Adaptive refrigerant control algorithm
AssigneeHoneywell Inc.
InventorsThomas J. Beckey, Lorne W. Nelson
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Abstract
A refrigeration system comprises a compressor, a condenser, an evaporator, an accumulator, and an adjustable controllable expansion valve. An electronic control system monitors the value of superheat and accordingly provides an electrical control signal to adjust the controllable expansion valve in order to maintain a set point superheat value. An unfiltered path is provided to ensure expedient response when the system starts operation and when dynamic changes occur. A filtered path is provided to reduce hunting, or oscillations about the set point, of the superheat value during steady state operation.
Claims20
A control apparatus for a refrigeration system, the refrigeration system having an evaporator, a compressor, a condenser, and an adjustable controlled expansion valve connected in series, and having superheat sensing means for providing a sensed superheat signal, said control apparatus comprising:
- control means adapted to be connected to the superheat sensing means, said control means responsive to the characteristics of the sensed superheat signal and having an output;
- and
- signal conditioning means adapted to be connected to the superheat sensing means for responding to the sensed superheat signal and connected to control the expansion valve, said signal conditioning means connected to said output of said control means for modifying effect of the sensed superheat signal on the control of the expansion valve, said control means comprising a transfer function control for modifying the transfer characteristics of said signal conditioning means.
A control apparatus for a refrigeration system, the refrigeration system having an evaporator, a compressor, a condenser, and an adjustable controlled expansion valve connected in series, and having superheat sensing means for providing a sensed superheat signal, said control apparatus comprising:
- control means adapted to be connected to the superheat sensing means, said control means responsive to the characteristics of the sensed superheat signal and having an output;
- and
- signal conditioning means adapted to be connected to the superheat sensing means for responding to the sensed superheat signal and connected to control the expansion valve, said signal conditioning means connected to said output of said control means for modifying effect of the sensed superheat signal on the control of the expansion valve, said signal conditioning means comprising a filtered means connected to said sensed superheat signal for providing a filtered output signal, and an unfiltered means connected to said sensed superheat signal for providing an unfiltered output signal.
A control for a refrigeration system having an evaporator and an adjustable controllable expansion valve comprising:
- means for sensing a value of superheat to provide a first output signal proportional to said superheat value;
- unfiltered means with an input electrically connected to said first output of said superheat sensing means for providing a second output;
- filtered means with an input electrically connected to said first output of said superheat sensing means for providing a third output;
- summation means for sensing a combination of said second output of said unfiltered path and said third output of said filtered path for providing a fourth output;
- means for providing a set point signal;
- means for sensing a difference between said fourth output of said summation means and said set point signal for providing control signal;
- means for connecting said control signal to the control of the expansion valve;
- and
- means responsive to the operation of the refrigeration system to control the authority of said unfiltered means and said filtered means.
Dependencies are inferred from the claim text.