JPS6045735B2 - Engine combustion chamber device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is designed to combust a lean air-fuel mixture in a main combustion chamber having a main intake valve and an exhaust valve by a flame ejected from a sub-combustion chamber having a sub-intake valve and a spark plug through a through hole. The present invention relates to a combustion chamber device for an engine.

This type of engine is designed to operate with a relatively lean mixture in order to reduce harmful components in the exhaust.
Generally, the auxiliary combustion chamber is disposed toward one side of the cylinder axis J in the main combustion chamber, and injects flame toward the other side, that is, the side where the main intake valve and exhaust valve are located.

When the auxiliary combustion chamber is located near the center, the auxiliary combustion chamber is placed near the top of the wedge-shaped main combustion chamber, and the main combustion chamber is defined at the end on the opposite gate side with respect to the cylinder axis. The inner surface of the cylinder head is provided with a horizontal part, a so-called skid part, to prevent knocking.
However, in the conventional main combustion chamber, it is actually difficult to increase the compression ratio due to the shape of the auxiliary combustion chamber or the squishy part, and the good fuel efficiency that should naturally be obtained by burning a diluted mixture is not sufficient. I couldn't get it. In addition, by arranging the auxiliary combustion chamber at the top of the wedge-shaped main combustion chamber, and without providing a squeezing part at the other end, the inner surface of the cylinder head can be viewed from the top in a cross section that includes the auxiliary combustion chamber axis and the cylinder axis. It is possible to increase the compression ratio to 9 or more by forming a gentle slope up to the end of the top surface of the piston at the top dead center.

However, in this case, before the air-fuel mixture existing at the end of the wedge is ignited by the flame, it is adiabatically compressed under the influence of the pressure increase due to the force of the air-fuel mixture near the through hole, becomes high temperature, and self-ignites, resulting in abnormal combustion. So-called knocking is more likely to occur. The present inventor has devised the present invention in order to improve the problems of the conventional engine described above.

An object of the present invention is to provide an engine with a sub-combustion chamber that can operate at a high compression ratio without causing knocking, which has a wedge-shaped main combustion chamber, and which operates with a diluted air-fuel mixture to eliminate harmful components in exhaust gas. To provide a combustion chamber device for an engine that is low in fuel consumption and excellent in terms of fuel consumption.

Another object of the present invention is to provide a combustion engine with a sub-combustion chamber that operates at a high compression ratio of 9 or more, so as to suppress the combustion noise and prevent the occurrence of knocking. Control appropriately. The main combustion chamber configuration, the position of the sub-combustion chamber, the shape of the recess provided on the top surface of the piston, etc. are provided for the combustion chamber device of the engine.

Next, a combustion chamber of an engine according to an embodiment of the present invention will be explained based on the embodiment diagrams in the accompanying drawings. -ru.

1 and 2 are examples of conventional engine combustion chambers having a sub-combustion chamber, and FIG. 3 shows an embodiment of the combustion chamber according to the present invention.

Corresponding parts and positions in FIGS. 1 to 3 are given the same symbols. In the figure, an engine 1 used for automobiles and other applications is composed of a cylinder block 4 consisting of one or more cylinders 3 having a vertically movable piston 2 therein, and a cylinder head 5 above the cylinder block 4.

Each cylinder 3 has a main combustion chamber 8 in its upper part defined by the inner surface of the cylinder head 5 and the top surface of the piston 2, and the main combustion chamber 8 has a main intake valve 7 and an exhaust valve not shown in the figure. A combustion supply device such as a carburetor supplies a lean fuel-air mixture with a larger amount of air than the stoichiometric mixture ratio. Further, the main combustion chamber 8 is provided with a sub-combustion chamber 11 having a sub-intake valve 9 and a spark plug, and a rich mixture is supplied to the sub-combustion chamber 11, and there is a communication between the main combustion chamber 11 and the auxiliary combustion chamber 11. They communicate through holes 13. Further, the sub-combustion chamber 11 is made of a relatively thin cylindrical body made of heat-resistant metal and is insulated from the cylinder head 5.
The bottom portion 11a has a hemispherical or cylindrical shape projecting into the main combustion chamber 8, and the through hole 13 is provided on its side surface at an angle with respect to the axis of the cylindrical body. In the conventional examples shown in Figs. 1 and 2, the presence of corners such as the vicinity of the sub-combustion chamber or the squishy portion shown as 8a poses an obstacle to increasing the compression ratio, which is at most 8.5 or less. The compression ratio was .

Therefore, in the embodiment of the present invention shown in FIG. 3, the inner surface of the cylinder head 5 defining the main combustion chamber 8 has a wedge shape, is offset to the left of the cylinder axis, and a sub-combustion chamber 11 is disposed. It exhibits a gentle slope from the top to the right end, and ends at the end of the top surface of the piston 2 located at the top dead center position. In the embodiment of the present invention, a recess 12 is provided on the top surface of the piston 2 corresponding to the gently inclined inner surface of the cylinder head 5, and the recess 12 has a semicircular shape as shown in FIG. It consists of a portion 12a parallel to the lower surface, a horizontal portion 12b1, and a portion 12c rising toward the end of the main combustion chamber 11.
With this configuration, it is possible to operate the engine at a compression ratio of 9 or higher, and to obtain an engine with excellent fuel consumption without causing knocking.

Furthermore, according to experiments conducted by the inventors, the recess 12 on the piston 2
It has been found that the depth of the auxiliary combustion chamber 11 and the position of the through hole 13 have important effects on fuel consumption and other engine performance.

That is, the ratio of the bore radius D and the depth d of the recess 12 is d/D=0.
．． Knocking occurs below 075 and d/D=0
．． At 125 or higher, the fuel consumption is poor in the lean mixture region. Regarding the position of the auxiliary combustion chamber 8, the ratio of the bore radius D and the distance between the perpendicular line drawn down to the top of the piston from the point where the axial center of the auxiliary combustion chamber 11 passes through its lower end in FIG. 3 is I/ If D=0.5 or more, knocking will occur and the fuel consumption rate will deteriorate, and I/D=0.
．． If it is less than 1, the pressure inside the combustion chamber will suddenly rise during ignition, resulting in problems such as increased combustion noise. The height H of the main combustion chamber has a ratio H/D of 0.25 to the bore radius D.
The best results are obtained if it is within the range of 0.4. Fourth
As shown in the figure, in the embodiment of the present invention, the auxiliary combustion chamber 11
The through hole 13 that communicates the main combustion chamber 8 with the piston recess 1
Three through holes 13 are provided at an angle of 720 from each other in the direction passing through the holes 2, and two through holes 13 facing the opposite side are provided. In order to obtain the effects of the present invention, it is necessary that at least two through holes 13 are oriented toward the piston recess and at least one through hole is formed facing the opposite side. The present invention is 25111ゞ0=0.04~0.2 (Crlld) Volume (Va) of sub-combustion chamber 11 81--1, 1?0=0.0
It is particularly effective when applied to an engine configured to have a Vc of 5 to 0.12.

Here, the clearance volume is the sum of the volumes of the main combustion chamber 8 and the sub-combustion chamber 11 when the piston 2 is at the top dead center. Next, the operation of the present invention will be explained based on an embodiment of the present invention.

A rich mixture is supplied to the auxiliary combustion chamber 11 through the auxiliary intake valve 9, and a lean mixture is supplied to the main combustion chamber 8 from the main intake valve, resulting in an overall lean region with an air-fuel mixture ratio of 17 to 19. is configured to burn at

The rich air-fuel mixture in the sub-combustion chamber 11 is ignited by the spark plug 10, the pressure within the sub-combustion chamber 11 increases, and flame is ejected into the main combustion chamber 8 through the through hole. The injection flame is in the piston recess 1
2, the flame propagates to the edge of the wedge where knocking is likely to occur and burns it before the air-fuel mixture in that area self-ignites, thus effectively preventing the occurrence of knocking, and also prevents the opposite combustion chamber from auxiliary combustion chamber 11. The flame jetting out to the side ignites the air-fuel mixture in that part, thereby making it possible to burn a lean air-fuel mixture relatively quickly at a high compression ratio of 9 or higher without using any means such as swirl in the combustion chamber. . FIGS. 5 and 6 show the difference in engine performance when the piston recess 12 is provided and when it is not provided. As is clear from the figure, the effect of the piston recess 12 on the amount of HC in the exhaust gas and fuel consumption is clear, and the recess is not only effective in preventing the occurrence of knocking, but also improves combustion in the main combustion chamber 8. I understand that it is very effective. Figure 7 shows the auxiliary combustion chamber 11.
This shows the relationship between the location and fuel consumption.

When the I/D is in the range of 0.1 to 0.525, good fuel consumption is shown, but below 0.1, there is a large problem of combustion noise (0.51). On top of that, knocking problems occur. As is clear from the above, according to the engine combustion device according to the present invention, an engine combustion device with a sub-combustion chamber that operates with a lean mixture can operate at a high compression ratio, and the amount of harmful components in the exhaust gas is significantly increased. It is possible to realize an engine that exhibits extremely high fuel consumption without causing any increase in knocking or combustion noise, and achieves the above with a simple structure.

[Brief explanation of the drawing]

1 and 2 show a cross section of an example of an engine combustion chamber having a conventional auxiliary combustion chamber, FIG. 3 is a cross section of an engine combustion chamber according to the present invention, and FIG. 4 is a cross section of an engine combustion chamber according to the present invention. FIG. 5 is a plan view of the top surface of the piston showing the positions of the auxiliary combustion chamber and the through holes using imaginary lines, and FIGS. 5, 6, and 7 are graphs showing the performance of the engine combustion chamber according to the present invention. 7 In the drawing, 1 is the engine, 2 is the piston, 3 is the cylinder, 7 is the main intake valve, 11 is the sub-combustion chamber, 12 is the recess, 13
is a through hole.

Claims (1)

[Scope of Claims] 1. In an engine that supplies a lean air-fuel mixture to a main combustion chamber having a main intake valve and an exhaust valve, and burns the air-fuel mixture in the main combustion chamber with a flame from a through hole in a sub-combustion chamber. , the main combustion chamber is defined in a wedge shape by the inner surface of the cylinder head and the top surface of the piston, and the cross-sectional shape of the inner surface of the cylinder head in a plane including the sub-combustion chamber axis and the cylinder axis is offset to one side from the cylinder head axis. The other side of the cylinder axis of the piston top, that is, the cylinder, has a top portion and a portion that gently slopes toward the other side, and the slope portion ends near the end of the top surface of the piston at the top dead center, and forms a substantially horizontal surface. A concave portion is provided in a portion of the inner surface corresponding to the inclined portion almost up to the end of the piston, and the auxiliary combustion chamber is located near the top of the wedge shape so that at least two of the through holes through which the flame is ejected face the piston concave portion. , and a combustion chamber device for a high compression ratio engine, characterized in that at least one through hole is arranged so as to face the other end. 2 The concave portion of the piston is composed of a portion parallel to the lower surface of the valve and a horizontal surface, and the ratio d/D of the depth d and the bore radius D
2. A combustion chamber device for a high compression ratio engine according to claim 1, wherein the combustion chamber device is configured such that the max. 3. The auxiliary combustion chamber is provided with at least two or more through holes provided so as to face the piston recess, and one through hole oriented toward the reaction side of the auxiliary combustion chamber. Distance l between the perpendicular line and the cylinder axis and bore radius D
The combustion chamber device for a high compression ratio engine according to claim 1, wherein the combustion chamber device is located such that the ratio l/D is in the range of 0.2 to 0.5. 4. When the piston is at top dead center, the ratio H/D of the distance H between the top surface of the piston and the top of the main combustion chamber to the bore radius D is 0.
A combustion chamber device for a high compression ratio engine according to claim 2 or 3, wherein the compression ratio is within the range of 25 to 0.4.