JP2008145411A - Concentration detector for particles in liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concentration detector for a particle in a liquid, capable of restraining foreign matters in the liquid from depositing on a face, serving as an optical path for an inspection light, and capable of reducing the number using optical sensors. <P>SOLUTION: This concentration detector for the particle in the liquid uses one photodiode 5, and alternately switches an optical path, until the light emitted from a light-emitting diode 4 enters the photodiode 5 from a light guide part 31 to a path comprising only a lubricating oil and vice versa, by a rotor 3 rotated by receiving the flow of the lubricating oil. A concentration sensor 1 for the particle in the liquid capable of accurately detecting particle concentration is provided, in this manner by using one optical sensor. The foreign matters, deposited on surfaces of a window member 6 and a window member 7, are separated immediately to be removed by pressure pulsation, generated when the light guide part 31 of the rotor 3 is passed through the window member 6 and the window member 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical liquid particle concentration detecting device, and is suitable for use in detecting the particle concentration of carbon particles contained in, for example, automobile engine oil.

  As a conventional liquid particle concentration detection device, for example, light from a light source is irradiated onto a light guide that is in contact with the liquid, and light that travels while being totally reflected by the liquid contact surface in the light guide is received by a main light sensor. In addition, the light reflected by the reflecting surface of the light guide is received by the reference light sensor, and the reflectance at the liquid contact surface is calculated based on the outputs of both sensors, thereby calculating the concentration of particles in the liquid. Yes (see Patent Document 1).

Further, as another conventional particle concentration detector in liquid, two transmitted light quantity ratios respectively measured for two types of light path lengths with different optical path lengths transmitted through the liquid, and the above-described two types of optical path lengths. There is a configuration that detects the particle concentration in the liquid based on the ratio (see Patent Document 2).
JP-A-8-247933 JP 2004-340806 A

  In the liquid particle concentration detection apparatus described in Patent Document 1, there is a problem in that foreign matter contained in the liquid adheres to the liquid contact surface of the light guide as the usage time elapses, and the detection accuracy decreases.

  In addition, since the conventional liquid particle concentration detection device uses two optical sensors, the main light sensor and the reference light sensor, there is a risk that the number of parts of the liquid particle concentration detection device will increase, the physique will increase, and the cost will increase. is there.

  On the other hand, in the liquid particle concentration detection device described in Patent Document 2, two transmitted light quantity ratios respectively measured for light of two types of optical path lengths having different optical path lengths transmitted through the liquid, and the above-mentioned 2 Since the particle concentration in the liquid is detected based on the type of optical path length ratio, it is possible to eliminate the influence of foreign matter adhering to the liquid contact surface of the light guide on the particle particle concentration detection accuracy, but there are multiple light sources and optical sensors. Since it is necessary to have parts with liquid passages with complex shapes that require two different optical path lengths that pass through the liquid, the number of parts in the liquid particle concentration detector increases. There is a risk of increased physique and cost.

  The present invention has been made in view of the above-described problems, and its object is to suppress the adhesion of foreign substances in the liquid to the surface that becomes the optical path of the inspection light and to reduce the number of optical sensors to be used. An object of the present invention is to provide a liquid particle concentration detection device.

  In order to achieve the above object, the present invention employs the following technical means.

  According to a first aspect of the present invention, there is provided a liquid particle concentration detecting device comprising: a casing having a liquid passage; a light source fixed to the casing so as to be able to irradiate light into the liquid; and light from the light source traveling in the liquid. An optical sensor fixed to the casing so as to be able to receive light, and a rotor that is disposed in the passage and is supported so as to be rotatable around an axis by receiving a fluid force when the liquid flows. The rotor is disposed so as to face each other across the rotor in the direction, the rotor is formed of a translucent material having higher transmittance than the liquid with respect to the light emitted from the light source, and the rotor is opposed to the light source and the optical sensor and from the light source. The light guide unit is formed so that the light in the rotor travels through the rotor and is guided to the optical sensor, and when the liquid flows through the passage, the rotor rotates and the light guide unit and the liquid alternate between the light source and the optical sensor. Appearing It is characterized.

  In the above-described configuration, when the liquid flows through the passage and the rotor rotates by receiving the fluid force, there are two types of optical paths for the light emitted from the light source to reach the optical sensor: the light guide and the liquid. That is, when the light guide part of the rotor is provided between the light source and the optical sensor, the light from the light source enters the optical sensor via the inside of the rotor. On the other hand, when the light guide part of the rotor does not exist between the light source and the optical sensor and there is a liquid instead, the light from the light source enters the optical sensor via the liquid. Therefore, the output signals from the optical sensor are also two types according to these. Here, since the light transmittance of the rotor is higher than that of the liquid, the output signal level of the light sensor when the light guide part of the rotor is between the light source and the light sensor is between the light source and the light sensor. Higher than the output signal level of the optical sensor when only liquid is present. Further, in the process of using the liquid particle concentration detection apparatus, the light transmittance of the rotor hardly changes, but the light transmittance of the liquid changes according to the change in the particle concentration in the liquid. That is, in the process of using the liquid particle concentration detection device, the output signal of the optical sensor when the light guide part of the rotor is between the light source and the optical sensor is always at a constant level, whereas the light source and the optical sensor The output signal level of the light sensor when light from the light source enters the light sensor through the liquid is lower than when there is a light guide and the concentration of particles in the liquid changes. It changes in conjunction with. That is, in the liquid particle concentration detection apparatus according to the first aspect of the present invention, one optical sensor is used, and the optical path of the reference light and the inspection light are switched by the rotation of the rotor.

  In the liquid particle concentration detection device according to claim 1 of the present invention, when the liquid flows through the passage of the casing, the light emission window from the light source provided in the casing and the incident window to the optical sensor As the liquid flows along the surface, the light guide part of the rotor passes intermittently in the vicinity thereof. For this reason, the pressure on each surface of the exit window and the entrance window of the passage varies when passing through the light guide portion of the rotor. That is, pressure pulsations are generated on the surfaces of the exit window and the entrance window. Due to this pressure pulsation, even if foreign matter adheres to the surfaces of the exit window and the entrance window, they are immediately separated and carried away by the liquid. As a result, the surfaces of the exit window and the entrance window are always kept clean with no foreign matter attached thereto.

  As described above, it is possible to realize a liquid particle concentration detection apparatus that can suppress foreign substances in the liquid from adhering to the surface that becomes the optical path of the inspection light in the casing and can reduce the number of optical sensors to be used to one.

  In the liquid particle concentration detecting device according to claim 2 of the present invention, at least a portion where the light source faces the passage and a portion where the optical sensor faces the passage are formed of a translucent material. Thus, the light emitted from the light source can be reliably irradiated into the liquid passage and incident on the optical sensor. Further, if the entire casing is formed of a light-transmitting material, the number of parts and the number of assembling steps can be reduced as compared with the case where the light emission window from the light source and the incident window to the optical sensor are separate parts. .

  In the liquid particle concentration detection device according to claim 3 of the present invention, the size of the gap between the rotor and the casing in the axial direction of the rotor is set as small as possible within a range in which smooth rotation of the rotor can be maintained. It is said. According to such a configuration, when the light guide unit of the rotor is provided between the light source and the optical sensor, the ratio of the light guide unit in the optical path length between the light source and the optical sensor can be maximized. In other words, the ratio of the liquid in the optical path length between the light source and the optical sensor can be minimized. As a result, the output signal level of the optical sensor when receiving the reference light can be increased, and the influence of the change in the particle concentration in the liquid on the output signal level when receiving the reference light can be minimized. Accordingly, it is possible to stabilize the optical sensor output signal level when receiving the reference light in the process of using the liquid particle concentration detection device, and to maintain good particle particle concentration detection accuracy.

  According to a fourth aspect of the present invention, the rotor includes a contact piece made of an elastic member and in contact with the passage on at least one of both end faces of the light guide portion in the axial direction. . In such a configuration, when the rotor rotates due to the flow of the liquid, the contact piece slides on the surface of the passage including the surfaces of the exit window and the entrance window of the passage. As a result, even if foreign matter adheres to each surface of the exit window and the entrance window of the passage, it can be immediately wiped off by the sliding piece, so that each surface of the exit window and the entrance window can be always kept clean. it can.

  The liquid particle concentration detecting device according to claim 5 of the present invention is characterized in that the light source is a light emitting diode and the optical sensor is a photodiode or a phototransistor. Light-emitting diodes, photodiodes, and phototransistors are common elements, and have a wide variety of characteristics, shapes, etc. and are inexpensive, so that the concentration of particles can be detected accurately according to the liquid to be inspected and the type of particles contained. Simple elements can be set easily and inexpensively.

  According to a sixth aspect of the present invention, there is provided a liquid particle concentration detection apparatus, comprising: a casing having a liquid passage; a light source fixed to the casing so as to be able to emit light into the liquid; and light from the light source traveling in the liquid. An optical sensor fixed to the casing so as to be able to receive light, and a rotor that is disposed in the passage and is supported so as to be rotatable around an axis by receiving a fluid force when the liquid flows. The rotor is disposed so as to face each other across the rotor in the direction, the rotor is formed of a translucent material having a higher transmittance than the liquid with respect to the light emitted from the light source, and the rotor is opposed to the light source and the optical sensor from the light source. A first light guide part and a second light guide part, which are two kinds of light guide parts that guide light to the optical sensor by traveling in the rotor, and the light path length from the light source to the optical sensor in the first light guide part Is the first optical path length The second light guide unit is formed to be different from a second optical path length that is a path length of light traveling from the light source to the optical sensor, and when the liquid flows through the passage, the rotor rotates and the second optical path is formed between the light source and the optical sensor. 1 light guide part and 2nd light guide part appear alternately.

  In the above-described configuration, when the rotor is rotated by receiving the fluid force of the liquid flowing through the passage, the light path from the light source to the optical sensor includes the first light guide section and the optical path composed of the liquid section that follows the second light path. Two types of optical paths composed of a light guide portion and a subsequent liquid portion appear alternately. Here, the path length of light traveling from the light source to the optical sensor in the liquid section following the first light guide section is the third optical path length, and the path length of light traveling from the light source to the optical sensor in the liquid section following the second light guide section. When the length is expressed as the fourth optical path length, the optical path length from the light source to the optical sensor when the first light guide portion appears between the light source and the optical sensor is the first optical path length + the third optical path length. The optical path length from the light source to the optical sensor when the second light guide portion appears between the light source and the optical sensor is the second optical path length + the fourth optical path length. Since “first optical path length + third optical path length” and “second optical path length + fourth optical path length” are equal and the first optical path length and the second optical path length are different, for example, the first optical path length Assuming that the second optical path length is satisfied, from the relationship of (first optical path length + third optical path length) = (second optical path length + fourth optical path length), the third optical path length <the fourth optical path length.

  Here, the amount of light received by the optical sensor will be considered. The amount of light received when the first light guide portion appears between the light source and the light sensor is the first light amount received, and the amount of light received when the second light guide portion appears between the light source and the light sensor is the second light amount received. Expressed as a quantity. When light passes through the liquid, if the liquid contains particles, the light is absorbed or diffusely reflected by the particles and attenuates, so the amount of transmitted light decreases. In addition, the degree of attenuation of light when light passes through the liquid increases as the optical path length in the liquid becomes longer when the particle concentration is the same. On the other hand, the rotor is formed of a translucent material having a higher transmittance than the liquid with respect to the light emitted from the light source. For this reason, although the optical path length differs between the first light guide section and the second light guide section, the influence of both optical path length differences on the first received light amount and the second received light amount is very small and can be ignored. From the above, the first received light amount and the second received light amount are determined by the optical path length of the first liquid part and the optical path length of the second liquid part, that is, the third optical path length and the fourth optical path length.

  Next, a liquid particle concentration detection method using the liquid particle concentration detection device according to claim 6 of the present invention will be described.

  Assuming that the ratio of the third optical path length and the fourth optical path length is 1: n, the first received light amount, which is the transmitted light amount in the third optical path length, is the transmittance α (0 <α If <1), it can be expressed by the following formula (1).

First received light amount = light emission amount of light emitting portion × transmittance α (1)
The second received light amount, which is the transmitted light amount in the fourth optical path length, can be expressed by the following equation (2), where the transmittance of light in the liquid is the transmittance α (0 <α <1).

Second received light amount = amount of light emitted from the light emitting unit × (transmittance α) ⁿ (2)
Then, the following equation (3) is obtained from the above equations (1) and (2).

(Transmissivity α) ⁿ⁻¹ = second received light amount / first received light amount (3)
Then, Expression (4) is obtained from Expression (3).

Transmittance α = (second received light amount / first received light amount) ^{1 / n−1} (4)
As can be seen from the above equation (4), when the ratio of the third optical path length and the fourth optical path length is 1: n, the ratio of the respective optical path lengths and the ratio of the respective received light amounts measured at the respective optical path lengths are used. Thus, the liquid transmittance α can be obtained. As is well known, since the light transmittance in the liquid and the particle concentration in the liquid are in a correlation, the particle concentration can be obtained by obtaining the transmittance.

  As described above, if the value (transmittance) correlated with the particle concentration is obtained based on each received light amount, the influence of the change in the characteristics of the light emitting unit and the optical sensor on the detection accuracy of the particle concentration can be suppressed to a small level. The particle concentration can be detected with high accuracy.

  Further, according to the above-described method, in the case where the exit surface where the light from the light emitting unit is emitted into the liquid and the incident surface where the transmitted light in the liquid enters the optical sensor are contaminated due to adhesion of foreign matter or the like in the liquid However, since the influence of the dirt on the amount of transmitted light can be offset, the particle concentration can be detected with high accuracy.

  In the liquid particle concentration detection apparatus according to claim 6 of the present invention described above, the two types of optical path lengths in the liquid are switched by rotating the rotor. Thereby, the number of light emission parts and optical sensors can be made into one set. That is, two different signals can be detected using one light source and one optical sensor. Therefore, it is possible to reduce the number of light emitting units and optical sensors used in the liquid particle concentration detection device.

  In the liquid particle concentration detection device according to claim 6 of the present invention described above, the light emission window from the light source provided in the casing is rotated when the rotor is rotated by the fluid force of the liquid flowing in the passage. And the light guide part of a rotor passes intermittently at least one surface vicinity of the entrance window to an optical sensor. For this reason, the pressure on each surface of the exit window and the entrance window provided in the casing varies, and thereby at least one surface of the exit window and the entrance window can be kept clean.

  In the liquid particle concentration detection apparatus according to claim 7 of the present invention, the rotor includes a contact piece made of an elastic member and in contact with the passage on at least one of both end faces of the light guide portion in the axial direction. . In such a configuration, when the rotor rotates due to the flow of the liquid, the contact piece slides on the surface of the passage including the surfaces of the exit window and the entrance window of the passage. As a result, even if foreign matter adheres to each surface of the exit window and the entrance window of the passage, it can be immediately wiped off by the sliding piece, so that each surface of the exit window and the entrance window can be always kept clean. it can.

  According to an eighth aspect of the present invention, there is provided the particle concentration detecting device in a liquid, wherein the light source is a light emitting diode and the light sensor is a photodiode or a phototransistor. Light-emitting diodes, photodiodes, and phototransistors are common elements, and have a wide variety of characteristics, shapes, etc. and are inexpensive, so that the concentration of particles can be detected accurately according to the liquid to be inspected and the type of particles contained. Simple elements can be set easily and inexpensively.

  A liquid particle concentration detection method according to claim 9 of the present invention is a liquid particle concentration detection method using the liquid particle concentration detection device according to any one of claims 6 to 8. When the first light guide portion appears in the optical path of the light from the light source to the optical sensor, the first received light amount that is detected by the optical sensor and the second in the optical path of the light from the light source to the optical sensor. The ratio of the received light amount that is the amount of received light detected by the optical sensor when the light guide portion appears, and the liquid when the first light guide portion appears in the optical path of light from the light source toward the optical sensor. It is obtained from the ratio of the third optical path length, which is the optical path length, and the fourth optical path length, which is the optical path length in the liquid when the second light guide portion appears in the optical path of the light from the light source toward the optical sensor. Detecting the concentration of liquid particles based on the liquid permeability There.

  According to the above-described liquid particle concentration detection method, as shown in the equation (4) in the description of the liquid particle concentration detection device according to claim 6, the liquid transmittance α And the received light amount ratio measured through each optical path length. As a result, even if foreign matter or the like adheres to the light emitting surface of light into the liquid and the light receiving surface of light transmitted through the liquid and the transmittance varies, the influence is eliminated. It can be detected with high accuracy. As is well known, the light transmittance in the liquid and the particle concentration in the liquid have a correlation, so that the particle concentration can be obtained with high accuracy by obtaining the transmittance.

  Hereinafter, the case where the liquid particle concentration detecting device according to the present invention is applied to a particle concentration sensor 1 in a lubricating oil used in an oil deterioration detecting system for determining the degree of deterioration of lubricating oil in an automobile engine will be described with reference to the drawings. This will be explained based on.

  In the process of using an automobile, carbon such as combustion gas and particles such as abrasion powder from each moving part 104 are mixed in the lubricating oil of the engine, and the function as the lubricating oil gradually deteriorates. The oil deterioration detection system detects the particle concentration in the lubricating oil by the particle concentration sensor 1 in the lubricating oil, and calculates the deterioration degree of the lubricating oil based on the detected particle concentration. Further, when the degree of deterioration of the lubricating oil exceeds a predetermined value, an alarm is issued by some means, thereby prompting the driver to replace the lubricating oil.

(First embodiment)
The lubricating oil particle concentration sensor 1 according to the first embodiment of the present invention is disposed in the middle of a lubricating oil circulation path in an automobile engine. As shown in FIG. 3, the engine lubricating oil circulation path includes an oil pan 101, an oil pump 102, an oil filter 103, and engine moving parts 104. The lubricating oil in the oil pan 101 is pressure-fed to the oil filter 103 by the oil pump 102 and passes through the oil filter 103 to remove foreign matters and the like, so that each moving part 104 of the engine (for example, a bearing of a crankshaft or a camshaft) , Piston / cylinder sliding portion, gear train meshing portion, etc.). Lubricating oil flowing out from each moving part 104 is collected in the oil pan 101 and pumped again. As shown in FIG. 1, the lubricating oil particle concentration sensor 1 is mounted in the middle of the lubricating oil path on the downstream side of the oil filter 103. Below, the structure of the particle concentration sensor 1 in lubricating oil by 1st Embodiment of this invention is demonstrated.

  The particle concentration sensor 1 in lubricating oil is a casing 2 having a passage 21 for lubricating oil that is a liquid, a rotor 3 that is rotatably accommodated in the passage 21 of the casing 2, a light emitting diode 4 that is a light source, and an optical sensor. It is composed of a photodiode 5.

  The casing 2 is formed from a resin material. As the resin material, a material excellent in heat resistance and oil resistance and having ordinary light shielding properties is used. As shown in FIG. 1, a passage 21 through which lubricating oil that is a liquid flows is formed in the casing 2. As shown in FIG. 1, an inlet 21 a and an outlet 21 b are formed at both ends of the passage 21. As shown in FIG. 1, a lubricating oil pipe 11 forming an engine lubricating oil circuit is connected to the inlet portion 21a and the outlet portion 21b. The lubricating oil pumped by the oil pump 102 flows into the passage 21 of the lubricating oil particle concentration sensor 1 from the inlet portion 21a, flows in the passage 21 in the direction of the arrow in FIG. It flows out toward the moving part 104. As the resin material forming the casing 2, a material excellent in lubricating oil resistance and heat resistance is used. The casing 2 has a window hole 22 for emitting light from the light emitting diode 4 as a light source, which will be described later, into the passage 21, a window hole 23 for allowing light to enter the photodiode 5, which is an optical sensor, and a rotor which will be described later. A shaft hole 24 for fixing the shaft 8 that rotatably supports the shaft 3 is provided. The window hole 22 and the window hole 23 are arrange | positioned so that it may mutually oppose, as shown in FIG. In other words, the window hole 22 and the window hole 23 are arranged coaxially with each other, and the axial direction of both the windows 22 and 23 is orthogonal to the flow direction of the lubricating oil.

  In the window hole 22 of the casing 2, a light emitting diode 4 as a light source is disposed so as to be able to irradiate the lubricating oil in the passage 21. That is, the light emitting diode 4 is arranged with its optical axis (direction in which the light emission luminance is maximum) parallel to the window hole 22. On the other hand, a photodiode 5, which is an optical sensor, is disposed in the window hole 23 of the casing 2 so as to receive light from the light emitting diode 4. That is, the photodiode 5 is arranged so that the direction in which the light detection sensitivity is maximum coincides with the optical axis of the light emitting diode 4. Further, the window member 6 is fitted and fixed to the window hole 22 and the window member 7 is fixed to the window hole 23 as shown in FIG. The window member 6 and the window member 7 are made of a light-transmitting material having a high transmittance, such as a colorless transparent resin or glass, so that light loss in the window members 6 and 7 is minimized. The window member 6 and the window member 7 are firmly and airtightly fixed to the window holes 22 and 23 by adhesion or the like, and the lubricating oil is prevented from leaking around the light emitting diode 4 and the photodiode 5 through the window holes 22 and 23. is doing. The light emitting surface of the light emitting diode 4 and the window member 6 and the light receiving surface of the photodiode 5 and the window member 7 are in close contact with each other as shown in FIG. That is, it is fixed so that there is no air layer between them. This eliminates the loss of transmitted light quantity when there is an air layer between them. The light emitting diode 4 and the photodiode 5 are respectively provided with leads 41 and 51 as electrodes, and each lead is connected to a terminal 9 as shown in FIG. It is connected to an electric circuit outside the sensor 1. As shown in FIG. 1, a sealing member 10 is filled between each terminal 9 and the casing 2. As the sealing member 10, for example, an epoxy resin or the like is used, and the light emitting diode 4 and the photodiode 5 are hermetically accommodated in the casing 21 by the sealing member 10.

  As shown in FIGS. 1 and 2, the rotor 3 is rotatably supported in the casing 2, that is, in the passage 21. The rotor 3 is made of a translucent material such as a colorless and transparent polycarbonate resin or glass. The rotor 3 is made of a material whose transmittance is higher than that of engine lubricating oil. Specifically, a material having a higher transmittance than that of a lubricating oil normally used in an engine to which the lubricant concentration sensor 1 is attached is used.

  The rotor 3 is rotatably supported by the shaft 8. The rotor 3 is provided with a bearing hole 32 that engages with the shaft 8. As shown in FIG. 1, the bearing hole 32 is formed as a conical recess. The shaft 8 is formed of a resin material or a metal material and is press-fitted and fixed in the shaft hole 24 of the casing 2. As shown in FIG. 1, the end portion of the shaft 8 on the rotor 3 side is formed in a conical shape and is engaged with a bearing hole 32 of the rotor 3. The central angle of the cone of the shaft 8 is formed smaller than the central angle of the bearing hole 32 of the rotor 3, and the tip of the shaft 8 is in light contact with the bottom of the bearing hole 32 of the rotor 3. Thereby, the contact area of the rotor 3 and the shaft 8 can be made very small, and the rolling resistance produced between both can be made very small. A shaft 8 that is a rotation axis of the rotor 3 is arranged in parallel to the facing direction of the light emitting diode 4 and the photodiode 5. In other words, the shaft 8, which is the rotation axis of the rotor 3, is arranged in parallel with the optical axis of light traveling from the light emitting diode 4 to the photodiode 5. Further, the gap between the rotor 3 and the casing 2 in the axial direction of the rotor 3 is set to be as small as possible within a range in which the smooth rotation of the rotor 3 can be maintained.

  The rotor 3 includes a light guide portion 31 extending radially in the radial direction. In the case of the lubricating oil particle concentration sensor 1 according to the first embodiment of the present invention, three light guides 31 are provided at intervals of 120 degrees as shown in FIG. As shown in FIG. 2, the rotation range A of the rotor 3, that is, the inner region of the trajectory at the radial tip of the light guide portion 31 includes a window hole 22 and a window hole 23. For this reason, when the rotor 3 rotates, the light guide 31 may face the window hole 22 and the window hole 23 simultaneously in the axial direction of the rotor 3.

  The rotation axis C of the rotor 3 is arranged offset from the flow path center R of the passage 21 as shown in FIG. In other words, the rotor 3 is arranged such that a part thereof faces the passage 21 in the radial direction. Therefore, when lubricating oil flows through the passage 21 and the fluid force acts on the rotor 3, that is, the light guide portion 31 in the passage 21, a clockwise rotational moment is generated in the rotor 3. Thereby, the rotor 3 rotates clockwise by the lubricating oil flowing.

  Next, the operation of the lubricating oil particle concentration sensor 1 configured as described above, that is, the particle concentration detecting operation in the lubricating oil will be described.

  During the operation of the automobile, that is, during the operation of the engine, the lubricating oil flows through the passage 21 of the particle concentration sensor 1 in the lubricating oil, whereby the rotor 3 rotates. When the rotor 3 is rotating, the light guide portion 31 of the rotor 3 appears intermittently in the space between the light emitting diode 4 and the photodiode 5 in the passage 21. When the light guide portion 31 passes, the space between the light emitting diode 4 and the photodiode 5 is filled only with lubricating oil. That is, in the space between the light emitting diode 4 and the photodiode 5, the light guide portions 31 and the lubricating oil appear alternately. In other words, the light path until the light emitted from the light emitting diode 4 enters the photodiode 5 is switched alternately between the light guide portion 31 and the lubricating oil.

  Further, during the operation of the automobile, the light emitting diode 4 of the particle concentration sensor 1 in the lubricating oil is driven to be lit by a predetermined current, and the photodiode 5 is also in an operating state.

  When the light path from which the light emitted from the light emitting diode 4 enters the photodiode 5 is lubricating oil, the output voltage of the photodiode 5 is the transmittance of the light guide portion 31 in FIG. Since it is higher than the transmittance at, the time when the lubricating oil is new and the time when the lubricating oil is used are alternately switched.

  The photo diode 5 generates an output voltage corresponding to the amount of light from the light emitting diode 4 incident thereon. That is, the output voltage is high when the amount of light is large, and the output voltage is low when the amount of light is small. In the lubricant concentration sensor 1 according to the first embodiment of the present invention, the transmittance of the rotor 3 is set higher than the transmittance of the lubricant when it is new. For this reason, the amount of light from the light emitting diode 4 incident on the photodiode 5 is large when the light path from the light emitting diode 4 until the light emitted from the light emitting diode 4 enters the photodiode 5 is the light guide 31, and the lubricating oil When it is, it becomes less. That is, the output voltage of the photodiode 5 is high when the light path from which the light emitted from the light emitting diode 4 enters the photodiode 5 is the light guide portion 31, and is low when it is the lubricating oil.

  Here, the output voltage of the photodiode 5 will be described with reference to FIG. FIG. 4 is a graph showing the relationship between the output voltage E (vertical axis) of the photodiode 5 and time T (horizontal axis). The output voltage E of the photodiode 5 when the light path until the light emitted from the light emitting diode 4 enters the photodiode 5 is the lubricating oil, that is, the inspection voltage Ed, is when the lubricating oil is new, that is, in the lubricating oil. Highest when particle concentration is lowest. The inspection voltage Ed at this time is Ed1 in FIG. As the engine operation time elapses and carbon particles, wear powder, etc. are mixed in the lubricating oil and the particle concentration in the lubricating oil increases, the amount of light from the light emitting diode 4 incident on the photodiode 5 decreases. The inspection voltage Ed also decreases from Ed1 to Ed2, as shown in FIG. On the other hand, the output voltage E of the photodiode 5, that is, the reference voltage Ec when the light path from the light emitting diode 4 until the light enters the photodiode 5 is the light guide portion 31 of the rotor 3, is the engine operating time. Almost no change even after elapse. Therefore, during operation of the automobile, the lubricant particle concentration sensor 1 outputs the reference voltage Ec and the inspection voltage Ed, which are two types of output voltages. By comparing the reference voltage Ec and the inspection voltage Ed for these two signals, the particle concentration in the lubricating oil can be detected with high accuracy.

  If the engine operating time further elapses and the particle concentration in the lubricating oil reaches the use limit of the lubricating oil, that is, the output voltage E of the photodiode 5 decreases to the inspection voltage Ed3 in FIG. The control circuit (not shown) detects this, determines that it is time to replace the lubricating oil, and executes an alarm operation (not shown, warning lamp lighting, warning sound blowing, etc.) provided in the oil deterioration detection system. Call attention to car drivers.

  In the lubricating oil particle concentration sensor 1 according to the first embodiment of the present invention, one photodiode 5 is used, and an optical path from the light emitted from the light emitting diode 4 to the photodiode 5 is changed to that of the lubricating oil. The light guide 31 and only the lubricating oil are alternately switched by the rotor 3 that rotates in response to the flow. Thereby, the particle concentration sensor 1 in the lubricating oil that can detect the particle concentration with high accuracy while reducing the number of the two light sensors for receiving the reference light and the inspection light in the conventional liquid particle concentration detecting device to one. Can be realized.

  Further, in the lubricating oil particle concentration sensor 1 according to the first embodiment of the present invention, when the rotor 3 rotates in the casing 2, the light guide portion 31 of the rotor 3 is a window from which the light emitting diode 4 emits light. It passes near the surface of each of the member 6 and the window member 7 that is a light incident portion to the photodiode 5. Since the gap between the rotor 3 and the casing 2 in the axial direction of the rotor 3 is set to a minimum as long as the smooth rotation of the rotor 3 can be maintained, the light guide portion 31, the window member 6, and the window member 7 The gap between is also smaller. For this reason, the pressure on the surfaces of the window member 6 and the window member 7 varies when the light guide part 31 of the rotor 3 passes. That is, pressure pulsation is generated on the surfaces of the window member 6 and the window member 7. Due to this pressure pulsation, even if foreign matter adheres to the surfaces of the window member 6 and the window member 7, it is immediately peeled off and carried away by the lubricating oil. As a result, the surfaces of the window member 6 and the window member 7 are always kept clean without foreign matter or the like adhering thereto. Therefore, the particle concentration detection accuracy of the lubricating oil particle concentration sensor 1 can be maintained satisfactorily.

(Second Embodiment)
FIG. 5 shows a cross-sectional view of the lubricating oil particle concentration sensor 1 according to the second embodiment of the present invention.

  The lubricating oil particle concentration sensor 1 according to the second embodiment of the present invention is different in the configuration of the rotor 3 from the lubricating oil particle concentration sensor 1 according to the first embodiment of the present invention. That is, the wiper 12 as a contact piece is attached to the light guide portion 31 of the rotor 3 as shown in FIG. The wiper 12 is formed from a soft rubber material or a resin material which is an elastic member. As shown in FIG. 6, the wiper 12 is attached to the rear side in the rotation direction of the rotor 3 of the light guide 31 so as to protrude toward the window member 6 side and the window member 7 side of the casing 2. The degree of protrusion of the wiper 12 is set so that the wall surface of the passage 21 of the casing 2, the window member 6 and the window member 7 are always in light contact. The radial length of the rotor 3 of the wiper 12 is set to the shortest length that can reliably wipe the entire surface of the window member 6 and the window member 7 while the rotor 3 is rotating. Thereby, during rotation of the rotor 3, the surfaces of the window member 6 and the window member 7 are always wiped by the wiper 12 and kept in a clean state in which foreign matter or the like does not stay. Therefore, the particle concentration detection accuracy of the lubricating oil particle concentration sensor 1 can be maintained satisfactorily.

  By the way, the frictional force with respect to the rotation of the rotor 3 is increased by always bringing the wiper 12 into contact with the inner wall surface of the passage 21. However, by setting the length of the wiper 12 to the shortest length that can reliably wipe the entire surface of the window member 6 and the window member 7, and by selecting the material and shape so as to make the contact pressure as small as possible, An increase in frictional force with respect to rotation can be minimized.

  In the lubricating oil particle concentration sensor 1 according to the second embodiment of the present invention, the wiper 12 is attached to only one of the three light guides 31 included in the rotor 3. The wiper 12 may be attached to the light unit 31 or all the light guide units 31.

(Third embodiment)
FIG. 7 shows a sectional view of a particle concentration sensor 1 in a lubricating oil according to a third embodiment of the present invention.

  The lubricating oil particle concentration sensor 1 according to the third embodiment of the present invention is different in the shape of the rotor 3 from the lubricating oil particle concentration sensor 1 according to the first embodiment of the present invention. The configuration other than the shape of the rotor 3 is the same as that in the lubricant particle concentration sensor 1 according to the first embodiment of the present invention. The configuration of the lubricating oil particle concentration sensor 1 according to the third embodiment of the present invention, in particular, the configuration of the rotor 3 and the operation thereof will be described below.

  The rotor 3 is formed in a substantially rectangular plate shape from a translucent material such as a colorless and transparent polycarbonate resin or glass. In other words, the rotor 3 has a propeller-like shape having two blades with its rotating shaft interposed therebetween. As shown in FIG. 7, the first light guide 33 is provided on one of the two blades, and the second light guide 34 is provided on the other blade. In the rotor 3 according to the third embodiment of the present invention, L1> L2 is set as shown in FIG. As shown in FIG. 7, the optical path length of light from the light emitting diode 4 to the photodiode 5 in the first light guide 33 is the first optical path length L1, and from the light emitting diode 4 to the photodiode 5 in the second light guide 34. The optical path length of the light which goes is 2nd optical path length L2, as shown in FIG. Therefore, the optical path length in the lubricating oil when the first light guide portion 33 is in the optical path of the light from the light emitting diode 4 to the photodiode 5 is the third optical path length L3, the second optical path length, as shown in FIG. As shown in FIG. 7, the optical path length in the lubricating oil when the optical unit 34 is in the optical path of light from the light emitting diode 4 to the photodiode 5 is the fourth optical path length L4, and L3 <L4. Yes.

  When the lubricating oil flows through the passage 21 during the operation of the engine, the rotor 3 rotates clockwise as shown in FIG. Then, the optical path of light from the light emitting diode 4 to the photodiode 5 is the length in the lubricating oil in the optical path of light from the light emitting diode 4 to the photodiode 5 when the first light guide portion 33 of the rotor 3 is present. Is the third optical path length L3, in other words, when the optical path length in the lubricating oil is the shortest, and all the optical paths of light from the light emitting diode 4 to the photodiode 5 are in the lubricating oil, in other words, in the lubricating oil When the second light guide 34 of the rotor 3 is present, that is, the length in the lubricating oil in the light path from the light emitting diode 4 toward the photodiode 5 is the fourth optical path length L4. In other words, in other words, three types of states when the optical path length in the lubricating oil is the intermediate length between the two appear repeatedly in the order described above. In this case, the output voltage E of the photodiode 5 changes as shown in FIG. That is, among the output voltages E in FIG. 9, the output voltage E <b> 1 passes through the first light guide 33 of the rotor 3, and the output voltage E <b> 2 passes through the second light guide 34 of the rotor 3. E3 is the case where there is no rotor 3, that is, 100% lubricating oil. Therefore, when the rotor 3 rotates, the output voltage E of the photodiode 5 repeatedly fluctuates in the order of E1, E3, E2, and E3 as shown in FIG.

  Next, a method for detecting particle concentration in lubricating oil using the particle concentration sensor 1 in lubricating oil according to the third embodiment of the present invention will be described.

  When the ratio of the third optical path length L3 and the fourth optical path length L4, that is, L3: L4 is expressed as 1: n, the first received light amount that is the transmitted light amount after passing through the third optical path length L3 is the transmission of light in the lubricating oil. If the rate is transmittance α (0 <α <1), it can be expressed by the following equation (1).

First received light amount = light emission amount of light emitting portion × transmittance α (1)
The second received light amount, which is the transmitted light amount in the fourth optical path length, can be expressed by the following equation (2), where the transmittance of light in the lubricating oil is the transmittance α (0 <α <1).

Second received light amount = amount of light emitted from the light emitting unit × (transmittance α) ⁿ (2)
Then, the following equation (3) is obtained from the above equations (1) and (2).

(Transmissivity α) ⁿ⁻¹ = second received light amount / first received light amount (3)
Then, Expression (4) is obtained from Expression (3).

Transmittance α = (second received light amount / first received light amount) ^{1 / n−1} (4)
Here, the following expression (5) is obtained by substituting the output voltage E1 of the photodiode 5 that is the first received light amount and the output voltage E2 of the photodiode 5 that is the second received light amount into the expression (4).

Transmittance α = (E2 / E1) ^{1 / n−1} (5)
As can be seen from the above equation (5), the ratio of the third optical path length and the fourth optical path length is replaced with 1: n, and the ratio of the output voltages E1 and E2 as the respective received light amounts measured by the photodiode 5 is used. Thus, the permeability α of the lubricating oil can be obtained. Based on this transmittance α, the particle concentration in the lubricating oil having a correlation with the transmittance α can be obtained.

  Thus, according to the method for detecting the concentration of particles in the lubricating oil using the particle concentration sensor 1 in the lubricating oil according to the third embodiment of the present invention, the ratio between the third optical path length and the fourth optical path length, and the photodiode 5 By obtaining the particle concentration in the lubricating oil based on the ratio of the output voltages E1 and E2, foreign matters in the lubricating oil adhere to the surface of the window member 6 that is the exit surface and the surface of the window member 7 that is the incident surface. Even if the transmittance of the window member 6 and the window member 7 changes, the influence of the dirt on the transmitted light amount can be offset, so that the particle concentration can be detected with high accuracy. Further, even if the characteristics of the light emitting diode 4 and the photodiode 5 change, the influence on the transmitted light amount due to the change in these characteristics can be offset, so that the particle concentration can be detected with high accuracy.

  In the lubricating oil particle concentration sensor 1 according to the third embodiment of the present invention, the two kinds of optical path lengths in the lubricating oil are switched by rotating the rotor 3. Thus, the particle concentration in the lubricating oil can be detected by using one each of the light emitting diode 4 and the photodiode 5. Therefore, it is possible to reduce the number of light emitting units and optical sensors used in the liquid particle concentration detection device.

  Furthermore, in the particle concentration sensor 1 in the lubricating oil according to the third embodiment of the present invention, when the rotor 3 is rotated by the fluid force of the lubricating oil flowing in the passage 21, the vicinity of the surface of the window member 7 provided in the casing 2 is observed. The rotor 3 passes intermittently. For this reason, the pressure on the window member 7 surface fluctuates, whereby the surface of the window member 7 can be kept clean.

  In the lubricating oil particle concentration sensor 1 according to the first and second embodiments of the present invention described above, the number of the light guide portions 31 of the rotor 3 is three, but it is necessary to limit the number to three. However, any number of rotors 3 may be provided as long as the rotor 3 can rotate smoothly.

  In the lubricating oil particle concentration sensor 1 according to the first to third embodiments of the present invention described above, the casing 2 is formed of a resin material having a light shielding property, and the light path from the light emitting diode 4 Although the transparent window members 6 and 7 are fixed to the casing 2 in the window holes 22 and 23, the entire casing 2 may be formed of a transparent material.

  Further, as the light emitting diode 4, it is desirable to use a light emitting diode whose peak wavelength is such that it can be transmitted to some extent even in lubricating oil having a high particle concentration. Here, “permeable to some extent” means that the photodiode 5 can reliably output the inspection voltage Ed3 in FIG.

  In each of the embodiments of the liquid particle concentration detection device according to the present invention described above, the case where the liquid particle concentration detection device is applied to the lubricating oil particle concentration sensor 1 mounted on an automobile will be described as an example. However, it is not necessary to limit the use of the particle concentration detector in the liquid to the particle concentration sensor 1 in the lubricating oil, and use for detecting the concentration of particles contained in other liquids other than the lubricating oil, such as fuel or hydraulic fluid for automatic transmissions. You may apply to. Furthermore, the use need not be limited to automobiles, and may be applied to other uses such as various consumer devices. For example, the present invention may be applied to detecting the concentration of particles in the fuel of a combustion heating apparatus.

It is sectional drawing of the particle concentration sensor 1 in lubricating oil by 1st Embodiment of this invention, and is the II sectional view taken on the line in FIG. It is the II-II sectional view taken on the line in FIG. It is a schematic diagram explaining a lubricating oil circuit of an engine equipped with the particle concentration sensor 1 in lubricating oil according to the first embodiment of the present invention. 3 is a graph showing the relationship between the output voltage E (vertical axis) and the time T (horizontal axis) of the photodiode 5; It is sectional drawing of the particle concentration sensor 1 in lubricating oil by 2nd Embodiment of this invention, and is equivalent to FIG. FIG. 6 is a view taken in the direction of arrow VI in FIG. 5. It is sectional drawing of the particle concentration sensor 1 in lubricating oil by 3rd Embodiment of this invention, and is the VII-VII sectional view taken on the line in FIG. It is the VIII-VIII sectional view taken on the line in FIG. 3 is a graph showing the relationship between the output voltage E (vertical axis) and the time T (horizontal axis) of the photodiode 5;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid particle concentration detection apparatus 2 Casing 21 Passage 21a Inlet part 21b Outlet part 22 Window hole 23 Window hole 24 Shaft hole 3 Rotor 31 Light guide part 32 Bearing hole 33 1st light guide part 34 2nd light guide part 4 Light emitting diode (light source)
41 Lead 5 Photodiode (Optical sensor)
51 Lead 6 Window member 7 Window member 8 Shaft 9 Terminal 10 Sealing member 11 Lubricating oil pipe 12 Wiper (contact piece)
A Rotation range C Rotational axis E Output voltage Ec Reference voltage Ed, Ed1, Ed2, Ed3 Inspection voltage L1 First optical path length L2 Second optical path length L3 Third optical path length L4 Fourth optical path length R Channel center

Claims (9)

A casing with a passage for liquid;
A light source fixed to the casing so as to be able to irradiate light into the liquid;
An optical sensor fixed to the casing so as to be able to receive light from the light source traveling in the liquid;
A rotor that is disposed in the passage and that is supported so as to be rotatable around an axis by receiving fluid force when the liquid flows;
The light source and the optical sensor are arranged to face each other across the rotor in the axial direction of the rotor,
The rotor is formed of a translucent material having a higher transmittance than the liquid with respect to light emitted from the light source,
The rotor includes a light guide portion that is opposed to the light source and the light sensor and is formed to guide light from the light source to the light sensor by traveling through the rotor.
When the liquid flows through the passage, the rotor rotates, and the light guide and the liquid alternately appear between the light source and the optical sensor.   The in-liquid particle concentration detecting device according to claim 1, wherein at least a portion of the casing facing the light path and a portion of the optical sensor facing the passage are formed of a translucent material.   The size of the gap between the rotor and the casing in the axial direction of the rotor is set as small as possible within a range in which smooth rotation of the rotor can be maintained. The in-liquid particle concentration detection apparatus of description.   The said rotor is provided with the contact piece which consists of an elastic member in at least one of the both end surfaces of the said light guide part in the axial direction, and contacts the said channel | path. In-liquid particle concentration detector.   The liquid particle concentration detection device according to any one of claims 1 to 4, wherein the light source is a light emitting diode and the photosensor is a photodiode or a phototransistor. A casing with a passage for liquid;
A light source fixed to the casing so as to be able to irradiate light into the liquid;
An optical sensor fixed to the casing so as to be able to receive light from the light source traveling in the liquid;
A rotor that is disposed in the passage and that is supported so as to be rotatable around an axis by receiving fluid force when the liquid flows;
The light source and the optical sensor are arranged to face each other across the rotor in the axial direction of the rotor,
The rotor is formed of a translucent material having a higher transmittance than the liquid with respect to light emitted from the light source,
The rotor includes a first light guide portion and a second light guide portion which are two types of light guide portions that face the light source and the optical sensor and guide light from the light source to the optical sensor by traveling in the rotor. Prepared,
A first optical path length which is a path length of light from the light source toward the optical sensor in the first light guide section; and a path length of light which travels from the light source to the optical sensor in the second light guide section. Formed different from the second optical path length,
When the liquid flows through the passage, the rotor rotates and the first light guide part and the second light guide part appear alternately between the light source and the optical sensor. Detection device.   The liquid particle concentration detection device according to claim 6, wherein the rotor includes a contact piece made of an elastic member and in contact with the passage on at least one of both end faces of the light guide portion in the axial direction thereof.   8. The liquid particle concentration detecting device according to claim 6, wherein the light source is a light emitting diode and the optical sensor is a photodiode or a phototransistor. A liquid particle concentration detection method using the liquid particle concentration detection device according to any one of claims 6 to 8,
When the first light guide portion appears in the optical path of light from the light source toward the optical sensor, the first received light amount that is detected by the optical sensor and the light from the light source toward the optical sensor. When the second light guide portion appears in the optical path, the ratio to the second received light amount that is the received light amount detected by the optical sensor, and the optical path of the light from the light source toward the optical sensor. In the liquid when the second light guide part appears in the third optical path length, which is the optical path length in the liquid when the one light guide part appears, and in the optical path of the light from the light source toward the optical sensor A liquid particle concentration detection method, comprising: detecting a particle concentration of the liquid based on a transmittance of the liquid obtained from a ratio with a fourth optical path length which is an optical path length of the liquid.

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