JPH06193642A - Fitting structure of inner race to shaft portion of constant speed universal joint - Google Patents

Abstract

PURPOSE:To embody a constant speed universal joint miniaturized and lightened, having high operating angle, and also improved in its assemblage. CONSTITUTION:The inner side chamfer 1dy of the serration 1d of an inner race 1 touches a circular circlip 2c, and an inlet side chamfer 1dz touches a shoulder portion 2e, thereby the inner race 1 and a shaft portion 2 are axially and mutually bound. The chamfer angle thetaz of the inlet side chamfer 1dz is set to 32.5 deg. or less, which is preferably set to 15 deg. or more and 32.5 deg. or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fitting structure for an inner ring and a shaft of a constant velocity universal joint used in automobiles and various industrial machines.

[0002]

2. Description of the Related Art A constant velocity universal joint includes an outer ring having a plurality of axially extending guide grooves formed on its inner peripheral surface, and an inner ring having a plurality of axially extending guide grooves formed on its inner peripheral surface.・ A torque transmitting ball arranged on a ball track formed by the guide groove of the outer ring in cooperation with each other, and a cage for holding the torque transmitting ball in the angle bisector of the operating angle. Usually, a driven shaft (or a drive shaft) is joined to an outer ring, and a shaft part such as a drive shaft (or a driven shaft) or an intermediate shaft is serrated or spline-fitted to an inner ring for use. Then, when an angular displacement occurs between the drive shaft and the driven shaft, the torque transmitting balls are guided by the guide grooves of the inner and outer rings and move in the ball track, so that the inner and outer rings form an operating angle. Corresponds to angular displacement. As is well known, serrations and splines are distinguished by the tooth shape, splines are key-shaped teeth parallel to the axis formed on the outer peripheral surface of the shaft portion at equal intervals, and serrations are spline teeth. It is a small triangular mountain. Since serrations have a low tooth depth and a large number of teeth, they can transmit even greater torque than splines, and splines are generally used for large diameter shafts, whereas serrations are used for small diameter shafts. There are many.

Conventionally, for example, a fitting structure as shown in FIGS. 5 to 7 has been adopted as a fitting structure between an inner ring and a shaft portion of a fixed type constant velocity universal joint.

FIG. 5 shows a so-called two-clip type fitting structure in which the inner ring 11 and the shaft portion 12 are constrained from both sides in the axial direction by a round circlip 13 and a square circlip 14. Torque is transmitted between the inner ring 11 and the shaft portion 12 by engagement between the serrations 11d formed on the inner peripheral surface of the inner ring 11 and the serrations 12d formed on the outer peripheral surface of the shaft end portion of the shaft portion 12. The circular circlip 13 is mounted in the annular groove 12b formed in the shaft end of the shaft 12, and the inner chamfer 11 located on the joint inner side Y of the chamfers at both ends of the serration 11d.
It is in contact with dy. The square circlip 14 is fitted into the cutout portion of the serration 12d and is in contact with the end surface of the inner ring 11 on the joint inlet side Z. The circular circlip 13 is generally a C-shaped ring having a diameter larger than the inner diameter of the serration 11d.
Incorporated into the inner diameter of 1d. Then, in this state, the shaft portion 12
When is pushed, the circular circlip 13 is guided by the inner diameter of the serration 11d together with the shaft portion 12 to move to the inside Y of the joint, and when the inner chamfer 11dy is reached, the diameter is automatically expanded by the restoring force. There is.

FIG. 6 shows a so-called one-clip type fitting structure in which the inner ring 11 and the shaft portion 12 are axially restrained by a single circular circlip 13. The circular circlip 13 is an annular groove 1 formed at the shaft end of the shaft 12.
2b, and is engaged with an annular groove 11b formed on the inner peripheral surface of the inner ring 11.

FIG. 7 shows a so-called one-clip shoulder stop type fitting structure, in which the inner ring 11 and the shaft portion 12 are formed by the circular circlip 13 and the shoulder portion 12e formed on the shaft portion 12 on both sides in the axial direction. Is to be restrained from. Shoulder 12e
Is provided on the axial center side of the serration 12d and faces the axial center side chamfer 12dz of the serration 12d at a distance. The circular circlip 13 is the inner chamfer 1 located inside the joint inner side Y of the serration 11d.
1 dy, and the shoulder 12e abuts on the inlet side chamfer 11dz located on the joint inlet side Z.

[0007]

As a recent tendency, it is important to reduce the size and weight of constant velocity universal joints.
This corresponds to the fact that in the automobile industry, which is the main application of constant velocity universal joints, the weight of the vehicle body is being actively reduced as a part of low fuel consumption. One of the most effective means to reduce the size and weight is to reduce the size by increasing the torque transmission capacity. Further, the constant velocity universal joint is also required to have characteristics such as a high operating angle and low cost.

By the way, the torque transmission capacity of the constant velocity universal joint is practically determined by the strength of the inner ring and the strength of the joint inlet side portion. This is mainly because the inner ring of a fixed type constant velocity universal joint has the thinnest wall thickness of the guide groove on the inlet side, and when the operating angle is applied, the torque transmission ball on the opposite operating angle side guides. This is because the torque is transmitted by moving to the entrance side of the groove. In particular, the higher the operating angle, the closer the torque transmitting ball comes to the vicinity of the entrance, so the maximum operating angle also largely depends on the strength of this portion.

Therefore, regarding the above-mentioned three types of fitting structures, the inner ring 11 and the shaft portion 12 are strong from the viewpoint of size and weight reduction and a high operating angle, and the cost of the inner ring 11.
The following is a brief summary of the assemblability with and each of them (the details will be given later).

[2 clip type shown in FIG. 5]

(1) With respect to the strength of the inner ring 11, structurally,
No special consideration has been paid.

(2) Since the chamfer angle θz of the chamfer 11dz on the inlet side of the serration 11d is 45 degrees, the assembly of the inner ring 11 and the shaft portion 12 cannot be automated.

[1 clip type shown in FIG. 6]

(1) The strength of the inner ring 11 is equal to or higher than that of the two-clip type.

(2) Since the chamfer angle θz of the chamfer 11dz on the inlet side of the serration 11d is 25 degrees, the assembling of the inner ring 11 and the shaft portion 12 can be automated.

[One-clip shoulder type shown in FIG. 7]

(1) The strength of the inner ring 11 is the largest of the three types.

(2) Since the chamfer angle θz of the entrance side chamfer 11dz of the serration 11d is 45 degrees, it is impossible to automate the assembling of the inner ring 11 and the shaft portion 12.

First, comparing the strength of the inner ring 11, the strength of the inner ring 11 is the largest in the one-clip shoulder type. This is for the following reason. That is, when torque is transmitted between the inner ring 11 and the shaft portion 12, the maximum force is generated at the fitting start position between the serrations 11d and 12d. While the joining start position is the entrance side chamfer 11dz of the serration 11d, in the one-clip shoulder type, the shaft center side chamfer 12dz of the serration 12d located on the joint inner side Y than the entrance side chamfer 11dz starts fitting. Be in position. In other words, the one-clip shoulder type has a structure in which the maximum force point enters the joint inner side Y more than the above two types, and the maximum force can be applied to the thicker portion of the inner ring 11. , The strength is greater than other types.

Next, comparing the assembling ability,
Of the above three types, only one clip type can be automatically assembled. This is the chamfer 11d on the entrance side of the serration 11d in the one clip type.
The chamfer angle θz of z is set to a relatively small value of 25 degrees, and when the shaft portion 12 is assembled, the circular circlip 13 is guided by the chamfer 11dz on the inlet side, and is automatically reduced to the required dimension (the inner diameter dimension of the serration 11d). This is because the diameter. However, in the other two types, since the chamfer angle θz of the entrance side chamfer 11dz is set to be relatively large at 45 degrees, the guide by the entrance side chamfer 11dz becomes insufficient when the shaft part 12 is assembled, and the Circlip 13 does not automatically reduce its diameter. for that reason,
With the other two types, automatic assembly is not possible.

As described above, the advantages of the conventional fitting structure are as follows.
There are many disadvantages and there is much room for improvement. Therefore,
An object of the present invention is to overcome the problems in the conventional structure, to achieve the downsizing and weight reduction of the constant velocity universal joint, and to increase the working angle, and at the same time to improve the assembling property.

[0022]

According to a first aspect of the present invention, a constant velocity universal joint is provided in which a plurality of guide grooves extending in the axial direction are formed on the outer peripheral surface and serration or spline tooth patterns are formed on the inner peripheral surface. In the fitting structure of the inner ring and the shaft part where the serration or spline tooth profile that fits the tooth profile of the inner ring is formed on the outer peripheral surface of the shaft end, inside the joint of the chamfers on both ends of the tooth profile of the inner ring Abut the inner chamfer located on the circlip attached to the shaft end of the shaft, and place the inlet chamfer located on the inlet side of the joint on the shoulder provided on the shaft center side rather than the tooth profile of the shaft. The chamfer angle of the inlet side chamfer is 32.5 degrees or less.

According to the invention of claim 2, in the structure of claim 1, the chamfer angle of the chamfer on the inlet side is 15 degrees or more and 3 or more.
It is set to 2.5 degrees or less.

Here, the chamfer angle means an angle formed by the chamfer generatrix and the axis.

[0025]

The fitting structure of the present invention is a so-called one-clip shoulder stopper type, and the inner ring and the shaft portion are axially moved by the circlip mounted on the shaft end portion of the shaft portion and the shoulder portion provided on the shaft center side. Both sides are bound by each other. The shoulder that the chamfer on the inlet side of the tooth profile of the inner ring contacts is provided closer to the center of the shaft than the tooth profile on the shaft, and the fitting start position (maximum force application point) of both tooth models is greater than that on the inlet chamfer. It has entered the inside of the joint. This improves the strength of the inner ring.

The chamfer angle of the chamfer on the inlet side is 32.
The reason why the angle is set to 5 degrees or less is mainly to consider the assembling property. Whether automatic assembly of the inner ring and the shaft is possible depends on the size of the chamfer angle of the chamfer on the entrance side. If this chamfer angle is too large, the circlip does not automatically reduce its diameter when the shaft portion is mounted on the inner peripheral surface of the inner ring, which makes automatic assembly impossible. As a result of many experiments by the applicant, the limit value of the chamfer angle at which automatic assembly is possible is 3
It has been confirmed to be 2.5 degrees. Further, as will be described later, reducing the chamfer angle also improves the strength of the inner ring.

The chamfer angle of the chamfer on the inlet side is set to 15 degrees or more in consideration of the dimensional accuracy of the tooth profile of the inner ring. That is, if the chamfer angle of the inlet chamfer is too small, it becomes difficult to secure the accuracy of the entire width (effective length) of the tooth mold in terms of processing.

[0028]

EXAMPLES Examples of the present invention will be described below.

FIG. 1a shows an inner ring 1 of a fixed type constant velocity universal joint.
And a shaft portion 2 fitted to the inner ring 1. In the figure, the left side is the joint inside side Y and the right side is the joint inlet side Z.

A plurality of guide grooves 1b extending in the axial direction are formed on the outer peripheral surface 1a of the inner ring 1, and serrations 1d are formed on the inner peripheral surface 1c. A chamfer is applied to both ends of the serration 1d. In the figure, the left side is the inner chamfer 1dy located on the joint inner side Y, and the right side is the inlet side chamfer 1dz located on the joint inlet side Z. The chamfer angle θz of the entrance side chamfer 1dz is set to 32.5 degrees or less, preferably 15 degrees or more and 32.5 degrees or less. The chamfer angle θy of the inner chamfer 1dy is not particularly limited,
For example, it is set to 45 degrees. In the present specification, the chamfer angle means an angle formed by the chamfer generatrix with the axis X.

A serration 2d that fits with the serration 1d of the inner ring 1 is formed on the outer peripheral surface 2a of the shaft end portion of the shaft portion 2. An annular groove 2b is formed on the outer peripheral surface 2a of the shaft end portion of the shaft portion 2, and a circular circlip 2c is attached to the annular groove 2b. The circular circlip 2c is, for example, a C-shaped ring, and the outer diameter in its natural state is larger than the inner diameter of the serration 1d of the inner ring 1, and the inner diameter is larger than the outer diameter of the annular groove 2. Further, a shoulder 2e is formed on the shaft center side of the shaft 2 with respect to the serration 2d.
The chamfer 2dz on the axial center of d is opposed to the chamfer 2dz at a distance. The angle θ′z formed by the generatrix of the shoulder portion 2e and the axis X is the same as the chamfer angle θz of the entrance chamfer 1dz.

In FIG. 1b, the shaft portion 2 is incorporated into the inner peripheral surface 1c of the inner ring 1 from the shaft end side, and the serrations 1d and 2
The state which fitted with d is shown. The inner chamfer 1dy of the serration 1d comes into contact with the round circlip 2c, and the inlet chamfer 1dz comes into contact with the shoulder portion 2e, whereby the inner ring 1 and the shaft portion 2 are restrained from each other in the axial direction. .

As shown in the enlarged view of FIG. 2, when the shaft portion 2 is assembled, the circular circlip 2c is moved into the chamfer 1dz on the inlet side.
The diameter is gradually reduced while being guided by and is fitted into the inner diameter of the serration 1d. Then, in that state, the shaft portion 2
Is pushed to the inside Y of the joint, the circular circlip 2c is guided by the inner diameter of the serration 1d and moves to the inside Y of the joint together with the shaft 2, and when it reaches the inner chamfer 1dy, the diameter is automatically expanded by the restoring force. To do. As described above, in the fitting structure of this embodiment, it is not necessary to artificially reduce the diameter of the circular circlip 2c by using a special jig, and the shaft portion 2 is fixed to the inner ring 1
The assembly can be completed automatically simply by inserting it into the inner peripheral surface of the. In order to enable automatic assembly, the chamfer angle θz needs to be 32.5 degrees or less. When the chamfer angle θz is larger than 32.5 degrees, the circular circlip 2c is automatically contracted. Without diameter, automatic assembly becomes impossible. However, if the chamfer angle θz is too small, it becomes difficult to secure the accuracy of the entire width A (effective length: see FIG. 1a) of the serration 11, so it is preferable to set it to 15 degrees or more.

As shown in an enlarged manner in FIG. 3, the chamfer 2dz on the axial center of the serration 2d is located closer to the inside Y of the joint than the chamfer 1dz on the inlet side of the serration 1d. The fitting start position (maximum force application point) P1 of the above is a dimension L1 on the joint inner side Y with respect to the point P2 (in the fitting structure shown in FIGS. 5 and 6, the inlet side chamfer is the maximum force application point).
It's just entering. Since the maximum force can be applied to the thicker portion of the inner ring 1 (the inner side Y of the joint is thicker), the strength of the inner ring 1 is stronger than that of the fitting structure shown in FIGS. 5 and 6. improves. It is effective that the dimension L1 is about 10 to 20% with respect to the entire width A of the serration 1d.

FIG. 4 shows the fitting structure of the present embodiment shown in FIG. 1 (two types of chamfer angle θz: 25 degrees and 32.5 degrees).
The conventional fitting structure shown in FIGS. 5 and 7 (chamfer angle θ
(z: 45 degrees) shows the results of testing the one-sided torsional fatigue strength of the inner ring. As is clear from the figure, in the fitting structure of this embodiment, the torsional strength of the inner ring 1 is significantly improved as compared with the conventional fitting structure. This is because the fitting start position (maximum force application point) P1 between the serration 1d and the serration 2d has entered the joint inner side Y. However, also in the fitting structure of the present embodiment, when the chamfer angle θz is 25.0 degrees and when it is 32.5 degrees, the torsional strength of the inner ring 1 becomes larger when the chamfer angle θz is 25.0 degrees. ing. As described above, when the chamfer angle θz is small, the torsional strength of the inner ring 1 tends to be large. Therefore, the chamfer angle θz of the inlet side chamfer 1dz is directly related not only to the assembling property but also to the torsional strength of the inner ring 1, and it is extremely important to set the value of this.

Although the above embodiment relates to the serration fitting, the present invention can be similarly applied to the spline fitting. Further, the type of the constant velocity universal joint is not limited to the fixed type, but can be applied to the sliding type.
Further, the invention is not limited to the fitting structure between the inner ring of the constant velocity universal joint and the shaft portion, but can be applied to general serration or spline fitting structure.

[0037]

As described above, according to the fitting structure of the present invention, the fitting start position (maximum force applied point) between the inner ring tooth profile and the shaft tooth profile is the inlet side chamfer of the inner ring tooth profile. Since the inner ring is located on the inner side of the joint, and the maximum force is applied to the thicker portion of the inner ring, the strength of the inner ring is improved, which increases the torque transmission capacity of the constant velocity universal joint and the resulting small size. It is possible to achieve a reduction in weight and a high operating angle. At the same time, since the chamfer angle of the chamfer on the inlet side of the inner ring tooth type is set to 32.5 degrees or less, it is possible to automatically assemble the inner ring and the shaft portion, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view (FIG. A) showing an inner ring and a shaft portion related to a fitting structure of an embodiment of the present invention, and a cross-sectional view (FIG. B) showing the fitting structure.

FIG. 2 is an enlarged cross-sectional view around an entrance-side chamfer.

FIG. 3 is an enlarged cross-sectional view around the entrance-side chamfer.

FIG. 4 is a diagram showing the results of a one-sided torsional fatigue strength test of an inner ring.

FIG. 5 is a cross-sectional view (FIG. A) showing an inner ring relating to a conventional fitting structure, and a cross-sectional view (FIG. B) showing the fitting structure.

FIG. 6 is a cross-sectional view (FIG. A) showing an inner ring relating to a conventional fitting structure, and a cross-sectional view (FIG. B) showing the fitting structure.

FIG. 7 is a cross-sectional view (FIG. A) showing an inner ring relating to a conventional fitting structure and a cross-sectional view (FIG. B) showing the fitting structure.

[Explanation of symbols]

 1 inner ring 1a outer peripheral surface 1b guide groove 1c inner peripheral surface 1d serration 1dy inner chamfer 1dz inlet chamfer θz chamfer angle 2 shaft portion 2a shaft end outer peripheral surface 2c round circlip 2d serration 2e shoulder portion

Claims (2)

[Claims] 1. An inner ring of a constant velocity universal joint, wherein a plurality of guide grooves extending in the axial direction are formed on the outer peripheral surface, and serrations or spline-shaped tooth patterns are formed on the inner peripheral surface, and the outer peripheral surface of the shaft end portion is provided with the above-mentioned inner ring. In a fitting structure with a shaft portion formed with serrations or splined tooth molds that fit with a tooth mold of an inner ring, an inner chamfer located on the inner side of the joint among the chamfers at both ends of the tooth mold of the inner ring is the shaft part. The circlip mounted on the shaft end of the shaft, and the inlet side chamfer located on the joint inlet side is contacted with the shoulder provided on the shaft center side with respect to the tooth profile of the shaft. The fitting structure between the inner ring and the shaft portion of the constant velocity universal joint, wherein the chamfer angle of the inlet chamfer is 32.5 degrees or less. 2. A fitting structure between an inner ring and a shaft portion of a constant velocity universal joint, wherein a chamfer angle of the chamfer on the inlet side is 15 degrees or more and 32.5 degrees or less.