Gas cooking hob comprising a control element

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Solution Overview

Problem

Gas cooking hobs with control elements featuring sliding contacts often malfunction due to contamination from cooking liquids, which impairs the control lighting functionality, and existing solutions do not effectively indicate the position detected by magnetic sensors.

Innovation Solution

A control element with a printed circuit board and magnetic sensors that contactlessly detect the position and orientation of a rotatable or slidable shaft, using LEDs for control lighting, where the direction of rotation activates or deactivates the gas burner, and at least one LED is deactivated after a predetermined time, ensuring functionality even with contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sliding contacts are used in the control element, then the control element can detect shaft position, but the control element malfunctions when contaminated by cooking liquids

Engineering Contradiction:
Improvecontrol element functionalityVSAvoidcontamination by cooking liquids
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical sliding contact system with a magnetic field-based detection system. Magnetic sensors detect the position and orientation of a permanent magnet attached to the shaft without physical contact. This eliminates the harmful effect of cooking liquid contamination on electrical contacts while maintaining the ability to detect shaft position for controlling gas burners.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a permanent magnet as an intermediary between the shaft and the magnetic sensors. The magnet carries information about shaft position and orientation through its magnetic field, which the sensors detect without physical contact. This intermediary enables contamination-free signal transmission while preserving control functionality.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If magnetic sensors are used for contactless detection, then the control element is resistant to contamination, but the detected position is not indicated to the user

Engineering Contradiction:
Improveresistance to contaminationVSAvoidshaft position indication
Core Design Contradiction:
Object-affected harmful factorsVSLoss of information

Solution Approach 1:

The patent implements a feedback system where control lighting (LEDs) provides visual information about the shaft position detected by the magnetic sensors. The control lighting is activated or deactivated based on the detected position, giving the user immediate feedback about the current state without requiring physical inspection of the control element.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent uses control lighting with light emitting diodes to indicate different shaft positions through illumination or deactivation. The visual state of the LEDs changes according to the detected position, providing intuitive information to the user about the current setting while maintaining the contamination-resistant magnetic detection system.

Inventive Principle:
Principle #32Color changes

3Loss of information

If control lighting is continuously activated, then the user can see the shaft position, but energy is wasted when the burner is deactivated

Engineering Contradiction:
Improveshaft position indicationVSAvoidenergy consumption of control lighting
Core Design Contradiction:
Loss of informationVSUse of energy by moving object

Solution Approach 1:

The patent implements conditional activation of the control lighting based on the operational state of the gas burner. The control lighting is activated when the burner is on and deactivated when the burner is off, creating a periodic or conditional operation pattern that reduces energy consumption while maintaining necessary visual feedback during active operation.

Inventive Principle:
Principle #19Periodic action

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 provides reliable indication of the shaft position and orientation, maintaining control element functionality despite contamination, and allows for precise control of gas burners and gas flow, ensuring accurate and clean operation.

Implementation Method 1

the magnetic sensor is responsive to the magnetic element and generate signals regarding to the rotational position of the rotary knob

Methodology Applied
Scientific EffectMagnetic field sensing: Magnetic Field

Implementation Method 2

the control lighting includes at least one light emitting diode (LED)

Methodology Applied
Scientific EffectLight emitting diode: Light Emitting Diode

Data Source

PatentEP3396254B1Gas cooking hob comprising a control element
Publication Date: 2019.11.27 ELECTROLUX APPLIANCES
  • EP3396254B1 patent drawingFigure 1~2

AI summary

The present invention relates to a control element (10) for a gas cooking hob, in particular a rotary control element (10) for a gas cooking hob. The control element (10) comprises a moveable shaft (12) and a permanent magnet (14) rigidly connected to said shaft (12). The control element (10) comprises a stationary printed circuit board (18). The printed circuit board (18) includes a cut-out (20) penetrated by the moveable shaft (12). The control element (10) comprises a magnetic sensor (22) arranged on the printed circuit board (18) and beside the cut-out (20). The magnetic sensor (22) is responsive to the permanent magnet (14), so that the magnetic sensor (22) generates at least one control signal depending on the position and/or orientation of the shaft (12). The control element (10) comprises a control lighting including at least one light emitting diode (LED). The control lighting is controlled via the magnetic sensor (22).