JPH04300464A - Boot - Google Patents

Abstract

PURPOSE:To improve flexuosity, elasticity, and also durability of a bellows part used as a boot for constant velocity joint suspension, operating device and the like of an automobile. CONSTITUTION:A bellows 2 of a boot 1 made of an elastomer of a thermoplastic resin is constituted to have six or more crest portions 10 and five or more recessed portions 11. The boot 1 is of a constitution such that at least three of the six or more crest portions 10 have an angle delta of 34 deg. to 90 deg. on the large diameter side and an angle gamma of 0 deg. to 56 deg. on the small diameter side both relative to a perpendicular line (c) drawn downward from the peak portion to an axis (b) of the bellows 2 and setting it as delta>gamma.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cover boots for constant velocity joints, suspension boots, steering system boots, etc. of automobiles.

0002

[Prior Art] Boots for constant velocity joints of automobiles made of thermoplastic synthetic resin elastomer were disclosed in Japanese Patent Application Laid-Open No. 64-8
The one described in Japanese Patent No. 7972 is known.

Hitherto, rubber boots have been widely used for constant velocity joints in automobiles because of their excellent elasticity. However, while rubber products have excellent elasticity, they are not durable enough, so products made of durable thermoplastic synthetic resin elastomer are used, especially for constant velocity joints that rotate at high speed. It has come to be widely used as boots.

0004

[Problem to be Solved by the Invention] In the boot described in the above publication, a perpendicular line is drawn from the top of the peak of the bellows portion to the axis, and the angles formed by both peak walls with respect to the perpendicular are equal angles. Therefore, the expansion and contraction of both mountain walls with respect to the perpendicular line tends to change at the same angle. However, in this type of boot, which has a large-diameter fixed part and a small-diameter fixed part, the length of both mountain walls is Since the wall on the small diameter side is larger, the balance during expansion and contraction is lost. For this reason, especially when the boot is rotating at high speed, smooth elasticity cannot be obtained, resulting in unreasonable deformation and strain, which has the disadvantage of causing cracks in a short period of time.

The present invention solves the above-mentioned drawbacks, and even if the boot is constructed by blow-molding a thermoplastic synthetic resin elastomer, it has excellent elasticity and flexibility as a whole. In particular, the object is to provide a highly durable boot for constant velocity joints in automobiles that rotate at high speed.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention is constructed as follows. That is, in a boot that is constructed by blow molding an elastomer made of thermoplastic synthetic resin and has a large-diameter fixed part at one end of the bellows part and a small-diameter fixed part at the other end, the bellows part between the large-diameter fixed part and the small-diameter fixed part is configured to have six or more peaks and five or more valleys, and the angle α between the axis and the straight line connecting the inner end of the large-diameter fixed part and the inner end of the small-diameter fixed part is 15 to 30 degrees. , the angle δ on the large diameter side of at least three or more of the six or more peaks with respect to the perpendicular drawn from the top of the peak to the axis of the bellows part.
is 34 to 90 degrees, the angle γ on the small diameter side is in the range of 0 to 56 degrees, and the angle δ on the large diameter side is larger than the angle γ on the small diameter side, and furthermore, the large diameter fixed part is followed by a peak part. The boots are characterized by the fact that they are formed.

[0007]

[Function] According to the boot according to the present invention, the bellows portion is composed of six or more peaks and five or more valleys, and the straight line connecting the inner end of the large-diameter fixed portion and the inner end of the small-diameter fixed portion and the axis line The angle with
Since the angle is 30 degrees, the small diameter side is folded into the large diameter side first, centering on the trough, and the bellows part smoothly follows and bends even during high speed rotation, and its overall elasticity is In good condition. In addition, at least three of the six or more peaks have an angle δ of 34 to 90 degrees on the large diameter side with respect to a perpendicular drawn from the top of the peak to the axis of the bellows part, and an angle δ of 34 to 90 degrees on the small diameter side. Since the angle γ is in the range of 0 to 56 degrees and δ>γ, when bending, the wall on the small diameter side on the inside of the bend is folded into the bellows part centering on the trough, and when rotating at high speed. Operates smoothly. On the outside of the bend, the elongation can be absorbed by the wall on the small diameter side, and as a result, the angles of the walls on the large and small diameter sides with respect to the perpendicular are approximately the same, making bending smooth during high-speed rotation. It will be activated. Furthermore, since the bellows part is formed so that it starts from the peak part following the large-diameter fixed part, the distance between the bellows part and the axis can be increased, and the bellows part comes into contact with the axis of the constant velocity joint when bending. There is no risk of damage.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a boot for a constant velocity joint of an automobile. The boot 1 is made by blow molding an elastomer made of thermoplastic synthetic resin, and is integrally formed with a large-diameter fixing part 3 at one end of the bellows part 2 and a small-diameter fixing part 4 at the other end. . 5 is a constant velocity joint, 6 is its outer ring, and 7 is a shaft portion. The large diameter fixed portion 3 of the boot 1 is fitted to the outer ring 6, and the small diameter fixed portion 4 is fitted to the shaft portion 7, and their outer peripheral surfaces are fitted. are tightened by annular tightening bands 8 and 9, respectively.

The bellows portion 2 of the boot 1 has a large diameter fixing portion 3.
The shape has six ridges 10 and five troughs 11 in the direction from the small diameter fixed portion 4. The bellows portion 2 has a shape in which the large-diameter fixed portion 3 side starts from the first peak portion 10 instead of from the valley portion.

In the bellows portion 2, a straight line a connecting the inner end 3a of the large-diameter fixed portion 3 and an inner end 4a of the small-diameter fixed portion 4 and an axis b
The angle α between the two is set to 15 to 30 degrees. Further, as shown in detail in FIG. 2, three of the six peaks 10 have an angle δ of 34 to 90 between the perpendicular c drawn from the top of the peak 10 to the axis a and the large diameter side. The angle γ on the small diameter side is set in a range of 0 to 56 degrees, and the angle δ on the large diameter side is set to be larger than the angle γ on the small diameter side.

The thermoplastic synthetic resin elastomer constituting the boots 1 includes polyester, polyurethane, polyamide, polyolefin, polystyrene, and vinyl chloride thermoplastic elastomers, and these may be used alone or as a blend. Layered or multilayered.

As described above, according to the boot 1 of the embodiment, the bellows portion 2 consists of six peaks 10 and five valleys 11, and the inner end of the large-diameter fastening portion 3 and the inner end of the small-diameter fastening portion 4 Since the angle between the straight line a connecting them and the axis b is 15 to 30 degrees, it is possible to satisfy both blow moldability and flexibility during use. In addition, the mountain parts of 3 out of the 10 mountain parts of 6 mountains are
Since the angle on the large diameter side is 34 to 90 degrees and the angle on the small diameter side is 0 to 56 degrees with respect to the perpendicular c drawn from the top of the mountain to axis b, the wall on the small diameter side bends when bent. On the inside, the wall on the small diameter side is folded into the bellows with priority, and on the outside of the bend, the wall on the small diameter side absorbs the elongation and bends smoothly, improving the overall elasticity. Becomes good. Also,
Since the bellows part 2 is formed so as to start from the peak part 10 following the large-diameter fixed part 3, the distance of the bellows part 2 from the axis can be set large relative to its diameter, and the bellows part is evenly spaced during bending. There is no risk of damage due to contact with the shaft of the speed joint.

[0013]

[Effects of the Invention] According to the present invention, even a boot constructed by blow-molding a thermoplastic synthetic resin elastomer has excellent elasticity and flexibility as a whole, and is particularly suitable for high-speed rotation. Great durability can be obtained as a boot for constant velocity joints in automobiles.

[Brief explanation of drawings]

FIG. 1 is an overall partially cutaway front view showing one embodiment.

FIG. 2 is an enlarged cross-sectional view of a portion inside the circle shown in broken lines in FIG. 1;

[Explanation of symbols]

1 Boots 2 Bellows belly 3 Large diameter fixed part 4 Small diameter fixed part 5 Constant velocity joint 6 Outer ring 7 Shaft part 10 Yamabe 11 Tanibe

Claims (1)

[Claims] Claim 1: A boot constructed by blow molding an elastomer made of thermoplastic synthetic resin, and having a large-diameter fixed portion at one end of the bellows portion and a small-diameter fixed portion at the other end, wherein The bellows part has 6 or more peaks and 5 or more valleys, and the angle α between the axis and the straight line connecting the inner end of the large-diameter fixed part and the inner end of the small-diameter fixed part is 15.
~30 degrees, and the angle δ on the large diameter side of at least three or more of the six or more peaks is 34 to 90 degrees with respect to the perpendicular drawn from the top of the peak to the axis of the bellows part. The angle γ on the small diameter side is in the range of 0 to 56 degrees, the angle δ on the large diameter side is larger than the angle γ on the small diameter side, and a peak part is formed following the large diameter fixed part. boots.