Refrigeration pull-down technique
AssigneesThermo King Corporation, Honeywell Inc.
InventorsGreg Truckenbrod, Paul C. Wacker
Life of this patent
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Abstract
Apparatus for and method of rapidly bringing a controlled space to a desired temperature. The technique is particularly applicable to the maintenance of controlled temperature spaces for the transportation of perishable cargo, such as in refrigeration trucks. Immediately following completion of the loading process, it is desirable to bring the internal temperature of the controlled space to the proper operating point as quickly as possible to retard spoilage. However, it is necessary to avoid unacceptable overshoot to prevent damage to the cargo by freezing. The disclosed system employs multiple sensors and a control algorithm to permit pull down to occur as rapidly as possible without unacceptable overshoot.
Claims15
A refrigeration system control apparatus comprising:
- a. means for initiating a pull down mode of operation;
- b. a plurality of sensors for monitority a plurality of parameters during said pull down mode wherein said plurality of sensors includes a discharge air temperature sensor;
- c. means for comparing each of said plurality of parameters to a different predetermined standard to produce a plurality of comparisons including second means for determining whether discharge air temperature is less than a predetermined set point minus ten degrees and including second means coupled to said second determining means for deactivating said pull down mode whenever said second determining means indicates that said discharge air temperature is less than a predetermined set point minus ten degrees;
- and
- means responsively coupled to said comparing means for terminating said pull down mode in response to a one of said plurality of comparisons.
A method of terminating a pull down mode of a heat exchange system of a temperature controlled space comprising:
- a. monitoring a first parameter of said temperature controlled space;
- b. terminating said pull down mode if aid first parameter coincides with a first predefined condition;
- c. monitoring a second parameter of said temperature controlled space;
- d. terminating said pull down mode if said second parameter coincides with a second predefined condition;
- e. computing a third parameter of said temperature controlled space;
- and
- f. terminating said pull down mode if said third parameter coincides with a third predefined condition.
An apparatus for refrigerating a space comprising:
- a. means for initating a pull down mode of operation;
- b. a return air temperature sensor;
- c. a discharge air temperature sensor;
- d. means responsively coupled to said initiating means and said return air temperature sensor for terminating said pull down mode of operation whenever said return air temperature is less than a setpoint plus a first predetermined number;
- and
- e. means responsively coupled to said initiating means and said discharge air temperature sensor for terminating said pull down mode of operation whenever said discharge air temperature is less than said setpoint minus a second predetermined number.
Dependencies are inferred from the claim text.