WO2022176050A1

WO2022176050A1 - Air-conditioning device

Info

Publication number: WO2022176050A1
Application number: PCT/JP2021/005858
Authority: WO
Inventors: 龍一永田; 雄亮田代
Original assignee: 三菱電機株式会社
Priority date: 2021-02-17
Filing date: 2021-02-17
Publication date: 2022-08-25
Also published as: JPWO2022176050A1; EP4296593A1; JP7466754B2; US20240068699A1; EP4296593A4

Abstract

An air-conditioning device (1) comprises a refrigerant circuit (150) and a control device (200). The refrigerant circuit (150) is configured so as to circulate a refrigerant through a compressor (10), a condenser (40, 20), an LEV (111), and an evaporator (20, 40). The LEV (111) is configured so as to have a variable opening degree between a lower limit opening degree and an upper limit opening degree. The control device (200) is configured so as to control the LEV (111) to alternate between a first opening degree (CvA) and a second opening degree (CvB) smaller than the first opening degree (CvA) within a range of one-quarter of the upper limit opening degree or less.

Description

air conditioner

The present disclosure relates to an air conditioner.

In recent years, with the aim of becoming a ZEH (Net Zero Energy House), homes are becoming highly airtight and highly insulated. In homes with advanced thermal insulation, the rated capacity corresponding to the number of tatami mats is required when air conditioning is in operation in midsummer and midwinter, but the air conditioning load is extremely small when the room temperature is stable.

　In order to achieve stable air conditioning with an extremely low air conditioning load, the frequency of the compressor should be lowered to operate the air conditioner. However, when the compressor frequency is lowered, the pressure difference between high and low pressures in the refrigerant circuit is reduced, and the temperature and degree of superheat of the discharged refrigerant are lowered. When the degree of superheat of the discharged refrigerant is low, the temperature and the degree of superheat of the suctioned refrigerant also decrease, and the state of the refrigerant sucked into the compressor tends to be in a two-phase state of liquid and gas. Such a condition can lead to compressor failure. Normally, if you want to change the state of the sucked refrigerant from two-phase to gas single-phase, the electronic expansion valve should be throttled. Met.

In International Publication No. 2013/103061 (Patent Document 1), in order to stabilize air conditioning control, an electronic expansion valve attached with characteristic data associated with manufacturing variations written in a barcode and an air conditioner equipped with the same. disclosed.

WO2013/103061

In the electronic expansion valve described in International Publication No. 2013/103061 (Patent Document 1), in order to correct manufacturing variations in the valve opening point, the valve opening point of each electronic expansion valve is measured in advance, and the bar The code contains the data. Then, when the air conditioner is manufactured, it is necessary to read the bar code and reflect the data in the electronic expansion valve control program. As a result, the number of manufacturing steps for the air conditioner is increased.

The present disclosure has been made to solve the above problems, and aims to disclose an air conditioner that can realize low-capacity operation while avoiding complication of the manufacturing process.

The present disclosure relates to an air conditioner. An air conditioner includes a refrigerant circuit and a control device. The refrigerant circuit is configured such that refrigerant circulates through the compressor, the condenser, the expansion valve, and the evaporator. The expansion valve is configured such that the degree of opening is variable between a lower limit opening degree and an upper limit opening degree. The control device controls the expansion valve such that the first degree of opening and the second degree of opening, which is smaller than the first degree of opening, are alternately repeated within the range of the degree of opening equal to or less than 1/4 of the upper limit degree of opening. configured to

The air conditioner of the present disclosure repeats the increase and decrease of the opening of the expansion valve within a range of 1/4 of the upper limit opening or less. As a result, it is possible to realize an air conditioner capable of low-capacity operation while avoiding complication of the manufacturing process.

1 is a diagram showing the configuration of an air conditioner according to Embodiment 1. FIG. 3 is a block diagram showing the configuration of a control device and LEV; FIG. FIG. 4 is a waveform diagram for explaining changes in the degree of opening of an electronic expansion valve; 4 is a diagram for explaining the relationship between the Cv value of the LEV 111 and the number of pulses indicating the degree of opening; FIG. FIG. 5 is a diagram for explaining the positions of CvA and CvB in FIG. 3 at the opening degree shown in FIG. 4; 4 is a flowchart for explaining control of operation mode switching executed in the air conditioning system of Embodiment 1. FIG. FIG. 7 is a flow chart showing an example of the processing contents of step S3 of FIG. 6; FIG. FIG. 10 is a flow chart for explaining processing executed in the second embodiment; FIG. FIG. 10 is a diagram showing an example of a map M1 used in Embodiment 2; FIG. FIG. 10 is a diagram showing another map M1A used in Embodiment 2; FIG. FIG. 4 is a diagram showing the relationship between the operating frequency of the compressor and the desired Cv value; FIG. 12 is a diagram for explaining time ratio control executed in the third embodiment; FIG. 14 is a flowchart for explaining control of operation mode switching executed in the air conditioning system of Embodiment 4. FIG. FIG. 14 is a flowchart for explaining the process of step S3B in FIG. 13; FIG. FIG. 12 is a diagram showing an example of a map M2 used in Embodiment 4; FIG.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. A plurality of embodiments will be described below, but appropriate combinations of the configurations described in the respective embodiments have been planned since the filing of the application. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated. In the following figures, the size relationship of each component may differ from the actual size.

Embodiment 1.
FIG. 1 is a diagram showing the configuration of an air conditioner according to Embodiment 1. FIG. The air conditioner 1 includes a compressor 10, an indoor heat exchanger 20, an electronic expansion valve (LEV: Linear Expansion Valve) 111, an outdoor heat exchanger 40, and

pipes

90, 92, 94, 96, 97, 99. and a refrigerant circuit 150 including the four-way valve 100 . The four-way valve 100 has ports EH.

The pipe 90 is connected between the port H of the four-way valve 100 and the port P1 of the indoor heat exchanger 20. Piping 92 is connected between port P4 of indoor heat exchanger 20 and LEV 111 . A pipe 94 is connected between the LEV 111 and the port P3 of the outdoor heat exchanger 40 .

The pipe 96 is connected between the port P2 of the outdoor heat exchanger 40 and the port F of the four-way valve 100 . A pipe 97 is connected between the suction port of the compressor 10 and the port E of the four-way valve 100 . A pipe 99 is connected between the outlet of the compressor 10 and the port G of the four-way valve 100 .

The compressor 10, the LEV 111, the outdoor heat exchanger 40, the

pipes

94, 96, 97, 99, and the four-way valve 100 are housed in the outdoor unit 2. The indoor heat exchanger 20 is housed in the indoor unit 3 . The outdoor unit 2 and the indoor unit 3 are connected by

pipes

90 and 92 .

The air conditioner 1 further includes temperature sensors 101 to 103, 106, 107 and a control device 200. A temperature sensor 101 is arranged in the middle of the pipe 99 and measures the discharge temperature TH. A temperature sensor 102 is arranged near the indoor heat exchanger 20 to measure the indoor temperature Tr. The temperature sensor 103 is arranged near the outdoor heat exchanger 40 and measures the outdoor temperature Te. The temperature sensor 106 is arranged in the refrigerant pipe of the indoor heat exchanger 20 and measures the temperature T1 of the two-phase region refrigerant. The temperature sensor 107 is arranged in the refrigerant pipe of the outdoor heat exchanger 40 and measures the temperature T2 of the two-phase region refrigerant. The control device 200 controls the compressor 10, the four-way valve 100, and the LEV 111 according to the operation command signal given by the user and the outputs of various sensors.

The compressor 10 is configured to change the operating frequency according to a control signal received from the control device 200 . Specifically, the compressor 10 incorporates an inverter-controlled drive motor whose rotational speed is variable, and the rotational speed of the drive motor changes when the operating frequency is changed. By changing the operating frequency of the compressor 10, the output of the compressor 10 is adjusted. Various types such as rotary type, reciprocating type, scroll type, and screw type can be adopted for the compressor 10 .

The four-way valve 100 is controlled by a control signal received from the control device 200 so as to be in either the cooling operation state or the heating operation state. The cooling operation state is a state in which the port E and the port H are in communication, and the port F and the port G are in communication. In the heating operation state, the port E and the port F communicate, and the port H and the port G communicate. By operating the compressor 10 in the cooling operation state, the refrigerant circulates in the refrigerant circuit in the direction indicated by the solid line arrow. Further, by operating the compressor 10 in the heating operation state, the refrigerant circulates in the refrigerant circuit in the direction indicated by the dashed arrow.

The opening of the LEV 111 is controlled by a control signal received from the control device 200 so as to adjust the SH (superheat: degree of heating) of the refrigerant at the outlet of the evaporator.

FIG. 2 is a block diagram showing the configuration of the control device and LEV. As shown in FIG. 2, the control device 200 includes a CPU (Central Processing Unit) 201, a memory 202 (ROM (Read Only Memory) and RAM (Random Access Memory)), an input/output buffer (not shown), etc. composed of The CPU 201 expands a program stored in the ROM into the RAM or the like and executes it. The program stored in the ROM is a program in which processing procedures of the control device 200 are described. The control device 200 controls each device in the air conditioner 1 according to these programs. This control is not limited to processing by software, and processing by dedicated hardware (electronic circuit) is also possible.

The controller 200 is configured to control the motor drive circuit 203 based on the outdoor temperature Te, the indoor temperature Tr, the discharge temperature TH, and the temperatures T1 and T2 of the two-phase refrigerant.

The LEV 111 is provided with a stepping motor 112 and a valve body 113 in which the rotation of the stepping motor 112 changes the position of the needle and changes the degree of opening. The stepping motor 112 is driven by a motor drive circuit 203 . The control device 200 outputs the number of pulses to the motor drive circuit 203 as a command value indicating the degree of opening of the valve body 113 .

　Referring to FIG. 1 again, the flow of the refrigerant during the heating operation indicated by the dashed arrow will be described. Gas refrigerant discharged from the compressor 10 flows into the indoor heat exchanger 20 through the pipe 90 . The gas refrigerant flowing into the indoor heat exchanger 20 exchanges heat with the air flowing on the fin side of the indoor heat exchanger 20 to become liquid refrigerant. The liquefied refrigerant flows into the LEV 111 through the pipe 92 and adiabatically expands.

The gas-liquid two-phase refrigerant adiabatically expanded in the LEV 111 flows through the pipe 94 into the outdoor heat exchanger 40 . The gas-liquid two-phase refrigerant that has flowed into the outdoor heat exchanger 40 exchanges heat with the air flowing on the fin side of the outdoor heat exchanger 40 to become a gas refrigerant. The gasified refrigerant returns to the compressor 10 through the pipe 96 , the four-way valve 100 and the pipe 97 .

Here, for example, a case where the air conditioning load is reduced and the operating frequency of the compressor 10 is reduced will be described.

When the air conditioning load is small, the controller 200 lowers the operating frequency of the compressor 10 until the air conditioning capacity matches the air conditioning load. When the operating frequency of the compressor 10 is lowered, the refrigerant circulation amount of the refrigerant circuit 150 is lowered. When the refrigerant circulation amount decreases, the air conditioning capacity (=refrigerant circulation amount×indoor unit enthalpy difference) decreases.

Also, when the operating frequency of the compressor 10 decreases, the pressure difference generated in the compressor 10 decreases, and the temperature difference between the refrigerant temperature and the air temperature in the indoor heat exchanger 20 and the outdoor heat exchanger 40 decreases. As the temperature difference becomes smaller, heat exchange becomes more difficult and the discharge temperature becomes less likely to rise, resulting in a decrease in the degree of superheat of the discharged refrigerant.

Therefore, in order to secure the temperature difference, the control device 200 controls the LEV 111 to secure the throttling pressure difference.

However, in order to accurately achieve a low air conditioning capacity of 1 kW or less, when operating the compressor 10 at a reduced frequency, it is necessary to accurately control the opening of the LEV 111 to a small opening. In this case, it is necessary to reduce the number of pulses for commanding the opening, which is transmitted from the control device 200 to the motor drive circuit 203 . Here, there is a problem that the valve opening point at which the electronic expansion valve shifts from the closed state to the open state varies from electronic expansion valve to electronic expansion valve. Such variations in the valve opening point are caused by variations in the mounting method of the stepping motor, the dimensions of the valve body, and the dimensions of the valve seat. Therefore, use in a region where the number of pulses is small may lead to an unintended valve closing state due to manufacturing variations in valve opening point, and is not recommended.

For this reason, International Publication No. 2013/103061 indicates that the characteristics of the expansion valve are individually measured in advance and the valve opening point data is provided as a barcode. However, by individually measuring the characteristics of the expansion valves in advance or registering the characteristics of the expansion valves in the control device of the air conditioner, the number of manufacturing processes increases.

Therefore, in the present embodiment, when the opening of the LEV 111 decreases to a certain opening close to the lower limit at which stable use is possible and the degree of superheat of the discharged refrigerant is insufficient, the LEV 111 is intentionally fully closed or completely closed. A close second opening degree is set, and then the opening degree is increased to the first opening degree, which is repeated.

FIG. 3 is a waveform diagram for explaining changes in the degree of opening of the electronic expansion valve. In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates the Cv value corresponding to the degree of opening of the electronic expansion valve. The Cv value indicates the capacity coefficient of the valve.

When the period of setting the opening of the LEV 111 to the first degree of opening (Cv value=CvA) and the period of setting the degree of opening of the LEV 111 to the second degree of opening (Cv value=CvB) are repeated at a certain time ratio in the cycle tC, the time ratio An arbitrary average opening (Cv value=CvC) between the first opening and the second opening can be realized according to .

The control device 200 adjusts the periods tA and tB in FIG. 3 so that the Cv value of the LEV 111 becomes the desired Cv value in order to achieve the desired degree of superheat of the discharged refrigerant when the air conditioning load is small. In other words, the Cv value changes according to the time ratio (tA/tC or tB/tC), so the controller 200 changes the time ratio to obtain the desired Cv value.

FIG. 4 is a diagram for explaining the relationship between the Cv value of the LEV 111 and the number of pulses indicating the degree of opening. The control device 200 outputs the number of pulses corresponding to the opening of the valve to the motor drive circuit 203 as a command value. The number of pulses can vary from 0 to n. The number of n varies depending on the specifications of the electronic expansion valve, etc. For example, in the example of FIG. 4, n=500 and 1/4×n=125. Let Cvmin be the Cv value of the opening indicated by the command value 0, and let Cvmax be the Cv value of the opening indicated by the command value 500, which is the maximum number of pulses. It can be a value. If Cvmin<Cvmax, Cvmin and Cvmax can be determined appropriately.

FIG. 5 is a diagram for explaining the positions of CvA and CvB in FIG. 3 at the opening shown in FIG. In FIG. 5, both the command value A corresponding to CvA and the command value B corresponding to CvB are less than 1/4 (eg 125) of the pulse number n (eg 500) corresponding to the maximum controllable opening. It is shown to be the number of pulses.

As shown in FIG. 3, the opening degree of the expansion valve corresponding to the Cv value=CvC realized by controlling the pulse is used when the air conditioning load is extremely small. This is used when there is a risk that the valve will be closed without doing so. Therefore, such a Cv value cannot be realized when the number of pulses A and B is greater than 1/4 of n.

For example, it is conceivable to set the pulse number B to zero, the pulse number A to 500, and make tA in FIG. 3 extremely shorter than tB. Since the response speed at which the Cv value changes is slow, it becomes difficult to achieve a desired Cv value with high accuracy.

Therefore, in the present embodiment, the command values A and B have a relationship of 0≦B<A≦n×1/4. Also, if the cycle tC in FIG. 3 is too long, CvC as an average value cannot be achieved, so it is desirable that the cycle tC is one minute or less.

FIG. 6 is a flow chart for explaining the operation mode switching control executed in the air conditioning system of the first embodiment.

In step S1, the control device 200 determines whether the magnitude of the difference between the room temperature Tr and the set temperature Tset is smaller than the determination value Tth1. The magnitude of the air conditioning load is determined based on this.

If |t−Tset|<Tth1 (YES in S1), the control device 200 determines in step S2 whether or not the degree of superheat of the discharged refrigerant (hereinafter referred to as discharge SH) is smaller than the determination value Tth2. . Thereby, the state of the refrigerant circuit 150 is determined.

If discharge SH<Tth2 (YES in S2), in step S3, control device 200 repeatedly outputs command values A and B as described with reference to FIGS. The LEV 111 is controlled to periodically repeat (first degree of opening, Cv value=CvA) and L (second degree of opening, Cv value=CvB). As a result, an opening degree of Cv value=CvC is realized as an average value.

On the other hand, if |t−Tset|≧Tth1 (NO at S1) or discharge SH≧Tth2 (NO at S2), in step S4, normal control is performed to designate the opening of the LEV 111 with one command value. is executed.

Here, in FIG. 3, the time ratio tA/tC may be a fixed value (for example, 50%), but by changing the time ratio, the average opening of the LEV 111 can be changed with finer precision.

FIG. 7 is a flowchart showing an example of the processing contents of step S3 in FIG. First, in step S11, the control device 200 determines whether or not the ejection SH is smaller than the determination value Tth2.

If discharge SH<Tth2 (YES in S11), in step S12, the control device 200 reduces the time tA, which is the first opening degree CvA with the high LEV opening degree, and reduces the time ratio tA/tC. Then, the process of step S11 is executed again.

If the initial value of the time ratio in step S12 is set to 100%, the time ratio is adjusted so that the discharge SH becomes the desired value, and after the time ratio is adjusted (YES in S11), the adjusted time ratio is fixed. , the LEV opening degree H/L repetitive operation is executed for a certain period of time (S13).

As described above, in the first embodiment, due to manufacturing variations, it is difficult to establish a correspondence between the pulse command value and the opening of the LEV 111 or the Cv value. The LEV 111 can be controlled to the corresponding aperture state. For this reason, it becomes easier to perform low-capacity operation in which the operating frequency of the compressor is lowered.

Embodiment 2.
In Embodiment 1, as shown in FIG. 7, an appropriate time ratio is determined by changing the time ratio while detecting the value of the ejection SH.

In the second embodiment, the memory 202 of the control device 200 stores the Cv value of the expansion valve for increasing the discharge SH to a specified value or more according to the indoor and outdoor temperatures. A refrigeration cycle apparatus characterized by adjusting the time ratio of the opening of the LEV 111 within a certain period of time to obtain a desired Cv value (CvC) will be described.

The flow and state of the refrigerant in the refrigeration cycle device are the same as in Embodiment 1, so the description will not be repeated.

FIG. 8 is a flowchart for explaining the processing executed in the second embodiment. FIG. 8 shows the process of step S3A executed in the second embodiment instead of step S3 shown in FIG.

First, in step S21, the control device 200 acquires the outdoor temperature Te from the temperature sensor 103 and acquires the indoor temperature Tr from the temperature sensor 102. Then, in step S22, the control device 200 determines the Cv value from the map M1 pre-stored in the memory 202, and calculates the time ratio corresponding to the determined Cv value in step S23.

FIG. 9 is a diagram showing an example of the map M1 used in the second embodiment. As shown in FIG. 9, Cv values corresponding to expansion valve opening degrees corresponding to combinations of indoor and outdoor temperatures are stored as a table in memory 202 incorporated in control device 200 . Control device 200 measures indoor and outdoor air temperatures Tr and Te with

temperature sensors

102 and 103 such as thermistors, calculates a time ratio for realizing a Cv value according to the air temperature, and controls LEV 111 .

Although the Cv value is stored in the map in FIG. 9, the time ratio according to the air temperature may be directly stored instead of the Cv value. FIG. 10 shows another map M1A used in the second embodiment. In FIG. 9, the higher the outdoor temperature and the lower the indoor temperature (upper left in FIG. 9), the smaller the Cv value, and the lower the outdoor temperature and the higher the indoor temperature (lower right in FIG. 9), the larger the Cv value. Therefore, in order to decrease the Cv value, the time tB in FIG. 3 should be lengthened, and the time ratio (tB/tC in FIG. 3) should be increased. Therefore, in the map M1A of FIG. 10, the higher the outdoor temperature and the lower the indoor temperature (in the upper left direction in FIG. 10), the larger the time ratio RB (=tB/tC). lower right direction) The time ratio RB becomes smaller.

In the second embodiment, as in the first embodiment, by controlling the LEV 111 with a time ratio, it is possible to achieve a Cv value with a small degree of opening, which is difficult to control, on a time average basis, and to ensure the discharge SH. Furthermore, by storing the desired Cv value that changes depending on the indoor and outdoor air temperature in the memory 202 in advance as a table, in the actual product, the time ratio can be immediately determined simply by measuring the indoor and outdoor temperatures with the

temperature sensors

102 and 103. Therefore, faster control can be realized.

Embodiment 3.
In the third embodiment, the opening degree of the LEV 111 is adjusted within a certain period of time to obtain a desired Cv value (CvC) by adjusting the time ratio (tB/tC in FIG. 3) according to the operating frequency of the compressor 10. Characterized by

In general control, the refrigerant flow and the refrigerant state in the refrigeration cycle device are the same as in Embodiment 1, so the description will not be repeated.

FIG. 11 is a diagram showing the relationship between the operating frequency of the compressor and the desired Cv value. In general, increasing the operating frequency also increases the desired Cv value, as shown in FIG. However, as explained in the first embodiment, it is difficult to control the degree of opening of the expansion valve with a small Cv value. Therefore, in the third embodiment, the desired Cv value is realized by changing the time ratio shown in FIG. 3 at frequencies where a small Cv value is required.

FIG. 12 is a diagram for explaining the time ratio control executed in the third embodiment. In Embodiment 3, the time ratio (tB/tC) of the expansion valve opening degree corresponding to each operating frequency of compressor 10 is stored as a table in memory 202 built in controller 200 . The control device 200 calls the time ratio corresponding to the operating frequency from the memory 202 and performs control.

In Embodiment 1, the time ratio is set to tA/tC, and the time ratio is 100%, indicating a state of continuous large opening, but in FIG. 12, the time ratio is set to tB/tC, so the time ratio is 0 %, the degree of opening is large and continuous.

Therefore, in FIG. 12, when the operating frequency is between fth and fmax, the LEV 111 is continuously operated with one opening command value as in normal control. ) and the second degree of opening (corresponding to CvB) are repeated. As the operating frequency decreases from fth to fmin, the time ratio tB/tC increases and the Cv value decreases.

According to Embodiment 3, similarly to Embodiment 1, the opening command value is controlled so that the opening of the LEV 111 is repeated between the first opening and the second opening at a certain time ratio. As a result, the Cv value in the region smaller than the minimum Cv value that can be stably controlled can be realized by time average, and the ejection SH can be ensured. Furthermore, by storing in advance the desired Cv value that varies depending on the operating frequency as a table, better control can be realized in the actual product simply by reading the time ratio according to the frequency.

Embodiment 4.
The fourth embodiment is characterized in that the LEV 111 is controlled based on the indoor air temperature, the outdoor air temperature, and the time ratio according to the operating frequency by combining the first to third embodiments.

The refrigerant flow and refrigerant state in a general refrigeration cycle device are the same as in Embodiment 1, so the description will not be repeated.

FIG. 13 is a flow chart for explaining the operation mode switching control executed in the air conditioning system of the fourth embodiment. In the flowchart of FIG. 13, in the flowchart of FIG. 6, step S2A is added after step S2, and step S3B is executed instead of step S3.

First, in step S1, the control device 200 determines whether the magnitude of the difference between the room temperature Tr and the set temperature Tset is smaller than the determination value Tth1. The magnitude of the air conditioning load is determined based on this.

If |t−Tset|<Tth1 (YES in S1), the control device 200 determines in step S2 whether or not the discharge SH is smaller than the determination value Tth2. Thereby, the state of the refrigerant circuit 150 is determined.

If the discharge SH<Tth2 (YES in S2), in step S2A, the control device 200 determines whether or not the operating frequency f of the compressor 10 is lower than the determination value fth. Thus, it is determined whether or not the frequency range is from fmin to fth in which the time ratio control as shown in FIG. 12 is introduced.

If f<fth (YES in S2A), in step S3B, the controller 200 repeatedly outputs the command values A and B so that the opening of the LEV 111 is H (first opening, Cv value=CvA). and L (second opening, Cv value=CvB) are periodically repeated. As a result, an opening degree of Cv value=CvC is realized as an average value.

On the other hand, if |t−Tset|≧Tth1 (NO at S1), or if ejection SH≧Tth2 (NO at S2), or if f≧fth (NO at S2A), the opening degree of the LEV 111 is adjusted in step S4. Normal control specified by one command value is executed.

FIG. 14 is a flowchart for explaining the process of step S3B in FIG. First, in step S31, the control device 200 acquires the outdoor temperature Te from the temperature sensor 103, acquires the indoor temperature Tr from the temperature sensor 102, and further acquires the operating frequency f from the control processing routine of the compressor 10. FIG. Then, in step S32, the control device 200 determines the Cv value from the map M2 pre-stored in the memory 202, and calculates the time ratio corresponding to the determined Cv value in step S33.

FIG. 15 is a diagram showing an example of the map M2 used in the fourth embodiment. As shown in FIG. 15, Cv values corresponding to expansion valve opening degrees corresponding to combinations of indoor/outdoor temperatures and operating frequencies are stored as a table in memory 202 incorporated in controller 200 . Control device 200 calculates a time ratio for realizing a Cv value according to air temperatures Tr, Te and operating frequency f, and controls LEV 111 .

Although the Cv value is stored in the map in FIG. 15, the time ratio according to the air temperature may be directly stored instead of the Cv value.

As described above, in the fourth embodiment, the memory 202 stores the Cv value or the time ratio of the expansion valve opening according to the air temperatures Tr, Te and the operating frequency f as a table. The controller 200 calls up the Cv value or the time ratio corresponding to the air temperatures Tr and Te during operation and the operating frequency f from the memory 202 and controls the LEV 111 .

According to Embodiment 4, similarly to Embodiment 1, the opening command value is controlled such that the opening of the LEV 111 is repeated between the first opening and the second opening at a certain time ratio. As a result, the Cv value in the region smaller than the minimum Cv value that can be stably controlled can be realized by time average, and the ejection SH can be ensured. Furthermore, by combining the second embodiment and the third embodiment, better control can be achieved.

(summary)
Air conditioner 1 of the present embodiment includes refrigerant circuit 150 and control device 200 . Refrigerant circuit 150 is configured such that refrigerant circulates through compressor 10 ,

condensers

40 and 20 , LEV 111 , and

evaporators

20 and 40 . The opening degree of the LEV 111 is variable between the lower limit opening degree and the upper limit opening degree. The control device 200 causes the LEV 111 to alternately repeat the first degree of opening CvA and the second degree of opening CvB smaller than the first degree of opening CvA within a range equal to or less than 1/4 of the upper limit degree of opening. configured to control.

Preferably, if n is a natural number, the control device 200 designates a plurality of opening degrees between the lower limit opening degree Cvmin and the upper limit opening degree Cvmax by command values from 0 to n. The control device 200 outputs command values so as to alternately repeat a first command value A and a second command value B smaller than the first command value A within a range of command values equal to or less than 1/4 of n. configured as

Preferably, the air conditioner 1 includes an outdoor unit 2 housing one of the

condensers

40, 20 and the

evaporators

20, 40 and a compressor, and any one of the

condensers

40, 20 and the

evaporators

20, 40 It further includes an indoor unit 3 that accommodates the other. When the low-capacity operating condition including the first condition that the difference between the temperature Tr of the air sucked into the indoor unit 3 and the set temperature Tset is smaller than the threshold value Tth1 is satisfied ( FIG. 6 , S1 YES), the LEV 111 is controlled to alternately repeat the first opening degree CvB and the second opening degree CvA.

More preferably, the low-capacity operating condition satisfies the first condition and the second condition that the value of the degree of superheat of the refrigerant discharged from the compressor 10 is equal to or less than the specified value Tth2 (FIG. 6, in S2 YES).

More preferably, as shown in FIG. 7, the control device 200 controls the first opening and Adjust the time ratio with the second degree of opening.

Preferably, the control device 200 includes an arithmetic processing unit 201 and a memory 202. The memory 202 uses the indoor temperature and the outdoor temperature as input data, and corresponds to the time ratio or the time ratio between the first opening and the second opening in the cycle in which the first opening and the second opening are alternately repeated. A map as shown in FIG. 9 is stored in which the capacity coefficient (Cv value) of the LEV 111 to be measured is output data. Arithmetic processing unit 201 controls LEV 111 using a map.

Preferably, the control device 200 includes an arithmetic processing unit 201 and a memory 202. The memory 202 uses the operating frequency of the compressor 10 as input data, and corresponds to the time ratio or the time ratio between the first opening and the second opening in the cycle in which the first opening and the second opening are alternately repeated. A map is stored in which the capacity coefficient (Cv value) of the expansion valve is used as output data. Arithmetic processing unit 201 controls LEV 111 using a map.

Preferably, the control device 200 includes an arithmetic processing unit 201 and a memory 202. The memory 202 uses the room temperature, the outside air temperature, and the operating frequency of the compressor as input data, and stores the first opening degree and the second opening degree in a cycle in which the first opening degree and the second opening degree are alternately repeated. A map such as that shown in FIG. 15 is stored in which output data is the time ratio or the capacity coefficient of the expansion valve corresponding to the time ratio. Arithmetic processing unit 201 controls LEV 111 using a map.

The embodiments disclosed this time should be considered illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the scope of the claims rather than the above-described description of the embodiments, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

1 air conditioner, 2 outdoor unit, 3 indoor unit, 10 compressor, 20, 40 heat exchanger, 90, 92, 94, 96, 97, 99 piping, 100 four-way valve, 101, 102, 103, 106, 107 Temperature sensor, 111 LEV, 112 stepping motor, 113 valve body, 150 refrigerant circuit, 200 control device, 201 arithmetic processing unit, 202 memory, 203 motor drive circuit, E, F, G, H, P1, P3, P4 ports.

Claims

a refrigerant circuit configured to circulate refrigerant through a compressor, a condenser, an expansion valve, and an evaporator;
a control device that controls the expansion valve;
The expansion valve has a variable opening between a lower limit opening and an upper limit opening,
The control device controls the expansion valve so as to alternately repeat a first degree of opening and a second degree of opening smaller than the first degree of opening within a range of a quarter of the opening degree of the upper limit or less. An air conditioner configured to control the
where n is a natural number, the control device designates a plurality of opening degrees between the lower limit opening degree and the upper limit opening degree by command values from 0 to n,
The control device outputs the command value so as to alternately repeat a first command value and a second command value smaller than the first command value within a range of the command value equal to or less than 1/4 of n. , The air conditioner according to claim 1.
The air conditioner is
an outdoor unit housing one of the condenser and the evaporator and the compressor;
and an indoor unit housing the other of the condenser and the evaporator,
When a low-capacity operating condition including a first condition that a difference between the temperature of the air sucked into the indoor unit and a set temperature is smaller than a threshold is satisfied, the controller controls the first opening and the The air conditioner according to claim 1, wherein said expansion valve is controlled so as to alternately repeat said second degree of opening.
4. The low-capacity operating condition according to claim 3, wherein the low-capacity operating condition is satisfied when the first condition is satisfied and the second condition is satisfied that the value of the degree of superheat of the refrigerant discharged from the compressor is equal to or less than a specified value. An air conditioner as described.
The control device adjusts the first opening degree and the second opening degree in a cycle in which the first opening degree and the second opening degree are alternately repeated so that the value of the degree of superheat approaches the specified value. 5. The air conditioner according to claim 4, wherein the time ratio is adjusted.
The control device is
comprising an arithmetic processing unit and a memory,
The memory uses indoor temperature and outdoor temperature as input data, and the time ratio between the first opening and the second opening in a cycle in which the first opening and the second opening are alternately repeated, or storing a map whose output data is the capacity coefficient of the expansion valve corresponding to the time ratio;
The air conditioner according to claim 1, wherein said arithmetic processing unit controls said expansion valve using said map.
The control device is
comprising an arithmetic processing unit and a memory,
The memory uses the operating frequency of the compressor as input data, and the time ratio between the first opening and the second opening in a cycle in which the first opening and the second opening are alternately repeated, or the storing a map having as output data the capacity coefficient of the expansion valve corresponding to the time ratio;
The air conditioner according to claim 1, wherein said arithmetic processing unit controls said expansion valve using said map.
The control device is
comprising an arithmetic processing unit and a memory,
The memory receives the indoor temperature, the outdoor temperature, and the operating frequency of the compressor as input data, and stores the first opening and the second opening in a cycle in which the first opening and the second opening are alternately repeated. Storing a map whose output data is a time ratio with two degrees of opening or a capacity coefficient of the expansion valve corresponding to the time ratio;
The air conditioner according to claim 1, wherein said arithmetic processing unit controls said expansion valve using said map.