JP2005037052A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a defrost controlling method for an air conditioner capable of improving the reliability of a compressor by preventing the lowering of a refrigerant sucking pressure of the compressor without elongating a defrosting time. <P>SOLUTION: A capacity variable compressor is changed to a specific frequency by switching a four-way valve to a cooling circuit, when a temperature detected by an outdoor heat exchanger temperature detecting means becomes lower than a first specific temperature in a heating operation. When the pressure detected by a sucked pressure detecting means is lower than a specific pressure, a gas bypass valve is controlled to be opened. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an air conditioner, and more particularly to defrosting control of an outdoor heat exchanger provided in the air conditioner.

  A conventional defrosting control method for an air conditioner reduces the suction pressure drop by reducing the operating frequency of the compressor when the compressor suction pressure drops below a predetermined value during defrosting (for example, patents). Reference 1).

Japanese Patent Laid-Open No. 5-71832 (paragraph 0043, FIG. 5)

  However, in the above-described conventional configuration, reducing the compressor operating frequency is an effective means when the compressor suction pressure is reduced. However, if the defrosting capability is required, the defrosting capability is reduced. The problem of lengthening the defrosting time was a problem.

  The present invention has been made in view of such problems of the prior art, and improves the reliability of the compressor by preventing a decrease in the refrigerant suction pressure of the compressor without increasing the defrosting time. An object of the present invention is to provide a defrosting control method for an air conditioner.

  In order to achieve the above object, the invention according to claim 1 of the present invention is an outdoor unit having a variable capacity compressor, a four-way valve, and an outdoor heat exchanger, and an indoor unit having an indoor heat exchanger. An air conditioner having a refrigeration cycle configured by connecting a refrigerant pipe and a gas bypass pipe that bypasses the refrigerant discharge pipe and the refrigerant suction pipe of the compressor, and attached to the gas bypass pipe A gas bypass valve, suction pressure detection means for detecting the pressure of refrigerant sucked into the compressor, and an outdoor heat exchanger temperature detection means for detecting the temperature of the outdoor heat exchanger, during heating operation, When the temperature detected by the outdoor heat exchanger temperature detecting means is equal to or lower than a first predetermined temperature, the four-way valve is switched to a cooling circuit to change the variable capacity compressor to a predetermined frequency, and the suction pressure detection By means If the sensed pressure is less than a predetermined pressure, characterized in that so as to open control said gas bypass valve.

  Further, according to the second aspect of the present invention, when the pressure detected by the suction pressure detecting means exceeds a predetermined pressure, the gas bypass valve is closed and the temperature detected by the outdoor heat exchanger temperature detecting means is detected. When the temperature reaches a second predetermined temperature higher than the first predetermined temperature, the four-way valve is switched to a heating circuit.

  According to the present invention, during the heating operation, when the temperature detected by the outdoor heat exchanger temperature detecting means becomes equal to or lower than the first predetermined temperature, the four-way valve is switched to the cooling circuit and the variable capacity compressor is set to the predetermined frequency. The gas bypass valve is controlled to open when the pressure detected by the suction pressure detection means becomes smaller than the specified pressure, preventing an extreme drop in the compressor suction pressure without lengthening the defrosting time. This can improve the reliability of the compressor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a multi-room air conditioner according to the present invention, in which a plurality of (two in FIG. 1) indoor units 4a and 4b are connected to one outdoor unit 2 by refrigerant piping. The outdoor unit 2 is provided with a variable capacity compressor 6, a four-way valve 8, an outdoor heat exchanger 10, and an outdoor expansion valve 12 that are sequentially connected by refrigerant piping, while each of the indoor units 4 a and 4 b has Are provided with indoor heat exchangers 14a and 14b and indoor expansion valves 16a and 16b sequentially connected by refrigerant piping, and the plurality of indoor units 4a and 4b are connected to the outdoor unit 2 in parallel.

  The outdoor unit 2 includes an oil separator 17 for separating a compressor lubricating oil contained in the refrigerant gas into which a part of the refrigerant gas discharged from the compressor 6 is introduced, and a refrigerant discharge pipe of the compressor 6. A gas bypass pipe 18 that bypasses the refrigerant suction pipe, a gas bypass valve (electromagnetic on-off valve) 19 attached to the gas bypass pipe 18, and liquid refrigerant condensed in the outdoor heat exchanger 10 during cooling or dehumidifying operation are stored. A buffer tank 20 is provided.

  Further, the outdoor unit 2 includes an outdoor fan 21 that sends air to the outdoor heat exchanger 10, discharge temperature detection means 22 that detects the temperature of the refrigerant discharged from the compressor 6, and refrigerant that is sucked into the compressor 6. Suction temperature detecting means 23 and suction pressure detecting means 24 for detecting the temperature and pressure of the outdoor heat exchanger, outdoor heat exchanger temperature detecting means 26 for detecting the temperature of the outdoor heat exchanger 10, and outdoor temperature detecting means for detecting the outdoor temperature. 28 are provided. On the other hand, the indoor units 4a and 4b include indoor fans 30a and 30b that send air to the indoor heat exchangers 14a and 14b, and indoor heat exchange that detects the temperature (condensation temperature or evaporation temperature) of the indoor heat exchangers 14a and 14b. Temperature detectors 32a and 32b, indoor pipe temperature detectors 34a and 34b for detecting indoor pipe temperature (exit temperature when functioning as an evaporator), and indoor temperature detectors 36a and 36b for detecting indoor temperature Is provided.

  In the multi-room air conditioner according to the present invention having the above-described configuration, during the cooling operation and the dehumidifying operation, the four-way valve 8 is switched so that the refrigerant flows in the arrow direction shown in FIG. 1, and the indoor heat exchanger temperature detecting means 32a, Based on the indoor heat exchanger temperature detected by 32b and the indoor heat exchanger outlet temperature detected by the indoor pipe temperature detection means 34a, 34b, the refrigerant superheat degree at the outlet of the indoor heat exchangers 14a, 14b is calculated, High-efficiency operation is performed by controlling the refrigeration cycle so that the refrigerant superheat degree becomes a predetermined value.

  On the other hand, during the heating operation, the four-way valve 8 is switched so as to constitute a heating circuit, and the refrigerant gas discharged from the compressor 6 is first guided to the indoor units 4a and 4b and then to the outdoor unit 2. Return to the compressor 6 again.

  A defrosting control method during normal heating control of the multi-room air conditioner having the above configuration will be described below with reference to the flowchart of FIG. 2 and the time chart of FIG.

  First, in step S1, it is determined whether or not the evaporation temperature Tc of the outdoor heat exchanger 10 detected by the outdoor heat exchanger temperature detection means 26 is equal to or lower than a predetermined temperature (inrush temperature in FIG. 3). When it is determined that the evaporation temperature Tc of the outdoor heat exchanger 10 is equal to or lower than the predetermined temperature (YES in step S1), it is determined that the outdoor heat exchanger 10 has been frosted, and the process proceeds to defrosting control in step S2. If it is determined that the evaporation temperature Tc of the outdoor heat exchanger 10 is higher than the predetermined temperature (NO in step S1), it is determined that the outdoor heat exchanger 10 has no frost formation, and the determination in step S1 is performed. repeat.

  In the defrosting control in step S2, first, the four-way valve 8 is switched to the cooling circuit, the compressor 6 is changed to a predetermined frequency in the cooling circuit, and the compression detected by the suction pressure detecting means 24 in the next step S3. It is determined whether the suction pressure Ps of the machine 6 is equal to or higher than a predetermined pressure. If it is determined that the suction pressure Ps of the compressor 6 is equal to or higher than the predetermined pressure (YES in step S3), the process proceeds to step S4, while it is determined that the suction pressure Ps of the compressor 6 is smaller than the predetermined pressure ( If the determination in step S3 is NO), the process proceeds to step S5, where gas bypass valve control is performed.

  In the gas bypass valve control in step S <b> 5, part of the gas refrigerant discharged from the compressor 6 is returned to the compressor 6 by opening the gas bypass valve 19. The gas bypass valve control is performed until the suction pressure Ps of the compressor 6 detected by the suction pressure detection means 24 becomes equal to or higher than a predetermined pressure (release pressure in FIG. 3), and the compressor 6 is not lengthened. The reliability of the compressor 6 is improved by preventing an extreme decrease in the suction pressure.

  In step S4, the gas bypass valve 19 that has been controlled to open in step S5 is closed, and the evaporation temperature Tc of the outdoor heat exchanger 10 detected by the outdoor heat exchanger temperature detecting means 26 is higher than the inrush temperature. It is determined whether or not the temperature is equal to or higher than a predetermined temperature (release temperature in FIG. 3). If it is determined that the evaporation temperature Tc of the outdoor heat exchanger 10 is equal to or higher than the predetermined temperature (YES in step S4), it is determined that the frost attached to the outdoor heat exchanger 10 has disappeared, and the normal heating control in step S6 is performed. On the other hand, when it is determined that the evaporation temperature Tc of the outdoor heat exchanger 10 is lower than the predetermined temperature (NO in step S4), it is determined that the frost attached to the outdoor heat exchanger 10 still remains. The determination in step S4 is repeated.

  In the normal heating control in step S6, the four-way valve 8 is switched to the heating circuit again and the compressor 6 is changed to a predetermined frequency in the heating circuit to perform the heating operation.

  Although the above embodiment has been described by taking a multi-room air conditioner as an example, the present invention is not limited to a multi-room air conditioner, and air in which one indoor unit is connected to one outdoor unit. It can also be used in a harmony machine.

  The air conditioner according to the present invention can prevent an extreme decrease in the suction pressure of the compressor without lengthening the defrosting time, so that the reliability of the compressor can be improved, and the outdoor heat exchanger This is useful for defrosting control of

It is a refrigerating cycle figure of the air conditioner concerning this invention. It is a flowchart which shows gas bypass valve control at the time of defrosting of the air conditioner concerning this invention. It is a time chart which shows gas bypass valve control at the time of defrosting of the air conditioner concerning this invention.

Explanation of symbols

2 outdoor unit, 4a, 4b indoor unit, 6 capacity variable compressor,
8 four-way valve, 10 outdoor heat exchanger, 12 outdoor expansion valve,
14a, 14b indoor heat exchangers, 16a, 16b indoor expansion valves,
17 Oil separator, 18 Gas bypass pipe,
19 gas bypass valve, 20 buffer tank, 21 outdoor fan,
22 discharge temperature detection means, 23 suction temperature detection means,
24 suction pressure detection means, 26 outdoor heat exchanger temperature detection means,
28 outdoor temperature detection means, 30a, 30b outdoor temperature detection means,
32a, 32b Indoor heat exchanger temperature detection means,
34a, 34b Indoor piping temperature detection means,
36a, 36b Indoor temperature detection means.

Claims (2)

An air conditioner having a refrigeration cycle configured by connecting an outdoor unit having a variable capacity compressor, a four-way valve, and an outdoor heat exchanger, and an indoor unit having an indoor heat exchanger by a refrigerant pipe,
A gas bypass pipe bypassing the refrigerant discharge pipe and the refrigerant suction pipe of the compressor; a gas bypass valve attached to the gas bypass pipe; and a suction pressure detection means for detecting the pressure of the refrigerant sucked into the compressor And an outdoor heat exchanger temperature detecting means for detecting the temperature of the outdoor heat exchanger, and when the temperature detected by the outdoor heat exchanger temperature detecting means is equal to or lower than a first predetermined temperature during heating operation. The four-way valve is switched to a cooling circuit, the variable capacity compressor is changed to a predetermined frequency, and when the pressure detected by the suction pressure detecting means becomes smaller than a predetermined pressure, the gas bypass valve is controlled to open. An air conditioner characterized by When the pressure detected by the suction pressure detecting means exceeds a predetermined pressure, the gas bypass valve is controlled to be closed, and the temperature detected by the outdoor heat exchanger temperature detecting means is higher than the first predetermined temperature. The air conditioner according to claim 1, wherein the four-way valve is switched to a heating circuit when the temperature exceeds a predetermined temperature.

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