Torque Sensor Yoke Positioning for Stable Magnetic Flux Gap
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Solution Overview
Problem
The positional relationship between the stator and magnetic collection yoke in torque sensors is not accurately maintained due to the use of an elastic O-ring, leading to changes in the gap between the magnetic collection yoke and stator, affecting the output characteristic and causing individual differences in sensor performance.
Innovation Solution
A torque sensor design with a magnetic collection yoke assembly that includes movement restriction protrusions on both surfaces, allowing for precise positioning and attachment to a housing, ensuring a consistent positional relationship between the stator and magnetic collection yoke, while also incorporating a sealing member to prevent external ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an elastic O-ring is used for sealing between the magnetic collection yoke assembly and housing, then sealing performance is improved, but the positional relationship between the stator and magnetic collection yoke becomes unstable
Solution Approach 1:
The sealing function is segmented from the positioning function. The O-ring is dedicated solely to sealing between the magnetic collection yoke assembly and housing, while separate positioning protrusions on the magnetic collection yoke assembly engage with positioning holes in the housing to maintain precise positional relationships. This segmentation allows each component to perform its specific function without compromising the other.
Solution Approach 2:
Positioning protrusions and positioning holes act as intermediary structures that mediate between the elastic O-ring and the magnetic collection yoke assembly. These intermediaries provide a rigid positioning mechanism that compensates for the elasticity of the O-ring, ensuring that the gap between the stator and magnetic collection yoke remains consistent even when the O-ring compresses.
2Ease of operation
If the magnetic collection yoke assembly is detachably attached to the housing, then ease of assembly and disassembly is improved, but positioning accuracy may be compromised
Solution Approach 1:
The attachment mechanism is segmented into detachable connection elements (screws or bayonet connectors on flange portions) for ease of assembly/disassembly, and separate positioning protrusions for maintaining precision. This allows the assembly to be easily detached and reattached while ensuring that each reattachment maintains the correct positional relationship through the positioning features.
Solution Approach 2:
The positioning protrusions are pre-formed on the magnetic collection yoke assembly, and the positioning holes are pre-formed in the housing. When the assembly is detached and reattached, these pre-formed features automatically guide the components into the correct positional relationship, eliminating the need for complex alignment procedures and ensuring consistent positioning accuracy across multiple assembly cycles.
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 design ensures a stable positional relationship between the stator and magnetic collection yoke, maintaining consistent output characteristics and preventing environmental interference, thereby enhancing sensor accuracy and reliability.
Implementation Method 1
a Hall element outputting the change in magnetic flux detected by the magnetic collection yoke as an electric signal
Implementation Method 2
The O-ring used as the sealing material is interposed between the mounting hole of the housing and the cylindrical portion inserted into the mounting hole. The O-ring has elasticity, and the O-ring is in a compressed state when the cylindrical portion is inserted into the mounting hole of the housing.
Data Source
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AI summary
In order to set the positional relationship between a stator and a magnetic collection yoke to a desired positional relationship, a torque sensor 10 includes a stator 60 fixed to a first pinion gear 88a, and a magnetic collection yoke assembly 40 including a magnetic collection yoke 46 that is disposed so as to overlap a flange portion 61 of the stator 60 and detects a change in magnetic flux according to a relative positional change between the stator 60 and a magnet 65, and is attached to a housing 20, the magnetic collection yoke assembly 40 includes a plurality of movement restriction protrusions 44 facing an inner wall 25 of a storage portion 24 included in the housing 20, two movement restriction protrusions 44 of the plurality of movement restriction protrusions 44 are disposed apart from each other in at least one direction of a length direction Y and a width direction X, two movement restriction protrusions 44 of the plurality of movement restriction protrusions 44 are disposed apart from each other in the other direction, or at least one movement restriction protrusion 44 extends longer in the other direction than in the one direction.