JP3295441B2 - Refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus having a refrigerating cycle in which a compressor, a condenser, a decompression device, and an evaporator are connected by a refrigerant circulation pipe.

[0002]

2. Description of the Related Art In a refrigeration cycle, a compressor plays a role of changing a low-temperature low-pressure refrigerant to a high-temperature high-pressure state, and is a device that can be said to be the heart.

[0003] By the way, at the time of refrigerant compression, the compression mechanism portion repeatedly rotates and slides at high speed.
Although lubricating oil is indispensable, in a refrigeration cycle, since the lubricating oil and the refrigerant are mixed in the same cycle, the situation where the refrigerant is dissolved in the lubricating oil is inevitable. In this case, since the viscosity of the lubricating oil in which the refrigerant is dissolved decreases, the lubricating oil itself has a great effect on the lubricity and sealability, and the compressor is operated at a low temperature when the refrigerant and the lubricating oil tend to separate into two phases. In the start-up of the compressor, the liquid return is sent to the lubricating portion of the compression mechanism portion, which causes wear of the rotating portion and the sliding portion for the compressor. For this reason, it is important for the refrigeration system to know the amount of refrigerant contained in the lubricating oil (hereinafter, referred to as “dilution degree”).

Conventional methods for measuring the degree of dilution include a method of extracting the lubricating oil from the compressor, a method of obtaining the degree of dilution from the refrigerant dissolution characteristics of the lubricating oil, and a method of providing a detector for measuring the degree of dilution in the compressor. Is mentioned.

[0005] A method of extracting the lubricating oil is as follows. A lubricating oil extracting tank is connected to the bottom of the compressor, and the lubricating oil is guided to the tank. Is a method of calculating the degree of dilution by using the calculation formula.

Dilution degree = {(refrigerant weight) / (refrigerant weight + lubricating oil weight)} × 100 [wt%] The method based on refrigerant solubility characteristics measures lubricating oil temperature and compressor discharge side pressure. The dilution degree is obtained from the refrigerant solubility characteristic of the lubricating oil shown in FIG. 6. When the cycle is stable, an almost accurate dilution degree is obtained.

The method of providing a detecting device is a method of providing a device for measuring the degree of dilution in the lubricating oil in the compressor. This method can always measure the degree of dilution, and is the most accurate method for detecting the degree of dilution. A method.

[0008]

However, each of these methods has the following disadvantages and problems.

The method of extracting the lubricating oil is a method of actually extracting the lubricating oil and investigating it. Therefore, it takes time and effort, and when the cycle such as when starting the compressor is transient,
Since the mixing state of the lubricating oil and the refrigerant is not uniform, there are problems such as large variations in measured values.

In the method based on the refrigerant solubility characteristic, although there is no troublesome operation like the above-described method of extracting the lubricating oil, in a transition period, the discharge pressure often rises rapidly while the lubricating oil temperature is still low. Discharge pressure is Pd
2. When the lubricating oil temperature is To1, the dilution degree may be 100 [wt%], which is not practically possible.

In addition, the method of providing the detection device requires a device for measuring the dilution degree to be provided in the lubricating oil in the compressor, so that the mounting position of the measuring device is limited and difficult, and the mounting of the measuring device is difficult. For this reason, it is necessary to perform processing such as drilling and filling holes in the compressor, which may impair the reliability of the compressor itself and the entire refrigeration cycle, such as leakage of refrigerant or lubricating oil therefrom.

The present invention has been made in view of the above, and an object of the present invention is to provide a refrigeration apparatus capable of accurately measuring the degree of dilution without impairing the reliability of the compressor itself and the entire refrigeration cycle. To provide.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a liquid return amount provided in a refrigerant circulation pipe near a suction port of a compressor and detecting a liquid return amount of the refrigerant to the compressor. Detecting means, and calculating means for calculating the degree of dilution of the lubricating oil in the compressor by the refrigerant based on the detected liquid return amount.
The calculating means records the relationship between the liquid return amount and the dilution degree.
The function storage unit and the liquid return amount detection unit
The correlation stored in the function storage unit from the liquid return amount
Having a dilution degree calculation unit for obtaining the dilution degree using the
Features.

[0014]

In the refrigerating apparatus according to the present invention, paying attention to the fact that there is a certain correlation between the amount of refrigerant returned to the compressor and the degree of dilution, the refrigerant is returned to the compressor. Liquid return amount detecting means for detecting the amount is provided in the refrigerant circulation pipe near the suction port of the compressor, and the degree of dilution of the lubricating oil in the compressor by the refrigerant is determined based on the detected amount of liquid return. .

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a refrigeration cycle in a refrigeration apparatus according to one embodiment of the present invention. In the figure, 1 is a compressor, 3 is a condenser, 5 is a decompression device, 7 is an evaporator, and is connected by a refrigerant circulation pipe 9. In addition, a liquid return amount detection unit 11 is provided in the refrigerant circulation pipe 9 near the suction port of the compressor 1, and an operation unit 13 is connected to the liquid return amount detection unit 11.

The liquid return amount detector 11 detects the liquid return amount of the refrigerant to the compressor 1, and is connected to a pair of conductive electrode support rods 14 alternately and electrically as shown in FIG. By disposing the stacked electrode 15 (see FIG. 2B) in the refrigerant circulation pipe 9, a configuration equivalent to connecting a capacitor in parallel to the electrode support rod 14 is obtained (see FIG. 2C). ,
The amount of the liquid refrigerant 17 is detected as a change in capacity, and is output by the converter 19 as a voltage value. That is, as shown in FIG. 3, the liquid return amount detector 11 has a characteristic that the output voltage increases in proportion to the increase in the liquid return amount. In FIG. 2, reference numeral 21 denotes an insulator.

The calculation unit 13 calculates the degree of dilution based on the detection result of the liquid return amount detection unit 11, and the function storage unit 2
3 and a dilution degree calculation unit 25. The function storage unit 23 stores the relationship between the liquid return amount and the dilution degree. That is, when the refrigeration cycle is operated,
The change of the liquid return amount and the dilution degree with respect to time is shown in FIG.
When the relationship between the two is arranged for each certain time unit, the correlation shown in FIG. 5 can be obtained in which the dilution is high when the liquid return amount is large. They remember the relationship. Dilution degree calculator 2
Numeral 5 is for obtaining the degree of dilution from the detected liquid return amount using the correlation stored in the function storage unit 23.

Therefore, according to the present embodiment, the compressor 1
The liquid return amount detection unit 11 is provided in the refrigerant circulation pipe 5 near the suction port on the low-temperature and low-pressure side, and the dilution degree calculation unit 25 uses the detected liquid return amount according to the correlation stored in the function storage unit 23. Since the degree of dilution is determined, there is no need to process the compressor itself as in the past, and the degree of dilution can be determined regardless of the state of the refrigeration cycle, such as a transition period or a stable period. While maintaining the reliability of the compressor,
The dilution degree can be easily measured.

[0020]

As described above, according to the present invention, attention has been paid to the fact that there is a certain correlation between the amount of refrigerant returned to the compressor and the degree of dilution, and Liquid return amount detection means for detecting the liquid return amount is provided in the refrigerant circulation pipe near the suction port of the compressor, and the degree of dilution of the lubricating oil in the compressor by the refrigerant is determined based on the detected liquid return amount. Therefore, the dilution degree can be accurately measured without impairing the reliability of the compressor itself or the entire refrigeration cycle.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a liquid return amount detection unit in the embodiment.

FIG. 3 is a diagram illustrating characteristics of the liquid return amount detection unit.

FIG. 4 is a diagram showing an output change characteristic and a dilution degree change characteristic of a liquid return amount detection unit after the start of a refrigeration cycle operation.

FIG. 5 is a diagram illustrating a change in an output of a liquid return amount detection unit with respect to a dilution degree.

FIG. 6 is a diagram for explaining a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 3 Condenser 5 Pressure reducing device 7 Evaporator 9 Refrigerant circulation pipe 11 Liquid return amount detection part 13 Operation part 14 Electrode support rod 15 Stacked electrode 17 Liquid refrigerant 19 Converter 21 Insulator 23 Function storage part 25 Dilution degree calculation Department

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F25B 43/00-49/04

Claims (1)

(57) [Claims] 1. A liquid return amount detecting means provided in a refrigerant circulation pipe near a suction port of a compressor, for detecting a liquid return amount of a refrigerant to a compressor, and compressing based on the detected liquid return amount. Calculation means for determining the degree of dilution of the lubricating oil in the machine with the refrigerant.
The calculating means records the relationship between the liquid return amount and the dilution degree.
The function storage unit and the liquid return amount detection unit
The correlation stored in the function storage unit from the liquid return amount
A refrigeration apparatus comprising a dilution degree calculating unit for obtaining a dilution degree using a clerk .