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US 4,697,431 AGranted
Refrigeration system having periodic flush cycles
OwnerRichard H. Alsenzinventor
Life of this patent
Estimating the term…
Abstract
A microprocessor controlled system for use in a refrigeration system which includes a plurality of pulse controlled solenoid flow control valves suitable for use as expansion valves is disclosed. A pulse width modulated control signal is generated for cyclically opening and closing the flow through the solenoid expansion valve. The duty cycle of the pulsed control signal determines the average flow rate through the valve. The microprocessor controls, periodically, the opening of each expansion valve to permit full flow therethrough to flush any accumulated compressor lubrication oil logged in any associated evaporator coils.
Claims18
A refrigeration system comprising:
- (a) compressor means having an inlet and an outlet end;
- (b) a condenser means connected to the outlet end of said compressor means and responsive to a high pressure gaseous phase recirculating refrigerant for condensing the refrigerant from its gaseous to its liquid phase;
- (c) an evaporator means having an inlet and an outlet end connected to the outlet end of said condenser means and to the inlet end of said compressor means, respectively;
- (d) said evaporator means having an associated solenoid-actuated expansion valve having an inlet and an outlet end connected between the outlet end of said condenser means, and the inlet end of said evaporator means, said condenser means delivering high pressure liquid refrigerant to the inlet end of said expansion valve, said refrigerant expanding as it flows through said expansion valve;
- (e) said solenoid-actuated valve including an associated on-off modulator responsive to the instantaneous superheat of said refrigerant in said evaporator means for generating a variable duty cycle on-off modulated solenoid control signal, said solenoid control signal alternatively energizing and de-energizing said associated solenoid-actuated valve for each cycle of said control signal to cycle said valve from a first flow rate position to a second flow rate position without imparting shock waves to the refrigerant thereby to obtain an average flow rate of refrigerant through the valve which results in a desired superheat for the refrigerant in said evaporator means, said valve further including a flush cycle timer means for generating a flush cycle having a time interval during which said associated expansion valve is controlled to permit full flow therethrough to fill said associated evaporator means with liquid refrigerant;
- and
- (f) control means for periodically initiating flush cycles for said expansion valve whereby said valve is opened for full flow therethrough during the flush cycle so that said evaporator means is flushed of compressor lubricant oils which may have accumulated therein.
4 more elements
A refrigeration system comprising:
- (a) a compressor means having an inlet and an outlet end;
- (b) a condenser means having an inlet and an outlet end, the inlet end connected to the outlet end of said compressor means and responsive to a high pressure gaseous phase recirculating refrigerant for condensing the refrigerant from its gaseous to its liquid phase;
- (c) an evaporator means having an inlet and an outlet end connected to the outlet end of said condenser means and to the inlet end of said compressor means, respectively;
- (d) said evaporator means having an associated solenoid actuated expansion valve having an inlet and an outlet end connected between the outlet end of said condenser means and the inlet end of said evaporator means, said condenser means delivering high pressure liquid refrigerant to the inlet end of said expansion valve, said refrigerant expanding as it flows through said expansion valve;
- (e) said valve including an associated flow control means responsive to the instantaneous superheat of said refrigerant in said associated evaporator means for generating a solenoid control signal, said solenoid control signal obtaining an average flow rate of refrigerant through the valve which results in a desired superheat for the refrigerant in said evaporator means, said valve further including a flush cycle timer means for generating a flush cycle having a time interval during which said associated expansion valve is controlled to permit full flow therethrough to fill said associated evaporator means with liquid refrigerant;
- and
- (f) a controller means for periodically initiating flush cycles for said expansion valve whereby said evaporator means is flushed of compressor lubricant oils which may have accumulated therein.
4 more elements
A refrigeration system employing a vaporizable and liquifiable refrigerant comprising:
- (a) a compressor having an inlet and an outlet;
- (b) a condensor capable of liquifying the vaporized refrigerant and having an inlet connected to the outlet of the compressor so as to receive compressed, vaporized refrigerant and further having an outlet to discharge the refrigerant in liquid form;
- (c) an evaporator, including an expansion coil having an inlet, an outlet and an expansion valve attached to the inlet of the evaporator and to the outlet of the condensor to pass liquid refrigerant from the condensor to the evaporator;
- (d) a flow controller responsive to the instantaneous superheat of vaporized refrigerant in the evaporator to control the flow of refrigerant through the expansion valve;
- and
- (e) a cycle timer operable to fully open the expansion valve at preselected intervals for preselected periods of time thereby to flush compression lubricant oils that may have accumulated in said evaporator.
3 more elements
Dependencies are inferred from the claim text.