Abstract: The bellows in the stroke control valve of a variable stroke axial piston wobble plate refrigerant compressor is partially filled with an anti-freeze solution and continuously exposed to both suction pressure and crankcase pressure. This has the effect of reducing the piston stroke at high compressor speeds while increasing suction pressure to maintain some air conditioning performance.

Abstract: A control method for a variable capacity automotive air conditioning compressor in which the compressor operating point is tailored to the nonlinear control characteristics of variable displacement compressors. When the error between the desired and actual values of a specified system parameter is relatively large, the operating point is determined by a coarse gain closed-loop control. When the error is within a fine control range defined in relation to the desired value, the control point is set to one of three predetermined values for effecting small displacement increases, small displacement decreases, or no change in displacement. An adaptive tuning technique is used to update the predetermined control point values to compensate for compressor-to-compressor differences and changes in the operating conditions of a given compressor system. An anticipation technique shortens the transition from coarse control to fine control by minimizing gross overshoots of the specified system parameter.

Abstract: A control method for a variable capacity automotive engine driven air conditioning compressor in which the onset of an overspeed condition is anticipated in relation to the compressor speed and acceleration for the purpose of initiating an override of the normal control setting to quickly destroke the compressor so long as the overspeed condition is indicated. In normal operation, the control setting for the air conditioning system is chosen in relation to the current compressor speed. The compressor capacity is electrically controlled in relation to the error between the control setting and an actual or measured setting. Concurrently, a secondary control setting is determined based on an estimate of a future compressor speed, given the current rate of change in compressor speed. When the secondary control setting would produce more destroke than the primary control setting, the secondary control overrides the primary control to protect the compressor should the current conditions continue.

Abstract: A passive destroker mechanism operated by centrifugal force is added to a variable stroke axial piston wobble plate refrigerant compressor. The destroker operates at a predetermined compressor speed to communicate the discharge side of the compressor with its sealed crankcase to thereby provide a controlled discharge gas bleed thereto to destroke the compressor to a desired displacement. Then after the speed is reduced below such trigger speed, the destroker mechanism operates to return the compressor to its normal stroke control condition.