JP2013113183A - Laser-ignition engine, and method for adjusting air-fuel mixture in the laser-ignition engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser-ignition engine, capable of calculating an equivalent ratio at an ignition position in ignition, and a method for adjusting air-fuel mixture, capable of adjusting the mixed state of air-fuel mixture by use of the engine.SOLUTION: The laser-ignition engine includes: an engine body unit including a cylinder in which air-fuel mixture is combusted in a combustion chamber, and a piston which generates power by the combustion of the air-fuel mixture; a laser light emission unit which emits laser light to the air-fuel mixture for igniting the air-fuel mixture in the combustion chamber; an analysis unit which receives the ignition position of the air-fuel mixture and the emitted light in the ignition by use of a laser-induced breakdown spectroscopic method to perform spectroscopic analysis; and an arithmetic unit which calculates, by use of the result of spectroscopic analysis in the analysis unit, the equivalent ratio of the air-fuel mixture at the ignition position of the air-fuel mixture for every ignition. The mixing state of air-fuel mixture is adjusted by a mixing adjustment unit based on information for the calculated equivalent ratio, and new air-fuel mixture adjusted in the mixing state is supplied to the cylinder.

Description

  The present invention relates to a laser ignition engine that ignites an air-fuel mixture for combustion using laser light and a method for adjusting the air-fuel mixture in the engine.

As an ignition device for an internal combustion engine, a laser ignition device for an internal combustion engine using laser light is known. This laser ignition device for an internal combustion engine condenses laser light emitted from a laser oscillator in a combustion chamber of the internal combustion engine by a lens, and activates an air-fuel mixture in the combustion chamber to perform ignition and combustion.
An engine using such an ignition device can be operated under lean fuel conditions and is more efficient than a conventional plug ignition type engine.

For example, there is known a laser ignition device used for an engine capable of reducing emission while efficiently using energy of laser light (Patent Document 1).
The laser ignition device irradiates an air-fuel mixture in a combustion chamber of an internal combustion engine with an ignition laser beam to activate the air-fuel mixture, and irradiates a concentration measurement laser beam into the engine combustion chamber. The concentration measurement laser light irradiation device that measures the concentration of the combustion product generated when the air-fuel mixture burns based on the intensity of the concentration measurement laser light, and the equivalent ratio of the air-fuel mixture based on the concentration of the combustion product A control device to be changed.

JP 2006-242040 A

By the way, in an engine using a laser ignition device for an internal combustion engine, that is, a laser ignition engine, when an attempt is made to expand the above-mentioned lean fuel condition over a wide range compared to the conventional case, the variation in the equivalence ratio at the ignition position increases. It is assumed that engine output becomes unstable. Therefore, it is desired to accurately measure the equivalence ratio of the air-fuel mixture at the ignition position at the time of ignition.
In the above-described laser ignition device, the equivalence ratio of the air-fuel mixture in the combustion chamber is changed according to the measurement result of the concentration of the combustion product generated by the combustion of the air-fuel mixture, and this equivalence ratio is supplied to the combustion chamber. This is the average equivalence ratio of the air-fuel mixture, not the equivalence ratio in the point-like fine region where the laser beam is converged. Further, the above-mentioned laser ignition device cannot calculate the equivalent ratio at the ignition position at the time of ignition from the measurement result of the concentration of the combustion product. For this reason, it is not possible to obtain information on the variation of the equivalence ratio at the time of ignition and at the ignition position for each ignition when the engine is driven.

  Accordingly, the present invention provides a laser ignition engine capable of calculating an equivalence ratio at the ignition position at the time of ignition in a laser ignition engine that ignites a combustion air-fuel mixture using laser light and burns, and uses this engine. It is an object of the present invention to provide a method for adjusting an air-fuel mixture that can adjust the mixed state of the air-fuel mixture.

One embodiment of the present invention is a laser ignition engine that uses a laser beam to ignite and burn a combustion air-fuel mixture. The engine
A cylinder in which an air-fuel mixture burns in a combustion chamber, and an engine body including a piston that generates power by combustion of the air-fuel mixture;
A laser beam irradiation unit for irradiating the mixture with laser light for ignition of the mixture in the combustion chamber;
An analysis unit for performing spectral analysis by receiving the ignition position of the air-fuel mixture and light emission at the time of ignition using laser-induced breakdown spectroscopy;
A calculation unit that calculates an equivalence ratio of the air-fuel mixture at an ignition position of the air-fuel mixture for each ignition using a result of spectral analysis of the analysis unit.

  It is preferable that the laser beam used for ignition of the air-fuel mixture is further used for breakdown of the air-fuel mixture in the laser-induced breakdown spectroscopy.

  The laser light irradiation unit includes a laser light source that emits the laser light, and an optical path that guides the laser light from the laser light source into the cylinder, and the laser is emitted from the cylinder in the middle of the optical path. It is preferable that a branching optical path that branches from the middle of the optical path using an optical element is provided so as to go to the light receiving surface of the analysis unit when the optical path is traced toward the light source.

  The air-fuel mixture is, for example, a gas in which fuel gas and air are mixed. In this case, the calculation unit includes the emission peak intensity of atoms contained in the fuel gas and the air included in the air from the result of the spectroscopic analysis. It is preferable to calculate the ratio of the emission peak intensity of the atoms to be calculated and to calculate the equivalent ratio using this ratio.

  In addition, a mixing adjustment unit that adjusts the mixture state of the mixture based on the calculated equivalence ratio information, and a new mixture whose mixture state is adjusted by the mixture adjustment unit is supplied to the cylinder. It is preferable that

  In that case, it is preferable that the information of the equivalence ratio includes a variation for each ignition by the laser light regarding the equivalence ratio, and the mixing adjustment unit adjusts the mixing state to a mixing state in which the variation is reduced.

Furthermore, another aspect of the present invention is a method for adjusting a mixture in a laser ignition engine that uses a laser beam to ignite a combustion mixture for combustion. The method is
Igniting an air-fuel mixture for combustion in a cylinder of the laser ignition engine using laser light, and driving the laser ignition engine;
Receiving the emission position of the air-fuel mixture and light emission at the time of ignition using laser-induced breakdown spectroscopy, and performing spectroscopic analysis for each ignition by the laser beam;
Calculating the equivalence ratio of the air-fuel mixture at the ignition position of the air-fuel mixture for each ignition using the result of the spectral analysis;
Adjusting the mixture state of the air-fuel mixture based on the calculated equivalence ratio information, and supplying a new air-fuel mixture with the mixed state adjusted to the cylinder.

  At that time, the air-fuel mixture is, for example, a gas in which fuel gas and air are mixed. At this time, the ratio between the emission peak intensity of atoms contained in the fuel gas and the emission peak intensity of atoms contained in the air is calculated from the result of the spectroscopic analysis, and the equivalent ratio is calculated using this ratio. It is preferable to do.

  The information on the equivalence ratio includes a variation for each ignition by the laser beam related to the equivalence ratio, and when adjusting the mixed state of the air-fuel mixture, the mixed state is preferably adjusted so that the variation is reduced. .

  When the above-mentioned laser ignition engine is ignited, the equivalent ratio at the ignition position can be calculated for each ignition. For this reason, the air-fuel mixture can be adjusted efficiently using this engine.

It is a figure which shows the structure of the laser ignition engine of this embodiment. It is the figure which graphed an example of the analysis result for every ignition supplied from the analysis part of the laser ignition engine shown in FIG. FIG. 2 is a diagram showing a relationship between an equivalence ratio calculated by a calculation unit and a flow rate of fuel gas when an air-fuel mixture is burned using the engine shown in FIG. 1. It is a block diagram which shows an example of the mixing adjustment part of the laser ignition engine shown in FIG. It is a figure which shows the structure of the analysis part of another example different from the analysis part of the laser ignition engine shown in FIG.

  Hereinafter, the laser ignition engine of the present invention and the method for adjusting the air-fuel mixture in the laser ignition engine will be described in detail.

FIG. 1 is a diagram showing a configuration of a laser ignition engine (hereinafter referred to as an engine) 10 according to the present embodiment.
The engine 10 supplies an air-fuel mixture obtained by previously mixing air and fuel gas into a combustion chamber of a cylinder, and burns the air-fuel mixture by ignition with a laser beam, thereby driving a piston to generate power. It is. The ignition laser beam used by the engine 10 is simultaneously used for measuring the emission intensity at the time of breakdown of the air-fuel mixture at the ignition position. In the engine 10, the equivalence ratio at the ignition position at the start of ignition generated by breakdown is calculated by performing analysis using spectroscopy. Further, the engine 10 calculates the variation of the equivalence ratio calculated for each ignition, and adjusts the mixture state of the air-fuel mixture supplied into the combustion chamber so that the variation is reduced.

  The engine 10 mainly includes an engine main body 12, a laser beam irradiation unit 14, an analysis unit 16, a calculation unit 18, a mixing adjustment unit 20, and a controller 22.

The engine main body 12 includes a cylinder 12a, a piston 12b, an intake valve 12c, an exhaust valve 12d, and a laser irradiation port 12e.
The cylinder 12a has a combustion chamber in which the air-fuel mixture burns in the combustion chamber, and an air supply valve 12c and an exhaust valve 12d are provided on the wall surface. A mixture obtained by mixing air and fuel gas in a predetermined equivalence ratio by a mixing device in advance is supplied into the combustion chamber in the cylinder 12a through the supply valve 12c, and after combustion, the combustion product is exhausted through the exhaust valve 12d.
The piston 12b is connected to a crankshaft or the like (not shown) and generates power by combustion of the air-fuel mixture. A combustion chamber is defined by the cylinder 12a and the piston 12b.
A laser irradiation port 12e is provided in the upper part of the cylinder 12a, and the laser light for ignition is converged in the combustion chamber through a converging lens 12f provided in the laser irradiation port 12e.

The laser beam irradiation unit 14 irradiates the mixture with laser light to ignite the mixture in the combustion chamber. The laser beam irradiation unit 14 includes a laser light source 14a, a λ / 2 plate 14b, a polarizing plate 14c, a mirror 14d, a beam splitter 14e, a collimator lens 14f, mirrors 14g and 14h, a power meter 14i, and a condenser lens 14j.
The laser light source 14a has input energy that can ignite the air-fuel mixture, and emits laser light that causes the air-fuel mixture to break down. As the laser light source 14a, for example, an Nd: YAG laser having a wavelength of 532 nm and an input energy of several hundred mJ is used.
The λ / 2 plate 14b and the polarizing plate 14c control the output in a state where the output beam profile of the laser light is maintained constant.
The mirrors 14d, 14g, and 14h are disposed so as to reflect the laser beam and guide the laser beam to the laser irradiation port 12e of the cylinder 12a. The mirrors 14d, 14g, and 14h are desired to have resistance to the incidence of laser light and to have high reflection characteristics in a wide band. For example, the mirrors 14d, 14g, and 14h are preferably mirrors having a reflectance of 95% or more in the wavelength range of 350 to 1100 nm, and having a laser resistance of 1 J / cm ² or more. % Or more and a mirror having a laser proof stress of ² J / cm ² or more is more preferable.
The beam splitter 14e is arranged to branch the optical path of the laser beam that travels from the laser light source 14a into the combustion chamber of the cylinder 12a and the light beam emitted from the combustion chamber toward the beam splitter 14e by the breakdown of the air-fuel mixture. . That is, the light passing through the optical path of the laser beam irradiation unit 14 is transmitted from the upper side to the lower side in FIG. 1, and a part of the light is reflected and enters the power meter 14i. On the other hand, the light emitted in the combustion chamber passes through the converging lens 12f in the optical path, is reflected by the mirrors 14h and 14g, passes through the collimating lens 14f, is reflected by the beam splitter 14e, and enters the analysis unit 16. As described above, the optical path of the laser light and the light at the time of breakdown is partially shared, and when the optical path is traced from the cylinder 12a toward the laser light source 14a by using the beam splitter 14e, the light received by the analysis unit 16 is received. A branching optical path that branches from the middle of the optical path of the laser beam is provided so as to face the surface.
The collimating lens 14f makes light parallel light. The condensing lens 14j is provided to condense light on the light receiving surface of the analysis unit 16.
The power meter 14i measures the input energy of the laser beam.

The analysis unit 16 uses a laser-induced breakdown spectroscopy (LIBS) to receive the emission position of the air-fuel mixture and the light emission at the time of ignition for each ignition of the laser beam and perform the spectroscopic analysis. Is provided. Specifically, laser-induced breakdown spectroscopy uses a high-energy laser pulse as an excitation source, converges laser light, excites a component of a measurement object such as an air-fuel mixture into an atomic state, and turns it into plasma, This is a method of analyzing the light emitted by plasma at this time. The air-fuel mixture is ignited by the generation of the plasma. According to the analysis result at the time of breakdown of the air-fuel mixture, in this embodiment, the component of the air-fuel mixture having broken down, that is, the component of the air-fuel mixture at the time of ignition can be known. Can be known.
Although not shown, the analysis device of the analysis unit 16 includes an ICCD camera 16a that receives and captures the separated light, in addition to an optical element such as a slit for dispersing light, a wavelength dispersion element (for example, a prism), or a lens. The ICCD camera 16a picks up the light dispersed for each wavelength band within a certain period after the lapse of a predetermined time from the irradiation of the laser light, and using this image pickup signal, the analysis unit 16 obtains the spectral spectrum at the time of ignition. . The predetermined period after the lapse of the predetermined time is a period determined so that the breakdown of the air-fuel mixture is always caused by the irradiation of the laser beam within the period. The obtained spectral spectrum is supplied to the calculation unit 18 described later.

The calculation unit 18 calculates the equivalence ratio of the air-fuel mixture at the ignition position of the air-fuel mixture for each ignition using the spectral spectrum that is the result of the spectral analysis of the analysis unit 16. Furthermore, in addition to the value of the equivalent ratio itself, the calculation unit 18 obtains the variation of the equivalent ratio at the ignition position at the time of ignition for each laser light ignition as information on the equivalent ratio.
FIG. 2 is a graph showing an example of an analysis result (light emission spectrum distribution) at the time of breakdown (at the time of ignition) for each of the 50 ignitions supplied from the analysis unit 16. The horizontal axis represents the wavelength of 600 to 850 nm, and the vertical axis represents the emission intensity. This analysis result is a result when an air-fuel mixture obtained by mixing methane gas (fuel gas) and air (air) is ignited using a YAG laser (wavelength 532 nm, input energy 60 mJ). At this time, the timing of laser beam irradiation was set to 20 degrees BTDC (Before Top Dead Center). As shown in FIG. 2, the emission spectrum distribution at the time of breakdown (ignition) has a plurality of peaks. Among these peaks, it includes at least emission Hα (656 nm) of hydrogen atoms in methane gas and emission (777 nm) of oxygen atoms in air.

The computing unit 18 calculates the ratio between the emission peak intensity of Hα (656 nm) and the emission peak intensity of emission of oxygen atoms (777 nm) from the analysis result, and uses this ratio to calculate the equivalence ratio.
Specifically, the ratio of the peak intensity measured by the LIBS spectroscopic analysis method when an air-fuel mixture containing fuel gas and air is ignited, and the equivalent ratio of the air-fuel mixture actually measured using a known lambda meter , And the calculation unit 18 stores this relationship as a reference table. The calculation unit 18 calculates the equivalence ratio in each ignition from the ratio obtained at each ignition of the engine 10 using the stored reference table.

FIG. 3 is a diagram showing the relationship between the equivalence ratio calculated by the calculation unit 18 and the flow rate of the fuel gas when the equivalence ratio is changed by changing the flow rate of the fuel gas and burned by the engine 10. As can be seen from FIG. 3, the equivalence ratio (value indicated by □ in the figure) calculated in the calculation unit 18 changes corresponding to the equivalence ratio that changes by changing the flow rate of the fuel gas. I understand. From this, it can be said that the equivalence ratio calculated in the calculation part 18 shows a reasonable result. The equivalent ratio calculated in this way can be used for adjusting the equivalent ratio of air and fuel gas by a mixing device (not shown). That is, a control signal is sent to the mixing device so as to adjust the mixing device in accordance with the calculation result of the equivalence ratio of the calculation unit 18. Note that the error bars indicated by the vertical bars in FIG. 3 are based on variations of about 300 times excluding the equivalent ratio calculated 500 times and statistically excluded from the average value by 1σ (σ: standard deviation). Standard deviation is shown. The variation in the equivalence ratio indicates that the ignition state is different at the time of ignition. The variation in the equivalence ratio can be said to be based on the fact that the ignition by the laser light occurs in a very narrow position, but the mixture of the air-fuel mixture at this position is not uniform.
In the present embodiment, the equivalence ratio at the ignition position at the time of each ignition can be calculated, and the calculation unit 18 calculates the variation in the equivalence ratio by collecting the equivalent ratios calculated over a certain period. Thereby, the calculating part 18 can obtain the dispersion | variation in the equivalent ratio at the time of each ignition. If the equivalence ratio varies, the presence or absence of ignition and the engine output tend to become unstable, which is not preferable. Therefore, in order to suppress such variation in the equivalence ratio, the engine 10 is provided with a mixing adjustment unit 20.

The mixing adjusting unit 20 adjusts the mixed state of the air-fuel mixture to a mixed state in which variations are reduced.
FIG. 4 is a configuration diagram illustrating an example of the mixing adjustment unit 20.
The mixing adjusting unit 20 includes a turbulent flow grid 20b having a mesh-like grid having a rotation axis in a direction orthogonal to the flow direction of the air-fuel mixture inside the air supply pipe 20a after mixing the air and the fuel gas. When the direction of the lattice surface of the turbulent lattice 20b is orthogonal to the flow direction of the air-fuel mixture, turbulence is difficult to occur, and when it is parallel to the flow direction of the air-fuel mixture, the most turbulent flow is generated. Therefore, the arithmetic unit 18 adjusts the direction of the turbulent flow grid 20b, whereby the mixed state due to the turbulent flow of the air-fuel mixture can be adjusted.

  The controller 22 generates a control signal for controlling ON / OFF of laser light emission of the laser light source 14 and sends the control signal to the laser light source 14, and also generates a signal for controlling the start and stop of the spectroscopic analysis in the analysis unit 16. The control of the ignition of the air-fuel mixture and the control of the LIBS spectroscopic analysis method are performed by sending to 16. Of course, the controller 22 controls the air supply valve 12c and the exhaust valve 12d of the engine body 12a and the equivalence ratio of air and fuel gas.

In such an engine 10, the following air-fuel mixture adjustment method is performed.
First, the laser beam irradiation unit 14 uses a laser beam to ignite the combustion air-fuel mixture supplied into the cylinder 12a of the engine 10 to drive the laser ignition engine. At this time, the laser light is excited by the breakdown of the air-fuel mixture and the atoms constituting the air-fuel mixture are excited to emit light, and the light emitted at this time is measured using laser-induced breakdown spectroscopy. In other words, the analysis unit 16 receives the light emission at the ignition position of the air-fuel mixture and at the time of ignition (at the time of breakdown) and performs spectral analysis every time the laser light is ignited. Next, the calculation unit 18 uses the spectral analysis result of the analysis unit 16 to create a reference table that represents the correspondence relationship between the equivalence ratio stored in advance and the analysis result of the equivalence ratio of the mixture at the ignition position of the mixture. And calculated for each ignition. The calculation unit 18 collects the calculated equivalence ratio for a certain period and obtains the equivalence ratio variation (standard deviation). Based on the calculated equivalence ratio variation, the calculation unit 18 generates a control signal for adjusting the mixture state of the air-fuel mixture and sends the control signal to the mixture adjustment unit 20. The mixture adjusting unit 20 adjusts the mixture state of the air-fuel mixture based on the control signal sent from the calculation unit 18, and supplies the adjusted new air-fuel mixture into the cylinder 12a. The air-fuel mixture at this time is adjusted in the mixing state so that the variation in the equivalence ratio for each ignition by the laser light is reduced.
The equivalence ratio is calculated by calculating the ratio between the emission peak intensity of atoms contained in the fuel gas and the emission peak intensity of atoms contained in the air, and using this ratio, the equivalence ratio is calculated. Thereby, an equivalence ratio can be calculated | required in real time.

  In this way, the mixing adjustment unit 20 uniformly mixes the mixed state of the fuel gas and air in the mixture by the turbulent flow formed by the small vortex. Since the mixing adjustment unit 20 generates a large amount of turbulent flow, it suppresses variations in the local mixed state in the air-fuel mixture, so that it can be considered that a spatially and temporally stable mixed state can be created. . However, if a large amount of turbulent flow is generated in the air-fuel mixture, the supply loss (supply loss) to the cylinder 12a increases and the engine output becomes unstable. Further, due to the turbulent flow, the light at the time of breakdown is diffusely reflected and the received light intensity is lowered, and the accuracy of calculation of the equivalence ratio using the analysis result is lowered. For this reason, in the mixing adjustment unit 20, it is not always preferable to generate a large amount of turbulent flow in order to make the mixing state uniform. In order to maintain the engine output constant and accurately measure the equivalence ratio. There is an optimum state of mixing due to turbulent flow. Accordingly, the calculation unit 18 adjusts the mixture state of the air-fuel mixture by the mixture adjustment unit 20 so that the variation in the calculated equivalent ratio is reduced.

As can be seen from the above description, the engine 10 spectrally analyzes the light emission at the ignition position when the air-fuel mixture is ignited using LIBS analysis, so the equivalence ratio at the ignition position is calculated for each ignition. can do. For this reason, this engine 10 is used to realize an efficient air-fuel mixture adjustment method.
Further, since the laser light used for the ignition of the air-fuel mixture is further used for the breakdown of the air-fuel mixture in the LIBS analysis, the ignition and the equivalence ratio can be calculated simultaneously by one irradiation of the laser light. In particular, the equivalence ratio can be calculated almost in real time.
Further, the laser light irradiation unit 14 has an optical path that leads from the laser light source 14a into the cylinder 12a. When the optical path is traced from the cylinder 12a toward the laser light source 14a, the laser light irradiation unit 14 is directed toward the light receiving surface of the analysis unit 16. A branching optical path that branches using an optical element such as a beam splitter from the middle of the optical path of the light is provided. That is, since the optical path of the laser beam for ignition and the optical path of the light emitted at the time of breakdown partially share the optical path, the layout of the optical device and the measuring device around the engine body 12 is simplified. . Further, as in the prior art, the optical path is formed by using optical elements such as the mirrors 14d, 14g, 14h, the beam splitter 14e, the collimator lens 14f, etc. without using an optical fiber for laser light irradiation. Since the spectral analysis can be performed at a position not affected by the engine vibration of the unit 12, the SN ratio in the spectral analysis can be improved.
The mixing adjustment unit 20 adjusts the mixture state of the mixture based on the calculated equivalence ratio information, and the new mixture whose mixture state is adjusted by the mixture adjustment unit 20 is supplied to the cylinder 12a. The main body 12 can ignite the air-fuel mixture in an optimal mixed state.
When the calculation unit 18 obtains variation data for each ignition of laser light related to the equivalence ratio as the equivalence ratio information, the mixing adjustment unit 20 changes the mixture state of the air-fuel mixture to a mixed state in which the variation of the equivalence ratio is reduced. Can be adjusted.

The analysis unit 16 of the engine 10 of the above embodiment includes an analysis device that performs LIBS analysis. Instead of the analysis unit 16, as shown in FIG. 5, the slit 24a that splits incident light and the slit 24a pass through. It is also possible to use a wavelength dispersion element 24b (for example, a diffraction grating) that disperses the emitted light and an analysis unit 24 that includes photodiodes 24c and 24d.
In the LIBS analysis, when the wavelength of the emission peak to be measured is determined in advance, the apparatus configuration can be simplified by measuring only the emission peak intensity at that wavelength using the slit 24a and the wavelength dispersion element 24b. it can. In this case, the slit 24b is provided so as to correspond to a predetermined wavelength, and the photodiodes 24c and 24d receive only light of a predetermined wavelength in the dispersed light and measure two peak intensities. It is good to configure. Since the wavelength of the emission peak measured by the atoms contained in the air and the wavelength of the emission peak measured by the atoms contained in the fuel gas are determined, the photodiodes 24c and 24d can select the 2 By receiving only light corresponding to the wavelengths of the two emission peaks, the two emission peak intensities can be measured.

In order to calculate the equivalence ratio, in the above-mentioned example, the emission peak intensity of hydrogen atom Hα (656 nm) and the emission peak intensity of oxygen atom emission (777 nm) were measured as the emission peak intensity. It is not limited to the emission peak intensity. For example, the emission peak intensity of light emitted from carbon atoms in the fuel gas can be measured.
In this embodiment, the laser beam is used simultaneously as irradiation light for ignition of the air-fuel mixture and as irradiation light for performing LIBS analysis at the ignition position when the air-fuel mixture is ignited. Therefore, the laser light applied to the air-fuel mixture and the laser light applied to the air-fuel mixture to perform the LIBS spectroscopy may be applied as different laser lights at different timings.

  In this embodiment, the engine main body 12 that supplies an air-fuel mixture obtained by mixing fuel gas and air as shown in FIG. 1 is used, but the present invention is not limited to such a configuration. For example, an engine in which air is supplied into the cylinder 12 a and liquid fuel is directly injected into the cylinder 12 a can be used in place of the engine body 12.

  As described above, the laser ignition engine of the present invention and the method of adjusting the air-fuel mixture in the laser ignition engine have been described in detail. However, the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the present invention. Of course, improvements and changes may be made.

DESCRIPTION OF SYMBOLS 10 Laser ignition engine 12 Engine main-body part 12a Cylinder 12b Piston 12c Supply valve 12d Exhaust valve 12e Laser irradiation port 12f Condensing lens 14 Laser light irradiation part 14a Laser light source 14b Lambda / 2 wavelength plate 14c Polarizing plates 14d, 14g, 14h Mirror 14e Beam splitter 14f Collimating lens 14i Power meter 14j Condensing lenses 16 and 24 Analysis unit 16a ICCD camera 18 Calculation unit 20 Mixing adjustment unit 20a Air supply tube 20b Turbulent grating 22 Controller 24a Slit 24b Wavelength dispersion elements 24c and 24d Photodiode

Claims (9)

A laser ignition engine that uses a laser beam to ignite and burn a combustion air-fuel mixture,
A cylinder in which an air-fuel mixture burns in a combustion chamber, and an engine body including a piston that generates power by combustion of the air-fuel mixture;
A laser beam irradiation unit for irradiating the mixture with laser light for ignition of the mixture in the combustion chamber;
An analysis unit for performing spectral analysis by receiving the ignition position of the air-fuel mixture and light emission at the time of ignition using laser-induced breakdown spectroscopy;
A laser ignition engine comprising: an arithmetic unit that calculates an equivalence ratio of the air-fuel mixture at an ignition position of the air-fuel mixture for each ignition using a result of spectral analysis of the analysis unit.   The laser ignition engine according to claim 1, wherein the laser light used for ignition of the air-fuel mixture is further used for breakdown of the air-fuel mixture in the laser-induced breakdown spectroscopy. The laser light irradiation unit includes a laser light source that emits the laser light, and an optical path that guides the laser light from the laser light source into the cylinder,
In the middle of the optical path, there is provided a branching optical path that branches from the middle of the optical path using an optical element so as to go to the light receiving surface of the analysis unit when the optical path is traced from the cylinder toward the laser light source. The laser ignition engine according to claim 2. The air-fuel mixture is a gas in which fuel gas and air are mixed,
The calculation unit calculates a ratio between an emission peak intensity of atoms contained in the fuel gas and an emission peak intensity of atoms contained in the air from the result of the spectroscopic analysis, and the equivalence ratio is calculated using this ratio. The laser ignition engine according to claim 1, which is calculated. Furthermore, based on the information of the calculated equivalent ratio, having a mixing adjustment unit that adjusts the mixing state of the air-fuel mixture,
The laser ignition engine according to any one of claims 1 to 4, wherein a new air-fuel mixture whose mixing state is adjusted by the mixing adjusting unit is supplied to the cylinder. The information of the equivalence ratio includes a variation for each ignition by the laser beam with respect to the equivalence ratio,
The laser ignition engine according to claim 5, wherein the mixing adjustment unit adjusts the mixing state to a mixing state in which the variation is reduced. A method for adjusting an air-fuel mixture in a laser ignition engine for igniting and combusting a fuel-air mixture for combustion using laser light,
Igniting an air-fuel mixture for combustion in a cylinder of the laser ignition engine using laser light, and driving the laser ignition engine;
Receiving the emission position of the air-fuel mixture and light emission at the time of ignition using laser-induced breakdown spectroscopy, and performing spectroscopic analysis for each ignition by the laser beam;
Calculating the equivalence ratio of the air-fuel mixture at the ignition position of the air-fuel mixture for each ignition using the result of the spectral analysis;
Adjusting the mixture state of the mixture based on the calculated equivalence ratio information and supplying the cylinder with a new mixture having the adjusted mixture state. Adjustment method. The air-fuel mixture is a gas in which fuel gas and air are mixed,
The ratio of the emission peak intensity of atoms contained in the fuel gas and the emission peak intensity of atoms contained in the air is calculated from the result of the spectral analysis, and the equivalent ratio is calculated using this ratio. Item 8. The method of adjusting an air-fuel mixture according to Item 7. The information of the equivalence ratio includes a variation for each ignition by the laser beam with respect to the equivalence ratio,
The method of adjusting an air-fuel mixture according to claim 7 or 8, wherein when the mixture state of the air-fuel mixture is adjusted, the air-fuel mixture state is adjusted so as to reduce the variation.

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