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Microprocessor based control system and method providing better performance and better operation of a shipping container refrigeration system

  • US 4,663,725 A
  • Filed: 02/15/1985
  • Issued: 05/05/1987
  • Est. Priority Date: 02/15/1985
  • Status: Expired due to Fees
First Claim
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1. A control system for operating a transport refrigeration system having a motor driven compressor coupled to a condenser and an evaporator and further having heater means so as to cool or heat a served space, said system comprising:

  • first and second temperature sensing means for respectively sensing first and second temperatures in first and second different locations of the served space;

    a microprocessor for monitoring and controlling said transport refrigeration system;

    means for coupling said first and second temperature sensing means to said microprocessor;

    means for manually selecting one of said first and second temperature sensing means as an operative temperature sensor;

    means for generating and coupling to said microprocessor an operator selected space temperature set point;

    means for comparing said operator selected set point with the temperature sensed by the operative sensor to provide a difference error;

    operating controls for the compressor motor and the heater means to provide cooling and heating needed for space temperature control;

    means for coupling said operating controls to said microprocessor;

    first and second algorithms which define in accordance with first and second sets of rules, respectively, operating states of said operating controls;

    means for automatically selecting one of said algorithms as the operative algorithm in response to the operative sensor;

    means for operating said microprocessor to sequence or control said operating controls in accordance with said selected algorithm to produce a level of heat transfer to or from the served space on the basis of the level of said difference error;

    means for operating said microprocessor to detect a failure of said operative sensor; and

    means for automatically switching sensors to cause the non-selected sensor to be the operative sensor in determining said difference error and for automatically designating one of said algorithms for continued system sequencing the control in the event said manually selected temperature sensing means is detected to have failed.

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