Heat pump system with high efficiency reversible helical screw rotary compressor

In a refrigeration system including:

• a positive displacement rotary compressor including a casing having axially spaced end walls and axially spaced suction and discharge ports within said casing open to the casing interior, rotor means mounted for rotation within said casing and forming during rotation closed threads sealed from said ports, and said refrigeration system further including a condenser coil and an evaporator coil and conduit means fluid connecting said compressor, said condenser and said evaporator coil in a closed series loop, with said conduit means carrying a mass of refrigerant working fluid for circulation therein and expansion valve means upstream of said evaporator coil for expanding refrigerant within said evaporator coil and motor means for driving said rotor means for causing refrigerant in vapor form to enter said suction port, to be compressed within said closed thread and to be discharged under relatively high pressure at said discharge port, the improvement comprising:
• at least one axially extending recess within the compressor casing in open communication with the rotor threads,
• a first slide valve axially slidable relative to said casing and sealably covering said recess with the interface of the first slide valve being complementary to the casing confronted by the opening of said recess,
• means for axially shifting said first slide valve,
• an ejection port within said slide valve open to the closed thread for providing partially compressed refrigerant vapor, and a second condenser coil, secondary loop conduit means for connecting said ejection port and said second condenser coil and forming a secondary closed refrigeration loop in parallel with said closed series loop, whereby said ejection port supplies intermediate pressure refrigerant which condenses at a lower condenser pressure than that of said first condenser, with said second condenser supplying a separate load from that of said first condenser, and;
• means responsive to the load on the second condenser for controlling the means for axially shifting said first slide valve to vary the pressure of the refrigerant vapor at the point of removal from said compressor by way of said ejection port.

In a refrigeration system including:

• a positive displacement rotary compressor including a casing having axially spaced end walls and axially spaced suction and discharge ports within said casing open to the casing interior,
• rotor means mounted for rotation within said casing and forming during rotation closed threads sealed from said ports,
• and said refrigeration system further includes a first coil mounted within an enclosure to be conditioned and a second coil mounted external of said enclosure and within the ambient,
• conduit means for fluid series connecting said compressor and said first and second coils in a closed loop with said conduit means carrying a mass of refrigerant working fluid for circulation therein and expansion valves intermediate of said coils for operating one of said two coils as a refrigerant evaporator,
• motor means for driving said rotor means for causing refrigerant gas to enter said suction port, to compress said gas within said closed threads and to discharge compressed refrigerant gas under high pressure at the discharge port,
• a first axially extending recess within the casing in open communication with the rotor threads,
• a first slide valve axially slidable relative to said casing and sealably covering said first recess with the interface of said first slide valve being complementary to the casing confronted by the opening of said first recess, said first slide valve being movable between extreme positions, in one of which said suction port is fully open and the other in which said suction port is closed,
• means for axially shifting said first slide valve for varying the capacity of the compressor to meet system load variations,
• the improvement comprising:
• a third heat exchange coil coupled to said closed loop conduit means and subject to a load independent of that affecting said first and second coils,
• a second axially extending recess within the casing in open communication with the rotor threads,
• a second slide valve axially slidable relative to said casing and sealably covering said second recess with the interface of said second slide valve being complementary to the casing confronted by the opening of said second recess,
• an injection port carried by said second slide valve,
• means for fluid connecting said injection port to said third heat exchange coil, and
• means for axially shifting said second slide valve to place said injection port at a closed thread position dependent upon a parameter of operation of said third heat exchange coil.

In a refrigeration system including:

• a positive displacement rotary compressor including a casing having axially spaced end walls and axially spaced suction and discharge ports within said casing open to the casing interior,
• rotor means mounted for rotation within said casing and forming during rotation closed threads sealed from said ports,
• said system further including a first coil mounted within an enclosure to be conditioned and a second coil mounted external of said enclosure and within the ambient,
• conduit means for fluid series connecting said compressor and said first and second coils in a closed loop with said conduit means carrying a mass of refrigerant working fluid for circulation therein and expansion valves intermediate of said coils for operating a selected coil as a refrigerant evaporator,
• motor means for driving said rotor means for causing refrigerant gas to enter said suction port, to be compressed within said closed threads and to be discharged under high pressure at said discharge port,
• the improvement comprising:
• a pair of axially extending recesses within the casing in open communication with the rotor threads,
• a first slide valve axially slidable relative to said casing and sealably covering one recess with the interface of the slide valve being complementary to the casing confronted by the opening of said one recess,
• a second slide valve axially slidable relative to said casing for sealably covering the opening of the other recess with the interface of the second slide valve being complementary to the casing confronted by the opening of said other recess, said second slide valve carrying a port opening to the closed threads for sensing the compressed gas pressure within a closed thread immediately adjacent said discharge port,
• means for comparing the closed thread pressure just before opening to said discharge port with said compressor discharge pressure at the compressor discharge port and for shifting said first slide valve axially to equalize these pressures and to prevent undercompression or overcompression of the compressor working fluid within the closed thread prior to discharge,
• an injection port within said first slide valve open to the closed threads,
• means for fluid connecting said injection port to an element of the refrigeration system carrying refrigerant in vapor form at a pressure lower than that of the compressor discharge port, and
• means responsive to an operating parameter of said closed loop refrigeration system for controlling the means for axially shifting said first slide valve to vary the point of injection of refrigerant vapor into said compressor.

In a refrigeration system including:

• a positive displacement rotary compressor including a casing having axially spaced end walls and axially spaced suction and discharge ports within said casing open to the casing interior,
• rotor means mounted for rotation within said casing and forming during rotation closed threads sealed from said ports,
• and said refrigeration system further includes a first coil mounted within an enclosure to be conditioned and a second coil mounted external of said enclosure and within the ambient,
• conduit means for fluid series connecting said compressor and said first and second coils in a closed loop with said conduit means carrying a mass of refrigerant working fluid for circulation therein and expansion valves intermediate of said coils for operating one of said two coils as a refrigerant evaporator,
• motor means for driving said rotor means for causing refrigerant gas to enter said suction port, to compress said gas within said closed threads and to discharge compressed refrigerant gas under high pressure at the discharge port,
• a first axially extending recess within the casing in open communication with the rotor threads,
• a first slide valve axially slidable relative to said casing and sealably covering said first recess with the interface of said first slide valve being complementary to the casing confronted by the opening of said first recess, said first slide valve being movable between extreme positions, in one of which said suction port is fully open and the other in which said suction port is closed,
• means for axially shifting said first slide valve for varying the capacity of the compressor to meet system load variations,
• the improvement comprising:
• a third heat exchange coil coupled to said closed loop conduit means and subject to a load independent of that affecting said first and second coils,
• a second axially extending recess within said casing in open communication with the rotor thread,
• a second slide valve axially slidable relative to said casing and sealably covering said second recess with the interface of the second slide valve being complementary to the casing confronted by the opening of said second recess,
• an ejection port carried by said second slide valve and opening to the compressor closed threads intermediate of said compressor suction and discharge ports,
• means for fluid connecting said ejection port to said third heat exchange coil for supplying compressed refrigerant vapor thereto independently of refrigerant flow to said first and second coils, and
• means responsive to heat exchange load on said system coil for shifting said second slide valve to vary the supply of refrigerant supplied by said ejection port to said third heat exchange coil.

In a heat pump system including:

• a positive displacement rotary compressor including a casing having axially spaced ports in fluid communication with said casing interior, rotor means mounted for rotation within said casing and forming during rotation closed threads sealed from said ports, and said heat pump system further including a first coil mounted within an enclosure to be conditioned for selective heating and cooling of said enclosure, a second coil external of said enclosure and within the ambient and acting either as a heat sink or heat source, and conduit means for fluid, series connecting said compressor and said first and second coils in a closed loop with said conduit means carrying a mass of refrigerant working fluid for circulation therein and expansion valve means intermediate of said coils for operating a selected coil as a refrigerant evaporator, bidirectional motor means for driving said rotor means in either of two directions for causing refrigerant gas to enter selectively one of said ports under suction, to compress said gas within said closed threads and to discharge compressed refrigerant gas under high pressure from said compressor at said other port and vice versa, the improvement comprising:
• a pair of axially extending recesses within the casing in open communication with the rotor threads,
• a first slide valve sealably axially slidable on said casing relative to one recess with the interface of the slide valve being complementary to the casing confronted by the opening of said one recess,
• a second slide valve sealably axially slidable on said casing and being complementary to the casing confronted by the opening of the other recess,
• said slide valves being movable between extreme positions in one of which a given port is fully open and the other in which a given port is closed, each slide valve carrying means for sensing the compressed gas pressure within a closed thread immediately adjacent the port within said casing formed by its recess,
• motor means for axially shifting said slide valves,
• means operatively coupled to said sensing means for selectively comparing a closed thread pressure just before opening to the port acting as the discharge port for the compressor with said compressor discharge pressure at that port depending upon the direction of rotation of said rotor means,
• means for operating said motor means for shifting the other slide valve associated with the port acting as the suction port for said compressor under such conditions for varying the capacity of the compressor to meet heat pump system load variations, and
• means for operating said motor means for shifting said slide valve associated with the discharge port in response to said comparing means to equalize the closed thread pressure immediately adjacent the discharge port with the compressor discharge pressure at said compressor discharge port to prevent undercompression and overcompression of the compressor working fluid within the closed thread prior to discharge.