JP2000186864A - Control method for motor-operated expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify control of a motor operated expansion valve when a plurality of indoor units are provided. SOLUTION: An air conditioner sets control sets (steps 230, 232, 250, 252) of each motor operated expansion valve with PI operation based upon target discharge temperature. Thereafter, in a cooling mode thick tube temperature for each indoor unit is read, and on the basis of a deviation among the thick tube temperatures a correction amount of an opening of each motor driven expansion valve is set (steps 254 to 258). Based upon the amount of correction set as such the control steps are corrected (steps 242, 260) and operation is carried out to provide corrected control steps for each motor operated expansion valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor which is provided in an outdoor unit of an air conditioner in which a plurality of indoor units are connected to one outdoor unit and adjusts a flow rate of refrigerant to each indoor unit. The present invention relates to a method for controlling an expansion valve.

[0002]

2. Description of the Related Art In an air conditioner (hereinafter referred to as "air conditioner") for air-conditioning a room, air blown out of the indoor unit is circulated by circulation of a refrigerant in a refrigeration cycle formed between an indoor unit and an outdoor unit. Is controlling the temperature. At this time, in the air conditioner, an electric expansion valve is provided in the refrigeration cycle, a target discharge temperature which is a target temperature of the refrigerant discharged from the compressor is set, and the opening degree of the electric expansion valve is set based on the target discharge temperature. Is controlled to adjust the flow rate of the refrigerant.

There is a so-called multi-type air conditioner in which a plurality of indoor units are connected to one outdoor unit.

In a multi-type air conditioner, an electric expansion valve is further provided for each of a plurality of indoor units to adjust the flow rate of the refrigerant to each of the indoor units.

[0005]

However, in such an air conditioner, the distribution flow rate of the refrigerant to each indoor unit is adjusted in addition to the electric expansion valve that adjusts the overall refrigerant flow rate based on the target discharge temperature. The provision of the electric expansion valve complicates the control of the opening of the electric expansion valve to obtain the air-conditioning capacity according to the requirements of the individual indoor units.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances. In an air conditioner in which a plurality of indoor units are connected to one outdoor unit, electric expansion of the air conditioner is simplified. The purpose is to propose a control method of the valve.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a refrigerant piping system comprising at least an outdoor unit having a compressor, an electric expansion valve, and a heat exchanger and at least a plurality of indoor units having a heat exchanger so that a refrigeration cycle is established. In the air conditioner performing heat exchange between the air blown into the room to be air-conditioned and the refrigerant circulated in the refrigeration cycle, the air conditioner is provided in the outdoor unit corresponding to each of the plurality of indoor units. A method of controlling an electric expansion valve for adjusting a flow rate of a refrigerant to a corresponding indoor unit, wherein an opening degree of each electric expansion valve is set to a target discharge temperature which is a target value of a refrigerant temperature discharged from a compressor. And the refrigerant temperature detecting means passes through each of the plurality of indoor unit heat exchangers to the outdoor unit. Detected refrigerant temperature, find the deviation of the refrigerant temperature of each of the plurality of indoor units based on the refrigerant temperature of any of the indoor units, and according to the deviation of the electric expansion valve corresponding to each indoor unit The opening is corrected.

According to the present invention having the above-described structure, the opening degree of the electric expansion valve corresponding to each of the plurality of indoor units is set based on the target discharge temperature. At the same time, the opening of the electric expansion valve provided for each indoor unit is corrected based on the refrigerant temperature of the thick pipe corresponding to each indoor unit.

At this time, in the cooling mode, for example, the refrigerant temperature having the lowest temperature is set as a reference temperature, and the deviation of the refrigerant temperature of each indoor unit from the reference temperature is calculated. Based on this deviation, the refrigerant temperatures become substantially the same. Thus, the opening degree of each electric expansion valve is corrected.

Thus, the flow rate of the refrigerant circulated in the refrigeration cycle and the flow rate of the refrigerant to each of the plurality of indoor units can be adjusted, so that the air-conditioned room can be appropriately cooled in each of the indoor units. .

According to the present invention, in the present invention, the amount of change in the deviation is calculated for each of the plurality of indoor units, and the calculation results are included in the electric expansion valve corresponding to each indoor unit. It is more preferable to correct the opening.

This makes it possible to more appropriately correct the degree of opening of each electric expansion valve.

Further, the present invention provides an outdoor unit having at least a compressor, an electric expansion valve, and a heat exchanger, and a plurality of indoor units having at least a heat exchanger connected by refrigerant piping so that a refrigeration cycle is established. In an air conditioner that performs heat exchange between air blown into a room to be air-conditioned and refrigerant circulated in a refrigeration cycle, an air conditioner is provided in an outdoor unit corresponding to each of the plurality of indoor units. A method of controlling an electric expansion valve for adjusting a flow rate of a refrigerant to an indoor unit, wherein an opening degree of each electric expansion valve is set based on a target discharge temperature which is a target value of a refrigerant temperature discharged from a compressor. At the same time, the coil temperature of the heat exchanger is detected by the coil temperature detecting means provided in each of the plurality of indoor units. A deviation of the coil temperature of each indoor unit is obtained based on the coil temperature of the indoor unit, and the opening degree of the electric expansion valve corresponding to each indoor unit is corrected according to the deviation. .

According to this invention, the opening degree of the electric expansion valve corresponding to each of the plurality of indoor units is set based on the target discharge temperature, and the temperature (coil) of the heat exchanger of each indoor unit is set. Based on the temperature, the opening degree of the electric expansion valve provided corresponding to each of the indoor units is corrected.

At this time, in the heating mode, for example, the coil temperature of each indoor unit with respect to this reference temperature is calculated based on the lowest coil temperature as a reference temperature. The opening degree of each electric expansion valve is corrected so that

Thus, the flow rate of the refrigerant circulated in the refrigeration cycle and the flow rate of the refrigerant to each of the plurality of indoor units can be adjusted, so that each indoor unit can appropriately heat the room to be air-conditioned.

As described above, according to the present invention, the flow rate of the refrigerant to each indoor unit can be adjusted by the electric expansion valve corresponding to each of the plurality of indoor units, and the flow rate of the refrigerant circulated in the refrigeration cycle. Therefore, it is not necessary to separately provide an electric expansion valve for adjusting the flow rate of the refrigerant, and the number of electric expansion valves of the multi-type air conditioner can be reduced.

[0018]

Embodiments of the present invention will be described below.

FIGS. 1 and 2 show a schematic configuration of an air conditioner (hereinafter referred to as "air conditioner 10") applied to the present embodiment. The air conditioner 10 is of a multi-type composed of a plurality of (two as an example in the present embodiment) indoor units 12 and one outdoor unit 14. In the following description, when distinguishing the two indoor units 12, the indoor units 12A, 12A
B will be described.

Between the indoor unit 12 and the outdoor unit 14, there is a thick refrigerant pipe 16 for circulating a refrigerant.
A and the refrigerant pipe 16B of a thin tube.

As shown in FIG. 2, each indoor unit 12 is provided with a heat exchanger 18, and one end of each of the refrigerant pipes 16A and 16B is connected to the heat exchanger 1.
8 is connected.

The outdoor unit 14 is provided with a pair of valves 20A and 20B corresponding to the number of the indoor units 12. The other end of the refrigerant pipe 16A is connected to a valve 20A of the outdoor unit 14. The valve 20A is connected inside the outdoor unit 14, and further connected to a four-way valve 24 via a muffler 22A.

An accumulator 28 connected to the suction side of the compressor 26 and a muffler 22B connected to the discharge side of the compressor 26 are connected to the four-way valve 24, respectively. In addition, in the outdoor unit 14,
A heat exchanger 30 is provided. This heat exchanger 30
One is connected to the four-way valve 24, and the other is connected to the capillary tube 32. The strainer 34 and the modulator 38 are connected to the capillary tube 32, and the tip of the modulator 38 is branched and connected to each valve 20B.

The other end of the cold pipe 16B is connected to a valve 20B, thereby forming a closed circulation path of a refrigerant forming a refrigeration cycle between the indoor unit 12 and the outdoor unit 14. Also, the outdoor unit 14
Among them, electric expansion valves 36A and 36B are provided at an intermediate portion of each pipe branched toward the valve 20B, and each of the indoor units 12 is provided in accordance with the degree of opening of the electric expansion valve 36. The flow rate of the refrigerant circulated in the heat exchanger 18 is adjusted. The electric expansion valves 36A and 36B are referred to as electric expansion valves 36 unless otherwise specified.

In the air conditioner 10, when the compressor 26 is driven, the refrigerant circulates through the refrigeration cycle. FIG.
As shown by arrows, the flow of the refrigerant during the heating operation (heating mode) and during the cooling or dehumidifying operation (cooling mode)
The operation mode of the air conditioner 10 is switched between a cooling mode (including a dry mode) and a heating mode by switching the four-way valve 24, and the indoor units 12A and 12B are controlled by controlling the valve opening of the electric expansion valves 36A and 36B. The evaporation temperature of the refrigerant in each of the heat exchangers 18 is adjusted.

As shown in FIG. 1, the indoor unit 12
Is provided with a casing 42 in which a suction port 48 and an outlet port 50 are formed, and is fixed at a predetermined height to a wall surface or the like of a room to be air-conditioned by a base plate (not shown) provided on a back surface of the casing 42.

A cross flow fan (not shown) is arranged in the casing 42 together with the heat exchanger 18.
The air in the room is sucked into the casing 42 from the suction port 48 by the operation of the cross flow fan. The air sucked into the casing 42 passes through the heat exchanger 18 and is then blown into the room from the outlet 50. This air passes through the heat exchanger 18 and is
Heat is exchanged with the refrigerant circulating in the inside, and the air becomes air-conditioned (air-conditioned air) for air-conditioning the room.

The outlet 50 of the indoor unit 12 is provided with upper and lower flaps 54 and left and right flaps (not shown). The left and right flaps and upper and lower flaps 54 control the direction of the conditioned air blown from the outlet 50. be changed. In the air conditioner 10, the left and right flaps provided on the inner side of the upper and lower flaps 54 can be manually turned, and the air conditioning blows out from the outlet 50 mainly by controlling the directions of the upper and lower flaps 54. Controls the wind direction. Note that the indoor unit 12 may control the directions of the left and right flaps together with the upper and lower flaps 54. The indoor units 12A and 12B may have the same structure, but may have different structures as long as they have the heat exchanger 18.

FIG. 3 shows an example of a schematic configuration of the indoor unit 12. The indoor unit 12 is provided with a power supply board 56 and a control board 58. The power supply board 56 is provided with a motor power supply 62, a control circuit power supply 64, a serial power supply 66, and a drive circuit 68 so that power (for example, single-phase 100V AC power) for operating the air conditioner 10 is supplied. It has become.
Further, a serial circuit 70,
A microcomputer (microcomputer 7) together with the drive circuit 72
4) is provided.

The drive circuit 68 of the power supply board 56 is connected to a fan motor 76 (for example, a DC brushless motor) for driving the above-described cross flow fan, and receives a control signal from a microcomputer 74 provided on the control board 58. The driving power is supplied from the motor power supply 62 according to. At this time, the microcomputer 74 controls the output voltage from the drive circuit 68 by changing the output voltage in a range of 12 V to 36 V in 256 steps, and adjusts the amount of the conditioned air blown out from the outlet 50 of the indoor unit 12.

The drive circuit 7 of the control board 58
An upper / lower flap motor 78 for operating the upper / lower flap 54 is connected to 2. The upper and lower flap motors 78
The upper and lower flaps 54 are operated in response to a control signal from the microcomputer 74. Thereby, the conditioned air is blown from the outlet 50 of the indoor unit 12 to a desired area.

The microcomputer 74 is connected to a room temperature sensor 84 for detecting the room temperature and a heat exchange temperature sensor 86 for detecting the coil temperature of the heat exchanger 18, and a service LED provided on the control board 58. And an operation changeover switch 88 are connected. The operation switch 88 is switched between “normal operation” and “test operation” for maintenance and the like, and “stop” for stopping the operation of the air conditioner 10. The air conditioner 10 is used with the operation changeover switch 88 set to “normal operation”. As a result, the contact 88A is closed, and operation power is supplied to the indoor unit 12. The operation changeover switch 8
By bringing 8 into the "stop" position, the contact 88A is opened and the supply of power to the indoor unit 12 is stopped. The service LED is turned on at the time of maintenance to notify a service person of a self-diagnosis result.

The indoor unit 12 includes an outdoor unit 14
There is provided a terminal block 90 to which wiring is connected. Wirings for supplying power from the outdoor unit 14 to the indoor unit 12 and wiring for serial communication can be connected to the terminals 90A, 90B, 90C of the terminal block 90.

The serial circuit 70 connected to the microcomputer 74 and the serial power supply 66 of the power supply circuit 56 is connected to the outdoor unit 14 via the terminals 90B and 90C.
Serial communication is possible between the device and the outdoor unit 14.

On the other hand, a display substrate 82 is connected to the microcomputer 74. The display board 82 is provided with a display unit provided with operation display LEDs and the like, and a light receiving unit provided with a light receiving element for receiving an operation signal transmitted from a remote control switch (not shown). Thereby, in the air conditioner 10, when the remote control switch is operated,
While performing serial communication between the indoor unit 12 and the outdoor unit 14, the air-conditioning operation is performed so that the room is in the air-conditioning state set by the remote control switch.

FIG. 4 shows a schematic configuration of the outdoor unit 14. The outdoor unit 14 is provided with a terminal block 92, and terminals 92A, 92B, 92 of the terminal block 92 are provided.
The wiring for serial communication is connected to terminals 92B and 92C of C. In addition, operating power is supplied to the outdoor unit 14 via the terminals 90A and 90B.

The outdoor unit 14 includes a rectifying board 9
4. A control board 96 is provided. The control board 96 is provided with noise filters 100A, 100B, 100C, a serial circuit 102, a switching power supply 104, and the like, together with the microcomputer 98.

The rectifying board 94 is provided with a noise filter 100A.
Rectifies the power supplied through the
Switching power supply 1 after smoothing via 0B and 100C
04. The switching power supply 104 is connected to an inverter circuit 106 together with the microcomputer 98.
Power having a frequency corresponding to the control signal output from the microcomputer 98 is supplied from the inverter circuit 106 to the compressor motor 1.
08 to drive the compressor 26 to rotate.

The microcomputer 98 is connected to the inverter circuit 1
06 is controlled so that the frequency of the electric power output from the control unit 06 is off (0 Hz) or in a predetermined range of 14 Hz or more (the upper limit is limited by the operating current or the like). The rotation speed (operating frequency) is changed, and the capacity of the compressor 26 (the cooling / heating capacity of the air conditioner 10) is controlled.

The control board 96 includes a four-way valve 2
4 and a fan motor 110 for driving a fan (not shown) for cooling the heat exchanger 30 and a fan motor condenser 110A.

The microcomputer 98 switches the four-way valve 24 according to the operation mode, and turns on / off the fan motor 110 and the compressor motor based on a control signal from the indoor unit 12 and detection results of various sensors described later. 108 (compressor 26).

On the other hand, each of the electric expansion valves 36A and 36B provided in the outdoor unit 14
And the microcomputer 98 controls opening and closing of the electric expansion valves 36A and 36B. Electric expansion valve 36
A and 36B are provided with a stepping motor (not shown), which is opened and closed by driving the stepping motor. The microcomputer 98 controls this stepping motor by, for example, 512 steps (control steps are 0 to 511).
The degree of opening (the range from fully closed to fully open) of the electric expansion valves 36A and 36B is controlled in the range of.

The outdoor unit 14 includes an outside air temperature sensor 112 for detecting the outside air temperature, a coil temperature sensor 114 for detecting the temperature of the refrigerant coil of the heat exchanger 30, and a compressor temperature sensor 1 for detecting the temperature of the compressor 26.
16, refrigerant temperature sensors 150A, 150B, 15
2A and 152B are provided, and these sensors are connected to the microcomputer 98. Refrigerant temperature sensor 150
A, 150B (when not particularly distinguished, the refrigerant temperature sensor 150) detects the temperature (refrigerant temperature) of the thick refrigerant pipes 16A, 16B, and the refrigerant temperature sensors 152A, 152B (particularly distinguished). When not performed, the refrigerant temperature sensor 152) detects the temperature (refrigerant temperature) of the narrow refrigerant pipe 16B.

The microcomputer 98 includes the indoor unit 1
The temperature of the heat exchanger 18 detected by the heat exchange temperature sensor 86 provided in each of 2A and 12B is input as a coil temperature by serial communication.

In the air conditioner 10, the indoor unit 12A,
When the operation of the indoor unit 12B is started, the indoor units 12A,
The 2B microcomputer 74 sets the operating frequency of the compressor 26 in accordance with the required air conditioning capacity based on the indoor temperature and the set temperature, and the outdoor unit 14 operates to drive the compressor 26 at the set operating frequency. At this time, in the microcomputer 98 of the outdoor unit 14, the electric expansion valves 36A, 3A corresponding to the indoor units 12A, 12B are used.
The air conditioning capacity of the indoor units 12A and 12B is adjusted by controlling the opening degree of the indoor unit 6B.

The basic operation of the air conditioner 10 is the same as that of a conventionally known multi-type air conditioner, and a detailed description of the basic operation of the air conditioner 10 will be omitted in the present embodiment.

In the air conditioner 10, a target discharge temperature (target discharge temperature) which is the temperature of the refrigerant discharged from the compressor 26 is set, and the electric expansion valve 36 is set based on the target discharge temperature.
The opening degree of A and 36B is set. At this time, the electric expansion valve 36 is controlled based on the operation state of the indoor units 12A and 12B.
By adjusting the opening degree of A and 36B, a desired air conditioning capacity can be obtained in each of the indoor units 12A and 12B.

The target discharge temperature can be calculated and set by any conventionally known method. Further, the calculated target discharge temperature is calculated based on the outside air temperature, the coil temperature of the indoor unit 12, the discharge temperature, and the compressor 26. The temperature may be corrected based on the suction temperature or the like, which is the temperature of the refrigerant sucked in, and detailed description is omitted in the present embodiment.

On the other hand, in the air conditioner 10, the outdoor unit 1
4 is provided with a microcomputer 98 having a refrigerant temperature sensor 150.
A, 150B and the electric expansion valve 36A based on the pipe temperature detected by the refrigerant temperature sensors 152A, 152B.
The opening of 36B is corrected.

Hereinafter, the electric expansion valve 36 provided in each indoor unit 12 (in the present embodiment, the electric expansion valve 36
A, 36B) will be described.

In the air conditioner 10, the electric expansion valve 36 is controlled so as to obtain a refrigerant flow rate based on the target discharge temperature.
The opening degree of A and 36B is set. At this time, if both indoor units 12A and 12B are in the thermo-on state, each of the electric expansion valves 36A and 36B is set to have a predetermined opening (an opening corresponding to the target discharge temperature). Further, when at least one of the indoor units 12 is turned off, the electric expansion valve 36 corresponding to the corresponding indoor unit 12 is closed.

On the other hand, in the air conditioner 10, the electric expansion valve 36
A, 36B correction amount (number of correction steps) Vb
[x] (Kb [x] = Kb [a] for the electric expansion valve 36A, Kb [x] = Kb [b] for the electric expansion valve 36B), and the correction set for the electric expansion valves 36A and 36B. Quantity Kb [a], K
Based on b [b], the opening of the electric expansion valves 36A and 36B is corrected. Thereby, without using the electric expansion valve for adjusting the refrigerant flow rate of the entire refrigeration cycle,
Each indoor unit 12 is set to a desired air-conditioning state.

The correction amount Vb [x] in the cooling mode is expressed by (1)
The calculation is based on the formula.

Vb [x] = Kbr × ((Sah × 4 + Hef × k) / 4 (1) where Kbr is a variable based on the operating capacity of the compressor.

In the present embodiment, the correction amount Vb [x]
Is determined using the lowest thick pipe temperature min (thick pipe temperature) among the thick pipe temperatures detected by the coolant temperature sensors 150 (152A, 152B) as the refrigerant temperature reference. The deviation D, which is the difference between the temperature of the thick pipe to which the expansion valve 36 is connected and min (thick pipe temperature),
= (Thick tube temperature)-min (Thick tube temperature) Deviation D
, And when D = 0, Hef = − ／ D / 2 When D> 0, Hef = D−1. When D <0 due to the reference temperature, Hef = D + 1. ΣD is the deviation D of the indoor unit 12.
And the sum of

Sah is a correction amount based on the variation of the deviation D when the difference between the current deviation D and the previous deviation Dm is ΔD.

Sah = ΔD = D−Dm Further, k is a coefficient corresponding to the sum of deviations ΣD. When 2 <ΣD ≦ 10, k = 3 10 <ΣD, and k = 5.

That is, in the air conditioner 10, the deviation D of the thick pipe temperature of each indoor unit 12 and the deviation D
The correction amount Vb [x] of each electric expansion valve 36 is calculated based on the difference between m and the current deviation D, that is, the amount of change in the deviation D.

In the air conditioner 10, the correction amount Vb [a] for each of the electric expansion valves 36A and 36B is thus obtained.
, Vb [b], and correct the opening of the electric expansion valves 36A, 36B set based on the target discharge temperature and the like. Thereby, the opening degree of the electric expansion valve 36 is controlled so that the temperature of the thick pipe to which each indoor unit 12 is connected becomes substantially the same.

On the other hand, in the heating mode, the coil temperature T-coil, which is the temperature of the heat exchanger of the indoor unit connected to the electric expansion valve 36 to be corrected, is the lowest coil temperature.
The deviation Hec between the coil temperature min (T-coil) as a reference and the coil temperature T-coil of each indoor unit 12 is calculated based on the min (T-coil) (see the equation (2)). (Hec = T-coil-min T-coil) (2) Here, when Hec> 1 (° C.), the correction amount Vb [x] of the higher coil temperature is Vb [x] = Kbd. × (−1) (3) The correction amount Vb [x] for the lower coil temperature is Vb [x] = Kbd × Hec (4) where Kbd is determined by the rotation speed of the compressor 26. The air conditioning capacity (heating capacity) in the determined heating mode.

When Hec ≦ 1, Vb [x] = 0. That is, in the air conditioner 10, when the deviation Hec of the coil temperature T-coil is within a predetermined range (for example, within 1 ° C.), if the deviation Hec exceeds the predetermined range as a dead zone in which the opening degree of the electric expansion valve 36 is not corrected. , Coil temperature T-c
The opening of the electric expansion valve 36 is corrected so that the oil is substantially the same.

In the air conditioner 10, the electric expansion valve 36
Is controlled in 511 steps between fully closed and fully open.
The opening of the electric expansion valve 36 is set only for the electric expansion valve 36 for the indoor unit 12 that is thermo-on, and the electric expansion valve 36 for the indoor unit 12 that is stopped or thermo-off is set to the preset opening. I am trying to be.

On the other hand, in the air conditioner 10, initial control is performed for a predetermined time from the start of operation, and when the initial control is completed, the process proceeds to normal control.

In the normal control after the end of the initial control, a control step is set by PI calculation based on the target discharge temperature, and the set control step is determined by the correction amount V
The correction is performed based on b [x] and output to each electric expansion valve 36.

The initial control is started when the operation of the air conditioner 10 (any of the indoor units 12) is started or when the operation mode is changed.

The output step Os during the initial control can be set, for example, by equation (5).

Os = Freq × A + Kx + S (5) where Freq is the operating frequency of the compressor 26, A is the slope preset according to the operating mode and the number of operating units, and Kx is the operating mode and the operating unit number. Table 1 shows an example of the slope A and the constant Kx.

[0068]

[Table 1]

S is a correction value, which is the
Last correction value by PI control at N. Compressor temperature,
It is set based on the operating frequency of the compressor 26, the number of operating indoor units 12, the presence or absence of a change in the operating mode, and the like, and is cleared when the air conditioner 10 stops (S
= 0).

That is, during the initial control, control is performed such that the opening degree of each electric expansion valve 36 of the operating indoor unit 12 is substantially constant. In the initial control, for example, the coil temperature T of the two indoor units 12 is set.
When the temperature difference of -coil exceeds a predetermined temperature, the control step of the electric expansion valve 36 of the indoor unit 12 having the high coil temperature T-coil is reduced by a predetermined value (for example, 10 steps).

The operation of the present embodiment will be described below.

In the air conditioner 10, when at least one of the indoor units 12 is operated by operating a remote control switch (not shown), the indoor unit 1 is operated based on a signal from the operated indoor unit 12.
4 operates.

In the outdoor unit 14, the operating frequency of the compressor 26 is set based on a signal from the indoor unit 12 that has been operated, and the compressor motor 108
To work. At the same time, the outdoor unit 14 sets the target discharge temperature and operates the electric expansion valve 36 so that the refrigerant temperature on the discharge side of the compressor 26 becomes the target discharge temperature.

As a result, in the air conditioner 10, the indoor unit 1 operated by the operation
2 is installed so that the room to be air-conditioned where the air conditioner 2 is installed is in a desired air-conditioning state.

By the way, in the air conditioner 10, by controlling the electric expansion valves 36 provided corresponding to each of the plurality of indoor units 12, the total refrigerant flow rate can be improved.
The refrigerant flow to each indoor unit 12 is controlled.

Here, control of the electric expansion valve 36 (setting of control steps) will be described with reference to the flowchart shown in FIG.

This flowchart is executed when the operation of at least one indoor unit 12 is instructed and the outdoor unit 14 starts operating. In the first step 200, the operation mode is changed to the cooling mode. Check if there is. As a result, the cooling mode is set, and if an affirmative determination is made in step 200, step 2 is performed.
02, the control of the electric expansion valve 36 in the cooling mode is started.

When the mode is set to the heating mode, a negative determination is made in step 200 and the process proceeds to step 204, in which the four-way valve 24 is operated to shift to the heating mode, and the electric expansion valve 36 in the heating mode is operated. Start initial control.

As described above, the air conditioner 10 performs the initial control for a preset time, and confirms that the initial control has been completed in step 206 (in the cooling mode) or step 208 (in the heating mode). , Step 21
0 or the process proceeds to step 212 to start the normal control.
In Steps 214 and 216, it is confirmed whether or not the operation mode has been changed. If the operation mode has been changed (Yes in Step 214 or Step 216), the process proceeds to Step 200, and the operation mode is changed. After the confirmation, the initial control is started. Step 21
In steps 8 and 220, it is confirmed whether or not the stop of the air conditioner 10 has been instructed. If all the indoor units 12 of the air conditioner 10 are stopped and a positive determination is made in step 218 or step 220, the process proceeds to step 222. Then, the control of the electric expansion valve 36 ends.

Here, the normal control of the electric expansion valve 36 when the air conditioner 10 is operating in the cooling mode is shown in FIG.
This will be described with reference to the flowchart shown in FIG. In addition,
During the initial control, the opening degree of the electric expansion valve may be controlled by a conventionally known method, and therefore, detailed description is omitted in the present embodiment.

The flowchart shown in FIG.
When the control of the electric expansion valve in the cooling mode is performed by moving to step 210 in the flowchart of the above, the control is executed at predetermined time intervals. In the first step 230, the target discharge temperature is calculated, and in the next step 232, Based on the calculated target discharge temperature, a control step of the opening degree of the electric expansion valve 36 thermo-on by PI calculation is set.

Thereafter, in step 234, the temperature of the thick pipe corresponding to the indoor unit 12 which is thermo-on is detected and read by the refrigerant temperature sensors 150 (150A, 150B), and in the next step 236, for example, the lowest thick pipe The deviation of the thick pipe temperature corresponding to each electric expansion valve 36 is calculated based on the temperature min (T), and the correction amount H based on the deviation D is calculated.
Set ef. In step 238, the amount of change in the calculated deviation D is calculated, and a correction amount Sah based on the amount of change in the deviation D is set.

In the next step 240, each electric expansion valve 3
6, the correction amount Sah, and the outdoor unit 1
From the air conditioning capacity Kbr of No. 4, the control step correction amount Vb [x]
Is calculated based on the equation (1), and in step 242, the control step set by the target discharge temperature is corrected by the correction amount Vb [x], and the control step of each electric expansion valve 36 is set.

In the air conditioner 10, the control step set in this way is output as an output step to each motor-operated expansion valve 36, and the valve opening of each motor-operated expansion valve 36 is operated (step 244).

Thus, in the air conditioner 10, when operating in the cooling mode, the temperature of the thick pipe of the indoor unit 12, that is, the temperature of the refrigerant returned to the compressor 26 through the thick refrigerant pipe 16A is substantially the same. Is controlled so that

Therefore, while operating in the cooling mode, the flow rate of the refrigerant circulating in the refrigeration cycle can be adjusted while adjusting the flow rate of the refrigerant to the individual indoor units 12.

FIG. 6B shows the normal control of the electric expansion valve 36 when the air conditioner 10 is operating in the heating mode. This flowchart is executed at predetermined time intervals by moving to step 212 in the flowchart of FIG.

In the first step 250, the target discharge temperature is calculated, and in the next step 252, a control step of the opening degree of the motor-operated expansion valve 36 thermo-on is set by PI calculation based on the calculated target discharge temperature. .

Thereafter, in step 254, the coil temperature T-coil detected by the heat exchange temperature sensor 86 of the indoor unit 12 which is thermo-on is read, and in the next step 256, for example, the lowest coil temperature min (T-coil
) Is calculated, and the deviation Hec of the coil temperature T-coil corresponding to each electric expansion valve 36 is calculated.

In the next step 258, each electric expansion valve 3
6 and the air conditioning capacity Kbd of the outdoor unit 14
, A correction amount Vb [x] of the control step is calculated, and in step 260, the control step set by the target discharge temperature is corrected by the correction amount Vb [x].
6 control steps are set.

The air conditioner 10 outputs the control steps set in the heating mode to the respective electric expansion valves 36 (step 262), thereby operating the valve opening of each electric expansion valve 36.

Thus, in the heating mode, the electric expansion valves 36 provided for the respective indoor units 12 are controlled such that the coil temperatures T-coil of the respective indoor units 12 become substantially constant.

Therefore, the air conditioner 10 can adjust the flow rate of the refrigerant circulating in the refrigeration cycle while adjusting the flow rate of the refrigerant to the individual indoor units 12 when operating in the heating mode.

As described above, in the air conditioner 10, the flow rate of the refrigerant circulating in the refrigeration cycle is adjusted by setting the opening of the electric expansion valves 36A and 36B based on the target discharge temperature. Since an electric expansion valve separately provided for adjusting the flow rate of the refrigerant circulated in the cycle is not required, the number of parts can be reduced.

In the air conditioner 10, the indoor unit 1
The electric expansion valve 36 corresponding to each of 2A and 12B
The opening degree of A, 36B is set based on the target discharge temperature, and based on the temperature of the refrigerant passing through the indoor units 12A, 12B or the coil temperature T-coil, which is the temperature of the heat exchanger 18 of the indoor units 12A, 12B. The air conditioning capacity of the indoor units 12A and 12B can be maintained at a predetermined level by simple control of operating the electric expansion valves 36A and 36B based on the corrected control steps.

Note that the present embodiment described above does not limit the present invention. For example, in the present embodiment, the lowest temperature is used as the reference temperature of the thick tube temperature and the coil temperature, but the highest temperature or the temperature of any one indoor unit may be used.

An air conditioner to which the present invention is applied is as follows:
It is not limited to the one that performs cooling and heating with the refrigerant circulating in the refrigeration cycle, and may be an air conditioner dedicated to cooling that performs only cooling with the refrigerant that circulates in the refrigeration cycle, and performs heating using hot water. A so-called hot water air conditioner may be used.

[0098]

As described above, according to the present invention, based on the refrigerant temperature or coil temperature for each indoor unit,
By correcting the opening of the electric expansion valve provided corresponding to each indoor unit, it is possible to adjust the flow rate of the refrigerant to each indoor unit and to adjust the flow rate of the refrigerant circulated in the refrigeration cycle. Therefore, it is not necessary to separately provide an electric expansion valve for adjusting the flow rate of the refrigerant, and the number of electric expansion valves of the multi-type air conditioner can be reduced. Further, according to the present invention, an excellent effect that control of the electric expansion valve becomes extremely easy can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of a multi-type air conditioner applied to an embodiment.

FIG. 2 is a schematic configuration diagram illustrating an example of a refrigeration cycle of an air conditioner applied to the present embodiment.

FIG. 3 is a block diagram illustrating a schematic configuration of an electric circuit of the indoor unit.

FIG. 4 is a block diagram illustrating a schematic configuration of an electric circuit of the outdoor unit.

FIG. 5 is a flowchart.

FIG. 6A is a flowchart schematically illustrating the setting of control steps for each electric expansion valve in the cooling mode, and FIG. 6B is a flowchart schematically illustrating setting of control steps for each electric expansion valve in the heating mode. is there.

[Explanation of symbols]

Reference Signs List 10 air conditioner (air conditioner) 12 (12A, 12B) indoor unit 14 outdoor unit 16A refrigerant pipe (thick pipe) 18 heat exchanger 26 compressor 36 (36A, 36B) electric expansion valve 86 heat exchange temperature sensor (coil temperature detecting means) ) 98 microcomputer 150 (150A, 150B) Refrigerant temperature sensor (refrigerant temperature detecting means)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuhito Fujinaka 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. (Reference) 3L060 AA08 CC04 DD05 EE09 3L092 GA12 JA01 KA02 KA09 LA06

Claims (5)

[Claims] An outdoor unit having at least a compressor, an electric expansion valve, and a heat exchanger, and a plurality of indoor units having at least a heat exchanger are connected by a refrigerant pipe so that a refrigeration cycle is established. In an air conditioner that performs heat exchange between air blown out and a refrigerant circulated in a refrigeration cycle, provided in an outdoor unit corresponding to each of the plurality of indoor units,
A method of controlling an electric expansion valve that adjusts a flow rate of a refrigerant to a corresponding indoor unit, wherein an opening degree of each electric expansion valve is determined based on a target discharge temperature that is a target value of a refrigerant temperature discharged from a compressor. While setting, the refrigerant temperature detecting means detects the refrigerant temperature which passes through each of the heat exchangers of the plurality of indoor units and is returned to the outdoor unit, and the plurality of indoor units are determined based on the refrigerant temperature of any of the indoor units. A method for controlling an electric expansion valve, wherein a deviation of each refrigerant temperature of a unit is obtained, and an opening degree of an electric expansion valve corresponding to each indoor unit is corrected according to the deviation. 2. The method according to claim 1, wherein a change amount of the deviation is calculated for each of the plurality of indoor units, and an opening degree of the electric expansion valve corresponding to each indoor unit is corrected including the calculation result. The method for controlling an electric expansion valve according to claim 1. 3. The control method for an electric expansion valve according to claim 1, wherein the correction of the degree of opening of the electric expansion valve is performed in a cooling mode for cooling a room to be air-conditioned. 4. An air-conditioned room while connecting an outdoor unit having at least a compressor, an electric expansion valve, and a heat exchanger and a plurality of indoor units having at least a heat exchanger so that a refrigeration cycle is established. In an air conditioner that performs heat exchange between air blown out and a refrigerant circulated in a refrigeration cycle, provided in an outdoor unit corresponding to each of the plurality of indoor units,
A method of controlling an electric expansion valve that adjusts a flow rate of a refrigerant to a corresponding indoor unit, wherein an opening degree of each electric expansion valve is determined based on a target discharge temperature that is a target value of a refrigerant temperature discharged from a compressor. While setting, the coil temperature of the heat exchanger is detected by the coil temperature detecting means provided in each of the plurality of indoor units, and the coil temperature of each indoor unit is determined based on the coil temperature of any of the indoor units. A method for controlling an electric expansion valve, wherein a deviation is obtained, and an opening degree of an electric expansion valve corresponding to each indoor unit is corrected according to the deviation. 5. The control method for an electric expansion valve according to claim 4, wherein the opening degree of the electric expansion valve is corrected in a heating mode for heating a room to be air-conditioned.