Capacity modulated scroll compressor

Abstract

A scroll compressor has a biasing chamber which contains a pressurized fluid. The pressurized fluid within the chamber biases the two scroll members together. A rotatable ring is attached to one of the scroll members to open and close a passage leading to this biasing chamber. When the ring opens the passage in one embodiment, this releases the pressurized fluid to remove the load, biasing the two scroll members together. When the biasing load is removed, the two scroll members separate, creating a leakage path between discharge and suction to reduce the capacity of the scroll compressor. When the ring opens the passage in another embodiment, a delayed suction passage is opened to reduce the capacity of the compressor.

Description

FIELD OF THE INVENTION [0001] The present invention relates to capacity modulation of compressors. More particularly, the present invention relates to the capacity modulation of a scroll compressor by controlling the fluid pressure in a chamber where the fluid pressure in the chamber biases the two scrolls together. BACKGROUND AND SUMMARY OF THE INVENTION [0002] Capacity modulation is often a desirable feature to incorporate into the compressors of air conditioning and refrigeration systems in order to better accommodate the wide range of loading to which the systems may be subjected. Many different approaches have been utilized for providing this capacity modulation feature. These approaches have ranged from control of the suction inlet of the compressor to bypassing compressed discharge gas back into the suction pressure zone of the compressor. With a scroll-type compressor, capacity modulation has often been accomplished by using a delayed suction approach which comprises providi...

AI Technical Summary

Benefits of technology

[0003] More recently, compressor unloading and, thus, capacity modulation has been accomplished by cyclically effecting axial or radial separation of the two scroll members for predetermined periods of time during the operating cycle of the compressor. In order to facilitate the axial unloading or axial separation of the two scroll members, a biasing chamber is formed in or adjacent one of the two scroll members; and this biasing chamber is placed in communication with a source of compressed fluid in a pressure chamber or the discharge chamber of the compressor. The fluid in the biasing chamber is cyclically released to the suction area of the compressor to facilitate the unloading of the compressor.

[0004] The continued development of capacity modulated scroll compressors has been directed towards the simplification of the capacity modulation devices in order to lower the costs of the capacity modulated systems, as well as simplifying the overall manufacture, design and development of these capacity modulated systems without sacrificing performance and more preferably increasing the performance and / or reliability of the capacity modulation system.

[0005] The present invention provides the art with a capacity modulated compressor which vents an existing intermediate pressurized chamber cyclically to suction to modulate the capacity of the compressor. The existing intermediate pressurized chamber is utilized in the compressor to bias the two scrolls together as well as to bias a floating seal into contact with a partition or the shell to seal a leakage passage between discharge pressure and the suction pressure zone of the compressor. A sealing system is incorporated into the scroll member defining the intermediate pressurized chamber. The sealing system incorporates a lip seal which improves both the performance and the reliability of the capacity modulation system.

Problems solved by technology

This delays the point at which the sealed compression chambers are formed and, thus, delays the start of compression of the suction gas.

This method of capacity modulation has the effect of actually reducing the compression ratio of the compressor.

While these delayed suction systems are effective at reducing the capacity of the compressor, they are only able to provide a predetermined amount of compressor unloading with the amount being determined by the position of the unloading ports along the end plate.

While it is possible to provide multiple step unloading by incorporating a plurality of unloading ports at different locations, this approach becomes costly and it requires additional space to accommodate the separate controls for opening and closing each set of ports.

Even when using multiple unloading ports, it is typically not possible to control the capacity of the compressor between 0% and 100% using this delayed suction technique.

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