JP2000088750A - Method and device for measuring deterioration of engine oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To replace an engine oil usefully and efficiently by grasping the deterioration state of an engine oil as numerical data easily without dirtying hands. SOLUTION: A transducer 40 and a thermocouple 50 utilizing surface plasmon resonance are provided in an oil pan 21 of an engine E. In this case, the resonance angle (resonance angle minimum point) of an engine oil 30 is calculated from information from the transducer 40 by an operation means CPU, and temperature compensation is made, thus estimating the degree of deterioration of the engine oil 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for measuring deterioration of engine oil, and more particularly to a method and a device for measuring deterioration of engine oil for estimating the deterioration from a change in the refractive index of light of engine oil.

[0002]

2. Description of the Related Art Engine oil for internal combustion engines deteriorates with time and gradually loses its function as a lubricating oil. Deterioration of the engine oil during use is tested for the alkalinity, diffusivity, carbon content, etc. of the oil using required measuring equipment and the degree is judged.However, such tests are not easy. This is done by pulling out the oil gauge and visually determining the color of the oil adhering to the gauge, or by picking up the oil with a fingertip and tactilely determining the viscosity.

[0003]

The above-described judgment of the degree of deterioration by visual or tactile sense is relatively easy as a technique, but is a judgment based on human senses. The result cannot be avoided. Using a measuring device to test physical property values such as alkalinity, diffusivity, and the amount of carbon, and to determine the degree of deterioration, the results can be shown as numerical values and the objectivity is high, but the work is difficult In addition to the above, when foreign matter is mixed in oil, it may affect the test result.

[0004] Further, in any of the methods, it is necessary to stop the engine, and it is not possible to immediately know the information while the engine is operating. An object of the present invention is to provide an objective measurement of engine oil deterioration as a measured value without human perception, and regardless of whether the engine is running or stopped, It is an object of the present invention to provide a method and an apparatus for measuring deterioration of engine oil which can be readily obtained by always providing immediate information.

[0005]

Means for Solving the Problems In the course of conducting many experiments and studies on the deterioration of engine oil, the present inventors have found a correlation between the deterioration of engine oil and the change in the refractive index of reflected light with respect to incident light. I knew there was. FIG.
Is a graph showing the correlation, and the use time and the decrease in the refractive index are clearly correlated. The graph in FIG. 6 is based on data obtained by sampling a few drops of engine oil after a certain period and measuring with an Abbe refractometer.

The present invention is based on the above findings, and a method for measuring deterioration of an engine oil according to the present invention is to irradiate the engine oil with light, measure the refractive index of the irradiated light, and set the value as a reference value. By comparing, the deterioration of the engine oil is estimated. The method of measuring the refractive index may be any method, but it is a preferable embodiment to calculate the refractive index based on the resonance angle by the surface plasmon resonance method.
The reason is that the use of a commercially available transducer using surface plasmon resonance makes it easy to carry out, and that even if foreign matter or the like is mixed in the engine oil, the measurement result is not affected.

As is already known, surface plasmon resonance means that a prism 1, a glass 2, and a metal thin film (for example, a gold thin film composed of two layers of chromium Cr and gold Au) 3 as shown in FIG. When light P is made incident from the glass 2 side at an incident angle equal to or greater than the total reflection angle, the evanescent wave bleeds at the boundary surface from the glass side to the gold side, and the incident angle is set. When it satisfies, it refers to the phenomenon that surface plasmons and evanescent waves resonate. When the surface plasmon resonance occurs, the energy of the incident light shifts to the surface plasmon resonance, and the intensity of the reflected light becomes weaker than the intensity of the incident light, and the intensity of the reflected light Pr becomes weakest with respect to the intensity of the incident light. The angle of incidence is called the resonance angle. Since the resonance angle changes due to a change in the refractive index of the surface of the metal thin film, the refractive index of the sample S in contact with the surface of the metal thin film can be measured using the surface plasmon resonance method.

In the transducer 10 shown in FIG. 5, a liquid supply / drainage head 6 is attached to the surface of the metal thin film via an O-ring 5, and a sample liquid S is supplied into the bed 6 by a pump (not shown). The measurement of the resonance angle is performed, and then the liquid is drained.

The thickness of the sample in contact with the surface of the metal thin film is several μm.
The surface plasmon resonance method can be used to measure the change in the refractive index of engine oil, which is always in a fluid state in an oil pan and is liable to contain foreign substances. It is a particularly effective measuring means as compared with other measuring methods such as a refractometer. In the actual measurement, the temperature environment of the engine oil changes greatly. Therefore, the values (reference values,
When the measured value is compared with the reference value, the temperature of the subject engine oil is measured at the same time, and the measured value is subjected to temperature compensation using the previously determined temperature compensation coefficient of the engine oil. It is desired.

According to the present invention, as a specific apparatus for carrying out the above method, a transducer utilizing surface plasmon resonance is attached to an oil pan of an engine so that a metal thin film thereof is in contact with engine oil, and Means for measuring the temperature of the engine oil, further comprising: means for calculating a resonance angle of the engine oil based on information from the transducer; means for temperature-compensating the calculated value based on temperature information; and Also disclosed is an engine oil deterioration measuring device characterized by comprising at least means for comparing the calculated value after compensation with a reference value and means for displaying the result of comparison.

By using this device, the deterioration state of the engine oil of the internal combustion engine can be easily grasped as numerical data and can be obtained as immediate information when necessary, so that it can be used in automobiles, ships, etc. without waste. In addition, the engine oil can be changed efficiently.

In a preferred embodiment, the apparatus for measuring deterioration of engine oil further comprises means for removing bubbles in the engine oil at a position near the metal thin film of the transducer. By arranging such an air bubble removing means in the oil pan, it is possible to avoid air bubbles from adhering to the measurement head (metal thin film), and it is possible to effectively eliminate measurement errors caused by air bubbles. As a specific means of bubble removal, means having a wire mesh in front of the metal thin film,
Means for disposing a centrifugal force generating means to eliminate bubbles by centrifugal force are effective. In still another embodiment, a thin film having a photocatalytic function, such as titanium oxide, may be laminated on the surface of a metal thin film of a transducer. Thereby, the wettability of the metal thin film surface is improved, and measurement errors due to bubbles can be effectively eliminated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 illustrates an embodiment in which the method for measuring deterioration of engine oil according to the present invention is performed in an internal combustion engine. The engine E has an oil pan 21 at the bottom, and the engine oil 30 is jumped up by an oil dipper 23 formed on the crankshaft 22 to lubricate around the piston. Although not shown, an oil pump is also provided, and the pumping of the engine oil 30 is also performed. In the present invention, the form of the engine as the internal combustion engine is arbitrary, and there is no particular limitation on the method of supplying engine oil.

In this example, the oil pan 21 is provided with a transducer 40 utilizing surface plasmon resonance and a thermocouple 50 as shown in FIG. 2A. Also,
A wire mesh 24 having a mesh size of about 0.5 mm is provided immediately in front of the transducer 40, and bubbles contained when the engine oil 30 passes through the wire mesh 24 are eliminated. The transducer 40 is the same as that described with reference to FIG. 5, and includes a prism 1 and a transparent substrate (glass).
2 and the metal thin film 3 are brought into contact with each other.
Is housed in the casing 44 so as to be exposed to the outside. A light-emitting element 41 and a light-receiving element 42 are attached to face the prism 1, and an input / output signal line 43 connected thereto is connected to an arithmetic CPU. The transducer 40 may be a conventionally known transducer.
Reference numeral 45 denotes a screw provided on the casing 44, which is used for fixing to the oil pan 21. Alternatively, as shown in FIG. 2b, transducer 40 and thermocouple 50
May be screwed into the oil pan 21 and fixed in a single casing 44a.

In this example, the transducer 40
Was based on a surface plasmon resonance biosensor (SPR-20) manufactured by Electrochemical Instruments Co., Ltd., and the sensor head portion (measurement chip portion) was replaced with the following measurement chip. That is, the measurement chip is a transparent substrate (glass)
A blue plate glass (manufactured by Matsunami Glass Industry Co., Ltd.) having a size of 13 mm × 18 mm × 0.3 mm was used as 2. . Sputtering is
100W, 30 seconds for chrome, 1 for gold
The test was performed at 00 W for 150 seconds. The thickness of the obtained chromium layer was 32.2 °, and the thickness of the gold layer was 474 °.
On the gold layer, a titanium oxide (TiO ₂ ) film was formed to a thickness of about 50 ° by plasma CVD.

The thermocouple 50 is also commercially available, and the thermocouple 5
1, a signal line 52 and a screw 53 to be attached, and the signal line 52 is connected to the above-described CPU for calculation. A calculating CPU for calculating a resonance angle of the engine oil 30 based on information from the transducer 40; a means for temperature-compensating the calculated value based on temperature information from the thermocouple 50; Means for comparing the calculated value with the reference value, and the comparison result is displayed on the display means DU.
It is displayed visually or numerically or by a graph.

FIG. 3 shows an example of the calculation. First, as the data, the resonance angle (minimum resonance angle point) P0 [予 め] is previously obtained from a resonance curve at the time of a new reference engine oil temperature T0 [° C.] and stored (10).
1). In the measurement, the measuring device is operated to calculate the current temperature T [° C.] and the resonance angle P [の] of the engine oil 30 from the transducer 40 and the thermocouple 50 (102). The temperature T0 and the temperature T are compared (103), and when they are equal (104), (T-T0) × a = 1 (where a is a temperature compensation coefficient of the engine oil and is obtained in advance). Go to the next step 105. If they are not equal (106), the process goes to the next step 105 as (T-T0) × a × P.

In step 105, taking temperature compensation into consideration,
A comparison is made between the reference resonance angle P0 [゜] and the current resonance angle P [゜] of the engine oil, and the difference ΔP is calculated. The result is sent to the display means DU, and an appropriate display is made. In this example, the magnitude of ΔP is divided into three stages,
≦ ΔP <0.7500, “good oil”;
If 7500 ≦ ΔP <1.5000, “oil attention” is displayed, and if 1.5000 ≦ ΔP, “oil replacement required” is displayed.

FIG. 4 shows the transducer 4 shown in FIG.
6 is a graph showing a surface plasmon resonance curve when the degree of deterioration of engine oil is actually estimated using 0. In the graph, the horizontal axis represents the resonance angle, and the vertical axis represents the reflection intensity. The engine oil used was BP # 1000 (manufactured by British Petroleum Co.), curve A was measured by transferring the engine oil immediately after opening to a container, and curve B was run 10,000 km with the oil in a car. Later, it was taken out of the oil pan and measured (note that the temperature environment was measured under the same conditions, so no temperature compensation was performed here).

The resonance curve exhibits a high angle side because the new oil has little deterioration, but the old oil deteriorates and the curve shifts to the low angle side. This indicates that the refractive index of the engine oil has decreased due to the deterioration. After traveling 10,000 km, when the oil gauge was pulled out and the color of the oil adhering to the gauge was observed, it was close to dark brown or black. Oil degradation was observed. This proves that the method according to the invention is effective for estimating engine oil degradation.

[0021]

According to the present invention, the deterioration state of the engine oil of the internal combustion engine can be easily grasped as numerical data without soiling the hands, and it can be obtained as immediate information when necessary. In ships, etc.
Lean and efficient engine oil change becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment in which an engine oil deterioration measuring method according to the present invention is implemented in an internal combustion engine.

FIG. 2 is a diagram showing a transducer and a thermocouple using surface plasmon resonance.

FIG. 3 is a flowchart showing an example of a calculation procedure.

4 is a graph showing a surface plasmon resonance curve when the degree of deterioration of engine oil is actually estimated using the transducer shown in FIG. 2;

FIG. 5 is a diagram shared with description of surface plasmon resonance.

FIG. 6 is a graph showing a correlation between deterioration of engine oil and a change in refractive index.

[Explanation of symbols]

E: engine (internal combustion engine), 21: oil pan, 30 ...
Engine oil, 40: transducer using surface plasmon resonance, 50: thermocouple, CPU: arithmetic unit,
DU: display means

Claims (6)

[Claims] An engine oil is characterized in that the engine oil is irradiated with light, the refractive index of the irradiated light is measured, and the measured value is compared with a reference value to estimate the deterioration of the engine oil. Measuring method. 2. The method for measuring deterioration of engine oil according to claim 1, wherein the refractive index is calculated based on a resonance angle obtained by a surface plasmon resonance method. 3. An oil pan of an engine is provided with a transducer utilizing surface plasmon resonance with its metal thin film in contact with the engine oil, and a means for measuring the temperature of the engine oil. Means for calculating the resonance angle of the engine oil based on information from the transducer, means for temperature-compensating the calculated value based on temperature information, means for comparing the calculated value after temperature compensation with a reference value, and a comparison result At least means for displaying the following. 4. The apparatus for measuring deterioration of engine oil according to claim 3, further comprising means for removing bubbles in the engine oil at a position near the metal thin film of the transducer. 5. The engine oil deterioration measuring device according to claim 3, wherein the transducer has a thin film having a photocatalytic function laminated on a surface of the metal thin film. 6. The engine oil deterioration measuring device according to claim 5, wherein the thin film having a photocatalytic function is a titanium oxide thin film.