Engine Knock Control via Dynamic Spark Retard and Fluid Injection
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Solution Overview
Problem
Existing methods for controlling engine knock in alcohol-fueled engines often lead to degraded fuel economy and sub-optimal performance, as they bias towards ethanol injection when sufficient ethanol is available, neglecting the benefits of spark retard for better fuel economy or lower emissions.
Innovation Solution
A method that retards ignition spark timing up to a predetermined amount and increases direct injection of a knock control fluid, such as ethanol or gasoline, to address engine knock, while maintaining the spark timing at the predetermined level, optimizing fuel usage based on engine conditions and cost functions like fuel economy or emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ethanol injection is used to address engine knock when sufficient ethanol is available, then engine knock is suppressed, but fuel economy deteriorates
Solution Approach 1:
The system dynamically adjusts the knock control strategy by transitioning from ethanol injection to spark retardation based on real-time ethanol availability detection. When ethanol level drops below a threshold, the controller automatically switches to spark retardation mode, optimizing fuel economy while maintaining knock suppression effectiveness.
Solution Approach 2:
The invention changes the control parameter from ethanol injection quantity to spark timing retardation when ethanol availability changes. This parameter substitution allows the system to maintain knock control functionality while improving fuel economy when ethanol is not available, as spark retardation does not consume additional fuel.
2Loss of energy
If spark retard is used to address engine knock, then fuel economy improves, but engine performance becomes sub-optimal
Solution Approach 1:
The system dynamically selects between spark retardation and ethanol injection based on ethanol availability. When ethanol is sufficient, the system uses ethanol injection to maintain optimal spark timing and engine performance. When ethanol is depleted, it transitions to spark retardation to improve fuel economy, creating a dynamic performance-fuel economy optimization strategy.
Solution Approach 2:
The invention creates a backup control strategy (spark retardation) that replicates the knock suppression function of ethanol injection. This alternative approach ensures that knock control capability is maintained even when the primary method (ethanol injection) is unavailable, while offering improved fuel economy characteristics.
3Reliability
If ethanol injection is biased towards when sufficient ethanol is available, then knock control is effective, but emissions increase
Solution Approach 1:
The system dynamically adjusts the knock control method based on ethanol availability detection. When ethanol is insufficient, the controller automatically switches to spark retardation, which reduces exhaust emissions compared to ethanol injection, while maintaining effective knock control. This dynamic adaptation resolves the emissions issue.
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 improves fuel economy and reduces emissions by judiciously using ethanol and gasoline, determining a break-even point for spark retard versus ethanol injection to minimize fuel losses and maximize engine performance.
Implementation Method 1
The charge-cooling effect of the high octane alcohol fuel
Data Source
AI summary
Methods and systems are provided for improving fluid usage while addressing knock by adjusting the use of spark retard and direct injection of a fluid based on engine operating conditions and the composition of the injected fluid. One or more engine parameters, such as EGR, VCT, boost, throttle position, are coordinated with the direct injection to reduce torque and EGR transients.