Cooktop Knob Assembly with Joint to Absorb Valve Shaft Misalignment
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Solution Overview
Problem
Existing cooking appliance knobs face misalignment issues due to assembly tolerance, leading to operational failures and aesthetic defects, and lack a reliable mechanism for fine adjustment of gas flow rate without separating components.
Innovation Solution
A knob assembly with a joint that absorbs positional errors between the knob and valve shafts, featuring a knob ring with a display device for setting and displaying timer and firepower levels, using a Hall sensor and magnet for precise rotation sensing, and a push-and-turn mechanism to prevent accidental rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a knob is directly connected to a valve shaft, then the structure is simple, but assembly tolerance causes misalignment and operational failure
Solution Approach 1:
A joint is introduced as an intermediary component between the knob and valve shaft. This joint includes a joint body with a first shaft coupling portion connected to the valve shaft and a second shaft coupling portion connected to the knob shaft, serving as a mediator that absorbs assembly tolerance and prevents misalignment while maintaining structural simplicity.
2Ease of manufacture
If the knob structure is simplified, then manufacturing is easier, but position error of the valve shaft cannot be absorbed
Solution Approach 1:
The joint acts as a mediator that absorbs position errors of the valve shaft through its coupling mechanism. The joint body with flexible coupling portions can accommodate manufacturing variations without requiring high-precision assembly, thereby maintaining ease of manufacture while achieving accurate knob positioning.
Solution Approach 2:
The joint allows for parameter changes in the coupling geometry to accommodate position errors. By designing the joint with specific geometric parameters that can vary within tolerance ranges, the system absorbs manufacturing variations while maintaining functional precision.
3Manufacturing precision
If a joint is added to absorb position error, then knob alignment is improved, but device complexity increases
Solution Approach 1:
The joint serves as a compact intermediary component that absorbs position errors without significantly increasing overall device complexity. Its integrated design with shaft coupling portions allows it to perform multiple functions (alignment, error absorption, force transmission) in a single component, minimizing the complexity increase.
4Device complexity
If the knob shaft is directly supported, then the structure is simple, but the knob cannot be stably supported
Solution Approach 1:
The joint body serves as an intermediary support structure for the knob shaft. It includes a second shaft coupling portion that receives and stably supports the knob shaft, providing reliable support while maintaining structural simplicity through its integrated design.
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 stabilizes the knob operation, improves appearance quality, enhances user convenience, and reduces the risk of gas leakage by accurately controlling the gas flow and preventing operational errors, while maintaining a compact design and reducing manufacturing complexity.
Implementation Method 1
using a Hall sensor and magnet for precise rotation sensing
Data Source
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.