Thermal Expansion Valve (TXV)

V-5 Thermal Expansion Valve System:

THE VARIABLE DISPLACEMENT - THERMAL EXPANSION VALVE REFRIGERANT SYSTEM
BASIC OPERATION
The Variable Displacement Thermal Expansion Valve Refrigerant system employs the constant run V-5 compressor. The V-5 is a variable displacement compressor that can match the automotive A/C demand under all conditions without cycling. The basic compressor mechanism is a variable angle wobble-plate with 5 axially oriented cylinders. The center of control of the compressor displacement is a bellows actuated control valve located in the rear head of the compressor that senses compressor suction pressure. The wobble-plate angle and compressor displacement are controlled by the crankcase-suction pressure differential.

HIGH A/C DEMAND
When the A/C capacity demand is high, the suction pressure will be above the control point; the valve will maintain a bleed from crankcase to suction; no crankcase-suction pressure differential; and the compressor will have maximum displacement.

LOW A/C DEMAND
When the A/C capacity demand is lower and the suction pressure reaches the control point, the valve will bleed discharge gas into the crankcase and close off a passage from the crankcase to the suction plenum. The angle of the wobble-plate is controlled by a force balance on the 5 pistons. A slight elevation of the crankcase-suction pressure differential creates a total force on the pistons resulting in a movement about the wobble-plate pivot pin that reduces the plate angle.