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US 4,583,373 AGranted
Constant evaporator pressure slide valve modulator for screw compressor refrigeration system
AssigneeDunham-Bush, Inc.
InventorDavid N. Shaw
Life of this patent
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AssigneeDunham-Bush, Inc.
InventorDavid N. Shaw
Estimating the term…
A space conditioning closed loop refrigeration system, particularly a vehicle air conditioning system utilizing a positive displacement compressor having a slide valve for varying the capacity and shiftable between full load and full unload positions and vice versa and driven therebetween by a linear fluid motor having a movable member coupled to the slide valve and forming a first chamber which is normally dumped via a slide valve modulator to compressor suction pressure and a second chamber open to compressor discharge pressure. A restricted passage between chambers tends to cause the first chamber to reach compressor discharge pressure absent that chamber dumping to suction. The slide valve modulator selectively activates the venting of the first chamber to compressor suction pressure in response to fall of suction pressure below a predetermined value to prevent a serious reduction in evaporator temperature caused by either a reduction in load on the evaporator, an increase in speed of the compressor, or both. A temperature unloader in the form of a normally closed valve is connected within a bypass passage by passing the slide valve modulator to insure dumping of the first chamber to suction in response to a predetermined drop in temperature of the space to be conditioned, irrespective of the level of compressor suction pressure.
In a closed loop refrigeration system for conditioning a space, said system comprising a positive displacement compressor, a condenser, and an evaporator, conduit means carrying a condensible refrigerant working fluid and connecting said compressor, condenser and evaporator in closed loop series and including expansion means upstream of said evaporator, said compressor including a shiftable slide valve for movement between a first position to effect full unloading of the compressor and a second position to effect full loading of the compressor, and vice versa, a fluid motor for shifting said slide valve between said first and second positions, said fluid motor comprising a movable member operatively coupled to said slide valve, means defining with said movable member a first sealed chamber remote from said slide valve and a second sealed chamber proximate to said slide valve on respective sides of said movable member, means for subjecting said second chamber to compressor discharge pressure;
A climate control system for controlling the temperature of air in a controlled area, said system including a compressor operable over a varying load level, said system being capable of at least a cooling mode, wherein said compressor is activated to reduce said air temperature said control system comprising:
A control system for controlling the temperature of air in a controlled area, said system including a compressor operable over a varying load level, said system being capable of at least a cooling mode, wherein said compressor is activated to reduce said air temperature said control system comprising:
Dependencies are inferred from the claim text.