V-Shaped Spring Drive Train Assembly With X-Hinges to Reduce Fretting
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Solution Overview
Problem
Existing personal care device drive trains with nodally mounted V-shaped springs are prone to failure due to fretting fatigue and require numerous components, leading to increased costs and manufacturing time, and exhibit inefficient behavior due to hysteresis.
Innovation Solution
A drive train assembly featuring a V-shaped spring with X-shaped spring hinges at both ends, eliminating the need for nodal mounting and reducing component complexity, thereby enhancing robustness and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a V-shaped spring is nodally mounted at both ends, then the spring can be suspended and functional, but it is prone to fretting fatigue and failure at the clamped ends
Solution Approach 1:
The patent removes the harmful clamped end mounting from the spring design. Instead of clamping the spring ends to mounting structures, the spring is configured with free ends that engage directly with the drive train components through elastic deformation. This extraction of the clamped mounting eliminates the fretting fatigue interface while maintaining spring functionality.
Solution Approach 2:
The patent inverts the traditional mounting approach. Rather than fixing the spring ends to rigid mounting structures and allowing the spring body to deform, the design allows the spring ends to freely engage with moving components. The mounting structures become flexible through the spring's elastic arms, reversing the rigidity-flexibility relationship and eliminating stress concentration at mounting points.
2Reliability
If a spring is mounted at both ends with numerous parts, then the spring can be securely attached, but component costs and manufacturing complexity increase
Solution Approach 1:
The patent merges the spring mounting function with the spring structure itself. The elastic arms of the spring directly engage with the drive shaft and stator, eliminating the need for separate mounting brackets, clamps, and fasteners. The spring body serves both as the elastic element and as the mounting interface, reducing part count while maintaining secure attachment.
Solution Approach 2:
The spring structure performs multiple functions simultaneously: it provides elastic suspension, transmits mechanical forces, and serves as its own mounting mechanism. The elastic arms both support the spring weight and engage with drive train components, eliminating the need for dedicated mounting hardware and simplifying the overall assembly.
3Stability of the object's composition
If nodal mounting is used to suspend the spring, then the spring can be positioned, but hysteresis behavior occurs resulting in drive inefficiency
Solution Approach 1:
The patent removes the nodal mounting point from the spring system. Instead of suspending the spring at a node point along its length, the spring is configured with elastic arms that extend from the ends to engage with drive train components. This extraction eliminates the hysteresis associated with nodal mounting while maintaining stable positioning through the elastic engagement of the arms.
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 non-nodally mounted V-shaped spring drive train assembly is more resistant to stress and fatigue, reduces hysteresis, and simplifies manufacturing, resulting in a more efficient and cost-effective personal care device drive train.
Implementation Method 1
a V-shaped spring that is not nodally mounted... The V-shaped spring comprises an X-shaped spring hinge on both ends
Data Source
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AI summary
A drive train assembly (200) for a personal care device (10), comprising a torsion spring (210) suspended between a first end mount (220) and a second end mount (230), the torsion spring comprising a first end mounted to the first end mount and a second end mounted to the second end mount, wherein the first and second ends of the torsion spring each comprises a cross flexure spring hinge (250, 260).