Sensing Device Groove Coupling Magnetic Interference
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Solution Overview
Problem
Existing sensing devices in electronic power steering systems face issues with magnetic field interference between torque and index sensors, which can be exacerbated by the use of ferromagnetic covers, and also suffer from structural integrity problems when using synthetic resin materials for housings.
Innovation Solution
A sensing device design featuring a metal cover with strategically placed grooves to block magnetic interference and a coupling structure using a metal case and synthetic resin housing, where the case is securely assembled without additional components, preventing magnetic field interference and enhancing structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a ferromagnetic cover is used to prevent magnetic field interference between torque sensor and index sensor, then magnetic field interference is reduced, but motor performance deteriorates due to flux flowing to the cover
Solution Approach 1:
The cover is designed with a non-ferromagnetic material structure where only specific local regions (the first and second covers) are made of non-ferromagnetic material, while other parts can use ferromagnetic materials. This localized application of material properties prevents magnetic field interference in critical areas without causing flux leakage that would harm motor performance elsewhere.
Solution Approach 2:
A non-ferromagnetic cover is introduced as an intermediary component between the torque sensor and index sensor to block magnetic field interference, and between the magnets and Hall sensors to prevent unwanted magnetic flux paths. This intermediary structure protects the sensing system without interfering with motor operation.
2Ease of manufacture
If a case is fixed to housing using heat fusion method, then assembly process is simplified, but structural integrity deteriorates as the case is easily damaged by external impact and may separate from housing
Solution Approach 1:
The coupling structure uses a combination of materials with different properties: the case is made of metal material while the housing is made of synthetic resin material. This composite material approach allows the metal case to provide structural strength and impact resistance, while the synthetic resin housing provides ease of manufacturing and damping properties. The groove coupling structure combines these materials to achieve both strong bonding and impact resistance.
3Strength
If a case is fixed to housing using fixing member such as screw, then structural integrity is improved, but productivity deteriorates due to additional components and added cost and process
Solution Approach 1:
The coupling structure merges the case and housing into a unified assembly through groove interactions, eliminating the need for separate fixing members like screws. The groove structure in the housing engages with corresponding features on the case, creating a unified structure that provides both structural integrity and simplified assembly. This merging of components maintains fixing force while improving productivity by reducing part count and assembly steps.
Solution Approach 2:
The groove coupling structure enables self-aligning and self-fixing functionality. The grooves are designed to automatically guide and secure the case to the housing during assembly without requiring additional fixing members. This self-service mechanism maintains strong structural integrity while simplifying the assembly process and improving productivity.
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 effectively reduces magnetic field interference and enhances the structural integrity of the sensing device, improving motor performance and assembly efficiency by using a metal cover with grooves to manage magnetic flux and a secure coupling mechanism between the metal case and synthetic resin housing.
Implementation Method 1
a first Hall sensor disposed on the circuit board to detect an amount of magnetization of the stator generated due to an electrical interaction between the first magnet of the rotor and the stator
Implementation Method 2
magnetic field interference occurs between the torque sensor and the index sensor
Data Source
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AI summary
An embodiment provides a sensing device comprising: a first cover; a second cover coupled with the first cover; a rotor disposed at the second cover; a first magnet disposed between the second cover and the rotor; a stator disposed between the first magnet and the second cover; a seating part disposed between the first cover and the rotor; a second magnet disposed on the seating part; a circuit board disposed on a bottom surface of the second cover; and a first hall sensor and a second hall sensor disposed on the circuit board, wherein the first cover comprises an upper plate having an opening and a side plate extending downward from the upper plate, and the side plate of the first cover comprises a first groove formed at a position corresponding to the second hall sensor and a second groove spaced apart from the first groove.