Refrigerator Fan Motor Outer Rotor Design
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Solution Overview
Problem
Conventional fan motors for refrigerators are large due to the inner rotor design, leading to increased material costs and space requirements, and lack a simple, effective waterproofing method.
Innovation Solution
A compact fan motor design with an outer rotor and integrally molded stator and circuit board, featuring a shaft bearing unit and end cap for reduced material usage and enhanced waterproofing through resin molding and insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an inner rotor design is used, then the motor structure is conventional and easy to manufacture, but the motor size increases and material costs increase
Solution Approach 1:
The patent inverts the conventional motor structure by placing the rotor outside the stator instead of inside. This outer rotor configuration reverses the traditional arrangement, allowing the motor to achieve sufficient torque with a more compact overall size while maintaining manufacturing feasibility through standardized components.
Solution Approach 2:
The patent transitions from a planar motor layout to a three-dimensional stacked configuration with the rotor positioned above the stator. This dimensional change enables better space utilization and reduces the motor's footprint while maintaining the necessary magnetic coupling between stator and rotor components.
2Ease of manufacture
If an inner rotor design is used, then the motor structure is conventional, but the amount of materials such as molding resin and iron sheets increases
Solution Approach 1:
By inverting the motor structure to an outer rotor design, the patent reduces the volume of stator core material and molding resin required. The inverted configuration allows for more efficient material distribution and reduces the overall material quantity needed to achieve the same torque output.
Solution Approach 2:
The patent changes the geometric parameters of the motor components, particularly the radial and axial dimensions of the stator and rotor. These parameter changes optimize the material usage by reducing the cross-sectional area of iron sheets and molding resin while maintaining the magnetic flux path efficiency necessary for adequate torque production.
3Power
If the rotor size is increased to get enough torque, then the torque increases, but the motor size and costs increase
Solution Approach 1:
The outer rotor design allows the rotor to be positioned at a greater radial distance from the stator center, increasing the lever arm for torque generation. This inverted configuration enables sufficient torque with a smaller overall motor size compared to conventional inner rotor designs where the rotor is constrained inside the stator.
Solution Approach 2:
The patent utilizes the axial dimension by stacking the rotor above the stator, creating a three-dimensional magnetic coupling arrangement. This dimensional change allows for increased torque density by optimizing the magnetic flux path length and cross-sectional area without proportionally increasing the motor's radial or axial footprint.
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 reduces manufacturing costs, simplifies the motor structure, and provides improved waterproofing while maintaining sufficient output and compact size.
Implementation Method 1
The circuit board 7 is placed toward the side of the stator 2 and makes magnetic fields around the stacked core 2a by applying electric currents to the coil and rotating the rotor 3
Implementation Method 2
The rotor 3 has a cylinder-shaped permanent magnet inserted through the stacked core 2a
Implementation Method 3
The conventional fan motor in the refrigerator is insulated by molding and is also capable of waterproof against the moisture because it is made by an insert molding method applied over the stator 2 and the circuit board 7
Data Source
AI summary
The present invention relates to a fan motor is for forced circulation of cool air in the refrigerator and comprises a molding unit, a shaft bearing unit, a rotor and an end cap. The molding unit comprises a stator having a shaft bearing unit mounting hole in the center thereof and core teeth which protrude radially outward so that a coil is wound thereon; and a circuit board having a circuit and a device which are electrically connected to the coil of the stator. The shaft bearing unit is inserted and fixed in the shaft bearing unit mounting hole. The rotor has a magnetic ring formed on the inner surface of a cup-shaped rotor housing, and a rotating shaft is fixed at the bottom center of the rotor housing. The end cap whose edge is connected to a side wall of the molding unit covering the rotor.