JPH10253170A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner which can improve its reliability and reduce its consumed power by decreasing the number of times of starts and stops of a compressor. SOLUTION: A controller 10 controls the degree of superheat of the suction pipe of a compressor 1 so that an operating capacity becomes maximum when the temperature difference between room temperature and setting temperature is higher than an upper threshold value and a coefficient of performance COP becomes maximum when the temperature difference is smaller than a lower threshold value. Further, the controller 1 10 controls the degree of superheat of the suction pipe of the compressor 1 so that the degree of superheat of the suction pipe is substantially inversely proportional to the temperature difference from the degree of superheat of the inlet pipe obtained when the operating capacity is maximum to that when the coefficient of performance COP is maximum, in case the temperature difference is within a range from the upper threshold value to the lower threshold value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling driving performance and a coefficient of performance (COP).
The present invention relates to an air conditioner for controlling ce).

[0002]

2. Description of the Related Art Conventionally, as an air conditioner, there is an air conditioner in which the operating frequency of a compressor is constant and always operates at a maximum capacity.
In this air conditioner, for example, even if the temperature difference between the indoor temperature and the set temperature in the cooling operation becomes small, the operation continues at the maximum capacity, and after the indoor temperature reaches the set temperature, the indoor temperature is set for a while. When the temperature drops below the temperature, the thermostat turns off and the compressor stops. Thereafter, when the room temperature gradually rises, the room temperature becomes higher than the set temperature, and the temperature difference between the room temperature and the set temperature increases, the thermo-on is performed.
The compressor starts again.

[0003]

However, the air conditioner described above has a drawback that the reliability is reduced because the operation of the compressor is repeatedly started / stopped in accordance with the fluctuation of the room temperature, as shown in FIG. In addition, the air conditioner has a drawback that power consumption increases because the air conditioner always operates at the maximum capacity.

An object of the present invention is to provide an air conditioner that can improve reliability and reduce power consumption by reducing the number of times the compressor starts and stops.

[0005]

According to one aspect of the present invention, there is provided an air conditioner having a refrigerant circuit in which a compressor, a condenser, an electric expansion valve, and an evaporator are connected in a ring shape. In the above, when the temperature difference between the room temperature and the set temperature is larger than the upper threshold, while controlling the degree of superheat of the suction pipe of the compressor so that the operating capacity is maximized, the temperature difference is lower When the temperature difference is within the range from the upper threshold to the lower threshold, the suction pipe superheat degree of the compressor is controlled so that the coefficient of performance COP is maximized. In accordance with the temperature difference, a control device that controls the suction pipe superheat degree of the compressor between the suction pipe superheat degree when the operating capacity is maximized and the suction pipe superheat degree when the coefficient of performance COP is maximized. It is characterized by having.

According to the air conditioner of the first aspect, in the refrigerant circuit having the above structure, the superheat degree of the suction pipe of the compressor when the operating capacity is maximized is as low as about 0 ° C., and the coefficient of performance COP is generally low. While the efficiency decreases as the size decreases, the degree of superheat of the suction pipe of the compressor when the coefficient of performance COP is maximized, that is, when the efficiency is maximized, is as high as, for example, about 8 ° C., and the operating capacity is reduced. Therefore, for example, in the cooling operation, when the room temperature is higher than the set temperature and the temperature difference between the room temperature and the set temperature is larger than the upper threshold, the control device includes:
By controlling the degree of opening of the electric expansion valve, the number of rotations of the indoor fan, the operating frequency of the compressor, and the like, the degree of superheat of the suction pipe of the compressor is controlled so that the operating capacity is maximized. Then, by operating at the maximum capacity, the room temperature gradually decreases, and when the temperature difference between the room temperature and the set temperature falls within the range of the upper threshold value and the lower threshold value, the control device In accordance with the difference, the suction pipe superheat degree is controlled from the suction pipe superheat degree when the operating capacity is maximized to the suction pipe superheat degree when the coefficient of performance COP is maximized. Thereafter, when the temperature difference between the room temperature and the set temperature is smaller than the lower threshold,
The control device controls the degree of superheat of the suction pipe of the compressor so that the coefficient of performance COP becomes maximum, and operates at the maximum efficiency.
In this way, since the degree of superheat of the suction pipe of the compressor is effectively controlled in accordance with the temperature difference between the indoor temperature and the set temperature, the indoor temperature is reliably adjusted to the set temperature, and the room is cooled too much in the cooling operation. The number of stoppages of the compressor is reduced, and the number of stoppages of the compressor is reduced without being excessively heated in the heating operation. Therefore, the reliability can be improved by reducing the number of start and stop of the compressor, and when the temperature difference between the room temperature and the set temperature is within the range of the upper threshold value and the lower threshold value, it is higher than at the maximum capacity. Power consumption can be reduced by effectively controlling the coefficient of performance COP, that is, the efficiency, while reducing the driving capacity.

[0007] The air conditioner according to the second aspect of the present invention is the first aspect of the invention.
In the air conditioner, the control device is configured such that, when the temperature difference is within the range from the upper threshold to the lower threshold, the degree of superheat of the suction pipe of the compressor is substantially inversely proportional to the temperature difference. It is characterized in that the degree of superheat of the suction pipe is controlled.

According to the air conditioner of the second aspect, the temperature difference is the lower threshold and the coefficient of performance COP is based on the degree of superheat of the suction pipe when the operating capacity is maximized at the upper threshold.
When the superheat degree of the suction pipe of the compressor is substantially inversely proportional to the temperature difference, that is, up to the suction pipe superheat degree at the time of maximizing If the temperature difference is small on the lower threshold side while the capacity is increased and the coefficient of performance COP is reduced, a large operating capacity is not required, so that the operating capacity is reduced and the coefficient of performance COP is increased. Next, the degree of superheat of the suction pipe of the compressor is controlled. Therefore, the target suction pipe superheat degree can be easily determined according to the temperature difference, and the suction pipe superheat degree can be accurately controlled.

[0009] The air conditioner according to the third aspect is characterized by the first aspect.
In the air conditioner of the second aspect, the control device controls a discharge pipe temperature corresponding to a suction pipe superheat degree of the compressor.

According to the air conditioner of the third aspect, since the discharge pipe temperature corresponds to the suction pipe superheat degree, the discharge pipe temperature can be easily converted based on the target suction pipe superheat degree. It is. Therefore, without providing a sensor for detecting the degree of superheat of the suction pipe of the compressor, using a sensor for detecting the temperature of the discharge pipe provided for protection of the refrigerant circuit,
The superheat degree of the suction pipe can be controlled, and the cost can be reduced.

[0011] The air conditioner of claim 4 is characterized in that
Or, in the air conditioner of 2, the indoor temperature sensor for detecting the indoor temperature, and a discharge pipe temperature sensor for detecting the discharge pipe temperature of the compressor, the control device is detected by the indoor temperature sensor A temperature difference calculating section for calculating a temperature difference between the room temperature and the set temperature, and a target suction pipe superheat degree calculation for calculating a target suction pipe superheat degree based on the temperature difference calculated by the temperature difference calculation section. A target discharge pipe temperature calculating section for calculating a target discharge pipe temperature based on the target suction pipe superheat degree calculated by the target suction pipe superheat degree calculation section; and a discharge detected by the discharge pipe temperature sensor. An electric expansion valve control unit that controls an opening degree of the electric expansion valve so that the pipe temperature becomes the target discharge pipe temperature calculated by the target discharge pipe temperature calculation unit.

According to the air conditioner of the fourth aspect, the temperature difference calculating section calculates the temperature difference between the room temperature detected by the room temperature sensor and the set temperature. Based on the temperature difference, the target suction pipe superheat degree calculation unit calculates the target suction pipe superheat degree. That is, when the temperature difference is larger than the upper threshold value, the target suction pipe superheat degree at which the operating capacity is maximized is determined, while when the temperature difference is smaller than the lower threshold value, the coefficient of performance COP is maximized. When the target suction pipe superheat degree is obtained, and when the temperature difference is within the range from the upper threshold value to the lower threshold value, the suction pipe at the time when the operating capacity is maximized according to the temperature difference is obtained. The target suction pipe superheat degree is obtained from the degree of superheat to the suction pipe superheat degree at which the coefficient of performance COP is maximized. Next, the target discharge pipe temperature is calculated by the target discharge pipe temperature calculation section based on the target suction pipe superheat degree calculated by the target suction pipe superheat degree calculation section. The discharge pipe temperature of the compressor corresponds to the suction pipe superheat degree, and the discharge pipe temperature can be easily converted based on the suction pipe superheat degree. Therefore, the discharge pipe temperature sensor also serves as a sensor for detecting the suction pipe superheat degree. Then, the opening of the electric expansion valve is controlled by the electric expansion valve control unit such that the discharge pipe temperature detected by the discharge pipe temperature sensor becomes the target discharge pipe temperature. Thus, by controlling the opening degree of the electric expansion valve so that the discharge pipe temperature becomes the target discharge pipe temperature and the suction pipe superheat degree becomes the target suction pipe superheat degree, stable operation with good controllability can be performed. Efficient operation is possible without requiring energy other than opening and closing of the electric expansion valve.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an air conditioner according to the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 1 is a circuit diagram of an air conditioner according to an embodiment of the present invention, wherein 1 is a compressor, 2 is a four-way valve connected to the discharge side of the compressor 1, and 3 is the four-way valve. An outdoor heat exchanger having one end connected to the valve 2, 4 is an electric expansion valve having one end connected to the other end of the outdoor heat exchanger 3, and 5 is an electric expansion valve 4.
Is an indoor heat exchanger having one end connected to the other end, and 6 is an accumulator connected to the other end of the indoor heat exchanger 5 via the four-way valve 2. The air conditioner also includes an indoor temperature sensor 21 that detects an intake temperature, that is, an indoor temperature Ta, near the indoor heat exchanger 5, a discharge pipe temperature sensor 22 that detects a discharge pipe temperature of the compressor 1, Indoor temperature sensor 2
1 and a control device 10 that receives the output from the discharge pipe temperature sensor 22 and controls the compressor 1, the electric expansion valve 4, and the like.

The control device 10 comprises a microcomputer, an input / output circuit, and the like. A temperature difference between the room temperature Ta detected by the room temperature sensor 21 and a set temperature Ts set by a remote controller (not shown) or the like. A temperature difference calculating section 11 for calculating ΔT, a target suction pipe superheating degree calculating section 12 for calculating a target suction pipe superheating degree SH based on the temperature difference ΔT calculated by the temperature difference calculating section 11, A target discharge pipe temperature calculator 13 for calculating a target discharge pipe temperature Tk based on the target suction pipe superheat degree SH calculated by the target suction pipe superheat degree calculator 12, and a target discharge pipe temperature calculator 13
And a motor-operated expansion valve controller 14 that controls the opening of the motor-operated expansion valve 4 so that the target discharge pipe temperature Tk is calculated.

In the air conditioner having the above configuration, for example,
When performing the cooling operation, when the four-way valve 2 is switched to the switching position indicated by the solid line and the compressor 1 is started, the refrigerant discharged from the compressor 1 is supplied to the outdoor heat exchanger 3 as a condenser and the electric expansion valve 4. Circulate in the order of the indoor heat exchanger 5 as an evaporator and the accumulator 6. Then, after the refrigerant is condensed in the outdoor heat exchanger 3, the refrigerant decompressed by the electric expansion valve 4 evaporates in the indoor heat exchanger 5 to cool the room.

In the air conditioner, as shown in FIG. 2, a characteristic curve of the capacity (cooling / heating capacity) of the compressor 1 with respect to the degree of superheat of the suction pipe and the coefficient of performance of the compressor 1 with respect to the degree of superheat of the suction pipe. Although it differs from the characteristic curve of the COP and varies depending on the configuration of the air conditioner, etc., generally, the maximum point of the operating capacity is near the suction pipe superheat degree 0 ° C., whereas the maximum point of the coefficient of performance COP, that is, the maximum point The point of efficiency is around the suction pipe superheat degree of 8 ° C. Therefore, in the air conditioner, in the cooling operation, when the indoor temperature Ta is higher than the set temperature Ts and the temperature difference between the indoor temperature Ta and the set temperature Ts exceeds the upper threshold, the suction pipe The opening degree of the electric expansion valve 4 is controlled so that the degree of superheat becomes 0 ° C.
On the other hand, when the room temperature Ta is higher than the set temperature Ts and the temperature difference between the room temperature Ta and the set temperature Ts is less than the lower threshold, the electric motor is controlled so that the suction pipe superheat degree becomes 8 ° C. The opening degree of the expansion valve 4 is controlled. Then, the room temperature Ta
Is higher than the set temperature Ts, and if the temperature difference between the room temperature Ta and the set temperature Ts is within the range from the upper threshold to the lower threshold, the suction between 0 ° C. and 8 ° C. The opening of the electric expansion valve 4 is controlled so that the degree of superheating of the pipe is substantially inversely proportional to the temperature difference.

FIG. 3 is a flowchart illustrating the operation of the control device 10 during the cooling operation of the air conditioner.

Hereinafter, a process for controlling the operation capability and the coefficient of performance COP of the control device 10 will be described with reference to FIG.

First, when the process starts, step S
In step 1, the indoor temperature sensor 21 is
Is calculated, the temperature difference ΔT (= Ta−Ts) between the room temperature Ta detected by the above and the set temperature Ts is calculated.

Next, the process proceeds to step S2, and step S1
The target suction pipe superheat degree calculating section 12 calculates the target suction pipe superheat degree SH based on the temperature difference ΔT calculated in the above. That is, when the temperature difference ΔT is larger than the upper threshold value, the target suction pipe superheat degree SH is set to 0 ° C. at which the operation capacity is maximized.
When the temperature difference ΔT is smaller than the lower threshold value, the target suction pipe superheat degree SH is set to 8 ° C. at which the coefficient of performance COP is maximized, and the temperature difference ΔT is increased from the upper threshold value. Within the range up to the lower threshold value, the target suction pipe superheat degree SH that is substantially inversely proportional to the temperature difference ΔT between 0 ° C. and 8 ° C. is calculated.

Next, the process proceeds to step S3, and step S2
The target discharge pipe temperature calculating section 13 calculates the target discharge pipe temperature Tk on the basis of the target suction pipe superheat degree SH calculated in (1). The target discharge pipe temperature Tk is obtained using the following equation.

Tk = T2 (SH = 2) + f (SH) (1) SH: target suction pipe superheat degree T2 (SH = 2): discharge pipe temperature f when SH reaches 2 ° C. SH): SH function Note that T2 (SH = 2) is calculated in advance according to the performance of the air conditioner and the like, and the function f (SH) is determined according to the performance of the air conditioner and the like.

Next, the process proceeds to step S4, and the process proceeds to step S3.
Based on the target discharge pipe temperature Tk calculated in the above, the opening degree of the electric expansion valve 4 is controlled by PID (proportional / integral / derivative) by the electric expansion valve control unit 14 so that the discharge pipe temperature becomes the target discharge pipe temperature Tk. After that, the process ends.

Hereinafter, this process is repeated during the cooling operation.

FIG. 4 shows the temperature difference ΔT when the upper threshold value is set to 10 ° C. and the lower threshold value is set to 1 ° C. and the target suction pipe superheat degree SH.
The relationship is shown. In FIG. 4, the temperature difference ΔT
Is lower than 1 ° C., the target suction pipe superheat SH is set to 8 ° C.
The target suction pipe superheat SH changes linearly from 8 ° C. to 0 ° C. from 1 ° C. to 10 ° C., and the temperature difference ΔT
Is higher than 1 ° C., the target suction pipe superheat SH is set to 0 ° C.
And Further, the above-described processing of the control device 10 describes the case of the cooling operation in which the room temperature Ta is higher than the set temperature Ts. However, in the case of the heating operation in which the room temperature Ta is lower than the set temperature Ts, the temperature difference The temperature difference ΔT = Ts−Ta is used instead of ΔT = Ta−Ts.

As described above, in the above air conditioner, the compressor 1 is operated in accordance with the temperature difference ΔT between the room temperature Ta and the set temperature Ts.
5, the indoor temperature is surely adjusted to the set temperature Ts, as shown by the dotted line in FIG. 5, to stop the operation due to excessive cooling in the cooling operation or excessive heating in the heating operation. The number of times is reduced, and the number of times the compressor 1 is stopped is reduced. Therefore, the reliability can be improved by reducing the number of times the compressor 1 starts and stops. When the temperature difference ΔT is within the range between the upper threshold value and the lower threshold value,
Coefficient of performance CO while lowering driving capacity than at maximum capacity
Effective control is performed so that P, that is, efficiency is increased, and power consumption can be reduced.

When the temperature difference ΔT is within the range from the upper threshold value to the lower threshold value, the suction pipe superheat degree is set so as to become the target suction pipe superheat degree SH which is substantially inversely proportional to the temperature difference ΔT. The target suction pipe superheat degree SH is controlled according to the temperature difference ΔT.
Can be easily determined, and the degree of superheat of the suction pipe can be accurately controlled.

The discharge pipe temperature detected by the discharge pipe temperature sensor 22 corresponds to the suction pipe superheat degree, and the target discharge pipe temperature Tk can be easily converted based on the target suction pipe superheat degree SH according to the following equation (1). can do. Accordingly, without providing a sensor for detecting the degree of superheat of the suction pipe of the compressor 1, the discharge pipe temperature sensor 2 provided for protecting the refrigerant circuit is provided.
By controlling the discharge pipe temperature by using 2, the degree of superheat of the suction pipe can be controlled, and the cost can be reduced.

Further, the electric expansion valve is controlled so that the discharge pipe temperature detected by the discharge pipe temperature sensor 22 becomes the target discharge pipe temperature Tk, that is, the suction pipe superheat degree becomes the target suction pipe superheat degree SH. The electric expansion valve 4 is controlled by the controller 14.
, The stable operation with good controllability can be achieved. In addition, compared to the number of rotations of the indoor fan, the operating frequency of the compressor, and the like, energy other than opening and closing of the electric expansion valve 4 is required for controlling the degree of superheat of the suction pipe, and efficient operation can be performed.

In the above embodiment, the air conditioner performing the cooling / heating operation has been described. However, the present invention may be applied to an air conditioner performing either the cooling operation or the heating operation.

In the above embodiment, the room temperature Ta
When the temperature difference ΔT between the temperature and the set temperature Ts is within the range from the upper threshold value to the lower threshold value, the target suction pipe superheat degree SH that is substantially inversely proportional to the temperature difference ΔT is calculated. The method of calculating the degree is not limited to this, and the target suction pipe superheat degree may be calculated using a table or the like.

Further, in the above embodiment, the target discharge pipe temperature Tk corresponding to the target suction pipe superheat degree SH is obtained by using the equation (1). However, the target discharge pipe temperature is obtained by using other conversion formulas and tables. Of course, you may ask.

In the above embodiment, the electric expansion valve 4
By controlling the opening degree of the compressor, the discharge pipe temperature corresponding to the suction pipe superheat degree of the compressor 1 was controlled, but by controlling the rotation speed of the indoor fan, the operating frequency of the compressor, and the like,
The superheat degree of the suction pipe of the compressor may be controlled.

In the above embodiment, the opening of the electric expansion valve 4 is controlled so that the discharge pipe temperature detected by the discharge pipe temperature sensor 22 becomes the target discharge pipe temperature.
A sensor for detecting the degree of superheat of the suction pipe may be provided, and the degree of opening of the electric expansion valve may be controlled so that the degree of superheat of the suction pipe detected by the sensor becomes the target degree of superheat of the suction pipe.

In the above-described embodiment, the compressor 1 may have an operation frequency changed by inverter control, or may operate the compressor at a constant operation frequency.

[0037]

As is clear from the above, the air conditioner according to the first aspect of the present invention is an air conditioner having a refrigerant circuit in which a compressor, a condenser, an electric expansion valve, and an evaporator are connected in a ring. When the temperature difference between the room temperature and the set temperature is larger than the upper threshold, the control device controls the degree of superheat of the suction pipe of the compressor so that the operating capacity is maximized, while the temperature difference is lower. When it is smaller than the value, while controlling the degree of superheat of the suction pipe of the compressor so that the coefficient of performance COP becomes maximum,
When the temperature difference is within the range from the upper threshold to the lower threshold, the suction pipe superheat degree when the operating capacity is maximized and the suction when the coefficient of performance COP is maximized are determined according to the temperature difference. The superheat degree of the suction pipe of the compressor is controlled until the pipe superheat degree.

Therefore, according to the air conditioner of the first aspect of the present invention, the degree of superheat of the suction pipe of the compressor is effectively controlled in accordance with the temperature difference between the indoor temperature and the set temperature, so that the indoor temperature is reduced. The temperature is reliably adjusted to the set temperature, so that the cooling operation does not cause excessive cooling and the heating operation does not cause excessive heating, and the number of times of operation stop due to thermo-off is reduced, thereby reducing the number of times the compressor is stopped. Therefore, the reliability can be improved by reducing the number of times of starting and stopping of the compressor. Further, in the range where the temperature difference is smaller than the upper threshold, the power consumption can be reduced by restricting the operation capacity according to the temperature difference and operating efficiently.

According to a second aspect of the present invention, in the air conditioner of the first aspect, the control device is arranged such that the temperature difference is within a range from the upper threshold value to the lower threshold value. At this time, the superheat degree of the suction pipe of the compressor is controlled so as to be substantially inversely proportional to the temperature difference.

Therefore, according to the air conditioner of the present invention, the target superheat degree of the suction pipe can be easily determined according to the temperature difference, and the superheat degree of the suction pipe can be accurately controlled.

According to a third aspect of the present invention, in the air conditioner of the first or second aspect, the control device controls a discharge pipe temperature corresponding to a suction pipe superheat degree of the compressor. It is.

Therefore, according to the air conditioner of the present invention, since the discharge pipe temperature can be easily converted based on the target suction pipe superheat degree, a sensor for detecting the suction pipe superheat degree can be provided. It is possible to control the degree of superheat of the suction pipe by using a sensor for detecting the temperature of the discharge pipe provided for protecting the refrigerant circuit without using the same, thereby reducing the cost.

The air conditioner according to a fourth aspect of the present invention is the air conditioner according to the first or second aspect, wherein an indoor temperature sensor for detecting the indoor temperature and a discharge pipe for detecting a discharge pipe temperature of the compressor. A temperature sensor, wherein a temperature difference between the indoor temperature detected by the indoor temperature sensor and the set temperature is calculated by a temperature difference calculation unit of the control device, and the temperature difference calculated by the temperature difference calculation unit is calculated. Based on the target suction pipe superheat degree calculation unit calculates the target suction pipe superheat degree,
Based on the target suction pipe superheat degree calculated by the target suction pipe superheat degree calculation section, the target discharge pipe temperature is calculated by the target discharge pipe temperature calculation section, and the discharge pipe temperature detected by the discharge pipe temperature sensor is calculated. The degree of opening of the electric expansion valve is controlled by the electric expansion valve controller so that the target discharge pipe temperature calculated by the target discharge pipe temperature calculator is obtained.

Therefore, according to the air conditioner of the present invention, the degree of superheat of the suction pipe is reduced by controlling the opening degree of the electric expansion valve so that the discharge pipe temperature becomes the target discharge pipe temperature. Since the degree of opening of the electric expansion valve is controlled so as to achieve the degree of superheat, stable operation with good controllability can be performed, and energy efficient operation other than opening and closing of the electric expansion valve can be performed, and efficient operation can be performed. .

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an operating capacity and a coefficient of performance COP with respect to a degree of superheat of a suction pipe of a compressor in the air conditioner.

FIG. 3 is a flowchart illustrating an operation of the control device of the air conditioner.

FIG. 4 is a diagram showing a relationship between a temperature difference of the air conditioner and a target suction pipe superheat degree.

FIG. 5 is a view showing repetition of operation / stop of a compressor of a conventional air conditioner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Four-way valve, 3 ... Outdoor heat exchanger, 4 ... Electric expansion valve, 5 ... Indoor heat exchanger, 6 ... Accumulator, 10
... Control device, 11 ... Temperature difference calculator, 12 ... Target suction pipe superheat degree calculator, 13 ... Target discharge pipe temperature calculator, 14 ... Electric expansion valve controller, 21 ... Room temperature sensor, 22 ... Discharge pipe temperature sensor .

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Masaki Yamamoto 1304 Kanaokacho, Sakai City, Osaka Daikin Industries Inside the Kanaoka Plant of Sakai Seisakusho Co., Ltd. (72) Inventor Seiki Inoue 1304 Kanaokacho Sakai City, Osaka Daikin Industries, Ltd. Inside the Sakai Plant Kanaoka Plant (72) Inventor Hajime Kurata 1304 Kanaokacho, Sakai City, Osaka Daikin Industries, Ltd. Inside the Sakai Plant Kanaoka Plant (72) Inventor Hideki Matsumoto 1304 Kanaokacho, Sakai City, Osaka Daikin Industries, Ltd. Kanaoka factory

Claims (4)

[Claims] In an air conditioner having a refrigerant circuit in which a compressor (1), a condenser, an electric expansion valve (4), and an evaporator are connected in a ring shape, a temperature difference between an indoor temperature and a set temperature increases. When the temperature is larger than the threshold value, the degree of superheat of the suction pipe of the compressor (1) is controlled so that the operating capacity is maximized. On the other hand, when the temperature difference is smaller than the lower threshold value, the coefficient of performance (COP) is reduced. While controlling the degree of superheat of the suction pipe of the compressor (1) so as to be maximum, when the temperature difference is within the range from the upper threshold to the lower threshold, according to the temperature difference, A control device (10) for controlling the suction pipe superheat degree of the compressor (1) from the suction pipe superheat degree when the operating capacity is maximized to the suction pipe superheat degree when the coefficient of performance (COP) is maximized. An air conditioner comprising: 2. The air conditioner according to claim 1, wherein the controller (10) is configured to control the compressor (10) when the temperature difference is within a range from the upper threshold value to the lower threshold value. 1)
An air conditioner wherein the degree of superheat of the suction pipe is controlled so as to be substantially inversely proportional to the temperature difference. 3. The air conditioner according to claim 1, wherein the control device (10) controls a discharge pipe temperature corresponding to a suction pipe superheat degree of the compressor (1). Air conditioner. 4. The air conditioner according to claim 1, wherein an indoor temperature sensor for detecting the indoor temperature, and a discharge pipe temperature sensor for detecting a discharge pipe temperature of the compressor. 22), the control device (10) includes a temperature difference calculation unit (11) that calculates a temperature difference between the room temperature detected by the room temperature sensor (21) and the set temperature.
A target suction pipe superheat degree calculation unit (12) that calculates a target suction pipe superheat degree based on the temperature difference calculated by the temperature difference calculation unit (11); and a target suction pipe superheat degree calculation unit ( Based on the target suction pipe superheat degree calculated by (12), a target discharge pipe temperature calculating unit (13) for calculating a target discharge pipe temperature, and a discharge pipe temperature detected by the discharge pipe temperature sensor (22). An electric expansion valve control unit (14) for controlling an opening degree of the electric expansion valve (4) so as to reach the target discharge pipe temperature calculated by the target discharge pipe temperature calculation unit (13). And air conditioner.