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V7 Compressor







VDOT A/C Compressor / System Description
The V7 compressor is a variable displacement compressor that can match the automotive air conditioning demand under all conditions without cycling. The basic compressor mechanism is a variable angle wobble-plate with seven axially oriented cylinders. A bellows actuated control valve located in the rear head of the compressor senses the compressor suction pressure and is the center of control for the compressor displacement. The crankcase-suction differential controls both the wobble-plate and the compressor displacement. When the A/C capacity demand is high, the suction pressure will be above the control point. The control valve will maintain a bleed from crankcase to suction which causes no crankcase-suction pressure differential giving the compressor maximum displacement. When the A/C capacity demand is lower and the suction pressure reaches the control point, the valve will bleed discharge gas into thee crankcase and close of a passage from the crankcase to the suction plenum. The wobble-plate angle is controlled by a force balance on the seven pistons. A slight increase in the crankcase-suction pressure differential creates a force on the pistons, resulting is a movement about the wobble-plate pivot pin that reduces the plate angle.

The compressor has a unique lubrication system. The crankcase-suction bleed is routed through the rotating wobble-plate for lubrication of he wobble-plate bearing. The rotation acts a an oil separator, removing some of the oil from the crankcase-suction bleed, and rerouting the oil to the crankcase where the oil can lubricate the compressor mechanism.

The compressor is belt driven from the engine crankshaft through the compressor clutch pulley. The pulley rotates without driving the compressor shaft until an electromagnetic clutch coil is energized. When voltage is applied to energize the coil, the clutch plate and hub assembly are drawn rearward toward the pulley. The magnetic force locks the clutch plate and the pulley together in order to drive the compressor shaft.