JP4063041B2 - Control method of multi-room air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control method for a multi-room air conditioner composed of an outdoor unit and a plurality of indoor units. More specifically, according to the high pressure of the compressor, the intake temperature or pressure is shifted higher by a predetermined value, 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 buildings that have a larger number of rooms than before, multi-room type air conditioners with multiple indoor units are used, and the operating status (number of units, load fluctuations) of indoor units of multi-room air conditioners is used. 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 pressure, the evaporation temperature, the degree of superheat, etc., and adjusting the opening of the expansion valve (for example, refer to Patent Document 1).
This controls the amount of refrigerant circulating in the compressor with the goal of low pressure, evaporating temperature, superheat, etc. that can provide sufficient cooling capacity. However, when the indoor and outdoor loads (air temperature, etc.) are high, the low pressure, evaporating Since the temperature and the degree of superheat rise, it was necessary to increase the amount of refrigerant circulation in order to maintain the cooling capacity (maintain the target low pressure, evaporation temperature, and degree of superheat).
[0003]
However, in cooling operation under high load conditions, the refrigerant pressure in the refrigerant circuit rises, so if the refrigerant circulation rate is increased, the high pressure may exceed the design pressure, and compression by a protection circuit (such as a high pressure switch) The machine stopped frequently and there was a problem in reliability.
[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-described problems, the intake temperature or pressure is shifted higher by a predetermined value in accordance with the high pressure of the compressor, and the refrigerant circulation amount controlled from the combination of the compressors is reduced. It is an object of the present invention to provide a control method for a multi-room air conditioner that controls a stop operation of a protection circuit due to ascent to be reduced.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a plurality of compressors connected in parallel and having different capacities, a four-way valve, an outdoor heat exchanger, an outdoor unit including an expansion valve, and an indoor heat exchanger. A multi-chamber air formed by connecting a plurality of indoor units having a throttle mechanism to form a refrigerant circuit, and controlling the operation / stop of each compressor in combination according to the operation status of the indoor units. In the harmony machine,
A discharge pressure sensor for detecting the pressure at the discharge side merging point of each compressor, a suction temperature sensor for detecting the temperature of the suction side merging point of each compressor, or a suction pressure sensor for detecting pressure are provided, respectively. During operation, the temperature or pressure at the suction side confluence of each compressor is shifted higher by a predetermined value than the target temperature or pressure during normal operation according to the high pressure detected by the discharge pressure sensor, and after this shift The operation / stop of each compressor is controlled according to the temperature or 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]
Further, each of the compressors is constituted by a constant speed type compressor.
[0009]
DETAILED DESCRIPTION OF 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, 2c are three indoor units connected in parallel.
[0010]
The outdoor unit 1 includes three constant speed compressors connected in parallel, each having a different capacity (capacity), such as 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, and 2c are exchanged with the electronic expansion valves 7a, 7b, and 7c, respectively, for indoor heat exchange. Units 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 controller 9 controls the compressors 3a, 3b, and 3c to be switched in combination with each other in accordance with 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 confluence point a of each of the compressors 3a, 3b, 3c. Further, 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 suction side confluence point 3a, 3b, 3c of each compressor. ing.
[0013]
In the above operation, during the cooling operation, as indicated by solid arrows in FIG. 1, the high-temperature and high-pressure gas refrigerant in the compressors 3a, 3b, and 3c is sent to the outdoor heat exchanger 5 to generate heat between the outdoor air and the outdoor air. The gas refrigerant is cooled and condensed by the exchange, and becomes a high-temperature and high-pressure liquid refrigerant. This high-temperature and high-pressure liquid refrigerant is decompressed by the expansion valve 6 to become a low-temperature and low-pressure liquid refrigerant. This 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 heat exchange with the indoor air, and also heats and evaporates itself to cool and cool the low-temperature and low-pressure gas refrigerant. It becomes. At this time, the indoor heat exchangers 8a, 8b, 8c function as an evaporator for evaporating the liquid refrigerant. This 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]
Further, during the heating operation, as indicated by broken line arrows, the four-way valve 4 is set so that the refrigerant having passed through the compressors 3a, 3b, 3c flows into the indoor heat exchange units 2a, 2b, 2c, and the indoor heat exchange unit 2a , 2b, 2c function as a condenser, and the outdoor heat exchanger 5 functions as an evaporator.
[0015]
As shown in FIG. 2, when the three compressors 3a, 3b, and 3c are combined, the operation / stop combination step is 0 (all stopped) to 7 (all operated) depending on the operation status (load fluctuation). Up to 8 combinations can be created.
Here, the refrigerant circulation amount of the three compressors 3a, 3b, 3c is set such that compressor 3a <compressor 3b <compressor 3c. Further, the refrigerant circulation amount in each step is set as step 1 <step 2 <.
[0016]
In the above-described configuration, the target temperature or target pressure on the suction side is set as follows according to the high pressure detected by the discharge pressure sensor 10 during the cooling operation (FIG. 3).
When high pressure <PH1,
Target temperature (pressure) shift amount 0 (0), after shift T0 (P0)
When PH1≤high pressure <PH2,
Target temperature (pressure) shift amount ΔT1 (ΔP1), after shift T0 + ΔT1 (P0 + ΔP1)
When PH2 <high pressure <PH3,
Target temperature (pressure) shift amount ΔT2 (ΔP2), after shift T0 + ΔT2 (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 refrigerant circulation rate decreases and the high pressure also decreases.
When the high pressure detected by the discharge pressure sensor 10 reaches PH3 or more, the operation / stop step of the compressors 3a, 3b, 3c is forcibly stepped down as shown in FIG. Thereby, the refrigerant circulation amount is reduced and the high pressure is lowered.
[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 that detects the detection by the discharge pressure sensor 10 on the discharge side of the compressors 3a, 3b, and 3c, a suction temperature sensor 11 on the suction side, or a suction pressure. According to the suction temperature / suction pressure detection unit 9b that detects the temperature or pressure detected by the sensor 11 ′ and the high pressure detected by the discharge pressure sensor 10, the target temperature on the suction side or the shift amount of the target pressure is determined in advance. The target temperature or pressure setting unit 9c to store 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 A comparison operation unit 9d for calculating the target temperature or pressure on the suction side after the shift, and driving the compressors 3a, 3b, 3c by the control signal of the comparison operation unit 9d during cooling operation And the drive unit 9e to be controlled. When the temperature or pressure rises, the combination step of operation / stop of the compressors 3a, 3b, 3c is controlled so as to reduce the refrigerant circulation rate, the high pressure is lowered, and the high pressure protection circuit is stopped due to the high pressure rise. Control to avoid.
[0019]
In the flowchart of FIG. 6, when the operation of the multi-room air conditioner starts, first, it is determined whether or not the cooling operation is performed in step ST1. If it is a cooling operation, it is determined in step ST2 whether the high pressure (discharge pressure) P is less than PH1, and if so, in step 3, the target suction temperature T0 or pressure P0 is set and compared according to the shift amount. In step 4, the compressor combination is controlled to the target step, and the process ends (ST5).
[0020]
Next, if the high pressure P is not less than PH1 in step ST2, it is determined in step ST6 whether the high pressure P is within the range of PH1 ≦ P <PH2. If it is within the range, the target intake temperature T0 + ΔT1 or the pressure (P0 + ΔP1) is set and compared according to the shift amount in step ST7, and the compressor combination is controlled to the target step in step 4 as described above. End (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 intake temperature T0 + ΔT2 or the pressure (P0 + ΔP2) is set and compared in step ST9 according to the shift amount, and the compressor combination is controlled to the target step in step 4 as described above. End (ST5).
[0022]
Furthermore, 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 greater than PH3. If this is the case, as shown in FIG. 4 in step ST10, the compressor step is forcibly stepped down and the process ends (ST5). If not, the operation returns to step ST2 and is repeated.
[0023]
As described above, the discharge pressure sensor 10 for detecting the pressure at the discharge side confluence point a of the compressors 3a, 3b, 3c and the temperature of the suction side confluence point b 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 the suction side of each of the compressors 3a, 3b, 3c according to the high pressure P detected by the discharge pressure sensor 10 during cooling operation. The temperature or pressure at the junction b is shifted higher by a predetermined value than the target temperature or pressure during normal operation, and the operation / stop of each of the compressors 3a, 3b, 3c is controlled according to the temperature or pressure after this shift. With this configuration, the control method of the multi-chamber air conditioner that controls the stop operation of the protection circuit due to the high pressure rise to be reduced by reducing the refrigerant circulation amount controlled from the combination of the compressors. .
[0024]
【The invention's effect】
As described above, according to the present invention, the suction temperature or pressure is shifted higher by a predetermined value in accordance with the high pressure of the compressor, and the amount of refrigerant circulation controlled by the combination of the compressors is reduced. This is a control method for a multi-room air conditioner that controls to reduce the stop operation of the protection circuit due to ascent.
[Brief description of the drawings]
FIG. 1 is a refrigerant circuit diagram showing an embodiment of a control method for 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 the relationship between the high pressure and the target temperature or pressure on the compressor suction side in the present invention.
FIG. 4 is a table for forcibly reducing compressor operation / stop steps according to the present invention.
FIG. 5 is a control block diagram in the present invention.
[Fig. 6]
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outdoor unit 2a, 2b, 2c Indoor unit 3a, 3b, 3c Compressor 4 Four way valve 5 Outdoor heat exchanger 6 Expansion valve 7a, 7b, 7c Electronic expansion valve 8a, 8b, 8c Indoor heat exchanger 9 Control part 9a Discharge Pressure detecting unit 9b Suction temperature / suction pressure detecting unit 9c Target temperature or pressure setting unit 9d Comparison calculating unit 9e Drive unit 10 Discharge pressure sensor 11 Suction temperature sensor 11 'Suction pressure sensor

Claims (3)

A plurality of compressors having different capacities connected in parallel, a four-way valve, an outdoor heat exchanger, an outdoor unit having an expansion valve, and a plurality of indoor units having an indoor heat exchanger and a throttle mechanism; In a multi-room air conditioner that is configured by connecting a refrigerant circuit to control the operation / stop of each compressor in combination according to the operation status of the indoor unit,
A discharge pressure sensor for detecting the pressure at the discharge side merging point of each compressor, a suction temperature sensor for detecting the temperature of the suction side merging point of each compressor, or a suction pressure sensor for detecting pressure are provided, respectively. During operation, the temperature or pressure at the suction side confluence of each compressor is shifted higher by a predetermined value than the target temperature or pressure during normal operation according to the high pressure detected by the discharge pressure sensor, and after this shift A control method for a multi-chamber air conditioner, wherein operation / stop of each compressor is controlled according to temperature or pressure. 2. The control of a 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 lowered. Method. 2. The method of controlling a multi-room air conditioner according to claim 1, wherein each of the compressors is a constant speed type compressor.

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