Rotary expansible chamber devices – Working member has planetary or planetating movement – Helical working member – e.g. – scroll
Reexamination Certificate
1999-03-16
2001-01-16
Denion, Thomas (Department: 3748)
Rotary expansible chamber devices
Working member has planetary or planetating movement
Helical working member, e.g., scroll
C418S151000, C417S350000, C029S888022, C310S051000, C310S261100, C310S157000, C074S603000, C074S573110
Reexamination Certificate
active
06174149
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the attachment of a counterweight to a rotating shaft in a way that simplifies the attachment.
Counterweights are often utilized on rotating shafts to balance forces that might be occurring along the shaft as the shaft rotates. As one example, in a scroll compressor, a shaft is driven by an electric motor to drive an orbiting scroll member. The orbiting scroll member is driven to orbit relative to a second scroll member. The counterweight is utilized to balance forces that are created by the orbiting scroll member.
Typically, counterweights have been attached to the shaft by any one of several attachment methods. As an example, the counterweights have been press-fit or shrunk-fit onto the shafts. Further, staking, swaging or other positive attachment methods have been utilized. These methods have required the counterweight to be formed rather precisely, and further have added the additional costs of the individual attachment methods.
It would be desirable to reduce the cost and complexity of attaching the counterweight to the shaft.
SUMMARY OF THE INVENTION
In a disclosed embodiment of this invention, structure is provided on the shaft and on the motor rotor to hold the counterweight. The counterweight is not positively attached to the shaft, but rather is captured.
In a disclosed embodiment of this invention, the counterweight is utilized in a scroll compressor. However, it should be understood that the counterweight attachment structure and method would have application in other rotating devices.
In one embodiment, the shaft is formed with an enlarged ledge that captures a first side of the counterweight. The motor rotor end ring axially captures the other side of the counterweight. The counterweight is preferably formed with an axially enlarged portion which is captured between the ledge and the end cap, and an axially larger portion which provides the counterweight function. The end cap may also be provided with locator lugs which abut both sides of the axially enlarged portion to ensure that the counterweight does rotate with the shaft.
In a preferred embodiment of this invention, the counterweight has a bore with a draft that expands radially outwardly in a direction moving away from the scroll compressor, and toward the motor. This facilitates the attachment of the counterweight to the shaft, and facilitates the holding of the counterweight at a predictable position on the shaft.
In a method according to the present invention, the shaft is formed with a ledge. The counterweight is initially placed on the shaft, and the motor rotor is then placed onto the shaft and secured to the shaft. Various methods for attaching the motor rotor may be utilized. The motor rotor thus captures the counterweight between the shaft ledge and the motor rotor structure.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
REFERENCES:
patent: 4889475 (1989-12-01), Gannaway et al.
patent: 4992033 (1991-02-01), Caillat et al.
patent: 5017107 (1991-05-01), Fraser, Jr. et al.
patent: 5439361 (1995-08-01), Reynolds et al.
patent: 0 623 748 (1994-11-01), None
patent: 403175185 (1991-07-01), None
patent: 405288168 (1993-11-01), None
Carlson & Gaskey & Olds
Denion Thomas
Scroll Technologies
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