JPH0533653A - 2-cycle methanol heat shield engine - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the combustion failure of a two-cycle heat shield engine using methanol, which has a large latent heat of vaporization and a high ignition point, as fuel. [Structure] A headliner 11 made of ceramics and a sub-combustion chamber 2 using a heat insulating material 21 are integrated to provide a plurality of communication holes 4 communicating with the main combustion chamber.
So that the air from the inside advances to the peripheral wall portion of the auxiliary combustion chamber 2,
Further, in the combustion process, the communication hole 4 is formed so that the combustion gas from the auxiliary combustion chamber 2 becomes a turbulent flow in the main combustion chamber. Therefore, when the fuel spray from the nozzle 3 is sprayed in the peripheral wall direction of the auxiliary combustion chamber 2, the air-fuel mixture is efficiently generated, and the combustion gas ejected from the communication hole 4 is also rapidly combusted in the main combustion chamber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-cycle methanol heat shield engine in which the combustion chamber of the engine has a heat shield structure and methanol is used as fuel.

[0002]

2. Description of the Related Art In recent years, a heat shield engine has been developed which uses a heat shield material such as ceramics, which can withstand high temperatures, mainly in a combustion chamber such as an engine cylinder liner, cylinder head, piston head and intake / exhaust valve. There is.

Although fossil fuels such as light oil are usually used as fuels for this type of engine, the exhaust gas contains many substances that pollute the atmosphere, such as nitrogen oxides and black smoke. The engine is being tried.

[0004]

The above-mentioned methanol is almost infinite as a fuel resource, and the generation of harmful substances in exhaust gas is reduced, but since it has a large latent heat of vaporization and a high ignition point, it is vaporized and ignited. There is a problem that the blowing out of the combustion gas is delayed and the combustion at partial load is bad.

The present invention has been made in view of the above problems, and an object thereof is to improve the low combustion efficiency at the time of partial load and the delay of the discharge of combustion gas from the auxiliary combustion chamber, which are the drawbacks of the methanol engine. The present invention is to provide a two-cycle methanol heat shield engine.

[0006]

In order to achieve the above-mentioned object, according to the present invention, a heat shield is used in a combustion chamber-related portion of an engine having a secondary combustion chamber, and methanol is used as a fuel.
In a cycle methanol heat shield engine, ceramics is used for the headliner that integrates the cylinder head lower surface of the engine and the cylinder liner, and the auxiliary combustion chamber is connected to the upper part so that the bottom surface is formed integrally with the headliner. A spray of fuel from a nozzle provided above the chamber is ejected in the direction of the inner peripheral wall of the auxiliary combustion chamber, and a plurality of communication holes communicating the auxiliary combustion chamber and the cylinder are formed through the integral part of the headliner. Two-cycle methanol in which a plurality of communication holes are formed so that the compressed air from the cylinder in the compression stroke proceeds in the direction of the inner peripheral wall of the auxiliary combustion chamber and the combustion gas in the combustion stroke becomes turbulent and dispersed in various parts of the main combustion chamber. A heat shield engine is provided.

[0007]

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

FIG. 1 is a sectional view of a cylinder and a piston portion showing an embodiment of a two-cycle methanol heat shield engine according to the present invention, and FIG. 2 is a sectional view of combustion gas from a communication hole of a sub-combustion chamber in this embodiment. It is explanatory drawing which shows a blowing condition.

In these drawings, 1 is a cylinder,
A headliner 11 made of, for example, ceramics made of silicon nitride is provided at the top, a sub-combustion chamber 2 is attached at a predetermined position above the headliner 11, and a cylinder liner 12 is connected below the subcombustion chamber 2 via a gasket 13.

The sub-combustion chamber 2 is made of a ceramic material having high heat resistance and mechanical strength. The sub-combustion chamber 2 has a stepped cylindrical space whose upper part is narrowed, and the sub-injection is divided from the injection nozzle. The bottom surface is integrated with the headliner 11 so that the spray from the hole collides and ignites to push out the air-fuel mixture in the sub chamber. The outer circumference of the upper part is covered with a heat insulating material 21 and is shielded from heat so that the inner wall temperature is maintained at a high temperature, and a nozzle 3 for injecting methanol as fuel as a spray is attached to the central part of the top part. At the tip of the nozzle 3 protruding into the auxiliary combustion chamber 2, a nozzle hole for spraying methanol of fuel as a main spray 31 to the lower inner wall as shown in the figure, and a temperature surrounded by the heat insulating material 21 as a sub spray 32 The injection holes to be blown to the upper inner wall portion are formed in two stages, and vaporization of fuel in the auxiliary combustion chamber 2 and mixing with air are achieved.

A plurality of communication holes 4 are provided so as to penetrate the bottom surface of the auxiliary combustion chamber 2, that is, the upper wall of the headliner 11, to connect the auxiliary combustion chamber 2 and the cylinder 1 to each other. Is provided with four small holes. Then, in the compression stroke in the two-cycle operation of the engine, the air flow from the cylinder is blown into the vicinity of the inner wall of the auxiliary combustion chamber 2 where the fuel spray reaches, and in the combustion stroke, the combustion gas from the auxiliary combustion chamber 2 becomes as shown in FIG. It is blown out in the direction of the arrow shown, and is configured to favorably generate the air-fuel mixture by the turbulent flow effect with the air in the main combustion chamber.

Reference numeral 5 denotes a piston, which is provided with a piston head 51 made of ceramics having excellent heat resistance and mechanical strength, and a piston body 52 connected by a connector 53. By sliding the inner surface up and down, the vehicle is driven via the connecting rod 54, the crankshaft, and the like.

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 the spray is heat shielded as the main spray 31 and the sub spray 32 as shown in FIG. Reaching the vicinity of the wall surface of the sub-combustion chamber 2 that is generated, while being mixed with air from the plurality of communication holes 4 by the ascending piston 5, the mixture of sub-spray sprayed above the inner wall and kept at high temperature is ignited To do. In this case, the air from the communication hole 4 is formed so as to be blown toward the inner wall surface, not near the nozzle hole of the nozzle 3, so that the fuel and air are vigorously mixed near the wall surface to achieve efficient mixing. Become.

Then, the combustion gas which has become half-burned by the pressure due to the above-mentioned ignition and combustion is ejected from the communication hole 4 into the main combustion chamber and, as mentioned above, is sufficiently mixed by the turbulent flow effect with the air flow to be completely mixed. The piston 5 is combusted, the piston 5 is strongly lowered by this pressure, and the crankshaft is rotated by the connecting rod 54.

Then, exhaust is performed by the fresh air pressure-fed from the scavenging port (not shown), and the two-cycle operation of the engine is continued.

Although the present invention has been described with reference to the above-described 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]

As described above, according to the present invention, the headliner made of ceramics and the bottom portion of the auxiliary combustion chamber are integrally formed, and the plurality of communication holes communicating the auxiliary combustion chamber and the main combustion chamber are penetrated. Since the opening direction is set so that the compressed air from the cylinder advances to the inner peripheral wall of the auxiliary combustion chamber and the combustion gas from the auxiliary combustion chamber becomes a turbulent flow in the main combustion chamber, When the fuel spray from the nozzle at the top of the combustion chamber is injected in the wall direction of the auxiliary combustion chamber, it violently mixes with the air flow from the communication holes on the wall surface with good dispersibility to form combustion gas and start the combustion process. Then, the unburned gas ejected from the communication hole due to the pressure of the combustion gas becomes a turbulent flow in the main combustion chamber and mixes with the air, so that rapid combustion is performed and combustion efficiency is improved even when the engine is partially loaded. The effect is obtained.

Further, in the present invention, since the communication hole between the auxiliary combustion chamber and the main combustion chamber is provided in the headliner made of ceramics, the heat resistance is better than that of a member mainly made of metal. Therefore, there is an advantage that the occurrence of inconveniences such as cracks is reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a cylinder and a piston portion showing an embodiment of a two-cycle methanol heat shield engine according to the present invention.

FIG. 2 is an explanatory diagram showing a spraying state of spray from a communication hole of the auxiliary combustion chamber in the present embodiment.

[Explanation of symbols]

 1 ... Cylinder 2 ... Secondary combustion chamber 3 ... Nozzle 4 ... Communication hole 5 ... Piston 11 ... Headliner 21 ... Thermal insulation material 31 ... Main spray 32 ... Sub spray

Claims (1)

Claim: What is claimed is: 1. A two-cycle methanol heat shield engine in which a heat shield material is used in a combustion chamber-related portion of an engine having a sub-combustion chamber and methanol is used as a fuel, and a ceramic is used as a headliner of the engine. In addition to adopting the above, the sub-combustion chamber is connected to the upper part to form the bottom surface integrally with the headliner, and the fuel spray from the nozzle provided above the sub-combustion chamber is ejected toward the inner peripheral wall of the sub-combustion chamber. Further, a plurality of communication holes that communicate the sub-combustion chamber and the cylinder are formed in an integral part of the headliner, and the compressed air from the cylinder in the compression process advances toward the inner peripheral wall of the sub-combustion chamber and the combustion gas in the combustion process. A two-cycle methanol heat shield engine in which a plurality of communication holes are formed so as to form a turbulent flow and disperse in various places in the main combustion chamber.