Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
2005-02-15
2005-02-15
Norman, Marc (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C062S212000, C062S223000, C236S09200D
Reexamination Certificate
active
06854285
ABSTRACT:
A controller for an expansion valve of a refrigeration system for cooling a medium is configured to include, in the generation of a control signal, a measure of the evaporation temperature (T0) of the refrigerant in an evaporator and a measure of a property of the cooled medium, preferably without influence from a measure of the superheat temperature (SH) of the refrigerant. The controller comprises a PI-element for integrating and for producing a control signal for the expansion valve for controlling the flow of refrigerant into the evaporator, the PI-element being arranged in an inner control loop, a reference for which is produced by an outer control loop. The controller allows for fast response to disturbances and/or fast response of the medium temperature when the operating conditions of the refrigeration system are changed and/or fast response during start-up of the refrigeration system and maintains stable operation conditions with low, but positive superheating and a stable evaporation pressure.
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Danfoss A/S
McCormick Paulding & Huber LLP
Norman Marc
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