Internal-combustion engine

Abstract

An internal-combustion engine includes a cylinder, a piston, a spark plug, and a fuel injection device. The piston includes a top surface, a guiding protrusion, and a cavity. The cavity is provided at a position closer to the fuel injection device than the guiding protrusion when viewed from above the top surface of the piston. The guiding protrusion includes a guiding surface to guide the fuel mist toward the spark plug when the fuel mist is injected from the fuel injection device at a first predetermined timing in a compression stroke. The cavity includes a guiding wall portion to guide the fuel mist toward the spark plug when the fuel mist is injected from the fuel injection device at a timing in the compression stroke between the first predetermined timing and a second predetermined timing.

Description

technical field [0001] The present invention relates to an in-cylinder direct-injection internal combustion engine that injects fuel directly into cylinders and ignites and burns a mixture of fuel and air by spark ignition. Background technique [0002] Conventionally, as an internal combustion engine of an in-cylinder direct injection type, for example, an internal combustion engine disclosed in Patent Document 1 is known. This internal combustion engine includes a spark plug facing inside a cylinder from above, a piston reciprocating inside the cylinder, a fuel injection valve injecting fuel into the cylinder from obliquely above, and the like. [0003] A recess is formed on the top surface of the piston from near the center of the piston to near the injection port of the fuel injection valve. The recess is an elliptical recess that is horizontally long in a direction perpendicular to the axial direction of the fuel injection valve in a plan view, and has an elliptical fl...

AI Technical Summary

Problems solved by technology

[0007] According to the internal combustion engine of Patent Document 1, when stratified air-fuel mixture is generated, both the main spray and the sub-spray must be injected into the recess, so the positional relationship between the fuel injection valve and the piston during fuel injection is less restricted. large, so there is a problem that the degree of freedom of the injection timing of the fuel injection valve is low due to this

Therefore, when the injection timing of the fuel injection valve varies among a plurality of cylinders due to variation among products or aging, the generation state of the stratified mixture among the cylinders varies, and thus, the combustion of the stratified mixture Decreased stability of conditions, resulting in reduced combustion efficiency or worsened fuel costs

[0008] In addition, in the case of this internal combustion engine, both the main spray and the sub spray are configured to be flattened when viewed from the side and fan-shaped when viewed from above from the fuel injection valve, and then guided to the wall surface in an arcuate shape. Guided upward, therefore, it is easy to cause spray diffusion, and it is impossible to gather high-concentration air-fuel mixture near the spark plug, which may further reduce the generation efficiency and combustion efficiency of stratified air-fuel mixture, and further worsen fuel costs.

In addition, the sub-spray is injected at a nearly horizontal angle toward the guide wall surface on the side away from the fuel injection valve, and the guide wall surface has a shape extending linearly obliquely upward. Dropletization occurs on the guide wall, so there is a possibility of deposition

In this case, the generation efficiency and combustion efficiency of the stratified mixture may be further reduced, and the fuel cost may be further deteriorated.

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