Conductive Pulse Wheel Layout for Accurate Low-Speed Sensing
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Solution Overview
Problem
Existing vehicle speed measurement systems, particularly for electric bicycles, face challenges in achieving accurate and cost-effective low-speed detection with limited mounting space and require multiple magnets, which are expensive and prone to inaccuracies.
Innovation Solution
A pulse wheel with two different materials, one non-conductive and one conductive, generates signals in a resonant circuit to detect wheel revolutions, allowing for high-resolution speed measurement without expensive magnets, and can be mounted in a space-saving manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnets are used in the pulse wheel to generate detection signals, then the measurement precision is improved, but the manufacturing cost increases
Solution Approach 1:
The patent replaces expensive permanent magnets with inexpensive conductive material areas on the pulse wheel. These conductive areas interact with the resonant circuit to generate detection signals without requiring costly magnetic materials, thereby reducing manufacturing costs while maintaining measurement functionality
Solution Approach 2:
The patent substitutes the magnetic detection system with an electromagnetic resonant circuit system. Instead of using magnets to generate magnetic fields for detection, the invention uses conductive areas on the pulse wheel that interact with a resonant circuit to generate electrical signals, replacing mechanical/magnetic components with an electromagnetic field-based system
2Area of stationary object
If the pulse wheel is mounted close to the brake disc to save space, then the mounting space is reduced, but the reliability of detection may be compromised
Solution Approach 1:
The replacement of magnets with conductive areas and the use of a resonant circuit allows for a more compact mounting arrangement. The electromagnetic field interaction occurs over a shorter distance compared to magnetic field detection, enabling reliable detection signals even when the pulse wheel is mounted in close proximity to the brake disc, thus saving mounting space without compromising detection reliability
3Device complexity
If a single magnet is used for revolution detection, then the device complexity is reduced, but the measurement precision at low speeds deteriorates
Solution Approach 1:
Instead of using a single magnet or single detection point, the patent divides the detection function into multiple conductive areas arranged around the pulse wheel circumference. Each conductive area interacts with the resonant circuit to generate a detection signal, creating multiple measurement points that improve low-speed detection precision while maintaining relatively simple device structure
Solution Approach 2:
The patent employs periodic detection signals generated by the interaction between the rotating conductive areas and the resonant circuit. This periodic signal generation allows for more frequent measurements during rotation, improving the precision of low-speed detection by capturing more data points over the same time period compared to single-magnet systems
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 system provides accurate low-speed detection with improved resolution and reduced costs by using a pulse wheel with alternating conductive and non-conductive materials, enabling efficient installation without competing for space with brake components.
Implementation Method 1
areas with a first material and areas with a second material are arranged alternately with respect to one another on the circumference... the second material is configured to exert an influence on the measuring device... generates signals in a resonant circuit
Data Source
AI summary
Pulse wheel and system for determining the speed of a vehicle based on a revolution measurement of a wheel of the vehicle. The wheel has a wheel axle which is fixed to a frame of the vehicle and a hub which rotates thereon. A brake disc is connected to the hub. A pulse wheel is attached in a rotationally fixed manner in relation to the hub in the installed state. A measuring device determines the revolutions of the pulse wheel. The pulse wheel has a first material which does not influence the measuring device, and a second material, preferably an electrically conductive material, which influences the measuring device. The measuring device is an oscillator which excites an oscillating circuit, the amplitude of which is damped by the movement of the second material in the alternating electromagnetic field of a coil of the oscillator. An evaluation circuit evaluates the change in the voltage of the oscillating circuit and determines the revolutions of the pulse wheel.