Cooktop Knob Assembly With Tolerance-Absorbing Joint Support

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Solution Overview

Problem

Existing knob assemblies for cooking appliances face issues with misalignment due to assembly tolerance, leading to operational failures and reduced appearance quality, and lack a stable support structure for the knob and display device, which can result in safety risks and user inconvenience.

Innovation Solution

A fire power controlling knob assembly with a knob ring that supports the knob and includes a joint to absorb positional errors, a Hall sensor for precise rotation measurement, and a display device integrated into the knob ring for easy operation and safety features, ensuring accurate operation and improved user experience.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional knob assembly is used without a support structure, then the device complexity is reduced, but misalignment occurs due to assembly tolerance leading to operational failures

Engineering Contradiction:
Improveoperational reliabilityVSAvoidsupport structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A support structure is introduced as an intermediary component between the knob and the valve assembly. This support structure includes a support body that receives the knob shaft and a support plate that couples to the front panel, acting as a mediator to absorb assembly tolerances and prevent misalignment between the knob and valve, thereby improving operational reliability without requiring complex adjustment mechanisms

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If the knob is directly coupled to the valve shaft without a joint, then the device complexity is minimized, but positional errors and misalignment occur reducing appearance quality

Engineering Contradiction:
Improvealignment precisionVSAvoidjoint structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

A joint is introduced as an intermediary coupling mechanism between the knob shaft and the valve shaft. The joint includes a joint body with a first shaft coupling portion for the valve shaft and a second shaft coupling portion for the knob shaft, along with a joint spring to allow relative movement. This intermediary structure absorbs positional errors and misalignment, ensuring precise alignment and high appearance quality while maintaining a relatively simple structure

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The joint spring changes the mechanical parameter of rigidity by allowing controlled relative movement between the knob shaft and valve shaft. This elastic deformation capability enables the system to accommodate assembly tolerances and maintain alignment precision without requiring extremely tight manufacturing tolerances or complex adjustment mechanisms

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If a stable support structure is implemented, then misalignment and safety risks are reduced, but the device complexity increases

Engineering Contradiction:
Improvesafety risksVSAvoidsupport structure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The support structure acts as a safety intermediary by providing a stable foundation that prevents misalignment and operational failures. The support body receives the knob shaft, the support plate couples to the front panel, and the joint connects the knob assembly to the valve assembly, creating a stable mechanical chain that eliminates safety risks related to misalignment and loose connections while maintaining a relatively simple structure

Inventive Principle:
Principle #24Intermediary (Mediator)

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 a stable and accurate operation of the knob assembly, reducing the risk of misalignment and safety hazards while enhancing user convenience and appearance quality by allowing precise control and display of fire power and timer settings.

Implementation Method 1

a Hall sensor for precise rotation measurement

Methodology Applied
Scientific EffectHall effect: Hall Effect

Data Source

PatentEP3367003B1Knob assembly for cook top
Publication Date: 2023.04.05 LG ELECTRONICS INC
  • EP3367003B1 patent drawingFigure 1
  • EP3367003B1 patent drawingFigure 2
  • EP3367003B1 patent drawingFigure 3

AI summary

A knob assembly includes a front panel, a knob located at a front side of the front panel and configured to rotate based on operation by a user, a knob shaft that is coupled to the knob and that extends through the front panel, a supporting pipe that receives the knob shaft and that supports the knob shaft, the supporting pipe being configured to maintain a position relative to the front panel, a valve configured to control supply of gas to the appliance, a valve shaft connected to the valve and configured to control the valve to adjust a flow rate of gas based on rotation of the valve shaft, and a joint that couples the knob shaft to the valve shaft and that is configured to transfer at least one of a rotational motion or a linear motion of the knob shaft to the valve shaft.