Pulse Frequency Modulation Valve Control for Precise Fluid Mixing
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Solution Overview
Problem
Existing fluid mixing devices for drinks lack precise and rapid feedback control of fluid flow rates, leading to low reproducibility of flavor over time, especially under varying pressure and temperature conditions, and are prone to turbulences and residue formation.
Innovation Solution
A device with valve means that utilize Pulse Frequency Modulation (PFM) to control fluid flow rates continuously, reduce head losses, and maintain the desired mixing ratio by using feedback integral control and feed-forward control, along with quick and precise actuation to prevent residue formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If valve opening time is adjusted to control flow rate, then flow rate can be regulated, but response time of shutters prevents effective feedback control
Solution Approach 1:
The patent replaces the mechanical shutter system with an electronic control system using solenoid valves. The control unit directly actuates the valves electronically based on flow rate sensor feedback, eliminating mechanical shutter inertia and achieving rapid response times for effective closed-loop flow rate control.
Solution Approach 2:
The patent implements a closed-loop feedback control system where flow rate sensors continuously monitor the actual flow rate, and the control unit adjusts valve opening times based on the difference between desired and actual flow rates. This feedback mechanism enables precise flow rate regulation despite variations in operating conditions.
2Productivity
If high operating pressure is used to maintain flow rate, then fluid delivery is ensured, but turbulences and loss of carbonation increase
Solution Approach 1:
The feedback control system continuously monitors flow rate and adjusts valve opening times to maintain the desired flow rate at lower pressures. By precisely controlling the timing of valve openings rather than relying on high pressure, the system achieves consistent fluid delivery while minimizing turbulence and carbonation loss.
Solution Approach 2:
The system uses periodic valve actuation with precisely controlled opening times rather than continuous high-pressure flow. The solenoid valves are opened in controlled pulses timed to deliver the exact required flow rate, reducing continuous high-pressure exposure that causes turbulence and carbonation degradation.
3Measurement precision
If valve shutters are moved frequently to regulate flow, then flow rate control is achieved, but sugar residues accumulate and hinder shutter movement
Solution Approach 1:
The patent replaces mechanical shutters with solenoid-operated valves that have no moving parts exposed to the fluid stream. The solenoid valves use an electromagnetic field to control fluid flow, eliminating the mechanical shutter surfaces where sugar residues would accumulate and cause sticking or binding.
Solution Approach 2:
The patent extracts the fluid-contact moving parts (shutters) from the valve mechanism and replaces them with a non-contact electromagnetic actuation system. This removes the source of residue accumulation problems while maintaining precise flow control capability.
4Ease of operation
If flow rate control is performed by adjusting valve opening time, then some regulation is achieved, but reproducibility of drink flavor deteriorates over time
Solution Approach 1:
The patent implements continuous feedback control where flow rate sensors monitor the actual flow in real-time and the control unit dynamically adjusts valve opening times to maintain the precise syrup-to-water ratio. This closed-loop system compensates for variations in viscosity, temperature, and pressure, ensuring consistent flavor reproduction over time and across different operating conditions.
Solution Approach 2:
The system dynamically adjusts multiple parameters including valve opening time, valve actuation timing, and control signal frequency based on real-time flow rate measurements and operating conditions. This adaptive parameter adjustment maintains precise mixing ratios despite changes in fluid properties or system conditions.
Data Source
AI summary
The device (1) for the mixing of fluids comprises:—a first supply line (3) of a first fluid along which first valve means (4) are arranged, there being provided first control means (5) able to command the opening/closure of the first valve means (4); —at least a second supply line (6) of a second fluid along which second valve means (7) are arranged, there being provided second control means (8) able to command the opening/closure of the second valve means (7); —driving means (20) of the control means (5, 8) which comprise generation means (21, 22) of an impulsive driving signal (23) by pulses able to open the first valve means (4) and/or the second valve means (7) for an impulsive opening time (T-on) and to close the first valve means (4) and/or the second valve means (7) for an impulsive closure time (T-off), wherein the ratio between the impulsive opening time (T-on) and the impulsive closure time (T-off) for each pulse is constant and the pulses have a variable repetition frequency.