Magnetic Hob Control Knob Retention for Precise Sensor Detection
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Solution Overview
Problem
Existing domestic appliance devices, such as hob devices, face challenges in achieving a simple construction with improved sensitivity and usability, often requiring complex magnetic systems and additional components like coils and permanent magnets, which can lead to magnetic interference and increased costs.
Innovation Solution
A domestic appliance device with a retaining plate element that exerts a main magnetic fastening force on the operating element, featuring a thin sheet metal element with unevenness and a permanent magnet, which forms a closed magnetic circuit and guides magnetic field lines through a sensor unit, eliminating the need for coils and enhancing magnetic field sensing precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If coils and permanent magnets are used to generate attractive force on the operating element, then the operating element can be held in place, but the construction becomes complex and magnetic interference increases
Solution Approach 1:
The patent extracts and eliminates the coils from the magnetic system, retaining only the permanent magnet and the retaining plate element. This simplification removes the complex electromagnetic generation mechanism while preserving the essential magnetic holding function through the permanent magnet's field interacting with the ferromagnetic retaining plate.
Solution Approach 2:
The patent replaces the electromagnetic system (coils generating magnetic fields) with a static magnetic system (permanent magnet). This substitution eliminates the need for electrical power and complex control while maintaining the holding force through the permanent magnet's inherent magnetic field.
2Strength
If a thick retaining plate element is used, then structural strength is improved, but magnetic field sensing precision deteriorates due to increased distance and interference
Solution Approach 1:
The patent optimizes the thickness parameter of the retaining plate element to a specific range (0.5-2mm), finding the optimal balance between structural strength and magnetic field sensing precision. This parameter optimization ensures the plate is thin enough for magnetic field penetration but thick enough for mechanical strength.
Solution Approach 2:
The patent introduces local quality variations in the retaining plate through recesses and protrusions at specific locations. These local structural modifications create magnetic field concentration zones that enhance sensing precision at critical areas without requiring the entire plate to be thin, thus maintaining overall structural strength.
3Ease of manufacture
If the retaining plate element is made completely flat, then manufacturing is simplified, but magnetic interference with sensor elements increases
Solution Approach 1:
The patent applies local quality modifications by introducing recesses and protrusions only in specific areas of the retaining plate where magnetic field concentration is needed for sensor operation. The majority of the plate remains flat for manufacturing simplicity, while localized features provide the necessary magnetic field management.
Solution Approach 2:
The recesses and protrusions in the retaining plate act as intermediaries that modify the magnetic field distribution. These features create air gaps and magnetic path modifications that reduce magnetic interference with sensor elements while maintaining the overall structural integrity and manufacturing feasibility of the plate.
4Reliability
If additional magnetic components are added to improve holding force, then the fastening reliability is improved, but the device complexity and cost increase
Solution Approach 1:
The retaining plate element serves multiple functions simultaneously: it provides structural support, acts as a magnetic flux conductor, creates magnetic field concentration zones for sensing, and provides the holding force through its interaction with the permanent magnet. This multi-functionality eliminates the need for separate components for each function.
Solution Approach 2:
The patent merges the structural support function and the magnetic holding function into a single retaining plate element. The plate combines ferromagnetic properties with mechanical strength, eliminating the need for separate structural and magnetic components, thus reducing overall device complexity while maintaining reliability.
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 configuration results in a cost-effective, compact, and ergonomically friendly design with reduced magnetic interference, allowing for precise sensing of operating movements and improved user experience while saving components and reducing complexity.
Implementation Method 1
the retaining plate element (14) exerts in the operating state a main magnetic fastening force on the operating element (12)
Implementation Method 2
which forms a closed magnetic circuit and guides magnetic field lines through a sensor unit
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a household appliance, in particular a cooking surface device, having at least one control element contact surface (10) with which a functionally coupled control element (12) makes contact in at least one operating state. In order to achieve a simple design, the household appliance comprises at least one retaining clip element (14) exerting a magnetic main attaching force on the control element (12) in the operating mode.