JP3689974B2 - In-cylinder direct fuel injection internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an in-cylinder direct fuel injection internal combustion engine.
[0002]
[Prior art]
A conventional in-cylinder direct fuel injection internal combustion engine is disclosed, for example, in Japanese Patent Laid-Open No. 6-81651 as shown in FIG. In this conventional example, in FIG. 5, 4a is an intake port, 2 is a piston, 20 is an ignition means, 18 is a fuel injection valve, C is fuel spray, and Vf is gas flow in the cylinder.
[0003]
[Problems to be solved by the invention]
However, in such a conventional in-cylinder direct fuel injection internal combustion engine, the intake port is laid out at an angle close to perpendicular to the combustion chamber, and the upper surface of the piston is directed from the fuel injection valve to the ignition means in the latter half of the compression stroke. Since the gas flow is formed so that the fuel directly collides with the piston recess and the fuel is transported to the ignition means by the gas flow, the non-atomized fuel spray reflected from the upper surface of the piston is directly connected to the spark plug. There was a problem that the spark plug smoldered.
[0004]
The present invention has been made paying attention to such a conventional problem, and forms an angle of 0 degree or more and 90 degrees or less counterclockwise with respect to the approach direction from the air flow from the intake port on the upper surface of the piston. By providing a convex portion having a ridge line at a position close to the intake valve side and a concave portion at a position close to the exhaust valve side, the direction of the air flow from the intake port is deflected in the cylinder, An object of the present invention is to provide an in-cylinder direct fuel injection internal combustion engine capable of performing stable combustion by forming an oblique swirl flow and injecting fuel into a recess on the upper surface of a piston.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a combustion chamber defined by the cylinder inner wall surface of the cylinder block, the upper surface of the piston fitted in the cylinder, and the lower surface of the cylinder head, and the upper wall of the combustion chamber. almost a ignition means provided at the center, and an intake port having an intake opening disposed on one side of the cylinder head combustion chamber, the intake valve and the intake opening and the relative opening and closing the intake opening portion of the lower surface the cylinder head Combustion with a four-valve valve arrangement in which there are two exhaust ports each having an exhaust opening disposed on the other side of the cylinder head combustion chamber, two exhaust valves for opening and closing the exhaust opening, and two intake valves. This is a chamber structure, and includes an in-cylinder direct fuel injection valve disposed near the center of two intake openings toward the exhaust opening, and a cylinder center axis on the upper surface of the piston, and the exhaust opening from the intake opening of the combustion chamber Head to the club A convex portion having a plane perpendicular in the parallel to the plane which is rotated by an angle smaller than than 90 degrees above 0 degrees to the cylinder central axis, and edge line closer than the combustion chamber center to the intake opening side line, ridge line thereof And a concave portion provided in the piston crown surface portion extending from the exhaust opening to the exhaust opening side, and the tumble flow formed in the cylinder during the intake stroke is converted into an oblique swirl flow by the concave portion and the convex portion .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
[0007]
1 and 2 are diagrams showing an embodiment of the present invention.
[0008]
First, the structure will be described. As shown in FIG. 1, the ignition plug 2 is provided substantially at the center of the combustion chamber 4, and the intake port 6 is opened to the combustion chamber 4 through two intake valves 5. An exhaust port 15 opens to the combustion chamber 4 via an exhaust valve 14 at a position facing the intake port 6 of the combustion chamber 4. The fuel injection valve 1 is disposed in the middle of the two intake ports below the intake port in the combustion chamber toward the exhaust valve 14.
[0009]
A counterclockwise direction when viewed from the engine upper surface with respect to a plane p perpendicular to the axis extending from the intake valve 5 to the exhaust valve 14 and including the cylinder central shaft 12 on the upper surface of the piston 3 which is fitted in the cylinder block 9 and moves up and down. Is provided with a convex portion 10 having a ridge line m parallel to a virtual plane f rotated 90 degrees or less and close to the intake valve side from the center of the combustion chamber, and a concave portion 13 on the piston upper surface portion extending from the ridge line to the exhaust valve side. ing.
[0010]
Next, the operation of the embodiment of the present invention will be described.
[0011]
As shown in FIG. 3, the air flowing in from the intake valve is directed toward the exhaust valve 14, but is deflected in a direction perpendicular to the virtual plane f in the cylinder due to the unevenness of the upper surface of the piston, and turns obliquely in the cylinder. In the latter half of the compression stroke in which the piston 3 moves upward, fuel is injected from the injection valve 1 toward the exhaust valve 14. The injected fuel 16 is concentrated in the piston recess 13 on the exhaust valve 14 side and obliquely follows the piston upper surface recess 13 from the piston upper surface recess 13 to the piston upper surface protrusion 10 by the oblique swirl flow 18 formed in the cylinder chamber 11 and the combustion chamber 4. And transported to the upper part of the combustion chamber. At this time, the fuel 16 injected from the fuel injection valve 1 is sufficiently vaporized in the piston upper surface recess 13 on the exhaust valve 14 side, and then transported to the vicinity of the spark plug, and the rich mixture 17 is arranged around the spark plug 2. It will be. This enables good lean combustion at low loads.
[0012]
On the other hand, as shown in FIG. 4, during a high load, fuel is injected during the intake stroke in which the piston 3 moves downward. The fuel injected from the fuel injection valve 1 collides with the piston upper surface convex portion 10 by a penetrating force, can diffuse the fuel widely in the cylinder, and the tumble flow 19 is converted into an oblique swirl flow 18 by the piston. Therefore, the fuel is further diffused by the gas flow in the radial direction. As a result, the fuel can be easily diffused without specially providing a means for enhancing the gas flow, and stable combustion can be performed without being affected by cycle fluctuations by homogenizing the air-fuel mixture.
[0013]
【The invention's effect】
As described above, according to the present invention, the configuration is such that the plane on the upper surface of the piston is perpendicular to the axis that includes the cylinder center axis and extends from the intake opening to the exhaust opening, and is greater than 0 degree and about 90 degrees around the cylinder center axis. A convex portion having a ridge line parallel to a plane rotated by a smaller angle and approaching the intake opening side from the center of the combustion chamber, and a concave portion provided in a piston crown surface portion extending from the ridge line to the exhaust opening side ; The tumble flow formed in the cylinder during the intake stroke is converted into an oblique swirl flow by the concave and convex portions, so that stratification of the air-fuel mixture can be established without smoldering the spark plug at low load. The effect that the homogenization of the mixer can be promoted at a high load is obtained.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an embodiment of the present invention.
FIG. 2 is a schematic diagram showing an embodiment of the present invention.
FIG. 3 is a schematic diagram showing the movement of fuel and air-fuel mixture at low load in the embodiment of the present invention.
FIG. 4 is a schematic diagram showing the movement of fuel and air-fuel mixture at high load in the embodiment of the present invention.
FIG. 5 is a view showing a conventional in-cylinder direct fuel injection device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Ignition means 3 Piston 4 Combustion chamber 5 Intake valve 6 Intake port 9 Cylinder block 10 Piston upper surface convex part 11 Cylinder chamber 12 Cylinder central axis 13 Piston upper surface recessed part 14 Exhaust valve 15 Exhaust port 16 Fuel spray 17 Concentrated mixture 18 Swirl flow 19 Tumble flow f Virtual plane m Convex ridgeline

Claims (2)

A combustion chamber defined by the cylinder inner wall surface of the cylinder block, the upper surface of the piston fitted in the cylinder, and the lower surface of the cylinder head, and the ignition provided substantially at the center of the lower surface of the cylinder head serving as the upper wall of the combustion chamber means and the other of said intake port having an intake opening disposed on one side of the cylinder head combustion chamber, an intake valve for opening and closing the intake opening and the intake opening opposite the cylinder head combustion chamber An exhaust port having an exhaust opening disposed on one side of the combustion chamber, a four-valve valve arrangement combustion chamber structure in which two exhaust valves and two intake valves each for opening and closing the exhaust opening are provided. An in-cylinder direct fuel injection valve disposed near the center of one intake opening toward the exhaust opening, and an axis extending from the intake opening of the combustion chamber to the exhaust opening including the cylinder central axis on the upper surface of the piston. Vertical Plane at a parallel to the plane obtained by rotating by the angle the less than greater 90 degrees above 0 degrees to the cylinder central axis, and a convex portion having a ridge line closer than the combustion chamber center to the intake opening side, the exhaust opening from the ridge And a concave portion provided in a piston crown surface portion to the side, and a tumble flow formed in the cylinder during the intake stroke is converted into an oblique swirl flow by the concave portion and the convex portion, and directly in the cylinder Fuel injection internal combustion engine.   2. The direct injection fuel injection internal combustion engine according to claim 1, wherein the fuel is injected from the fuel injection valve at a compression stroke when the load is low and an intake stroke when the load is high.

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