WO2017221396A1

WO2017221396A1 - Air conditioner

Info

Publication number: WO2017221396A1
Application number: PCT/JP2016/068794
Authority: WO
Inventors: 邦弘乾
Original assignee: 三菱電機株式会社
Priority date: 2016-06-24
Filing date: 2016-06-24
Publication date: 2017-12-28
Also published as: JPWO2017221396A1; JP6641478B2

Abstract

An air conditioner according to the present invention is provided with: a refrigeration cycle circuit having a compressor, a condenser, a plurality of electronic expansion valves, and a plurality of evaporators; and a control device for controlling the opening degree of each of the electronic expansion valves. The plurality of electronic expansion valves and the plurality of evaporators are disposed such that one electronic expansion valve and one evaporator connected in series together constitute one group, and a plurality of such groups are connected in parallel between the condenser and the compressor. The control device has: a reference opening degree determination unit for determining a reference valve opening degree; a storage unit for storing, for each of the electronic expansion valves, a value used in correcting the opening degree of the electronic expansion valves; and a control unit for controlling each of the electronic expansion valves to an opening degree such that the reference valve opening degree is corrected using the value stored in the storage unit.

Description

Air conditioner

The present invention relates to a so-called multi-type air conditioner in which a plurality of evaporators are connected in parallel between a condenser and a compressor.

The air conditioner includes a refrigeration cycle circuit in which a compressor, a condenser, an expansion mechanism, and an evaporator are sequentially connected. Moreover, what employ | adopted the electronic expansion valve which can change an opening degree arbitrarily is proposed as the expansion mechanism of the refrigerating cycle circuit in the conventional air conditioner.

The electronic expansion valve is configured to adjust the opening by moving the valve body with, for example, a pulse motor. That is, when a command value such as a pulse value is input from the control device, the electronic expansion valve has an opening corresponding to the command value. For example, the electronic expansion valve has a larger opening as the pulse value that is the command value is larger.

If the opening degree at which the refrigerant begins to flow is defined as the “opening opening degree”, the opening degree differs for each electronic expansion valve due to dimensional errors and assembly errors of parts. That is, when the opening degree of a plurality of electronic expansion valves is controlled to the opening degree that theoretically becomes the opening degree, the refrigerant flows in some electronic expansion valves, but the refrigerant flows in some other electronic expansion valves. Will not flow.

Therefore, a conventional air conditioner having only one electronic expansion valve is proposed to detect the actual opening degree of the electronic expansion valve and accurately set the opening position of the electronic expansion valve. (See Patent Document 1).

Japanese Patent Laid-Open No. 9-42784

A so-called multi-type air conditioner in which a plurality of evaporators are connected in parallel between a condenser and a suction side of a compressor has been proposed as a conventional air conditioner. The multi-type air conditioner is provided with a plurality of electronic expansion valves corresponding to the number of evaporators. Specifically, the multi-type air conditioner has one electronic expansion valve and one evaporator connected in series as one set, and a plurality of sets are connected in parallel between the condenser and the suction side of the compressor. Has been. Even in the multi-type air conditioner, the plurality of electronic expansion valves do not have the same opening degree due to individual differences.

Here, by applying the technique described in Patent Document 1 to the multi-type air conditioner, the opening degree of each electronic expansion valve can be accurately set to the valve opening degree position. However, even if the technique described in Patent Document 1 is applied to the multi-type air conditioner, the refrigerant cannot be accurately distributed to each evaporator. For example, when there is an electronic expansion valve A whose opening corresponding to a command value of 45 pulses is a valve opening, and an electronic expansion valve B whose opening corresponding to a command value of 35 pulses is a valve opening. To do. Even if the opening degree of these two electronic expansion valves is controlled with the same command value, there is a difference in opening degree corresponding to 10 pulses. Therefore, the conventional multi-type air conditioner has a problem that the refrigerant cannot be accurately distributed to each evaporator due to the individual difference of each electronic expansion valve.

The present invention has been made to solve the above-described problems. In an air conditioner in which a plurality of electronic expansion valves and an evaporator are connected in parallel between a condenser and a compressor, each evaporator is supplied to each evaporator. An object of the present invention is to obtain an air conditioner that can perform refrigerant distribution more accurately than in the past.

An air conditioner according to the present invention includes a compressor, a condenser, a plurality of electronic expansion valves, and a refrigeration cycle circuit having a plurality of evaporators, and a control device that controls the respective opening degrees of the electronic expansion valves. The plurality of electronic expansion valves and the plurality of evaporators include one electronic expansion valve and one evaporator connected in series as one set, and a plurality of sets include the condenser and the compression unit. Are connected in parallel to each other, and the control device determines a reference valve opening degree and a value used for correcting the opening degree of the electronic expansion valve for each electronic expansion valve. And a control unit that controls each of the electronic expansion valves to an opening degree obtained by correcting the reference valve opening degree with a value stored in the storage part.

The air conditioner according to the present invention corrects the reference valve opening for each electronic expansion valve, and controls the opening of each electronic expansion valve to the corrected opening. For this reason, the air conditioner according to the present invention can correct individual differences for each electronic expansion valve, and can perform refrigerant distribution to each evaporator more accurately than before.

It is a refrigerant circuit figure of the air conditioner concerning an embodiment of the invention. It is a refrigerant circuit figure which shows another example of the air conditioner which concerns on embodiment of this invention. It is a characteristic view which shows the relationship between the opening degree and flow volume of each electronic expansion valve in the air conditioner which concerns on embodiment of this invention. It is a control flow which detects the valve opening degree of the electronic expansion valve in the air conditioner which concerns on embodiment of this invention. It is a control flow of the electronic expansion valve at the time of air_conditionaing | cooling operation in the air conditioner which concerns on embodiment of this invention.

Embodiment.
FIG. 1 is a refrigerant circuit diagram of an air conditioner according to an embodiment of the present invention.
The air conditioner 100 according to the present embodiment includes a refrigeration cycle circuit 101. The refrigeration cycle circuit 101 includes a compressor 1, an outdoor heat exchanger 3, a plurality of electronic expansion valves 4, and a plurality of indoor heat exchangers 5. That is, the air conditioner 100 according to the present embodiment is a so-called multi-type air conditioner.
The air conditioner 100 according to the present embodiment includes n electronic expansion valves 4 and an indoor heat exchanger 5 that are two or more natural numbers. In order to distinguish each electronic expansion valve 4 from each other, the subscripts “a” to “n” are added to the end of the reference numerals. Similarly, in order to distinguish between the indoor heat exchangers 5, the suffixes “a” to “n” are added to the end of the reference numerals. The same applies to the indoor unit 120 and the temperature sensor 12 described later.

The compressor 1 sucks refrigerant and compresses the refrigerant into a high-temperature and high-pressure gaseous refrigerant. The kind of the compressor 1 is not specifically limited, For example, the compressor 1 can be comprised using various types of compression mechanisms, such as a reciprocating, a rotary, a scroll, or a screw. The compressor 1 may be configured of a type that can be variably controlled by an inverter.

The outdoor heat exchanger 3 is connected to the discharge side of the compressor 1. The outdoor heat exchanger 3 is, for example, a fin tube type air heat exchanger that exchanges heat between the refrigerant flowing inside and the outdoor air. The outdoor heat exchanger 3 acts as a condenser during the cooling operation.

A plurality of electronic expansion valves 4a to 4n and a plurality of indoor heat exchangers 5a to 5n are connected in parallel between the outdoor heat exchanger 3 and the suction side of the compressor 1. Specifically, the plurality of electronic expansion valves 4 a to 4 n are connected in series to the outdoor heat exchanger 3. In addition, indoor heat exchangers 5a to 5n are connected in series to the electronic expansion valves 4a to 4n. The indoor heat exchangers 5a to 5n are connected in parallel to the suction side of the compressor 1. That is, one electronic expansion valve 4 and one indoor heat exchanger 5 connected in series constitute one set, and a plurality of sets are connected in parallel between the outdoor heat exchanger 3 and the suction side of the compressor 1. Has been.

The electronic expansion valves 4a to 4n are configured to adjust the opening degree by moving the valve body with, for example, a pulse motor. That is, when a command value such as a pulse value is input from the control device 50 to be described later, the electronic expansion valves 4a to 4n have openings corresponding to the command value. For example, the electronic expansion valves 4a to 4n have a larger opening degree as the pulse value as the command value is larger. The electronic expansion valves 4a to 4n adjust the flow rate of the refrigerant in accordance with the opening degree. In other words, the refrigerant flowing through the electronic expansion valves 4a to 4n is decompressed to a pressure corresponding to the opening degree of the electronic expansion valves 4a to 4n and expands.

The indoor heat exchangers 5a to 5n are, for example, fin-tube type air heat exchangers that exchange heat between the refrigerant flowing inside and the room air. The indoor heat exchangers 5a to 5n function as an evaporator during the cooling operation.

In addition, the air conditioner 100 according to the present embodiment has a configuration that allows not only cooling operation but also heating operation. For this reason, the refrigeration cycle circuit 101 of the air conditioner 100 includes the four-way valve 2 that switches the refrigerant flow path between the cooling operation and the heating operation. During the cooling operation, the four-way valve 2 connects the discharge side of the compressor 1 and the outdoor heat exchanger 3, and connects the suction side of the compressor 1 and the indoor heat exchangers 5a to 5n. During the heating operation, the four-way valve 2 connects the discharge side of the compressor 1 and the indoor heat exchangers 5a to 5n, and connects the suction side of the compressor 1 and the outdoor heat exchanger 3.

Each component of the air conditioner 100 described above is housed in the outdoor unit 110 or the indoor unit 120. Specifically, the outdoor unit 110 houses a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, and a plurality of electronic expansion valves 4a to 4n. The indoor unit 120 houses indoor heat exchangers 5a to 5n. At this time, one indoor heat exchanger 5 may be accommodated in one indoor unit 120, or two or more indoor heat exchangers 5 may be accommodated in one indoor unit 120.

In the present embodiment, the electronic expansion valves 4a to 4n are housed in the outdoor unit 110. For example, the electronic expansion valves 4a to 4n may be housed in the indoor unit 120 together with the indoor heat exchangers 5a to 5n connected to the electronic expansion valves 4a to 4n. Further, for example, as shown in FIG. 2, a branch box 130 for branching the refrigerant flowing out of the outdoor unit 110 to each indoor unit 120 may be provided, and the electronic expansion valves 4a to 4n may be stored in the branch box 130. FIG. 2 is a refrigerant circuit diagram showing another example of the air conditioner according to the embodiment of the present invention.

The air conditioner 100 also includes a plurality of temperature sensors and a control device 50 that controls each component of the air conditioner 100 (such as the opening degree of the electronic expansion valve 4) based on the detection values of these temperature sensors. ing.

Specifically, a temperature sensor 11 that detects the temperature of the refrigerant discharged from the compressor 1 is provided on the discharge side of the compressor 1. Each of the indoor heat exchangers 5a to 5n is provided with temperature sensors 12a to 12n for detecting the temperature of the indoor heat exchangers 5a to 5n. The temperature sensors 11, 12a to 12n are, for example, thermistors.
Here, the temperature sensor 11 corresponds to the discharge refrigerant temperature sensor of the present invention. The temperature sensor 12 corresponds to the evaporator temperature sensor of the present invention.

The control device 50 is configured by dedicated hardware or a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor) that executes a program stored in a memory. . The control apparatus 50 is accommodated in the outdoor unit 110, for example.

When the control device 50 is dedicated hardware, the control device 50 may be, for example, a single circuit, a composite circuit, an ASIC (application specific integrated circuit), an FPGA (field-programmable gate array), or a combination of these. Applicable. Each functional unit realized by the control device 50 may be realized by individual hardware, or each functional unit may be realized by one piece of hardware.

When the control device 50 is a CPU, each function executed by the control device 50 is realized by software, firmware, or a combination of software and firmware. Software and firmware are described as programs and stored in a memory. The CPU implements each function of the control device 50 by reading and executing a program stored in the memory. Here, the memory is a nonvolatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM.

Note that a part of the function of the control device 50 may be realized by dedicated hardware, and a part may be realized by software or firmware.

The control device 50 according to the present embodiment includes a reference opening degree determination unit 51, a detection unit 52, a storage unit 53, and a control unit 54 as functional units.

The reference opening determination unit 51 determines a reference valve opening that serves as a reference when controlling the opening of each of the electronic expansion valves 4 a to 4 n based on the temperature detected by the temperature sensor 11. The detection unit 52 detects the opening degrees of the electronic expansion valves 4a to 4n based on the detected temperatures of the temperature sensors 12a to 12n provided in the indoor heat exchangers 5a to 5n. The valve opening degree is an opening degree of the electronic expansion valves 4a to 4n at which the refrigerant starts to flow into the electronic expansion valves 4a to 4n. The storage unit 53 stores values used for correcting the opening degree of the electronic expansion valves 4a to 4n. The storage unit 53 stores the value for each of the electronic expansion valves 4a to 4n. In the present embodiment, the storage unit 53 uses the opening degree of the electronic expansion valves 4a to 4n and the opening degree of the electronic expansion valves 4a to 4n as values used for correcting the opening degree of the electronic expansion valves 4a to 4n. The comparison opening used for comparison with the opening is stored. The control unit 54 controls each of the electronic expansion valves 4a to 4n to an opening obtained by correcting the reference valve opening determined by the reference opening determining unit 51 with a value stored in the storage unit 53. The control unit 54 also controls driving and stopping of the compressor 1 and switching of the flow path of the four-way valve 2.

[Description of operation]
Next, the operation of the air conditioner 100 configured as described above will be described. In the following, the operation during the cooling operation in which the indoor heat exchangers 5a to 5n function as an evaporator will be described.

When the controller 54 drives the compressor 1, the high-temperature and high-pressure gaseous refrigerant compressed by the compressor 1 flows into the outdoor heat exchanger 3 through the four-way valve 2. The high-temperature and high-pressure gaseous refrigerant that has flowed into the outdoor heat exchanger 3 dissipates heat to the outdoor air, condenses, and flows out of the outdoor heat exchanger 3 as a liquid refrigerant. The liquid refrigerant flowing out of the outdoor heat exchanger 3 branches and flows into the electronic expansion valves 4a to 4n. The liquid refrigerant that has flowed into the electronic expansion valves 4a to 4n is decompressed to be in a low-temperature gas-liquid two-phase state, and flows out from the electronic expansion valves 4a to 4n. In the present embodiment, the opening degree of the electronic expansion valves 4a to 4n is set so that the detected value of the temperature sensor 11, that is, the temperature of the refrigerant discharged from the compressor 1 falls within a specified range (a specified temperature range). Control.

The low-temperature gas-liquid two-phase refrigerant flowing out of the electronic expansion valves 4a to 4n flows into the indoor heat exchangers 5a to 5n connected in series to the electronic expansion valves 4a to 4n. The low-temperature gas-liquid two-phase refrigerant that has flowed into the indoor heat exchangers 5a to 5n cools the indoor air, that is, cools the room and becomes low-pressure gaseous refrigerant and flows out of the indoor heat exchangers 5a to 5n. The low-pressure gaseous refrigerant that has flowed out of the indoor heat exchangers 5a to 5n joins and then is sucked into the compressor 1 through the four-way valve 2.

Here, the electronic expansion valves 4a to 4n are controlled to an opening degree corresponding to the amount of refrigerant distributed to the indoor heat exchangers 5a to 5n. For this reason, for example, when it is desired to flow the same amount of refrigerant in each of the indoor heat exchangers 5a to 5n, the conventional multi-type air conditioner controls the opening degree of the electronic expansion valves 4a to 4n to the same opening degree. . However, the electronic expansion valves 4a to 4n have different valve opening degrees due to dimensional errors and assembly errors of parts. For this reason, even if the opening degree of the electronic expansion valves 4a to 4n is controlled as in the prior art, the flow rate of the refrigerant flowing to the indoor heat exchangers 5a to 5n is actually different, and it is precisely to the indoor heat exchangers 5a to 5n. Refrigerant distribution cannot be performed.

FIG. 3 is a characteristic diagram showing the relationship between the opening and flow rate of each electronic expansion valve in the air conditioner according to the embodiment of the present invention. FIG. 3 shows the relationship between the opening degree and the flow rate of the electronic expansion valves 4a to 4c. In FIG. 3, the relationship between the opening degree of the virtual electronic expansion valve V and the flow rate is also indicated by a two-dot chain line.

As shown in FIG. 3, the opening degree of the electronic expansion valve 4a is smaller than that of the

electronic expansion valves

4b and 4c. The opening degree of the electronic expansion valve 4b is larger than the electronic expansion valve 4a and smaller than the electronic expansion valve 4c. Further, the opening degree of the electronic expansion valve 4c is larger than that of the

electronic expansion valves

4a and 4b. Therefore, if the opening degree of the electronic expansion valves 4a to 4c is controlled to the same opening degree α, as shown in FIG. 3, the flow rate actually flowing through the electronic expansion valves 4a to 4c, that is, the indoor heat exchangers 5a to 5c The flow rate of the flowing refrigerant is expressed by the following equation (1). Therefore, the same amount of refrigerant cannot be distributed to the indoor heat exchangers 5a to 5c.

Flow rate of electronic expansion valve 4a (indoor heat exchanger 5a)> Flow rate of electronic expansion valve 4b (indoor heat exchanger 5b)> Flow rate of electronic expansion valve 4c (indoor heat exchanger 5c) (1)

Therefore, in this embodiment, the opening degree of each of the electronic expansion valves 4a to 4n is controlled to the value corrected by the following equation (2).

Opening of electronic expansion valve 4 = reference valve opening + (opening opening of electronic expansion valve 4−comparative opening) (2)

That is, the electronic expansion valve 4 whose valve opening degree is smaller than the comparison opening degree is controlled to an opening degree smaller than the reference opening degree. Further, the electronic expansion valve 4 whose valve opening degree is larger than the comparison opening degree is controlled to an opening degree larger than the reference opening degree. As a result, the flow rate actually flowing through the electronic expansion valves 4a to 4n, that is, the flow rate of the refrigerant flowing through the indoor heat exchangers 5a to 5n can be made the same. For example, when the opening degree of the virtual electronic expansion valve V is used as the comparison opening degree, if the electronic expansion valves 4a to 4n are controlled to the opening corrected by the equation (2), the electronic expansion valves 4a to 4n The flow rate of the refrigerant flowing through each is the same as the flow rate of the virtual electronic expansion valve V.

Specifically, the control device 50 according to the present embodiment controls the electronic expansion valves 4a to 4n as described above using the following control flow.

FIG. 4 is a control flow for detecting the opening degree of the electronic expansion valve in the air conditioner according to the embodiment of the present invention.
When starting control of detection of the opening degrees of the electronic expansion valves 4a to 4n in step S1, the control unit 54 controls the four-way valve 2 to the flow path during the cooling operation to drive the compressor 1. In step S2, the control unit 54 controls the electronic expansion valves 4a to 4n to the same initial opening. This initial opening is an opening smaller than the opening degrees of all the electronic expansion valves 4a to 4n. Then, after a predetermined time has elapsed from step S2, in step S3, the control unit 54 opens the opening degree of the electronic expansion valves 4a to 4n by a predetermined amount. That is, the control unit 54 increases the opening degree of the electronic expansion valves 4a to 4n.

In step S4, the detection unit 52 determines whether or not there is a temperature sensor 12 whose detected temperature has decreased by a specified temperature (for example, 1 ° C.) or more. That is, the detection unit 52 has received the detected temperatures of the temperature sensors 12a to 12n before step S3, and determines whether there is any temperature sensor 12 that has fallen by a specified temperature or more after step S4. If there is no temperature sensor 12 whose detected temperature has fallen above the specified temperature in step S4, the process returns to step S3. That is, the control unit 54 opens the opening degree of the electronic expansion valves 4a to 4n by a specified amount.

On the other hand, if there is a temperature sensor 12 whose detected temperature has decreased in step S4, the detecting unit 52 in step S5 is that of the electronic expansion valve 4 connected in series with the indoor heat exchanger 5 provided with the temperature sensor 12. Is stored in the storage unit 53 as the opening degree of the electronic expansion valve 4. When the refrigerant starts to flow into the electronic expansion valve 4, low-pressure gas-liquid two-phase refrigerant flows into the indoor heat exchanger 5 connected in series to the electronic expansion valve 4, and the temperature of the indoor heat exchanger 5 decreases. It is. For example, when the temperature detected by the temperature sensor 12a decreases, the detection unit 52 stores the opening degree of the electronic expansion valve 4a at that time in the storage unit 53 as the opening degree of the electronic expansion valve 4a.

After step S5, in step S6, the detection unit 52 determines whether or not all the opening degrees of the electronic expansion valves 4a to 4n are stored in the storage unit 53. And when there exists the electronic expansion valve 4 in which the valve opening degree is not memorize | stored, it returns to step S3. That is, the control unit 54 opens the opening degree of the electronic expansion valves 4a to 4n by a specified amount. On the other hand, if all the opening degrees of the electronic expansion valves 4a to 4n are stored in the storage unit 53, the detection of the opening degrees of the electronic expansion valves 4a to 4n is terminated in step S7.

The opening degree of the electronic expansion valves 4a to 4n is detected, for example, when the air conditioner 100 is installed. Further, for example, when taking into account the secular change of the opening degree of the electronic expansion valves 4a to 4n, the opening degree of the electronic expansion valves 4a to 4n may be detected periodically. In FIG. 4, the opening degree of the electronic expansion valves 4a to 4n is gradually opened to detect the opening degree, but the opening degree of the electronic expansion valves 4a to 4n is gradually closed to open the valve. The degree may be detected. That is, an opening larger than the opening degrees of all the electronic expansion valves 4a to 4n is set as an initial opening degree, and the opening degrees of the electronic expansion valves 4a to 4n are gradually closed. When there is the electronic expansion valve 4 in which the refrigerant has stopped flowing, the low-pressure gas-liquid two-phase refrigerant does not flow into the indoor heat exchanger 5 connected in series to the electronic expansion valve 4, and the temperature of the indoor heat exchanger 5 is reduced. To rise. The opening degree of the electronic expansion valves 4a to 4n can also be detected by detecting this temperature rise by the temperature sensor 12.

FIG. 5 is a control flow of the electronic expansion valve during the cooling operation in the air conditioner according to the embodiment of the present invention.

When a cooling operation command is transmitted from the remote controller or the like (not shown) to the control device 50, the control unit 54 controls the four-way valve 2 to the flow path during the cooling operation and drives the compressor 1 (step S11). . In step S12, the reference opening degree determination unit 51 determines the reference valve opening degree as an initial value. In step S13, the control unit 54 obtains the corrected opening of each of the electronic expansion valves 4a to 4n by the above-described equation (2), and sets each of the electronic expansion valves 4a to 4n to the corrected opening. Control.

After step S14, the reference opening determination unit 51 determines the reference valve opening so that the temperature detected by the temperature sensor 11 falls within the specified range. Specifically, when the detected temperature of the temperature sensor 11 is within a specified range, if the stop command for cooling operation is not transmitted from the remote controller (not shown) to the control device 50 (step S15), the reference opening degree determination unit 51 returns to step S13 without changing the reference valve opening.

On the other hand, when the temperature detected by the temperature sensor 11 is out of the specified range, the reference opening determination unit 51 changes the reference valve opening in step S16. And if the stop command of cooling operation is not transmitted to the control apparatus 50 from the remote controller etc. which are not shown in figure (step S17), the reference opening degree determination part 51 returns to step S13. That is, when the process returns to step S13 after step S16, the control unit 54 substitutes the changed reference valve opening into the above-described equation (2), and the corrected opening of each of the electronic expansion valves 4a to 4n. Each of the electronic expansion valves 4a to 4n is controlled to the corrected opening.

The above control is performed until a cooling operation stop command is transmitted to the control device 50 from a remote controller (not shown) or the like. On the other hand, when a cooling operation stop command is transmitted from the remote controller (not shown) to the control device 50 (steps S15 and S17), the control unit 54 stops the compressor 1 and ends the cooling operation in step S18. Let

As described above, the air conditioner 100 according to the present embodiment corrects the reference valve opening for each electronic expansion valve 4 and controls the opening of each electronic expansion valve 4 to the corrected opening. Therefore, the air conditioner 100 according to the present embodiment can correct individual differences for each electronic expansion valve 4, and can more accurately distribute the refrigerant to the indoor heat exchangers 5a to 5n than before. That is, since the refrigerant corresponding to the air conditioning load of the indoor heat exchangers 5a to 5n can be distributed to the indoor heat exchangers 5a to 5n, the comfort of the installation space of the indoor heat exchangers 5a to 5n can be improved.

Moreover, the air conditioner 100 according to the present embodiment can also obtain the following effects. That is, the conventional multi-type air conditioner has a problem that refrigerant cannot be accurately distributed to each evaporator (indoor heat exchanger during cooling operation) due to individual differences of each electronic expansion valve. This problem is particularly noticeable in a low-load operation state where the electronic expansion valve has a minute opening. This is because some electronic expansion valves are less than the opening degree. For this reason, in the conventional multi-type air conditioner, since the temperature and pressure of the refrigerant discharged from the compressor are maintained at a predetermined value or more, the lower limit of the operation range of the compressor cannot be lowered. On the other hand, the air conditioner 100 according to the present embodiment can distribute the refrigerant according to the air conditioning load of the indoor heat exchangers 5a to 5n to the indoor heat exchangers 5a to 5n, so that the lower limit of the operating range of the compressor 1 is set. Can be enlarged. For this reason, the air conditioner 100 according to the present embodiment can reduce the stop frequency of the compressor 1 during the cooling operation in a low load state in which the electronic expansion valves 4a to 4n have a minute opening. Therefore, the air conditioner 100 according to the present embodiment can improve the operation efficiency and can also reduce power consumption.

Here, the air conditioner 100 according to the present embodiment is based on the temperature detected by the temperature sensor 11, that is, on the basis of the refrigerant temperature at a location that is not divided into the indoor heat exchangers 5a to 5n. The opening degree of 4n is controlled. Thus, when the opening degree of the electronic expansion valves 4a to 4n is controlled, the flow rate of the refrigerant cannot be grasped for each indoor heat exchanger 5. For this reason, the control method of the opening degree of the electronic expansion valves 4a to 4n shown in the present embodiment is based on the refrigerant temperature at the location where the electronic expansion valves 4a to 4n are not divided into the indoor heat exchangers 5a to 5n. This is particularly effective when controlling the opening.

In the present embodiment, the air conditioner 100 has a function of detecting the opening degree of the electronic expansion valves 4a to 4n. However, the opening degree of the electronic expansion valves 4a to 4n may be detected by a test device or the like. And the detected value may be stored in the storage unit 53. Even in this way, the present invention can be implemented. In the present embodiment, the comparison opening and the opening degrees of the electronic expansion valves 4a to 4n are stored in the storage unit 53, and the opening degrees of the electronic expansion valves 4a to 4n are corrected with these values. However, the present invention is not limited to this, and a value obtained by subtracting the comparison opening from the opening degree of the electronic expansion valves 4a to 4n is stored as a correction value in the storage unit 53, and the electronic expansion valves 4a to 4n are stored using the correction value. The opening degree may be corrected. Even in this way, the present invention can be implemented.

Here, as the air conditioner 100 has a function of detecting the opening degrees of the electronic expansion valves 4a to 4n as in the present embodiment, the opening degrees of the electronic expansion valves 4a to 4n are periodically set. By recalculating, the refrigerant distribution to each indoor heat exchanger 5 can be accurately performed even when the valve opening degree of the electronic expansion valves 4a to 4n changes due to aging. In addition, the method for detecting the opening degrees of the electronic expansion valves 4a to 4n shown in the present embodiment can detect the opening degrees of the electronic expansion valves 4a to 4n in parallel. Therefore, the air conditioner 100 according to the present embodiment can shorten the detection time of the opening degrees of the electronic expansion valves 4a to 4n.

Also, some conventional multi-type air conditioners include an electronic expansion valve that adjusts the circulation amount of the refrigerant in the entire refrigeration cycle circuit between the outdoor heat exchanger and the plurality of electronic expansion valves. Also in the air conditioner 100 according to the present embodiment, such an electronic expansion valve 6 may be provided as shown in FIG. Even if the electronic expansion valve 6 is provided, the method for controlling the opening degree of the electronic expansion valves 4a to 4n is not changed, and the present invention can be implemented.

In addition, there is a so-called high-pressure shell type compressor having a shell that temporarily stores the refrigerant compressed by the compression mechanism. When such a high-pressure shell type compressor is used as the compressor 1, a temperature sensor 13 is provided at a location where the compressed refrigerant in the shell is stored as shown in FIG. Also good. Similar to the temperature sensor 11, the temperature sensor 13 can detect the temperature of the refrigerant after being compressed by the compressor 1. For this reason, the present invention can be implemented even when the temperature detected by the temperature sensor 13 is used instead of the temperature detected by the temperature sensor 11.

1 compressor, 2-way valve, 3 outdoor heat exchanger, 4 (4a-4n) electronic expansion valve, 5 (5a-5n) indoor heat exchanger, 6 electronic expansion valve, 11 temperature sensor, 12 (12a-12n) Temperature sensor, 13 temperature sensor, 50 control device, 51 reference opening determination unit, 52 detection unit, 53 storage unit, 54 control unit, 100 air conditioner, 101 refrigeration cycle circuit, 110 outdoor unit, 120 (120a to 120n) Indoor unit, 130 branch box.

Claims

A refrigeration cycle circuit having a compressor, a condenser, a plurality of electronic expansion valves, and a plurality of evaporators;
A control device for controlling the opening degree of each of the electronic expansion valves;
With
The plurality of electronic expansion valves and the plurality of evaporators include one electronic expansion valve and one evaporator connected in series as one set, and a plurality of sets include the condenser and the compressor. Are connected in parallel,
The control device includes:
A reference opening determining unit for determining a reference valve opening;
For each electronic expansion valve, a storage unit that stores a value used to correct the opening of the electronic expansion valve;
A control unit for controlling each of the electronic expansion valves to an opening obtained by correcting the reference valve opening with a value stored in the storage unit;
Having an air conditioner.
The storage unit
A valve opening degree that is an opening degree at which the refrigerant begins to flow to the electronic expansion valve for each electronic expansion valve;
A comparative opening used for comparison with the valve opening;
Remember
The controller is
2. The air conditioner according to claim 1, wherein each opening degree of the electronic expansion valve is controlled to be the reference valve opening degree + (the valve opening degree−the comparison opening degree).
An evaporator temperature sensor provided in each of the evaporators;
The control device includes:
A detector for detecting the opening degree of each of the electronic expansion valves;
The detection unit
When the opening temperature of the electronic expansion valve was changed, and when the detected temperature of the evaporator temperature sensor changed more than a specified temperature, the evaporator temperature sensor was connected in series with the evaporator. The air conditioner according to claim 2, wherein the air conditioner is configured to detect the opening degree of the electronic expansion valve.
The air conditioner according to claim 3, wherein the detection unit is configured to detect the valve opening degrees of the plurality of electronic expansion valves in parallel.
The storage unit stores a correction value for each electronic expansion valve,
The controller is
The air conditioner according to claim 1, wherein the opening degree of each of the electronic expansion valves is controlled to be the reference valve opening degree + the correction value.
The correction value stored for each electronic expansion valve is:
The air conditioner according to claim 5, wherein the air conditioner is a value obtained by subtracting a comparative opening degree from a valve opening degree that is an opening degree at which refrigerant starts to flow through the electronic expansion valve.
A discharge refrigerant temperature sensor for detecting the temperature of the refrigerant discharged from the compressor;
The reference opening degree determining unit is configured to determine the reference valve opening degree so that a temperature detected by the discharged refrigerant temperature sensor falls within a specified range. Air conditioner.
The compressor has a shell for storing the compressed refrigerant,
A shell temperature sensor for detecting the temperature of the location where the compressed refrigerant in the shell is stored;
The air according to any one of claims 1 to 6, wherein the reference opening determination unit is configured to determine the reference valve opening so that a temperature detected by the shell temperature sensor falls within a specified range. Harmony machine.