Air conditioner and heat source unit with other unit start up control

1. An air conditioner comprising:

a plurality of heat source units each having a compressor, a four-way switching valve, a heat source-side heat exchanger, a supercooler, an accumulator disposed on an intake side of the compressor, a bypass refrigerant circuit having a bypass flow control valve to adjust flow rate of refrigerant that flows through the bypass refrigerant circuit, and the plurality of heat source units including at least a first heat source unit and a second heat source unit;

a utilization unit having a utilization-side expansion mechanism and a utilization-side heat exchanger;

a liquid refrigerant communication pipe and a gas refrigerant communication pipe connecting the plurality of heat source units and the utilization unit and forming a single main refrigerant circuit; and

a controller configured to

make a determination that an amount of refrigerant in the first heat source unit is excessive while the first heat source unit is in an operating state,

perform an excessive refrigerant control in response to the determination that the amount of refrigerant in the first heat source unit is excessive, the excessive refrigerant control including an other-unit startup control to start up the second heat source unit in a stopped state and set the second heat source unit in an operating state such that air is conditioned by the second heat source unit,

perform a refrigerant accumulation control by the bypass refrigerant circuit directing refrigerant from between the heat source-side heat exchanger and the liquid refrigerant communication pipe to between the four-way switching valve and the accumulator without passing through the accumulator, and

first perform the refrigerant accumulation control in the first heat source unit in response to prescribed refrigerant accumulation conditions having been firmed in the first heat source unit, and then perform the other-unit startup control in the second heat source unit in response to the determination that the amount of refrigerant in the first heat source unit is excessive during refrigerant accumulation control thereof.

2. The air conditioner as recited in claim 1 , wherein

the supercoolers cool a refrigerant sent from the heat source-side heat exchangers to the utilization unit via the liquid refrigerant communication pipe, using the refrigerant that flows from the bypass flow control valve to the accumulator.

3. The air conditioner as recited in claim 2 , wherein

the controller makes the determination that the amount of refrigerant is excessive in the first heat source unit in response a degree of superheat of gas refrigerant on a discharge side of the compressor having fallen below a prescribed value.

4. The air conditioner as recited in claim 3 , wherein

the controller sets a refrigerant accumulation-processed flag in the first heat source unit for which refrigerant accumulation control has been performed, and in response to the determination that the amount of refrigerant in the first heat source unit is excessive, performs the other-unit startup control in the second heat source unit in which the refrigerant accumulation-processed flag has not been set.

5. The air conditioner as recited in claim 2 , wherein

the controller makes the determination that the amount of refrigerant is excessive in the first heat source unit in response to the bypass flow control valve being completely open or in response to a degree of superheat of gas refrigerant on a discharge side of the compressor having fallen below a prescribed value.

6. The air conditioner as recited in claim 1 , wherein

the prescribed refrigerant accumulation conditions during cooling operation include at least one of

a first condition in which a degree of refrigerant supercooling at an outlet of the heat source-side heat exchanger is higher than a prescribed value, and

a second condition in which a pressure of high-pressure refrigerant on a discharge side of the compressor is higher than a prescribed value.

7. The air conditioner as recited in claim 1 , wherein

each heat source unit further has a heat source-side expansion mechanism that includes an expansion valve disposed between the heat source-side heat exchanger and the liquid refrigerant communication pipe, and

the prescribed refrigerant accumulation conditions during heating operation include at least a third condition in which the expansion valve of the heat source-side expansion mechanism is completely open.

8. The air conditioner as recited in claim 1 , wherein

the controller makes the determination that the amount of refrigerant is excessive in the first heat source unit in response to a degree of superheat of gas refrigerant on a discharge side of the compressor having fallen below a prescribed value.

9. The air conditioner as recited in claim 1 , wherein

the controller sets a refrigerant accumulation-processed flag in the first heat source unit for which refrigerant accumulation control has been performed, and in response to the determination that the amount of refrigerant in the first heat source unit is excessive, performs the other-unit startup control in the second heat source unit in which the refrigerant accumulation-processed flag has not been set.

10. The air conditioner as recited in claim 1 , wherein

the excessive refrigerant control further includes stopping the first heat source unit.

11. The air conditioner as recited in claim 10 , wherein

the first heat source unit is returned to normal control when a prescribed amount of time has elapsed or another condition is satisfied after the excessive refrigerant control is performed.

12. A first heat source unit of an air conditioner in which a second heat source unit and a utilization unit are connected to form a single main refrigerant circuit, and in which heat exchange is performed between air in a target air-conditioning space and a utilization-side heat exchanger of the utilization unit, the first heat source unit comprising:

a compressor;

a four-way switching valve;

a heat source-side heat exchanger;

a supercooler;

an accumulator disposed on an intake side of the compressor;

a bypass refrigerant circuit having a bypass flow control valve to adjust flow rate of refrigerant that flows through the bypass refrigerant circuit; and

a controller being configured to

make a determination that an amount of refrigerant in the first heat source unit is excessive while the first heat source unit is in an operating state,

perform an excessive refrigerant control in response to the determination that the amount of refrigerant in the first heat source unit is excessive, the excessive refrigerant control including an other-unit startup control to start up the second heat source unit in a stopped state and set the second heat source unit in an operating state such that air is conditioned by the second heat source unit,

perform a refrigerant accumulation control by the bypass refrigerant circuit directing refrigerant from between the heat source-side heat exchanger and a liquid refrigerant communication pipe to between the four-way switching valve and the accumulator without passing through the accumulator, and

first perform the refrigerant accumulation control in the first heat source unit in response to prescribed refrigerant accumulation conditions having been formed in the first heat source unit, and then perform the other-unit startup control in the second heat source unit in response to the determination that the amount of refrigerant in the first heat source unit is excessive during refrigerant accumulation control thereof.

13. The first heat source unit as recited in claim 12 , wherein

the excessive refrigerant control further includes stopping the first heat source unit.

14. The first heat source unit as recited in claim 13 , wherein

the first heat source unit is returned to normal control when a prescribed amount of time has elapsed or another condition is satisfied after the excessive refrigerant control is performed.