JPH0424364Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a multi-room air conditioner in which multiple indoor units are connected in parallel to one outdoor unit to form a reversible compression refrigeration cycle. .

(Prior art) This type of multi-room air conditioner is disclosed in Japanese Patent Laid-Open No. 12372/1983, which is capable of operating not only cooling and heating, but also cooling a portion of the air conditioner and heating the rest of the air conditioner. As shown above, there are some known methods.

(Problems to be solved by the invention) By the way, a conventional multi-room air conditioner capable of simultaneous heating and cooling operations has three times as many on-off valves as the number of indoor units, such as solenoid valves, as shown in the above-mentioned publication. However, the disadvantage is that the required device is complicated and expensive, and the control circuit is similarly complicated.

In order to solve this problem, as shown in FIG. 3, each liquid pipe 7 of a plurality of indoor units _2-1 , _2-2 , . It is connected to the high pressure liquid pipe 14 of the outdoor unit 1, and each gas pipe 8 can be switched to the high pressure gas pipe 16 and the low pressure gas pipe 17 of the outdoor unit 1 via the three-way switching valves 26-1, _{26-2 ,} respectively. During cooling operation, the switching valves _26-1 , 26-2... are switched to the connection side to the low-pressure gas pipe 17, and the outdoor coil 12 acts as a condenser, while during heating operation, the switching valves 26-1, _26-2 ... are switched to the connection side to the low-pressure gas pipe 17. valve 2
_6-1 , _26-2 ... may be switched to the connection side to the high-pressure gas pipe 16, and a control form may be considered in which the outdoor coil 12 is made to function as an evaporator.

When such a control mode is adopted, in the stop mode during heating operation, the three-way switching valve 26 is closed in order to prevent refrigerant liquid from accumulating in the indoor coil 4.
- ₁ , 26- ₂ ... are connected to the low pressure gas pipe 1 in the same way as in the cooling operation.
In this case, the high-pressure refrigerant is connected to the surroundings in the piping connecting the high-pressure gas pipe 16 and the ports of the three-way switching valves _26-1 , _26-2 ... As it cools down to a certain temperature, liquefies and accumulates, in order to start cooling operation,
When the three-way switching valves _26-1 , _26-2 ... are switched and operated, the above-mentioned accumulated liquid suddenly flows toward the indoor coil 4, and as a result, there is a risk that the coil of the indoor unit will be damaged by the refrigerant liquid hammer. There is.

The present invention has been devised to eliminate such drawbacks, and is a bypass that releases accumulated liquid in the piping that connects the high-pressure gas pipe and the switching valve that switches between the cooling cycle and the heating cycle. By providing a channel, the purpose is to reliably prevent the occurrence of liquid hammer.

(Means for solving the problem) Therefore, the present invention provides a multi-room air conditioner that
Each liquid pipe 7 of a plurality of indoor units _2-1 , _2-2 ... equipped with a series refrigerant circuit including a cooling expansion valve 3 and an indoor coil 4
are connected to the high-pressure liquid pipe 14 of one outdoor unit 1, and each gas pipe 8 is connected to the high-pressure gas pipe 16 of the outdoor unit 1 and the low-pressure gas pipe via four-way switching valves _15-1 , _15-2 , respectively. The surplus ports of the four-way switching valves _15-1 , _15-2 , which switch to the high pressure range during the cooling cycle and to the low pressure range during the heating cycle, are connected to the capillary reach tube 18 in a switchable manner. Therefore, it is characterized in that it is connected to a low pressure gas pipe 17.

(Function) The present invention allows the four-way switching valve 1 to
_5-1 , _15-2 ..., the gas pipe 8 on the indoor side is connected to the outdoor unit 1
By switching the four-way switching valves _15-1 and _15-2 so as to communicate with the low pressure gas pipe 17 of
The high-pressure refrigerant gas in the high-pressure gas pipe connected to the high-pressure gas pipe constantly flows through the capillary reach tube 18, and as a result, the temperature of the high-pressure gas pipe can be maintained at a high temperature to prevent liquid accumulation.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a device circuit diagram of a two-room air conditioner according to one example of the present invention, where 1 is an outdoor unit, _2-1 , _2-2
is an indoor unit, and each of the indoor units _2-1 and _2-2 has an indoor coil 4, and they have the same structure, so to explain one indoor unit _2-1 , the indoor fan 5 will be explained. A cooling expansion valve 3 in which a bypass pipe 6 having, for example, a check valve for circulating a refrigerant during heating operation is connected in parallel is connected in series to the indoor coil 4 having the above-mentioned indoor coil 4. A liquid pipe 7 is connected to the inlet side of the expansion valve 3, and a gas pipe 8 is connected to the coil end of the indoor coil 4.

Each of the expansion valves 3 is a temperature-sensitive expansion valve in order to maintain the temperature of the gas pipe 8 at a predetermined degree of superheat,
A three-way solenoid valve 24 is attached as a pilot valve to control the valve to open or close, and when energized, the three-way solenoid valve 24 opens the gas pipe 8.
pressure is applied to the expansion valve 3, and the liquid pipe 7 is deenergized.
The pressure is applied to the expansion valve 3.

On the other hand, the outdoor unit 1 has a single unit structure common to the two indoor units _2-1 and _2-2 , and includes a compressor 9, a low-pressure gas pipe 17 connected to the inlet of the compressor 9, and a low-pressure gas pipe 17 connected to the inlet of the compressor 9. an accumulator 10 interposed in the gas pipe 17;
a high-pressure gas pipe 16 connected to the discharge port of the compressor 9;
A high-pressure liquid pipe 14 is connected to each liquid pipe 7 in each indoor unit _2-1 , _2-2 , a receiver 11 has one end connected to this high-pressure liquid pipe 14, and an inlet is also connected to the high-pressure liquid pipe 14. A heating expansion valve 13, an outdoor coil 12 serving as a condenser and evaporator connected in series to the outlet of the expansion valve 13, and an end of the outdoor coil 12 selectively connected to a high pressure gas pipe 16 and a low pressure gas pipe 17. Switching valve 1 for outdoor coil provided as possible
9. A first bypass circuit 21 extending between the outlet of the heating expansion valve 13 and the other end of the receiver 11 and having a check valve interposed therebetween, the high-pressure gas pipe 16 and the other end of the receiver 11; and a second bypass circuit 22 having a proportional control valve 23 interposed therebetween, between the high pressure gas pipe 16, the low pressure gas pipe 17, and the gas pipe 8 of each indoor unit _2-1 , _2-2 . a plurality of four-way switching valves 15-1, 15-2, which are respectively interposed in the four-way switching valves _15-1 , _15-2 , to selectively connect each gas pipe 8 of the indoor units _2-1 , _2-2 to the high-pressure gas pipe 16 or the low-pressure gas pipe 17; It is constituted by each member of a three-way solenoid valve 25 attached as a pilot valve for controlling the heating expansion valve 13 to open or close.

Note that a temperature-sensitive expansion valve is used as the heating expansion valve 13, and the temperature of the low-pressure gas pipe 17, that is, the compressor 9
Valve control is performed to maintain the temperature of the gas refrigerant sucked into the gas refrigerant at a predetermined degree of superheat. Accordingly, the high pressure liquid pipe 14
The pressure inside is applied to the expansion valve 13.

In the air conditioner having the above configuration, the four-way switching valves _15-1 , _15-2 and the outdoor coil switching valve 19 are operated by solenoid control as schematically shown in FIG.
A four-way valve with a pilot-operated sliding structure is used, and two ports B and D are switched and communicated with a high-pressure port A connected to a high-pressure gas pipe 16 and a low-pressure port C connected to a low-pressure gas pipe 17.
Of these, the surplus port B, which is normally a closed port, and the low pressure port C are connected by capillary reach tubes 18 and 20, respectively, and are essentially used as a three-way switching valve.

In this case, the capillary reach tube 18 operates in the high pressure region during the four-way switching valves _15-1 and _15-2 during the cooling cycle.
It is a resistance pipe for communicating surplus port B, which becomes a low pressure region during the heating cycle, with the low pressure gas pipe 17,
On the other hand, the capillary reach tube 20 is a resistance pipe for communicating with the low pressure gas pipe 17 the surplus port B which becomes a low pressure region during the cooling cycle and a high pressure region during the heating cycle.

Next, the operation of this air conditioner will be explained below with reference to FIGS. 1 and 2.

() In the case of full heating operation mode, the four-way switching valves _15-1 , _15-2 and the outdoor coil switching valve 19 are switched to the valve positions shown by solid lines in FIG. 1, and the three-way solenoid valve 24 is deenergized. to fully close the cooling expansion valve 3, and then close the three-way solenoid valve 25.
is energized to maintain the heating expansion valve 13 in a flow rate control state, and the second bypass passage 22 is connected to the proportional control valve 2.
3, the flow rate is controlled so that the high pressure becomes a predetermined value.

Thus, the high pressure leaving the compressor 9 is transferred to the high pressure gas pipe 16.
→High pressure port A of four-way switching valve _15-1 , _15-2 ,
A→Same ports D, D→Gas pipes 8, 8→Indoor coils 4, 4→Bypass circuits 6, 6→Liquid pipes 7, 7→
High pressure liquid pipe 14 → heating expansion valve 13 → outdoor coil 1
2 Port D of outdoor coil switching valve 19 → Low pressure port C → Low pressure gas pipe 17 → Accumulator 1
0 and returns to the suction port of the compressor 9, the indoor coils 4, 4 act on the condenser, and the outdoor coil 12 acts on the evaporator, respectively, so that the indoor coils 4, 4 and the outdoor coil 12 act on the evaporator.
The heat balance is balanced between

In the case of this heating operation, to stop the indoor units _2-1 and _2-2 , stop the fan 5 and at the same time move the corresponding four-way switching valves _15-1 and _15-2 to the valve positions indicated by the broken lines in Fig. 1. By switching the indoor coil 4,
4 is connected to the low pressure gas pipe 17 to prevent liquid refrigerant from accumulating in the coil.

() In the case of full cooling operation mode, the four-way switching valves _15-1 , _15-2 and the outdoor coil switching valve 19 are switched to the valve positions shown by broken lines in FIG. 1, and the three-way solenoid valve 24 is energized. The cooling expansion valve 3 is held in the flow rate control state, the three-way solenoid valve 25 is deenergized, the heating expansion valve 13 is fully closed, and the second bypass passage 22 is set to high pressure by the operation of the proportional control valve 23. The flow rate is controlled so that the pressure is at a predetermined value.

The high-pressure gas exiting the compressor 9 is routed through the high-pressure gas pipe 16 → the high-pressure port of the outdoor coil switching valve 19 → the same port D → the outdoor coil 12 → the first bypass circuit 21 →
Receiver 11 → High pressure liquid pipe 14 → Liquid pipe 7, 7 → Cooling expansion valve 3, 3 → Indoor coil 4, 4 → Gas pipe 8,
8→Four-way switching valve _15-1 , _15-2 ports D, D
→ Similarly, it flows in the order of low pressure ports C, C → low pressure gas pipe 17 → accumulator 10 and returns to the inlet of compressor 9, and the outdoor coil 12 acts on the condenser and the indoor coils 4, 4 act on the evaporator, respectively. The heat balance is balanced between

During the cooling operation, the indoor units _2-1 and _2-2 can be stopped by deenergizing the three-way solenoid valve 24 and fully closing the cooling expansion valve 3.

() In the case of the cooling/heating simultaneous operation mode, the four-way switching valve ₁₅₁ is switched to the valve position shown by the solid line in Fig. 1, and the three-way solenoid valve 24 of the indoor unit _2-1 is deenergized and its cooling expansion is activated. The valve 3 is fully closed, and the four-way selector valve _15-2 is switched to the valve position shown by the broken line in _FIG .
The three-way solenoid valve 24 is energized to maintain the cooling expansion valve 3 in the flow rate control state, the outdoor coil switching valve 19 is switched to the state indicated by the solid line in the figure, and the three-way solenoid valve 25 is de-energized. The heating expansion valve 13 is then fully closed, and the second bypass passage 22 is similarly brought into a state of flow rate control.

In this way, indoor unit _2-1 is in heating operation, and indoor unit _2-2 is in heating operation.
The cooling operation is performed respectively, and the compressor 9
The high-pressure gas that exits is transferred to high-pressure gas pipe 16 → four-way switching valve 1
5 High pressure port A of ₁ → same port D → indoor unit 2
- ₁ gas pipe 8 → same indoor coil 4 → same bypass circuit 6 → same liquid pipe 7 → high pressure liquid pipe 14 → indoor unit 2- ₂ liquid pipe 7 → same cooling expansion valve 3 → same indoor coil 4 → same The gas flows in the order of gas pipe 8 → port D of four-way switching valve _15-2 → low pressure port C → low pressure gas pipe 17 → accumulator 10 and returns to the suction port of compressor 9, and indoor coil 4 of indoor unit _2-1 The condenser and the indoor coil 4 of the indoor unit _2-2 act as an evaporator, and the heat balance between them is approximately balanced.

The difference between the amount of refrigerant required for heating and the amount of refrigerant required for cooling is adjusted by the receiver 11, while the outdoor coil 12 is connected to a low pressure line, and the inlet side is closed by a heating expansion valve 13. It becomes inactive.

Each operation mode has been explained above, but when the four-way switching valve _15-1 is in the cooling cycle state, it is in the valve operating state shown by the solid line in Fig. 2, facing the high pressure port A and outside the bowl-shaped valve. The internal space of the valve body formed in is connected to the low pressure port C via the capillary reach tube 18 connected to the port B.
A small amount of high-pressure gas constantly flows through the high-pressure gas pipe 16 connected to the high-pressure port A, so that the temperature of the high-pressure gas pipe 16 can be maintained at a high temperature, and the immediate warming performance at the start of operation is improved.

Of course, even if the high-pressure refrigerant turns into liquid and accumulates in the valve body of the four-way switching valve _15-1 , the liquid flows to the low-pressure gas pipe 17 while being depressurized through the capillary reach tube 18. There is no risk of stagnation in the switching valve, and liquid hammer at the start of operation is prevented.

The liquid hammer phenomenon occurs when the four-way selector valve _15-1 is switched to the heating operation side when the high-pressure gas pipe 16 is cooled by outside air and liquid accumulates during the cooling operation.

On the other hand, during cooling operation, the flow rate is controlled by the cooling expansion valve 3, so the degree of superheat at the coil outlet of each indoor unit _2-1 , _2-2 is controlled to an appropriate value, for example, 5°. - If ₁ , _2-2 and outdoor unit 1 are far apart and the connecting piping is long, there is a risk that the degree of superheat will further increase due to heat exchange with outside air at the compressor 9 inlet, and the discharge gas temperature will rise. .

In such a case, the four-way switching valves _15-1 , _15-2
The high-temperature, high-pressure gas inside the valve body facing high-pressure port A and port B at port D and low-pressure port C
The refrigerant gas is sufficiently liquefied through heat exchange with the low-pressure low-temperature gas flowing inside the bowl-shaped valve facing the refrigerant gas pipe 17, and is injected into the low-pressure gas pipe 17, making it possible to reduce the degree of superheating of the suction refrigerant gas to around 5°C. It is possible.

(Effects of the invention) The present invention has the configuration and operation detailed above, and in particular, when the heating operation is stopped, the refrigerant liquid is transferred to the capillary reach tube 18 in the four-way switching valves _15-1 and _15-2 . Therefore, the liquid can flow out into the low-pressure gas pipe 17, eliminating the liquid hammer that tends to occur when switching from cooling operation or heating stop to heating operation, which can cause damage to indoor units _2-1 and _2-2. This can increase the safety of the device.

Furthermore, it is possible to maintain a high pipe temperature of the high-pressure gas pipe 16 connected to the four-way switching valves _15-1 and _15-2 , thereby improving the instant heating performance at the start of heating operation.

Furthermore, as mentioned above, during cooling operation, liquid injection is performed in which the high-pressure liquid refrigerant is depressurized and injected into the low-pressure gas pipe 17 at the four-way switching valves _15-1 and _15-2 . It is possible to suppress an abnormal rise in the discharge pipe temperature by lowering the temperature.

[Brief explanation of the drawing]

FIG. 1 is a device circuit diagram according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of the four-way switching valve shown in FIG. 1, and FIG. 3 is a circuit diagram of a conventional air conditioner. 1...Outdoor unit, _2-1 , _2-2 ...Indoor unit, 3
...Air conditioning expansion valve, 4...Indoor coil, 7...Liquid pipe, 8...Gas pipe, 14...High pressure liquid pipe, _15-1 ,
_15-2 ...Four-way switching valve, 16...High pressure gas pipe,
17...Low pressure gas pipe, 18...Capillary reach tube.

Claims (1)

[Scope of utility model registration request] Each liquid pipe 7 of a plurality of indoor units _2-1 , _2-2 , etc., each equipped with a series refrigerant circuit including a cooling expansion valve 3 and an indoor coil 4, is connected to the high-pressure liquid pipe 14 of one outdoor unit 1, Each gas pipe 8 is switchably connected to a high pressure gas pipe 16 and a low pressure gas pipe 17 of the outdoor unit 1 through four-way switching valves _15-1 , _15-2 , etc. The surplus port of each of the four-way switching valves _15-1 , _15-2 , which switches to the low-pressure region during the heating cycle and heating cycle, is connected to the low-pressure gas pipe 17 by a capillary reach tube 18. Shape air conditioner.