Method for operating a domestic appliance, and domestic appliance
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Solution Overview
Problem
Existing methods for detecting children in washing machines and dryers are unsafe, as they often require water, which can lead to drowning or inadequate laundry processing, and are not effective for dryers.
Innovation Solution
A method that controls the drum to move by an angle less than 90 degrees, then de-energizes, allowing the evaluation unit to detect a rotational-speed signal and interrupt the program if the signal exceeds a threshold, indicating a child's presence through a rocking motion, thereby avoiding water usage and ensuring safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water is fed into the drum to encourage a child to move, then the child's movement can be detected, but the child might choke on the water and suffocate or drown therein
Solution Approach 1:
The patent extracts the harmful element (water) from the detection system and replaces it with a mechanical excitation method. The drum is rotated back and forth mechanically to encourage child movement, while detection is achieved through sensors that do not require water injection, thereby eliminating the drowning risk while maintaining detection capability
Solution Approach 2:
The patent introduces an intermediary mechanical excitation mechanism (drum rotation) between the detection goal and the child. Instead of directly using water to provoke movement, the drum's mechanical motion serves as an intermediary that indirectly encourages the child to move, allowing detection without direct water contact
2Reliability
If water is fed into the drum to detect child movement, then movement can be encouraged, but it provides poorer starting conditions for programs where laundry should not be thoroughly dampened
Solution Approach 1:
The patent removes water injection from the system entirely, replacing it with mechanical drum excitation and sensor-based detection. This extraction eliminates the unwanted side effect of laundry dampening while preserving the core function of detecting child presence through movement analysis
Solution Approach 2:
The patent replaces the hydraulic/water-based detection system with a mechanical excitation system (drum rotation) combined with electronic sensing. This substitution allows movement detection through mechanical means rather than water injection, preventing laundry dampening while achieving the same safety detection goal
3Reliability
If water is fed into the drum to encourage child movement, then detection is possible, but it is an impediment for programs such as spinning or freshening-up with hot air
Solution Approach 1:
The patent creates a universal detection system based on mechanical drum excitation and sensor monitoring that functions across all program types. The same excitation and detection mechanism works for washing, spinning, freshening-up, and other programs, eliminating the need for program-specific water injection logic and enabling versatile application across different appliance functions
Solution Approach 2:
Instead of adapting the detection method to each specific program (water injection for washing, no water for spinning), the patent inverts the approach by using a program-independent mechanical excitation method that works universally. The detection system remains constant while adapting to different program requirements, rather than changing the detection method for each program
4Object-affected harmful factors
If the drum is moved by an angle of less than 90 degrees and then de-energized to detect rocking motion, then child detection can be achieved without water, but the method requires precise control and evaluation of rotational-speed signals
Solution Approach 1:
The patent employs self-service principles where the drum's own rotational motion and natural rocking behavior serve as the detection mechanism. The system uses the drum's inherent physical properties and motion characteristics, evaluated through rotational-speed sensors, to automatically detect child presence without requiring complex external intervention or additional complex control systems
Data Source
AI summary
A method for operating a domestic appliance with a housing, a rotationally movable drum disposed in the housing for receiving laundry, a motor for driving the drum, a control device for controlling the motor, and an evaluation unit. The method, once a program of the domestic appliance has started, includes controlling the motor via the controller such that the drum is driven by the motor and the drum is moved by an angle of less than 90 degrees. Upon attaining the angle the motor is de-energised. The method includes detecting a rotational-speed signal of the drum from when the motor is de-energised over a predetermined first period, and evaluating the detected rotational-speed signals via the evaluation unit by forming a value. The method also includes interrupting the program when the value is greater than a predetermined first threshold value.