JP2002213798A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner which is constituted by connecting a plurality of indoor machines to one outdoor machine and is improved in fluctuation and deterioration in its operational efficiency by more accurately controlling the degree of superheat at the suction port of a compressor. SOLUTION: During operation, the corrected degree of superheat SHax of an individual unit which is the sum of the degree of superheat SHt of all units (which is the difference between the inlet temperature of the compressor, namely, the temperature of a refrigerant sucked in the compressor and the mean temperature value of the indoor heat exchangers of all indoor units during operation) and the deviation DSHx of the degree of superheat of the individual unit (which is the difference between the degree of superheat SHx of the individual unit that is the difference between the temperatures of the refrigerant and indoor heat exchanger of the individual unit and the mean value SHm of the degrees of superheat of the individual units of all indoor units during operation) is found at every indoor unit. Then the flow rate of the refrigerant is controlled to increase when the corrected degree of superheat SHax of the individual unit is larger than a preset reference degree of superheat SHOx or to decrease when the corrected degree of superheat SHax is smaller than the reference degree of superheat SHOx.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner in which one outdoor unit is connected to a plurality of indoor units, and more particularly to a refrigerant control for the air conditioner.

[0002]

2. Description of the Related Art FIG. 1 shows an example of a block diagram of an air conditioner. The outdoor side has a compressor 101, an outdoor heat exchanger 102,
Outdoor fan 103, electric expansion valves 104-1 and 104-
2, 104-3, four-way valve 105, oil separator 10
6. Capillary tube 107 for oil separator, compressor discharge temperature sensor 108, compressor suction temperature sensor 109, outdoor heat exchanger temperature sensor 110, individual gas temperature sensor 11
1-1, 111-2, and 111-3, and the control device 112.

[0003] On the indoor side, a first unit comprising an indoor heat exchanger 201-1, an indoor fan 202-1, an indoor temperature sensor 203-1, an indoor heat exchanger temperature sensor 204-1 and a control device 205-1. A second room including an indoor unit 200-1, an indoor heat exchanger 201-2, an indoor fan 202-2, an indoor temperature sensor 203-2, an indoor heat exchanger temperature sensor 204-2, and a control device 205-2. Unit 2
00-2, and a third room including an indoor heat exchanger 201-3, an indoor fan 202-3, an indoor temperature sensor 203-3, an indoor heat exchanger temperature sensor 204-3, and a control device 205-3. It is composed of a unit 200-3.

[0004] During the cooling operation, the high-pressure gas refrigerant discharged from the compressor 101 is subjected to oil separation by the oil separator 106 and the capillary tube 107, and then the four-way valve 1.
At 05, it is sent to the outdoor heat exchanger 102. In the outdoor heat exchanger 102, heat is released to the outside and the refrigerant is liquefied.

The liquefied refrigerant is supplied to the electric expansion valve 104-
1, 104-2, and 104-3 are diverted at the branch point A and decompressed through electric expansion valves 104-1, 104-2, and 104-3, and then each of the indoor heat exchangers 201-1 , 201-2, 201-3. still,
The degree of opening of the electric expansion valves 104-1, 104-2, and 104-3 is electrically adjustable, and the amounts of refrigerant flowing through the indoor heat exchangers 201-1, 201-2, and 201-3, respectively, are controlled. Also used to control.

The indoor heat exchangers 201-1, 201-2, 2
In 01-3, the refrigerant is evaporated by absorbing heat from the room.
Indoor heat exchangers 201-1, 201-2 and 201-
The refrigerant discharged from 3 joins at a branch point B before reaching the four-way valve 105, and is sent to the compressor 101 by the four-way valve 105. In the heating operation, the refrigerant flows through a path reverse to that in the cooling operation. Switching between cooling operation and heating operation is
This is performed by switching the flow path of the refrigerant using the four-way valve 105.

[0007] The compressor discharge temperature sensor 108 is
The compressor 101 is disposed at an upper portion or a discharge side pipe, and detects a temperature corresponding to a temperature of the refrigerant discharged from the compressor 101. The compressor suction temperature sensor 109 is connected to the compressor 101
And detects a temperature corresponding to the temperature of the refrigerant sucked into the compressor 101 (hereinafter, “compressor suction temperature”). The outdoor heat exchanger temperature sensor 110 is
Between the indoor heat exchangers 201-1, 201-2, 201-3 and the compressor 101, a pipe on the outdoor heat exchanger 102 side from the branch point A on the side where the outdoor heat exchanger 102 exists. Are arranged.

[0008] Individual gas temperature sensors 111-1, 111-
2, 111-3 are indoor heat exchangers 201-1,
Between the 201-2, 201-3 and the compressor 101, the indoor heat exchanger 201-1, 201-2, 201-3 side from the branch point B on the side where the outdoor heat exchanger 102 does not exist. A temperature (hereinafter, “individual gas temperature”) corresponding to the temperature of the refrigerant flowing through the pipe (hereinafter, “individual pipe on the compressor side of the indoor heat exchanger”) is detected.

The indoor temperature sensors 203-1, 203-2,
203-3 is the first indoor unit 200-
1, the second indoor unit 200-2 and the third indoor unit 200-3 are arranged on the indoor air suction side,
The temperature of the indoor air in which each indoor unit is installed is detected.

The indoor heat exchanger temperature sensors 204-1, 20
4-2, 204-3 are indoor heat exchangers 201-1, 20-20.
1-2, 201-3, and a temperature corresponding to the temperature of the refrigerant inside the indoor heat exchangers 204-1, 204-2, 204-3 (hereinafter referred to as “the indoor heat exchanger”). Temperature ”).

Control devices 205-1, 205-2, 205
-3 are indoor fans 202-1 and 202-, respectively, according to a command input from a user using a remote controller or the like.
2, 202-3 as well as transmitting commands such as operation start and operation stop, and information such as operation type, set temperature, and temperature detected by a temperature sensor of the indoor unit to the outdoor control device 112. .

The outdoor controller 112 includes a compressor discharge temperature sensor 108, a compressor suction temperature sensor 109, an outdoor heat exchanger temperature sensor 110, and individual gas temperature sensors 111-1, 111-2, and 111. -3 and the control units 205-1, 205 on the indoor unit side
-2, 205-3, the compressor 101, the outdoor fan 103, the electric expansion valve 10
4-1, 104-2, 104-3, and four-way valve 105
Is controlled.

The electric expansion valves 104-1, 104-2, 10
A conventional method of controlling the opening degree of 4-3 will be described with reference to a flowchart shown in FIG. First, regarding each indoor unit 200-x (x indicates 1, 2, or 3) during operation, the detected temperature Ts of the individual gas temperature sensor 111-x is used.
x and the temperature Tex detected by the indoor heat exchanger temperature sensor 204-x are taken in (S501). Next, the individual unit superheat degree SHx, which is the difference between the temperatures Tsx and Tex taken in S501, is calculated (S502).

Next, if the individual unit superheat degree SHx calculated in S502 is larger than the reference value (Ye in S503)
s), the opening degree of the corresponding electric expansion valve 104-x is increased to increase the flow rate of the refrigerant in the indoor unit 200-x (S504). On the other hand, if the individual unit superheat degree SHx is smaller than the reference value (Yes in S505), the opening degree of the corresponding electric expansion valve 104-x is reduced to make the indoor unit 2
The flow rate of the 00-x refrigerant is reduced (S506).

After S504 and S506, the process returns to S501. If the individual unit superheat degree SHx is not larger than the reference value (No in S503) and is not smaller than the reference value (No in S505), the opening degree of the corresponding electric expansion valve 104-x is changed. And return to S501.

[0016]

As described above, conventionally,
The degree of opening of the electric expansion valve is controlled so that the degree of superheating of the indoor unit (the difference between the temperature detected by the individual gas temperature sensor and the temperature detected by the indoor heat exchanger temperature sensor) becomes equal to the reference value. However, this had the following problems.

The temperature detected by these temperature sensors varies depending on the degree of attachment of the individual gas temperature sensor and the indoor heat exchanger temperature sensor and the influence of ambient heat. The relationship with the degree of superheat of the indoor unit is as shown in FIG. 7. Even if the degree of superheat of the indoor unit slightly changes, the degree of superheat at the inlet of the compressor greatly changes (this is because In the individual pipe on the compressor side of the exchanger, the superheat degree is 3 to 5 ° C, and the superheated gas flows or becomes a two-phase flow due to the pulsation of the refrigerant flow rate. Because it is expensive).

The degree of superheat at the inlet of the compressor is generally 5 to 5.
Although it is set to 15 ° C., for example, when controlling the superheat degree of the indoor unit to 6 ° C. in order to make the superheat degree at the suction port of the compressor 12 ° C.,
If detected low, the superheat at the compressor inlet is 14 ° C
When the superheat degree of the indoor unit is detected to be higher by 2 ° C., the superheat degree at the suction port of the compressor becomes 6 ° C.

Therefore, in the conventional method of controlling the opening of the electric expansion valve based on the degree of superheating of the indoor unit, the degree of superheating at the suction port of the compressor cannot be accurately controlled, and the operating efficiency cannot be improved. This is a factor that causes variation and reduction.

Therefore, the present invention relates to an air conditioner in which a plurality of indoor units are connected to one outdoor unit, and by controlling the degree of superheat at the suction port of the compressor more accurately,
An object of the present invention is to provide an air conditioner in which variation and reduction in operation efficiency are improved.

[0021]

In order to achieve the above object, according to the present invention, a plurality of indoor heat exchangers are provided for one compressor, and a refrigerant is provided for each of the plurality of indoor heat exchangers. An air conditioner comprising a means for controlling the flow rate of the compressor, a means for detecting a compressor suction temperature which is a temperature of the refrigerant sucked into the compressor, and a means for detecting a temperature of the refrigerant inside each indoor heat exchanger. Means for detecting a certain indoor heat exchanger temperature, between the indoor heat exchanger and the compressor, the temperature of the refrigerant on the indoor heat exchanger side from the branch point on the side where the outdoor heat exchanger does not exist. Means for detecting an individual refrigerant temperature for each indoor heat exchanger, and the difference between the compressor suction temperature and the average of the indoor heat exchanger temperatures of all the indoor units in operation is determined for all units of superheat, The individual refrigerant temperature and the indoor heat exchanger temperature The difference between the individual unit superheat degree and the difference between the individual unit superheat degree and the average of the individual unit superheat degrees of all the indoor units in operation is defined as the individual unit superheat deviation, and for each indoor unit in operation, Determine the corrected individual unit superheat degree which is the sum of the total unit superheat degree and the individual unit superheat degree deviation, and when the corrected individual unit superheat degree is larger than a preset reference superheat degree, the flow rate of the refrigerant increases, On the other hand, means for controlling the flow rate of the refrigerant to be decreased when the flow rate is small.

With this configuration, the compressor suction temperature is set to Ts
c, assuming that the indoor heat exchanger temperature of the target indoor unit is Tex, the individual gas temperature of the target indoor unit is Tsx, and the average of the individual gas temperatures of all the operating indoor units is Tsm, Based on the corrected individual unit superheat degree Shax represented by 2, the flow rate of the refrigerant in the target indoor unit is controlled.

Further, in the present invention, a plurality of indoor heat exchangers are provided for one compressor, and means for controlling the flow rate of the refrigerant for each of the plurality of indoor heat exchangers is provided. In the air conditioner, means for detecting a compressor suction temperature which is a temperature of a refrigerant sucked into the compressor,
Means for detecting the indoor heat exchanger temperature, which is the temperature of the refrigerant inside each indoor heat exchanger, and between the indoor heat exchanger and the compressor, from the branch point on the side where the outdoor heat exchanger does not exist Means for detecting the individual refrigerant temperature, which is the temperature of the refrigerant on the indoor heat exchanger side, for each indoor heat exchanger, and an average of the compressor suction temperature and the indoor heat exchanger temperature of all the operating indoor units. And the difference between the individual refrigerant temperature of the indoor unit and the indoor heat exchanger temperature is the individual unit superheat degree, the individual unit superheat degree and the individual unit overheating of all the indoor units in operation. The difference between the average and the individual unit superheat degree, the sum of the total unit superheat degree and the individual unit superheat degree deviation is referred to as the corrected individual unit superheat degree, and for each indoor unit during operation, at predetermined time intervals. Correction individual unit Sums determining a difference in a pair reference superheat difference between a preset reference degree of superheat degree of superheating, if the integrated value is larger than the predetermined value increases the flow rate of the refrigerant,
On the other hand, means for controlling the flow rate of the refrigerant to decrease when the flow rate is smaller than the predetermined value is provided.

With this configuration, the compressor suction temperature is set to Ts
c, if the indoor heat exchanger temperature of the target indoor unit is Tex, the individual gas temperature of the target indoor unit is Tsx, and the average of the individual gas temperatures of all the operating indoor units is Tsm, the following equation Based on the integral value of the difference between the corrected individual unit superheat degree SHax and the reference superheat degree SH0x, the flow rate of the refrigerant in the target indoor unit is controlled.

The reference degree of superheat is set for each combination of the capacity of the target indoor unit, the operating frequency of the compressor, and the capacity and number of all the indoor units in operation. Is also good.

Further, in the present invention, a plurality of indoor heat exchangers are provided for one compressor, and means for controlling the flow rate of the refrigerant for each of the plurality of indoor heat exchangers is provided. In the air conditioner, means for detecting a compressor suction temperature which is a temperature of a refrigerant sucked into the compressor,
Means for detecting the indoor heat exchanger temperature, which is the temperature of the refrigerant inside each indoor heat exchanger, and between the indoor heat exchanger and the compressor, from the branch point on the side where the outdoor heat exchanger does not exist Means for detecting the individual refrigerant temperature, which is the temperature of the refrigerant on the indoor heat exchanger side, for each indoor heat exchanger; and correcting the sum of the indoor heat exchanger temperature and the indoor heat exchanger correction temperature. temperature,
The difference between the compressor suction temperature and the average of the corrected indoor heat exchanger temperatures of the operating indoor units is the total unit superheat degree, and the difference between the individual refrigerant temperature of the indoor unit and the indoor heat exchanger temperature is the individual unit. The degree of superheat, the difference between the individual unit superheat degree and the average of the individual unit superheat degrees of all the indoor units in operation is defined as the individual unit superheat degree deviation. And the corrected individual unit superheat degree which is the sum of the individual unit superheat degree deviation and the corrected individual unit superheat degree is larger than the reference superheat degree set in advance. And means for controlling the flow rate of the refrigerant to decrease.

With this configuration, the compressor suction temperature is set to Ts
c, Tex is the indoor heat exchanger temperature of the target indoor unit, Tam is the average of the indoor heat exchanger corrected temperatures of all the indoor units in operation, Tsx is the individual gas temperature of the target indoor unit, and Tsx is the operating indoor unit. Assuming that the average of the individual gas temperatures of all the indoor units is Tsm, the amount of the refrigerant of the target indoor unit is controlled based on the corrected superheat degree Shax expressed by Expression 3 described later.

In the present invention, a plurality of indoor heat exchangers are provided for one compressor, and means for controlling the flow rate of the refrigerant is provided for each of the plurality of indoor heat exchangers. In the air conditioner, means for detecting a compressor suction temperature which is a temperature of a refrigerant sucked into the compressor,
Means for detecting the indoor heat exchanger temperature, which is the temperature of the refrigerant inside each indoor heat exchanger, and between the indoor heat exchanger and the compressor, from the branch point on the side where the outdoor heat exchanger does not exist Means for detecting the individual refrigerant temperature, which is the temperature of the refrigerant on the indoor heat exchanger side, for each indoor heat exchanger; and correcting the sum of the indoor heat exchanger temperature and a preset indoor heat exchanger correction temperature. The difference between the indoor heat exchanger temperature, the compressor suction temperature and the average of the corrected indoor heat exchanger temperatures of the operating indoor units is calculated as the degree of superheating of all units, the individual refrigerant temperature of the indoor unit and the indoor heat exchanger temperature. The difference between the individual unit superheat degree and the difference between the individual unit superheat degree and the average of the individual unit superheat degrees of all the indoor units in operation is the individual unit superheat deviation, the total unit superheat degree and the individual unit superheat Correct the sum with the deviation Assuming the knit superheat degree, for each indoor unit during operation, at predetermined time intervals, a difference between the corrected individual unit superheat degree and a preset reference superheat degree is determined and integrated, and the sum is calculated. Means for controlling so that the flow rate of the refrigerant increases when the integrated value is larger than a predetermined value, and decreases when the integrated value is smaller than the predetermined value.

With this configuration, the compressor suction temperature is set to Ts
c, Tex is the indoor heat exchanger temperature of the target indoor unit, Tam is the average of the indoor heat exchanger corrected temperatures of all the indoor units in operation, Tsx is the individual gas temperature of the target indoor unit, and Tsx is the operating indoor unit. Assuming that the average of the individual gas temperatures of all the indoor units is Tsm, based on the integral value of the difference between the corrected superheat degree SHax and the reference superheat degree SH0 expressed by Expression 3 below, the refrigerant of the target indoor unit is Is controlled.

The indoor heat exchanger correction temperature is set for each combination of the capacity of the target indoor unit, the operating frequency of the compressor, and the capacity and number of all the indoor units in operation. You may leave.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. The air conditioner according to the first embodiment of the present invention has the same configuration as that described in the related art as shown in FIG. 1, and therefore, only the characteristic portions of the first embodiment will be described.

Indoor units 200-1, 200-2, 2
00-3, each of the control devices 205-1, 205-
2, 205-3, a room temperature sensor 2 is provided when a request for a set temperature and a cooling operation is input from a user by a remote controller or the like.
The required capacity code corresponding to the difference between the temperature detected in 03-1, 203-2, and 203-3 and the set temperature is transferred to the outdoor controller 112.

The operation of the outdoor controller 112 will be described with reference to the flowchart shown in FIG. First, the required capacity codes transmitted from the control devices of the indoor units are integrated, and the operating frequency Ft of the compressor 101 is determined based on the sum (S101). The compressor 101 is of an inverter type, and the number of revolutions is determined according to the operating frequency Ft.

Next, the operating frequency Ft determined in S101
Starts the operation of the compressor 101 (S102). Next, an operating frequency Fx per unit of each of the indoor units 200-x in operation is derived (S103).

The operating frequency per unit is the capacity of the corresponding indoor unit and the operating frequency F of the compressor 101.
It is derived based on t and the capacity and the number of indoor units that are operating. For example, in this embodiment, there are three indoor units, and one of them has a capacity of 3.5 [kW] and the other two have a capacity of 2.5 [kW]. In this way, a distribution correction coefficient is given in advance for each capacity of the indoor unit according to the capacity and the number of the indoor units in operation, and a value obtained by multiplying the operating frequency Ft of the compressor 101 by the corresponding distribution correction coefficient. Is the operating frequency per unit. Alternatively, the operating frequency per unit may be obtained from Equation 1 below.

[0036]

[Table 1]

[0037]

(Equation 1)

Next, a reference superheat degree SH0x of the operating indoor unit 200-x is derived (S104). The reference superheat degree is preset as a numerical table or a function for the operating frequency and capacity per unit of the corresponding indoor unit as shown in Table 2 below, for example, and is derived based on this. Is done.

[0039]

[Table 2]

Next, the temperature Tsc detected by the compressor suction temperature sensor 109 and the temperature Ts detected by the individual gas temperature sensor 111-x corresponding to the operating indoor unit 200-x.
x and the temperature Tex detected by the indoor heat exchanger temperature sensor 204-x of the operating indoor unit 200-x (S105).

Next, the detected temperature Te taken in S105
The average value Tem of x is calculated (S106). Next, S1
The total unit superheat SHt, which is the difference between the detected temperature Tsc taken in at 05 and the average value Tem obtained at S106, is obtained (S107).

Next, the detected temperature Ts taken in S105
individual unit superheat degree S, which is the difference between x and the detected temperature Tex
Hx is obtained (S108). Next, the average SHm of the individual unit superheat degrees SHx obtained in S108 is obtained (S1).
09). Next, the individual unit superheat degree S obtained in S108
An individual unit superheat degree deviation DSHx, which is a difference between Hx and the average value SHm obtained in S109, is obtained (S110). Next, the total unit superheat degrees SHt and S11 determined in S107
A corrected individual unit superheat degree SHAx which is a sum of the individual unit superheat degree deviation DSHx obtained at 0 is obtained (S11).
1).

Next, the corrected individual unit superheat degree SHax obtained in S111 is equal to the reference superheat degree SH0 derived in S104.
It is determined whether it is larger than x (S112). If it is larger (Yes in S112), the opening degree of the electric expansion valve 104-x is increased by one step (S113), and thereafter, the process proceeds to S101.

On the other hand, if it is not large (N in S112)
o), the corrected individual unit superheat degree Shax is the reference superheat degree S
It is determined whether it is smaller than H0x (S114). If smaller (Yes in S114), the electric expansion valve 104-x
Is decreased (S115), and the process proceeds to S101. On the other hand, if it is not smaller (No in S114), the process directly proceeds to S101.

With the above processing, the suction temperature Tsc of the compressor 101, the indoor heat exchanger temperature Tex of the operating indoor unit 200-x, the individual gas temperature Tsx of the operating indoor unit 200-x, and all the operating temperatures The degree of opening of the electric expansion valve 104-x is controlled based on the average value Tsm of the individual gas temperatures of the indoor units described above and based on the corrected individual unit superheat degree SHax obtained by the following equation (2).

[0046]

(Equation 2)

Thus, the individual gas temperature sensor 111-
Even if the temperatures detected by the temperature sensors 1, 111-2, 111-3 and the indoor heat exchanger temperature sensors 204-1, 204-2, 204-3 vary, the corresponding electric motor is controlled based on the degree of superheat of the indoor unit. As compared with the case where the opening degree of the expansion valve is controlled, the degree of superheat at the suction port of the compressor 101 can be controlled with higher accuracy, and variation and reduction in operating efficiency can be improved.

An air conditioner according to a second embodiment of the present invention will be described. Since the second embodiment has the same configuration as that described in the related art as shown in FIG. 1, only the characteristic portions will be described. FIG. 3 shows a flowchart of an operation performed by the control device 112 regarding the control of the opening degrees of the electric expansion valves 104-1, 104-2, and 104-3 during the cooling operation.

Steps S201 to S211 are performed by the control device 112 in the first embodiment shown in FIG.
The description is omitted because it is the same as S111. When S211 is finished, a reference superheat degree difference DShax, which is a difference between the corrected individual unit superheat degree Shax and the reference superheat degree SH0x, is obtained (S212). Next, by adding the reference superheat degree difference DShax obtained in S212, the integrated value ΣDSHa of the reference superheat degree difference of the operating indoor unit 200-x is added.
x is updated (S213).

Next, the integrated value ΣDS updated in S213
It is determined whether or not Hax is equal to or more than the upper limit (S21).
4). If it is equal to or more than the upper limit (Yes in S214), the opening of the electric expansion valve 104-x is increased by one step (S21).
5) Then, the process proceeds to S201. On the other hand, if it is not equal to or greater than the upper limit (No in S214), it is determined whether or not the integrated value ΣDSHax updated in S213 is equal to or less than the lower limit (S216).

If the value is equal to or less than the lower limit value (Ye in S216)
s) The opening degree of the electric expansion valve 104-x is reduced by one step (S217), and thereafter, the process proceeds to S201. On the other hand, if not less than the lower limit value (No in S216), S2
Move to 01.

With the above processing, the suction temperature Tsc of the compressor 101, the indoor heat exchanger temperature Tex of the operating indoor unit 200-x, the individual gas temperature Tsx of the operating indoor unit 200-x, and all the operating temperatures The corrected individual unit superheat degree SHax and the reference superheat degree SH0x obtained from the average value Tsm of the individual gas temperatures of the indoor units obtained by the above formula 2 from the average value Tsm of the indoor units.
The opening degree of the electric expansion valve 104-x is controlled based on the integrated value of the difference between.

Thus, the individual gas temperature sensor 111-
Even if the temperatures detected by the temperature sensors 1, 111-2, 111-3 and the indoor heat exchanger temperature sensors 204-1, 204-2, 204-3 vary, the corresponding electric motor is controlled based on the degree of superheat of the indoor unit. As compared with the case where the opening degree of the expansion valve is controlled, the degree of superheat at the suction port of the compressor 101 can be controlled with higher accuracy, and variation and reduction in operating efficiency can be improved. Further, the degree of superheat at the suction port of the compressor 101 can be controlled more smoothly and finely.

An air conditioner according to a third embodiment of the present invention will be described. Since the third embodiment has the same configuration as that described in the related art as shown in FIG. 1, only the characteristic portions will be described. FIG. 4 shows a flowchart of an operation performed by the control device 112 regarding the control of the degree of opening of the electric expansion valves 104-1, 104-2, and 104-3 during the cooling operation.

First, the required capacity codes transmitted from the control devices of the indoor units are integrated, and the operating frequency Ft of the compressor 101 is determined based on the sum (S301).
Next, the operation of the compressor 101 is started at the operation frequency determined in S301 (S302). Next, the operating frequency Fx per unit of the operating indoor unit 200-x is derived (S303). The operation frequency per unit in S303 may be derived in the same manner as in the first embodiment.

Next, the indoor heat exchanger correction temperature Tax of the operating indoor unit 200-x is derived (S304).
The indoor heat exchanger correction temperature is used to correct the temperature drop of the refrigerant from the portion where the indoor heat exchanger temperature sensor is disposed to the suction port of the compressor 101.
As shown in (1), the operating frequency and capacity per unit of the corresponding indoor unit are preset as a numerical table or a function, and are derived based on this.

[0057]

[Table 3]

Next, the temperature Tsc detected by the compressor suction temperature sensor 109, the temperature Tsx detected by the individual gas temperature sensor 111-x of the operating indoor unit 200-x, and
The temperature Tex detected by the indoor heat exchanger temperature sensor 204-x of the operating indoor unit 200-x is captured (S30).
5).

Next, the detected temperature Te taken in S305
x and the corrected indoor heat exchanger temperature Teax, which is the sum of the indoor heat exchanger corrected temperature Tax derived in S304, is determined (S
306). Next, an average value Team of the corrected indoor heat exchanger temperature Teax obtained in S306 is obtained (S307).

Next, the detected temperature Ts taken in S305
A corrected total unit superheat degree SHat, which is a difference between c and the average value Team obtained in S307, is obtained (S308). Next, the detected temperature Tsx and detected temperature T
The individual unit superheat degree SHx, which is the difference from ex, is obtained (S309). Next, an average value SHm of the individual unit superheat degrees SHx obtained in S309 is obtained (S310).

Next, an individual unit superheat degree deviation DSHx, which is a difference between the individual unit superheat degree SHx obtained in S309 and the average value SHm obtained in S310, is obtained (S31).
1). Next, the corrected total unit superheat degree S obtained in S308
Hat and individual unit superheat degree deviation DS obtained in S311
A corrected individual unit superheat degree SHAx which is a sum with Hx is obtained (S312).

Next, the corrected individual unit superheat degree SHax obtained in S312 is set to a predetermined fixed reference superheat degree SH.
It is determined whether it is larger than 0 (S313). If it is larger (Yes in S313), the opening degree of the electric expansion valve 104-x is increased by one step (S314), and thereafter, the process proceeds to S301.

On the other hand, if it is not large (N in S313)
o), the corrected individual unit superheat degree Shax is the reference superheat degree S
It is determined whether it is smaller than H0 (S315). If it is smaller (Yes in S315), the opening of the electric expansion valve 104-x is reduced by one step (S316), and then S301.
Move to. On the other hand, if it is not small (N in S315)
o), proceed to S301 as it is.

With the above processing, the temperature Tsc on the suction side of the compressor 101, the indoor heat exchanger temperature Tex of the operating indoor unit 200-x, and the average of the indoor heat exchanger corrected temperatures of all the operating indoor units. From the value Tam, the individual gas temperature Tsx of the operating indoor unit 200-x, and the average value Tsm of the individual gas temperatures of all the operating indoor units, based on the corrected individual unit superheat degree Shax obtained by the following equation (3). The opening of the electric expansion valve 104-x is controlled.

[0065]

(Equation 3)

Thus, the individual gas temperature sensor 111-
Even if the temperatures detected by the temperature sensors 1, 111-2, 111-3 and the indoor heat exchanger temperature sensors 204-1, 204-2, 204-3 vary, the corresponding electric motor is controlled based on the degree of superheat of the indoor unit. As compared with the case where the opening degree of the expansion valve is controlled, the degree of superheat at the suction port of the compressor 101 can be controlled with higher accuracy, and variation and reduction in operating efficiency can be improved. Further, the temperature of the indoor heat exchanger is corrected based on the temperature drop of the refrigerant generated according to the operating frequency of the compressor 101 and the capacity of the target indoor unit, so that the above-described effect can be obtained in a wider operating range.

An air conditioner according to a fourth embodiment of the present invention will be described. Since the fourth embodiment has the configuration shown in FIG. 1 in the same manner as that described as the related art, only the characteristic portions will be described. FIG. 5 shows a flowchart of an operation performed by the control device 112 regarding the control of the opening degree of the electric expansion valves 104-1, 104-2, and 104-3 during the cooling operation.

Steps S401 to S412 are executed by the control device 112 in the third embodiment shown in FIG.
The description is omitted because it is the same as S312. When S412 is completed, the reference superheat degree difference D, which is the difference between the corrected individual unit superheat degree SHax and the preset reference superheat degree SH0.
SHAx is obtained (S413). By adding the reference superheat degree difference DShax obtained in S413, the integrated value ΔD of the reference superheat degree difference of the operating indoor unit 200-x is added.
SHAx is updated (S414).

Next, the integrated value ΣDS updated in S414
It is determined whether or not Hax is equal to or more than the upper limit (S41).
5). If it is equal to or more than the upper limit (Yes in S415), the opening of the electric expansion valve 104-x is increased by one step (S41).
6) Then, the process proceeds to S401. On the other hand, if it is not equal to or greater than the upper limit (No in S415), it is determined whether or not the integrated value ΣDSHax updated in S414 is equal to or less than the lower limit (S417).

If the value is equal to or smaller than the lower limit value (Yes in S417)
s) The opening degree of the electric expansion valve 104-x is reduced by one step (S418), and thereafter, the process proceeds to S401. On the other hand, if not less than the lower limit (No in S417), S4
Move to 01.

By the above processing, the temperature Tsc on the suction side of the compressor 101, the indoor heat exchanger temperature Tex of the operating indoor unit 200-x, and the average of the indoor heat exchanger corrected temperatures of all the operating indoor units. From the value Tam, the individual gas temperature Tsx of the operating indoor unit 200-x, and the average value Tsm of the individual gas temperatures of all the operating indoor units, the corrected individual unit superheat degree Shax and the reference obtained by the above equation 3 are calculated. The opening of the electric expansion valve 104-x is controlled based on the integrated value of the difference from the superheat degree SH0.

Thus, the individual gas temperature sensor 111-
Even if the temperatures detected by the temperature sensors 1, 111-2, 111-3 and the indoor heat exchanger temperature sensors 204-1, 204-2, 204-3 vary, the corresponding electric motor is controlled based on the degree of superheat of the indoor unit. As compared with the case where the opening degree of the expansion valve is controlled, the degree of superheat at the suction port of the compressor 101 can be controlled with higher accuracy, and variation and reduction in operating efficiency can be improved. Further, the temperature of the indoor heat exchanger is corrected based on the temperature drop of the refrigerant generated according to the operating frequency of the compressor 101 and the capacity of the target indoor unit, so that the above-described effect can be obtained in a wider operating range. Further, the degree of superheat at the suction port of the compressor can be controlled more smoothly and finely.

The control of the degree of opening of the electric expansion valve by the method shown in each of the above embodiments may be performed not only during the cooling operation but also during the heating operation. In each of the above embodiments, the air conditioner has both the cooling and heating functions. However, the air conditioner may have one of the cooling and heating functions. The number of indoor heat exchangers is 2 or 4
It may be more than this.

[0074]

As described above, according to the air conditioner of the present invention, as compared with the case where the opening degree of the corresponding electric expansion valve is controlled based on the degree of superheat of the indoor unit, the suction port of the compressor is improved. , The degree of superheat can be controlled with high accuracy, and variations and reductions in operating efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an air conditioner.

FIG. 2 is a flowchart of an operation related to control of the opening degree of the electric expansion valve according to the first embodiment.

FIG. 3 is a flowchart of an operation relating to control of an opening degree of an electric expansion valve according to a second embodiment.

FIG. 4 is a flowchart of an operation related to control of an opening degree of an electric expansion valve according to a third embodiment.

FIG. 5 is a flowchart of an operation related to control of an opening degree of an electric expansion valve according to a fourth embodiment.

FIG. 6 is a flowchart of an operation relating to control of the opening degree of the electric expansion valve in the related art.

FIG. 7 is a diagram showing a relationship between a degree of superheat at a suction port of a compressor and a degree of superheat of an indoor unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 101 Compressor 102 Outdoor heat exchanger 103 Outdoor fan 104-1, 104-2, 104-3 Electric expansion valve 105 Four-way valve 106 Oil separator 107 Oil separator capillary tube 108 Compressor discharge temperature sensor 109 Compressor suction temperature sensor 110 outdoor heat exchanger temperature sensor 111-1, 111-2, 111-3 individual gas temperature sensor 112 controller 200-1, 200-2, 200-3 indoor unit 201-1, 201-2, 201-3 indoor Heat exchanger 202-1, 202-2, 202-3 Indoor fan 203-1, 203-2, 203-3 Indoor temperature sensor 204-1, 204-2, 204-3 Indoor heat exchanger temperature sensor 205-1 , 205-2, 205-3 Control device

Claims (6)

[Claims] 1. An air conditioner comprising: a plurality of indoor heat exchangers for one compressor; and means for controlling a flow rate of a refrigerant for each of the plurality of indoor heat exchangers. A means for detecting a compressor suction temperature which is a temperature of a refrigerant sucked into the compressor; a means for detecting a temperature of an indoor heat exchanger which is a temperature of a refrigerant inside each indoor heat exchanger; and an indoor heat exchanger. And between the compressor, means for detecting for each indoor heat exchanger the individual refrigerant temperature that is the temperature of the refrigerant on the indoor heat exchanger side than the branch point on the side where the outdoor heat exchanger does not exist, The difference between the compressor suction temperature and the average of the indoor heat exchanger temperatures of all the indoor units in operation is the total unit superheat,
The difference between the individual refrigerant temperature of the indoor unit and the temperature of the indoor heat exchanger is an individual unit superheat degree, and the difference between the individual unit superheat degree and the average of the individual unit superheat degrees of all the operating indoor units is the individual unit overheat. Degree deviation, for each operating indoor unit, a corrected individual unit superheat degree which is the sum of the total unit superheat degree and the individual unit superheat degree deviation was obtained, and the corrected individual unit superheat degree was set in advance. Means for controlling the flow rate of the refrigerant to increase when the degree of superheat is larger than the reference superheat degree, and to decrease the flow rate of the refrigerant when the degree is lower than the reference superheat degree. 2. An air conditioner comprising: a plurality of indoor heat exchangers for one compressor; and means for controlling the flow rate of the refrigerant for each of the plurality of indoor heat exchangers. A means for detecting a compressor suction temperature which is a temperature of a refrigerant sucked into the compressor; a means for detecting a temperature of an indoor heat exchanger which is a temperature of a refrigerant inside each indoor heat exchanger; and an indoor heat exchanger. And between the compressor, means for detecting for each indoor heat exchanger the individual refrigerant temperature that is the temperature of the refrigerant on the indoor heat exchanger side than the branch point on the side where the outdoor heat exchanger does not exist, The difference between the compressor suction temperature and the average of the indoor heat exchanger temperatures of all the indoor units in operation is the total unit superheat,
The difference between the individual refrigerant temperature of the indoor unit and the temperature of the indoor heat exchanger is an individual unit superheat degree, and the difference between the individual unit superheat degree and the average of the individual unit superheat degrees of all the operating indoor units is an individual unit. Assuming that the superheat degree deviation and the sum of the superheat degrees of all units and the individual unit superheat degrees are the corrected individual unit superheat degrees, the corrected individual unit superheat degrees are set in advance at predetermined time intervals for each indoor unit during operation. Obtain and integrate the difference with the reference superheat degree that is the difference with the reference superheat degree, and when the integrated value is larger than a predetermined value, the flow rate of the refrigerant increases,
Means for controlling the flow rate of the refrigerant to decrease when the flow rate is smaller than a predetermined value. 3. The reference superheat degree is set for each combination of the capacity of the target indoor unit, the operating frequency of the compressor, and the capacity and the number of all the indoor units in operation. The air conditioner according to claim 1 or 2, wherein: 4. An air conditioner comprising: a plurality of indoor heat exchangers for one compressor; and means for controlling a flow rate of a refrigerant for each of the plurality of indoor heat exchangers. A means for detecting a compressor suction temperature which is a temperature of a refrigerant sucked into the compressor; a means for detecting a temperature of an indoor heat exchanger which is a temperature of a refrigerant inside each indoor heat exchanger; and an indoor heat exchanger. And between the compressor, means for detecting for each indoor heat exchanger the individual refrigerant temperature that is the temperature of the refrigerant on the indoor heat exchanger side than the branch point on the side where the outdoor heat exchanger does not exist, The sum of the indoor heat exchanger temperature and the corrected indoor heat exchanger temperature is corrected.The indoor heat exchanger temperature, the difference between the compressor suction temperature and the average of the corrected indoor heat exchanger temperature of the operating indoor unit is calculated. Unit superheat, the individual refrigerant temperature of the indoor unit and The difference of the individual units superheat the serial indoor heat exchanger temperature,
Assuming that the difference between the individual unit superheat degree and the average of the individual unit superheat degrees of all the indoor units in operation is an individual unit superheat degree deviation, the total unit superheat degree and the individual Determine the corrected individual unit superheat degree which is the sum of the unit superheat degree deviation, and when the corrected individual unit superheat degree is larger than a preset reference superheat degree, the flow rate of the refrigerant increases; Means for controlling the flow rate of the air to decrease. 5. An air conditioner comprising: a plurality of indoor heat exchangers for one compressor; and means for controlling the flow rate of the refrigerant for each of the plurality of indoor heat exchangers. A means for detecting a compressor suction temperature which is a temperature of a refrigerant sucked into the compressor; a means for detecting a temperature of an indoor heat exchanger which is a temperature of a refrigerant inside each indoor heat exchanger; and an indoor heat exchanger. And between the compressor, means for detecting for each indoor heat exchanger the individual refrigerant temperature that is the temperature of the refrigerant on the indoor heat exchanger side than the branch point on the side where the outdoor heat exchanger does not exist, Correct the sum of the indoor heat exchanger temperature and a preset indoor heat exchanger correction temperature, the indoor heat exchanger temperature, the compressor suction temperature and the average of the corrected indoor heat exchanger temperature of the operating indoor unit and The difference between the degree of superheat of all units and the The difference between the different refrigerant temperature and the indoor heat exchanger temperature is an individual unit superheat degree, the difference between the individual unit superheat degree and the average of the individual unit superheat degrees of all the operating indoor units is the individual unit superheat deviation, Assuming that the sum of the superheat degrees of all units and the individual unit superheat degree is a corrected individual unit superheat degree, the corrected individual unit superheat degree and a preset reference superheat are set at predetermined time intervals for each indoor unit during operation. Degree and the degree of superheat difference is calculated and integrated, if the integrated value is greater than a predetermined value, the flow rate of the refrigerant increases,
Means for controlling the flow rate of the refrigerant to decrease when the flow rate is smaller than a predetermined value. 6. The indoor heat exchanger correction temperature is set for each combination of the capacity of the target indoor unit, the operating frequency of the compressor, and the capacity and number of all the indoor units in operation. The air conditioner according to claim 4 or 5, wherein: