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Frost detection system for refrigeration apparatus

  • US 4,831,833 A
  • Filed: 07/13/1987
  • Issued: 05/23/1989
  • Est. Priority Date: 07/13/1987
  • Status: Expired due to Fees
First Claim
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1. A system for detecting frost buildup on an evaporator of a refrigeration system having intermittent forced air flow across the evaporator, and for avoiding unnecessary defrost cycles due to transient fluctuations in air flow, comprising:

  • air movement means for moving air across said evaporator, said air movement means operative intermittently;

    air velocity sensing means for sensing air velocity adjacent the evaporator;

    signal generating means in connection with said sensing means for generating at least one signal corresponding to the air velocity sensed by said sensing means;

    processor means in connection with said signal generating means, and said air movement means;

    memory means in connection with said processor means, said memory means adapted for storing a defrost initiation value;

    said processor means programmed to receive said air velocity signal, to calculate said defrost initiation value as a function of said air velocity signal a predetermined time after said air movement means commences operation and when said evaporator is in a defrosted condition, and to transmit said defrost initiation value to said memory means for storage therein, said processor means further programmed to thereafter compare said velocity signal and said initiation value and generate a defrost cycle initiation signal when said velocity signal and said initiation value have a predetermined relationship.

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