JPH0588778B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine oil deterioration detection device that can detect the degree of deterioration of engine oil with high accuracy.

Further, the present invention relates to a vehicle-mounted engine oil deterioration detection device that can detect the progress of deterioration of engine oil of a vehicle during driving.

(Prior Art) As engine oil is used under harsher conditions as engines improve in performance and output, it is necessary to accurately determine when to replace the engine oil. To this end, it is necessary to accurately detect the progress of deterioration of engine oil and prevent the occurrence of mass production of sludge and rapid viscosity (oil shock) that can cause engine trouble.

Conventionally, as a method for determining the degree of deterioration of engine oil, a sensitive inspection method such as visual inspection has been used because promptness is required. For example, at a gas station, an engine oil level gauge was pulled out and the degree of contamination of the engine oil adhering to the tip was visually determined, or by tactile inspection with one's fingers. However, such a sensitive test is too empirical and has the disadvantage that it is not possible to accurately determine the degree of deterioration of the engine oil because there are many errors caused by each individual.

Furthermore, as another inspection method, an apparatus for optically measuring the degree of contamination of engine oil has been proposed, and is described, for example, in Japanese Patent Application Laid-Open No. 76938/1983. In this known measuring device, the engine oil to be measured is filled into a transparent container, a light beam is projected into the transparent container, and the degree of contamination of the engine oil is measured by the intensity of the transmitted light from the transparent container. ing.

(Problems to be Solved by the Invention) The method of determining the deterioration of engine oil based on the degree of contamination of the engine oil described above is difficult because soot and metal traces get mixed into the engine oil depending on the operating time of the engine.
This can be used as a tentative guideline for determining deterioration.

However, the turbidity measurement merely detects contamination of the engine oil, and cannot accurately detect oxidative deterioration of the engine oil itself, which is a direct cause of engine trouble. In other words, the essential deterioration of engine oil is mainly caused by oxidative deterioration and the formation of polymers due to high-temperature driving, and it is difficult to accurately detect the progress of engine oil deterioration by simply detecting the degree of contamination. Must not be. For example, even if the amount of foreign matter such as soot is small, nitro oxidation is often progressing rapidly due to high-temperature driving, and in such cases, simply detecting the degree of contamination cannot accurately determine the progress of engine oil deterioration. There was a risk that this could lead to engine trouble due to failure to grasp the situation. Therefore, in order to accurately grasp the progress of engine oil deterioration, turbidity measurement is incomplete, and it is necessary to accurately measure the total acid value, total base value, viscosity, etc. specified in the JIS standard. However, this requires extensive measuring equipment, and it is difficult to easily measure it at locations such as gas stations.

Furthermore, the known deterioration detection devices described above are of a portable type and must be detected by sampling engine oil from the engine. On the other hand, for drivers, if the degree of engine deterioration is automatically displayed while driving, they will be able to accurately judge when it is time to change the engine oil while driving, which will improve the efficiency of changing engine oil and prevent accidents. A great advantage can be achieved in that it can prevent such problems from occurring.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned drawbacks and to provide an engine capable of detecting the degree of deterioration of the engine oil itself, which causes engine troubles, with high precision, and with a simple configuration and easy operation. The present invention provides an oil deterioration detection device.

Further, the present invention provides an engine oil deterioration detection device that can directly detect the deterioration degree of engine oil installed in a vehicle and display the deterioration degree of the engine oil on a driving panel.

(Means for Solving the Problems) A deterioration detection device according to the present invention includes a light source that projects infrared light toward engine oil to be detected for deterioration, and a light source that receives transmitted light from the engine oil to detect deterioration depending on the degree of deterioration. and a photodetector that generates a photoelectric output signal, and the center wavelength range of the light incident on the photodetector is approximately equal to the infrared absorption peak wavelength of the nitrate ester.

Further, the deterioration detection device according to the present invention includes a light source that projects infrared light toward the engine oil to be detected for deterioration, and a light source that receives transmitted light from the engine oil and generates an optical power signal according to the degree of deterioration. a photodetector to
and a display device that displays the degree of deterioration of the engine oil based on the optical power signal, and the central wavelength range of the light incident on the photodetector is approximately equal to the infrared absorption peak wavelength of the nitrate ester. It is something to do.

(effect) Engine oil deterioration can be broadly classified into the following types:

Oxidative deterioration of the engine oil itself due to loss of antioxidants, etc. Deterioration of various functions due to consumption of additives Contamination of external substances such as fuel, combustion products, and dust These deteriorations may progress independently, but
In many cases, each type of deterioration is intricately intertwined to cause deterioration of the entire engine oil, with oxidative deterioration being the dominant factor. Regarding oxidative deterioration, the effect of NO _x contained in exhaust gas from gasoline engines, gas engines, diesel engines, etc. on engine oil is extremely important. In the oxidation reaction at high temperatures, NO _x acts as a catalyst, and nitro-oxidation of hydrocarbon RH proceeds as shown below, resulting in RONO,
Generate RONO ₂ .

RH _{NO x −−− →} R _{+ HNO} It has been found that there is a correlation between the amount of nitrate esters contained in engine oil and the total acid value at various running times. Therefore, by quantifying the amount of nitrate ester in the engine oil whose deterioration is to be detected, the progress of deterioration can be accurately detected.

In the present invention, absorbance is measured using light with a wavelength approximately equal to the infrared absorption peak wavelength of nitrate ester.
If absorbance is measured using light with a wavelength equal to the infrared absorption peak of nitrate ester, a photoelectric output corresponding to the amount of nitrate contained in engine oil can be obtained without being affected by other components, and the deterioration of engine oil can be detected. The progress of the process can be accurately degraded. Furthermore, in the present invention, a transparent container made of hard vinyl chloride resin, polymethylpentene resin, or polypropylene resin is used as the sample container. Since these sample containers do not have characteristic absorption at the infrared absorption peak wavelength of nitrate ester, they do not adversely affect absorbance measurement, and are inexpensive and can be used disposable. In particular, since hard vinyl chloride resin has high mechanical bending strength, the advantage is achieved that desired mechanical strength can be obtained even if the wall thickness of the sample container is made thin.

(Example) FIG. 1 is a graph showing the infrared absorption spectrum characteristics of deteriorated engine oil used in a highway driving test. The horizontal axis shows wavelength, and the vertical axis shows infrared transmittance. As is clear from Figure 1, 2~
Three absorption peaks occur in the 15 μm wavelength range, and these three absorption peaks are absorption peaks specific to nitrate ester. Therefore, these three
If the absorbance characteristics of engine oil are measured using light at one of the absorption peak wavelengths, it is possible to determine the amount of nitrate esters contained in engine oil without being affected by other component substances. This means that it can be measured with sensitivity. In particular, in the wavelength region around 6.1 μm, it has steep absorption peak characteristics, so if infrared light with a center wavelength of 6.1 μm is used, the amount of nitrate ester can be quantified with extremely high precision.

First, a portable engine oil deterioration detection device will be explained.

FIGS. 2a and 2b show the configuration of an example of the engine oil deterioration detection device according to the present invention. FIG. 2a is a diagrammatic sectional view showing the overall configuration, and FIG. FIG. 3 is a circuit diagram showing the configuration. A light source 2 is attached to a base 1 that serves as a reference for positioning various optical members. The light source 2 is composed of a ceramic heater that emits infrared light including light at a wavelength of 6.1 μm, which is the absorption peak wavelength of nitrate ester. Infrared light is projected from a light source 2 toward a chopper device 3. The chopper device 3 has a rotary disk 3a having a plurality of circumferential openings and a motor 3b for driving the rotary disk, and allows incident infrared light to pass intermittently. The infrared light that has passed through the chopper device 3 is focused by a condenser lens 4, and then enters a sample container 6 containing engine oil 5 whose deterioration is to be detected. The sample container 6 is a transparent container made of hard vinyl chloride, and is inserted into a recess formed in the support member 7. This sample container has no characteristic absorption for light at the infrared absorption peak wavelength of nitrate ester, so it is extremely effective in ensuring measurement accuracy.Moreover, since it is inexpensive, it can be disposable and can be easily measured on site. It is also suitable for The infrared light incident on the sample container 6 is absorbed by the amount of various components including nitrate ester contained in the engine oil in the container, and then emitted. The transmitted light from the sample container passes through a filter 8 and is received by a photodetector 9 to form a photoelectric output signal. Filter 8 uses a bandpass filter having a central transmission wavelength range approximately equal to 6.1 μm, which is the infrared absorption peak wavelength of nitrate ester,
Only light with a wavelength of 6.1 μm is made incident on the photodetector 9.
The transmitted light from the sample container 6 contains light waves that are attenuated due to the unique absorption effect of various substances contained in the engine oil, but depending on the transmission characteristics of the filter 8, the light waves are attenuated depending on the amount of nitrate ester. Only the absorbed light will be incident on the photodetector 9.
As a result, a photoelectric output signal is generated according to the amount of nitrate ester contained in the engine oil. A post-processing circuit 1 that amplifies this photoelectric output signal with an amplifier 10
Supply to 1. The processing circuit 11 includes a chopper drive circuit 12 that creates a drive signal for the chopper device 3.
A detection signal is created by synchronously detecting the input photoelectric output signal using the same synchronization signal as that supplied to the sensor. Furthermore, the processing circuit 11 includes various data for calibration, such as zero data values, calibration curve data,
Correction data and the like for the optical system are stored in advance, and signal processing is performed using these data to calculate the amount of nitrate ester contained in the engine oil.
The calculated amount of nitrate ester is displayed on the display device 13. Various display methods such as digital display or analog display can be used. This processing and driving circuit is mounted on a substrate, and this substrate is placed in the space between the base 1 and the housing 20. By arranging it in this way, it is possible to make a portable deterioration detection device that is convenient to carry, and it can be directly measured at a gas station or the like.

Next, the transparent sample container will be explained.

FIG. 3 shows the structure of an example of a transparent sample container according to the present invention, in which FIG. 3a is a perspective view, FIG. 3b is a front view, and FIG. 3c is a sectional view taken along the line -- in FIG. 3b. It is. Front plate 31 forming the entrance window
A spacer plate 33 is disposed between the rear plate 32 constituting the exit window, and these plates are bonded together with an adhesive to define a sample accommodation space 34. The spacer plate 33 has two planes parallel to each other, and by connecting the front plate 31 and the rear plate 32 to these planes, the front plate 31 and the rear plate 32 are made parallel to each other via the spacer plate. will be combined. Furthermore, a notch is formed in the spacer plate 3 and is tapered to expand upward, and the bottom of this notch is curved toward the lower end. Since the thickness of this spacer plate 33 serves to define the thickness of the sample storage space, it is desirable to determine it by considering the amount of absorption by the sample. When measuring the absorbance of engine oil, the thickness is preferably 0.1 to 2.0 mm. By bonding these three plates 31, 32, and 33 to each other with adhesive, a sample accommodation space 34 that has a uniform thickness in the direction orthogonal to the optical axis l and expands toward the opening 35 is created. defined. With this configuration, the sample storage space 34 has no edge portion and is formed in a gently tapered shape toward the lower end, so that bubbles are less likely to be generated when a liquid sample is injected from the opening 5. At the same time, even if bubbles are generated, they immediately move upward and disappear. moreover,
In this example, the front plate 31 and the spacer plate 33 are extended upward from the opening 35. If the front plate 31 is extended above the opening 35 in this way, the portion extending above the opening will serve as a guide.
Injection work can be performed more efficiently. This is particularly effective when using a thin analytical cell.

Next, the material of the sample container will be explained. The material of the sample container must be appropriately selected in consideration of the characteristic absorption. FIG. 4 shows the transmission characteristics of various materials for light with a wavelength of 6.1 μm. The horizontal axis shows the thickness of the material to be measured, and the vertical axis shows the transmittance. The △ mark indicates the transmission characteristics of polypropylene, the ○ mark indicates the transmission characteristics of hard vinyl chloride resin that does not contain a plasticizer,
□ indicates the transmission characteristics of polycarbonate, and ◇ indicates the transmission characteristics of polymethylpentene. Polycarbonate is
It has a strong absorption property for light with a wavelength of 6.1μm, and the thickness
At 0.5mm, the transmittance becomes almost zero. In contrast, rigid vinyl chloride, polymethylpentene and polypropylene exhibit good permeation properties;
At a thickness of 0.2 mm, the transmittance is approximately 70%. From this result, it can be understood that hard vinyl chloride and polypropylene are effective materials for the sample container used in the present invention. In addition, additives such as plasticizers may be mixed into the resin material. For example, if a plasticizer that has a characteristic absorption for light at the absorption wavelength of nitrate ester is added,
Due to the influence of the plasticizer, a disadvantage arises in that light with a wavelength of 6.1 μm is strongly absorbed by the sample container. Therefore, it is desirable to consider the material of the sample container as well as the absorption characteristics of additives, and it is necessary to construct the sample container from a resin that does not use additives. Further, as is clear from FIG. 4, as the thickness of the wall of the sample container increases, the amount of absorption by the sample container increases, so it is desirable to make the thickness of the wall of the sample container as thin as possible. On the other hand, when the thickness of the wall portion becomes thinner, the structural mechanical strength of the sample container is reduced. Therefore, it is desirable to use a material that has high mechanical strength as well as characteristic absorption of infrared light. In particular, hard vinyl chloride has a bending elastic modulus of 28,000 to 42,000/cm ² and is therefore extremely suitable as a sample container from the viewpoint of mechanical strength.

Next, the measurement results obtained when the degree of deterioration of various engine oils was measured using the deterioration detection device according to the present invention will be explained.

FIGS. 5a and 5b show the measurement results of engine oil of gasoline engines and gas engines using the deterioration detection device according to the present invention, and FIG. The measurement results for engine oil of gasoline engine vehicles are shown. In FIGS. 5a to 5c, the horizontal axis represents the total acid value, and the vertical axis represents the relative output value. The various engine oils used in the measurements were those used in actual driving tests and had different running times. As shown in FIGS. 5a and 5b, the measurement results by the deterioration detection device according to the present invention show that as the total oxidation increases, the relative output value also increases correspondingly, and there is a gap between the relative output value and the total acid value. This shows that there is a relative relationship. on the other hand,
As shown in FIG. 5c, in the pollution level measuring device, there is no correspondence between the relative output value and the total acid value, and only a distinction is made between new oil and used engine oil. This experimental result shows that the amount of nitrate esters contained in engine oil has a corresponding relationship with the total acid value of the engine oil, so by detecting the amount of nitrate esters, the degree of deterioration of engine oil can be detected with high accuracy. become.

In the above-mentioned example, the degree of deterioration was detected based on the photoelectric output signal of light with a wavelength equal to the infrared absorption peak wavelength of nitrate ester, but the degree of deterioration was detected based on the photoelectric output signal of light with a wavelength equal to the infrared absorption peak wavelength of nitrate ester and this wavelength range. It is also possible to detect the degree of deterioration based on a photoelectric output signal generated by light of a wavelength other than the above. That is, foreign substances such as soot are also present in engine oil along with nitrate ester. Due to the presence of these foreign substances, the projected light is subject to scattering and absorption effects within the cell, and this effect reduces the photoelectric output signal. This drop in the photoelectric output signal occurs over almost the entire wavelength range, so even when measuring using the infrared absorption peak wavelength of nitrate ester, the measurement results include some noise due to contamination levels such as soot. will be included. On the other hand, if absorbance is measured using light at a wavelength other than the infrared absorption peak wavelength of nitrate ester, for example, infrared light around 4 to 5 μm as shown in Figure 1, this measurement result will reflect the amount of noise caused by substances other than nitrate ester. will represent. Therefore, the amount of nitrate ester can be detected more accurately by removing the photoelectric output signal component due to light with a wavelength other than the above wavelength range, which represents the amount of noise, from the photoelectric output signal due to light at the infrared peak wavelength of nitrate ester. . In this case, measurements are performed by alternately inserting a bandpass filter whose center transmission wavelength range is at the infrared absorption peak wavelength of nitrate ester and other bandpass filters into the optical path, and then transmitting these photoelectric output signals to a processing circuit. The amount of nitrate ester can be determined by performing calculation processing.

Next, a vehicle-mounted engine oil deterioration detection device will be described. Figures 6a and 6b show the configuration of an example of a vehicle-mounted engine oil deterioration detection device according to the present invention, and Figure 6a is a diagram showing the mounting position of the deterioration detection part, and Figure 6b is a diagram showing the deterioration detection part. FIG. In this example, the deterioration detection unit is attached to the engine oil pan, and the output signal from the deterioration detection unit is output to a display device placed on the display panel in the driver's seat, allowing the driver to directly see the progress of engine oil deterioration. shall be displayed. Engine has oil pan 4
0, cylinder block 41, cylinder head 4
2. The oil pan 40 includes a head cover 43 and an air cleaner 44, and a through hole is formed in the wall of the oil pan 40, and the detection section 50 is attached to the oil pan through the through hole. The detection unit 50 has a housing 51 in which various optical elements are housed. The housing 51 has a base portion 51a and a protruding portion 51b, and is screwed onto the wall portion 40a of the oil pan via an O-ring so that the protruding portion 51b is located within the engine oil circulation portion within the oil pan. A light source 52 emits infrared light including light with a wavelength of 6.1 μm, and the infrared light is focused by a condenser lens 53 and made to enter a total reflection mirror 54 . Two transparent plates 55a and 55b are arranged parallel to each other at a predetermined interval between the condensing lens 53 and the total reflection mirror 54, and two transparent plates 55a and 55b are arranged in parallel to each other at a predetermined distance between the condenser lens 53 and the total reflection mirror 54. An opening 56 is formed through which engine oil flows.
The two transparent plates 55a and 55b are made of transparent hard vinyl chloride resin, and their ends are closely sealed to the housing. Therefore, a flow path is formed between the two transparent plates through the opening 56, through which the engine oil in the oil pan flows. The infrared light focused by the condenser lens 53 is absorbed by the engine oil flowing between the two transparent plates, is reflected by the total reflection mirror 54, and is absorbed by the engine oil and the condenser lens again. The light then enters the photodetector 57. A filter 58 having a central transmission wavelength range of about 6.1 μm is placed in front of the photodetector 57, and only infrared light around 6.1 μm is allowed to enter the photodetector 57. As a result, the photodetector 57 generates a photoelectric output signal corresponding to the amount of nitrate ester contained in the engine oil. After the output signal from the photodetector 57 is amplified by the amplifier 59, the signal processing circuit 60
The signal is processed to generate an output signal corresponding to the degree of deterioration of the engine oil, and is supplied to a display device 61 disposed on a display panel in front of the driver's seat to display the degree of deterioration of the engine oil. Note that the display method may be a digital display or an analog display, or an alarm display that lights or blinks a lamp when the deterioration limit value is exceeded may be used. With this configuration, the driver can directly know the degree of deterioration of the engine oil when driving the vehicle, and accidents caused by deterioration of the engine oil can be prevented. Although the engine oil flow path to be detected for deterioration is defined between two parallel transparent plates, a condensing lens and a total reflection mirror are hermetically attached to the housing, and these condensing lenses It is also possible to configure the engine oil to flow directly between the mirror and the total reflection mirror. In this case, two transparent plates are not required, and the structure of the detection section can be simplified.

FIG. 7 is a sectional view showing a modification of the detection section.
The same members as those used in FIG. 6 will be described with the same reference numerals. In this example, a light source is placed on one side of a flow path of engine oil whose deterioration is to be detected, and a photodetector is placed on the other side.
After condensing the infrared light emitted from the light source 52 with the condensing lens 53, the infrared light emitted from the light source 52 is
The liquid is projected toward the engine oil flow path defined by 5b. The infrared light is absorbed depending on the amount of nitrate ester contained in the engine oil in the flow path, and passes through a filter 57 with a central transmission wavelength range of 6.1 μm to the photodetector 5.
8, and a photoelectric output signal is generated according to the amount of nitrate ester contained in the engine oil. With this configuration, the infrared light passes through the engine oil only once, so the width of the engine oil flow path can be set relatively wide.

FIG. 8 is a diagrammatic cross-sectional view showing the configuration of another modification of the engine oil deterioration detection device according to the present invention. In this example, an example will be described in which a light source and a photodetector are arranged at arbitrary positions using a light transmission body such as an optical fiber. As the optical transmission body, a double transmission optical fiber having a central transmission part and an outer peripheral transmission part formed on the outer periphery of the central transmission part is used. Infrared light emitted from the light source 70 is radiated toward a filter 71 with a center transmission wavelength of 6.1 μm, and light with a wavelength of 6.1 μm is projected toward the center transmission section 72a of the optical fiber 72. The optical fiber 72 is a quartz fiber that does not have specific absorption characteristics in the 6.1 μm wavelength range. The 6.1 μm wavelength light passes through the central transmission section 72a of the optical fiber and propagates to its end face. The end of the optical fiber 72 is fixed to a casing 73, and the casing 73 is screwed onto the wall 74 of the oil pan. casing 73
A total reflection mirror 75 is attached to the end of the optical fiber 72 so as to face the end surface 72c of the optical fiber 72, and is fixed with an end cap 76. An opening 73a is formed in a portion of the casing 73 located between the total reflection mirror 75 and the end surface 72c of the optical fiber.
3a, engine oil is made to flow between the total reflection mirror and the end face of the optical fiber. Therefore, the light that has propagated to the end face 72c through the central transmission part 72a of the optical fiber is radiated toward the engine oil, and is absorbed into the total reflection mirror 75 according to the amount of nitrate ester contained in the engine oil. do. The light emitted from the end face of the optical fiber becomes a diverging light flux, so after being reflected by the total reflection mirror, it enters the outer peripheral part 72b of the optical fiber, propagates through this outer peripheral transmission part 72b, and enters the photodetector 77. Therefore, this photodetector 77 generates a photoelectric output signal corresponding to the amount of nitrate ester contained in the engine oil. In this way, by using an optical fiber, the light source and the photodetector can be separated from the detection section and placed at an arbitrary position, and the effects of temperature and vibration can be avoided.

FIGS. 9a and 9b are diagrammatic cross-sectional views showing the structure of another modification of the deterioration detection device according to the present invention. FIG. 9a shows a detection system using an engine oil supply pipe. A transparent piping member 81 made of hard vinyl chloride resin is connected in the middle of the engine oil supply piping 80, and a light source 82, a filter 83, and a photodetector 84 are arranged across the transparent piping member. The infrared light emitted from the light source 82 enters the flowing engine oil through the transparent piping member 81, is absorbed by the engine oil, and is filtered by the filter 83, where only the 6.1 μm wavelength light is transmitted. incident on the detector 84.

In this way, if deterioration is detected using the engine oil flowing through the piping, the arrangement of the light source and the photodetector becomes extremely easy. FIG. 9b shows an example in which a light source 91 and a photodetector 92 including a filter are attached to the tip of an oil level gauge 90 to detect deterioration. Since the tip of the oil level gauge 90 is always immersed in the oil in the oil pan,
By using an oil level gauge, the light source and photodetector can be more easily accommodated in the oil pan.

The present invention is not limited to the embodiments described above, and various modifications and changes are possible. For example, in the above-mentioned embodiment, a bandpass filter was used that had a central transmission wavelength range that was almost equal to the infrared absorption peak wavelength of nitrate ester, but the bandpass filter had a sharp filter that centered around the infrared absorption peak wavelength and cut shorter wavelengths. It is also possible to use a filter that combines a cut filter and a sharp cut filter that cuts out the long wavelength side. Furthermore, if a light source having a central emission peak approximately equal to the infrared absorption peak wavelength of the nitrate ester is used, a filter is, of course, unnecessary.

(Effects of the Invention) As explained above, according to the present invention, the amount of nitrate ester contained in the engine oil to be detected for deterioration is optically detected. The degree of deterioration corresponding to the measurement item can be detected with high accuracy. In particular, highly accurate measurements can be made simply by placing a sample container and filter between the light source and the photodetector, and the optical path length of the optical system can be set short, allowing it to be designed as a portable detection device. The degree of deterioration of engine oil can be directly measured at a stand or other site with simple operations.

Furthermore, the present invention is configured to optically detect the amount of nitrate ester contained in the engine oil during driving and display the degree of deterioration of the engine oil on the display panel based on the detected amount of nitrate ester. It is possible to check the degree of deterioration of the engine oil during operation, and to reliably determine when it is time to replace the engine oil.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the infrared absorption spectrum characteristics of deteriorated engine oil, Fig. 2 a and b are diagrams and circuit diagrams showing the configuration of an embodiment of a portable engine oil deterioration detection device, and Fig. 3 Figures a to c are perspective views, front views, and cross-sectional views showing the structure of the transparent sample container, Figure 4 is a graph showing the transmittance characteristics of the sample container material, and Figures 5 a and b show the deterioration detection device according to the present invention. Figure 5c is a graph showing the measurement results when using a conventional device. Figures 6a and b are the configuration of an on-vehicle engine oil deterioration detection device. A line diagram showing
FIG. 7, FIG. 8, and FIG. 9 a and b are diagrammatic cross-sectional views showing the configuration of a modified example of the vehicle-mounted engine oil deterioration detection device. DESCRIPTION OF SYMBOLS 1...Base, 2,52...Light source, 3...Chopper device, 4,53...Condensing lens, 5...Engine oil, 6
...sample container, 7...support member, 8,58...filter, 9,57...photodetector, 10,59...amplifier,
11, 60... Processing circuit, 12... Chopper drive circuit, 13, 61... Display device, 40... Oil pan,
50...Detection unit, 51...Housing, 54...Total reflection mirror, 55a, 55b...Transparent plate.

Claims (1)

[Claims] 1. A light source that projects infrared light toward the engine oil whose deterioration is to be detected, and a photodetector that receives transmitted light from the engine oil and generates a photoelectric output signal according to the degree of deterioration. An apparatus for detecting deterioration of engine oil, characterized in that the center wavelength range of the light incident on the photodetector is approximately equal to the infrared absorption peak wavelength of nitrate ester. 2. The engine oil deterioration detection device according to claim 1, wherein the sample container containing the engine oil is made of hard vinyl chloride resin, polymethylpentene resin, or polypropylene resin. 3. The sample container has two transparent walls that are parallel to each other, and the space between these transparent walls is closed except for an opening, and a taper is formed to widen toward the opening. The engine oil deterioration detection device according to claim 2, further comprising a sample storage space defined by a side wall portion. 4. A light source that projects infrared light toward the engine oil whose deterioration is to be detected, a photodetector that receives the transmitted light from the engine oil and generates an optical power signal according to the degree of deterioration, and a a display device that displays the degree of deterioration of the engine oil based on the deterioration of the engine oil, the center wavelength range of the light incident on the photodetector being approximately equal to the infrared absorption peak wavelength of the nitrate ester. Detection device. 5. The light source and the photodetector are arranged opposite to each other at a predetermined distance, and the engine oil to be detected for deterioration flows between the light source and the photodetector. Engine oil deterioration detection device. 6 A light source and a photodetector are placed on one side of the area where the engine oil to be detected for deterioration flows, and a reflector is placed on the other side, so that infrared light emitted from the light source detects the engine oil. Claim 5 characterized in that the light is configured such that the light is incident on the reflector through a distribution area of the reflector, and the reflected light from the reflector is incident on the photodetector.
The engine oil deterioration detection device described in . 7. The infrared light emitted from the light source is made to enter a reflector through a light transmitter and engine oil, and the reflected light from the reflector passes through the light transmitter and enters a photodetector. The engine oil deterioration detection device according to claim 6. 8. A first filter that is disposed between the light source and the photodetector, and whose center transmission wavelength range is approximately equal to the infrared absorption peak wavelength of the nitrate ester, and allows light of a wavelength other than the infrared absorption peak wavelength of the nitrate ester to pass therethrough. comprising a second filter and means for switching insertion of the first and second filters into the optical path;
Any one of claims 1 to 7, characterized in that the deterioration degree is detected based on a photoelectric output signal caused by light passing through the first filter and a photoelectric output signal caused by light passing through the second filter. The engine oil deterioration detection device according to item 1.