JPH01302072A - Heat pump type air conditioner - Google Patents

Abstract

PURPOSE:To improve the reliability of a compressor by largely setting the opening of a flow control valve provided in a refrigerant tube for connecting an oil separator to the compressor for a predetermined period of time when an oil level in the compressor becomes lower than a predetermined value. CONSTITUTION:Refrigerator oil discharged together with refrigerant from a compressor 1 is separated by an oil separator 2, reduced under pressure through a refrigerant tube 12 b y a flow control valve 8, introduced to a suction tube 11 through a refrigerant tube 13, and returned to the compressor 1. An oil level detection sensor provided in the compressor 1 detects the oil level of the compressor 1, detects the operating frequency of the compressor 1 if it is a predetermined level or more, calculates the opening of the valve 8 on the basis of this frequency, and controls the valve to a determined opening. If it is the predetermined level or less, the opening of the valve is once set to fully open, the the valve 8 is then controlled. Thus, the oil level in the compressor 1 can be held at the predetermined level or more even in any operating condition.

Description

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

2. Description of the Related Art In recent years, pump-type air conditioners have been equipped with an oil separator to prevent refrigerating machine oil from flowing out from the compressor from flowing into the refrigeration cycle.

An example of the conventional heat pump type air conditioner mentioned above 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 cycle and heating cycle, 4 is an outdoor heat exchanger that acts as a condenser during cooling operation, 6 is a pressure reduction device, and θ is an evaporator during cooling operation 7 is an accumulator, and these are connected in a ring to form a refrigeration cycle.

Reference numeral 9 denotes a variable frequency power supply, which controls the operating frequency of the compressor 1 according to the air conditioning load. Reference numerals 12 and 13 are refrigerant pipes connecting the oil separator 2 and the suction pipe 11, with a flow control valve 8 in between.
through.

20 is a frequency detection means for detecting the operating frequency of the compressor 1 from the variable frequency power source 9; 21 is a flow rate control valve control means for calculating and controlling the opening degree of the flow rate control valve 8 based on the detected frequency; be.

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. 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 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 pressure reducing device 5 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 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 passed through the refrigerant pipe 12.
The refrigerant is depressurized by the flow rate control valve 8, is led out to the suction pipe 11 through the refrigerant pipe 13, and is returned to the compressor 1.

Next, the control of the flow rate control valve 8 will be explained in more detail with reference to the flowchart shown in FIG.

In step 4o, the operating frequency of the compressor 1 is detected, in step 41, the opening of the flow control valve 8 is calculated based on this frequency, and in step 42, the opening of the flow control valve 8 is adjusted to the opening determined in step 41. Control.

Problems to be Solved by the Invention However, with the above configuration, oil separation occurs when the difference between high and low pressures is small or at startup when a large amount of refrigerating machine oil flows out from the compressor, regardless of the operating frequency of the compressor. Refrigerating machine oil accumulates in the chamber, but since the flow control valve opening cannot be controlled to a correspondingly large opening, there is little refrigerating machine oil returning to the compressor, resulting in a shortage of refrigerating machine oil in the compressor, and damage to sliding parts. In the worst case, the compressor may stop, or refrigeration oil may leak into the refrigeration cycle through the oil separator, reducing heating and cooling performance.

In view of the above-mentioned problems, the present invention aims to improve the reliability of the compressor by maintaining the oil level in the compressor at a predetermined level or higher under any operating conditions. This product provides a heat pump type air conditioner equipped with a function that suppresses the outflow of machine oil.

Means for Solving the Problems In order to solve the above problems, the heat pump type air conditioner of the present invention includes a flow control valve in the refrigerant pipe connecting the oil separator and the suction pipe of the compressor, and an oil level detection sensor in the compressor. and a flow control valve control means for setting the opening degree of the flow control valve to be larger than during normal operation for a predetermined period of time when the oil level in the compressor becomes lower than a predetermined position.

With the above-described configuration, the present invention automatically sets the opening degree of the flow control valve to be larger than that during normal operation when the oil level of the compressor falls below a predetermined level under any operating conditions. The refrigeration oil stored in the oil separator is easier to return to the compressor, and as a result, the oil level in the compressor can be maintained above a certain level, making it possible to improve the reliability of the compressor. In addition, leakage of refrigerating machine oil into the refrigeration cycle, which causes a decrease in heating and cooling capacity, is also suppressed.

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 air conditioner according to an embodiment of the present invention, and the configuration of the refrigeration cycle is as follows:
This is the same as the conventional example shown in FIG. The same or equivalent parts as in FIG. 2 are indicated by the same symbols, so a description of the configuration of the refrigeration cycle will be omitted.

Therefore, the configuration for controlling the flow rate control valve 8 will be described below.

14 is an oil level detection sensor, 22 is a compressor oil level detection means,
2Q is a frequency detection means, and 21 is a flow rate control valve control means that controls the flow rate control valve 8 based on the compressor oil level or the compressor operating frequency.

Regarding the heat pump type air conditioner configured as above, the operation of the flow rate control valve 8 will be explained below using FIG. 1 and FIG. 2.

FIG. 2 is a flowchart of control of the flow rate control valve 8.

In step 6o, the oil level of the compressor 1 is detected by the oil level detection sensor provided in the compressor 1, and in step 61, it is determined whether the oil level of the compressor 1 is normal, that is, whether it is above a predetermined level, If the oil level is normal, the operating frequency of the compressor 1 is detected in step 52, and the opening degree of the flow control valve 8 is calculated based on this frequency in step 53.
4, the flow rate control valve 8 is opened at the opening determined in step 63.
control.

If the oil level of the compressor 1 is below a predetermined level in step 51, the flow rate control valve opening degree is set to full open in step 55, and the flow rate control valve 8 is controlled in step 64.

As described above, according to this embodiment, the oil level detection sensor 14 is provided in the compressor 1, and when the oil level in the compressor 1 becomes lower than a predetermined position, the flow rate control valve 8 is opened for a predetermined period of time. By fully opening the oil level in the compressor 1, the oil level in the compressor 1 can be maintained at a predetermined level or higher under any operating conditions, making it possible to improve the reliability of the compressor 1 and to prevent the cooling and heating capacity from decreasing. It is also possible to suppress the leakage of refrigerating machine oil into the refrigeration cycle.

Effects of the Invention As described above, the present invention provides a flow control valve in the refrigerant pipe connecting the oil separator and the suction pipe of the compressor, and an oil level detection sensor in the compressor, so that the oil level in the compressor is lower than a predetermined position. By providing a flow control valve control means that sets the opening degree of the flow control valve to be larger than during normal operation for a predetermined period of time when the flow rate control valve becomes low.
The oil chamber inside the compressor can be maintained at a predetermined level or higher under any operating conditions, making it possible to improve the reliability of the compressor and preventing refrigeration oil from leaking into the refrigeration cycle, which can cause a decline in heating and cooling capacity. It is also possible to suppress it.

[Brief explanation of the drawing]

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. 1...Compressor, 2...Oil separator, 3.
...Flow control valve. Name of agent: Patent attorney Toshio Nakao and 1 other person1-
11 pressure J1 machine 2- series +) 11 machines 8-・- flow reduction valve Fig. 1 Fig. 2 Fig. 3

Claims (1)

[Claims] Compressors, oil separators, four-way valves, outdoor heat exchangers, pressure reduction devices,
A refrigeration cycle is configured by connecting an indoor heat exchanger and an accumulator in a ring, a flow control valve is provided in a refrigerant pipe connecting the oil separator and the suction pipe of the compressor, and an oil level detection sensor is provided in the compressor. and a flow control valve control means for setting the flow rate control valve to a higher degree than during normal operation for a predetermined period of time when the oil level in the compressor becomes lower than a predetermined position. Heat pump air conditioner.