Torque Sensor Magnetic Shield Clearance Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Torque detecting apparatuses face issues with crack formation due to differential thermal expansion between the magnetic shield, magnetic flux collecting holder, and housing, causing stress concentration and potential damage.
Innovation Solution
Incorporating a design with an annular magnetic flux collecting ring and a magnetic shield attached to the magnetic flux collecting holder, where the housing portion includes a clearance between its outer wall and the magnetic shield's circumferential end, preventing direct contact and stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the magnetic shield is attached to the magnetic flux collecting holder, then the magnetic shield can reduce the influence of external magnetic fields, but differential thermal expansion causes stress concentration and crack formation
Solution Approach 1:
A resin layer is introduced as an intermediary substance between the magnetic shield and the magnetic flux collecting holder. This resin layer acts as a buffer that absorbs differential thermal expansion stress, preventing direct stress transmission to the magnetic flux collecting holder while maintaining the magnetic shield's attachment and functionality.
Solution Approach 2:
The resin layer is applied beforehand to the magnetic flux collecting holder's outer peripheral surface before attaching the magnetic shield. This pre-applied cushioning layer anticipates and prepares for the thermal expansion differences that will occur during operation, distributing stresses before they can concentrate and cause cracks.
2Ease of manufacture
If the magnetic shield, magnetic flux collecting holder, and housing are tightly coupled, then assembly is simplified, but thermal expansion differences cause stress concentration at contact points
Solution Approach 1:
The resin layer serves as a mediator between the magnetic flux collecting holder and the magnetic shield, enabling a simplified assembly process while simultaneously preventing stress concentration. The resin's compliant nature allows for easy attachment without requiring complex stress-absorbing mechanisms.
Solution Approach 2:
The resin layer changes the mechanical interaction parameters between the magnetic flux collecting holder and magnetic shield, transitioning from rigid-to-rigid contact to compliant-to-rigid contact. This parameter change allows tight coupling for ease of assembly while preventing stress concentration through the resin's elastic properties.
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 effectively prevents crack formation in the magnetic flux collecting holder and housing by maintaining a clearance, thereby ensuring the structural integrity and reliability of the torque detecting apparatus across temperature changes.
Implementation Method 1
The magnetic shield is attached to the outer peripheral surface of the magnetic flux collecting holder so as to reduce influence that an external magnetic field exerts on the magnetic flux collecting ring
Implementation Method 2
The magnetic flux collecting holder surrounds and holds the magnetic flux collecting ring
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A torque detecting apparatus includes an annular magnetic flux collecting ring, a magnetic flux collecting holder surrounding and holding the magnetic flux collecting ring, and a magnetic shield including a circumferential end and attached to the outer periphery of the magnetic flux collecting holder. The magnetic flux collecting holder includes a housing portion that houses in its inner space the circumferential end of the magnetic shield. The housing portion includes an outer wall radially inwardly facing an outer peripheral surface of the circumferential end of the magnetic shield such that a first clearance is provided between the housing portion and the outer peripheral surface of the circumferential end of the magnetic shield.