Catalyst Protection Control During Engine Cylinder Misfire
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cylinder misfires in internal combustion engines can cause unburned fuel/air mixtures to combust in the catalyst, leading to potentially damaging temperature increases, which conventional systems fail to adequately address.
Innovation Solution
Implementing a system to monitor and count cylinder misfire events, and when the cylinder misfire count exceeds a predetermined threshold count, the system reduces the engine torque limit and operates the cylinder bank in a stoichiometric fuel/air ratio, and operates the particular cylinder bank in a stoichiometric fuel/air ratio to prevent excessive temperatures at the catalyst due to the catalyst during the cylinder misfire event.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine operates with rich fuel/air ratio for performance, then power output is improved, but catalyst temperature increases excessively during misfire events
Solution Approach 1:
The system performs preliminary action by detecting misfire events and switching to stoichiometric operation before excessive catalyst temperatures occur. The controller monitors misfire counts and preemptively changes fueling strategy when misfires are detected, preventing the harmful temperature rise before it happens.
Solution Approach 2:
The system changes the fuel/air ratio parameter from rich to stoichiometric during misfire events. This parameter change directly controls the combustion characteristics and prevents excessive temperature rise in the catalyst while maintaining engine operation.
2Reliability
If misfire detection threshold is set low for early protection, then catalyst protection is improved, but false activation increases reducing engine performance
Solution Approach 1:
The system uses a predetermined threshold count that is less than the maximum misfire count to pre-emptively protect the catalyst. This preliminary action threshold is set to activate protection before severe misfire conditions occur, balancing early protection with avoiding false activations that would unnecessarily reduce performance.
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
Prevents excessively high temperatures at the catalyst by reducing engine torque and adjusting the fuel/air ratio, thereby protecting the catalyst from damage during misfire events.
Implementation Method 1
An engine cylinder misfire typically results in an unburned fuel/air mixture reaching the catalyst, which can then combust in or near the catalyst.
Data Source
AI summary
A vehicle includes an internal combustion engine having at least one cylinder bank, an exhaust system having a catalyst, and an engine control system with a controller configured to perform an operation to protect the catalyst during a cylinder misfire event. The operation includes monitoring and counting a number of cylinder misfires on each cylinder bank, determining if the cylinder misfire count exceeds a predetermined threshold count, and when the cylinder misfire count exceeds the predetermined threshold count in a particular cylinder bank, subsequently (i) setting a reduced engine torque limit and (ii) operating the particular cylinder bank in a stoichiometric fuel/air ratio, to thereby facilitate preventing excessively high temperatures at the catalyst due to the misfire event.