JP3498882B2 - In-cylinder direct injection internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection type internal combustion engine.

[0002]

2. Description of the Related Art As a conventional direct injection type internal combustion engine, for example, there is one shown in FIG. 6 (Japanese Patent Laid-Open No. 5-1013).
(See Japanese Patent No. 7). That is, in the configuration disclosed herein, the spark plug 1 is provided at the center of the cylinder head inner wall surface 23, and the peripheral edge 1
4, the fuel injection valves 8 are arranged on the top surface 16 of the piston 11, and the groove 25 is defined by a pair of side wall surfaces 24 extending from the lower side of the spark plug 1 toward the fuel injection valve 8 while gradually expanding. To form. Each groove side wall surface 24 has a concave curved section, and the radius of curvature of the section of each groove side wall surface 24 is gradually increased toward the fuel injection valve 8 side.

[0003]

However, in such a conventional in-cylinder direct injection internal combustion engine, the concave groove side wall surface 24 gradually expands toward the fuel injection valve 8 and at the concave groove side. Since the radius of curvature of the cross section of the wall surface 24 gradually increases toward the fuel injection valve 8, when the fuel spray 10 immediately after the injection having a relatively high fuel density hits the groove 25, the groove 25 is formed.
There is a problem in that the fuel is diffused to the outside and the concentration of fuel on the spark plug 1 becomes relatively weak.

The present invention has been made by paying attention to such a conventional problem, and is a range in which the recess 12 formed on the piston crown surface 16 is substantially opposed to the fuel injection valve 8 to the spark plug 1. By making it an ellipsoidal concave shape that extends to
The purpose is to solve the above problems.

[0005]

In order to solve the above-mentioned problems, the present invention has an intake port and an intake valve of two cylinders each, and a fuel is provided at a peripheral portion of a cylinder head combustion chamber wall between the intake ports. In an in-cylinder direct-injection internal combustion engine in which the tip of the injection valve is exposed in the cylinder head combustion chamber and fuel is directly supplied into the cylinder, the crown shape of the piston that receives fuel spray from the fuel injection valve to the spark plug The shape is such that it has an ellipsoidal recess extending substantially in the opposite direction.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

(First Embodiment) A first embodiment of the present invention will be described with reference to FIG. First, the structure will be described. The fuel injection valve 8 has a substantially conical fuel spray 10 toward the piston crown surface 16 at a predetermined CA at the cylinder head combustion chamber wall peripheral portion 14 between the intake ports 2. Is installed at such a mounting angle and fuel injection direction that the contact area with the piston crown surface 16 is substantially in the range from the fuel injection valve 8 on the piston crown surface 16 to the ignition plug 1. is there. Further, the piston crown surface 16 is formed of a substantially flat surface, and the fuel spray outer shape 10a is formed at a predetermined CA.
Along the line of intersection 15 between the piston and the crown surface 16 of the piston and the line of intersection 15
Is formed to have an ellipsoidal concave portion 12 enclosing.

Next, the operation of the first embodiment will be described. With the above configuration, the fuel spray 10 injected from the fuel injection valve 8 installed on the cylinder head combustion chamber wall peripheral portion 14 between the intake ports 2 has a substantially conical shape, and therefore at a predetermined CA, the fuel spray outline 10a. The shape of the intersection line 15 with which the flat piston crown surface 16 collides is an ellipse.

Further, the recess 12 formed in the piston crown surface 16 extends in an area facing the fuel injection valve 8 to the ignition plug 1, and is an ellipse along the intersection line 15 and including the intersection line 15. Because of the body shape, it is possible to receive the fuel spray 10 of almost the entire body and move it toward the spark plug 1.

Further, since the concave portion 12 has a small radius of curvature near the lower portion of the fuel injection valve 8, even when receiving the fuel spray 10 immediately after injection, which has a relatively high fuel density, the fuel is not diffused to the spark plug 1. Since it can be turned away and the radius of curvature near the bottom of the spark plug 1 is also small, the concentration of the fuel spray 21 that rolls up toward the spark plug 1 can be increased and the ignitability can be improved.

(Second Embodiment) A second embodiment will be described with reference to FIG. In the second embodiment, the shape of the piston crown surface 16 is configured by a substantially flat surface on the intake side and the exhaust side,
In addition, the ridge line 19 is an upward convex portion that is located on the exhaust side of the spark plug 1, and the concave portion 12 is formed in the intake-side flat surface portion 17. Even if the cone angle of 10 is made relatively large, it can be received by the intake side flat portion 17 or can correspond to a wider fuel injection timing.

(Third Embodiment) A third embodiment will be described with reference to FIG. In the third embodiment, the recess has an elliptical shape with the injection port 9 of the fuel injection valve 8 as one of the focal points, whereby the fuel spray 10 received by the recess 12 is directed toward the ignition plug 1 further. You can turn away.

(Fourth Embodiment) A fourth embodiment will be described with reference to FIG. In the fourth embodiment, the concave portion is formed into an ellipsoidal shape with the electrode portion 20 of the spark plug 1 as one of the focal points, thereby increasing the degree of concentration of the fuel spray 21 wound up on the spark plug 1. The ignition performance can be improved.

(Fifth Embodiment) A fifth embodiment will be described with reference to FIG. In the fifth embodiment, the recess has an ellipsoidal shape with the injection port portion 9 of the fuel injection valve 8 and the spark plug electrode portion 20 as the focal point, and the fuel spray 10 received by the recess 12 is further spark plug. Dodge in one direction,
In addition, the degree of concentration of the wound fuel spray 21 on the ignition plug 1 can be increased to improve the ignitability.

[0015]

As described above, according to the present invention, the structure has two intake ports and intake valves for each cylinder, and the cylinder head combustion chamber wall peripheral portion between the intake ports. In an in-cylinder direct injection internal combustion engine in which the tip of a fuel injection valve is exposed in the cylinder head combustion chamber and fuel is directly supplied into the cylinder, a piston crown surface shape for receiving fuel spray has an elliptical concave portion. Because of the shape, it is possible to obtain an effect that the fuel spray received in the concave portion can be directed toward the spark plug with a higher degree of concentration.

In addition to the common effects described above, each of the above-described embodiments has the following effects. In the first embodiment, it is possible to improve the performance by minimizing the change of the piston shape, and in the second embodiment, the fuel injection valve having a comparatively wide spray cone angle and a wide range of fuel injection timing are supported. In the third embodiment, the fuel spray received in the recess can be directed further toward the spark plug, and in the fourth embodiment, the concentration of the fuel spray to be wound up on the spark plug can be increased. Yes, 5th
In the embodiment described above, the fuel spray received in the recess can be further directed toward the spark plug and the degree of concentration of the fuel spray to be wound up on the spark plug can be increased.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a third embodiment of the present invention.

FIG. 4 is a diagram showing a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a fifth embodiment of the present invention.

FIG. 6 is a diagram showing a conventional in-cylinder direct injection internal combustion engine.

FIG. 7 is a diagram showing a conventional in-cylinder direct injection internal combustion engine.

[Explanation of symbols]

1 spark plug 2 intake ports 3 intake valve 4 exhaust ports 5 exhaust valve 6 cylinder head 7 cylinder block 8 fuel injection valves 9 spout part 10 Fuel spray 10a Fuel spray outline 11 pistons 12 recess 13 Combustion chamber 14 Edge of combustion chamber wall 15 lines of intersection 16 Piston crown 17 Air intake side flat surface 18 Exhaust side flat surface 19 ridge 20 Spark plug electrode 21 Roll-up spray 22 Fuel flow 23 Cylinder head inner wall surface 24 Side wall surface 25 groove 26 convex

Front page continuation (51) Int.Cl. ⁷ identification code FI F02M 61/14 F02M 61/14 310S 69/04 69/04 P (58) Fields investigated (Int.Cl. ⁷ , DB name) F02B 23 / 10 F02B 23/08 F02F 3/28 F02M 61/14 310 F02M 69/04

Claims (5)

(57) [Claims] 1. A fuel injection valve having two intake ports for each cylinder and an intake valve, the tip of the fuel injection valve being exposed in the cylinder head combustion chamber at the peripheral portion of the wall of the cylinder head combustion chamber between the intake ports. In an in-cylinder direct injection internal combustion engine that directly supplies the An in-cylinder direct injection internal combustion engine characterized by: 2. The concave portion has an ellipsoidal concave shape along a line of intersection between the piston crown surface and the fuel spray outline at a predetermined crank angle (hereinafter referred to as CA) and including the line of intersection. The in-cylinder direct injection internal combustion engine according to claim 1. 3. The in-cylinder direct injection internal combustion engine according to claim 1, wherein the concave portion has an elliptical concave shape in which the injection port portion of the fuel injection valve is one of the focal points at a predetermined CA. organ. 4. The in-cylinder direct injection internal combustion engine according to claim 1, wherein the concave portion has an elliptical concave shape having an electrode portion of the spark plug as one of focal points in a predetermined CA. . 5. The cylinder according to claim 1, wherein the concave portion has an elliptical concave shape whose focal point is the injection hole portion of the fuel injection valve and the electrode portion of the spark plug at a predetermined CA. Internal direct injection internal combustion engine.