Sensing Device Protrusion-Groove Coupling for Noise Reduction
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Solution Overview
Problem
The existing sensing devices in electronic power steering systems face issues such as magnet cracking due to thermal expansion differences, noise generation from surface contact between the stator and housing, and increased noise with minimal gap, which complicates manufacturing and increases component count.
Innovation Solution
A sensing device design that couples a rotor holder and magnet without adhesives, using protrusions and grooves to enhance coupling force and minimize surface contact between the stator and housing, thereby reducing noise and simplifying manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is used to attach magnet to rotor holder, then magnet attachment is achieved, but cracks occur in magnet surface due to thermal expansion difference
Solution Approach 1:
The contact surface between magnet and rotor holder is segmented into multiple discrete contact points through protrusions and grooves, rather than continuous adhesive bonding. This segmentation reduces thermal stress concentration and prevents crack propagation across the entire interface.
Solution Approach 2:
The rotor holder acts as an intermediary component with a specific structure (protrusions and grooves) that mediates the thermal expansion difference between magnet and holder. The groove structure provides expansion space while maintaining attachment force.
2Stability of the object's composition
If stator is rotated with surface contact to housing, then functional stability is achieved, but noise is generated
Solution Approach 1:
The harmful surface contact between stator and housing is extracted and replaced with point contact through protrusions. This removes the source of continuous friction noise while maintaining the necessary functional stability of the stator.
Solution Approach 2:
The contact interface is changed from a two-dimensional surface contact to a one-dimensional line contact or zero-dimensional point contact through protrusions. This dimensional reduction minimizes contact area and thus noise generation while preserving stability.
3Stability of the object's composition
If gap is minimized by increasing surface contact between stator and housing, then functional stability is induced, but noise is further increased
Solution Approach 1:
The contact interface dimensionality is changed from surface-to-surface contact to point contact via protrusions. This allows gap minimization for stability while reducing contact area to minimize noise, resolving the contradiction through dimensional transformation.
4Strength
If adhesive is used for magnet attachment, then manufacturing process includes adhesive application, but component count and manufacturing complexity increase
Solution Approach 1:
The magnet attachment function is merged with the rotor holder structural design through integral protrusions and grooves. This eliminates the need for separate adhesive materials and application processes, reducing manufacturing complexity while maintaining attachment strength.
Solution Approach 2:
The rotor holder structure itself provides the attachment mechanism through its protrusion-groove geometry, without requiring external adhesive materials or additional assembly steps. The structure serves its own attachment function, simplifying manufacturing.
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 increases the coupling force between the rotor holder and magnet, reduces noise by minimizing surface contact, and simplifies the manufacturing process by eliminating adhesives and reducing component count.
Implementation Method 1
the magnet includes a first body and a first protrusion protruding from the first body in an axial direction, the sleeve includes a second body and a second protrusion protruding outward from the second body, and the rotor holder includes a first groove in which the first protrusion is disposed
Implementation Method 2
one surface of the stator is in surface contact with a lower surface of the housing. Accordingly, there is a problem in that noise is generated due the surface contact when the stator is rotated
Data Source
AI summary
An embodiment may provide a sensing device comprising: a rotor; a stator disposed outside the rotor; and a sensor module disposed outside the stator, wherein the rotor includes a rotor holder, and a magnet and a sleeve which are coupled to the rotor holder, wherein the magnet includes a first body and a first protrusion protruding in an axis direction from the first body, the sleeve includes a second body and a second protrusion protruding outward from the second body, and the rotor holder includes a first groove in which the first protrusion is disposed.