Sealed Motor Bearing Structure for Fluid Ingress Resistance
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Solution Overview
Problem
Existing motors are vulnerable to fluid penetration, especially in applications involving exposure to fluids, leading to potential damage and operational issues.
Innovation Solution
A sealed brushless DC motor design with a hydrophobic material-filled gap between the motor housing and shaft, combined with a shaft seal and lubricated bearings, prevents fluid ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the motor is exposed to fluids for application purposes, then the motor can be used in versatile environments, but fluid penetration damages the motor components
Solution Approach 1:
The motor is divided into sealed segments with distinct sealing zones. The bearing housing includes a sealed chamber that isolates critical components (bearings, shaft seal) from fluid exposure, while other motor portions can remain accessible. This segmentation allows the motor to operate in fluid environments without compromising component protection.
Solution Approach 2:
A shaft seal acts as an intermediary barrier between the fluid environment and the motor's internal components. The seal is positioned at the interface where the shaft exits the motor housing, preventing fluid penetration while allowing rotational motion. Additionally, lubricant serves as an intermediary substance that coats sealing surfaces to enhance fluid resistance.
2Reliability
If a seal is added to prevent fluid penetration, then motor protection is improved, but device complexity increases
Solution Approach 1:
The sealing function is merged with existing motor components rather than adding entirely separate sealing systems. The bearing housing is designed to incorporate the shaft seal and lubricant reservoir within its structure, combining support and sealing functions into a single integrated component. This reduces the number of separate parts while maintaining effective sealing.
Solution Approach 2:
The lubricant serves a dual function: it lubricates the bearing and shaft seal interfaces while simultaneously acting as a sealing medium that prevents fluid penetration. This self-service approach eliminates the need for separate sealing compounds or additional lubrication systems, simplifying the overall sealing structure.
3Reliability
If a shaft seal is located on the interior side of the bearing, then fluid penetration is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The shaft seal is pre-installed within the bearing housing during assembly, positioned in a dedicated sealing chamber that is formed as an integral part of the housing. This preliminary positioning ensures correct seal alignment and orientation before the bearing is assembled, reducing the precision requirements for final assembly operations.
Solution Approach 2:
The shaft seal utilizes a flexible lip or membrane structure that can conform to slight variations in shaft diameter and positioning tolerances. This flexibility compensates for manufacturing variations without requiring extremely tight tolerances, while still maintaining effective sealing against fluid penetration.
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 seals the motor against fluids, ensuring reliable operation in environments exposed to water, humidity, or submersion, without the need for a gearbox.
Implementation Method 1
a hydrophobic material filling a gap created by a region that is free of being covered by the motor housing
Implementation Method 2
a seal that is lubricated by the bearing so that the seal prevents fluid from entering the motor
Data Source
AI summary
A motor includes a motor housing; motor stators including motor windings; a shaft connected to the motor stators, the shaft extending along a longitudinal axis of the motor; and a motor rotor including: a rotor; magnets located within the rotor or motor windings located within the rotor; and bearings located between the motor housing and the shaft so that the motor housing and the shaft are movable relative to each other. The bearings comprise: an interior side that faces an interior of the motor; an exterior side that faces a location outside of the motor and all or portion of the exterior side is free of being covered by the motor housing; a hydrophobic material filling a gap created by a region that is free of being covered by the motor housing; and a shaft seal located on the interior side of one of the one or more bearings.