Loop-Powered Shaft Speed Sensor with Analog Output
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Solution Overview
Problem
Current systems require multiple components to monitor shaft rotational speed, increasing size and cost, necessitating a self-contained solution for efficient shaft speed monitoring.
Innovation Solution
A self-contained, loop-powered shaft rotational-speed sensor that uses a magneto-resistive sensor to detect magnetic pulses from a shaft-mounted target, generating a voltage pulse frequency proportional to rotational speed, with a controller circuit converting this to a digital code and a digital-to-analog converter producing a 4-20 mA output current for analog representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate pulse-frequency-output sensor and pulse-frequency-input to analog-output signal-conditioner module are used to generate analog representation of shaft speed, then the shaft speed monitoring function is achieved, but the system size and cost increase
Solution Approach 1:
The patent combines the sensor, controller circuit, digital-to-analog converter, and voltage/current circuit into a single self-contained shaft speed sensor device. This merging of previously separate components (pulse-frequency-output sensor and signal-conditioner module) directly resolves the technical contradiction by achieving shaft speed monitoring while reducing device complexity and component count.
Solution Approach 2:
The integrated sensor device performs multiple functions within a single unit: detecting shaft position, generating pulse frequency output, converting to digital code, producing analog voltage signal, and generating current output. This multi-functionality allows the device to replace multiple separate components while maintaining full shaft speed monitoring capability.
2Measurement precision
If multiple separate components are used for shaft speed monitoring, then the monitoring function is achieved, but the system size increases
Solution Approach 1:
The patent integrates all necessary functional circuits (sensor, controller, DAC, and voltage/current circuit) into a single compact sensor device, eliminating the need for separate mounted components. This directly addresses the volume issue by consolidating what would have been multiple discrete components into one integrated unit.
3Measurement precision
If multiple separate components are used for shaft speed monitoring, then the monitoring function is achieved, but the system cost increases
Solution Approach 1:
The patent consolidates multiple functional components into a single integrated device, reducing the total component count that needs to be sourced, assembled, and tested. This integration directly impacts manufacturing cost by simplifying the supply chain and assembly processes while maintaining full monitoring 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 compact, cost-effective means to monitor shaft speed, reducing component count and enabling efficient communication of rotational speed data through a single, self-powered device, suitable for various systems.
Implementation Method 1
a sensor that detects a shaft mounted target and outputs a voltage pulse frequency proportional to shaft rotational speed
Data Source
AI summary
A 2-wire, loop-powered shaft rotational speed sensor device that outputs a 4-20 mA current in response to the shaft rotational speed. The device is comprised of a sensor (e.g., magnetic, optical) that senses an output from a sensor disk (e.g., magnetic, optical) and outputs a series of voltage pulses whose frequency varies with the shaft rotational speed. A microcontroller measures this pulse frequency and generates a digital code representative of that frequency. A digital-to-analog converter generates an analog waveform in response to the digital code. A loop-powered, voltage-to-current circuit generates the output current in response to the analog waveform.