JPH0533654A - Combustion chamber of methanol engine - Google Patents

Abstract

PURPOSE:To contrive the promotion of efficiency in a combustion state of fuel in a two-cycle methanol engine equipped with an auxiliary combustion chamber, through improvements in the auxiliary combustion chamber and an injection nozzle. CONSTITUTION:An edged platelike upper wall material 21 provided with a heat insulator 22 is installed on the upper part of an auxiliary combustion chamber 2, while a main connecting hole 23 and a sub connecting hole 24 are installed in a bottom part of a barrel part 20 and a side wall part, interconnecting it to a main combustion chamber. In addition, a nozzle 3 is set up in an upper central part of the auxiliary combustion chamber 2 and two types of nozzle holes for generating both and lower sprays 31 and 32 are installed there. At the time of engine driving, an unblended mixture by the lower spray long in a fueling range is blown to the hot upper wall material 21 short in the fueling range and, after being ignited, and it is extruded to the main combustion chamber by dint of combustion gas by the ignited upper spray, thus mixture generation and its combustion are promoted.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a combustion chamber of a methanol engine which uses methanol as a fuel for the engine.

[0002]

2. Description of the Related Art Fossil fuels such as light oil are usually used as engine fuels, but the exhaust gas contains many substances that pollute the atmosphere such as nitrogen oxides and black smoke. Being tried.

[0003]

In an engine using methanol as the fuel, nitrogen oxides in the exhaust gas can be reduced, but since the latent heat of vaporization of methanol itself is high and the ignition temperature is high, it is low in a 2-cycle engine. There is a problem of poor combustion at load and low speed. Then, it is effective to use ceramics as an adiabatic structure for the engine and maintain the combustion chamber at a high temperature, but it is necessary to speed up the mixing of fuel methanol and air. When a sub combustion chamber is used, it is possible to promote combustion in the sub combustion chamber and blowout of the combustion gas from the sub combustion chamber to the main combustion chamber.
It has become a challenge for methanol engines.

The present invention has been made in view of the above problems, and an object thereof is to provide a combustion chamber of a methanol engine which intends to promote combustion in a two-cycle engine using methanol.

[0005]

In order to achieve the above-mentioned object, according to the present invention, in a combustion chamber of a methanol engine which has a sub-combustion chamber and is operated for two cycles using methanol as a fuel, the outer wall is thermally insulated. A sub-combustion chamber having a stepped columnar space provided with an upper wall member made of a downward-facing edge-shaped ceramics covered with a material and a large body portion of the inner wall,
A fuel nozzle provided in a central portion of the upper wall material and having a nozzle for spraying fuel toward an edge portion thereof and a nozzle for spraying downwardly of a peripheral wall of the body portion, and a central portion of a bottom surface of the auxiliary combustion chamber. Provides a combustion chamber for a methanol engine having a main communication hole that penetrates through the cylinder and communicates with the main combustion chamber, and a sub-communication hole that communicates between the lower portion of the peripheral wall of the body and the central portion of the cylinder upper wall.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing the construction of an embodiment of a combustion chamber of a methanol engine according to the present invention, and FIG. 2 is an explanatory view related to the auxiliary combustion chamber.

In these drawings, 1 is a cylinder,
A headliner 11 made of ceramics made of silicon nitride is provided on the top, a sub-combustion chamber 2 and an exhaust valve 4 are mounted above the headliner 11, and a cylinder liner 12 is connected below via a gasket 13. There is.

The sub-combustion chamber 2 is made of ceramics having high heat resistance and mechanical strength, is formed in a two-step cylindrical shape having a small inner diameter in the upper portion, and has a downward facing edge-shaped dish-shaped upper wall member 21. Aluminum nitride with excellent thermal conductivity is used for
Since the outer wall portion is covered with the heat insulating material 22, the temperature rises quickly and the high temperature is maintained. A main communication hole 23 and a sub communication hole 24, which communicate with the main combustion chamber, are respectively formed through the bottom surface and the side wall of the body portion 20 of the auxiliary combustion chamber 2 as shown in the drawing, so that air in the compression stroke and air in the combustion stroke are generated. It is configured so that combustion gas can pass through. Reference numeral 25 denotes a current circuit, which energizes the heater coil 26 of the upper wall member 21 to heat the engine to a predetermined temperature when the engine is cold.

Reference numeral 3 denotes a nozzle for injecting methanol as a fuel, which is provided in the upper central portion of the auxiliary combustion chamber 2 and has an injection port for spraying the upper spray 31 on the side edge portion of the upper wall member 21 of the auxiliary combustion chamber 2.
The side wall below the sub-combustion chamber 2 is provided with a two-stage injection port including the injection port for spraying the downward spray 32. Since the former upper spray 31 has a short scattering distance, it can be rushed to the high temperature upper wall material 21 in a short time. It often reaches and ignites by touching the wall temperature, and this collision causes the air-fuel mixture to diffuse at once. The latter downward spray 32 has a long scattering distance, and fuel with large latent heat of vaporization mixes with air during the ignition delay. However, a large amount of the air-fuel mixture that remains in the sub-combustion chamber, but stays in the lower combustion chamber, is ejected into the main combustion chamber while the flame spreads from above due to the former strong diffusion force.

Reference numeral 5 denotes a piston, which comprises a piston head 51 made of ceramics which is excellent in heat resistance and mechanical strength, and a piston body portion 52 connected by a connector 53.

On the upper surface of the piston head 51, a circular projecting portion 54 is provided at a portion corresponding to the above-mentioned main communication hole 23.
A recess 55 is formed in a portion corresponding to the sub-communication hole 24 to promote the generation of the air-fuel mixture in the auxiliary combustion chamber in the compression stroke and the promotion of combustion in the main combustion chamber in the combustion stroke.

Next, the operation of this embodiment thus constructed will be described.

A little before the piston 5 rises to reach the top dead center, the fuel methanol is injected from the nozzle 3, and its spray is sprayed from the nozzle of the nozzle 3 to the upper spray 31 and the lower spray 31 as shown in FIG. It becomes the spray 32 and is sprayed on the inner wall of the auxiliary combustion chamber 2.

Since the upper spray 31 is sprayed on the edge of the upper wall member 21 which is covered with the heat insulating material 22 and holds the high temperature, and hits the high temperature wall surface rapidly with a short flight distance, Even fuel with a large latent heat of vaporization and a high ignition point is ignited, and when it collides, it immediately becomes a mixture and is efficiently diffused to promote its combustion. On the other hand, the lower spray 32, which has a long flight distance and is injected toward the side wall below the sub-combustion chamber 2, tends to remain in the sub-combustion chamber 2 as an air-fuel mixture with delayed vaporization and ignition due to its latent heat of vaporization. Is extruded into the main combustion chamber through the auxiliary communication hole 24 and the main communication hole 23 by the above-mentioned force of the efficient combustion gas of the upper spray 31 and mixed with the air compressed by the rise of the piston 5. And efficiently burns, and the combustion energy powerfully drives the piston 5 downward.

Then, as the piston 5 descends, the exhaust valve 4 is opened, and then fresh air is pressure-fed by the opening of the scavenging port (not shown) to scavenging the inside of the cylinder 1 and the next compression stroke. Will be done.

Although the present invention has been described with reference to the above embodiments, various modifications can be made within the scope of the gist of the present invention, and these modifications are not excluded from the scope of the present invention.

[0018]

According to the present invention as in the above embodiments,
The sub-combustion chamber is formed by an upper wall material made of ceramics and a body, and a nozzle having two kinds of nozzles is arranged on the upper wall material and a main communication hole and a sub-communication hole are provided in the body. Since it is communicated with the combustion chamber, the lower spray injected from the nozzle has a longer reach and vaporization and combustion are delayed as described above, but the upper spray reaches the edge of the high temperature upper wall material quickly. As a result of the vaporization and ignition of the air, the combustion energy causes it to be rapidly pushed out into the main combustion chamber through the main and auxiliary communication holes, efficiently mixed with the air in the main combustion chamber, and its combustion is promoted. can get.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a combustion chamber of a methanol engine according to the present invention.

FIG. 2 is an explanatory diagram related to a sub combustion chamber in the present embodiment.

[Explanation of symbols]

1 ... Cylinder 2 ... Secondary combustion chamber 3 ... Nozzle 5 ... Piston 11 ... Headliner 21 ... Upper wall material 22 ... Insulation 23 ... Main communication hole 24 ... Sub communication hole 26 ... Heater coil 31 ... Upward spray 32 ... downward spray

Claims (2)

[Claims] 1. A combustion chamber of a methanol engine having a sub-combustion chamber and operated for two cycles using methanol as a fuel, wherein an outer wall is covered with a heat insulating material and an upper wall made of a downward-facing edged plate-shaped ceramics. Of the sub-combustion chamber having a stepped cylindrical space provided with a material and a large body portion of the inner wall, an injection port provided in the central portion of the upper wall material and spraying fuel in the direction of the edge, and the body portion. A fuel nozzle having an injection port that sprays toward the lower portion of the peripheral wall, a main communication hole that communicates with the main combustion chamber through the cylinder from the center of the bottom surface of the auxiliary combustion chamber, the lower peripheral wall of the body and the cylinder upper wall. A combustion chamber for a methanol engine, comprising a sub-communication hole communicating with the central portion of the. 2. The edged plate-shaped ceramics is made of aluminum nitride having a high thermal conductivity.
Combustion chamber of the described methanol engine.