Piezoelectric Oscillator Mass Flow Control
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Solution Overview
Problem
Existing mass flow measurement and control systems for high-pressure gases require complex, bulky, and expensive hardware, making them inefficient and costly for accurate control of mass flow rates.
Innovation Solution
A method using two piezoelectric oscillators, one upstream and one downstream of a flow orifice, with a temperature sensor, to measure and control the mass flow rate by adjusting the electronic valve through a feedback loop, ensuring a constant mass flow rate under choked flow conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex mechanical mass flow meters (coriolis, diaphragm, rotary, turbine) are used to measure mass flow rate accurately, then measurement precision is improved, but device complexity increases and moving parts are subject to wear
Solution Approach 1:
The patent replaces complex mechanical mass flow meters with a piezoelectric oscillator-based measurement system. The piezoelectric oscillator's resonant frequency changes in response to gas density variations, providing mass flow rate measurement without mechanical moving parts. This substitution eliminates wear issues while maintaining measurement accuracy and reducing device complexity.
Solution Approach 2:
The system measures mass flow rate by detecting changes in the piezoelectric oscillator's resonant frequency parameter. As gas density changes affect the oscillator's frequency, the system translates this frequency parameter into mass flow rate information, providing a simple yet accurate measurement method without complex mechanical structures.
2Measurement precision
If electronic flow meters (thermal, ultrasonic) are used to measure mass flow rate, then measurement precision is improved, but device complexity and cost increase due to significant signal processing hardware requirements
Solution Approach 1:
The patent replaces electronic flow meters with thermal or ultrasonic methods with a piezoelectric oscillator-based system. The oscillator's natural resonant frequency response to gas density provides measurement capability with minimal electronic processing, significantly reducing hardware complexity and cost while maintaining measurement precision.
3Measurement precision
If mechanical mass flow meters with moving parts are used, then measurement precision is improved, but reliability decreases due to wear of moving parts
Solution Approach 1:
The patent eliminates mechanical moving parts by using a piezoelectric oscillator to measure mass flow rate. The oscillator's resonant frequency responds to gas density changes without any mechanical contact or wear, significantly improving system reliability while maintaining measurement accuracy through the frequency-based detection method.
4Productivity
If high-pressure gas flow control systems are implemented, then productivity is improved, but device complexity increases due to the need for accurate flow measurement and control under high pressure
Solution Approach 1:
The patent uses a piezoelectric oscillator-based measurement system combined with electronic valve control to manage high-pressure gas flow. The oscillator provides accurate density-based flow measurement under high pressure without complex mechanical components, while the electronic valve enables precise flow control, together improving productivity with reduced system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate and efficient control of mass flow rates with reduced hardware complexity and cost, maintaining a constant flow rate even under varying pressure conditions.
Implementation Method 1
a piezoelectric oscillator in contact with the gas upstream of the orifice and downstream of the electronic valve
Implementation Method 2
the piezoelectric oscillator has a resonant frequency which is proportional to the density of the gas upstream of the orifice
Implementation Method 3
through an orifice through which, in use, choked flow is arranged to occur
Implementation Method 4
controlling the electronic valve by means of an electronic feedback loop to minimise the difference between the target value and a function of the measured resonant frequency
Implementation Method 5
a temperature sensor, wherein the piezoelectric oscillator has a resonant frequency which is proportional to the density of the gas upstream of the orifice
Data Source
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AI summary
There is provided a method of automatically controlling the mass flow rate of a gas through an orifice through which, in use, choked flow is arranged to occur. The method uses an electronic valve located downstream of a gas source, a piezoelectric oscillator in contact with the gas upstream of the orifice and downstream of the electronic valve and a temperature sensor. The method comprises a) driving the piezoelectric crystal oscillator at a resonant frequency b) measuring the resonant frequency of the piezoelectric oscillator c) measuring the temperature of the gas; and d) controlling the electronic valve in response to the resonant frequency of the piezoelectric oscillator and the temperature of the gas in order to regulate the mass flow rate of gas through said orifice.