JP2007040589A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner capable of reducing refrigerant noise. <P>SOLUTION: When a difference Tmax-Tmin between a max value Tmax and a minimum value Tmin out of outlet temperatures T1-TN of a plurality of refrigerant circuits 8.1-8.N of an outdoor heat exchanger 5 exceeds a predetermined temperature Ts (for example 8°C) (S3), the air conditioner determines that a possibility of occurrence of the refrigerant noise is high because refrigerants in different conditions flow in the refrigerant circuits 8.1-8.N, and reduces a rotation number of a compressor 6 (S4) to reduce a circulating volume of the refrigerant and reduce the refrigerant noise. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner that performs a defrosting operation when frost is formed on an outdoor heat exchanger.

Conventionally, in an air conditioner, the refrigerant condensed in the indoor heat exchanger is decompressed by a decompression device and given to the outdoor heat exchanger, and the refrigerant evaporated in the outdoor heat exchanger is compressed by the compressor to convert the high-temperature refrigerant. It is given to the indoor heat exchanger to heat the room. In addition, when the outdoor heat exchanger is frosted, the refrigerant condensed in the outdoor heat exchanger is decompressed by the decompression device and given to the indoor heat exchanger, and the refrigerant evaporated in the indoor heat exchanger is compressed by the compressor. Then, a high-temperature refrigerant is applied to the outdoor heat exchanger, and the defrosting operation is performed by defrosting the frost formed on the outdoor heat exchanger (see, for example, Patent Document 1).
JP 2003-172560 A

  However, when the outdoor heat exchanger has a plurality of refrigerant circuits (paths) connected in parallel, the refrigerant is condensed (liquefied) while defrosting the frost formed on the outdoor heat exchanger between the refrigerant circuits during defrosting. If there is a difference in the degree of aging, the refrigerant that is completely liquefied, the two-phase refrigerant that is not completely liquefied (liquid and gas are mixed), and the refrigerant that has not condensed because it flows through the circuit that has defrosted It will flow to the junction of the refrigerant circuit. When the refrigerant in such a different state flows into the merging portion, the decompression device portion (expansion valve or capillary tube), or the indoor heat exchanger, it may cause the generation of refrigerant noise in that portion.

  Therefore, a main object of the present invention is to provide an air conditioner capable of reducing refrigerant noise.

  In the air conditioner according to the present invention, during heating, the refrigerant condensed in the indoor heat exchanger is decompressed by the decompression device and given to the outdoor heat exchanger, and the refrigerant evaporated in the outdoor heat exchanger is compressed by the compressor. When the outdoor heat exchanger is defrosted, the refrigerant condensed in the outdoor heat exchanger is depressurized by the decompression device and applied to the indoor heat exchanger, and the refrigerant evaporated in the indoor heat exchanger is removed. In an air conditioner that is compressed by a compressor and applied to an outdoor heat exchanger, the outdoor heat exchanger includes a plurality of refrigerant circuits connected in parallel, and each of the air conditioners has a refrigerant flow during defrosting of the plurality of refrigerant circuits. The difference between the maximum value and the minimum value of the detection values of the multiple temperature sensors that detect the temperature of the outlet part and the multiple temperature sensors during defrosting of the outdoor heat exchanger exceeded the predetermined temperature. And a controller for reducing the drive rotational speed of the compressor To.

  Preferably, the decompression device is an expansion valve provided between the indoor heat exchanger and the outdoor heat exchanger, and the control unit further includes a maximum of detection values of the plurality of temperature sensors during defrosting of the outdoor heat exchanger. The opening degree of the expansion valve is controlled to close in response to the difference between the value and the minimum value exceeding a predetermined temperature.

  In the air conditioner according to the present invention, during heating, the refrigerant condensed in the indoor heat exchanger is decompressed by the expansion valve and supplied to the outdoor heat exchanger, and the refrigerant evaporated in the outdoor heat exchanger is compressed by the compressor. When the outdoor heat exchanger is defrosted, the refrigerant condensed in the outdoor heat exchanger is decompressed by the expansion valve and supplied to the indoor heat exchanger, and the refrigerant evaporated in the indoor heat exchanger is removed. In an air conditioner that is compressed by a compressor and applied to an outdoor heat exchanger, the outdoor heat exchanger includes a plurality of refrigerant circuits connected in parallel, and each of the air conditioners has a refrigerant flow during defrosting of the plurality of refrigerant circuits. The difference between the maximum value and the minimum value of the detection values of the multiple temperature sensors that detect the temperature of the outlet part and the multiple temperature sensors during defrosting of the outdoor heat exchanger exceeded the predetermined temperature. And a control unit that controls the opening degree of the expansion valve in a closing direction. To.

  In the air conditioner according to the present invention, when there is a difference in the degree to which the refrigerant is condensed (liquefied) while defrosting the frost formed on the outdoor heat exchanger between the refrigerant circuits during defrosting, the refrigerant is completely liquefied. The temperature of the refrigerant is lower than the temperature of the refrigerant in the two-phase state (a state where the liquid and gas are mixed), and the temperature of the uncondensed refrigerant flowing through the circuit that has finished defrosting is lower than the temperature of the refrigerant in the two-phase state high. When the temperatures at the outlets of the plurality of refrigerant circuits of the outdoor heat exchanger are detected and the difference between the maximum value and the minimum value exceeds a predetermined temperature, refrigerant in different states flows in the junction and refrigerant noise is generated. Since it is judged that the possibility is high and the driving speed of the compressor is reduced, the opening degree of the expansion valve is controlled to close, or both of them are performed to reduce the circulation amount of the refrigerant, Reduction can be achieved.

[Embodiment 1]
FIG. 1 is a refrigerant circuit diagram showing a configuration of an air conditioner according to Embodiment 1 of the present invention. In FIG. 1, the air conditioner includes an indoor blower 1, an indoor heat exchanger 2, a capillary tube 3, an outdoor blower 4, an outdoor heat exchanger 5, a compressor 6, and a four-way valve 7.

  The indoor blower 1 supplies room air to the indoor heat exchanger 2. The indoor heat exchanger 2 performs heat exchange between the indoor air supplied from the indoor blower 1 and the refrigerant. The capillary tube 3 reduces the pressure of the refrigerant. The outdoor blower 4 supplies outdoor air to the outdoor heat exchanger 5. The outdoor heat exchanger 5 performs heat exchange between the outdoor air supplied from the outdoor blower 4 and the refrigerant. The compressor 6 compresses the refrigerant. The four-way valve 7 switches the direction of refrigerant flow during heating and defrosting.

  At the time of heating, the four-way valve 7 allows the refrigerant to flow along the dotted line in the figure. The refrigerant that has absorbed heat from the outdoor air and evaporated in the outdoor heat exchanger 5 is given to the compressor 6 via the four-way valve 7. The high-temperature refrigerant compressed by the compressor 6 condenses (liquefies) the indoor heat exchanger 2 by applying heat to the indoor air. Thereby, room air is warmed. The refrigerant condensed in the indoor heat exchanger 2 is decompressed by the capillary tube 3 and given to the outdoor heat exchanger 5, absorbs the heat of the outdoor air through the outdoor heat exchanger 5, and evaporates (vaporizes).

  When frost adheres to the outdoor heat exchanger 5, the heat exchange efficiency of the outdoor heat exchanger 5 is lowered, and the heating effect is also lowered. Therefore, for example, when the temperature of the outdoor heat exchanger 5 becomes a predetermined value or less, it is determined that the outdoor heat exchanger 5 has been frosted, and the defrosting operation is performed.

  At the time of defrosting, the four-way valve 7 causes the refrigerant to flow along the path indicated by the solid line in the figure, and the fans 1 and 4 are stopped. The refrigerant evaporated in the indoor heat exchanger 2 is given to the compressor 6 through the four-way valve 7. The high-temperature refrigerant compressed by the compressor 6 gives heat to the outdoor heat exchanger 5 to condense (liquefy). Thereby, the outdoor heat exchanger 5 is warmed and defrosted. The refrigerant condensed in the outdoor heat exchanger 5 is decompressed by the capillary tube 3 and given to the indoor heat exchanger 2, absorbs the heat of the indoor air through the indoor heat exchanger 2, and evaporates (vaporizes).

  FIG. 2 is a diagram illustrating a configuration of the outdoor heat exchanger 5. 2, this outdoor heat exchanger 5 includes N refrigerant circuits 8.1 to 8.N connected in parallel (where N is an integer of 2 or more). N is included. The arrows in FIG. 2 indicate the direction in which the refrigerant flows during defrosting. Refrigerant circuit 8.1-8. N outlet pipes have temperature sensors 9.1 to 9. N is provided. The outlet piping of each circuit is collected at the junction and connected to the capillary tube 3.

  FIG. 3 is a block diagram showing the configuration of the air conditioner. In FIG. 3, the air conditioner includes an operation unit 10 and a control unit 11 in addition to those shown in FIGS. 1 and 2. The operation unit 10 includes a power switch, a temperature adjustment key, an air volume adjustment key, a timer, and the like. The control unit 11 includes instructions input from the user via the operation unit 10 and temperature sensors 9.1 to 9. According to the detection result of N, etc., control of the air volume of the blowers 1 and 4, control of the driving frequency of the compressor 6, switching of the four-way valve 7 and the like are performed.

  FIG. 4 is a flowchart showing the operation of the control unit 11 during the defrosting operation. In step S1, the control unit 11 starts driving the compressor 6, and sets the driving frequency of the compressor 6, that is, the rotation speed, to an initial value. In step S2, the temperature sensors 9.1 to 9. It is determined whether or not the minimum value Tmin among the detected values T1 to TN of N is higher than a predetermined temperature Te (for example, 17 ° C.), and when Tmin> Te, the refrigerant circuits 8.1 to 8. The defrosting operation is terminated by determining that the temperature of the N frost has been removed and the temperature has increased. If Tmin> Te, it is determined that there is a refrigerant circuit in which frost has not yet been removed, and the process proceeds to step S3.

  In step S3, the temperature sensors 9.1 to 9. It is determined whether or not the difference Tmax−Tmin between the maximum value Tmax and the minimum value Tmin among the detected values T1 to TN of N is higher than a predetermined temperature Ts (for example, 8 ° C.). Circuits 8.1-8. N is determined that the refrigerant in the same state flows in N and the possibility of generation of the refrigerant noise is low, and the process returns to step S2. It is judged that the refrigerants in different states flow in N and the possibility of generating refrigerant noise is high, and the rotational speed of the compressor 6 is lowered.

  In the refrigerant circuit in which the frost is sufficiently removed and the refrigerant exits in a gas state, the outlet temperature is high, whereas in the refrigerant circuit in which the frost is not yet removed and the refrigerant exits, the outlet temperature is low. Therefore, when the difference in the outlet temperature between the refrigerant circuits is large, the refrigerant of gas and liquid is supplied to the indoor heat exchanger 2 via the capillary tube 3 and causes a refrigerant sound. Therefore, when Tmax−Tmin> Ts, the number of rotations of the compressor 6 is lowered to a preset number of rotations to reduce the circulation amount of the refrigerant, thereby mitigating the generation of refrigerant noise. In step S5, it waits until Tmin> Te, and when Tmin> Te, the defrosting operation is stopped.

  FIG. 5 shows temperature sensors 8.1, 8,. FIG. 6 is a time chart illustrating the time change of the detected values T1, TN of N, and FIG. 6 is a time chart illustrating the time change of Tmax−Tmin. 5 and 6, when the rotation speed of the compressor 6 is set to the initial value (5000 rpm) and warm refrigerant is supplied to the outdoor heat exchanger 5, the refrigerant circuits 8.1 to 8. N's frost begins to melt. Since the cold water generated by melting of the frost flows down, the refrigerant circuit 8 is usually lower than the upper refrigerant circuit 8.1 due to the cold water. N often has a slower temperature rise.

  In FIG. 5, the outlet temperature T1 of the refrigerant circuit 8.1 first starts to rise, and the refrigerant circuit 8. A state is shown in which the outlet temperature TN of N starts to rise with a delay. When T1-TN = Tmax-Tmin exceeds a predetermined temperature (Ts = 8 ° C.), it is determined that refrigerant noise is generated, and the rotational speed of the compressor 6 is reduced from 5000 rpm to 4000 rpm. Thereby, the circulation amount of a refrigerant | coolant falls and a refrigerant | coolant sound is reduced. When TN = Tmin exceeds a predetermined temperature (Te = 17 ° C.), the defrosting operation is terminated.

[Embodiment 2]
FIG. 7 is a refrigerant circuit diagram showing a configuration of an air conditioner according to Embodiment 2 of the present invention, and is a diagram contrasted with FIG. With reference to FIG. 7, this air conditioner differs from the air conditioner of FIG. 1 in that the capillary tube 3 is replaced with an expansion valve 12. The opening degree of the expansion valve 12 is controlled by the control unit 11 shown in FIG. The expansion valve 12 adjusts the circulation amount of the refrigerant while reducing the pressure of the refrigerant.

  FIG. 8 is a flowchart showing the operation of the control unit 11 of the air conditioner, and is a diagram to be compared with FIG. 8 differs from FIG. 4 in that the opening degree of the expansion valve 12 is set to an initial value in step S1, and the opening degree of the expansion valve 12 instead of lowering the rotational speed of the compressor 6 in step S4. It is a point to lower. By lowering the opening degree of the expansion valve 12 (changing the opening degree by a predetermined value in the direction in which the expansion valve 12 is closed), it is possible to reduce the refrigerant circulation amount and reduce the refrigerant sound.

  FIG. 9 is a flowchart showing a modification of the second embodiment. In this modified example, in step S4, the opening degree of the expansion valve 12 is lowered and the rotational speed of the compressor 6 is lowered. As shown in FIG. 10, the rotation speed of the compressor 6 is lowered from A0 to A1, and the opening degree of the expansion valve 12 is lowered from B0 to B1.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a refrigerant circuit diagram which shows the structure of the air conditioner by Embodiment 1 of this invention. It is a figure which shows the structure of the outdoor heat exchanger shown in FIG. It is a block diagram which shows the structure of the air conditioner shown in FIG. It is a flowchart which shows the operation | movement at the time of defrosting of the control part shown in FIG. It is a time chart which illustrates the time change of the exit temperature of a refrigerant circuit at the time of defrosting. It is a time chart which illustrates the time change of the difference of the maximum value and the minimum value of the exit temperature of a refrigerant circuit at the time of defrosting. It is a refrigerant circuit diagram which shows the structure of the air conditioner by Embodiment 2 of this invention. It is a flowchart which shows the operation | movement at the time of defrosting of the outdoor heat exchanger shown in FIG. 10 is a flowchart illustrating a modification example of the second embodiment. It is a figure which shows the relationship between the rotation speed of the compressor in the air conditioner demonstrated in FIG. 9, and the opening degree of an expansion valve.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Indoor blower, 2 Indoor heat exchanger, 3 Capillary tube, 4 Outdoor blower, 5 Outdoor heat exchanger, 6 Compressor, 7 Four-way valve, 8.1-8. N refrigerant circuit, 9.1-9. N temperature sensor, 10 operation unit, 11 control unit, 12 expansion valve.

Claims (3)

At the time of heating, the refrigerant condensed in the indoor heat exchanger is decompressed by the decompression device and given to the outdoor heat exchanger, the refrigerant evaporated in the outdoor heat exchanger is compressed by the compressor and given to the indoor heat exchanger, During defrosting of the outdoor heat exchanger, the refrigerant condensed in the outdoor heat exchanger is depressurized by the decompression device and given to the indoor heat exchanger, and the refrigerant evaporated in the indoor heat exchanger is sent by the compressor In the air conditioner that compresses and applies to the outdoor heat exchanger,
The outdoor heat exchanger includes a plurality of refrigerant circuits connected in parallel,
The air conditioner
A plurality of temperature sensors for detecting temperatures of portions serving as refrigerant outlets during the defrosting of the plurality of refrigerant circuits, respectively;
When the difference between the maximum value and the minimum value of the detected values of the plurality of temperature sensors exceeds a predetermined temperature during defrosting of the outdoor heat exchanger, the drive rotational speed of the compressor is decreased. An air conditioner comprising a control unit. The decompression device is an expansion valve provided between the indoor heat exchanger and the outdoor heat exchanger,
The control unit further includes the expansion valve in response to a difference between a maximum value and a minimum value detected by the plurality of temperature sensors exceeding a predetermined temperature during defrosting of the outdoor heat exchanger. The air conditioner according to claim 1, wherein the air opening is controlled in a closing direction. At the time of heating, the refrigerant condensed in the indoor heat exchanger is decompressed by the expansion valve and given to the outdoor heat exchanger, the refrigerant evaporated in the outdoor heat exchanger is compressed by the compressor and given to the indoor heat exchanger, During defrosting of the outdoor heat exchanger, the refrigerant condensed in the outdoor heat exchanger is decompressed by the expansion valve and supplied to the indoor heat exchanger, and the refrigerant evaporated in the indoor heat exchanger is supplied by the compressor. In the air conditioner that compresses and applies to the outdoor heat exchanger,
The outdoor heat exchanger includes a plurality of refrigerant circuits connected in parallel,
The air conditioner
A plurality of temperature sensors for detecting temperatures of portions serving as refrigerant outlets during the defrosting of the plurality of refrigerant circuits, respectively;
When the difference between the maximum value and the minimum value of the detection values of the plurality of temperature sensors exceeds a predetermined temperature during defrosting of the outdoor heat exchanger, the opening degree of the expansion valve is closed. An air conditioner comprising a control unit for controlling.

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