axis (22) with respect to the ring (32) of about 2 to 3 °. 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. 2A) increases in proportion to the operating angle (θ).
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 axis (22) as a basis, the other two leg axes (22) are slightly inclined from their axes at an operating angle of 0 shown by a 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) on the inner peripheral surface of the ring (32), the surface pressure at the contact portion between the leg shaft (22) and the ring (32) becomes excessively high. Can be prevented.
FIG. 2 (B) schematically shows three leg shafts (22) of the tripod member (20) viewed from the left side surface of FIG. 2 (A), and a solid line represents the leg shaft. I have.

[0028]

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 the movable constant velocity universal joint, a plurality of balls are interposed between the ring and the roller to form a relatively rotatable roller assembly, and the inner peripheral surface of the ring is formed in an arc-shaped convex cross section, The outer peripheral surface of the leg shaft has a straight shape in a vertical cross section, and in a transverse cross section, contacts with the inner peripheral surface of the ring in a direction perpendicular to the axis of the joint, and in the axial direction of the joint. A clearance is formed between the outer joint member and the inner joint surface, so that when the joint takes an operating angle, the leg shaft is connected to the outer joint member without changing the attitude of the roller assembly with respect to the outer joint member. 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. Accordingly, the attitude of the roller assembly is always stable and the roller is held parallel to the roller guide surface, and the roller can roll smoothly. 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.

Further, according to the present invention, the roller interposed between the tripod member and the outer joint member is supported by the ball which smoothly rotates at low friction without any problem such as skew. When the roller rolls along the roller guide surface in the track groove of the outer joint member, rolling with low friction and low resistance is realized. Therefore, the sliding resistance when the roller slides in the track groove in the axial direction of the outer joint member, and furthermore, the induction that occurs when the outer joint member and the tripod member transmit torque in an operating angle state. A high performance sliding tripod type constant velocity universal joint with further reduced thrust and reduced vibration and noise can be provided.

The sliding tripod type constant velocity universal joint of the present invention can contribute to the improvement of the NVH performance of an automobile, especially when applied to a drive shaft of an automobile, in which the slide resistance and the magnitude of induced thrust are involved. The degree of freedom in vehicle underbody design also increases.

[Brief description of the drawings]

1A is a cross-sectional view of a constant velocity universal joint according to a first embodiment of the present invention, FIG. 1B is a cross-sectional view perpendicular to a leg axis,
(C) is a sectional view of a ring for explaining a contact ellipse.

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. 3A is an end view of a constant velocity universal joint with a partial cross section, showing a second embodiment of the present invention, and FIG. 3B is a cross section perpendicular to a leg axis in FIG. FIG. 3C is a longitudinal sectional view of the constant velocity universal joint shown in FIG.

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

FIG. 5A is a cross-sectional view of a conventional constant velocity universal joint,
(B) is a longitudinal sectional view of the constant velocity universal joint of (A), (C) is a schematic perspective view showing the interrelationship between the roller, the roller guide surface, and the roller in (B).

6A is a cross-sectional view of another conventional tripod type constant velocity universal joint, FIG. 6B is a cross-sectional view perpendicular to a leg axis, and FIG. 6C is a cross-sectional view of a ring for explaining a contact ellipse. It is.

[Explanation of symbols]

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

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatsuro Sugiyama 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture, Japan (72) Inventor Tatsuhiro Goto 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture, Japan (72) Inventor Kenji Terada 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture (72) Inventor Hiroshi Tone Hiroshi Tone 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture Intranet, Inc. No. 3-17 Inside NTN Corporation

Claims (5)

[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, a plurality of balls are interposed between the ring and the roller to form a relatively rotatable roller assembly, an inner peripheral surface of the ring is formed in an arc-shaped convex cross section, and the leg shaft is The outer peripheral surface has a straight shape in a vertical cross section, and in a transverse cross section, contacts the inner peripheral surface of the ring in a direction perpendicular to the axis of the joint and the inner periphery of the ring in the axial direction of the joint. A constant velocity universal joint wherein a clearance is formed between the joint and the surface. 2. The constant velocity universal joint according to claim 1, wherein the cross section of the leg shaft has a substantially elliptical shape whose major axis is perpendicular to the axis of the joint. 3. The constant velocity universal joint according to claim 1, wherein a generatrix on an inner peripheral surface of the ring is constituted by an arc portion at a center portion and a relief portion at both ends. 4. The constant velocity universal joint according to claim 1, wherein balls are arranged in a double row between the ring and the rollers. 5. An outer peripheral surface of the roller is formed in a spherical shape,
The constant velocity universal joint according to any one of claims 1 to 4, wherein the spherical outer peripheral surface of the roller is in angular contact with the roller guide surface of the outer joint member.