Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
2000-06-20
2001-03-13
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S562000, C277S569000, C277S571000, C277S572000
Reexamination Certificate
active
06199869
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a sealing device to be used for sealing a shaft of, for example, a cooling water circulating pump (water pump) in an automobile.
Heretofore, a mechanical seal has generally been used in a seal portion of a cooling water circulating pump in an automobile.
With the mechanical seal, however, various noises are generated during idling of the automobile because the seal portion is formed as a sliding surface.
Additionally, the mechanical seal causes an increase of the manufacturing cost because it includes many portions to be precision-machined.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a sealing device capable of preventing the generation of the aforesaid noises and capable of reducing the manufacturing cost.
The sealing device of the present invention has a first sealing lip made of rubber and slidable with respect to a shaft and a second sealing lip made of resin and slidable with respect to the said shaft, with a lubricant being held between the first and second sealing lips.
It is preferable that a spiral groove be formed in the first and/or the second sealing lip, whereby, during rotation of the shaft, the spiral groove if formed in the second sealing lip prevents a fluid from flowing downward. When the shaft is at a standstill, the fluid leaks along the groove because the second sealing lip of a second seal is made of resin and hence the shape of the groove remains intact. However, since the shaft is sealed by a first seal, the fluid is prevented from flowing out downward.
As the resin there usually is employed a fluorine series inelastic resin such as Teflon for example. As the rubber there is used an elastic body such as, for example, nitrile rubber, acrylic rubber, fluorine-contained rubber, or silicone rubber.
Since the first sealing lip is made of rubber and the second sealing lip is made of resin, the second sealing lip is more rigid than the first sealing lip. Therefore, the second sealing lip does not undergo any excessive deformation even at an elevated pressure. Thus, it is possible to improve the pressure resistance.
If the first sealing lip is provided on the side to be sealed by the second sealing lip, variations in pressure against the second sealing lip are diminished and the amount of cooling water (hereinafter referred to as “LLC”) and a foreign matter flowing to the second sealing lip is decreased. As a result, it is possible to attain not only improvement of the pressure resistance but also prevention of wear of both second sealing lip and the shaft.
Further, since a lubricant is held between the first and second sealing lips, the lubricant is fed effectively to the space between the front end portion of the first sealing lip and the sealing surface of the second sealing lip, so that it is possible to diminish the sliding resistance and improve the wear resistance, with no generation of noise.
Since the first and second sealing lips are made of rubber and resin, respectively, and there is used a lubricant, it is possible to reduce the manufacturing cost without the need of going through such a precision machining as in the prior art.
If spiral concaves and convexes are formed on the sealing surface of the first sealing lip, the fluid which has entered under a screw pump action during rotation of the shaft can be excluded to the side to be sealed, so that it is possible to enhance the sealability.
If spiral concaves and convexes are formed on the sealing surface of the second sealing lip, the fluid which has entered under a screw pump action during rotation of the shaft can be excluded to the side to be sealed, and therefore it is possible to enhance the sealability.
If the seal portion of the first sealing lip is made generally arcuate in section, an oil film formed between the seal portion and the shaft becomes thicker, whereby not only the wear resistance can be improved but also it is possible to prolong the service life.
It is preferable that a textile cloth be provided on the sealing surface of the first sealing lip. In the case where the fluid to be sealed is LLC having a high content of water, it is difficult to hold a highly lubricative oil component on the sliding surface of the seal portion, with a likelihood of resulting in deteriorated wear resistance. However, in the presence of a textile cloth, since a lubricant is held in the gaps of the textile cloth, the sealing surface of the first sealing lip slides while forming a thin film of the lubricant. As a result, durability can be improved.
The textile cloth is impregnated with rubber, then is fed into a mold and is bonded to the first sealing lip simultaneously with vulcanization molding of the first sealing lip. The rubber comes to be present in a crosslinked state within the textile cloth.
By such a structure of the first sealing lip, a sealability of the sealing surface can be ensured by the rubber, the strength of the sealing lip can be improved by the textile cloth, and the wear resistance can be improved by the lubricant held in the gaps of the textile cloth and the rubbery elastomer.
The term “rubber” is used herein in a broad sense covering various rubbery elastic bodies.
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Anzue Kaoru
Furuyama Hideyuki
Mizunoya Kouichi
Yamanaka Satoshi
Jacobson Price Holman & Stern PLLC
Knight Anthony
NOK Corporation
Pickard Alison K.
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