JP2533994Y2 - Boot for mechanical shaft coupling - Google Patents

Description

[Detailed description of the invention]

[0001]

In this invention, a bellows portion is provided between a large-diameter ring portion and a small-diameter ring portion, and the bellows portion is composed of the large-diameter ring portion and the first first mountain counted from the large-diameter side. Between the department
The present invention relates to a boot for a mechanical shaft coupling having a first valley portion and receiving a compressive action and a tensile action when a cross-rotational motion of a shaft coupling is performed, for example, a constant velocity type connecting a drive shaft and an axle of an automobile. Boots such as universal joints.

In the present specification, the numbers of the peaks and valleys of the bellows are numbers counted from the large-diameter ring side.

[0003]

2. Description of the Related Art This type of boot for a mechanical shaft coupling (hereinafter referred to simply as a boot) has a large negative force due to a compression action or a tension action at a peak or a valley during the cross-rotational movement of the shaft coupling. Causes positive distortion. This distortion greatly affects the life of the boot.

Therefore, in order to extend the life of boots,
Conventionally, various proposals have been made to reduce the distortion at the peaks and valleys.

For example, it is known that a convex portion is formed on the inner peripheral surface near the top of the crest to substantially maintain the bent shape of the crest of the crest to reduce the distortion of the crest. Kaisho 62-
174122).

It is also known to reduce the surface pressure on the first valley by making the slope of the first valley to the first mountain side thinner than the thickness of the general portion of the bellows. (See Japanese Utility Model Laid-Open No. 62-174121).

[0007] Further, there is a known configuration in which a ridge protruding inward is provided on the inner peripheral surface of the first valley portion on the side of the first ridge portion to reduce the distortion of the second valley portion (Japanese Patent Application Laid-Open No. Sho. 61-236925
Reference).

However, in this type of boot, reducing the strain at the valley, particularly the dynamic strain (the sum of the absolute values of the compressive strain and the tensile strain) at each portion of the first valley, generally reduces the life. It was effective in extending, and there was room for improvement in this regard.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a boot that can reduce the dynamic strain at each portion of the first valley and extend the life.

[0010]

In the boot according to the present invention, a bellows portion is provided between the large-diameter ring portion and the small-diameter ring portion, and the bellows portion is counted from the large-diameter ring portion with respect to the large-diameter side. A first valley between the first valley and the first valley, wherein the first valley is subjected to a compressive action and a tensile action when the shaft joint crosses the rotary motion. A boot for a shaft coupling, wherein a portion near the bottom of the first valley portion is formed thicker than a general portion of the bellows portion, and a slope portion of the first valley portion on the side of the first hill portion is the bellows portion. A step portion is formed at a thin portion side end of the thick portion on the entire inner peripheral surface side of the slope portion on the first peak portion side of the first valley portion. An end of the thick portion on the side of the stepped portion is located at a distance from the bottom of the first valley with a center of an arc surface on an inner peripheral surface side of the bottom in the first valley. Characterized in that it is arranged in a range of to 30 °.

[0011]

In the boot according to the present invention, when a part of the first valley is subjected to a tensile action at the time of cross rotation of the shaft coupling, the slope at the first hill side of the first valley at the time of receiving the tensile action. A step portion is formed at the end of the thin portion of the thick portion on the entire circumference of the inner peripheral surface side, stress concentration occurs at the step portion, and the largest tensile strain is generated at the step portion, and the step portion is formed. Tensile deformation around.

Then, when the shaft coupling rotates and a part of the first valley is subjected to a compressive action, the bottom of the first valley is subjected to the largest compressive strain, and the bottom is removed. Compression deformation to the center. At this time, the arrangement portion of the step portion is shifted from the bottom of the first valley portion to the slope portion on the first mountain portion side, and the step portion is arranged on the inner peripheral surface side of the first valley portion. Since the outer peripheral surface side of the portion is formed gently, it does not bend at the step portion and generate the largest compressive strain at the step portion.

Therefore, in the boot according to the present invention,
At the time of cross rotation of the shaft coupling, in the first valley, the portion where the maximum tensile strain is generated is the portion of the step portion, and the portion where the maximum compressive strain is generated is the bottom portion, and the maximum tensile strain and the maximum compressive strain are compared. Since the generated portions can be shifted, the dynamic strain of the first valley can be reduced at each portion, and the life can be extended.

The stepped portion is formed at an angle of 10 ° with respect to the center of the arc surface on the inner peripheral surface side of the bottom of the first valley.
If it is less than this, the step portion that generates the maximum tensile strain and the bottom portion that generates the maximum compressive strain are too close to each other, and cannot contribute much to the reduction of the dynamic strain at each part.

Further, the stepped portion is formed at an angle of 30 ° from the bottom with respect to the center of the arc surface on the inner peripheral surface side of the bottom in the first valley.
If it is arranged in a range exceeding, the thick portion comes into contact with the second valley portion, so that it becomes impossible to reduce wear resistance and contribute to extending the life.

[0016]

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

The boot 5 of the embodiment shown in FIGS. 1 to 3 is made of rubber, such as NR, NBR, SBR, BR, and CR, and TPE, such as urethane, vinyl, polyester, and polyolefin, as in the prior art. A large-diameter ring portion 6, a small-diameter ring portion 7, and a bellows portion 8 disposed between the large-diameter ring portion 6 and the small-diameter ring portion 7;
It has.

The bellows portion 8 is formed between the large-diameter ring portion 6 and the first first hill portion 11 counted from the large-diameter side.
1 is provided.

1 is a drive shaft, 2 is an axle, 3 is a shaft coupling, and 4 is a socket.

In the boot 5 of this embodiment, the first
The vicinity of the bottom 21a of the valley portion 21 is formed thicker than the general portion 9 of the bellows portion 8, and the slope 21b of the first valley portion 21 on the first mountain portion 11 side is thinner than the general portion 9 of the bellows portion 8. Is formed. In addition, the general portion 9 of the bellows portion 8 is a mountain portion after the first mountain portion 11 (the first mountain portion 11, the second mountain portion 12, the third mountain portion 1).
3) and valleys (the second valley 22 and the third valley 23).

Incidentally, in the case of the embodiment, the thickness t1 of the thick portion 25 is set to 2, the thickness t2 of the thin portion 26 is set to 0.8, and the thickness t3 of the general portion 9 is set to 1. .

A step 27 is formed at the end of the thick portion 25 on the thin portion 26 side on the entire inner peripheral surface side of the slope 21 b of the first valley 21 on the first peak 11 side. I have.

The end of the thick portion 25 on the side of the step portion 27 is 10 to 30 ° from the bottom 21a about the center O of the arc surface on the inner peripheral surface side of the bottom 21a in the first valley 21.
Are arranged in the range.

In the case of the embodiment, the arrangement angle θ1 of the terminal end of the thick portion 25 on the side of the step portion 27 is set to 20 °.

FIGS. 3, 4 and 5 show the case where the joint angles θ2 of the drive shaft 1 are 33 °, 41 ° and 20 °, respectively.

In the boot 5 configured as described above, when a part of the first valley portion 11 receives a tensile action during the cross rotation of the shaft coupling 3 during use (see the right side of FIG. 3), the first valley is formed. A step 27 is formed at the end of the thick portion 25 on the side of the thin portion 26 on the entire inner circumferential surface side of the slope 21 b on the first mountain portion 11 side of the portion 21.
Is formed, and stress concentration occurs in the step portion 27,
While the largest tensile strain is generated in the step portion 27, the step portion 27 is tensilely deformed around the step portion 27.

Thereafter, when the shaft coupling 3 rotates and a part of the first valley portion 21 is subjected to a compressive action (see the left side of FIG. 3), one portion of the first valley portion 21 is brought into contact with the bottom 21a of the first valley portion 21. While undergoing the greatest compression strain, it is compressed and deformed around its bottom 21a. At this time, the location of the step 27 is the bottom 21 of the first valley 21.
a to the slope 21 b on the side of the first peak 11, the step 27 is arranged on the inner peripheral side of the first valley 21, and the outer peripheral side of the first valley 21 is formed gently. As a result, it does not bend at the step 27 and cause the largest compressive strain in the step 27.

Therefore, in the boot 5 of the embodiment, when the shaft joint 3 rotates crosswise, in the first valley portion 21, the portion where the maximum tensile strain occurs becomes the portion of the step portion 27, and the maximum compressive strain is reduced. Since the generated portion is the bottom 21a, the portion where the maximum tensile strain and the maximum compressive strain occur can be shifted,
The dynamic strain of the first valley 21 can be reduced at each part,
Life can be extended.

If the step portion 27 is arranged at less than 10 ° from the bottom 21a with respect to the center O of the circular arc surface on the inner peripheral surface side of the bottom 21a in the first valley portion 21, the step causing the maximum tensile strain is generated. The portion 27 and the bottom portion 21a that generates the maximum compressive strain are too close to each other, and cannot contribute much to the reduction of the dynamic strain.

When the step portion 27 is arranged within a range of more than 30 ° from the bottom centering on the center O of the arc surface on the inner peripheral surface side of the bottom portion 21a in the first valley portion 21, the thick portion 25 is formed. It comes into contact with the second valley portion 22, lowering the wear resistance and making it impossible to contribute to extending the life.

When the arrangement angle θ1 of the terminal end of the thick portion 25 on the side of the step portion 27 is set to 20 ° as shown in FIG. 1, 0 ° as shown in FIG. As shown in the figure, when the wall thickness is gradually reduced without providing the step portion 27, the first case in the boot 1
FIG. 8 shows a graph in which a large number of small balls B are bonded in the axial direction on the outer peripheral surface of the valley 21 and displacement of the distance between the small balls B is examined.

In the graph of FIG. 8, the reason why the joint angle θ2 is set to 26 ° smaller than 41 ° on the tensile strain side on the compression strain side is that the joint angle θ2 is smaller on the compression side of the first valley. If it is too large, the displacement cannot be measured.

As can be seen from this graph, the arrangement angle θ
If 1 is set to 0 ° or the step 27 is not provided, the portions where the maximum compressive strain and the maximum tensile strain are generated substantially coincide with or approach to each other, so that dynamic strain cannot be reduced. On the other hand, when the arrangement angle θ2 is set to 20 °, the portions where the maximum compressive strain and the maximum tensile strain occur are separated,
It can be understood that the dynamic distortion can be effectively reduced.

Further, Table 1 shows the results of endurance tests of boots in which the arrangement angle θ1 of the step portion 27 is variously changed and a boot having the shape shown in FIG. 7 without the step portion 27.

The boots were made of CR, grease was sealed, and a durability test was performed at the same ambient temperature at a rotational speed of the shaft coupling of 300 rpm.

[0036]

[Table 1]

As can be seen from Table 1, in the case of the boot in which the arrangement angle θ1 is in the range of 10 to 30 °, the step 2
The life is extended by 20% or more compared to the type without 7.

In the embodiment, the bellows 8 has a type having three peaks and three valleys, but the number of peaks and the like may be four or five.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part showing an embodiment of a boot according to the present invention.

FIG. 2 is a half sectional view showing a use mode of the embodiment.

FIG. 3 is a cross-sectional view showing a use mode of the embodiment when the joint angle is 31 °.

FIG. 4 is a cross-sectional view showing a use mode of the embodiment when the joint angle is 41 °.

FIG. 5 is a cross-sectional view showing a usage mode of the embodiment when the joint angle is 20 °.

FIG. 6 is a partial cross-sectional view of the boot when the arrangement angle of the terminal end of the thick portion on the step portion side is set to 0 °.

FIG. 7 is a partial cross-sectional view of the boot when no step is provided.

FIG. 8 is a graph showing compression strain and tensile strain.

[Explanation of symbols]

 3 ... Shaft coupling, 5 ... Boot, 6 ... Large-diameter ring part, 7 ... Small-diameter ring part, 8 ... Bellows part, 9 ... General part, 11 ... First ridge part, 21 ... First valley part, 21a ... Bottom part 21b: slope portion, 25: thick portion, 26: thin portion, 27: step portion, θ1: arrangement angle.

Claims (1)

(57) [Scope of request for utility model registration] 1. A bellows portion is formed between a large-diameter ring portion and a small-diameter ring portion, and the bellows portion is formed between the large-diameter ring portion and a first first peak portion counted from a large-diameter side. A boot for a mechanical shaft coupling made of a polymer elastic material, wherein the first valley is subjected to a compressive action and a tensile action when the shaft joint cross-rotates. The vicinity of the bottom of the valley is formed to be thicker than the general portion of the bellows portion, and the slope portion on the first mountain side of the first valley portion is formed to be thinner than the general portion of the bellows portion. A step portion is formed at the end of the thick portion at the thin portion side end of the entire inner peripheral surface side of the slope portion of the first valley portion on the side of the first mountain portion, and the end of the thick portion at the step portion side is formed. , The first
A boot for a mechanical shaft coupling, wherein the boot is arranged within a range of 10 to 30 degrees from the bottom with respect to the center of the arc surface on the inner peripheral surface side of the bottom in the valley.