JPH08327122A - Air conditioner - Google Patents

Abstract

PURPOSE: To provide an air conditioner capable of stabilizing the quantity of refrigerant flowing to an indoor heat exchanger in excellent response to the optimum value, and thereby always operating suitably. CONSTITUTION: The total amount of the openings flow rate regulating valves 11, 21, 31 are obtained from the operating frequency of a compressor 1, indoor temperatures detected by indoor units B1 , B2 , B3 , atmospheric temperature detected by an outdoor unit A and capacity rank decided at the indoor unit. The distribution ratio of the refrigerant to the indoor units is obtained according to the circumstances of the indoor units. The target value of the opening of the each regulating valve is obtained according to the total value and the ratio, and the opening of each regulating valve is set to the target value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-type air conditioner having an outdoor unit and a plurality of indoor units.

[0002]

2. Description of the Related Art In a multi-type air conditioner equipped with an outdoor unit having a compressor and an outdoor heat exchanger, and a plurality of indoor units each having an indoor heat exchanger, an air conditioning load of a room in which each indoor unit is installed. Is detected and the operating frequency of the compressor is controlled according to the sum of these air conditioning loads. As a result, the optimum cooling capacity or heating capacity corresponding to the total air conditioning load can be obtained.

However, when the operating frequency changes, the flow rate of the refrigerant in the refrigeration cycle changes, and the amount of the refrigerant flowing through each indoor heat exchanger also changes. This change in the refrigerant flow rate appears as a change in the degree of superheat of the refrigerant in each indoor heat exchanger (evaporator) during cooling. This superheat degree needs to be maintained at a constant value in order to ensure an appropriate refrigerant flow rate to each indoor heat exchanger.

Therefore, a flow rate adjusting valve is provided in the refrigerant pipe connected to each indoor unit, and each flow rate adjusting valve is controlled so that the superheat degree of the refrigerant in each indoor heat exchanger maintains a constant value (= set value). The opening is adjusted. In this case, a temperature sensor is attached to each of the indoor heat exchanger and the gas side pipe of the refrigeration cycle, and the difference between the temperatures detected by the temperature sensors is detected as the degree of superheat.

[0005]

In the above superheat degree control, when the opening degree of the flow rate adjusting valve is adjusted, the flow rate of the refrigerant to the indoor heat exchanger first changes, which results in a change in the superheat degree. Appears. Then, this change is captured, and the opening degree of the flow rate adjusting valve is adjusted again.

In such so-called feedback control, there is a time delay from the opening adjustment to the change in superheat degree. Due to the influence of this time delay, the degree of superheat does not immediately converge to the set value, but rather converges while repeating amplitude fluctuations around the set value. That is, a response delay occurs, the amount of the refrigerant flowing through each indoor heat exchanger is not stable at an optimum value, and proper operation becomes difficult.

FIG. 5 shows an example of detecting the degree of superheat by the temperature sensor. However, there is a limit of detection such that the temperature above the ambient temperature of the sensor cannot be detected on the overheat side and 0 deg or less cannot be detected on the liquid back side. The reality is that the degree of superheat cannot be properly captured. This detection error, combined with the above-mentioned response delay, makes the operation of the refrigeration cycle more and more unstable.

The present invention takes the above circumstances into consideration,
It is an object of the present invention to provide an air conditioner capable of stabilizing the amount of refrigerant flowing through each indoor heat exchanger to an optimum value with good responsiveness, thereby always enabling proper operation. .

[0009]

The air conditioner of the first invention is an outdoor unit having a compressor and an outdoor heat exchanger,
A plurality of indoor units, each having an indoor heat exchanger,
It is provided with a plurality of flow rate adjusting valves for adjusting the amount of refrigerant flowing from the outdoor unit to each indoor unit,
Based on the operating frequency of the compressor, the indoor temperature detected by each indoor unit, the outside air temperature detected by the outdoor unit, and the capacity rank set for each indoor unit, calculate the total value of the opening of each flow rate adjustment valve. A total value detecting means to be obtained, a distribution ratio detecting means to obtain a distribution ratio of the refrigerant to each indoor unit according to the situation of each indoor unit, and a target of the opening degree of each flow rate adjusting valve according to the total value and the distribution ratio Target value detection means for obtaining a value and opening degree setting means for setting the opening degree of each flow rate adjusting valve to the target value are provided.

In the air conditioner of the second invention, the total value detecting means of the first invention corrects the calculated total value by integrating the coefficients corresponding to the operating numbers of the indoor units. In the air conditioner of the third invention, the distribution ratio detecting means of the first invention is set for the indoor temperature detected by each indoor unit, the indoor heat exchanger temperature detected by each indoor unit, and each indoor unit. The distribution ratio is obtained according to the capacity rank that is set, or according to the difference between the indoor temperature and the indoor heat exchanger temperature detected for each indoor unit.

In the air conditioner of the fourth invention, the opening degree setting means of the first invention operates the opening degree of each flow rate adjusting valve according to the difference between the current opening degree of each flow rate adjusting valve and the target value. It determines the amount.

[0012]

In the air conditioner of the first aspect of the invention, the operating frequency of the compressor, the indoor temperature detected by each indoor unit, the outside air temperature detected by the outdoor unit, and the capacity rank determined for each indoor unit are set. Based on this, the total value of the openings of the flow rate adjusting valves is obtained. Further, the distribution ratio of the refrigerant to each indoor unit is obtained according to the situation of each indoor unit. A target value of the opening degree of each flow rate adjusting valve is obtained according to the total value and the distribution ratio, and the opening degree of each flow rate adjusting valve is set to the target value.

In the air conditioner of the second invention, in the first invention, the obtained total value is corrected by integrating the coefficients corresponding to the operating numbers of the indoor units. In the air conditioner of the third invention, in the first invention, the distribution ratio is determined for the indoor temperature detected by each indoor unit, the indoor heat exchanger temperature detected by each indoor unit, and each indoor unit. It is calculated according to the capacity rank of the indoor unit or the difference between the indoor temperature and the indoor heat exchanger temperature detected for each indoor unit. In the air conditioner of the fourth invention,
In the first aspect of the invention, the manipulated variable of the opening degree for each flow rate adjusting valve is determined according to the difference between the current opening degree of each flow rate adjusting valve and the target value.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, A is an outdoor unit and B is
₁ , B ₂ , B ₃ are indoor units, and the following refrigeration cycle is configured in these units.

An outdoor heat exchanger 3 is connected to a discharge port of the compressor 1 via a four-way valve 2, and a liquid side main pipe W is connected to the outdoor heat exchanger 3. Liquid side main pipe W is liquid side branch pipe W ₁ , W ₂ , W
_It is branched into ₃ and the indoor heat exchangers 12 and 2 are connected to the respective liquid side branch pipes.
2, 32 are connected.

A flow rate adjusting valve 1 for the liquid side branch pipes W ₁ , W ₂ and W _3.
1, 21, 31 are provided. These flow rate adjusting valves are pulse motor valves (PMV) whose opening degree changes continuously according to the number of drive pulses supplied.

Gas side branch pipes G ₁ , G ₂ and G ₃ are connected to the indoor heat exchangers 12, 22 and 32. These gas side branch pipes are gathered together in the gas side main pipe G, and the gas side main pipe G is connected to the suction port of the compressor 1 via the four-way valve 2.

An outdoor fan 4 and an indoor temperature sensor 5 are provided near the outdoor heat exchanger 3. One end of a defrosting bypass 6 is connected to a pipe between the discharge port of the compressor 1 and the four-way valve 2, and the other end of the bypass 6 is connected to the liquid side main pipe W. The bypass 6 is provided with a two-way valve 7 for flow control.

Indoor fans 13, 23, 33 are provided near the indoor heat exchangers 12, 22, 32. Heat exchanger temperature sensors 14, 24, 3 for the indoor heat exchangers 12, 22, 32
4 are attached respectively.

For the indoor units B ₁ , B ₂ and B ₃ , the capacity rank Rx based on the capacity of the indoor heat exchangers 12, 22 and 32 is predetermined. The control circuit is shown in FIG.

The outdoor control unit 50 of the outdoor unit A is connected to the commercial AC power supply 40. The outdoor control unit 50 includes a microcomputer and its peripheral circuits. To the outdoor control unit 50, the flow rate adjusting valves 11, 21, 31, the four-way valve 2, the outdoor fan motor 4M, the indoor temperature sensor 5, the two-way valve 7, and the inverter circuit 51 are connected.

The inverter circuit 51 rectifies the voltage of the power supply 40, converts it into a voltage of a frequency and level according to a command from the outdoor control unit 50, and outputs it. This output becomes drive power for the compressor motor 1M.

The indoor units B ₁ , B ₂ and B ₃ each include an indoor control unit 60. The indoor control unit 60 includes a microcomputer and its peripheral circuits. The indoor temperature sensor 15 (and 25, 3
5), the heat exchanger temperature sensor 14 (and 24, 34),
The indoor fan motor 13M (and 23M, 32M) and the light receiving unit 61 are connected. The light receiving unit 61 receives infrared light emitted from a remote control type operation device (hereinafter, abbreviated as a remote controller) 62.

The indoor control unit 60 and the outdoor control unit 50 are connected by a power supply line ACL and a serial signal line SL for data transfer, respectively. Each indoor control unit 60 has the following as main functional means.

[1] A means for notifying the outdoor unit A of the operating conditions (including the set temperature Ts) by operating the remote controller 62 by a serial signal synchronized with the power supply voltage. [2] The difference between the detected temperature Ta of the indoor temperature sensor 15 (and 25, 35) and the set temperature Ts set by the remote controller 62 is detected as an air conditioning load, and the required capacity (frequency value) corresponding to the air conditioning load is detected. A means to notify the outdoor unit A by a serial signal synchronized with the power supply voltage.

[3] Indoor temperature sensor 15 (and 25,
A means for notifying the outdoor unit A of the detection temperature Ta of 35), the detection temperature Tc of the heat exchanger temperature sensor 14 (and 24, 34), and the capacity rank Rx of the indoor unit by a serial signal synchronized with the power supply voltage.

The outdoor control unit 50 has the following as main functional means. [1] Based on the cooling operation mode command from each indoor unit, the refrigerant discharged from the compressor 1 is supplied with the four-way valve 2, the outdoor heat exchanger 3, the flow rate adjusting valves 11, 21, 31 and the indoor heat exchanger 1.
2, 22, 32, means for passing through the four-way valve 2 and returning to the compressor 1 to execute cooling operation.

[2] Based on the heating operation mode command from each indoor unit, the four-way valve 2 is switched, and the refrigerant discharged from the compressor 1 is transferred to the four-way valve 2 and the indoor heat exchangers 12, 22, 3.
2, means for performing heating operation by returning to the compressor 1 through the flow rate adjusting valves 11, 21, 31 and the outdoor heat exchanger 3 and the four-way valve 2.

[3] Means for controlling the operating frequency F of the compressor 1 (= output frequency of the inverter circuit 51) during cooling and heating operations in accordance with the sum of the required capacities from the indoor units.

[4] Means for obtaining the average value Tax of the indoor temperature Ta notified from each indoor unit and the average value Rx of the capacity rank R also notified from each indoor unit during the cooling operation.

[5] During cooling operation, based on the operating frequency F, the room temperature average value Tax, the temperature detected by the outdoor temperature sensor 5 (outside air temperature) To, and the capacity rank average value Rx,
Total value detecting means for obtaining the total value PCL of the opening degrees of the flow rate adjusting valves 11, 21, 31. (Actually, the indoor unit B ₁ ,
Since not all B ₂ and B ₃ are operated, the coefficient Di corresponding to the number of operating indoor units is added to the total value PCL to obtain the corrected total value PCLi (= Di · PC
L)).

[6] Distribution ratio detecting means for obtaining the distribution ratio H of the refrigerant to each indoor unit according to the situation of the indoor units B ₁ , B ₂ , B ₃ . (Indoor units B ₁ , B ₂ , B
The situation of ₃ is the indoor temperature T notified from each indoor unit.
a, Indoor heat exchanger temperature T known from each indoor unit
c and ability rank R informed from each indoor unit
Is. Or, the situation of the indoor units B ₁ , B ₂ , B ₃ is a comparison of the difference between the indoor temperature Ta and the indoor heat exchanger temperature Tc for each indoor unit).

[7] Correction total value PCLi and distribution ratio H
According to the target value Q of the opening of the flow rate adjusting valves 11, 21, 31
Target value detecting means for obtaining each t. [8] Opening degree setting means for setting the respective opening degrees Q of the flow rate adjusting valves 11, 21, 31 to the target value Qt. (Specifically, the operation amount of the opening is determined according to the difference between the current opening Q of the flow rate adjusting valves 11, 21, 31 and the target value Qt).

Next, the operation of the above configuration will be described with reference to the flowchart of FIG. When the cooling operation mode is set by each remote controller 62, the refrigerant discharged from the compressor 1 is
A cooling cycle that flows in the direction of the solid line arrow is formed, and the outdoor heat exchanger 3 becomes the condenser and the indoor heat exchangers 12, 22, 32.
Functions as an evaporator. As a result, the cooling operation is executed.

During the cooling operation, the operating frequency F (=
The output frequency of the inverter circuit 41) is the indoor unit B
It is controlled according to the sum of the required capacities of ₁ , B ₂ , and B ₃ .
Simultaneously with this operation frequency control, the average value Tax of the indoor temperature Ta known from each indoor unit is sequentially obtained, and the average value Rx of the capability rank R known from each indoor unit is also obtained.

The operating frequency F, the room temperature average value Tax,
The calculation of the following formula using the detected temperature (outside air temperature) To of the outdoor temperature sensor 5 and the average value Rx of the capability ranks is executed,
The total value PCL of the openings of the flow rate adjusting valves 11, 21, 31 is obtained. a ₁ , a ₂ , a ₃ , a ₄ , and a ₅ are constants.

[0037]

[Equation 1]

In practice, the indoor units B ₁ , B ₂ , B ₃
Not all are driven, so as in the following formula,
A coefficient Di corresponding to the number of operating indoor units is added to the total value PCL to obtain a corrected total value PCLi. The coefficient Di is stored in advance in the memory in the outdoor control unit 50 by the number corresponding to all combinations of the operating numbers of the indoor units B ₁ , B ₂ , and B ₃ .

[0039]

[Equation 2]

The conditions of the indoor units B ₁ , B ₂ , B ₃ such as the indoor temperature Ta and the indoor heat exchanger temperature T
The distribution ratio H of the refrigerant to each indoor unit is obtained according to c and each capability rank R.

The target values Qt of the opening degrees of the flow rate adjusting valves 11, 21, 31 are respectively calculated according to the calculated correction total value PCLi and the distribution ratio H. And the flow control valve 1
The opening Q of 1, 21, 31 is set to the target value Qt, respectively. That is, the opening degree setting condition shown in FIG. 4 is stored in the memory in the outdoor control unit 50, and the difference between the current opening degree Q and the target value Qt is applied to this opening degree setting condition to determine the opening degree. The operation amount ΔQ is determined, and the opening of the flow rate adjusting valve is operated by the operation amount ΔQ. The numerical values in FIG. 4 represent the number of drive pulses. For example, when the difference between the current opening Q and the target value Qt corresponds to 50 drive pulses, the operation amount Δ of the opening is
As Q, 10 drive pulses are determined.

Here, the indoor units B ₁ , B ₂ , B ₃
As the situation, the difference between the indoor temperature Ta and the indoor heat exchanger temperature Tc of each indoor unit is captured, and the comparison is described as the distribution ratio H. In this case, the target value Q
t is required. The fractional part of the following equation corresponds to the distribution ratio H.

[0043]

(Equation 3)

The value of j (1 to n) corresponds to the total number of indoor units, and the indoor temperature Ta and the indoor heat exchanger temperature of each indoor unit B ₁ , B ₂ , B ₃ are used as the denominator of the fractional part. The total value of the difference from Tc {= absolute value of (Ta-Tc)} is obtained. i corresponds to each of the indoor units B ₁ , B ₂ , and B ₃ .

In this way, the distribution amount of the refrigerant to each indoor heat exchanger is estimated in a feed-forward manner from the present operating condition and load condition and controlled to flow to the indoor heat exchangers 12, 22, 32. The amount of the refrigerant can be stabilized to the optimum value with good responsiveness, and proper operation can always be performed.

In the above embodiment, the number of indoor units is three.
Although the case of the number of indoor units has been described as an example, the present invention can be similarly applied to the case where there are two or four or more indoor units. Further, in the above-mentioned embodiment, the superheat control which is the feedback control is not used for setting the target value Qt of the opening, but at the stage of determining the target value Qt in the above-mentioned embodiment, the feedback of the conventional method is used. The target value Qt may be determined by adding / subtracting the correction opening degree for each flow rate adjusting valve determined by the superheat control, which is the control, to the distributed correction total value. According to this, the amount of the refrigerant can be stabilized to the optimum value with good responsiveness.

[0047]

As described above, according to the present invention, the operating frequency of the compressor, the indoor temperature detected by each indoor unit, the outside air temperature detected by the outdoor unit, and each indoor unit are determined. Calculate the total value of the opening of each flow rate adjusting valve based on the capacity rank, calculate the distribution ratio of the refrigerant to each indoor unit according to the situation of each indoor unit, and then calculate each flow rate adjusting valve according to these total value and distribution ratio. Since the target value of the opening of the indoor heat exchanger is determined and the opening of each flow rate adjusting valve is set to the target value, it is possible to stabilize the amount of the refrigerant flowing through each indoor heat exchanger to the optimum value with good responsiveness. It is possible to provide an air conditioner that always enables proper operation.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a refrigeration cycle according to an embodiment of the present invention.

FIG. 2 is a block diagram of a control circuit of the embodiment.

FIG. 3 is a flowchart for explaining the operation of the embodiment.

FIG. 4 is a diagram showing opening control conditions in the embodiment.

FIG. 5 is a diagram showing an example of superheat detection by a conventional temperature sensor.

[Explanation of symbols]

A ... outdoor unit, B ₁ , B ₂ , B ₃ ... indoor unit,
1 ... Variable capacity compressor, 2 ... Four-way valve, 3 ... Outdoor heat exchanger,
11, 21, 31 ... Flow rate adjusting valve, 12, 22, 32 ... Indoor heat exchanger, 14, 24, 34 ... Heat exchanger temperature sensor,
15, 25, 35 ... Indoor temperature sensor, 50 ... Outdoor control unit, 60 ... Indoor control unit.

Claims (4)

[Claims] 1. An outdoor unit having a compressor and an outdoor heat exchanger, a plurality of indoor units each having an indoor heat exchanger, and a plurality of flow rate adjustments for adjusting the amount of refrigerant flowing from the outdoor unit to each indoor unit. In an air conditioner equipped with a valve, each flow rate is based on the operating frequency of the compressor, the indoor temperature detected by each indoor unit, the outside air temperature detected by the outdoor unit, and the capacity rank set for each indoor unit. Total value detection means for obtaining the total value of the opening of the adjusting valve, distribution ratio detection means for obtaining the distribution ratio of the refrigerant to each indoor unit according to the situation of each indoor unit, and according to the total value and the distribution ratio Target value detecting means for obtaining a target value of the opening degree of each flow rate adjusting valve, and opening degree setting means for setting the opening degree of each flow rate adjusting valve to the target value are provided. Air conditioner to be. 2. The air conditioner according to claim 1, wherein the total value detecting means corrects the calculated total value by integrating a coefficient corresponding to the number of operating indoor units. Machine. 3. The air conditioner according to claim 1, wherein the distribution ratio detecting means includes an indoor temperature detected by each indoor unit, an indoor heat exchanger temperature detected by each indoor unit, and each indoor unit. An air conditioner characterized by obtaining a distribution ratio according to a defined capacity rank or according to a contrast of a difference between an indoor temperature and an indoor heat exchanger temperature detected for each indoor unit. 4. The air conditioner according to claim 1, wherein the opening degree setting means sets the operation amount of the opening degree for each flow rate adjusting valve according to the difference between the current opening degree of each flow rate adjusting valve and the target value. An air conditioner that is characterized by: