Flow Meter Resolution via Inductive Sensor and Gear Mechanism
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Solution Overview
Problem
Existing target flow meters have reliability and accuracy issues, particularly at lower flow rates, due to the force being proportional to the flow rate squared, resulting in lower resolution at lower flow rates compared to higher flow rates.
Innovation Solution
A flow meter design featuring a flow target, a beam, and a non-contact inductive sensor system where the displacement of a moveable sensor part relative to a static sensor part generates a signal representative of fluid flow rate, with sensitivity decreasing as a function of displacement, allowing for improved resolution at low flow rates by operating partly in a non-linear range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional target flow meter with a pivotable support member is used, then the flow rate can be measured, but the resolution at lower flow rates is poor because the force is proportional to the flow rate squared
Solution Approach 1:
The patent replaces the traditional mechanical pivotable support member with a magnetic coupling system. The flow target is coupled to a drive magnet, and this couples to a drive gear which drives a count clockwork mechanism. This mechanical substitution eliminates the need for a pivotable support member and provides better resolution at low flow rates through the gear mechanism's ability to amplify small movements.
Solution Approach 2:
The patent changes the measurement parameter from direct force measurement (which is proportional to flow rate squared) to rotational displacement measurement through a gear mechanism. The count clockwork mechanism converts the small rotational movements caused by low flow rates into measurable increments, effectively changing how the flow rate is quantified and improving resolution across the entire flow range.
2Measurement precision
If the sensor operates in a linear range, then the response is straightforward, but the resolution at low flow rates remains limited
Solution Approach 1:
The patent employs a dynamic sensor response where the sensitivity varies with displacement. The sensor operates partly in a non-linear range, with sensitivity decreasing as a function of displacement. This dynamic characteristic allows the sensor to provide higher resolution measurements at low flow rates (small displacements) while maintaining functionality across the entire measurement range.
Solution Approach 2:
The count clockwork mechanism performs preliminary action by pre-converting the continuous rotational movement into discrete countable increments before the final measurement is taken. This preliminary conversion of motion into countable units enhances resolution independent of the sensor's linear or non-linear response characteristics.
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
The design enhances the resolution of the flow meter across the range of measurable fluid flow rates, particularly at lower rates, by distributing sensitivity and maintaining accuracy through the use of a resilient arrangement and a non-contact inductive sensor system.
Implementation Method 1
The sensor may be an inductive sensor. One of the static sensor part and the moveable sensor part may comprise at least one primary coil and at least one secondary coil, and wherein the other of the static sensor part and the moveable sensor part may comprise a conductor. The primary coil may be provided with an alternating current which induces an induced current in the secondary coil.
Implementation Method 2
Target flow meters operate on the principle that the drag force acting on a body due to fluid flow is related to the flow rate of the fluid.
Data Source
AI summary
Disclosed aspects relate to a flow meter comprising a flow target arranged to be disposed in a fluid flow path in a conduit; a beam coupled to the flow target and arranged to extend outside of the conduit; a sensor having a moveable sensor part coupled to the beam at a position which in use is outside of the conduit, and a static sensor part, wherein displacement of the moveable sensor part with respect to the static sensor part generates a signal. In use, fluid flow acting on the flow target causes displacement of the moveable sensor part, thereby generating a signal which is representative of the fluid flow rate.