Magnetostrictive Torque Sensor Assembly for Thermal Coaxiality
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Solution Overview
Problem
Existing magnetostrictive torque sensors face challenges in maintaining sufficient bonding strength and coaxiality between the bobbin and magnetic ring due to thermal expansion, leading to relative displacement and interference during assembly.
Innovation Solution
A magnetostrictive torque sensor design that includes a bobbin with a bobbin-side fitting surface and a magnetic ring with a ring-side fitting surface, connected by a positioning member such as a spring pin, ensuring a spigot fit without looseness in the radial direction to maintain coaxiality and bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bobbin and magnetic ring are bonded using adhesive, then bonding strength is improved, but adhesion decreases due to temperature changes causing relative displacement
Solution Approach 1:
The connection structure is divided into multiple functional elements: the bobbin with locking protrusions, the magnetic ring with locking grooves, and the positioning member. This segmentation allows each component to perform its specific function - the locking structures provide mechanical bonding while the positioning member ensures precise alignment, together solving the adhesion stability problem under temperature changes
Solution Approach 2:
The positioning member acts as an intermediary between the bobbin and magnetic ring. It bridges the gap caused by thermal expansion differences by providing precise positioning and allowing relative movement, thereby maintaining stable adhesion despite temperature variations
2Strength
If snap-fitting is used to ensure bonding strength in the axial direction, then bonding strength is improved, but the claw portion interferes with spigot fitting making coaxiality difficult to ensure
Solution Approach 1:
The solution moves the locking mechanism from the radial dimension to the axial dimension. The locking protrusions and grooves engage in the axial direction, allowing the radial spigot fitting to achieve precise coaxiality without interference. This dimensional separation resolves the conflict between bonding strength and manufacturing precision
Solution Approach 2:
The connection structure is divided into multiple functional elements: the bobbin with locking protrusions, the magnetic ring with locking grooves, and the positioning member. This segmentation allows each component to perform its specific function - the locking structures provide mechanical bonding while the positioning member ensures precise alignment, together solving the adhesion stability problem under temperature changes
3Manufacturing precision
If the bobbin and magnetic ring are tightly fitted to ensure coaxiality, then coaxiality is improved, but relative displacement occurs due to thermal expansion differences
Solution Approach 1:
The connection structure transitions from a static tight fit to a dynamic adjustable connection. The positioning member and locking structures allow the bobbin and magnetic ring to adjust their relative positions dynamically in response to thermal expansion, maintaining both coaxiality and bonding stability under varying temperature conditions
Solution Approach 2:
The connection structure is divided into multiple functional elements: the bobbin with locking protrusions, the magnetic ring with locking grooves, and the positioning member. This segmentation allows each component to perform its specific function - the locking structures provide mechanical bonding while the positioning member ensures precise alignment, together solving the adhesion stability problem under temperature changes
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 effectively prevents relative displacement between the bobbin and magnetic ring, ensuring stable bonding strength and coaxiality, even with temperature changes, thereby maintaining a stable magnetic circuit for accurate torque measurement.
Implementation Method 1
the positioning member is bridged between the bobbin-side locking hole and the ring-side locking hole
Implementation Method 2
measures torque applied to a rotating shaft having a magnetostrictive property
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Bonding strength between a bobbin and a magnetic ring is sufficiently ensured regardless of temperature changes while favorably ensuring coaxiality between the bobbin and the magnetic ring. A magnetostrictive torque sensor 1 includes: a bobbin 3 having a bobbin-side cylindrical portion 7 arranged around a rotating shaft 2, a cylindrical bobbin-side fitting surface 8, and a bobbin-side locking hole 9; a detection portion 4 having detection coils arranged on an outer periphery of the bobbin-side cylindrical portion 7; a magnetic ring 5 having a ring-side cylindrical portion 13 arranged around the detection portion 4, a ring-side fitting surface 14 fitted to the bobbin-side fitting surface 8, and a ring-side locking hole 15; and a positioning member 6 bridged between the bobbin-side locking hole 9 and the ring-side locking hole 15.