Rotary compressor

A rotary compressor comprises a shell, a motor, a compression pump arranged in the shell, a high-pressure cavity communicating unit arranged in the shell, and a high-pressure cavity communicating unit located on one side of the shell, communicated with the space in the shell and connected with the compression pump. By starting an electromagnetic valve of the high-pressure cavity communicating unit, low-density refrigerant gas in a shell of the rotary compressor is transmitted to a bypass port through a communicating pipe located in the inner space of the shell 0-180 seconds before starting and enters a compression cavity of a cylinder body of the compression pump, the mass of operating refrigerant in single suction-compression-exhaust circulation is reduced, and the working efficiency of the compressor is improved. Meanwhile, the high-low pressure difference in the starting period is reduced, the electromagnetic valve is closed when the timing time is up, the starting torque and the maximum torque needed in t