Flexible Temperature Sensor for Stator Windings
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Solution Overview
Problem
Resistance-based temperature sensors (RTDs) used in stator windings of motors and generators are prone to failures due to stress during installation and manufacturing, particularly in space-constrained environments, where the thin, rigid fiberglass body and lead steps are susceptible to damage and tensile failures.
Innovation Solution
A temperature sensor design featuring a fiberglass body with a polyimide substrate and acrylic adhesive, surrounded by an epoxy laminate, and a conductive tab extending between the lead wire and sensing wire to protect the lead step and sensing wire, along with a flexible zone that does not include epoxy laminate or fiberglass, enhancing durability and reducing the likelihood of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thin, rigid fiberglass body is used to house the sensing portion, then the sensor structure is stable and protective, but the sensor becomes susceptible to damage during installation and manufacturing due to stress on the sensing wire
Solution Approach 1:
The patent replaces the rigid fiberglass body with a flexible thin film structure. The sensing wire is embedded in a flexible substrate that can accommodate bending and stretching during installation, eliminating the lead step configuration and reducing stress concentration points that cause tensile failures.
Solution Approach 2:
The patent uses composite material structures combining flexible substrates with protective coatings. The sensing wire is integrated into a multi-layer flexible composite that provides both mechanical protection and flexibility, allowing the sensor to withstand installation stresses while maintaining structural integrity.
2Volume of moving object
If the RTD is installed completely within a stator slot with only insulated wires protruding, then the sensor fits in space-constrained environments, but the lead step configuration makes installation difficult and susceptible to damage
Solution Approach 1:
The flexible thin film structure allows the sensor to conform to the stator slot geometry without requiring a rigid housing. The flexible substrate enables the sensor to be installed in tight spaces while the integrated lead wire configuration eliminates the need for complex lead steps, simplifying the installation process.
Solution Approach 2:
The patent divides the sensor into modular segments with the sensing portion, flexible substrate, and lead wires as separate but integrated components. This segmentation allows for easier manipulation during installation while maintaining a compact overall structure that fits within stator slots.
3Strength
If pressure and blows with rubber mallets are applied during installation, then the RTD is secured in place, but tensile failures occur due to stress on the sensing wire
Solution Approach 1:
The flexible thin film structure distributes mechanical stress along the entire length of the sensing wire rather than concentrating it at specific points. This flexibility allows the sensor to absorb installation forces without causing tensile failures, eliminating the need for aggressive installation methods.
Solution Approach 2:
The flexible substrate acts as a cushioning layer that absorbs and distributes mechanical stresses before they reach the sensing wire. This pre-cushioning effect protects the wire from damage during installation while still allowing the sensor to be securely positioned in the stator slot.
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 enhanced sensor design increases the strength of internal sensing wires to at least 120 PSI, reduces external fiberglass damage, and allows for visible detection of over-stressing, thereby improving installation precision and reducing failure rates.
Implementation Method 1
a core material comprising a polyimide substrate having an acrylic adhesive surrounding at least a portion of the sensing wire
Data Source
AI summary
A stator winding temperature sensor including at least one sensing wire for connecting to a stator. The sensor also includes a body, including a core material comprising a polyimide substrate having an acrylic adhesive surrounding at least a portion of the sensing wire, and a laminate material over the core material. The body has a thickness adapted to protect the sensing wire. The sensor includes a lead wire for connecting to an external monitoring device. The sensing wire is electrically connected to the lead wire at a lead step portion of the sensor. The sensor further includes a tab extending from the lead wire and encompassing the lead step, the tab including a flexible zone where the tab is surrounded by a polyimide and an adhesive but is not surrounded by fiberglass.