Heat pump apparatus

A heat pump apparatus, comprising:

• a two-cylinder compressor including
• an electric motor, and
• two compression units to be driven by the electric motor,
• the two-cylinder compressor being structured to switch between a single operation in which one of the two compression units is brought into a non-compression state, and a parallel operation in which both of the two compression units are brought into a compression state,
• a heat-rejecting-side heat exchanger;
• an expansion valve;
• a heat-removing-side heat exchanger,
• the two-cylinder compressor, the heat-rejecting-side heat exchanger, the expansion valve, and the heat-removing-side heat exchanger being connected to each other,
• at least one of the two compression units of the two-cylinder compressor includes,
• a cylinder having a cylindrical cylinder chamber formed therein,
• a piston arranged on an eccentric shaft portion of a drive shaft of the electric motor, and configured to perform eccentric rotary motion in the cylindrical cylinder chamber, and
• a vane slidably arranged so that a distal end portion of the vane abuts on the piston, the vane partitioning the cylindrical cylinder chamber into two spaces;
• and
• a controller configured to,
• supply drive power to the electric motor of the two-cylinder compressor;
• output a conduction signal of a switch under a state in which the distal end portion of the vane of the at least one of the two compression units is separated away from the piston and the vane is stopped;
• identify that a current operation mode is the single operation when acquiring the conduction signal output from the switch, and identifies that the current operation mode is the parallel operation when acquiring no conduction signal;
• and
• control output frequency of an inverter drive control device based on a result of identifying so that a temperature of an object is brought close to a set value, and
• a closed container into which the electric motor and the two compression units are inserted,
• wherein the two-cylinder compressor passively switches an operation mode between the two operation modes when a pressure within the closed container changes in accordance with operation conditions.