Waste heat recovery apparatus

A waste heat recovery apparatus comprising:

• a Rankine cycle which includes a pump for pressure-feeding a liquid phase operation fluid, a heater for transforming the liquid phase operation fluid fed from the pump into a gaseous phase operation fluid by heating with waste heat from a heat-generating device, an expansion unit for converting energy of expansion of the gaseous phase operation fluid flowing out from the heater into mechanical energy, and a condenser for condensing and liquefying the expanded gaseous phase operation fluid flowing out from the expansion unit and introducing the liquefied operation fluid into the pump;
• a rotary electric machine which has both functions of an electric motor and a generator, and is connected to the pump and the expansion unit through the same shaft;
• a control unit which controls the operation of the rotary electric machine;
• a bypass passage which bypasses the expansion unit;
• an opening/closing part which is controlled by the control unit to open and close the bypass passage;
• a temperature detector which detects the temperature of the gaseous phase operation fluid on an inlet side of the expansion unit;
• and
• pressure differential detecting means for detecting a pressure differential between an inlet and an outlet of the expansion unit;
• wherein, at the start of the Rankine cycle, the control unit controls the opening/closing part to open the bypass passage and controls the rotary electric machine to operate as the electric motor at a predetermined rotational speed, and if the temperature of the gaseous phase operation fluid detected by the temperature detector becomes equal to or higher than a predetermined temperature, the control unit controls the opening/closing part to close the bypass passage, and controls the rotary electric machine such that an operation rotational speed of the rotary electric machine increases relative to the predetermined rotational speed until a pressure differential detected by the pressure differential detector means reaches a predetermined pressure differential.