Compact Torque Sensor Using Segmented Soft Magnetic Rings
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Solution Overview
Problem
Existing torque sensors face challenges in manufacturing soft magnetic rings due to their complex shape, requiring expensive processes like metal casting or sintering, and result in a large and heavy sensor design.
Innovation Solution
The torque sensor design features a rotating magnetic circuit with first and second soft magnetic members, each comprising magnetic rings and tips connected by columns, allowing for press-working of plate material to form a compact and lightweight structure, with a magnetic flux transmission mechanism that prevents short-circuits and allows for detection of torque without contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If soft magnetic rings are formed using traditional methods (metal casting or sintering), then manufacturing capability is achieved, but manufacturing cost increases and production complexity increases
Solution Approach 1:
The soft magnetic ring is divided into multiple segments that can be separately manufactured using press-working and then assembled together. This segmentation allows each segment to be produced using simple, cost-effective press-working processes rather than requiring complex metal casting or sintering for the entire ring, thereby reducing manufacturing complexity while maintaining manufacturing capability
Solution Approach 2:
Multiple soft magnetic ring segments are nested or assembled together to form the complete soft magnetic ring structure. This nesting approach enables the construction of a complex-shaped magnetic ring using multiple simple press-worked components, avoiding the need for complex single-piece manufacturing processes
2Device complexity
If soft magnetic rings are formed using press-working of plate material, then manufacturing cost decreases and production simplicity increases, but the complex shape cannot be achieved
Solution Approach 1:
The complex-shaped soft magnetic ring is segmented into multiple simpler components that can each be press-worked from plate material. By dividing the complex shape into manageable segments, each with simpler geometry, the patent enables use of cost-effective press-working processes while still achieving the overall complex functional shape when segments are assembled
Solution Approach 2:
Multiple press-worked plate segments are combined or assembled together to form the complete soft magnetic ring with the required complex shape. This merging of simple press-worked components creates the functional complex geometry that would be difficult to achieve with a single press-working operation, while maintaining manufacturing simplicity and cost-effectiveness
3Volume of moving object
If the sensor size is reduced, then compactness is achieved, but magnetic flux transmission effectiveness may be compromised
Solution Approach 1:
The patent optimizes the magnetic flux transmission path by arranging magnetic circuit components in different spatial dimensions and orientations. By carefully designing the three-dimensional arrangement of magnetic paths, poles, and soft magnetic structures, the patent achieves effective magnetic flux transmission within a compact volume, preventing short-circuits while maintaining detection reliability in a reduced-size sensor configuration
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 enables the manufacture of compact and lightweight torque sensors by press-working, reducing manufacturing costs and improving magnetic hysteresis characteristics, while maintaining effective magnetic flux detection and preventing magnetic short-circuits.
Implementation Method 1
a magnetic force generating part which rotates together with an end of the torsion bar while generating a magnetic flux in a direction of a rotation axis of the torsion bar
Implementation Method 2
a rotating magnetic circuit which rotates together with another end of the torsion bar, and a fixed magnetic circuit fixed to the housing to surround the rotating magnetic circuit so as to accept a magnetic flux from the rotating magnetic circuit without contact
Implementation Method 3
a magnetic sensor which detects a magnetic flux density in the fixed magnetic circuit
Implementation Method 4
The first soft magnetic member comprises a first magnetic ring disposed around the torsion bar, first magnetic tips disposed in a peripheral direction at equal angular intervals so as to face the magnetic force generating part in the direction of the rotation axis, and first magnetic columns connecting the first magnetic tips magnetically to the first magnetic ring
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A torque sensor (50) detects an input torque input into a torsion bar (51) using a magnetic force generating part (60), a rotating magnetic circuit (69), a fixed magnetic circuit (90), and a magnetic sensor (98). The rotating magnetic circuit (69) comprises a first soft magnetic member (70) and a second soft magnetic member (80), each of which comprises a magnetic ring (73, 83), a magnetic tip (71, 81) facing the magnetic force generating part (60), and a magnetic column (72, 82) connecting the tip (71, 81) and the ring (73, 83). By disposing the first soft magnetic member (70) and the second soft magnetic ring (80) so as to face each other, the soft magnetic rings (70, 80) are formed in an identical shape that can be manufactured by press-working a plate material, thereby realizing a compact and lightweight torque sensor (50).