JPS58133482A - Ignition method for internal-combustion engine - Google Patents

Abstract

PURPOSE:To have an arrangement in which the ignition energy lowers compared with the gas phase reaction method by installing a solid target in the combustion chamber and by allowing a laser beam to make incidence upon this target. CONSTITUTION:In the combustion chamber 2 of an internal combustion engine 1, a through hole 6 is excavated in its wall 5, supported and fastened by a support rod 4 from a solid target 3. This through hole 6 is blocked by a glass sheet 7 consisting of quartz glass to hold the pressure at the explosion time of mixture gas in the combustion chamber 2. Outside the chamber 2, a laser generator 8 and a light concentration device 9 are installed, and the laser beam L cast from the laser generator 8 is focused at a concentration point P in the surface of target 3 or its adjacency. The energy of laser beam L is converted into thermal energy concentratively at the point P to cause generation of a high temperature which can provide ignition for the mixture gas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition method for an internal combustion engine, and more particularly to a laser-induced ignition method.

The laser ignition method for stool rice uses a lens.
Laser light is focused in a combustion chamber, the air-fuel mixture is turned into plasma at the focusing point, and the property of the laser beam to heat the plasma gas is used to heat the air-fuel mixture at the focusing point all at once. The phase reaction method is well known. However, this gas phase reaction method requires a huge amount of ignition energy, requires a large capacity without laser generation equipment, and is expensive.

This invention was devised to solve the problems of the conventional laser-induced ignition method, and provides an ignition method that can significantly reduce ignition energy compared to the gas phase reaction method. With the goal.

In the ignition method for an internal combustion engine according to the present invention, a solid target is placed within a combustion chamber, and a laser beam is directed toward the target.

Next, an embodiment of the ignition method according to the present invention will be described with reference to the drawings.

1 and 2, the combustion chamber 2 of an internal combustion engine l
A solid target 3 is supported and fixed inside by a support rod 4, and a through hole 6 is bored in the wall 5 of the combustion chamber 2.

The through hole 6 is closed by a glass plate 7 made of quartz glass, so that the pressure inside the combustion chamber 2 when the air-fuel mixture m is generated is maintained.

A laser generator [8] and a laser beam generator 9 are provided outside the combustion chamber 2, and the laser beam emitted from the laser generator IL8 is focused at a converging point P near the target 30. Ru. At the condensing point P, the energy of the laser beam is converted into thermal energy, generating a high temperature capable of igniting the air-fuel mixture.

Laser source; YAG condenser 9; single lens target 3 with focal length 100 [■]; distance between carbon target surface and focal point P; 5-3 [haze]
As a result of conducting experiments under the following conditions, the threshold value of energy required for - times of ignition (hereinafter referred to as ignition threshold) CmJ
/pulae) and x [knee] as shown in Figure 3.

According to Figure 3, the minimum value of the ignition threshold is approximately 1 (mJ/
pulse), and considering that the minimum ignition threshold value in the conventional gas phase reaction method is 4 (mJ/pulse), the ignition energy has been significantly reduced.

The cause of this decrease in ignition energy has not been completely investigated at present, but the target 3 is vaporized or elevated by the energy of the laser beam, and a gas consisting of 7C of the target 3 is generated near the surface of the target 30. It is thought that the energy of the laser beam is efficiently converted into thermal energy in this gas. The basis for this is that there were traces of melting or sublimation on the surface of the target 3, and as is clear from Figure 3, when X is a small positive value, that is, the focal point P is on the surface of the target 3. The ignition threshold is at its minimum when the ignition threshold is a small distance in front of the ignition threshold.

Experiments were also conducted using silicon instead of carbon as the material for the target 3, but results similar to those shown in the graph of FIG. 3 were obtained.

Note that a laser beam from another laser source may be used as the laser beam, and the configuration of the condenser may be changed as appropriate. The laser beam can be not only a parallel beam but also a parallel beam, and therefore the focal point P is not necessarily the focal point of the condenser.

Currently, in order to generate a laser beam with an energy of 1 (mJ/pulse), a comparatively large cylinder size and a large generator are required, but it is possible to increase the output power of semiconductor lasers or further increase the ignition threshold. The reduction can provide a very inexpensive ignition system. According to this invention, the position of the target can be set at any position within the combustion chamber, and the timing of laser generation can also be set extremely precisely, so ignition can be achieved under more favorable conditions than with conventional spark plugs. It becomes possible.

As mentioned above, the ignition method for an internal combustion engine according to the present invention includes:
Since a solid target is placed in the combustion chamber and the laser beam is directed toward the target, this method has an excellent effect in that the ignition energy can be significantly reduced compared to the gas phase reaction method.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an embodiment of the ignition method for an internal combustion engine according to the present invention, Fig. 2 is a partially enlarged view of Fig. 1, and Fig. 3 shows changes in the ignition threshold in the same embodiment. The graph shown is correct. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 2... Combustion chamber, 3... Target, 4... Support rod, 5... Wall, 6... Through hole, 7
... Glass plate, 8 ... Laser generator, 9 ... Concentrator, L ... Laser light, P ... Focusing point. 2nd FS! 'I Sochi Kim

Claims (1)

[Claims] (1) Ignition of an internal combustion engine in which a solid target is placed in the combustion chamber of an internal combustion engine, a laser beam is directed toward the target, and the air-fuel mixture in the combustion chamber is ignited by the heat generated at or near the target surface. Method.