Electronic Proportioning Valve Feedforward Feedback Control
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Solution Overview
Problem
Traditional electronic proportioning valves for mixing hot and cold water exhibit slow response times and oscillations due to feedback control mechanisms, leading to temperature spikes and instability in mixed water temperature.
Innovation Solution
A water delivery system that employs a controller operating in both feed forward and feedback modes, adjusting hot and cold water valves based on characteristics of the water sources and mixed water, using sensors for temperature and pressure feedback to stabilize the mixed water temperature and flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If feedback control mechanism is used to regulate mixed water temperature, then temperature stability is improved, but response time increases and oscillations occur
Solution Approach 1:
The system performs preliminary action by measuring the temperature of incoming hot and cold water supplies and using this information to proactively adjust valve positions before the water is mixed. This feed-forward approach anticipates temperature changes and adjusts the mixing ratio in advance, eliminating the delay inherent in traditional feedback systems that wait for mixed water temperature to be measured and then respond.
Solution Approach 2:
The system incorporates feedback mechanisms through temperature sensors that continuously monitor the mixed water temperature and supply water temperatures. This feedback information is processed by the controller to make real-time adjustments to valve positions, ensuring temperature stability while working in conjunction with feed-forward control to minimize response time and eliminate oscillations.
2Stability of the object's composition
If feedback control mechanism is used to regulate mixed water temperature, then temperature stability is improved, but temperature spikes and oscillations occur
Solution Approach 1:
By measuring supply water temperatures and calculating the required mixing ratio in advance, the system adjusts valve positions proactively before temperature spikes can occur. This prevents the oscillations that typically result from feedback systems over-correcting temperature deviations.
Solution Approach 2:
The controller acts as an intermediary that processes temperature information from multiple sensors and coordinates valve adjustments to smooth out temperature variations. This intermediate processing layer prevents direct, reactive valve movements that cause oscillations, instead producing gradual, controlled adjustments.
3Device complexity
If traditional proportioning valve is used, then system simplicity is maintained, but response to temperature changes is slow
Solution Approach 1:
The system measures supply water temperatures and calculates the optimal mixing ratio in advance, enabling rapid valve adjustments when temperature changes occur. This preliminary calculation eliminates the slow response characteristic of traditional valves that must wait for temperature deviations to develop before responding.
Solution Approach 2:
The system replaces traditional mechanical proportioning valves with an electronically controlled valve system driven by a microprocessor. This substitution enables faster, more precise valve actuation through electronic signals compared to mechanical mechanisms, significantly improving response speed while maintaining acceptable system complexity.
Data Source
AI summary
An electronic proportioning valve for connection to a cold water source, a hot water source and a mixed water outlet and for providing a mixed water of a desired water temperature and flow rate to the mixed water outlet.