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Monitoring air filter status in automotive HVAC system

  • US 9,120,366 B2
  • Filed: 04/27/2012
  • Issued: 09/01/2015
  • Est. Priority Date: 04/27/2012
  • Status: Active Grant
First Claim
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1. A method of monitoring for a clogged or an unclogged state of an air filter in an automotive HVAC system, wherein the HVAC system includes a blower having a blower motor providing a driven airflow, a plurality of outlet registers controllable to provide a plurality of circulation modes, and an evaporator for selectably cooling the driven airflow, wherein the air filter passes the driven airflow, the method comprising the steps of:

  • entering a baseline condition, wherein the baseline condition includes applying a moisture purge to the evaporator and selection of a predetermined circulation mode;

    controlling the blower motor to maintain a testing speed;

    quantifying an energization of the blower motor while maintaining the testing speed;

    comparing the energization to a base value derived according to the baseline condition with the air filter in an unclogged state;

    triggering a replacement action when the energization is greater than the base value; and

    wherein the method of monitoring of the air filter is performed in a plurality of baseline conditions each corresponding to a respective circulation mode, wherein a plurality of base values are stored according to respective baseline conditions, and wherein the method further comprises the step of selecting a base value for use in the comparing step according to the predetermined circulation mode present in the HVAC system.

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