Motor Device Magnetic Shielding for Angle Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Motor devices with built-in control systems face errors in detecting the rotational angle of the rotor due to distortion of the magnetic field caused by the magnetic flux from components like choke coils, leading to inaccuracies in rotational angle computation.
Innovation Solution
The motor device incorporates a power source filter with a wall portion that surrounds at least a portion of the filter on the side of the magnetic sensor, preventing interference from leakage flux and ensuring the magnetic sensor detects an ideal magnetic field, thereby reducing errors in rotational angle detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a power source filter (choke coil) is installed on the substrate to reduce electromagnetic noise, then electromagnetic noise is reduced, but the magnetic field from the filter distorts the magnetic field around the sensor magnet, causing errors in rotational angle detection
Solution Approach 1:
A magnetic shielding member (wall portion) is introduced as an intermediary between the power source filter and the sensor magnet. This shielding member blocks the magnetic field lines from the choke coil, preventing them from reaching and distorting the magnetic field around the sensor magnet, thus eliminating the harmful effect while maintaining the electromagnetic noise reduction function
Solution Approach 2:
The housing is divided into two functional regions: a first housing portion that houses the power source filter and a second housing portion that houses the sensor magnet and magnetic sensor. This spatial segmentation isolates the magnetic field sources, reducing mutual interference between the choke coil's magnetic field and the sensor magnet's magnetic field
2Area of stationary object
If the power source filter is positioned close to the sensor magnet on the substrate, then space is saved, but the leakage flux from the filter directly interferes with the magnetic field detection
Solution Approach 1:
The magnetic shielding member (wall portion) is positioned between the power source filter and the sensor magnet to block magnetic field lines. This intermediary structure allows the filter and sensor to remain in close proximity on the substrate while preventing harmful magnetic field interference, thus maintaining compact space utilization without sacrificing detection accuracy
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 configuration enhances the precision of rotational angle detection by minimizing the distortion of the magnetic field around the sensor magnet, ensuring accurate computation of the rotational angle of the motor's rotary shaft.
Implementation Method 1
a magnetic sensor provided on a surface of the substrate on a side of the motor so as to face the sensor magnet, the magnetic sensor generating an electric signal that matches a magnetic field from the sensor magnet
Implementation Method 2
a power source filter provided on the substrate on a side opposite to the motor as one of the various electronic components, the power source filter generating leakage flux
Data Source
AI summary
A motor device that can secure the detection precision of the rotational angle of a motor is provided. A motor device has a motor housing, a heat sink, a motor cover, a motor, and a substrate. An opening portion of the motor housing is covered by the motor cover which is made of a magnetic body such as iron in a roofed tubular shape. A choke coil is provided on a surface of the substrate on the side opposite to the motor. A magnetic sensor is provided on a surface of the substrate on the side of the motor. A housing portion is provided at a roof portion of the motor cover. The choke coil, which is mounted on the substrate, is surrounded by the housing portion.