JPH0285660A - Heat pump type air conditioner - Google Patents

Abstract

PURPOSE:To prevent a damage of the compressor by providing a means for controlling cross valves by which, during the defrosting, the refrigerant flowing out of an accumula tor is passed into an oil separator with heat storage tank and, after that, the refriger ant is sent through an oil return pipe to the compressor and by providing also a means for controlling oil return with a large valve opening for the return oil. CONSTITUTION:During the defrosting in the heating operation, the refrigerant gas compressed to a high temperature and high pressure by a compressor 1 does not enter an oil separator with heat storage tank 2 but flows through a first cross valve 8, bypass 31, line 33, four-way valve 3, and line 24 and into an indoor heat exchanger 6 where the refrigerant is liquefied by condensation. The refrigerant than flows through a fully opened expansion valve 5 and into an outdoor heat exchanger 4 which is thereby defrosted. The refrigerant next flows through a four-way valve 3, line 34, accumulator 7, line 30, third cross valve 10, bypass 28, and second cross valve 9 and into an oil separator with heat storage tank 2. The heat stored in the heat storage vessel 11 is then used to augment the dryness of the refrigerant, which, after being evaporated completely thereby, flows through an oil return pipe 32 and returns to the compressor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat pump type air conditioner having a function of defrosting an outdoor heat exchanger while continuing heating operation.

Conventional technology In recent years, heat pump type air conditioners have been developed to remove frost that forms on the outdoor heat exchanger during heating operation. A method of defrosting is adopted.

An example of the above-mentioned conventional double bomb type air conditioner will be described below with reference to the drawings.

FIG. 3 is a refrigeration cycle diagram of a conventional heat pump type air conditioner.

1 is a compressor, 2 is an oil separator, 3 is a four-way valve that switches between cooling and heating cycles, 4 is an outdoor heat exchanger that acts as a condenser during cooling operation, 5 is an expansion valve, and 6 is evaporation during cooling operation. 7 is an accumulator, which is connected to piping 21゜33.24.25.26.27
．． At 34.30, they are connected in a ring to form a refrigeration cycle.

32 is a pipe connecting the oil separator 2 and the suction side pipe 30 of the compressor 1, with an oil return valve 12 interposed therebetween.

A pressure sensor 13 is installed at the outlet of the outdoor heat exchanger 4 which serves as an evaporator during heating, and when the pressure falls below a set pressure, a defrosting operation detection means 41 determines whether defrosting is to be performed. 42 is an expansion valve control means for controlling the expansion valve 5, and 43 is an oil return valve control means for controlling the oil return valve 12.

The operation of the heat pump air conditioner configured as above will be described below.

During cooling operation, the high temperature, high pressure refrigerant gas compressed by the compressor 1 is passed through the oil separator 2. Passes through the four-way valve 3 and enters the outdoor heat exchanger 4
It radiates heat and condenses into liquid. It further expands adiabatically in the expansion valve 6 to become a low-temperature, low-pressure gas-liquid two-phase refrigerant, absorbs heat in the indoor heat exchanger 6, evaporates and gasifies, and reaches the accumulator 7.
Return to compressor 1 and repeat the cycle.

During heating operation, the high temperature, high pressure refrigerant gas compressed by the compressor 1 is passed through the oil separator 2. It passes through a four-way valve 3 and is condensed and liquefied in an indoor heat exchanger 6. The refrigerant then expands adiabatically in the expansion valve 6 to become a low-temperature, low-pressure gas-liquid two-phase refrigerant, absorbs heat in the outdoor heat exchanger 4, evaporates and gasifies, reaches the accumulator 7, and returns to the compressor 1. repeat.

The cold machine oil discharged together with the refrigerant from the compressor 1 is separated in the oil separator 2, and the separated refrigerating machine oil passes through the pipe 32, is depressurized by the oil return valve 12, is led out to the pipe 3o, and is sent to the compressor. It is returned to 1.

Next, the control of the defrosting operation during heating will be explained with reference to the flowchart of FIG. 4.

In step 61, it is detected whether the evaporator outlet pressure detected by the pressure sensor 13 is below a set value, and in step 62, it is determined whether defrosting operation is to be performed. When it is determined that the defrosting operation is to be performed, the opening degree of the expansion valve 6 is set and controlled to be fully open in step 63, and the opening degree of the oil return valve 12 is optimally set and controlled in step 64.

With the above control, the evaporation pressure increases and the outdoor heat exchange 'a
It becomes possible to remove the frost that has adhered to 4.

Problems to be Solved by the Invention However, with the above configuration, during defrosting operation, the opening degree of the expansion valve is increased, so a large amount of liquid refrigerant that could not be evaporated in the outdoor heat exchanger is transferred to the compressor. As a result, liquid compression is likely to occur, and in the worst case, the compressor may stop or be damaged.

In view of the above-mentioned problems, the present invention provides a heat pump air conditioner having a function of suppressing liquid refrigerant that could not be evaporated in the outdoor heat exchanger from returning to the compressor during defrosting operation. .

Means for Solving the Problems In order to solve the above problems, the heat pump air conditioner of the present invention has a first three-way valve installed between the compressor and the oil separator with a heat storage tank, and a first three-way valve installed between the oil separator with a heat storage tank. A second three-way valve installed at the outlet, a third three-way valve installed between the accumulator and compressor, a bypass circuit connecting the first three-way valve and the inlet of the four-way valve, and a bypass connecting the second three-way valve and the third three-way valve. An oil return pipe is installed to connect the circuit, the oil separator with heat storage tank, and the piping on the suction side of the compressor via an oil return valve, and the refrigerant is drawn out from the accumulator to the oil separator with heat storage tank during defrosting during heating. The system is equipped with a three-way valve control means for guiding the oil through the oil return pipe to the compressor, and an oil return control means for setting the opening degree of the oil return valve to a large degree.

According to the above-described configuration, the present invention provides heat transfer to the refrigerant discharged from the compressor through the oil separator with heat storage tank to the heat storage tank during normal air-conditioning/heating operation, and then transfers the heat to the indoor heat exchanger. The first three-way valve and the second three-way valve are set to introduce the refrigerant into the suction side of the compressor, and the third three-way valve is set to introduce the refrigerant drawn out from the accumulator into the suction side of the compressor. , the first three-way valve is switched so that the refrigerant discharged from the compressor is directly introduced into the indoor heat exchanger without passing through the oil separator with a heat storage tank, and the refrigerant discharged from the accumulator is introduced into the oil separator with a heat storage tank. By setting the second three-way valve and the third three-way valve so that the heat is introduced into the suction side of the compressor after being introduced into During defrosting operation, the heat in the heat storage tank is used to increase the dryness of the refrigerant flowing out of the accumulator, making it difficult for liquid compression to occur and improving the reliability of the compressor.

EXAMPLE Hereinafter, a heat pump type air conditioner according to an example of the present invention will be described with reference to the drawings. Fig. 1 is a refrigeration cycle diagram and a block diagram of a heat pump type air conditioner according to an embodiment of the present invention. Regarding the configuration of the refrigeration cycle, the same or equivalent parts as in the conventional example shown in Fig. 3 are indicated by the same symbols. Therefore, here, we will specifically explain in detail the configuration with additional additions to the conventional example.

A first three-way valve 8 is installed between the compressor 1 and the oil separator 2 with a heat storage tank, and is connected to a pipe 33 at the inlet of the four-way valve 3 through a bypass circuit 31. 9 is a second three-way valve, which connects the oil separator with heat storage tank 2 and the outlet piping 30 of the accumulator. The inlet piping 33 of the four-way valve 3 is connected to the piping 23. The bypass circuit was connected on the 2nd day. 10 is a third three-way valve, and the second three-way valve is a bypass circuit 28. It is connected to the accumulator V-7 by a pipe 30 and to the compressor 1 by a pipe 36. 11 is a heat storage tank, and 14 is a heat insulation tank that covers the heat storage tank.

44 is the first three-way valve 8. Second three-way valve9. This is a three-way valve control means that controls the third three-way valve 10.

The operation of the heat pump air conditioner configured as described above during cooling and heating will be explained.

During cooling, the high-temperature, high-pressure refrigerant gas compressed by the compressor 1 is transferred to the pipe 21. First three-way valve8. The oil passes through the pipe 22 and enters the oil separator 2 with a heat storage tank, transfers heat to the heat storage tank 11, and separates the refrigerating machine oil discharged together with the refrigerant. Next, the refrigerant gas is transferred to the second three-way valve 9° pipe 23. Piping 33. Four-way valve 3. The heat is radiated through the pipe 27 and is condensed and liquefied by the outdoor heat exchanger 4. Furthermore, it undergoes adiabatic expansion in the pressure reducing device 5 to become a low-temperature, low-pressure gas-liquid two-phase refrigerant, which absorbs heat in the indoor heat exchanger 6 and is evaporated and gasified to the pipe 24. Four-way valve 3. The cycle of reaching the accumulator 7 via the pipe 34 and returning to the compressor 1 is repeated.

During heating, the high-temperature, high-pressure refrigerant gas compressed by the compressor 1 is passed through the pipe 21. First three-way valve8. The oil passes through the pipe 22 and enters the oil separator 2 with a heat storage tank, transfers heat to the heat storage tank 11, and separates the refrigerating machine oil discharged together with the refrigerant. Next, the refrigerant gas is supplied to the second three-way valve 9. Piping 23, piping 33. Four-way valve 3. Piping 2
4f, it is condensed and liquefied in the indoor heat exchanger 6. Furthermore, it undergoes adiabatic expansion in the pressure reducing device 6 to become a low-temperature, low-pressure gas-liquid two-phase refrigerant, which absorbs heat in the outdoor heat exchanger 4 and is evaporated and gasified to the piping 27. The cycle of passing through the four-way valve 3 to the accumulator 7 and returning to the compressor 1 is repeated.

The oil separated by the oil separator 2 with a heat storage tank is transferred to the pipe 32.
The oil is returned to the compressor 1 through the oil return valve 12.

During defrosting operation during heating, the high-temperature, high-pressure refrigerant gas compressed by the compressor 1 does not enter the oil separator with heat storage tank 2, but instead enters the first oil separator.
Three-way valve 8. Bypass circuit 31. Piping 33. Four-way valve 3. It passes through the pipe 24 and is condensed and liquefied in the indoor heat exchanger 6.

Further, the air passes through the expansion valve 6, which is set to be fully open, and enters the outdoor heat exchanger 4 to remove adhering frost. Next, four-way valve 3
．． Piping 34, accumulator 7, piping 30. Third three-way valve 10° bypass circuit 28. It passes through the second three-way valve 9 and enters the oil separator 2 with a heat storage tank. At this time, the heat stored in the heat storage tank 11 is used to increase the degree of dryness of the refrigerant, and the refrigerant is completely evaporated and returned to compression@1 via the oil return pipe 32.

Next, while referring to the flowchart in FIG. 2, the expansion valve 5 during defrosting operation will be explained. Oil return valve 12 and three-way valve 8, 9.1
0 control will be explained in more detail.

In step 61, it is detected whether the evaporator outlet pressure detected by the pressure sensor 13 is below a set value, and in step 62, it is determined whether to perform defrosting operation. If it is determined that defrosting operation is to be performed, the opening degree of the expansion valve 6 is set and controlled to be fully open in step 63, and the opening degree of the oil return valve 12 is fully opened in step 64. Return all the oil stored in 2 [7-C to compressor 1. Next, the first three-way valve 8. Second three-way valve9. The third three-way valve 1o is controlled by the three-way valve control means 44 so as to function as a defrosting circuit.

As described above, according to this embodiment, the first three-way valve 8 is installed between the compressor and the oil separator 2 with a heat storage tank. A second three-way valve 9° installed at the outlet of the oil separator 2 with a heat storage tank.A third three-way valve 1o and a first three-way valve 8 installed between the accumulator 7 and the compressor 10.
and the bypass circuit connecting the inlet of the four-way valve 3, the bypass circuit connecting the second three-way valve 9 and the third three-way valve 1°, the oil separator with heat storage tank 2, and the piping 3o on the suction side of the compressor 1 as an oil return valve. 1
An oil return pipe 32 is provided, which connects the refrigerant from the accumulator 7 to the oil separator 2 with a heat storage tank during defrosting during heating, and then leads the refrigerant to the compressor 1 through the oil return pipe 32. Three-way valve control means 44 and oil return valve 1
By providing the oil return valve control means 43 that sets the opening degree of the oil separator 2 to full open, the refrigerant having a low degree of dryness flowing out from the outdoor heat exchanger 4 is transferred to the heat stored in the heat storage PB11 of the oil separator 2 with a heat storage tank. The dryness can be increased by
Liquid compression is less likely to occur, and the reliability of the compressor 1 can be improved.

Effects of the Invention As described above, the present invention provides a first three-way valve installed between a compressor and an oil separator with a heat storage tank, a second three-way valve installed at the outlet of the oil separator with a heat storage tank, an accumulator and a compressor. A third three-way valve installed between the two, a Paipanu circuit that connects the inlets of the first three-way valve and the four-way valve, a bypass circuit that connects the second three-way valve and the third three-way valve, an oil separator with a heat storage tank, and a compressor. An oil return pipe is installed that connects the suction side pipe of the compressor via an oil return valve, and after passing the refrigerant drawn from the accumulator to the oil separator with a heat storage tank during defrosting during heating, the refrigerant is returned to the compressor via the oil return pipe. By providing a three-way valve control means for leading out the oil return valve, and an oil return valve control means for setting the opening degree of the oil return valve to a large value,
The heat stored in the oil separator with heat storage tank during normal heating operation is used to increase the dryness of the refrigerant flowing out from the outdoor heat exchanger during defrosting operation, making it difficult for liquid compression to occur and increasing the dryness of the compressor. Improved reliability.

[Brief explanation of drawings]

FIG. 1 is a refrigeration cycle diagram of a heat pump air conditioner according to an embodiment of the present invention, and FIG. 2 is a flowchart diagram of the same.
FIG. 3 is a refrigeration cycle diagram of a conventional heat pump air conditioner, and FIG. 4 is a flow chart thereof. DESCRIPTION OF SYMBOLS 1... Compressor, 2... Oil separator with heat storage tank, 8... First three-way valve, 9... Second three-way valve, 10. ...Third three-way valve. Name of agent: Patent attorney Shigetaka Awano and one other person Suichi Jinzumiori 9-Tsubasa 23t, 1? @2 Figure 3

Claims (1)

[Claims] A refrigeration cycle is constructed by connecting a compressor, an oil separator with a heat storage tank, a four-way valve, an outdoor heat exchanger, an expansion valve, an indoor heat exchanger, and an accumulator in a ring, and the compressor and the oil separator with a heat storage tank are connected in a ring. a first three-way valve installed between the two, a second three-way valve installed at the outlet of the oil separator with a heat storage tank, a third three-way valve installed between the accumulator and the compressor, and the first three-way valve. A bypass circuit connecting the inlet of the four-way valve, a bypass circuit connecting the second three-way valve and the third three-way valve, and piping on the suction side of the oil separator with a heat storage tank and the compressor are connected through an oil return valve. A three-way valve control means is provided with an oil return pipe connecting the refrigerant to the compressor via the oil return pipe after passing the refrigerant drawn from the accumulator to the oil separator with a heat storage tank during defrosting during heating. . A heat pump type air conditioner, comprising: an oil return valve control means for setting a large opening degree of the oil return valve.