Fuel Control System Purge Valve Closure for Engine Stability

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Solution Overview

Problem

Existing fuel control systems in internal combustion engines face challenges in managing fuel vapor flow during engine idle, leading to over fueling and potential engine stalling due to the open purge valve, which is not effectively addressed by current control mechanisms.

Innovation Solution

A fuel control system that includes a closing module to command the purge valve closure when engine speed drops below a predetermined idle speed and an exhaust gas oxygen sensor indicates a fuel-rich air/fuel mixture, along with a closed-loop fuel correction module that adjusts fuel injection based on oxygen measurements to maintain a target air/fuel ratio, preventing over fueling and stabilizing engine speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If the purge valve remains open during engine idle, then fuel vapor can be purged into the engine, but over fueling occurs causing engine stalling

Engineering Contradiction:

Improvefuel vapor purge efficiencyVSAvoidengine stability

Core Design Contradiction:

Loss of substanceVSReliability

Solution Approach 1:

The system dynamically adjusts the purge valve state based on real-time engine operating conditions. The ECU monitors engine speed and compares it to a predetermined threshold, transitioning the purge valve from open to closed state when engine speed drops below the threshold during idle operation. This dynamic control prevents over-fueling while maintaining purge functionality during normal operation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses feedback from engine speed sensing to control the purge valve. The ECU continuously monitors engine speed and uses this feedback to determine when to close the purge valve. When engine speed falls below the predetermined threshold, the ECU closes the purge valve to prevent excessive fuel vapor from causing stalling, creating a closed-loop control system that maintains engine stability.

Inventive Principle:

Principle #23Feedback

2Reliability

If the purge valve closes in response to engine speed drop, then engine stability is maintained, but fuel vapor purging is interrupted

Engineering Contradiction:

Improveengine stabilityVSAvoidfuel vapor purging

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system converts the potentially harmful effect of continued purging during low-speed operation into a beneficial control mechanism. By detecting engine speed drop as a harmful condition and responding with purge valve closure, the system prevents the worse outcome of engine stalling. The harmful purging action is converted into a controlled shutdown that protects engine stability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Quantity of substance

If fuel injection is increased to compensate for purge valve closure, then air/fuel mixture is maintained, but complex control mechanisms are required

Engineering Contradiction:

Improveair/fuel mixture ratioVSAvoidcontrol mechanism complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The system merges the purge control function with the existing fuel injection control system. The ECU integrates purge valve status monitoring and engine speed monitoring into its existing control logic, and automatically adjusts fuel injection timing and quantity in response to purge valve closure. This consolidation avoids adding separate complex control mechanisms while maintaining proper air/fuel mixture ratios.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The ECU's existing control system serves multiple functions by automatically adjusting fuel injection in response to purge valve closure. The system uses its inherent capability to monitor engine parameters and control fuel delivery to self-correct the air/fuel mixture ratio without requiring external or additional complex control mechanisms. The existing control infrastructure performs the additional function of compensating for purge valve closure.

Inventive Principle:

Principle #25Self-service

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 solution effectively prevents over fueling by closing the purge valve and adjusting fuel injection, thereby maintaining engine stability and preventing stalling, even when the engine speed falls below target idle speed, ensuring efficient operation.

Implementation Method 1

an exhaust gas oxygen sensor indicates that an air/fuel mixture supplied to the engine is fuel rich relative to a target air/fuel mixture

Methodology Applied

Scientific EffectOxygen sensing:

Data Source

PatentUS9828954B2Fuel control systems and methods for preventing over fueling

Publication Date: 2017.11.28 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A fuel control system for an engine includes a closing module and a purge control module. The closing module commands closing of a purge valve in response an engine speed transitioning from greater than a predetermined speed to less than the predetermined speed while the purge valve is in an open state. The predetermined speed is less than a predetermined target speed of the engine and is greater than zero. The purge control module transitions the purge valve from the open state to a closed state in response to the command.