Torque Sensor Adhesive Peel-Off Mitigation
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Solution Overview
Problem
Existing relative angle sensing devices fail to accurately sense the rotation angle between two rotary shafts when the adhesive material peels off, leading to a loss of synchronization between the magnetic generator and the rotary shafts.
Innovation Solution
A relative angle sensing device utilizing a magnetoresistive (MR) sensor with a thin-film ferromagnetic metal on a substrate, where the resistance changes in response to the magnetic field, allowing for accurate detection of the relative rotation angle even if the adhesive peels off, by using a configuration that ensures the magnet rotates with the first rotary shaft through direct contact with the rotary component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive material is used to join the magnetic body to the back yoke, then the magnetic generator can be assembled easily, but the reliability of rotation synchronization is reduced when the adhesive peels off
Solution Approach 1:
The magnetic body is divided into multiple magnetic segments that are joined to the back yoke. This segmentation allows for mechanical interlocking structures between the segments and the back yoke, providing both easy assembly and reliable rotation synchronization even if adhesive fails.
Solution Approach 2:
The patent combines multiple joining methods: adhesive material for initial assembly and mechanical interlocking structures (such as grooves and protrusions) for reliable rotation synchronization. This merging of joining methods ensures that even if the adhesive peels off, the magnetic segments remain securely attached to the back yoke.
2Device complexity
If only adhesive material is used to join the magnetic body, then the device structure is simple, but the sensing accuracy is lost when the adhesive peels off
Solution Approach 1:
The magnetic segments are pre-equipped with mechanical interlocking structures (grooves and protrusions) before assembly. These structures are designed in advance to engage with corresponding features on the back yoke, ensuring that rotation synchronization is maintained from the outset and preventing loss of sensing accuracy.
Solution Approach 2:
The patent incorporates mechanical interlocking structures as a backup mechanism that cushions against the potential failure of adhesive bonding. This beforehand cushioning ensures that even if the adhesive peels off, the magnetic segments remain securely attached, and the relative rotation angle sensing accuracy is preserved.
3Reliability
If the magnetic body is firmly attached to prevent peeling, then the rotation synchronization is maintained, but the ease of assembly and disassembly is reduced
Solution Approach 1:
The joining mechanism is designed to be dynamic: during assembly, the magnetic segments can be easily inserted and engaged with the back yoke through the mechanical interlocking structures. During operation, these same structures provide firm attachment to maintain rotation synchronization. The design allows for easy assembly while ensuring reliable operation.
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
Enables reliable sensing of the relative rotation angle between two rotary shafts, maintaining accuracy and functionality even if the adhesive material peels off, ensuring continuous operation of the electric power steering system.
Implementation Method 1
a magnetoresistive (MR) sensor with a thin-film ferromagnetic metal on a substrate, where the resistance changes in response to the magnetic field
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A relative angle sensing device that senses a relative rotation angle between first and second rotary shafts includes: a rotary component that is provided on one rotary shaft out of the first rotary shaft and the second rotary shaft, and that rotates together with the one rotary shaft; a supported component that generates a magnetic field and that is supported by the rotary component through an adhesive material; and a sensor that is provided in the other rotary shaft out of the first rotary shaft and the second rotary shaft, and that outputs a value corresponding to the magnetic field generated by the supported component. A transmitting unit is provided between the rotary component and the supported component. The transmitting unit transmits rotative force of the one rotary shaft to the supported component by direct contact with each other in a case of peeling of the adhesive material.