JP4752791B2 - Liquid property detection method - Google Patents

Description

  The present invention relates to a liquid property detection method for detecting the property of the liquid based on the transmitted light quantity of the liquid.

As a conventional liquid property detection method, for example, the particle concentration in a liquid such as soot mixed in engine lubricating oil is determined based on the light transmission characteristics of the liquid, specifically, the amount of transmitted light that can be transmitted through the liquid. The gist is to measure the amount of transmitted light for light with different optical path lengths in the liquid and detect the particle concentration of the liquid based on the difference in the measured amount of transmitted light. Is known (see Patent Document 1). According to this particle concentration detection method, the particle concentration can be accurately detected by suppressing adverse effects due to changes in the characteristics of the light emitting unit and the light receiving unit or contamination attached to the light emitting surface of the light emitting unit and the light receiving surface of the light receiving unit. can do.
JP 2004-340806 A

  According to the conventional particle concentration detection method, when the amount of foreign matter or dirt attached to the wall of the passage of the liquid to be measured is relatively small in the light path from the light emitting portion to the light receiving portion, the particles are accurately obtained. The concentration can be detected. However, when the amount of foreign matter or dirt adhered exceeds a certain limit, the amount of light absorbed by the foreign matter or dirt when passing through the foreign matter or dirt increases, and is used for measuring the amount of light that passes through the liquid, that is, particle concentration. The amount of light decreases, making it difficult to detect the particle concentration with good accuracy.

  Furthermore, in the conventional particle concentration detection method, there is no way to detect the amount of foreign matter or dirt adhering to the wall surface of the liquid to be measured. In consideration of this, the particle concentration is determined. Therefore, accurate particle concentration detection cannot be continuously executed.

  The present invention has been made in view of the above problems, and its purpose is to improve the detection method even when the amount of foreign matter or dirt attached to the wall surface of the passage of the liquid to be measured increases. It is an object to provide a liquid property detection device capable of detecting a liquid property with high accuracy.

  Means for achieving the above object and its operation and effects will be described below.

  In the liquid property detection method according to the first aspect of the present invention, the light is emitted from the light emitting unit to the liquid, and the amount of transmitted light transmitted through the liquid is detected by the light receiving unit, and based on the detected transmitted light amount. In a liquid property detection method for detecting a property of a liquid, a first received light amount and a second received light amount, which are received light amounts of light passing through the liquid and passing through the first optical path and the second optical path having different optical path lengths, are obtained. And measuring a third received light amount that is the amount of light received through the third optical path from the light emitting unit directly to the light receiving unit without passing through the liquid, and the ratio of the first received light amount and the second received light amount Based on the ratio of the length of the liquid portion in the first optical path and the length of the liquid portion in the second optical path, the first transmittance, which is the transmittance of the liquid, is calculated, and the third received light amount and the calculated first transmission are calculated. Of the light emitting surface and the light receiving unit Calculating a second the transmittance of foreign material layer adhering to the optical surface, it is characterized by determining the nature of the liquid based on the first transmission and the second transmission.

  The concept of liquid property determination by the detection method having the above configuration will be described.

  According to the above configuration, the length of the liquid portion in the optical path is different between the first optical path and the second optical path. Therefore, the length of the liquid portion is different between the first received light amount and the second received light amount. The amount of light received by the light reaching the light receiving unit via the optical path is measured. Here, the amount of received light that is measured decreases as the liquid property, for example, the particle concentration increases, but the amount of received light that is measured with a liquid partial optical path length that is longer than one liquid partial optical path length is the difference in distance. The amount corresponding to the amount of particles contained is attenuated more than the amount of light received measured with the one liquid partial optical path length (short liquid partial optical path length). Therefore, as the particle concentration increases, the rate of decrease in the amount of received light measured with a long liquid partial optical path length increases as compared to the rate of decrease in the amount of received light measured with a short liquid partial optical path length. Thus, since the ratio of the received light amount measured at different liquid partial optical path lengths is correlated with the particle concentration, the liquid property based on the ratio of these liquid partial optical path lengths and the ratio of these received light quantities, for example, The particle concentration can be detected. Specifically, based on the ratio of the liquid partial optical path lengths and the ratio of the amounts of received light, first the first transmittance, which is the transmittance of the liquid, is detected, and subsequently correlated with the first transmittance. Liquid properties, such as particle concentration, are detected.

  Here, when the light emission amount of the light emitting unit changes, the change amount is similarly reflected in each light reception amount. Therefore, the change amount can be easily removed by obtaining the ratio of the light reception amounts. In other words, by detecting the liquid property, for example, the particle concentration based on the ratio of the amount of received light, the liquid property, for example, the particle concentration can be detected without knowing the light emission amount of the light emitting unit. Therefore, according to the above configuration, it is possible to accurately detect the liquid property while suppressing the adverse effect due to the characteristic change of the light emitting unit when detecting the liquid property.

  Even if the output characteristics change depending on the ambient temperature of the light receiving unit, the change is reflected in the detection value of each received light amount in the same way. Can be removed. Therefore, according to the above configuration, the particle concentration can be accurately detected while suppressing the adverse effect due to the change in the characteristics of the light receiving unit when detecting the particle concentration.

  By the way, a specific apparatus in which the above-described liquid property detection method is implemented is, for example, a light-emitting part and a light-receiving part that are opposed to each other with a liquid interposed outside a housing that is made of a light-transmitting material and in which the liquid flows. At the same time, the housing includes a liquid passage that forms the first optical path and the second optical path, and a portion that includes only the housing that forms the third optical path. Light from the light emitting portion enters from the outer surface of the housing, exits from the housing outer surface on the opposite side through the liquid passage, and enters the light receiving portion. In such a liquid property detection device, foreign substances contained in the liquid adhere to the liquid passage wall surface. The foreign matter adhering to the wall surface of the liquid passage is present almost uniformly in the optical path from the light emitting portion to the light receiving portion, that is, on the first optical path and the second optical path, so that the light traveling toward the light receiving portion is absorbed by the foreign matter. Thus, each received light amount in the light receiving unit is reduced.

  When the amount of foreign matter attached is small, that is, when the light transmittance of the foreign matter layer is high, as described above, the first transmittance is detected based on the ratio of the first received light amount and the second received light amount. This makes it possible to accurately detect liquid properties such as particle concentration.

  However, when the foreign matter adhesion amount on the liquid passage wall surface increases and the light transmittance of the foreign matter layer decreases, it is difficult to accurately detect the liquid property, for example, the particle concentration, based on the ratio of the first received light amount and the second received light amount. It becomes.

  Therefore, in the liquid property detection method according to claim 1 of the present invention, the third light reception amount that is the amount of light received through the third optical path from the light emitting portion directly to the light receiving portion without passing through the liquid is determined. Based on the first transmittance and the second transmittance, a measurement is performed to calculate a second transmittance that is a transmittance of the foreign substance layer attached to the liquid passage wall surface based on the third received light amount and the calculated first transmittance. The liquid property is judged.

  Below, the specific liquid property detection procedure by the liquid property detection method of Claim 1 of this invention is demonstrated.

  When the ratio of the optical path lengths in the liquid in the first optical path and the second optical path is 1: n, the first received light quantity that is the received light quantity of light passing through the first optical path corresponding to “1” is the optical path length. Light transmittance, that is, transmittance α which is the first transmittance, light transmittance of foreign matter attached to the inner wall surface of the liquid passage which is the light emitting surface and the light receiving surface, that is, transmittance β which is the second transmittance, housing When the light transmittance of the foreign matter adhering to the outer wall of the liquid passage is defined as transmittance γ, it can be expressed by the following equation (1). Here, each transmittance is not expressed as a percentage, but 0 <α <1, 0 <β <1.

First received light amount = light emission amount of light emitting part × transmittance α × transmittance β ² × transmittance γ ² (1)
Further, the second received light amount that is the received light amount of light passing through the second optical path corresponding to “n” can be expressed by the following equation (2).

Second received light amount = light emission amount of light emitting part × transmittance α ⁿ × transmittance β ² × transmittance γ ² (2)
Moreover, the 3rd light reception amount which is the light reception amount of the light which passes through a 3rd optical path can be represented by following Formula (3).

Third received light amount = light emission amount of light emitting part × transmittance γ ² (3)
Then, when the ratio between the first received light amount and the second received light amount is obtained, the following equation (4) is obtained from the above equations (1) and (2).

Second received light amount / first received light amount = (transmittance α) ⁿ⁻¹ (4)
Then, the following equation (5) is obtained from the equation (4).

Transmittance α = (second received light amount / first received light amount) ^{1 / n−1} (5)
As can be seen from this equation (5), when the ratio of the different optical path lengths is 1: n, the transmittance α is calculated using the ratio of the respective optical path lengths and the ratio of the respective received light amounts measured by the respective optical path lengths. Can be sought. As is well known, the transmittance of light in a liquid and its properties, for example, the concentration of particles contained in the liquid are correlated, so the particle concentration can be determined by determining the transmittance.

  Thus, when the value (transmittance) correlated with the particle concentration is obtained based on the difference in transmitted light amount, as described above, it is possible to suppress the adverse effect on the detection of the particle concentration due to the characteristic change of the light emitting unit or the light receiving unit. become able to.

  Further, when the difference between the first received light amount and the second received light amount is obtained, the following equation (6) is obtained from the above equations (1) and (2).

Second received light amount−first received light amount = light emitting amount of light emitting portion × (α ⁿ −α) × β ² × γ ² (6)
Then, the following equation (7) is obtained from the equations (6) and (3).

β = [(second received light amount−first received light amount) / {third received light amount × (α ⁿ −α)}] ^1/2 (7)
By Expression (7), it is possible to detect the second transmittance that is the transmittance of the foreign material layer attached to the liquid passage wall surface.

  According to the liquid property detection method of the first aspect of the present invention, in addition to being able to detect the first transmittance, which is the transmittance of the liquid as the object to be measured, the permeation of the foreign substance layer attached to the liquid passage wall surface The second transmittance, which is the rate, can also be detected. Therefore, the liquid property, for example, the particle concentration can be accurately determined based on the first transmittance, and the foreign matter adhesion state on the liquid passage wall surface is monitored based on the second transmittance. It can correct | amend based on the made 2nd transmittance | permeability, and can maintain the determination accuracy of a liquid property favorably.

  In the liquid property detection method according to claim 2 of the present invention, when the second transmittance is less than a predetermined value, the property of the liquid is determined based on the first transmittance, and the second transmittance is less than the predetermined value. When it is large, the liquid property is determined based on the first transmittance and the second transmittance.

  When determining the liquid property based only on the first transmittance, that is, the transmittance of the liquid to be measured, the determination accuracy is affected by the amount of foreign matter adhering to the liquid passage wall surface. Until the amount of foreign matter adhering to the wall surface of the liquid passage reaches a certain amount, the liquid property can be accurately determined based only on the first transmittance. When the amount of foreign matter attached to the liquid passage wall surface exceeds a certain amount, the determination accuracy of the liquid property determination based only on the first transmittance is lowered. Therefore, if the value of the second transmittance at the maximum value of the foreign matter adhesion amount range on the liquid passage wall surface where the liquid property can be accurately determined based on only the first transmittance described above is set to a predetermined value. Even when the second transmittance exceeds a predetermined value, correction is performed based on the second transmittance, for example, based on a map or the like indicating the relationship between the magnitude of the second transmittance and the correction coefficient prepared in advance. By correcting, the determination accuracy of the liquid property can be maintained satisfactorily.

  In the liquid property detection method according to the third aspect of the present invention, when the second transmittance exceeds a limit value larger than a predetermined value, the liquid property determination is stopped and a warning signal is sent to notify the fact. It is characterized by doing.

  When the amount of foreign matter attached to the liquid passage wall surface further increases, it becomes difficult to correct based on the second transmittance.

  According to the above configuration, in such a case, it is possible to prevent any action based on an erroneous determination result by quickly stopping the liquid property determination. In addition, it is possible to notify the practitioner of the liquid property detection method of a decrease in the accuracy of liquid property determination and immediately perform necessary treatment.

  In the liquid property detection method according to claim 4 of the present invention, at least one of the light emitting unit and the light receiving unit is moved in the direction perpendicular to the optical axis of the light emitting unit with respect to the other by the drive mechanism, and the first received light amount and the second It is characterized by measuring the amount of received light and the third amount of received light.

  According to the configuration described above, the optical path of the measurement light is switched by moving at least one of the light emitting unit and the light receiving unit in a direction perpendicular to the optical axis of the light emitting unit with respect to the other. Therefore, the amount of light transmitted through each optical path can be measured using the same light emitting unit and light receiving unit, so that the influence of individual differences between the light emitting unit and the light receiving unit on the detection accuracy of the liquid property can be eliminated.

  Hereinafter, a first embodiment embodying a liquid property detection method according to the present invention will be described with reference to the drawings.

(First embodiment)
In the first embodiment, the liquid property detection method according to the present invention is applied to particle concentration detection in oil in an oil deterioration detection device attached to an automobile engine. The oil deterioration detection device detects the concentration of particles contained in the engine lubricating oil, such as soot that is a combustion product, wear powder generated in each moving part of the engine, that is, the degree of oil deterioration, and the detection result Based on this, for example, the replacement time of the lubricating oil is determined and displayed so that the driver can recognize it.

  FIG. 1 is a schematic diagram showing a configuration of an oil deterioration detection device 1 according to this embodiment attached to an engine of an automobile.

  As is well known, the engine 50 sucks an air-fuel mixture composed of air sucked from an intake passage and fuel injected from a fuel injection valve into a combustion chamber defined by a cylinder and a piston. The air-fuel mixture is ignited and burned by a spark plug provided in the combustion chamber, and after combustion, the exhaust gas is discharged from the combustion chamber to the exhaust passage. Further, lubricating oil is stored in the engine 50, and this lubricating oil is supplied to a movable part of the engine through a lubricating passage 51.

  Now, the oil deterioration detection apparatus 1 in this embodiment uses the lubricating oil of the engine 50 as a liquid to be inspected, and detects the concentration of particles (for example, soot) mixed in the lubricating oil using the amount of transmitted light. .

  The oil deterioration detection device 1 includes a detection mechanism 10, a control device 20, a display unit 30, an alarm mechanism 40, and the like.

  The detection mechanism 10 is a mechanism that detects the amount of light transmitted through the inspection target liquid, and is disposed in the middle of the lubrication passage 51. FIG. 2 schematically shows a cross section of the detection mechanism 10 in a direction orthogonal to the flow direction of the liquid to be inspected. As shown in FIG. 2, the detection mechanism 10 is roughly composed of a body 11, a light emitting diode 12 as a light emitting part, photodiodes 13a, 13b, 13c as a light receiving part, a driving mechanism 14, and the like.

  The body 11 has a flow path 15 through which lubricating oil that is a liquid to be inspected flows, and lubrication paths 51 are connected to both ends of the flow path 15. The body 11 is made of a translucent material such as colorless and transparent glass, a resin material, or the like. As shown in FIG. 2, the light emitting diode 12 and the photodiodes 13 a, 13 b, and 13 c are disposed outside the body 11 so as to face each other with the flow path 15 interposed therebetween. In the body 11, high-temperature lubricating oil flows through the flow path 15. Further, light emitted from the light emitting diode 12 passes through the body 11 and enters each photodiode 13a, 13b, 13c. Therefore, the material of the body 11 is required to be excellent in heat resistance and lubricating oil resistance and to have a high transmittance in order to suppress attenuation of transmitted light as much as possible. Therefore, in this embodiment, quartz glass is selected as the material of the body 11.

  The light emitting diode 12 emits a constant amount of light when a predetermined voltage is applied from the control device 20 through a drive circuit. A lens (not shown) for making the light emitted from the light emitting diode 12 into parallel light is provided on the emission surface of the light emitting diode 12. By this lens (not shown), most of the light emitted from the light emitting element 3c is used as inspection light without being diverged.

  The photodiodes 13a, 13b, and 13c are for detecting the light quantity after the light emitted from the light emitting diode 12 has passed through the lubricating oil that is the liquid to be inspected and the light quantity after having passed through the body 11. Since each photodiode 13a, 13b, 13c used in the present embodiment has a characteristic that the output increases as the amount of received light increases, an output having a magnitude corresponding to the amount of transmitted light can be obtained. . The outputs of the photodiodes 13a, 13b, and 13c are input to the amplifier circuit of the control device 20. Illustrated for focusing light emitted from the body 11 toward the photodiodes 13a, 13b, and 13c toward the photodiodes 13a, 13b, and 13c on the flow path 15 side of the photodiodes 13a, 13b, and 13c. No lens is provided.

  The light emitting diode 12 is held by a drive mechanism 14 as shown in FIG. The drive mechanism 14 is for moving the light emitting diode 12 so as to face any one of the photodiodes 13a, 13b, and 13c. The drive mechanism 14 is an actuator such as a stepping motor (not shown) or a linear solenoid (not shown), and a transmission mechanism (moving the light emitting diode 12 by transmitting the driving force generated by the actuator to the light emitting diode 12. (Not shown).

  When the light emitting diode 12 is at the position indicated by the solid line in FIG. 2 and at the position indicated by the broken line 12b, the light emitted from the light emitting diode 12 passes through the flow path 15, that is, passes through the lubricating oil that is a liquid. Then, the light enters the photodiode 13a or the photodiode 13b. When the light emitting diode 12 is at the position indicated by the broken line 12c in FIG. 2, the light emitted from the light emitting diode 12 does not pass through the flow path 15, but passes only through the quartz glass body 11 and enters the photodiode 13c. . That is, the optical path from the light emitting diode 12 to the photodiode 13a is the first optical path A, the optical path from the light emitting diode 12 to the photodiode 13b is the second optical path B, and the optical path from the light emitting diode 12 to the photodiode 13c is the third. This is the optical path C. Therefore, the received light amount of the photodiode 13a is the first received light amount P, the received light amount of the photodiode 13b is the second received light amount Q, and the received light amount of the photodiode 13c is the third received light amount R. Further, the length L1 of the portion that transmits through the flow path 15 in the first optical path A, that is, the portion that transmits lubricating oil, is the length of the portion that transmits the lubricating oil in the second optical path B as shown in FIG. It is longer than L2. By sequentially switching the position of the light emitting diode 12 by the drive mechanism 14, the optical path in which the light emitted from the light emitting diode 12 travels is switched to the first optical path A, the second optical path B, and the third optical path C. An output signal based on the first received light amount P is output from the photodiode 13a, an output signal based on the second received light amount Q is output from the photodiode 13b, and an output signal based on the third received light amount R is output from the photodiode 13c. Thus, by using the drive mechanism 14, it is possible to increase the detection accuracy of each received light amount P, Q, R by sharing one light emitting diode 12 as a light emitting unit.

  The drive mechanism 14 is controlled by a signal from the control device 20. The control device 20 performs control so that high accuracy of each position of the light emitting diode 12 in the drive mechanism 14, that is, high reproducibility of each position every time is obtained.

  The control device 20 includes a central processing control device (CPU), a read-only memory (ROM) that stores various programs and maps in advance, a random access memory (RAM) that temporarily stores CPU calculation results, an input interface, and an output. It is mainly composed of a microcomputer equipped with an interface. The control device 20 computes the detection result of the detection mechanism 10 and the like to calculate the particle concentration of the lubricating oil that is the inspection target liquid, and displays the calculated particle concentration, that is, the degree of oil deterioration on the display unit 30. Further, the control device 20 compares the detected particle concentration, that is, the degree of oil deterioration with a predetermined value. When the degree of oil deterioration exceeds a predetermined value, for example, when the degree of oil deterioration is large and oil replacement is required, An alarm is issued from the alarm mechanism 40 to urge that effect.

  Next, a liquid property detection method performed by the oil deterioration detection device 1 in the present embodiment will be described.

  In the present embodiment, the ratio of the received light amounts P and Q measured for the light in the first optical path A and the second optical path B having different lubricating oil transmission lengths, the length L1 of the lubricating oil transmission part in the first optical path A, and Lubricant transmittance α was determined from the ratio of the length L2 of the lubricating oil transmission part in the second optical path B, and measured for each of the received light amounts P and Q and the light in the third optical path C not passing through the lubricating oil. From the amount of received light R, the transmittance β of the foreign substance layer adhering to the wall surface of the flow path 15 is obtained.

  The transmittance of the lubricating oil flowing in the flow path 15 is the transmittance α. As shown in FIG. 2, a foreign substance adheres to the wall surface of the flow path 15 of the body 11 of the detection mechanism 10 to form a foreign substance layer X, and the transmittance is the transmittance β. Further, as shown in FIG. 2, foreign matter such as dust in the air or water droplets dewed by water vapor adheres to the outer surface of the body 11 of the detection mechanism 10 to form a dirty layer Y, and its transmittance is Transmittance γ. The light traveling along the first optical path A and the second optical path B passes through the dirt layer Y twice, the lubricating oil once, and the foreign substance layer X twice before entering the photodiode 13a or photodiode 13b from the light emitting diode 12. pass. The light traveling in the third optical path C passes through the dirt layer Y twice before entering the photodiode 13c from the light emitting diode 12. The ratio of the length L1 of the lubricating oil transmission part in the first optical path A and the length L2 of the lubricating oil transmission part in the second optical path B is 1: n. Here, if the light emission amount of the light emitting diode 12 is the light emission amount F, the first light reception amount P, the second light reception amount Q, and the third light reception amount R, which are the light reception amounts detected by the photodiodes 13a, 13b, and 13c, are: And can be represented by the following equations. Here, each transmittance is not expressed as a percentage, but 0 <α <1, 0 <β <1, and 0 <γ <1.

P = F × α × β ² × γ ² (8)
Q = F × α ⁿ × β ² × γ ² (9)
R = F × γ ² (10)
Here, the equation (8) and the equation (9) to the equation (11), that is, the lubricating oil transmittance α is obtained.

α = (Q / P) ^{1 / n−1} (11)
Moreover, Formula (12) is obtained from Formula (8) and Formula (9).

Q−P = F × (α ⁿ −α) × β ² × γ ² (12)
Then, the following equation (13), that is, the transmittance β of the foreign material layer X is obtained from the equations (12) and (10).

β = [(Q−P) / {R × (α ⁿ −α)}] ^1/2 (13)
As can be seen from the above equation (11), when the ratio of the length L1 of the lubricating oil transmission portion of the first optical path to the length L2 of the lubricating oil transmission portion of the second optical path is 1: n, this lubricating oil The transmittance α of the lubricating oil can be obtained by using the ratio of the length of the transmission part and the ratio of the length of the lubricating oil transmission part. And since there is a correlation that the transmittance α of the lubricating oil increases as the concentration of the particles contained in the lubricating oil increases, the liquid property, that is, the concentration of particles in the lubricating oil can be determined by determining the transmittance α of the lubricating oil. Can be sought. Expression (11) does not include the light emission amount F of the light emitting diode 12. In other words, in the liquid property detection method performed by the oil deterioration detection device 1 in the present embodiment, the transmittance α of the lubricating oil, that is, the liquid property can be detected regardless of the light emission amount F of the light emitting diode 12, so that the light emitting diode It is also possible to suppress the influence of the twelve characteristic changes, that is, the fluctuation of the light emission amount.

  By the way, when the operating time of the engine 50 increases, the foreign matter in the lubricating oil adheres to the wall surface of the flow path 15 of the detection mechanism 10 and the foreign matter layer X is formed. The transmittance of the foreign material layer X is the transmittance β. As the foreign material layer X increases, the transmittance β decreases. When the light from the light emitting diode 12 is absorbed by the foreign material layer X, the received light amounts P and Q of the photodiodes 13a and 13b are reduced. When the foreign material layer X is thin, that is, when the transmittance β is large, the particle concentration that is a liquid property can be accurately detected based only on the transmittance α of the lubricating oil. However, if the foreign matter layer X on the wall surface of the flow path 15 becomes thick and the transmittance β decreases, it becomes difficult to accurately detect the liquid property, that is, the particle concentration based only on the transmittance α of the lubricating oil. Therefore, in the liquid property detection method performed by the oil deterioration detection device 1 in the present embodiment, the liquid property is determined based on both the transmittance α of the lubricating oil and the transmittance β of the foreign material layer X attached to the flow path 15. is doing. For example, when the size of the transmittance β of the foreign material layer X is in a region that does not affect the accuracy of liquid property determination based only on the transmittance α of the lubricating oil, the liquid property is determined based only on the transmittance α of the lubricating oil. To do. When the size of the transmittance β of the foreign material layer X exceeds a predetermined value, that is, the boundary value of the above-described region, the liquid property determination result based only on the transmittance α of the lubricating oil is based on the transmittance β of the foreign material layer X. Correct and determine the final liquid properties. This correction is performed based on, for example, a map indicating the relationship between the magnitude of the transmittance β and the correction coefficient prepared in advance in the control device 20 based on experimental data or the like.

  When the thickness of the foreign material layer X adhering to the flow path 15 further increases as the engine operating time elapses, the particle concentration is accurately detected despite the correction based on the transmittance β of the foreign material layer X described above. It becomes difficult. In such a liquid property detection method performed by the oil deterioration detection device 1 in this embodiment, in such a case, the control device 20 immediately stops the liquid property determination operation. At the same time, the control device 20 activates the alarm mechanism 40 to inform the driver that the liquid property determination accuracy has decreased, and immediately performs necessary actions, for example, cleaning the flow path 15 of the detection mechanism 10. Alternatively, the detection mechanism 10 can be exchanged. As a result, it is possible to prevent a problem that some kind of treatment is performed based on a determination result with poor accuracy.

  In the liquid property detection method performed by the oil deterioration detection device 1 in the present embodiment described above, the light in the first optical path A and the second optical path B having different lubricating oil permeation lengths measured in the conventional particle concentration detection method. In addition to the received light amounts P and Q, the received light amount R is also measured for the light in the third optical path C that does not pass through the lubricating oil. Thereby, in addition to the transmittance α of the lubricating oil, the transmittance β of the foreign material layer X attached to the flow path 15 can also be calculated. Therefore, it is difficult to detect the particle concentration with high accuracy by the conventional particle concentration detection method by determining the liquid property based on both the transmittance α of the lubricating oil and the transmittance β of the foreign material layer X adhering to the flow path 15. Even when the foreign material layer X adhering to the flow path 15 increases, the liquid property can be detected with high accuracy.

  Next, the processing procedure of the liquid property detection method performed by the oil deterioration detection device 1 in the present embodiment will be described based on the flowchart of FIG. The liquid property detection process is executed by the control device 20 every predetermined time.

  When the liquid property detection process is started, the control device 20 first executes an initialization process in step S1.

  Subsequently, the control device 20 measures the amount of received light P, which is the amount of light transmitted through the first optical path A, as the process of step S2. At this time, the control device 20 drives the drive mechanism 14 to set the light emitting diode 12 at a position corresponding to the first optical path A.

  Subsequently, the control device 20 measures the amount of received light Q, which is the amount of light transmitted through the second optical path B, as the process of step S3. At this time, the control device 20 drives the drive mechanism 14 to set the light emitting diode 12 at a position corresponding to the second optical path B.

  Subsequently, the control device 20 measures the received light amount R, which is the amount of light transmitted through the third optical path C, as the process of step S4. At this time, the control device 20 drives the drive mechanism 14 to set the light emitting diode 12 at a position corresponding to the third optical path C.

  Subsequently, the control device 20 calculates the transmittance α and the transmittance β based on the measured amounts of received light P, Q, and R as the process of step S5.

  Subsequently, the control device 20 determines whether or not the calculated transmittance β is smaller than the limit value G as a determination process in step S6. When the transmittance β is smaller than the limit value G, the control device 20 determines the particle concentration that is a liquid property, that is, the oil deterioration degree K based on the transmittance α and the transmittance β as the processing of the subsequent step S7. Subsequently, the control device 20 causes the display unit 30 to display the determined degree of oil deterioration K as the subsequent process of step S8.

  On the other hand, when the calculated transmittance β is equal to or greater than the limit value G as a result of the determination process in the previous step S6, the control device 20 stops the liquid property detection process as the subsequent process in step S9. Subsequently, as a process of step S10, the alarm mechanism 40 is activated to notify the driver of the fact.

(Second Embodiment)
A second embodiment embodying the liquid property detection method according to the present invention will be described.

  2nd Embodiment changes the structure of the detection mechanism 10 of the oil degradation detection apparatus 1 with respect to 1st Embodiment. Since the configuration other than the configuration of the detection mechanism 10 is the same as that of the first embodiment, only changes in the configuration of the detection mechanism 10 will be described.

  In the detection mechanism 10 of the oil deterioration detection apparatus 1 in the second embodiment, one photodiode 16 is used as a photodiode, and the light emitting diode 12 and the photodiode 16 are fixed to a common bracket 17 as shown in FIG. is doing. The bracket 17 is rotationally driven around the rotation shaft 17 a by the drive mechanism 18.

  The light emitting diode 12 and the photodiode 16 are fixed to the bracket 17 so that their optical axes coincide with each other and are orthogonal to the flow direction of the flow path 15. The bracket 17 is rotatably held by the body 11 with its rotating shaft 17a orthogonal to the flow direction of the flow path 15.

  In the detection mechanism 10 of the oil deterioration detection device 1 according to the second embodiment, the bracket 17 is rotated by the drive mechanism 18 so that the optical axis positions of the light emitting diode 12 and the photodiode 16 are changed to the first as shown in FIG. The position is switched to each position of the optical path A, the second optical path B, and the third optical path C. Thus, the first received light amount P, the second received light amount Q, and the third received light amount R are sequentially measured.

  As described above, in the second embodiment, since the three received light amounts P, Q, and R are measured by one photodiode 16, the accuracy of the relative relationship between the received light amounts P, Q, and R is as follows. Can be increased.

  In addition, each said embodiment can also be changed and implemented as follows.

  In the first embodiment, one light-emitting diode 12 is moved by the drive mechanism 14, but the three light-emitting diodes 12 are fixed corresponding to the respective optical paths A, B, and C, and one photodiode is provided. 13 may be moved by the drive mechanism 14.

  In each of the embodiments described above, at least one of the light emitting diode that is the light emitting unit and the photodiode that is the light receiving unit is moved, but a plurality of detection units each including the light emitting diode and the photodiode are used, that is, the first optical path A, Three may be used for the second optical path B and the third optical path C.

  When an alarm is issued from the alarm mechanism 40, that is, when it is determined that the operation of the engine 50 is impossible, the engine output of the engine 50 is gradually decreased to finally stop the engine operation, A failure of the engine 50 can also be reliably prevented.

  In the above embodiment, the case where the present invention is applied to a device for detecting the particle concentration of engine lubricating oil has been described. However, the present invention can be similarly applied to devices for detecting the particle concentration of other liquids. For example, the present invention may be applied to a particle concentration detection application contained in a fuel other than lubricating oil, a fuel for automatic transmission, or the like. 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 the schematic explaining the structure of the oil deterioration detection apparatus which concerns on 1st Embodiment. It is sectional drawing which shows the structure of the detection mechanism of the oil degradation detection apparatus which concerns on 1st Embodiment. It is a flowchart which shows the procedure of the liquid property detection process which concerns on 1st Embodiment. It is sectional drawing which shows the structure of the detection mechanism of the oil degradation detection apparatus which concerns on 2nd Embodiment. It is a V arrow directional view in FIG.

Explanation of symbols

1 Oil deterioration detection device (liquid property detection device)
10 Detection Mechanism 11 Body 12 Light Emitting Diode (Light Emitting Unit)
13a, 13b, 13c Photodiode (light receiving part)
DESCRIPTION OF SYMBOLS 14 Drive mechanism 15 Flow path 16 Photodiode 17 Bracket 17a Rotating shaft 18 Drive mechanism 20 Control apparatus 30 Display part 40 Alarm mechanism 50 Engine 51 Lubricant oil path A 1st optical path B 2nd optical path C 3rd optical path F Light emission amount G Limit value K Degree of oil deterioration L1, L2 Length P First received light quantity Q Second received light quantity R Third received light quantity S1 to S10 Step X Foreign matter layer Y Dirt layer α transmittance β transmittance β transmittance

Claims (4)

In the liquid property detection method of irradiating the liquid from the light emitting unit and detecting the amount of transmitted light that passes through the liquid with the light receiving unit, and detecting the property of the liquid based on the detected transmitted light amount,
Measuring the first received light amount and the second received light amount, which are received light amounts passing through the liquid and passing through the first optical path and the second optical path having different optical path lengths in the liquid, and do not transmit the liquid Measuring a third light receiving amount that is a light receiving amount of light passing through a third optical path directly from the light emitting unit to the light receiving unit,
Calculating a first transmittance which is a transmittance of the liquid based on a ratio of the first received light amount and the second received light amount and a ratio of the length of the first optical path and the second optical path;
Based on the third received light amount and the calculated first transmittance, a second transmittance that is a transmittance of the light emitting surface of the light emitting portion and a foreign substance layer adhering to the light receiving surface of the light receiving portion is calculated,
A liquid property detection method, comprising: determining a property of the liquid based on the first transmittance and the second transmittance. If the second transmittance is less than a predetermined value, determine the property of the liquid based on the first transmittance,
2. The liquid property detection method according to claim 1, wherein when the second transmittance is larger than a predetermined value, the property of the liquid is determined based on the first transmittance and the second transmittance. .   3. The liquid property according to claim 2, wherein when the second transmittance exceeds a limit value larger than a predetermined value, the liquid property determination is stopped and a warning signal is transmitted to notify the fact. Detection method.   Measurement of the first received light amount, the second received light amount, and the third received light amount by moving at least one of the light emitting unit and the light receiving unit in a direction perpendicular to the optical axis of the light emitting unit with respect to the other by a driving mechanism The liquid property detection method according to claim 1, wherein the liquid property detection method is executed.

Images