External-Rotor Fan Motor Assembly for Compact Condenser Dryers
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Solution Overview
Problem
Laundry dryer machines of the condenser type face limitations in thermal efficiency and increased humidity due to the need for large, costly motors with low torque density, leading to constructional compromises and maintenance issues.
Innovation Solution
A fans-motor assembly using a synchronous permanent magnet electric motor with an internal stator and external rotor, allowing for increased torque density and reduced motor dimensions, along with a belt tightener mechanism that simplifies belt tensioning and reduces the need for external cabling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an asynchronous motor with a limited diameter rotor is used, then the motor structure is simple and compact, but the torque density is low requiring a large motor dimensions
Solution Approach 1:
The patent inverts the traditional motor configuration by placing the rotor externally and the stator internally. This inversion allows the rotor to have a larger effective diameter for generating torque while keeping the overall motor compact. The external rotor design enables direct coupling with the drive shaft, eliminating the need for belt transmissions and reducing mechanical losses.
Solution Approach 2:
The patent implements a nested structure where the internal stator is positioned within the external rotor assembly. The stator is mounted on the drive shaft interior, while the rotor surrounds it, creating a compact nested arrangement that maximizes torque density within a limited space envelope.
2Power
If a large dimension motor is used to obtain necessary torque, then the torque requirement is met, but the production cost increases due to high quantity of active materials
Solution Approach 1:
The patent changes the motor configuration parameters by inverting the rotor-stator arrangement and using permanent magnets in the external rotor. This parameter change increases the torque density by approximately 3-5 times compared to traditional asynchronous motors, allowing a much smaller motor to deliver the same torque output, thereby reducing active material quantity and production cost.
3Device complexity
If the stator is mounted rotatingly on the frame by means of bushings, then the motor can be positioned centrally, but the bushings wear rapidly requiring maintenance
Solution Approach 1:
The patent extracts the rotating mounting function from the stator and relocates it to the rotor assembly. The external rotor is directly coupled to the drive shaft, which rotates on bearings within the motor housing. This extraction eliminates the need for external bushings to support the rotating stator, thereby removing the wear and maintenance issue while maintaining central motor positioning.
4Power
If the motor has considerable dimensions, then the torque requirement is met, but the control board cannot be directly associated requiring costly cablings
Solution Approach 1:
The compact nested structure of the internal stator and external rotor reduces the motor's overall dimensions, creating sufficient space to integrate the control board directly within the motor housing. This integration eliminates the need for external cablings between the motor and control board, simplifying the system and reducing cost.
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
This solution reduces production costs and overall dimensions of the motor while maintaining necessary torque for drum rotation, allowing for more efficient and compact designs with improved maintenance and reduced noise levels.
Implementation Method 1
a synchronous permanent magnet electric motor comprising an internal stator traversed by said drive shaft and an external rotor integral during rotation with said drive shaft
Implementation Method 2
external rotor integral during rotation with said drive shaft designed to move it to rotate
Implementation Method 3
The heat exchange takes place between the flow of hot drying air and a flow of cold air coming from the outside
Implementation Method 4
the hot air used to dry the laundry is not expelled to the exterior of the machine, but instead dehumidified and then made to recirculate
Data Source
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AI summary
A fans-motor assembly (1) for condenser laundry dryer machine, of unusually low cost and overall dimensions, comprising: a drive shaft (2) which can be associated in a rotating manner with a frame of a laundry dryer machine and designed to be connected by means of a transmission belt (100) to a rotating drum (101) thereof; a fan for the hot air (3) and a fan for the cold air (4) integral in rotation with said drive shaft (2) and designed to convey respectively a flow of hot air and a flow of cold air along separate paths of said laundry dryer machine; a synchronous permanent magnet electric motor (10) comprising an internal stator (5) traversed by said drive shaft (2) and an external rotor (6) integral during rotation with said drive shaft (2).