JPH0694959B2 - Multi-room air conditioner - Google Patents

Description

TECHNICAL FIELD The present invention relates to a multi-room air conditioner, and more particularly to a multi-room air conditioner in which a plurality of indoor units are connected to one outdoor unit. Is.

[Conventional technology]

As a multi-room air conditioner of this type according to a conventional example, for example, a configuration of a multi-room air conditioner described in Japanese Utility Model Publication No. 55-28993 is shown in FIG. That is, in FIG. 7, reference numeral 1 denotes a compressor, 2 denotes an upstream side of the compressor 1, and a four-way valve having a switching valve for performing cycle switching between cooling and heating, 3
Is an outdoor heat exchanger in which one is connected to the four-way switching valve 2 and the other is connected to the expansion valve 22 and the receiver 28 in series, 4 is an accumulator connected between the compressor 1 and the four-way valve 2, Reference numeral 23 is a check valve connected in parallel to the expansion valve 22 and constitutes a main circuit portion of the air conditioner. A plurality of 5a and 5b are branched in parallel from the main circuit section and connected between the four-way valve 2 and the receiver 28 via gas side solenoid valves 6a and 6b and liquid side solenoid valves 24a and 24b, respectively. Indoor heat exchangers for each of these heat exchangers 5a, 5
Also for b, the expansion valve is connected between each liquid side solenoid valve 24a, 24b.
Parallel circuits of 26a, 26b and check valves 25a, 25b are connected in series, respectively. In the case of the multi-room air conditioner according to this conventional example, the refrigerant is circulated by the switching operation of the four-way valve 2 as shown by the solid arrow in FIG. 7 for the cooling operation and as shown by the dotted arrow in the heating operation. is there.

And, in the case of the configuration of this conventional example, each indoor heat exchanger 5a, 5
b, that is, the plurality of indoor units are provided with expansion valves 26a, 26b for cooling, and these are unbalanced in load of the plurality of indoor units during cooling, or the installed positional relationship of each indoor unit is relatively large. Its main purpose is to supply a proper amount of refrigerant to each indoor unit even when it is not equal, but there is a means to distribute an appropriate amount of refrigerant to multiple indoor units during heating. However, the circuit configuration is not always sufficient as an air conditioner for multiple rooms. Further, in a so-called one-to-one correspondence general air conditioner in which one outdoor unit corresponds to one indoor unit, the same reference numerals are used in FIG. 8 for the portions corresponding to FIG. 7. As described above, the indoor unit is not provided with the expansion valve for controlling the refrigerant, and the capillary tube 27 provided in the outdoor unit controls both cooling and heating, which is a very simple and inexpensive circuit configuration. Is normal.

[Problems to be solved by the invention]

However, as an indoor unit for a multi-room air conditioner, it is difficult to apply the one-to-one correspondence indoor unit that is relatively inexpensive and has a large number of productions, and it is difficult to use it during heating and cooling. Control requires a receiver that stores excess refrigerant due to changes in operating conditions, and requires two refrigerant absorption containers together with an accumulator to prevent liquid return to the compressor in an excessive state. there were.

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 causes a problem that the refrigerant circuit becomes complicated.

The present invention has been made to solve the above-mentioned problems, and while being a simple refrigerant circuit, it can be directly connected to a standard indoor unit used for a one-to-one air conditioner, An object of the present invention is to obtain a multi-room air conditioner that appropriately distributes refrigerant during heating and cooling operation to a plurality of indoor units, and that does not require a refrigerant recovery circuit and can adjust the amount of refrigerant only by an accumulator. .

[Means for solving problems]

The multi-room air conditioner according to the present invention, each gas side branch pipe connected to a plurality of indoor units is provided with an electromagnetic valve, and each liquid side branch pipe is provided with an expansion valve driven by an electric signal. A heat exchanger for exchanging heat with the refrigerant in the accumulator is provided between the confluence of the outdoor heat exchanger and the liquid side branch pipe, and the pressure or temperature obtained by the means for detecting the high pressure or the saturation temperature and the above-mentioned respective chambers. The control device controls the expansion valve according to the input signal of the switch for setting the capacity of the machine.

[Work]

The multi-room air conditioner according to the present invention, at the time of cooling and heating,
The expansion valve can control the degree of supercooling while balancing the supply of refrigerant to multiple indoor units, and can properly distribute the refrigerant to multiple indoor units, while maintaining a constant degree of supercooling. With a simple refrigerant circuit, standard indoor units can be connected as they are.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, 1 is a compressor, 2 is a four-way valve which is a switching valve, 3
Is an outdoor heat exchanger, 4 is an accumulator, and these constitute the main part of the air conditioner. Reference numeral 8 is a heat exchanger in the accumulator, and the piping between the liquid side branch circuit and the outdoor heat exchanger 3 exchanges heat with the refrigerant in the accumulator. 6a to 6c are gas side electromagnetic valves provided in the gas side branch pipes 14a to 14c, and 7a to 7c are reversible expansion valves driven by electronic or electric signals provided in the liquid side branch pipes 15a to 15c. Further, the indoor heat exchanger 5a in a plurality of indoor units (not shown) via the connecting pipes 16a to 16c and 17a to 17c between the gas side branch pipes 14a to 14c and the liquid side branch pipes 15a to 15c. ,Five
b and 5c are connected. Reference numeral 10 is a pressure sensor which is a pressure detecting means for detecting the discharge pressure of the compressor 1, and 12a to 12c are switches for setting the capacity of the indoor unit. Here, the capacity of the indoor unit is the cooling capacity and the heating capacity, and can be the capacity of the indoor unit, that is, the size of the indoor heat exchanger. 13a ~ 13c
Is a temperature sensor that is a temperature detector that detects the temperature of the liquid side branch pipe, 11 is a temperature sensor that detects the outlet temperature of the outdoor heat exchanger during cooling, 9 is the input of the above switch, the temperature signal of the temperature sensor, and the pressure sensor Is a control device that controls the reversible expansion valves 7a to 7c by taking in the pressure signal.

FIG. 2 is a block diagram of the control device, which includes an analog-digital converter (A / D converter) 51, an input circuit 52, a central processing unit (CPU) 53, a memory 54, an output circuit 55, and an output buffer 56. It is configured. It should be noted that the input / output unit is shown as an example only. Each of the capacity setting switch values 12a to 12c is composed of a 3-bit switch. For example, when the cooling capacity of the connected indoor unit is 2000 kcal / h, the switch setting is "000", and when it is 2500 kcal / h. There are 8 possible settings, such as "001".

Next, the operation of this embodiment will be described. In FIG. 1, during cooling, the high-pressure gas refrigerant discharged from the compressor 1 passes through the four-way valve 2, is liquefied by the outdoor heat exchanger 3, and is further cooled by the heat exchanger 8 in the accumulator 4 to obtain the degree of supercooling. Is taken to a branch circuit. Further, the pressure is reduced by expansion valves 7a to 7c provided in the respective branch pipes, enters the indoor heat exchangers 5a to 5c through the connecting pipes 17a to 17c, and evaporates there. The evaporated refrigerant is connected to the gas side communication pipes 16a to 16c.
Through the solenoid valves 6a to 6c provided on the gas side branch pipes 14a to 14c, and then returns to the compressor 1 via the four-way valve 2 and the accumulator 4. At this time, the pressure sensor 10 and the temperature sensor at the outlet of the outdoor heat exchanger 3
11 makes the degree of subcooling at the outlet of the outdoor heat exchanger 3 (hereinafter referred to as "subcool") constant, and at the same time sets the capacity setting switch.
The expansion valves 7a to 7c are controlled by the control device 9 so as to distribute the entire opening depending on the size of each indoor unit registered by 12a to 12c.
To control.

FIG. 3 shows that the expansion valves 7a to 7c are controlled by the control device 9 during cooling.
5 is a flowchart for explaining an example of controlling the.

When the flow starts, the high pressure saturation temperature is detected by the pressure sensor 10 in step 61, the saturation temperature t ₁ is arithmetically processed, and in step 62, the outdoor heat exchanger 3 is operated by the temperature sensor 11 provided on the outlet side of the outdoor heat exchanger 3. Outlet temperature of exchanger 3 t ₂
Is detected, this outlet temperature t ₂ is entered, and step 63
Then, the SC as the difference between these temperatures is calculated. Step
In 64, it is compared whether or not the deviation | SC-SCo | with the target subcool SCo calculated as the set value of the subcool is a constant value, for example, 3 ° C or less, and when it is determined that the deviation exceeds 3 ° C, Total of each expansion valve opening in step 65 Is the formula Is calculated using.

Where Nj is the opening of each expansion valve Nj ^* : The opening of each expansion valve before the change A: A constant determined by experiments The total opening ΣNj of each expansion valve is calculated and when the subcool is large, the expansion valve Adjust the total opening to the opening direction, or to the closing direction when it is small, and move to step 66. If you judge that the deviation is 3 ° C or less, change the total opening in step 65. Instead, proceed to step 66. Step
In 66, the capacity code Qj, which is proportional to the capacity of each indoor unit in operation set by the capacity setting switches 12a to 12c,
For example, when the cooling capacity is 2000 kcal / h, Qj = 4, 2500 kcal
Qj = 5 when / h, Qj = 8 when 4000 kcal / h Controller 9
Read from. Next, in step 67, the total opening is distributed by Qj, and in step 68, the new opening Nj is output.

According to this flowchart, the subcool adjustment and the distribution to the indoor units are controlled appropriately.

FIG. 4 shows the state of the refrigerant at the outlet of the evaporator and the change in the average heat transfer coefficient. As can be seen from FIG. 4, when the outlet enters the superheat region, the performance deteriorates sharply. It can be seen that using the outlet in a wet state (dryness x = around 0.9) is important for improving performance. The above-mentioned control uses this, positively increasing the subcool to keep the evaporator outlet wet, and even if the dryness of the outlet changes slightly in each circuit,
It is designed to have a stable capacity, and it has multiple branch pipes 14
In distributing the refrigerant to a to 14c and 15a to 15c, the controllability is very good, and at the same time, in the outdoor heat exchanger 3,
Since the subcool is properly taken, the outdoor heat exchanger 3 can be effectively used. As a matter of course, the amount of the refrigerant is filled so that the evaporator outlet is in a wet state even when all the indoor units are in operation. Furthermore, when the number of operating indoor units decreases, the refrigerant supply is stopped by fully closing the expansion valves 7a, 7b, 7c of the liquid side branch pipes corresponding to the stopped indoor units, while the excess refrigerant is It also has a function of being able to be stored in the accumulator 4.

During heating, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 has a four-way valve 2 whose passage is switched as shown by the broken line in FIG.
Through the solenoid valves 6a to 6c provided in the gas side branch pipes 14a to 14c, and are led to the indoor heat exchangers 5a to 5c via the connecting pipes 16a to 16c. The liquefied refrigerant here is used for indoor / outdoor communication pipes 17
After returning to the outdoor unit through a to 17c, the pressure is reduced by the expansion valves 7a to 7c provided in the three liquid side branch pipes 15a to 15c, evaporated in the outdoor heat exchanger 3, and compressed via the four-way valve 2 and the accumulator 4. Configure a cycle to return to machine 1. At this time, with the pressure sensor 10,
The temperature sensors 13a to 13c provided on the liquid side branch pipes 15a to 15c make the subcool at the outlets of the indoor heat exchangers 5a to 5c constant, and at the same time, the controller 9 expands the expansion valve 7a so that the temperatures of the respective branch pipes are equalized. Control ~ 7c. Further, when the number of operating indoor units decreases, the refrigerant supply is stopped by closing the solenoid valve of the gas side branch circuit corresponding to the stopped indoor unit. The surplus refrigerant can be stored in the accumulator 4 as in the case of cooling.

In addition, when both the cold side and the heating side have a junction at the downstream side of the branch circuit that is on the low pressure side and there is a stopped indoor unit, the refrigerant can be recovered by closing the branch circuit inlet and opening the outlet. Becomes

According to the embodiment of the present invention, since the control device is controlled by the electric signal, the subcool at the indoor heat exchanger outlet can be made constant by the pressure sensor and the temperature sensor provided in the liquid side branch pipe during heating. The temperature of the branch pipes can be made uniform, and during cooling, the subcool can be made constant by the pressure sensor and the temperature sensor provided at the outlet of the outdoor heat exchanger, and the refrigerant is appropriately distributed by the capacity code Qj of each indoor unit. There is an effect that it is not necessary to provide a receiver, can be easily combined with a standard indoor unit, has good distribution performance, and does not require a refrigerant recovery circuit. Further, in the multi-room air conditioner of one embodiment of the present invention, the expansion valve is controlled by the microcomputer, which is convenient when the frequency of the compressor is to be controlled by an inverter.

FIG. 5 is a refrigerant circuit diagram showing another embodiment of the present invention. In this embodiment, a saturation temperature detecting circuit 18 is used in place of the pressure sensor 10, and a temperature sensor 19 which is a saturation temperature detecting means for directly detecting the saturation temperature instead of the pressure is used for detection. The detection circuit 18 includes a heat exchanger 21 and a capillary tube.
The refrigerant at the outlet of the compressor 1 is cooled by the heat exchanger 21 to become a two-phase refrigerant, which is decompressed to the suction pressure of the compressor 1 by the capillary tube 20 and becomes a low-temperature two-phase refrigerant.
At 21, the heat exchange results in a low-pressure refrigerant having an enthalpy almost the same as the enthalpy of the refrigerant at the compressor outlet, completing the cycle. FIG. 6 shows the behavior of this refrigerant on the Mollier diagram. The solid line shows the state of the refrigerant in the detection circuit 18, and the broken line ABCD shows the state of the refrigerant on the normal refrigeration cycle. In FIG. 6, E shows the entrance state of the capillary tube 20, and by attaching the temperature sensor 19 to this location,
It is possible to detect the high pressure saturation temperature without using a pressure sensor.

Although not shown, it goes without saying that the high pressure saturation temperature during cooling and heating can also be detected by detecting the temperature of the pipe near the center of the indoor and outdoor heat exchangers.

〔The invention's effect〕

As described above, according to the present invention, the expansion valve driven by the electric signal can be controlled by the control device so as to properly distribute the refrigerant to the plurality of branch pipes while keeping the subcool constant. It is possible to obtain an multi-room air conditioner that can be combined with an indoor unit, does not require a receiver, has good distribution performance, and does not require a refrigerant recovery circuit.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of a multi-room air conditioner according to an embodiment of the present invention, FIG. 2 is a block diagram of the same controller, FIG. 3 is a flow chart for explaining control operation, and FIG. 4 is an evaporator. FIG. 5 is a diagram showing the relationship between the refrigerant state at the outlet and the average heat transfer coefficient, FIG. 5 is a refrigerant circuit diagram of a multi-room air conditioner according to another embodiment of the present invention, and FIG. 6 is a refrigerant in the saturation temperature detection circuit. Fig. 7 and Fig. 8 showing the above state are refrigerant circuit diagrams of different conventional air conditioners. 1 ... Compressor, 2 ... four-way valve (switching valve), 3 ... outdoor heat exchanger, 4 ... accumulator, 5a-5c ... indoor heat exchanger, 6a-6c ... solenoid valve, 7a-7c ...... Expansion valve, 8 ...... Heat exchanger in accumulator, 9 ...... Control device, 10 ...... Pressure sensor, 11,13a to 13c ...... Temperature sensor, 12a to 12c ...... Capability setting switch, 14a to 14c ... … Gas side branch pipe, 15a-15c
...... Liquid side branch pipe, 16a to 16c, 17a to 17c ...... Communication pipe, 18
...... Saturation temperature detection circuit, 19 ...... Temperature sensor, 20 ...... Capillary tube, 21 ...... Heat exchanger. The same reference numerals in the drawings indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Sato 3-18-1, Oga, Shizuoka-shi, Shizuoka Mitsubishi Electric Corporation Shizuoka Works (56) Reference JP-A-61-153357 (JP, A) Kaisho 61-243262 (JP, A)

Claims (1)

[Claims] 1. An outdoor unit capable of switching between cooling and heating, which comprises a compressor, a switching valve, an accumulator, and an outdoor heat exchanger as main members, and has a branch in parallel with a liquid pipe and a gas pipe of the outdoor unit. In a multi-room air conditioner in which pipes are provided and a plurality of indoor units are connected to these branch pipes through communication pipes, each gas side branch pipe is equipped with a solenoid valve, and each liquid side branch pipe is electrically connected. An expansion valve driven by a signal is provided, a heat exchanger capable of exchanging heat with the refrigerant in the accumulator is provided in the pipe between the confluence point of the outdoor heat exchanger and the liquid side branch pipe, and further, the liquid side branch pipe and A temperature detector is provided in each of the outlet pipes during cooling of the outdoor heat exchanger, and detection means for detecting the high pressure or saturation temperature, a switch for setting the capacity of the connected indoor unit, and the temperature detector are provided. Temperature and above detection means Thus resulting pressure or the saturation temperature and the multi-room air conditioner which is characterized in that is provided a control device for controlling the expansion valve by the input signal of the switch.