Hall Effect Speed Sensor Assembly for Motorcycle
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Solution Overview
Problem
Existing speed sensors for motorcycles and ATVs, particularly those using reed switches and Hall effect sensors, face reliability issues due to delicate moving parts and lack of robustness in harsh environments, such as off-road conditions with shock, water, and mud.
Innovation Solution
A compact, robust Hall effect sensor assembly with protective circuitry is developed, featuring a stainless steel housing, a back-biased integrated circuit Hall effect sensor, and a permanent magnet for enhanced detection, along with a flexible printed circuit and epoxy encapsulation for strain relief and protection against environmental damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a reed switch is used in a hollow metallic housing, then the sensor is compact, but the reliability is insufficient due to delicate moving parts (thin metal reeds)
Solution Approach 1:
The patent replaces the mechanical reed switch with a Hall effect sensor that has no moving parts. The Hall effect sensor uses a semiconductor plate that detects magnetic field changes, eliminating the delicate metal reeds that are prone to failure. This substitution maintains compactness while dramatically improving reliability.
Solution Approach 2:
The patent removes the magnetic reeds from the sensor assembly, extracting the problematic moving parts while retaining the magnetic field detection function through the Hall effect sensor. This extraction eliminates the reliability issues associated with reed switch components.
2Reliability
If a Hall effect sensor is used, then the sensor is more reliable than a reed switch, but it lacks robustness in severe environments without additional protective circuitry
Solution Approach 1:
The patent incorporates protective circuitry that provides beforehand cushioning against voltage excursions and environmental damage. The circuit includes protection elements that are activated before damage can occur, shielding the Hall effect sensor from harmful electrical conditions and enhancing its robustness in severe off-road environments.
3Measurement precision
If the Hall plate is oriented parallel to the target path (transverse-to-target orientation), then the sensor can detect passing targets, but the housing space requirements increase
Solution Approach 1:
The patent orients the Hall plate in a plane that is transverse to the target path, utilizing the magnetic field's three-dimensional nature. This dimensional arrangement allows the sensor to detect targets passing by while maintaining a compact housing, as the magnetic field lines extend through the housing wall rather than requiring large internal space.
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 reliable and durable speed sensing system capable of withstanding severe environments, ensuring accurate wheel speed detection and extended functionality in harsh conditions.
Implementation Method 1
Hall effect sensors include a planar conductor, or Hall plate, along which a current is applied. Variations in the magnetic flux through the plate produce a voltage across the plate that is directly related to the flux density. The magnetic flux density variations can be provided by a magnet that moves past the plate.
Implementation Method 2
A permanent magnet for enhanced detection
Data Source
AI summary
A robust and compact speed sensor assembly that includes a Hall effect sensor with protective circuitry in a compact housing that can be attached to the wheel of a motorcycle in the vicinity of the brake rotor to present the sensor Hall plate in a proper transverse-to-target orientation to detect passing targets, such as the brake rotor mounting bolts or magnets.