Construction and function of the capacity regulators

The design of the capacity regulators hardly differs between CR and CRII. However, CRII capacity regulators offer a higher cycling rate and a larger part load range. When controlled via an adapted control algorithm, this enables fine-step (virtually stepless) capacity control. This can cover a control range of 100% .. 10% (down to 5% for tandem compressors) in fully equipped compressors, depending on operating conditions and refrigerant.

Full and part load operation for various compressors

Full load operation

Part load operation

Solenoid coil (see figure below)

de-energised

energised

Function in compressors for R744 (C02)

The internal bypass is closed, refrigerant flows in and is compressed.

The internal bypass is open, refrigerant flows from the pressure side to the suction side and is not compressed.
An internal check valve on the valve plate prevents refrigerant from flowing back from the gas cooler / condenser. The integrated control algorithm, together with the compressor module, ensures that the compressor heats up as little as possible.

Function in compressors for hydrocarbons, HFC, HFO

The channels in the valve plate and cylinder head are open, refrigerant flows in and is compressed.

The suction channel in the cylinder head is shut off by means of the control piston; refrigerant is not compressed.

Resulting output of refrigerant

--> The compressor delivers on all cylinders.

--> The delivery to the shut-off cylinder bank is interrupted.

Constructive design in compressors for R744 (C02)

Constructive design of the capacity regulators in compressors for R744 (C02)

Constructive design in compressors for hydrocarbons, HFC, HFO

Constructive design of the capacity regulators in compressors for hydrocarbons, HFC, HFO