In recent years, as one of countermeasures against environmental problems, attention has been paid to a hybrid vehicle, a fuel cell vehicle, an electric vehicle, and the like running with driving force of a motor. In such vehicles, electric devices such as a motor, a generator, an inverter, a converter, and a battery generate heat by transmission and reception of electric power. Therefore, these electric devices need to be cooled. Accordingly, there is a proposed technique for cooling a heat-generating body utilizing a vapor compression refrigeration cycle used as an air-conditioning apparatus for a vehicle.
For example, Japanese Patent Laying-Open No. 2006-290254 (PTD 1) discloses a cooling system of a hybrid vehicle including a compressor capable of sucking and compressing a gas coolant; a main condenser that can be cooled by ambient air for condensing a high-pressure gas coolant; an evaporator capable of evaporating a low-temperature liquid coolant and cooling an object to be cooled; and pressure reducing means, in which a heat exchanger capable of absorbing heat from a motor and second pressure reducing means are connected in parallel to the pressure reducing means and the evaporator. Japanese Patent Laying-Open No. 2007-69733 (PTD 2) discloses a system for cooling a heat-generating body utilizing a coolant for an air-conditioning device. In the system, a heat exchanger for performing heat exchange with air-conditioning air and a heat exchanger for performing heat exchange with the heat-generating body are arranged in parallel on a coolant passage extending from an expansion valve to a compressor.
Japanese Patent Laying-Open No. 2005-90862 (PTD 3) discloses a cooling system, in which heat-generating body cooling means for cooling a heat-generating body is provided on a bypass passage bypassing a decompressor, an evaporator and a compressor in a refrigeration cycle for air-conditioning. Japanese Patent Laying-Open No. 2001-309506 (PTD 4) discloses a cooling system, in which a coolant of a vehicle air-conditioning refrigeration cycle device is circulated to a cooling member of an inverter circuit portion for performing a drive control of a vehicle running motor, thereby suppressing cooling of air-conditioning air flow by an evaporator of the vehicle air-conditioning refrigeration cycle device when cooling of the air-conditioning air flow is not required.