Knock Sensor Cylinder Balancing for Engine Fueling
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Solution Overview
Problem
Multi-cylinder engines face issues with uneven fueling and degradation due to unbalanced cylinder performance, leading to engine misfire, decreased efficiency, and stress on components, which existing pressure sensors and fueling systems fail to address effectively.
Innovation Solution
A method for individually adjusting gas flow rates, diesel flow rates, injection timing, and induction timing of each engine cylinder based on outputs from a knock sensor, a knock threshold, and a reference value, using a controller to manage fuel injectors and valves, ensuring balanced cylinder operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual cylinder pressure sensors are used for measuring in-cylinder pressure, then cylinder balancing measurement precision is improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The patent uses knock sensors as intermediary devices to indirectly measure cylinder pressure characteristics. Instead of directly measuring in-cylinder pressure with complex pressure sensors, the knock sensor detects vibration signals that correlate with pressure events, providing a simpler indirect measurement approach that still enables cylinder balancing
Solution Approach 2:
The patent replaces the mechanical/physical in-cylinder pressure sensing system with an acoustic/vibration-based knock sensor system. By substituting direct pressure measurement with vibration analysis, the system achieves comparable measurement capability while reducing device complexity and sensor exposure to harsh in-cylinder conditions
2Measurement precision
If in-cylinder pressure sensors are deployed, then cylinder output measurement accuracy is improved, but reliability decreases due to sensor exposure to high combustion gas pressures and temperatures
Solution Approach 1:
The knock sensor serves as an intermediary that measures cylinder characteristics from the outside, avoiding direct exposure to high-pressure combustion gases. The sensor detects vibration signals transmitted through the engine block, providing reliable indirect measurement without compromising sensor durability
Solution Approach 2:
The patent creates a correlation model that copies in-cylinder pressure information from knock sensor vibration signals. Instead of placing sensors inside the combustion chamber, the system captures external vibrations and processes them to reconstruct cylinder pressure characteristics, maintaining measurement accuracy while improving reliability
3Manufacturing precision
If fueling is individually controlled for each cylinder, then fuel injection precision is improved, but cylinder output balance deteriorates due to degradation and uneven fueling over time
Solution Approach 1:
The patent implements a feedback control system that continuously monitors cylinder output using knock sensors and adjusts fuel injection accordingly. The controller compares measured cylinder characteristics against target values and modifies individual cylinder fueling to compensate for degradation and maintain balance, resolving the instability caused by uneven fueling over time
Solution Approach 2:
The system dynamically adjusts fuel injection parameters for each cylinder based on real-time knock sensor data. Instead of fixed fueling maps, the controller continuously adapts injection timing and quantity to maintain cylinder balance despite degradation, transforming a static fueling system into a dynamic one that self-corrects
4Power
If cylinder output varies and cylinders become unbalanced, then individual cylinder performance may be optimized, but stress on engine components such as crankshaft, bearings, and connecting rods increases
Solution Approach 1:
The knock sensor-based feedback system detects cylinder output variations and adjusts fueling to balance cylinder performance. By maintaining consistent cylinder outputs through continuous monitoring and adjustment, the system prevents the harmful vibrations and stress concentrations that would otherwise damage crankshaft, bearings, and connecting rods
Solution Approach 2:
The system takes preliminary action by detecting and correcting cylinder imbalances before they cause significant component stress. Through continuous monitoring and proactive fuel adjustment, the system prevents unbalanced cylinder operation from developing into a condition that would harm engine components
Data Source
AI summary
Various methods and systems are provided for individually adjusting fueling to cylinders of an engine based on an output of a knock sensor coupled to each cylinder. In one embodiment, a method for a multi fuel engine comprises individually adjusting, for each cylinder of the engine, one or more of a gas flow rate of gaseous fuel, a diesel flow rate of diesel fuel, an injection or induction timing of gaseous fuel, or an injection timing of diesel fuel based on each of an output of an individual knock sensor for each cylinder, a knock threshold for current engine operating conditions, and a reference value of individual cylinder output.