Oil Mist Measuring Device

Abstract

To provide an oil mist measurement device for preventing droplet-shaped oil from being easily stored inside an introduction chamber.SOLUTION: An oil mist measurement device includes: a cylindrical introduction chamber having pierced through-holes to introduce oil mist in a side peripheral surface; an irradiation section for radiating light via an observation window arranged in the introduction chamber toward the inside of the introduction chamber; a light reception section for receiving the light radiated by the irradiation section and reflected or scattered by the oil mist inside the introduction chamber via the observation window, and then, outputting a value corresponding to a light reception amount; and a measurement section for measuring the oil mist based on the output value of the light reception section. The through-holes are obliquely pierced in a circumferential direction with respect to a normal direction of the side peripheral surface of the introduction chamber.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] As a typical example of an oil mist measuring device, there is an oil mist measuring device disposed in the crankcase of an internal combustion engine. This is a device including a casing having an oil mist introduction chamber, and a light emitting means and a light receiving means disposed so as to face the outside of a light transmitting window provided in the oil mist introduction chamber. Due to the presence of oil mist introduced into the oil mist introduction chamber, the irradiation light by the light emitting means is reflected or scattered. The reflected light or scattered light is received by the light receiving means through the light transmitting window to detect the oil mist.

[0003] The above-described introduction chamber is a cylindrical body provided with a plurality of through holes on its circumferential surface. By disposing this cylindrical body in the crankcase, the oil mist in the crankcase is introduced into the introduction chamber through the through holes. Here, not only oil mist but also droplet-shaped oil exists in the crankcase. The droplet-shaped oil stains the introduction chamber and the light transmitting window, resulting in measurement errors. Therefore, preventing the droplet-shaped oil from entering the introduction chamber is important for performing good measurement with less error.

[0004] From such a viewpoint, for example, in the oil mist detection device disclosed in Patent Document 1, the tubular introduction chamber is a double tube of an outer tube and an inner tube. While circular through holes are provided on the circumferential surfaces of the respective tubes, the through holes of the outer tube and the through holes of the inner tube are arranged alternately so that a straight path into the inner tube of the introduction chamber does not occur. With such a configuration, while not inhibiting the introduction of oil mist into the inner tube, it is possible to prevent the droplet-shaped oil pouring down from above from entering the inner tube of the introduction chamber.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The technology of Patent Document 1 has the outer tube and the inner tube configured as described above, and the structure is complex. Once the droplet-shaped oil enters the introduction chamber, it is difficult to be discharged outside the introduction chamber and tends to stay, so it is difficult to keep the inside of the introduction chamber clean. In addition, there is a problem that the droplet-shaped oil adhering to the surface of the introduction chamber or the oil entering the introduction chamber blocks the through hole due to the surface tension of the oil depending on the relationship between its viscosity and the size of the through hole, thereby inhibiting the introduction of oil mist.

Means for Solving the Problems

[0007] Therefore, in order to solve the above problems, the present invention provides the following oil mist measuring devices, etc. That is, a cylindrical introduction chamber having a through hole for introducing oil mist formed in its side peripheral surface, an irradiation unit that irradiates light into the chamber of the introduction chamber through an observation window provided in the introduction chamber, a light receiving unit that receives the light reflected or scattered by the oil mist in the introduction chamber through the observation window and outputs a value corresponding to the received light amount, and a measuring unit that measures the oil mist based on the output value by the light receiving unit. The through hole is characterized in that it is formed to be inclined in the circumferential direction with respect to the normal direction of the side peripheral surface of the introduction chamber. An oil mist measuring device, etc. is provided.

Effects of the Invention

[0008] According to the present invention, it is possible to provide an oil mist measuring device in which droplet-shaped oil is less likely to stay inside the introduction chamber.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the present invention should not be limited to these embodiments, and can be implemented in various forms without departing from the gist thereof. <Embodiment 1> <Overview>

[0011] The feature of the oil mist measuring device of the present embodiment is that a through-hole for introducing oil mist into the introduction chamber is drilled so as to be inclined in the circumferential direction with respect to the normal direction of the side peripheral surface of the introduction chamber. <Configuration>

[0012] FIG. 1 is a conceptual diagram showing an example of the oil mist measuring device of the present embodiment. As shown in the figure, the oil mist measuring device 100 includes a cylindrical introduction chamber 101 disposed in a measurement space such as inside a crank case for introducing oil mist, a cylindrical member 102 connected to the introduction chamber 101 and enclosing an irradiation unit and a light receiving unit described later, and a case 103 connected to the cylindrical member 102. A plurality of through-holes 104 are drilled in the side peripheral surface of the introduction chamber 101. Note that the introduction chamber 101 and the cylindrical member 102 may be integrally formed. For example, the introduction chamber 101 may be configured to be connected to the case 103, and the irradiation unit and the light receiving unit may be held inside the introduction chamber 101 on the side closer to the case 103.

[0013] Figure 2 is a side view of the oil mist measuring device shown in Figure 1. And Figure 3 is a cross-sectional view of the oil mist measuring device shown in Figure 2. Hereinafter, the configuration of the oil mist measuring device of the present embodiment will be described with reference to Figures 1, 2, and 3. Note that the same components are denoted by the same reference numerals.

[0014] The introduction chamber 101 has a cylindrical structure into which oil mist is introduced. As shown in Figure 3, the introduction chamber 101 has a hollow structure and is configured such that the oil mist 110 is introduced into the introduction chamber through the through-hole 104. Further, a light-transmissive observation window 105 is provided on the side connected to the cylindrical member 102 of the introduction chamber 101. In addition, an irradiation unit 106 and a light-receiving unit 107 are provided on the cylindrical member 102 facing the observation window 105 so as to project light into the interior of the introduction chamber 101 through the observation window 105 and receive light from the interior of the introduction chamber 101.

[0015] When it is planned to measure with the oil mist measuring device in a fixed posture, in the region of the side peripheral surface of the introduction chamber 101 near the observation window 105 during oil mist measurement, no through-hole 104 is provided above the side peripheral surface, and a discharge hole 108 for discharging droplet-like oil or the like from the introduction chamber 101 is provided below the side peripheral surface at a position near the observation window 105. This is to prevent the light-receiving unit 107 from directly receiving background light other than the reflected light and scattered light by the oil mist 110 through the through-hole 104, since the light-receiving unit 107 is provided on the side sandwiching the observation window 105.

[0016] The irradiation unit 106 irradiates light into the introduction chamber through the observation window 105 provided in the introduction chamber 101. Specific means for irradiating light include light-emitting elements such as LEDs (light emitting diodes).

[0017] The light receiving unit 107 receives, through the observation window 105, the light reflected or scattered by the oil mist 110 in the introduction chamber from the light irradiated by the irradiation unit 106, and outputs a value corresponding to the received light amount. Specific means for receiving light include light receiving elements such as PD (Photodiode) and phototransistors. Inside the case 103, a substrate 109 is accommodated, which is connected to the LED 106 as the irradiation unit and the PD 107 as the light receiving unit, and the output of the substrate 109 is sent to the measurement unit described later.

[0018] Then, the measurement unit measures the oil mist based on the output value from the light receiving unit 106. The more the oil mist 110 exists in the measurement region inside the introduction chamber 101, the more the amount of received reflected light or scattered light by the oil mist increases, and accordingly, the output value of the light receiving unit 106 also increases. Due to such a relationship, the oil mist can be measured based on the output value of the light receiving unit 106. The function of the measurement unit is realized by a processing device such as a CPU, a main memory that provides a work area for the processing device, and a non-volatile memory such as a ROM that stores data and programs. It acquires the output value from the light receiving unit, executes a predetermined program, and refers to the relational expression between the output value and the oil mist amount to perform oil mist measurement.

[0019] FIG. 4 is a conceptual diagram showing an example of a cross section of the introduction chamber. As shown in FIG. 4, the through hole 402 formed in the side peripheral surface of the introduction chamber 401 is formed to be inclined at an angle β in the circumferential direction with respect to the normal direction 403 of the side peripheral surface (dotted arrow). Also, the other through holes are each formed to be inclined in the circumferential direction with respect to the normal direction of the side peripheral surface. The inclination angle with respect to the normal direction may be the same for all the through holes or different.

[0020] Further, the through holes 402 are preferably arranged evenly in the circumferential direction of the introduction chamber 401. In a measurement environment such as inside a crankcase, since the oil mist and oil move in all directions, it is preferable to arrange them evenly in the circumferential direction in order to introduce the oil mist from various directions. With such a configuration, it is also possible to discharge the droplet-shaped oil that has entered the inside of the introduction chamber to the outside through the through holes.

[0021] The inclination angle β with respect to the normal direction for drilling the through hole 402 is preferably 45° or more. The larger the inclination angle β is, the less likely the opening on the outer surface of the side peripheral surface of the introduction chamber and the opening on the inner surface overlap in the normal direction, contributing to cutting off the linear intrusion path of the atomized oil from the outside to the inside of the introduction chamber.

[0022] Also, the side peripheral surface of the introduction chamber 401 is formed as a single plate at least at the location where the through hole 402 is arranged. As described above, the through hole 402 is drilled obliquely in the circumferential direction with respect to the normal direction of the side peripheral surface, thereby cutting off the linear path of the atomized oil from the outside to the inside of the introduction chamber. In addition, by inclining the direction of the through hole, a location where the inner surface of the through hole and the inner surface of the introduction chamber are in contact at an obtuse angle is generated, so that the atomized oil that has entered the through hole is transmitted from the inner surface of the through hole to the inner surface of the introduction chamber and flows, preventing the atomized oil from immediately dripping from the through hole into the internal space of the introduction chamber. Furthermore, the atomized oil flowing along the inner surface of the introduction chamber flows in the vertical direction and is discharged to the outside of the introduction chamber through the through hole or discharge hole located in the vertical direction. In order to obtain such an effect, the side peripheral surface of the introduction chamber is formed by a single plate so that the inner surface of the through hole can be generated.

[0023] In the technology disclosed in the above-mentioned Patent Document 1, in order not to generate a linear path into the inside of the introduction chamber, the introduction chamber is made into a double tube of an outer tube and an inner tube, and circular through holes are provided on the circumferential surfaces of the outer tube and the inner tube respectively, and a structure is adopted in which the through holes of the outer tube and the through holes of the inner tube are arranged alternately. In the case of such a complex structure, the manufacturing cost naturally becomes high. In contrast, the oil mist detection device according to the present invention has the merit that it can be manufactured at low cost because it adopts a simple structure of drilling a through hole with an inclination in a single-plate introduction chamber.

[0024] FIG. 5 is a conceptual diagram showing an enlarged part of the introduction chamber. As shown in FIG. 5, the opening shape of the through-hole 502 formed in the side peripheral surface of the introduction chamber 501 is a rectangle with the longitudinal direction of the introduction chamber 501 as the long side direction.

[0025] In a conventional oil mist detection device as disclosed in Patent Document 1, the shape of the through-hole for guiding the oil mist into the introduction chamber is circular, and the liquefied oil droplets adhering to the surface of the introduction chamber may exert surface tension and block the through-hole. As a result, the introduction efficiency of the oil mist decreases, which hinders the oil mist measurement.

[0026] On the other hand, in the oil mist measurement device according to the present invention, the opening shape of the through-hole formed in the side peripheral surface of the introduction chamber is rectangular, and the surface tension of the oil acting at the periphery of the opening becomes non-uniform depending on the location of the periphery, making it more difficult for the oil film to form compared to the case where the opening shape is circular. Therefore, even if oil adheres to the surface of the introduction chamber, it is difficult to block the through-hole and less likely to interfere with the oil mist measurement.

[0027] Also, the difficulty of forming the oil film depends on the properties of the oil (density, viscosity, etc.), the aspect ratio of the rectangle of the opening shape, the lengths of the long side and the short side, and the plate thickness of the side peripheral surface where the through-hole is arranged. As shown in FIG. 5, if the length of the long side of the rectangle, which is the opening shape of the through-hole, is "L", the length of the short side is "S", and the plate thickness of the side peripheral surface is "t", the preferable ranges of each value are as follows. When the plate thickness is 0.5 ≤ t ≤ 1.5 mm, short side: 1.5 ≤ S ≤ 2.5 mm, long side: 3 ≤ L ≤ 150 mm Furthermore, the more preferable range is as follows. Plate thickness: 0.5 ≤ t ≤ 1 mm, short side S × long side L = 2 mm × 20 mm Also, when the plate thickness is 1.5 ≤ t ≤ 10 mm, short side: 2.5 ≤ S ≤ 4 mm, long side: 5 ≤ L ≤ 150 mm Furthermore, the more preferable range is as follows. Plate thickness: 1.5 ≤ t ≤ 3.5 mm, short side S × long side L = 3 mm × 20 mm

[0028] If the short side S is made smaller than the above-described range, the oil film is likely to form. On the other hand, if the short side S is made larger, the liquefied oil is likely to directly enter the through hole. Further, the long side L has a length corresponding to the short side S, and setting it within the above-described range is preferable for making it difficult to form an oil film.

[0029] It is also preferable to further include a configuration for detecting contamination of the observation window. The surface of the observation window may be contaminated due to adhesion of oil mist or the like. Such surface contamination reduces the transmittance of the observation window and decreases the amount of light received by the light-receiving unit compared to the actual situation. As a result, the accuracy of oil mist measurement decreases. Therefore, in addition to the light-emitting element and the light-receiving element for oil mist measurement, a light-emitting element and a light-receiving element for contamination detection are configured to be held in the element block.

[0030] The detection of contamination of the observation window may be performed when the internal combustion engine is stopped (when there is no oil mist) or when the internal combustion engine is operating (when there is oil mist). When performing contamination detection when the engine is stopped, for example, an output value corresponding to the amount of light received by the contamination detection light-receiving element when irradiated by the contamination detection light-emitting element in a state where there is no oil mist and the observation window is not contaminated is stored in advance as a reference value, and when the output value corresponding to the amount of light received with respect to this reference value drops below a predetermined range, it can be configured to determine that the observation window is contaminated. Also, when performing it during operation of the internal combustion engine, for example, the amount of oil mist immediately before performing contamination detection is acquired, and the output value of the contamination detection light-receiving element when the observation window is not contaminated at that amount of oil mist is compared with the actual output value of the contamination detection light-receiving element, and when the difference exceeds a predetermined range, it can be configured to determine that the observation window is contaminated. <Embodiment 2> <Overview>

[0031] This embodiment is based on Embodiment 1 and relates to an oil mist measurement device having an introduction chamber in a polygonal cylinder shape. <Configuration>

[0032] The configuration of the oil mist measuring device of this embodiment is the same as that in Embodiment 1 except for the introduction chamber. Therefore, only the introduction chamber according to this embodiment will be described, and the description of other configurations will be omitted.

[0033] FIG. 6(a) is a conceptual diagram showing the oil mist measuring device of this embodiment, and FIG. 6(b) is a conceptual diagram showing a cross section of the introduction chamber. As shown in FIG. 6(a), a through hole 602 is formed in the side peripheral surface of the introduction chamber 601 of the oil mist measuring device 600.

[0034] Also, as shown in FIG. 6(b), the through hole 602 is formed to be inclined at an angle β in the circumferential direction with respect to the normal direction 60 of the side peripheral surface of the introduction chamber 601. Further, similar to Embodiment 1, the side peripheral surface of the introduction chamber 601 is formed of a single plate at least at the location where the through hole 602 is disposed. By forming the through hole in this manner, the same excellent effects as the through hole in the oil mist measuring device of Embodiment 1 can be achieved. In addition, although a square tube-shaped introduction chamber is shown in this embodiment, the introduction chamber may be a polygonal tube shape such as a triangular tube shape or a pentagonal tube shape. <Effect>

[0035] As described above, the oil mist measuring device of this embodiment can prevent droplet-shaped oil from entering the introduction chamber and maintain cleanliness, and can provide an oil mist measuring device in which the introduction of oil mist is not inhibited due to the blockage of the through hole.

Description of Reference Numerals

[0036] 100: Oil mist measuring device 101: Introduction chamber 102: Cylindrical member 103: Case 104: Through hole 105: Observation window 106: Irradiation unit 107: Light receiving unit 108: Discharge hole 109: Substrate 110: Oil mist

Claims

1. A cylindrical introduction chamber having through holes for introducing oil mist drilled evenly in the circumferential direction on the side circumferential surface, an irradiation unit that irradiates light into the chamber of the introduction chamber through an observation window provided in the introduction chamber, a light receiving unit that receives the light reflected or scattered by the oil mist in the introduction chamber when the light irradiated by the irradiation unit, and outputs a value corresponding to the received light amount through the observation window, and a measurement unit that measures the oil mist based on the output value by the light receiving unit. The oil mist measuring device is characterized in that the through holes are drilled obliquely in the circumferential direction with respect to the normal direction of the side circumferential surface of the introduction chamber, and the opening shape is a rectangle with the longitudinal direction of the introduction chamber as the long side direction.

2. The oil mist measuring device according to claim 1, wherein the cylindrical introduction chamber is a cylindrical introduction chamber.

3. The oil mist measuring device according to claim 1, wherein the cylindrical introduction chamber is a polygonal cylindrical introduction chamber.

4. The oil mist measuring device according to any one of claims 1 to 3, wherein the side circumferential surface of the introduction chamber is formed of a single plate at least at the location where the through holes are arranged.

5. When the length of the long side of the rectangle, which is the opening shape of the through hole, is "L", the length of the short side is "S", and the plate thickness of the side circumferential surface is "t", the oil mist measuring device according to any one of claims 1 to 4, wherein each value is within the following ranges. Plate thickness: 0.5 ≤ t ≤ 1.5 mm, short side: 1.5 ≤ S ≤ 2.5 mm, long side: 3 ≤ L ≤ 150 mm

6. When the length of the long side of the rectangle, which is the opening shape of the through hole, is "L", the length of the short side is "S", and the plate thickness of the side circumferential surface is "t", the oil mist measuring device according to any one of claims 1 to 4, wherein each value is within the following ranges. Plate thickness: 1.5 ≤ t ≤ 10 mm, short side: 2.5 ≤ S ≤ 5 mm, long side: 4 ≤ L ≤ 150 mm

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