JP2002013544A - Constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance strength and durability of a cage. SOLUTION: A pocket 4c of the cage 4 comprises a pair of axial direction wall surfaces 4c1 facing in the direction of axis of the cage 4, a pair of circumferential wall surfaces 4c2 facing in the circumferential direction, and a corner radius section 4c3 which joins the axial direction wall surfaces 4c1 and the circumferential wall surface 4c2 together. Ratio (R/d) of a radius of curvature of the corner radius section 4c3 as opposed to a diameter d of a torque transmission ball 3 is turned into a limit value of 0.45<=R/d<=0.62, and the circumferential wall surface 4c2 and the corner radius section 4c3 are configured to form one arc having a radius of curvature R. In addition, as to the axial direction wall surface 4c1, variations of machining allowances are made small by performing grinding process or hardened steel cutting operation, after the heat treatment (carburizing and quenching, and tempering) of the cage 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant velocity universal joint capable of transmitting a rotational torque at a constant speed even when a drive shaft and a driven shaft are at an angle. Constant velocity universal joints
Fixed type constant velocity universal joints that allow only angular displacement between two axes, and sliding type constant velocity universal joints that allow angular displacement and axial displacement between two axes, and the present invention is the former of the former For fixed type constant velocity universal joints.

[0002]

2. Description of the Related Art FIG. 7 shows a fixed type constant velocity universal joint (zepper type constant velocity universal joint: ball fixed joint) conventionally used as a coupling for connecting a drive shaft of an automobile. The constant velocity universal joint includes an outer joint member 11 having six curved guide grooves 11b formed in a spherical inner surface 11a in an axial direction, and a spherical outer surface 12a.
a, an inner joint member 12 in which six curved guide grooves 12b are formed in the axial direction and a fitting portion 12c having a tooth shape (serration or spline) on an inner diameter surface, and a guide groove of the outer joint member 11 11b and the corresponding inner joint member 1
It comprises six torque transmitting balls 13 arranged on six ball tracks formed in cooperation with the two guide grooves 12b, and a retainer 14 having a pocket 14c for retaining the torque transmitting balls 13. Is done.

The center A of the guide groove 11b of the outer joint member 11
Is the inner joint member 12 with respect to the center of the spherical surface of the inner surface 11a.
The center B of the guide groove 12b is opposite to the center of the spherical surface of the outer diameter surface 12a by an equal distance in the axial direction, respectively (in the example shown in the figure, the center A is the opening side of the joint, and the center B is the depth of the joint. Part side). Therefore, the guide groove 11b
And the corresponding guide groove 12b cooperate with each other, the ball track is formed in a wedge-like shape toward one of the axial directions (in the example shown in the figure, the opening side of the joint). The spherical center of the inner diameter surface 11a of the outer joint member 11 and the spherical center of the outer diameter surface 12a of the inner joint member 12 are both in the joint center plane O including the center of the torque transmitting ball 13.

When the outer joint member 11 and the inner joint member 12 are angularly displaced by an angle θ, the torque transmitting ball 13 guided by the retainer 14 always has a bisector (θ) of the angle θ at any operating angle θ. / 2), and the constant velocity of the joint is ensured.

[0005]

FIG. 8 shows a retainer 14 of the above-described constant velocity universal joint. The retainer 14 has six window-shaped pockets 1 for holding the torque transmitting balls 13.
4c are provided at equally circumferential positions. Columns 14d are provided on both circumferential sides of the pocket 14c. Conventionally, the pocket 14c of the retainer 14 is formed by shaving (broaching) a pair of axial wall surfaces 14c1 facing each other in the axial direction (see FIG. 8B) after punching by press. In this case, by processing the axial wall surface 14c1, the axial initial clearance between the pocket 14c and the torque transmitting ball 13 is set to −50 μm to −10 μm.
If there is a variation in the machining allowance of 4c1, a so-called pocket staggered state occurs in which the center positions of the pockets 14c vary between the pockets 14c arranged in the circumferential direction, which hinders the strength and durability of the retainer 14. Therefore, the radius of curvature R of the corner radius portion 14c3 of the pocket 14c is reduced to reduce the linear portion 1c.
4c4, the axial dimension δ between the axial wall surface 14c1 and the straight portion 14c4 is controlled so that a so-called pocket staggered state does not occur. Therefore, the corner radius portion 14
As a result of reducing the radius of curvature R of c3, the pocket space is expanded to a part that is originally unnecessary functionally.

On the other hand, the present applicant has further improved strength, load capacity and durability equal to or higher than the conventional constant velocity universal joint (fixed constant velocity universal joint having six balls) shown in FIG. In order to reduce the size and weight of the vehicle, a fixed type constant velocity universal joint having eight ball tracks and eight torque transmitting balls has already been proposed (Japanese Patent Application No. 8-259484).
No.). In the constant velocity universal joint according to this proposal, the outer diameter of the outer joint member is smaller than that of the above-described conventional constant velocity universal joint (fixed constant velocity universal joint having six balls), so that the outer diameter of the retainer is reduced. The cross-sectional area around the pocket is reduced. Accordingly, if the pocket structure of the retainer is the same as the conventional structure, the stress acting on the pillar portion of the retainer is increased due to the pocket space being too wide from the functional aspect, and the surface area of the inner and outer diameter surfaces is increased. In some cases, and the strength and durability of the cage cannot be sufficiently secured.

Therefore, an object of the present invention is to optimize the pocket structure in the above-mentioned constant velocity universal joint without impairing the function of the cage, thereby improving the strength and durability of the cage, and furthermore, the joint. The purpose is to improve the strength and durability.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an outer joint member having eight curved guide grooves extending in the axial direction on a spherical inner surface, and a spherical outer member. An inner joint member formed with eight curved guide grooves extending in the axial direction on a radial surface, a guide groove of the outer joint member and a corresponding guide groove of the inner joint member are formed in cooperation with each other. Eight torque transmitting balls arranged in a ball track,
A cage having eight window-shaped pockets for holding a torque transmitting ball, wherein the ball track is a constant velocity universal joint opened in a wedge shape toward one of the axial directions, wherein the pocket of the cage is And a ratio (R / R) between the radius of curvature R of the corner radius and the diameter d of the torque transmitting ball.
d) is R / d ≧ 0.22, preferably 0.45 ≦ R / d
Provide a configuration where ≦ 0.62.

The ratio (R / d) is set within the above range for the following reason. FIG. 6 shows a result obtained by FEM analysis of the relationship between the ratio (R / d) and the maximum principal stress load acting on the pillar portion (the interval between circumferentially adjacent pockets) of the cage. From the results shown in the figure, it is recognized that the {(R / d)-(maximum principal stress load)} diagram takes a minimum value when R / d = 0.538, and when R / d = 0.538. It was confirmed that the maximum principal stress load of the column became the smallest theoretically. Further, as shown in Table 1, based on the analysis result, R / d = 0.5 for each size of the torque transmitting ball.
An R dimension satisfying 37 was determined. Further, since the general tolerance of the R dimension is ± 1 mm (general tolerance: the tolerance is ± 1 mm for those exceeding the standard dimension category of 6 mm), the upper limit value and the lower limit value of the R dimension are obtained, and The corresponding upper and lower limits of R / d were determined (the median of R / d is the average of the upper and lower limits). As a result, 0.45 ≦ R / d ≦ 0.62 was obtained as a preferable range of R / d. On the other hand, in the conventional cage shown in FIG. 8, R / d = 0.
21 and an effect of reducing the maximum main stress load can be expected if R / d ≧ 0.22. Therefore, the ratio (R / d) is set to R /
d ≧ 0.22, preferably 0.45 ≦ R / d ≦ 0.62
Within the range. By setting the ratio (R / d) within the above range, the pocket space is minimized without impairing the function of the retainer (operability with respect to the torque transmitting ball), and the inner surface of the retainer is reduced accordingly. In addition, the surface area of the outer diameter surface can be increased. Thereby, the strength and durability of the retainer can be enhanced in combination with the effect of reducing the maximum main stress load of the column portion.

[0010]

[Table 1]

Further, the present invention provides an outer joint member having eight spherical guide grooves extending in the axial direction on a spherical inner surface, and eight curves extending in the axial direction on a spherical outer surface. Eight ball tracks arranged on eight ball tracks formed in cooperation with the guide groove of the inner joint member, the guide groove of the outer joint member, and the guide groove of the corresponding inner joint member having the guide groove formed in the shape of a circle. A torque transmitting ball, a retainer having eight window-shaped pockets for holding the torque transmitting ball, wherein the ball track opens in a wedge shape toward one of the axial directions, and the outer joint member and the inner joint A constant velocity universal joint in which a straight portion having a linear groove bottom is provided in each guide groove of the member, wherein a pocket of the retainer has a corner radius portion, and a curvature radius R and a torque of the corner radius portion. The ratio (R / d) to the diameter d of the transmission ball is /D≧0.22, preferably 0.4
An arrangement is provided wherein 5 ≦ R / d ≦ 0.62. Since the constant velocity universal joint of the present invention includes a straight portion having a linear groove bottom in each of the guide grooves of the outer joint member and the inner joint member, it is larger than the constant velocity universal joint of the invention described above. There is a feature that the operating angle can be taken. Other matters are the same as those of the above-described constant velocity universal joint.

In the constant velocity universal joint according to the present invention, the torque transmitting ball is assembled as follows. That is, the outer joint member and the inner joint member are relatively angularly displaced,
With the pocket of the retainer facing outside through one opening of the outer joint member, the torque transmitting ball is assembled into the pocket of the retainer and the ball track. When the outer joint member and the inner joint member are relatively angularly displaced, the torque transmission ball held in the pocket of the cage relatively moves in the circumferential direction. The displacement angle with the inner joint member is referred to as the "ball assembly angle".
That. ), It is necessary to set the circumferential length of the cage pocket so that the torque transmission balls already incorporated do not relatively move in the circumferential direction and interfere with the circumferential wall surface of the cage pocket. Further, the relative movement amount of the torque transmitting ball in the pocket in the circumferential direction is 45 °, 135 °, 225 ° in phase angle.
°, 315 ° maximum, phase angle 0 °, 90 °, 1
It becomes 0 at each position of 80 ° and 270 °. In consideration of these points, the eight pockets of the retainer are configured by a first pocket and a second pocket having mutually different circumferential lengths,
In addition, the first pocket having a short circumferential length is 90 ° or 18 °.
A configuration in which they are arranged at intervals of 0 degrees can be adopted. The second pocket having a long circumferential length is set to a length which does not interfere with the circumferential wall surface of the pocket even when the torque transmitting ball relatively moves within the pocket when the torque transmitting ball is assembled. The first pocket, which is short in length, has an interference with the circumferential wall surface of the pocket when the joint takes the maximum operating angle (the maximum displacement angle that the joint can functionally take) even if the torque transmitting ball relatively moves in the pocket by the maximum amount. Set the length not to. Thereby, while ensuring the incorporation of the torque transmitting ball and the function of the joint, the surface area of the inner diameter surface and the outer diameter surface of the cage can be increased, and the strength and durability of the cage can be increased.

Alternatively, the eight pockets of the retainer may be constituted by pockets having the same circumferential length. As described above, by setting the ratio (R / d) to a value within the above range, the strength and durability of the cage are improved, so that the circumferential lengths of the eight pockets are all the same (the above-described second pocket). (The same length as two pockets).

At least a pair of axial wall surfaces facing each other in the axial direction of the cage among the wall surfaces of the pocket of the cage,
Preferably, the cage is formed by cutting after heat treatment. Here, "cutting" includes grinding, hardened steel cutting, and the like. As a result, the variation in the machining allowance of the axial wall surface is reduced, so that the straight portion provided for managing the machining allowance of the axial wall surface in the conventional pocket structure is eliminated,
By increasing the radius of curvature of the corner radius, the ratio (R / d) can be set to a value within the above range.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a fixed type constant velocity universal joint according to a first embodiment of the present invention. The constant velocity universal joint of this embodiment has an outer joint member 1 in which eight curved guide grooves 1b are formed in a spherical inner surface 1a in an axial direction, and eight curved surfaces in a spherical outer surface 2a. An inner joint member 2 in which an annular guide groove 2b is formed in the axial direction, and a fitting portion 2c having a tooth profile (serration or spline) is formed on the inner diameter surface;
Eight torque transmitting balls 3 arranged on eight ball tracks formed in cooperation with the guide groove 1b of the outer joint member 1 and the corresponding guide groove 2b of the inner joint member 2; And a holder 4 for holding the ball 3.
The shaft end of, for example, a drive shaft of an automobile is engaged with the fitting portion 2c of the inner joint member 2 by tooth-shaped fitting (serration fitting or spline fitting).

The center O1 of the guide groove 1b of the outer joint member 1 is relative to the center of the spherical surface of the inner surface 1a, and the center O2 of the guide groove 2b of the inner joint member 2 is relative to the center of the spherical surface of the outer surface 2a. In the example shown in the drawing, the center O1 is offset to the opposite side by an equal distance F in the axial direction (the center O1 is the opening side of the joint, and the center O2 is the back side of the joint). For this reason, the ball track formed by the guide groove 1b and the corresponding guide groove 2b cooperating with each other has a wedge-like shape that opens toward one of the axial directions (in the example shown in the drawing, the joint opening side). become.

The center of the spherical surface of the outer diameter surface 4a of the retainer 4 and the center of the spherical surface of the inner diameter surface 1a of the outer joint member 1 serving as a guide surface of the outer diameter surface 4a of the cage 4 Are located in the joint center plane O including the center O3. Also,
The center of the spherical surface of the inner diameter surface 4b of the retainer 4, and the outer diameter surface 2a of the inner joint member 2 serving as a guide surface of the inner diameter surface 4b of the retainer
Are in the joint center plane O. Therefore, the offset amount F of the center O1 of the guide groove 1b is
The axial distance between 1 and the joint center plane O and the offset amount F of the center O2 of the guide groove 2b are the axial distance between the center O2 and the joint center plane O, and both are equal.

The pitch circle diameter of the torque transmitting ball (PCD
_BALL) And diameter r (r) (= PCD)_BALL/ D) is
3.3 ≦ r1 ≦ 5.0, preferably 3.5 ≦ r1 ≦ 5.
It is set to a value within the range of 0. Where the torque transmission
Pitch diameter of the ball (PCD _BALL) Is twice the PCR
(PCD_BALL= 2 x PCR). Outer joint
Between the center O1 of the guide groove 1b of the material 1 and the torque transmitting ball 3
Length of the line segment connecting the centers O3, the guide groove 2b of the inner joint member 2
Line connecting the center O2 of the torque transmission ball 3 to the center O2 of the
Is the PCR, and both are equal. Ma
In addition, the outer diameter (D_OUTER) And inner joint member
Tooth shape (serration or spline) of fitting part 2c
Pitch circle diameter (PCD_SERR) And r2 (= D_OUTER /
PCD_SERR) Is a value within the range of 2.5 ≦ r2 <3.5.
Is set. Therefore, the constant velocity universal joint of this embodiment
Is the same as the conventional joint (fixed constant velocity universal joint with 6 balls)
Etc., with strength and durability equal to or greater than
It is impact.

In the above construction, when the outer joint member 1 and the inner joint member 2 are angularly displaced by the angle θ, the torque transmission ball 3 guided by the retainer 4 always has the angle θ of 2 at any operating angle θ. Maintained within the dividing plane (θ / 2), the constant velocity of the joint is ensured. FIG. 3 shows the retainer 4. The retainer 4 accommodates and holds the torque transmission ball 3.
It has a plurality of window-shaped pockets 4c and pillars 4d between the pockets 4c adjacent in the circumferential direction. In this embodiment, the circumferential length of each pocket 4c is all the same.
Also, the difference between the axial dimension L of the pocket 4c and the diameter d of the torque transmitting ball 3 at the initial stage of the joint operation (= L−
d), that is, the initial axial gap between the two is -30 to +
It is controlled within the range of 10 μm, preferably -10 to +10 μm. The eight pockets 4c are constituted by a first pocket and a second pocket having mutually different circumferential lengths, and the first pockets having a short circumferential length are arranged at intervals of 90 degrees or 180 degrees. You may. The cage 4 is formed of, for example, carburizing steel, and has a carburized layer formed by carburizing, quenching and tempering on a surface layer thereof. As the carburizing steel, chromium steel, chromium molybdenum steel, nickel chromium molybdenum steel, or the like can be used. In this embodiment, chromium molybdenum steel SCM415B is used. The surface hardness of the carburized layer is HRC 58-63, core part (excluding the carburized layer)
Has an HRC of 35 to 45. Further, in the predetermined cross section of the retainer 4, particularly, in the cross section of the column portion 4d, the area ratio of the core portion to the entire area is 40 to 55%.

As shown in FIG. 4, the pocket 4c of the retainer 4 has a pair of axial wall surfaces 4c1 opposed in the axial direction of the retainer 4 and a pair of peripheral wall surfaces 4c2 opposed in the circumferential direction. And a corner radius portion 4c3 connecting the axial wall surface 4c1 and the circumferential wall surface 4c2. In this embodiment, the corner radius 4 with respect to the diameter d of the torque transmitting ball 3
The ratio (R / d) of the radius of curvature R of c3 is 0.45 ≦ R / d ≦
A value within the range of 0.62, R / d = 0.
537, and the circumferential wall surface 4c2 and the corner radius portion 4c3 are drawn by one arc having a radius of curvature R. Further, with respect to the axial wall surface 4c1, after heat treatment (carburizing, quenching and tempering) of the cage 4, grinding or quenching steel cutting is performed to reduce the variation in the machining allowance (the circumferential direction).

The wall surface 4c2 and the corner radius portion 4c3 are left as they are by punching. FIG. 5 shows a constant velocity universal joint according to a second embodiment of the present invention. The constant velocity universal joint of this embodiment is different from the constant velocity universal joint of the first embodiment described above in that the guide groove 1b of the outer joint member 1 is provided.
And that the guide grooves 2b of the inner joint member 2 are provided with straight portions U1 and U2 each having a straight groove bottom. The constant velocity universal joint of this embodiment has the straight portions U1 and U2 provided in the guide groove 1b of the outer joint member 1 and the guide groove 2b of the inner joint member 2, respectively.
The maximum operating angle can be increased as compared with the constant velocity universal joint of the first embodiment described above. The other items are the same as those of the first embodiment, and the description is omitted.

[0023]

According to the present invention, in a fixed type constant velocity universal joint having eight ball tracks and eight torque transmitting balls, the pocket structure is optimized without impairing the function of the retainer, thereby , The strength and durability of the cage,
As a result, the strength and durability of the joint can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a constant velocity universal joint according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the constant velocity universal joint according to the first embodiment of the present invention.

FIG. 3 is a transverse sectional view {FIG. 3 (a)} and a longitudinal sectional view {FIG. 3 (b)} of the cage.

FIG. 4 is an enlarged plan view showing a peripheral portion of a pocket of the retainer.

FIG. 5 is a longitudinal sectional view of a constant velocity universal joint according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a ratio (R / d) and a maximum principal stress load of a column portion.

FIG. 7 is a longitudinal sectional view showing a conventional constant velocity universal joint.
(A)} and {FIG. 6 (b)}.

FIG. 8 is a longitudinal sectional view of a retainer in a conventional joint {FIG.
(A)｝, an enlarged plan view showing the periphery of the pocket ｛FIG.
(B)｝.

[Explanation of symbols]

 Reference Signs List 1 outer joint member 1a inner diameter surface 1b guide groove 2 inner joint member 2a outer diameter surface 2b guide groove 3 torque transmitting ball 4 retainer 4c pocket 4d pillar portion 4c1 axial wall surface 4c3 corner radius portion

Claims (6)

[Claims] An outer joint member formed with eight curved guide grooves extending in the axial direction on a spherical inner diameter surface, and eight curved guide grooves extending in an axial direction on a spherical outer diameter surface. And eight torque transmitting balls disposed on eight ball tracks formed by cooperation of the guide groove of the outer joint member and the corresponding guide groove of the inner joint member. ,
A cage having eight window-shaped pockets for holding a torque transmission ball, wherein the ball track is a constant velocity universal joint opened in a wedge shape toward one of the axial directions; A constant velocity universal joint having a corner radius portion, wherein a ratio (R / d) of a radius of curvature R of the corner radius portion to a diameter d of the torque transmission ball is R / d ≧ 0.22. 2. An outer joint member formed with eight curved guide grooves extending in the axial direction on a spherical inner diameter surface, and eight curved guide grooves extending in the axial direction on a spherical outer diameter surface. And eight torque transmitting balls disposed on eight ball tracks formed by cooperation of the guide groove of the outer joint member and the corresponding guide groove of the inner joint member. ,
A cage having eight window-shaped pockets for holding a torque transmitting ball, wherein the ball track opens in a wedge shape toward one of the axial directions, and the guide grooves of the outer joint member and the inner joint member are provided. A constant-velocity universal joint provided with a straight portion having a linear groove bottom, wherein the pocket of the retainer has a corner radius, the radius of curvature R of the corner radius and the diameter d of the torque transmitting ball. The constant (R / d) with respect to R / d ≧ 0.22. 3. The ratio (R / d) of the radius of curvature R of the corner radius to the diameter d of the torque transmitting ball is 0.45 ≦ R / d.
The constant velocity universal joint according to claim 1 or 2, wherein ≤ 0.62. 4. The eight pockets of the retainer are composed of a first pocket and a second pocket whose circumferential lengths are different from each other, and the first pocket having a short circumferential length is 90 degrees or The constant velocity universal joint according to any one of claims 1 to 3, wherein the constant velocity universal joints are arranged at intervals of 180 degrees. 5. The cage according to claim 1, wherein the eight pockets of the retainer have the same circumferential length.
The constant velocity universal joint according to any one of the above. 6. A pocket of the cage, wherein at least a pair of axial wall surfaces facing each other in the axial direction of the cage are formed by cutting the cage after heat treatment. The constant velocity universal joint according to claim 1.