JPH11201594A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the noise in an indoor unit during defrosting operation, by fully closing the expansion valve of the indoor unit that is in the shut down condition at the time of the defrosting operation of the outdoor unit during heating operation, and by fully opening the expansion valve of the indoor unit that is in the operating condition. SOLUTION: In a defrosting operation, a heating operation is started (S12) by tuming on a power supply (S11). When an outdoor heat exchanger is frosted at the time of the heating operation, the time when the temperature Tn of a heat exchanging sensor becomes a defrosting starting temperature or lower (S13) is determined as the start of the defrosting operation by a control device. Then, the control device issues a command to an electronic expansion valve driving means (S14), and fully closes the electronic expansion valve of the indoor unit that stops to operate (S15). When the temperature Tn becomes the defrosting completion temperature or higher (S16), it is determined as the completion of the defrosting operation. Then, the command is issued to the electronic expansion valve driving means (S17), and a normal heating operation is returned (S18).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique suitable for use in an air conditioner.

[0002]

2. Description of the Related Art FIG. 3 shows a so-called multi-type air conditioner in which a plurality of indoor units (two in the illustrated example) are connected. In FIG.
a and 2b are indoor units, 3 is a compressor, 5c is an outdoor heat exchanger, 7a and 7b are expansion valves (electronic expansion valves), 9 is a heat exchange sensor, 10a and 10b are indoor heat exchangers, 30 is a control device, 31 is an electronic expansion valve control means, and 32 is an electronic expansion valve driving means. Note that, here, the description will be made using only those parts of FIG. 3 necessary for understanding the related art.

In such an air conditioner, for example, the indoor unit 2a is in an operating state during the heating operation, but the indoor unit 2b may be stopped. During the heating operation, frost may be formed on the outdoor heat exchanger 5c of the outdoor unit 1, and in that case, the defrosting operation has been performed.

[0004] Conventional defrosting operation control will be described with reference to FIG. During the defrosting operation, the heating operation is started by turning on the power (step S1) (step S1).
2). When frosted outdoor heat exchanger 5c during the heating operation, the temperature T _n of the heat exchange sensor 9 is transmitted to the electronic expansion valve control means 31 of the control device 30, the temperature T _n defrosting initiation temperature less (Step S3), the control device 30 determines that the defrosting operation has started (Step 4), and issues a command to the electronic expansion valve driving means 32 by the electronic expansion valve control means 31 to stop the operation of the room. The electronic expansion valve 7b of the unit 2b is fully opened (Step 5). At the same time, the control device 3
0, the compressor 3 is operated at the maximum number of revolutions, and the discharged gas is supplied to the outdoor heat exchanger 5 of the outdoor unit 1.
In step c, the frost is melted and condensed and liquefied. The refrigerant liquid passes through the electronic expansion valve 7a and the electronic expansion valve 7b which are fully opened, and the indoor heat exchanger 10a and the indoor heat exchanger 10a.
b, the gas is absorbed, gasified and returned to the compressor 3. When the temperature _Tn becomes _equal to or higher than the defrost end temperature (step S6), the control device 30 determines that the defrost operation has ended (step S7), issues a command to the electronic expansion valve driving means 32, and performs normal heating. Return to operation (step S8).

[0005]

However, during the conventional defrosting operation, the refrigerant flows to the electronic expansion valve 7b of the stopped indoor unit 2b, and the sound of the operation of the electronic expansion valve 7b and the electronic expansion of the refrigerant. The sound flowing through the valve 7b is transmitted to the indoor unit 2
The noise was in the room where b was installed.

The present invention has been made in view of the above circumstances, and has as its object to suppress noise in an indoor unit during a defrosting operation.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an air conditioner having an outdoor unit and a plurality of indoor units.
During the defrosting operation of the outdoor unit during the heating operation, the expansion valve of the indoor unit in the operation stop state is fully closed, and the expansion valve of the indoor unit in the operation state is fully opened. The above problem has been solved by preventing the refrigerant from flowing to the indoor unit in the operation stop state.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an air conditioner according to the present invention will be described below with reference to the drawings. FIG. 1 is an electronic expansion valve opening control flowchart according to the present embodiment, which is executed by the control unit 30 of the air conditioner shown in FIG.

The air conditioner shown in FIG. 3 is a so-called multi-type air conditioner in which a plurality of indoor units (two in the illustrated example) are connected, and includes an outdoor unit 1 and indoor units 2a, 2a.
2b are connected by a refrigerant circuit. In FIG. 3, reference numeral 4 denotes a four-way valve, 5d denotes an outdoor heat exchanger, and 6c and 6d.
Is a temperature type expansion valve, 10 is an accumulator, 11a, 1
1b is an indoor fan, 11c and 11d are supercooling heat exchangers,
12c and 12d are check valves, and 14 is a receiver.

The outdoor unit 1 includes a compressor 3 and
A four-way valve 4, outdoor heat exchangers 5c and 5d, thermal expansion valves 6c and 6d, accumulators 10, supercooling heat exchangers 11c and 11d, check valves 12c and 12d, and a receiver 14 are provided. And these constitute a refrigerant circuit.
Further, the outdoor unit 1 is provided with a heat exchange sensor 9 for measuring the temperature of the outdoor heat exchangers 5c and 5d, and a control device 30 connected to the heat exchange sensor 9.

The indoor units 2a and 2b include expansion valves (electronic expansion valves) 7a and 7b and an indoor heat exchanger 10 respectively.
a, 10b are connected to the refrigerant circuit, and the indoor heat exchangers 10a, 10b are provided with indoor fans 11a, 11b.
b is provided.

The control device 30 includes electronic expansion valve control means 31, electronic expansion valve drive means 32, compressor inverter control means (not shown), and drive means (not shown). The electronic expansion valve driving means 32 instructs the opening degree to the electronic expansion valve driving means 32, and the electronic expansion valve driving means 32 operates the electronic expansion valves 7a and 7b to fully open and fully closed in accordance with the instruction.

In such an air conditioner, for example, the indoor unit 2a is in an operating state during the heating operation, but the indoor unit 2b may be stopped. Here, the high-temperature and high-pressure refrigerant gas compressed by the compressor 3 of the outdoor unit 1 enters the indoor heat exchangers 10a and 10b of the indoor units 2a and 2b via the four-way valve 4, and the indoor unit 2a
Is cooled by the indoor fan 11a and condensed and liquefied. Further, the indoor fan 11b of the indoor unit 2b is stopped, and the refrigerant gas does not condense in the indoor heat exchanger 10b.

The refrigerant liquid that has passed through the electronic expansion valve 7a and the refrigerant gas that has passed through the electronic expansion valve 7b are mixed to form a receiver 14
After entering, it is cooled by the supercooling heat exchangers 11c and 11d, and becomes a complete refrigerant liquid. This refrigerant liquid is decompressed by the thermal expansion valves 6c and 6d, absorbs heat in the outdoor heat exchangers 5c and 5d, gasifies, and passes through the four-way valve 4 to the accumulator 1.
Return to compressor 3 through 0.

In the above-described air conditioner, frost may form on the outdoor heat exchangers 5c and 5d of the outdoor unit 1 during the heating operation. In such a case, the defrosting operation is performed.
The defrosting operation in the present embodiment will be described with reference to FIG. During the defrosting operation, when the power is turned on as shown in step S11, the heating operation is started as shown in step S12. If the frosted outdoor heat exchanger 5c, the 5d during heating operation, the temperature T _n of the heat exchange sensor 9 is transmitted to the electronic expansion valve control means 31 of the control unit 30, step S
When the temperature _Tn becomes equal to or lower than the defrosting start temperature as shown in FIG. 13, the control device 30 determines that the defrosting operation has started as shown in step S14, and the electronic expansion valve control means 31 drives the electronic expansion valve. The indoor unit 2 that has issued an instruction to the means 32 and has stopped operating as shown in step S15
b is fully closed.

At the same time, the compressor 3 is operated at the maximum number of revolutions by a compressor inverter control means (not shown) of the control device 30 and a drive means (not shown), and the discharge gas of the compressor 3 passes through the four-way valve 4 to exchange outdoor heat. The frost is melted and condensed and liquefied in the vessels 5c and 5d. The refrigerant liquid is further cooled by the supercooling heat exchangers 11c and 11d through the check valves 12c and 12d, passes through the receiver 14, passes through the fully opened electronic expansion valve 7a, and passes through the indoor heat exchanger. Heat is absorbed at 10a, gasified, and returned to the compressor 3 via the four-way valve 4 and the accumulator 10. Then, when the temperature _Tn becomes _equal to or higher than the defrost end temperature as shown in step S16, the control device 30 determines that the defrost operation has ended as shown in step S17, and issues a command to the electronic expansion valve driving means 32. However, as shown in step 18, the operation returns to the normal heating operation.

As a result, when the defrosting operation is performed during the heating operation, the electronic expansion valve 7b of the stopped indoor unit 2b is fully closed by the electronic expansion valve control means 31, and the operation of the indoor unit 2a which has been operating is stopped. Since the refrigerant does not flow through the electronic expansion valve 7b by fully opening the electronic expansion valve 7a, the electronic expansion valve 7b of the stopped indoor unit 2b
And the sound of the refrigerant flowing through the indoor heat exchanger 10b can be suppressed, and the noise of the indoor unit 2b can be suppressed.

[0018]

According to the air conditioner of the present invention, the electronic expansion valve of the indoor unit stopped during the heating operation is fully closed during the defrosting operation, and only the operated indoor unit is also operated during the defrosting operation. By opening the electronic expansion valve, the operation sound of the electronic expansion valve of the indoor unit that was stopped during the heating operation and the sound of the refrigerant flowing through the indoor heat exchanger are suppressed, and the noise in the indoor unit during the defrosting operation is reduced. Can be suppressed.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating opening control of an electronic control valve in an embodiment of an air conditioner according to the present invention.

FIG. 2 is a flowchart showing a conventional opening control of an electronic control valve.

FIG. 3 is a block diagram showing a refrigerant circuit diagram and the like of the air conditioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Outdoor unit 2a, 2b ... Indoor unit 3 ... Compressor 4 ... Four-way valve 5c, 5d ... Outdoor heat exchanger 6c, 6d ... Temperature-type expansion valve 7a, 7b ... Expansion valve (electronic expansion valve) 9 ... Heat exchange sensor 10 ... Accumulators 10a, 10b ... Indoor heat exchangers 11a, 11b ... Indoor fans 11c, 11d ... Subcooling heat exchangers 12c, 12d ... Check valves 14 ... Receiver 30 ... Control device 31 ... Electronic expansion valve control means 32 ... Electronic expansion Valve drive means

Claims (1)

[Claims] In an air conditioner having an outdoor unit and a plurality of indoor units, when a defrosting operation of the outdoor unit is performed during the heating operation, the expansion valve of the indoor unit in the operation stop state is fully closed, and the operation is performed. An air conditioner characterized by fully opening an expansion valve of an indoor unit in a state.