JPH09264769A - Apparatus for measuring lubricant return amount of refrigerating cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for measuring the amount of returned lubricant to a compressor by circulating in a refrigerating cycle. SOLUTION: In a refrigerating cycle, refrigerant becomes gas state immediately before a compressor, lubricant partly flows along the tube wall in liquid state, and is partly carried as mist to gas refrigerant. The lubricant is separated to the liquid state part and mist part, the flow of the lubricant is made to liquid droplets. The number of the droplets per unit time is measured to measure the amount of the former, and the amount of the latter is measured by a light scattering method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the amount of lubricating oil that circulates in a refrigeration cycle and returns to a compressor to evaluate the performance of the refrigeration cycle.

[0002]

2. Description of the Related Art The amount of lubricating oil discharged from a compressor for a refrigerating machine and circulating in a refrigerating cycle is one of the important characteristics for evaluating the performance of the compressor and is measured as an oil circulation rate. This is measured as a weight percentage concentration of the lubricating oil contained in the liquid refrigerant in a place where the refrigerant is circulated as a liquid in the refrigeration cycle, that is, immediately before the expansion valve.

On the other hand, what the present invention seeks to measure is the amount of lubricating oil that circulates in the refrigeration cycle and actually returns to the compressor.

The refrigerant vaporizes after passing through the expansion valve and returns to the compressor as a gas. However, since the lubricating oil does not vaporize, it separates from the gasified refrigerant and returns independently. The refrigeration cycle is basically a closed system, and once the lubricating oil discharged from the compressor does not disappear somewhere in the cycle, it will return to the compressor again at some point. The oil circulation rate and the amount of lubricating oil returned are the same. However, when viewed in a shorter time unit, the separated lubricating oil itself does not have the property of returning to the compressor, and is simply blown back to the refrigerant of the gas that returns as a high-speed airflow. Therefore, the easiness of returning the lubricating oil is greatly affected by the configuration and shape of the cycle after the expansion valve, and as a result, the efficiency of the refrigeration cycle is greatly influenced.

Under these circumstances, it has been strongly desired to measure the oil return amount for evaluation of the refrigeration cycle, but at present, it is difficult to measure the oil return amount, and it is transparent to the part to be measured. There was no suitable method other than providing a simple piping part and visually observing it.

[0006]

The difficulty in measuring the return amount of lubricating oil is due to the following characteristics of the refrigeration cycle. 1) Since the refrigeration cycle is composed of a closed system in which high-pressure gas is enclosed, it is difficult to sample without affecting the operating condition. 2) At the part to be measured, the refrigerant is a gas and the lubricating oil is in a non-uniform state, and the lubricating oil in question is partly mixed with the gaseous refrigerant in a mist state and moves at high speed. Some of them flow at a relatively slow and non-uniform velocity along the pipe wall, and they have completely different characteristics as measurement targets, making it difficult to measure them collectively or separately. To be.

In particular, regarding the lubricating oil flowing along the pipe wall in 2), even if it is possible to measure the amount existing at that portion, it is determined whether it is flowing or staying. Not easy to distinguish. Furthermore, what really needs to be measured is the amount of movement of the lubricating oil. Therefore, calculate the product of the existing amount at the measurement site and the average flow velocity there, or when assuming a cross section of the flow, It is necessary to measure the flow velocity of each of the minute portions constituting it and integrate it over the entire cross-sectional area, but it is extremely difficult to realize either of them.

The present invention was made to break through the walls of the prior art, which could only be visually observed because of such difficulties, and the amount of lubricating oil returned to the compressor was determined by physical means. It is something to be measured.

[0009]

In order to solve the above-mentioned problems, the present invention separates the lubricating oil flowing along the pipe wall from the lubricating oil which becomes mist and is carried by the gaseous refrigerant, Provide a means to separately measure the amount of That is, the flow path that returns to the compressor in the refrigeration cycle is divided into a flow path in which the lubricating oil becomes mist and flows with the gas refrigerant, and a flow path in which only lubricating oil flows, and the former amount becomes the mist and the amount that moves It is measured as the amount of oil particles contained in the space, and the amount of the lubricating oil moving independently in the liquid state is measured as the amount of pure liquid flowing.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION One embodiment of the present invention is shown in FIG. In the refrigeration cycle, the refrigerant compressed by the compressor 1 is liquefied by the condenser 2, released from the compression pressure by the expansion valve 3, vaporized by the evaporator 4 and returned to the compressor again.
The pipe 5 connects the respective elements of these refrigeration cycles and guides the refrigerant in order. The lubricating oil discharged from the compressor together with the refrigerant is almost uniformly dissolved in the refrigerant up to the expansion valve where the refrigerant is in a liquid state, but after the refrigerant is vaporized in the evaporator, it is separated from the refrigerant, and part of it is at high speed. Is carried by the refrigerant of the gas flowing as a mist, and the rest is adhered as a liquid to the pipe wall, is pushed by the refrigerant and moves toward the compressor. The device for measuring the amount of returned lubricating oil according to the present invention comprises a sensor unit 6 and a main body unit 7, and the sensor unit is installed in a pipe just before the compressor. The sensor section and the main body section are connected by a connection cable 8.

The sensor section has a structure as shown in FIG. The sensor unit is connected to the piping of the refrigeration cycle at 11 and 12. For this connection, a flare joint method, a swagelok method, a flange method, or the like is used.
The sensor unit is composed of a main flow path 13, a mist amount measuring unit 14 and a liquid amount measuring unit 15 which are attached thereto. Make sure that the cross-sectional area of the main flow path is equal to or larger than that of the piping of the connected refrigeration cycle so that the flow path resistance does not increase by installing this sensor. Therefore, the flow velocity of the gaseous refrigerant is prevented from increasing so that the lubricating oil on the pipe wall does not become a new mist. The recess 16 provided in the main flow path is
The lubricating oil flowing along the pipe wall collects here and is guided to the liquid component measuring unit so that it does not go to the mist component measuring unit.

Next, each measuring section will be described. Measurement of the mist is based on the light scattering method. The configuration is shown in FIGS. The light irradiation section 21 and the light receiving section 22 are provided at 90 ° on the same circumference of the tube wall of the main flow path. A lamp 2 which is a light source is incorporated in the light irradiating section, and the light from the lamp 23 is made into a parallel light flux by the lens 24, and the window 2 is made of a material that transmits the light.
It is introduced through 6 into the main flow path. On the opposite side of the light irradiation part, a recess is formed in the main flow path, and a light trap 29 coated so as to further absorb light is provided there, and the irradiation light is reflected by the wall of the flow path and enters the light receiving part. Try not to. For the same reason, the inside of the flow path is also coated so as to absorb light.
A photodetector 28 is installed in the light receiving unit so that scattered light due to mist passes through the light transmissive window 27, is condensed by the lens 25, reaches the detector, and is detected. The intensity of light scattered and incident on the detector is related to the amount of mist existing in the space irradiated by the irradiation light.Therefore, from the detected scattered light intensity, a calibration curve prepared separately as necessary is used. Calculate the amount. The amount of the mist-like oil transferred can be calculated by multiplying the amount of the mist thus obtained by the flow velocity of the gas refrigerant that is separately measured. Electric power for operating the light source lamp and the detector is sent from the main body through the connecting cable, and the signal detected by the detector is also sent to the main body through the connecting cable, where it is processed and output.

As another embodiment of the present invention, a light source lamp and a detector are not incorporated in the light emitting portion and the light receiving portion, but a light source is incorporated in the main body portion, and light is guided to the light emitting portion from here by using an optical fiber. Further, there is a configuration in which scattered light obtained by the light receiving section is guided to the main body section by an optical fiber and the intensity thereof is detected there.

Next, the measuring unit for the moving amount of the lubricating oil in the liquid state will be described. An embodiment according to the present invention is shown in FIG. Hollow 1
Lubricating oil flowing into 6 is the thin tube 3 connected directly below it.
Fill the liquid lubricating oil measuring container 32 through 1. A thin branch pipe 33 is connected to almost the middle of this small container,
When the lubricating oil reaches this point, it overflows from this branch pipe and drops as droplets from the nozzle 34 provided at the end of this branch pipe into the container 35. A light emitting portion 36 and a light receiving portion 37 formed of a light emitting diode are arranged immediately below the nozzle,
The dropped droplet is detected by light. The dropped lubricating oil passes through the narrow tube 38, returns to the main flow path, and finally returns to the compressor. The thin tubes 39 and 40 are provided to maintain the pressure balance in the container. The valve 41 and the subsequent thin tube 42 are for draining the lubricating oil accumulated in the small container after the measurement is completed.

The amount of lubricating oil that moves as a liquid is proportional to the number of droplets per unit time. The number of detected droplets is converted into the number per unit time, and the movement amount of the lubricating oil is calculated using a calibration curve prepared separately as needed.

[0016]

As described above, according to the present invention, it is possible to physically measure the return amount of the lubricating oil, which can only be visually observed, and to design a refrigeration cycle with higher efficiency. It is possible to supply objective data of.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a state in which a lubricating oil return amount measuring device according to the present invention is incorporated in a refrigeration cycle.

FIG. 2 is a schematic explanatory diagram of a sensor unit of the present invention.

FIG. 3 is a front view illustrating a mist component measuring mechanism by a light scattering method, which is one of the embodiments of the present invention.

FIG. 4 is a top view illustrating a mist component measuring mechanism by a light scattering method, which is one embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a mechanism for measuring a liquid lubricating oil as the number of liquid droplets, which is one of the embodiments of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Expansion valve 4 Evaporator 5 Piping 6 Sensor part 7 Main body part 8 Signal cable 11 Connection part (in side) 12 Connection part (out side) 13 Main flow path 14 Mist type lubricating oil component measurement part 15 Liquid type lubrication Oil measuring part 16 Liquid lubricating oil collecting part 21 Light emitting part 22 Light receiving part 23 Light source lamp 24, 25 Lens 26, 27 Light transmitting window plate 28 Optical detector 29 Optical trap part 31, 33, 38, 39, 40 , 42 Thin tube 32 Liquid lubricating oil measuring small container 34 Nozzle 35 Droplet receiving container 36 Light emitting part 37 Light receiving part 41 Valve

Claims (3)

[Claims] 1. When measuring the amount of lubricating oil returning to a compressor in a refrigeration cycle, the lubricating oil flowing in a liquid state in a pipe of the refrigeration cycle is separated into a gaseous refrigerant flow containing a mist of lubricating oil, A lubricating oil return amount measuring device having a mechanism for measuring the amount of lubricating oil flowing in a liquid state, and a mechanism for measuring the amount of lubricating oil carried as a mist by the flow of a gas refrigerant. 2. The lubricating oil return amount measuring device according to claim 1, wherein the separated liquid lubricating oil is dropped as droplets from a thin tube, and the flow rate of the lubricating oil is measured by counting the number of drops. Lubricant return amount measuring device. 3. The lubricating oil return amount measuring device according to claim 1, wherein the gas refrigerant containing the separated mist of the lubricating oil is measured by a light scattering method, and the mist-like lubricating oil is conveyed from the intensity of the scattered light. Lubricating oil return amount measuring device to measure the amount of.