A refrigeration cycle device includes: a high-pressure side heat exchanger; a low-pressure side heat exchanger; a vehicle-mounted device that supplies heat to the heat medium; a heat-medium air heat exchanger that exchanges heat between the heat medium and air; a switching portion that switches between a state in which the heat medium circulates through the high-pressure side heat exchanger and a state in which the heat medium circulates through the low-pressure side heat exchanger with respect to each of the vehicle-mounted device and the heat-medium air heat exchanger; and a controller that drives the compressor, while controlling an operation of the switching portion to switch to a defrosting mode in which the heat medium circulates between the low-pressure side heat exchanger and the vehicle-mounted device, and the heat medium circulates between the high-pressure side heat exchanger and the heat-medium air heat exchanger, when defrosting of the heat-medium air heat exchanger is necessary.

A vehicle air conditioning apparatus is provided that can prevent temperature variations of the air after the heat exchange in a radiator to reliably control the temperature of the air supplied to the vehicle interior. During the heating operation and the heating and dehumidifying operation, target degree of supercooling SCt when target air-blowing temperature TAO is a predetermined temperature or higher is set to SCt1 that is greater than SCt2 when the target air-blowing temperature TAO is lower than the predetermined temperature. When amount of air Ga supplied from indoor fan 12 is lower than a predetermined value, the target degree of supercooling SCt is corrected, which is set such that the degree of supercooling is lower than target degree of supercooling corrected when the amount of air Ga supplied from the indoor fan 12 is a predetermined value or higher.

A vehicle air conditioning apparatus is provided that can prevent temperature variations of the air after the heat exchange in a radiator to reliably control the temperature of the air supplied to the vehicle interior. During the heating operation and the heating and dehumidifying operation, target degree of supercooling SCt when target air-blowing temperature TAO is a predetermined temperature or higher is set to SCt1 that is greater than SCt2 when the target air-blowing temperature TAO is lower than the predetermined temperature. When amount of air Ga supplied from indoor fan 12 is lower than a predetermined value, the target degree of supercooling SCt is corrected, which is set such that the degree of supercooling is lower than target degree of supercooling corrected when the amount of air Ga supplied from the indoor fan 12 is a predetermined value or higher.

A vehicle air conditioning apparatus is provided that can prevent temperature variations of the air after the heat exchange in a radiator to reliably control the temperature of the air supplied to the vehicle interior. During the heating operation and the heating and dehumidifying operation, target degree of supercooling SCt when target air-blowing temperature TAO is a predetermined temperature or higher is set to SCt1 that is greater than SCt2 when the target air-blowing temperature TAO is lower than the predetermined temperature. When amount of air Ga supplied from indoor fan 12 is lower than a predetermined value, the target degree of supercooling SCt is corrected, which is set such that the degree of supercooling is lower than target degree of supercooling corrected when the amount of air Ga supplied from the indoor fan 12 is a predetermined value or higher.

A vehicle air conditioning apparatus is provided that can prevent temperature variations of the air after the heat exchange in a radiator to reliably control the temperature of the air supplied to the vehicle interior. During the heating operation and the heating and dehumidifying operation, target degree of supercooling SCt when target air-blowing temperature TAO is a predetermined temperature or higher is set to SCt1 that is greater than SCt2 when the target air-blowing temperature TAO is lower than the predetermined temperature. When amount of air Ga supplied from indoor fan 12 is lower than a predetermined value, the target degree of supercooling SCt is corrected, which is set such that the degree of supercooling is lower than target degree of supercooling corrected when the amount of air Ga supplied from the indoor fan 12 is a predetermined value or higher.

In a vehicle air conditioning apparatus, during a cooling operation, and a cooling and dehumidifying operation, a refrigerant flows through an outdoor heat exchanger, flows through a supercooling radiator, and then flows into a radiator to absorb heat. During a heating operation, the refrigerant flows through a heat exchanger and then is sucked into a compressor without passing through the supercooling radiator. During a first heating and dehumidifying operation, the refrigerant flows through another radiator, flows through the supercooling radiator, and then flows into another heat exchanger to absorb heat.

Method of cooling a heat exchanger of an engine using a cooling fan system includes: measuring conditions of an engine cooling system, determining a desired fan cooling demand. Based on the fan cooling demand, a fan control circuit operates to selectively control an electrically commutated (EC) motor at a continuously variable speed for an EC cooling fan and to control a direct current (DC) motor of a DC cooling fan. The DC motor is controlled to: not operate the DC cooling fan, operate the DC motor at a first predetermined operating speed, and operate the DC motor at a second predetermined operating speed corresponding to a second DC motor speed signal that is less than the first predetermined operating speed. The conditions for determining fan cooling demand include at least one of a temperature and a pressure of an engine coolant and of a refrigerant of a vehicle air conditioning system.

There is disclosed a vehicle air conditioner which is capable of enlarging an effective range of a dehumidifying and heating mode to environmental conditions and smoothly dehumidifying and heating a vehicle interior. A vehicle air conditioner 1 executes a dehumidifying and heating mode in which a controller lets a refrigerant discharged from a compressor 2 radiate heat in a radiator 4, and decompresses the refrigerant by which heat has been radiated and then lets the refrigerant absorb heat in a heat absorber 9 and an outdoor heat exchanger 7, the controller decreases an outdoor blower voltage FANVout of an outdoor blower 15 and decreases an air volume into the outdoor blower 15 in a case where a temperature Te of the heat absorber 9 is high even when the controller adjusts a valve position of an outdoor expansion valve 6 into a lower limit of controlling in a situation in which a temperature TCI of the radiator 4 is satisfactory.

A vapor compression cooling system includes a centrifugal compressor(s) for compressing a primary fluid in a cycle including at least two compressions, and a control module for controlling the centrifugal compressor dependent upon at least a condition of a secondary fluid. The module controls a power of the centrifugal compressor by adjusting a speed of the motor driving the compressor and/or an opening of guide vanes associated with at least one impeller. The module may also control a pressure drop of a primary fluid moving through at least one expansion device. The at least two compressions may be made in parallel or in series. A related method includes compressing a primary fluid in a first and a second compression cycle and adjusting a parameter of the compressor dependent upon a calculated desired power of the compressor.

In a vehicle air conditioning apparatus, during a cooling operation, and a cooling and dehumidifying operation, a refrigerant flows through an outdoor heat exchanger, flows through a supercooling radiator, and then flows into a radiator to absorb heat. During a heating operation, the refrigerant flows through a heat exchanger and then is sucked into a compressor without passing through the supercooling radiator. During a first heating and dehumidifying operation, the refrigerant flows through another radiator, flows through the supercooling radiator, and then flows into another heat exchanger to absorb heat.