Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
1998-10-23
2001-08-28
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S394000, C277S549000
Reexamination Certificate
active
06279914
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sealing apparatus applicable for a shaft sealing portion of various devices and appliances, particularly to a lip-type sealing apparatus provided with a sealing lip.
2. Description of the Related Art
There is conventionally known a lip-type seal in which a metal ring outer periphery is engaged with, and fixed to, the inner periphery of a housing, and a sealing lip supported by the metal ring slides in close contact with a shaft peripheral surface. In a lip-type sealing apparatus, it is the usual practice to cover the outer periphery of the metal ring with a stationary sealing portion made of a rubber-like elastic material so as to ensure sealing of a stationary portion over the shaft hole inner periphery of a housing.
When using a pressurized liquid for sealing, however, a stop ring is engaged with the shaft hole inner periphery of the housing, or when a bearing is arranged on the open-air side of the sealing apparatus, a bearing outer race is used for preventing coming-off.
When a stationary seal is not provided on the outer periphery of the metal ring, the open-air side end of the metal ring outer periphery certainly engages with the stop ring. When a stationary seal is provided on the metal ring outer periphery, however, there is usually produced a gap of about 1 mm between the metal ring outer periphery and the inner periphery of the sealing ring attachment hole of the housing, which reduces the size of an engagement margin with the stop ring, and this may make stopping unstable. In some cases, a deformation of the stop ring may cause inclination of the sealing apparatus, thus leading to a lower sealing property.
When coming-off is prevented by means of a bearing, it is necessary to achieve engagement with the outer race while avoiding interference with the inner race rotating with the shaft. However because there are diverse and various sizes of bearing, it may happen that the inside-diameter end position of the outer race is larger than the bore diameter of the seal attachment hole. It is therefore necessary to consider a stopper in response to a particular size of bearing.
SUMMARY OF THE INVENTION
The present invention has an object to provide a sealing apparatus of a type having a stationary sealing portion on the outer periphery of a metal ring, which ensures support by means of a stop functional member, and permits display of a satisfactory sealing property for a long period of time.
To achieve the above object, the present invention provides a sealing apparatus of a lip-type seal structure, which is fixed to one of relatively movable two members and is slidable in tight contact to another one of movable members, the sealing apparatus comprising:
a reinforcing ring, made of a rigid material, having a cylindrical portion, and fixed to the one of movable members;
a stationary sealing portion mounted to the reinforcing ring so as to seal a gap between the reinforcing ring and the one of movable members;
a sealing lip supported by the reinforcing ring to be slidable in contact to the other one of movable members;
a stopper member (stop functional member) fixed to the one of movable members for preventing the reinforcing ring from coming off through axial engagement with the stopper member,
wherein the reinforcing ring is provided with an engagement area expanding section being arranged near the one of movable members and expanding an engagement area with the stopper member.
When a sealing apparatus, such as that of the present invention having the configuration as described above, is arranged closer to one member such as a housing than the cylindrical portion of the reinforcing ring, and the engagement area expanding section for expanding the engagement area with the stop functional member such as a stop ring is provided as a part of the reinforcing ring, the apparatus firmly engages with the stop functional member, thus permitting display of a stable stop function.
Particularly when a stop ring is used as a stop functional member, the position of the stopper acting point upon pressuring by the sealing liquid shifts to the side of one member side than that in the conventional art, and as a result, a relatively short distance between the action point and the fulcrum is set, leading to a relatively small moment acting on the stop ring, thus permitting effective prevention of deformation of the stop ring.
The engagement area is known also as the interference area, the contact region or the contact area, and can be expressed in terms of the radial length such as the engagement length, the interference length or the contact length.
In one aspect of a preferred embodiment, the stopper member is a stop ring to be engaged with an engagement groove formed to an open-air side end portion of a seal fitting hole on an inner periphery of a shaft hole of a housing as the one of movable members, and the reinforcing ring comprises a cylindrical portion to which the stationary sealing portion made of a rubber-like elastic material is applied, an engagement area expanding section, continuous to the open-air side end portion of the cylindrical portion, having a diameter larger than that of the cylindrical portion and being arranged near the inner periphery of the shaft hole, and an inward flange portion extending from the engagement area expanding section in a radially inward direction, the engagement area expanding section being positioned within the seal fitting hole and having a largest outer diameter smaller than a diameter of the seal fitting hole and larger than an inner diameter of the stop ring.
When the stop functional member is a stop ring as described above, the engagement area with the stop ring is expanded and certain stopper action can be ensured by expanding the engagement area expanding section over the diameter of the cylindrical portion within a range of bore diameter of the seal attachment hole.
Since the engagement area expanding section is provided at an open-air side end position on the outer periphery of the metal ring, the inward flange portion has a higher bending rigidity as compared with a case without an engagement area expanding section. As a result, the inward flange portion is harder to bend even under the action of a sealing pressure, thus backing up the sealing lip and maintaining the contact state of the sealing lip.
A large-diameter hole having a diameter larger than that of the seal fitting hole is formed on the inner periphery of the shaft hole of the housing on the open-air side of the seal fitting hole, a tapered hole which gradually diverges toward the open-air side and is continuous to the large-diameter hole is formed at the open-air side end portion of the seal fitting hole, and the engagement groove for the stop ring is formed at a boundary position between the open-air side end portion of the tapered hole and the large-diameter hole.
When a tapered hole is provided as described above, the stop ring has a slightly larger size, resulting in the inside-diameter end position of the stop ring somewhat shifting radially outside, whereas stopper action is ensured by the engagement area expanding section.
Further, the tapered hole guides the stationary sealing portion, and becomes easier to attach.
A claw extending from an inner-diameter end portion of the inward flange portion in an axial direction toward the axial open-air side is provided to the inner-diameter end portion of the reinforcing ring, and the claw has an end portion bent outward in a radial direction.
Provision of a claw makes it easier to withdraw the sealing apparatus. Upon withdrawal, a bending moment acts on the inward flange portion of the metal ring. However, because bending rigidity of the inward flange portion is improved by the engagement area expanding section, the inward flange portion becomes less susceptible to deformation.
The sealing lip is composed of a first sealing lip section which is provided on a first sealing member formed of a rubber-like elastic material to be integral with th
Ikeda Yasuhiro
Munekata Shinobu
Yamanaka Satoshi
Armstrong, Westerman, Hattori, McLeland & Naughton, LLP.
Eagle Industry Co. Ltd.
Knight Anthony
Schwing Karlena D.
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