Laundry Dryer Drum-Fan Control for Delicate Fabric Drying
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Solution Overview
Problem
Rotatable-drum laundry dryers risk damaging delicate laundry due to high air flow rates generated by the centrifugal fan during high-speed rotation, causing the laundry to separate from the drum surface and leading to sliding, tumbling, and subsequent damage or shrinkage.
Innovation Solution
A control method that adjusts the rotational speed and direction of the drum and centrifugal fan to maintain a lower air flow rate, ensuring centrifugal acceleration equals gravitational acceleration, thereby keeping the laundry pressed against the drum surface, and incorporates separate control algorithms for delicate and non-delicate laundry cycles to manage temperature and drying time effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the drum rotates at high speed to press laundry against the inner wall, then rubbing damage is reduced, but the centrifugal fan generates very high air flow rate that separates laundry from drum surface
Solution Approach 1:
The patent applies dynamics by enabling the centrifugal fan to rotate in two opposite directions. During the drying phase, the fan rotates in the first direction to generate high air flow for rapid drying. During the high-speed drum rotation phase, the fan rotates in the second direction (opposite direction) to generate counteracting airflow that prevents laundry from separating from the drum surface, thus resolving the contradiction between high-speed drying and laundry stability.
Solution Approach 2:
The patent implements periodic action by alternating between different operational phases: a drying phase with high air flow in one direction, followed by a high-speed rotation phase with counteracting air flow in the opposite direction. This periodic reversal of fan rotation direction allows the system to achieve both rapid drying and prevention of laundry separation at different time intervals within the drying cycle.
2Device complexity
If a single electric motor drives both the drum and centrifugal fan, then device complexity is reduced, but control precision for different laundry types becomes difficult
Solution Approach 1:
The patent applies dynamics by implementing variable control algorithms that dynamically adjust the operational parameters of the single motor based on the type of laundry being dried. The control system can modify rotation speeds, rotation directions, and operational sequences to optimize performance for different laundry types (delicate vs. non-delicate), thereby achieving adaptability without increasing hardware complexity.
Solution Approach 2:
The patent implements parameter changes by allowing the control algorithm to modify multiple operational parameters including drum rotation speed, fan rotation speed, fan rotation direction, and air flow rates based on the detected laundry type. This enables a single motor system to adapt its behavior to different drying requirements through software-based parameter adjustment rather than hardware modification.
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 approach effectively prevents laundry from sliding or tumbling, reduces damage and shrinkage, and allows a single electric motor to power both the drum and fan, ensuring efficient and gentle drying of delicate items.
Implementation Method 1
a centrifugal fan which is located along the recirculating conduit and is designed to produce, inside the recirculating conduit, an airflow flowing through the drum
Implementation Method 2
heating means located along said air recirculating conduit to heat the airflow
Implementation Method 3
controlling said electric motor so as to cause: said drum to rotate at a second rotational speed greater than said first rotational speed in a reverse direction of rotation, thereby resulting in that the centrifugal acceleration of the inner surface of the drum equals gravitational acceleration, so the laundry is pressed by centrifugal force against the inner surface of the drum
Data Source
AI summary
A laundry dryer (1) has a laundry drum (3) which is designed to rotate about an longitudinal axis (6). An air recirculating conduit (10) is connected to the laundry drum (3). A heater device (10) is located along air recirculating conduit (10) to heat the airflow. A rotatable fan (11) is located along air recirculating conduit (10) to produce an airflow flowing through drum (3). The fan (11) is designed to be rotated in a main and secondary direction of rotation for providing different air flow rates. An electric motor (14) is mechanically connected with the fan (11) and the drum (3) for rotating the fan (11) and drum (3), simultaneously. The home laundry dryer (1) further has electric control means (18) configured to control the electric motor (14) so as to cause: the drum (3) to rotate at a first rotational speed (v1) in a forward direction of rotation, thereby resulting in the fan (11) being rotated in the main direction of rotation for providing a first air flow rate; or the drum (3) to rotate at a second rotational speed (v2) greater than said first rotational speed (v1) in a reverse direction of rotation, thereby resulting in the fan (11) being rotated in the secondary direction of rotation for providing a second air flow rate lower than the first air flow rate.