JPH09264616A - Controller for refrigeration cycle of air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a compressor in service life, in a refrigeration cycle in which the amount of throttling is controlled by a motor-operated expansion valve, by a method wherein, when the degree of superheat is within a specified range including a target value and, having lasted a specified time, this condition is in a stabilized state, the opening of the motor-operated expansion valve is altered by a prescribed degree. SOLUTION: Refrigerant is in part made to flow into a bypass 9 and led into a suction port of a compressor 1, while a temperature sensor 16 detects the temperature of the refrigerant flowing though the low-pressure side of the bypass 9 and a temperature sensor 15 detects the temperature of the refrigerant sucked into the compressor 1. The difference in detected temperature between the temperature sensors 15, 16 is obtained as a degree of superheat of refrigerant. From this degree of superheat of refrigerant and the degree of superheat obtained the last time a change in degree of superheat is quantitatively determined and from the deviation of the present degree of superheat from the target value the amount by which the opening of the motor-operated expansion valve 4 needs to be accommodated is obtained. In this constitution, when the degree of superheat is on the smaller (larger) side in a specified range including the target value and after this condition has lasted for a specific period of time, the opening of the motor-operated expansion valve 4 is controlled in a manner of being closed (opened) by a specified degree.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle control device for an air conditioner, which controls the degree of superheat of refrigerant by an electric expansion valve.

[0002]

2. Description of the Related Art In an air conditioner, the capacity (operating frequency) of a compressor is controlled according to a cooling load or a heating load.
At the same time, the superheat degree SH of the refrigerant is detected, and the throttle amount of the refrigeration cycle (that is, the refrigerant flow rate) is controlled by the electric expansion valve so that the detected superheat degree SH reaches a predetermined target value SHO.

In controlling the superheat degree SH, in consideration of the fact that there is a variation error (maximum ± 2 ° C.) for each component in the detection accuracy of the temperature sensor used for detecting the superheat degree, the superheat degree is actually taken into consideration.
If SH falls within the specified range including the target value SHO, it is acceptable. We do not dare to change the target value.

[0004]

When the degree of superheat SH stabilizes, for example, on the smaller side of the predetermined range, the electric expansion valve is operated in a direction in which it is opened more than the optimum state, and therefore the compressor is opened. The liquid refrigerant is sucked into the so-called liquid returning cycle, which adversely affects the life of the compressor.

When the degree of superheat SH stabilizes on the side of a large predetermined range, the opening of the electric expansion valve is operated in a direction closer than the optimum state, resulting in a so-called over-throttle cycle, and the compressor overheats. It may adversely affect its life.
It is not preferable in terms of operation efficiency.

[0006] The present invention has been made in view of the above circumstances,
The refrigeration cycle control device for an air conditioner of the first aspect of the invention, when the superheat degree SH stabilizes within a predetermined range including the target value SHO, brings the superheat degree SH closer to the target value SHO and returns the liquid or throttles too much. It is an object of the present invention to form a cycle in an optimum state that does not have a crack, and thereby to improve the life of the compressor.

In the refrigeration cycle control device for an air conditioner of the second invention, when the superheat degree SH stabilizes within a predetermined range including the target value SHO, the superheat degree SH is brought closer to the target value SHO and the liquid returns. It is an object of the present invention to form a cycle in an optimum state that does not have a crack, and thereby to improve the life of the compressor.

In the refrigeration cycle control device for an air conditioner of the third invention, when the superheat degree SH stabilizes within a predetermined width range including the target value SHO, the superheat degree SH is brought closer to the target value SHO and is excessively throttled. It is an object of the present invention to be able to form a cycle in an optimum state without any damage, thereby improving the life of the compressor, and obtaining good operation efficiency and energy saving effect.

In the refrigeration cycle control device for an air conditioner of the fourth invention, in addition to the object of the first invention, even if the superheat degree SH instantly deviates from a stable state within a predetermined range, it does not matter. The purpose is to be able to form a cycle in an optimal state without any

In addition to the object of the fourth aspect of the invention, the refrigeration cycle control device for an air conditioner of the fifth aspect of the invention can reduce the number of detections of the superheat degree SH and improve the life of the temperature sensor for detecting the superheat degree. The purpose is to achieve simplification of control.

In addition to the object of the first invention, the refrigeration cycle control device for an air conditioner of the sixth invention can reduce the number of times of opening operation of the electric expansion valve and can improve the stability of the refrigeration cycle. The purpose is to

The refrigeration cycle controller for an air conditioner according to the seventh aspect of the present invention can quickly bring the superheat degree SH close to the target value SHO to form a cycle in an optimum state without liquid return or excessive throttling. The purpose of this is to improve the life of the compressor.

The refrigeration cycle control device for an air conditioner according to the eighth aspect of the present invention is the object of the seventh aspect of the invention, in addition to the superheat degree SH being a target value.
The purpose is to increase the certainty of the control to quickly approach the SHO.

A refrigeration cycle controller for an air conditioner according to a ninth aspect of the present invention is the object of the first aspect of the invention, in addition to the superheat degree SH being a target value.
The objective is to approach SHO without overshoot and obtain a stable cycle state without hunting.

The refrigeration cycle control device for an air conditioner of the tenth aspect of the invention is capable of forming a cycle in an optimal state without overthrowing, in addition to the object of the ninth aspect of the invention, thereby improving the life of the compressor. The object is to achieve good operation efficiency and energy saving effect. First
A refrigeration cycle control device for an air conditioner according to a first aspect of the present invention is
In addition to the object of the present invention, it is an object of the present invention to improve safety against abnormal conditions such as overheating of a compressor.

[0016]

A refrigeration cycle control device for an air conditioner according to a first aspect of the present invention is a stable state in which a superheat degree SH is within a predetermined range including a target value SHO and the state continues for a predetermined time t _1. In case of, the electric expansion valve is changed by a predetermined opening degree.

In the refrigeration cycle control device for an air conditioner of the second invention, the superheat degree SH is the target value SHO in the first invention.
When the stable state continues for a predetermined time t ₁ , the electric expansion valve is closed by a predetermined opening degree.

In the refrigeration cycle control device for an air conditioner of the third invention, in the first invention, the superheat degree SH is the target value SHO.
When the stable state continues for a predetermined time t ₁ , the electric expansion valve is opened by a predetermined opening degree.

In the refrigeration cycle controller for an air conditioner according to a fourth aspect of the present invention, in the first aspect of the present invention, the means for determining that the stable state of the superheat degree SH has continued for a predetermined time t ₁ is the superheat degree.
The SH is judged at every predetermined time t ₂ (> t ₁ ) and it is judged that the result is stable and the result is obtained a predetermined number of times in succession.

In the refrigeration cycle controller for an air conditioner of the fifth aspect of the invention, in the fourth aspect of the invention, the predetermined time t ₂ is synchronized with the normal opening control cycle of the electric expansion valve. In the refrigeration cycle control device for an air conditioner of a sixth aspect of the present invention, in the first aspect of the present invention, the timing of operating the opening degree of the electric expansion valve is synchronized with the normal opening control cycle of the electric expansion valve.

A refrigeration cycle control device for an air conditioner according to a seventh aspect of the present invention comprises means for obtaining a difference between the superheat degree SH and a target value SHO, and when the absolute value of the obtained difference is equal to or larger than a predetermined value, electric expansion is performed. The cycle of normal valve opening control is shortened.

The refrigeration cycle control device for an air conditioner of the eighth invention is the air conditioner refrigeration cycle control apparatus according to the seventh invention, wherein the target value SH is changed from the superheat degree SH.
The predetermined value was made different depending on whether the value obtained by subtracting O 2 is positive or negative.

A refrigeration cycle control device for an air conditioner according to a ninth aspect of the invention is the same as the first aspect, except that the superheat degree SH and the target value SHO.
And a control means for prohibiting the opening operation of the electric expansion valve or reducing the opening operation amount when the absolute value of the difference calculated by the operation means is equal to or greater than a predetermined value. And equipped.

In the refrigeration cycle control device for an air conditioner of the tenth invention, in the ninth invention, when the superheat degree SH exceeds a preset value, the inhibition or reduction control by the control means is released. .

The refrigeration cycle control device for an air conditioner of the eleventh aspect of the present invention is, in the first aspect, provided with means for detecting the discharge refrigerant temperature Td of the compressor during the refrigeration cycle, and the detected discharge refrigerant temperature Td is When the temperature rises above the predetermined temperature, the opening degree of the electric expansion valve is replaced with the superheat degree SH and the target value SHO, instead of the discharge refrigerant temperature Td and the discharge refrigerant temperature Td.
Based on the target value Tdo for

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 2, the outdoor heat exchanger 3 is connected to the discharge port of the variable capacity compressor 1 via the four-way valve 2.
To the outdoor heat exchanger 3 via an electric expansion valve (pulse motor valve; PMV) 4 and a packed valve 5
Is connected to the piping.

An indoor heat exchanger 6 is connected to the packed valve 5 by piping, and a packed valve 7 is connected to the indoor heat exchanger 6. Then, the suction port of the compressor 1 is connected to the packed valve 7 through the four-way valve 2 and the accumulator 8 by piping.

These pipe connections constitute a heat pump type refrigeration cycle capable of cooling and heating. During cooling, the flow path of the four-way valve 2 is set to the cooling mode so that the refrigerant flows in the direction of the solid arrow to form a cooling cycle, and the outdoor heat exchanger 3 is the condenser and the indoor heat exchanger 6 is the evaporator. To function as.

During heating, the flow path of the four-way valve 2 is switched to the heating mode to flow the refrigerant in the direction of the broken line arrow to form a heating cycle, and the indoor heat exchanger 6 is used as the condenser and the outdoor heat exchanger 3 Function as an evaporator.

A bypass 9 is connected from the liquid side pipe between the outdoor heat exchanger 3 and the electric expansion valve 4 to the low pressure side pipe between the four-way valve 2 and the suction port of the compressor 1. The bypass tube 9 is provided with a capillary tube 10 as a diaphragm device.

An outdoor fan 11 is provided near the outdoor heat exchanger 3. The outdoor fan 11 circulates the outdoor air through the outdoor heat exchanger 3. The indoor fan 1 is installed near the indoor heat exchanger 6.
2 is provided. The indoor fan 12 circulates indoor air through the indoor heat exchanger 6.

The temperature sensor 13 is attached to the liquid side pipe near the outdoor heat exchanger 3. The temperature sensor 13 detects the temperature Te of the refrigerant flowing into the outdoor heat exchanger 3 during heating, and is used for detecting frost formation on the outdoor heat exchanger 3.

An indoor temperature sensor 14 for detecting an intake air temperature (hereinafter referred to as indoor temperature) Ta is provided in an air passage passing through the indoor heat exchanger 6. A temperature sensor 15 for detecting the suction refrigerant temperature Ts of the compressor 1 is attached to the low pressure side pipe between the four-way valve 2 and the suction port of the compressor 1.

In the bypass 6, a temperature sensor 16 is attached at a position downstream of the capillary tube 10.
The temperature sensor 16 measures the refrigerant temperature Tu on the low pressure side of the bypass 6.
To detect.

A temperature sensor 17 for detecting the discharge refrigerant temperature Td is attached to the high pressure side pipe between the discharge port of the compressor 1 and the four-way valve 2. Compressor 1 to packed valves 5 and 7
The outdoor unit A is mainly composed of the pipes and the equipments, and the indoor unit B is mainly composed of the pipings and the equipments closer to the indoor heat exchanger 6 than the packed valves 5 and 7.

The control circuit is shown in FIG. Commercial AC power supply 20
Is connected to the indoor control unit 30 of the indoor unit B, and the outdoor control unit 40 of the outdoor unit A is connected to the indoor control unit 30 via the power supply line 21 and the serial signal line 22.

The indoor control unit 30 includes an indoor fan motor 12
M, the indoor temperature sensor 14, and the light receiving 31 are connected.
The light receiving unit 31 receives infrared light emitted from the remote control type operation device 32. The operation device 32 transmits operating conditions input by a user's key operation to the air conditioner body by infrared light. The operation device 32 will be abbreviated as a remote controller hereinafter.

A four-way valve 2, an electric expansion valve 4, temperature sensors 13, 15, 16 and 17, an indoor fan motor 11M, and an inverter circuit 41 are connected to the outdoor control section 40. The inverter circuit 41 rectifies the power supply voltage, converts the power supply voltage into alternating current having a frequency (and voltage) according to a command from the outdoor control unit 40, and outputs the alternating current. This output is supplied to the compressor motor 1M as drive power.

The indoor control unit 30 and the outdoor control unit 40 are
The overall control of the air conditioner is performed while transferring data to each other via the serial signal line 22. The control functions include the following [1] to [3].

[1] The detected temperature Tu of the temperature sensor 16 is taken in as the pseudo saturation temperature of the refrigerant, and the temperature sensor 15 and the temperature sensor 15
Detecting means for detecting the superheat degree SH of the refrigerant in the evaporator from the detection temperature Ts of

[2] Opening degree control means for controlling the opening degree of the electric expansion valve 4 in a predetermined cycle so that the detected superheat degree SH becomes a target value SHO, for example, 5 deg. [3] Opening operation for closing the electric expansion valve 4 by a predetermined opening degree when the superheat degree SH is on the smaller side of the predetermined width range including the predetermined target value SHO and the stable state continues for the predetermined time t ₁ means.

Next, the operation will be described with reference to the flowchart of FIG. During the cooling operation, the refrigerant flows in the direction of the solid arrow in FIG. 2 so that the outdoor heat exchanger 3 functions as a condenser and the indoor heat exchanger 6 functions as an evaporator. This cools the room.

During the heating operation, the flow path of the four-way valve 2 is switched to flow the refrigerant in the direction of the broken arrow in FIG. 2 so that the indoor heat exchanger 6 functions as a condenser and the outdoor heat exchanger 3 functions as an evaporator. This heats the room.

During this cooling and heating operation, the remote controller 32
The set indoor temperature by T and the detected temperature T of the indoor temperature sensor 14
The difference from a is obtained as an air conditioning load, and the operating frequency (output frequency of the inverter circuit 41) F of the compressor 1 is controlled according to the air conditioning load. By this control, the indoor temperature is made to converge to the set indoor temperature.

During operation, a part of the refrigerant passing through the liquid side pipe of the refrigeration cycle flows into the bypass 9. The refrigerant that has flowed in passes through the capillary tube 10 and is guided to the suction port of the compressor 1. At this time, the low pressure side (downstream side) of the bypass 9
The temperature Tu of the refrigerant flowing through the temperature sensor 16 is detected by the temperature sensor 16, and the temperature Ts of the refrigerant sucked into the compressor 1 is detected by the temperature sensor 15. Detection temperature T of the temperature sensor 16
u corresponds to the pseudo saturation temperature.

During operation, the following control is executed at predetermined control intervals. The difference (= Ts-Tu) between the temperature Ts detected by the temperature sensor 15 and the temperature Tu detected by the temperature sensor 16 is calculated as the superheat degree SH of the refrigerant (step 101). The calculated superheat degree SH is stored in the internal memory of the outdoor control unit 40.

The previously obtained superheat degree SH in the internal memory is subtracted from the currently obtained superheat degree SH to obtain the superheat degree change amount ΔSH (= this superheat degree SH-previous superheat degree SH) (step 102).
The deviation (= SH-SHO) between the current superheat degree SH and the target value SHO is calculated, and the deviation and the superheat degree change amount ΔSH are stored in the internal memory of the outdoor control unit 40. The degree of opening operation required (the number of drive pulses) P with respect to the current opening of the electric expansion valve 4
Find n (step 103).

When the required amount Pn for operating the opening is not zero (NO in step 104), the opening of the electric expansion valve 4 is actually operated by the required amount Pn (step 110). By this opening operation, the superheat degree SH changes toward the target value SHO.

When the required amount Pn of the opening degree operation is zero (YES in step 104), the superheat degree change amount ΔSH is zero and the superheat degree is
It is determined whether the deviation between SH and the target value SHO (= SH-SHO) is -1deg or -2deg, that is, whether the superheat degree SH is stable on the smaller side of the predetermined range including the target value SHO (step 105). ).

If the degree of superheat SH is stable on the smaller side of the predetermined range including the target value SHO (YES in step 105), the time count t is executed (step 106). When the superheat degree SH deviates from the predetermined range including the target value SHO (step 105
NO), the time count t is cleared (step 109).
).

The time count t is the predetermined time t _{1 while the} superheat degree SH remains stable on the small side of the predetermined range including the target value SHO.
(YES at step 107), the required amount Pn for opening operation is corrected in the decreasing direction by a predetermined amount P _1, for example, one pulse (step 108).

Then, the time count t is cleared (step 109), and the opening degree of the electric expansion valve 4 is operated by the corrected necessary amount Pn (step 110). That is, the opening degree of the electric expansion valve 4 is closed.

When the degree of superheat SH is stable in a predetermined range, for example, on the small side, the opening degree of the electric expansion valve 4 is operated in a direction that opens more than the optimum state. It becomes a so-called liquid-returning cycle in which the compressor 1 is sucked in, which may adversely affect the life of the compressor 1.

Therefore, the degree of superheat SH is on the side of a small predetermined range including the target value SHO, and its stable state is the predetermined time t ₁
For example, when it continues for 300 seconds, the electric expansion valve 4 is closed by a predetermined opening degree as described above. As a result, the superheat degree SH becomes closer to the target value SHO, and it is possible to form a cycle in an optimum state in which there is no liquid return. The life of the compressor 1 can be improved.

In the above embodiment, the refrigerant temperature on the outlet side of the bypass 9 (the temperature detected by the temperature sensor 16) Tu is taken in as the pseudo saturation temperature of the refrigerant, and the intake refrigerant temperature (temperature detected by the temperature sensor 15) Ts is taken into consideration. Although the superheat degree SH is detected, the detected temperature Te of the temperature sensor 13 for detecting frost near the outdoor heat exchanger 3 is selected as the pseudo saturation temperature during heating, and the superheat degree SH is calculated from the detected temperature Te and the suction refrigerant temperature Ts. You may make it detect.

[First Modification] In the above embodiment, the superheat degree SH
Is on the side of a small predetermined range including the target value SHO, and the electric expansion valve 4 is closed by a predetermined opening when the stable state continues for a predetermined time t ₁ , but the superheat degree SH includes the target value SHO. Whether or not it is stable on the smaller side of the predetermined width for a predetermined time t ₂
For example, the electric expansion valve 4 may be closed by a predetermined opening degree when it is determined every 100 seconds and a stable determination result is obtained a predetermined number of times N, for example, three consecutive times.

In this case, even if the degree of superheat SH momentarily deviates from the side of the small predetermined width range, the opening degree operation in the closing direction with respect to the electric expansion valve 4 can be performed regardless of this.

Since the superheat degree SH may be detected every predetermined time t ₂ , the control can be simplified. [Second Modification] The following control is added.

When the superheat degree SH is on the large side of the predetermined width range including the target value SHO and the stable state continues for the predetermined time t ₁ , the electric expansion valve 4 is opened by the predetermined opening degree. In this case, the opening manipulated variable setting condition of FIG. 5 is used instead of FIG. 4, the superheat change amount ΔSH is zero, and the deviation (= SH−SHO) between the superheat SH and the target value SHO is +1 deg or + Whether 2deg,
The condition for determining whether or not the superheat degree SH is stable on the larger side of the specified width including the target value SHO is used.

When the degree of superheat SH stabilizes on the side of a large predetermined range, the opening degree of the electric expansion valve 4 is operated in a direction to close it from the optimum state, which is a so-called overthrottle cycle,
There is a concern that the compressor 1 may overheat and adversely affect its life. It is not preferable in terms of operation efficiency.

Therefore, the degree of superheat SH is on the side of the large predetermined width range including the target value SHO, and the stable state is for the predetermined time t ₁
When continuing, the electric expansion valve 4 is opened by a predetermined opening degree. As a result, the superheat degree SH becomes closer to the target value SHO, and it is possible to form a cycle in an optimal state in which there is no excessive throttling. As a result, the life of the compressor 1 can be improved, good operating efficiency can be obtained, and an energy saving effect can be obtained.

[Third Modification] In the second modification, the degree of superheat SH is on the side of a large predetermined range including the target value SHO,
When the stable state continues for a predetermined time t ₁ , the electric expansion valve 4 is opened by a predetermined opening degree, but whether the superheat degree SH is stable on the large side of a predetermined width range including the target value SHO a predetermined time t ₂ For example, the determination may be made every 100 seconds, and the electric expansion valve 4 may be opened by a predetermined opening degree when a stable determination result is obtained a predetermined number of times N, for example, three consecutive times.

In this case, even if the degree of superheat SH is instantaneously deviated from the side of the larger predetermined width range, the opening degree operation of the electric expansion valve 4 in the opening direction can be performed regardless.

Since the superheat degree SH may be detected every predetermined time t ₂ , the control can be simplified. [Fourth Modification] In the third modification, the predetermined time t ₂ is
The electric expansion valve 4 is synchronized with a normal opening control cycle.

That is, the number of detections of the superheat degree SH is reduced. The temperature sensor is energized when detecting the degree of superheat SH, and the life of the temperature sensor can be improved by reducing the number of detections and shortening the energization time. The control can be simplified.

[Fifth Modification] In the above-described embodiments and modifications, the timing of the opening operation of the electric expansion valve 4 is synchronized with the normal opening control cycle of the electric expansion valve 4.

Generally, the refrigeration cycle is often temporarily unstable after the opening degree of the electric expansion valve 4 is manipulated.
If possible, I want to minimize the number of operations. If the timing of the opening operation for the electric expansion valve 4 is synchronized with the normal opening control cycle of the electric expansion valve 4, the number of opening operations for the electric expansion valve 4 can be minimized and the refrigeration Cycle stability can be improved.

[Sixth Modification] The deviation (= SH-SHO) between the superheat degree SH and the target value SHO in the above-mentioned embodiment and each modification.
) Is greater than a predetermined value, for example 4deg, that is, the target value SHO is 5deg, so if the superheat degree SH ≥ 9deg or the superheat degree SH ≤ 1deg, the normal opening control cycle of the electric expansion valve 4, for example 60sec. To 20 seconds.

That is, it is possible to quickly bring the superheat degree SH close to the target value SHO to form a cycle in an optimum state without liquid return or excessive throttling. Thereby, the life of the compressor 1 can be improved.

[Seventh Modification] In the sixth modification, when the value obtained by subtracting the target value SHO from the superheat degree SH is positive (SH> SHO).
And when negative (SH <SHO), the specified value is made different.

That is, when the superheat degree SH is larger than the target value SHO (SH> SHO), 7 deg is selected as the predetermined value.
When the superheat degree SH is smaller than the target value SHO (SH <SHO), select 5deg as the predetermined value.

When the superheat degree SH is larger than the target value SHO and 7 deg is selected as the predetermined value, the opening control cycle is shortened when the superheat degree SH ≧ 12 deg. When the superheat degree SH is smaller than the target value SHO and 5 deg is selected as the predetermined value, the opening control cycle is shortened when the superheat degree SH ≤ 0 deg.

In this way, a plurality of types of predetermined values are used,
The certainty of the control to bring the superheat degree SH closer to the target value SHO is enhanced. [Eighth Modification] In the fifth modification, the opening operation timing for the electric expansion valve 4 is synchronized with the normal opening control cycle of the electric expansion valve 4, but the superheat degree SH and the target value SHO are changed. If the deviation is too large, the amount of opening operation may become excessive.

Therefore, when the absolute value of the deviation (= SH-SHO) between the superheat degree SH and the target value SHO is equal to or greater than a predetermined value, the opening operation for the electric expansion valve 4 is prohibited. Alternatively, the amount of opening operation is reduced.

As a result, the superheat degree SH approaches the target value SHO without overshoot, and a stable cycle state without hunting can be obtained. [Ninth Modification] In the eighth modification, the superheat degree SH and the target value SHO
If the absolute value of the deviation (= SH-SHO) is more than the specified value,
The opening operation for the electric expansion valve 4 is prohibited or the amount of opening operation is reduced.
If, for example, is larger than 20 deg, the refrigeration cycle is over-throttled and it is necessary to cancel that state early.

Therefore, when the superheat degree SH exceeds a preset value, the control for prohibiting the opening operation or the control for decreasing the opening operation amount is released. This allows
It is possible to form a cycle in an optimum state without over-squeezing. As a result, the life of the compressor 1 can be improved, good operating efficiency can be obtained, and an energy saving effect can be obtained.

[Tenth Modification] In the above embodiments and the respective embodiments, when the temperature Td detected by the temperature sensor 17 (discharge refrigerant temperature) rises above a predetermined temperature, the compressor 1
In order to prevent the overheating abnormality of the above, the opening degree control of the electric expansion valve 4 is executed based on the detected temperature Td and a predetermined target discharge refrigerant temperature Tdo instead of the superheat degree SH and the target value SHO.

That is, the previous detected temperature Td is subtracted from the present detected temperature Td to obtain the discharged refrigerant temperature change amount ΔTd. Deviation between the detected temperature Td this time and the target value Tdo (=
Td-Tdo), and the deviation and the calculated refrigerant discharge temperature variation ΔTd are applied to the opening manipulated variable setting condition of FIG. 6 stored in the internal memory of the outdoor control unit 40. , The required amount (driving pulse number) Pn of the opening degree operation with respect to the current opening degree of the electric expansion valve 4 is obtained.

Then, the opening degree of the electric expansion valve 4 is actually operated by the calculated required amount Pn. When the detected temperature Td of the temperature sensor 17 falls below a predetermined temperature, the normal control according to the superheat degree SH and the target value SHO is restored.

[0080]

As described above, in the refrigeration cycle control device for the air conditioner of the first invention, the superheat degree SH has the target value SHO.
When the electric expansion valve is changed by a predetermined opening degree when the state is in a stable state in which the state continues for a predetermined time t ₁ within a predetermined width range including, the superheat degree SH has a predetermined value including the target value SHO. When it stabilizes within the range, the superheat degree SH is set to the target value SHO
It is possible to form a cycle in an optimum state in which liquid return and over-throttlement are not possible by bringing the cycle closer to, and thereby improving the life of the compressor.

In the refrigeration cycle control device for an air conditioner of the second invention, when the superheat degree SH is on the side of a small predetermined range including the target value SHO and the stable state continues for a predetermined time t ₁ , Since the electric expansion valve is configured to close by a predetermined opening, when the superheat degree SH stabilizes within a predetermined range including the target value SHO, the superheat degree SH is brought closer to the target value SHO and there is no liquid return. Cycle can be formed, which can improve the life of the compressor.

In the refrigeration cycle controller for an air conditioner according to the third aspect of the present invention, when the superheat degree SH is on the side of a large predetermined range including the target value SHO and the stable state continues for a predetermined time t ₁ , Since the electric expansion valve is configured to open by a predetermined opening,
When the superheat degree SH stabilizes within a predetermined range including the target value SHO, the superheat degree SH can be brought closer to the target value SHO to form an optimal state cycle without over-throttlement. The life can be improved, good operating efficiency can be obtained, and an energy saving effect can be obtained.

In the refrigeration cycle control device for an air conditioner of the fourth invention, in the first invention, the means for determining that the stable state of the superheat degree SH has continued for a predetermined time t ₁ is the superheat degree.
Since SH is judged every predetermined time t ₂ (> t ₁ ) and the judgment result that it is stable is obtained a predetermined number of times in succession, the superheat degree SH is within a predetermined range. The objective is to be able to form the cycle of the optimum state regardless of the momentary deviation from the stable state of.

In the refrigeration cycle control device for an air conditioner of the fifth aspect of the invention, in the fourth aspect of the invention, the predetermined time t ₂ is synchronized with the cycle of the normal opening control of the electric expansion valve. The number of detections of the temperature SH can be reduced, the life of the temperature sensor for detecting the degree of superheat can be improved, and the control can be simplified.

In the refrigeration cycle control device for an air conditioner of the sixth invention, in the first invention, the timing of the opening operation to the electric expansion valve is synchronized with the normal opening control cycle of the electric expansion valve. Therefore, the number of times the opening degree of the electric expansion valve is manipulated can be reduced, and the stability of the refrigeration cycle can be improved.

The refrigeration cycle control device for an air conditioner according to the seventh aspect of the invention is provided with means for obtaining the difference between the superheat degree SH and the target value SHO, and when the absolute value of the obtained difference is equal to or greater than a predetermined value, electric expansion is performed. Since it is configured to shorten the cycle of the normal valve opening control, it is possible to quickly bring the superheat degree SH close to the target value SHO and form an optimal state cycle without liquid return or excessive throttling. The life of the compressor can be improved.

An air conditioner refrigeration cycle controller according to an eighth aspect of the present invention is the air conditioner according to the seventh aspect, wherein the superheat degree SH is changed to a target value SH.
Since the specified value is made different depending on whether the value obtained by subtracting O is positive or negative, the superheat degree SH is set to the target value SHO.
The certainty of the control for promptly approaching is increased.

A refrigeration cycle controller for an air conditioner according to a ninth aspect of the invention is the superheat degree SH and the target value SHO in the first aspect of the invention.
And a control means for prohibiting the opening operation of the electric expansion valve or reducing the opening operation amount when the absolute value of the difference calculated by the operation means is equal to or greater than a predetermined value. And, with the addition of the superheat degree SH, the target value SHO
A stable cycle state without hunting can be obtained by approaching to without overshoot.

In the refrigeration cycle control device for an air conditioner of the tenth invention, in the ninth invention, when the superheat degree SH exceeds a preset value, the inhibition or reduction control by the control means is released. Since the configuration is adopted, it is possible to form a cycle in an optimal state without excessive throttling, whereby the life of the compressor can be improved, good operating efficiency can be obtained, and an energy saving effect can be obtained.

An air conditioner refrigeration cycle control device according to the eleventh aspect of the present invention is, in the first aspect, provided with means for detecting the discharge refrigerant temperature Td of the compressor during the refrigeration cycle, and the detected discharge refrigerant temperature Td is When the temperature rises above the predetermined temperature, the opening degree of the electric expansion valve is replaced with the superheat degree SH and the target value SHO, instead of the discharge refrigerant temperature Td and the discharge refrigerant temperature Td.
Since the control is performed on the basis of the target value Tdo for, the safety of the compressor against overheating abnormality can be further improved.

[Brief description of drawings]

FIG. 1 is a block diagram of a control circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a refrigeration cycle of the same embodiment.

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

FIG. 4 is a diagram showing a format of an opening manipulated variable setting condition in the embodiment.

FIG. 5 is a view showing a format of an opening manipulated variable setting condition in a modification of the embodiment.

FIG. 6 is a diagram showing a format of an opening manipulated variable setting condition in yet another modified example of the embodiment.

[Explanation of symbols]

 1 ... Variable capacity compressor 3 ... Outdoor heat exchanger 4 ... Electric expansion valve 6 ... Indoor heat exchanger 9 ... Bypass 14 ... Indoor temperature sensor 13, 15, 16, 17 ... Temperature sensor 30 ... Indoor control section 40 ... Outdoor control Part A ... Outdoor unit B ... Indoor unit

Claims (11)

[Claims] 1. In an air conditioner in which an electric expansion valve controls a throttle amount of a refrigeration cycle so that a superheat degree SH of a refrigerant reaches a target value SHO, the superheat degree SH falls within a predetermined range including the target value SHO. A refrigeration cycle control device for an air conditioner, wherein the electric expansion valve is changed by a predetermined opening degree when the state is a stable state in which the state continues for a predetermined time t ₁ . 2. The air conditioner according to claim 1, wherein when the superheat degree SH is on the side of a small predetermined range including the target value SHO and the stable state continues for a predetermined time t ₁ ,
A refrigeration cycle control device for an air conditioner, characterized in that the electric expansion valve is closed by a predetermined opening degree. 3. The air conditioner according to claim 1, wherein when the superheat degree SH is on the side of a large predetermined range including the target value SHO and the stable state continues for a predetermined time t ₁ ,
A refrigeration cycle control device for an air conditioner, wherein the electric expansion valve is opened by a predetermined opening degree. 4. The air conditioner according to claim 1, wherein the means for determining that the stable state of the superheat degree SH has continued for a predetermined time t ₁ is the superheat degree SH for a predetermined time t ₂ (> t ₁ ).
The refrigeration cycle control device for an air conditioner, wherein the refrigeration cycle control device is characterized in that the refrigeration cycle is determined for each time and is determined to be stable for a predetermined number of times continuously. 5. The refrigeration cycle control device for an air conditioner according to claim 4, wherein the predetermined time t ₂ is synchronized with a cycle of normal opening control of the electric expansion valve. 6. The air conditioner according to claim 1, wherein the timing of operating the opening of the electric expansion valve is synchronized with a normal opening control cycle of the electric expansion valve. Refrigeration cycle control device. 7. An air conditioner that controls the throttle amount of a refrigeration cycle by an electric expansion valve so that the superheat degree SH of the refrigerant becomes a target value SHO, and means for obtaining a difference between the superheat degree SH and the target value SHO. A refrigeration cycle control device for an air conditioner, characterized in that the cycle of the normal opening control of the electric expansion valve is shortened when the absolute value of the obtained difference is equal to or greater than a predetermined value. 8. The air conditioner according to claim 7, wherein the predetermined value is different depending on whether the value obtained by subtracting the target value SHO from the superheat degree SH is positive or negative. Refrigeration cycle control device for air conditioner. 9. The air conditioner according to claim 1, wherein a calculation means for calculating a difference between the superheat degree SH and the target value SHO and an absolute value of the difference calculated by the calculation means is a predetermined value or more. In this case, a refrigeration cycle control device for an air conditioner, comprising: a control unit that prohibits the opening operation of the electric expansion valve or reduces the amount of the opening operation. 10. The air conditioner according to claim 9,
A refrigeration cycle control device for an air conditioner, wherein when the superheat degree SH exceeds a preset value, the inhibition or reduction control by the control means is released. 11. The air conditioner according to claim 1,
A means for detecting the discharge refrigerant temperature Td of the compressor during the refrigeration cycle is provided, and when the detected discharge refrigerant temperature Td rises above a predetermined temperature, the opening degree of the electric expansion valve is set to the superheat degree SH.
And, instead of the target value SHO, the refrigerating cycle control device for an air conditioner is controlled based on a discharge refrigerant temperature Td and a target value Tdo for the discharge refrigerant temperature Td.