JPS6017222A - Combustion chamber structure of engine - Google Patents

Abstract

PURPOSE:To prevent the occurrence of knocking as well as to improve a degree of charging efficiency, by forming a guide wall situated more downward than a head part of a suction valve in time of maximum lifting, into a state of being substantially tilted. CONSTITUTION:A guide wall 7, directing suction air to a specified direction, is installed in position along a part of the circumference of a suction valve seat 5. At the guide wall 7, a lower side wall 7a situated more downward than a heat part 6a of a suction valve 6 in time of maximum lifting becomes a curved surface form being substantially tilted against an upper side wall 7b rising steeply. Thus, with the formation of a swirl, the occurrence of knocking is preventable and, what is more, especially in time of high load driving, suction resistance is reduced to some extent whereby a degree of charging efficiency can be well heightened.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a combustion chamber structure of an engine.

(Prior art) Conventionally, a guide wall for directing intake air in a specific direction is provided along a part of the outer periphery of the intake valve seat, and the guide wall 1 guides the intake air to strengthen the swirl and prevent knocking. The engine made & well known.

However, in such an engine, there is a problem that when the intake air amount is large and the load is high, the intake resistance becomes large and the charging efficiency becomes low.

Incidentally, Japanese Patent Application Laid-open No. 6207-1986 is known as prior art.

(Object of the Invention) The present invention has been made in view of the above points, and is an engine having a guide wall for generating swirl, which prevents knocking by generating swirl, and improves charging efficiency by lowering intake resistance. The purpose of this is to provide a combustion chamber structure.

(Structure of the Invention) The present invention relates to an improvement in an engine that is provided with a guide wall that directs intake air in a specific direction along a part of the outer periphery of an intake valve seat.

In order to achieve the above-mentioned object, the present invention is characterized in that, in the engine, the guide wall located below the umbrella portion of the intake valve at the time of maximum lift has a substantially inclined shape. , which aims to improve filling efficiency by lowering intake resistance without impairing the swirl effect.

(Example) An embodiment of the present invention will be described in detail below with reference to the drawings.

In the engine shown in FIGS. 1 and 2, 1 is a cylinder head, and 2 is a recess partially provided in the inner wall of the cylinder head 1 facing the upper surface of a piston (not shown), so that the piston is at the top dead center. A squish zone 3 is formed between the inner wall surface of the cylinder head 1 and the upper surface of the piston at a certain time, with a slight gap between the combustion chamber and the recess 2.

Reference numeral 4 designates an intake port that opens into the recess 2, and an intake valve 6 that is seated on an intake valve seat 5 installed in the intake port is disposed therein.

The inner wall surface of the cylinder head 1 forming the four portions 2 serves as a guide wall 7 that directs intake air in the cylinder circumferential direction along a part of the outer periphery of the intake valve seat 5 to generate a swirl.

The guide wall 7 has a curved surface shape in which a lower wall 7a located below the umbrella portion 6a of the intake valve 6 at the time of maximum lift shown in FIG. 2 is substantially inclined with respect to a steep upper wall 7b. Therefore, when the intake valve 6 is at its maximum lift, swirl is suppressed.

Reference numeral 8 denotes an exhaust port that opens into skin zone B, and is opened and closed by an exhaust valve 9. Reference numeral 10 denotes a mounting portion for a spark plug (not shown) formed in the recess 2.

With the above configuration, during low-load operation, the intake air-fuel mixture introduced into the combustion chamber (recess 2) through the intake port 4 is swirled in the circumferential direction of the cylinder by the guide wall 7, ensuring directionality. Therefore, the swirl of the intake air-fuel mixture is maintained until the point of ignition without attenuation, thereby increasing the combustion rate and increasing the combustion efficiency.

At the same time, by forming the combustion chamber 14 (concave portion 2), high compression can be achieved, further improving combustion efficiency. In this case, since the intake air-fuel mixture is mainly introduced at the beginning of the intake stroke, at the end of the intake stroke when the intake valve 6 is at its maximum lift position, not much swirl is generated and the slope of the lower wall 7a of the guide wall 7 is reduced. Being loose isn't really a problem.

In addition, at the end of the compression stroke, the squish flow generated in the squish zone 3, which is a minute gap formed between the inner wall surface of the cylinder head 1 and the upper surface of the piston, flows into the combustion chamber (
Since it is pushed out toward the recess 2), a vortex is actively formed in the air-fuel mixture in the combustion chamber, thereby improving combustion efficiency.

On the other hand, during high-load operation, when the intake valve 6 reaches its maximum lift position, the lower wall 7a of the guide wall 7 lowers the intake resistance and suppresses swirl, increasing the filling efficiency of the intake air-fuel mixture and increasing the output. is obtained. In this case, unlike the case during low-load operation, the intake air-fuel mixture is sucked in uniformly over the entire suction stroke, so the effect of improving filling efficiency by suppressing swirl is particularly large.

In the above embodiment, the lower wall 7a of the guide wall 7 has a curved shape, but as shown in FIG. 3, the lower wall 7C of the guide wall 7 may have a sloped shape. That is, any substantially inclined shape that can lower the intake resistance may be used.

(Effects of the Invention) Since the present invention is configured as described above, it is possible to prevent the occurrence of knocking due to the generation of swirl, and it is also possible to lower the intake resistance and increase the filling efficiency, especially during high-load operation.

[Brief explanation of drawings]

The drawings illustrate embodiments of the present invention, and FIG. 1 is an explanatory diagram showing the structure of the combustion chamber of the engine, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is a modified example. FIG. 2 is a diagram similar to FIG. 1... Cylinder head, 2... Concavity (
Combustion chamber) 4... Intake port, 5... Intake valve seat, 7... Guide wall, 7a, c...
lower wall

Claims (1)

[Claims] (1) In an engine that is provided with a guide wall that directs intake air in a specific direction along a part of the outer periphery of the intake valve seat, the guide wall located below the umbrella portion of the intake valve at maximum lift is substantially tilted. A combustion chamber structure of an engine characterized by a shaped shape.