JPH0814698A - Operation control device for air-conditioner - Google Patents

Abstract

PURPOSE:To improve reliability and to reduce a cost by a method wherein the opening of an expansion valve is controlled based on a temperature difference between temperature on the outlet side of at least one of a condenser and a vaporizer and a saturation temperature corresponding to a pressure on the outlet side, and constitution of the system is simplified. CONSTITUTION:The degree of superheating is computed by a degree of superheat computing means 31 based on a saturation temperature corresponding to the pressure of a refrigerant in a suction pipe detected by an inlet pressure sensor 26 and the temperature of a refrigerant fed to the suction pipe of a compressor 11 from a vaporizer 13 and detected by a suction temperature sensor 21. A number of pulses change amount of an expansion valve 14 is computed by an expansion valve opening computing means 32 based on the computed degree of superheating, the target degree of superheating, and a number of revolutions of an engine. The expansion valve 14 is driven by a stepping motor of which a driven device consists based on a computing result to control a valve opening during ordinary operation. Since there is no need to control an air quantity of an outdoor fan as in a conventional device, constitution of a system is simplified and a cost is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for taking in outside air to perform air conditioning, and a saturation temperature corresponding to the temperature of the outlet side of at least one of the condenser and the evaporator and the pressure of the refrigerant on the outlet side. The present invention relates to an operation control device for an air conditioner that controls the opening degree of the expansion valve based on the degree of superheat or the degree of subcooling, which is the temperature difference between

[0002]

2. Description of the Related Art A conventional air conditioner operation control device (Japanese Patent Laid-Open No. 4-222341) uses an individual air conditioning system in which an indoor unit I is provided for each room H as shown in FIG. The outside air temperature detecting means S detects the outside air temperature and controls the air volume of the variable air volume type outdoor fan F of the outdoor unit O and the opening degree of the electric expansion valve V based on the outside air temperature.

[0003]

Since the above-mentioned operation control device for the air conditioner controls the air volume of the outdoor fan F and the opening degree of the electric expansion valve V based on the outside air temperature, the control logic, the controller, There was a problem that the actuator and the entire system became complicated.

Further, the above-mentioned conventional operation control device for the air conditioner has a complicated system as described above, which causes more troubles and requires the use of an expensive variable air volume type fan. There was a problem that the cost increased.

Therefore, the inventor of the present invention, in an air conditioner that takes in outside air to perform air conditioning, sets the temperature at the outlet side of at least one of the condenser and the evaporator and the saturation temperature corresponding to the pressure of the refrigerant at the outlet side. Focusing on the technical idea of the present invention of controlling the opening degree of the expansion valve based on the degree of superheat or the degree of supercooling which is a temperature difference, as a result of further research and development, the system configuration is simplified, and As a result, the present invention has been achieved which achieves the object of improving reliability and reducing cost.

[0006]

The operation control device of the air conditioner of the present invention (the first invention according to claim 1) comprises a compressor, a condenser, an evaporator and an expansion valve, and takes in outside air. In an air conditioner that performs air conditioning, based on the temperature difference between the temperature on the outlet side of at least one of the condenser and the evaporator and the saturation temperature corresponding to the pressure of the refrigerant on the outlet side, the opening of the expansion valve It is provided with a control device for controlling.

The operation control device for an air conditioner of the present invention (the second invention according to claim 2) is the air conditioner operation control device according to the first invention, wherein the control device is such that the temperature on the outlet side of the evaporator and the pressure on the outlet side are The degree of opening of the expansion valve is controlled based on the degree of superheat determined by the difference between the saturation temperature and the saturation temperature.

An operation control device for an air conditioner of the present invention (the third invention according to claim 3) is the same as the first invention.
The control device controls the opening degree of the expansion valve based on the degree of supercooling determined by the difference between the temperature on the outlet side of the condenser and the saturation temperature corresponding to the pressure on the outlet side.

The operation control device for an air conditioner of the present invention (the fourth invention according to claim 4) is the same as the second invention,
A superheat degree calculating means for calculating a superheat degree based on a temperature on the outlet side of the evaporator and a pressure on the outlet side,
It comprises expansion valve opening degree calculation means for calculating the opening degree of the expansion valve based on the degree of superheat calculated by the degree of superheat calculation means, the target degree of superheat, and the engine speed.

The operation control device for an air conditioner of the present invention (the fifth invention according to claim 5) is the same as the fourth invention,
The control device sets a large control constant for a certain period of time after starting the compressor, and sets a small control constant after the certain period of time has elapsed.

An operation control device for an air conditioner of the present invention (sixth invention according to claim 6) is the same as the fifth invention.
The control device calculates the opening degree of the expansion valve based on the difference between the superheat degree and the target superheat degree and the temporal change of the superheat degree.

The operation control apparatus for an air conditioner of the present invention (the seventh invention according to claim 7) is the same as the sixth invention,
The control device calculates the opening degree of the expansion valve based on a temporal change in the engine speed.

[0013]

In the operation controller for the air conditioner according to the first aspect of the present invention, the controller responds to the temperature on the outlet side of at least one of the condenser and the evaporator and the pressure of the refrigerant on the outlet side. The opening degree of the expansion valve is controlled on the basis of the temperature difference from the saturation temperature, and outside air is taken in as necessary to perform air conditioning.

In the operation controller for the air conditioner of the second aspect of the present invention having the above-mentioned structure, the controller may control the temperature difference between the temperature on the outlet side of the evaporator and the saturation temperature corresponding to the pressure of the refrigerant on the outlet side. The opening degree of the expansion valve is controlled on the basis of the degree of superheat determined in (3), and outside air is taken in as necessary to perform air conditioning.

In the operation controller for the air conditioner of the fifth aspect of the present invention having the above structure, the controller sets the control constant to a large value for a certain time after the compressor is started, and quickly approaches the set superheat degree for the certain time. After the lapse of time, the control constant is set to a small value, and control is performed so as to stabilize the set superheat degree.

[0016]

The operation control device of the air conditioner according to the first or second aspect of the present invention, which has the above-described operation, only controls the opening of the expansion valve based on the temperature difference from the saturation temperature or the degree of superheat. Since the air volume of the outdoor fan is not controlled unlike the conventional case, the system configuration is simplified, and accordingly, the reliability is increased and the cost is reduced.

In the operation controller for the air conditioner according to the fifth aspect of the present invention, which has the above-described effect, the controller sets a large control constant for a certain period of time after the compressor is started, and quickly approaches the set superheat degree. It is possible to quickly bring the temperature close to the set temperature, and after the lapse of the fixed time, the control constant is set to a small value, and the control is performed so as to stabilize the set superheat, so that hunting of the superheat is suppressed. Produce an effect.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) As shown in FIGS. 1 to 4, the operation control device of the air conditioner of the first embodiment is a duct type air conditioner 1 for taking in outside air to perform air conditioning. 11, a condenser 12 that constitutes an outdoor heat exchanger, a refrigerant circuit 5 that constitutes a closed circuit in which an evaporator 13 that constitutes an indoor heat exchanger and an expansion valve 14 are disposed, and a temperature at the outlet side of the evaporator 13 A sensor 2 for detecting the pressure on the outlet side and the like; a superheat degree calculating means 31 for calculating a superheat degree based on the temperature on the outlet side of the evaporator 13 detected by the sensor 2 and the pressure on the outlet side; Control device 3 comprising expansion valve opening degree calculation means 32 for calculating the opening degree of the expansion valve 14 based on the degree of superheat calculated by the degree of superheat calculation means 31, the target degree of superheat, and the engine speed.
And a drive device 4 for driving and controlling the opening degree of the expansion valve 14 based on a control signal from the control device 3.

As shown in FIG. 2, the duct type air conditioner 1 has an indoor unit 17 controlled by an outdoor unit 16 by introducing outside air from an outside air inlet 15 formed on the outer wall of the building.
The temperature controllable air can be supplied to each room via the duct 18.

As shown in FIG. 3, the refrigerant circuit 5 includes a compressor 11 which is rotationally driven by an engine 10,
An oil collector 51 disposed in the discharge side pipe of the compressor 11 for collecting oil in the discharge refrigerant, and a pipe connected to the oil collector 51 and connecting the evaporator 13 and the condenser 12 to each other. The four-way switching valve 52 provided and the four-way switching valve 5
2, the condenser 12 which is connected to the outdoor unit and is arranged outdoors;
A receiver 53 which communicates with the condenser 12 and stores a liquid refrigerant; an expansion valve 14 which communicates with the other end of the receiver 53 and has a refrigerant decompression function and a refrigerant flow rate adjusting function; The evaporator 13 connected to the container 12 and arranged indoors, and the accumulator 54 arranged in the suction pipe of the compressor 11 for recovering and removing the liquid refrigerant in the suction refrigerant are arranged to circulate the refrigerant. Is configured to cause heat transfer.

The condenser 1 constituting the outdoor heat exchanger
2 functions as a condenser during cooling operation, but functions as an evaporator during heating operation, and the evaporator 13 constituting the indoor heat exchanger functions as an evaporator during cooling operation, but a condenser during heating operation. 3, and accordingly, the four-way switching valve 52 can be switched so as to have a communication relationship shown by a solid line in FIG. 3 during a cooling operation and a communication relationship shown by a broken line in FIG. 3 during a heating operation. ing.

From the oil recovery unit 51 to the compressor 1
An oil return circuit 55 is provided which connects to the suction pipe connected to the accumulator 54 and returns the oil collected by the oil recovery unit 51 to the suction side of the compressor 11.

The expansion valve 14 is constituted by an electric expansion valve, and is disposed between the condenser 12 and one end P of the common path 500, which is connected to the lower liquid portion of the receiver 53, on the upper side of the receiver 53. In the first channel 501, the condenser 1
A first check valve 56 is provided which allows only the flow of the refrigerant from 2 to the receiver 53.

A second check valve 57, which allows only the flow of the refrigerant from the evaporator 13 to the receiver 53, is arranged in the second flow path 502 between the point P and the evaporator 13. It is set up.

Further, the flow from the expansion valve 14 to the condenser 12 is allowed in the third flow path 503 between the one end S of the first check valve 56 and the other end Q of the expansion valve 14. Third
A check valve 58 is provided, and from the expansion valve 14 to the evaporator 13, a fourth flow path 504 between the one end R of the second check valve 57 and the other end Q of the expansion valve 14 is provided. A fourth check valve 59 that allows the flow of the above is provided.

As shown in FIG. 3, the sensor 2 is provided in the suction pipe of the compressor 11, and a suction temperature sensor 21 for detecting the temperature of the refrigerant supplied from the evaporator 13 to the suction pipe, and the compressor 11 are provided. Discharge temperature sensor 22 for detecting the temperature of the refrigerant discharged to the discharge pipe, and the condenser 1 constituting the outdoor heat exchanger.
An outdoor heat exchanger temperature sensor 23, which is arranged in the second liquid pipe and detects the condensation temperature of the refrigerant during the cooling operation, and the evaporation temperature of the refrigerant during the heating operation, and the air suction port of the condenser 12 that constitutes the outdoor heat exchanger. An outdoor air temperature sensor 24 for detecting the outdoor air temperature, an indoor temperature sensor 25 disposed near the indoor thermostat for detecting the indoor air temperature, and an indoor air temperature sensor 25 disposed in the suction pipe of the compressor 11 for calculating the degree of superheat. A suction pressure sensor 26 for detecting a suction pressure, a low pressure operation switch 27 arranged in the suction pipe of the compressor 11 for activating and abnormally stopping when the low pressure side pressure reaches a lower limit, and arranged in the discharge pipe of the compressor 11. And a high-pressure operation switch 28 that operates and abnormally stops when the high-pressure side pressure reaches the upper limit, and the engine that rotationally drives the compressor 11. Made from the engine speed sensor 29 for detecting the rotational speed of 10.

Each of the sensors 21 to 29 constituting the sensor 2 is connected to the control device 3 and outputs a detected signal, and the operation of each device is controlled according to the signal input by the control device 3. Is configured to.

The control device 3 is composed of a computer, and a large control constant is set for a certain time after the compressor is started, and a small control constant is set after the certain time elapses. The opening degree (pulse number) of the expansion valve is calculated based on the difference from the superheat degree, the temporal change in the superheat degree, and the temporal change in the engine speed.

That is, the difference between the superheat degree and the target superheat degree is multiplied by the proportional constant shown in Table 1, and the difference between the present superheat degree and the previous superheat degree is multiplied by the differential constant shown in Table 1. And the difference between the current engine speed and the previous engine speed multiplied by the engine coefficient shown in Table 1, the pulse number change amount of the expansion valve 14 is determined.

[Table 1]

In the first embodiment, the target superheat degree is set to 10 ° C. during the cooling operation and 8 ° C. during the heating operation, respectively, and the control constants such as the proportional constant, the differential constant and the engine coefficient are set. As shown in Table 1, by making the value larger than that during normal operation, the target superheat is brought closer to the target as soon as possible, and the rising time of the air conditioner is shortened.

The control program shown in the flow chart of FIG. 4 is previously stored in the ROM of the computer constituting the control device 3 in order to realize the above-mentioned calculation.

The drive unit 4 is composed of a stepping motor, and is configured to control the movable valve member of the expansion valve 14 according to the number of pulses output by the control unit 3 to control the valve opening degree. Become.

In the air conditioner of the first embodiment having the above structure, during the cooling operation, the liquid refrigerant condensed and liquefied in the outdoor condenser 12 flows from the first flow path 501 to the common path 500. And stored in the receiver 53.

The refrigerant stored in the receiver 53 is decompressed by the expansion valve 14 and then supplied to the indoor evaporator 13 through the second flow path 502 to be evaporated and then to the compressor 11. It will be a return cycle.

On the other hand, during the heating operation, the liquid refrigerant condensed and liquefied in the indoor heat exchanger 13 flows from the second flow path 502 to the common path 500, is stored in the receiver 53, and is expanded by the expansion valve 14. After being decompressed, it is supplied to the outdoor heat exchanger 12 through the third flow path 503, evaporates and returns to the compressor 11 for circulation.

FIG. 4 shows the operation of the operation control device for the air conditioner of the first embodiment having the above-described structure during the cooling operation, that is, the contents of the start control when the compressor 11 is started and the contents of the control during the normal operation. It will be described according to the flowchart shown. The device of this embodiment is set so as not to operate when the temperature is 20 ° C. or lower during the cooling operation.

In step 101, the expansion valve 14
Is set to 1000 pulses, and then in step 102, the four-way switching valve 52 is turned on, that is, in the cooling cycle.

In step 103, the compressor 11 is started, and in step 104, the opening change amount of the expansion valve 14 is calculated. That is, the superheat calculation means 31 causes the saturation temperature corresponding to the pressure of the refrigerant in the suction pipe detected by the suction pressure sensor 26 and the evaporator 13 detected by the suction temperature sensor 21 to move the compressor 11 from the evaporator 13. The degree of superheat is calculated based on the temperature of the refrigerant supplied to the suction pipe, and the expansion valve opening degree calculating means 32 calculates the degree of superheat calculated by the degree of superheat calculating means 31, the set target degree of superheat, and the previous degree of superheat. Calculation is performed based on the degree of superheat, the engine speed, and the previous engine speed, and the pulse number change amount of the expansion valve 14 is calculated.

In step 105, the stepping motor constituting the drive unit 4 drives the expansion valve 14 to control the valve opening based on the pulse number change amount calculated by the expansion valve opening calculation means 32. In this state, the timer is maintained for 15 minutes.

After 15 minutes, in step 106, when the average value of the calculated superheat is within the range of 5 ° C. to 15 ° C., in step 107
Using the control constants such as the proportional constant, the differential constant and the engine coefficient in the normal operation, the expansion valve opening calculation means 32 performs the same calculation as described above to calculate the pulse number change amount of the expansion valve 14 in the normal operation. To do.

In step 108, the stepping motor constituting the drive unit 4 drives the expansion valve 14 based on the pulse number change amount calculated by the expansion valve opening calculation means 32 to set the valve opening for normal operation. Control.

The control constants in the above normal operation are shown in Table 1.
The value is set to a small value as shown in (4) so that the degree of superheat does not overshoot and hunting is prevented so that the operation stop is avoided.

In the heating operation, the number of pulses that determine the initial opening of the expansion valve 14 is set to 800 when the compressor 11 is started.

The operation controller of the air conditioner of the first embodiment having the above-mentioned operation controls the opening degree of the expansion valve 14 based on the degree of superheat calculated by the controller 3, so that it is conventional. Since it is not necessary to control the air flow rate of the outdoor fan as described above, the system configuration is simplified, and accordingly, troubles are avoided, reliability is increased, and cost is reduced.

Further, in the operation control device for the air conditioner of the first embodiment, the control device 3 sets the control constant to a large value for 15 minutes after the compressor 11 is started, so that the air conditioner approaches the set superheat degree quickly. In addition to the effect that the indoor temperature can be brought close to the set temperature quickly, the control constant is set small after the lapse of the 15 minutes, and the control is performed so as to stabilize the set superheat, so that the overshoot of the superheat occurs. There is an effect that it is possible to improve reliability at low cost by suppressing the hunting based on the above and avoiding the operation stop.

Further, in the operation control device for the air conditioner of the first embodiment, since the control constant is made large during the fixed time when the compressor 11 is started, the high pressure cutoff is suppressed by suppressing the increase of the high pressure side pressure in the high outside air. Further, it is possible to avoid the operation stop of the air conditioner due to the excessive rise of the discharge pipe temperature.

Further, in the first embodiment, the control constant of the expansion valve is increased even when the compressor 11 is started during the heating operation, thereby suppressing the decrease in the low pressure side pressure in the low outside air. In addition to the effect of avoiding the operation stop of the air conditioner due to the low pressure cut and the excessive rise of the discharge pipe temperature, after reaching the set superheat degree, the hunting of the superheat degree is suppressed by reducing the control constant. By avoiding the operation stop, it is possible to improve reliability at low cost.

That is, in the heating operation, if the opening degree of the electric expansion valve 14 is controlled to be constant as in the conventional case, the low pressure side pressure is lowered in the low outside air region due to the reduction of the evaporation capacity of the outdoor heat exchanger. Although the pressure may momentarily excessively decrease to cause a low pressure cut or an excessive increase in the discharge temperature, the operation may be stopped. However, in the first embodiment, by increasing the control constant for a certain period of time, the evaporation capacity and the refrigerant circulation amount are increased. Is moderately maintained, and the pressure drop on the low pressure side is suppressed.

Further, in the first embodiment, in the high outside air area, the outside air is switched to the outside air and the heating operation is not performed. Therefore, the evaporation capacity of the outdoor heat exchanger becomes excessive, and the high pressure side pressure rises. There is no possibility that a peak that rises excessively instantaneously will occur, resulting in an excessive rise in discharge pipe temperature and a high pressure cut. As a result, the operation stop of the air conditioner is avoided.

The embodiments described above are merely examples for the purpose of explanation, and the present invention is not limited to them. Those skilled in the art will recognize from the claims, the detailed description of the invention and the description of the drawings. Modifications and additions can be made without departing from the technical idea of the present invention.

In the above-mentioned embodiments, the example in which the superheat degree is converged to the target value has been described as an example, but the present invention is not limited to this, and for example, the discharge temperature or the supercooling degree of the condenser is targeted. A mode of converging to a value can also be adopted.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a first embodiment device of the present invention.

FIG. 2 is a schematic view showing a duct air conditioning system to which the first embodiment is applied.

FIG. 3 is a block diagram showing a refrigerant circuit of the first embodiment.

FIG. 4 is a chart showing a control flow of the first embodiment.

FIG. 5 is a schematic diagram showing a conventional individual air conditioning system.

[Explanation of symbols]

 1 Duct type air conditioner 2 Sensor 3 Control device 4 Drive device 5 Refrigerant circuit 11 Compressor 12 Condenser 13 Evaporator 14 Expansion valve 31 Superheat calculation device 32 Expansion valve opening calculation means

Claims (7)

[Claims] 1. An air conditioner comprising a compressor, a condenser, an evaporator, and an expansion valve, which takes in outside air and performs air conditioning, wherein the temperature and the outlet side of the outlet side of at least one of the condenser and the evaporator. An operation control device for an air conditioner, comprising: a control device that controls the opening degree of the expansion valve based on a temperature difference from a saturation temperature corresponding to the pressure of the refrigerant. 2. The control device according to claim 1, wherein the control device opens the expansion valve based on a degree of superheat determined by a difference between a temperature on an outlet side of the evaporator and a saturation temperature corresponding to a pressure on the outlet side. An air conditioner operation control device characterized by controlling the temperature. 3. The expansion device according to claim 1, wherein the control device controls the expansion valve based on a degree of supercooling determined by a difference between a temperature on an outlet side of the condenser and a saturation temperature corresponding to a pressure on the outlet side. An operation control device for an air conditioner, which controls an opening. 4. The superheat degree calculating means according to claim 2, wherein the controller calculates a superheat degree on the basis of a temperature on the outlet side of the evaporator and a pressure on the outlet side, and the superheat degree calculating means calculates. An operation control device for an air conditioner, comprising: an expansion valve opening degree calculation means for calculating an opening degree of the expansion valve based on the superheat degree, the target superheat degree, and an engine speed. 5. The air conditioner according to claim 4, wherein the control device sets a large control constant for a certain period of time after starting the compressor, and sets a small control constant after the certain period of time has elapsed. Operation control device. 6. The air conditioner according to claim 5, wherein the control device calculates the opening degree of the expansion valve based on a difference between the superheat degree and the target superheat degree and a temporal change in the superheat degree. Device operation control device. 7. The operation control device for an air conditioner according to claim 6, wherein the control device calculates the opening degree of the expansion valve based on a temporal change in the engine speed.