JPS61228125A - Uniform motion joint - Google Patents

Abstract

PURPOSE:To enable a joint to increase its folding angle, by permitting a ball to be dislocated to a fixed limit from a ball groove in an outer ring when the joint increases its folding angle to a maximum. CONSTITUTION:A ball B is both guided by a ball groove 4 in an inner ring R1 and held to a cage C in a condition that a part of the ball is left in a ball groove 2. Consequently, the ball, being prevented from falling off from a joint and again returned into the ball groove 2 in accordance with a rotation of the joint, renders services to torque transmission of the joint. Accordingly, one or two of the balls B are derailed from the ball groove 2 as the joint rotates, but the ball, being prevented from being completely freed, enables a folding angle of the joint to be increased larger by forming the ball groove of an outer ring in a short length.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a Zeppa type constant velocity joint.

[Conventional technology]

FIG. 7 shows a constant velocity joint of a conventional Zeppa cover, and is a sectional view thereof. This joint is disclosed, for example, in FIGS. 1 and 2 of Japanese Utility Model Publication No. 58-53148.

In the figure, RO is the outer ring, R1 is the inner ring, and S is the shaft.

In the outer ring Ro, 1 is a concave spherical surface provided on the inner circumferential surface, and 2 is a ball groove provided in this concave spherical surface 1. A plurality of ball grooves are formed in the longitudinal direction of the outer ring RO. In the inner ring R1, 3 is a convex spherical surface provided on the outer peripheral surface, 4 is a ball groove provided on this convex spherical surface 3,
A plurality of grooves are formed in the longitudinal direction of the inner ring R, so as to pair with each ball groove 2 of the outer ring RO.

B is a ball interposed between the ball groove 2 of the outer ring RO and the ball groove 4 of the inner ring R1 to transmit torque between the inner and outer rings. C is a cage which is interposed between the inner and outer rings Ro and R1, with an outer spherical surface 5 in sliding contact with the concave spherical surface l of the outer ring RO, and an inner spherical surface 6 in sliding contact with the convex spherical surface 3 of the inner ring R1. This cage C is provided with a pocket 7 in which the method B is held.

The centers of curvature of the groove bottom 2a of the ball groove 2 and the groove bottom 4a of the ball groove 4 are set at points offset by a certain distance to the left and right from the joint center 0, so that the ball B is always aligned with the two axes. It is oriented on the bisecting plane P of the corner, so that uniform velocity can be ensured regardless of the operating angle or rotation angle.

When the bending angle θi of the joint is maximized by bringing the shaft S into contact with the chamfer m of the outer ring RO, the ball B located on the opposite side of the bending angle direction (in the drawing, the ball B is closest to the opening of the outer ring Ro) The closer ball B) is designed not to come off the ball groove 2 of the outer ring Ro. In other words, the ball B closest to the opening has center 01 of ball B and joint center 0
1 at the outer end point on the line connecting the groove bottom 2 of the ball groove 2.
It is designed so that it does not deviate outside of 2 at the terminal point of a.

Now, if the distance from the joint center 0 to the above-mentioned end point 2 is X, and the distance from the joint center O to the above-mentioned outer end point 1 is xl, then there is a relationship of X>x+. therefore,
All the balls B (6 balls) are always held in the cage C and exist in the ball grooves 2 and 4 of the outer ring Ro and the inner ring R. The bending angle θ1 at the maximum value is 46.5 degrees for the constant velocity joint currently in practical use.

Note that the centers of curvature of the groove bottoms 2a, 4a are set at positions offset from the joint center 0, as described above, so the distance between the groove bottoms 2a, 4a is from the bottom side of the outer ring Ro to the opening. It gradually increases in size laterally. The centers of curvature of the outer spherical surface 5 of the cage C and the inner spherical surface 6 of the cage C coincide with the joint center O.

[Problem that the invention seeks to solve]

However, in such a conventional constant velocity joint, as described above, the ball B that transmits the torque between the inner ring R1 and the outer ring RO has the shaft S in contact with the chamfered portion m of the outer ring Ro. Even when the bending angle θ1 of the joint is maximized, it is necessary that it always be in the ball groove 2 of the outer ring RO.
And it was designed that way. For this reason, the maximum bending angle θ■ of the joint in current use is 4B.5 degrees. Therefore, even though there has been a recent demand for improving the turning radius of automobiles by reducing their turning radius as much as possible, there has been a problem in that it is not possible to meet this demand as is.

Of course, even with current constant velocity joints, it is necessary to (1) reduce the diameter of the shaft S, or (2) reduce the joint balls P and C.
,D (pitch circle diameter
) can be increased, the bend angle of the joint itself can be increased to 48.5° + α.

However, when the diameter of the shaft S is reduced, the static torsional strength and torsional durability strength of the shaft S are significantly reduced, making it difficult to obtain the strength required for practical use and making it difficult to put it into practical use. A constant velocity joint that allows bending angles of 4B and 5°, and bending angles of 3
In order to increase the shaft diameter by more than 150 degrees, it is necessary to make the shaft diameter φ18.2, but when made thinner in this way, the static torsional strength (torsional stress τ) of the shaft decreases by 40%, and the torsional durability strength also decreases to 1/10 or less. .

On the other hand, if the joint balls P-C and D are increased,
The outer diameter of the outer ring RO has to become larger. 1. New problems such as interference with surrounding parts, increased weight, or cost increase occur, making it difficult to put it into practical use. 0. For example, the shaft diameter is φ22.8.
In order to maintain the shaft diameter of φ22.8 and increase the bending angle by 3 degrees or more with a joint that allows a bending angle of 48.5°, the outer ring outer diameter needs to be increased from φ80 to φ82. .

This invention was made to solve these conventional problems.When the bending angle of the joint is maximized, the ball on the opposite side of the bending angle direction is prevented from coming out of the ball groove of the outer ring. The purpose is to increase the bending angle of the joint by configuring it to allow up to a certain limit.

[Means for solving problems]

In this invention, in a Zeppa type constant velocity joint, when the bending angle of the joint is maximized, the first ball located on the opposite side of the bending angle direction comes out of the ball groove of the outer ring, and the first ball is placed next to the first ball. The second ball located at is characterized in that the ball groove of the outer ring is shortened within a range that does not deviate from the ball groove of the outer ring.

〔Example〕

FIG. 1 shows an embodiment of the invention.

In the figure, the same reference numerals as in FIG. 7 indicate the same or corresponding parts. R2 is an outer ring, which is the same as the conventional outer ring RO in terms of outer shape and dimensions. ml is a chamfered portion that comes into contact with the shaft S, and is formed by chamfering the chamfered portion m of the conventional outer ring RO to a larger extent. Therefore, the ball groove 2 is further shortened by an amount corresponding to the chamfered portion. The lower limit is
When the shaft S comes into contact with the chamfered portion m1 of the outer ring R2 and the bending angle θ2 of the joint reaches the maximum (48,5@+α), the ball B located on the opposite side of the bending angle direction (the opening of the outer ring R2 This is until the ball B closest to the ball B (hereinafter referred to as the top ball B) just comes out of the ball groove 2.

That is, the length of the ball groove 2 is as follows: The terminal point of the groove bottom 2a of the ball groove 2 is 3, and the outer end point of the ball B, which is on the line connecting the joint center 0 and the center 01 of the ball B, is 1. Further, if the distance from the joint center 0 to the above-mentioned end point 3 is X, and the distance from the joint center O to the above-mentioned outer end point Kl is Xl, then at the lower limit.

X1≧X・・・・・・(1) It is set so that the relationship is satisfied.

On the other hand, the upper limit is that under the same conditions, the top ball B and two balls B on both sides of it (hereinafter referred to as side balls B), so-called a total of three balls B, simultaneously miss the end point 3 of the outer ring groove bottom 2a. Since half of the six balls B no longer receive any load, the inner ring R1 cannot be restrained in the radial direction.

Therefore, the above upper limit is just before 4 at the outer end points of the side balls B on both sides of the top ball B deviates from 3 at the end point of the ball groove 2 of the outer ring R2. The outer end point 4 here is a point on the outer surface of the balls B on both sides, which are on the line connecting the joint center O and the center 02 of the side ball B.

That is, at its upper limit, the length of the ball groove 2 is as follows: X≧x2 (2) It is set so that the relationship is satisfied. however.

xl is the distance from the joint center O to the above outer end point 4.

Therefore, the length of the ball groove 2 is x1 from equations (1) and (2).
≧X≧x2 (3) is set to be satisfied.

Here, when the calculated values of xl and xl in the above equation (3) are obtained from FIGS. 2 to 6, they are as follows.

(1) Calculation of x+ In Fig. 2.3, when the joint is bent by the bending angle φ, due to the offset center (P, Q) of the center of curvature (P, Q) of the ball grooves 4.2 of the inner and outer rings R, R2, All the balls B exist on the bisector of the bending angle φ, and have a positional relationship as shown in FIG. 4 when viewed from the Y direction.

Now, the position of the outer end point Kl of the top ball B at position a is determined, assuming that the balls P, C, and D are r, and the diameter of ball B is d.

From Figure 3 The distance x1 from the joint center 0 to the outer end point 1 is Here, 1 is obtained by the following formula.

0K1=OD+DK+ =OD+DO1+ol Kl Further, D is the point at which the center C of the balls P, C, and D in the neutral state has moved due to the offset of the ball grooves 4.2 of the inner and outer rings R1 and R2. therefore.

Therefore, OK+ = OD+DK+ It can be expressed as

(2) Calculation of X2 The center of side ball B at position b with joint angle φ attached is the ellipse with MM, NNt - minor axis and major axis in Figure 4, and the joint as shown in Figure 5. It is determined as the intersection of the outer ring R2, which is divided into six equal parts with the center 0, and the ball groove 2. Therefore, the formula for an ellipse with MM, NNt - minor axis and major axis is calculated using the dot as the origin, MM as the y axis, and NN as the x axis.
Find the coordinates for the axis. NN=2 a, MM=2
If it is b.

The formula for the center line of the ball groove 2 of the outer ring R2 is y = xta
n 30°−NikodeC is from Figure 6, φ φ,”,y=xtan30°−esrn−cos
-"""■By the way, since NN is the same as P, C, and D when the joint angle is 0 degrees, 2a=r(P.

C, D), MM are from Figure 6. Since DO1=-, Therefore, the ■expression is becomes.

Since the center of side ball B at position b is the y-coordinate of the intersection of equations 2 and 2, it can be determined from equations 2 and 3.

■Transform the formula.

Substituting the 0 expression into the 0 expression.

＝　0　・・・・・・・・・■ The coordinates of the side ball center B at position b are (xb).

yb) from joint center 0 to ball B center 02
Find the distance to.

002 = OD + DO2, yb can be found from formula 0, so OK
The distance of A is found. Therefore, the distance x2 from the outer end point 4 of the side ball B at position b to the joint center O is (3) In this example, 1 is the outer end point of the top ball B at the end of the ball groove 2. Since the point exists outside point 3, the above equation (3), that is, the relational expression x1≧X≧x2 is obtained.

Note that r, d, e, and φ are numerical values specifically given at the time of joint design.

Next, the effect will be explained.

The bending angle θ2 of the joint is regulated by the abutment between the shaft S and the chamfered portion m1 of the outer ring R2, and is at its maximum at that time.

The 6-sided ball B comes on the bisecting plane of the bending angle θ2, but at that time, the outer end point Kl of the top ball B is on the outer ring R2.
It comes out of the ball groove 2 at the end point of the ball groove 2, so it comes off from the ball groove 2. Further, when the ball B rotates by half a pitch (30 degrees), the two balls, the top ball B and the ball B following it, similarly come out of the ball groove 2.

In this way, one or two balls B come out of the ball groove 2 as the joint rotates, but they do not become completely free; that is, some of these balls B remain in the ball groove 2. In this state, ball groove 4 of inner ring R1
Since it is guided by the cage C and held by the cage C, it does not fall off from the joint, and as the joint rotates, it returns to the ball groove 2 and contributes to the torque transmission of the joint.

In this state, if a load is applied to the joint,
There is no problem because the four or five balls B present in the ball grooves 4, 2 of the outer rings R, , R2 contribute to torque transmission.

Incidentally, when the following test was conducted assuming the usage condition of an actual vehicle at a sharp turning angle, the durability strength as a joint was sufficient for practical use considering the usage conditions of an actual vehicle.

(Test conditions (2), test results Ball B smoothly enters and exits from ball 1iIII2,
No abnormalities affecting joint function were observed. In addition, in the case of this test product, the maximum static bending angle θ2 is possible up to 50 degrees, which is 3.
It was possible to increase the angle by 5°.

Also, the centering of the joint is done correctly,
There were no problems in functioning as a constant velocity joint.

As mentioned above, in the embodiment, 4 to 5 of the 6 balls B are always held in the ball groove 2 of the outer ring R2, so that practical durability and strength are not impaired. , the bending angle of the joint can be made even larger than the conventional 48.5 degrees.

[Effects of the Invention] As explained above, according to the present invention, when the bending angle of the joint is maximized, the first ball located on the opposite side of the bending angle direction of the joint comes out of the ball groove of the outer ring. Since the second ball located adjacent to the first ball has the ball groove of the outer ring shortened within a range that does not deviate from the ball groove of the outer ring, the bending angle of the joint can be increased.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of an embodiment of this invention, Figure 2 is a cross-sectional view for explaining the detailed configuration of the embodiment, Figures 3 to 6 are (-)
Figure 7 is a sectional view of a conventional constant velocity joint. In the figure, R1 is an inner ring, R2 is an outer ring, ml is a chamfered portion, S is a shaft, 2 and 4 are ball grooves, B is a ball, and C is a cage. M Figure 5

Claims (1)

[Claims] an outer ring having a concave spherical surface on its inner circumferential surface and a plurality of longitudinal ball grooves on the concave spherical surface; and an outer ring having a convex spherical surface on its outer circumferential surface, and a plurality of longitudinal balls forming pairs on the convex spherical surface with the outer ring ball grooves. An inner ring having a groove, a ball interposed between the ball groove of the outer ring and a ball groove of the inner ring to transmit torque between the inner and outer rings, and a ball interposed between the concave spherical surface of the outer ring and the convex spherical surface of the inner ring. In a Zeppa type constant velocity joint consisting of a cage that holds the ball in a cage pocket, when the bending angle of the joint is maximized, the first ball located on the opposite side of the bending angle direction of the joint is the ball of the outer ring. Out of the groove, the first
A constant velocity joint characterized in that the second ball located next to the ball has a ball groove of the outer ring shortened within a range that does not deviate from the ball groove of the outer ring.