Externally Controlled Variable Displacement Compressor - Denso

The variable displacement compressor has a swash plate that rotates to reciprocate pistons, which compresses refrigerant. The variable displacement compressor change the swash plate angle to change the refrigerant displacement.
The externally controlled type variable displacement compressor changes the swash plate angle in accordance with an electrical signal from an electric control unit.
DENSO’s externally controlled variable displacement compressor manages displacement by controlling refrigerant differential pressure before and after a throttle at the discharge side; achieving precise cooling capability control in accordance with cabin environment and driving conditions. 


DENSO Technology – Leading the World
  • DENSO developed the world’s first technology that controls refrigerant displacement from almost zero percent to 100 percent. Using this technology, in 1997, DENSO launched the world’s first externally controlled variable displacement compressor with a damper limiter (DL) pulley, instead of a magnetic clutch, making the compressor smaller, lighter and more reliable.
  • In 2001, DENSO launched the world’s first externally controlled variable displacement compressor with an electromagnetic control valve that controls refrigerant differential pressure before and after a throttle at the discharge side, in accordance with an electric signal from the engine ECU or air conditioner ECU. By controlling refrigerant discharge pressure rather than refrigerant suction pressure, the engine torque used for the compressor can be estimated. This allows the compressor to be controlled in connection with engine management to reduce fuel consumption.
  • In 2001, DENSO launched an even lighter variable displacement compressor with a resin-made DL pulley.
  • In 2003, DENSO launched the world’s first externally controlled variable displacement compressor with a rotary valve as a suction valve, instead of a conventional lead valve plate. This improved compressor efficiency by approximately 10 percent.
Benefits and Features
  • Small size and light weight
    • The externally controlled variable displacement compressor (5SER09) with resin-made DL pulley achieves the world’s lightest weight for equivalent displacement compressors.
      DENSO improved the housing to have a thinner wall while maintaining its strength, contributing to a smaller and lighter compressor.
  • High compressor efficiency
    • The world’s first rotary valve reduces pressure drop of refrigerant gas drawn into compression chambers, and prevents heating of the refrigerant gas. This enables the compressor to draw a larger amount of refrigerant into the compressing chambers, increasing compressor efficiency by approximately 10 percent when compared to a conventional compressor.
  • Precisely controllable in connection with engine management
    • Using DENSO-developed electromagnetic control valve, refrigerant displacement is controlled in accordance with the amplitude of engine torque used for the compressor. This maximizes engine efficiency.
  • Low noise and vibration
    • The rotary valve and the housing’s muffler structure significantly reduce the pulsation of refrigerant gas pulled into the compression chambers.
  • High reliability
    • The pistons are hollow, enabling the compressor to control refrigerant displacement at a maximum of 11,000 revolutions per minute, at high engine speed. This prevents the pistons from disturbing the swash plate inclination control even at the high engine speed.
DENSO’s Latest Model (5SER09) Structure