A flange is provided in the first member, projecting radially inward into the annular recess, thus forming an annular channel in the first member. An opening is provided, opening from the lowest point in the channel of the first member to the outer surface.
The first member is fixedly attachable to the housing so as to allow for free rotation of the shaft within the first member. A second ring member is positioned axially internal to the first member and is provided with an outer annular surface facing the inner surface of the first member and an inner annular surface facing internally of the housing.
The second member is fixedly attachable to the shaft and is provided with a flange which extends into the recess of the first member. A seal is thus provided which traps contaminants in the channel of the first member, allowing them to flow back to the atmosphere through the opening in the first member, whether the shaft is rotating or in a static position.
Many industries require the use of machines in which a rotatable shaft is contained by a housing. The housing usually contains lubricated bearings and sometimes additional attachments to the shaft such as turbine blades or gears. There are manytypes of seals provided between a shaft and a housing so as to prevent the leakage of lubricants from the housing and/or to prevent external contaminants from entering the housing along the shaft. In high speed operations of such rotating shaftmechanisms, contaminants to the internal lubricant result in increased wear, costly replacement of parts and, consequently, down time for the mechanism.
It is known to provide a sealing ring assembly comprising a first ring fixed to the housing and a second ring exterior to the housing and fixed to rotate with the shaft. Such an assembly is disclosed by U.S. Pat. No. 4,002,479, invented byDavid C. Orlowski and issued on May 10, 1977. In Orlowski, the first ring is held fixed to the housing by an o-ring and has an annular recess which matingly receives an annular flange of the rotating second member so as to allow free rotation withoutcontact between the flange and the recess. The contaminants are theoretically discharged through an opening in the bottom of the recess in the first ring. The second ring is secured to the shaft by an o-ring. This arrangement has failed to preventcertain contaminants from entering the housing.
An example of such a problem arises in the steam turbine industry, where such a seal is subject to an environment of steam, itself a contaminant, and also particles carried in the steam. In such anenvironment, steam easily penetrates the crevices between the first and second rings, condenses and is carried into the housing along the rotating shaft. An even greater contamination problem is created when the shaft is at rest and contaminants areallowed to build up and travel along the surfaces of the static rings to the static shaft which provides less frictional resistance to the contaminants than a moving shaft. A further problem arises when the o-rings or the sealing rings must be changed,which requires extensive down time while other components are removed in order to allow the sealing rings to be removed from the shaft.
Considering the above, it is an object of this invention to provide a ring seal between a housing and a rotatable shaft which prevents external contaminants such as steam from entering the housing, whether the shaft is rotating or static.
Accordingly, a ring seal between a housing and a rotatable shaft is provided, comprising a plurality of ring members generally concentric with the shaft. A first ring member is fixedly and sealingly attachable within the housing and has an outerannular surface facing externally of the housing and an inner annular surface facing internally of the housing. A second ring member is positioned axially internal to the first member and is provided with an outer annular surface facing the innersurface of the first member and an inner annular surface facing internally of the housing. The second member is fixedly and sealingly attachable to the shaft so as to rotate relative to the fixed positon of the first ring member.
The first ring memberhas an annular recess in its inner surface which receives an annular flange formed on the outer surface of the second member. A flange in the recess of the first member also forms a channel through which captured contaminants flow downward to an exitopening provided in the first member. The first and second ring members can be spilt so as to facilitate easy installation and removal. A third ring member is then provided which locks the second ring member into position and holds that positionrelative to the shaft and the first member.
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