Rotary kinetic fluid motors or pumps – Bearing – seal – or liner between shaft or shaft sleeve and...
Reexamination Certificate
2000-05-02
2001-07-17
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Bearing, seal, or liner between shaft or shaft sleeve and...
C415S170100, C415S174200, C415S111000, C384S585000, C384S492000
Reexamination Certificate
active
06261061
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to an apparatus and method for mounting a bearing. More particularly, in one embodiment, the present invention defines an apparatus for mounting a ceramic inner race of a bearing for a gas turbine engine. Although the present invention was developed for use in a gas turbine engine, certain applications may be outside of this field.
There is a continuing need to improve the efficiency and simplify the construction of the gas turbine engine. One approach is the development of materials for bearings that do not require lubrication, or that use lubrication systems which are simplified. Ceramic materials, particularly silicon nitride, are candidate bearing materials for such advanced gas turbine engines. Other materials, including variants of ceramics and metals, will doubtless be proposed in the future.
There are problems, however, in the use of ceramics when the ceramic material is under tension. Ceramics are typically characterized with low fracture toughness, meaning that imperfections in the material result in the bearing being susceptible to tensile failure. Other materials may have similar problems, or may be better suited to bearing applications if the degree of tension in the material can be controlled.
Various inventions have been proposed for providing bearings within gas turbine engines. Examples of bearings can be found in the following U.S. Pat. No. 4,792,244 issued to Yamashita et al; U.S. Pat. No. 5,176,456 issued to Takebayashi; U.S. Pat. No. 5,575,571 to Takebayashi et al.; U.S. Pat. No. 4,968,158 issued to Atkinson et al.; U.S. Pat. No. 5,306,565 issued to Corbin et al; U.S. Pat. No. 4,997,296 to Narita et al.; U.S. Pat. No. 5,197,808 to Takata; U.S. Pat. No. 5,568,985 to Schutte; U.S. Pat. No. 5,600,867 to Niwa et al. al.; U.S. Pat. No. 5,197,808 to Takata; U.S. Pat. No. 5,568,985 to Schutte; U.S. Pat. No. 5,600,867 to Niwa et al.
Even with the variety of earlier designs, there remains a need for an improved apparatus and method for mounting the inner race of a bearing. The present invention satisfies this need in a novel and unobvious way.
SUMMARY OF THE INVENTION
One aspect of the present invention concerns an apparatus which includes a shaft, a ceramic inner race, an intermediate member, and a first separable compression member. The intermediate member is mounted on the shaft, and the inner race is mounted on the intermediate member. The intermediate member permits differential thermal growth between the shaft and the inner race. The separable compression member radially compresses the inner race.
Another aspect of the present invention concerns a method for mounting an inner race of a bearing on a shaft. The method includes providing a gas turbine with a shaft, a ceramic inner race, an intermediate member with a general split ring shape, a first ring and a second ring. The method includes loading a compressive stress into the inner race, and placing the intermediate member on the shaft between the shaft and the inner race. The first ring, second ring, and inner race are urged together in an axial direction. The urging together compresses the inner race in a radial direction.
Another aspect of the present invention concerns an apparatus comprising a gas turbine and a shaft rotatable within the gas turbine. There is an inner race rotatably supporting the shaft, the inner race having an outer diameter, an inner diameter, and two ends, each end having a contact face. The apparatus includes a first ring and a second ring, the first ring and one of the contact faces being urged together, and the second ring and the other of the contact faces being urged together. There is also a plurality of rolling elements in rolling contact with the inner race. The apparatus includes a first separable member mounted to the inner race and a second separable member mounted to the inner race. The first separable member and the second separable member provide a guide for the rolling elements. The one contact face and the first ring are constructed and arranged so as to radially compress the inner race when urged together, and the other contact face and the second ring are constructed and arranged so as to radially compress the inner race when urged together.
In another aspect of the present invention, there is an apparatus including a ceramic inner race mounted by a spring member to a shaft. The spring member provides thermal dissociation between the ceramic inner race and the shaft. The spring member is constructed and arranged so as to not build up internal hoop stresses as the shaft expands.
In yet another aspect of the present invention, there is an apparatus for placing a ceramic inner race in a state of compression. The apparatus includes a first separable member and a second separable member that are interferingly fit onto the outer diameter of the inner race. The first and second compression members also provide a guideway for rolling elements of the bearing.
In yet another aspect of the present invention, there is a method for lubricating a bearing in which the guideways for the rolling elements are fabricated from a material that forms a lubricious oxide coating after exposure to the proper temperature. This oxide coating lubricates the rolling elements.
One object of the present invention is to provide an improved bearing for a gas turbine engine.
Related objects of the present invention will be apparent from the following description.
REFERENCES:
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patent: 4997296 (1991-03-01), Narita et al.
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patent: 5176456 (1993-01-01), Takebayashi et al.
patent: 5197808 (1993-03-01), Takata
patent: 5306565 (1994-04-01), Corbin et al.
patent: 5568985 (1996-10-01), Schutte
patent: 5575571 (1996-11-01), Takebayashi et al.
patent: 5600867 (1997-02-01), Niwa et al.
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patent: 5775816 (1998-07-01), Baranek et al.
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patent: 3706365 C1 (1988-09-01), None
patent: 0 345 214 B1 (1993-08-01), None
patent: 1-295025 (1989-11-01), None
Zaretsky, E.V., Ceramic Bearings for Use in Gas Turbine Engines, NASA Lewis Research Center, Cleveland, OH 44135 Fellow ASME, vol. 111, Jan. 1989.
Baumgartner, H.R., Evaluation of Roller Bearings Containing Hot Pressed Silicon Nitride Rolling Elements, Norton Company, High Performance Ceramics, Worchester, Massachusetts, Nov., 1973.
Hosang, G.W., Turbomach, Sundstrand, AIAA-87-1844 Results and Design Techniques from the Application of Ceramic Ball Bearings to the Meradcom 10 kW Turbine, American Institute of Aeronautics and Astronautics, San Diego, California.
Allison Tolerance Rings (2 pages).
Allison “Prior Art” (1 page).
Allison “Prior Art” (1 page).
USA Tolerance Rings (2 pages).
Look Edward K.
Rolls-Royce Corporation
Woo Richard
Woodard Emhardt Naughton Moriarty & McNett
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