JP3346004B2 - Liquid particle concentration detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical particle concentration detecting device capable of accurately measuring the particle concentration in a liquid having a very low light transmittance.

[0002]

2. Description of the Related Art Deterioration of a lubricating oil such as a diesel engine is determined by the amount of carbon particles contained in the lubricating oil. That is, it is determined that the lubricating oil is to be renewed at an upper limit of the concentration of carbon particles contained in the lubricating oil of 3 to 5 wt%.

[0003] Such a device 9 for detecting the concentration of particles in lubricating oil.
13, the lubricating oil 8 is introduced between the light emitting element 91 and the light receiving element 92, as shown in FIG. There is one that detects oil contamination (Japanese Unexamined Patent Publication No. Sho 61-61).
No. 213749). In the figure, reference numeral 93 denotes a thermistor thermometer for temperature correction, reference numeral 94 denotes an input / output terminal plate, and reference numeral 95 denotes a screw portion for screwing into a lubricating oil pipeline.

[0004]

However, the device 90 for detecting the concentration of particles in liquid has the following problems. The first problem is that, with respect to the test liquid 8 having a low light transmittance, the light transmission amount is extremely small, and the sensitivity is deteriorated. As a countermeasure, there are a method of greatly increasing the intensity of the inspection light to be incident, and a method of reducing the thickness t of the inspection target liquid in the light transmission direction.

[0005] However, if the inspection light is intensified, there is a problem that the liquid to be inspected and the particles contained therein are deteriorated, and the reduction in the thickness t of the liquid to be inspected is difficult if the particle diameter d is close to the thickness t. There is a problem that particles are clogged. The second problem is that when the liquid to be inspected contains bubbles or the like, the intensity of transmitted light is changed by the bubbles, and the particle concentration cannot be measured accurately.

A third problem is that particles in the liquid adhere to the light emitting surface from which the inspection light is emitted and the light receiving surface to which the transmitted light is incident, and a detection error easily occurs. In view of the conventional problems, the present invention provides a liquid particle concentration detecting device that does not decrease sensitivity even for a liquid having a low light transmittance and is not easily affected by non-particle foreign substances such as air bubbles. It is something to offer.

[0007]

According to the present invention, there is provided a light emitting unit which emits inspection light which comes into contact with a liquid to be inspected and is totally reflected at a boundary surface thereof,
It has an optical sensor that receives the total reflected light, a reference optical sensor that directly receives the inspection light, and a determination unit that determines the reflectance from the output signals of both optical sensors and calculates the particle concentration in the liquid based on the reflectance. In the liquid particle concentration detector.

The first point of most note in the present invention is that the inspection light emitted from the light emitting portion to the inspection target liquid is totally reflected at the boundary surface. That is, assuming that the refractive index of the inspection target liquid is n ₂ and the refractive index of a light emitting portion (hereinafter referred to as a “boundary portion”) forming a detection surface in contact with the inspection target liquid is n ₁ , the inspection light 82 shown in FIG. The incident angle θ ₁ is equal to the total reflection angle θ _C (= sin ⁻¹
n ₂ / n ₁ ), which means that the position of the light source and the refractive index n ₁ at the boundary are determined.

In the present invention, the second point to be noted is that the optical sensor is disposed at a position capable of receiving the total reflection light, and furthermore, a reference optical sensor for directly receiving the inspection light is provided. It is arranged. The determination unit is an arithmetic circuit that calculates the reflectance based on the output signals of the two optical sensors that change according to the particle concentration, and determines the particle concentration of the inspection target liquid based on the reflectance. As the above-mentioned liquid particle concentration detecting device, for example, there is a lubricating oil deterioration detecting device for a diesel engine which determines the deterioration of lubricating oil from the carbon particle concentration.

It is preferable that a container for the liquid to be inspected is provided, and a cleaning member that floats due to the fluid movement of the liquid to be inspected is mixed into the container. If the cleaning member floats due to the fluid movement of the liquid to be inspected including convection, it will collide with the detection surface, and by repeating such collisions, foreign matter will adhere to the detection surface, preventing light from entering the inspection light or preventing light from entering. This is because a change in the amount of light received by the sensor is suppressed.

[0011] When such a cleaning member is mixed in the liquid, there is a concern that the amount of reflected light may be changed. However, such a drawback is that the measurement time for measuring the light becomes longer than a certain time. The problem is solved by using the time average value. That is, since the cleaning member floats, the frequency of the cleaning member entering the light reflection path can be almost ignored if the length of the measurement member is longer than a predetermined value.

[0012] It is extremely difficult to mix such a cleaning member into the accommodating section with a conventional translucent particle concentration detecting device in liquid. First, the gap between the light entrance and the light exit is extremely narrow for liquids with low light transmittance.
In addition, the transmitted light is blocked by the mixing of the cleaning member, and the amount of received light changes.

Further, a plurality of detection surfaces which come into contact with the liquid to be inspected and totally reflect the inspection light at the boundary surface are provided, and the inspection light emitted from the light source of the light emitting section is totally reflected by the plurality of detection surfaces, and then the optical sensor is provided. It is preferable to form an optical path so as to reach. This is because, by providing a plurality of detection surfaces, the rate of change of total reflection light with respect to the test liquid having the same particle concentration can be greatly increased.

As will be described in detail later, the intensity of the totally reflected light on the detection surface changes (decreases) according to the particle concentration of the liquid to be inspected. If a plurality of total reflections are performed on a plurality of detection surfaces, the rate of change of the total reflected light is accumulated, and as a result, the rate of change that is difficult to detect with one total reflection is detected. Because it becomes.

Forming an optical path so that total reflection can be performed on a plurality of detection surfaces as described above can be achieved by disposing the plurality of detection surfaces at different angles or by changing the path of inspection light. And the like can be appropriately arranged (for example, see Example 2 and FIG. 8).

Further, a plurality of mirrors and the like are arranged in the optical path from the light source to the optical sensor, and the optical path is changed by the mirrors and the like, so that the totally reflected light is incident on the optical sensor arranged on the same substrate as the light source. It is preferable to form an optical path so as to cause the light path. This is because if the light source and the optical sensor can be arranged on the same substrate as described above, the two members can be easily assembled because they are on the same substrate, and the number of substrates can be reduced to one to reduce the cost. This is because

In the first place, general circuit components mounted on a substrate have no restrictions on optical mounting angles, and can be mounted on the same substrate. On the other hand, the light source and the optical sensor are limited in the mounting angle due to optical requirements, and they are generally required to be mounted on different substrates. Therefore, the two members are mounted on separate substrates or mounted outside the substrate on which circuit components are mounted (see FIGS. 1 and 13). However, the above configuration solves the above problem,
Both members can be mounted on the same substrate.

[0018] That is, the total reflection light 83 reflected by the detection surface and the inspection light 82 incident on the detector surface, as shown in FIG. 1, has an angle of 2 [Theta] ₁ not is intact collimated (Θ ₁ is the incident angle of the inspection light). Therefore, this remains a will have an angle of mounting angles 2 [Theta] ₁ of the light source and the light sensor, arranged parallel to each other on the same substrate (vertical arrangement on substrate)
I can't.

However, if the optical path of the inspection light (total reflection light) is appropriately changed by using a mirror or the like as described above, the inspection light emitted from the light source and the total reflection light incident on the optical sensor become parallel. It becomes possible. As a result, it is possible to arrange the light source and the optical sensor in parallel on the same substrate. The “mirror or the like” includes the detection surface itself in addition to the plane mirror. This is because the detection surface performs the same reflection function as a plane mirror.

In the mirror or the like for changing the path of the inspection light, for example, the main part of the optical path is formed by a prism, and can be formed on the outer wall surface of the prism.
That is, the prism has a plurality of outer wall surfaces that cross each other, and these outer wall surfaces are formed at appropriate positions to have an appropriate angle, and a mirror or the like that reflects inspection light is formed on the outer wall surface. By doing so, a desired optical path can be formed.

In the optical path from the light source to the optical sensor,
It is preferable to provide an aperture for selectively passing only light incident at a predetermined angle. By arranging the aperture, it is possible to remove disturbance light entering from an angle different from the desired inspection light, noise light in the inspection light, and scattered light in the total reflection light. This is because the S / N ratio of the device can be increased and the detection accuracy can be improved.

For example, apertures are provided in the light path on the light entrance side and the light path on the light exit side of the prism. By providing the aperture on the light incident side, inspection light at a fixed angle can be made incident on the detection surface, and the noise light and the like can be cut. Further, by providing an aperture in the light path on the light exit side, only regular total reflection light can be made incident on the optical sensor, and scattered light, noise light, and the like can be cut.

Further, the structure of the liquid particle concentration detecting device includes a projection inserted into a container or a conduit for containing the liquid to be inspected, and a fixing member for inserting and fixing the projection into the container or the conduit. It is preferable to provide a detection surface on the protrusion.
With this configuration, a storage section for introducing the liquid to be inspected and a conduit for guiding the liquid to be inspected to the storage section are not required.
The number of components is reduced. In addition, because it can be directly mounted on a container or a conduit of the liquid to be inspected, the device for detecting the concentration of particles in liquid can be installed without taking up space.

Further, it is preferable to provide an enclosing portion of a cleaning member for allowing the liquid to be inspected to pass freely on the detection surface of the projection. As described above, the cleaning member is a member that floats due to the fluid movement of the liquid to be inspected, and can prevent the detection surface from being stained.

As shown by the following equation (1) (indicator of the penetration depth of the evanescent wave), the wavelength λ of the inspection light is increased and the incident angle θ ₁ of the inspection light is decreased (where θ ₁ >).
θ _c ) Further, by decreasing the refractive index of the prism, the rate of change of total reflection light with respect to the particle concentration, that is, the detection sensitivity can be increased. For example, when the liquid to be inspected is a diesel engine lubricant, the light source may be red or infrared (6
LED emitting light of wavelength of not less than nm), such as a semiconductor laser, such as with a glass or a resin which transmits light to medium light emitting portion forming a detection surface, the incident angle theta ₁ is total reflection critical angle theta _C The optical system is configured to have a value close to.

[0026]

[Operation and Effect] As shown in FIG.
When the light travels from the first medium 801 having the refractive index n ₁ to the second medium 802 having the refractive index n ₂ at an angle θ ₁ equal to or larger than _C , the light has a refractive index n ₂
Does not enter the second medium 802, but is totally reflected. However, if this phenomenon is observed in detail, the reflected light will be emitted from point B, which is separated by G from incident point A.

That is, as shown by the broken line in FIG. 6, the light once enters the second medium 802 and exits from the point B. The incoming light is called an evanescent wave, and the interval G is called Goose-Henschen shift. Then, the second medium 8
When solid foreign matter 81 such as carbon is present in
As shown in (1), since the evanescent wave is absorbed and scattered, the intensity of the totally reflected light decreases.

The depth of the light entering the second medium 802 is determined by the wavelength λ of the light, the refractive indices n ₁ and n of the media 801 and 802.
₂ , it varies depending on the incident angle θ _{1 and the} like. That is, the penetration depth D at which the electric field strength of the evanescent wave attenuates to 1 / e.
Is represented by the following equation. D = λ × {2π (n ₁ ² sin ² θ ₁ −n ₂ ² ) ^1/2 } (1) Then, as the penetration depth D of the evanescent wave becomes larger, the fixed foreign matter 81 suffers. Since the absorption and the scattering increase, the degree of the change (decrease) of the total reflected light also increases.

The present invention detects the particle concentration of the liquid to be inspected by utilizing the above phenomenon. That is, since the reflected light 83 totally reflected from the boundary surface with the liquid to be inspected attenuates in proportion to the particle concentration in the liquid as shown in FIG. 5, the intensity of the reflected light decreases, that is, the reflectance changes. The particle concentration of the test target liquid can be detected.

At this time, an appropriate area S of the detection surface corresponding to the particle concentration and sampling at the judging section are set so that the number of particles existing in the penetration depth δ (≒ λ / 2) of the evanescent wave does not vary. A time length T (a time length for measuring the amount of received light) is selected. That is, by preventing the number of particles present in the volume S × δ on the detection surface of the liquid to be inspected from fluctuating in the sampling time T, there is no variation in measurement accuracy.

In the present invention, since the reflected light in the liquid to be inspected is detected to detect the particle concentration, it is not affected by the magnitude of the light transmittance in the liquid to be inspected. Therefore, the sensitivity does not decrease at all even for a liquid to be inspected having a low transmittance. Also, even if bubbles exist in the liquid to be inspected, there is almost no effect on the evanescent wave. That is, since the penetration depth δ of the evanescent wave is extremely shallow, the probability that the evanescent wave hits the bubble is extremely small. Even if the evanescent wave collides with the bubble, the evanescent wave is almost scattered by the non-particle foreign matter such as the bubble. For they will not receive it.

In the conventional translucent particle concentration detecting apparatus in liquid (FIG. 13), particles adhere to two surfaces, a light emitting surface and a light receiving surface, and have a function of weakening the amount of light received by the optical sensor. In the present invention for measuring reflected light, there is only a single detection surface, so that the effect can be reduced by half. In addition, since it is of the reflection type, the depth of the storage section for storing the liquid to be inspected can be increased. This is because in the transmission type, the amount of transmitted light is attenuated depending on the depth of the liquid to be inspected. Therefore, the cleaning member can be mixed into the housing portion, and thereby the contamination on the detection surface can be suppressed.

Since the reflected light measurement method is used, the presence of the cleaning member has almost no influence on the detection accuracy, similarly to the presence of bubbles. Further, even if the presence of the cleaning member slightly affects the amount of received light, if the sampling time T in the determination section is increased, the effect of the cleaning member can be made uniform, so that the measurement accuracy is not affected. As described above, according to the present invention, there is provided an apparatus for detecting the concentration of particles in a liquid that does not decrease in sensitivity even to a liquid having a low light transmittance and is hardly affected by non-particle foreign substances such as bubbles. Can be.

[0034]

【Example】

Embodiment 1 An apparatus for detecting the concentration of particles in liquid according to an embodiment of the present invention will be described with reference to FIGS. In this embodiment, the deterioration of the lubricating oil is determined by detecting the concentration of carbon particles contained in the lubricating oil of the diesel engine. In the present embodiment, as shown in FIGS.
A light emitting unit 11 that emits an inspection light 82 that is totally reflected at
An optical sensor 12 that receives the reflected light 83 with respect to the liquid 8 to be inspected, a reference optical sensor 13 that directly receives the inspection light 82, and a reflectance σ is obtained from output signals of both optical sensors 12 and 13, and inspection is performed based on the reflectance σ. A liquid particle concentration detection device 10 having a determination unit 20 for calculating the particle concentration α in the target liquid 8
It is.

The liquid 8 to be inspected in this embodiment is a lubricating oil of a diesel engine, and the judging section 20 further judges the deterioration of the lubricating oil from the particle concentration σ. In addition, the cleaning member 35 of the detection surface 31, which floats due to the fluid movement of the inspection target liquid 8, is mixed into the container 30 of the inspection target liquid 8 having the detection surface 31 in contact with the inspection target liquid 8 and receiving the inspection light 82. Let me do it.

Hereinafter, each of them will be described in detail. As shown in FIGS. 1 and 2, the inspection light 82 emitted from the light source 111 of the light emitting unit 11 travels in the prism 15, is totally reflected at the boundary surface 80 with the liquid 8 to be inspected, and the reflected light 83 is ,
The light enters the optical sensor 12.

That is, the refractive index of the prism 15 is n ₁ , the refractive index of the liquid 8 to be inspected is n _2, and the incident angle of the inspection light 82 is θ
Assuming that ₁ , the relationship θ ₁ > sin ⁻¹ (n ₂ n ₁ ⁻¹ ) holds. A reference optical sensor 13 that is in contact with the prism 15 is disposed on a side of the detection surface 31 of the housing 30. The reference optical sensor 13 is an optical sensor that detects the intensity of the inspection light 82.

The storage section 30 for storing the liquid 8 to be inspected is
As shown in FIG. 1, it has an inflow portion 301 of the test liquid 8, an outflow portion (not shown), and a detection surface 31 for the inspection light 82. In addition, an outflow prevention member 45 of a wire mesh cleaning member 35 is disposed at the inflow portion 301 and the outflow portion.
The mesh of the outflow prevention member 45 is formed finer than the size of the cleaning member 35.

The cleaning member 35 accommodated in the accommodating portion 30 together with the liquid 8 to be inspected is formed of a fluororesin or the like so as not to damage the prism 15 and to have durability in the liquid 8 to be inspected. As shown in FIG. 4, the shape of the cleaning member 35 is a sphere having a small spherical concave portion (FIG. 4A), a sphere (FIG. 4B), and a sphere having a small spherical convex portion (FIG. (C)), a regular tetrahedron (FIG. 4D), a combination of two spheres (FIG. 4E), and the like. Each of these cleaning members 35 has a shape and specific gravity that are easy to move in accordance with the flow of the test target liquid 8.

As a material of the cleaning member 35, fluorine rubber, glass, ceramic, metal or the like can be used in addition to the fluorine resin. Further, the cleaning member 35 may be hollow to obtain an appropriate specific gravity. Further, it is preferable that the surface of the cleaning member 35 is made of a substance having a low light reflectance. In order to satisfy these conditions, the material at the center and the material at the surface can be made of different substances. For example, it can be formed of a Teflon ball in which an iron core is covered with Teflon, a fluororubber ball in which an iron core is covered with fluororubber, or the like.

FIG. 3 shows the entire apparatus for detecting the concentration of particles in liquid 10.
Has a cross-sectional shape as shown in FIG. An optical system member such as a prism 15 is disposed at the center, and an inflow pipe 61 for the liquid 8 to be inspected is provided below the optical system member. Have. Further, a printed wiring board 65 on which the determination unit 20 is mounted is disposed above. In FIG. 3, reference numeral 69 denotes a signal and power input / output connector.

The liquid 8 to be inspected flows in from the inflow pipe 61 and flows out of the outflow pipe (not shown) through the storage section 30. The inspection target liquid 8 comes into contact with the prism 15 in the storage unit 30. An optical sensor 12 and a light source 111 are mounted on the left and right side surfaces of the prism 15, and a reference optical sensor 13 (not shown) is mounted on the bottom surface.

On the other hand, as shown in FIG.
Driver circuit 21 for driving LED as light source 111
And the output signals I of the optical sensor 12 and the reference optical sensor 13
₁ , a signal amplifier 22 for amplifying I ₀ , a division circuit 23 for dividing the amplified output V ₁ of the optical sensor 12 by the amplified output V ₀ of the reference optical sensor 13 to obtain a reflectance σ,
(= I ₁ / I ₀ ) is compared with the reference reflectance σ _S to determine a deterioration of the lubricating oil, and a drive circuit 25 for driving an alarm display device (not shown). The determination circuit 24 may be configured to convert the reflectance σ into a particle concentration α according to the characteristic diagram shown in FIG. 5 and output the particle concentration α.

A thermistor thermometer 26 is provided near the boundary surface 80 of the prism 15, and its output signal T is input to the driver circuit 21. The driver circuit 21 determines that the temperature output signal T is within a certain range T
Only when in the ₁ through T ₂ actuates the determination unit 20.

Therefore, the particle concentration is measured only when the temperature of the lubricating oil as the liquid 8 to be inspected is in a substantially constant range T _{1 to} T _2, and almost no error occurs due to the lubricating oil temperature difference. . Further, the output signal I ₁ of the optical sensor 12 of the reflected light 83 is amplified and divided by the output signal I ₀ of the reference optical sensor 13 to be converted into a reflectance σ.
No detection error occurs even if the intensity of the light 1 fluctuates.

Next, the operation of the cleaning member 35 will be described. The test target liquid 8 flows in a certain direction, and convection also occurs in the storage unit 30. On the other hand, the cleaning member 35 is sealed in the housing part 30 by the outflow prevention member 45. Therefore, the cleaning member 35 is connected to the inspection target liquid 8.
Floats in the accommodating section 30 under the force of. Therefore, the cleaning member 35 collides with the detection surface 31 which is the boundary surface of the prism 15 with the liquid 8 to be inspected, and dissolves the dirt on the detection surface 31 and releases it from the detection surface 31. In addition, there is an effect of preventing stains from growing on the detection surface 31 beforehand.

In this embodiment, the dirt on the detection surface 31 can be removed by a relatively simple configuration in which the cleaning member 35 is mixed without providing a special dirt removing mechanism such as a wiper on the detection surface 31. As described above, according to the present embodiment, with a simple structure, there is provided the liquid particle concentration detection device 10 which can prevent or remove stain on the boundary portion (detection surface 31) between the prism 15 and the test liquid 8. can do. It is more effective if the flow of the liquid in the flow path is promoted by means such as intermittently giving an impulse flow to the test target liquid 8.

Since the liquid particle concentration detecting device 10 of this embodiment measures the total reflection light 83 and detects the particle concentration, it is irrelevant to the magnitude of the light transmittance of the liquid 8 to be inspected. Therefore,
The particle concentration can be accurately measured even for the test target liquid 8 having a low light transmittance. In addition, the inspection target liquid 8
Even if non-particle foreign substances such as air bubbles are present therein, as described above, they are hardly affected.

Further, the contamination of the detection surface 31 is removed by the cleaning member 35.
Therefore, errors due to contamination of the detection surface 31 are less likely to occur. As described above, according to this example, the sensitivity does not decrease even for a liquid having a low light transmittance, and it is hardly affected by non-particle foreign substances such as air bubbles.
Further, it is possible to provide the in-liquid particle concentration detection device 10 capable of suppressing an error due to contamination of the detection surface 31.

In this embodiment, the thermistor thermometer 26 is arranged near the liquid 8 to be inspected to measure the particle concentration of the liquid to be inspected in a certain temperature range. Light source 1
There is also a method of controlling the operating ambient temperature of the LED 11 to a certain value or less (for example, 100 ° C.) to extend the life of the LED.

Embodiment 2 In this embodiment, as shown in FIG. 8, in Embodiment 1, three detection surfaces 361 to 363 which come into contact with the liquid 8 to be inspected and totally reflect the inspection light 82 at the boundary surface are provided. This is another embodiment in which the detection surfaces 361 to 363 are configured to be inserted and fixed in a container or a conduit for accommodating the liquid 8 to be inspected.

Hereinafter, each part will be described. In this example, as shown in FIG. 8, there are three detection surfaces 361 to 363 which come into contact with the liquid 8 to be inspected and totally reflect the inspection light 82 at the boundary surface. Then, the inspection light 82 has three detection surfaces 361.
363, the light is totally reflected, and reaches the optical sensor 12.

Then, the inspection light 82 is transmitted to the detection surfaces 361-361.
The light path is changed by 62 and the light source 1 is placed on the same substrate 66.
The light is incident on an optical sensor 12 arranged close to the optical sensor 11. The detection surfaces 361 to 363 are formed on the outer wall surface of the prism 16. An aperture 1 for selectively passing the inspection light 82 and the reflected light 83 incident at a predetermined angle on the light path on the light entrance side and the light path on the light exit side of the prism 16.
81 and 182 are provided.

Further, the above-mentioned liquid particle concentration detecting device 10
As shown in FIG. 8, a projection 41 is inserted into a container or conduit or the like containing the liquid 8 to be inspected, and a fixing member 42 is inserted into the container or conduit or the like and screwed and fixed. The protrusion 41 has detection surfaces 361 to 363 formed thereon. The projecting portion 41 is provided with an enclosing portion 43 of a cleaning member 35 which covers the detection surfaces 361 to 363 and allows the inspection target liquid 8 to pass freely. The floating cleaning member 35 is accommodated.

In this example, the wavelength λ of the inspection light 82 is 940.
nm, the test liquid 8 is engine oil of a diesel engine, and its refractive index n ₂ is 1.48 (λ =
940 nm). Further, the prism 16 is
11 or FD11, and the refractive index n ₁ is 1.759 (λ = 940 nm) (the total reflection angle critical angle θ _c1 is 56 ° if the refractive index of the engine oil is 1.46, If the refractive index is 1.50, it becomes 58.5 °).

The three detection surfaces 361 to 363 are formed on the outer wall surface of the prism 16 so as to have an angle difference of 120 ° sequentially. Inspection light 82 emitted from light source 111
Enters the prism 16 via the first aperture 181 and enters the first detection surface 161 at an incident angle θ ₁ = 60 °.

Then, the light is totally reflected by the second detection surface 162
At an incident angle of 60 °, is totally reflected again, and
At 63, an incident angle of 60 ° is applied. The inspection light 82 is again totally reflected here and passes through the second aperture 182 to the optical sensor 1.
An optical path is formed so as to be incident on the light source 2.

As is known from the figure, the reflected light 83 incident on the optical sensor 12 has a parallel direction (an angle difference of 180 °) opposite to the inspection light 82 emitted from the light source 111.
The light source 111 and the optical sensor 12 are mounted on the substrate 66 in parallel (both vertically). Note that a circuit component of a reference sensor and a determination unit (not shown) is also mounted on the board 66.

The projection 41 has detection surfaces 361-36.
An enclosing portion 43 of the cleaning member 35 is provided so as to cover 3. The enclosing part 43 is formed by a wire net, and is formed in a shape in which the cleaning member 35 operates effectively. A male screw 421 is formed on the surface of the fixing member 42. The male screw 421 is screwed into a screw hole provided in a container or a conduit of the liquid 8 to be inspected (not shown) to detect the particle concentration in the liquid. The device 10 can be mounted.

The above-mentioned container or pipe is, for example, an oil passage of an engine oil (such as a bracket of an oil filter) or an oil pan. In FIG. 8, reference numeral 40 denotes a housing of the liquid particle concentration detecting device 10, and reference numeral 401 denotes an O-ring for liquid sealing.

Next, the operation and effect of this embodiment will be described. The liquid particle concentration detection device 10 of this example has three detection surfaces 361 to 363, and each detection surface 361
The total reflection light of the inspection light 82 in ３６363 changes (decreases) according to the particle concentration in the liquid. Therefore, the rate of change of the amount of received light corresponding to the particle concentration detected by the optical sensor 12 increases almost algebraically as compared with the case where there is only one detection surface. As a result, the detection sensitivity with respect to the particle concentration is greatly increased.

The inspection light 82 is incident on the three detection surfaces 361 to 363 having an angle difference of 120 ° at an incident angle of 60 °, and the optical path is changed. As a result, the optical sensor 1
2 and the inspection light 82 emitted from the light source 111 are in opposite directions by 180 °.

Therefore, the light source 111 and the optical sensor 12 can be arranged completely in parallel, and the same substrate 6
6 (in the first embodiment, as shown in FIGS. 1 and 3, the light source 111 and the optical sensor have different mounting angles and cannot be mounted on the same substrate). Therefore, in this example, both members including the circuit components of the determination unit can be mounted on the single substrate 66, and the number of steps for assembling the components can be greatly reduced.

The liquid particle concentration detecting device 10 of this embodiment
Can be directly attached to a container or a conduit of the liquid 8 to be inspected by using the fixing member 42, so that a housing section (see reference numeral 30 in FIG. 1) for introducing the liquid 8 to be inspected and the inspection The introduction conduit for the target liquid 8 is unnecessary, and the number of parts can be reduced. In addition, since it is mounted on a container or a pipeline, the installation space is reduced.

Further, since the apertures 181 and 182 are provided on the light entrance side and the light exit side of the prism 16, the entrance of noise light and scattered light can be eliminated, and the S / N ratio can be improved. The accuracy is improved. Others are the same as in the first embodiment.

Embodiment 3 This embodiment is another embodiment in which one detection surface 364 and two mirrors 371 and 372 are formed on the outer wall surface of the prism 17 in Embodiment 2 as shown in FIG. It is.
That is, the inspection light 82 emitted from the light source 111 is incident on the incident surface 171 of the prism 17, is reflected by the first mirror 371 which is a plane mirror, and is incident on the detection surface 364.

After being totally reflected by the detection surface 364 and again reflected by the second mirror 372 which is a plane mirror,
It exits from 72 and enters the optical sensor 12. Prism 1
7 is made of FF5, TiFN5, etc.
Its refractive index n ₁ is about 1.577 (at λ = 940 nm)
(The critical angle of total reflection angle θ _c is 67.8 ° when the refractive index of the engine oil is 1.46 and 72 ° when the refractive index of the engine oil is 1.50). Further, the incident angle with respect to the detection surface 364 is equal to or larger than the total reflection angle critical angle θ _c2 and is 67.8 ° or 7
2 °.

The inspection light 82 radiated from the light source 111 and the reflected light 83 incident on the optical sensor 12 are in substantially parallel directions, and the light source 111 and the optical sensor 12 are mounted on the same substrate 66. Further, as shown in FIG. 10, the reference light sensor 13 is mounted on the substrate 66, and circuit components of a determination unit (not shown) are also mounted. Others are the same as the second embodiment.

Embodiment 4 In this embodiment, as shown in FIG. 11, in Embodiment 2, the first detection surface of the prism 160 (reference numeral 361 in FIG.
The detection surface (FIG. 8, reference numeral 363) is connected to mirrors 373 and 374.
This is another embodiment in which is replaced by. That is, the optical path of the liquid particle concentration detecting device 10 of this example is the same as that of the second embodiment, but the number of the detection surface 365 is different from that of the second embodiment.
The mirrors 373 and 374 are plane mirrors that do not come into contact with the liquid to be inspected. Others are the same as in the first embodiment.

Embodiment 5 As shown in FIG. 12, this embodiment differs from Embodiment 3 in that the shape of the prism 18 is changed, and two mirrors 375 and 376 are provided on the outer wall surface of the prism 18.
Is another embodiment in which an optical path is formed so as to be reflected a plurality of times by each of the mirrors 375 and 376.

That is, as shown in FIG. 12, the inspection light 82 is reflected by both the first mirror 375 and the second mirror 376 and enters the detection surface 366. Then, the reflected light 83 totally reflected by the detection surface 366 is reflected by the first mirror 375 and the second mirror 376, then reflected by the first mirror 375 again, and enters the optical sensor 12. The prism 18
The input / output surface 181 is formed as an inclined surface that is not parallel to the detection surface 366.
It is arranged in parallel with 81. Others are the same as the third embodiment.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an optical system of an oil deterioration detection device according to a first embodiment.

FIG. 2 is an explanatory diagram of signal processing of the oil deterioration detection device according to the first embodiment.

FIG. 3 is a sectional front view of the oil deterioration detection device according to the first embodiment.

FIG. 4 is an explanatory diagram of a shape of a cleaning member of the oil deterioration detection device according to the first embodiment.

FIG. 5 is a correlation diagram between the particle concentration and the reflectance of the apparatus for detecting the concentration of particles in a liquid according to the present invention.

FIG. 6 is an explanatory diagram of an evanescent wave.

FIG. 7 is an explanatory view of the principle of an optical system of the apparatus for detecting concentration of particles in liquid according to the present invention.

FIG. 8 is a sectional view of an oil deterioration detection device according to a second embodiment.

FIG. 9 is a sectional view of an oil deterioration detection device according to a third embodiment.

FIG. 10 is a cross-sectional view taken along the line AA of FIG.

FIG. 11 is a sectional view of an essential part of an optical system of an oil deterioration detection device according to a fourth embodiment.

FIG. 12 is a sectional view of an essential part of an optical system of an oil deterioration detection device according to a fifth embodiment.

FIG. 13 is an explanatory diagram of a conventional oil deterioration detection device.

[Explanation of symbols]

 10. . . 10. Liquid particle concentration detection device, . . Light emitting unit, 12. . . Light sensor, 13. . . Reference light sensor, 30. . . Receiving section, 31. . . Detection surface, 35. . . 7. cleaning member; . . Liquid to be tested, 80. . . Interface, 82. . . Inspection light, 83. . . reflected light,

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yurio Nomura 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (72) Inventor Rie Osaki 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Japan Denso Stock In-company (56) References JP-A-4-274741 (JP, A) JP-A-2-22540 (JP, A) JP-A-61-292044 (JP, A) JP-A-2-19745 (JP, A) JP-A-62-2138 (JP, A) JP-A-50-50978 (JP, A) JP-A 62-104145 (JP, U) JP-A 2-118853 (JP, U) JP-A 54-108 110176 (JP, U) JitsuHiraku Akira 53-108279 (JP, U) PCT National flat 6-506772 (JP, a) WO 92/19956 (WO, A1) (58 ) investigated the field (Int.Cl. ⁷ G01N 21/00-21/61 Practical file (PATOLIS) Patent file Le (PATOLIS)

Claims (10)

(57) [Claims] A light-emitting unit that emits inspection light that comes into contact with a liquid to be inspected and is totally reflected at a boundary surface thereof; an optical sensor that receives the total reflection light; and a reference optical sensor that directly receives the inspection light. A determination unit configured to determine a reflectance from an output signal of an optical sensor and calculate a particle concentration in the liquid based on the reflectance. 2. A liquid particle concentration detecting apparatus according to claim 1, wherein the liquid to be inspected is a lubricating oil of a diesel engine, and said judging section judges the deterioration of the lubricating oil further from the particle concentration. apparatus. 3. The liquid particle concentration detecting device according to claim 1 or 2, wherein the device for detecting the concentration of particles in liquid has a storage section for the liquid to be inspected having a detection surface in contact with the liquid to be inspected and on which the inspection light is incident. An apparatus for detecting a concentration of particles in a liquid, wherein a cleaning member for the detection surface, which floats due to a fluid motion of a liquid to be inspected, is mixed in the storage section. 4. A detecting surface according to claim 1, wherein a plurality of detecting surfaces which are in contact with the liquid to be inspected and totally reflect the inspection light at a boundary surface thereof are provided, and which are emitted from a light source of a light emitting section. An optical path is formed so that the inspection light is totally reflected on the plurality of detection surfaces and then reaches an optical sensor. 5. There you <br/> to any one of claims 1 to 4, the light emitting portion of the light source that emits inspection light, the optical path reaching the light sensor for receiving the totally reflected light is A plurality of mirrors and the like for changing the optical path of the inspection light are provided. The inspection light is changed in the optical path by a mirror and the like, and is applied to an optical sensor arranged on the same substrate at a distance not far from the light source. An apparatus for detecting the concentration of particles in a liquid, which is incident. 6. A device according to claim 5, wherein a main part of an optical path from the light source to the optical sensor is formed by a prism, and the mirror and the like are formed on an outer wall surface of the prism. Liquid particle concentration detector. 7. A part of an optical path from a light source to an optical sensor according to any one of claims 1 to 6, wherein only light incident at a predetermined angle is selectively provided. An apparatus for detecting the concentration of particles in a liquid, wherein an aperture through which the liquid passes is provided. 8. The method according to claim 6, wherein only the light incident at a predetermined angle is selectively applied to the light path on the light entrance side of the prism from the light source to the prism and the light path on the light exit side of the prism from the prism to the optical sensor. An apparatus for detecting the concentration of submerged particles, wherein an aperture through which the liquid is passed is provided. 9. Claim 1, Claim 2, Claim 4 to Claim 9.
8. In any one of the above 8 , the above-mentioned liquid particle concentration detecting device may comprise a projection inserted into a container or a conduit for accommodating a liquid to be inspected, and the projection inserted into the container or the conduit and fixed. An apparatus for detecting a concentration of a particle in a liquid, comprising: a fixing member; and the detection surface is formed on the protrusion. 10. The inspection device according to claim 9, wherein the projection is provided with an enclosing portion for a cleaning member which covers the detection surface and allows the inspection target liquid to freely pass therethrough. An apparatus for detecting the concentration of particles in a liquid, wherein a cleaning member floating by movement is accommodated.