Tapered Pin Locking for Foldable Handle Vibration
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Solution Overview
Problem
Existing walk-behind work machines with foldable operating handles experience relative vibration and rattling issues due to gaps between linking pins and fitting holes, which compromises the stability of the handle when locked in the usage position.
Innovation Solution
A tapered second linking pin is used, which fits into a corresponding pin-fitting hole, eliminating gaps and ensuring a stable locked state, while round holes formed using a drill method manage tolerance for improved fit and reduced vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cylindrical second linking pin is used to lock the operating handle, then the handle can be locked in the usage position, but gaps exist between the pin and fitting hole causing relative vibration and instability
Solution Approach 1:
The patent changes the geometric parameters of the second linking pin from a cylindrical shape to a tapered shape, where the diameter decreases from the base toward the distal end. This parameter change allows the pin to eliminate gaps with the fitting hole during insertion, providing a tight fit that prevents relative vibration while maintaining locking functionality.
Solution Approach 2:
The patent introduces asymmetry in the shape of the second linking pin by using a tapered geometry instead of a symmetric cylindrical shape. The asymmetric tapered form allows the pin to progressively engage with the fitting hole, eliminating play and ensuring stable locking without requiring perfect manufacturing tolerances.
2Stability of the object's composition
If tight tolerances are used for the pin and fitting hole to eliminate gaps, then vibration is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The tapered geometry of the second linking pin changes the dimensional parameters from a constant diameter to a variable diameter along the length of the pin. This allows the pin to achieve a tight fit in the fitting hole through its conical shape rather than requiring tight tolerances on a cylindrical pin, thereby simplifying manufacturing while maintaining stability.
Solution Approach 2:
The patent applies local quality by concentrating the fit-tightening function at the distal end of the pin where the tapered surface contacts the fitting hole. The varying diameter along the pin length allows different sections to serve different functions: the larger base provides structural strength while the smaller distal end achieves the tight fit, optimizing both manufacturing and performance.
Data Source
AI summary
A walk-behind work machine having a foldable operating handle is disclosed. The operating handle is swingable and foldable about a first linking pin relative to a handle-attachment part of a work-machine body from a usage position to a storage position and can be locked in a usage position by a second linking pin. The second linking pin is present on one of the operating handle and the handle-attachment part, and the distal end part of the second linking pin is formed in a tapered shape. The other of the operating handle and the handle-attachment part has a second pin-fitting hole allowing insertion and retraction of the distal end part. When the distal end part is fit into the second pin-fitting hole, no gap is present in the second pin-fitting hole due to the tapered surface of the distal end part, and the operating handle is locked in the usage position.