JPH0668290B2 - Constant velocity joint - Google Patents

Description

The present invention relates to a Rzeppa type constant velocity joint.

[Conventional technology]

FIG. 7 shows a conventional Rzeppa type constant velocity joint. The figure is a sectional view thereof. This joint is disclosed, for example, in FIGS. 1 and 2 of Japanese Utility Model Publication No. 56-53148.

In the figure, R ₀ is an outer ring, R ₁ is an inner ring, and S is a shaft. Outer ring
In R ₀ , 1 is a concave spherical surface provided on the inner peripheral surface, 2 is a ball groove provided on the concave spherical surface 1, and a plurality of ball grooves are formed in the longitudinal direction of the outer ring R ₀ . In the inner ring R ₁ , 3 is a convex spherical surface provided on the outer peripheral surface, and 4 is a ball groove provided on the convex spherical surface 3 so as to be paired with each ball groove 2 of the outer ring R ₀ in the longitudinal direction of the inner ring R _1. A plurality of them are formed.

B is a ball that is interposed between the ball groove of the outer ring R ₀ and the ball groove 4 of the inner ring R ₁ to transmit torque between the inner and outer rings.
C is a cage, and the outer spherical surface 5 is provided on the concave spherical surface 1 of the outer ring R ₀ ,
The inner spherical surface 6 is slidably contacted with the convex spherical surface 3 of the inner ring R ₁ ,
It is interposed between the outer rings R ₀ and R ₁ . The cage C is provided with a pocket 7 for holding the ball B therein.

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 from the joint center O to the left and right by a certain distance, whereby the sphere B is always biaxial. Orientation is made on the bisector P of the angle so that the constant velocity can be ensured regardless of the operating angle and the rotation angle.

When the shaft S is brought into contact with the chamfered portion m of the outer ring R ₀ to maximize the bending angle θ _{1 of the} joint, the ball B located on the opposite side in the bending angle direction (in the drawing, the opening of the outer ring R ₀ The ball B) closest to the part is designed not to come off from the ball groove 2 of the outer ring R ₀ . That is, the ball B closest to the opening has the end point K ₂ of the groove bottom 2a of the ball groove 2 at the outer end point K ₁ on the line connecting the center O _{1 of the} ball B and the joint center O.
It is designed so that it cannot come out further. If the distance from the joint center O to the end point K ₂ is X and the distance from the joint center O to the outer end point K ₁ is x ₁ , then X>
There is a relationship of x ₁ . Therefore, all balls B (6)
Is always held in the cage C and exists in the ball grooves 2 and 4 of the outer ring R ₀ and the inner ring R ₁ . The bending angle θ ₁ when it is maximized above is the same for the constant velocity joints currently in practical use.
It is 46.5 degrees.

Since the center of curvature of the groove bottoms 2a and 4a is set at a position offset from the joint center O as described above, the distance between the groove bottoms 2a and 4a is set to the bottom side of the outer ring R _0. It gradually increases in a wedge shape toward the part side. 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.

[Problems to be solved by the invention]

However, in such a conventional constant velocity joint, as described above, the ball B that transmits the torque between the inner ring R ₁ and the outer ring R ₀ makes the shaft S contact the chamfered portion m of the outer ring R _0. It is necessary to always be in the ball groove 2 of the outer ring R ₀ even when they are in contact with each other to maximize the bending angle θ _{1 of the} joint, and
It was designed that way. For this reason, the maximum bending angle θ _{1 of the} joint was 46.5 degrees for the current one. Therefore, even if there is a recent demand for reducing the turning radius of an automobile as much as possible to improve its small turning characteristic, there is a problem that this cannot be handled as it is.

Of course, even in the current constant velocity joint, (1) make the diameter of the shaft S thin, or (2) joint the ball PCD (pit
If the ch circle diameter is increased, the bending angle of the joint can be increased to 46.5 ° + α.

However, if the diameter of the shaft S is reduced, the static torsional strength and the torsional durability of the shaft S are significantly reduced, and it is difficult to obtain the strength required for practical use and it is difficult to put it into practical use. For example, the diameter is φ22.8 and the bending angle is
With a constant velocity joint capable of 46.5 °, it is necessary to set the shaft diameter to φ19.2 in order to increase the bending angle by 3 ° or more, but if it is made thin like this, the static torsional strength (torsional stress τ) of the shaft is 40. %, And the torsional durability strength becomes 1/10 or less.

On the other hand, if the joint ball PCD is increased, the outer ring R
The outer diameter size of ₀ is inevitably large, and new problems such as interference with peripheral parts, an increase in weight, and an increase in cost occur, which makes practical application difficult. For example, a shaft diameter of φ22.8 and a bending angle of 4
With a joint capable of 6.5 °, in order to maintain the shaft diameter φ22.8 and increase the bending angle by 3 ° or more, the outer ring outer diameter is φ80.
It is necessary to increase the size up to φ92.

The present invention has been made to solve such a conventional problem, and when the bending angle of the joint is maximized, the balls coming on the opposite side in the bending angle direction are prevented from coming off from the ball groove of the outer ring. The purpose is to increase the bending angle of the joint by adopting a configuration that allows up to a certain limit.

[Means for solving problems]

According to the present invention, in the Rzeppa type constant velocity joint, when the bending angle of the joint is maximized, the first ball located on the opposite side in the bending angle direction is located outside the ball groove of the outer ring and adjacent to the first ball. The second ball is characterized in that the ball groove of the outer ring is shortened within a range in which it does not come off the ball groove of the outer ring.

〔Example〕

 FIG. 1 shows an embodiment of the present invention.

In the figure, the same reference numerals as in FIG. 7 indicate the same or corresponding parts. The outer ring R ₂ is the same in outer shape and size as the conventional outer ring R ₀ . m ₁ is a chamfer that contacts the shaft S, and is a conventional outer ring R ₀
The chamfered portion m is further chamfered. Therefore, the ball groove 2 is shortened by an amount corresponding to the chamfered portion. The lower limit is that when the shaft S comes into contact with the chamfered portion m ₁ of the outer ring R ₂ and the bending angle θ _{2 of the} joint reaches the maximum (46.5 ° + α), the ball B (on the opposite side in the bending angle direction) The ball B closest to the opening of the outer ring R ₂ and 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 now K _{3 at} the end point of the groove bottom 2a of the ball groove 2, the joint center O and the center of the ball B.
The outer end point of the ball B on the line connecting O ₁ is K ₁ , and
The distance from the joint center O to the end point K ₃ is X, and the distance from the joint center O to the outer end point K ₁ is x ₁
Then, at the lower limit thereof, the relation of x ₁ ≧ X ... (1) 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 (hereinafter referred to as side balls B), so-called three balls B at the same time, are the end points of the outer race groove bottom 2a.
Since half of the outside when six balls B to K ₃ is not under load becomes impossible radial restraint of the inner ring R _1.

Therefore, the upper limit is that the outer end points K ₄ of the side balls B adjacent to the top ball B are the end points of the ball groove 2 of the outer ring R _2.
Until just before K ₃ . The outer end point K ₄ referred to here is a point on the outer surface of the ball B on both sides, which is on the line connecting the joint center O and the center O ₂ of the side ball B.

That is, the length of the ball groove 2 is set so that the upper limit thereof satisfies the relationship of X ≧ x ₂ (2). However, x ₂ is the distance from the joint center O to the outer end point K ₄ .

Therefore, the length of the ball groove 2 is set so as to satisfy x ₁ ≧ X ≧ x ₂ (3) according to the equations (1) and (2).

Here, the calculated values of x ₁ and x ₂ in the above formula (3) are
Obtained from FIG. 6, the results are as follows.

(1) Calculation of .x _{1 In} Fig. 2 and 3, when the joint is bent at a bending angle φ, the center of curvature of the ball grooves 4 and ₂ of the inner and outer rings R ₁ and R ₂ (P, Q)
Due to the offset e of, all the balls B have the above bending angle φ.
Exist on the bisecting plane of and have a positional relationship as shown in FIG. 4 when viewed from the Y direction.

Now, the position of the outer end point K ₁ of the top ball B at the position a is obtained with the ball PCD = r and the diameter of the ball B = d.

From Figure 3 Distance x ₁ from the joint center O to the outer end points K ₁ is Is.

Here, K ₁ is calculated by the following equation.

OK ₁ = OD + DK ₁ = OD + DO ₁ + O ₁ K ₁ , D is the point where the center C of the ball PCD in the neutral state has moved due to the offset of the ball grooves 4, ₂ of the inner and outer rings R ₁ , R ₂ . Therefore, Therefore, Can be expressed as

Therefore, (2) Calculation of .x _{2 As} shown in FIG. 5, the center of the side ball B at the position b with the joint angle φ is an ellipse whose minor and major axes are MM and NN in FIG. It is obtained as the intersection of the outer ring R _{2 and} the ball groove 2 divided into six equal parts with the joint center O as the center. Therefore, the formula of the ellipse with MM and NN as the minor axis and the major axis is
The coordinates are calculated with the point D as the origin and the MM as the y-axis and the NN as the x-axis. If NN = 2a and MM = 2b, The formula of the center line of the ball groove 2 of the outer ring R ₂ is y = x tan 30 ° -C where C is from FIG. By the way, since NN is the same as PCD when the joint angle is 0 degree, 2a = r (PCD), MM is from FIG. Therefore, the formula is Becomes

Since the center of the side ball B at the position b is the y coordinate of the intersection point of the equation, it can be obtained from the equation.

Transform the expression, Substituting the expression into the expression, The distance from the joint center O to the center O ₂ of the ball B is determined with the coordinates of the side ball center B at the position b as (xb.yb).

here, Also, Therefore, Is. Since yb can be obtained from the equation, the OK ₄ distance can be obtained. Therefore, the distance x ₂ from the outer end point K ₄ of the side ball B at the position b to the joint center O is (3). In the case of this embodiment, since the outer end point K ₁ of the top ball B exists outside the end point K ₃ of the ball groove 2, the above expression (3), that is, the relationship of x ₁ ≧ X ≧ x ₂ is satisfied. The formula will be obtained.

It should be noted that r, d, e and φ are numerical values that are specifically given when the joint is designed.

Next, the operation will be described.

The bending angle θ _{2 of the} joint is the chamfered portion m _{1 of the} shaft S and the outer ring R _2.
It is regulated by the contact of, and then it is the maximum. The six balls B come on the bisector of the bending angle θ ₂ , and the outer end point K ₁ of the top ball B at that time goes out of the end point K ₂ of the ball groove 2 of the outer ring R _2. Therefore, it comes off from the ball groove 2. Further, when the ball B rotates a half pitch (30 degrees), the two balls, the top ball B and the ball B following the top ball B, are simultaneously removed from the ball groove 2.

Thus, one or two balls B will come out of the ball groove 2 as the joint rotates, but will not be completely free. That is, these balls B are guided by the ball groove 4 of the inner ring R ₁ and are held by the cage C with some of the balls B remaining in the ball groove 2, and therefore they cannot fall out of the joint. Instead, it returns to the ball groove 2 again with the rotation of the joint and contributes to the torque transmission of the joint.

If a load is applied to the joint in this state,
There is no problem because the four or five balls B existing in the ball shafts 4, ₂ of the outer rings R ₁ , R ₂ contribute to the torque transmission.

By the way, when the following test was conducted assuming a use state of a real vehicle at a sharp turning angle, the durability strength as a joint was practically sufficient considering the use conditions as an actual vehicle.

(1). Test condition (2). Test Results Ball B smoothly entered and left through the ball groove 2, and no abnormality affecting the function of the joint was observed. Moreover, in the case of this test product, the static maximum bending angle θ ₂ is
It can be up to 50 degrees and can be increased by 3.5 degrees from the conventional θ ₁ .

Also, the centering of the joint is done correctly,
There was no problem in exerting the function as a constant velocity joint.

As described above, in the embodiment, since 4 to 5 of the 6 balls B are always held in the ball groove 2 of the outer ring R ₂ , the practical durability and function are impaired. In addition, the bending angle of the joint can be made larger than the conventional 46.5 degrees.

As described above, according to the present invention, when the bending angle of the joint is maximized, the first ball located on the opposite side in the bending angle direction of the joint is disengaged from the ball groove of the outer ring, The second ball located next to the first ball has the ball groove of the outer ring shortened within the range in which the ball does not come off the ball groove of the outer ring, so that the bending angle of the joint can be increased.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view for explaining a detailed structure of the embodiment, and FIGS. 3 to 6 are views schematically showing the structure of FIG. FIG. 7 is a sectional view of a conventional constant velocity joint. In the figure, R ₁ is an inner ring, R ₂ is an outer ring, m ₁ is a chamfer, S is a shaft, 2,
4 is a ball groove, B is a ball, and C is a cage.

Claims (1)

[Claims] 1. An outer ring having a concave spherical surface on an inner peripheral surface thereof and having a plurality of longitudinal ball grooves on the concave spherical surface, and a convex spherical surface on an outer peripheral surface, and a plurality of pairs forming a pair with the outer ring ball groove on the convex spherical surface. An inner ring having a ball groove in the longitudinal direction, a ball for transmitting torque between the inner and outer rings by being interposed between the ball groove of the outer ring and the ball groove of the inner ring, and a concave spherical surface of the outer ring and a convex spherical surface of the inner ring. In a Rzeppa type constant velocity joint comprising a cage interposed between and holding 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 a constant velocity joint characterized in that the second ball positioned outside the ball groove of the outer ring and adjacent to the first ball has a shorter ball groove of the outer ring within a range in which the second ball is not separated from the ball groove of the outer ring.