JPH08219572A - Air conditioner - Google Patents

Abstract

PURPOSE: To avoid danger of breaking a compressor due to a liquid compression by improving computing accuracy of the degree of overcooling at an inlet of an outdoor side expansion valve to control the opening of the outdoor side expansion valve to a proper value during the heating operation in an air conditioning equipment using a non-azeotropic mixed refrigerant. CONSTITUTION: A circulated refrigerant composition ratio forecasting means 19 is provided to forecast a composition ratio of a circulated refrigerant based on the height of a liquid surface in an accumulator 6 as detected by a liquid surface height detecting sensor 18. In the heating operation, a degree of overcooling computing means 25 computes the degree of overcooling at an inlet of the outdoor side expansion valve based on a high pressure side pressure as detected by a high pressure side pressure detection sensor 12, the temperature of a liquid piping as detected by a liquid piping temperature detection sensor 13 and a composition ratio of the circulated refrigerant forecast by the circulated refrigerant composition ratio forecast means 19. Then, based on the results of the computation, an outdoor side expansion valve control means 17 controls the opening of an outdoor side expansion valve 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner using a non-azeotropic mixed refrigerant.

[0002]

2. Description of the Related Art Conventionally, as this type of air conditioner, for example, there is an air conditioner disclosed in Japanese Patent Laid-Open No. 1-212870.

The above-mentioned air conditioner will be described below with reference to the drawings. In FIG. 16, the outdoor unit 1 of the air conditioner includes a compressor 2, a four-way valve 3, an outdoor heat exchanger 4,
It is composed of an outdoor expansion valve 5 and an accumulator 6. In addition, the indoor unit 7 includes an indoor expansion valve 8 and an indoor heat exchanger 9. Further, the outdoor unit 1 and the indoor unit 7
Are annularly connected by the liquid pipe 10 and the gas pipe 11 to form a refrigerant circuit.

Further, a high pressure side pressure detection sensor 12 for detecting the high pressure side pressure and a liquid pipe temperature detection sensor 13 mounted between the indoor expansion valve 8 and the outdoor expansion valve 5 for detecting the temperature are provided. The supercooling degree calculating means 15 for calculating the supercooling degree based on the high pressure side pressure detected by the pressure detecting sensor 12 and the liquid pipe temperature detected by the liquid pipe temperature detecting sensor 13, and the supercooling degree calculating means 15 for calculating the supercooling degree. It has an outdoor expansion valve control means 17 for controlling the outdoor expansion valve 5 based on the degree of cooling. It should be noted that three indoor units 6 are connected in this conventional example, and the subscripts a, b, and c are added to distinguish them.

Next, regarding the operation of the air conditioner having the above-mentioned configuration, when a non-azeotropic mixed refrigerant is used, the liquid refrigerant pool in the accumulator 6 causes a change in the composition ratio of the circulating refrigerant, and a heating operation. Only time will be explained.

In the heating operation, the high-temperature high-pressure gas discharged from the compressor 2 is guided to each indoor heat exchanger 9 through the four-way valve 3, where it is condensed and liquefied and then passes through the indoor expansion valve 8. Flow into the liquid pipe 10, the pressure is reduced to a low pressure two-phase state by the outdoor expansion valve 5, enters the outdoor heat exchanger 4, evaporates and vaporizes, and passes through the four-way valve 3 and the accumulator 6 to the compressor 2. Return and perform heating operation.

At this time, the subcooling degree calculating means 15 calculates the degree of subcooling of the outdoor expansion valve inlet from the high pressure side pressure detected by the high pressure side pressure detection sensor 12, and the liquid pipe temperature detection sensor 13. Calculated as the temperature difference detected by the outdoor expansion valve control means 17 and the outdoor expansion valve 5
When the calculated supercooling degree becomes smaller than a predetermined value, the opening degree is decreased, and when the supercooling degree becomes larger than the predetermined value, the opening degree is increased to control the outdoor expansion valve 5 to an appropriate opening degree. ing.

[0008]

However, in the above structure, when a non-azeotropic mixed refrigerant (for example, two kinds of mixed refrigerants of R134a which is a high boiling point refrigerant and R32 which is a low boiling point refrigerant) is used, When the non-azeotropic mixed refrigerant is in a gas-liquid equilibrium state in the accumulator 6, the liquid side has a high composition ratio of the high boiling point refrigerant and the gas side has a high composition ratio of the low boiling point refrigerant. Therefore, the compressor 2 sucks the gas refrigerant rich in the low boiling point refrigerant in the accumulator 6, so that the refrigerant having a high composition ratio of the low boiling point refrigerant circulates in the cycle.

Therefore, at the same pressure, the liquid saturation temperature of the circulating refrigerant is lowered, and the degree of supercooling calculated by the supercooling degree calculating means 15 becomes larger than the degree of supercooling of the circulating refrigerant, so that the outdoor expansion valve control is performed. The opening degree of the outdoor expansion valve 5 controlled by the means 17 becomes larger than the appropriate opening degree. For this reason, the refrigerant circulation amount increases, the refrigerant at the outlet of the outdoor heat exchanger 4 is not completely evaporated, and is in a wet state. As a result, liquid compression due to liquid return to the compressor 2 occurs, and the compressor 2 There was a drawback that the risk of breakage was high.

The present invention solves the conventional problems. In the heating operation when a non-azeotropic mixed refrigerant is used, the composition ratio of the circulating refrigerant is predicted and the liquid saturation temperature is accurately calculated, so that the outdoor side. By improving the calculation accuracy of the degree of supercooling at the inlet of the expansion valve and controlling the opening of the outdoor expansion valve to an appropriate opening, liquid return to the compressor causes liquid compression, resulting in damage to the compressor. An object is to provide an air conditioner capable of avoiding the risk of

[0011]

In order to solve the above problems, the present invention uses an non-azeotropic mixed refrigerant and is an outdoor unit including a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion valve, and an accumulator. Machine, an indoor expansion valve, an indoor unit consisting of an indoor heat exchanger to form an annular refrigerant circuit, a liquid level height detection sensor for detecting the height of the liquid level in the accumulator, From the liquid level in the accumulator detected by the liquid level detection sensor, a circulating refrigerant composition ratio predicting means for predicting a composition ratio of the circulating refrigerant, a high pressure side pressure detecting sensor for detecting a high pressure side pressure, and a liquid pipe Liquid pipe temperature detection sensor to detect temperature, and during heating operation,
The composition ratio of the circulating refrigerant predicted by the circulating refrigerant composition ratio predicting unit, the high pressure side pressure detected by the high pressure side pressure detection sensor, and the liquid pipe temperature detected by the liquid pipe temperature detection sensor The subcooling degree calculating means for calculating the inlet supercooling degree and the outdoor expansion valve control means for controlling the opening degree of the outdoor expansion valve according to the supercooling degree calculated by the supercooling degree calculating means are provided. It has been configured.

Further, a non-azeotropic mixed refrigerant is used, a compressor,
A four-way valve, an outdoor heat exchanger, an outdoor expansion valve, an outdoor unit consisting of an accumulator and an indoor expansion valve, an indoor unit consisting of an indoor heat exchanger to form an annular refrigerant circuit,
High pressure side pressure detection sensor for detecting high pressure side pressure, outside air temperature detection sensor for detecting outside air temperature, indoor load detection means for detecting indoor load, indoor load detected by the indoor load detection means, and the outside air temperature Circulating refrigerant composition ratio prediction means for predicting the composition ratio of the circulating refrigerant from the outside air temperature detected by the detection sensor and the high pressure side pressure detected by the high pressure side pressure detection sensor, and a liquid pipe temperature detection sensor for detecting the liquid pipe temperature And during heating operation,
The composition ratio of the circulating refrigerant predicted by the circulating refrigerant composition ratio predicting unit, the high pressure side pressure detected by the high pressure side pressure detection sensor, and the liquid pipe temperature detected by the liquid pipe temperature detection sensor The subcooling degree calculating means for calculating the inlet supercooling degree and the outdoor expansion valve control means for controlling the opening degree of the outdoor expansion valve according to the supercooling degree calculated by the supercooling degree calculating means are provided. It has been configured.

Further, a non-azeotropic mixed refrigerant is used, a compressor,
A four-way valve, an outdoor heat exchanger, an outdoor expansion valve, an outdoor unit consisting of an accumulator and an indoor expansion valve, an indoor unit consisting of an indoor heat exchanger to form an annular refrigerant circuit,
High pressure side pressure detection sensor for detecting high pressure side pressure, outside air temperature detection sensor for detecting outside air temperature, and compressor operation for controlling the operating frequency of the compressor by the high pressure side pressure detected by the high pressure side pressure detection sensor Frequency control means, indoor load detection means for detecting indoor load, indoor load detected by the indoor load detection means, outdoor air temperature detected by the outdoor air temperature detection sensor, and operating frequency of the compressor, circulating refrigerant Circulating refrigerant composition ratio predicting means for predicting the composition ratio of, the liquid pipe temperature detection sensor for detecting the liquid pipe temperature, during heating operation, the composition ratio of the circulating refrigerant predicted by the circulating refrigerant composition ratio predicting means, and the high pressure By the high pressure side pressure detected by the side pressure detection sensor and the liquid pipe temperature detected by the liquid pipe temperature detection sensor Supercooling degree calculating means for calculating the degree of supercooling at the inlet of the outdoor expansion valve, and outdoor expansion valve control for controlling the degree of opening of the outdoor expansion valve according to the degree of supercooling calculated by the degree of supercooling calculation means It is configured to include means.

Further, a non-azeotropic mixed refrigerant is used, a compressor,
A four-way valve, an outdoor heat exchanger, an outdoor expansion valve, an outdoor unit consisting of an accumulator and an indoor expansion valve, an indoor unit consisting of an indoor heat exchanger to form an annular refrigerant circuit,
A high pressure side pressure detection sensor for detecting the high pressure side pressure, a discharge temperature detection sensor for detecting the discharge temperature of the compressor,
An outside air temperature detection sensor for detecting the outside air temperature, an outside air temperature detected by the outside air temperature detection sensor, and a high pressure side pressure detected by the high pressure side pressure detection sensor,
From the discharge temperature of the compressor detected by the discharge temperature detection sensor, a circulating refrigerant composition ratio prediction means for predicting a composition ratio of the circulating refrigerant, a liquid pipe temperature detection sensor for detecting a liquid pipe temperature, and during heating operation, The composition ratio of the circulating refrigerant predicted by the circulating refrigerant composition ratio predicting means, the high pressure side pressure detected by the high pressure side pressure detection sensor, and the liquid pipe temperature detected by the liquid pipe temperature detection sensor Constitution comprising supercooling degree calculating means for calculating the degree of subcooling and outdoor side expansion valve control means for controlling the degree of opening of the outdoor side expansion valve according to the degree of supercooling calculated by the degree of supercooling calculation means Has become.

[0015]

According to the present invention, the accumulator having the above-described structure is used during heating operation when a non-azeotropic mixed refrigerant (for example, two kinds of mixed refrigerant of R134a which is a high boiling point refrigerant and R32 which is a low boiling point refrigerant) is used. When the non-azeotropic mixed refrigerant is in a gas-liquid equilibrium state, the composition ratio of the high boiling point refrigerant is high on the liquid side and the composition ratio of the low boiling point refrigerant is high on the gas side. Therefore, since the compressor sucks the gas refrigerant rich in the low boiling point refrigerant in the accumulator, when the liquid amount in the accumulator increases and the liquid level rises, the low boiling point refrigerant composition ratio of the circulating refrigerant increases. Further, when the amount of liquid in the accumulator decreases and the height of the liquid surface decreases, the composition ratio of the low boiling point refrigerant of the circulating refrigerant becomes low. Therefore, the composition ratio of the circulating refrigerant can be predicted from the height of the liquid level in the accumulator. The liquid saturation temperature can be accurately calculated from the predicted composition ratio of the circulating refrigerant, the calculation accuracy of the outdoor expansion valve inlet supercooling degree can be improved, and the opening degree of the outdoor expansion valve can be controlled to an appropriate opening degree. Therefore, the risk of damage to the compressor due to liquid compression for returning the liquid to the compressor can be avoided.

When the load on the indoor side and the outside air temperature are the same, the high-pressure side pressure rises above a predetermined value as the low-boiling point refrigerant composition ratio of the circulating refrigerant increases. Further, when the low boiling point refrigerant composition ratio of the circulating refrigerant becomes low, the high-pressure side pressure becomes lower than a predetermined value. Therefore, a predetermined value of the high-pressure side pressure is obtained from the indoor load and the outside air temperature, and the composition ratio of the circulating refrigerant can be predicted from the difference between the predetermined value and the high-pressure side pressure detected by the high-pressure side pressure detection sensor. The liquid saturation temperature can be accurately calculated from the predicted composition ratio of the circulating refrigerant, the calculation accuracy of the outdoor expansion valve inlet supercooling degree can be improved, and the opening degree of the outdoor expansion valve can be controlled to an appropriate opening degree. Therefore, the risk of damage to the compressor due to liquid compression for returning the liquid to the compressor can be avoided.

Further, when the load on the indoor side and the outside air temperature are the same, when the low boiling point refrigerant composition ratio of the circulating refrigerant becomes high, the high pressure side force rises, and the compressor controlled by the high pressure side pressure increases. The operating frequency drops below a predetermined value. Further, when the low-boiling-point refrigerant composition ratio of the circulating refrigerant decreases, the high-pressure side pressure decreases, and the operating frequency of the compressor controlled by the high-pressure side pressure rises above a predetermined value. Therefore, the predetermined value of the operating frequency of the compressor is obtained from the indoor load and the outside air temperature, and the composition ratio of the circulating refrigerant can be predicted from the difference between the predetermined value and the actual operating frequency of the compressor. The liquid saturation temperature can be accurately calculated from the predicted composition ratio of the circulating refrigerant, the calculation accuracy of the outdoor expansion valve inlet supercooling degree can be improved, and the opening degree of the outdoor expansion valve can be controlled to an appropriate opening degree. Therefore, the risk of damage to the compressor due to liquid compression for returning the liquid to the compressor can be avoided.

Further, when the outside air temperature and the pressure on the high pressure side are the same, when the low boiling point refrigerant composition ratio of the circulating refrigerant becomes high, the gas saturation temperature becomes low and the discharge temperature becomes lower than a predetermined value. Further, when the low boiling point refrigerant composition ratio of the circulating refrigerant becomes low, the gas saturation temperature rises and the discharge temperature rises above a predetermined value. Therefore, the predetermined value of the discharge temperature of the compressor is obtained from the outside air temperature and the pressure on the high pressure side, and the composition ratio of the circulating refrigerant is determined by the difference between the predetermined value and the discharge temperature of the compressor detected by the discharge temperature detection sensor. Can be predicted. The liquid saturation temperature can be accurately calculated from the predicted composition ratio of the circulating refrigerant, the calculation accuracy of the outdoor expansion valve inlet supercooling degree can be improved, and the opening degree of the outdoor expansion valve can be controlled to an appropriate opening degree. Therefore, the risk of damage to the compressor due to liquid compression for returning the liquid to the compressor can be avoided.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. The same parts as those of the prior art are designated by the same reference numerals, and detailed description thereof will be omitted.

First, the first embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. In FIG. 1, 18 is a liquid level detection sensor (for example, a plurality of float switches) that detects the position of the liquid level in the accumulator 6. Further, 19 is a circulating refrigerant composition ratio predicting means for predicting the composition ratio of the circulating refrigerant from the height of the liquid surface in the accumulator 6 detected by the liquid surface height detection sensor 18.

Here, the supercooling degree calculating means 25, the composition ratio of the circulating refrigerant predicted by the refrigerant composition ratio predicting means 19, the high pressure side pressure detected by the high pressure side pressure detecting sensor 12 during the heating operation, and the liquid piping Temperature sensor 1
The outdoor expansion valve inlet supercooling degree is calculated based on the liquid pipe temperature detected by 3, and the outdoor expansion valve control means 1
Reference numeral 7 controls the opening degree of the outdoor expansion valve 5 according to the degree of supercooling calculated by the degree of supercooling calculating means 25.

Next, the operation of the air conditioner thus constructed during the heating operation, which is a problem, will be described. The same components as those of the conventional example are designated by the same reference numerals,
Detailed description thereof will be omitted.

First, FIG. 2 is a flow chart of the air conditioner in the first embodiment of the present invention, and FIG. 3 is a liquid level height of the accumulator and the low boiling point refrigerant composition of the circulating refrigerant in the first embodiment of the present invention. It is a characteristic view which shows the relationship of a ratio.

As shown in FIG. 2, first, in step 1, the liquid level height sensor 18 detects the liquid level height H in the accumulator 6. In step 2, when the liquid level height H in the accumulator 6 is changed to a gas-liquid equilibrium state in the accumulator 6, the composition ratio of the high boiling point refrigerant is high on the liquid side and low on the gas side. Since the composition ratio of the boiling point refrigerant becomes high and the compressor 2 sucks the gas refrigerant rich in the low boiling point refrigerant in the accumulator 6, when the liquid amount in the accumulator 6 increases and the liquid level rises, the circulating refrigerant becomes low. The boiling point refrigerant composition ratio becomes high, and the accumulator 6
When the amount of liquid in the inside decreases and the liquid level decreases, the composition ratio of the low boiling point refrigerant of the circulating refrigerant becomes low, and thus the accumulator liquid level height and the low boiling point refrigerant composition ratio of the circulating refrigerant shown in FIG. It is converted into the low boiling point refrigerant composition ratio X of the circulating refrigerant using the characteristic diagram showing the relationship. In step 3, the high side pressure detecting sensor 12 detects the high-pressure side pressure P _a. In step 4, the liquid pipe temperature detection sensor 13 detects the liquid pipe temperature T _a.

In step 5, the supercooling degree calculating means 25 calculates the difference between the liquid boiling temperature T _a and the liquid saturation temperature T _b converted from the low boiling point refrigerant composition ratio X of the circulating refrigerant and the high pressure side pressure P _a. , And the supercooling degree SC is calculated. In step 6,
The outdoor expansion valve control means 17 controls the outdoor expansion valve 5 to an opening degree corresponding to the calculated supercooling degree SC.

According to the first embodiment, the circulation is performed during the heating operation when the non-azeotropic mixed refrigerant (for example, two kinds of mixed refrigerant of R134a which is a high boiling point refrigerant and R32 which is a low boiling point refrigerant) is used. By predicting the composition ratio of the refrigerant and accurately calculating the liquid saturation temperature, the calculation accuracy of the inlet supercooling degree of the outdoor expansion valve 5 is improved and the opening degree of the outdoor expansion valve 5 is controlled to an appropriate opening degree. be able to. Therefore, the risk of damage to the compressor 2 due to the liquid compression for returning the liquid to the compressor 2 can be avoided.

Next, a second embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. In FIG. 4, reference numeral 14 denotes an outside air temperature detection sensor that detects the outside air temperature. Reference numeral 16 denotes an indoor load detecting means for detecting an indoor load. In this embodiment, the indoor load is detected from the operating capacity of the indoor unit 7 and the opening degree of the indoor expansion valve 8. Further, reference numeral 20 predicts the composition ratio of the circulating refrigerant from the indoor load detected by the indoor load detection means 16, the outside air temperature detected by the outside air temperature detection sensor 14, and the high pressure side pressure detected by the high pressure side pressure detection sensor 12. It is a circulating refrigerant composition ratio predicting means.

Here, the supercooling degree calculating means 25 and the composition ratio of the circulating refrigerant predicted by the refrigerant composition ratio predicting means 20 and the high pressure side pressure detecting sensor 12 during the heating operation.
The high-pressure side pressure detected by the liquid pipe temperature detection sensor 13 and the liquid pipe temperature detected by the liquid pipe temperature detection sensor 13 calculate the outdoor expansion valve inlet supercooling degree, and the outdoor expansion valve control means 17 calculates the supercooling degree. The opening degree of the outdoor expansion valve 5 is controlled according to the degree of supercooling calculated by the means 25.

Next, the operation of the air conditioner thus constructed during the heating operation, which is a problem, will be described. The same components as those of the conventional example are designated by the same reference numerals,
Detailed description thereof will be omitted.

First, FIG. 5 is a flow chart of the air conditioner in the second embodiment of the present invention, and FIG. 6 shows predetermined values of the indoor load, the outside air temperature and the high pressure side in the second embodiment of the present invention. FIG. 7 is a characteristic diagram showing the relationship, and FIG. 7 is a characteristic diagram showing the relationship between the difference between the detected value of the high pressure side pressure and the predetermined value and the low boiling point refrigerant composition ratio of the circulating refrigerant in the second embodiment of the present invention.

From FIG. 5, first, in step 11, the high pressure side pressure detection sensor 12 detects the high pressure side pressure P _a .
In step 12, if the indoor load detection means 16 increases the indoor load due to a decrease in the indoor temperature or the indoor fan is set to strong operation,
If the load on the indoor side decreases due to an increase in the opening degree of the indoor expansion valve 8 and an increase in the indoor temperature, or the indoor fan is set to a weak operation, the indoor expansion is performed. By utilizing the fact that the opening degree of the valve 8 decreases, the indoor load A is detected from the operating capacity of the indoor unit 7 and the opening degree of the indoor expansion valve 8. In step 13, the outside air temperature detection sensor 14 detects the outside air temperature T _c .

Next, in step 14, the circulating refrigerant composition ratio predicting means 20 shows the indoor load A detected by the indoor load detecting means 16 and the outside air temperature T _c detected by the outside air temperature detecting sensor 14 in FIG. using a characteristic diagram showing the relationship between the indoor load and the outside air temperature and a predetermined value of the high side pressure, it is converted to a predetermined value P _b of the high-pressure side pressure. And the load on the indoor side, and
When the outside air temperature is the same, when the low boiling point refrigerant composition ratio of the circulating refrigerant becomes high, the high pressure side pressure rises above a predetermined value, and when the low boiling point refrigerant composition ratio of the circulating refrigerant becomes low, the high pressure side pressure becomes a predetermined value. Figure 7
To the difference between the detected value and a predetermined value of the high-pressure side pressure indicated, using a characteristic diagram showing the relationship of the low boiling point refrigerant composition ratio of the circulating refrigerant, the high-pressure side pressure P _a and the high-pressure side pressure high pressure side sensor 12 has detected The difference between the predetermined values P _b is calculated by the low boiling point refrigerant composition ratio X of the circulating refrigerant.
Calculate to. In step 15, the liquid pipe temperature detection sensor 13 detects the liquid pipe temperature T _a.

Then, in step 16, the supercooling degree computing means 25 causes the circulating refrigerant composition ratio predicting means 20 to predict the low boiling point refrigerant composition ratio X of the circulating refrigerant and the high pressure side sensor 12.
Liquid saturation temperature T but which is calculated from the high side pressure P _a of detecting
and _b, and the difference between the liquid pipe temperature T _a, is calculated as a degree of supercooling SC. In step 17, the outdoor expansion valve control means 17
The outdoor expansion valve 5 is controlled to an opening degree according to the calculated supercooling degree SC.

According to the second embodiment, the accumulator is used during the heating operation when the non-azeotropic mixed refrigerant (for example, two kinds of mixed refrigerant of R134a which is a high boiling point refrigerant and R32 which is a low boiling point refrigerant) is used. Calculating the composition ratio of the circulating refrigerant and calculating the liquid saturation temperature with high accuracy without complicating the production process by mounting the liquid level sensor on the The accuracy can be improved and the opening degree of the outdoor expansion valve 5 can be controlled to an appropriate opening degree. Therefore, the risk of damage to the compressor 2 due to the liquid compression for returning the liquid to the compressor 2 can be avoided.

Next, a third embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. In FIG. 8, reference numeral 14 is an outside air temperature detection sensor that detects the outside air temperature. Also, 16
Is an indoor load detecting means for detecting an indoor load, and in this embodiment, the indoor load is detected from the operating capacity of the indoor unit 7 and the opening degree of the indoor expansion valve 8. Reference numeral 22 is a compressor operating frequency control means for controlling the operating frequency of the compressor 2.
Reference numeral 21 denotes the indoor load detected by the indoor load detection means 16 and the outside air temperature detected by the outside air temperature detection sensor 14,
It is a circulating refrigerant composition ratio predicting means for predicting the composition ratio of the circulating refrigerant from the operating frequency of the compressor 2.

Here, the supercooling degree calculating means 25, the composition ratio of the circulating refrigerant predicted by the refrigerant composition ratio predicting means 21, the high pressure side pressure detected by the high pressure side pressure detecting sensor 12 during the heating operation, and the liquid piping Temperature sensor 1
The outdoor expansion valve inlet supercooling degree is calculated based on the liquid pipe temperature detected by 3, and the outdoor expansion valve control means 1
Reference numeral 7 controls the opening degree of the outdoor expansion valve 5 according to the degree of supercooling calculated by the degree of supercooling calculating means 25.

Next, the operation of the air conditioner thus constructed during the heating operation, which is a problem, will be described. The same components as those of the conventional example are designated by the same reference numerals,
Detailed description thereof will be omitted.

First, FIG. 9 is a flow chart of an air conditioner in a third embodiment of the present invention, and FIG. 10 is a predetermined value of indoor load, outside air temperature and compressor operating frequency in the third embodiment of the present invention. FIG. 11 is a characteristic diagram showing the relationship showing the characteristic of FIG. 11, and FIG. 11 shows the relationship between the difference between the predetermined value of the compressor operating frequency and the low boiling point refrigerant composition ratio of the circulating refrigerant in the third embodiment of the present invention. It is a characteristic view which shows the relationship which shows the characteristic shown.

From FIG. 9, first, in step 21, the high pressure side pressure detection sensor 12 detects the high pressure side pressure P _a .
In step 22, if the indoor load detection means 16 increases the indoor load due to a decrease in the indoor temperature or the indoor fan is set to strong operation,
If the load on the indoor side decreases due to an increase in the opening degree of the indoor expansion valve 8 and an increase in the indoor temperature, or the indoor fan is set to a weak operation, the indoor expansion is performed. By utilizing the fact that the opening degree of the valve 8 decreases, the indoor load A is detected from the operating capacity of the indoor unit 7 and the opening degree of the indoor expansion valve 8.

Next, at step 23, the outside air temperature detection sensor 14 detects the outside air temperature T _c . In step 24, the circulating refrigerant composition ratio prediction means 21 sets the indoor load A detected by the indoor load detection means 16 and the outside air temperature T _c detected by the outside air temperature detection sensor 14 as the indoor load and the outside air temperature shown in FIG. It is converted into a predetermined value F _b of the compressor frequency using a characteristic diagram showing the relationship between the predetermined values of the compressor operating frequency.
Then, when the indoor load and the outside air temperature are the same, the high-pressure side pressure rises as the low-boiling-point refrigerant composition ratio of the circulating refrigerant increases, and the operating frequency of the compressor 2 falls below a predetermined value, and When the low-boiling-point refrigerant composition ratio of the circulating refrigerant becomes low, the high-pressure side pressure decreases, and the operating frequency of the compressor 2 is determined to be higher than a predetermined value. by using the difference, a characteristic diagram showing the relationship of the low boiling point refrigerant composition ratio of the circulating refrigerant, the difference between the predetermined value F _b of the compressor operation frequency and the compressor operation frequency F _a, a low boiling point refrigerant composition ratio X of the circulated refrigerant Calculate to. In step 25, the liquid pipe temperature detection sensor 13 detects the liquid pipe temperature T _a.

Then, in step 26, the supercooling degree calculating means 25 causes the circulating refrigerant composition ratio predicting means 21 to predict the low boiling point refrigerant composition ratio X of the circulating refrigerant and the high pressure side sensor 12.
Liquid saturation temperature T but which is calculated from the high side pressure P _a of detecting
and _b, and the difference between the liquid pipe temperature T _a, is calculated as a degree of supercooling SC. In step 27, the outdoor expansion valve control means 17
The outdoor expansion valve 5 is controlled to an opening degree according to the calculated supercooling degree SC.

According to the third embodiment, the accumulator is used during the heating operation when a non-azeotropic mixed refrigerant (for example, two kinds of mixed refrigerant of R134a which is a high boiling point refrigerant and R32 which is a low boiling point refrigerant) is used. The composition of the circulating refrigerant composition is such that the high pressure side pressure is controlled to a constant value by changing the operating frequency of the compressor without complicating the production process by mounting the liquid level sensor on the Even in an air conditioner in which changes in pressure do not appear as changes in high-pressure side pressure,
By predicting the composition ratio of the circulating refrigerant and accurately calculating the liquid saturation temperature, the calculation accuracy of the degree of supercooling of the outdoor expansion valve inlet is improved, and the opening degree of the outdoor expansion valve 5 is controlled to an appropriate opening degree. be able to. Therefore, the risk of damage to the compressor 2 due to the liquid compression for returning the liquid to the compressor 2 can be avoided.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
~ It demonstrates using FIG. In FIG. 12, reference numeral 14 is an outside air temperature detection sensor that detects the outside air temperature. Also,
A discharge temperature detection sensor 24 detects the discharge temperature of the compressor 2. Further, 23 is the outside air temperature detected by the outside air temperature detection sensor 14, and the high pressure side pressure detection sensor 1
High-side pressure detected by 2 and discharge temperature detection sensor 24
Is a circulating refrigerant composition ratio predicting means for predicting the composition ratio of the circulating refrigerant from the discharge temperature of the compressor 2 detected by.

Here, the supercooling degree calculation means 25, the composition ratio of the circulating refrigerant predicted by the refrigerant composition ratio prediction means 23, the high pressure side pressure detected by the high pressure side pressure detection sensor 12 during the heating operation, and the liquid piping Temperature sensor 1
The outdoor expansion valve inlet supercooling degree is calculated based on the liquid pipe temperature detected by 3, and the outdoor expansion valve control means 1
Reference numeral 7 controls the opening degree of the outdoor expansion valve 5 according to the degree of supercooling calculated by the degree of supercooling calculating means 25.

Next, the operation of the air conditioner thus configured during the heating operation, which is a problem, will be described. The same components as those of the conventional example are designated by the same reference numerals,
Detailed description thereof will be omitted.

First, FIG. 13 is a flow chart of an air conditioner according to the fourth embodiment of the present invention, and FIG. 14 is a graph showing predetermined outside air temperature, high-pressure side pressure and compressor discharge temperature in the fourth embodiment of the present invention. FIG. 16 is a characteristic diagram showing a relationship between values, and FIG.
FIG. 9 is a characteristic diagram showing a relationship between a difference between a detected value of a compressor discharge temperature and a predetermined value and a low boiling point refrigerant composition ratio of a circulating refrigerant in a fourth example of the present invention.

From FIG. 13, first, in step 31, the high pressure side pressure detection sensor 12 detects the high pressure side pressure P _a . In step 32, the discharge temperature detection sensor 24 detects the discharge temperature T _d of the compressor 2. In step 33,
The outside air temperature detection sensor 14 detects the outside air temperature _Tc .

Next, in step 34, the circulating refrigerant composition ratio prediction means 23, and the outside air temperature T _c of the outside air temperature detecting sensor 14 has detected, and the high-pressure side pressure P _a of the high pressure side sensor 12 has detected, the compressor 2 The discharge temperature T _d of the compressor 2 is determined by using the characteristic diagram showing the relationship between the outside air temperature, the high-pressure side pressure, and the predetermined value of the compressor discharge temperature shown in FIG.
Convert to _e . Then, when the outside air temperature and the high-pressure side pressure are the same, when the low boiling point refrigerant composition ratio of the circulating refrigerant becomes high, the gas saturation temperature lowers, and the discharge temperature of the compressor 2 lowers. When the low-boiling point refrigerant composition ratio becomes low, the gas saturation temperature rises, and the discharge temperature of the compressor rises. The difference between the detected compressor discharge temperature and the predetermined value shown in FIG. Using the characteristic diagram showing the relationship of the low boiling point refrigerant composition ratio, the difference between the compressor discharge temperature T _d detected by the discharge temperature detection sensor 24 and the predetermined value T _e of the compressor discharge temperature is calculated as the low boiling point refrigerant of the circulating refrigerant. The composition ratio X is calculated. In step 35, the liquid pipe temperature detection sensor 13 detects the liquid pipe temperature T _a.

Then, in step 36, the supercooling degree computing means 25 causes the circulating refrigerant composition ratio predicting means 23 to predict the low boiling point refrigerant composition ratio X of the circulating refrigerant and the high pressure side sensor 12.
Liquid saturation temperature T but which is calculated from the high side pressure P _a of detecting
and _b, and the difference between the liquid pipe temperature T _a, is calculated as a degree of supercooling SC. In step 37, the outdoor expansion valve control means 17
The outdoor expansion valve 5 is controlled to an opening degree according to the calculated supercooling degree SC.

According to the fourth embodiment, the accumulator is used during the heating operation when the non-azeotropic mixed refrigerant (for example, two kinds of mixed refrigerant of R134a which is a high boiling point refrigerant and R32 which is a low boiling point refrigerant) is used. The composition ratio of the circulating refrigerant does not increase the complexity of the production process due to the installation of the liquid level sensor on the inside, and does not increase the construction man-hours for the wiring equipment that communicates the indoor load to the outdoor unit. Of the outdoor expansion valve 5 by predicting the
It is possible to improve the calculation accuracy of the inlet supercooling degree and control the opening degree of the outdoor expansion valve 5 to an appropriate opening degree. Therefore, the risk of damage to the compressor 2 due to the liquid compression for returning the liquid to the compressor 2 can be avoided.

[0051]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the circulation refrigerant composition ratio prediction for predicting the composition ratio of the circulation refrigerant from the height of the liquid level in the accumulator during the heating operation when the non-azeotropic mixed refrigerant is used Means, the composition ratio of the circulating refrigerant, the high-pressure side pressure, and the liquid pipe temperature, the supercooling degree calculating means for calculating the outdoor expansion valve inlet supercooling degree, and the outdoor expansion valve according to the subcooling degree. The outdoor expansion valve control means for controlling the opening is provided.

Therefore, by predicting the composition ratio of the circulating refrigerant,
By accurately calculating the liquid saturation temperature, the calculation accuracy of the outdoor expansion valve inlet supercooling degree is improved, and by controlling the opening of the outdoor expansion valve to an appropriate opening, the liquid return to the compressor can be controlled. It is possible to avoid the risk of damage to the compressor due to the liquid compression.

Further, during the heating operation when the non-azeotropic mixed refrigerant is used, the circulating refrigerant composition ratio predicting means for predicting the composition ratio of the circulating refrigerant from the indoor load, the outside air temperature and the high pressure side pressure, and the circulating refrigerant. The composition ratio, the pressure on the high pressure side, and the liquid pipe temperature, and the supercooling degree calculating means for calculating the degree of supercooling at the inlet of the outdoor expansion valve, and the degree of opening of the outdoor expansion valve according to the degree of supercooling The outdoor expansion valve control means is provided.

Therefore, the composition ratio of the circulating refrigerant is predicted and the liquid saturation temperature is calculated with high accuracy without complicating the production process by mounting the liquid level sensor on the accumulator. By improving the calculation accuracy of the inlet supercooling degree and controlling the opening of the outdoor expansion valve to an appropriate opening, the risk of damaging the compressor due to liquid compression for liquid return to the compressor is avoided. be able to.

Further, during heating operation when a non-azeotropic mixed refrigerant is used, the circulation rate for predicting the composition ratio of the circulating refrigerant is predicted from the indoor load, the outside air temperature, and the operating frequency of the compressor controlled by the high-pressure side pressure. Refrigerant composition ratio predicting means, composition ratio of circulating refrigerant, high-pressure side pressure, and liquid pipe temperature, supercooling degree calculating means for calculating the outdoor expansion valve inlet supercooling degree, and chamber depending on the supercooling degree. The outdoor expansion valve control means for controlling the opening of the outer expansion valve is provided.

Therefore, the construction is such that the production process is not complicated by mounting the liquid level sensor on the accumulator, and the operating frequency of the compressor is changed to control the high pressure side to a constant value. Even in an air conditioner in which the change in the composition ratio of the circulating refrigerant does not appear as a change in the high-pressure side pressure, the composition ratio of the circulating refrigerant is predicted and the liquid saturation temperature is accurately calculated, so that the outside expansion valve inlet Avoiding the risk of damage to the compressor due to liquid compression for liquid return to the compressor by improving the calculation accuracy of the supercooling degree and controlling the opening of the outdoor expansion valve to an appropriate opening. You can It is possible to avoid the risk that liquid compression occurs due to liquid return to the compressor, and as a result, the compressor is damaged.

Further, during the heating operation when the non-azeotropic mixed refrigerant is used, a circulating refrigerant composition ratio predicting means for predicting the composition ratio of the circulating refrigerant from the high pressure side pressure, the outside air temperature, and the discharge temperature of the compressor. , A composition ratio of the circulating refrigerant, a pressure on the high pressure side, and a liquid pipe temperature, a supercooling degree calculating means for calculating an inlet supercooling degree of the outdoor expansion valve, and an opening degree of the outdoor expansion valve according to the supercooling degree. The outdoor expansion valve control means for controlling the above is provided.

Therefore, the production process is not complicated by mounting the liquid level sensor on the accumulator, and the number of construction steps for wiring equipment for communicating the indoor unit load to the outdoor unit is not increased. In addition, by predicting the composition ratio of the circulating refrigerant and accurately calculating the liquid saturation temperature, the calculation accuracy of the outdoor expansion valve inlet supercooling degree is improved,
By controlling the opening of the outdoor expansion valve to an appropriate opening,
The risk of damage to the compressor due to liquid compression for liquid return to the compressor can be avoided.

[Brief description of drawings]

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

FIG. 2 is a flowchart of the air conditioner according to the first embodiment of the present invention.

FIG. 3 is a characteristic diagram showing the relationship between the liquid level height of the accumulator and the low boiling point refrigerant composition ratio of the circulating refrigerant in the first embodiment of the present invention.

FIG. 4 is a refrigeration cycle diagram of an air conditioner according to a second embodiment of the present invention.

FIG. 5 is a flowchart of the air conditioner according to the second embodiment of the present invention.

FIG. 6 is a characteristic diagram showing the relationship between the indoor load, the outside air temperature, and the predetermined value of the high-pressure side pressure in the second embodiment of the present invention.

FIG. 7 is a characteristic diagram showing the relationship between the difference between the detected value and the predetermined value of the high pressure side and the low boiling point refrigerant composition ratio of the circulating refrigerant in the second embodiment of the present invention.

FIG. 8 is a refrigeration cycle diagram of an air conditioner according to a third embodiment of the present invention.

FIG. 9 is a flowchart of an air conditioner according to a third embodiment of the present invention.

FIG. 10 is a characteristic diagram showing a relationship among a predetermined value of an indoor load, an outside air temperature, and a compressor operating frequency in the third embodiment of the present invention.

FIG. 11 is a characteristic diagram showing the relationship between the difference between the compressor operating frequency and a predetermined value and the low boiling point refrigerant composition ratio of the circulating refrigerant in the third embodiment of the present invention.

FIG. 12 is a refrigeration cycle diagram of an air conditioner according to a fourth embodiment of the present invention.

FIG. 13 is a flowchart of the air conditioner according to the fourth embodiment of the present invention.

FIG. 14 is a characteristic diagram showing the relationship between the high-pressure side pressure and a predetermined value of the discharge temperature of the compressor in the fourth embodiment of the present invention.

FIG. 15 is a characteristic diagram showing a relationship between a difference between a detected value of a compressor discharge temperature and a predetermined value and a low boiling point refrigerant composition ratio of a circulating refrigerant in a fourth example of the present invention.

FIG. 16 is a refrigeration cycle diagram of a conventional air conditioner

[Explanation of symbols]

 1 Outdoor unit 2 Compressor 3 Four-way valve 4 Outdoor heat exchanger 5 Outdoor expansion valve 6 Accumulator 7 Indoor unit 8 Indoor expansion valve 9 Indoor heat exchanger 12 High pressure side pressure sensor 13 Liquid pipe temperature detection sensor 14 Outdoor air Temperature detection sensor 16 Indoor load detection means 17 Outdoor expansion valve control means 18 Liquid level height detection sensor 19 Circulating refrigerant composition ratio predicting means 20 Circulating refrigerant composition ratio predicting means 21 Circulating refrigerant composition ratio predicting means 22 Compressor operating frequency control means 23 Circulating refrigerant composition ratio prediction means 24 Discharge temperature detection sensor 25 Supercooling degree calculation means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Michi Kusaka Matsushita Refrigerating Machinery Co., Ltd.

Claims (4)

[Claims] 1. An outdoor unit including a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion valve, and an accumulator using a non-azeotropic mixed refrigerant, and an indoor expansion valve and an indoor heat exchanger. An annular refrigerant circuit is formed by connecting the indoor unit, and a liquid level detection sensor for detecting the height of the liquid level in the accumulator, and the liquid in the accumulator detected by the liquid level detection sensor. Circulating refrigerant composition ratio predicting means for predicting the composition ratio of the circulating refrigerant from the surface height, a high pressure side pressure detecting sensor for detecting the high pressure side pressure, a liquid pipe temperature detecting sensor for detecting the liquid pipe temperature, and a heating operation. The composition ratio of the circulating refrigerant predicted by the circulating refrigerant composition ratio predicting means, the high pressure side pressure detected by the high pressure side pressure detection sensor, and the liquid distribution detected by the liquid pipe temperature detection sensor. A supercooling degree calculating means for calculating an outdoor expansion valve inlet supercooling degree based on a pipe temperature, and a control of the opening degree of the outdoor expansion valve according to the supercooling degree calculated by the supercooling degree calculating means. An air conditioner equipped with an outdoor expansion valve control means. 2. An outdoor unit including a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion valve, and an accumulator, which uses a non-azeotropic mixed refrigerant, and an indoor expansion valve and an indoor heat exchanger. An annular refrigerant circuit is formed by connecting the indoor unit, a high pressure side pressure detection sensor that detects the high pressure side pressure, an outside air temperature detection sensor that detects the outside air temperature, and an indoor load detection means that detects the indoor load, An indoor load detected by the indoor load detection means, an outside air temperature detected by the outside air temperature detection sensor, and a high pressure side pressure detected by the high pressure side pressure detection sensor, a circulating refrigerant composition ratio for predicting a composition ratio of the circulating refrigerant. Predicting means, liquid pipe temperature detection sensor for detecting the liquid pipe temperature, during heating operation, the composition ratio of the circulating refrigerant predicted by the circulating refrigerant composition ratio predicting means, the high Supercooling degree calculating means for calculating the outdoor expansion valve inlet supercooling degree by the high pressure side pressure detected by the pressure side pressure detection sensor and the liquid pipe temperature detected by the liquid pipe temperature detection sensor, and the supercooling degree calculation An air conditioner comprising an outdoor expansion valve control means for controlling the opening of the outdoor expansion valve according to the degree of supercooling calculated by the means. 3. An outdoor unit including a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion valve, and an accumulator, which uses a non-azeotropic mixed refrigerant, and an indoor expansion valve and an indoor heat exchanger. An annular refrigerant circuit is formed by connecting the indoor unit, and a high pressure side pressure detection sensor that detects the high pressure side pressure, an outside air temperature detection sensor that detects the outside air temperature, and a high pressure detected by the high pressure side pressure detection sensor. Compressor operating frequency control means for controlling the operating frequency of the compressor by side pressure, indoor load detecting means for detecting indoor load, indoor load detected by the indoor load detecting means, and detection by the outside air temperature detection sensor Circulating refrigerant composition ratio predicting means for predicting the composition ratio of the circulating refrigerant from the outside air temperature and the operating frequency of the compressor, and a liquid pipe temperature detecting sensor for detecting the liquid pipe temperature. During heating operation, the composition ratio of the circulating refrigerant predicted by the circulating refrigerant composition ratio predicting means, the high pressure side pressure detected by the high pressure side pressure detection sensor, and the liquid pipe temperature detected by the liquid pipe temperature detection sensor. According to the subcooling degree calculating means for calculating the outdoor side expansion valve inlet supercooling degree, and the outdoor side for controlling the opening degree of the outdoor side expansion valve according to the subcooling degree calculated by the subcooling degree calculating means. An air conditioner equipped with expansion valve control means. 4. An outdoor unit including a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion valve, and an accumulator, which uses a non-azeotropic mixed refrigerant, and an indoor expansion valve and an indoor heat exchanger. A high pressure side pressure detection sensor that detects the high pressure side pressure, a discharge temperature detection sensor that detects the discharge temperature of the compressor, and an outside air temperature that detects the outside air temperature constitute an annular refrigerant circuit by connecting the indoor unit. From the detection sensor, the outside air temperature detected by the outside air temperature detection sensor, the high pressure side pressure detected by the high pressure side pressure detection sensor, and the discharge temperature of the compressor detected by the discharge temperature detection sensor, the composition of the circulating refrigerant. Circulating refrigerant composition ratio predicting means for predicting ratio, liquid pipe temperature detecting sensor for detecting liquid pipe temperature, and predicting by the circulating refrigerant composition ratio predicting means during heating operation Supercooling that calculates the degree of subcooling of the outdoor expansion valve inlet based on the composition ratio of the circulating refrigerant, the high-pressure side pressure detected by the high-pressure side pressure detection sensor, and the liquid pipe temperature detected by the liquid pipe temperature detection sensor And an outdoor side expansion valve control means for controlling the opening degree of the outdoor side expansion valve according to the degree of supercooling calculated by the degree of supercooling calculation means.