Rotary shafts – gudgeons – housings – and flexible couplings for ro – Housing – Flexible housing
Reexamination Certificate
2002-10-04
2004-02-24
Browne, Lynne H. (Department: 3679)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Housing
Flexible housing
C277S636000, C277S637000
Reexamination Certificate
active
06695706
ABSTRACT:
The present application is based on Japanese Patent Application No. 2001-308620, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a boot for covering a constant velocity joint that is served as a joint for a drive shaft of the front-wheel-drive vehicle for protecting the joint portion of the constant velocity joint from invasion of water or dust.
2. Related Art
Hitherto, the joint portion of the constant velocity joint is covered by an accordion-folded boot in which grease is encapsulated and is protected from invasion of water or dust, so that smooth revolution at broad angle is ensured. The constant velocity joint boot includes a larger cylindrical portion of large diameter to be held by a joint outer race, a smaller cylindrical portion being smaller than the larger cylindrical portion in diameter to be held by a shaft, and a bellows portion of substantially conical shape for integrally connecting the larger cylindrical portion and the smaller cylindrical portion. When in use, the bellows portion deforms in accordance with the angle (joint angle) formed between the joint outer race and the shaft, and thus the joint portion is reliably sealed by the boot even when the angle increases.
In past days, the constant velocity joint boot used to be formed of rubber in many cases. However, since rubber has a problem in durability, thermoplastic elastomer being superior in weather resistance and in fatigue resistance is used in recent years. On the other hand, the constant velocity joint boot is required to be provided with a sealing performance to prevent water or dust reliably from invading into the joint. However, there was such problem that thermoplastic elastomer, when being employed as material, cannot ensure enough sealing performance as rubber because of its low resiliency. Though blow molding is convenient as a method for forming the constant velocity joint boot, it is difficult to form the shape of the inner peripheral surface of the larger cylindrical portion so as to have a high sealing performance by blow molding. Therefore, it is difficult to ensure a sealing performance with respect to the mating member from these points of view.
Accordingly, in JP-U-02-87131, a constant velocity joint boot in which the boot body is formed of polyester thermoplastic elastomer, and a ring-shaped bushing formed of soft rubber is inserted into the larger cylindrical portion thereof is disclosed. According to the constant velocity joint boot of this type, the bushing can be manufactured with a high degree of accuracy by injection molding or the like. Therefore, the shape accuracy of the boot body does not have to be so high, and thus the boot body may be manufactured by blow molding. A tightening force from the clamp is transmitted to the bushing via the larger cylindrical portion, and resilient deformation and hence tight adherence of the bushing with the mating member establish the sealing performance. In other words, durability is established by the boot body and the sealing performance with respect to the mating member is established by the bushing. Furthermore, the boot body, being larger in shape than the bushing, may be manufactured by blow molding, which results in reduction of the number of process and hence of the costs.
However, when manufacturing the boot body by blow molding, there remains such problem that the accuracy of the internal surface and the accuracy of the thickness are poor. Therefore, in the case of a constant velocity joint boot of a structure having a soft bushing inserted into the larger cylindrical portion of the boot body, when the thickness of the larger cylindrical portion varies, uniformity of the pressure exerted on sealing surface with respect to the bushing is impaired. As a consequent, there is a case in which the sealing performance between the boot body and the bushing is lowered, and thus problems such as leakage of grease arise.
SUMMARY OF THE INVENTION
With such circumstances in view, it is an object of the invention to provide a constant velocity joint boot of a construction having a soft bushing inserted into the larger cylindrical portion in which a high sealing performance with respect to the bushing is ensured even when the dimensional accuracy of the larger cylindrical portion is low.
A constant velocity joint boot according to the invention in which the aforementioned problem is solved is a constant velocity joint boot comprising:
a boot body made of a first material including
a smaller cylindrical portion attachable to a shaft,
a larger cylindrical portion disposed coaxially with and at a distance from the smaller cylindrical portion and being larger than the smaller cylindrical portion in diameter, and
a conical bellows portion connecting the smaller cylindrical portion and the larger cylindrical portion; and
a ring-shaped bushing formed of a second material that is softer than the first material and having a sealing projection to be engaged with a mating member on an inner peripheral surface thereof, the boot body and the bushing being tightened on the mating member by reducing diameters thereof from the outer peripheral surface of the larger cylindrical portion;
at least one ring-shaped ridge formed on an outer peripheral surface of the bushing and extending in a circumferential direction of the boot body, the ring-shaped ridge being configured so as to fall down toward a side where the bellows portion is provided in a longitudinal direction of the boot body when the ring-shaped ridge is pressed by the larger cylindrical portion.
The ring-shaped ridge is preferably formed on the outer periphery at the position corresponding to the sealing projection. The ring-shaped ridge and the sealing projection may be formed on a common plane which is normal to an axial direction of the bushing. The ring-shaped ridge may be formed in parallel with the sealing projection.
The ring-shaped ridge may be triangular in cross section, and an angle formed between a raising surface of the ring-shaped ridge which is oriented to the bellows portion and the outer peripheral surface of the bushing is not more than 90 degrees.
Further, a groove which is in parallel with the ring-shaped ridge may be formed on the outer peripheral surface of the bushing so that the groove is engaged with the sealing projection of the larger cylindrical portion.
In the constant velocity joint boot of the invention, preferably a pair of the ring-shaped ridges are provided on the outer peripheral surface of the bushing and the groove is located between these two ring-shaped ridges in parallel therewith in the circumferential direction of the boot body.
A constant velocity joint boot of the invention is formed with a ring-shaped ridge on the outer peripheral surface of the bushing so as to extend in the circumferential direction, and the ring-shaped ridge is capable of falling toward the bellows portion when the larger cylindrical portion is brought into press contact therewith. In other words, in a state in which it is tightened by the mating member, the ring-shaped ridge being fallen toward the bellows portion is interposed between the larger cylindrical portion and the bushing, and the ring-shaped ridge is brought into press contact with the larger cylindrical portion by a resilient reaction force of its own. When a pressure is exerted from grease contained in the bellows portion, since the pressure acts in the direction to allow the ring-shaped ridge to restore its original posture, the ring-shaped ridge is further brought into press contact with the inner peripheral surface of the larger cylindrical portion. In other words, since the ring-shaped ridge serves as a dam and is brought into press contact with the larger cylindrical portion at a high bearing pressure, problem such as leakage of grease may reliably be prevented. With these actions, even when there are variations in thickness or shape of the larger cylindrical portion, a high sealing performance is established between the larger cylindrical
Browne Lynne H.
Posz & Bethards, PLC
Thompson Kenn
Toyoda Gosei Co,., Ltd.
LandOfFree
Constant velocity joint boot does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Constant velocity joint boot, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Constant velocity joint boot will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3325614