JPH05149190A - Combustion measuring device for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a combustion measuring device for an internal combustion engine wherein behavior of a plurality of kinds of radicals in terminal gas in a combustion chamber is simultaneously measured by a spectral method. CONSTITUTION:A combustion measuring device for an internal combustion engine comprises comparison light sources 7 and 8, an optical system by which light passing through the combustion chamber 6 of an internal combustion chamber 1 is guided, a spectral device 15 wherein light guided to the optical system is dispersed and a detector 25 to simultaneously detect wavelengths corresponding to three kinds of respective radicals in combustion gas, an analyzing processing device 30 wherein emission and/or absorption of light having a wavelength corresponding to a radial is effected based on an output from the detector 25, and a display device 31 to display an analyzed result in a waveform according to an output from the analyzing processing device 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion measuring device for an internal combustion engine such as gasoline for examining abnormal combustion such as knocking.

[0002]

2. Description of the Related Art In an internal combustion engine such as a gasoline or diesel engine, suppression of knocking is an unavoidable technical problem in achieving improvement of thermal efficiency and output. Knocking of this internal combustion engine, in particular fireworks ignition engine, is a phenomenon known from the beginning of the appearance of the internal combustion engine, and in the course of various attempts to develop and improve the internal combustion engine,
It has been the subject of many studies. The occurrence of knocking is influenced by the chemical and physical properties of the air-fuel mixture and the ambient conditions. Further, for example, in a gasoline engine, it is known that the unburned gas in front of the combustion flame surface undergoes adiabatic compression to cause spontaneous ignition from the point of the best conditions for ignition. The point at which such an explosive spontaneous ignition occurs is at the end of combustion, just opposite the plug. When ignition occurs, most of the unburned gas is almost in front of the ignition, so if you ignite at one point, the remaining unburned gas also enters the ignition state almost at the same time, just like the combustion in the diesel engine. It is said that almost the same phenomenon will occur. Recently, much research has been conducted on the processes from the preflame reaction in the end gas of the combustion chamber to the self-ignition.

In the studies so far, radicals such as OH, CH, and C ₂ play an important role in the reaction mechanism from the preflame reaction of the terminal gas to the self-ignition and the knocking oscillation. I know.

[0004]

However, until now, no suitable device has been developed as a device for measuring the behavior of radicals during the operation of an internal combustion engine. The fact is that only one radical could be measured. Therefore, it was not possible to understand the behavior of various radicals in total through the combustion process. Therefore, an object of the present invention is to provide a combustion measuring apparatus for an internal combustion engine, which solves the problems of the above-mentioned conventional technology and can simultaneously measure the behavior of several kinds of radicals in the end gas of the combustion chamber by spectroscopy. ..

[0005]

In order to achieve the above object, the present invention provides a comparative light source, an optical system for guiding light passing through a combustion chamber of an internal combustion engine, and a light for dispersing the light guided to the optical system. And a spectroscopic device having detectors for simultaneously detecting wavelengths respectively corresponding to two types of radicals in the combustion gas, and based on the output of the detector, emission of light at a wavelength corresponding to the radicals and / or It is characterized by comprising an analysis processing device for analyzing absorption, and a display device for displaying the analysis result in a waveform according to the output of the analysis processing device.

[0006]

According to the present invention, the emission / absorption of light having wavelengths corresponding to the three types of radicals in the end gas in the combustion chamber are simultaneously measured, and the results are displayed as a waveform. It becomes possible to understand the radical behavior that plays an important role in the mechanism.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a combustion measuring device for an internal combustion engine according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing the configuration of the entire system of a combustion measuring apparatus for an internal combustion engine according to this embodiment. In FIG. 1, reference numeral 1 is a gasoline engine as a test engine, reference numeral 2 is a dynamometer, reference numeral 3 is a flywheel, reference numeral 4 is a fuel tank, and reference numeral 5 is a surge tank. The combustion measuring apparatus of the present invention is provided with the following optical system in order to measure the behavior of radicals in the end gas portion of the combustion chamber 6 of the gasoline engine 1 by the absorption method and the light emission method. The xenon lamp 7 and the halogen lamp 8 are comparative light sources, and either of them can be selected. The light passing through the combustion chamber 6 is condensed by the condenser lens 9, and the light path thereafter is divided into two. The first one passes through the D-line interference filter 10 and is photoelectrically converted by the photomultiplier tube 11, and then the amplifier 1
2 is an optical system (hereinafter referred to as an optical system I) that is given to the data recorder 13 as an output signal amplified by 2, and the other is that the light that has passed through the combustion chamber 6 is introduced into the spectroscopic device 15 via the optical fiber 14. Optical system (hereinafter referred to as optical system II). Either of these optical systems I and II can be switched via a mirror.

Next, FIG. 2 schematically shows the structure of the spectroscopic device 15 which constitutes the optical system II. That is, in FIG. 2, reference numerals 17, 18, 19, 20 denote reflecting mirrors, and the light guided into the spectroscopic device 15 by these reflecting mirrors 17, 18, 19, 20 is dispersed by the diffraction grating 21, The light enters the mirror 23 for switching the optical path via the reflecting mirror 22. This optical path switching mirror 23 is
It is rotatably supported, and the light dispersed by the diffraction grating 21 can be switched to either side of the first detector 24 or the second detector 25 according to its position. ing. In this case, the first detector 24 comprises a set of photomultiplier tubes and an amplifier. In contrast, the second
The detector 25 is composed of four sets of photomultiplier tubes and amplifiers, and the optical fiber 2 for guiding light to the photomultiplier tubes.
The incident end 6 is arranged at a position corresponding to the wavelength of light to be detected. Reference numeral 27 indicates a wavelength adjusting handle, which is operated to operate the diffraction grating 2
The wavelength of the light to be detected is adjusted by changing the angle of 1.

The output of the first detector 24 or the second detector 25 as described above is introduced into the data recorder 13 of 9 channels in FIG. 1, and the data collected by the data recorder 13 is used by a computer. Is input to the analyzed processing device 30. The analysis processing device 30 gives the result of the analysis process to a display device 31 such as an XY plotter. As a result, the analysis result is displayed on the display device 31 as an image having a waveform as shown in FIGS. Reference numeral 32 indicates a digital memory.

In addition to the measurement of light emission or absorption intensity of the end gas portion in the combustion chamber 6, the pressure in the cylinder of the gasoline engine 1 and the crank angle are also measured. in this case,
The pressure in the cylinder is detected by a pressure transducer 33 provided on the cylinder head, and the output of this pressure transducer 33 is supplied to the data recorder 13. Further, the knock intensity is measured using the high frequency band filter 34. The crank angle is detected by the crank angle detector 36 via the shutter 35, and the output of the crank angle detector 36 is introduced into the data recorder 13.

The combustion measuring apparatus for an internal combustion engine according to this embodiment is basically constructed as described above,
Next, measurement using this measuring device will be described. Table 1 shows the specifications of the gasoline engine 1 which is the test engine. In this gasoline engine 1, two observation window holders 3 provided at the end of the combustion chamber 6 as shown in FIG.
Three kinds of radicals in the terminal gas portion between 8 and 38,
That is, OH (306.4 nm), CH (431.5)
nm) and the behavior of C ₂ (516.5 nm) are measured by a light emission method and an absorption method.

[0012]

[Table 1] In measurement, three types of fuel with different octane numbers, N-heptane (octane number; 0), Iso-oc
tane (octane number; 100), Gasoline (octane number;
91) is used as a fuel, and the behavior of the emission intensity of the above-mentioned three types of radicals in normal combustion and abnormal combustion is measured at the same time corresponding to the combustion gas temperature (in the case of the emission method) and the cylinder pressure. In this case, it is possible to reduce the amount of cooling air to the cylinder head of the gasoline engine 1 to gradually change from the normal state to the overheated state, and shift from the normal combustion to the abnormal combustion.

Therefore, in FIG. 1, when the temperature of the combustion gas is first measured, a halogen lamp 8 is used as a comparative light source.
Using the spectrum D line inversion method, the luminance of the halogen lamp 8 is changed with respect to the output waveform of the radiant energy from the combustion chamber 6, and the temperature is calibrated to measure the combustion gas temperature. Next, in the case of simultaneously measuring the emission intensity of OH, CH, and C ₂ radicals by the light emission method, the operating conditions (intake pressure, mixing ratio) of the gasoline engine 1 are set, and then the temperature scale is adjusted. , D-line interference filter (58
Instead of 9.3 nm), the optical system II is switched to and the light from the combustion chamber 6 is guided to the spectroscopic device 15 via the optical fiber 14 to measure the change in emission intensity. In this case, in FIG. 2, in the spectroscopic device 15, the mirror 23 is provided on the side of the second detector 25 including four photomultiplier tubes and amplifiers in order to perform simultaneous measurement of the above three types of radicals. Switch it. The incident ends of the optical fiber 26 are OH (306.4 nm) and CH (431.5n).
_m), wavelengths corresponding to the respective radicals of C 2 (516.5nm), and used in a combustion gas measurement Na-D line (58
It is set in advance at a position for detecting a wavelength of 9.3 nm).

When the absorption intensity is simultaneously measured for each radical of OH, CH and C ₂ by the absorption method,
A xenon lamp 7 is used as a comparative light source. The gasoline engine 1 is operated with the xenon lamp 7 lit at a constant brightness. The light from the combustion chamber 6 is switched to the optical system II and guided to the spectroscopic device 15 via the optical fiber 14 to measure the change in the degree of light absorption. At this time, the combustion gas temperature is not measured.

FIGS. 4 to 9 show examples of the light emission and absorption of the end gas portion in the combustion chamber 6 measured with the fuels having different octane numbers as described above. 4 to 7 are examples of measurement of normal combustion. Of these, Fig. 4 shows N-heptane and Fig. 5
Is Iso-octane, and FIG. 6 is a measurement example for Gasoline. 4 to 6 show one cycle of absorption and one of emission.
The result of the cycle is shown. Three types of OH, CH, C
The behavior of each radical of ₂ is absorption at the top and emission at the bottom. FIG. 7 shows the results of one cycle of absorption in Iso-octane and one cycle of absorption in the mixed fuel. 8 and 9 are examples of measurement of abnormal combustion when N-heptane is used as the fuel. FIG. 8 shows a display method similar to that shown in FIGS.
FIG. 9 is an enlarged display of the absorption waveform in FIG. In each of the above figures, knock vibration (pressure amplitude), cylinder internal pressure, behavior of OH, CH, C ₂ radicals, combustion gas temperature (in the case of light emission method) and crank angle are shown from the top. Further, in each of the above figures, point B is the point at which the preflame reaction is considered to have started, point A is the point at which the flame has reached the end gas portion and combustion has started, and section B-A shows the preflame. The reaction period.

As a result of analyzing the combustion mechanism, the following can be seen from FIGS. 4 to 9.

First, OH, CH, and
Simultaneous measurement of C ₂ radicals reveals that the behavior of these radicals depends on the octane number of the fuel. Further, in the cycle in which abnormal combustion of spark knock occurs, OH, CH, C generated in the preflame reaction of normal combustion
Of the _two radicals, CH, C ₂ in the preflame reaction in the knock region
Radicals rarely appear, while OH radicals gradually increase. After that, it is understood that the radicals rapidly increase due to the occurrence of self-ignition, and the knock oscillation starts immediately before the maximum value is exhibited. Thus, by simultaneously measuring the light of the wavelengths corresponding to the radicals of OH, CH, and C _{2 in} the period from the preflame reaction to the start of knock oscillation, these radicals have different octane numbers, normal combustion and abnormal combustion. It is clarified that and show different behaviors, and it is possible to obtain effective data for analysis of reaction mechanism from pre-flame reaction in end gas to self-ignition.

[0018]

As is apparent from the above description, according to the present invention, light having wavelengths corresponding to three kinds of radicals can be measured by the emission method and the absorption method, and data effective for analysis of combustion mechanism can be obtained. be able to. Therefore, the present invention provides means for contributing to research and development for the purpose of elucidating the mechanism of occurrence of knocking and improving fuel efficiency and thermal efficiency.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the entire system of a combustion measuring apparatus for an internal combustion engine according to the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a spectroscope of the combustion measuring apparatus for an internal combustion engine.

FIG. 3 is an explanatory diagram showing measurement positions in a cylinder head of a gasoline engine.

FIG. 4 is a diagram showing an example of measurement results when normal combustion is performed using N-heptane as a fuel.

FIG. 5 is a diagram showing an example of measurement results when normal combustion is performed using Iso-octane as fuel.

FIG. 6 is a diagram showing an example of measurement results when normal combustion is performed using Gasoline as fuel.

FIG. 7 is a diagram showing an example of measurement results when normal combustion is performed with a mixed fuel of Iso-octane and gasoline.

FIG. 8 is a diagram showing an example of measurement results when abnormal combustion is performed using N-heptane as fuel.

FIG. 9 is an enlarged view of a main part of FIG.

[Explanation of symbols]

 1 Gasoline Engine 2 Dynamometer 3 Flywheel 4 Fuel Tank 6 Combustion Chamber 7 Halogen Lamp 8 Xenon Lamp 14 Optical Fiber 15 Spectroscopic Device 23 Switching Mirror 25 Detector 30 Computing Device 31 Display Device 33 Pressure Transducer 36 Crank Angle Detector

[Procedure amendment]

[Submission date] November 12, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

In order to achieve the above object, the present invention provides a comparative light source, an optical system for guiding light passing through a combustion chamber of an internal combustion engine, and dispersion of the light guided to the optical system. Spectroscopic device having detectors for simultaneously detecting wavelengths corresponding to two or more types of radicals, and analysis processing for analyzing light emission and / or absorption at wavelengths corresponding to the radicals based on the output of the detectors A device,
And a display device for displaying the analysis result in a waveform according to the output of the analysis processing device.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

As is clear from the above description, according to the present invention, light having wavelengths corresponding to two or more types of radicals can be measured by the emission method and the absorption method, and data effective for analyzing the combustion mechanism can be obtained. You can Therefore, the present invention provides means for contributing to research and development for the purpose of elucidating the mechanism of occurrence of knocking and improving fuel efficiency and thermal efficiency.

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

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 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuichi Ikeda 3-9-22 Oka, Asaka City, Saitama Prefecture (72) Inventor Junichi Arai 495-26 Komakidai, Nagareyama City, Chiba Prefecture

Claims (1)

[Claims] 1. A comparative light source, an optical system for guiding light passing through a combustion chamber of an internal combustion engine, a light for guiding the light guided to the optical system, and wavelengths respectively corresponding to three types of radicals in combustion gas. A spectroscopic device having a detector for simultaneously detecting light, an analysis processing device for analyzing light emission and / or absorption of light at a wavelength corresponding to the radical based on the output of the detector, and an analysis device according to the output of the analysis processing device. A combustion measuring device for an internal combustion engine, comprising: a display device for displaying a result in a waveform.