Engine Knock Control via Cylinder Air Management
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Solution Overview
Problem
Current engine knock control methods primarily rely on spark retardation to mitigate detonation, which reduces engine efficiency and torque, compromising vehicle performance and fuel economy.
Innovation Solution
A method that detects engine knock, calculates knock density, and performs air management across all engine cylinders by reducing air in knocking cylinders and increasing it in non-knocking cylinders, while maintaining optimal spark timing to optimize performance and efficiency without compromising engine hardware protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spark retardation is used to mitigate engine knock, then engine knock is reduced, but engine efficiency and torque decrease
Solution Approach 1:
The patent changes the control parameter from ignition timing (spark retardation) to air management (intake valve timing and duration). By adjusting when and how long the intake valve remains open, the system controls the amount of air entering the cylinder, thereby managing knock through charge density and composition rather than delaying combustion, thus avoiding torque loss.
Solution Approach 2:
The patent replaces the traditional mechanical/thermal control method (spark timing adjustment) with a gas dynamic control method (air management through variable valve timing). This substitution allows knock control without compromising the combustion efficiency and torque production that result from optimal spark timing.
2Reliability
If spark retardation is used to mitigate engine knock, then engine knock is reduced, but vehicle performance and drivability are compromised
Solution Approach 1:
The system changes from controlling combustion timing to controlling charge composition and density. By managing air intake timing and duration, the system influences knock propensity through charge preparation rather than combustion timing, preserving optimal spark timing and associated torque output.
Solution Approach 2:
The patent implements cylinder-specific air management control, allowing different intake valve timing and duration settings for individual cylinders based on their specific knock conditions. This segmented approach enables precise knock mitigation in affected cylinders while maintaining optimal performance in non-knocking cylinders.
3Reliability
If spark retardation is used to mitigate engine knock, then engine knock is reduced, but fuel economy deteriorates
Solution Approach 1:
The patent transitions from timing-based knock control to air management-based control. By adjusting intake valve timing and duration, the system optimizes charge composition and density to reduce knock propensity while maintaining optimal combustion timing, thereby preserving fuel efficiency that would otherwise be lost to spark retardation.
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 effectively alleviates engine knock while maintaining engine output torque and fuel efficiency, enhancing vehicle performance and drivability while protecting engine hardware.
Implementation Method 1
Knock sensors contain piezoelectric elements that are tuned to the engine knock frequency. Vibrations from the engine knock will vibrate the piezoelectric element, which generates a voltage that can be sent to the engine control unit (ECU).
Data Source
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AI summary
A system and method for controlling a vehicle to implement an engine torque management strategy. The engine torque management strategy implements a sophisticated engine knock control method that alleviates/mitigates the cause of the knock while also optimizing vehicle performance and engine efficiency without compromising engine hardware protection. Whenever suitable, the system and method attempt to reduce the amount of air trapped in a knocking cylinder to reduce its effective compression ratio and to eliminate the knock while keeping the same optimal spark timing for combustion efficiency.