JPH10299789A - Flexible boot for constant velocity joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To devise a small boot without lowering durability by specifying the shapes of the third angle and the third valley of a bellows part. SOLUTION: A boot 11 is used for a small constant velocity joint in which a difference of the diameter D1 of a boots fixing part of the outer race of a joint 15 and the diameter D2 of a shaft 17 is 60 mm or below. The boots 11 has a bellows part 12 on the intermediate part and small opening mounting part 13 and large opening mounting part 14 provided at both the ends. The bellows part 12 is constituted of a first angle 12a, a first valley 12b, a second angle 12c, a second valley 12d, a third angle 12e and a third valley 12f from the side of the small opening mounting part 13. A reference location which is abutted on the end face of the outer race of the joint 15 is determined for O, and a distance (b) up to the center of the third valley 12f from this reference location O for a distance (a) up to the center of the third angle 12e on the large opening side of the bellows part 12 from the reference location is set to a ratio of 30% to 40%. Therefore, deformation stress of the third valley 12f which is the largest in deformation can be mitigated and contact of angles each other at the time of compression can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible boot for a small constant velocity joint in which the difference between the diameter of the boot fixing portion of the outer ring of the constant velocity joint used for the drive shaft of an automobile and the diameter of the shaft is 60 mm or less. About.

[0002]

2. Description of the Related Art Conventionally, a flexible boot used for a constant velocity joint of this type is generally made of rubber and has a shape of three ridges and three valleys which is advantageous in expansion, contraction, abrasion, deformation by centrifugal force, and the like. ing. FIG. 4 shows an example of a conventional small constant velocity joint. The boot 1 has a bellows portion 2 at an intermediate portion, and a small-diameter mounting portion 3 and a large-diameter mounting portion 4 provided at both ends thereof. The bellows portion 2 includes a first peak 2a, a first valley 2b, a second peak 2c, a second valley 2d, a third peak 2e, and a third valley 2f from the small-diameter mounting portion 3 side. The large-diameter mounting part 4
The band 6 is fixed to the outer ring 5 a of the joint 5, and the small-diameter mounting portion 3 is fixed to the shaft 7 by the band 8. The tip of the shaft 7 is fixed to the inner ring of the joint 5. The interior space 9 of the boot 1 is filled with grease to lubricate the joint 5.

[0003]

However, recently, with the reduction in the weight of the vehicle and the size of the engine room, the size and weight of flexible boots have been required to be reduced. However, when the bellows deployment length is insufficient and the operating angle is high, the expansion ratio increases, and the durability decreases. In addition, when it is shrunk in the axial direction, the pitch between the peaks and valleys becomes small, and there is a problem that contact wear occurs during compression and durability decreases. Furthermore, the difference between the diameter of the boot fixing portion of the outer ring of the joint and the diameter of the shaft is 60 mm.
In the following small constant velocity joints, the distance between the shaft and the valley is extremely short, and it has been difficult to further reduce the size.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a flexible boot for a constant velocity joint that can be reduced in size without reducing durability.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a small-sized constant velocity joint in which the difference between the diameter of the boot fixing portion of the outer ring of the joint connected to the shaft and the diameter of the shaft is 60 mm or less. And a small-diameter attachment portion attached to the shaft at one end, and a large-diameter attachment portion attached to the outer ring of the joint at the other end. , A second valley, a third peak, a flexible boot having a bellows portion having a third valley,
The reference position that abuts on the end face of the outer ring of the joint is O,
The distance b from the reference position O to the center of the third valley is set at a ratio of 30% to 40% with respect to the distance a from the center of the third peak on the large diameter side of the bellows.

According to the present invention, the intersection angle θ ₁ between the virtual extension line connecting the inner peripheral surface of the first valley and the inner peripheral surface of the second valley on the small diameter side of the bellows portion and the center line of the boot is set to 10 to 15 degrees. And the diameter d ₁ of the inner peripheral surface of the third valley is set to be larger than the diameter d ₂ of the inner peripheral surface of the second valley.

[0007] The present invention also includes a 30-degree crossing angle theta ₂ between the virtual extension line and the boot center line connecting the outer peripheral surface and the outer peripheral surface of the second mountain of the small-diameter-side first crest of the bellows portion 20 degrees In addition, the outer peripheral surface of the third mountain is set radially inward of the virtual extension line.

The present invention is further characterized in that the opening angle θ ₃ of the outer peripheral surface of the second valley of the bellows portion is from 50 degrees to 65 degrees.

[0009]

FIG. 1 shows a boot according to an embodiment of the present invention. The boot 11 is made of an elastic material such as chloroprene rubber, and has a bellows portion 12 at an intermediate portion, small-diameter attachment portions 13 and large-diameter attachment portions 1 provided at both ends thereof.
And 4. The bellows portion 12 includes a first peak 12a, a first valley 12b, a second peak 12c, a second valley 12d, a third peak 12e, and a third valley 12f from the small-diameter mounting portion 13 side. The large-diameter mounting portion 14 is fixed to an outer ring of the joint 15 by a band 16, and the small-diameter mounting portion 13 is fixed to a shaft 17 by a band 18. The tip of the shaft 17 is fixed to the inner ring of the joint 15.

The difference between the diameter D ₁ of the boot fixing portion of the outer ring of the joint 15 and the diameter D _{2 of the} shaft 17 is 60 in the boot 11.
As shown in FIG. 2, a reference position which is used for a small constant velocity joint having a diameter equal to or less than 1 mm and abuts on an end surface of an outer ring of the joint 15 is defined as O. The distance b to the center of the third valley 12f is set to 30% to 40% of the distance a to the center. For this reason, even if the length of the bellows portion 12 of the boot 11 is shortened, the dimension required for the third valley 12f is secured, and the deformation stress of the third valley 12f, which is the largest deformed by the operation of the joint 15, can be reduced. In addition, the contact between the peaks during compression can be reduced. If the ratio of b / a is larger than 40%, stress concentrates on the third valley 12f during compression. If b / a is less than 30%, the third valley 12f during compression
May be pinched between the shaft 17 and the joint 15.

The intersection angle θ ₁ between the virtual extension line connecting the inner peripheral surface of the first valley 12b on the small diameter side of the bellows portion 12 and the inner peripheral surface of the second valley 12d and the center line C of the boot is set to 10 degrees. with a 15 °, the diameter d ₁ of the inner peripheral surface of the third valley 12f is is made larger than the diameter d ₂ of the inner circumferential surface of the second trough 12d. For this reason, even if the boot 11 is downsized in the radial direction, the shaft 1
7 can be prevented from contacting. When crossing angle theta ₁ is less than 10 degrees, the distance is too short between the valley and the shaft 17, the valley portion during compression high risk of contact with the shaft 17. Further, when the crossing angle theta ₁ is greater than 15 degrees, not only can not be miniaturized boot 11, sufficient bellows developed length is obtained, or expansion due to the rotation, there is a risk of deformation.

Further, the first peak 12a on the small diameter side of the bellows portion 12
The intersection angle θ ₂ between the virtual extension line connecting the outer peripheral surface of the second mountain 12c and the outer peripheral surface of the second mountain 12c and the center line C of the boot is set to 20 ° to 30 °, and the outer peripheral surface of the third mountain 12e is virtually extended. It is set radially inward from the line. For this reason, even if the boot 11 is reduced in size in the radial direction, a required bellows deployment length can be obtained. If the crossing angle θ ₂ is smaller than 20 degrees, a sufficient bellows deployment length cannot be obtained, or the valleys are not aligned with the axis 1 during compression.
There is a high risk of contact with 7. If the intersection angle θ ₂ is larger than 30 degrees, not only the boot 11 cannot be reduced in size, but also there is a risk of expansion and deformation due to rotation.

Further, the second valley 1 on the small diameter side of the bellows portion 12 is formed.
The opening angle θ ₃ of the outer peripheral surface of 2d is set to be from 50 degrees to 65 degrees. For this reason, even if the boot 11 is downsized, the contact between the second ridge 12c and the third ridge 12e, which is most likely to come into contact during compression, can be reduced. If the opening angle θ ₃ is smaller than 50 degrees, the above-mentioned effects cannot be sufficiently obtained. If the opening angle θ ₃ is larger than 65 degrees, the boot 11 cannot be downsized, or abnormal contact occurs at other portions.

FIG. 3 shows a dimensional ratio b / a in this embodiment.
5 is an experimental example in which the relationship between the time and the endurance time is obtained. The boots used were 70 mm in total length, 62 mm in joint diameter, and 1 shaft diameter.
7.5 mm, θ ₁ = 15 degrees, θ ₂ = 30 degrees, θ ₃ = 60
The ambient temperature was RT (room temperature), the operating angle was 40 degrees, the number of revolutions was 600 rpm, and the number of samples was three. As is clear from this figure, it has been proved that the dimensional ratio b / a is preferably in the range of 30% to 40%.

[0015]

As described above, according to the present invention, by setting the shape of the bellows of three peaks and three valleys as described above, it is possible to reduce the size of the constant velocity joint without reducing the durability. Flexible boot can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a flexible boot for a constant velocity joint according to an embodiment of the present invention, together with a joint.

FIG. 2 is a sectional view of a flexible boot for a constant velocity joint according to the embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a relationship between a dimensional ratio b / a and a durability time in the embodiment of the present invention.

FIG. 4 is a sectional view of a conventional flexible boot for a constant velocity joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Boot 12 Bellows part 12a 1st ridge 12b 1st valley 12c 2nd ridge 12d 2nd valley 12e 3rd ridge 12f 3rd valley 13 Small diameter attachment part 14 Large diameter attachment part 15 Joint 16 Band 17 Shaft 18 Band

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Shinichi Uda 2-4-36 Tsujido Shindai, Fujisawa-shi, Kanagawa Inside Keeper Corporation

Claims (4)

[Claims] 1. A small-diameter constant velocity joint for use in a small constant velocity joint in which a difference between a diameter of a boot fixing portion of an outer race of a joint coupled to a shaft and a diameter of the shaft is 60 mm or less, and one end of which is attached to the shaft. A large-diameter attachment portion attached to the outer ring of the joint at the other end, and a first crest, a first valley, a second crest, and a second crest are provided between the two attachment portions from the smaller diameter side.
In a flexible boot having a valley, a third crest, and a bellows portion having a third valley, a reference position abutting on the end surface of the outer ring of the joint is defined as O, and from this reference position O, the center of the third ridge on the large diameter side of the bellows portion. A flexible boot characterized in that a distance b to the center of the third valley is set at a ratio of 30% to 40% with respect to a distance a to the third valley. 2. An intersection angle θ ₁ between a virtual extension line connecting the inner peripheral surface of the first valley on the small diameter side of the bellows portion and the inner peripheral surface of the second valley and the center line of the boot is set to 10 to 15 degrees. with flexible boot according to claim 1, characterized in that the diameter d ₁ of the inner peripheral surface of the third valley has been set larger than the diameter d ₂ the inner peripheral surface of the second trough. 3. An intersection angle θ ₂ between a virtual extension line connecting the outer peripheral surface of the first mountain on the small diameter side of the bellows portion and the outer peripheral surface of the second mountain and the center line of the boot is set to 20 to 30 degrees. The flexible boot according to claim 1, wherein an outer peripheral surface of the third mountain is set radially inward of the virtual extension line. 4. The flexible boot according to claim 1, wherein the opening angle θ ₃ of the outer peripheral surface of the second valley of the bellows portion is set to 50 ° to 65 °.