JPH0282057A - Heat pump type air conditioner - Google Patents

Abstract

PURPOSE:To prevent a refrigerating machine oil from being discharged into a refrigerating cycle from an oil separator by installing a flow rate control valve to an oil return pipe which connects said oil separator with an suction pipe of a compressor and setting the opening of said flow rate valve so that its opening may be increased when the compressor comes to a halt. CONSTITUTION:Whether a compressor 1 is under operation or under suspension is decided by the step 30 when an oil return flow rate control means 21 detects a signal transmitted from a frequency control means 20. When the compressor is under suspension, the opening of an oil return flow rate control valve indicated in the step 34 is made full by an oil return flow rate control valve opening increment means 22. When it is under operation, a compressor operation frequency is detected in the step 31 while an oil return flow rate control valve opening is calculated based on the aforesaid data in the step 32, and an oil return flow rate control valve opening control is carried out in the step 32 as well. As described above, a refrigeration machine oil remaining in an oil separator can be easily returned to the compressor. It is, therefore, possible to prevent the refrigerating machine oil from being discharged into a cooling cycle from the oil separator when the compressor is called for to start again.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a heat pump type air conditioner having a function of recovering refrigerating machine oil discharged together with a refrigerant by an oil separator and returning it to a compressor.

BACKGROUND OF THE INVENTION In recent years, heat pump air conditioners have been equipped with an oil separator to prevent refrigerating machine oil from flowing into the refrigeration cycle.

Figure 3 is a refrigeration cycle diagram and block diagram of a conventional heat pump air conditioner. 1 is a compressor, 2 is an oil separator, 3 is a four-way valve that switches between cooling cycle and heating cycle/V, and 4 is condensation during cooling operation. 6 is a pressure reducing device, 6 is an indoor heat exchanger that acts as an evaporator during cooling operation, 7 is an accumulator, and these are connected to the discharge pipe 9 of the compressor 1. Refrigerant pipes 10, 11.12, 13, 14, 15. They are connected in an annular manner through the suction pipe 16 of the compressor 1 to form a refrigeration cycle. 20 is a frequency control means, which controls the operating frequency of the compressor 1 according to the air conditioning load. Reference numeral 17 denotes an oil return pipe connecting the oil separator 2 and the compressor suction pipe 16, with a flow control valve 8 interposed therebetween. 21 is frequency control means 2
The operating frequency value of the compressor 1 is received from 0, and the opening degree of the flow rate control valve 8 is controlled according to the amount of oil discharged from the compressor 1.

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

When the cooling system is connected, the high-temperature, high-pressure refrigerant gas compressed by the compressor 1 passes through the oil separator 2 and the four-way valve 3, and then passes through the outdoor heat exchanger 4.
It radiates heat and condenses into liquid. Furthermore, it expands adiabatically in the pressure reducing device 6 to become a low-temperature, low-pressure gas-liquid two-phase refrigerant, absorbs heat in the indoor heat exchanger 6, evaporates and gasifies, reaches the accumulator 7, and returns to the compressor 1, repeating the cycle. .

During heating operation, the high-temperature, high-pressure refrigerant gas compressed by the compressor 1 is sent to the oil separator 2, the four-way valve 3f, the passage, and the indoor heat exchanger 6.
It is condensed and liquefied. Furthermore, it is adiabatically expanded in the pressure reducing device 6,
It becomes 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, repeating the cycle υ.

The refrigerating machine oil discharged together with the refrigerant from the compressor 1 is separated in the oil separator 2, and the separated refrigerating machine oil is reduced in pressure and flow rate controlled by the flow rate control valve 18, and is returned to the compressor 1 through the oil return pipe 17. is led out to the suction pipe 16 and returned to the compressor 1.

FIG. 4 shows a flowchart of the control of the flow rate control valve 8, and the control of the flow rate control valve 8 will be explained in detail below.

In step 31, the compressor operating frequency of the compressor 1 is detected, and based on this data, in step 32, the opening degree of the oil return flow rate control valve is calculated, and in step 33, the opening degree of the oil return flow rate control valve is controlled.

Problems to be Solved by the Invention However, in the above configuration, when the compressor stops, the opening degree of the flow control valve maintains the opening degree corresponding to the frequency immediately before the stoppage, so after the compressor stops, The refrigerating machine oil stored in the oil separator becomes difficult to return to the compressor, and if the compressor is restarted in this state, an even larger amount of refrigerating machine oil will be discharged from the oil separator and cooled due to forcing during startup. The oil leaks into the cycle, causing a shortage of refrigerating machine oil held by the compressor 1, resulting in insufficient oil supply to the sliding parts of the compressor, and in the worst case, the compressor may stop, or the refrigerating machine oil may leak from the oil component The problem was that the water leaked into the refrigeration cycle, reducing heating and cooling capacity.

Means for Solving the Problems In order to solve the above problems, the heat pump air conditioner of the present invention is provided with a flow control valve in the oil return pipe that connects the oil separator and the suction pipe of the compressor to control the operation of the compressor. The opening of the flow rate control valve is set to a large degree when the flow rate control valve is stopped.

According to the above-described configuration, the present invention is configured such that when the compressor is on the clock, the opening degree of the flow control valve provided in the oil return pipe connecting the oil separator and the suction pipe of the compressor is fully opened when the compressor is stopped. The refrigerating machine oil stored in the oil separator is easier to return to the compressor, and the refrigerating machine oil is stored in the compressor, so when the compressor is restarted, the oil level in the compressor can be maintained at a predetermined level or higher. It becomes possible to improve the reliability of the compressor, and also suppress the leakage of refrigerating machine oil from the oil separator to the cooling cycle, which causes a decrease in heating and cooling capacity.

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 diagram of the refrigeration cycle of the heat pump type air conditioner according to the second embodiment of the misfire. Since the configuration and operation are the same as the conventional example, the explanation of the configuration and operation of the cooling cycle will be omitted. In particular, Here, a method of returning refrigerating machine oil that is different from the conventional example will be described below.

The refrigerating machine oil discharged together with the refrigerant from the compressor 1 is separated by an oil separator 2, and the separated refrigerating machine oil is passed through a flow control valve 8.
The oil is depressurized and the flow rate is controlled, and the oil is led out to the suction pipe 16 of the compressor 1 through a 17-ft oil return pipe, and then returned to the compressor 1. Next, regarding the control of the flow rate control valve 8, the flow rate control valve 8 shown in FIG.
The explanation will be given with reference to the flowchart of the control.

When the compressor 1 is turned ON-OFF, a signal from the frequency control means 20 is detected by the oil return flow rate control valve control means 21, and in step 30 it is determined whether the compressor 1 is in operation or stopped.

If the compressor 1 is stopped, the oil return flow rate control valve opening degree in step 34 is changed to the oil return flow rate control valve opening degree increasing means 2.
2, the compressor is fully opened, and if it is in operation, the compressor operating frequency is detected in step 31, and the opening degree of the oil return flow rate control valve is calculated based on this data in step 32.
Controls the opening of the oil return flow rate control valve.

As described above, according to this embodiment, when the compressor is stopped, the opening degree of the flow control valve provided in the oil return pipe connecting the oil separator and the compressor suction pipe is set to a large value when the compressor is stopped. The refrigerating machine oil stored in the oil separator is easier to return to the compressor, and the refrigerating machine oil is stored in the compressor. When the compressor is restarted, the oil level in the compressor can be maintained at a predetermined level or higher. It is possible to improve the reliability of the machine, and it is also possible to suppress the leakage of refrigerating machine oil from the oil separator to the cooling cycle, which causes a decrease in heating and cooling capacity.

Effects of the Invention As described above, the present invention provides a flow control valve in the oil return 7 pipe that connects the oil separator and the suction pipe of the compressor, and sets the opening degree of the flow control valve to a large value when the compressor stops operating. This makes it easier for the refrigerating machine oil stored in the oil separator to return to the compressor, and the refrigerating machine oil is stored in the compressor, making it difficult to maintain the oil level in the compressor above a specified level when the compressor is restarted. This makes it possible to improve the reliability of the compressor, and also to suppress the leakage of refrigerating machine oil from the oil separator to the cooling cycle, which causes a decrease in heating and cooling capacity.

[Brief explanation of the drawing]

10 is a cooling cycle diagram of a single-pump air conditioner according to an embodiment of the present invention, FIG. 2 is a flowchart 1 of flow control valve control according to an embodiment of the present invention, and FIG. 3 is a conventional diagram. FIG. 4 is a cooling cycle diagram of the beat pump type air conditioner in the example, and is a flow chart diagram of control of the flow rate control valve in the conventional example. 1...Compressor, 2...Oil separator, 8.
Mountain: Flow rate control valve. Name of Agent Patent Attorney Shigetaka Awano Haga 16 Funeral Map δ - Flow Control Valve Figure 2

Claims (1)

[Claims] Compressors, oil separators, four-way valves, outdoor heat exchangers, pressure reduction devices,
A refrigeration cycle is constructed by connecting an indoor heat exchanger and an accumulator in a ring, and a flow control valve is provided in the oil return pipe connecting the oil separator and the suction pipe of the compressor, and the operation of the compressor is stopped. A heat pump type air conditioner in which the opening degree of the flow rate control valve is set to be large at times.