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Control method for a variable displacement air conditioning system compressor

  • US 5,022,234 A
  • Filed: 06/04/1990
  • Issued: 06/11/1991
  • Est. Priority Date: 06/04/1990
  • Status: Expired due to Fees
First Claim
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1. In an automotive air conditioning system including a refrigerant compressor having a capacity determined in accordance with the pressure in a control chamber thereof, and a control valve in communication with inlet and outlet ports of the compressor for effecting a ratiometric control of the pressure in said control chamber, control apparatus comprising:

  • means for measuring the value of a specified system parameter;

    means defining a fine control range of values in relation to a desired value of said specified system parameter and a deadband range of values within said fine control range;

    closed-loop control means effective when the measured value is outside said fine control range for operating the control valve at a setting determined at least in proportion to the difference between the measured and desired values; and

    open-loop control means effective when the measured value is within said fine control range for operating the control valve at (1) a first predetermined setting designed to change the capacity of the compressor in a direction to decrease the specified system parameter when the measured value is above said deadband range, (2) at a second predetermined setting designed to change the capacity of the compressor in a direction to increase the specified system parameter when the measured value is below said deadband range, and (3) at a third predetermined setting designed to maintain the current capacity of the compressor if the measured value is within said deadband range.

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