Sensor Rotor Sleeve and Magnet Integration for EPS
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Solution Overview
Problem
The existing electric power steering (EPS) systems face issues with magnet exposure during assembly, leading to damage and detachment due to incomplete adhesive curing or external forces.
Innovation Solution
A sensor device design where the magnet is housed inside a sleeve with a fixing part that protrudes and is coupled using caulking, eliminating the need for adhesive and enhancing the coupling force between the magnet and the yoke by integrating the sleeve and yoke to form a core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the magnet is attached to the sleeve using adhesive in an externally exposed state, then the magnet can be fixed to the sleeve, but the magnet is at high risk of being damaged during assembly and may detach due to incomplete adhesive curing
Solution Approach 1:
The patent replaces the chemical bonding method (adhesive) with a mechanical coupling method. The fixing part protruding from the sleeve end engages with the magnet through physical interlocking, eliminating the need for adhesive and its associated curing issues. This mechanical substitution provides immediate and reliable attachment without the risks of incomplete curing or chemical bonding failures.
Solution Approach 2:
The fixing part acts as an intermediary element between the sleeve and the magnet. It protrudes from the sleeve end and couples with the magnet, providing a dedicated mechanical interface that transfers and distributes forces between the sleeve and magnet, thereby enhancing the reliability of the attachment.
2Ease of manufacture
If the magnet is externally exposed on the sleeve, then the assembly process can be simplified, but the magnet is at high risk of being damaged during assembly
Solution Approach 1:
The magnet is positioned inside the sleeve structure, with the fixing part protruding from the sleeve end to couple with the magnet. This nested arrangement protects the magnet from external damage during assembly while maintaining ease of manufacture, as the magnet is securely housed within the sleeve's protective structure.
Solution Approach 2:
The sleeve structure serves as a protective cushion for the magnet before the final assembly is complete. By housing the magnet within the sleeve and using the fixing part for secure coupling, the design provides beforehand protection against external forces and damage during the assembly process.
3Reliability
If multiple components are used to house and fix the magnet, then the magnet is protected from damage, but the number of components and manufacturing processes increases
Solution Approach 1:
The patent merges the protective housing function and the fixing function into a single integrated sleeve structure. The fixing part is formed as an integral part of the sleeve, eliminating the need for separate protective housings and fasteners. This merging reduces the number of components and simplifies manufacturing processes while maintaining reliable magnet protection.
Solution Approach 2:
The sleeve structure performs multiple functions simultaneously: it houses and protects the magnet from external damage, provides a mounting interface through the fixing part, and maintains the magnet's position. This multi-functionality reduces the need for additional specialized components, thereby simplifying the overall device structure.
Data Source
AI summary
A sensor device may include a rotor, a stator disposed outside the rotor and a sensor module disposed outside the stator. The rotor may include a sleeve and a magnet coupled to the sleeve, and the magnet may be disposed inside the sleeve. The sleeve may include a fixing part which protrudes from an end of the sleeve and is in contact with the magnet. The sleeve includes a second body, and a third body. The second body is disposed to cover an upper surface of the magnet, and the third body is disposed to cover an outer circumferential surface of the magnet. The magnet is disposed between the shaft and the third body, thereby providing an advantageous effect of increasing a coupling force between the magnet of the rotor and a yoke.