Rotary expansible chamber devices – Working member has planetary or planetating movement – Helical working member – e.g. – scroll
Reexamination Certificate
1999-08-04
2001-05-08
Vrablik, John J. (Department: 3748)
Rotary expansible chamber devices
Working member has planetary or planetating movement
Helical working member, e.g., scroll
C418S270000, C137S533170
Reexamination Certificate
active
06227830
ABSTRACT:
BACKGROUND OF THE INVENTION
This application relates to a variety of scroll compressor discharge check valve locations which are positioned relatively close to the discharge opening from the compression chambers.
Scroll compressors have become widely utilized in many refrigerant compression applications. Scroll compressors are relatively efficient, and thus are being utilized in more and more applications. In a typical scroll compressor, the compression chambers are defined by two generally spiral wraps. The spiral wraps are formed on individual scroll members, and extend from a base plate. The spiral wraps interfit to define compression chambers. One of the spiral wraps is driven to orbit relative to the other, and the size of the compression chambers changes to compress the entrapped refrigerant.
As the compression chamber nears the end of its cycle, the entrapped gas is exposed to a discharge port. The entrapped gas leaves the discharge port and moves through a check valve to a discharge plenum. The discharge check valve is typically opened during operation of the scroll compressor. The check valve closes the discharge port and desirably prevents backflow once the compressor is stopped.
In scroll compressors there is a phenomenon known as reverse rotation. This occurs when as compressed gas moves back through the discharge port and into the compression chamber to drive the scroll compressor wraps relative to each other in a reverse direction at shutdown of the compressor. This is undesirable, and results in unwanted noise and potential harm to the compressor components.
One method of minimizing the amount of reverse rotation is to minimize the volume of compressed gas which will move between the scroll wraps at shutdown. The present invention is directed to optimizing the location of the check valve to minimize the volume gas which is likely to move back into the compression chambers.
SUMMARY OF THE INVENTION
In a disclosed embodiment of this invention, the base of a scroll compressor wrap is formed with the discharge port and also receives the discharge check valve in an enclosed chamber. A stop for the check valve is also preferably formed in the base plate.
In a first embodiment, the discharge fluid moves through the discharge port and into a discharge check valve chamber formed in the base plate in a first direction. The gas in the discharge check valve chamber then communicates with a radially outwardly directed outlet port to pass outwardly through the base plate and into a discharge plenum. An opening at the opposed end of the base plate from the discharge port is provided with a stop which provides a check valve seat. The check valve seat is provided with a tap which communicates to a discharge pressure chamber.
At shutdown, the discharge pressure in the discharge pressure chamber rapidly biases the check valve to its closed position. Mounting the check valve within the base plate insures that the distance between the check valve and the compression chambers in the scroll compressor is relatively small. This minimizes the amount of backflow discharge fluid, and hence minimizes the amount of reverse rotation.
In other embodiments, the same basic arrangement is used. However, the outlet ports are formed at circumferentially spaced locations around a plug which forms the check valve stop. Thus, the fluid flows into the check valve chamber in the base of the scroll member, and then flows radially outwardly, to ports. The outlet ports have a first port that extends generally perpendicular to the discharge port, and a second portion which extends parallel to the discharge port and which communicates to the discharge pressure chamber.
In another embodiment, a separate plug is utilized which extends into the discharge port. The plug is mounted within a separator plate spaced upwardly from the scroll wrap base plate. The plug is provided with a check valve chamber and a stop at an opposed end formed by a closure plug. The stop has an opening which extends through to a chamber at discharge pressure such that the check valve will rapidly close.
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.
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patent: 5173042 (1992-12-01), Chambers
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Fields Gene Michael
Hill Joe T.
Milliff Tracy L.
Williams John R.
Young Michael R.
Carlson & Gaskey & Olds
Scroll Technologies
Vrablik John J.
LandOfFree
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