Inductive Position Encoder for Utility Meters
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Solution Overview
Problem
Existing non-contact methods for reading mechanical odometers, such as those used in utility meters, are either expensive or complex, making them costly to manufacture and maintain, and there is a need for a low-cost, simple solution that does not introduce friction or torque.
Innovation Solution
A non-contact inductive position encoder using a magnetic device and windings arranged to generate sensor signals varying with the relative position of moveable members, employing a Gray code to accurately determine the position of dials without physical contact, utilizing conductor tracks on printed circuit boards for cost-effectiveness and ease of manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact methods such as gold contacting wiper switches brushing on a patterned contact plate are used, then the position of dials can be read electronically, but friction and torque are introduced that cause the meter to under-read
Solution Approach 1:
The patent replaces the mechanical contact system (wiper switches brushing on contact plates) with a non-contact inductive sensing system using windings and magnetic devices. This substitution eliminates physical contact between the reading mechanism and the dial, thereby removing friction and torque that caused measurement errors while maintaining electronic reading capability
2Object-affected harmful factors
If non-contact methods using multiple photodiodes, light pipes, and light emitting diodes are used, then friction and torque are eliminated, but the system becomes expensive
Solution Approach 1:
The patent extracts and eliminates the expensive optical components (multiple photodiodes, light pipes, and light emitting diodes) from the system, retaining only the essential non-contact sensing functionality through a simpler inductive detection approach using windings and magnetic devices, thereby reducing manufacturing cost while maintaining the frictionless operation
Solution Approach 2:
The patent employs inexpensive conductor tracks formed on printed circuit boards as windings instead of expensive optical components. These PCB-tracked windings provide the necessary inductive sensing capability at a fraction of the cost of optical systems, making the solution economically viable for mass production
3Object-affected harmful factors
If non-contact inductive system with embedded resonant targets and multiple coils is used, then friction and torque are eliminated, but the system becomes complicated and difficult to manufacture
Solution Approach 1:
The patent merges the functions of multiple separate coils (excitation and reception) into a single winding structure on the PCB. This unified winding performs both excitation and sensing functions, eliminating the need for multiple discrete coils and their associated mounting, wiring, and alignment procedures, thereby simplifying the overall system while maintaining non-contact operation
Solution Approach 2:
The patent designs the PCB winding to serve multiple functions: it acts as both the excitation source for the magnetic device and the sensor for detecting position changes. This multi-functional design eliminates the need for separate excitation and reception coils, reducing component count and simplifying the system architecture
4Object-affected harmful factors
If non-contact inductive system with multiple coils and complicated excitation circuitry is used, then position can be read without contact, but the manufacturing cost increases
Solution Approach 1:
The patent replaces complex mechanical coil winding processes with automated PCB trace fabrication. The conductor tracks are formed on printed circuit boards using standard PCB manufacturing techniques, which are highly automated and cost-effective, eliminating the labor-intensive and expensive process of manually winding multiple coils
Solution Approach 2:
The patent changes the physical form and material state of the winding from traditional wire-wound coils to planar conductor tracks on PCB. This parameter change enables the use of automated PCB manufacturing processes instead of manual coil winding, significantly reducing labor costs and improving manufacturing efficiency while maintaining the inductive sensing functionality
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 solution provides a cost-effective, reliable method for electronically reading the position of odometer dials, reducing friction and torque, and simplifying the manufacturing process while maintaining high accuracy and resolution.
Implementation Method 1
said magnetic device is operable to interact with said windings such that upon the energisation of one of said second winding and said first windings, there is generated a plurality of sensor signals in the other one of said second winding and said first windings
Data Source
AI summary
An inductive position encoder is described having first and second members which are relatively moveable over a measurement path, a magnetic device mounted on the first member; a plurality of first windings mounted on the second member; and a second winding. The magnetic device is operable to interact with the windings such that upon the energization of either the second winding or the first windings, there is generated a plurality of sensor signals each being associated with a respective one of said first windings and varying with the relative position between said magnetic device and the associated first winding and hence with the relative position between said first and second members. Additionally, the plurality of first windings are arranged along said measurement path so that the sensor signals vary substantially in accordance with a predetermined Gray code.