Oil mist measuring device

Abstract

To provide an oil mist measurement device that can correct a measurement error due to dirt.SOLUTION: An oil mist measurement device includes: a correction-purpose first light reception unit that receives light irradiated with by a correction-purpose irradiation unit irradiating a reflection plate to be arranged inside an introduction room via an observation window with light, and reflected at a boundary between a surface on an introduction room side of the observation window and dirt adhered to the surface via the observation window, and outputs a value corresponding to an amount of received light; and a correction-purpose second light reception unit that receives light irradiated with by the correction-purpose irradiation unit via the observation window, and outputs a value corresponding to an amount of received light. The oil mist measurement device is configured to calculate a correction value according to the dirt of the observation window on the basis of the output value of the correction-purpose first light reception unit and the output value of the correction-purpose second light reception unit, and perform correction using the calculated correction value.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an oil mist measuring device that measures oil mist by optical means. [Background technology]

[0002] A typical example of an oil mist measuring device is an oil mist measuring device that is placed inside the crankcase of an internal combustion engine. This device is equipped with a casing having an oil mist introduction chamber, and a light emitting means and a light receiving means that are arranged to face the outside of a light-transmitting window provided in the oil mist introduction chamber. The light emitted by the light emitting means is reflected or scattered by the presence of oil mist introduced into the oil mist introduction chamber. The oil mist is detected by receiving this reflected or scattered light by the light receiving means through the light-transmitting window.

[0003] As described above, since light is projected and received through the light-transmitting window, there is a problem in that if the surface of the light-transmitting window becomes dirty with oil mist or the like, the transmittance of the light-transmitting window will decrease, and this decrease in transmittance will result in a measurement value that is lower than the actual value.

[0004] To address this problem, the technology in Patent Document 1 uses the detection signal value of the light receiving means when there is no oil mist in the oil mist introduction chamber as a reference, compares the detection signal value of the light receiving means when measuring oil mist with the reference detection signal value, and determines whether the light-transmitting window is dirty from the result and issues a report or alarm. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-157648 A Summary of the Invention [Problem to be solved by the invention]

[0006] The technology of Patent Document 1 contributes to preventing the continuation of inaccurate measurements due to dirt by notifying the user of dirt on the surface of the light-transmitting window. In other words, the user can receive the notification, stop the measurement, and remove the dirt from the light-transmitting window or replace the light-transmitting window, thereby enabling accurate measurements to be performed again.

[0007] However, rather than simply detecting dirt on the translucent window and reporting it, it would be more beneficial to configure the device so that measurement errors caused by dirt can be corrected, thereby suppressing errors and maintaining good measurement accuracy for a longer period of time. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides the following oil mist measuring device etc. That is, a measurement irradiating section irradiates light into an introduction chamber into which oil mist is introduced through an observation window provided in the introduction chamber, a measurement light receiving section receives, through the observation window, the light irradiated by the measurement irradiating section that is repelled or scattered by the oil mist in the introduction chamber and outputs a value according to the amount of light received, a correction irradiating section irradiates light through the observation window onto a reflector plate disposed in the introduction chamber, and receives, through the observation window, the light irradiated by the correction irradiating section and reflected at the boundary between the surface of the observation window on the introduction chamber inner side and dirt adhering to the surface, The oil mist measuring device comprises: a first correction light-receiving unit that outputs a value corresponding to the amount of received light; a second correction light-receiving unit that receives light irradiated by the correction irradiation unit and reflected by the reflector through the observation window and outputs a value corresponding to the amount of received light; a correction value calculation unit that calculates a correction value corresponding to dirt on the observation window surface based on the output value of the first correction light-receiving unit and the output value of the second correction light-receiving unit; and a measurement unit that measures oil mist based on the output value of the measurement light-receiving unit and the correction value calculated by the correction value calculation unit. Effect of the Invention

[0009] According to the present invention, by calculating a correction value corresponding to the degree of dirt on the observation window, the correction value can be used to measure oil mist, and the measurement time with good accuracy can be extended. [Brief description of the drawings]

[0010] [Figure 1] Schematic diagram showing an example of an oil mist measuring device [Diagram 2] A conceptual diagram showing the element holding block and the elements it holds. [Diagram 3] A schematic diagram showing a cross section of a portion of an oil mist measuring device in which the element holding block shown in Figure 2 is placed. [Figure 4] Block diagram showing the functional configuration of the oil mist measuring device [Diagram 5] FIG. 1 is a conceptual diagram for explaining a correction value calculation process; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the present invention should not be limited to these embodiments, and can be embodied in various forms without departing from the spirit of the present invention. <Embodiment> <Summary>

[0012] The oil mist measuring device of this embodiment is characterized in that it is equipped with an optical configuration for measuring the dirt on the observation window, calculates a value corresponding to the dirt on the observation window from this configuration, and corrects the oil mist measurement value using the calculated value. <Configuration>

[0013] Fig. 1 is a schematic diagram showing an example of an oil mist measuring device of this embodiment. Fig. 1(a) is a perspective view, and Fig. 1(b) is a cross-sectional view. As shown in the figure, the oil mist measuring device 100 is provided with a cylindrical introduction chamber 101 that is disposed in a measurement space such as the inside of a crankcase and has a hole for introducing oil mist, an observation window 102 for viewing the introduction chamber from outside the introduction chamber, an element holding block 103 that holds a light emitting element and a light receiving element for measuring the oil mist in the introduction chamber through the observation window 102, and a board 104 that is connected to each element.

[0014] The element holding block 103 holds an LED (light emitting diode) 105, which is a light emitting element, and a PD (photodiode) 106, which is a light receiving element. The oil mist is measured by receiving light irradiated by the LED 105 that is reflected or scattered by the oil mist in the introduction chamber and then measuring the oil mist. Although not shown in the figure, the element holding block 103 also holds a correction LED and PD for making corrections in accordance with dirt on the observation window.

[0015] The board 104 is also connected to a processor 107, a main memory 108, and a ROM 109. The processor 107 performs arithmetic processing according to a program deployed on the main memory 108, processes and stores data, and controls each piece of hardware. The board 104 may also include an input / output interface and a communication interface (not shown). The processor is an example of an arithmetic processing device. The main memory provides a working area for the arithmetic processing device. The ROM is an example of a non-volatile memory that stores various programs and data, including an OS (operating system).

[0016] Fig. 2 is a conceptual diagram showing an element holding block and the elements held therein. Fig. 2(a) is a front view from the observation window side, Fig. 2(b) is a cross-sectional view along the AA line, and Fig. 2(c) is a cross-sectional view along the BB line. As shown in each figure, LED 202 and PD 203 for measuring oil mist, and LED 204, PD 205, and PD 206 for correction are arranged in element holding block 201. In this figure, all elements are arranged in one block, but each element may be divided and held in multiple blocks.

[0017] Fig. 3 is a conceptual diagram showing a cross section of a part of an oil mist measuring device in which the element holding block shown in Fig. 2 is arranged. This diagram shows a cross section in which a correction LED 304 and PDs 305 and 306 appear. As shown in the figure, the element holding block 301 is housed in a cylindrical case that forms an introduction chamber 303, and contacts an observation window 302 on the inside of the introduction chamber. In addition, a reflector 307 that is arranged in the introduction chamber via a holding member 308 is configured to reflect light irradiated from the LED 304.

[0018] 4 is a block diagram showing the functional configuration of the oil mist measuring device of this embodiment. As shown in the figure, the oil mist measuring device 400 has a measurement irradiation section 401, a measurement light receiving section 402, a correction irradiation section 403, a first correction light receiving section 404, a second correction light receiving section 405, a correction value calculation section 406, and a measurement section 407. The function of each section will be described below.

[0019] The measurement irradiation unit 401 has a function of irradiating light into the introduction chamber into which the oil mist is introduced through an observation window provided in the introduction chamber. This function can be realized by a light emitting element such as the LED 105 shown in Fig. 1 or the LED 202 shown in Fig. 2, the processor 107, the main memory 108, and the ROM 109 shown in Fig. 1, etc.

[0020] The measurement light receiving unit 402 has a function of receiving light, which is irradiated by the measurement irradiation unit and reflected or scattered by the oil mist in the introduction chamber, through an observation window, and outputting a value according to the amount of received light. This function can be realized by a light receiving element such as the PD 106 shown in Fig. 1, the PD 203 shown in Fig. 2, or a phototransistor, and the processor 107, main memory 108, and ROM 109 shown in Fig. 1.

[0021] The correction irradiation unit 403 has a function of irradiating light to a reflector placed in the introduction chamber through an observation window. This function can be realized by a light emitting element such as the LED 204 shown in Fig. 2, the processor 107, the main memory 108, and the ROM 109 shown in Fig. 1, etc.

[0022] The first light-receiving unit for correction 404 has a function of receiving light, which is irradiated by the irradiating unit for correction and is reflected at the boundary between the surface of the observation window on the inside of the entrance chamber and dirt adhering to the surface, through the observation window, and outputting a value according to the amount of received light. This function can be realized by a light-receiving element such as PD 205 shown in Fig. 2, and the processor 107, main memory 108, and ROM 109 shown in Fig. 1.

[0023] The second light-receiving unit for correction 405 has a function of receiving the light irradiated by the irradiating unit for correction and reflected by the reflector through an observation window, and outputting a value according to the amount of received light. This function can be realized by a light-receiving element such as the PD 206 shown in Fig. 2, the processor 107, the main memory 108, and the ROM 109 shown in Fig. 1, etc.

[0024] The correction value calculation unit 406 has a function of calculating a correction value according to dirt on the observation window surface based on the output value of the first correction light receiving unit and the output value of the second correction light receiving unit. Specifically, the correction value is calculated as the transmittance of dirt adhering to the surface of the observation window. The function of the correction value calculation unit can be realized by the processor 107, main memory 108, ROM 109, etc. shown in FIG. 1.

[0025] The measurement unit 407 has a function of measuring oil mist based on the output value from the measurement light receiving unit and the correction value calculated by the correction value calculation unit. As described above, the correction value is the transmittance of dirt on the observation window surface. Oil mist is measured using this transmittance as the correction value. This function can be realized by the processor 107, main memory 108, ROM 109, etc. shown in FIG. 1. <Calculation of correction value and oil mist measurement>

[0026] The process of calculating the correction value and measuring the oil mist in the oil mist measuring device will be described below. Fig. 5 is a conceptual diagram for explaining the correction value calculation process. As shown in the figure, a correction LED 504, a first correction PD 505, and a second correction PD 506 are arranged on an element holding block 501. A reflector 507 is arranged at a position facing the element holding block 501 with an observation window 502 in between (holding member is not shown). In addition, oil mist, oil, etc. adhere to the surface of the observation window 502, causing dirt 508.

[0027] The first PD 505 is configured to receive light, which is irradiated by the LED 504 and reflected at the boundary between the surface of the observation window 502 and dirt 508 attached to the surface, through the observation window. The dotted arrow in the figure indicates the path of the irradiated light. The second PD 506 is configured to receive light, which is irradiated by the LED 504, transmitted through the observation window 502, and reflected by the reflector 507, through the observation window 502. The first PD 505 and the second PD 506 output a value according to the amount of light received. The light irradiated by the LED 504 and received by the second PD 506 passes through dirt 508 attached to the surface of the observation window 502 before and after reflection by the reflector 507. During this passage, the light is absorbed by the dirt attached to the observation window 502, and the amount of light received by the second PD 506 decreases accordingly. On the other hand, the light received by the first PD 505 does not pass through the dirt 508 on the observation window 502. Since the light received by each PD is emitted from the same LED 504, the dirt 508 on the observation window 502 can be evaluated from the output value of the light received by each PD.

[0028] The measurement system for evaluating dirt on the observation window is built based on the following assumptions. These assumptions do not hold strictly when implemented, but they hold true in terms of measurement by performing the adjustment work described below and calculating the ratio with the PD output at the time of adjustment. The assumptions are as follows. 1. No reflection occurs on the upper surface (the surface on the element holding block 501 side) or inside the observation window 502. 2. No absorption occurs inside the observation window 502. 3. If there is no dirt on the bottom surface of the observation window 502, all of the light that reaches the bottom surface of the observation window 502 is transmitted. 4. No light is transmitted through the reflector 507, and all light that reaches the surface of the reflector 507 is reflected. 5. The light reflected by the reflector 507 is not reflected by the lower surface of the observation window 502 . 6. If there is dirt on the bottom surface of the observation window 502 , part of the light emitted from the LED 504 is reflected at the boundary between the observation window 502 and the dirt 508 and enters the first PD 505 . 7. Due to dirt 508 on the observation window 502 and dirt adhering to the reflector 507, part of the light that reaches the observation window 502 is absorbed. 8. The light reflected by the reflector 507 passes through the observation window 502 and enters the second PD. 9. Light reflection occurs only at the boundary between the lower surface of the observation window 502 and the dirt 508 and on the surface of the reflector 507, and does not occur on the surface of the dirt 508. 10. The dirt 508 adhering to the lower surface of the observation window 502 is the same as the dirt adhering to the reflector, and the light absorption by the dirt is also the same. 11. It is assumed that there is no reflection or scattering due to oil mist between the observation window 502 and the reflector 507.

[0029] Based on the above premise, we will consider the output value of the first PD505, which receives light irradiated from the LED504 and reflected at the boundary between the underside of the observation window 502 and the adhering dirt 508, and the output value of the second PD06, which receives light irradiated from the LED504 and reflected by the reflector 507.

[0030] The transmittance of the dirt 508 adhering to the observation window 502 is τ G The reflectance of the boundary between the observation window 502 and the dirt 508 is γ G , the absorption rate of the dirt 508 attached to the observation window 502 is ε G The reflectance of the dirty reflector 507 is γ R , the absorption rate of dirt adhering to the reflector 507 is ε R When 0≦τ G , γ G , ε G , γ R , εR ≦1, τ R =0 (1) The output values ​​(after I / V conversion and amplification) of the first PD505 and the second PD506 are V PD1 , V PD2 Then, V PD1 = L α γ G (2) V PD2 = L β τ G ·γ R ·τ G = L β τ G (1-ε R )·(1-ε R )·τ G = L β τ G 2 (1-ε R ) 2 (3) Here, L: LED light intensity α: constant representing the I / V conversion and amplification of the first PD β: constant representing the I / V conversion and amplification of the second PD Furthermore, from Kirchhoff's law, τ G +γ G +ε G =1 (4) Gamma R +ε R =1 (5) It is.

[0031] Next, the adjustment work will be described. First, in a state where the observation window and reflector are free of dirt and oil mist, PD1 , V PD2 In this case, from the premise, γ G = 0, τ G = 1, ε R =0, from equations (2) and (3) V PD1 = L α γ G =0 (6) V PD2 = L β τ G2 (1-ε R ) 2 = L β (7) is obtained.

[0032] Next, the observation window was replaced with one that has a total reflection on the bottom surface, and V PD1 , V PD2 In this case, from the premise, γ G = 1, τ G =0, and from equations (2) and (3), V PD1 = L α γ G = L α (8) V PD2 = L β τ G 2 (1-ε R ) 2 =0 (9) Here, the reflectance of the bottom surface of the observation window γ G γ G If it is difficult to obtain V = 1, or if the reflectance increase due to actual dirt is significantly different, it is sufficient to carry out the experiment using an observation window with a known reflectance, and equation (8) can be made V PD1 = (known emissivity of the observation window) L α In reality, equation (6) is simply V PD1 The offset value of (7) is V PD1 The span value of (8) is V PD2 The span value of (9) is V PD2 The offset value of V is set as above, taking into account the prerequisites. PD1 Then, in equation (7), V PD2 Then, by performing a ratio calculation with equation (8), the premised conditions 1 to 5 will be met in actual measurements.

[0033] In actual measurements, dirt adheres to the observation window, and its transmittance τ G When the value of the span decreases, the oil mist measurement value is lower than the actual value. When the ratio of the span value during adjustment is used to process the data during the actual measurement, the following is obtained from equations (2), (3), (7), and (8): V PD1´ = L α γG / L·α=γ G (10) V PD2´ = L β τ G 2 (1-ε R ) 2 / L·β=τ G 2 (1-ε R ) 2 (11) Here, the dirt on the observation window does not absorb light, that is, ε G Only when V = 0, V PD1´ =1-τ G This makes it possible to compensate for dirt on the observation window. Equation (11) is obtained from prerequisite 10 as follows: V PD2´ = τ G 2 (1-ε R ) 2 = τ G 2 (1-ε G ) 2 (12) Equation (10) is V PD1´ =γ G =1-(τ G +ε G ) · · · (13) From equations (12) and (13), the unknowns are τ G , ε G Since there are two of them, by solving them simultaneously, we get τ G The transmittance τ of the dirt adhering to the observation window can be calculated. G Using this as a correction value, it is possible to measure the oil mist by compensating for the decrease in the oil mist measurement value due to dirt adhering to the observation window. <Effects>

[0034] As described above, the oil mist measuring device of this embodiment calculates the transmittance of dirt adhering to the observation window as a correction value, and can measure the oil mist using the correction value. This makes it possible to extend the measurement time with good accuracy compared to conventional oil mist measuring devices that simply notify the presence of dirt. <Other embodiments>

[0035] Based on the above-mentioned oil mist measuring device, it can be further configured to have a judgment unit that judges the degree of dirt on the observation window. The judgment unit has a function of judging the degree of dirt based on a comparison between the calculated correction value and a predetermined value. This function can be realized by the processor 107, main memory 108, ROM 109, etc. shown in FIG. 1.

[0036] As described above, by calculating the correction value according to the dirt on the observation window, it is possible to continue the oil mist measurement while maintaining good accuracy. On the other hand, it is also necessary to remove the dirt on the observation window. Therefore, the correction value according to the dirt on the observation window is compared with a predetermined value to determine the degree of dirt on the observation window. There are various possible levels of dirt to be determined, and for example, the level may be determined as "low," "medium," or "high," or the level of dirt that requires stopping the measurement or removing the dirt from the observation window may be determined.

[0037] It is also preferable to configure the determination unit to output the determination result. For example, the degree of dirt on the observation window described above may be displayed, or an alarm may be output to prompt the user to remove the dirt from the observation window or to stop the measurement. The alarm may be output to other devices or terminals via a network. The function of the determination unit can be realized by the processor 107, main memory 108, ROM 109, and output devices such as a display and a speaker via an input / output interface, as shown in FIG. 1. [Explanation of symbols]

[0038] 100, 400: Oil mist measuring device 101, 303: Introduction room 102, 302: Observation window 103, 201, 301: Element holding blocks 104: Substrate 105, 202: Measurement LED 106, 203: PD for measurement 107: Processor 108: Main memory 109:ROM 204, 304: Correction LED 205, 206, 305, 306: Correction PD 307:Reflector 308: Retaining member 401: Measurement irradiation part 402: Measurement light receiving section 403: Correction irradiation unit 404: First light receiving section for correction 405:Second light receiving section for correction 406: Correction value calculation unit 407:Measurement part

Claims

1. a measurement irradiation unit that irradiates light into an introduction chamber into which the oil mist is introduced through an observation window provided in the introduction chamber; a measurement light receiving unit that receives light irradiated by the measurement irradiating unit and reflected or scattered by the oil mist in the introduction chamber through the observation window and outputs a value corresponding to the amount of received light; a correction irradiation unit that irradiates light onto a reflector disposed in the introduction chamber through the observation window; a first light receiving unit for correction, which receives light irradiated by the irradiating unit for correction and reflected at a boundary between a surface of the observation window on the side of the entrance chamber and dirt adhering to the surface through the observation window, and outputs a value corresponding to the amount of light received; a second light-receiving section for correction that receives the light irradiated by the light-irradiating section for correction and reflected by the reflecting plate through the observation window and outputs a value according to an amount of the received light; a correction value calculation unit that calculates a correction value corresponding to dirt on the surface of the observation window based on an output value of the first correction light receiving unit and an output value of the second correction light receiving unit; a measurement unit that measures the oil mist based on an output value from the measurement light receiving unit and a correction value calculated by the correction value calculation unit; An oil mist measuring device comprising:

2. 2. The oil mist measuring device according to claim 1, further comprising a determination unit that determines the degree of contamination of the observation window based on a comparison between the calculated correction value and a predetermined value.

3. 3. The oil mist measuring device according to claim 2, further comprising an alarm unit that outputs an alarm based on a result of the determination by the determination unit.

4. 4. The oil mist measuring device according to claim 1, wherein the measurement irradiating section, the measurement light receiving section, the correction irradiating section, the first correction light receiving section, and the second correction light receiving section are provided in one block.

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