Adaptive NOx Control via Cam Phaser Timing Adjustment
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Solution Overview
Problem
Existing emissions control systems for vehicles are limited in their ability to dynamically adjust NOx levels due to static reference tables, which do not account for varying engine speeds and loads, leading to inefficient NOx reduction.
Innovation Solution
A control system that utilizes a NOx sensor and cam phaser to adjust the rotational position of the exhaust camshaft based on real-time NOx levels, storing optimal positions in a two-dimensional reference table indexed by speed and load values, allowing for dynamic NOx emission control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a static reference table is used to control exhaust gas retention, then the system is simple to implement, but the ability to dynamically adjust NOx levels is limited
Solution Approach 1:
The patent transforms the static reference table into a dynamic control system by continuously adjusting the cam phaser position based on real-time NOx levels from the sensor. The control module dynamically modifies exhaust valve timing to optimize NOx reduction under varying engine conditions, moving from fixed predetermined values to adaptive real-time control.
Solution Approach 2:
The patent implements a feedback control loop where the NOx sensor continuously monitors exhaust gas NOx levels, the control module compares these levels to target values, and adjusts the cam phaser position accordingly. This closed-loop feedback mechanism enables dynamic adaptation to changing engine conditions while maintaining simplicity through automated control.
2Object-generated harmful factors
If exhaust gas retention is increased to reduce NOx, then NOx emissions decrease, but the control precision for maintaining optimal NOx levels is reduced
Solution Approach 1:
The NOx sensor provides continuous feedback on exhaust gas NOx levels, enabling the control module to precisely adjust cam phaser position. This feedback mechanism allows the system to maintain optimal NOx reduction while preventing excessive retention that would harm engine performance, achieving precise control through real-time monitoring and adjustment.
Solution Approach 2:
The system dynamically changes the cam phaser rotational position parameter based on real-time NOx levels and engine operating conditions. By continuously adjusting this critical parameter, the system optimizes exhaust gas retention to achieve precise control over NOx emissions while adapting to varying engine speeds and loads.
3Object-generated harmful factors
If the cam phaser rotational position is adjusted to control exhaust valve timing, then NOx reduction is optimized, but the system complexity increases
Solution Approach 1:
The control system uses the engine's existing operational parameters (speed, load) and the NOx sensor feedback to automatically adjust the cam phaser without requiring complex external control mechanisms. The system serves itself by using readily available data and simple comparison logic to achieve optimized NOx reduction, minimizing added complexity.
Solution Approach 2:
The cam phaser control system serves multiple functions: it optimizes NOx reduction, adapts to varying engine conditions, and maintains simplicity through unified control logic. The same control module that manages engine operation also handles NOx control, eliminating the need for separate complex control systems.
Data Source
AI summary
A control system for adjusting levels of emissions exiting an engine includes a NOx sensor that generates a NOx signal in response to oxides of nitrogen (NOx) in an exhaust gas and a control module that communicates with the cam phaser. The rotational position of the cam phaser controls an actuation time when the camshaft opens the exhaust valve during rotation of the camshaft. The control module further receives the NOx signal, and calculates a NOx level of the exhaust gas based on the NOx signal. The control module compares the NOx level to a predetermined threshold range and adjusts the cam phaser to achieve a rotational position that releases a desired level of NOx from the engine when the NOx level exceeds the predetermined threshold range. The control module further stores the rotational position in a storage device when the NOx level is within the predetermined threshold range.