Dynamic Engine Knock Window Timing for Noise Learning
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Solution Overview
Problem
The existing methods for determining engine knock background noise levels are prone to errors due to changes in noise contributions from fuel injectors and poppet valves as the engine ages, leading to missed or false indications of engine knock, especially under varying operating conditions.
Innovation Solution
The method involves ceasing fuel supply to a cylinder, adjusting the knock window timing to span the closing event of a nearby cylinder, and sampling the knock sensor output to learn and relearn engine knock background noise levels without disrupting active cylinder operations, allowing for robust knock control throughout the engine's life cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the knock window timing is fixed based on initial engine conditions, then the measurement is simple, but the measurement precision deteriorates as the engine ages and noise levels change
Solution Approach 1:
The knock window timing is made dynamic rather than fixed. The controller adjusts the knock window timing based on actual engine operating conditions and observed background noise levels, allowing the measurement system to adapt to engine aging and changing conditions while maintaining measurement precision
Solution Approach 2:
The system changes the timing parameter of the knock window dynamically. By adjusting when the knock window opens and closes based on observed noise contributions from fuel injectors and poppet valves, the system maintains accurate knock detection despite changes in engine background noise characteristics over time
2Measurement precision
If fuel supply is ceased to learn background noise levels, then the measurement precision improves, but the productivity decreases due to interrupted fuel delivery
Solution Approach 1:
Instead of ceasing fuel supply to all cylinders, the system applies the knock window only to specific cylinders (e.g., deactivating cylinders) while maintaining normal operation of other cylinders. This partial application allows background noise learning without completely interrupting fuel delivery and engine productivity
Solution Approach 2:
The system maintains continuous fuel delivery to active cylinders while using deactivated cylinders for background noise measurement. This ensures that the useful action of fuel delivery continues uninterrupted in productive cylinders, while still enabling noise level learning through alternative means
3Measurement precision
If the knock window spans the closing event of another cylinder, then the measurement of total noise contribution improves, but the device complexity increases
Solution Approach 1:
The knock window mechanism is made multi-functional. It serves both as a knock detection window for active cylinders and as a measurement window for capturing noise contributions from other cylinders' closing events, eliminating the need for separate measurement systems
Solution Approach 2:
The system merges the knock detection function with the background noise measurement function by coordinating the knock window timing to span closing events of other cylinders. This combines multiple measurement objectives into a single integrated approach, reducing overall system complexity
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 the detection of engine knock and efficiency in learning background noise levels, enabling accurate assessment even under changing conditions, thus ensuring consistent engine knock control.
Implementation Method 1
The engine knock background noise may include noise from engine bearings, poppet valve opening and closing events, cam rotation, crankshaft rotation, fuel injectors opening and closing, and other sources. The noise sources may cause the engine's block to vibrate
Data Source
AI summary
Methods and systems are disclosed for operating an engine that includes a knock control system that may determine contributions of individual noise sources to an engine background noise level. The contributions of the individual noise sources may be the basis for establishing the presence or absence of knock in one or more engine cylinders.