Parallel Link Mechanism With Bearing Layout for Wide-Angle Rigidity
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Solution Overview
Problem
Existing parallel link mechanisms face challenges in achieving a wide operating range and high rigidity while maintaining compactness and lightweight design, often resulting in reduced bearing life due to interference and increased dimensions.
Innovation Solution
A parallel link mechanism with a trinodal structure and four revolute pairs, incorporating bearings with a critical oscillation angle smaller than the maximum bending angle to reduce friction and enhance durability, allowing for a two-degrees-of-freedom movement and constant velocity transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the link length is increased to expand the operating range, then the operating range increases, but the dimensions of the mechanism increase and the apparatus becomes bulky
Solution Approach 1:
The link mechanism is divided into multiple links (first link, second link, third link, fourth link) connected by revolute pairs, allowing the mechanism to achieve extended operating range through angular coordination of segments rather than increasing overall link length
Solution Approach 2:
The parallel link mechanisms are arranged in a nested configuration where multiple link mechanisms operate within a compact spatial envelope, enabling wide operating range without increasing overall mechanism dimensions
2Adaptability or versatility
If the link length is increased to expand the operating range, then the operating range increases, but the rigidity of the mechanism decreases
Solution Approach 1:
The mechanism uses multiple shorter links instead of one long link, maintaining rigidity through shorter structural segments while achieving extended operating range through the coordinated angular movement of segmented links
Solution Approach 2:
Multiple parallel link mechanisms are combined to work together, where the collective action of multiple rigid segments maintains overall mechanism rigidity while enabling extended operating range through parallel operation
3Strength
If the revolute pair section size is increased to improve rigidity, then the rigidity increases, but interference between members occurs and the operating range is reduced
Solution Approach 1:
The revolute pair sections are designed with locally optimized properties where the connection structures have sufficient rigidity for structural integrity while maintaining compact dimensions to prevent interference, achieving rigidity through local structural optimization rather than overall size increase
Solution Approach 2:
The link mechanisms employ asymmetric link configurations where link lengths and angles are specifically optimized to prevent interference between members during operation, allowing compact revolute pair sections without sacrificing operating range
4Adaptability or versatility
If the link length is increased, then the operating range increases, but the weight capacity of the travelling plate is limited to a small value
Solution Approach 1:
The mechanism uses multiple shorter links instead of one long link, where the segmented structure maintains higher rigidity-to-weight ratio, enabling the mechanism to support heavier loads while achieving extended operating range through angular coordination of segments
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 mechanism achieves a wide operating range with improved rigidity and compactness, extending bearing life by minimizing interference and reducing rotational resistance, while maintaining constant speed transmission between input and output shafts.
Implementation Method 1
each revolute pair of each of the link mechanisms includes one pair of pair constituent members connected to each other via a bearing
Implementation Method 2
a geometric model of the link mechanism represented by lines shows symmetry between a proximal end side portion and a distal end side portion with respect to a center portion of the intermediate link member
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A parallel link mechanism includes proximal end side and distal end side link hubs, and three or more link mechanisms. Each link mechanism is a trinodal link mechanism including four revolute pairs, and includes proximal side and distal side end link members and an intermediate link member. In each revolute pair of the link mechanism, a pair of pair constituent members is connected to each other via a bearing. A shaft portion provided in one pair constituent member is fitted on an inner periphery of an inner ring of the bearing, and an annular inner face forming portion provided in the other pair constituent member is fitted on an outer periphery of the outer ring of the bearing.