Vacuum Impregnated Epoxy Overmolding for Motor Water Resistance
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Solution Overview
Problem
Current water-resistant electric motors used in combined ice shavers and blenders are prone to water damage due to condensation and ice melt, leading to motor failure, as water penetrates through epoxy coatings and wears out seals, compromising the Hall sensor system and stator windings.
Innovation Solution
A motor design featuring a rotor assembly, stator assembly with thixotropic, flexible epoxy resin overmolding and glass fibers, applied via vacuum pressure impregnation, encapsulating the stator and Hall effect circuit board to enhance water resistance and protect internal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the motor is positioned directly under the ice shaver blade, then the design is compact and simple, but water penetrates the motor housing and drive shaft bearings through worn O-rings, causing motor failure
Solution Approach 1:
The patent extracts the vulnerable motor from direct water exposure by positioning it in a elevated motor housing above the ice shaver blade, separating the motor from the water-prone environment while maintaining direct drive through a sealed transmission mechanism
Solution Approach 2:
The patent introduces an intermediary sealed transmission mechanism (gears or belts within a sealed housing) that transmits rotational motion from the motor to the shaver blade without requiring the motor to be in direct contact with water, thus protecting the motor while maintaining functionality
2Device complexity
If the Hall sensor circuit board and stator are encased in epoxy, then the motor structure is simplified, but water wicks through the epoxy coating over time and damages the Hall effect sensor system and stator windings
Solution Approach 1:
The patent uses a composite encapsulation system combining epoxy resin with hydrophobic additives and multiple coating layers, creating a material structure that maintains the simplicity of encasement while adding water-repellent properties to prevent water wicking
Solution Approach 2:
The patent applies thin film hydrophobic coatings over the epoxy-encased components, creating a flexible water-resistant barrier that prevents water from penetrating through the epoxy coating while maintaining the structural integrity of the encasement
3Reliability
If sealing O-rings are used to seal the motor housing and drive shaft bearings, then the motor is protected from water, but the O-rings wear over time due to exposure to cleaning agents and ice melt, allowing water penetration
Solution Approach 1:
The patent employs multiple redundant sealing mechanisms (seals, gaskets, and hydrophobic barriers) positioned at critical water penetration points before water can reach sensitive components, providing advance protection against seal wear and failure
Solution Approach 2:
The patent applies different sealing materials and methods at different locations based on specific water exposure risks, using robust seals at high-stress areas and hydrophobic coatings in areas exposed to cleaning agents, optimizing both protection and durability
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 solution significantly reduces water ingress and contamination, extending the motor's lifespan by creating a robust, water-resistant barrier that prevents damage to the stator windings and Hall effect sensors, improving reliability in humid environments.
Implementation Method 1
an overmolding encapsulating the stator assembly, wherein the overmolding is formed from a mixture of a thixotropic, flexible epoxy resin and glass fibers
Implementation Method 2
the overmolding significantly reduces water ingress and contamination, extending the motor's lifespan by creating a robust, water-resistant barrier
Implementation Method 3
The overmolding may be applied to the stator assembly by a vacuum pressure impregnation process
Implementation Method 4
a circuit board to which a plurality of Hall effect sensors are connected for detecting rotational position of the rotor assembly
Data Source
AI summary
For improved water resistance, the stator assembly of a d.c. brushless motor is encapsulated in an overmolding formed from a mixture of a thixotropic, flexible epoxy resin and glass fibers. The overmolding may be applied to the stator assembly by a vacuum pressure impregnation process. The overmolding may also encapsulate a Hall effect circuit board and sensors of the motor.