JP2004144351A - Control method of multi-room type air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method of a multi-room type air conditioner for shifting up a suction temperature by a predetermined value in accordance with high pressure of a compressor, reducing the circulation of a refrigerant controlled on the basis of the combination of the compressors, and reducing the stop operation of a protecting circuit by the rise of high pressure. <P>SOLUTION: This multi-room type air conditioner having a refrigerant circuit configurated by connecting the plurality of compressors 3a, 3b, 3c connected in parallel, an outdoor unit comprising a four-way valve, an outdoor heat exchanger and an expansion valve, and a plurality of indoor units comprising indoor heat exchangers, is provided with a discharge pressure sensor 10 for detecting the pressure of a discharge-side confluence of the compressors 3a, 3b, 3c, and a suction temperature sensor 11 or a suction pressure sensor 11' for detecting a temperature or a pressure of a suction-side junction of the compressors 3a, 3b, 3c. The suction-side temperature or pressure of the compressors 3a, 3b, 3c is shifted up by the predetermined value with respect to the target temperature or pressure in normal operation, in accordance with the high pressure detected by the discharge pressure sensor 10, and the operation/stop of the compressors 3a, 3b, 3c are controlled on the basis of the temperature or pressure after the shifting. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control method of a multi-room air conditioner including an outdoor unit and a plurality of indoor units, and more specifically, shifts a suction temperature or a pressure higher by a predetermined value according to a high pressure of a compressor, The present invention relates to a control method for controlling the operation of a high-voltage protection circuit to be reduced.
[0002]
[Prior art]
In a building or the like having a larger number of rooms than before, a multi-room type (multi-type) air conditioner having a plurality of indoor units is used, and the operation status (number, load fluctuation) of the indoor units of the multi-room air conditioner is determined. Accordingly, the refrigerant circulation amount changes. As a method of controlling the refrigerant circulation amount during the cooling operation, there is a method of detecting the low pressure, the evaporation temperature, the degree of superheat, and the like, and adjusting the opening of the expansion valve (for example, see Patent Document 1).
In this method, the amount of refrigerant circulating in the compressor is controlled with the target of low pressure, evaporation temperature, and degree of superheat that can provide sufficient cooling capacity. However, when indoor and outdoor loads (air temperature, etc.) are high, low pressure pressure, evaporation Since the temperature and the degree of superheat increase, it is necessary to increase the amount of circulating refrigerant to maintain the cooling capacity (maintain the target low pressure, the evaporation temperature, and the degree of superheat).
[0003]
However, in the cooling operation under a high load condition, the refrigerant pressure in the refrigerant circuit increases, so if the refrigerant circulation amount is increased, the high pressure may exceed the design pressure, and the compression by the protection circuit (high pressure switch, etc.) may be performed. Frequent stoppage of the machine caused reliability problems.
[0004]
[Patent Document 1]
JP-A-7-120091 (page 6-8, FIG. 1-2).
[0005]
[Problems to be solved by the invention]
In the present invention, in view of the above problems, the suction temperature or the pressure is shifted to a predetermined value higher according to the high pressure of the compressor, and the refrigerant circulation amount controlled from the combination of the compressors is reduced to increase the high pressure. It is an object of the present invention to provide a control method of a multi-room air conditioner that controls so that a stop operation of a protection circuit due to a rise is reduced.
[0006]
[Means for Solving the Problems]
The present invention, in order to solve the above problems, a plurality of compressors each having a different capacity connected in parallel, a four-way valve, an outdoor heat exchanger, an outdoor unit equipped with an expansion valve, and an indoor heat exchanger. A multi-chamber air system comprising a plurality of indoor units each having a throttle mechanism connected to form a refrigerant circuit, and the operation / stop of each of the compressors is controlled in combination according to the operation state of the indoor units. In the harmonic machine,
A discharge pressure sensor for detecting a pressure at a discharge-side junction of each of the compressors; a suction temperature sensor for detecting a temperature at a suction-side junction of each of the compressors; or a suction pressure sensor for detecting the pressure. During operation, the temperature or pressure at the merging point on the suction side of each of the compressors is shifted by a predetermined value higher than the target temperature or pressure during normal operation according to the high pressure detected by the discharge pressure sensor. The operation / stop of each of the compressors is controlled according to the temperature or the pressure.
[0007]
Further, when the high pressure detected by the discharge pressure sensor reaches a predetermined value or more, the total operating capacity of the plurality of compressors is reduced.
[0008]
Each of the compressors is constituted by a constant speed compressor.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described as examples based on the accompanying drawings.
FIG. 1 is a configuration diagram of a refrigerant circuit of a multi-room air conditioner according to the present invention. In the figure, 1 is an outdoor unit installed outdoors, and 2a, 2b, and 2c are three indoor units connected in parallel, respectively.
[0010]
The outdoor unit 1 includes three compressors connected in parallel and having different capacities (capacities) of a constant speed type, for example, a small capacity compressor 3a, a medium capacity compressor 3b, and a large capacity compressor 3c. , The four-way valve 4, the outdoor heat exchanger 5, and the expansion valve 6 are connected to each other, and the indoor units 2a, 2b, 2c are connected to the electronic expansion valves 7a, 7b, 7c, respectively. The devices 8a, 8b and 8c are connected to each other.
[0011]
The outdoor unit 1 and the indoor units 2a, 2b, 2c are connected by a refrigerant pipe via a first connection part A1 and a second connection part A2 to form a refrigerant circuit, and the indoor units 2a, 2b, 2c The control unit 9 controls the compressors 3a, 3b, and 3c to switch the operation / stop according to load fluctuations such as the number of operating units.
[0012]
A discharge pressure sensor 10 for detecting the pressure (high pressure) of the discharged refrigerant is provided at the discharge-side junction a of each of the compressors 3a, 3b, 3c. A suction temperature sensor 11 for detecting the temperature of the suction refrigerant or a suction pressure sensor 11 'for detecting the pressure (low pressure) of the suction refrigerant is provided at the junction 3a, 3b, 3c on the suction side of each compressor. ing.
[0013]
In the above, during the cooling operation, as shown by solid arrows in FIG. 1, the gas refrigerant which has become high temperature and high pressure in the compressors 3a, 3b, 3c is sent to the outdoor heat exchanger 5, and the heat exchange with the outdoor air is performed. The gas refrigerant is cooled and condensed by the exchange, and becomes a high-temperature and high-pressure liquid refrigerant. The high-temperature and high-pressure liquid refrigerant is reduced in pressure in the expansion valve 6 to become a low-temperature and low-pressure liquid refrigerant. The low-temperature and low-pressure liquid refrigerant is sent to the indoor heat exchange units 2a, 2b and 2c, and cools the indoor air by exchanging heat with the indoor air. It becomes. At this time, the indoor heat exchangers 8a, 8b, 8c function as evaporators for evaporating the liquid refrigerant. The low-temperature and low-pressure gas refrigerant is returned to the compressors 3a, 3b and 3c via the four-way valve 4 to become a high-temperature and high-pressure gas refrigerant, and this process is repeated thereafter.
[0014]
During the heating operation, the four-way valve 4 is set so that the refrigerant passing through the compressors 3a, 3b, 3c flows to the indoor heat exchange units 2a, 2b, 2c, as indicated by the dashed arrows, and the indoor heat exchange unit 2a , 2b, and 2c function as condensers, and are the same as in the cooling operation except that the outdoor heat exchanger 5 functions as an evaporator.
[0015]
As shown in FIG. 2, when the three compressors 3a, 3b, 3c are combined, the operation / stop combination step is 0 (all stop) to 7 (all operation) according to the operation condition (load fluctuation). Up to eight combinations can be created.
Here, the refrigerant circulation amounts of the three compressors 3a, 3b, 3c are set as compressor 3a <compressor 3b <compressor 3c. Further, the refrigerant circulation amount in each step is defined as Step 1 <Step 2 <... <Step 7.
[0016]
In the above configuration, during the cooling operation, the target temperature or the target pressure on the suction side is set as follows according to the high pressure detected by the discharge pressure sensor 10 (FIG. 3).
When high pressure <PH1,
Shift amount of target temperature (pressure) 0 (0), T0 (P0) after shift
When PH1 ≦ high pressure <PH2,
Shift amount ΔT1 (ΔP1) of target temperature (pressure), T0 + ΔT1 after shift (P0 + ΔP1)
When PH2 <high pressure <PH3,
Shift amount ΔT2 (ΔP2) of target temperature (pressure), T0 + ΔT2 after shift (P0 + ΔP2)
However,
It is assumed that PH1 <PH2 <PH3, ΔT1 <ΔT2, and ΔP1 <ΔP2.
[0017]
The operation / stop of the compressors 3a, 3b, 3c is controlled according to the target temperature or the target pressure after the shift. When the temperature or pressure on the suction side increases, the amount of circulating refrigerant decreases, and the high pressure also decreases.
When the high pressure detected by the discharge pressure sensor 10 reaches PH3 or more, the operation / stopping steps of the compressors 3a, 3b, 3c are forcibly stepped down as shown in FIG. Thereby, the refrigerant circulation amount is reduced, and the high pressure is reduced.
[0018]
Next, in the above configuration, the control operation of the present invention will be described based on the control block diagram of FIG. 5 and the flowchart of FIG.
In FIG. 5, the control unit 9 includes a discharge pressure detection unit 9a for detecting the detection by the discharge pressure sensor 10 on the discharge side of the compressors 3a, 3b, 3c, a suction temperature sensor 11 on the suction side, or a suction pressure. A suction temperature / suction pressure detection unit 9b for detecting a temperature or pressure detected by the sensor 11 ', and a target temperature or a shift amount of the target pressure on the suction side in advance according to the high pressure detected by the discharge pressure sensor 10. The target temperature or pressure setting unit 9c to be stored and set, and the temperature or pressure of the suction temperature / suction pressure detection unit 9b and the shift of the target temperature or pressure setting unit 9c according to the high pressure of the discharge pressure detection unit 9a. And a compressor 3a, 3b, 3c based on a control signal of the comparison operation unit 9d during a cooling operation. With the drive unit 9e for controlling the drive, when the suction temperature or the pressure increases, the combination step of the operation / stop of the compressors 3a, 3b, 3c is controlled so as to decrease the refrigerant circulation amount, The high pressure is reduced so that the high pressure protection circuit is prevented from being stopped due to the high pressure rise.
[0019]
In the flowchart of FIG. 6, when the operation of the multi-room air conditioner is started, first, in step ST1, it is determined whether the operation is the cooling operation. If it is a cooling operation, it is determined in step ST2 whether the high pressure (discharge pressure) P is equal to or less than PH1, and if not, in step 3, the target suction temperature T0 or the pressure P0 is set and compared according to the shift amount. Then, in step 4, the combination of the compressors is controlled to the target step, and the process ends (ST5).
[0020]
Next, if the high pressure P is not equal to or less than PH1 in step ST2, it is determined in step ST6 whether the high pressure P is in the range of PH1 ≦ P <PH2. If it is within the range, the target suction temperature T0 + ΔT1 or the pressure (P0 + ΔP1) is set and compared in step ST7 according to the shift amount, and the combination of the compressors is controlled to the target step in step 4 in the same manner as described above. The process ends (ST5).
[0021]
If the high pressure P is not in the range of PH1 ≦ P <PH2 in step ST6, it is determined in step ST8 whether the high pressure P is in the range of PH2 ≦ P <PH3. If it is within the range, the target suction temperature T0 + ΔT2 or the pressure (P0 + ΔP2) is set and compared in step ST9 according to the shift amount, and the combination of the compressors is controlled to the target step in step 4 in the same manner as described above. The process ends (ST5).
[0022]
Further, if the high pressure P is not in the range of PH2 ≦ P <PH3 in step ST8, it is determined in step ST10 whether the high pressure P is equal to or higher than PH3. If this is the case, as shown in FIG. 4, control for forcibly stepping down the compressor step is performed in step ST10, and the process ends (ST5). If not, the process returns to step ST2 and the operation is repeated.
[0023]
As described above, the discharge pressure sensor 10 for detecting the pressure at the discharge side junction point a of each of the compressors 3a, 3b, 3c, and the temperature at the suction side junction point b of each of the compressors 3a, 3b, 3c. Alternatively, a suction temperature sensor 11 or a suction pressure sensor 11 'for detecting pressure is provided, respectively, and during a cooling operation, the suction side of each of the compressors 3a, 3b, 3c according to the high pressure P detected by the discharge pressure sensor 10. The temperature or pressure at the junction b is shifted by a predetermined value higher than the target temperature or pressure during normal operation, and the operation / stop of each of the compressors 3a, 3b, 3c is controlled in accordance with the shifted temperature or pressure. The configuration of the multi-chamber air conditioner, which reduces the amount of refrigerant circulation controlled by the combination of the compressors and thereby controls the stop operation of the protection circuit due to the high pressure rise, is reduced. The way.
[0024]
【The invention's effect】
As described above, according to the present invention, the suction temperature or the pressure is shifted to a predetermined value higher according to the high pressure of the compressor, and the refrigerant circulating amount controlled from the combination of the compressors is reduced to thereby increase the high pressure. A control method of a multi-room air conditioner that controls so as to reduce a stop operation of a protection circuit due to a rise is provided.
[Brief description of the drawings]
FIG. 1 is a refrigerant circuit diagram showing an embodiment of a control method of a multi-room air conditioner according to the present invention.
FIG. 2 is a combination table of operation / stop steps of each compressor in the present invention.
FIG. 3 is a table showing a relationship between a high pressure and a target temperature or pressure on a compressor suction side in the present invention.
FIG. 4 is a table for forcibly reducing the operation / stop step of the compressor in the present invention.
FIG. 5 is a control block diagram according to the present invention.
FIG. 6
[Explanation of symbols]
1 outdoor units 2a, 2b, 2c indoor units 3a, 3b, 3c compressor 4 four-way valve 5 outdoor heat exchanger 6 expansion valves 7a, 7b, 7c electronic expansion valves 8a, 8b, 8c indoor heat exchanger 9 control unit 9a discharge Pressure detection unit 9b Suction temperature / suction pressure detection unit 9c Target temperature or pressure setting unit 9d Comparison calculation unit 9e Drive unit 10 Discharge pressure sensor 11 Suction temperature sensor 11 'Suction pressure sensor

Claims (3)

A plurality of compressors each having a different capacity connected in parallel, a four-way valve, an outdoor heat exchanger, an outdoor unit having an expansion valve, and an indoor unit having an indoor heat exchanger and a throttle mechanism; To form a refrigerant circuit, and in accordance with the operation status of the indoor unit, in a multi-room air conditioner configured to control the operation / stop of each of the compressors in combination.
A discharge pressure sensor for detecting a pressure at a discharge-side junction of each of the compressors; a suction temperature sensor for detecting a temperature at a suction-side junction of each of the compressors; or a suction pressure sensor for detecting the pressure. During operation, the temperature or pressure at the merging point on the suction side of each of the compressors is shifted by a predetermined value higher than the target temperature or pressure during normal operation according to the high pressure detected by the discharge pressure sensor. A method for controlling a multi-room air conditioner, comprising controlling the operation / stop of each of the compressors according to temperature or pressure. The control of the multi-room air conditioner according to claim 1, wherein when the high pressure detected by the discharge pressure sensor reaches a predetermined value or more, the total operating capacity of the plurality of compressors is reduced. Method. 2. The control method for a multi-room air conditioner according to claim 1, wherein each of the compressors is a constant speed compressor.

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