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Vehicle passenger compartment temperature control system with P.I.D. control of heater servo-valve

  • US 5,127,576 A
  • Filed: 12/26/1991
  • Issued: 07/07/1992
  • Est. Priority Date: 12/26/1991
  • Status: Expired due to Fees
First Claim
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1. A control system for vehicle passenger compartment climate control the type having a passenger compartment heat exchanger and an engine driven pump circulating heated fluid through said heat exchanger comprising:

  • (a) motorized valve means including a movable valve member operable for controlling flow of said heated fluid to said heat exchanger upon receipt of an output control signal;

    (b) feedback means operable to provide an electrical indication of the position of said movable valve member;

    (c) blower means operable to provide a flow of air over said heat exchanger, including a plenum means for directing said flow to the passenger compartment;

    (d) tachometer means operative to provide an electrical indication of engine speed;

    (e) speed change indicating means operative to provide an indication of the rate of change of engine speed;

    (f) temperature sensing means operative to provide an electrical indication of the temperature of the air in said plenum means;

    (g) user control means operative upon selective movement by the user to provide an electrical temperature signal indicative of a selected relative temperature level and a selected blower speed;

    (h) means operative to provide an output control signal according to the relationship
    
    
    space="preserve" listing-type="equation">CS=P+I+D+T+C where ##EQU2## and Kp is a gain constant in the range 11-22;

    ##EQU3## where KI is an integer in the range 9-20 and is calculated only for the case P=0;

    D=dTERROR xKD, where dTERROR

    T.sub.(t) -Δ

    T.sub.(t-1) andKD is a gain constant integer in the range 1-7;

    T=Δ

    RPM×

    KT, where Δ

    RPM=RPMt-1 -RPMt and KT is an RPM gain constant in the range 1-7, and C is an idle speed compensation factor C=+Kc when engine speed falls below a first threshold value and C=-Kc which represents 15°

    of valve movement when engine speed rises to above a second threshold higher than said first threshold, where a separate determination of the control signal is made for each user-selected blower speed.

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