Engine Control Method for Combustion Stability

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Solution Overview

Problem

Conventional engine systems face challenges in maintaining stable compressed self-ignition combustion during transition states due to changes in in-cylinder properties, leading to instability and discomfort for drivers.

Innovation Solution

An engine controlling method that sets a target torque with a delay time after accelerator operation, preselects combustion modes between flame propagation and compressed self-ignition, and adjusts in-cylinder properties using a controller, spark plug, and injector to ensure accurate target properties are achieved, optimizing both combustion modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If compressed self-ignition combustion is used to improve thermal efficiency, then fuel efficiency is improved, but combustion stability deteriorates in transition states due to in-cylinder property changes

Engineering Contradiction:

Improvethermal efficiencyVSAvoidcombustion stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The controller predicts future in-cylinder properties based on current accelerator opening and sets target values in advance. By performing preliminary prediction and target setting before the transition state occurs, the system prepares appropriate target in-cylinder properties (temperature, EGR rate, etc.) to maintain combustion stability during acceleration transitions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically switches between flame propagation combustion and compressed self-ignition combustion based on predicted in-cylinder properties and target torque requirements. This dynamic combustion mode selection allows the engine to adapt to changing operating conditions, maintaining both efficiency and stability during transition states.

Inventive Principle:

Principle #15Dynamics

2Reliability

If in-cylinder properties are adjusted to maintain combustion stability, then combustion stability is improved, but response time to accelerator operation deteriorates

Engineering Contradiction:

Improvecombustion stabilityVSAvoidresponse time

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The controller performs prediction and target setting in advance based on current accelerator opening, eliminating the need for real-time adjustments during the transition. This preliminary action allows the property adjusting device to be commanded with sufficient lead time, maintaining both stability and responsive vehicle behavior.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control process is divided into distinct phases: prediction based on accelerator opening, target setting for future cycles, and execution by the property adjusting device. This segmentation allows each component to operate optimally without conflicting requirements for simultaneous speed and stability.

Inventive Principle:

Principle #1Segmentation

3Speed

If target torque is set immediately in response to accelerator operation, then response speed is improved, but vehicle behavior becomes abrupt causing driver discomfort

Engineering Contradiction:

Improveresponse speedVSAvoiddriver discomfort

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The controller sets target torque based on predicted future in-cylinder properties rather than immediate accelerator opening. This preliminary calculation smooths the torque response curve, preventing abrupt vehicle behavior while maintaining responsive acceleration that feels natural to the driver.

Inventive Principle:

Principle #10Preliminary action

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 method stabilizes combustion in transition states, improving drivability by smoothing vehicle acceleration and reducing driver discomfort, while maintaining efficient engine operation.

Implementation Method 1

flame propagation combustion in which fuel inside a cylinder is forcibly ignited using a spark plug

Methodology Applied

Scientific EffectSpark ignition: Electric Spark

Implementation Method 2

compressed self-ignition combustion in which fuel inside the cylinder carries out compressed self-ignition without using the spark plug

Methodology Applied

Scientific EffectFuel injection: Injector

Implementation Method 3

compressed self-ignition combustion in which fuel inside the cylinder carries out compressed self-ignition

Methodology Applied

Scientific EffectCompression ignition: Compression

Data Source

PatentUS11635040B1Engine controlling method and engine system

Publication Date: 2023.04.25 MAZDA MOTOR CORP

AI summary

A method of controlling an engine is provided, which includes setting, by a controller, a target torque of the engine in a specific cycle in the future by a given delay time from the present time based on a present accelerator opening. The method includes selecting beforehand, by the controller, combustion in the specific cycle according to the target torque, from flame propagation combustion and compressed self-ignition combustion. The method includes outputting, by the controller, a control signal to a property adjusting device before the specific cycle so that a property inside the cylinder in the specific cycle becomes a property corresponding to the selected combustion. The method includes estimating, by the controller, the property at a timing when an intake valve is closed in the specific cycle. The method includes outputting, by the controller, a control signal corresponding to the estimated property to a spark plug or an injector.