JP5766061B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner including a plurality of compressors, and more particularly to an air conditioner that controls a plurality of compressors according to an air conditioning load.

  As a conventional air conditioner, for example, there is one that includes two compressors driven by an inverter circuit to simplify the circuit configuration and reduce the shape (for example, refer to Patent Document 1).

WO2005 / 124988 (5th page, FIG. 3)

  However, although the above-described conventional air conditioner has two compressors on the refrigerant circuit, the power consumption per compressor same work and the compressor efficiency are optimized for the air conditioning load. It was not a thing.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain an air conditioner capable of optimizing the compressor efficiency with respect to the air conditioning load.

An air conditioner according to the present invention includes an outdoor unit having a plurality of compressors, and an indoor unit that includes a room temperature sensor that detects a room temperature and forms a refrigerant circuit with the outdoor unit. in the time of operation start of the air conditioning, and starts the operation of the preset one compressor of the plurality of compressors, the operating air-conditioning load based on the temperature difference between the set temperature and the detected temperature of room temperature sensor previously When the efficiency of all compressors including the compressor becomes higher than the efficiency of the compressor, the remaining compressor starts operating when the air conditioning load becomes higher, including the compressor that has been operated first Calculate the average efficiency of each compressor based on the discharge refrigerant flow rate for the air conditioning load in all compressors, and calculate the number of rotations corresponding to the efficiency of each compressor when the average efficiency is obtained. A control circuit that operates the machine at each speed Those were.

  According to the present invention, when the air conditioning load based on the temperature difference between the detected temperature of the room temperature sensor and the set temperature becomes a certain level or more due to the preset compressor operation, the remaining compressors are started to operate. , Calculate the average efficiency for the air conditioning load due to the operation of all the compressors including the compressor that was operated earlier, and calculate the rotation speed corresponding to the efficiency of each compressor when the average efficiency was obtained, Each compressor is operated at each speed. As a result, the efficiency of each compressor can be optimized with respect to the air conditioning load. Therefore, the total current value during operation of all the compressors can be suppressed, and the power consumption of the air conditioner can be reduced. be able to.

It is a refrigerant circuit figure at the time of air_conditionaing | cooling operation which shows the air conditioner which concerns on embodiment. It is a refrigerant circuit figure at the time of the heating operation of the air conditioner shown in FIG. It is a curve figure which shows the correlation of the air-conditioning load and compressor efficiency in the air conditioner of embodiment. It is a flowchart which shows control of the compressor of the air conditioner which concerns on embodiment.

FIG. 1 is a refrigerant circuit diagram during cooling operation showing the air conditioner according to the embodiment of the present invention, and FIG. 2 is a refrigerant circuit diagram during heating operation of the air conditioner shown in FIG.
The air conditioner of the present embodiment includes an outdoor unit 100 and an indoor unit 110 connected to the outdoor unit 100 via a refrigerant pipe. The outdoor unit 100 includes, for example, two compressors 101 and 102, a four-way valve 103, an outdoor heat exchanger 104, an expansion valve 105, stop valves 106 and 107, a circuit board 108, an outdoor fan, and a circuit board 108. Has been. The indoor unit 110 includes an indoor heat exchanger 111, a room temperature sensor such as a room temperature thermistor 112, an indoor fan (not shown), and the like.

  The two compressors 101 and 102 have a discharge side connected to the inlet of the four-way valve 103 via one refrigerant pipe, and a suction side connected to the outlet of the four-way valve 103 via one refrigerant pipe. An outdoor heat exchanger 104, an expansion valve 105, a stop valve 106, an indoor heat exchanger 111, and a stop valve 107 are sequentially connected by refrigerant piping between one inlet / outlet of the four-way valve 103 and the other inlet / outlet. ing.

  The four-way valve 103 is a valve for switching between a cooling cycle and a heating cycle. When the cooling operation is switched by the four-way valve 103, the outdoor heat exchanger 104 operates as a condenser and the indoor heat exchanger 111 operates as an evaporator. Further, when switched to the heating operation, the outdoor heat exchanger 104 operates as an evaporator and the indoor heat exchanger 111 operates as a condenser. The expansion valve 105 expands the flowing liquid refrigerant according to the adjustment of the throttle amount, and lowers the pressure and temperature of the refrigerant. The liquid refrigerant flows through the stop valve 106, and the gas refrigerant flows through the stop valve 107. These stop valves 106 and 107 are closed when the product is shipped or moved, and the valves are opened after connection with the indoor unit 110.

  The room temperature thermistor 112 detects the temperature of the room in which the indoor unit 110 is installed, and outputs a signal corresponding to the detected temperature to the circuit board 108. The circuit board 108 includes a converter circuit that converts AC voltage into DC, two inverter circuits that drive the compressors 101 and 102, an A / D converter that converts a signal from the room temperature thermistor 112 into digital, and two inverter circuits The control circuit 108a for driving and controlling the expansion valve 105, the outdoor blower fan, and the like, the memory 108b, and the like are mounted on the substrate.

  In the air conditioner configured as described above, the flow of the refrigerant during the cooling operation flows as indicated by the arrows shown in FIG. The refrigerant is compressed by the two compressors 101 and 102 to become a high-temperature and high-pressure gas refrigerant, and flows into the outdoor heat exchanger 104 through the four-way valve 103. Then, the gas refrigerant exchanges heat (radiates heat) with the outdoor air sent by the outdoor fan in the outdoor heat exchanger 104 to become a high-pressure liquid refrigerant. Thereafter, the liquid refrigerant is expanded to a predetermined pressure by the expansion valve 105 to become a low-pressure gas-liquid two-phase refrigerant, and flows into the indoor heat exchanger 111 through the stop valve 106. The gas-liquid two-phase refrigerant that has flowed into the indoor heat exchanger 111 exchanges heat (absorbs heat) with the indoor air sent by the indoor fan and becomes a low-temperature and low-pressure gas refrigerant, and is compressed through the stop valve 107 and the four-way valve 103. Return to the machines 101 and 102.

  Further, the flow of the refrigerant during the heating operation flows as shown by the arrows in FIG. As described above, the refrigerant is compressed by the two compressors 101 and 102 to become a high-temperature and high-pressure gas refrigerant, and flows into the indoor heat exchanger 111 through the four-way valve 103 and the stop valve 107. The gas refrigerant exchanges heat (radiates heat) with indoor air sent by the indoor fan in the indoor heat exchanger 111 to become a high-pressure liquid refrigerant. Thereafter, the liquid refrigerant passes through the stop valve 106, is expanded to a predetermined pressure by the expansion valve 105, becomes a low-pressure gas-liquid two-phase refrigerant, and flows into the outdoor heat exchanger 104. The gas-liquid two-phase refrigerant that has flowed into the outdoor heat exchanger 104 exchanges heat (absorbs heat) with the outdoor air sent by the outdoor blower fan to become a low-temperature and low-pressure gas refrigerant, and the compressors 101 and 102 via the four-way valve 103. Return to.

  FIG. 3 is a curve diagram showing the correlation between the air conditioning load and the compressor efficiency in the air conditioner of the embodiment. The curve diagram shows the performance data of the compressor. For example, when two small-capacity compressors are mounted on the outdoor unit 100, the correlation between the air conditioning load and the compressor efficiency at the time of operation of one unit is shown. It shows the correlation between air conditioning load and compressor efficiency during stand-alone operation, and shows the correlation between air-conditioning load and compressor efficiency during single-unit operation when two large-capacity compressors are installed. The correlation between air conditioning load and compressor efficiency during stand operation is shown. The small capacity compressor is a compressor having a small stroke volume (the amount of refrigerant sent to the refrigerant circuit by one rotation of the compressor), and the large capacity compressor is a compressor having a large stroke volume. That is.

  In general, as shown in FIG. 3, the small capacity compressor has a lower limit of the load that can be air conditioned than the large capacity compressor, but is more efficient than the large capacity compressor in the range of the load that can be air conditioned. This is because there are inevitably differences in processing variations and mechanical loss of the compressor. Since the compressor has an efficiency characteristic that is convex upward at a certain rotation speed, the efficiency is decreasing when the rotation speed is exceeded. However, when two compressors are operated, the efficiency is higher than when one compressor is operated from a certain rotational speed. This is because the peak inherent to a higher rotational speed moves as the rotational speed per vehicle decreases.

The following two points can be seen from FIG.
(1) Once the air conditioning load area (mainly the upper limit) to be supported as an air conditioner is determined, the compressor can be determined accordingly, but at that time, by configuring multiple smaller compressors It is possible to raise the overall efficiency of the compressor in the area of the air conditioning load to be handled.
(2) After configuring the compressor with a plurality of units, for example, in a region where the air conditioning load is small, the compressor is operated with one unit, and when the air conditioning load exceeds a certain level, the number of operating compressors is increased. Since the average efficiency increases by lowering the number of revolutions per unit, the compressor efficiency can be effectively increased.

  In the present embodiment, when the operation of the air conditioner is started, when, for example, the preset compressor 101 of the two compressors 101 and 102 is operated and the air conditioning load becomes a certain level or more, that is, When the efficiency of the first compressor 101 decreases, the second compressor 102 is also driven to calculate the average efficiency that is highest for the air conditioning load due to the operation of the two compressors 101 and 102, And it controls by the rotation speed corresponding to the efficiency of each compressor 101,102 when the average efficiency is obtained, respectively.

In order to implement the above-described control, the following control parameters are used, and data obtained from the control parameters is stored in the memory 108b in advance. Note that the compressors 101 and 102 mounted on the outdoor unit 100 in the present embodiment will be described assuming that a small-capacity compressor having a small stroke volume is used as an example.
R1 Rotation speed of compressor 101 R2 Rotation speed of compressor 102 S1 Stroke volume of compressor 101 S2 Stroke volume of compressor 102 V1 Discharge refrigerant flow rate of compressor 101 V2 Discharge refrigerant flow rate of compressor 102 C1 Rotation of compressor 101 Efficiency corresponding to number R1 C2 Efficiency corresponding to rotation speed R2 of compressor 102 N Number of operating compressors Q Air conditioning load T1 Room setting room temperature by remote control setting T2 Room temperature detected by room temperature thermistor 112 T3 Air conditioning capacity is air conditioning Temperature threshold T4 indicating that the air conditioning capacity is excessive with respect to the air conditioning load ΔT T1 and T2 temperature difference

The parameters described above have the following relationship.
(1) Q∝ (V1 + V2) The air conditioning load Q is proportional to the discharge refrigerant flow rate V1 + V2 of the compressors 101 and 102, and is proportional to the discharge refrigerant flow rate V1 of the compressor 101 only.
(2) V1 = S1 × R1 The discharge refrigerant flow rate V1 of the compressor 101 is the product of the stroke volume S1 and the rotational speed R1.
(3) V2 = S2 × R2 The refrigerant flow rate V2 discharged from the compressor 102 is the product of the stroke volume S2 and the rotational speed R2.
(4) C1 = F (R1) The efficiency C1 of the compressor 101 is a function of the rotational speed R1.
(5) C2 = F (R2) The efficiency C2 of the compressor 102 is a function of the rotational speed R2.
(6) ((C1 + C2) / N) = F (V1 + V2) N is the number of compressors, and C1 and C2 are calculated from equations (4) and (5).

  In the memory 108b described above, information on the compressor 101 that operates first at the start of operation is stored as data. Based on the stroke volumes S1 and S2 of the compressors 101 and 102 and the above (4) and (5). Stored is the correlation data of the rotation speeds R1 and R2 and the efficiency C1 and C2 for each of the created compressors 101 and 102. In addition, the memory 108b has performance data including a correlation curve of air conditioning load / compressor efficiency when operating one small capacity compressor and a correlation curve of air conditioning load / compressor efficiency when operating two small capacity compressors. Is stored as The memory 108b stores the equations (1) to (5) and the equation (6).

Next, the operation will be described based on the flowchart shown in FIG.
The control circuit 108a on the circuit board 108 reads the information of the compressor 101 to be activated first from the memory 108b (S2) when the operation start command by the operation of the remote controller is input via the indoor unit 110 (S1). . Next, the control circuit 108a reads from the memory 108b a correlation curve of the air conditioning load / compressor efficiency when one small capacity compressor is operating, and a correlation curve of the air conditioning load / compressor efficiency when the two small capacity compressors are operating. Is read as performance data (S3).

  Thereafter, the control circuit 108a activates the compressor 101 based on the previously read information (S4). Thereafter, based on the performance data described above, the compressor 101 is operated when the air conditioning load has not reached a certain level, and is operated by the two compressors 101 and 102 when the air conditioning load has exceeded a certain level. .

  The control circuit 108a recognizes the optimum efficiency of the compressor 101 with respect to the current air conditioning load Q from the performance data read in S3, and the compressor whose rotational speed R1 corresponding to the efficiency is stored in the memory 108b. A search is performed from the correlation data between the rotation speed R1 of 101 and the efficiency. Then, the control circuit 108a controls the compressor 101 to operate at the rotation speed R1, and increases the discharge refrigerant flow rate V1.

  At this time, the control circuit 108a calculates the discharge refrigerant flow rate V1 based on the rotation speed R1 of the compressor 101 (see equation (2)), recognizes the air conditioning state, and determines the discharge refrigerant flow rate V1 and the air conditioning state. The data is written in the memory 108b in association (S5). The air conditioning state is a temperature difference ΔT between the indoor set temperature T1 set by the remote controller and the room temperature T2 detected by the room temperature thermistor 112. The temperature difference ΔT during the cooling operation is ΔT = T2−T1, and the temperature difference ΔT during the heating operation is ΔT = T1−T2.

  And the control circuit 108a confirms whether the discharge refrigerant | coolant flow volume V1 of the compressor 101 is enough from the air-conditioning state written in the memory 108b (S6). When ΔT ≧ T3, the control circuit 108a increases the discharged refrigerant flow rate V1 on the assumption that the air conditioning capacity is insufficient with respect to the air conditioning load. When T4 ≦ ΔT <T3, the control circuit 108a maintains the current discharged refrigerant flow rate V1, and ΔT < At T4, the discharged refrigerant flow rate V1 is decreased on the assumption that the air conditioning capability is excessive with respect to the air conditioning load. In addition, since the change of the discharge refrigerant | coolant flow volume V1 of the compressor 101 tends to cause a hunting in refrigeration cycle control, it is desirable to provide an appropriate difference between T3 and T4.

  The control circuit 108a calculates the rotational speed R1 from the discharge refrigerant flow rate V1 of the compressor 101 determined in S6 (S7). For example, the control circuit 108a maintains the current rotational speed R1 when maintaining the current discharged refrigerant flow rate V1, and rotates from the discharged refrigerant flow rate V1 using the equation (2) when increasing or decreasing the discharged refrigerant flow rate V1. The number R1 is calculated. Then, the control circuit 108a performs control so that the compressor 101 is operated at the calculated rotation speed R1 (S8). At this time, the control circuit 108a recognizes the current air conditioning load Q that is proportional to the discharge refrigerant flow rate V1 of the compressor 101 determined in S6, and returns to S5 when the air conditioning load Q is not equal to or greater than a certain value, and the operation described above. repeat. The control circuit 108a also activates the second compressor 102 when the air conditioning load Q recognized from the discharge refrigerant flow rate V1 becomes equal to or greater than a certain level.

  When the second compressor 102 is started, the control circuit 108a recognizes the highest efficiency (average efficiency) for the current air conditioning load Q from the above performance data. The average efficiency is a value calculated by using the equation (6) for the efficiency C1, C2 of the compressors 101, 102 obtained from the equations (4), (5). Then, the control circuit 108a rotates the rotation speeds R1 and R2 corresponding to the efficiency C1 and C2 of the compressors 101 and 102 when the average efficiency is obtained, for each compressor 101 and 102 stored in the memory 108b. Search is performed from the correlation data of the numbers R1 and R2 and the efficiencies C1 and C2. Next, the control circuit 108a controls the compressors 101 and 102 to operate at the rotation speeds R1 and R2, and increases the discharged refrigerant flow rate V1 + V2 (S4).

  At this time, the control circuit 108a calculates the discharge refrigerant flow rate V1 based on the rotation speed R1 of the compressor 101, and calculates the discharge refrigerant flow rate V2 based on the rotation speed R2 of the compressor 102 (formula (2)). , (3)), the total discharged refrigerant flow rate V1 + V2 is written in the memory 108b. In addition, the control circuit 108a recognizes the air-conditioning state in the same manner as described above and writes it in the memory 108b in association with the discharged refrigerant flow rate V1 + V2 (S5).

  Then, the control circuit 108a checks whether or not the discharged refrigerant flow rate V1 + V2 discharged from the compressors 101 and 102 is sufficient from the air conditioning state written in the memory 108b (S6). As described above, the control circuit 108a increases the discharge refrigerant flow rate V1 + V2 when ΔT ≧ T3, maintains the current discharge refrigerant flow rate V1 + V2 when T4 ≦ ΔT <T3, and decreases the discharge refrigerant flow rate V1 + V2 when ΔT <T4. Let In addition, since the change of the refrigerant flow rate V1 + V2 discharged from the compressors 101 and 102 is likely to cause hunting in the refrigeration cycle control, it is desirable to provide an appropriate difference between T3 and T4. Further, when a predetermined time or more has elapsed, it may be determined whether or not to increase or decrease the discharge refrigerant flow rate V1 + V2 from the discharge refrigerant flow rate V1 + V2 and ΔT written in the memory 108b.

  The control circuit 108a calculates the rotation speed R1 from the discharge refrigerant flow rate V1 of the compressor 101 determined in S6, and calculates the rotation speed R2 from the discharge refrigerant flow rate V2 of the compressor 102 (S7). For example, the control circuit 108a maintains the current rotation speeds R1 and R2 of the compressors 101 and 102 when maintaining the current discharge refrigerant flow rate V1 + V2. Further, when increasing or decreasing the discharge refrigerant flow rate V1 + V2, the control circuit 108a calculates the rotational speeds R1 and R2 of the compressors 101 and 102 from the discharge refrigerant flow rates V1 and V2 using the equations (2) and (3). To do. Then, the control circuit 108a operates the compressor 101 at the calculated rotational speed R1, and operates the compressor 102 at the rotational speed R2 (S8). At this time, the control circuit 108a recognizes the current air conditioning load Q that is proportional to the discharge refrigerant flow rate V1 + V2 of the compressor 101 determined in S6. repeat.

  As described above, according to the present embodiment, when the air conditioning load based on the temperature difference between the detected temperature of the room temperature thermistor 112 and the set temperature becomes a certain level or more due to the operation of the compressor 101 set in advance, The first compressor 102 is also operated to calculate the average efficiency that is highest for the air conditioning load due to the operation of the two compressors 101 and 102, and the efficiency C1 of each compressor when the average efficiency is obtained, The rotation speeds R1 and R2 corresponding to C2 are calculated, and the compressors 101 and 102 are operated at the respective rotation speeds R1 and R2. As a result, the efficiency of the compressors 101 and 102 can be optimized with respect to the air conditioning load Q. Therefore, the total current value during operation of the compressors 101 and 102 can be suppressed. Reduction in power consumption can be achieved.

  In the embodiment, the compressors 101 and 102 are described as the same small capacity compressor, but may be described as a large capacity compressor. Further, the compressor 101 may be described as a small capacity compressor, and the compressor 102 may be described as a large capacity compressor.

  100 outdoor unit, 101, 102 compressor, 103 four-way valve, 104 outdoor heat exchanger, 105 expansion valve, 106, 107 stop valve, 108 circuit board, 108a control circuit, 108b memory, 110 indoor unit, 111 indoor heat exchanger 112 Room temperature thermistor.

Claims (3)

In an air conditioner comprising an outdoor unit having a plurality of compressors, an indoor unit having a room temperature sensor for detecting the indoor temperature, and an indoor unit that constitutes a refrigerant circuit with the outdoor unit,
In operation start of the air conditioning, and starts the operation of the preset one compressor of the plurality of compressors, air-conditioning load based on the temperature difference between the detected temperature and the set temperature of the room sensor is operated earlier When the efficiency of all the compressors including the compressor becomes higher than the efficiency of the compressor, the operation of the remaining compressors starts when the air-conditioning load becomes higher, and all the compressors that have been operated earlier Calculate the average efficiency of each compressor based on the flow rate of refrigerant discharged to the air conditioning load in the compressor, and calculate the number of rotations corresponding to the efficiency of each compressor when the average efficiency is obtained. An air conditioner comprising a control circuit for operating the machine at each rotation speed.   The control circuit has data indicating the relationship between the air conditioning load and the efficiency of the compressor in advance, and recognizes the efficiency of the compressor with respect to the air conditioning load from the data when operating a preset compressor. 2. The air conditioner according to claim 1, wherein the compressor is operated at a rotation speed set corresponding to the efficiency.   The air conditioner according to claim 1 or 2, wherein the plurality of compressors have the same capacity or different capacities.

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