JP2011149611A - Air-conditioning apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air-conditioning apparatus that suppresses the occurrence of pulsation noise. <P>SOLUTION: The air-conditioning apparatus at least includes: a refrigerating cycle having a compressor 1, an indoor side heat exchanger 3, an outdoor side heat exchanger 4, and a variable electric expansion valve 5; a saturation temperature detection means 8 (9) that detects a saturation temperature of a cooling medium 10; and a discharge temperature detecting means that detects a temperature of the cooling medium discharged from the compressor 1. The air-conditioning apparatus calculates the degree of superheat of the cooling medium that is absorbed into based on the difference between the saturation temperature that is detected by the saturation temperature detection means and the discharge temperature that is detected by the discharge temperature detecting means, and increases an operation frequency of the compressor when the calculated degree of the superheat of the cooling medium is lower than a certain threshold. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for controlling an air conditioner.

  A conventional air conditioner has a refrigeration cycle in which a compressor, an evaporation side heat exchanger, a condensation side heat exchanger, and an electronic expansion valve that can be changed are connected in an annular shape. In such a refrigeration cycle, If the refrigerant heat-exchanged by the exchanger remains in a liquid state, the refrigerant returns to the compressor in a liquid state. As described above, when the refrigerant heating degree is low in the refrigeration cycle, for example, there are cooling operations when the environmental temperature is low.

  If the compressor is continuously operated in such a state that the liquid refrigerant returns to the compressor in this way, problems such as liquid compression and poor lubrication that impair the reliability of the compressor are caused, and consequently the life of the compressor is reduced. . Conventionally, a gas-liquid separator is installed as a measure for preventing liquid refrigerant from returning to the compressor (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 11-83209

  However, even if a gas-liquid separator is provided as in the above-described conventional configuration, the liquid refrigerant is compressed with a small amount, but abnormal sound called pulsation noise may occur, and this phenomenon is caused by the suction of the compressor. This tends to occur in situations where the degree of refrigerant heating cannot be obtained.

  This invention solves the said conventional subject, and it aims at providing the air conditioner which suppressed generation | occurrence | production of a pulsation sound.

  In order to solve the above-described conventional problems, an air conditioner of the present invention includes at least a compressor, an indoor heat exchanger, an outdoor heat exchanger, and a refrigeration cycle having a variable electronic expansion valve; Saturation temperature detection means for detecting the saturation temperature of the refrigerant and discharge temperature detection means for detecting the temperature of the refrigerant discharged from the compressor. The saturation temperature detected by the saturation temperature detection means, and the discharge temperature detection means By calculating the superheat degree of the refrigerant sucked into the compressor based on the detected discharge temperature, and if the calculated superheat degree of the refrigerant falls below a certain threshold, the operating frequency of the compressor is increased. , The discharge temperature of the compressor can be raised and the state of heating of the refrigerant in the suction part of the compressor can be maintained, and the occurrence of the liquid return phenomenon of the refrigerant is suppressed, and consequently the generation of pulsation noise is suppressed. Is possible

  The air conditioner of the present invention can suppress the generation of pulsating noise.

Control flowchart according to Embodiment 1 of the present invention The block diagram of the air conditioner in Embodiment 1

  The air conditioner of the first invention is a refrigeration cycle having at least a compressor, an indoor heat exchanger, an outdoor heat exchanger, and an electronic expansion valve that can be varied, and saturation for detecting a saturation temperature of the refrigerant. A temperature detection means and a discharge temperature detection means for detecting the temperature of the refrigerant discharged from the compressor, based on the saturation temperature detected by the saturation temperature detection means and the discharge temperature detected by the discharge temperature detection means In addition to calculating the superheat degree of the refrigerant sucked into the compressor, if the calculated superheat degree of the refrigerant falls below a certain threshold, the compressor discharge temperature is increased by increasing the operating frequency of the compressor. Therefore, it is possible to maintain a state in which the degree of heating of the refrigerant in the suction portion of the compressor can be maintained, and it is possible to suppress the liquid return phenomenon of the refrigerant and thus to suppress the generation of pulsating noise.

  In the air conditioner of the second invention, particularly in the first invention, when the degree of refrigerant heating is below a certain threshold, the degree of heating of the refrigerant can always be increased by further reducing the opening of the electronic expansion valve. Thus, it is possible to prevent the occurrence of the liquid return phenomenon of the refrigerant and suppress the generation of the pulsating sound.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a flowchart showing control for maintaining the degree of refrigerant superheat of the air conditioner in the first embodiment, and FIG. 2 is a configuration diagram of the air conditioner in the first embodiment.

  First, the structure of the air conditioner in this Embodiment 1 is demonstrated using FIG. As shown in FIG. 2, the refrigeration cycle in the first embodiment includes a compressor 1 that compresses refrigerant, a four-way valve 2 that switches a refrigerant flow direction in the refrigerant flow path, and heat exchange between the refrigerant and indoor air. It has an indoor heat exchanger 3 to perform, an outdoor heat exchanger 4 for heat exchange between the refrigerant and outdoor air, and an electronic expansion valve 5 whose opening degree can be changed. It is connected.

  As a result, during the cooling operation, the high-temperature refrigerant discharged from the compressor 1 passes through the four-way valve 2, exchanges heat with outdoor air in the outdoor heat exchanger 4, and then passes through the electronic expansion valve 5. It flows into the inner heat exchanger 3 and exchanges heat with room air, and returns to the compressor 1 via the four-way valve 2 again. Further, during the heating operation, the high-temperature refrigerant discharged from the compressor 1 passes through the four-way valve 2, exchanges heat with room air in the indoor heat exchanger 3, and then passes through the electronic expansion valve 5 to enter the outdoor side. It flows into the heat exchanger 4 and exchanges heat with outdoor air, and returns to the compressor 1 via the four-way valve 2 again.

  In addition, an indoor fan 6 that generates an air flow to promote heat exchange in the indoor heat exchanger 3 and an outdoor fan 7 that generates an air flow to promote heat exchange in the outdoor heat exchanger 4 are provided. Have. In addition, the indoor side heat exchanger 3 and the indoor fan 6 are arranged in an indoor unit installed in the room, and air-condition the installed room.

  Further, a saturation temperature detecting means for detecting the refrigerant saturation temperature is provided in each of the indoor heat exchanger 3 and the outdoor heat exchanger 4, and the indoor heat exchanger 3 is an indoor saturation temperature detecting means. The temperature sensor 8 is provided in the outdoor heat exchanger 4 and a temperature sensor 9 serving as an outdoor saturation temperature detecting means is provided. Further, a temperature sensor 10 serving as a discharge temperature detecting means for detecting the discharge temperature of the compressor 1 is provided, and the temperature sensor 10 detects the temperature of the refrigerant discharged from the compressor 1.

  The control unit 11 includes a microcomputer and its peripheral circuits. In the control unit 11, the saturation temperature of the refrigerant detected by the temperature sensor 8 and the temperature sensor 9 and the refrigerant detected by the temperature sensor 10. The current refrigeration cycle state is sequentially calculated from the discharge temperature of the compressor and the rotation speed of the compressor 1.

  Next, control for maintaining the degree of refrigerant superheat of the air conditioner in Embodiment 1 will be described with reference to FIG.

  As shown in FIG. 1, during normal operation, first, in step 1, the refrigerant temperature and the operating state of each device are detected from various temperature sensors, and in step 2 the state of the refrigeration cycle is detected. In the control of the refrigeration cycle according to the present invention, the superheat degree of the refrigerant is sequentially calculated from the refrigeration cycle states, and the refrigerant temperature detected by the temperature sensor 8 and the temperature sensor 9 and the temperature sensor 10 are detected. Based on the refrigerant temperature and the rotational speed of the compressor 1, the superheat degree SH1 of the refrigerant sucked into the compressor 1 is calculated.

  In step 3, the calculated superheat degree SH1 is compared with a preset superheat degree SH2. At this time, the superheat degree SH2 set in advance is set as a superheat degree at which the refrigerant state of the suction portion of the compressor 1 does not become a liquid refrigerant, and is calculated in advance by experiments. Therefore, the degree of superheat SH2 is not uniquely determined, and differs depending on the configuration of the refrigeration cycle.

  When a state in which the superheat degree SH1 is lower than the superheat degree SH2 is detected in step 3, in step 4, the operating frequency of the compressor 1 is increased and the opening degree of the electronic expansion valve 5 is reduced. As a result, since the temperature of the refrigerant discharged from the compressor 1 rises, the liquid return phenomenon of the refrigerant sucked into the compressor 1 can be suppressed.

  In step 5, the superheat degree SH1 of the refrigerant sucked into the compressor 1 is calculated again. In step 6, the recalculated superheat degree SH1 is compared with the preset superheat degree SH2, and the superheat degree is calculated. When SH1 returns to the superheat degree SH2 or higher, the operation returns to the normal operation control, but when the superheat degree SH1 still does not recover to the superheat degree SH2 or higher, the operating frequency of the compressor 1 is increased again, The discharge temperature of the refrigerant is raised so that the degree of superheat of the refrigerant can be obtained.

  Thus, until the superheat degree SH1 returns to the superheat degree SH2, step 4 and step 5 are repeated, and when the superheat degree SH1 exceeds the superheat degree SH2, the normal operation control is resumed. The state which can be taken can be maintained, generation | occurrence | production of the liquid return phenomenon of a refrigerant | coolant can be prevented, and generation | occurrence | production of a pulsation sound can be suppressed.

  During normal operation, the frequency of the compressor 1 is changed according to the indoor temperature and the indoor set temperature, and the optimum discharge temperature is preset for the current frequency of the compressor 1 and is detected by the temperature sensor 10. The opening degree of the electronic expansion valve 5 is changed so that the discharge temperature to be achieved becomes a predetermined optimal discharge temperature. In step 4, the operation frequency of the compressor 1 is increased and the opening degree of the electronic expansion valve 5 is controlled. However, only one of them may be used.

  As described above, since the air conditioner according to the present embodiment performs control according to the degree of refrigerant superheat, it is possible to perform an optimal air conditioning operation while suppressing generation of pulsating noise.

  The air conditioner according to the present invention can be controlled in a state where the degree of refrigerant superheat can always be obtained, can suppress the occurrence of liquid return phenomenon, can prevent the generation of pulsation noise, and is separated into an indoor unit and an outdoor unit. It is most suitable for the control of the separation type air conditioner.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Four way valve 3 Indoor side heat exchanger 4 Outdoor side heat exchanger 5 Electronic expansion valve 6 Indoor side fan 7 Outdoor side fan 8 Temperature sensor (indoor saturation temperature detection means)
9 Temperature sensor (outdoor saturation temperature detection means)
10 Temperature sensor 11 Control unit

Claims (2)

A refrigeration cycle having at least a compressor, an indoor heat exchanger, an outdoor heat exchanger, and a variable electronic expansion valve, saturation temperature detecting means for detecting a saturation temperature of the refrigerant, and discharged from the compressor And a discharge temperature detecting means for detecting the temperature of the refrigerant, and the refrigerant sucked into the compressor based on the saturation temperature detected by the saturation temperature detecting means and the discharge temperature detected by the discharge temperature detecting means An air conditioner that calculates the superheat degree of the compressor and raises the operating frequency of the compressor when the calculated superheat degree of the refrigerant falls below a certain threshold value. The air conditioner according to claim 1, wherein when the degree of refrigerant heating falls below a certain threshold, the opening of the electronic expansion valve is further throttled.

Images