Fuel Injection Control for Engine Start-Up

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Solution Overview

Problem

The starting phase of internal combustion engines results in excessive fuel consumption and pollutant emissions due to the need for a rich air-fuel mixture, which is not efficiently managed by existing open-loop control methods, especially before the exhaust gas treatment system reaches operating temperature.

Innovation Solution

A method for controlling fuel injection during engine start-up that determines a setpoint fuel quantity based on the difference between desired and instantaneous engine acceleration, using a richness correction factor and engine coolant temperature, allowing for adaptive fuel injection to match actual engine needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If open-loop control with fixed setpoint is used to ensure reliable engine start-up under all conditions, then start-up reliability is improved, but fuel consumption and pollutant emissions increase excessively

Engineering Contradiction:

Improveengine start-up reliabilityVSAvoidfuel consumption during start-up

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent transitions from fixed open-loop control to dynamic closed-loop control by continuously adjusting the injection setpoint based on real-time feedback from the lambda sensor. The control unit modifies the injection quantity dynamically during the start-up phase based on actual air-fuel mixture measurements, enabling adaptive optimization rather than relying on predetermined fixed values.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements closed-loop control using feedback from a lambda sensor that measures the actual air-fuel ratio during engine start-up. This feedback signal is processed by the control unit to continuously adjust the injection setpoint, creating a self-regulating system that responds to real-time conditions rather than following a predetermined open-loop schedule.

Inventive Principle:

Principle #23Feedback

2Reliability

If rich air-fuel mixture is injected during engine start-up to overcome mechanical friction and ensure ignition, then engine start-up reliability is improved, but pollutant emissions increase due to unburned fuel in exhaust

Engineering Contradiction:

Improveengine start-up reliabilityVSAvoidpollutant emissions during start-up

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The lambda sensor provides real-time feedback on the actual air-fuel ratio during start-up, allowing the control unit to adjust injection quantities dynamically. This closed-loop control prevents excessive fuel injection by continuously monitoring and correcting the mixture composition, thereby reducing unburned hydrocarbons in the exhaust while maintaining reliable start-up.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the injection parameters (quantity and timing) dynamically during the start-up phase based on feedback from the lambda sensor. Instead of maintaining a constantly rich mixture, the system adjusts the air-fuel ratio parameters in real-time to achieve the minimum necessary richness for reliable ignition while minimizing excess fuel that would become pollutants.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If excessive fuel is injected during engine start-up to account for manufacturing dispersions and fuel volatility variations, then adaptability to different conditions is improved, but fuel consumption increases beyond actual engine needs

Engineering Contradiction:

Improveadaptability to manufacturing dispersions and fuel variationsVSAvoidexcessive fuel consumption

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The lambda sensor provides real-time feedback that allows the control system to adapt to actual fuel properties and engine conditions during start-up. Instead of pre-compensating for all possible variations with excessive fuel, the system measures the actual air-fuel ratio and adjusts injection quantities dynamically, achieving adaptability through measurement and correction rather than over-injection.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control system uses the lambda sensor feedback to self-regulate the injection quantity during start-up. The system serves itself by automatically adjusting the fuel injection based on actual conditions without requiring external calibration or manual intervention, thereby optimizing fuel consumption according to real-time engine needs rather than predetermined conservative estimates.

Inventive Principle:

Principle #25Self-service

Data Source

PatentEP2761153B1Control of the injection of fuel upon combustion engine start-up

Publication Date: 2015.09.23 RENAULT SA

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AI summary

A method for controlling the injection of fuel upon start-up of a combustion engine involves a first step of determining a set point quantity of fuel on start up, which is dependent on a difference between a set point acceleration of the engine and an instantaneous acceleration of the engine. The invention also relates to an electronic control unit and to a motor vehicle.