Crankshaft Assembly With Offset Engaging Members for Vibration Reduction
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Solution Overview
Problem
Handheld power tools such as hedge trimmers and chainsaws experience undesirable vibrations due to the translational motion produced by their crankshafts, necessitating improved mechanisms to reduce these vibrations.
Innovation Solution
The crankshaft mechanism incorporates offset engaging members with an offset angle greater than 180°, coupled with connecting rods to reciprocating elements, which reduces secondary vibrations by balancing the crankshaft's motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional crankshaft with 180° offset engaging members is used, then the crankshaft can convert rotational motion to translational motion effectively, but it produces undesirable vibrations
Solution Approach 1:
The patent applies asymmetry by configuring the crankshaft with engaging members offset by more than 180 degrees (e.g., 210-240 degrees) rather than the conventional 180 degrees. This asymmetric angular offset creates unbalanced translational forces that counteract each other to reduce vibrations while maintaining effective cutting motion. The asymmetric geometry of the engaging members relative to the rotational axis enables vibration reduction without sacrificing productivity.
2Object-affected harmful factors
If the offset angle between engaging members is increased beyond 180°, then vibrations are reduced, but the crankshaft geometry becomes more complex
Solution Approach 1:
The patent applies parameter changes by modifying the offset angle parameter from the conventional 180 degrees to a range of 210-240 degrees. This parameter adjustment optimizes the balance between vibration reduction and geometric simplicity. By selecting specific angular values within this range, the patent achieves significant vibration reduction while maintaining manufacturable and relatively simple crankshaft geometry.
Data Source
AI summary
A crankshaft assembly is provided. The crankshaft assembly includes a crankshaft including a first engaging member and a second engaging member. The second engaging member is spaced from the first engaging member in a direction of a rotational axis of the crankshaft. A first center point of the first engagement member is offset from a second center point of the second engagement member an offset angle defined about the rotational axis. The offset angle is 270°.