Cylinder Misfire Detection via Exhaust Gas Oxygen Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine misfire detection methods, particularly in multi-cylinder engines, face challenges such as erroneous detection due to high engine speed and light load conditions, and difficulty in identifying paired misfires, especially in V-8, V-10, and V-12 engines, where crankshaft acceleration sensors provide insufficient data.
Innovation Solution
Implementing a system with exhaust gas oxygen sensors that combine the exhaust flows of paired cylinders before mixing with other cylinders' exhaust, allowing for more reliable misfire detection by analyzing the magnitude and phase of the sensor output relative to the engine's firing order, and using a control system to identify specific misfiring cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crankshaft acceleration sensor is used for misfire detection, then misfire detection can be implemented, but detection accuracy deteriorates under high engine speed and light load conditions
Solution Approach 1:
The patent introduces exhaust gas oxygen sensors as intermediary devices that indirectly detect misfire events by measuring oxygen content in exhaust gas. This mediator approach allows detection under conditions where direct crankshaft acceleration measurement fails, particularly at high speeds and light loads where torque pulses are too small to provide reliable signals.
Solution Approach 2:
The patent replaces the mechanical vibration-based detection system (crankshaft acceleration sensor) with a chemical/compositional analysis system (exhaust gas oxygen sensor). This substitution enables detection based on combustion chemistry rather than mechanical dynamics, overcoming the limitations of the mechanical approach at extreme operating conditions.
2Measurement precision
If exhaust gas oxygen sensors are used for misfire detection, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The patent combines exhaust flows from multiple cylinders into shared exhaust manifolds before reaching the oxygen sensors. This merging approach allows a single sensor to monitor multiple cylinders simultaneously, reducing the total number of sensors needed while maintaining detection precision. The combined exhaust gas composition reflects the aggregate combustion state of the monitored cylinders.
3Reliability
If additional sensor information is added to improve detection, then detection capability improves, but exhaust mixing reduces sensor effectiveness
Solution Approach 1:
The patent positions exhaust gas oxygen sensors upstream in the exhaust system, before exhaust from different cylinders fully mixes. This preliminary placement captures exhaust gas composition information from specific cylinder groups before dilution and mixing occur downstream, preserving the diagnostic information needed for accurate misfire detection.
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 misfire detection accuracy, allowing for the identification of both single and paired cylinder misfires, even in complex engine configurations, thereby improving diagnostic capabilities and reducing unnecessary cylinder deactivation.
Implementation Method 1
an exhaust gas sensor mounted in the exhaust in a position to sense exhaust from the first cylinder and second cylinder
Data Source
AI summary
Methods and systems are provided for detection of cylinder misfire in an engine. In one example, a system may comprise a first cylinder and second cylinder of the engine having exhaust flows combined together in an exhaust system before being combined with other cylinders of the engine. The first cylinder and second cylinder may share an exhaust gas sensor mounted in the exhaust in a position to sense exhaust from the first cylinder and second cylinder, and being positioned before exhaust from other cylinders is combined with sensed exhaust from the first cylinder and second cylinder. The system may further include a control system with instructions stored therein to indicate detected misfire in one or more of the first and second sensors based on an output from the exhaust gas sensor.