JPH06129535A - Boot - Google Patents

Abstract

PURPOSE:To improve durability by preventing a crack caused by hard friction between the walls of a bellows part, which are in close proximities to one another. CONSTITUTION:A boot 1 is formed of a relatively strong elastic material of tensile elastic modulus of 100-1000Kg/cm<2>. A large diameter fixed part 3 and a small diameter fixed part 4 fixed densely to an outer ring 6 of a constant velocity joint 5 and a shaft 7, are provided on both ends of a bellows part 2. The bellows part 2 comprises the crest part of seven ridges. Tilted sides 11, 12 that are in close proximities to one another of a third crest 8c and a fourth crest 8d from the large diameter fixed part 3 have the slopes of almost the same length.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to boots for covering constant velocity joints of automobiles.

[0002]

2. Description of the Related Art Conventionally, boots for constant velocity joints of automobiles are known such as those disclosed in Japanese Utility Model Laid-Open No. 63-25824.

[0003]

Generally, a boot for a constant velocity joint of an automobile has a rotational speed of 2 minutes per minute when it is used.
It has a high rotation speed of 000 rotations and a bending angle of 40
A high degree of flexion may occur.

Therefore, in the conventional boot for a constant velocity joint as described in the above publication, at the time of high bending,
Since the walls of the bellows adjacent to each other repeatedly come into contact with each other and rub against each other repeatedly, cracks easily occur and the durability is poor.

In view of the above problems, the present invention can preferentially bend a portion of the whole bellows portion that is most likely to bend to cope with high bending, and the walls of the bent portion that are adjacent to each other. The contact surface pressure that preferentially contacts at the time of high bending is increased by increasing the area of the contact area, while preventing the occurrence of cracks due to violent rubbing of the adjacent oblique sides of the bellows part for that contact. An object of the present invention is to provide a boot for a constant velocity joint of an automobile, which can improve durability.

[0006]

The present invention has the following constitution to achieve the above object. That is, the boot according to the present invention has a tensile elastic modulus (JIS K6301) of 10
It is composed of an elastic material having a relatively large strength of 0 to 1000 kg / cm ² , and has a large diameter fixing portion and a small diameter fixing portion that are tightly fixed to the outer ring and the shaft of the joint at both ends of the bellows portion of an automobile, etc. In the boot for a quick joint, the bellows portion has 6 to 8 peaks, and the oblique sides of the third and fourth peaks adjacent to each other, which are counted from the large-diameter fixed portion, are slopes having substantially the same length. . The preferred number of mountains is 6 to 7.
It is a mountain. The length of the hypotenuse is the total length from the top of the mountain to the base of the valley.

[0007]

The boot according to the present invention has a tensile elastic modulus of 1
Since it is made of an elastic material having a relatively high strength of 0 to 1000 Kg / cm ² , the operating environment is 80 to
The temperature is as high as 100 ° C, and the number of rotations is 200 per minute.
Even at 0 rotation and high speed rotation, excessive expansion deformation does not occur as a whole. Furthermore, since the bellows part is composed of 6 to 8 peaks, and the adjacent hypotenuses between the 3rd and 4th peaks counting from the large-diameter fixing part form slopes of substantially the same length, At a high bend of 40 degrees or more, that portion preferentially bends largely, and the bellows as a whole sufficiently corresponds to a high bend state. Then, even if the hypotenuses between the third mountain and the fourth mountain counted from the large-diameter fixing portion are bent and come into contact with each other during high flexion, the hypotenuse has a large contact area. Therefore, the contact is made with a low surface pressure, and the bending of other portions is suppressed. Therefore, even when highly bent, the adjacent oblique sides of the bellows part do not irregularly contact and rub against each other violently. If the tensile modulus is less than 100 Kg / cm ² ,
Large expansion in the outer peripheral direction, 1000 kg / cm ²
If it exceeds, the elasticity of the boot is impaired, not only the load on the constant velocity joint increases, but also an unreasonable strain is applied to the bellows portion of the boot, and cracks or cracks occur at the valley portion. If the number of crests is less than 6, the outer side of the bend due to the rocking of the constant velocity joint does not respond to the bending. To be

[0008]

1 shows an embodiment of the invention.
Reference numeral 1 is a boot for a constant velocity joint of an automobile. The boot 1 is formed by blow molding, injection molding, or injection blow molding of a single or a blend of a thermoplastic synthetic resin elastomer such as a polyester type, a polyurethane type, a polyamide type, or a polyolefin type into a single layer or a multi-layered form. At one end of the bellows portion 2, a cylindrical large-diameter fixing portion 3
And a cylindrical small-diameter fixing portion 4 is integrally formed at the other end. The large-diameter fixed portion 3 and the small-diameter fixed portion 4 are closely fixed to the outer ring 6 and the shaft 7 of the constant velocity joint 5, respectively.

The bellows portion 2 of the boot 1 has a mountain portion 8 (8a).
.About.8 g) and valleys 9 (9a to 9f) are alternately formed, and the bellows 2 has a shape in which the peak diameter is reduced in order from the large diameter fixing portion 3 side to the small diameter fixing portion 4 side. The tops of the six peaks 8 (8b to 8g) excluding the peaks are formed so as to be on the straight line L, and the peaks 8 are 7 peaks and the valleys 9 are 6 peaks. An indented annular groove 10 is formed in the first to fifth valleys 9a to 9e of the valley 9 of the bellows 2.

Third from the large-diameter fixing portion 3 side of the bellows portion 3
As shown in FIG. 1, the hypotenuses 11 and 12 between the ridge 8c and the fourth ridge 8d are formed to have substantially the same lengths m and n in the inclination direction and the longest length compared to the other hypotenuses. Has been done. Therefore, the hypotenuses 11 and 12 have the largest area than the other parts of the bellows part 2. 13 and 14 are fasteners.

The thermoplastic synthetic resin elastomer constituting the boot 1 has a tensile elastic modulus of 100 to 1000 Kg / cm.
² is an elastic material having a relatively high strength. The ridges 8 of the bellows portion 2 need to be 6 to 8 ridges. In this way, by setting the mountain portion 8 to 6 to 8 mountains, 40
It can be used even when the bending is high. Yamabe 8
When the number of peaks is less than 6 peaks, the outside of the bend does not correspond to the bending, and when the number of peaks exceeds 8 on the other hand, the valleys 9 of the inside of the bend contact each other to prevent the bellows from bending.

As described above, the boot 1 shown as the embodiment of the present invention is made of an elastic material having a comparatively large tensile strength of 100 to 1000 Kg / cm ² . Even if the environment in which the boot is used is at a high temperature of 80 to 100 ° C. and the rotation speed is 2000 rpm, it does not cause excessive expansion deformation as a whole, and the bellows Since the part 2 is composed of 7 ridges, it is sufficiently compatible with high bending of 40 degrees or more. Furthermore, the bellows portion 2 is made up of seven peaks as described above, and the third peak 8c and the fourth peak 8d are counted from the large-diameter fixing portion 3.
Since the oblique sides 11 and 12 adjacent to each other between and have substantially the same lengths m and n in the inclination direction and form the longest slopes as compared with the other oblique sides, the parts are bent at a high bending of 40 degrees or more. As a whole, the bellows portion 2 is largely bent, and the bellows portion 2 as a whole can sufficiently cope with a high bending state. The hypotenuse 1 between the third crest 8c and the fourth crest 8d counted from the large-diameter fixing portion 3
Even if the parts 1 and 12 bend and contact each other preferentially during high flexion, even if the hypotenuses 11 and 12 have a large area, even if they contact as shown in FIGS. 2 and 3, The contact surface pressure is kept low, and bending of other portions is suppressed. Therefore, even when highly bent, the adjacent walls of the bellows portion 2 do not irregularly contact and rub violently, and the occurrence of cracks is prevented.

If the tensile elastic modulus is less than 100 Kg / cm ² , expansion in the outer peripheral direction is large, and 1000 Kg / g.
If it exceeds / cm ² , the elasticity of the boot is impaired, the load on the constant velocity joint increases, and unreasonable strain is applied to the bellows of the boot, causing cracks and cracks in the valleys. If the number of peaks 8 is less than 6 peaks, the outside of the bend due to the swinging of the constant velocity joint 5 does not correspond to the bending. On the contrary, if the number of peaks exceeds 8 the adjacent valleys 9 of the inside of the bend contact each other. Bending is hindered. First valley 9a to fifth valley 9e
The bendability can be further improved by forming the reentrant annular groove 10 in the.

[0014]

EFFECTS OF THE INVENTION According to the present invention, it is possible to preferentially bend a portion of the whole bellows portion that is most likely to bend to cope with high bending, and increase the contact area between adjacent walls of the bending portion. While maintaining a low contact surface pressure that preferentially contacts at the time of high bending, the contact prevents the adjacent walls of the bellows part from contacting and rubbing violently, preventing the occurrence of cracks and improving durability. It is possible to obtain a boot for a constant velocity joint of an automobile which is greatly improved.

[Brief description of drawings]

FIG. 1 is an overall front view in which a part of a boot according to the present invention is cut away.

FIG. 2 is a side view showing a mode in which the boot according to the present invention is attached to a constant velocity joint of an automobile.

FIG. 3 is a vertical sectional front view showing a part of FIG. 2 in an enlarged manner.

[Explanation of symbols]

1 boot 2 bellows part 3 large diameter fixing part 4 small diameter fixing part 5 constant velocity joint 6 outer ring 7 shaft 8 crest part 8c third crest part 8e fourth crest part 9 trough part 11, 12 third crest part and fourth crest part Hypotenuses adjacent to each other

Claims (1)

[Claims] 1. A tensile elastic modulus of 100 to 1000 kg / c.
A constant velocity joint for automobiles, which is made of an elastic material having a relatively large strength of m ² and has a large diameter fixing portion and a small diameter fixing portion that are tightly fixed to the outer ring and the shaft of the joint at both ends of the bellows portion. In the boot, the bellows portion has 6 to 8 peaks, and the oblique sides of the third peak and the fourth peak adjacent to each other, which are counted from the large-diameter fixed portion, are slopes having substantially the same length.