JP2003222155A - Constant velocity joint boot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constant velocity joint boot exhibiting excellent sealing performance at the time of coupling and further capable of being easily formed and easily built in the counterpart members in the constant velocity joint boot formed integrally by injection blow molding and provided with a thick portion. <P>SOLUTION: When a cylindrical portion with a large diameter in a joining member is joined to the counterpart member, the external peripheral surface of the thick portion makes up a circular column surface together with the external peripheral surface of a thin portion. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boot for covering a constant velocity joint, which is indispensable for a drive shaft joint of a front-wheel drive vehicle, to prevent water and dust from entering the joint portion of the constant velocity joint.

[0002]

2. Description of the Related Art Conventionally, a joint portion of a constant velocity joint is covered with a bellows-shaped boot filled with grease, and a large angle and smooth rotation are maintained by preventing intrusion of water and dust. These boots for constant velocity joints
A large-diameter large-diameter cylinder part that is held by a joint outer race, etc., a small-diameter cylinder part that is smaller in diameter than the large-diameter cylinder part and that is held by the shaft, and a substantially conical shape that integrally connects the large-diameter cylinder part and the small-diameter cylinder part. It is composed of a trapezoidal bellows. During use, the bellows portion is deformed according to the change in the angle formed by the joint outer race and the shaft (joint angle), so that the joint portion can be reliably sealed by the boot even if the angle becomes large.

The fastening portion of the mating member fastened to the large diameter tubular portion of the constant velocity joint boot has a non-circular outer peripheral shape in a tripod joint or the like. Therefore, the large-diameter cylindrical portion of the boot for constant velocity joint imparts sufficient sealing performance to reliably prevent entry of water and dust into the joint. It is formed in a shape having a thick portion that partially protrudes toward the inner peripheral side. This boot for a constant velocity joint is usually formed of a thermoplastic elastomer having excellent weather resistance and fatigue resistance.

Japanese Unexamined Patent Publication (Kokai) No. 8-233116 discloses a CVJ boot made of a thermoplastic elastomer and having a thick portion that partially protrudes toward the inner peripheral side in the circumferential direction. Here, a thick-walled formed product formed of a thermoplastic elastomer may have a sink mark in which a curved surface is partially concave when cooled after forming, and may not be formed into a uniform shape. . Therefore, JP-A-8-233
The CVJ boot disclosed in Japanese Patent No. 116 may not show sufficient sealing performance because a sink mark is generated on the surface and a gap is formed between the CVJ boot and the mating member or the fastening member at the time of fastening. If good sealing performance is not exhibited at the time of fastening, water or dust may invade the inside of the boot or grease may leak from the inside of the boot. In this case, there is a problem that the joint cannot rotate properly. Furthermore, since thermoplastic elastomer has low elasticity, the thick-walled part has poor elongation, and the large-diameter cylindrical part having the thick-walled part is difficult to remove from the molding die after molding, and it is very difficult to assemble it to the mating member Had a bad problem.

Therefore, in recent years, PAT, No, E
P, No. 915264, boots for constant velocity joints in which the thick-walled portion of the large-diameter tubular portion has been thinned,
PAT, No. EP, No. A boot for a constant velocity joint, in which a ring-shaped bush made of soft rubber is inserted and integrated into a thin large-diameter cylindrical portion, as described in 924450, has been devised. PAT, No, EP, No. 91526
In the boot for constant velocity joint described in 4, the thick part is thinned, so that a molded product without a sink can be molded, and a gap between the mating member and the fastening member at the time of fastening can be obtained. Are prevented from occurring. Also, since the thick part is thinned out, the thick part has good elongation,
At the time of molding, it can be easily taken out from the mold and can be easily assembled to a mating member. Furthermore, since the thick portion is thinned, a lightweight product can be formed at low cost. However, on the other hand, in this thinned-out thick portion, the surface pressure distribution at the time of fastening with the mating member becomes non-uniform, and there is a problem that the sealing performance at the time of fastening is not good.

Further, PAT, No, EP, No. 924
According to the boot for constant velocity joint described in 450,
The fastening force of the fastening member is transmitted to the bush via the large-diameter cylindrical portion, and the bush is elastically deformed and comes into close contact with the mating member, so that the sealing function is exhibited. For this reason, the bush is made of a highly elastic material such as a rubber material, and the boot body is made of a material having excellent weather resistance and fatigue resistance such as a thermoplastic elastomer, so that the constant velocity joint has both sealing performance and durability. Boots can be formed. Since the bush and the boot body are molded separately, the bush can be molded accurately without being affected by the shape of the boot body during molding. However, on the other hand, since the bush and the boot main body are individually molded and then welded and integrated, the number of parts is increased, resulting in an increase in the number of manufacturing processes and an increase in manufacturing cost.

In recent years, Japanese Unexamined Patent Publication No. 10-110738
A boot for a joint has been devised, as described in Japanese Patent Laid-Open Publication No. 2003-115, in which a groove is provided in the thick portion in the axial direction from the outer end surface to form a belt-like portion continuous with the thin portion. According to this boot, since the difference in wall thickness between the thin portion and the strip portion is small, it is possible to prevent only the thin portion from being stretched when taking out from the molding die or when assembling the mounting portion to the mating member. Can be done easily. Since the thickness of the thick portion is relatively small, sink marks generated in the thick portion during molding can be reduced.

However, since the joint boot disclosed herein has a substantially cylindrical surface before fastening, the thick portion does not oscillate in the direction of the strip portion to form a true cylindrical surface during fastening. Therefore, a gap is created between the fastening member and the large-diameter cylindrical portion. FIG. 1 shows a schematic end view of a large-diameter tubular portion of such a joint boot, and FIG. 2 shows a schematic sectional view of the large-diameter tubular portion taken along a plane including an axis. Further, FIG. 3 shows a schematic end view when the large-diameter tubular portion of such a joint boot is fastened to a mating member, and FIG. 4 is an enlarged view of a main part of the large-diameter tubular portion fastened to the mating member. Show.

As shown in FIGS. 1 and 2, the large-diameter cylindrical portion 100 is formed by swinging a swinging portion 101 having a uniform wall thickness in the axial direction so as to project from the thin seal portion 102 in the outer peripheral direction, and swinging. A groove 103 in which the swinging portion 101 swings is provided between the moving portion 101 and the thin seal portion 102, and the thick portion 108 is formed.
It is said that. In addition, the thin seal portion 102 is
4 is formed continuously. And this large diameter cylindrical portion 10
At 0, the oscillating portion 101 and the thin portion 104 form a substantially cylindrical surface.

When the large-diameter tubular portion 100 is fastened to the mating member 106 by the fastening member 105, the oscillating portion 101 oscillates and comes into pressure contact with the thin seal portion 102 as shown in FIG. The shape of 100 does not take the surface of a true cylinder.
For this reason, as shown in FIG.
01 and the thin portion 104, a gap 107 is formed. In this case, the surface pressures a1 and a2 of the portion where the gap 107 is generated are the surface pressures a3 and a2 of the portion where the gap is not formed.
The surface pressures a1 to a4 in the circumferential direction are not constant. Therefore, the surface pressure distribution in the circumferential direction of the large-diameter cylindrical portion becomes non-uniform, and there is a problem that the sealing performance at the time of fastening is not good.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and in a boot for a constant velocity joint which is integrally molded by injection blow molding and has a thick portion, is favorable at the time of fastening. An object of the present invention is to provide a boot for a constant velocity joint that exhibits sealing performance, can be easily molded, and can be easily attached to a mating member.

[0012]

A boot for a constant velocity joint according to the present invention, which solves the above-mentioned problems, has a small-diameter cylindrical portion held by a shaft and a small-diameter cylindrical portion which is coaxially arranged apart from the small-diameter cylindrical portion. And a bellows portion integrally connecting the small-diameter tubular portion and the large-diameter tubular portion, the large-diameter tubular portion partially protruding inward in the circumferential direction. Having a substantially cylindrical thin-walled portion connecting the thick-walled portion and the thick-walled portion that are integrally formed by injection blow molding, and the inner peripheral surfaces of the thick-walled portion and the thin-walled portion are pressed against a non-circular mating member. The constant-velocity joint boot is fastened in such a manner that the thick-walled portion is formed on the thin-walled seal portion having an inner peripheral surface that is substantially similar to the outer peripheral surface of the mating member, and on the outer periphery of the thin-walled seal portion. And a swinging portion having a width smaller than the width of the swinging portion adjacent to the bellows portion and connecting the thin seal portion and the swinging portion. The wall connecting portion and the rocking space formed between the thin seal portion and the rocking portion, and when the fastening member fastens the large-diameter tubular portion to the mating member, the rocking portion is It is characterized in that the outer peripheral surface of the thick-walled portion and the outer peripheral surface of the thin-walled portion together with the outer peripheral surface of the thin-walled portion form a true cylindrical surface by being rocked in the rocking space and brought into pressure contact with the thin-walled seal portion.

According to this structure, when the large-diameter cylindrical portion is fastened to the mating member by the fastening member, the outer peripheral surface of the thick-walled portion and the outer circumferential surface of the thin-walled portion form a true cylindrical surface. There is no gap between the large-diameter cylindrical portion and the circumferential surface pressure is constant, so that the sealing performance at the time of fastening is good.

Further, since the thin connecting portion for connecting the thin seal portion and the swinging portion has a width smaller than that of the swinging portion, the thin seal portion is not affected by the swinging portion. Therefore, molding and assembly are easy, and the sealing performance at the time of fastening is good.

Further, it is preferable that the thin seal portion and the thin portion have substantially the same thickness.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A boot for a constant velocity joint according to the present invention comprises a small-diameter tubular portion held by a shaft and a large-diameter tubular portion which is coaxially arranged apart from the small-diameter tubular portion and has a diameter larger than that of the small-diameter tubular portion. And a bellows portion integrally connecting the small-diameter tubular portion and the large-diameter tubular portion, and the small-diameter tubular portion, the large-diameter tubular portion and the bellows portion are integrally formed by injection blow molding.

The boot for a constant velocity joint can be formed of a general elastic material, but is preferably formed of an oil resistant rubber material or a thermoplastic elastomer.

The large-diameter cylindrical portion of the boot for a constant velocity joint according to the present invention has a thick-walled portion that partially protrudes toward the inner circumferential side in the circumferential direction and a thin-walled portion of a substantially cylindrical shape that connects the thick-walled portion. Of these, the thick-walled portion includes a thin-walled seal portion having an inner peripheral surface that is substantially similar to the outer peripheral surface of the mating member, an oscillating portion formed on the outer periphery of the thin-walled seal portion, and a thin-walled seal portion adjacent to the bellows portion. The thin connecting portion has a width smaller than the width of the swinging portion that connects the swinging portions, and the swinging space formed between the thin seal portion and the swinging portion.

The large-diameter tubular portion of the boot for constant velocity joint of the present invention is assembled and fastened to the outer peripheral portion of the mating member. Here, as described above, the mating member such as the tripod joint has a non-circular outer peripheral shape. This non-circular outer peripheral shape is usually a shape in which a circular shape is indented from several predetermined positions. In the present invention, the thin-walled portion of the large-diameter tubular portion contacts the circular portion of the mating material, and the thick-walled portion contacts the recessed portion of the mating material. Therefore, the thin portion has a substantially cylindrical shape, and the thick portion has a shape corresponding to the recessed portion of the mating member. Further, the position where the thick portion is provided and the number of the thick portions are also adapted to the shape of the mating member.

In the boot for a constant velocity joint of the present invention, the thick portion contacts the mating member by the thin sealing portion. Therefore, the thin seal portion has an inner peripheral surface that is substantially similar to the outer peripheral surface of the mating member. Here, in order for the large-diameter tubular portion to exhibit good sealing performance when being fastened to the mating member, the portion of the large-diameter tubular portion that is in contact with the mating member must have a continuous structure. In the present invention, the thick-walled portion is connected by the thin-walled portion, and the thin-walled portion and the thin-walled seal portion of the thick-walled portion are both in contact with the mating member, so the thick-walled portion is connected by the thin-walled seal portion to the thin-walled portion. It is preferable that the thin-walled seal portion and the thin-walled portion have a continuous integral shape. Further, it is more preferable that the thin portion and the thin sealing portion have approximately the same thickness.
By making the thin part and the thin seal part have the same thickness,
When assembling the large-diameter tubular portion to the mating member, it is possible to prevent only the thin-walled portion or only the thin-walled sealing portion from extending, and improve the sealing performance between the mating member and the large-diameter tubular portion, and It is possible to maintain the strength of the large-diameter cylindrical portion.

In the present invention, when the large-diameter cylindrical portion is fastened to the mating member by the fastening member, the swinging portion swings in the swinging space and is pressed against the thin-walled seal portion so that the outer peripheral surface of the thick-walled portion is thin-walled. And a surface of a true cylinder together with the outer peripheral surface.

Here, as described above, the thin-walled seal portion has an inner peripheral surface that is substantially similar to the outer peripheral surface of the mating member. Therefore, in order for the outer peripheral surface of the thick part to form a true cylindrical surface together with the outer peripheral surface of the thin part, the swinging part that is pressed against the thin seal part corrects the shape of the indented part of the mating member to form a true cylindrical surface. It needs to be formed into a shape that can form a cylindrical surface.

In the present invention, the thin connecting portion for connecting the thin seal portion and the swinging portion has a width smaller than the width of the swinging portion. When the thin-walled connecting part is large, for example, when the thin-walled sealing part and the oscillating part are connected by the thin-walled connecting part over the entire surface in the circumferential direction, the expansion of the thin-walled sealing part is affected by the thick-walled oscillating part. To be done. In this case, the thin-walled part and the thin-walled seal part do not extend evenly when the large-diameter cylindrical part is assembled to the mating material, and the thin-walled part is thinned when the swing part swings at the time of fastening and is pressed against the thin-walled seal part. Strain stress may occur in the seal portion, and sufficient seal performance and strength may not be obtained. In the present invention, since the thin connecting portion has a width smaller than that of the swinging portion, the expansion of the thin sealing portion is affected by the swinging portion, and the thin wall sealing portion undergoes stress strain when the swinging portion swings. Is suppressed. Therefore, it becomes possible to maintain good sealing performance and strength. Further, in order to maintain good sealing performance and strength of the thin-walled connecting portion, the thin-walled connecting portion may be formed with a circumferential width of 5 to 10 mm and a wall thickness of 0.5 to 1.5 mm. preferable. If it is smaller than this, the strength of the connection between the swinging portion and the thin seal portion becomes low, and if it is larger than this, it becomes difficult to maintain sufficient sealing performance and strength of the large-diameter tubular portion.
Further, if the width and thickness of the thin connecting portion are within this range, the thin connecting portion can be molded by the gate portion of the molding die, so that more accurate molding can be performed.

Further, in the present invention, when the large-diameter cylindrical portion is fastened to the mating member by the fastening member, the outer peripheral surface of the thick-walled portion and the outer circumferential surface of the thin-walled portion constitute a true cylindrical surface, so that the fastening member is fastened at the time of fastening. There is no gap between the large-diameter cylindrical portion and the circumferential surface pressure is constant, so that good sealing performance can be obtained. In addition, the swinging portion can be formed in a shape having a constant thickness in a cross section when cut along a plane including the shaft,
In this case, the surface pressure in the axial direction of the large-diameter tubular portion when the large-diameter tubular portion is attached to the mating member and fastened by the fastening member can be made constant, so that the sealing performance can be further improved. .

Here, the rocking portion is relatively thick, and a slight sink mark in the axial direction may occur during molding. But,
The thin-walled seal part that is in contact with the mating material is thin, so that it does not cause sink marks and is formed in a good shape.The swing part is pressed and deformed at the time of fastening. It does not decrease.

In order to further reduce the sink marks generated on the swinging portion, the swinging portion may be lightened. in this case,
It is preferable that the thinning of the swinging portion is performed on the surface that comes into contact with the thin seal portion during fastening. By thinning the surface in contact with the thin-walled seal portion during fastening, the outer peripheral surface of the thick-walled portion at the time of fastening forms a true cylindrical surface together with the outer peripheral surface of the thin-walled portion, so that the circumferential surface pressure is kept constant. And good sealing performance is maintained. In addition, the weight of the constant velocity joint boot can be reduced by removing the thickness of the rocking portion.

Since the boot for constant velocity joint of the present invention is integrally formed by injection blow molding, it can be molded with a small number of steps and one member. Therefore, the cost and man-hours required for manufacturing can be suppressed. Since the thin seal portion and the thin portion have good elongation, they can be easily taken out of the mold and can be easily assembled to the mating material, which improves workability during manufacturing and use. To do.

[0028]

Embodiments of the present invention will be described below with reference to the accompanying drawings. (Embodiment 1) FIG. 5 is a schematic explanatory view illustrating a process of injection blow molding of a boot for a constant velocity joint according to Embodiment 1 of the present invention.
Shown in. Further, FIG. 6 shows an enlarged perspective view of an essential part of the large-diameter cylindrical portion of the constant velocity joint boot of the first embodiment after molding, and FIG. 7 shows a sectional view of the large-diameter cylindrical portion cut in the axial direction. . Then, an enlarged view of a main part of the constant-velocity joint boot of the first embodiment when the large-diameter tubular portion is fastened to the mating member is shown in FIG. 8, and for the constant-velocity joint of the first embodiment fastened to the mating member. A cross-sectional view of the large-diameter cylindrical portion of the boot is shown in FIG.

The boot for the constant velocity joint of the first embodiment is
It is manufactured by molding thermoplastic elastomer TPEE or TPO as a material, and molding this thermoplastic elastomer by injection blow molding. Molding by injection blow molding is performed as follows.

First, a heated and liquefied thermoplastic elastomer raw material is injected into a parison mold 3 consisting of a parison core mold 1 and a parison outer mold 2, and after injection, a hollow parison 4 is molded. The parison 4 has a large-diameter cylindrical portion 5,
It is molded into a shape having a small-diameter tubular portion 6 and a hollow blow portion 8 that greatly expands during blow molding to form a bellows portion 7.

The molded parison 4 is taken out from the parison outer mold 2 together with the parison core mold 1 and blown mold 9
Be attached to. The parison 4 mounted on the blow mold 9
Air is blown into the blow portion 8 from the parison core 1 and expands, and the bellows portion 7 is formed by this step. The parison 4 on which the bellows portion 7 is formed is cut and the runner at the time of molding is removed to form the small diameter cylindrical portion 6. Through the above steps, the boot for constant velocity joint of the first embodiment is molded.

As shown in FIG. 6, a thick swing portion 10 and a thin seal portion 11 are formed on the large-diameter cylindrical portion 5 of the boot for a constant velocity joint of the first embodiment formed in the above steps. The oscillating portion 10 and the thin seal portion 11 are arranged at a total of three places, and the oscillating portion 10 is formed so as to protrude toward the outside of the substantially cylindrical shape drawn by the thin portion 12.
Further, the thin seal portion 11 and the thin portion 12 are formed to have substantially the same thickness.

Further, as shown in FIG. 7, the rocking portion 10 is formed so that the wall thickness is constant when it is cut along a plane including the shaft, and the rocking portion 10 and the thin seal portion 11 are thinly connected. They are connected by the part 13. Further, the thin connecting portion 13 has a width shown in FIG.
And are connected.

When the large-diameter cylindrical portion 5 of the constant velocity joint boot of the first embodiment is assembled to the mating member 14, the large-diameter cylindrical portion 5 is used.
Is in contact with the outer surface of the mating member 14 at the thin seal portion 11 and the thin portion 12. At this time, the large-diameter side fitting groove 16 provided on the outer surface of the mating member 14 in the circumferential direction and the thin seal portion 1
The seal rib portion 17 provided in the circumferential direction is fitted to the surface of the thin wall portion 1 or the thin portion 12 which is in contact with the mating member 14. By fitting the large-diameter side fitting groove 16 and the seal rib portion 17, the large-diameter cylindrical portion 5 and the mating member 14 are assembled well.

When the large-diameter tubular portion 5 is fastened from the outside of the large-diameter tubular portion 5 by the ring-shaped fastening member 15, the swinging portion 10 swings the swinging space 18 by the fastening member 15,
As shown in FIG. 8, the outer peripheral surface 20 of the thick portion 19 pressed against the thin seal portion 11 constitutes a true cylindrical surface together with the outer peripheral surface 20 of the thin portion 12. Therefore, the swing unit 10,
A gap is suppressed from being formed between the thin seal portion 11 and the thin wall portion 12 and the fastening member 15, so that the surface pressure c1 in the circumferential direction is reduced.
~ C4 is constant. Therefore, the surface pressure distribution in the circumferential direction of the large-diameter cylindrical portion 5 becomes uniform, and the sealing performance at the time of fastening becomes good.

Further, since the swinging portion 10 is formed with a constant thickness when it is cut along a plane including the shaft, the axial direction when it is assembled and fastened to the mating member 15 as shown in FIG. The surface pressures d1 to d3 also become constant, and the surface pressure distribution in the axial direction of the large-diameter cylindrical portion 5 becomes uniform, so that the sealing performance at the time of fastening is further improved.

Since the thin-walled seal portion 11 and the thin-walled portion 12 are formed to have substantially the same wall thickness, only the thin-walled seal portion 11 or only the thin-wall portion 12 does not extend when assembled to the mating member. Therefore, it can be fastened to the mating member without a gap, and excellent sealing performance is exhibited.

Further, since the thin connecting portion 13 has a width smaller than the width of the swinging portion, the thin seal portion 11 is extended by the swinging portion 1.
Even when the swinging portion 10 swings and is brought into pressure contact with the thin-walled seal portion 11 at the time of fastening, no stress strain is generated in the thin-walled seal portion 11. (Embodiment 2) A boot for a constant velocity joint according to a second embodiment of the present invention is molded by the same injection blow molding as the boot for a constant velocity joint according to the first embodiment, except for the shape of the swinging portion. It has the same shape as the joint boot.

FIG. 10 shows a sectional view of the large-diameter cylindrical portion of the boot for a constant velocity joint of Example 2 taken along the axial direction. Further, FIG. 11 shows a cross-sectional view of the large-diameter cylindrical portion of the boot for a constant velocity joint of the second embodiment fastened to the counterpart member.

The rocking portion 21 of the boot for a constant velocity joint according to the second embodiment is circumferentially lightened at three points on the surface in contact with the thin seal portion 22, and has a concave lightening portion 23 and a convex lightening portion 23. The pressing portion 24 is formed. Lightening portion 23 and pressing portion 2
4 is formed so that the cross section when cut along a plane including an axis has a sawtooth shape. Further, the lightening portion 23 is formed in the circumferential direction so as to avoid the position facing the seal rib portion 25 of the thin seal portion 22.

When assembling and fastening the large-diameter cylindrical portion 26 of the constant velocity joint boot of the second embodiment to the mating member 27,
The oscillating portion 21 oscillated by the fastening member 28 has the pressing portion 24.
Is pressed against the thin seal portion 22. Here, the pressing portion 24
Is formed at a position facing the seal rib portion 25, the seal rib portion 25 is reliably pressed by the pressing portion 24. Therefore, the surface pressure in the circumferential direction of the seal rib portion 25 pressed by the pressing portion 24 is maintained without interruption because the swinging portion 21 is thinned in the circumferential direction, and the large diameter cylindrical portion 26 and the mating member are kept. The sealing performance with 27 is kept good.

According to the second embodiment, since the oscillating portion 21, which is a thick member, is thinned out, the oscillating portion 21 is formed at the time of molding.
The occurrence of sink marks is further prevented. Further, the weight of the constant velocity joint boot can be reduced by removing the meat.

Further, since the swinging portion 21 is thinned out on the surface in contact with the thin seal portion 22, the outer peripheral surface of the large-diameter cylindrical portion 26 at the time of fastening maintains a true cylindrical surface. Therefore, the surface pressure in the circumferential direction becomes constant, and good sealing performance is maintained.

[0044]

As described above, the boot for a constant velocity joint according to the present invention exhibits good sealing performance at the time of fastening,
It can be easily molded and can be easily assembled to a mating member. In addition, the number of steps and manufacturing cost can be reduced by integrally molding by injection blow molding.

[Brief description of drawings]

FIG. 1 is an end view showing a large-diameter cylindrical portion of a conventional joint boot.

FIG. 2 is an end view in which a large-diameter cylindrical portion of a conventional joint boot is axially cut.

FIG. 3 is an end view showing a large-diameter cylindrical portion of a conventional joint boot fastened to a mating member.

FIG. 4 is an enlarged view of a main part of a large-diameter tubular portion of a conventional joint boot fastened to a mating member.

FIG. 5 is an explanatory schematic diagram illustrating a process of injection blow molding of the boot for a constant velocity joint according to the first embodiment of the present invention.

FIG. 6 is an enlarged perspective view of an essential part showing a large-diameter cylindrical portion of the boot for a constant velocity joint according to the first embodiment of the present invention.

FIG. 7 is a cross-sectional view in which the large-diameter cylindrical portion of the boot for constant velocity joint of Example 1 of the present invention is axially cut.

FIG. 8 is an enlarged view of a main part of a large-diameter cylindrical portion of the boot for a constant velocity joint according to the first embodiment of the present invention fastened to a mating member.

FIG. 9 is a cross-sectional view of a large-diameter cylindrical portion of the boot for a constant velocity joint according to the first embodiment of the present invention fastened to a mating member.

FIG. 10 is a cross-sectional view of a boot for a constant velocity joint according to a second embodiment of the present invention, in which a large-diameter cylindrical portion is axially cut.

FIG. 11 is a cross-sectional view of a large-diameter cylindrical portion of a boot for a constant velocity joint according to a second embodiment of the present invention fastened to a mating member.

[Explanation of symbols]

100: Large-diameter cylindrical part 101: Swing part 102: Thin-walled seal part 103: Groove 107: Gap 108: Thick part 5: Large-diameter cylinder part 10: Swing part 11: Thin-walled seal part 12: Thin-walled part 13: Thin-walled part Connection part 14: Mating member 15: Fastening member 16: Large diameter side fitting groove 17: Seal rib part
18: Oscillating space 19: Thick part 21: Oscillating part 22: Thin sealing part 23: Thinning part 24: Pressing part 25: Seal rib part 26: Large diameter cylinder part 27: Mating member 28 Fastening member

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsumi Tanaka             Aichi Prefecture Kasuga-cho, Nishikasugai-gun Ochiai character Nagahata 1             Address within Toyoda Gosei Co., Ltd. F term (reference) 3J043 AA03 DA11 FA03 FA07 FB04

Claims (2)

[Claims] 1. A small-diameter tubular portion held by a shaft, a large-diameter tubular portion that is arranged coaxially apart from the small-diameter tubular portion and has a diameter larger than the small-diameter tubular portion, the small-diameter tubular portion, and the large-diameter portion. The large-diameter tubular portion is composed of a bellows portion integrally connecting the tubular portions. The large-diameter tubular portion has a thick-walled portion that partially protrudes toward the inner circumferential side in the circumferential direction and a thin-walled portion having a substantially cylindrical shape that joins the thick-walled portion. A constant velocity joint boot integrally formed by injection blow molding so that the inner peripheral surfaces of the thick-walled portion and the thin-walled portion are pressed against a non-circular mating member. A thin seal portion having an inner peripheral surface substantially similar to the outer peripheral surface of the mating member, a swinging portion formed on the outer periphery of the thin seal portion, the thin seal portion adjacent to the bellows portion, and the swing portion. A thin connecting portion having a width smaller than the width of the swinging portion connecting the moving portions, and a swinging space formed between the thin seal portion and the swinging portion. When the large-diameter cylindrical portion is fastened to the mating member with the fastening member, the swinging portion swings in the swinging space and is pressed against the thin seal portion, and the outer peripheral surface of the thick portion has the thin wall. A boot for a constant velocity joint, characterized in that it constitutes a true cylindrical surface together with the outer peripheral surface of the section. 2. The boot for a constant velocity joint according to claim 1, wherein the thin seal portion and the thin portion have substantially the same thickness.