Vehicular heat cycle apparatus and method of ascertaining refrigerant charge state using the same

A vehicular heat cycle apparatus comprising:

• a refrigerant cycle inside which a refrigerant circulates and which comprises:
• a compressor configured to send out the refrigerant,
• a refrigerant and heat-medium heat exchanger into which the refrigerant that has been sent out of the compressor flows,
• an expansion valve through which the refrigerant that has flowed out of the refrigerant and heat-medium heat exchanger is passable,
• a heat-absorption heat exchanger into which the refrigerant that has passed through the expansion valve flows,
• a bypass passage coupling a passage between an outlet portion of the refrigerant and heat-medium heat exchanger and an inlet portion of the expansion valve to a passage between an outlet portion of the heat-absorption heat exchanger and an intake portion of the compressor,
• a bypass-side expansion valve through which the refrigerant that has flowed out of the refrigerant and heat-medium heat exchanger is passable, the bypass-side expansion valve are disposed on the bypass passage. and
• a bypass-side heat-absorption heat exchanger into which the refrigerant that has passed through the bypass-side expansion valve flows, so that the refrigerant is configured to collect heat of a heating element, the bypass-side heat-absorption heat exchanger are disposed on the bypass passage;
• a heat medium cycle inside which a heat medium circulates and which comprises:
• a pump configured to send out the heat medium,
• a heat medium heating device into which the heat medium that has been sent out of the pump flows, the heat medium heating device configured to heat the heat medium, and
• a heat-dissipation heat exchanger into which the heat medium that has flowed out of the heat medium heating device flows, the heat-dissipation heat exchanger configured to dissipate heat from the heat medium, the heat medium cycle being thermally coupled to the refrigerant cycle at the refrigerant and heat-medium heat exchanger;
• a refrigerant temperature detector configured to detect a temperature of the refrigerant in the refrigerant cycle;
• a refrigerant pressure detector configured to detect a pressure of the refrigerant in the refrigerant cycle;
• an outside air temperature detector configured to detect a temperature of outside air;
• and
• a controller configured to control operations of the refrigerant cycle and the heat medium cycle and configured to determine a charge state of the refrigerant in the refrigerant cycle using a refrigerant temperature that has been detected by the refrigerant temperature detector, a refrigerant pressure that has been detected by the refrigerant pressure detector, and an outside air temperature that has been detected by the outside air temperature detector,
• wherein the heat-absorption heat exchanger and the heat-dissipation heat exchanger are disposed in an air blowing space in an air conditioner comprising a blower,
• wherein when it is determined that the outside air temperature is lower than a predetermined outside air temperature the controller is configured to switch to a determination operation mode in which the expansion valve is made closed, the bypass-side expansion valve is made fully open, and the compressor, the pump, and the heat medium heating device are operated, and
• wherein after switching to the determination operation mode, when the refrigerant temperature exceeds a first predetermined refrigerant temperature the controller is configured to make a determination whether a state of the refrigerant grasped from the refrigerant temperature and the refrigerant pressure is in a refrigerant insufficiency region set on a lower pressure side than a saturated vapor pressure curve of the refrigerant by a predetermined pressure difference.

A method of ascertaining a refrigerant charge state using a vehicular heat cycle apparatus comprising:

• a refrigerant cycle inside which a refrigerant circulates and which comprises:
• a compressor configured to send out the refrigerant,
• a refrigerant and heat-medium heat exchanger into which the refrigerant that has been sent out of the compressor flows,
• an expansion valve through which the refrigerant that has flowed out of the refrigerant and heat-medium heat exchanger is passable, and
• a heat-absorption heat exchanger into which the refrigerant that has passed through the expansion valve flows;
• a heat medium cycle inside which a heat medium circulates and which comprises:
• a pump configured to send out the heat medium,
• a heat medium heating device into which the heat medium that has been sent out of the pump flows, the heat medium heating device configured to heat the heat medium, and
• a heat-dissipation heat exchanger into which the heat medium that has flowed out of the heat medium heating device flows, the heat-dissipation heat exchanger configured to dissipate heat from the heat medium, the heat medium cycle being thermally coupled to the refrigerant cycle at the refrigerant and heat-medium heat exchanger;
• a refrigerant temperature detector configured to detect a temperature of the refrigerant in the refrigerant cycle;
• a refrigerant pressure detector configured to detect a pressure of the refrigerant in the refrigerant cycle;
• an outside air temperature detector configured to detect a temperature of outside air;
• and
• a controller configured to control operations of the refrigerant cycle and the heat medium cycle and configured to determine a charge state of the refrigerant in the refrigerant cycle using a refrigerant temperature that has been detected by the refrigerant temperature detector, a refrigerant pressure that has been detected by the refrigerant pressure detector, and an outside air temperature that has been detected by the outside air temperature detector,
• wherein the heat-absorption heat exchanger and the heat-dissipation heat exchanger are disposed in an air blowing space in an air conditioner comprising a blower,
• the method of ascertaining a refrigerant charge state comprising:
• operation mode switching steps of, when it is determined that the outside air temperature is lower than a predetermined outside air temperature switching to a determination operation mode in which the expansion valve is made fully open, and the compressor, the pump, and the heat medium heating device are operated, and
• refrigerant charge state determination steps of, after switching to the determination operation mode, when the refrigerant temperature exceeds a first predetermined refrigerant temperature determining a divergence degree of an actual pressure of the refrigerant with respect to a saturation pressure of the refrigerant at the temperature, so as to make a determination from the divergence degree as to whether the refrigerant in the refrigerant cycle is insufficient.

A method of ascertaining a refrigerant charge state using a vehicular heat cycle apparatus comprising:

• a refrigerant cycle inside which a refrigerant circulates and which comprises:
• a compressor configured to send out the refrigerant,
• a refrigerant and heat-medium heat exchanger into which the refrigerant that has been sent out of the compressor flows,
• an expansion valve through which the refrigerant that has flowed out of the refrigerant and heat-medium heat exchanger is passable,
• a heat-absorption heat exchanger into which the refrigerant that has passed through the expansion valve flows,
• a bypass passage coupling a passage between an outlet portion of the refrigerant and heat-medium heat exchanger and an inlet portion of the expansion valve to a passage between an outlet portion of the heat-absorption heat exchanger and an intake portion of the compressor,
• a bypass-side expansion valve through which the refrigerant that has flowed out of the refrigerant and heat-medium heat exchanger is passable, the bypass-side expansion valve are disposed on the bypass passage, and
• a bypass-side heat-absorption heat exchanger into which the refrigerant that has passed through the bypass-side expansion valve flows, so that the refrigerant is configured to collect heat of a heating element, the bypass-side heat-absorption heat exchanger are disposed on the bypass passage;
• a heat medium cycle inside which a heat medium circulates and which comprises:
• a pump configured to send out the heat medium,
• a heat medium heating device into which the heat medium that has been sent out of the pump flows, the heat medium heating device configured to heat the heat medium, and
• a heat-dissipation heat exchanger into which the heat medium that has flowed out of the heat medium heating device flows, the heat-dissipation heat exchanger configured to dissipate heat from the heat medium, the heat medium cycle being thermally coupled to the refrigerant cycle at the refrigerant and heat-medium heat exchanger;
• a refrigerant temperature detector configured to detect a temperature of the refrigerant in the refrigerant cycle;
• a refrigerant pressure detector configured to detect a pressure of the refrigerant in the refrigerant cycle;
• an outside air temperature detector configured to detect a temperature of outside air;
• and
• a controller configured to control operations of the refrigerant cycle and the heat medium cycle and configured to determine a charge state of the refrigerant in the refrigerant cycle using a refrigerant temperature that has been detected by the refrigerant temperature detector, a refrigerant pressure that has been detected by the refrigerant pressure detector, and an outside air temperature that has been detected by the outside air temperature detector,
• wherein the heat-absorption heat exchanger and the heat-dissipation heat exchanger are disposed in an air blowing space of an air conditioner comprising a blower,
• the method of ascertaining a refrigerant charge state comprising:
• operation mode switching steps of, when it is determined that the outside air temperature is lower than a predetermined outside air temperature switching to a determination operation mode in which the expansion valve is made closed, the bypass-side expansion valve is made fully open, and the compressor, the pump, and the heat medium heating device are operated, and
• refrigerant charge state determination steps of, after switching to the determination operation mode, when the refrigerant temperature exceeds a first predetermined refrigerant temperature determining a divergence degree of an actual pressure of the refrigerant with respect to a saturation pressure of the refrigerant at the temperature, so as to make a determination from the divergence degree as to whether the refrigerant in the refrigerant cycle is insufficient.