Engine Controller DFSO Pedal Filtering
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Solution Overview
Problem
During deceleration fuel shut-off (DFSO) mode, vehicle operators with a 'jittery foot' can cause transient throttle blips, leading to misfires and partial burns, which exacerbate exhaust catalyst degradation due to intermittent fuel injection, making it difficult to detect misfires at light cylinder loads and resulting in premature catalyst degradation.
Innovation Solution
Implementing a method to filter operator pedal input during DFSO, requiring sustained pedal input above thresholds for longer durations to confirm driver intent, integrating fuel amounts from transient events, and adjusting thresholds based on catalyst temperature and oxygen load to prevent low-load fuel injections and protect the catalyst from thermal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If transient pedal input is responded to with fuel injection during DFSO, then driver intent may be honored, but catalyst temperature increases and catalyst degradation accelerates
Solution Approach 1:
The system performs preliminary filtering of pedal input signals before triggering fuel injection. By applying a filter that requires sustained pedal input above a threshold for a predetermined duration, the system preemptively prevents transient signals from causing harmful fuel injection events that would damage the catalyst.
Solution Approach 2:
The patent introduces an intermediary filtering mechanism between the pedal input sensor and the fuel injection controller. This intermediary process evaluates the duration and magnitude of pedal signals, acting as a mediator that blocks transient inputs while allowing sustained driver intent to pass through to trigger fuel injection.
2Use of energy by moving object
If DFSO mode is extended for fuel economy, then fuel consumption decreases, but catalyst temperature control becomes more difficult
Solution Approach 1:
The system continuously monitors catalyst temperature and uses this feedback to dynamically adjust the DFSO operation. When catalyst temperature approaches unsafe levels, the system modifies its behavior by requiring longer sustained pedal input or integrating multiple transient events before allowing fuel injection, thereby preventing overheating while maintaining fuel economy benefits.
Solution Approach 2:
The patent implements dynamic control parameters for DFSO operation. The filter threshold and duration requirements are not fixed but adapt based on current engine and catalyst conditions. This dynamic adjustment allows the system to extend DFSO for fuel economy when safe, while automatically relaxing constraints when catalyst temperature requires protection.
3Measurement precision
If misfire detection sensitivity is increased during light load DFSO, then misfires can be detected, but false detections from transient events increase
Solution Approach 1:
The system applies preliminary filtering to pedal input signals before they can trigger fuel injection during DFSO. By requiring sustained input above a threshold for a predetermined duration, the system preemptively prevents transient events from causing both misfire conditions and false misfire detections, thereby improving detection reliability without sacrificing sensitivity.
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 reduces catalyst degradation, prolongs DFSO mode for improved fuel economy, limits misfires and partial burns, and extends the life of the exhaust catalyst by ensuring fuel injection only when driver intent is confirmed, thereby protecting the catalyst from thermal damage.
Implementation Method 1
The extra fuel from a misfire or partial burn can lead to an exothermic reaction at the exhaust catalyst, raising catalyst temperature.
Data Source
AI summary
Methods and systems are provided for protecting an exhaust catalyst from degradation during a DFSO event. Exit from DFSO due to pedal input received from an operator with a jittery foot is averted by filtering the pedal input differently when operating in a DFSO mode as compared to when operating out of the DFSO mode. Exit from DFSO is confirmed after receiving a higher than threshold pedal position input for a sustained period of time, or when an integrated fuel injection amount exceeds a threshold amount.