JP2003329135A - Resin joint boot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin joint boot having remarkably improved durability. <P>SOLUTION: In the resin joint boot having a large diameter cylindrical part 1 at one end and a small diameter cylindrical part 2 coaxial with the large diameter cylindrical part at the other end which are integrally connected through a bellows part 3, the bellows part 3 is constituted of six valley parts 31-36 and six crest parts 41-46 which are sequentially formed from the large diameter cylindrical part 1 by turns. As a molding compound, an olefinic thermoplastic elastomer comprising polyolefin as a hard segment and an ethylene propylene rubber as a soft segment is used. It is preferable that the thermoplastic elastomer contains at least one kind selected from a group comprising dioctyl sebacate, tall-oil-acid N-butyl, tall-oil-acid isooctyl, and N-butyl oleate. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin joint boot, and more particularly to a bellows-shaped resin joint boot used for a constant velocity joint of an automobile.

[0002]

2. Description of the Related Art Joint boots for driving shafts of automobiles, industrial machines, etc. are equipped with joint boots in order to retain grease contained therein or prevent dust from entering. ing.

FIG. 2 shows an example of a conventional joint boot. The boot includes a large-diameter cylindrical portion 1 fitted into a housing portion of a constant velocity joint, and a small-diameter cylindrical portion 2 coaxially arranged apart from the large-diameter cylindrical portion 1 and fitted to a shaft. It consists of a bellows part 3 that connects the two together,
It is integrally molded by injection molding or press blow molding. Conventionally, the bellows portion 3 is generally composed of five troughs and five troughs in which troughs and troughs are alternately formed continuously from the large-diameter cylindrical portion 1 side.

However, in the conventional boot having the bellows portion 3 composed of the five valley portions and the five mountain portions, when the durability is not sufficient when it is rotated in a state of being bent and deformed at a wide angle. Therefore, further improvement in durability is required.

The present invention has been made in view of the above points, and an object thereof is to provide a resin joint boot having improved durability.

[0006]

The resin joint boot of the present invention has a large-diameter cylindrical portion at one end and a small-diameter cylindrical portion coaxially with the large-diameter cylindrical portion at both ends, and both have a bellows portion. A resin joint boot integrally connected via, a polyolefin as a hard segment, ethylene propylene rubber as a soft segment, consisting of an olefin-based thermoplastic elastomer as a constituent component, the bellows portion, the large It is characterized in that it comprises six troughs and six troughs in which troughs and troughs are formed alternately and continuously from the radial tube side.

By thus forming the bellows portion with the six valley portions and the six peak portions, the bellows portion when rotated in a bent and deformed state at a wider angle than the conventional boot is formed. It is possible to dramatically improve durability by reducing the maximum stress amplitude value of.

In the resin joint boot of the present invention, the thermoplastic elastomer is at least one selected from the group consisting of dioctyl sebacate, N-butyl tall oil, isooctyl tall oil, and N-butyl oleate. It is preferably added.

[0009]

1 is a half cross-sectional half side view of a resin joint boot according to an embodiment of the present invention. This boot is a boot made of a thermoplastic elastomer resin to be mounted on a constant velocity joint of an automobile, and has a large-diameter cylindrical portion 1 and a small-diameter cylindrical portion 2 which is coaxially arranged apart from the large-diameter cylindrical portion 1. ,
The bellows portion 3 integrally connects the large-diameter cylindrical portion 1 and the small-diameter cylindrical portion 2.

The large-diameter cylindrical portion 1 has a short cylindrical shape which is externally fitted and fixed to the outer peripheral surface of the distal end portion of the cylindrical housing portion of the constant velocity joint by a clamp, and has a ring-shaped clamp on the outer peripheral side. There is a groove 11 for receiving the.

The small-diameter cylindrical portion 2 has a short cylindrical shape which is externally fitted and fixed to the outer peripheral surface of the shaft projecting from the housing portion by a clamping clamp, and is coaxial with the large-diameter cylindrical portion 1.
That is, they are arranged so as to have a common center line L. The small-diameter cylindrical portion 2 is also provided with a groove 21 on the outer peripheral side for receiving a ring-shaped tightening clamp.

The bellows portion 3 is a bellows body having a circular cross section with a difference in diameter at both ends, and a grease-filled space 4 is formed therein. The bellows portion 3 is arranged in order from the large diameter tubular portion 1 side to the first valley portion 3
1, 1st mountain part 41, 2nd valley part 32, 2nd mountain part 42, 3rd
Valley 33, third mountain portion 43, fourth valley portion 34, fourth mountain portion 4
4, fifth trough 35, fifth peak 45, sixth trough 36, sixth
Like the peaks 46, the valleys and the peaks are composed of six valleys and six peaks alternately and continuously formed. Tanibe 31
To 36 and crests 41 to 46 are set so that the diameters of the large-diameter tubular portion 1 and the small-diameter tubular portion 2 decrease in order. Further, the slopes that form the bellows and are not directly connected to the large-diameter tubular portion 1 and the small-diameter tubular portion 2, that is, the slopes other than both ends of the bellows are directed toward the outer side of the boot in the boot axial direction cross-sectional shape. It is formed in a convex curved shape.

In the joint boot of this embodiment, an olefin thermoplastic elastomer having a hard segment of polyolefin and a soft segment of ethylene propylene rubber as constituents is used as a molding material, so that stress relaxation is large. Excellent in bending fatigue.

As the polyolefin constituting the hard segment, polyethylene, polypropylene, poly (1
-Butene), poly (1-pentene), poly (1-hexene), and the like. These may be used alone or in combination of two or more. Preferably polyethylene and / or polypropylene is used.

As the ethylene propylene rubber constituting the soft segment, ethylene propylene rubber (EP
M), ethylene propylene diene terpolymer rubber (E
PDM) and the like.

As the soft segment, other rubber components may be used in combination with the ethylene propylene rubber. Examples of such other rubber component include butyl rubber, copolymers of isobutylene and alkylstyrene such as methylstyrene, and halogenated polymers thereof. Further, polar rubbers such as acrylic rubber and nitrile rubber may be used. it can.

In the thermoplastic elastomer, the ratio of the hard segment and the soft segment is not particularly limited, but it is generally preferable that the hard segment is 70 to 90% by weight.

It is preferable to add dioctyl sebacate, N-butyl tall oil, isooctyl tall oil, and N-butyl oleate to the thermoplastic elastomer. These may be used alone or in combination of two or more. By adding these, rubbing noise due to friction between the slopes of the bellows can be prevented.

Various known additives may be added to the thermoplastic elastomer to improve its properties, processability and the like. Examples of such additives include antioxidants, light stabilizers, antistatic agents, fillers, extenders, reinforcing agents, colorants and the like.

Examples of the antioxidant include known antioxidants such as hindered phenol-based, sulfur-based and phosphorus-based antioxidants, and examples of the light stabilizer include known hindered amine-based, triazole-based, benzophenone-based antioxidants and the like. Agents. Examples of the filler, extender, reinforcing agent, and colorant include carbon blacks, silica, calcium silicate,
Examples thereof include silicic acid compounds such as kaolin, talc, clay, diatomaceous earth and wollastonite, metal carbonates such as calcium carbonate and barium carbonate, and organic or inorganic pigments.

[0021]

EXAMPLE The joint boot of the example shown in FIG. 1 and the joint boot of the comparative example shown in FIG. 2 were analyzed by a finite element analysis method (hereinafter referred to as FEM analysis) and spread widely. A simulation was performed on the distribution of stress when deformed to an angle (joint angle = 43 °).

As a result, the maximum stress amplitude value of the bellows portion at the time of wide-angle deformation was 1.428 kg / mm ^{2 in the} comparative example.
However, in the example, 1.224 kg / mm ²
Was reduced.

Next, as the base resin material, polypropylene is used for the hard segment and EPD is used for the soft segment.
An olefinic thermoplastic elastomer obtained by using M (trade name: Santoprene, manufactured by AES) is used, and the additive shown in Table 1 is added thereto in an amount of 20 parts by weight per 100 parts by weight of the thermoplastic elastomer. A molding material was prepared. Using the obtained molding material, the joint boot of the example shown in FIG. 1 and the joint boot of the comparative example shown in FIG. 2 were molded by an injection molding machine.

Durability tests were carried out on the resin joint boots obtained in the examples and comparative examples. The durability test was carried out by assembling the joint boots of the examples and comparative examples into a constant velocity joint, atmosphere temperature = 100 ° C., joint angle (angle between the center line of the housing part and the center line of the shaft) = 43 °, number of rotations = 500 rpm.

The results are shown in Table 1. In the joint boot of the comparative example, a through crack was generated in the bellows portion 25 hours after the test was started, whereas in the joint boot of the example, a through crack was observed. The occurrence was extended to 60 hours after the start of the test, and the durability was dramatically improved, which is a target value of 3
I was able to achieve 0 hours.

[0026]

[Table 1]

[0027]

As described above, according to the resin joint boot of the present invention, by forming the bellows portion with the six valley portions and the six mountain portions, as compared with the conventional boot,
When rotated in a state of being bent and deformed at a wide angle, the stress applied to the bellows portion is dispersed, so that the maximum stress amplitude value in the bellows portion is reduced, and the durability can be dramatically improved. Further, if the length of the bellows portion along the slope is constant, the size of the boot in the radial direction can be made smaller by using 6 valleys and 6 valleys than in the conventional case of 5 valleys and 5 valleys. Compared to compact boots.

[Brief description of drawings]

FIG. 1 is a half sectional half side view of a resin joint boot according to an embodiment of the present invention.

FIG. 2 is a half cross-sectional half side view of a conventional resin joint boot.

[Explanation of symbols]

1 ... Large diameter cylinder 2 ... Small diameter tube 3 ... Bellows 31-36 ... Tanibe 41-46 ...... Yamabe

Claims (2)

[Claims] 1. A resin joint boot having a large-diameter tubular portion at one end and a small-diameter tubular portion coaxially with the large-diameter tubular portion at the other end, both of which are integrally connected via a bellows portion. A polyolefin as a hard segment, and an ethylene propylene rubber as a soft segment, and an olefinic thermoplastic elastomer having a constituent component, wherein the bellows portion has valleys and peaks alternating from the large diameter cylinder side. A resin joint boot, characterized in that it comprises 6 troughs and 6 peaks that are formed continuously. 2. At least one selected from the group consisting of dioctyl sebacate, N-butyl tall oil, isooctyl tall oil and N-butyl oleate is added to the thermoplastic elastomer. The resin joint boot according to claim 1.