JPS6155020B2 - - 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 valves and seizure between shafts and bearings, to create a compressor with a long life, and to obtain air-conditioning equipment with improved reliability.

As shown in Fig. 4, an example of a conventional air-conditioning system has a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, a capillary tube 4, and an indoor heat exchanger 5 connected through piping to form an air-conditioning/heating refrigerant circuit. It consists of The four-way valve 2 is fixed to a base 25 with a metal fitting 26, and the compressor 1 is elastically supported on the base 25 by a support 27.
0 is bent part 2 so as to have sufficient elasticity.
It is connected to the four-way valve 2 through discharge/suction connecting pipes 30 and 31 provided with pipes 8 and 29, respectively. As a result,
The discharge/suction connecting pipes 30 and 31 have to be long, and in particular, the diameter of the suction connecting pipe 31 connected to the suction pipe 10 and through which low-pressure refrigerant gas flows is large, resulting in a large refrigerant passage volume.

On the other hand, during heating operation, defrosting operation begins due to frost formation on the outdoor heat exchanger 3, but during defrosting, the refrigerant containing unevaporated liquid is transferred to the indoor heat exchanger 5, the four-way valve 2, and the suction connection pipe. 31 and reaches the gas-liquid separator 7, where it is separated into liquid and gas, and only the gas is sucked into the compressor 1.
However, when returning to heating, the switching of the four-way valve 2 connects the outdoor heat exchanger 3, which was on the high pressure side during defrosting, with the suction connecting pipe 31.
The internal pressure rises rapidly, and as a result, the liquid refrigerant remaining in the suction connection pipe 31, which has a large refrigerant passage volume, is instantaneously turned into a mist just before the return, and the gas volume is reduced, so that the flow of refrigerant is reduced to the same level as the liquid volume. A large amount of mist flows. This refrigerant enters the gas-liquid separator 7, 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 compressor internal temperature has been sufficiently lowered by defrosting, the liquid refrigerant 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 caused by the liquid refrigerant remaining in the suction connection pipe 31, which has a large refrigerant passage volume, and cannot be avoided during heating operation.
The pressure inside the compressor cylinder increases rapidly, resulting in damage to the discharge valve, seizing of the shaft and bearing, and other shortcomings such as shortening the life of the compressor.

The present invention eliminates the above-mentioned drawbacks,
The configuration will be explained below based on the drawings shown as examples.

1 is a compressor, 2 is a four-way valve as a cooling/heating 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. The four-way valve 2 has a suction connection pipe 6, a gas-liquid separator 7, and a suction pipe 8.
It is connected to the compressor 1 via a discharge pipe 9 to form a suction passage for the compressor 1, and is connected to the compressor 1 via a discharge pipe 9 to form a discharge passage for the compressor 1.
The compressor 1 includes a motor 10 and a compression mechanism 11. The piston 12 is attached to the drive shaft 13 of the motor 10, rotates along the inner wall of the cylinder 14, and divides the inside of the cylinder 14 into a suction chamber 15 and a compression chamber 16. Suction port 17 between suction chamber 15 and suction pipe 8
There is a discharge valve 1 between the compression chamber 16 and the discharge chamber 18.
There are 9. An on-off valve 20 is interposed between the suction port 17 and the discharge chamber 18, and is opened and closed by a coil 21. The four-way valve 2 and the coil 21 are a control circuit 22
It is electrically connected to the negative temperature sensing element 23 via.

During heating operation, when frost begins to form on the outdoor heat exchanger 3 and the temperature of the negative temperature sensing element 23 falls to the defrosting start temperature, the four-way valve 2 is switched by the control circuit 22, and the heating is started as indicated by the solid line arrow. The cycle then becomes a defrost cycle as indicated by the dashed arrow. At this time,
The on-off valve 20 remains closed. The refrigerant compressed in the compression chamber 16 by the rotation of the piston 12 of the compressor 1 reaches the discharge chamber 18 via the discharge valve 19, and then reaches the outdoor heat exchanger 3 via the discharge pipe 9 and the four-way valve 2. Here, the frost is melted and liquefied. The condensed refrigerant is depressurized by the capillary tube 4 and reaches the indoor heat exchanger 5, but during defrosting, heat is not exchanged sufficiently here, and the unevaporated liquid is transferred to the four-way valve 2 and the suction connection pipe 6.
and then reaches the gas-liquid separator 7. Here, the liquid is separated, and only the gas passes through the suction pipe 8, the suction port 17, the suction chamber 15, and is sucked into the compressor 1.

When the frost on the outdoor heat exchanger 3 melts and the temperature of the negative temperature sensing element 23 reaches the heating return temperature or higher, the control circuit 22 switches the four-way valve 2, and
At the same time, the coil 21 is also energized and the on-off valve 20 is opened. As a result, high-pressure gas refrigerant enters the suction pipe (from the four-way valve 2 to the suction pipe 8) from the outdoor heat exchanger 3 and the discharge chamber 18, which is the high-pressure part of the compressor 1. The residual liquid refrigerant that remains when returning to heating is confined within the pipes and does not turn into mist and flow out instantly. When the on-off valve 20 is open, the amount of refrigerant sucked through the suction pipe 8 is small because the discharge chamber 18, which is a high pressure part, and the suction port 17, which is a low pressure part, of the compressor 1 are bypassed. Therefore, the liquid refrigerant within the suction connection pipe 6 remains as it is within the pipe. After a certain period of time (T) has passed after the return, and the pressure inside the suction pipe becomes uniform, the power to the coil 21 is cut off, and the on-off valve 20 closes due to its own weight.
Because the pressure is uniform and the gas flow rate is slow, the liquid refrigerant in the suction connection pipe 6 does not flow out suddenly, but gradually flows out as a liquid, and the liquid is separated by the gas-liquid separator 7. Only gas is inhaled. Therefore, liquid compression does not occur when returning to heating. Note that FIG. 2 shows the operations of the four-way valve 2 and the on-off valve 20. FIG. 3 shows another embodiment in which even if the compression chamber 18 and suction pipe 8 are bypassed outside the compressor 1 via the on-off valve 24, liquid compression at the time of return can be prevented.

As described above, according to the present invention, the liquid compression that occurs when returning from defrosting to heating can be reduced without changing the size of the compressor or without causing vibrations in the suction connection pipe and discharge connection pipe. By eliminating damage to the discharge valve and seizing of the shaft and bearing, the lifespan and reliability of the compressor, that is, the air-conditioning equipment, has been improved.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant circuit diagram showing an embodiment of the present invention;
FIG. 2 is an operational relationship diagram of a four-way valve and an on-off valve, FIG. 3 is a refrigerant circuit diagram showing another embodiment of the present invention, and FIG. 4 is a refrigerant circuit diagram showing a conventional example. 1... Compressor, 2... Cooling/heating switching valve, 3... Outdoor heat exchanger, 4... Pressure reducing device, 5... Indoor heat exchanger, 7... Gas-liquid separator, 8... Suction pipe , 14...
...Cylinder cylinder, 17...Suction port, 18...Discharge chamber, 22...Control circuit.

Claims (1)

[Claims] 1. An outdoor heat exchanger, a pressure reduction device, an indoor heat exchanger, a gas-liquid separator, a compressor, a suction pipe connecting the gas-liquid separator and a cylinder inside the compressor, and the compressor. Control includes an on-off valve that bypasses the internal discharge chamber, opens the on-off valve at the same time as switching the heating/cooling switching valve in response to a heating/cooling switching signal when returning from defrosting to heating, and closes the on-off valve after a certain period of time. A heating and cooling system equipped with a circuit.