Exhaust Pressure Sampling for Engine Misfire Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine misfire detection methods struggle to accurately distinguish between engine acceleration and combustion at higher engine speeds, leading to potential misidentification of misfiring cylinders and inefficient operation of non-misfiring cylinders.
Innovation Solution
A system that samples exhaust pressure only during exhaust valve opening of a cylinder, using a pressure sensor in the exhaust passage, and adjusts cylinder operation based on peak exhaust pressure measurements to differentiate between misfiring and non-misfiring cylinders, thereby reducing false positive indications and improving misfire control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If engine acceleration monitoring is used to detect misfire, then misfire detection is possible, but false positive indications increase at higher engine speeds
Solution Approach 1:
The patent extracts the harmful influence of other cylinders' combustion events by monitoring exhaust pressure only during the exhaust valve opening period of the specific cylinder being tested. This temporal isolation removes the interference from simultaneous combustion in other cylinders, allowing accurate misfire detection even at high engine speeds where combustion events are closely spaced.
Solution Approach 2:
The system performs preliminary action by pre-identifying the exhaust valve opening timing for each cylinder and configuring the monitoring system to sample exhaust pressure only during these predetermined time windows. This advance preparation ensures that when high-speed operation occurs, the system is already configured to automatically isolate each cylinder's exhaust pressure signal, preventing false positives without requiring real-time complex processing.
2Loss of information
If exhaust pressure is sampled continuously throughout the cylinder cycle, then complete pressure data is obtained, but noise from cylinder blow-through increases
Solution Approach 1:
The patent extracts only the relevant portion of exhaust pressure data by sampling exclusively during the exhaust valve opening period. This eliminates the harmful blow-through noise that occurs when the exhaust valve is closed, while still capturing the essential combustion pressure information needed for misfire detection. The sampling window is precisely extracted to match the physically meaningful event period.
3Reliability
If misfire mitigating actions are taken for all cylinders, then reliable misfire control is achieved, but non-misfiring cylinders operate less efficiently
Solution Approach 1:
The patent segments the misfire detection and control process by independently monitoring each cylinder's exhaust pressure during its specific exhaust valve opening period. This per-cylinder segmentation allows the system to identify and treat only the specific cylinder that is misfiring, rather than applying mitigating actions to all cylinders. The segmented approach maintains reliable misfire control while preserving the efficiency of healthy cylinders.
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 approach enhances engine misfire detection accuracy at higher speeds, reduces noise from cylinder blow-through, and allows for more precise misfire control for individual cylinders, leading to improved engine efficiency and reduced false positives.
Implementation Method 1
sampling an exhaust pressure sensor in an exhaust passage of the cylinder
Data Source
AI summary
Systems and methods for improving detection and mitigation of engine misfire are presented. Engine misfire is determined by sampling exhaust pressure of a cylinder only during a time when an exhaust valve of the cylinder is in an open state. If misfire is indicated, an actuator is adjusted to reduce the possibility of misfire during a subsequent cylinder cycle.