JPS6154416A - Flame light detecting device - Google Patents

Abstract

PURPOSE:To improve heat resistance and airtightness with compact constitution by forming a photoconductor of a quartz optical fiber and a many-component optical fiber covered with a metallic pipe, and projecting the input terminal of the quartz optical fiber from a casing to a combustion chamber side. CONSTITUTION:A detector which detects the combustion flame light in the combustion chamber is equipped with a flame light guide-in part 3 having a screw casing 1 and at least one photoconductor 2 which is arranged in the screw casing 1 and transmits the incident frame light, a casing optical fiber 4 which is connected to the photoconductor 2 and arranged outside the screw casing 1, and a flame light detection part 6 having a photoelectric conversion part 5 which is connected to the casing optical fiber 4 and converts the incident transmitted flame light photoelectrically. The photoconductor 2 is formed of the quartz optical fiber 2a which has outer periphery covered with a metallic pipe 8 and the core 2c and clad 3d made of quartz and the many-component optical fiber 2b connected to the output terminal of the quartz optical fiber 2, and the input terminal of the quartz optical fiber 2a is projected from the casing 1 to the combustion chamber side.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a flame light detection device.

[Background of the invention]

In order to maintain optimal combustion in boilers, kerosene stoves, spark ignition type or compression ignition type internal combustion engines, etc., it is necessary to optimally control combustion temperature, pressure, air-fuel ratio, ignition timing, injection timing, etc. First, in terms of output and economy, it is advantageous for internal combustion engines to operate near the limit where knocking does not occur.

Many studies have been published to date on detecting any of these parameters for closed-loop control, and in particular, flame light detection devices have been proposed for detecting the physical process of combustion using combustion flame light. .

For example, JP-A-57-108734 and JP-A-57-
In No. 108735, a quartz glass trap is placed on the side of the combustion chamber in the screw casing, and an optical fiber is arranged on the other end side to detect flame light. In such a case, in order to sufficiently guide the flame light to the optical fiber, it is necessary to have a large cross section of the quartz glass rod, which increases the cost and makes it difficult to make the device compact. In addition, since the metal part and the quartz glass part are placed in close contact with each other in the high temperature part on the combustion chamber side,
The thermal expansion coefficients of the two are significantly different, which is not preferable from the viewpoint of heat resistance.

Furthermore, Japanese Patent Laid-Open No. 57-163842 proposes a device in which a center electrode is inserted into the axial center of the quartz glass rod of the above-mentioned detection device, and the threaded coupling portion is used as a ground electrode to function as a spark plug. However, this device also has the same structure of the flame introduction section as the above-mentioned one, and has the same drawbacks as the above-mentioned one.

[Purpose of the invention]

The present invention has been made in view of the above points, and it is an object of the present invention to provide a flame light detection device having a flame light introduction section that is compact and capable of improving heat resistance and airtightness.

[Summary of the invention]

That is, the present invention provides a device for detecting combustion flame light in a combustion mold, comprising a screw casing and a flame light introducing section disposed within the screw casing and having at least one light guide through which the flame light enters and propagates; connected to the light guide;
and a screw casing external optical fiber disposed outside the screw casing, and a flame light detection section connected to this optical fiber and having a photoelectric conversion section that photoelectrically converts the incident and propagated flame light. In this method, the optical guide is formed of a silica-based optical fiber whose outer periphery is covered with a metal pipe and whose core and cladding are quartz, and a multi-component optical fiber connected to the output end of the silica-based optical fiber. In addition, the input end of the silica-based optical fiber is made to protrude from the screw casing toward the combustion chamber, so that the light guide is composed of a quartz-based optical fiber covered with a metal pipe and a multicomponent. The input end of the silica optical fiber is made to protrude from the screw casing toward the combustion chamber.

[Embodiments of the invention]

The present invention will be explained below based on the illustrated embodiments. An embodiment of the present invention is shown in FIGS. 1-6.

Of these, as shown in FIG.
and a flame light introduction part 3 disposed inside the screw casing 1 and having at least one light guide 2 through which flame light enters and propagates; a flame light detection unit 6 having a screw casing external optical fiber 4 and a photoelectric conversion unit 5 connected to the optical fiber 4 and photoelectrically converting incident and propagated flame light;
It is equipped with In the figure, 5a and 5b constitute the photoelectric conversion section 5, 58 is a photoelectric conversion element, 5b is a signal processing circuit, and 7 is a connector. In this embodiment of the flame light detection device configured as described above, as shown in FIGS. 2 to 4, the light guide 2 is covered with a metal pipe 8 on its outer periphery, and is covered with a core 2C and a cladding. 2
A quartz-based optical fiber 2a in which d is quartz, and a multi-component optical fiber 2b connected to the output end of this silica-based optical fiber 2a.
At the same time, the input end of the silica-based optical fiber 2a was made to protrude from the screw casing 1 toward the combustion chamber side. By doing so, the light guide 2 is formed of a quartz optical fiber 2a covered with a metal pipe 8 and a multi-component optical fiber 2b, and the input end of the quartz optical fiber 2a is connected to a 7-strip casing l. 7 can be obtained by obtaining a flame light detection device having a flame introduction portion 3 which is compact and has improved heat resistance and airtightness by projecting toward the combustion chamber side.

The screw, that is, the casing l is the hexagonal nut part 1 for tightening.
a. Thread ml for installation in the combustion chamber b. Screw caning Threaded part IC for connecting connector to connect external optical fiber 4
It is composed of Inside this screw casing l, a silica-based optical fiber 2a (about 1 mm diameter) is arranged on its central axis, and its outer periphery is made of a metal with relatively low thermal expansion (for example, an alloy of F, N+ mixed with C0). ) pipe 8
However, the outer periphery is further covered with an insulator 9 having excellent heat resistance such as ceramics. The input end of this silica-based optical fiber 2a opens into the combustion chamber, and the output end of the other end is connected to the multi-component optical fiber 2b via the joining metal body 10.
It was joined with By doing this, the flame light introducing section 3
can be made compact, heat resistant, and airtight, which will be described next.

Particular attention should be paid to the flame light introduction section 3 of this type of flame light detection device to prevent the pressure inside the combustion chamber from leaking, that is, to ensure high airtightness.

In a spark ignition engine, it is 10 to 20 Ky during combustion.
/ cM, 100 to 150 Kp for compression ignition engines
This is because the pressure is as high as / crA. It is also necessary to prevent thermal breakdown in an atmosphere with a sharp temperature gradient between the high temperature atmosphere inside the combustion chamber and the outside air (low temperature).

The gas temperature during combustion is instantaneously between 2000 and 250.
This is because the temperature is as high as 0 Ca degrees. Therefore, it is necessary to use a material with a sufficiently high melting point for the parts that come into contact with the combustion gas.

The melting point of quartz glass is 1760C, and the melting point of ceramics is about 2000C, but the temperature distribution of conventional general spark plugs is about 500 to 700 tll' at the center electrode and about 250 to 350C at the ground electrode, so its heat capacity is Due to their heat dissipation properties, quartz glass and ceramics can withstand temperatures below 700C. The reason for mentioning the spark plug is that it is preferable for the flame light introduction part 3 of the flame light detection device to be built into the spark plug and installed in the combustion chamber of the engine because it is the easiest product to manufacture and from the standpoint of compactness. This is because it is 5 times.

First, ensuring airtightness will be explained. Figure 2.

As shown in FIGS. 4 and 6, the screw casing 1 and the ceramic insulator 9 are welded with metals (M, -M,) at the joint A on the outer periphery of the insulator 9. (Metallization) This part and the inner peripheral surface of the screw casing 1 are joined by silver brazing. The metal pipe 8 and the insulator 9 are joined by metallizing the joint part B on the inner circumferential surface of the insulator 9, and silver brazing this part to the metal pipe 8. Since it is difficult to directly join the silica-based optical fiber 2a and the metal pipe 8, this was done through a joining metal body IO. That is, the joining metal body 10 and the metal pipe 8 are silver-brazed at the illustrated joint C, and the multi-component optical fiber 2b provided at the other end of the joining metal body 10 is connected to the joining metal body 10 as shown in the figure. The joint is sealed with glass. The rear end 2e of the silica-based optical fiber 2a is made as large as the outer diameter of the metal pipe 8 to prevent it from coming off in the X direction. By doing so, the combustion chamber and the atmosphere are sufficiently closed off, and high airtightness of the flame light passenger section 3 can be ensured. That is, the gas and combustion pressure flowing between the silica-based optical fiber 2a and the metal pipe 8 are cut off at the junctions C and D.

Next, with regard to ensuring heat resistance, we not only used heat resistant materials as described above, but also took measures as described below. A joint part A between the screw casing l and the insulator 9, a joint part B between the insulator 9 and the metal pipe 8 are formed locally as shown in the figure, and a joint part A between the screw casing l and the insulator 9 and a joint part B between the insulator 9 and the metal pipe 8 are formed between the casing 1, the insulator 9 and the metal pipe 8. A slight gap was provided except for joints A and B. As a result, both the axial and radial directions of each member become free ends, and elongation due to differences in thermal expansion of each member can be released.For compactness, the input end of the silica optical fiber 2a is shown in Fig. 4. As shown in Figure 2, the quartz glass rod protrudes toward the combustion chamber side, and the quartz fiber 2a and the multi-component optical fiber are designed to allow the flame light to enter and propagate sufficiently. This eliminates the need for a large cross-sectional area, making it possible to make it more compact. In other words, in the quartz-based optical fiber 2a, both the core 2C and the cladding 2d are made of quartz. However, the cladding 2d has been subjected to some additional cutting so that the refractive index n2 of the cladding 2d part is nl compared to the refractive index n1 of the core 20 part. So that it is n2 (715 completed)
, the diameter ratio is approximately +1·I, such as approximately 9/lO. In order to enlarge the field of view, it is desirable to form a wide-angle lens at the input end (opening end) of this silica-based optical fiber 2a on the burning side with a predetermined radius hole as shown in the figure. . However, depending on the workability, the object to be measured, etc., various shapes can be arbitrarily selected as shown in FIG.

The shape shown in (a) in the figure is the easiest to process, and the metal pipe 8 and the quartz optical fiber 2a are cut at the same cross section. Therefore, its field of view is the smallest among those shown in FIG. 5, making it suitable for introducing and propagating localized flame light. In the same figure (b), a quartz optical fiber 2a is connected to a metal vibrator 8.
It protrudes slightly more, and the end face is cut into a square shape. The field of view is almost the same as in (a), but by peeling off the cladding 2d at the protruding part in (b), the cladding 2d and the metal pipe 8 are placed on the same surface as shown in (C). Then, the field of view will be greatly improved compared to that in (b). The end face of the quartz non-optic fiber 2a is formed into a hemispherical shape in FIG. 2(d), and into a conical shape in FIG.

FIG. 6 shows the condensing state of the light guide 2, and as also shown in the figure, the multi-component optical fiber 2b is
A lens function is provided to condense the flame light Q shown by the arrow in the figure between the distance from Xl to Xl. By doing this, the optical fiber outside the screw casing at the rear end of the multi-component optical fiber 2b is converted into a general communication optical fiber cable 4, as shown in FIG.
a (φ50 to φ125 μm) can be used to construct a flame light detection device that transmits and detects strong flame light using this optical fiber cable 4a. In other words, as shown in FIG. 1, the optical fiber cable 4a performs photoelectric conversion in a location separated from the harsh electrical, thermal, and mechanical environments around the combustion chamber, but in the internal combustion engine. In this case, the combustion flame light from one cylinder or each cylinder is transmitted to the optical fibers 4b, 4c, 4 of the optical fiber cable 4a.
d.

The light is collected into a bundle at 4e and converted into an electric quantity by a photoelectric conversion element 5a (for example, a phototransistor, a photodiode, or a PIN photodiode) connected to this end.

The output signal of the photoelectric conversion element 5a is sent to the signal processing circuit 5b, where necessary signal processing is performed and the target detection parameter is output. Therefore, by configuring the flame light detection device in this way, it is possible to not only obtain the flame light introduction section 3 which is compact and has improved heat resistance and airtightness as described above, but also solves problems in spark ignition engines. It is possible to detect flame signals that are free from the effects of electromagnetic noise, mechanical vibration noise, etc. that occur in general internal combustion engines.

Other embodiments of the invention are shown in FIGS. 7-9. In this embodiment, the flame light detection device is constructed by using a band fiber 4f as the optical fiber 4 outside the screw casing. In this way, a plurality of photoelectric conversion elements 5
al, 5a2, and multiple pieces of information can be detected simultaneously compared to the case described above. That is, a multi-component optical fiber 2b' having a core 2c/ and a cladding 2d/ is
The parallel light of the flame light Q incident on l is made to be parallel light when it exits on Xl, and the rear end of the multi-component optical fiber 2b' having such a function is connected to the handle fiber 4f.
It was composed of The handle fiber 4f has a large number of optical fibers 4g bundled together and housed inside the jacket 11. This handle fiber 4f is connected to the multi-component optical fiber 2b via the connector 7a provided in the flame light introducing section 3.
Connect to /. Then, the bundled optical fibers 4g of the handle fiber 4f are separated into several pieces at a branch part 12.
By forming a branched optical fiber and coupling it with a plurality of photoelectric conversion elements 5al and 5a2 having different detection characteristics, a plurality of pieces of information can be detected simultaneously. In this case, the flame light detection section 6 is configured to perform photoelectric conversion at a position away from the combustion chamber, as in the case described above. Further, as in the case described above, the optical fiber cables of each cylinder can be guided to the respective photoelectric conversion elements 5a1 and 5a2 for signal processing.

Still other embodiments of the present invention are shown in FIG. 1θ and FIG. 11. In this embodiment, the flame light introduction part 3a of the flame light detection device is integrated with the spark plug (one piece is formed.By doing so, the flame light introduction part 3a is formed integrally with the spark plug. So, in the case mentioned above) is it also necessary to attach the flame light introduction part 3a to the combustion chamber? It can be easily done. The basic configuration of the flame light civilian section 3a in this case is almost the same as that described above. That is, the multicomponent optical fiber 2b is connected to the joining metal body 10 at the output end of the silica optical fiber 2a.
The input end of the silica-based optical fiber 2a is made to protrude toward the combustion chamber side.

A metal pipe provided around the outer periphery of the silica optical fiber 2a is used as the center electrode 8a, and a screw casing is used as the ground electrode 13. Therefore, in order to position the ground electrode 13 part and the center electrode 8a part with a predetermined gap, the electrode part P at the tip of the ground electrode 13 is bent toward the center electrode 8a side as shown in the figure. The ground electrode 13, the center electrode 8a, and the quartz optical fiber 2a, which are connected and covered by a screw casing, are connected through an insulator 9 made of heat-resistant ceramics with excellent electrical insulation properties (preferably properties similar to those of a spark plug insulator). These insulators 9 and ground electrodes 13
The joining between the center electrode 8a and the silica optical fiber 2a was carried out in the same manner as in the above case. That is, the insulator 9 and the ground electrode 13 are metallized and silver soldered at the joint E, the center electrode 8a and the insulator 9 are metalized and silver soldered at the joint F, and the quartz-based optical fiber 2a and the center electrode 8 are
a is silver-brazed at the joint G at one end of the metal body 10 for bonding, and is connected to the multi-component optical fiber 2b and the metal body lO for bonding.
It was joined by glass sealing the other end at the joining part H. The multi-component optical fiber 2b was made to pass through the inside of the auxiliary insulator 9a made of heat-resistant ceramics, and a connector 7b for connecting the optical fiber was provided at the end thereof. The auxiliary insulator 9a and the insulator 9 were metallized at the joint part (2) and then silver-brazed.

By doing so, the space between the combustion chamber and the atmosphere can be sufficiently closed as in the case described above, and a high airtightness of the flame light introducing section 3a can be ensured. Further, an electric signal from the power distributor is guided to the joining metal body IO via a high voltage terminal 14 formed to protrude from a part of the insulator 9, a leaf spring 15, and further guided to the center electrode 8a. Note that optical fibers such as the quartz optical fiber 2a and the multi-component optical fiber 2b have excellent electrical insulation properties, so
In this way, even if it is in close proximity to a conductive path with a high voltage of several tens of kV, it will not be affected electrically. Furthermore, the flame light detecting section provided in connection with this flame light introducing section 3a may be selected from any of the above-mentioned ones.

In addition to the shapes shown in the same figure, various shapes can be selected for the electrode portion P of the spark plug, as shown in FIGS. 11(a), (b), and (C). I did it like that. In the figure (a), the ground electrode 13 is extended up to the tip of the center electrode 8a to form an electrode part P, and a spark discharge between the center electrode 8a and the ground electrode 13 is used to connect the silica-based optical fiber 2a. The dust attached to the input end of the filter is burnt to promote the cleaning effect. In FIG. 5B, a plurality of ground electrodes 13 are installed with respect to the center electrode 8a to form an electrode portion P, thereby avoiding the directionality of spark discharge. Figure (C) considers the positional relationship between the center electrode 8a and the ground electrode 13, combines the advantages of Figures (a) and (b), and combines the cleaning effect of spark discharge and the directionality of the plurality of ground electrodes 13. This is an attempt to avoid sex at the same time. By forming these electrode portions P as shown in FIGS. 12A and 21C, it is possible to eliminate the problem of damage to the silica-based optical fiber 2a during engine installation work. As is clear from the figure, this is because the silica-based optical fiber 2a is covered with the ground electrode 13.

FIG. 12 shows yet another embodiment of the invention. In this embodiment, a flame light introduction section 3b of a flame light detection device is integrated into a commercially available general spark plug. By doing this, the flame light introduction part 3b can be formed integrally with a commercially available spark plug, making it easier to attach the flame light introduction part 3b to the combustion chamber than in the case described above. It can be done.

In other words, although the flame light introduction part 3b is constructed using the threaded casing 16 of the spark plug as a threaded casing, the scrap metal pipe 8 of the quartz-based optical fiber 2a inserted into the 5th part of the threaded casing 16 and the threaded casing 16 are not easily soldered together. Join well. The input side of the silica-based optical fiber 2a is made to protrude toward the combustion chamber side, and the other end, the output end I (as shown in the figure, has a stepped shape to prevent it from coming off in the X direction in the figure). /.That is, this output end is treated so that it is perpendicular to the Y direction indicated by the arrow in the figure, and the first multi-component optical fiber 2bt (a quartz-based original fiber may also be used) is inserted here. Then, this first multi-component fiber 2b
The flame light incident at 1 is transmitted as parallel light. Next, the second multi-component optical fiber 21) 2 connected to the first multi-component optical fiber 2b is constructed as a lens with a light condensing function, and the output end 17 has a diameter of φ50 to φ20.
Focus the light at 0 μm and 8 degrees. A normal source fiber 18 used for communications, etc. having a core diameter of about 50 to 200 μm was connected to the output end 17 to form the flame light introduction section 3b. Connector 19 connected to this optical fiber 18
The light 7 Aiba cable 4a has a cushioning material 2 such as rubber.
The screw casing 16 is connected to the screw casing 16 through 0.

In this case, leakage of gas and pressure from the gap between the silica optical fiber 2a and the metal pipe 8 is prevented by sealing the joint between the first multi-component optical fiber 2b and the screw casing 16 with glass. In particular, this can be easily prevented, and the flame light introduction section 3
The airtightness of b can be maintained.

〔Effect of the invention〕

As described above, the present invention provides a flame light detection device having a flame light introduction part that is compact and has improved heat resistance and airtightness. can be obtained.

Of the drawing? 1j Simple Explanation FIG. 1 is a longitudinal sectional side view of the main parts of an embodiment of the flame light detection device of the present invention, FIG. 2 is a longitudinal sectional side view of the flame light introducing section of the same embodiment, and FIG. P in FIG. 2 is a view taken in the direction of arrows; FIG. 4 is an enlarged longitudinal cross-sectional side view of the quartz optical fiber portion of the flame light introducing section of one embodiment; FIGS. 5 (a), (b), (
C), (d)t (e) are longitudinal sectional side views showing different shapes of the input ends of the silica optical fiber of one embodiment, and FIG. 6 is the same. FIG. 7 is an explanatory view showing the state, and FIG.
The figure is an explanatory diagram showing the state of convergence by the multi-component light 7 eyeball of another embodiment, FIG. 9 is a cross-sectional view of the handle fiber of another embodiment, and FIG. 10 is a flame light detection according to the present invention. FIGS. 11(a), (b), and (C) are longitudinal sectional side views of the flame light introduction part of still another embodiment of the device, and respectively show the electrode parts of the center electrode and the ground electrode of the further embodiment of the device. FIG. 12 is a vertical side view of a flame light introducing section of still another embodiment of the flame light detection device of the present invention.

1... Screw casing, 2... Light guide, 2a...
Silica optical fiber, 2b, 2b'...Multi-component optical fiber, 2I)! ...first multi-component optical fiber, 2b
2...Second multi-component optical fiber, 2C, 2C'...
・Core, 2d, 2d'--Clad, 3, 3a, 3b
-Flame light introduction part, 4... Optical fiber outside the screw casing, 4a---Optical fiber cable, 4b, 4C, 4(i
.

4e... Optical 7 fiber, 4f... Bundle core ino (, 4g... Optical fiber, 5... Photoelectric conversion unit, 5a
, 5al.

5a2... Photoelectric conversion element, 5b... Signal processing circuit,
6...Flame light detection unit, 7, 7a, 7b...Connector, 8...Metal pipe, 8a...Center'FiL pole (metal tube), 9...Insulator, 9a... - Auxiliary insulator, 10... Metal body for joining, 11... Outer cover, 13
...Ground electrode (screw casing), 14...High voltage terminal, 16...Screw casing, 18...Optical fiber, 20...Buffer material.

Claims (1)

[Claims] 1. A device for detecting combustion flame light in a combustion chamber includes a screw casing and a flame light introducing section disposed within the screw casing and having at least one light guide through which the flame light enters and propagates. and a flame having a screw casing external optical fiber connected to the light guide and disposed outside the screw casing, and a photoelectric conversion unit connected to the optical fiber and photoelectrically converting the incident and propagated flame light. The light guide includes a quartz-based optical fiber whose outer periphery is covered with a metal pipe and whose core and cladding are quartz, and a multi-layer optical fiber connected to the output end of the silica-based optical fiber. In addition to forming the component optical fiber,
A flame light detection device characterized in that an input end of the quartz-based optical fiber protrudes from the screw casing toward the combustion chamber. 2. Flame light detection according to claim 1, wherein the flame light introduction part is configured to have the function of a spark plug with the metal pipe as a center electrode and the screw casing as a ground electrode. Device. 3. The flame light detection device according to claim 1, wherein the threaded casing is formed of a threaded casing of a general spark plug. 4. The flame light detection device according to claim 1, wherein the flame light detection device is formed of an optical fiber outside the screw casing, an optical fiber cable, or a handle fiber.