JPH0742563A - Combustion chamber for gas engine - Google Patents

Abstract

PURPOSE:To perform rapid transfer of mixed combustion gas to a main combustion chamber and to reduce the size of a structure. CONSTITUTION:At the second half stage of a compression stroke, the injection hole 32 of a fuel gas chamber 31 is inserted in the outlet 26 of an auxiliary chamber 21 and combustion gas is injected from the fuel gas chamber 31 to the auxiliary chamber 21. Consecutively, combustion gas in the auxiliary chamber 21 is injected to the outer peripheral area of the main combustion chamber 22 through a communication hole 23. Combustion in the main combustion chamber 22 is started from the outer periphery thereof and combustion gas gathers to the center of the main combustion chamber 22. A combustion time is shortened and the combustion efficiency of an engine is improved. Further, since the auxiliary chamber 21 is arranged in a piston 2, the structure of a cylinder head 3 is simplified and the degree of freedom of the design of an engine is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a combustion chamber of an engine, and more particularly to a structure of a combustion chamber of a diesel engine using gas as a fuel.

[0002]

2. Description of the Related Art Fossil fuels such as gasoline are often used as fuel for internal combustion engines, which are the prime movers of vehicles. High-pressure gas fuel is also partially used as fuel for internal combustion engines. Recently, high-pressure gas fuel has begun to be used as a fuel for diesel engines for power generation equipment in small-scale power generation units such as city buildings. When gas fuel is injected into the combustion chamber of an engine, it may be difficult to self-ignite because of poor mixing with air. In order to improve such inconvenience, a sub-combustion chamber type gas fuel engine has been developed in which a sub-combustion chamber following the main combustion chamber in the engine cylinder is provided and gas fuel is injected into the sub-combustion chamber. Sho 62-19163
No. 2 publication. The above-mentioned conventional example has a structure in which the low-pressure gas previously contained in the auxiliary combustion chamber is ignited by the spark of the spark plug and the combustion gas is injected into the main combustion chamber. In such a conventional engine, when the gas mixed and combusted in the auxiliary combustion chamber is ejected to the main combustion chamber, the mixed combustion gas cannot be smoothly transferred to the main combustion chamber, resulting in inconvenient combustion. . Besides, since the auxiliary combustion chamber is located at the upper end of the cylinder head, the size of the engine is increased and the degree of freedom in design is reduced.

[0003]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned conventional inconveniences, and an object thereof is to provide a mixed combustion gas in an engine having a sub-combustion chamber that uses gas fuel. The present invention aims to provide a combustion chamber for a gas engine that can be quickly transferred to the main combustion chamber and can be downsized.

[0004]

In order to achieve the above-mentioned object of the present invention, the present invention comprises a sub-combustion chamber communicating with the main combustion chamber, and a fuel gas chamber provided separately from them. In an engine that allows gas fuel to flow into the sub-combustion chamber, a fuel gas that is provided in the upper portion of a cylinder and has an ejection hole that projects into the cylinder, and that injects the gaseous fuel supplied into the cylinder from the ejection hole into the cylinder. Chamber, a control valve that opens and closes the injection hole of the fuel gas chamber, and a plurality of communication holes that are provided in a hollow shape in the head of a piston that moves up and down in the cylinder and that communicates from the hollow portion to the vicinity of the outer periphery of the cylinder. And a sub-combustion chamber having an outlet to which the ejection hole of the fuel gas chamber is fitted in the vicinity of the top dead center of the piston, and a combustion chamber of a gas engine.

[0005]

[Operation] In the latter half of the compression stroke, the injection hole of the fuel gas chamber is inserted into the outlet of the auxiliary combustion chamber, the combustion gas is injected from the fuel gas chamber to the auxiliary combustion chamber, and then the combustion gas of the auxiliary combustion chamber is passed through the communication hole. Ejects into the outer peripheral area of the main combustion chamber. The combustion in the main combustion chamber occurs from this outer circumference, and the combustion gas gathers in the center of the main combustion chamber.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a configuration diagram of a main part showing an embodiment of a combustion chamber of a gas engine according to the present invention, in which 1 is a cylinder. A piston 2 is arranged inside the cylinder 1 so as to be vertically movable. The center of the upper surface of the piston 2 is largely recessed to form a sub combustion chamber 21. FIG. 1 shows the piston in the uppermost position, and the main combustion chamber 22 is formed on the upper surface of the piston 2. Between the main combustion chamber 22 and the sub combustion chamber 21, a plurality of communication holes 2 formed by hollowing out the main body of the piston 2 are formed.
Combined at 3. Reference numeral 24 is a piston ring, and 25 is a connecting rod.

A combustion gas chamber 31 is provided in the cylinder head 3 located at the upper end of the cylinder 1. The fuel gas chamber 31 is made of, for example, high-strength and heat-resistant ceramics, and an ejection hole 32 extending to the auxiliary combustion chamber 21 is formed at the bottom thereof. When the piston 2 is near the top dead center, the outer periphery of the ejection hole 32 is inserted into the auxiliary combustion chamber 21 with a slight gap 27 with the outlet 26 of the auxiliary combustion chamber 21.

Reference numeral 4 denotes a control valve for controlling the opening and closing of the ejection hole 32, which comes into close contact with a valve seat 33 provided below the ejection hole 32 from below to close the fuel gas chamber 31. The stem 43 of the control valve 4 is axially supported by the valve guide 35 of the upper wall portion 34 of the fuel gas chamber 31, and the stem 43 is the upper plate 44.
Is biased by a spring 45 that pushes up.

Reference numeral 5 denotes a gas fuel valve mounted on the upper side portion of the fuel gas chamber 31, which extends from the gas supply pipe 53 to the fuel gas chamber 3
The gas fuel supply port 54 is opened and closed to control the gas flow, and the valve spring 52 that pushes up the upper end of the stem 51 normally closes the supply port 54. A control valve 55 controls the flow rate of the fuel gas.

Although not shown in FIG. 1, a control valve 4 and a gas fuel valve 5 are provided above the cylinder head 3, respectively.
Is provided with a cam mechanism that opens and closes at a timing described later. The drive mechanism for opening and closing these valves need not be a cam, but may be an electromagnetically driven valve mechanism driven by electromagnetic force.

Although not shown in FIG. 1, the cylinder head 3 is provided with a normal intake hole and an intake valve, an exhaust hole and an exhaust valve, and a cam mechanism for driving these two valves. .

Next, the operation of the embodiment of the present invention will be described with reference to FIGS. The operation is started from the exhaust stroke in which the exhaust valve (not shown in FIG. 1) opens and the piston 4 starts rising from the bottom dead center. In this state, the gas fuel valve 5 is closed and the control valve 4 is open. When the piston 2 rises and the combustion gas in the cylinder 1 is exhausted to the outside of the engine, an exhaust valve (not shown in FIG. 1) is closed and an intake valve is opened. When the piston 2 starts descending from the top dead center, fresh air is sucked into the cylinder 1 through the intake hole. The control valve 4 is closed during the intake, and the combustion chamber and the fuel gas chamber 31 in the cylinder are closed.
Distribution with is cut off. Immediately after that, the gas fuel valve 5 is opened, and the gas fuel is supplied from the gas supply pipe 53 to the fuel gas chamber 53. The supply amount of this gas fuel is adjusted by the control valve 55 depending on the load state of the engine. When a predetermined amount of gas fuel is supplied and the intake stroke ends, the intake valve closes and the gas fuel valve 5 also closes.

When the piston starts rising from the bottom dead center position, the air in the cylinder starts to be compressed. Then, when the piston 2 approaches the top dead center, the inside of the outlet 26 of the auxiliary combustion chamber 21 provided in the upper portion of the piston 2 has the injection hole 3 of the fuel gas chamber 31.
Fit into the outer circumference of 2. Around this timing, the control valve 4 opens. Then, the air compressed in the cylinder flows into the fuel gas chamber 31 to generate an air-fuel mixture, and when the temperature in the fuel gas chamber 31 reaches the ignition point, the fuel gas chamber 31 becomes fuel-rich. Combustion begins.

The air-fuel mixture in the fuel gas chamber is jetted into the sub-combustion chamber 21 through the jet holes 32 to generate air-fuel mixture.
The gas mixed and burned here flows from the auxiliary combustion chamber 21 to the communication hole 2
It is ejected to the outer peripheral portion of the main combustion chamber 22 near the cylinder through the nozzle 3. Therefore, combustion occurs in the main combustion chamber 22 at once. Then, the piston is pushed down by this combustion, and the outlet 26 of the auxiliary combustion chamber has the ejection hole 32 of the fuel gas chamber 31.
Get away from. At this time, the gas remaining in the sub-combustion chamber 21 is ejected from the outlet 26 to the center of the main combustion chamber 22, and the combustion in the main combustion chamber progresses at once and ends within a short time. When the piston reaches the bottom dead center, the exhaust stroke of the next cycle starts.

[0015]

As described above in detail, according to the present invention, combustion is started in the fuel rich state in the auxiliary combustion chamber provided on the piston side, so that NOx reduction can be achieved. Then, in the initial stage of combustion, the gas ejected from the sub-combustion chamber through the communication hole reaches a place near the cylinder outer periphery of the main combustion chamber, so the combustion in the main combustion chamber occurs from this outer periphery, and the combustion gas is the main combustion chamber. Since they are concentrated in the center, the combustion time is shortened and the combustion efficiency of the engine is improved. Further, since the auxiliary combustion chamber is also received in the piston, the structure of the cylinder head is simplified and the degree of freedom in engine design is increased.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram illustrating an operation of the embodiment.

[Explanation of symbols]

 1 ... Cylinder 2 ... Piston 21 ... Secondary combustion chamber 22 ... Main combustion chamber 23 ... Communication hole 24 ... Piston ring 25 ... Connecting rod 26 ... Outlet 3 ... Cylinder head 31 ... Fuel gas chamber 32 ... Spout hole 33 ... Valve seat 34 ... Upper wall 35 ... Valve guide 4 ... Control valve 43 ... Stem 44 ... Upper part Plate 45 ... Spring 5 ... Gas fuel valve 51 ... Stem 52 ... Stem 53 ... Gas supply pipe 54 ... Supply port 55 ... Control valve

Claims (1)

[Claims] 1. An engine provided with an auxiliary combustion chamber communicating with the main combustion chamber, wherein gas fuel is introduced into the auxiliary combustion chamber from a fuel gas chamber provided separately therefrom A fuel gas chamber having an ejection hole projecting into the cylinder for ejecting the gas fuel supplied therein into the cylinder from the ejection hole; a control valve for opening and closing the ejection hole of the fuel gas chamber; and a vertical movement in the cylinder. An outlet that is provided in a recessed shape on the head of the piston and that has a plurality of communication holes that communicate from the recessed portion to the vicinity of the outer periphery of the cylinder, and in which the injection hole of the fuel gas chamber fits near the top dead center of the piston. And a sub-combustion chamber having: a gas combustion chamber of the gas engine.