JPS60224042A - Turbidity measuring device for lubricant - Google Patents

Abstract

PURPOSE:To measure a range of high turbidity by placing a lubricant to be measured in a light path gap of less than 0.34mm. provided between a light source window and a light receiving window. CONSTITUTION:A light path gap 3 is provided between facing faces of the light source window of light source 11 side and the light receiving window 22 of photoelectric element side. Nearly U-shaped projections 41-43 provided on the circumference of a nearly cylindrical spacer ring 4 are inserted between window 21, 22 to fix the aperture D to less than 0.34mm., and the lubricant turbidity of which is to be measured based on the transmissivity of light is placed in the gap 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lubricating oil contamination measuring device. The device according to the present invention is used, for example, as an on-vehicle measuring device to measure the concentration of carbon particles contained in the lubricating oil of an internal combustion engine, particularly a diesel engine.

BACKGROUND OF THE INVENTION Problems to be Solved by the Prior Art and the Invention Various lubricating oil contaminants become mixed into engine lubricating oil as the engine is operated. For example, fine particles of sand contained in the engine intake air, or oxidation products produced by combustion of fuel, etc. In diesel engines, carbon particles contained in the combustion exhaust gas are particularly large in the oil. It is known that it can contaminate lubricating oil by contaminating it. Carbon particles mixed in the oil accelerate wear on the sliding parts of various parts of the engine, so if the concentration of carbon particles increases, measures such as replacing the lubricating oil are taken.

Conventionally, methods for measuring the concentration of carbon particles include extracting a portion of the lubricating oil from the engine, filtering it through a filter, and measuring the weight of the particles collected on the filter, or separating each particle by centrifugation and measuring its weight. Methods such as measuring the However, with this type of method, it is impossible to measure the carbon particle concentration during engine operation or to measure the particle concentration continuously over time. An example of a conventional lubricating oil pollution level measuring device is shown in FIG.

A light source 908 and a photovoltaic cell 904 are attached to both sides of a lubricating oil reservoir 901, making use of the fact that the amount of light received by the photovoltaic cell 904 decreases as the lubricating oil 913 becomes contaminated. In addition, in FIG. 3, 903 and 907 are side walls, and 9
05 is the sensor, 906 is the electric wire, 909 is the mounting hole, 910
is a transparent plate, and 911 and 912 are gears. (Unexamined Japanese Patent Publication No. 57
-98842).

It is impossible to measure the concentration of carbon particles in lubricating oil using this type of method in which the distance between the light source and the light receiving element is long. The reason for this will be explained below. Through various experiments, it was confirmed that the decrease in the amount of light transmitted due to the inclusion of carbon particles in oil is expressed by the following equation. Let T be the light transmittance of dirty oil to new oil, and let T be the distance between the light source and the light receiving element, and more precisely,
When the optical path length in oil is D (dragon) and the number of strikes is K, the carbon weight concentration α (%) in oil is expressed as, and the number of strikes is approximately 17.4 (1/n+
). From the il1 formula, the light transmittance T with respect to the carbon weight concentration is as follows.

FIG. 4 shows the relationship expressed by equation (2), with carbon weight concentration on the horizontal axis and light transmittance on the vertical axis. As is clear from Figure 2, the light transmittance with respect to the carbon concentration changes greatly depending on the optical path length, and when D = 1 + u, α
= about 0.2%, almost no light is transmitted. Specifically, T=3.3Xl0-'. On the other hand, this transmitted light is converted into an electrical signal by a light receiving element facing the light source and drives a concentration display meter and other display devices.
In a typical electrical signal processing circuit, the signal intensity ratio that can be processed is up to about 1:1000. Therefore, as mentioned above, when the light transmittance is D-1m, the light transmittance T reaches 0.001 at a carbon concentration of 0.172%, so above this concentration, the signal becomes too weak and measurement becomes impossible. It becomes possible.

Next, the optical path length is 0.1fi, 0.05 Tsuru, 0.01
Figure 4 shows the transmittance curve when the fin is shortened.
As is clear from the figure, when the optical path length is shortened, the transmittance curve approaches a straight line, making it possible to widen the measurable concentration range. Next, the required measurement concentration range varies depending on the type of engine and other factors, but the upper limit is usually between α-0.5% and 4%, so for example, when trying to measure up to α-0.5%, is α=0.5% and the light transmittance is T=0.
．． An optical path length of 0.34 m can be obtained. Using the same idea, when trying to measure up to α=4%, D=0.043M. As mentioned above, when trying to measure the carbon concentration in lubricating oil using light transmittance, the optical path length of the light is important, and in practice, the optical path length must be 0.34 m or less. Unable to measure the required concentration range. Therefore, the optical path length was set to 0.34 m.
The idea arises that the following should be done.

In addition, in order to widen the concentration measurement range, it is necessary to extremely shorten the optical path length as described above, but shortening D causes the following problems. One of them is: The problem is the accuracy of the optical path length. Figure 3 shows that the optical path length D (optical path gap) is 0.04 m, 0.03 m from 0.05 wm.
It shows changes in light transmission, etc. when changing to m. As is clear from FIG. 3, a slight change in the optical path gap of several tens of microns causes a large deviation in the relationship between the carbon concentration and the light transmittance. That is, there is a problem in that the optical path gap must be accurately defined. In addition, by shortening the optical path gap as described above, the exchange speed of the oil interposed between the light source and the light receiving element is slowed down. For example, when dirty oil is replaced with new oil, the concentration value changes quickly to the new oil. This causes a problem in that it does not return to normal. Furthermore, a problem arises in that the optical path gap is easily clogged with solid contaminant particles.

In view of the above-mentioned problems with the conventional type, an object of the present invention is to select the optical path gap length between the light source window and the light receiving window to be less than or equal to a predetermined length, and to form at least one of the light source window and the light receiving window into a convex shape. Based on the idea of abutting against the surface of the opposite window, the objective is to expand the measurement of lubricating oil contamination to areas with high contamination.

Means for Solving the Problems In the present invention, as a first form, an optical path gap is provided between a light source window provided on the light source side and a light receiving window provided on the light receiving element side, and the optical path gap is A lubricating oil whose degree of contamination is to be measured based on the light transmittance can be present, and the length of the optical path gear is 0.
A lubricating oil contamination measuring device is provided, characterized in that the contamination level of the lubricating oil is selected to be 34n or less.

Further, in the present invention, as a second form, an optical path gap is provided between a light source window provided on the light source side and a light receiving window provided on the light receiving element side, and the light source window and the light receiving window are small (both sides are small). has a convex shape, and lubricating oil whose degree of contamination is to be measured based on light transmittance can be present in the optical path gap, and the tip of the convex surface of the window having the convex shape is connected to the opposite window. A lubricating oil contamination level measuring device is provided, which is characterized in that it is in contact with a surface.

EXAMPLE FIG. 1 shows a lubricating oil contamination measuring device as an example of the first embodiment of the present invention. In the device shown in FIG. 1, 11
1 is a light source such as a light emitting diode, 12 is a light receiving element such as a photodiode or a phototransistor, 21 and 22 are windows made of glass or transparent synthetic resin, and an optical path gap 3 is formed between opposing surfaces of 21 and 22. In the device shown in FIG. 1, the gap 3 is 0.34n or less. Reference numeral 5 is a part of the body made of resin or part of metal, and serves not only to hold the light source and the light receiving element in a specified position, but also to attach it to the engine's oil reservoir or other parts. Reference numeral 6 indicates a terminal section for connecting the light source and the light receiving element to a signal processing and display section (not shown). As mentioned above, the relationship between the optical path gap 3 and the measurable carbon particle concentration in oil is up to 0.5% for D = 0.34 mm, 1.7% for D = 0.1 IIm, and 1.7% for D = 0.0.
For five fins, it is up to 3.4%.

In this type of method, it is necessary to accurately define the optical path gap 3, and an example of a configuration for realizing this is shown in FIG. In FIG. 2, reference numeral 4 denotes a substantially cylindrical spacer ring having substantially U-shaped protrusions 41, 42, and 43 at three locations on its circumference.
, 22, the optical path gap to be formed between 21 and 22 is the projections 41, 42, 4.
A thickness of 3 can be defined almost accurately.

A lubricating oil contamination measuring device as an example of the second embodiment of the present invention is shown in FIG. In FIG. 6, the same reference numerals as in FIG. 4 indicate the same components. In the device shown in FIG. 1, the opposing surfaces of the windows 21 and 22 were flat, but
In the device shown in FIG. 6, this is a convex spherical surface, and both are in contact with each other. Note that the radius of this spherical surface is about 1 to 3 fi. With the above configuration, the optical path gap has various optical path lengths from almost zero to several fins, and a sufficiently high output voltage can be maintained even at high concentrations.

The characteristics of the device shown in FIG. 6 are shown in FIG. In FIG. 7, the horizontal axis represents the carbon weight concentration α (%), and the vertical axis represents the receiver output voltage E (OIIT) (V). Curve A in FIG. 7 shows the case of the apparatus shown in FIG. 1 with an optical path gap of 0.1, and curve B shows the case of the apparatus shown in FIG. 6 with a spherical radius of 2.5. As is clear from FIG. 7, in the device shown in FIG. 6, there is no sudden drop in the photoreceiver output voltage E (OUT) even on the high concentration side, indicating that measurements can be made over a wide range. Furthermore, since the apparatus shown in FIG. 6 utilizes an optical path gap created by bringing two spherical surfaces into contact, it has the advantage that there is no need for gap adjustment during manufacture. Furthermore, since there is less stagnation of oil in the gap, there is an advantage that the ability to follow changes in concentration over time is also improved. Furthermore, the embodiment of the second aspect of the present invention has the advantage that the presence or absence of oil can be detected in addition to measuring the carbon concentration. This point will be explained below using FIGS. 8 and 9.

Figure 8 shows the path of light from the light source to the light receiving element when oil is present. When oil is present, the light is refracted mainly by the windows 21 and 22 made of glass or the like and by the oil. Since the ratios are approximately equal, the light is transmitted through the windows 21 and 2.
Go straight regardless of the shape of the convex part 2. Therefore, light that is largely deviated from the optical axis connecting the light source 11 and the light receiving element 12 does not reach the light receiving element. On the other hand, FIG. 9 shows the light path in the absence of oil, but due to the lens action of the windows 21 and 22, most of the light from the light source reaches the light receiving element 12, and the amount of light received by the light receiving element is , increases significantly compared to the case where oil is present. That is, it is possible to detect the presence or absence of oil.

Note that 72 and 84 are power supplies for driving the light source and the light receiving element, respectively, 71 is a stabilizing resistor, and 82 is a resistor for detecting the photocurrent flowing through the light receiving element, and a voltage proportional to the amount of light received is applied across the resistor. This occurs between terminals 81 and 83 connected to. This voltage is converted into a carbon concentration by an electric circuit using a conventionally well-known technique to drive a display device and other devices.

FIG. 10 shows another example in which one side of the window is spherical and the other is flat. The operation and effect are similar to those shown in FIGS. 8 and 9.

Next, FIG. 11 shows an example in which one side of the window is made into a convex cone based on the same idea. In the figure, a surface 211 of the window 21 facing the window 22 is a conical surface. FIG. 12 shows a case where the window has a cylindrical surface shape. The effects are almost the same as when the window is a convex spherical surface.

In the embodiments described above, the light emitting diode as the light source and the photodiode as the light receiving element are:
Used while immersed in oil.

On the other hand, since the lubricating oil temperature of the engine rises to about 120° C. during operation, errors may occur in the measured values depending on the temperature characteristics of each element.

In order to avoid this, the examples shown in FIGS. 13(A), 13(B), and 13(C) show examples in which each element is not immersed in oil. In FIG. 13, 100 indicates a detection part immersed in oil, and 108 and 109 are windows 21 and 22 for forming an optical path, and optical fibers 108 and 109 for guiding light from the outside to the window part. It consists of a light guide shown, and prisms shown 212 and 222 for changing the direction of light by 90 degrees.

Reference numeral 200 indicates a light transmitting/receiving element section, in which a light emitting diode 11 and a photodiode 12 are incorporated.

300 has a light guide 3 inside with a cable that connects the two.
14, 315, and connector parts 311, 313
are coupled to iio, 201, respectively. With the above configuration, the light transmitting/receiving section can be installed in a place with relatively low temperature, so that the influence of temperature can be almost avoided.

FIG. 14 shows an example of the structure for mounting the device shown in FIG. 4 on an engine. 41G is an engine oil pan, 417 is lubricating oil, M is a measuring device, and 419 is a drain plug.

420 indicates the oil level at normal times, and 421 indicates the oil level at the lower limit of oil amount. By attaching the measuring device M at the oil level position at the lower limit, it is also possible to detect the oil amount.

Note that the measuring device shown in FIG. 4 can also be attached to the tip of a level gauge that is normally used to monitor the amount of oil.

Effects of the Invention According to the present invention, a lubricating oil contamination measuring device can be constructed based on the relationship between the lubricating oil contamination, the optical path length, and the light transmittance, and the lubricating oil contamination can be measured at a high level. It can be extended to the pollution range.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a lubricating oil pollution level measuring device as an embodiment of the first embodiment of the present invention, FIG. 2 is a diagram showing another embodiment of the first embodiment of the present invention, and FIG. 1 is a diagram showing an example of a conventional lubricating oil contamination degree measuring device, FIGS. 4 and 5 are characteristic diagrams explaining contamination degree measurement characteristics, and FIG. 6 is an embodiment of the second embodiment of the present invention. FIG. 7 is a diagram showing the characteristics of the device shown in FIG. 6; FIG. 8 and FIG. 9 are both diagrams for explaining the operation of the device shown in FIG. 6. Figures 10, 11, 12, and 13 (A) (
B) and (C) are diagrams showing other embodiments of the second embodiment of the present invention, and Fig. 14 shows how the lubricating oil pollution level measuring device as an embodiment of the present invention is attached to an engine due to the structure. It is a figure showing an example. (Explanation of symbols) 11... Light source, 12... Light receiving element, 21... Light source window, 22... Light receiving window, 3... Optical path gap, 4... Spacer ring, 41, 42
, 43...Protrusion, 5...Body part, 6...Terminal part, 71...Stabilizing resistor, 72...Power supply, 81,
83...terminal, 82...resistance. Figure 1 shows 1'J2 figure'; g 3 'i:':'1 4th F, 7 0 1 2 (wtZ) -m--be Figure 5 Arrow 6 times Ax・8 Figure 4 Figure 10 110 11 121st force

Claims (1)

[Claims] 1. An optical path gap is provided between a light source window provided on the light source side and a light receiving window provided on the light receiving element side, and the degree of pollution is measured based on the light transmittance in the optical path gap. 1. A lubricating oil contamination degree measuring device, characterized in that the lubricating oil to be removed can be present, and the length of the optical path gap is selected to be 0.34 m or less. 2. An optical path gap is provided between a light source window provided on the light source side and a light receiving window provided on the light receiving element side, and at least one of the light source window and the light receiving window has a convex shape, and a light path gap is provided in the optical path gap. A lubricating oil whose degree of contamination is to be measured based on light transmittance may be present, and the tip of the convex surface of the window having a convex shape is brought into contact with the surface of the opposite window. A lubricating oil contamination measurement device featuring: 3. The device of claim 2, wherein both the light source window and the light receiving window have a convex shape.