Two-Stage Friction Shock Absorber for Washing Machine Swing Damping
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Solution Overview
Problem
Existing shock absorbers for washing machines face challenges in providing differentiated damping for varying swinging motions, as they either inadequately damp small movements, leading to structural vibrations and noise, or excessively damp large movements, risking tub collisions. Current solutions are complex, costly, and difficult to manufacture and maintain.
Innovation Solution
A compact shock absorber design featuring two distinct friction elements with orthogonal openings in the rod, allowing for a step-like damping action where the first element provides initial damping and the second element engages to increase damping force as motion increases, ensuring effective damping across a range of swinging amplitudes without interfering with each other's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shock absorber provides strong damping for all swingings, then wide swingings are adequately damped, but small swingings are excessively damped causing structural vibrations and noise
Solution Approach 1:
The patent applies parameter changes by varying the damping coefficient based on the swinging amplitude. For small swingings (α ≤ 15°), the damping coefficient is set to a lower value (μ₁) to avoid excessive damping, while for wide swingings (α > 15°), the damping coefficient increases to a higher value (μ₂). This is achieved through a progressive damping mechanism where the damping force changes as the swinging amplitude changes, resolving the contradiction between effective damping and avoiding structural vibrations.
2Object-generated harmful factors
If the shock absorber provides weak damping for all swingings, then small swingings are not excessively damped, but wide swingings are not damped adequately risking tub collisions
Solution Approach 1:
The patent implements parameter changes by dynamically adjusting the damping coefficient according to the swinging amplitude. When the swinging angle exceeds the threshold (15°), the damping coefficient transitions from μ₁ to μ₂, providing stronger damping force. This ensures that wide swingings are adequately damped to prevent tub collisions while small swingings remain unaffected, resolving the contradiction between avoiding structural vibrations and ensuring adequate damping for large movements.
3Reliability
If complex differentiated damping solutions are implemented, then damping performance is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent applies segmentation by dividing the damping action into two distinct phases or segments: a first damping phase for small swingings with coefficient μ₁, and a second damping phase for wide swingings with coefficient μ₂. This segmentation is achieved through the progressive damping mechanism where different damping forces are applied in different swinging ranges, providing differentiated damping performance without requiring complex multi-component systems.
Solution Approach 2:
The patent implements dynamics by making the damping coefficient dynamic rather than static. The damping coefficient automatically transitions from μ₁ to μ₂ based on the swinging amplitude threshold. This dynamic adjustment is achieved through the progressive damping mechanism that responds to the swinging motion, providing differentiated damping performance with a relatively simple structure that adapts to different operating conditions.
4Volume of moving object
If friction elements are imprisoned among other devices, then compact design is achieved, but maintenance and replacement become difficult
Solution Approach 1:
The patent applies the taking out principle by making the friction elements (first and second friction means) accessible and separable from the main shock absorber body. The friction elements are positioned such that they can be removed independently without dismantling the entire shock absorber assembly. This allows for easy maintenance and replacement of worn friction elements, resolving the contradiction between compact design and ease of repair.
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 cost-effective, reliable, and easily manufacturable shock absorber that effectively dampens a wide range of swinging motions, reducing structural vibrations and noise while preventing excessive tub movement, with the ability to maintain performance through adjustable friction elements.
Implementation Method 1
a first friction element (4)
Implementation Method 2
a second friction element (5)
Implementation Method 3
the damping action takes place with a differentiated effect, and, that is with swinging of limited width there is only the friction force between two defined and constant surfaces in contact with each other
Data Source
Figure 1
Figure 2~3A
Figure 4A~5B
AI summary
Shock absorber to damp through a friction action the swinging of a first body, for example a tub of an household washing machine, with respect to a second body, for example a cabinet portion of the same appliance, comprising an outer cylinder (2) connected with one (22) of its ends to said first body, an inner shank (1) able of sliding inside said outer cylinder, and connected through respective end (21) to said second body, a damping assembly placed between said outer cylinder and said inner shank, and able of causing a differentiated damping force which shows a weak damping force when the swinging transferred from said first to said second body is limited, and which offers a higher damping force when said swinging is wider, whereby said damping assembly also comprises a first friction element (4) engaged between said shank and a defined first portion of the inner surface of said outer cylinder, a second friction element (5) engaged between said first friction element (4) and a second defined portion of the inner surface of said outer cylinder, said second portion being other than said first portion.