KR100684980B1 - Gas Engine - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas engine, wherein a cylinder head (3) having a preceding combustion chamber (1) provided at one side with an ignition source at an eccentric position at its center line (AA) and a bottom of the preceding combustion chamber (1) The trailing combustion chamber 11, which communicates with the preceding combustion chamber 1 via the connecting opening 11, includes a cylinder 9 with a built-in piston 8, which is recessed in its upper surface, thereby providing the basis of a conventional diesel engine. Maintaining the shape of the combustion chamber has the advantage of avoiding the need for additional production facility investment in accordance with the shape of the combustion chamber.

Gas engine, leading combustion chamber, trailing combustion chamber, cylinder, piston

Description

Gas Engine

1 is a cross-sectional view showing a combustion chamber structure of a gas engine according to the present invention;

2 is a cross-sectional view showing another embodiment of a connection opening connecting a trailing combustion chamber and a preceding combustion chamber in the gas engine according to the present invention.

3 to 5 are sectional views showing modifications of the post combustion chamber of the gas engine according to the present invention.

FIG. 6 is a cross-sectional view showing a state in which the unburned portion on the squash region is removed in the embodiment shown in FIG.

Explanation of symbols on the main parts of the drawings

1: preceding combustion chamber

3: cylinder head

7: spark plug

9: cylinder

11: trailing combustion chamber

13: connection opening

The present invention relates to a gas engine, and more particularly, a spark ignition gas that can use a gas such as natural gas, propane gas, butane gas, bio-gas, etc. by improving a conventional indirect injection diesel engine. It's about the engine.

In general, there are systems that use only gas as fuel, and gasoline engines that can be used mainly for passenger cars and diesel engines that can use gas instead of diesel.

Since the combustion method of the engine using gas is the same as that of a gasoline engine except that the combustion method and the fuel supply method use gaseous fuel, research and development of a natural gas engine using an existing gasoline engine is being actively performed.

On the other hand, the conversion from a diesel engine to a gas engine using a conventional compression ignition scheme requires a change of many engine parts with respect to engine performance. That is, when converting a diesel engine into a gas engine, when the diesel engine is converted into a gas engine without modifying the combustion chamber structure, a low flame efficiency is generated due to a long flame propagation distance and harmful substances of unburned hydrocarbon series are generated. .

The present invention has been made in view of the above circumstances, and an object thereof is to provide a gas engine that generates power by using gas as a fuel by improving a combustion chamber structure of a conventional diesel engine.

Another object of the present invention is to provide a gas engine capable of maximally suppressing generation of harmful gases due to unburned gaseous fuel.

The gas engine according to the present invention includes a cylinder head having a preceding combustion chamber provided with an ignition source on one side in an eccentric position from a center line thereof, and a subsequent combustion chamber communicating with the preceding combustion chamber through a connection opening formed at a bottom of the preceding combustion chamber. And a cylinder having a piston formed concave on its upper surface, wherein a flame generated by the ignition source is propagated from the preceding combustion chamber to the subsequent combustion chamber.

Preferably, the cylinder head and / or the edge portion of the cylinder forming the edge of the connection opening can be chamfered so that the open cross-sectional area of the connection opening from the preceding combustion chamber to the subsequent combustion chamber is expanded.

Further, preferably, the bottom depth of the trailing combustion chamber is gradually lowered in the direction away from the region adjacent to the connection opening.

Preferably, the squash region and the piston do not occur in the squash region of the piston formed while maintaining a predetermined gap between the upper surface of the piston and the lower surface of the cylinder head. An edge portion of the piston forming the boundary portion of the trailing combustion chamber of may be chamfered and inclined.

Hereinafter, exemplary embodiments of a combustion chamber structure of a gas engine according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a combustion chamber structure of a gas engine according to the present invention.

Referring to Fig. 1, the combustion chamber of a gas engine according to the present invention has a preceding combustion chamber 1 and a trailing combustion chamber 11.

The preceding combustion chamber 1 is configured by forming recesses in the cylinder head 3. The preceding combustion chamber 1 preferably has an upper portion formed in a hemispherical shape and a lower portion formed in a truncated cone, a cylinder, or the like. The hemispherical shape of the preceding combustion chamber 1 is the structure which can propagate the flame which generate | occur | produces in the preceding combustion chamber 1 fastest when a spark arises by the spark plug 7 mentioned later. The lower surface of the preceding combustion chamber 1 forms the same surface as the lower surface of the cylinder head 3. One side of the preceding combustion chamber 1 is provided with a spark plug 7 as an ignition source.

The preceding combustion chamber 1 is connected to a trailing combustion chamber 11 formed by an upper surface of the piston 8 inserted into the cylinder 9, an inner surface of the cylinder 9 and a lower surface of the cylinder head 3. It communicates through the opening 13. Referring to FIG. 1, the trailing combustion chamber 11 is formed with a predetermined bottom depth only in a part of the upper surface of the piston 8, that is, in the region close to the connection opening 13. The upper surface of the piston 8 except for the region where the trailing combustion chamber 11 is formed is adjacent to the lower surface of the cylinder head 3 while maintaining a constant gap C as shown.

The following combustion chamber 11 is provided with a normal intake and exhaust port (not shown) and an intake and exhaust valve (not shown) for opening and closing the ports, the intake port being fueled outside the cylinder head (3) And a passage of a mixer of fuel and air flowing out of a mixing device (not shown) for mixing air with air.

The connecting opening 13 connects the preceding combustion chamber 1 and the trailing combustion chamber 11 at a position eccentrically from the center line A-A of the cylinder 9 as shown. FIG. 2 shows another embodiment of the connection opening 13 shown in FIG. Referring to Fig. 2, the connecting opening 13a has an opening direction coinciding with the direction in which the flame propagates from the spark plug 7 of the preceding combustion chamber 1, as shown. This is done by obliquely chamfering the edges of the connecting opening 13 formed in FIG. 1, ie the edges of the cylinder head 3 and / or the cylinder 9 to form the connecting path 14. Such a configuration serves to smooth flame flow by expanding the open area of the connection opening 13 when the flame generated from the spark plug 7 propagates from the preceding combustion chamber 1 to the subsequent combustion chamber 11. Improve the thermal efficiency.

In detail, the cross-sectional area size of the connecting opening 13 has an important influence on the flame propagation speed which is transferred from the preceding combustion chamber 1 to the subsequent combustion chamber 11.

In other words, the combustion of the engine is classified into the initial combustion, the main combustion, and the late combustion by time, and if the main combustion speed becomes too fast after the initial combustion in the engine combustion chamber, the temperature and pressure inside the combustion chamber are rapidly increased, resulting in nitrogen oxides (NOx). The generation of harmful exhaust gases such as) is increased.

Therefore, according to the structure of the combustion chamber shown in FIG. 1, the trailing combustion chamber 11 from the preceding combustion chamber 1 is formed by the edge portion of the cylinder head 3 and the cylinder 9 forming the edge of the combustion opening 13. The production of nitrogen oxides can be suppressed because the flame velocity of the furnace is partially blocked, which slows down the combustion rate.

On the other hand, such a configuration may lower the thermal efficiency due to the blocking element of the flame propagation flow between the preceding and following combustion chambers 1 and 11 described above.

A scheme for overcoming this is shown in FIG. That is, when the edges of the cylinder head 3 and the cylinder 9, which are the blocking elements of the flame propagation flow, are removed to form the connection path 14, the flame generated from the preceding combustion chamber 1 is transferred to this connection path 14 ) Propagates smoothly to the following combustion chamber (11). Therefore, the fall of the flame propagation flow rate can be prevented and the heat efficiency can be prevented from falling.

In addition, the above-described technical configuration in which the trailing combustion chamber 11 is formed at a position adjacent to the connecting opening 13 on the upper surface of the piston 8 is typically excessive in the main combustion period which may occur as the combustion chamber length increases. The increase can be suppressed and the fall of thermal efficiency can be prevented.

1 and 2, the operation according to the technical configuration of the present invention described above will be described below.

In the compression stroke of the gas engine according to the present invention, the mixture of air and gaseous fuel flowing into the trailing combustion chamber 11 is connected to the preceding combustion chamber 1 through the connecting opening 13 by the upward movement of the piston 8. Compressed as it enters into the squash (squash) turbulent flow in the preceding combustion chamber (1). Next, when the spark plug 7 generates a spark, the mixer compressed in the preceding combustion chamber 1 is ignited and rapidly propagated to the trailing combustion chamber 11 in the form of a flame.

In detail, the flame propagates toward the piston wall 8a located on the opposite side of the preceding combustion chamber 1 with reference to the center line A-A of the cylinder 9. Thereafter, the flame is dispersed along the upper surface of the piston 8 forming the trailing combustion chamber 11. In this regard, the technical configuration of FIG. 2, which forms the connection path 14 coinciding with the installation direction of the spark plug 7, allows the flame generated by the explosion in the preceding combustion chamber 1 to lag behind the combustion chamber 11 in a short time. It is advantageous to propagate

In particular, the gas engine according to the present invention has the advantage that the initial combustion period that affects the combustion stability in the combustion chamber is shortened. That is, the hemispherical shape of the preceding combustion chamber 1 having the structure of easy flame propagation as described above, and the ignition of the mixer in which the squash turbulent flows in the preceding combustion chamber 1 during the compression movement of the piston 8 shorten the initial combustion period. It becomes a factor. As such, when the initial combustion period is shortened, the combustion stability is increased, and thus, the thermal efficiency of the engine can be expected to increase. In other words, even if the lean combustion or Miller cycle state with high thermal efficiency is applied to the gas engine of the present invention, stable combustion can be performed without difficulty, and thus high thermal efficiency can be expected.

3 to 5 are cross-sectional views showing modifications of the trailing combustion chamber 11 in the combustion chamber structure of the gas engine according to the present invention. The cross-sectional shapes of these trailing combustion chambers all have in common that the bottom depth is gradually formed from a position adjacent to the connecting opening 13a to a position adjacent to the cylinder head 3.

Specifically, the trailing combustion chamber 11 of FIG. 3 has a smooth curved cross section from the position adjacent to the connecting opening 13a to the position adjacent to the cylinder head 3. At this time, the upper surface of the piston 8 except for the region in which the post combustion chamber 11 is formed is adjacent to the lower surface of the cylinder head 3 while maintaining a constant gap C, which is similar to the embodiment of FIG. .

Referring to Fig. 4, the depicted trailing combustion chamber 11 has a straight cross-section inclined from the point adjacent to the connecting opening 13 to the point adjacent to the cylinder head 3. In addition, the trailing combustion chamber 11 of FIG. 5 has a curved cross section from the point adjacent to the connecting opening 13 to the point adjacent to the cylinder head 3. Here, in the cross-sectional shape of the following combustion chamber 11, the upper surface of the piston 8 does not have an area adjacent to the lower surface of the cylinder head 3, unlike FIG.

Meanwhile, referring to FIGS. 1 to 4, the upper surface of the piston 8 except for the region in which the trailing combustion chamber 11 is formed is a constant gap (usually about 1 mm to 2 mm from the lower surface of the cylinder head 3). Spaced apart while maintaining C). In the area forming the gap C and the squash area, flame propagation from the preceding combustion chamber 1 to the subsequent combustion chamber 11 is not properly performed, and thus unburned fuel may be discharged. This may cause a hydrocarbon-based exhaust gas discharge. Therefore, by minimizing this squash region, it is necessary to circulate the fuel concentrated in this region back to the center region of the following combustion chamber 11 to suppress the generation of unburned fuel.

To this end, FIG. 6 shows an embodiment for removing the unburned region of fuel in the embodiment shown in FIG.

That is, referring to FIG. 6, the inclined surface 8b is formed by chamfering an edge portion of the piston 8 forming a boundary portion between the squash region of the piston 8 and the trailing combustion chamber 11 of the piston 8. The state is shown. On the other hand, the technical configuration illustrated in FIG. 6 is not limited to this embodiment only, and those skilled in the art can form the inclined surface on the edge portion of the piston 8 in other embodiments described above, that is, the embodiment shown in FIGS. 3 and 4. The configuration can be considered.

While the invention described above has been described in various embodiments, it should be understood that other embodiments may be derived from this description by changes in size, shape, material and substitution of parts without departing from the spirit thereof. .

As described above, since the gas engine according to the present invention maintains the basic combustion chamber shape of the conventional indirect injection diesel engine, it is not necessary to invest additional production facilities for changing the shape of the combustion chamber. In addition, it is possible to produce a mixed flow of the gas engine and the indirect injection diesel engine according to the present invention has an economic advantage in terms of production equipment investment.

In addition, there is an advantage that the mold cost for the production of the engine can be reduced because it can be used without modifying the mold for manufacturing the cylinder head of the existing indirect injection type diesel engine.

In addition, according to the gas engine according to the present invention, since the initial combustion period is shortened, stable combustion is possible even when the lean combustion or the Miller cycle state is applied, thereby improving thermal efficiency.

In addition, according to the combustion chamber structure of the gas engine according to the present invention, there is an advantage that can suppress the generation of harmful gases due to unburned fuel as much as possible.

Claims (4)

A cylinder head 3 provided with a preceding combustion chamber 1 having an ignition source provided on one side at an eccentric position in its center line A-A, The trailing combustion chamber 11 communicating with the preceding combustion chamber 1 through the connecting opening 11 includes a cylinder 9 having a piston 8 formed in a concave shape at an upper surface thereof. The connection opening 11 is formed on the same plane that the lower surface of the preceding combustion chamber 1 and the upper surface of the subsequent combustion chamber 11 abut, The flame generated by the ignition source propagates from the preceding combustion chamber 1 to the subsequent combustion chamber 11, The edge portion of the cylinder head 3 and the cylinder 9 forming the edge of the connecting opening 13 so that the open cross-sectional area of the connecting opening 13 from the preceding combustion chamber 1 to the subsequent combustion chamber 11 is expanded. The engine characterized in that it is formed obliquely to form a connection path (14), wherein the inclined length of the edge portion of the cylinder head (3) is longer than the inclined length of the edge portion of the cylinder (9). delete The bottom depth of the following combustion chamber (11) is gradually lowered in a direction away from an area adjacent to the connection opening (13), and the upper surface of the piston (8) and the cylinder head (3) Squash region of the piston 8 formed while maintaining a predetermined gap between the lower surface and the edge portion of the piston 8 forming the boundary portion of the trailing combustion chamber 11 of the piston 8 is formed to be inclined. Gas engine, characterized in that the. delete

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