Electric Machine Sensor Mounting via Axial Magnet Extension
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Solution Overview
Problem
Existing electric machines face challenges in securely mounting Hall sensors close to magnets without compromising compact packaging, which is essential for obtaining a sufficient signal for accurate position detection and high starting torque in brushless DC motors.
Innovation Solution
The electric machine design includes a support structure with a sensor secured to a housing or mid-shield, and a circuit board, with the sensor cooperating with the rotor's magnet to sense its position, allowing the magnet to extend axially beyond the rotor core for improved signal strength and mounting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall sensors are placed close to magnets to obtain sufficient signal, then measurement precision is improved, but device complexity increases due to mounting challenges
Solution Approach 1:
The magnet extends axially beyond the rotor core in the axial dimension, allowing the Hall sensor to be positioned close to the magnet's end face without requiring complex radial mounting arrangements. This dimensional change enables simple planar mounting of the sensor on the stator while achieving the required close proximity for strong signal detection.
2Measurement precision
If the magnet extends axially beyond the rotor core, then signal strength is improved, but volume of the rotor increases
Solution Approach 1:
The magnet extends axially only at the portion where it interacts with the Hall sensor, rather than uniformly increasing the entire magnet volume. This localized extension provides the necessary signal strength at the sensor location while minimizing the overall volume increase of the rotor.
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
This design facilitates inexpensive, reliable, and efficient mounting of Hall sensors close to magnets, enhancing signal strength, reducing labor costs, and improving the performance and quality of electric machines.
Implementation Method 1
A Hall effect sensor is a transducer that varies its output voltage in response to a magnetic field. Hall effect sensors are used for proximity switching, positioning, speed detection, and current sensing applications.
Data Source
AI summary
According to an embodiment of the invention, an electric machine is provided. The machine includes a support structure and a stator secured to the support structure. The machine also includes a rotor rotatably scoured to the support structure. The rotor defines a wall of the rotor. The machine also includes a sensor secured to the support structure and adapted to cooperate with the wall of the rotor to sense the position of the rotor relative to that of the stator.