Feed Forward Control for Diesel Exhaust Fluid Delivery Pressure Stability
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Solution Overview
Problem
Diesel exhaust fluid delivery systems experience negative pressure spikes due to the operation of dosing valves, which lead to mechanical wear and reduced efficiency, as current feedback control schemes compensate slowly for pressure deviations.
Innovation Solution
Implementing a feed forward pressure control system using an electronic controller that determines a feed forward control value based on pressure disturbances, adjusting the control request to reduce pressure spikes by controlling both the dosing valve and pressure adjustment components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If feedback control schemes are used to compensate for pressure deviations, then pressure stability is improved, but response speed is too slow to effectively reduce pressure spikes
Solution Approach 1:
The feed forward control calculates and applies pressure compensation values before pressure spikes occur by predicting the pressure disturbance based on the dosing request. This preliminary action allows the system to counteract pressure deviations proactively rather than reactively, achieving both fast response and pressure stability.
Solution Approach 2:
The system combines feed forward control with feedback control mechanisms. The feed forward component provides fast predictive compensation, while the feedback component ensures long-term pressure stability. This combination resolves the contradiction by leveraging both predictive and reactive control strategies.
2Productivity
If dosing valves operate to deliver diesel exhaust fluid, then dosing function is achieved, but negative pressure spikes cause mechanical wear and reduced efficiency
Solution Approach 1:
The feed forward control calculates a compensation value based on the dosing request before the dosing valve operates. This preliminary anti-action counteracts the expected pressure disturbance, preventing negative pressure spikes from occurring in the first place, thereby protecting mechanical components from wear while maintaining dosing functionality.
Solution Approach 2:
The system uses the information about upcoming dosing events (which cause harmful pressure spikes) to generate beneficial compensatory control actions. By converting the predictive information about harmful effects into proactive compensation, the system eliminates mechanical wear while preserving the necessary dosing function.
3Manufacturing precision
If system pressure is maintained at desired levels, then dosing accuracy is improved, but pressure deviations occur during dosing operations
Solution Approach 1:
Before dosing operations commence, the feed forward control pre-calculates and applies compensation values based on the dosing request. This preliminary action ensures that pressure is maintained at desired levels throughout the dosing process, preventing deviations that would compromise dosing accuracy.
Solution Approach 2:
The system employs feedback control to monitor actual pressure during dosing operations and makes real-time adjustments to maintain desired pressure levels. This feedback mechanism ensures pressure stability despite the disturbances introduced by dosing valve operations, thereby maintaining dosing accuracy.
Data Source
AI summary
A diesel exhaust fluid (DEF) delivery system and method for operating same. The method includes determining, by an electronic processor, an operating pressure, and receiving, from a pressure sensor of the DEF delivery system, a system pressure. The method further includes determining, by the processor, a dosing request and a pressure disturbance based on the dosing request. The method further includes determining, by the processor, a control request based on the system pressure and the operating pressure, and a feed forward control value based on the pressure disturbance. The method further includes generating, by the processor, an adjusted control request based on the control request based and the feed forward control value. The method further includes controlling, by the processor, a dosing valve of the DEF delivery system based on the dosing request, and a pressure adjustment component of the DEF delivery system based on the adjusted control request.