JPH10196471A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of modifying fuel at the compression ratio in which knocking and unexpected self-ignition are not generated, and low emission can be realized. SOLUTION: In an internal combustion engine for compressing air-fuel mixture by the upward movement of a piston 3 after introducing air-duel mixture into a cylinder 2 whose upper and lower parts are blocked with a cylinder head 4 and the piston 3 capable of being vertically moved, and for igniting and burning compressed high-temperature and high-pressure air-fuel mixture, a laser source 13 for irradiating laser light having the wavelength for decomposing hydrocarbon duel during the compression stroke is provided, the hydrocarbon fuel is decomposed by irradiation of the laser light before ignition and combustion, the great quantities of hydrocarbon with the small molecular weight having the NOx reducing action, and the action for cutting the generation mechanism of soot are formed, fuel modulation is performed, and low emission is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine provided with a fuel reforming means using laser light.

[0002]

2. Description of the Related Art In a conventional ordinary gasoline internal combustion engine, intake air and fuel are premixed and introduced as necessary into a cylinder defined by a cylinder head and a piston, and compressed by upward movement of the piston. The fuel injection is completed sufficiently earlier than the ignition timing to form a high-temperature, high-pressure mixture in which the fuel and air are relatively homogeneously mixed at the ignition timing, and is ignited by spark ignition with a spark plug near the compression end. And
The combustion of the air-fuel mixture is completed by the propagation of the flame in the combustion chamber starting from the ignition, and the generation of pressure is controlled by the ignition timing.

Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. 7-332141, a high compression ratio of a high compression ratio in which fuel is premixed to form a homogeneous mixture and self-ignition combustion is performed at a compression end. A premixed self-ignition internal combustion engine has also been proposed. If it can be realized, even if the air-fuel ratio is lean, combustion is completed simultaneously by multipoint ignition, high fuel efficiency and very low NOx emission concentration (about 10 ppm). , High efficiency and low emission engine can be obtained.

[0004]

By the way, in the ordinary gasoline internal combustion engine, in order to reduce emissions such as NOx and soot in exhaust gas, NOx reduction is carried out by decomposing hydrocarbon molecules such as benzene in fuel. Fuel reforming, which produces a large amount of low-molecular-weight hydrocarbons that have the effect of eliminating the action and soot generation mechanism, is one of the effective measures, but reforming by the fuel composition causes various problems, Although it is conceivable that the air-fuel mixture is made higher in temperature and pressure by increasing the compression ratio and reformed by a cracking action in the air-fuel mixture at high temperature and high pressure, knocking occurs when the compression ratio is increased.

On the other hand, in the premixed self-ignition internal combustion engine, a large fuel reforming action can be obtained by compression self-ignition at a high compression ratio, and as a result, low emission can be realized. However, there is a risk that self-ignition may occur unexpectedly, and a stable operating region due to self-ignition combustion is limited.

The present invention has been made in consideration of the above-described conventional problems, and has as its object to provide an internal combustion engine that can reform fuel while maintaining a compression ratio that does not cause knocking or accidental self-ignition, thereby achieving low emission. .

[0007]

In the internal combustion engine of the present invention, an air-fuel mixture is introduced into a vertically closed cylinder by a cylinder head and a vertically movable piston, and the air-fuel mixture is compressed by upward movement of the piston. In an internal combustion engine that ignites and burns a compressed high-temperature and high-pressure air-fuel mixture, a laser source that emits laser light having a wavelength that decomposes hydrocarbon fuel during the compression stroke is provided.
Prior to ignition and combustion, laser light is irradiated to decompose hydrocarbon fuel to generate a large amount of low molecular weight hydrocarbons that have the effect of reducing NOx reduction and soot generation mechanisms, and achieve low emissions through fuel reforming. It is something to do.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1A, 1 is an internal combustion engine using gasoline as fuel, 2 is its cylinder, 3 is a piston,
Reference numeral 4 denotes a cylinder head that covers the upper surface of the cylinder 1 and forms a combustion chamber 5 with the upper surface of the piston 3. Reference numeral 6 denotes an intake port formed in the cylinder head 4, and an intake valve 7 for opening and closing an opening 6a of the intake port 6 with respect to the combustion chamber 5.
Is provided. Reference numeral 8 denotes an exhaust port formed in the cylinder head 4. An exhaust valve 9 for opening and closing an opening 8a of the exhaust port 8 with respect to the combustion chamber 5 is provided.
Reference numeral 10 denotes an injector that supplies fuel through the intake port 6 toward the stem base of the intake valve 7. 11
Is a laser source for ignition, which is disposed on one side of the cylinder head 4 facing the combustion chamber 5, and on the upper wall surface forming the combustion chamber 5, a laser beam from the laser source 11 for ignition is introduced into the combustion chamber 5. A concave portion 12 for wide irradiation is formed. The ignition laser source 11 outputs near-ultraviolet laser light having a wavelength of about 310 nm, and the laser light of this wavelength doubles the frequency of the laser light having a wavelength of 632.8 nm from a He-Ne laser, for example. This can be realized by using a laser source that outputs the laser beam. The combustion chamber 5 of the cylinder head 4
Above the central position, a reforming laser source 13 for performing fuel reforming is disposed toward the cylinder 2. The reforming laser source 13 outputs an infrared laser beam having a wavelength of 1 to 3 μm. For example, an Nd; YAG laser (yttrium-aluminum-containing neodymium) which outputs a laser beam having a wavelength of 1.06 μm. (A laser using a garnet crystal) or a He-Ne laser that outputs a laser beam of 1.15 μm.

FIG. 1B shows the openings 6 of these intake ports 6.
a, the opening 8a of the exhaust port 8, the ignition laser source 11, the irradiation area of the laser light (indicated by oblique lines), and the arrangement of the reforming laser source 13.

The operation of the above configuration will be described. Before the intake valve 7 opens, a predetermined amount of fuel is injected from the injector 10 to perform premixing in the intake port 6, and then the intake valve 7 is opened in the intake stroke. When the mixture is opened, the mixture is introduced into the cylinder 2 and uniformly mixed in the cylinder 2. Then, the intake valve 7 is closed, the piston 3 rises, and the mixture is compressed, so that the mixture is in a high temperature and high pressure state. The fuel is decomposed into small molecules containing OH groups and CH groups by cracking. In this compression stroke, as shown in FIG. 2, from the reforming laser source 13 toward the air-fuel mixture in the cylinder 2, a few msec before the compression top dead center (TDC).
A laser beam with a wavelength of μm is irradiated, and this laser beam excites and decomposes the hydrocarbon fuel, and has a small molecular weight that has the effect of reducing NOx reduction and soot generation mechanisms before reaching the compression top dead center. A large amount of hydrogen is generated and fuel reforming is performed. The compression ratio at the compression top dead center is set such that the mixture temperature at the compression top dead center (TDC) is lower than the self-ignition temperature by ΔT and does not self-ignite as shown in FIG. . Even if the compression ratio is set so as not to cause self-ignition, the fuel reforming is reliably performed by irradiating the reforming laser light.
Then, immediately after the compression top dead center (TDC), the laser source 11
Irradiates the inside of the combustion chamber 5 with a laser beam having a wavelength of about 310 nm to excite OH groups in the air-fuel mixture in the irradiation region to generate OH radicals. That is, 310 nm
Is the light of the excitation band of the OH group, and the OH group has a wavelength of 10
OH radicals are formed at a reaction rate of about ^-9 sec. In addition,
The light energy of the laser beam applied for this reaction is sufficient to be 10 to 20 mJ. In this way, as soon as a large amount of OH radicals are generated, a chain reaction of combustion starts immediately, and the air-fuel mixture is immediately heated to the self-ignition temperature or higher as shown in FIG. 2, and a chain reaction of combustion is started at multiple points simultaneously. You. For this reason, the isocapacity is improved and the efficiency is high, and the flame propagation distance is shortened due to multipoint ignition, so that combustion at a lean air-fuel ratio becomes possible, and the maximum flame temperature is reduced, and as described above. Since the fuel reforming is reliably performed during the compression stroke, low NOx combustion is realized.

In the above description, approximately 310 n at the time of ignition
In this example, OH radicals are generated by irradiating a laser beam of m to excite OH groups.
Is irradiated with a laser beam to excite the CH group.
H radicals may be generated.

Further, in the above embodiment, before the intake valve 7 opens, fuel is injected from the injector 10 to form a premixture in the intake port 6, and the mixture does not self-ignite at the compression top dead center. Although the example of the internal combustion engine in which the temperature is adjusted and the laser light is radiated at a desired time to cause self-ignition has been described, the fuel mixture is injected from the injector 10 during the intake stroke to cause the air-fuel mixture in the cylinder 2. It can be applied to an internal combustion engine that is formed and ignited by irradiating a laser beam from the ignition laser source 11 immediately after the compression top dead center, or an internal combustion engine that is ignited by a conventional ignition plug. Similarly, it exerts a great effect on low emission by fuel reforming.

[0014]

According to the internal combustion engine of the present invention, the air-fuel mixture is introduced into the cylinder whose upper and lower parts are closed by the cylinder head and the vertically movable piston as described above, and the air-fuel mixture is moved upward by the piston. In an internal combustion engine that ignites and compresses a compressed high-temperature and high-pressure air-fuel mixture, a laser source that irradiates laser light with a wavelength that decomposes hydrocarbon fuel during the compression stroke is provided. Irradiation can decompose hydrocarbon fuel to produce a large amount of low molecular weight hydrocarbons that have the effect of reducing NOx reduction and soot generation mechanisms, resulting in fuel reforming and low emission. be able to.

[Brief description of the drawings]

FIG. 1 shows a schematic configuration of an embodiment of an internal combustion engine of the present invention, (a) is a longitudinal sectional view, and (b) is a plan view of an arrangement configuration of a main part.

FIG. 2 is a characteristic diagram of crank angle and temperature in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder 3 Piston 4 Cylinder head 13 Reforming laser source

Claims (1)

[Claims] An air-fuel mixture is introduced into a cylinder whose upper and lower parts are closed by a cylinder head and a vertically movable piston, the air-fuel mixture is compressed by upward movement of the piston, and the compressed high-temperature and high-pressure air-fuel mixture is ignited and burned. An internal combustion engine, comprising: a laser source for irradiating a laser beam having a wavelength that decomposes hydrocarbon fuel during a compression stroke.