JPH0116967B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for one cylinder in an engine.
The present invention relates to a multi-valve internal combustion engine equipped with two intake valves and two exhaust valves.

[Problems with conventional technology]

Japanese Patent Publication No. 1983-23481 describes the provision of two intake valves and two exhaust valves to the combustion chamber for the purpose of improving engine output, etc. as a prior art.

On the other hand, increasing the compression ratio is effective in improving the thermal efficiency of internal combustion engines, but increasing the compression ratio causes knocking in the low rotation range, so there is a certain limit to increasing the compression ratio. There is. In order to suppress the occurrence of knocking, (1) the air-fuel mixture sucked into the combustion chamber is compressed so that it concentrates at the ignition plug, so that the air-fuel mixture is as rich as possible around the ignition plug; to improve ignitability (first means).

(2) Make the combustion chamber compact and make the distance from the ignition plug to every corner of the combustion chamber, that is, the distance of flame propagation, as short as possible (second measure).

(3) To improve the flame propagation speed and shorten the combustion time by providing as much turbulence as possible to the air-fuel mixture in the combustion chamber (third means).

It is well known that there are other means.

The second means includes applying a swirl when the air-fuel mixture is taken into the combustion chamber;
A squish area may be formed around the combustion chamber, and these may be used in combination. Forming a squish area around the combustion chamber makes the combustion chamber more compact, so is also valid.

However, in the prior art, the inner wall surface of the combustion chamber in which the two intake ports and the two exhaust ports open is divided into a first spherical surface including one intake port and one exhaust port, and a first spherical surface including the other intake port. The second spherical surface containing the exhaust port and the other spherical surface are connected horizontally, and the ignition plug is provided at the joint between the two spherical surfaces. The first spherical surface is divided into a portion of the first spherical surface through which the intake port of the first spherical surface is viewed, and a portion of the second spherical surface through which the other intake port is viewed. The main flow of the intake air-fuel mixture from the other intake port flows into the part of the first spherical surface where the intake port looks into, and the main flow of the intake air-fuel mixture from the other intake port flows into the part of the second spherical surface where the other intake port looks into. The main flow of the intake air-fuel mixture cannot be collected against the spark plug provided at the connecting portion of both spherical surfaces, in other words, the rich air-fuel mixture cannot be collected around the spark plug. It is not possible to achieve the sufficiency of the first means.

Moreover, in the prior art, although a squishing area for the top surface of the piston is formed on the lower surface of the cylinder head in an area outside the combustion chamber, the squishing flow from this squishing area is directed to the spark plug part. Since it is not aimed at the above, it is also insufficient for the third means.

The present invention aims to solve the above-mentioned problems of the prior art and to satisfy the above-mentioned three means.

[Means to solve the problem]

In order to achieve this object, the present invention communicates two intake ports equipped with intake valves and two exhaust ports equipped with intake valves with a combustion chamber recessed in the lower surface of a cylinder head of an engine. In an internal combustion engine in which an ignition plug screwed onto a head is disposed so as to face approximately the center of the cylinder bore in plan view of the combustion chamber, the combustion chamber is located at the center point of the cylinder bore in plan view of the engine. On both sides of the longitudinal center line passing through,
The engine is provided with a planar inner wall surface that extends obliquely upward from the lower surface of the cylinder head toward the center line of the cylinder bore in a side view of the engine; The combustion chamber is formed in a pent-roof shape so as to intersect at a ridge line extending substantially parallel to the longitudinal center line through the center point, and an opening of both intake ports to the combustion chamber is formed on an inclined planar inner wall surface of one side of the combustion chamber. The lower part of the cylinder head includes a region outside the line of intersection between the inclined planar inner wall surface of one of the combustion chambers and the lower surface of the cylinder head; A squish area for the top surface of the piston is formed in a region outside the intersection line between the inner wall surface of the inclined planar shape and the bottom surface of the cylinder head on the other side, and a space facing the combustion chamber is formed on the top surface of the piston. A projecting portion is provided, and the projecting portion is provided with an inclined surface substantially parallel to the inner wall surface of the both inclined planes at a portion corresponding to the inner wall surface of the both inclined planes.

[Operations and Effects of the Invention] The combustion chambers are arranged on both sides of the longitudinal center line passing through the center point of the cylinder bore in a plan view of the engine, and diagonally upward from the lower surface of the cylinder head toward the center line of the cylinder bore in a side view of the engine. The cylinder has a planar inner wall surface extending at an angle, and the upper ends of both of the inclined planar inner wall surfaces intersect at a ridge line extending substantially parallel to the longitudinal centerline through a substantially central point of the cylinder bore. The interior of the combustion chamber is formed in a pent roof shape, and the openings of the intake ports to the combustion chamber are arranged parallel to the longitudinal center line on the inclined planar inner wall surface of one side of the combustion chamber. , unlike in the prior art, one intake port is not separated into the desired part and the other intake port is not separated into the desired part, so the main flow of the air-fuel mixture taken into the combustion chamber from one intake port and the intake air from the other Both the main flow of the air-fuel mixture sucked into the combustion chamber from the port can be compressed so that they are concentrated around the ignition plug located approximately in the center of the cylinder bore, so a rich air-fuel mixture can be created around the ignition plug. Therefore, the first means can be effectively achieved.

Moreover, as mentioned above, the combustion chamber is formed into a pent roof shape, and the region outside the intersection line of the inclined plane inner wall surface on one side of the combustion chamber and the lower surface of the cylinder head, and the inclined plane shape on the other side. By forming squish areas for the top surface of the piston in areas outside the intersection line of the inner wall surface and the lower surface of the cylinder head, and by providing a protrusion that projects into the combustion chamber on the top surface of the piston, Since the combustion chamber including two intake ports and two exhaust ports can be made more compact than in the prior art, the second means can be effectively achieved.

In addition, the area outside the line of intersection between the inclined planar inner wall surface and the lower surface of the cylinder head on one side of the combustion chamber, and the area outside the intersection line between the inclined planar inner wall surface and the lower surface of the cylinder head on the other side. In addition, in addition to forming a tightness area for the top surface of the piston, a portion of the protrusion on the top surface of the piston corresponding to the inner wall surface of the both inclined planes is provided with an inner wall surface of the both inclined planes. By providing an inclined surface that is approximately parallel to
Since the squishing flow from both squeezing areas can be directed toward the spark plug provided in the deepest part of the pent roof type combustion chamber by the inclined surface of the protrusion, the squishing flow can be directed to the entire area of the combustion chamber. Not only can a disturbed state be provided throughout the engine, but also a severe disturbed state can be provided particularly near the ignition plug, and the third means can be effectively achieved.

Therefore, according to the present invention, knocking in a multi-valve internal combustion engine having two intake valves and two exhaust valves in one cylinder can be significantly suppressed by the synergistic effects of the above and the above, and the compression ratio can be increased. Since it is possible to do this, it is possible to further improve the output and reduce the fuel consumption rate in the multi-valve internal combustion engine.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 indicates an in-line three-cylinder internal combustion engine having three cylinders, each cylinder having a cylinder block 4 having a cylinder bore 3 with a built-in piston 2. A cylinder head 5 is fastened to the upper surface, and a combustion chamber 6 is recessed in the lower surface of the cylinder head 5.

The combustion chamber 6 is located at both left and right ends of a longitudinal center line 7 extending in the same direction as the crank axis through the center point of the cylinder bore 3 in a plan view of the engine, and from the lower surface of the cylinder head 5 in a side view of the engine. It has planar inner wall surfaces 9 and 10 that extend obliquely upward toward the center line 8, and
The upper ends of the inner wall surfaces 9 and 10 of both inclined planes are formed in a pent roof shape such that they intersect at a ridge line 11 extending substantially parallel to the longitudinal center line 7 through the substantially center point of the cylinder bore 3. Inside room 6,
An ignition plug 12 screwed onto the cylinder head 5 is visible at approximately the center of the cylinder bore 3 in plan view.

Reference numerals 13 and 14 indicate two intake ports for one combustion chamber 6, and reference numerals 15 and 16 indicate two exhaust ports for one combustion chamber 6, both intake ports 13 and 14 and both exhaust ports. 15 and 16 are provided separately at both left and right ends sandwiching the longitudinal center line 7 in plan view, and both intake ports 13 and 14 are provided in an inclined planar shape on one side 17 of the cylinder head 5 and one of the combustion chambers 6. The exhaust ports 15 and 16 are opened separately and independently on the inner wall surface 9 of the combustion chamber 6, but the exhaust ports 15 and 16 are opened separately on the inner wall surface 10 of the other side of the combustion chamber 6, which has an inclined planar shape. On the side surface 18, they merge into one and are each open.

Further, the openings of both intake ports 13, 14 and both exhaust ports 15, 16 to the combustion chamber 6 are located at orthogonal centers in a direction perpendicular to the longitudinal centerline 7 through the center point of the cylinder bore 3 in a plan view of the engine. line 19
poppet-type intake valves 2 are located at the openings to the combustion chambers 6.
0 and 21 and exhaust valves 22 and 23 are provided, respectively.

The lower surface of the cylinder head 5 includes an area outside the intersection line between the inclined planar inner wall surface 9 on one side of the combustion chamber 6 and the lower surface of the cylinder head 5;
and in a region outside the line of intersection between the inclined planar inner wall surface 10 and the lower surface of the cylinder head 5 on the other side,
Squeezing areas 25 and 26 are formed for the top surface 24 of the piston 2, respectively.

On the other hand, the top surface 24 of the piston 2 is integrally formed with a protrusion 27 of an appropriate height that protrudes toward the combustion chamber 6 . Inclined planar inner wall surfaces 9 and 1
The portion corresponding to 0 is provided with inclined surfaces 28 and 29 formed substantially parallel to the corresponding inclined planar inner wall surfaces 9 and 10, respectively.

Note that the axes 30 and 31 of both the intake ports 13 and 14 are as follows in a plan view of the engine.
They are arranged so as to be inclined in opposite directions to each other across the orthogonal center line 19, and to form a V-shape that widens toward the combustion chamber 6. Further, reference numeral 32 indicates an atmospheric air intake passage 33 from an air cleaner (not shown).
The air from the surge tank 32 is connected to the intake port 1 of each cylinder.
In this case, the length of the intake passage from the surge tank 32 to the opening to the combustion chamber 6 depends on the specific engine. The intake air amount is set to be maximum at the rotation speed. Furthermore, the reference numeral 36 indicates both the intake ports 13 and 14.
This is a fuel injection nozzle for simultaneously supplying fuel to both.

In this configuration, during the intake stroke accompanying the descent of the piston 2, the air-fuel mixture is sucked into the combustion chamber 6 and the cylinder bore 3 from both intake ports 13 and 14. The inflowing air-fuel mixture from both intake ports 13 and 14 flows into the cylinder bore 3 in the directions indicated by arrows 39 and 40 in FIG. 4, and is then guided inward along the circumferential inner wall surface of the cylinder bore 3. As a result, both intake ports 1 turn in opposite directions as shown by arrows 41 and 42 in the figure.
The main flow of the intake air-fuel mixture from the spark plugs 12 and 12
Can be directed around.

In this case, the combustion chamber 6 of both intake ports 13 and 14
By arranging the openings to the inner wall surface 9 of one side of the pent roof-type combustion chamber 6 in the direction of the longitudinal center line 7, the inner diameter or cross-sectional area of the intake ports 13 and 14 can be This allows the chamber to be made larger than if it were configured spherically.

Then, when the intake stroke ends, the intake valves 20 and 21 close, and the compression stroke begins as the piston 2 rises.
At the end of the compression stroke, the protrusion 27 on the top surface 24 of the piston 2 enters the combustion chamber 6 as shown by the two-dot chain line in the figure and reduces the internal volume of the combustion chamber, so the combustion chamber 6 becomes compact. , the distance from the ignition plug 12 to every corner of the combustion chamber becomes shorter.

On the other hand, at the end of the compression stroke, when the top surface 24 of the piston 2 approaches the lower surface of the cylinder head 5, an inclined planar surface on one of the lower surface of the cylinder head 5 and the combustion chamber 6 is formed. and the top of the piston 2. A squishing action occurs at two locations with the surface 24, and a squishing flow is ejected inward from both squishing areas 25 and 26.

In this case, the protrusion 27 on the top surface 24 of the piston 2 has a portion corresponding to the inner wall surfaces 9, 10 of the combustion chamber 6, which are both inclined planes. Parallel slope 2
8 and 29, the two squish flows ejecting inward from the squish areas 25 and 26 are directed toward the slopes 28 and 2.
With the guide action of 9, arrow 3 appears in Figures 3 and 5.
As shown at 7 and 38, after the two squishing flows turn diagonally upward toward the ignition plug 12, the two squishing flows collide with each other, so that a particularly severe disturbance state can be obtained in the vicinity of the ignition plug 12. It can be done.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a plan view of the engine, FIG. 2 is a cross-sectional view of FIG. 1, and FIG.
The figure is an enlarged cross-sectional view of Fig. 1, and Fig. 4 is a cross-sectional view of Fig. 3.
5 is an enlarged sectional view of FIG. 1, and FIG. 6 is a sectional view of FIG. 3. DESCRIPTION OF SYMBOLS 1... Engine, 2... Piston, 3... Cylinder bore, 4... Cylinder block, 5... Cylinder head, 6... Combustion chamber, 7... Longitudinal center line, 8...
... Cylinder bore center line, 9, 10 ... Inclined planar inner wall surface, 11 ... Ridge line, 12 ... Spark plug, 1
3, 14... Intake port, 15, 16... Exhaust port, 24... Piston top surface, 25, 26... Squeeze area, 27... Projection, 28, 29...
...Slope.

Claims (1)

[Claims] 1. Two intake ports equipped with intake valves and two exhaust ports equipped with exhaust valves are connected to a combustion chamber recessed in the lower surface of the cylinder head of the engine, and an ignition plug screwed onto the cylinder head is attached. In an internal combustion engine, the combustion chamber is disposed so as to be located approximately at the center of the cylinder bore in plan view, and the combustion chamber is located on both left and right sides of a longitudinal centerline passing through the center point of the cylinder bore in plan view of the engine. , a planar inner wall surface extending obliquely upward from the lower surface of the cylinder head toward the center line of the cylinder bore in a side view of the engine; The combustion chamber is formed into a pent-roof shape that passes through the center point and intersects with a ridge line that extends substantially parallel to the longitudinal center line, and a slanted planar inner wall surface of one side of the combustion chamber is provided with a hole that connects both intake ports to the combustion chamber. The openings are arranged parallel to the longitudinal centerline, while the lower surface of the cylinder head has an area outside the intersection line of the inclined planar inner wall surface of one of the combustion chambers and the lower surface of the cylinder head. , and a region outside the intersection of the inclined planar inner wall surface and the lower surface of the cylinder head, respectively, to form a tightness area for the top surface of the piston. The projecting portion is provided with a protruding portion that protrudes in the direction, and the protruding portion is provided with an inclined surface substantially parallel to the inner wall surface of the both inclined planar shape at a portion corresponding to the inner wall surface of the both inclined planar shape. Internal combustion engine.