JPS6034034B2 - Air conditioning equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air conditioning system, and its purpose is to prevent liquid compression in a compressor caused by switching the four-way valve when returning from defrosting to heating. The aim is to eliminate damage to the shaft and seizure of the shaft and bearings, create a compressor with a long life, and obtain an air-conditioning system with improved reliability.

An example of a conventional air conditioning system is a compressor 1 as shown in FIG.
, four-way valve 2, outdoor heat exchanger 3, capillary tube 4
, the indoor heat exchanger 5 is connected to the piping to form an air conditioning/heating refrigerant circuit. The four-way valve 2 is fixed to the base 17 with a metal fitting 18, the compressor 1 is elastically supported on the base 17 by a support 19, and the discharge pipe 13 and suction pipe 12 of the compressor 1 have sufficient elasticity. The bent portion 20 has
, 21 are connected to the four-way valve 2 through discharge/suction connecting pipes 22 and 23 provided with the four-way valve 2. As a result, the discharge/suction connecting pipes 22, 23 must be made longer, especially the suction pipe 1.
The diameter of the suction connecting pipe 23 connected to 0 and through which the low-pressure cold soot gas flows is large, and the volume of the cold soot passage becomes large.
On the other hand, during heating operation, defrosting operation begins due to frost formation on the outdoor heat exchanger 3, but during defrosting, cold soot containing unevaporated liquid is transferred to the indoor heat exchanger 5, the four-way valve 2, and the suction connection pipe 23. The liquid then reaches a gas-liquid separator 11 where it is separated into liquid and gas, and only the gas is sucked into the compressor 1.

However, when returning to heating, the four-way valve 2 is switched between the outdoor heat exchanger 3, which was on the high pressure side during defrosting, and the suction connecting pipe 23.
As the pressure inside the suction connecting pipe 23 increases rapidly,
Therefore, just before returning, the suction connecting pipe 2 with a large cold soot passage volume is
Since the liquid refrigerant remaining in the inside 3 is instantaneously turned into mist and the gas volume is reduced, the flow of cold soot becomes a mist flow with a large amount of liquid. This soot enters the gas-liquid separator 11, but since the liquid is a mist, it is not separated and is sucked into the compressor 1 as it is. On the other hand, since the internal temperature of the compressor has been sufficiently lowered by defrosting, the liquid medium that has been turned into a mist due to the heating inside the compressor cannot be gasified.

As a result, liquid compression occurred and the pressure inside the compressor cylinder rose sharply. This liquid compression is due to the liquid refrigerant remaining in the suction connection pipe, which has a large cold soot passage volume, and a sudden increase in pressure.It cannot be reduced during heating operation, and the pressure inside the compressor cylinder increases rapidly. This has caused problems such as damage to the discharge valve and seizure of the shaft and bearing, which shortens the life of the compressor. The present invention eliminates the above-mentioned drawbacks, and the structure thereof will be explained below based on the drawings shown as examples.

1 is a compressor, 2 is a four-way valve as a waist switching valve, 3 is an outdoor heat exchanger, 4 is a capillary tube as a pressure reducing device, and 5 is an indoor heat exchanger.

6 is a flow path switching valve, which connects the connecting pipe 7 as close as possible to the four-way valve 2.
The flow path switching valve 6 and the gas-liquid separator inlet 10 are connected by two suction connecting pipes 8 and 9, and the gas-liquid separator 11 and the compressor 1 are connected by a suction pipe 12. .

On the other hand, on the discharge side of the compressor 1, the compressor 1 and the four-way valve 2 are connected by a discharge pipe 13 and a discharge connecting pipe 14. In addition, the negative temperature sensing element 1 attached to the outdoor heat exchanger 3
5 connects the four-way valve 2 and the flow path switching valve 6 via the control circuit 16.
There is an electrical connection. During heating operation, as shown by the solid arrow in the figure, the high temperature and high pressure cold soot discharged from the compressor 1 passes through the discharge pipe 13, the discharge connection pipe 14, and the four-way valve 2.
The condensed and liquefied refrigerant reaches the indoor heat exchanger 5, is depressurized by the capillary tube 4, and is transferred to the outdoor heat exchanger 3.
After being gasified, it is sucked into the compressor 1 through the four-way valve 2, the flow path switching valve 6, the suction connection pipe 8, the gas-liquid separator 11, and the suction pipe 12.

Frost begins to form on the outdoor heat exchanger 3, and the negative temperature sensing element 15
When the temperature falls below the defrosting start temperature, the four-way valve 2 is switched by the control circuit 16, resulting in a defrosting cycle indicated by the broken line arrow, but the flow path switching valve 6 is not switched as shown in FIG. . When defrosting is completed and the temperature of the negative temperature sensing element 15 reaches the return temperature, the control circuit 16 causes the four-way valve 2 to
and the flow path switching valve 6 are switched at the same time, and at the same time the suction cycle is started, the flow of the suction cold soot is changed from the suction connection pipe 8 to the suction connection pipe 9. Next, one of the switching signals (
When returning to heating by a return signal from defrosting to heating, the air returns to the suction connection pipe 8.

Thereafter, this process is repeated as shown in FIG. When returning from defrosting to heating, the four-way valve 2 and the gas-liquid separator 11 are connected because the suction connection pipe 8 in which liquid-cooled soot remains is switched to the suction connection pipe 9 in which no liquid refrigerant exists. Only gas refrigerant is inside the pipe, which prevents liquid compression during return. Further, the liquid remaining in the suction connecting pipe 8 due to the low temperature is also gasified during the heating operation, and there is no liquid during the next operation of the flow path switching valve. As a result, the present invention can reliably prevent liquid compression even at low outside temperatures, where the risk of liquid compression was conventionally high. The same effect can be obtained even if the flow path switching valve is switched when the four-way valve is switched. The above explanation was based on an example using two suction connecting pipes, but even if there are two or more suction connecting pipes, it is possible to switch to the suction connecting pipe without residual liquid cooling soot when returning from defrosting to heating. A similar effect can be obtained. Since the present invention has the above-described configuration, it is possible to prevent liquid compression when returning from defrosting to heating, and it is possible to eliminate damage to the discharge valve and seizure of the shaft and bearing due to liquid compression. This has the effect of extending the life of the machine and improving its reliability as a heating and cooling system.

[Brief explanation of the drawing]

FIG. 1 is a heating and cooling cycle diagram as an embodiment of the present invention, where solid arrows indicate heating cycles and broken arrows indicate defrosting cycles. FIG. 2 is an operational diagram of a flow path switching valve and a four-way valve, and FIG. 3 is a heating and cooling cycle diagram showing a conventional example. 1...Compressor, 2...Cooling/heating switching valve, 3...Outdoor heat exchanger, 4...Pressure reducing device, 5...Indoor heat exchanger, 6...Flow path switching valve ,8,
9... Suction connection pipe, 11... Gas-liquid separator, 16...
・Control circuit. Figure 2 Figure 1 Figure 3

Claims (1)

[Claims] 1 It has an outdoor heat exchanger, a pressure reducing device, an indoor heat exchanger, a heating/cooling switching valve, and a compressor, and is used as a suction pipe connecting the cooling/heating switching valve and the compressor, with one end connected to the flow path switching valve as described above. A heating and cooling device comprising: a plurality of suction connecting pipes connected to a flow path switching valve; and a control circuit so as to switch the suction connecting pipes in response to at least one of switching signals from the cooling/heating switching valve.