JPH03182618A - Combustion chamber structure for multiple valve engine - Google Patents

Abstract

PURPOSE:To form a compact combustion chamber and secure an effectively acting squish area by inclining both side intake valves among the three intake valves by the specified angle, and disposing the center intake valve in the approximately vertical state. CONSTITUTION:Side valves 11B, 13B among three intake valves are disposed being inclined by the specified angle so as to form the upper part of a pentagonal roof type combustion chamber 3 by the lower faces of the side valves 11B, 13B. The center valve 12B is disposed in the approximately vertical state so as to form a squish area 6 by the lower face area of the center valve 12B and the upper face of a piston 2. A recessed part 21 forming the lower face part of the combustion chamber 3 is further formed at the center area of the upper surface of the piston 2. The compact combustion chamber 3 can be thus formed, as well as the large squish area 6 acting effectively can be secured to enable highly efficient combustion.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a multi-valve engine that is provided with three intake valves for one cylinder, and in which the three intake valves are directly driven by one camshaft. Regarding combustion chamber structure.

[Prior Art and Its Problems] Recently, in order to improve the intake and exhaust efficiency and obtain high output, especially in four-stroke engines for vehicles, the number of intake and exhaust valves has been increased.

As an example of such a multi-valve engine,
There is a model with three intake valves as disclosed in Japanese Patent No. 34124.

By the way, in a gasoline engine, the shape of the combustion chamber should be made as compact as possible in order to shorten the combustion time by shortening the flame propagation distance during combustion and to prevent knocking during high-load sowing. Furthermore, in order to improve combustion efficiency by promoting the mixing of air and fuel in the combustion chamber (
Preferably, the air-fuel mixture pushed up by the piston during the compression stroke is compressed by the shape of the combustion chamber and generates a vortex (so-called squish).

However, if the intake and exhaust valves are made to have multiple valves as described above,
There is a problem in that the shape of the combustion chamber is regulated by the position of the intake and exhaust valves and the direction in which they operate due to the driving method, making it impossible to achieve a combustion chamber shape with high combustion efficiency. This restriction is particularly significant in a configuration in which all three intake valves are directly driven by one camshaft.

In addition, since the cylinder head side that constitutes the first surface of the combustion chamber is mostly occupied by the Harz surface, only an extremely narrow squish area can be formed, and no effective squish can be produced (according to simulations, only one area to 1
There are also reports that squish effects cannot be obtained within an area of 3% or more.

[Object of the Invention] In view of the above circumstances, the present invention enables a compact combustion chamber to be constructed even in a multi-valve engine in which 93 intake valves per cylinder are directly driven by a single camshaft. An object of the present invention is to provide a combustion chamber structure for a multi-valve engine that makes it possible to secure a squish area for effective operation.

[Structure of the Invention] Therefore, in the combustion chamber structure of the multi-valve engine according to the present invention, by arranging the intake valves on both sides at a predetermined angle among the three intake valves, the upper part of the penta-roof type combustion chamber is formed by using the lower surface of the intake valves. At the same time, the central intake valve is arranged approximately vertically, the lower surface area of the central intake valve and the upper surface of the piston form a squish area, and the lower surface part of the combustion chamber is formed in the central area of the upper surface of the cylinder. A recessed portion is formed.

This allows for a compact combustion chamber, and
We have secured a wide squish area that can be effective.
This enables highly efficient combustion.

[Embodiments of the invention] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a plan equivalent view showing the IILW8 configuration of the combustion chamber structure of a multi-valve engine according to the present invention, and FIG. 2 is a corresponding longitudinal cross-sectional view thereof.

A cylinder head 10 is fixed on the upper side of the cylinder 1, and the cylinder head 10 is reciprocated (
A combustion chamber 3, which will be described in detail later, is formed between C1 and the upper surface of the piston 2 which moves (elevating and lowering).

Three intake boats 11, 12, and 13 branched from the intake passage 14 on the upstream side of the cylinder head 10 are arranged open along the inner wall of the cylinder 1, and Three intake boats 11, 12.1
3, each intake valve IIB, 12B, 13B f Center valve 11B, Sightharz IIB, 13B) or each intake boat 11, 12. Open and close 13 TiT fi!
: It is closed.

Note that 15 in the figure is a fuel injector that injects and supplies fuel into the intake vent B14.

On the upper side of the intake bow 1-11.12° 13 of the cylinder head 10, - intake camshafts 4 are arranged, and each intake valve IIB.

The intake boats 12B and 13B are configured to be opened and closed directly by the rotation of the intake camshaft 4 without using a rocker arm or the like.

In addition, the intake boat 11.1 with the cylinder center as the center of symmetry
Exhaust boats are provided on the opposite side of 2.13, and the exhaust boats equipped with these exhaust boats are the intake Harts IIB, 1.
Like 2B and 13B, it is driven by an exhaust camshaft placed above the cylinder head 1O, but this is not shown.

The intake camshaft 4 is disposed substantially directly above the central intake boat 12, and therefore the center shaft 12B is provided substantially vertically, and its lower surface is substantially horizontal.

Sightharz IIB, 13B is the intake camshaft 4
It is arranged diagonally from approximately to the center of the cylinder, and therefore,
The lower surface of Sightharts IIB and 13B is an inclined surface with a predetermined angle, which is higher on the cylinder center side and lower on the peripheral side, which is the left side in the figure.

The lower surface of the cylinder head 10 forming the upper surface of the combustion chamber 3 is the intake bow) -11, 12, 13 side is the Sight Harz II
The lower surface of B and 13B is formed obliquely with an inclination between the road surface and the exhaust half side (not shown) is formed with an opposite slope of approximately the same angle as this, that is, the upper surface of the combustion chamber is roof-shaped. A so-called penta-roof type combustion chamber is constructed. Incidentally, an ignition plaque 5 (not shown in FIG. 2) is arranged at the center of the cylinder, which is the highest position of the penta-roof shape.

Here, the center valve 1 on the bottom surface of the cylinder head 10
The predetermined area around the center hartz 12B shown by the imaginary line in FIG. When either the piston 2 or the piston 2 is at the top dead center, a so-called squish area 6 is formed in which squish occurs in close proximity to each other at a predetermined distance.

In addition, in the central region of the upper surface of the piston 2 excluding the area where the squish area 6 is formed, there is a recess 21 having a substantially semicircular cross-sectional shape centered on the top of the pentaloof (i.e., the position of the spark plug 5), or a recess 21 along the length of the pentaloof. The recess 21 forms the lower surface of the combustion chamber 3.

The upper surface of the piston 2 on the exhaust boat side from the recess 21 is
It is formed as an inclined surface along the penta-roof-shaped slope of the cylinder head 10, and when the piston 2 is at the top dead center, it approaches a predetermined distance and squish occurs here as well.

By configuring as described above, a compact pentaloof-shaped combustion chamber 3 is formed by the pentaloof-shaped part of the cylinder head 1O and the recess 21 of the piston 2, and the lower surface of the center valve 12B and its surroundings form a compact pentaloof-shaped combustion chamber 3. , it is possible to secure a wide squish area 6 in which an effective squish can be generated toward the combustion chamber.

The squish flow generated by this squish area 6 flows toward the center of the combustion chamber 3 as shown by the arrow in FIG. It is an efficient product that has good ignitability and combustibility without causing problems such as wetting, and effectively works to improve thermal efficiency.

Next, another embodiment of the present invention shown in FIGS. 3 and 4 will be described.

In the figure, 71.72 is an exhaust boat, 71B.

Reference numeral 72B indicates an exhaust exhaust system, and the same reference numerals as those in the first embodiment are given to the other turning function parts, and the explanation thereof will be omitted.

The illustrated embodiment also has a cylinder head 10 similar to the first embodiment.
In this embodiment, the sight valve I
As shown in the plan view of FIG. 5 (A) and the BB cross-sectional view of FIG. A protrusion 22.22 with a gradient along a penta-roof slope of 10 is formed in a protruding manner.

According to this configuration, the squish produced by the squish area 6 does not contribute to stratification of the air-fuel mixture in the cylinder l.
The flow along the inner wall (indicated by the imaginary arrow in the figure) is blocked by the protrusions 22, 22, and an effective squish toward the center of the combustion chamber 3 is obtained.

[Effects of the Invention] According to the combustion chamber structure of the multi-valve engine according to the present invention as described above, even in a multi-valve engine in which 93 intake valves per cylinder are directly driven by a single camshaft, the combustion chamber This makes it possible to make the fuel more compact and to secure a squish area where it can work effectively, making it possible to achieve efficient combustion.

[Brief explanation of drawings]

FIG. 1 is a plan equivalent view showing a schematic configuration of the combustion chamber structure of a multi-valve engine according to the present invention, FIG. 2 is a longitudinal cross-sectional equivalent view thereof,
FIG. 3 is a plan equivalent view showing the schematic configuration of another embodiment;
5(A) is a plan view of the piston, and FIG. 5(B) is a sectional view taken along line BB in FIG. 5(A). l...Cylinder (cylinder) 2...Piston 3...Combustion chamber 4...Intake camshaft (camshaft) 6...
Squish areas 11B, 13B...Sight valves (intake valves on both sides) 12B...Center Harz (center intake valve) 21...
・Concavity

Claims (1)

[Scope of Claims] In a multi-valve engine in which one cylinder is provided with three intake valves, and the three intake valves are directly driven by one camshaft, both sides of the three intake valves are provided. By arranging the intake valves at a predetermined angle at a predetermined angle, the lower surface forms the upper part of the pentaloof-type combustion chamber, and by arranging the central intake valve approximately vertically, there is a squish between the lower surface area of the central intake valve and the upper surface of the piston. A combustion chamber structure for a multi-valve engine, characterized in that a concave portion is formed in the central region of the upper surface of the piston to form a lower surface portion of the combustion chamber.