Combustion Chamber Guide Portion for Engine Ignition

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In spark ignited engines, ensuring high ignitability of the air-fuel mixture by positioning it around the ignition plug is challenging, particularly when the piston is at compression top dead center, due to limitations in fuel atomization and mixing time.

Innovation Solution

A combustion chamber structure featuring a piston crown surface with a recessed cavity and guide portions that direct the air-fuel mixture towards the ignition plug, ensuring it is present around the ignition portion during ignition, and a cup-shaped cavity design for smooth flame propagation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fuel injection is performed when the piston is in the vicinity of compression top dead center, then fuel atomization time is reduced, but sufficient mixing of fuel and air cannot be achieved

Engineering Contradiction:

Improvefuel atomization speedVSAvoidfuel-air mixing homogeneity

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The combustion chamber is segmented into multiple regions: a cavity region for fuel injection and initial mixing, and a compression region above the piston for final mixing. This spatial segmentation allows fuel atomization to occur in the cavity while air-fuel mixing continues in the compression space, resolving the contradiction between rapid atomization and sufficient mixing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention utilizes the vertical dimension (cylinder axis direction) to separate fuel injection timing from ignition timing. Fuel is injected into the cavity during the compression stroke, and the air-fuel mixture is guided upward toward the ignition plug located above the piston. This dimensional arrangement allows extended mixing time without compromising atomization speed.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Quantity of substance

If a large cavity diameter is secured to improve mixing time, then the air-fuel mixture may not be properly positioned around the ignition plug

Engineering Contradiction:

Improvefuel-air mixing timeVSAvoidignitability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The guide portion acts as an intermediary structure that transfers the air-fuel mixture from the cavity region to the ignition plug region. This guide structure ensures that even with a large cavity diameter for extended mixing, the mixture is properly directed and concentrated around the ignition plug at the appropriate time, maintaining both mixing time and ignitability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The guide portion is pre-configured to direct the air-fuel mixture toward the ignition plug before ignition occurs. This preliminary positioning ensures that when ignition timing is reached, the air-fuel mixture is already properly positioned around the ignition plug, eliminating the need to compromise cavity size for mixing time.

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If the cavity is positioned directly below the ignition plug, then mixing time is improved, but the air-fuel mixture may not be effectively guided to the ignition area

Engineering Contradiction:

Improvefuel-air mixing timeVSAvoidmixture guidance efficiency

Core Design Contradiction:

Quantity of substanceVSEase of operation

Solution Approach 1:

The guide portion serves as a mediator that connects the cavity positioned below the ignition plug with the ignition area. This guide structure actively directs the air-fuel mixture upward from the cavity to the ignition plug, ensuring that the beneficial extended mixing time from the cavity position is combined with effective mixture guidance to the ignition area.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration enhances ignitability by ensuring the air-fuel mixture is effectively guided to the ignition area, promoting efficient combustion and reducing the risk of pre-ignition, while also facilitating smooth flame spread and residual gas expulsion.

Implementation Method 1

a guide portion... configured to guide an air-fuel mixture within the combustion chamber to the ignition portion

Methodology Applied

Scientific EffectFluid flow guidance:

Implementation Method 2

a cup-shaped cavity design for smooth flame propagation

Methodology Applied

Scientific EffectFlame propagation:

Implementation Method 3

the air-fuel mixture is ignited using an ignition plug

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS11041457B2Combustion chamber structure for engines

Publication Date: 2021.06.22 MAZDA MOTOR CORP

AI summary

A structure of a combustion chamber for an engine includes: a crown surface of a piston; a combustion chamber ceiling surface formed on a cylinder head; and an ignition plug mounted on the combustion chamber ceiling surface, and including an ignition portion disposed in such a way as to face the combustion chamber. The crown surface of the piston includes a cavity which is recessed in a cylinder axis direction in a region including a position below the ignition portion of the ignition plug in a plan view from the cylinder axis direction. A rim portion of the cavity includes a guide portion, raised in the cylinder axis direction with respect to an inner region of the rim portion, interposing the ignition portion when the piston is at a compression top dead center, and configured to guide an air-fuel mixture within the combustion chamber to the ignition portion.