GF83.55-P-2102-02P

Refrigerant compressor control valve, function

P83.55-0222-79

1 Bypass 2 Control plunger A Function diagram of refrigerant compressor control valve with variable volume control in partial-load range

Pc Crankcase pressure Pd High pressure Ps Suction pressure Ps1 Membrane pressure

Variable volume control in partial load range (e.g. at low ambient temperature or low cooling capacity requirement) Essentially, the cooling output is dependent on the intake pressure, i.e. if the suction pressure (Ps) drops below the diaphragm pressure (Ps1) in the refrigerant compressor control valve and the regulating current is reduced at the same time, then the passage from high pressure (Pd) to crankcase pressure (Pc) is released by the control plunger (2) in the refrigerant compressor control valve. As a result, refrigerant flows from the high pressure side into the crankcase which results in an increase in crankcase pressure (Pc).

The sum of the forces on the left-hand side, resulting from the crankcase pressure (Pc), the return force (centrifugal force) of the swash plate and the spring return force thus becomes greater than total piston forces. The swash plate moves into a vertical position, which causes a reduction in piston travel and replacement volume. In addition, a regulation of the cooling output takes place as a function of the air humidity, i.e. at high air humidity there is an external actuation of the control valve, achieving a post-regulation of the cooling output (preventing fogging up of the windows). The refrigerant compressor is automatically switched off at a volumetric flow of less than 5 cm3.

P83.55-0223-79

1 Bypass 2 Control plunger B Function diagram of refrigerant compressor control valve at max. swept volume

Pc Crankcase pressure Pd High pressure Ps Suction pressure Ps1 Membrane pressure

Control at max. swept volume (e.g. at higher ambient temperature or higher cooling capacity requirement) If the suction pressure (Ps) rises above the diaphragm pressure (Ps1) in the refrigerant compressor control valve and the control current is increased at the same time, in the refrigerant compressor control valve the passage - high pressure (Pd) to crankcase pressure (Pc) - is closed by the control plunger (2). The crankcase pressure (Pc) drops, as no refrigerant flows from the high pressure side into the crankcase via the refrigerant compressor control valve.

In the long-term the bypass (1) sets up a pressure compensation between the suction pressure (Ps) and crankcase pressure (Pc), i.e. the sum of the reaction forces on the left side, resulting from the crankcase pressure (Pc), return force of the swash plate (centrifugal force) and the spring return force, is therefore smaller than the sum of the piston forces. The swash plate angle extends to beyond the "0-position ", i.e. the inclined position increases continuously to the swash plate's mechanical limit stop at the stop plate. The piston stroke increases linear to the swash plate's inclination till it reaches max. volumetric flow.