Home appliance with knob assembly
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Solution Overview
Problem
Existing knob rotation limiting structures in cooking appliances require additional components and increased assembly time, leading to noise and wear due to friction, and complicate management and repair, as they involve a locker and rear surface member that need to be fixed and disassembled.
Innovation Solution
A knob assembly with a joint that reduces positional deviations between shafts and incorporates a rotation limiting structure within the frame and rotation member, allowing for smooth operation without additional components, noise, or increased assembly time, by using a rotation limiting groove and projection system that aligns the knob's position accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locker and rear surface member are added to prevent unintentional rotation, then the knob's anti-rotation capability is improved, but the device complexity and assembly time increase
Solution Approach 1:
The rotation limiting function is merged into the existing frame and rotation member structures. The frame includes a rotation limiting groove and the rotation member includes a rotation limiting projection, eliminating the need for separate locker and rear surface member components while maintaining the anti-rotation capability.
Solution Approach 2:
The frame and rotation member serve multiple functions: the frame provides structural support and includes the rotation limiting groove, while the rotation member both rotates with the knob and includes the rotation limiting projection. This multi-functionality reduces the need for additional specialized components.
2Reliability
If a locker and rear surface member are added to prevent unintentional rotation, then the knob's anti-rotation capability is improved, but the assembly time increases
Solution Approach 1:
The rotation limiting function is merged into the existing frame and rotation member structures. The frame includes a rotation limiting groove and the rotation member includes a rotation limiting projection, eliminating the need for separate locker and rear surface member components while maintaining the anti-rotation capability.
3Reliability
If the boss and rear surface member continuously receive elastic force, then the knob remains engaged with the rotation limiting structure, but noise and wear increase due to friction
Solution Approach 1:
The harmful continuous elastic force and friction are extracted from the system by changing the engagement mechanism. Instead of continuous contact with elastic force, the new design uses periodic engagement where the rotation limiting projection fits into the rotation limiting groove only when needed, reducing continuous friction and noise.
Solution Approach 2:
Instead of using elastic force to maintain continuous contact between components, the design inverts the approach by using geometric constraint through the groove-projection fit. The rotation limiting projection passively engages with the rotation limiting groove through shape complementarity rather than active elastic forcing, reducing friction-based noise and wear.
4Reliability
If the locker is disposed in the space encircled by the knob ring, then the rotation limiting function is achieved, but the management and repair process becomes complicated
Solution Approach 1:
The rotation limiting function is merged into the existing frame and rotation member structures. The frame includes a rotation limiting groove and the rotation member includes a rotation limiting projection, eliminating the need for separate locker and rear surface member components while maintaining the anti-rotation capability.
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 ensures smooth operation of the knob, reduces noise, and simplifies management and repair by eliminating the need for additional components and assembly hours, while maintaining accurate alignment and preventing unintentional rotation.
Implementation Method 1
The first shaft 41 is elastically supported by an elastic component forward in the axial direction. That is, when the knob 30 is pushed rearward in the axial direction, the knob 30 moves rearward, but when the knob 30 is released from the force of pushing the knob 30, the knob 30 receives a force for returning forward from the elastic component.
Data Source
AI summary
A cooking appliance may include a panel provided with a through hole; a knob assembly installed at the panel; and a valve disposed inside of the panel. The knob assembly may include a shaft that passes through the through hole, configured to move in an axial direction between a first axial position and a second axial position and rotate around a rotational center; a knob disposed outside of the panel, connected to the shaft, and configured to move with the shaft in the axial direction and rotate with the shaft; a frame installed at the panel and configured to support rotation of the shaft; a rotational member connected to the shaft, configured to move and rotate with the, and having a diameter larger than a diameter of the shaft; a first rotation limiting portion provided on the frame at a first circumferential position; a second rotation limiting portion provided to the rotational member at a second circumferential position, engaged with the first rotation limiting portion at the first axial position and interfering therewith in the circumferential direction in a state in which the first circumferential position and the second circumferential position correspond to each other, and disengaged from the first rotation limiting portion at the second axial position and not interfering therewith the circumferential direction; and an elastic member configured to elastically support the shaft.