JPH0670515B2 - Multi-room air conditioner - Google Patents

Description

The present invention relates to a multi-room air conditioner in which one outdoor unit is connected to a plurality of indoor units.

[Prior Art] As a conventional multi-room air conditioner of this type, for example, a multi-room air conditioner described in Japanese Utility Model Publication No. 55-28993 can be mentioned.

FIG. 11 is an overall configuration diagram of a conventional multi-room air conditioner known in the above publication.

In the figure, (1) is a compressor, (2) is a four-way switching valve which is a switching valve which is connected to the compressor (1) and switches the cooling or heating cycle, and (3) is one of these four-way switching valves. An outdoor heat exchanger connected to the switching valve (2) and connected in series to the expansion valve (23) and the receiver (25),
(4) is an accumulator connected between the compressor (1) and the four-way switching valve (2), and (24) is the expansion valve (23).
Is a check valve connected in parallel with, and constitutes the main circuit portion of the air conditioner.

Further, (7a) and (7b) are branched in parallel from the main circuit, and between the four-way switching valve (2) and the receiver (25),
A plurality of indoor heat exchangers, each of which is connected via a gas side solenoid valve (26a), (26b) and a liquid side solenoid valve (27a), (27b). ), (7b) between the liquid side solenoid valves (27a), (27b),
Expansion valves (29a) and (29b) and check valves (28a) and (28b) are connected in series in parallel circuits.

In the multi-room air conditioner according to the conventional example, the cooling operation is performed by the solid arrow by the switching operation of the four-way switching valve (2).
In the heating operation, the cooling is circulated as indicated by the dotted arrow.

As shown in FIG. 11, the conventional multi-room air conditioner of this type has indoor heat exchangers (7a), (7b), that is, a plurality of indoor units having expansion valves (29a) for cooling, (29b) is provided, but this is because even if the load of multiple indoor units is unbalanced during cooling operation, or the installed positional relationship of each indoor unit is not relatively even, Its main purpose is to supply quantity. However, during heating operation, there is no means for distributing an appropriate amount of refrigerant to a plurality of indoor units, and the circuit configuration is not always sufficient for a multi-room air conditioner.

In addition, during cooling operation, the expansion valves (29a) and (29b) are used to distribute the amount of refrigerant to each indoor unit, but there is no means to correct the influence of other indoor units, so there is no way of compensating for each other. Due to the influence of the machine, a hunting phenomenon is likely to occur in the distribution of the refrigerant amount, and the expansion valves (29a) and (29b) are superheated at the outlet of the indoor heat exchanger (hereinafter referred to as superheat).
However, if the superheat is controlled so as to be a constant value, the efficiency of the indoor heat exchanger decreases, and the cooling capacity tends to decrease.

That is, this is because, as can be seen from the characteristic diagram showing the relationship between the refrigerant state at the heat exchanger outlet and the average heat transfer coefficient in FIG. 12, the performance rapidly decreases when the heat exchanger outlet enters the superheat region. That is, for example, in the case of an indoor heat exchanger having a plurality of paths as shown in the configuration diagram of a general indoor unit heat exchanger of FIG. 13, even if the entire superheat is appropriate, If the superheat varies from pass to pass, the performance of the pass with a large superheat deteriorates, which further promotes the decrease of the cooling capacity.

In FIG. 13, (35) is a distributor, and (36a) to (3
6c) is a distribution pipe, (37a) to (37c) are evaporator paths, and (3
8) is the header.

Also, during the conventional multi-room air conditioning period, due to superheat control by the expansion valves (29a) and (29b) during heating and cooling operation,
Receiver (25) that stores excess refrigerant due to changes in operating conditions
Therefore, an accumulator (4) for preventing liquid return to the compressor (1) in an excessive state and two refrigerant absorption containers are required.

Furthermore, in the conventional multi-room air conditioner, when the junction of the liquid side branch circuit during heating operation is a high-pressure liquid refrigerant, and even if one of the indoor units is stopped, In order to collect the refrigerant, the refrigerant recovery circuit connected to the low-pressure circuit of the compressor via the check valve and the capillary tube is required, which makes the refrigerant circuit complicated. The refrigerant recovery circuit is omitted in FIG.

On the other hand, in the field of building air conditioning, multi-room air conditioners are popular due to restrictions on the installation space of the outdoor units, but in the conventional multi-room air conditioner shown in FIG. 11, the outdoor unit is generally installed. From the rooftop to the floor where the indoor units are installed, it is necessary to install refrigerant pipes for the number of indoor units, which increases construction costs and increases the occupied area of the pipe shaft of the building.

Therefore, as a multi-room air conditioner for a building, as shown in the refrigerant circuit diagram of another conventional multi-room air conditioner in FIG. 14, one pair from the outdoor unit to the floor on which the indoor unit is installed is installed. An air conditioner that can be installed by piping is proposed in Japanese Patent Laid-Open No. 62-102046.

Note that, in FIG. 14, the same reference numerals and symbols as in FIG. 11 indicate the same or corresponding components as those of the conventional first embodiment, and the description thereof will be omitted.

In FIG. 14, (30a) and (30b) are electric expansion valves that perform the functions of the liquid side solenoid valves (27a) and (27b) and the expansion valves (29a) and (29b) of FIG. 11, and (31) Is an electric expansion valve (30a), (3
0b) and gas side solenoid valves (26a) and (26b) are contained in a multi-unit, and (32a) and (32b) are capillaries.

In this conventional multi-room air conditioner, the refrigerant is circulated as indicated by a solid arrow during cooling operation and a dotted arrow during heating operation by switching operation of the four-way switching valve (2). .

Here, during the cooling operation, the electric expansion valves (30a) and (30b) are used to distribute the refrigerant to the indoor units, and during the heating operation, the electric expansion valve is fully opened and the capillaries (32a) and (32b). The distribution of the refrigerant to the indoor unit is corrected by the expansion pressure reduction valve (23).
It is done by.

On the other hand, the proposal of Japanese Patent Laid-Open No. 61-237978 describes the control when the number of operating indoor units suddenly increases or decreases. However, this is a problem of the speed of the expansion valve opening and cannot be used for distributing the refrigerant to the indoor units in the normal state.

[Problem to be Solved by the Invention] However, in the case of the conventional multi-room air conditioner of this type, the distribution means during the heating operation is improved as compared with the conventional example of FIG. Therefore, regarding the distribution performance during the cooling operation, it has the same performance as the conventional example of FIG. 11, and the receiver (25) and the cooling recovery circuit are required.

Furthermore, in this conventional example, in addition to the outdoor unit and the indoor unit, it is necessary to install the multi-unit (31) in the vicinity of the indoor unit, which causes a problem of installation space of the multi-unit (31) and complicated construction, and Considering after-sales service of (31) and dew condensation in the multi-unit (31), it becomes difficult to install due to restrictions on installation.

Further, together with the former conventional example and the latter conventional example, since the refrigerant is shut off by the gas side solenoid valves (26a) and (26b) in the stopped indoor unit during the heating operation, the high pressure gas refrigerant is The refrigerant may flow into the indoor heat exchangers (7a) and (7b) and generate refrigerant noise on the indoor unit side.

Therefore, the present invention properly performs the refrigerant distribution of a plurality of indoor units with a simple refrigerant circuit, and does not require a refrigerant recovery circuit,
It is possible to adjust the amount of refrigerant only with an accumulator and prevent the generation of refrigerant noise even during additional operation of the indoor unit.
An object is to provide a multi-room air conditioner that can be installed halfway from an outdoor unit with a pair of refrigerant pipes and can be freely branched on the indoor unit side with a high degree of installation freedom.

[Means for Solving the Problem] A multi-room air conditioner according to the invention of claim 1 is a compressor,
A four-way switching valve, an outdoor heat exchanger, and an accumulator are sequentially connected, and a heat exchanger incorporated in the accumulator capable of exchanging heat with the refrigerant in the accumulator disposed on the outlet side during the cooling operation of the outdoor heat exchanger. An outdoor unit capable of switching between heating and cooling and having a refrigerant circuit formed therein is connected to the outdoor unit through a pair of main pipes, and an indoor heat exchanger and an expansion valve driven by an electric signal are connected in series to a branch pipe branched from the main pipe. A plurality of indoor units that are connected to each other to form a refrigerant circuit, and a signal from a detector that detects a high pressure state on the output side of the temperature detector and the compressor that is disposed at the outlet during the cooling operation of the outdoor heat exchanger. To calculate the degree of supercooling, when the degree of supercooling is large in the direction of opening the total opening of the expansion valve for each indoor unit, and when the degree of supercooling is small, for each indoor unit Direction to close the total opening of the expansion valve Controlling said is for setting the opening degree of the expansion valve of the indoor machine according to the capability of the indoor unit.

A multi-room air conditioner according to the invention of claim 2 is a compressor,
A four-way switching valve, an outdoor heat exchanger, and an accumulator are sequentially connected, and a heat exchanger incorporated in the accumulator capable of exchanging heat with the refrigerant in the accumulator disposed on the outlet side during the cooling operation of the outdoor heat exchanger. An outdoor unit capable of switching between heating and cooling and having a refrigerant circuit formed therein is connected to the outdoor unit through a pair of main pipes, and an indoor heat exchanger and an expansion valve driven by an electric signal are connected in series to a branch pipe branched from the main pipe. A plurality of indoor units that are connected to each other to form a refrigerant circuit, and a signal from a temperature detector that is disposed at the outlet of the indoor heat exchanger during heating operation and a detector that detects the high pressure state of the output side of the compressor To calculate the degree of supercooling, and when the degree of supercooling is large, in the direction of opening the total opening of the expansion valves for each of the indoor units, and when the degree of supercooling is small, for each of the indoor units. To close the total opening of the expansion valve Controlling the said is for setting the opening degree of the expansion valve of the indoor machine according to the capability of the indoor unit.

[Operation] In the invention of claim 1, a signal from a temperature detector arranged at the outlet of the outdoor heat exchanger during the cooling operation and a detector for detecting a high-pressure state on the output side of the compressor is inputted and the temperature is exceeded. The degree of cooling is calculated, and when the degree of supercooling is large, the total opening of the expansion valves for each indoor unit is opened, and when the degree of subcooling is small, the total opening of the expansion valves for each indoor unit is closed. Direction, and the opening degree of the expansion valve of each indoor unit is set according to the capacity of each indoor unit.

According to the second aspect of the invention, the supercooling degree is controlled by inputting signals from the temperature detector arranged at the outlet of the indoor heat exchanger during the heating operation and the detector for detecting the high pressure state on the output side of the compressor. When the degree of supercooling is large, control is performed to open the total opening of expansion valves for each indoor unit, and when the degree of subcooling is small, control is performed to close the total opening of expansion valves for each indoor unit. Then, the opening degree of the expansion valve of each indoor unit is set according to the capacity of each indoor unit.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a refrigerant circuit diagram of a multi-room air conditioner according to a first embodiment of the present invention, and FIG. 2 is a block diagram of a control device for a multi-room air conditioner according to the first embodiment of the present invention. is there.

In FIG. 1, (1) is a compressor, (2) is a four-way switching valve, (3) is an outdoor heat exchanger, (4) is an accumulator,
(5) is a heat exchanger in the accumulator, and the pipe between the liquid pipe connection port and the outdoor heat exchanger (3) is designed to exchange heat with the refrigerant in the accumulator. , Constitutes a refrigerant circuit of the outdoor unit (6).

Further, (7a) to (7c) are indoor heat exchangers, (8a) to (8c)
Is a reversible expansion valve driven by an electric signal. The expansion valves (8a) to (8c) are installed on the inlet side of the indoor heat exchanger during cooling operation, and the refrigerant of the indoor units (9a) to (9c) It constitutes the circuit.

And (10) is a gas side main pipe connected to the gas pipe connection port of the outdoor unit (6), and the other end is a gas side branch pipe (12a)-
It branches to (12c) and is connected to the gas pipe connection ports of the indoor units (9a) to (9c). (11) is a liquid side main pipe connected to the liquid connection port of the outdoor unit (6), and the other end is branched to liquid side branch pipes (13a) to (13c), and the indoor units (9a) to (9c, respectively). )
It is connected to the liquid pipe connection port of.

(14) is a pressure sensor which is a pressure detecting means for detecting the discharge pressure of the compressor (1), (15) is a thermistor which is a temperature detector for detecting an outlet temperature during the cooling operation of the outdoor heat exchanger (3), (16a) to (16c) are indoor heat exchangers (7a) to (7c)
The thermistor, which is a temperature detector that detects the temperature of the outlet pipe during the heating operation of, the indoor units (9a) to (17a) to (17c)
A capacity setting switch for setting the capacity of (9c), (18) takes in the temperature and pressure signals and the switch input,
A control device for controlling the reversible expansion valves (8a) to (8c).

FIG. 2 is a block diagram of the control device (18). Basically, an analog / digital (A / D) converter (51), an input circuit (52), a central processing unit (CPU: 53), Memory (5
4), output circuit (55), output buffer (56) and resistor (5
It consists of 7). It should be noted that the input / output unit is only an example.

The capacity setting switches (17a) to (17c) are each composed of a 3-bit switch, and can be set in eight ways according to the capacities of the indoor units (9a) to (9c).

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

The high-pressure gas refrigerant discharged from the compressor (1) during the cooling operation passes through the four-way switching valve (2), is liquefied by the outdoor heat exchanger (3), and is liquefied by the heat exchanger (5) of the accumulator (4).
Further, it is cooled and has a large subcool (supercooling degree), and is guided to the indoor units (9a) to (9c) through the liquid side main pipe (11) and the liquid side branch pipes (13a) to (13c). Further, the expansion valves (8a) to (8c) provided in the indoor units (9a) to (9c) reduce the pressure, enter the indoor heat exchangers (7a) to (7c), and evaporate there. The evaporated refrigerant is the gas side branch pipe (12a) ~
A cycle is constructed in which the gas passes through (12c), merges in the gas side main pipe (10), returns to the outdoor unit (6), passes through the four-way switching valve (2), the accumulator (4), and returns to the compressor (1). .

At this time, the subcool at the outlet of the outdoor heat exchanger (3) is made constant by the pressure sensor (14) and the thermistor (15) at the outlet of the outdoor heat exchanger (3), and at the same time, the capacity setting switches (17a) to (17a). Each indoor unit (9a) registered by 17c) ~
The expansion valves (8a) to (8c) are controlled by the control device (18) so as to distribute the entire expansion valve opening depending on the size of (9c).

FIG. 3 is a flow chart for explaining an example of control of the expansion valves (8a) to (8c) during the cooling operation by the control device (18) of the present embodiment.

First, when the control is started, the high pressure is detected by the pressure sensor (14) in step S1, the saturation temperature (t1) converted from the pressure is input, and the output of the outdoor heat exchanger (3) is input in step S2. The outlet temperature (t2) of the outdoor heat exchanger (3) is detected by the thermistor (15) provided on the side, and this outlet temperature (t2) is input. In step S3, the subcool SC as these temperature differences is calculated by SC = t1−t2.

Absolute value of the difference from the subcool target value SC0 in step S4 | SC
-SC0 | is judged to be 3 ℃ or less, and if it is 3 ℃ or less, the total opening Does not change and moves to step S6. When it is determined that the deviation | SC-SC0 | from the input subcool target value SC0 as the subcool set value exceeds 3 ° C, step S
Total of each expansion valve opening in 5 Is the formula Is calculated using.

Where Nj: Opening of each expansion valve NJ: Opening of each expansion valve before change A: Positive constant determined by experiment Total of opening of each expansion valve Is calculated and when the subcool is large, the expansion valve (8
Adjust the overall opening of a) to (8c) in the opening direction, and if smaller, close it and move to step S6.

In step S6, the capacity code Qj: (= Q1 to Q3) of each indoor unit (9a) to (9c) being operated is set to the capacity setting switch (17a) to (17).
Read from c). Then, in step S7, the total opening Are distributed according to the size of Qj, and each expansion valve (8
The new opening Nj of a) to (8c) is output, and this flow ends. It should be noted that according to this flowchart, control is performed so that subcool adjustment and refrigerant distribution to the indoor units (9a) to (9c) are made appropriate.

That is, as can be seen from the characteristic diagram showing the relationship between the refrigerant state at the heat exchanger outlet and the average heat transfer coefficient in FIG. 12 described above, when the outlet enters the superheat region, the performance rapidly deteriorates, so the outlet is It can be seen that use in a wet state (dryness x = around 0.9) is important for improving performance. The above-mentioned control uses this, and the subcool is positively increased by the heat exchanger (5) of the accumulator (4), and the outlets of the indoor heat exchangers (7a) to (7c) are kept wet at the same time. , Even if the dryness of the outlet changes slightly in each circuit, it is designed to obtain a stable capacity, and indoor heat exchange in distributing the refrigerant to multiple indoor units (9a) to (9c). The indoor units (9a) to (7a) to (7c) are not uniquely fed back so as to adjust the distribution to the indoor units (9a) to (9c) depending on the refrigerant state at the outlets of the indoor units (9a) to (9a).
With the capacity ratio of (9c), even if only the total opening is distributed, the distribution performance can be secured under actual use conditions, and the controllability becomes good. At the same time, since the outdoor heat exchanger (3) takes a proper subcool, the outdoor heat exchanger (3) can be effectively used. Naturally, indoor units (9a) to (9c)
The amount of refrigerant is filled so that the outlets of the indoor heat exchangers (7a) to (7c) are in a wet state even when all of the above are operated. Further, in the heat exchanger (5) of the accumulator (4), pressure loss occurs in the extension pipe portion due to the height difference between the outdoor unit (6) and the indoor units (9a) to (9c), and the expansion valve (8a). It can also serve to prevent the refrigerant before (8c) to (8c) from flashing and changing the flow rate characteristics of the expansion valves (8a) to (8c). Further, when the number of operating indoor units (9a) to (9c) decreases, the expansion valves (8a) to (8c) of the stopped indoor units (9a) to (9c) are fully closed to make the refrigerant At the same time that the supply is stopped, the excess refrigerant can also be stored in the accumulator (4).

Further, during the heating operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor (1) passes through the four-way switching valve (2) whose flow path is switched as shown by the dotted line, and flows through the gas side main pipe (10) and the gas side branch. Indoor heat exchangers (7a) to (7c) through pipes (12a) to (12c)
Be led to. The refrigerant liquefied in the indoor heat exchangers (7a) to (7c) is the expansion valve (8a) to the indoor units (9a) to (9c).
It is decompressed by (8c) and becomes a two-phase refrigerant.
Outdoor unit (6) through a) to (13c) and liquid side main pipe (11)
To the compressor (1) via the four-way switching valve (2) and the accumulator (4).

At this time, the pressure sensor (14) and the indoor heat exchanger (7a) ~
Thermistors (16a) to (16c) provided on the outlet pipe of (7c)
As a result, the expansion valve (8) is controlled by the control device (18) so that the subcools at the outlets of the indoor heat exchangers (7a) to (7c) are kept constant.
a) to (8c) are controlled.

FIG. 4 is a flowchart illustrating an example of control of the expansion valves (8a) to (8c) during the heating operation by the control device (18) of the present embodiment.

First, when the control is started, the high pressure is detected by the pressure sensor (14) in step S11, the saturation temperature (t1) converted from the pressure is input, and in step S12, each indoor heat exchanger (7a)- The outlet temperatures (T1) to (T3) of (7c) are detected, the outlet temperatures (T1) to (T3) are input, and in step S13, each subcool SC1 to SC3 as the temperature difference between them is detected.
Is calculated by the formula SCj ＝ t1 ～ Tj. Average value SCA of each subcool in step S14
V is the formula Calculated by Subcool average SCAV in step S15
And the absolute value of the difference between the subcool target value SC0 | SCAV-SC0 | is 3 ° C or less, and if it is 3 ° C or less, step S1
Move to 7. When it is determined that the deviation | SCAV-SC0 | from the target subcool SC0 input as the subcool set value exceeds 3 ° C, the total opening of the expansion valves (8a) to (8c) is calculated in step S16. Is calculated using.

Where Nj: Opening of each expansion valve NJ: Opening of each expansion valve before change C: Positive constant determined by experiment Total of opening of each expansion valve (8a) to (8c) Is calculated, and when the average subcool is large, the opening degrees of the entire expansion valves (8a) to (8c) are adjusted in the opening direction, and when the average subcool is small, the opening direction is adjusted in the closing direction, and the process proceeds to step S17.

In step S17, it is determined whether the deviation | SCj−SCAV | of each subcool is 2 ° C. or less. If the deviation is 2 ° C. or less, the variable D is set to zero in step S18 and step S20.
Move on to. If the deviation exceeds 2 degrees, a predetermined constant D0 is set to the variable D in step S19, and the step
Move to S20.

Then, in step S20, each expansion valve opening Nj is calculated by Calculated in step S21, the expansion valves (8a) to (8
The new opening Nj of c) is output and this routine is ended.
In the calculation of the new opening of each expansion valve (8a) to (8c) in step S20, D is a positive constant determined by the experiment, and according to this calculation formula, each indoor heat exchanger (7a) to (7c ) The subcool at the exit is the indoor unit (9a) to (9
For c), the valve opening is increased, and for the indoor units (9a) to (9c) where the subcool is low, the valve opening is adjusted to a constant target value.

According to this flow chart, the correction based on the overall movement due to the average sub-cool and the correction based on the deviation of each sub-cool are performed, so the effect of the operating conditions of the other indoor units (9a) to (9c) is added, The amount of refrigerant is distributed, and the controllability is very good.

When the number of operating indoor units (9a) to (9c) decreases,
Expansion valves (8a) to (8c) of stopped indoor units (9a) to (9c)
The flow of the refrigerant is stopped by fully closing. The surplus refrigerant can be stored in the accumulator (4) as in the cooling operation.

Indoor heat exchanger (7a) of stopped indoor units (9a) to (9c)
In (7c), the refrigerant gradually condenses, but the liquid side branch pipe (13
Since the a) to (13c) sides are on the low pressure side, the refrigerant can be recovered by opening the expansion valves (8a) to (8c) for a certain period of time if necessary. Furthermore, since the indoor heat exchangers (7a) to (7c) are always connected to the high-voltage circuit, the indoor units (9a) to (9
Even if c) is additionally operated, no refrigerant noise is generated.

In addition, the expansion function (8a) to (8c) of the indoor units (9a) to (9c) for both air conditioning and heating allows the throttle function and each indoor unit (9a) to
Since it has a function to distribute the amount of refrigerant to (9c), the controller (18) automatically adjusts the flow rate difference due to the length and difference of the branch pipes and the height difference of the indoor units (9a) to (9c). Corrected,
Proper flow rate can be secured in any condition, and further,
The outdoor unit (6) can be constructed with a pair of pipes, and the pipe can be freely branched from the middle. In particular, in FIG. 1, the position where a plurality of branch pipes branch is one, but it is needless to say that the above characteristics can be exhibited even in a system where a plurality of branch pipes branch.

In the multi-room air conditioner of the first embodiment of the present invention, since the expansion valves (8a) to (8c) are controlled by the microcomputer, it is convenient even when the frequency control is used by the compressor. good.

FIG. 5 is a refrigerant circuit diagram of a multi-room air conditioner according to a second embodiment of the present invention. In the figure, the same reference numerals and symbols as those of the first embodiment show the same or corresponding components as those of the first embodiment, and therefore, duplicate description will be omitted and only different points will be explained.

This embodiment uses a saturation temperature detection circuit (19) instead of the pressure sensor (14) of the first embodiment, and is a temperature sensor which is a saturation temperature detection means for directly detecting the saturation temperature instead of pressure. The temperature is detected in (20). This detection circuit (1
9) is a heat exchanger (22), a capillary tube (21) and a temperature sensor (2
0), the refrigerant at the outlet of the compressor (1) is cooled by the heat exchanger (22), becomes a two-phase medium, and is decompressed by the capillary tube (21) to the suction pressure of the compressor (1). By becoming a phase refrigerant and exchanging heat in the heat exchanger (22), it becomes a low-pressure refrigerant having an enthalpy of refrigerant at the compressor inlet, completing the cycle.

FIG. 6 is a Mollier diagram showing the state of the refrigerant in the saturation temperature detection circuit of the multi-room air conditioner according to the embodiment of FIG. 5, and the solid line shows the state of the refrigerant in this detection circuit (19), and the broken line. (A), (B), (C), and (D) represent the states of the refrigerant on the normal refrigeration cycle. Further, (E) shows the entrance state of the capillary tube (21), and the temperature sensor (2
By installing 0), it becomes possible to detect the high pressure saturation temperature without using a pressure sensor.

In this embodiment, in steps S1 and S11 of the flowchart of the first embodiment, the saturation temperature (t
1) will be detected.

Further, although not shown, it goes without saying that if the temperature of the pipes near the center of the indoor and outdoor heat exchangers is detected, the high pressure saturation temperature during cooling and heating operation can also be detected.

As described above, according to the multi-room air conditioner of the embodiment of the present invention, the expansion valves (8a) to (8c) driven by electric signals provided in the indoor units (9a) to (9c) are used as control devices ( 18), while controlling the sub-cool during cooling operation so that the refrigerant is appropriately distributed by the capacity of each indoor unit (9a) to (9c), during heating operation, a plurality of indoor heat exchangers ( Since the subcools at the outlets 7a) to (7c) can be controlled to be constant, the receiver (25) is not required as in the conventional example, the refrigerant recovery circuit is not required, and the outdoor unit (6) can be used as a pair. Since the pipe can be installed halfway, the pipe becomes simple and the distribution performance is improved. Since the indoor heat exchangers (7a) to (7c) are always on the high voltage circuit side, no refrigerant noise is generated even during the additional operation of the indoor unit during the heating operation. Also, accumulator (4)
Since the heat exchanger (5) is provided in the above, a stable capacity can be obtained during the cooling operation even if the distribution of the refrigerant is slightly deviated or the load is slightly changed.

In the embodiment of the invention described above, each of the operating indoor units (9a) to (9
The ability of c) was input to the control device (18) as the ability code Qj (= Q1 to Q3) using the ability setting switches (17a) to (17c). However, this ability setting switch (17a)
~ (17c) can be omitted.

That is, the multi-room air conditioner of the present embodiment includes the compressor (1),
The four-way switching valve (2), the outdoor heat exchanger (3), and the accumulator (4) are sequentially connected, and the refrigerant in the accumulator (4) arranged on the outlet side of the outdoor heat exchanger (3) during the cooling operation is used. An outdoor unit (6) capable of switching between cooling and heating in which a heat exchanger (5) built in a heat-exchangeable accumulator (4) is provided to form a refrigerant circuit, and an outdoor unit (6) and a pair of main pipes (10) , (1
Expansion valves (8a) to which the indoor heat exchangers (7a) to (7c) and electric signals are connected to the branch pipes (12a) to (12c) that are connected by 1) and branched from the main pipes (10) and (11) It is composed of a plurality of indoor units (9a) to (9c) in which (8c) are connected in series to form a refrigerant circuit, a thermistor (15) arranged at the outlet of the outdoor heat exchanger (3) during the cooling operation, and the like. A supercooling degree is calculated by inputting a signal from a detector including a temperature sensor and a pressure sensor (14) for detecting a high pressure state on the output side of the compressor (1). In the direction to open the total opening of the expansion valves (8a) to (8c) for each indoor unit (9a) to (9c), and to each indoor unit (9a) to (9c) when the degree of subcooling is small. The total opening of the expansion valves (8a) to (8c) is controlled so as to be closed, and the expansion valves () of the indoor units (9a) to (9c) are controlled according to the capabilities of the indoor units (9a) to (9c). 8a) ~ (8c) open A control device (18) for setting the degree is provided, and the configuration during cooling and heating operation is shown, which can be the embodiment of claim 1.

In addition, the multi-room air conditioner of this embodiment includes a compressor (1),
The four-way switching valve (2), the outdoor heat exchanger (3), and the accumulator (4) are sequentially connected, and the refrigerant in the accumulator (4) arranged on the outlet side of the outdoor heat exchanger (3) during the cooling operation is used. An outdoor unit (6) capable of switching between cooling and heating in which a heat exchanger (5) built in a heat-exchangeable accumulator (4) is provided to form a refrigerant circuit, and an outdoor unit (6) and a pair of main pipes (10) , (1
The indoor heat exchanger (3) and the expansion valves (8a) to (8c) driven by electric signals are connected to the branch pipes (12a) to (12c) connected from the main pipes (10) and (11). A plurality of indoor units (9a) to (9c) connected in series to form a refrigerant circuit, and thermistors (16a) to (16c) arranged at the heating operation outlets of the indoor heat exchangers (7a) to (7c). ), Etc. and a signal from a detector, such as a pressure sensor (14), which detects the high-pressure state of the output side of the compressor (1), calculates the degree of supercooling by calculating the degree of supercooling. When is large, each indoor unit (9a) ~
Each indoor unit (9a) in the direction to open the total opening of expansion valves (8a) to (8c) for each (9c), and when the degree of supercooling is small.
Controlling the total opening of expansion valves (8a) to (8c) for each (9c) to the direction of closing, each indoor unit (9a) to (9c) to (9c) according to the capacity of each indoor unit (9a) to (9c) 9c) expansion valves (8a) ~ (8c) for setting the opening degree of the control device (18),
A configuration during heating operation is shown, and this can be the embodiment of claim 2.

FIG. 7 is a refrigerant circuit diagram of the multi-room air conditioner according to the third embodiment of the present invention, and FIG. 8 is a block diagram of a control device of the multi-room air conditioner according to the third embodiment of the present invention.

The third embodiment of the present invention is basically the same as the first embodiment, except that the capacity setting switch (17
a) ~ (17c) not used, indoor heat exchanger (7a) ~
The thermistors (160a) to (160c), which are temperature detectors for detecting the temperature of the outlet pipe during the cooling operation of (7c), are provided.

The outputs of the thermistors (160a) to (160c) that detect the temperature of the outlet pipe during the cooling operation of the indoor heat exchangers (7a) to (7c) are input to the control device (18), and the indoor heat exchangers ( 7
The expansion valves (8a) to (8c) are controlled so that the temperatures of the outlet pipes during the cooling operation of (a) to (7c) are made uniform.

FIG. 9 is a flow chart for explaining an example of control of the expansion valves (8a) to (8c) during the cooling operation by the control device (18) of the third embodiment of the present invention. Note that this flowchart is common to the control of the expansion valves (8a) to (8c) during the cooling operation by the control device (18) of the first embodiment of the present invention in FIG. 3, and the same step numbers are used. It shows the same content.

First, when the control is started, the high pressure is detected by the pressure sensor (14) in step S1, the saturation temperature (t1) converted from the pressure is input, and the output of the outdoor heat exchanger (3) is input in step S2. The outlet temperature (t2) of the outdoor heat exchanger (3) is detected by the thermistor (15) provided on the side, and this outlet temperature (t2) is input. In step S3, the subcool SC as these temperature differences is calculated by SC = t1−t2. In step S4, it is judged whether or not the absolute value | SC-SC0 | of the difference from the target value SC0 of the subcool is 3 ° C or less. Does not change and moves to step S6. When it is determined that the deviation | SC-SC0 | from the input subcool target value SC0 as the subcool set value exceeds 3 ° C, step S
Total of each expansion valve opening in 5 Is the formula Is calculated using.

Where Nj: Opening of each expansion valve NJ: Opening of each expansion valve before change A: Positive constant determined by experiment Total of opening each expansion valve Is calculated and when the subcool is large, the expansion valve (8
Adjust the whole opening of a) to (8c) to open, and if it is smaller, close it and move to step S26.

In step S26, the detected value (T1) of the outlet temperature of the indoor heat exchangers (7a) to (7c) is detected by the thermistors (160a) to (160c).
~ (T3) is input, and the detected values (T1) ~ (T
3) average value (TAV) is calculated and deviated in step S28 | Tj
-TAV | is judged to be 2 ° C or lower. If the deviation is 2 ° C. or less, the variable (B) is set to zero in step S29, and the process proceeds to step S31. If the deviation exceeds 2 ° C., a predetermined constant (B0) is set in the variable (B) in step S30, and the process proceeds to step S31. Then, in step S31, the opening degree Nj of each expansion valve (8a) to (8c) is calculated by Calculated in step S32, the expansion valves (8a) to (8
The new opening Nj of c) is output and this routine is ended.
That is, (B) in the new opening calculation formulas of the expansion valves (8a) to (8c) in step S31 is a positive constant determined by an experiment, and according to this calculation formula, each indoor heat exchanger (7a) ~ (7
For the outlet temperature of c), the indoor units (9a) to (9c) with higher temperature
For, increase the opening of each expansion valve (8a) ~ (8c),
For the indoor units (9a) to (9c) having a low temperature, the temperatures are adjusted by reducing the openings of the expansion valves (8a) to (8c).

The flowchart for explaining an example of the control of the expansion valves (8a) to (8c) during the heating operation by the control device (18) of this embodiment is the control of the first embodiment of the present invention of FIG. Since it is the same as the control of the expansion valves (8a) to (8c) during the heating operation by the device (18), the description thereof will be omitted.

As described above, according to the flow chart of the present embodiment, the adjustment of the subcool and the outlet temperature of each indoor heat exchanger are controlled to match.

This embodiment can also be modified like the second embodiment.

FIG. 10 is a refrigerant circuit diagram of a multi-room air conditioner according to a fourth embodiment of the present invention. The circuit configuration and its operation are
Since it is common to the second and third embodiments,
The description is omitted.

[Advantages of the Invention] As described above, the multi-room air conditioner according to claim 1 detects the high-pressure pressure state on the output side of the temperature detector and the compressor arranged at the outlet of the outdoor heat exchanger during the cooling operation. Input the signal from the detector to calculate the degree of supercooling, and when the degree of supercooling is large, in the direction to open the total opening of the expansion valves for each indoor unit,
Further, when the degree of subcooling is small, the total opening of the expansion valves of each indoor unit is controlled to be closed, and the opening of the expansion valve of each indoor unit is set according to the capacity of each indoor unit. Is.

Therefore, the expansion valve driven by the electric signal provided in the indoor unit, while keeping the subcool constant during the cooling operation,
It controls so that the refrigerant is appropriately distributed according to the capacity of each indoor unit, and during heating operation, it can be controlled so that the subcools at the outlets of multiple indoor heat exchangers are kept constant, so a receiver is not required and the refrigerant recovery circuit Is unnecessary, and furthermore, it can be installed halfway from the outdoor unit with a pair of pipes, and because simple refrigerant piping is required, construction performance is improved. Further, since the indoor heat exchanger is always on the high voltage circuit side, no refrigerant noise is generated. Further, since the accumulator is provided with the heat exchanger, there is an effect that a stable capacity can be obtained during the cooling operation even if the distribution of the refrigerant is slightly deviated or the load is slightly changed.

The multi-room air conditioner according to claim 2 inputs signals from a temperature detector arranged at the outlet of the indoor heat exchanger during heating operation and a detector for detecting a high pressure state on the output side of the compressor. Calculate the degree of supercooling, and when the degree of supercooling is large, open the total opening of the expansion valves for each indoor unit.When the degree of subcooling is small, the total amount of expansion valves for each indoor unit is calculated. The opening degree is controlled to be closed, and the opening degree of the expansion valve of each indoor unit is set according to the capacity of each indoor unit.

Also in this invention, it is possible to obtain the same effect as that of the above-mentioned invention of claim 1, and further, in the present invention, since the adjustment of the subcool and the outlet temperature of each indoor heat exchanger are controlled to coincide with each other, it is possible to control each indoor It can be controlled to match the capability of the machine, and by the way, proper distribution of the refrigerant can be performed even if the refrigerant circuit changes over time.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of a multi-room air conditioner according to the first embodiment of the present invention, and FIG. 2 is a block diagram of a control device for a multi-room air conditioner according to the first embodiment of the present invention. FIG. 4 is a flow chart for explaining a first example of the control of the expansion valve during the cooling operation by the control device of the first embodiment, and FIG. 4 is a flowchart of the control of the expansion valve during the heating operation by the control device of the first embodiment. A flow chart for explaining an example, FIG. 5 is a refrigerant circuit diagram of a multi-room air conditioner according to a second embodiment of the present invention, and FIG. 6 is a saturation temperature detection of the multi-room air conditioner according to the embodiment of FIG. FIG. 7 is a Mollier diagram showing the state of the refrigerant in the circuit, FIG. 7 is a refrigerant circuit diagram of the multi-room air conditioner according to the third embodiment of the present invention, and FIG. 8 is a multi-room air conditioner according to the third embodiment of the present invention. FIG. 9 is a block diagram of the control device of the air conditioner, and FIG. 9 is a cooling operation by the control device of the third embodiment of the present invention. A flow chart illustrating a first example of control of an expansion valve, FIG. 10 is a refrigerant circuit diagram of a multi-room air conditioner according to a fourth embodiment of the present invention, and FIG. 11 is a conventional multi-room air conditioner. Refrigerant circuit diagram, FIG. 12 is a characteristic diagram showing the relationship between the refrigerant state at the heat exchange outlet and the average heat transfer coefficient, FIG. 13 is a configuration diagram showing the connection state of the refrigerant circuit of a general heat exchanger, FIG. FIG. 6 is a refrigerant circuit diagram of another conventional multi-room air conditioner. In the figure, 1: compressor, 2: four-way switching valve 3: outdoor heat exchanger, 4: accumulator 5: heat exchanger built in accumulator 6: outdoor unit 7a, 7b, 7c: indoor heat exchanger 8a, 8b, 8c: Expansion valve 9a, 9b, 9c: Indoor unit 14: Pressure sensor 15,16a, 16b, 16c, 160a, 160b, 160c: Thermistor 17a, 17b, 17c: Capacity setting switch 18: Controller. In the drawings, the same reference numerals and symbols indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A compressor, a four-way switching valve, an outdoor heat exchanger, and an accumulator which are sequentially connected, and which can exchange heat with a refrigerant in the accumulator disposed on the outlet side of the outdoor heat exchanger during cooling operation. An outdoor unit capable of switching between heating and cooling, in which a heat exchanger incorporated in an accumulator is provided to form a refrigerant circuit, and the outdoor unit is connected to the outdoor unit by a pair of main pipes, and a branch pipe branched from the main pipe is connected to the indoor heat exchanger and the electricity. A plurality of indoor units in which expansion valves driven by signals are connected in series to form a refrigerant circuit, and a high temperature pressure state on the output side of the temperature detector and the compressor arranged at the outlet during the cooling operation of the outdoor heat exchanger A signal from a detector for detecting the supercooling degree is input to calculate a subcooling degree, and when the subcooling degree is large, in a direction of opening the total opening of the expansion valves of the indoor units, and When the degree of supercooling is small, A control device that controls the total opening of the expansion valves for each of the indoor units in the closing direction and sets the opening of the expansion valve of each of the indoor units according to the capacity of each of the indoor units. A multi-room air conditioner. 2. A compressor, a four-way switching valve, an outdoor heat exchanger, and an accumulator are sequentially connected, and the heat exchange with the refrigerant in the accumulator is provided on the outlet side of the outdoor heat exchanger during cooling operation. An outdoor unit capable of switching between heating and cooling, in which a heat exchanger incorporated in an accumulator is provided to form a refrigerant circuit, and the outdoor unit is connected to the outdoor unit by a pair of main pipes, and a branch pipe branched from the main pipe is connected to the indoor heat exchanger and the electricity. A plurality of indoor units in which expansion valves driven by signals are connected in series to form a refrigerant circuit, and a high temperature pressure state on the output side of the temperature detector and the compressor arranged at the heating operation outlet of the indoor heat exchanger The supercooling degree is calculated by inputting a signal from a detector that detects, and when the supercooling degree is large, in the direction of opening the total opening of the expansion valves of the indoor units, and the supercooling degree. When is small, expansion of each indoor unit And a control device that controls the opening of the expansion valve of each of the indoor units according to the capacity of each of the indoor units to control the total opening of the indoor unit of the multi-room air conditioner. Machine.