JPH05322265A - Air conditioner - Google Patents

Abstract

PURPOSE:To improve energy saving effect and heating efficiency by a method wherein an air conditioner is provided with first and second refrigerating cycles, the defrosting operation executing means of an outdoor heat exchanger and a means effecting the defrosting operation of the other refrigerating cycle or stopping the operation of the other cycle in accordance with the discharging refrigerant temperature of a compressor and the time of continuation of the operation when one refrigerating cycle enters the defrosting operation of the same. CONSTITUTION:An air conditioner is provided with a first refrigerating cycle, in which a compressor 11, a four-way valve 12, indoor heat exchangers 32, 42, a pressure reduce and an outdoor heat exchanger 13 are connected, and a second refrigerating cycle, in which a compressor 21, indoor heat exchangers 52, 62, a pressure reducer and an outdoor heat exchanger 23 in the heat exchanging relation between the outdoor heat exchanger 13. Further, the air conditioner is provided with a controller, which effects the defrosting operation of outdoor heat exchangers 13, 23 in respective refrigerating cycles upon the heating operation of both refrigerating cycles and effects the defrosting operation of the other refirgerating cycle or stopping the operation of the other refirgerating cycle in accordance with the discharging refrigerant temperature of the compressor and the time of continuation of the operation of the other refrigerating cycle when one refrigerating cycle enters defrosting operation upon the simultaneous heating operation of respective refrigerating cycles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having a plurality of refrigeration cycles.

[0002]

2. Description of the Related Art There is an air conditioner provided with two refrigeration cycles, and the outdoor heat exchangers of these refrigeration cycles are integrated in a heat exchange relationship with each other.

In this air conditioner, when one refrigeration cycle is in the cooling operation and the other refrigeration cycle is in the heating operation, the heat released from the cooling side outdoor heat exchanger is directly heated from the heating side outdoor heat exchanger. There is an advantage that it can be effectively taken in as heat and an energy saving effect can be obtained.

By the way, in a refrigerating cycle capable of heating operation, frost gradually adheres to the surface of the outdoor heat exchanger functioning as an evaporator, and the heat exchange area of the outdoor heat exchanger decreases as it is, and the heating capacity of the outdoor heat exchanger decreases. Will lead to a decline. For this reason,
During heating operation, it is necessary to perform defrosting operation on the outdoor heat exchanger as needed.

The defrosting operation is a so-called reverse cycle defrosting in which the refrigerant flow is switched in the opposite direction to form a defrost cycle (cooling cycle) and the high temperature refrigerant discharged from the compressor is supplied to the outdoor heat exchanger. is there. In addition, there is so-called hot gas bypass defrosting in which the high-temperature refrigerant discharged from the compressor is directly supplied to the outdoor heat exchanger by bypass.

On the other hand, in the air conditioner having the two refrigeration cycles as described above, the determination of the execution of the defrosting operation in each refrigeration cycle is independent in each refrigeration cycle. Therefore, one refrigeration cycle enters defrosting operation,
The other refrigeration cycle may continue the heating operation. However, in this case, since the outdoor heat exchanger of the other refrigeration cycle functions as an evaporator, there is a problem that defrosting of one refrigeration cycle is hindered.

Therefore, when one refrigeration cycle enters the defrosting operation, the other refrigeration cycle also enters the defrosting operation at the same time. Further, there is a system in which when one of the refrigeration cycles enters the defrosting operation, the operation of the other refrigeration cycle is turned off.

[0008]

When the other refrigerating cycle also enters the defrosting operation at the same time, the outdoor heat exchanger of the other refrigerating cycle is defrosted even though the outdoor heat exchanger is not yet frosted, or the other Defrosting may be performed without sufficient defrosting ability because the temperature of the refrigerant discharged from the compressor of the side refrigeration cycle is not so high. This is useless defrosting, and the energy saving effect is impaired.

When the operation of the other refrigeration cycle is turned off, when the outdoor heat exchanger of the other side refrigeration cycle is frosted, the defrosting time of the one side refrigeration cycle may be prolonged by the amount of frost formation. is there. If the defrosting time is limited, defrosting residue will occur. Such extension of defrosting time and defrosting residue lead to deterioration of heating efficiency.

The present invention takes the above circumstances into consideration,
The purpose thereof is that defrosting of the two refrigeration cycles can be performed without hindering each other, wasteful defrosting can be prevented, and energy saving effect can be improved. An object of the present invention is to provide an air conditioner that can eliminate defrost residue and improve heating efficiency.

[0011]

The air conditioner of the present invention comprises a heat pump type first refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a pressure reducer, and an outdoor heat exchanger are connected,
A heat pump type second refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a pressure reducer, and an outdoor heat exchanger in a heat exchange relationship with the outdoor heat exchanger of the first refrigeration cycle are connected, and heating of these refrigeration cycles. Means for performing a defrosting operation on the outdoor heat exchanger in each refrigeration cycle during operation, and when one refrigeration cycle enters the defrosting operation during simultaneous heating operation of each refrigeration cycle, the other refrigeration cycle is set to the refrigeration cycle. And a means for turning off or turning off the defrosting operation according to the discharge refrigerant temperature of the compressor and the operation on duration.

[0012]

When both the first refrigeration cycle and the second refrigeration cycle perform the heating operation, when one refrigeration cycle enters the defrosting operation, the other refrigeration cycle causes the refrigerant discharged from the compressor of the refrigeration cycle. The defrosting operation or the operation is turned off depending on the temperature and the operation-on duration.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, an outdoor heat exchanger 13 is connected to a discharge port of a variable capacity compressor 11 via a four-way valve 12. A plurality of pulse motor valves (hereinafter abbreviated as PMV) 3 that act as pressure reducing means in the outdoor heat exchanger 13.
A plurality of indoor heat exchangers 32, 4 via 1, 41 respectively
2 are connected. The indoor heat exchangers 32 and 42 are respectively P
It is connected to the suction port of the compressor 11 via the MVs 33 and 43 and further via the four-way valve 12 and the accumulator 14. Thus, the heat pump type first refrigeration cycle is configured.

That is, during the cooling operation, the refrigerant flows in the direction indicated by the solid line arrow to form a cooling cycle, and the outdoor heat exchanger 13 functions as a condenser and the indoor heat exchangers 32 and 42 function as evaporators. During the heating operation, the refrigerant flows in the direction of the dashed arrow in the figure to form a heating cycle, and the indoor heat exchanger 3
2, 42 function as a condenser, and the outdoor heat exchanger 13 functions as an evaporator.

In this first refrigeration cycle, the compressor 1
The refrigerant temperature sensor 15 is attached to the pipe connected to the first discharge port. The outdoor heat exchanger 13 has a heat exchanger temperature sensor 16
Is installed.

An outdoor heat exchanger 23 is connected to the discharge port of the variable capacity compressor 21 via a four-way valve 22. A plurality of indoor heat exchangers 52, 62 are connected to the outdoor heat exchanger 23 via a plurality of pulse motor valves (hereinafter, abbreviated as PMV) 51, 61 that function as pressure reducing means, respectively. The indoor heat exchangers 52 and 62 are PMVs 53 and 6, respectively.
3 and further to the suction port of the compressor 21 via the four-way valve 22 and the accumulator 24. Thus, the heat pump type second refrigeration cycle is configured.

That is, during the cooling operation, the refrigerant flows in the direction indicated by the solid line arrow to form a cooling cycle, and the outdoor heat exchanger 23 functions as a condenser and the indoor heat exchangers 52 and 62 function as evaporators. During the heating operation, the refrigerant flows in the direction of the dashed arrow in the figure to form a heating cycle, and the indoor heat exchanger 5
2, 62 function as a condenser, and the outdoor heat exchanger 23 functions as an evaporator.

In this second refrigeration cycle, the compressor 2
The refrigerant temperature sensor 25 is attached to the pipe connected to the first discharge port. In the outdoor heat exchanger 23, the heat exchanger temperature sensor 26
Is installed.

As shown in FIG. 2, the outdoor heat exchangers 13 and 23 have a structure in which heat exchange pipes are intertwined with each other so that heat can be exchanged with each other. Outdoor fans 17 and 27 are provided near the outdoor heat exchangers 13 and 23. Indoor heat exchanger 32,
42, 52, 62 are installed in different rooms one by one. The control circuit is shown in FIG. 70 is a commercial AC power supply,
Inverter circuits 71 and 72 and a control unit 80 are connected to the power supply 70.

The inverter circuits 71 and 72 rectify the power supply voltage, convert the rectified voltage into a voltage having a frequency and level according to a command from the control unit 80, and output the voltage. At the output ends of the inverter circuits 71 and 72, drive motors for the compressors 11 and 21 (hereinafter, referred to as compressor motors) 11M and 21
M is connected. The control unit 80 includes a microcomputer and its peripheral circuits, and controls the overall air conditioner.

The control unit 80 is connected to the outdoor fan motor 17
M, 27M, four-way valves 12, 22, refrigerant temperature sensor 15,
25, heat exchanger temperature sensors 16 and 26, indoor fan motors 34, 44, 54 and 64, indoor temperature sensors 35 and 4
5, 55, 65, operating device 81, PMV 31, 41, 5
1, 61, 33, 43, 53, 63 are connected. The indoor fan motors 34, 44, 54, 64 are drive motors for indoor fans that circulate indoor air through the indoor heat exchangers 32, 42, 52, 62. Indoor temperature sensors 35, 45,
55 and 65 detect the temperature of the room in which the indoor heat exchangers 32, 42, 52, and 62 are installed, respectively. The operation unit 81 is for setting the operation mode, instructing start / stop of operation,
Used for inputting set temperature. Then, the control unit 80
The following functional means are provided. (1) A means for operating both or one of the compressors 11 and 21 in accordance with the operation of the operating device 81 and performing a cooling operation in both or one of the refrigeration cycles.

(2) The compressor 1 is operated according to the operation of the operation device 81.
1, 21 both or one of them, and four-way valve 12,
22 means for appropriately switching the heating operation in both or one of the refrigeration cycles.

(3) A means for controlling the operating frequency F ₁ (= output frequency of the inverter circuit 71) of the compressor 11 according to the air conditioning load of the room in which the indoor heat exchangers 32, 42 are installed.

(4) A means for controlling the operating frequency F ₂ of the compressor 21 (= the output frequency of the inverter circuit 72) according to the air conditioning load of the room in which the indoor heat exchangers 52 and 62 are installed.

(5) During the heating operation in the first refrigeration cycle,
The temperature detected by the heat exchanger temperature sensor 16 is regularly monitored,
When the detected temperature is 0 ° C. or lower, the four-way valve 12 is returned to form a defrost cycle (cooling cycle) until a fixed time elapses or the detected temperature becomes a value higher than 0 ° C. Means for executing the defrosting operation on the outdoor heat exchanger 13.

(6) During heating operation in the second refrigeration cycle,
The temperature detected by the heat exchanger temperature sensor 26 is regularly monitored,
When the detected temperature is 0 ° C or lower, the four-way valve 22 is returned to form a defrost cycle (cooling cycle) until a fixed time elapses or until the detected temperature becomes a value higher than 0 ° C. Means for executing a defrosting operation on the outdoor heat exchanger 23.

(7) In the simultaneous heating operation of each refrigeration cycle, when one refrigeration cycle enters the defrosting operation, the other refrigeration cycle is operated in accordance with the refrigerant discharge temperature of the compressor of the refrigeration cycle and the operation-on duration. Means for defrosting operation or operation off. Next, the operation of the above configuration will be described.

The operating unit 81 sets the cooling modes of all the rooms and the desired room temperature, and gives an instruction to start the operation.
In this case, the inverter circuits 71 and 72 operate to start the compressors 11 and 21, and the cooling operation is executed in the first refrigeration cycle and the second refrigeration cycle. When the heating mode of all rooms is set, the four-way valves 12 and 22 are switched,
The heating operation is executed in the first and second refrigeration cycles.

When the cooling mode of the room in which the indoor heat exchangers 32 and 42 are installed and the heating mode of the room in which the indoor heat exchangers 52 and 62 are installed are set, the first refrigeration cycle The cooling operation is performed in the above, and the heating operation is performed in the second refrigeration cycle. On the contrary, it is of course possible to execute the heating operation in the first refrigeration cycle and the cooling operation in the second refrigeration cycle.

During operation, the indoor heat exchangers 32, 42, 5
The temperature of the room in which 2, 62 is installed is detected by the room temperature sensors 35, 45, 55, 65, and the difference between the detected temperature and the set room temperature at the operation unit 81 is detected as the air conditioning load of each room. To be done.

The opening of each PMV is controlled according to the detected air conditioning load, and the flow rate of the refrigerant to the indoor heat exchangers 32, 42, 52, 62 is adjusted. At the same time, the operating frequencies F ₁ and F _{2 of the} compressors 11 and 21 are controlled according to the detected air conditioning load, and the optimum capacity corresponding to the air conditioning load is exhibited.

As described above, since the two refrigerating cycles can be independently operated, even if the load is small as in the single-chamber operation, the optimum capacity for the small load can be secured. For example, the operation of the compressor is on,
It is possible to avoid such a problem that the power is frequently turned off and improve the driving efficiency.

Moreover, when one of the first refrigeration cycle and the second refrigeration cycle is in the cooling operation and the other is in the heating operation, the outdoor heat exchangers 13 and 23 are in a heat exchange relationship with each other,
The condensation heat on the cooling side is effectively used as it is as the evaporation heat on the heating side. Therefore, the cooling efficiency and the heating efficiency can be improved.

On the other hand, when the heating operation is executed in the first refrigeration cycle, the outdoor heat exchanger 1 functioning as an evaporator
The temperature of No. 3 is detected by the heat exchanger temperature sensor 16, and the detected temperature is regularly monitored. The defrosting operation control will be described below with reference to FIG.

When the detected temperature is 0 ° C. or lower, the defrosting start condition is satisfied and the first refrigeration cycle is ready for defrosting. This defrosting preparation is for increasing the operating frequency F ₁ of the compressor 11 to a predetermined value and raising the temperature of the refrigerant discharged from the compressor 11 to secure a sufficient defrosting capacity.

After a lapse of a predetermined time from the start of the defrost preparation, the operating frequency F ₁ of the compressor 11 is lowered to a predetermined value for the defrost, and the defrost preparation is completed there. Subsequently, the four-way valve 12 is restored, the heating cycle is switched to the defrosting cycle (cooling cycle), and the high temperature refrigerant discharged from the compressor 11 flows into the outdoor heat exchanger 13. The heat of this refrigerant melts the frost adhering to the surface of the outdoor heat exchanger 13,
Defrosting is done.

The defrosting termination condition is satisfied when a certain time has elapsed from the start of the defrosting operation or when the temperature detected by the heat exchanger temperature sensor 16 has risen to a value higher than 0 ° C.
At this time, the operating frequency F ₁ of the compressor 11 is shifted to the reference value, the four-way valve 12 is switched there, and the defrosting is restored to heating. The defrosting operation in the second refrigeration cycle is performed in the same way.

When the heating operation is being executed in both the first refrigeration cycle and the second refrigeration cycle, it is assumed that one of the refrigeration cycles, for example, the first refrigeration cycle, enters the defrosting operation.

In this case, the temperature of the refrigerant discharged from the compressor 21 in the second refrigeration cycle, that is, the temperature detected by the refrigerant temperature sensor 25 is confirmed. At the same time, the operation-on duration of the compressor 21 is confirmed.

The condition that the defrosting capacity of the compressor 21 is sufficient to be exhibited when the temperature of the discharged refrigerant is equal to or higher than the set value (for example, 60 ° C.), and the operation-on duration of the compressor 21 is set to the set value ( If the condition in which the outdoor heat exchanger 13 is likely to be frosted is satisfied for 12 minutes or more), the defrosting operation is simultaneously performed in the second refrigeration cycle as shown by the solid line in FIG. ..

In this way, by simultaneously entering the defrosting operation in both refrigerating cycles, the defrosting heat of each refrigerating cycle is effectively used without being taken away as the evaporation heat of the other refrigerating cycle. Therefore, the defrosting time is not extended and the defrosting residue does not occur, and reliable and short-time defrosting is possible, and the heating efficiency can be improved. Further, the defrost water is smoothly discharged without being frozen.

However, when the temperature of the refrigerant discharged from the compressor 21 is equal to or lower than the set value, it is judged that the sufficient defrosting capacity cannot be exerted, and as shown by the broken line in FIG. The operation of the second refrigeration cycle is turned off only during the frost operation. That is, useless defrosting operation is prevented, and the energy saving effect can be improved.

When the operation-on duration of the compressor 21 is less than the set value, it is judged that the outdoor heat exchanger 13 is not frosted, or the outdoor heat exchanger 13 is frosted. If it is determined that the amount is small, the operation of the second refrigeration cycle is turned off only during the defrosting operation of the first refrigeration cycle as described above. Therefore, useless defrosting operation is prevented, and the energy saving effect can be improved.

During the defrosting operation of both refrigeration cycles, the second
When an operation-off command is input for the refrigeration cycle, the operation of the compressor 22 is immediately turned off, as shown by the solid line in FIG. After that, the compressor 22 is not immediately started even if an operation-on command is input for the second refrigeration cycle. As indicated by the broken line in FIG. 5, when the defrosting operation of the first refrigeration cycle is completed, the compressor 22 is started in synchronization with it and the heating operation is restarted. In the above embodiment, the case where there are two indoor heat exchangers for each refrigeration cycle has been described as an example, but the number of indoor heat exchangers is not limited and can be set appropriately.

[0046]

As described above, according to the present invention, when both the first refrigeration cycle and the second refrigeration cycle are in the heating operation, when one refrigeration cycle enters the defrosting operation, the other refrigeration cycle is Since the defrosting operation or the operation off is performed according to the discharge refrigerant temperature of the compressor of the refrigeration cycle and the operation-on duration, the defrosting of the two refrigeration cycles can be performed without interfering with each other, and unnecessary defrosting is performed. It is possible to provide an air conditioner that can prevent frost and improve the energy saving effect, and that can extend the defrost time and eliminate the defrost residue to improve the heating efficiency.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a refrigeration cycle according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a configuration of an outdoor heat exchanger of each refrigeration cycle in the same example.

FIG. 3 is a configuration diagram of a control circuit of the same embodiment.

FIG. 4 is a view for explaining defrosting operation control of the same embodiment.

FIG. 5 is a diagram for explaining increase / decrease in operation cycle during the defrosting operation of the same embodiment.

[Explanation of symbols]

11, 21 ... Variable capacity compressor, 12, 22 ... Four-way valve, 1
3, 23 ... Outdoor heat exchanger, 32, 42, 52, 62 ... Indoor heat exchanger, 15, 25 ... Refrigerant temperature sensor, 16, 26
... heat exchanger temperature sensor, 80 ... control unit.

Claims (1)

[Claims] 1. A heat pump type first refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a pressure reducer, and an outdoor heat exchanger are connected, and a compressor, a four-way valve, an indoor heat exchanger, a pressure reducer,
A second heat pump type refrigeration cycle in which an outdoor heat exchanger having a heat exchange relationship with the outdoor heat exchanger of the first refrigeration cycle is connected, and a heat pump type second refrigeration cycle removes the outdoor heat exchanger in each refrigeration cycle during heating operation. In the simultaneous heating operation of the frost operation and each of the refrigeration cycles, when one refrigeration cycle enters the defrost operation, the other refrigeration cycle, the refrigerant discharge temperature of the compressor of the refrigeration cycle and the operation on duration time. An air conditioner characterized by comprising: