JPH09280681A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the degree of indoor heat exchange outlet supercooling upon heating operation with a simplified construction, and ensure highly effectual heating operation whatever installation conditions are by calculating as the degree of indoor heat exchange outlet supercooling a value obtained by subtracting liquid refrigerant temperature from saturation temperature corresponding to pressure yielded by subtracting pressure loss from discharge pressure. SOLUTION: A refrigerant circuit 33 is constructed by connecting through piping an outdoor unit 21 including a compressor 22 and an outdoor heat exchanger 24 and a plurality of indoor units each including indoor heat exchangers 29 (29a to 29d) and indoor expansion valves 28a to 28d, etc. Further, a discharge pressure sensor 34 and liquid refrigerant temperature sensors 35a to 35d are provided, and refrigerant pressure loss from the neighbourhood of the compressor 22 to the neighbourhood of the indoor heat exchanger 29 is estimated in a pressure loss estimation unit 37, and further saturation temperature corresponding to pressure yielded by subtracting pressure loss from the discharge pressure is estimated in a corrected saturation temperature estimation unit 38. A value obtained by subtracting liquid refrigerant temperature from the corrected saturation temperature is estimated by a corrected degree-of- supercooling estimation unit 39 as the degree of indoor heat exchange outlet supercooling, and the degree of opening of the indoor expansion valve is controlled such that the degree of supercooling falls within a substantially predetermined range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an air conditioner, and more particularly to an air conditioner capable of controlling the degree of subcooling during heating operation.

[0002]

2. Description of the Related Art Various proposals have been made for a conventional air conditioner. Among them, a conventional example having a plurality of indoor units will be described with reference to FIG.

An outdoor unit 1 of the air conditioner is composed of a compressor 2, a four-way valve 3, an outdoor heat exchanger 4, an outdoor expansion valve 5, and an outdoor fan 6.

[0004] 7a, 7b, 7c, 7d are indoor units,
Indoor expansion valves 8a, 8b, 8c, 8d, indoor heat exchangers 9a, 9b, 9c, 9d, indoor fans 10a, 10 respectively
b, 10c and 10d.

Then, the outdoor unit 1 and the indoor units 7a, 7
b, 7c, 7d are connected in a ring shape by a liquid pipe 11 and a gas pipe 12, and constitute a refrigerant circuit 13.

Reference numeral 14 denotes a discharge pressure sensor for detecting the discharge pressure of the compressor 2, 15a, 15b, 15c, 15d.
Is a temperature sensor for detecting the liquid-side refrigerant temperature of each indoor heat exchanger. Reference numeral 16 denotes a saturation temperature calculator that calculates a saturation temperature corresponding to the pressure from the pressure value detected by the discharge pressure sensor. Further, 17 is the saturation temperature calculated by the saturation temperature calculator 16 and the temperature sensors 15a, 15b, 1
Each indoor heat exchanger 9 is determined based on the refrigerant temperature detected in 5c and 15d.
This is a supercooling degree calculator that calculates the degree of supercooling of a, 9b, 9c, and 9d. Further, reference numeral 18 compares the degree of supercooling output from the degree of supercooling calculator 17 with a preset degree of supercooling, and determines whether the indoor expansion valves 8a, 8b, 8c, and 8d.
Is an expansion valve controller for opening and closing.

Next, the operation of the multi-room air conditioner having the above configuration will be described.

During the heating operation, the high-temperature high-pressure gas compressed by the compressor 2 is passed through the four-way valve 3 to the indoor fans 10a, 10a.
Air sent by b, 10c, 10d and indoor heat exchanger 9
a, 9b, 9c, 9d heat-condenses and condenses to become a high-temperature high-pressure liquid refrigerant, which is decompressed by the indoor expansion valves 8a, 8b, 8c, 8d and further decompressed by the outdoor expansion valve 5 to perform outdoor heat exchange. It vaporizes in the vessel 4 to become a low temperature and low pressure gas, and returns to the compressor 2 again via the four-way valve 3.

Further, when one of the indoor units is in a stopped state (for example, the indoor unit 7a), the indoor expansion valve thereof is slightly opened (for example, the indoor expansion valve 8a is slightly opened), and almost no refrigerant is contained in the stopped indoor unit. Is driven so that it does not flow.

The indoor expansion valve control during the heating operation is performed as follows. In order to operate the cycle efficiently, it is necessary to set the degree of supercooling at the outlet of the indoor heat exchangers 9a, 9b, 9c, 9d to an appropriate value.
The saturation temperature is calculated by the saturation temperature calculator 16 from the pressure detected by the discharge pressure sensor 14.

Further, the temperature sensors 15a, 15b, 1
Each indoor heat exchanger 9a, 9b, 9 detected by 5c, 15d
From the difference between the outlet temperatures of c and 9d and the saturation temperature calculated by the saturation temperature calculator 16, the supercooling degree of each of the indoor heat exchangers 9a, 9b, 9c and 9d is calculated using the supercooling degree calculator 17. calculate.

Also, using the expansion valve controller 18,
The degree of supercooling from the degree of supercooling calculator 17 is compared with a preset degree of supercooling, and when the degree of supercooling is large, the indoor expansion valves 8a, 8b, 8c, 8d are operated in the opening direction, When the degree of subcooling is small, the indoor expansion valves 8a, 8b,
By operating 8c and 8d in the closing direction, the operation is performed with the degree of supercooling at the outlet of the indoor heat exchangers 9a, 9b, 9c and 9d controlled to an appropriate value.

By doing so, the discharge pressure sensor 1
4 and each indoor heat exchanger 9a, 9b, 9
The supercooling degree at the outlets c and 9d is controlled to an appropriate value to perform an efficient operation.

On the other hand, during the cooling operation, the high-temperature high-pressure gas compressed by the compressor 2 is condensed in the outdoor heat exchanger 4 via the four-way valve 3 to become a high-pressure liquid refrigerant, and the indoor expansion valve 5 is opened. Air decompressed by the expansion valves 8a, 8b, 8c, 8d and exchanged with the air sent by the indoor fans 10a, 10b, 10c, 10d by the indoor heat exchangers 9a, 9b, 9c, 9d, and evaporated.
It becomes low-temperature low-pressure gas, and returns to the compressor 2 again via the four-way valve 3. At this time, if any of the indoor units is in the stopped state (for example, the indoor unit 7a), the indoor expansion valve is closed (for example, the indoor expansion valve 8a is closed), and the refrigerant does not flow to the stopped indoor unit. Be driven.

In the cooling operation, the indoor expansion valves 8a, 8b, 8 are provided in order to operate as efficiently as in the heating operation.
Control of c and 8d is required, but the details are omitted here.

[0016]

In these air conditioners, the length of the connecting pipe connecting the outdoor unit and the indoor unit varies greatly depending on the structure of the building in which the equipment is installed. In reality, it is not unusual for long ones to be longer than 100m.

Also, due to the restrictions on the location of equipment installed in high-rise buildings in recent years, there are various types such as outdoor units installed on the rooftop, ground units, and verandas on the middle floor.

On the other hand, an inexpensive and highly efficient system is required for the air conditioner, and it is necessary to accurately detect the degree of superheat or the degree of subcooling of the heat exchanger in order to perform highly efficient operation. Become. However, from the viewpoint of the price of the product, it has been a conflicting direction that it is desirable that detection means such as a pressure sensor and a temperature sensor be not used as much as possible.

In the conventional air conditioner, when the degree of subcooling at the outlet of the indoor heat exchanger is detected during heating operation, the saturation temperature is calculated from the pressure detected by the discharge pressure sensor provided at the outlet of the compressor. However, since the degree of supercooling was calculated from the temperature difference from the outlet temperature of the indoor heat exchanger, the pressure loss between the compressor and the indoor heat exchanger cannot be taken into consideration, and therefore the degree of supercooling cannot be accurately detected. Not only that, in these various installation situations, the detected value and the true value of the degree of supercooling often differ greatly, so that the degree of supercooling did not reach an appropriate value and the performance deteriorated. .

In order to prevent this, some indoor units are provided with a pressure sensor, but the pressure sensor is expensive, and it is difficult to satisfy the demand for an air conditioner that is inexpensive and highly efficient. Met.

The present invention is intended to solve the problems of the conventional air conditioner, and how to accurately detect the degree of subcooling at the outlet of the indoor heat exchanger during the heating operation with a simple structure. It is an object of the present invention to provide an air conditioner capable of highly efficient heating operation even under various installation conditions.

[0022]

An air conditioner according to the present invention includes an outdoor unit having a driven compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion valve, and the like, and an indoor heat exchanger, A discharge pressure detecting means for detecting a discharge pressure of the compressor and a refrigerant circuit by connecting at least one indoor unit having an indoor expansion valve or the like as a constituent element with a connecting pipe, and the indoor heat exchanger. Liquid refrigerant temperature detecting means for detecting the liquid refrigerant temperature, pressure loss calculating means for calculating the refrigerant pressure loss between the vicinity of the compressor and the indoor heat exchanger, and saturation equivalent to the pressure obtained by subtracting the pressure loss from the discharge pressure. A value obtained by subtracting the temperature detected by the liquid refrigerant temperature detection means from the saturation temperature calculated by the correction saturation temperature calculation means is provided as the indoor heat exchange outlet supercooling degree. Calculation A correction supercooling degree calculating unit that, the is characterized in that the degree of supercooling with an inflation valve controller for controlling the indoor expansion valve to a value substantially constant range.

The air conditioner according to the present invention is also
An outdoor unit that has a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion valve, etc. as its constituent elements and one or more indoor units that have an indoor heat exchanger, an indoor expansion valve, etc. as its constituent elements are connected by connecting piping. A refrigerant circuit is configured to provide a pipe length range switch capable of stepwise switching a set value according to the pipe length range of the connection pipe, and further a discharge pressure detection means for detecting the discharge pressure of the compressor. , An operating frequency detecting means for detecting the operating frequency of the compressor, a liquid refrigerant temperature detecting means for detecting the liquid refrigerant temperature of the indoor heat exchanger, a value of the operating frequency and a set value of the pipe length range switch Pressure loss calculation means for calculating the refrigerant pressure loss between the vicinity of the compressor and the vicinity of the indoor heat exchanger using the correction saturation temperature calculation for calculating the saturation temperature corresponding to the pressure obtained by subtracting the pressure loss from the discharge pressure. A correction supercooling degree calculating means for calculating a value obtained by subtracting a temperature detected by the liquid refrigerant temperature detecting means from a saturation temperature calculated by the correction saturation temperature calculating means as the indoor heat exchange outlet supercooling degree And an expansion valve controller that controls the opening degree of the indoor expansion valve so that the degree of supercooling becomes a value in a substantially constant range.

Furthermore, the air conditioner according to the present invention also comprises an outdoor unit having a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion valve and the like as components, an indoor heat exchanger, an indoor expansion valve and the like. A refrigerant circuit is configured by connecting one or more indoor units as elements with a connecting pipe, and a pipe length setting switch capable of setting a set value according to the pipe length of the connecting pipe is provided, and the compression circuit is further provided. Discharge pressure detecting means for detecting the discharge pressure of the machine, operating frequency detecting means for detecting the operating frequency of the compressor, liquid refrigerant temperature detecting means for detecting the liquid refrigerant temperature of the indoor heat exchanger, and the operating frequency Value and the set value of the pipe length setting switch, the pressure loss calculating means for calculating the refrigerant pressure loss between the vicinity of the compressor and the vicinity of the indoor heat exchanger, and the pressure obtained by subtracting the pressure loss from the discharge pressure. Corrected saturation temperature calculation means for calculating the saturation temperature is provided, and a value obtained by subtracting the temperature detected by the liquid refrigerant temperature detection means from the saturation temperature calculated by the corrected saturation temperature calculation means is used as the indoor heat exchange outlet temperature. A correction subcooling degree calculating means for calculating as a cooling degree, and an expansion valve controller for controlling the indoor expansion valve opening degree so that the subcooling degree has a value in a substantially constant range are provided. Is.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 shows the first aspect of the present invention.
2 is an embodiment of the air conditioner described in (2) and (2) above, showing a schematic circuit diagram of a refrigerating cycle, and particularly in the heating operation which is the main object of the present invention.

Reference numeral 21 is an outdoor unit of the air conditioner,
It is composed of a compressor 22, a four-way valve 23, an outdoor heat exchanger 24, an outdoor expansion valve 25, and an outdoor fan 26.

27a, 27b, 27c, 27d are indoor units, and indoor expansion valves 28a, 28b, 28c,
28d, indoor heat exchangers 29a, 29b, 29c, 29
d, indoor fans 30a, 30b, 30c, 30d.

The outdoor unit 21 and the indoor unit 27
a, 27b, 27c, 27d are connected in a ring by connecting pipes (liquid pipe 31 and gas pipe 32) to form a refrigerant circuit 33, and the refrigeration cycle and the flow of the refrigerant are the same as in the conventional example.

Further, 34 is a discharge pressure sensor for detecting the discharge pressure of the compressor 22, and 35a, 35b, 35c, 35.
Reference numeral d is a temperature sensor that detects the liquid-side refrigerant temperature of each indoor heat exchanger, and 36 is a frequency sensor that detects the operating frequency of the compressor 22.

Further, reference numeral 37 indicates from the value of the frequency detected by the frequency sensor 36 that the compressor 22 and the indoor heat exchanger 29a,
A pressure loss calculator for calculating the pressure loss between 29b, 29c, and 29d, and 38 is a correction for subtracting the discharge pressure detected by the discharge pressure sensor 34 and the pressure loss found by the pressure loss calculator 37 to calculate a saturation temperature corresponding to the pressure. It is a saturation temperature calculator.

Further, 39 is the saturation temperature calculated by the correction saturation temperature calculator 38 and the temperature sensors 35a, 35b, 3
5c and 35d, each indoor heat exchanger 2
This is a corrected supercooling degree calculator that calculates the supercooling degrees of 9a, 29b, 29c, and 29d.

Furthermore, 40 is a corrected supercooling degree calculator 3
The supercooling degree output from 9 is compared with the preset supercooling degree, and the indoor expansion valves 28a, 28b, 2
An expansion valve controller that opens and closes 8c and 28d.

Next, the operation of the air conditioner configured as described above will be described focusing on heating.

During the heating operation, the high-temperature high-pressure gas compressed by the compressor 22 passes through the four-way valve 23 and the indoor fans 30a, 3
Air sent by 0b, 30c, 30d and indoor heat exchanger 2
9a, 29b, 29c, and 29d exchange heat to condense and become a high-temperature high-pressure liquid refrigerant, and the indoor expansion valves 28a, 28b,
It is decompressed by 28c and 28d, decompressed by the outdoor expansion valve 25, evaporated in the outdoor heat exchanger 24 to become a low-temperature low-pressure gas, and returns to the compressor 22 again via the four-way valve 23.

When any of the indoor units is in a stopped state (for example, the indoor unit 27a), the indoor expansion valve thereof is slightly opened (for example, the indoor expansion valve 28a is slightly opened), and almost no refrigerant is contained in the stopped indoor unit. Is driven so that it does not flow.

Next, the indoor expansion valve control during the heating operation is performed as follows.

In order to operate the heating cycle efficiently, it is necessary to set the subcooling degree at the outlets of the indoor heat exchangers 29a, 29b, 29c, 29d to an appropriate value. For that purpose, first, the discharge pressure sensor 34 is used. The discharge pressure (Pd) is detected. Next, the pressure loss calculator 37 causes the pressure loss between the compressor 22 and the indoor heat exchangers 29a, 29b, 29c, 29d.
(ΔP) is calculated as a function of the operating frequency (f) of the compressor detected by the frequency sensor 36, for example, by the following equation.

[0039]

## EQU1 ## ΔP = A × (f) + B A and B are constants, where the compressor 22 to the indoor heat exchangers 29a and 2
It is well known that the state of the refrigerant between the inlets 9b, 29c, 29d is a gas single-phase flow because it is the discharge gas of the compressor 22, and the pressure loss in this case is largely related to the refrigerant circulation amount.

It is also known that the refrigerant circulation amount has a great influence on the compressor operating frequency. Therefore, by making the pressure loss a function of the compressor 22 as in the above equation, the compressor 22 is connected to the indoor heat exchanger 29a. , 29b, 29c, 29d can be accurately estimated.

Next, the calculated pressure loss (ΔP) and discharge pressure (P
d) is input to the corrected saturation temperature calculator 38, and the outlet pressure (Ph) of the indoor heat exchangers 29a, 29b, 29c, 29d is calculated by the following equation.

[0042]

## EQU00002 ## Ph = Pd-.DELTA.P Here, the indoor heat exchangers 29a, 29b, 29
Although the gas side pressures of c and 29d are calculated, it has been confirmed that the pressure loss of the heat exchanger that serves as the condenser during heating is so small that it can be ignored, so in this case, the indoor heat exchanger is used. The gas side pressure (inlet) and the liquid side pressure (outlet) of 29a, 29b, 29c, and 29d can be treated as substantially equal.

Next, here, the saturated liquid temperature for a given pressure value is calculated at the same time, and the indoor heat exchangers 29a, 29 are
Saturated liquid temperature with respect to pressure (Ph) of b, 29c and 29d
(Tsat) can be calculated.

Further, each indoor heat exchanger 29a, 29b,
The liquid refrigerant temperatures (Th) of 29c and 29d are detected by the temperature sensors 35a, 35b, 35c and 35d, and are input to the corrected supercooling degree calculation means together with the saturated liquid temperature (Tsat).
The degree of supercooling (SC) of each indoor heat exchanger 29a, 29b, 29c, 29d is calculated by the following formula.

[0045]

## EQU3 ## SC = Tsat-Th Here, since the pressure loss is calculated accurately, the pressure (P
h), the accuracy of the saturated liquid temperature (Tsat) is also high, and the supercooling degree (SC) can also be calculated accurately.

Next, the data of the degree of supercooling is used for the expansion valve controller 4
In this case, a value of the degree of supercooling at which the refrigeration cycle can be efficiently operated is set and input in advance, and each of the indoor heat exchangers 29a, 29b, 29c, 29
Compared with the liquid refrigerant supercooling degree (d) of d, when the supercooling degree is large, the corresponding indoor expansion valve is operated in the opening direction, and conversely, when the supercooling degree is small, the corresponding indoor expansion valve is operated. By operating the expansion valve in the closing direction, the degree of supercooling of each indoor heat exchanger 29a, 29b, 29c, 29d is operated in a highly efficient state.

Thus, by calculating the pressure loss of the connecting pipe between the compressor 22 and each of the indoor heat exchangers 29a, 29b, 29c, 29d as a function of the operating frequency of the compressor 22, the indoor heat exchanger 29a. , 29b, 29c, 29d
Since it is possible to estimate the pressure close to the true value without measuring the actual pressure of, the degree of subcooling can be accurately corrected and calculated, and at any operating frequency state. The degree of supercooling that has been set can be controlled, and highly efficient operation is always possible.

It should be noted that the pressure loss (ΔP) by the pressure loss calculator 37 used here is not only a linear function of the operating frequency (f), but also higher-order expressions and constant values are included in the present invention. Needless to say.

In the present embodiment, no mention is made of the type of refrigerant, but the mainstream HCFC 22 for air conditioning is used.
The same effect can be obtained with the HFC refrigerant and the HFC mixed refrigerant, and these are also included in the present invention.

On the other hand, the description of the cooling operation is omitted because it is not the main purpose of the present invention.

(Embodiment 2) FIG. 2 shows claim 3 of the present invention.
2 is an embodiment of the air conditioner described in (4) and (4), and shows a schematic circuit diagram of a refrigerating cycle. Particularly, a heating operation, which is the main object of the present invention, will be mainly described.

Further, the configuration of the first embodiment shown in FIG.
The same operation is denoted by the same reference numeral, and the detailed description is omitted.

Here, the pipe length range switch 5 is capable of stepwise changing the set value (a) according to the pipe length range of the connection pipes (the liquid pipe 31 and the gas pipe 32).
0 and the outdoor unit 21 and the indoor unit 27a,
Height difference switch 5 capable of setting a set value (b) according to the relative positional relationship with 27b, 27c, 27d
1 are provided in the outdoor unit 1 respectively.

In the present embodiment, these set values are set as shown in the following table.

[0055]

[Table 1] These set values (a) and (b) are used as the discharge pressure sensor 3
Discharge pressure (Pd) data from 4 and frequency sensor 3
The operating frequency (f) data of the compressor detected in 6 is sent to the pressure loss calculator 37, and the compressor 22 sends the indoor heat exchanger 29.
The pressure loss (ΔP) between a, 29b, 29c and 29d is calculated, for example, by the following equation.

[0056]

[Expression 4] ΔP = a × (A × (f) + B) + b
It is needless to say that A and B are constants, that is, the pressure loss increases as the pipe length becomes longer, and thus, the set value (a) that can be corrected according to the pipe length range should be provided to have a relationship approximately proportional to the pressure loss. As a result, the accuracy of pressure loss is significantly improved.

Considering the refrigerant flow in the gas pipe 32 during the heating operation, the outdoor unit 21 is connected to the indoor unit 27a,
When it is relatively higher than 27b, 27c, and 27d, the gas refrigerant flows downward, and when it is below (upward flow).
Since the pressure loss in the connecting pipe becomes smaller than the influence of gravity, the correction can be performed by providing the set value (b) of the height difference switch 51, and the pressure loss can be calculated in consideration of gravity, so that the accuracy is further improved.

Next, the calculated pressure loss (ΔP) and discharge pressure (P
Since the process after inputting d) to the corrected saturation temperature calculator 38 is the same as that in the first embodiment, the description thereof is omitted here. By doing so, the pressure loss increases in accordance with the length of the connecting pipe, and the correction by the set value of the pipe length range switch is added, and the outdoor unit 21 and the indoor units 27a, 27b, 27c, 27
For the relative positional relationship of d, the height difference switch 51
The accuracy of the pressure loss (ΔP) is improved by adding the correction by, and each indoor heat exchanger 29a, 29b, 29c,
Since the pressure close to the true value of 29d can be calculated, the degree of supercooling can be accurately corrected and calculated, and the set subcooling can be obtained at any operating frequency, pipe connection, and outdoor unit position. It can be controlled every time and highly efficient operation is possible.

Here, similarly, the pressure loss (ΔP) by the used pressure loss calculator 37 is not only a linear function of the operating frequency (f), but also higher-order equations and constant values are applicable to the present invention. Needless to say, it is included.

Further, the set value (a) of the pipe length range switch 50 and the set value (b) of the height difference switch 51 are not limited to the set values as in the present embodiment, and more detailed divisions are possible. Yes, these are also included in the present invention.

Furthermore, although no mention is made of the type of the refrigerant in this embodiment, the mainstream HCF for air conditioning is used.
The effects are the same for C22, HFC refrigerant, and HFC mixed refrigerant, and these are also included in the present invention.

On the other hand, the description of the cooling operation is omitted because it is not the main purpose of the present invention.

(Embodiment 3) FIG. 3 shows claim 5 of the present invention.
2 is an embodiment of the air conditioner described in (4) and (6), and shows a schematic circuit diagram of a refrigerating cycle. Particularly, a description will be given focusing on a heating operation which is the main object of the present invention.

The configuration of the first embodiment shown in FIG.
The same operation is denoted by the same reference numeral, and the detailed description is omitted.

Here, the pipe length setting switch 60, the outdoor unit 21 and the indoor unit 27a, which can input the set value (c) according to the pipe length of the connecting pipes (the liquid pipe 31 and the gas pipe 32). , 27b, 27c,
Each outdoor unit 21 is provided with a height difference switch 61 capable of setting a set value (d) according to a relative positional relationship with 27d.

In the present embodiment, these set values are set as shown in the following table.

[0067]

[Table 2] These set values (c) and (d) are measured by the discharge pressure sensor 3
Discharge pressure (Pd) data from 4 and frequency sensor 3
The operating frequency (f) data of the compressor detected in 6 is sent to the pressure loss calculator 37, and the compressor 22 sends the indoor heat exchanger 29.
The pressure loss (ΔP) between a, 29b, 29c and 29d is calculated, for example, by the following equation.

[0068]

[Expression 5] ΔP = c × (A × (f) + B) + d
A and B are constants, that is, it is clear that the pressure loss increases as the pipe length becomes longer. Therefore, the set value (c) that can be corrected by the pipe length is provided, and the pressure loss has a relationship substantially proportional to the pressure loss. By doing so, the accuracy of pressure loss is further improved.

Considering the refrigerant flow in the gas pipe 32 during the heating operation, the outdoor unit 21 is connected to the indoor unit 27a,
When it is relatively higher than 27b, 27c, and 27d, the gas refrigerant flows downward, and when it is below (upward flow).
Since the pressure loss in the connecting pipe becomes smaller than the influence of gravity, the correction can be performed by providing the set value (b) of the height difference switch 51, and the pressure loss can be calculated in consideration of gravity, so that the accuracy is further improved.

Next, the calculated pressure loss (ΔP) and discharge pressure (P
Since the process after inputting d) to the corrected saturation temperature calculator 38 is the same as that in the first embodiment, the description thereof is omitted here. By doing so, the pressure loss increases according to the length of the connecting pipe, but the pressure loss (ΔP) is corrected by adding the correction by the set value of the pipe length switch that can input the pipe length itself. The accuracy of
Since it becomes possible to calculate the pressure close to the true value of each indoor heat exchanger 29a, 29b, 29c, 29d, the degree of subcooling can be accurately corrected and calculated. Even in connection, the degree of supercooling can be controlled and the highly efficient operation becomes possible.

Here, similarly, the pressure loss (ΔP) by the pressure loss calculator 37 used is not only a linear function of the operating frequency (f), but also higher-order equations and constant values are used in the present invention. Needless to say, it is included.

The set value of the pipe length switch 60 (c)
The set value (d) of the height difference switch 61 is not limited to the set value as in the present embodiment, and more detailed division is possible, and these are also included in the present invention.

Furthermore, although no mention is made of the type of refrigerant in this embodiment, the mainstream HCF for air conditioning is used.
The effects are the same for C22, HFC refrigerant, and HFC mixed refrigerant, and these are also included in the present invention.

On the other hand, the description of the cooling operation is omitted because it is not the main purpose of the present invention.

[0075]

As is apparent from the above description,
According to the air conditioner of the first and second aspects, it is possible to accurately estimate the pressure of the indoor heat exchanger from the value of the discharge pressure. Therefore, the subcooling degree can be corrected and accurately calculated. It is possible to control the indoor expansion valve to the set degree of supercooling in any operating frequency state, and it is possible to always operate with high efficiency.

Further, according to the air conditioner of the third and fourth aspects, the pressure loss increases according to the length of the connecting pipe, and the pressure is increased by the correction by the set value of the pipe length range switch. Since the accuracy of the loss (ΔP) is improved and the pressure close to the true value of each indoor heat exchanger can be calculated, the degree of supercooling can be accurately corrected and calculated. In addition, the indoor expansion valve can be controlled to the set supercooling degree even in the operating frequency and the pipe connection, and highly efficient operation can be performed.

Further, a height difference switch capable of setting a set value in accordance with the relative positional relationship between the outdoor unit and the indoor unit is provided, and the pressure loss calculating means is provided with the operating frequency detected by the operating frequency detecting means. By calculating the pressure loss between the vicinity of the compressor and the vicinity of the indoor heat exchanger using the value, the setting value of the pipe length range switch, and the setting value of the height difference switch, the pressure loss (Δ The accuracy of P) is improved, the indoor expansion valve can be accurately controlled to the set degree of supercooling, and highly efficient operation becomes possible.

According to the air conditioner of the fifth and sixth aspects, the set value of the pipe length switch capable of inputting the pipe length itself against the increase of the pressure loss according to the length of the connecting pipe. Since the accuracy of pressure loss (ΔP) is improved and the pressure close to the true value of each indoor heat exchanger can be calculated, the degree of supercooling is accurately corrected and calculated. Therefore, it is possible to control to a set degree of supercooling at any operating frequency and pipe connection, which enables highly efficient operation.

Also in this case, by providing the height difference switch, the accuracy of the pressure loss (ΔP) is further improved, and the indoor expansion valve can be accurately controlled to the set degree of supercooling, and high efficiency can be achieved. It is possible to perform various driving.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a schematic configuration of an air conditioner according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a schematic configuration of an air conditioner according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a schematic configuration of a conventional multi-room air conditioner.

[Explanation of symbols]

 21 outdoor unit 22 compressor 23 four-way valve 24 outdoor heat exchanger 25 outdoor expansion valve 26 outdoor fan 27a, 27b, 27c, 27d indoor unit check valve 28a, 28b, 28c, 28d indoor expansion valve 29a, 29b, 29c, 29d Indoor heat exchanger 30a, 30b, 30c, 30d Indoor fan 31 Liquid pipe 32 Gas pipe 33 Refrigerant circuit 34 Discharge pressure sensor 35a, 35b, 35c, 35d Temperature sensor 36 Frequency sensor 36. 37 Pressure loss calculator 38 Corrected saturation temperature calculator 39 Corrected supercooling degree calculator 40 Expansion valve controller 50 Pipe length range switch 51, 61 Height difference switch 60 Pipe length setting switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Kitayama 4-2-5 Takada Hondori, Higashi-Osaka City, Osaka Prefecture Matsushita Refrigerator Co., Ltd. (72) Inventor Takayuki Takaya 4-chome Takaidamoto-dori, Higashi Osaka No. 2-5 Matsushita Cold Machinery Co., Ltd.

Claims (6)

[Claims] 1. An outdoor unit having at least a compressor, a four-way valve, an outdoor heat exchanger, and an outdoor expansion valve as constituent elements, and at least one indoor unit having at least an indoor heat exchanger and indoor expansion valve as constituent elements. A connection pipe connecting the outdoor unit and the indoor unit, discharge pressure detection means for detecting the discharge pressure of the compressor, liquid refrigerant temperature detection means for detecting the liquid refrigerant temperature of the indoor heat exchanger, and the compression A pressure loss calculating means for calculating a refrigerant pressure loss between the vicinity of the machine and the indoor heat exchanger, a correction saturation temperature calculating means for calculating a saturation temperature corresponding to a pressure obtained by subtracting the pressure loss from the discharge pressure, and the correction saturation temperature. Corrected supercooling degree calculating means for calculating a value obtained by subtracting the temperature detected by the liquid refrigerant temperature detecting means from the saturation temperature calculated by the calculating means as the indoor heat exchange outlet supercooling degree, and the supercooling degree An air conditioner characterized by comprising an expander valve controller for controlling the indoor expansion valve to a value substantially constant range. 2. An operating frequency detecting means for detecting an operating frequency of the compressor, wherein the pressure loss calculating means uses the value of the operating frequency to provide a refrigerant between the vicinity of the compressor and the vicinity of the indoor heat exchanger. The air conditioner according to claim 1, wherein the pressure loss is calculated. 3. An outdoor unit having at least a compressor, a four-way valve, an outdoor heat exchanger and an outdoor expansion valve as constituent elements, and at least one indoor unit having at least an indoor heat exchanger and indoor expansion valve as constituent elements. A connection pipe connecting the outdoor unit and the indoor unit, a pipe length range switch capable of stepwise switching a set value according to a pipe length range of the connection pipe, and a discharge detecting a discharge pressure of the compressor. Pressure detecting means, operating frequency detecting means for detecting the operating frequency of the compressor, liquid refrigerant temperature detecting means for detecting the liquid refrigerant temperature of the indoor heat exchanger, value of the operating frequency and the pipe length range switch A pressure loss calculating means for calculating a refrigerant pressure loss between the vicinity of the compressor and the vicinity of the indoor heat exchanger using a set value of, and a saturation temperature equivalent to a pressure obtained by subtracting the pressure loss from the discharge pressure. A correction saturation temperature calculating means for calculating, and a correction temperature for calculating a value obtained by subtracting the temperature detected by the liquid refrigerant temperature detecting means from the saturation temperature calculated by the correction saturation temperature calculating means as the indoor heat exchange outlet supercooling degree. An air conditioner comprising: a cooling degree calculating means; and an expansion valve controller that controls the opening degree of the indoor expansion valve so that the supercooling degree has a value in a substantially constant range. 4. A height difference switch capable of setting a set value in accordance with a relative positional relationship between the outdoor unit and the indoor unit, wherein the pressure loss calculating means detects the operating frequency detecting means. The pressure loss between the vicinity of the compressor and the vicinity of the indoor heat exchanger is calculated using the value of the operating frequency, the set value of the pipe length range switch, and the set value of the height difference switch. Air conditioner described. 5. An outdoor unit having at least a compressor, a four-way valve, an outdoor heat exchanger and an outdoor expansion valve as constituent elements, and at least one indoor unit having at least an indoor heat exchanger and indoor expansion valve as constituent elements. A connection pipe connecting the outdoor unit and the indoor unit, a pipe length setting switch capable of setting a set value according to the pipe length of the connection pipe, and a discharge pressure detection means for detecting the discharge pressure of the compressor. An operating frequency detecting means for detecting an operating frequency of the compressor, a liquid refrigerant temperature detecting means for detecting a liquid refrigerant temperature of the indoor heat exchanger, a value of the operating frequency and a setting value of the pipe length setting switch. Using a pressure loss calculating means for calculating a refrigerant pressure loss between the vicinity of the compressor and the vicinity of the indoor heat exchanger, and a correction for calculating a saturation temperature corresponding to the pressure obtained by subtracting the pressure loss from the discharge pressure. Corrected supercooling degree calculation for calculating a value obtained by subtracting the temperature detected by the liquid refrigerant temperature detection means from the saturation temperature calculated by the sum temperature calculation means and the corrected saturation temperature calculation means as the indoor heat exchange outlet supercooling degree An air conditioner comprising: a means and an expansion valve controller that controls the opening degree of the indoor expansion valve such that the degree of subcooling is a value in a substantially constant range. 6. A height difference switch capable of setting a set value in accordance with a relative positional relationship between the outdoor unit and the indoor unit, wherein the pressure loss calculating means is detected by the operating frequency detecting means. The pressure loss between the vicinity of the compressor and the vicinity of the indoor heat exchanger is calculated using the value of the operating frequency, the setting value of the pipe length setting switch, and the setting value of the height difference switch. Air conditioner described.