Rear Appliance Foot Mechanism With Low-Torque End-Stop Slipping
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Solution Overview
Problem
Existing adjustable feet for electric household appliances, such as washing machines and dishwashers, face issues with managing the stroke-end position, often requiring excessive user effort and risking thread damage due to torque application, especially when the foot is raised and controlled from the front.
Innovation Solution
A height-adjustable foot design featuring a stem with anti-rotation means, a toothed wheel, and elastic axial biasing elements that allow the toothed wheel to 'slip' at the stroke-end position with minimal torque, utilizing a synthetic plastic body with elastically deformable teeth to facilitate easy adjustment and reduce user effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nut screw consisting of two or more half-elements held together by a spring is used to allow thread slipping at stroke-end, then the thread can slip to stroke-end position, but the construction becomes complex and cumbersome and requires high torque from the user
Solution Approach 1:
The patent extracts the spring element from the nut screw assembly and places it separately as elastic axial biasing means. This separates the functions of the nut screw (thread engagement) and the spring (biasing force), simplifying the overall construction while maintaining the thread slipping capability at stroke-end.
Solution Approach 2:
The patent introduces an intermediary elastic axial biasing means that acts on the toothed wheel rather than directly on the nut screw. This intermediary mechanism allows the toothed wheel to be pushed against the first abutting means, creating the necessary condition for thread slipping without requiring a complex split nut screw design.
2Ease of operation
If a complex spring-based nut screw is used to enable thread slipping, then stroke-end management is improved, but the device becomes cumbersome and requires high user torque
Solution Approach 1:
By extracting the spring from the nut screw and positioning it to act on the toothed wheel, the patent reduces the torque required at the control interface. The spring force is applied indirectly through the toothed wheel mechanism, distributing the force requirement and reducing the peak torque the user must apply.
Solution Approach 2:
The patent creates a dynamic system where the elastic axial biasing means automatically adjusts the positioning of the toothed wheel based on the operational state. During normal operation, the spring maintains the toothed wheel against the second abutting means for precise control. At stroke-end, the mechanism naturally transitions to allow slipping with minimal additional torque.
3Device complexity
If the toothed wheel is held against the second abutting means by elastic axial biasing means, then the mechanism becomes simpler and more reliable, but the toothed wheel must be axially mounted with clearance
Solution Approach 1:
The patent segments the axial space into distinct zones: a first zone between the first abutting means and the toothed wheel for clearance and elastic deformation, and a second zone between the toothed wheel and the second abutting means for normal operation. This segmentation allows the mechanism to accommodate both the biasing force and the stroke-end slipping function.
Solution Approach 2:
The patent changes the positional parameter of the toothed wheel by introducing axial clearance. This clearance allows the toothed wheel to move axially between two abutting means, enabling the elastic axial biasing means to function while maintaining the ability to engage with the first abutting means at stroke-end for thread slipping.
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 simple, cost-effective, and reliable mechanism for adjusting the foot height with minimal user effort, preventing thread damage and ensuring smooth operation by leveraging elastic deformation to manage the stroke-end position without excessive torque.
Implementation Method 1
the toothed wheel which is normally held by the elastic axial biasing means against the second abutting means, is pushed by the 'unscrewing' action of the end length of the first screw means against the first abutting means, thus straining the elastic axial biasing means
Data Source
Figure 1
Figure 2~4
AI summary
An adjustable foot (1) including a body (3) integrally fastenable to a casing of the electric household appliance (2), a stem (12) slidingly carried by the body, floor resting means (13), first screw means (16) operatively associated with the stem and provided with anti-rotation means (18), a toothed wheel (19) carried by the body so as to be coaxial to the stem and idle about a substantially vertical symmetry axis (A) of the latter, second screw means (20) operatively associated with the toothed wheel and cooperating with the first screw means (16) for vertically translating the stem (12) in response to a rotation of the toothed wheel (19), and control means (21) for the toothed wheel; wherein the toothed wheel (19) is axially mounted with clearance (G) between opposite first and second abutting means (22,23) of the body; the latter being provided with elastic axial biasing means (24) cooperating with the toothed wheel (19) and arranged on the side opposite to the end length (26) of the first screw means (16), which has a thread height (H) gradually decreasing towards the elastic means (24).