JP2002235771A - Structure of boot for universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boot for a universal joint having no limit is full length or slide length of a drive shaft by shortening a mounting span and reducing a crest-to-crest contact of a bellows even at a large angle. SOLUTION: The shaft-side end 15 on the boot 10 for the universal joint 11 has a double wall structure having concentric outer and inner ring walls 15A, 15B positioned radially apart from each other. Ends of respective ring walls 15A, 15B adjacent to the bellows 16 are connected to each other by an annular web 17 substantially U-shaped in section to define an annular recess 18 opened in the direction away from the bellows 16. The inner ring wall 15B is provided with, at the periphery of its free end, a projection 19 slightly projecting radially from the outer periphery of a loose end toward the outer ring wall 15A. Even when the shaft is angled, the projection 19 prevents the annular recess 18 from becoming flat and eliminates the crest-to-crest contact of the bellows.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boot structure of a universal joint for protecting mud and dust from entering the universal joint and preventing the lubricating oil inside the universal joint from scattering outside. It is.

[0002]

2. Description of the Related Art As conventional boots 1 of a universal joint, there are a rubber boot and a resin boot, and as shown in FIG. Generally, a bellows portion 7 is provided between the portion 4 and the shaft side end portion 6 which is closely attached to the periphery of the shaft 5.

[0003] In the case of a conventional boot structure, particularly in the case of a resin boot, the span between the mounting ends must be about 1.3 to about 1.5 times that of a rubber boot, and the mounting span is equivalent to that of a rubber boot. To do so, it was necessary to increase the number of bellows mountains.

[0004]

In the case of a drive shaft having an intermediate slide, it is desirable to increase the slide length and shorten the overall length. However, if the mounting span is long, this condition cannot be satisfied.

[0005] When the number of bellows increases, if the shaft on the driving side and the shaft on the driven side form a large angle, as shown in FIG. If the drive shaft rotates at high speed in such a state, heat and wear occur at the contact portion, which affects the life.

To avoid this, the angle range may be limited. However, in this case, the operability and workability of a vehicle or a device using the drive shaft is limited.

Accordingly, it is an object of the present invention to shorten the mounting span, so that the length of the drive shaft and the slide length are not restricted, and the contact of the bellows peaks with each other is reduced even when a large angle is formed. Can be universal joint boots,
In particular, there is a need to obtain resin boots.

[0008]

In order to achieve this object, a boot structure of a universal joint according to the present invention comprises a concentric outer annular wall portion and an inner annular wall portion whose shaft side ends are radially separated from each other. Ends of the outer annular wall portion and the inner annular wall portion adjacent to the bellows portion are connected to each other by a substantially U-shaped cross-section annular web portion, and are opened in a direction away from the bellows portion. A recess is formed, and a convex portion is provided which projects slightly radially outward from the outer periphery of the free end of the inner annular wall toward the outer annular wall.

According to the boot structure of the universal joint of the present invention, the distance between the shaft side end and the housing side end is reduced and the concentric double wall structure is formed, and the outer and inner annular walls are connected to each other. When the angle formed by the shaft is small, the angle absorption is performed only by the bending of the annular web portion, and the bending of the annular web portion is performed when the angle formed by the shaft is small. When the angle cannot be completely absorbed by the above, the convex portion of the inner annular wall abuts against the inner surface of the outer annular wall portion, and the bellows portion is deformed by pushing the outer annular wall portion. Preferably, the bellows is more rigid than the annular web.

Also, the convex portion projecting radially outward from the inner annular wall portion does not cause the inner annular wall portion to contact the outer annular wall portion (the annular web portion is crushed). The bending stress of the annular web portion can be limited without generating self-heating.

Since the bellows need only cover the remaining angular range that the annular web cannot absorb, only the deformation over a small angular range is necessary, so that the peaks of the bellows are less likely to contact each other.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the drawings.

FIGS. 2A, 2B, and 2C show various angles of the shaft 12 of the universal joint 11 to which the boot 10 according to the present invention is attached. As shown in FIG. 1, a boot 10 according to the present invention comprises a housing 13 of a universal joint 11.
A housing-side end 14 sealingly connected to
And a shaft-side end portion 15 which is hermetically connected to the periphery of the housing.

In the boot 10 according to the present invention, the shaft-side end portion 15 has a double wall structure of a concentric outer annular wall portion 15A and an inner annular wall portion 15B which are radially separated from each other. Ends of the outer annular wall portion 15A and the inner annular wall portion 15B on the side adjacent to the bellows portion are connected to each other by an annular web portion 17 having a substantially U-shaped cross section, and are opened in a direction away from the bellows portion. To be generated. Furthermore, a projection 19 is provided which projects slightly radially outward from the outer periphery of the free end of the inner annular wall 15B toward the outer annular wall 15A.

The projecting portion 19 is an annular projecting portion continuously projecting radially outward in the circumferential direction, or a plurality of projecting portions projecting radially outward at regular intervals in the circumferential direction. be able to.

FIG. 2B shows a state immediately before the convex portion 19 of the inner annular wall portion 15B comes into contact with the inner surface of the outer annular wall portion 15A at an angle of the shaft, and FIG. Part 19
In contact with the inner surface of the outer annular wall 15A. FIG. 3 shows an enlarged view of this part.

According to the present invention, the peaks of the bellows 16 do not come into contact with each other in the range of FIGS. 2 (c), the convex portion 1 of the inner annular wall portion 15B
9 contacts the inner surface of the outer annular wall portion 15A, so that the annular web portion 17 is not crushed. In the remaining slight allowable angle movement of the shaft, the convex portion 19 deforms the bellows portion 16 by pressing the inner surface of the outer annular wall portion 15A, but does not bring the peaks of the bellows portions into contact with each other. Accordingly, the bellows portion does not come into contact with the peaks over the entire allowable angle at which the shaft can move.

In order to suppress the deflection of the bellows portion 16 when the universal joint 11 rotates, the bellows portion 16 has a greater thickness than the annular web portion 17, for example, so that the bellows portion 16 has a higher rigidity than the annular web portion 17. Alternatively, only the curved portion of the annular web portion 17 may be thinned. FIG. 4 shows that the rigidity ratio between the bellows portion 16 and the annular web portion 17 is “1”, “1.5”,
The relationship between the rotational speed of the universal joint and the deflection of the bellows portion in each case of “2” is shown.

[0019]

According to the boot of the present invention, the shaft-side end has a double wall structure of a concentric outer annular wall portion and an inner annular wall portion connected to each other by an annular web portion having a U-shaped cross section. An annular recess opened in a direction away from the bellows portion is provided by the annular web portion, the outer annular wall portion, and the inner annular wall portion, and is slightly radially outward from the free end outer periphery of the inner annular wall portion toward the outer annular wall portion. Even if the mounting span is shortened and the number of peaks of the bellows is increased, the peaks of the bellows can contact each other over the entire allowable angle range where the shaft can move. Disappears. Therefore, there is no problem of heat generation or abrasion at the contact portion when the drive shaft rotates at high speed as seen in the conventional boot, and the life can be improved. Also, there is no need to limit the angle range in which the universal joint shaft can move.

Further, according to the boot structure of the present invention, since the mounting span of the boot can be shortened, there is no restriction on the axial length or the slide length of the drive shaft having the intermediate slide.
The effect of increasing the degree of freedom in design can also be obtained.

[Brief description of the drawings]

FIG. 1 shows a conventional boot of a universal joint, in which (a) is a side view with a partial cross section, and (b) shows an angle between a shaft and a boot in which a mounting span is shortened and the number of bellows is increased. It is a side view of the state attached.

FIGS. 2A and 2B are side views of a universal joint having a boot structure according to the present invention, in which a part of the shaft is in a neutral state, and FIG. The state immediately before contacting the inner surface of the outer annular wall,
(C) shows a state in which the protrusion contacts the inner surface of the outer annular wall portion.

FIG. 3 is an enlarged view in which a part of FIG. 2C is enlarged.

FIG. 4 shows a rigidity ratio between the bellows portion and the annular web portion of “1”,
It is a graph which shows the relationship between the rotation speed of the universal joint and the deflection of the bellows part in each case of "1.5" and "2".

[Explanation of symbols]

 1 Boot 2 Universal joint 3 Housing 4 Housing end 5 Shaft 6 Shaft end 7 Bellows 10 Boot 11 Universal 12 Shaft 13 Housing 14 Housing end 15 Shaft end 15A Outer annular wall 15B Inner annular wall Part 16 Bellows part 17 Annular web part 18 Annular recess 19 Convex part

Claims (4)

[Claims] 1. A housing having a housing-side end sealingly connected to a housing of a universal joint, and a shaft-side end sealingly connected to a periphery of a shaft, wherein a bellows portion is provided between the housing-side end and the shaft-side end. And the concentric outer annular wall and the inner annular wall are separated from each other in the radial direction by a double wall structure, and the outer annular wall and the inner annular wall are provided. The end portions on the side adjacent to the bellows portion are connected to each other by an annular web portion having a substantially U-shaped cross section to form an annular recess opened in a direction away from the bellows portion, and the outer annular portion from the outer periphery of the free end of the inner annular wall portion A boot structure for a universal joint, wherein a convex portion is provided which projects slightly outward in the radial direction toward a wall portion. 2. The boot structure for a universal joint according to claim 1, wherein said convex portion is an annular convex portion continuously projecting radially outward in the circumferential direction. 3. The boot structure for a universal joint according to claim 1, wherein said projections are a plurality of projections projecting radially outward at equal intervals in a circumferential direction. 4. The boot structure for a universal joint according to claim 1, wherein said bellows portion has higher rigidity than said annular web portion.