JP2003156260A - Control method for air-conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method for an air-conditioner allowing the operation while maintaining always best refrigerating cycles without using additional sensors. SOLUTION: An ambient temperature sensor 9 for detecting an ambient temperature To, an indoor heat exchange temperature sensor 10 for detecting an intermediate temperature of the indoor heat exchanger 5 and a discharge temperature sensor 8 for detecting a discharge temperature Td of a compressor 1 are provided so that a condensation temperature Tc during cooling operation is calculated from a rotating speed N of the compressor, an evaporation temperature Te during cooling operation detected by the indoor heat exchange temperature sensor, a best degree of superheat SH is set corresponding to the evaporation temperature Te and the condensation temperature Tc and a target discharge temperature Tmd is calculated therefrom. The opening of an electronic expansion valve 4 is controlled so that the discharge temperature Td approaches the target discharge temperature Tmd. The operation is thus allowed in the best refrigerating cycles without using an intermediate point temperature sensor for an outdoor heat exchanger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for an air conditioner, and more particularly to a control method that enables operation while maintaining an optimum refrigeration cycle.

[0002]

2. Description of the Related Art Conventionally, a refrigeration cycle is constructed by sequentially connecting a compressor, a four-way valve, an outdoor heat exchanger, an electronic expansion valve, and an indoor heat exchanger. By switching the four-way valve, cooling is performed. During operation, the high-pressure refrigerant compressed by the compressor, the outdoor heat exchanger, the electronic expansion valve, the indoor heat exchanger in this order,
During heating operation, the air conditioner that flows through the indoor heat exchanger, the electronic expansion valve, and the outdoor heat exchanger in this order and operates while maintaining an optimal refrigeration cycle detects the evaporation temperature and compression suction pipe temperature of the refrigeration cycle. Then, the degree of superheat during operation is calculated, and the opening degree of the electronic expansion valve is controlled so that the degree of superheat becomes the optimum degree of superheat. However, in this control method, it is necessary to detect an accurate superheat degree, and in order to detect an accurate superheat degree, in addition to the indoor heat exchange intermediate temperature sensor normally used for protection control and the outdoor heat exchange temperature sensor, There is a problem that a sensor for detecting the indoor heat exchange inlet pipe temperature and the compressor suction pipe temperature is required, which causes a cost increase. Further, in order to solve the above problem, a reference temperature of the discharge pipe temperature of the compressor corresponding to each operation mode is obtained in advance, and the electronic expansion valve is opened so that the discharge pipe temperature becomes the reference temperature during operation. A method of controlling so as to adjust the degree is also used. However, in the case of this method, it is not possible to cope with changes in room temperature conditions, and there is a problem in that it is not possible to always maintain and operate an optimum refrigeration cycle, although it is possible under constant room temperature conditions.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a method for controlling an air conditioner that enables operation that always maintains an optimum refrigeration cycle without adding a sensor. Is intended.

[0004]

In order to solve the above problems, the present invention constitutes a refrigeration cycle by sequentially connecting a compressor, a four-way valve, an outdoor heat exchanger, an electronic expansion valve, and an indoor heat exchanger. By switching the four-way valve, the high-pressure refrigerant compressed by the compressor during the cooling operation is the outdoor heat exchanger, the electronic expansion valve, the indoor heat exchanger in this order, and the indoor heat exchanger during the heating operation. , An electronic expansion valve, an outdoor heat exchanger, and an air conditioner that adjusts the opening degree of the electronic expansion valve so as to achieve an optimum refrigeration cycle, and an outside air temperature sensor that detects an outside air temperature To; An indoor heat exchange temperature sensor for detecting the intermediate temperature of the indoor heat exchanger and a discharge temperature sensor for detecting the discharge temperature of the compressor are provided, and the compressor is operated at a predetermined rotation speed N to start the cooling operation. , Detection of the outside air temperature sensor The outside air temperature To, the evaporation temperature Te detected by the indoor heat exchange temperature sensor, the rotation speed N of the compressor, the outside air temperature To and the evaporation temperature Te are multiplied by constant coefficients a, b and c, respectively. Then, a constant coefficient d is calculated for each of the condensing temperature Tc calculated by adding these and the superheat degree SH set to be optimum on the Mollier diagram for the detected evaporation temperature Te and condensing temperature Tc. , E,
The discharge temperature Trd in the theoretical cycle is calculated by multiplying and adding f, and the discharge temperature T in the theoretical cycle is calculated.
The target discharge temperature Tmd is set to rd, and the opening degree of the electronic expansion valve is adjusted so that the discharge temperature Td of the compressor approaches the target discharge temperature Tmd.

A correction value Thd calculated by multiplying the number of revolutions N of the compressor and the condensing temperature Tc by constant coefficients g and h and adding them together is used as the discharge temperature Trd in the theoretical cycle.
Is used as the target discharge temperature Tmd.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a control method for an air conditioner according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a control method for an air conditioner according to the present invention. In FIG. 1, 1 is a compressor for compressing a gas refrigerant, 2 is a four-way valve for switching the direction of the refrigerant, 3 is an outdoor heat exchanger for exchanging heat between the refrigerant and the outside air, and 4 is compressed by adjusting its opening degree. Electronic expansion valves 5 for reducing the pressure of the refrigerant are indoor heat exchangers for exchanging heat between the refrigerant and the indoor air, and these are sequentially piped to form a refrigeration cycle. Then, by switching the four-way valve 2, the cooling operation and the heating operation are switched, and the compressed refrigerant compressed by the compressor 1 is transferred to the outdoor heat exchanger 3, the electronic expansion valve 4, and the indoor heat during the cooling operation. Exchanger 5
In this order, during the heating operation, the indoor heat exchanger 5, the electronic expansion valve 4,
The outdoor heat exchanger 3 is circulated in this order and circulated to the compressor 1.

Further, 6 is an outdoor unit controller provided in the outdoor unit, 7 is an indoor unit controller provided in the indoor unit, 8 is a discharge temperature sensor for detecting a discharge temperature Td of the compressor 1, and 9 is an outside air temperature. An outdoor air temperature sensor 10 for detecting is an indoor heat exchange temperature sensor for detecting an intermediate temperature of the indoor heat exchanger, and the discharge temperature sensor 8 and the outdoor air temperature sensor 9 are directly connected to the outdoor unit control unit 6 to provide indoor heat. The cross temperature sensor 10 is connected to the outdoor unit controller 6 via the indoor unit controller 7.
The indoor heat exchange temperature sensor 10 detects the evaporation temperature Te of the refrigerant during the cooling operation.

FIG. 2 is a flow chart for explaining the control method of the air conditioner of the present invention, FIG. 3 is a diagram showing a theoretical cycle on the Mollier diagram, and FIG. 4 is a condensing temperature Tc during cooling.
It is a figure which shows the relationship between the outside temperature, the rotation speed N of a compressor, and evaporation temperature Te. Hereinafter, a control method during cooling will be described with reference to FIGS. The cooling operation is started by switching the four-way valve 2 to the cooling side and operating the compressor 1 at a predetermined rotation speed N determined by the set temperature, the room temperature and the like.
When the cooling operation is started, the rotation speed N of the compressor 1 and
Outside air temperature To detected by the outside air temperature sensor 9
And the evaporation temperature Te detected by the indoor heat exchange temperature sensor 10 are input to the outdoor unit controller 6 (ST
1). As shown in FIG. 4, the condensation temperature Tc is the outside air temperature T.
o, the rotation speed N of the compressor, and the evaporation temperature Te, which are proportional to each other. Therefore, the rotation speed N, the outside air temperature To, and the evaporation temperature Te are multiplied by constant coefficients a, b, and c, respectively. The condensing temperature Tc is calculated by adding Tc = a × N + b × To + c × Te (a, b, and c are coefficients) ... Equation 1 (ST2). From the condensation temperature Tc thus obtained and the evaporation temperature Te, the superheat degree S at which the refrigeration cycle becomes optimum on the Mollier diagram shown in FIG.
By inputting H (ST3), the point A in FIG. 3 is obtained, and the evaporation temperature Te, the condensation temperature Tc, and the superheat degree SH are multiplied by constant coefficients d, e, f, respectively, and these are added to obtain the theoretical cycle. The discharge temperature Trd at this time is calculated as Trd = d × Te + e × Tc + f × SH (d, e, f are coefficients) ... Equation 2 (ST4). In addition, the rotational speed N of the compressor 1 and the condensing temperature Tc are respectively multiplied by constant coefficients g and h, and the correction values Thd are calculated by adding these, Thd = g × N + h × Tc (g, h Is a coefficient) ... Calculated as Equation 3 (ST5). Then, the correction value Thd is added to the discharge temperature Trd during the theoretical cycle, and
The target value Tmd of the discharge temperature shown in is calculated as Tmd = Trd + Thd (Equation 4) (ST6). Next, the discharge temperature Td detected by the discharge temperature sensor 8 is input to the outdoor unit control unit 6 so that the discharge temperature Td approaches the target value Tmd of the discharge temperature (ST7) to open the electronic expansion valve 4. Adjust the degree (ST8).

As described above, the number of revolutions N of the compressor relating to the indoor temperature conditions, the evaporation temperature Te, the outside air temperature, and the condensing temperature Tc relating to the performance of the compressor so that the discharge temperature Td becomes the optimum refrigeration cycle. Also, since the opening of the electronic expansion valve 4 is adjusted so as to approach the target value Tmd of the discharge temperature calculated based on the correction value related to the performance peculiar to the compressor, the indoor temperature condition, the outside air temperature condition, and the performance of the compressor. It is possible to provide a control method for an air conditioner that can operate in an optimum refrigeration cycle even if conditions change.

[0010]

As described above, according to the air conditioner of the present invention, the outside air temperature To and the evaporation temperature Te are detected during the cooling operation, and the rotation speed N of the compressor and the outside air temperature To are detected. Calculating the condensation temperature Tc from the evaporation temperature Te,
The detected evaporation temperature Te and the calculated condensation temperature Tc
And superheat degree S set to be optimum on the Mollier diagram
The discharge temperature Trd in the theoretical cycle is calculated by multiplying H and a constant coefficient d, e, f and adding them, and the discharge temperature Trd in the theoretical cycle is set as the target discharge temperature Tmd. Since the opening temperature of the electronic expansion valve is adjusted so that the discharge temperature Td of the battery is close to the target discharge temperature Tmd, even if the temperature sensor for detecting the condensation temperature is not provided, the optimum refrigeration is always performed during the cooling operation. It is possible to maintain a cycle of superheat.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a control method for an air conditioner according to the present invention.

FIG. 2 is a flowchart illustrating the operation of the control method for an air conditioner according to the present invention.

FIG. 3 is a Mollier diagram for explaining the operation of the control method for an air conditioner according to the present invention.

FIG. 4 is a diagram showing a relationship between a condensation temperature Tc during cooling, an outside air temperature, a rotation speed N of a compressor, and an evaporation temperature Te.

FIG. 5 is a schematic configuration diagram showing a control method of a conventional air conditioner.

[Explanation of symbols]

1 compressor 2 four-way valve 3 outdoor heat exchanger 4 Electronic expansion valve 5 Indoor heat exchanger 6 Outdoor unit control unit 7 Indoor unit controller 8 Discharge temperature sensor 9 Outside air temperature sensor 10 Indoor heat exchange temperature sensor

Claims (2)

[Claims] 1. A refrigeration cycle is constructed by sequentially connecting a compressor, a four-way valve, an outdoor heat exchanger, an electronic expansion valve, and an indoor heat exchanger, and by switching the four-way valve, a cooling operation is performed. The high-pressure refrigerant compressed by the compressor flows in the order of the outdoor heat exchanger, the electronic expansion valve, and the indoor heat exchanger, and in the heating operation, the indoor heat exchanger, the electronic expansion valve, and the outdoor heat exchanger in that order, which is optimal. In an air conditioner in which the opening degree of the electronic expansion valve is adjusted to form a refrigeration cycle, an outside air temperature sensor that detects an outside air temperature To and an indoor heat exchange temperature sensor that detects an intermediate temperature of the indoor heat exchanger And a discharge temperature sensor for detecting the discharge temperature of the compressor. When the compressor is operated at a predetermined rotation speed N to start the cooling operation, the outside air temperature To detected by the outside air temperature sensor and the indoor temperature Detection of heat exchanger temperature sensor That the evaporation temperature Te and, wherein the rotational speed N of the compressor and the outside air temperature To evaporation temperature T
e is multiplied by constant coefficients a, b and c, respectively, and these are added together to obtain the optimum condensation temperature Tc and the detected evaporation temperature Te and condensation temperature Tc on the Mollier diagram. The superheat degree SH set as above is multiplied by constant coefficients d, e, and f, respectively, and added to calculate the discharge temperature Trd during the theoretical cycle, and the discharge temperature Trd during the theoretical cycle is calculated as the target discharge temperature. A control method for an air conditioner, wherein the opening degree of the electronic expansion valve is adjusted so that the discharge temperature Td of the compressor approaches the target discharge temperature Tmd as Tmd. 2. A correction value Thd calculated by multiplying the number of revolutions N of the compressor and the condensing temperature Tc by constant coefficients g and h, and adding them to obtain a discharge temperature Tr during the theoretical cycle.
The method for controlling an air conditioner according to claim 1, wherein a value added to d is used as the target discharge temperature Tmd.