Lean-Side Air-Fuel Ratio Control Using Learned O2 Correction

Solution Overview

Problem

Existing air-fuel ratio control systems for internal combustion engines in outboard motors face challenges in accurately correcting displacements from target ratios, especially when operating conditions or fuel types change, leading to inefficient fuel consumption and operational discomfort.

Innovation Solution

An air-fuel ratio control system that employs an O2 sensor for feedback control, calculates a feedback correction coefficient based on sensor output, and adjusts the fuel injection amount using a learned value to maintain the target air-fuel ratio on the lean side, while also recalculating the learned value when conditions change, ensuring accurate and rapid correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If O2 sensor is used for air-fuel ratio detection, then cost is reduced, but measurement precision is insufficient for lean side ratios

Engineering Contradiction:

ImprovecostVSAvoidair-fuel ratio detection accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The system performs preliminary feedback control at the logical air-fuel ratio to establish a baseline correction coefficient before transitioning to open-loop control at the lean side target ratio. This preliminary action at the logical ratio enables accurate subsequent control at the lean ratio using the pre-calculated learned value.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback control with the O2 sensor to calculate a learned value that compensates for the sensor's limited precision. By repeatedly adjusting the air-fuel ratio based on O2 sensor feedback and storing the correction coefficients as learned values, the system achieves precise lean side control despite the sensor's inherent limitations.

Inventive Principle:

Principle #23Feedback

2Productivity

If learning correction coefficient is calculated early, then productivity is improved, but accuracy may be compromised

Engineering Contradiction:

Improvecalculation speedVSAvoidair-fuel ratio accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The system performs preliminary feedback control at the logical air-fuel ratio to establish a baseline correction coefficient before transitioning to open-loop control at the lean side target ratio. This preliminary action at the logical ratio enables accurate subsequent control at the lean ratio using the pre-calculated learned value.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system periodically recalculates the learned value during operation when conditions change, such as when switching between different hull types or fuel types. This periodic recalculation maintains accuracy without requiring continuous feedback control, balancing speed and precision.

Inventive Principle:

Principle #19Periodic action

3Measurement precision

If feedback control is continuously performed, then air-fuel ratio accuracy is maintained, but energy consumption increases

Engineering Contradiction:

Improveair-fuel ratio accuracyVSAvoidenergy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system performs preliminary feedback control at the logical air-fuel ratio to establish a baseline correction coefficient before transitioning to open-loop control at the lean side target ratio. This preliminary action at the logical ratio enables accurate subsequent control at the lean ratio using the pre-calculated learned value.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically switches between feedback control and open-loop control based on operating conditions. Feedback control is used when calculating or updating the learned value, while open-loop control with the stored learned value is used during normal operation, creating a dynamic control strategy that optimizes energy usage.

Inventive Principle:

Principle #15Dynamics

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

The system effectively corrects air-fuel ratio displacements, improving fuel consumption and operational efficiency by quickly adapting to changes in operating conditions and fuel types, ensuring the actual air-fuel ratio matches the target ratio on the lean side.

Implementation Method 1

an O2 sensor, which is disposed in an exhaust system of the internal combustion engine and varies in output characteristics in a vicinity of a logical air-fuel ratio

Methodology Applied

Scientific EffectOxygen sensing:

Data Source

PatentUS9347391B2Air-fuel ratio control device for internal combustion engine for outboard motor, air-fuel ratio control method, and program product

Publication Date: 2016.05.24 SUZUKI MOTOR CORP

AI summary

An air-fuel ratio control device has an open loop controller which controls an air-fuel ratio to be a target air-fuel ratio, a feedback controller that shifts the target air-fuel ratio to a logical air-fuel ratio, and feedback controls the air-fuel ratio to be the logical air-fuel ratio by using a feedback correction coefficient determined based on an output of an O2 sensor, an average value calculator that calculates an average value of the feedback correction coefficient when the output of the O2 sensor reverses from a lean side to a rich side and from the rich side to the lean side in a feedback control by the feedback controller, and a learned value calculator that calculates a learned value based on the average value at a time when the average value calculated by the average value calculator becomes substantially constant.