Refrigeration system with capacity control

Claim 2

The combination of a refrigeration system including an unloadable, hermetic shell, multi-cylinder compressor having an always loaded discharge port and an unloadable discharge port, and a non-unloading, hermetic shell, multi-cylinder compressor, said shells of said compressors being connected to receive suction gas returned from said system and being in open communication with each other, a condenser arrangement including a split condenser coil having one part connected by a first line to said always loaded discharge port, and another part connected by a second line to said unloadable discharge port, and another condenser connected by third line means to the discharge of said non-unloading compressor, and means to effect isolation from the remainder of said refrigeration system, of the inlet and outlet of said another part of said split condenser during operation of said unloadable compressor in an unloaded mode, and of the inlet and outlet of said another condenser during periods of nonoperation of said non-unloading compressor.

Claim 3

The combination of claim 1 wherein: said shells are connected in tandem to receive said suction gas from said system first to said unloadable compressor and then said non-unloading compressor.

Claim 4

The combination of claim 1 including: control means to effect capacity control in steps for successively reduced capacity by operating both said compressors fully loaded for maximum capacity, operating said unloadable compressor half loaded and said non-loading compressor fully loaded for three-fourths capacity, operating said unloadable compressor fully loaded with said non-unloading compressor shut down for half capacity, and operating said unloadable compressor half loaded with said non-unloading compressor shut down for one-fourth capacity.

Claim 5

The combination of claim 1 wherein: said means to effect isolation includes a check valve and a solenoid valve in both said second line and said third line means; means for operating each of said solenoid valves in accordance with the discharge of said second line and to said third line means.

Claim 6

The combination of claim 4 including: a relief line connecting said third line means upstream of said solenoid valve to the suction side of the refrigeration system, said line including valve means therein having a closed position when said non-unloading compressor is operating, and an open position when said non-unloading compressor is shut down.

Claim 7

In a refrigeration system including an unloadable, hermetic shelL, multi-cylinder compressor having an always loaded discharge port and an unloadable discharge port, and a non-unloading, hermetic shell, multi-cylinder compressor, said shells of said compressors being connected to receive suction gas returned from said system and being in communication with each other, a condenser arrangement including a split condenser coil having one part connected by a first line to said always loaded discharge port, and another part connected by a second line to said unloadable discharge port, and another condenser connected by third line means to the discharge of said non-unloading compressor, and valve means in both said second line and said third line means to close off said lines in response to the absence of discharge gas flow in said second line and said third line means respectively, each of said valves having a pilot chamber connected to said always loaded discharge part for creating a force in a closing direction corresponding to the discharge pressure in said first line.

Claim 8

In a refrigeration system including an unloadable, hermetic shelL, multi-cylinder compressor having an always loaded discharge port and an unloadable discharge port, and a non-unloading, hermetic shell, multi-cylinder compressor, said shells of said compressors being connected to receive suction gas returned from said system and being in communication with each other, a condenser arrangement including a split condenser coil having one part connected by a first line to said always loaded discharge port, and another part connected by a second line to said unloadable discharge port, and another condenser connected by third line means to the discharge of said non-unloading compressor, and valve means in both said second line and said third line means to close off said lines in response to the absence of discharge gas flow in said second line and said third line means respectively, each of said valves having a pilot chamber connected to said always loaded discharge part for creating a force in a closing direction corresponding to the discharge pressure in said first line.

Claim 9

In a refrigeration system according to claim 6 wherein: each of said valves includes an inlet chamber connected to receive discharge gas from its respective line and line means; a stepped piston interposed between said pilot chamber and said inlet chamber, the end of said piston presented to said pilot chamber having a reduced cross sectional area relative to the end of said piston presented to said inlet chamber so that said piston is movable in the direction of said pilot chamber to open in response to discharge gas pressure imposed in both said pilot chamber and said inlet chamber.

Claim 10

In a refrigeration system having at least one unloadable compressing apparatus and at least one always loaded compressing apparatus, and separate discharge lines for said compressing apparatuses connected to respectively separate condenser coil surfaces, valve means in the discharge lines connected to said unloadable compressing apparatus for closing said lines in response to an unloaded condition of the particular compressing apparatus serving said lines.

Claim 11

In a refrigeration system having at least one unloadable compressing apparatus and at least one always loaded compressing apparatus, and separate discharge lines for said compressing apparatuses connected to respectively separate condenser coil surfaces, valve means in the discharge lines connected to said unloadable compressing apparatus for closing said lines in response to an unloaded condition of the particular compressing apparatus serving said lines.

Claim 12

In a system according to claim 8 wherein: said valve means comprises a pilot type valve having a movable, stepped-diameter piston in a correspondingly stepped-diameter chamber, the cross sectionally smaller end of said piston being subject to pressure from always loaded compressing apparatus, and the opposite, cross-sectionally larger end being subject to pressure from said unloadable compressing apparatus, so that when both said compressing apparatuses operate said piston moves in the direction of said smaller end to effect opening of said valve, and when only said always loaded compressing apparatus is operating said piston moves in the opposite direction to close said valve.