Laundry Drum Speed Control to Form and Maintain Wetting Tunnel
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Solution Overview
Problem
Conventional laundry care devices struggle to ensure complete wetting of laundry, especially with large loads, as the laundry drum's rotation speed at or below resonance speed is insufficient to maintain laundry in contact, leading to incomplete wetting and inefficient washing liquid distribution.
Innovation Solution
A laundry care device with a controller that rotates the laundry drum at a maximum speed greater than resonance speed during a specific period to form and maintain a laundry tunnel, then reduces speed to a drum speed greater than detachment speed to keep the tunnel stable, ensuring effective wetting and preventing laundry collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the laundry drum is rotated at a speed lower than or equal to the resonance speed, then energy consumption is reduced and gentle washing is achieved, but the laundry cannot be completely placed on the laundry drum, leading to incomplete wetting
Solution Approach 1:
The patent applies periodic action by dividing the washing cycle into distinct phases: a first operating phase where the drum rotates at low speed (below resonance) for gentle washing and energy efficiency, and a second operating phase where the drum rotates at high speed (above resonance) to form and maintain a laundry tunnel. This periodic switching between speed regimes allows the system to achieve both gentle washing and complete wetting at different times during the cycle.
Solution Approach 2:
The patent implements dynamics by making the drum rotation speed variable rather than constant. The controller dynamically adjusts the rotation speed between two distinct operating phases: a low-speed phase for gentle washing and a high-speed phase for tunnel formation. This dynamic speed adjustment allows the system to optimize between energy consumption and wetting effectiveness based on the current washing stage.
2Reliability
If the laundry drum is rotated at maximum speed greater than resonance speed, then the laundry is completely placed on the drum and a laundry tunnel is formed, but the laundry tunnel becomes unstable and laundry may collapse
Solution Approach 1:
The patent uses periodic action to alternate between high-speed operation (above resonance) for tunnel formation and low-speed operation (below resonance) for tunnel stabilization. The controller switches between these two operating phases, allowing the laundry tunnel to be formed during the high-speed phase and then maintained during the low-speed phase, preventing collapse while ensuring complete wetting.
Solution Approach 2:
The patent applies preliminary action by first forming the laundry tunnel through high-speed rotation (above resonance) before transitioning to low-speed rotation (below resonance) to maintain it. The tunnel formation is achieved in advance during the second operating phase, and then the drum speed is reduced to preserve the tunnel structure for subsequent wetting operations.
3Speed
If the laundry drum rotates at resonance speed, then the oscillation frequency matches the natural oscillation frequency, but resonant rocking occurs causing instability
Solution Approach 1:
The patent applies asymmetry by deliberately avoiding the symmetric resonance condition. Instead of operating at the resonant frequency where oscillation frequency matches natural oscillation frequency, the controller operates at two asymmetric speed levels: below resonance during the first phase and above resonance during the second phase. This asymmetric speed selection prevents resonant rocking and maintains system stability.
Solution Approach 2:
The patent uses periodic action to switch between operating phases that avoid resonance. The controller periodically alternates between low-speed operation (below resonance) and high-speed operation (above resonance), ensuring that the drum never operates at the unstable resonant frequency. This periodic switching between non-resonant states eliminates resonant rocking while maintaining washing effectiveness.
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 effectively forms and maintains a laundry tunnel, ensuring complete wetting of laundry even with large loads, preventing immediate expulsion of washing liquid and reducing resonant rocking, thus enhancing the laundry care process.
Implementation Method 1
rotating the laundry drum at a maximum speed greater than a resonance speed... rotating the laundry drum at a drum speed... greater than a detachment speed... to form and maintain a laundry tunnel
Implementation Method 2
the resonance speed is a speed of the laundry drum at which an oscillation frequency of the oscillation system corresponds to a natural oscillation frequency of the oscillation system
Data Source
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AI summary
The invention relates to a method (200) for treating laundry (135) and to a laundry treatment appliance (100) which is designed to carry out the method, comprising an outer tub (105) for receiving washing liquid, a laundry drum (107) which is arranged in the outer tub (105), an oscillating system (109) for supporting the laundry drum (107) and the outer tub (105) in the laundry treatment appliance (100) in an oscillatable manner, a drum drive (123), and a controller (119) for controlling the drum drive (123). The controller (119) is designed to activate the drum drive (123) during a maximum time segment (151) of a washing time period (149) in order to rotate the laundry drum (107) at a maximum rotational speed (155) which is greater than the resonance speed (157) of the laundry drum (107). The controller (119) is also designed to activate the drum drive (123) during a drum time segment (153) of the washing time period (149) adjoining the maximum time segment (151) in order to rotate the laundry drum (107) at a drum rotational speed (159) which is lower than the resonance speed (157) of the laundry drum (107) and greater than the detaching speed (161) of the laundry drum (107) in order to form and maintain a laundry tunnel (137) within the laundry (135) received in the laundry drum (107).