Engine Knock Harmonization via Cylinder Spark Timing Offset
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Solution Overview
Problem
Internal combustion engines face challenges in harmonizing knock across multiple cylinders, leading to inefficiencies and potential damage due to uneven combustion and noise from knock sensors' noisy measurements, which are not effectively addressed by conventional systems that control individual cylinders independently.
Innovation Solution
A system comprising knock sensors and a controller that calculates an average spark timing offset value across multiple cylinders, adjusting each cylinder's spark timing to harmonize knock levels, thereby reducing cylinder-to-cylinder imbalance and improving engine performance and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual cylinder knock control is implemented, then knock in each cylinder can be addressed, but cylinder-to-cylinder combustion variation increases and overall engine performance deteriorates
Solution Approach 1:
The patent combines individual cylinder knock control with harmonization control that considers all cylinders collectively. The control unit adjusts spark timing not only to reduce knock in each cylinder but also to minimize the variation in knock levels across cylinders, merging individual cylinder management with overall engine performance optimization.
Solution Approach 2:
The system dynamically adjusts spark timing parameters based on knock sensor feedback from multiple cylinders. By changing the spark timing parameter in response to measured knock levels and their variations across cylinders, the system achieves both effective knock control and improved overall engine performance.
2Loss of information
If knock sensor measurements are used for control, then valuable feedback on combustion differences is obtained, but measurement noise significantly degrades control accuracy
Solution Approach 1:
The system uses knock sensor measurements as feedback to continuously adjust spark timing. Despite the noisy nature of individual measurements, the feedback mechanism processes signals from multiple cylinders to determine appropriate spark timing adjustments that reduce knock while accounting for measurement variations.
Solution Approach 2:
The knock sensor system serves multiple functions: detecting knock in individual cylinders, providing feedback for individual cylinder control, and enabling harmonization control across all cylinders. This multi-functional use of the measurement system allows the controller to extract useful information despite noise in individual readings.
3Stability of the object's composition
If spark timing is precisely controlled to reduce knock, then combustion stability improves, but system complexity increases
Solution Approach 1:
The control system is segmented into functions that can be implemented with existing engine control unit capabilities. The harmonization control builds upon conventional individual cylinder knock control by adding a layer of comparative analysis across cylinders, rather than requiring a completely new complex control architecture.
Data Source
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AI summary
A system for harmonizing knock in a plurality of cylinders included in an engine, the system comprises a plurality of knock sensors, and a controller coupled to each of the plurality of knock sensors. The controller is configured to receive a plurality of cylinder knock values corresponding to each of the plurality of knock sensors, and receive an average knock value. The controller determines a cylinder spark timing offset value for each cylinder in the plurality of cylinders from the average knock value and the cylinder knock values. The controller determines an average spark timing offset value. The controller also determines an adjusted spark timing value for each of the plurality of cylinders by subtracting the average spark timing offset value from a spark timing value of each of the plurality of cylinders.