Asymmetric Friction Torque Pivot Device Using Slotted Sleeve
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Solution Overview
Problem
Existing pivot devices require complex configurations or multiple components to generate asymmetric friction torque, which increases costs and manufacturing complexity, and often necessitate lubrication, whereas there is a need for simpler, cost-effective solutions that can provide differential resistance to opening and closing motions.
Innovation Solution
A pivot device comprising a shaft and a sleeve with a longitudinal gap, surrounded by a helical compression element that applies a compressive force, allowing for asymmetric friction torque without direct contact between the compression element and the shaft, utilizing a slotted sleeve and a helical compression element to create a wrap effect and deform the sleeve, thereby generating differential rotational resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex configurations or multiple components are used to generate asymmetric friction torque, then the desired differential resistance is achieved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The device segments the friction interface by introducing a longitudinal gap in the sleeve, creating distinct contact zones on either side of the gap. This segmentation allows asymmetric friction torque generation because the compression element can apply different compressive forces to each side of the gap depending on rotation direction, achieving the desired differential resistance without complex multi-component configurations
Solution Approach 2:
The compression element applies localized compressive forces to specific regions of the sleeve through the longitudinal gap. By concentrating the compressive force at the gap location rather than distributing it uniformly, the device creates asymmetric friction characteristics locally at the gap while maintaining a simple overall structure, resolving the contradiction between reliable asymmetric torque generation and device simplicity
2Strength
If traditional pivot device configurations are used, then structural integrity is maintained, but lubrication is required which increases maintenance needs
Solution Approach 1:
The longitudinal gap in the sleeve acts as an intermediary feature that modifies the friction interface. By introducing this gap, the compression element can apply controlled compressive forces that generate sufficient friction torque without requiring lubrication, as the asymmetric compression creates stable contact pressure at the gap edges. This eliminates maintenance needs while preserving structural integrity through the controlled deformation mechanism
Solution Approach 2:
The compression element with the longitudinal gap creates a self-regulating friction mechanism where the asymmetric compression forces automatically adjust during rotation. The gap allows the sleeve to deform and redistribute stresses, creating stable friction characteristics without external lubrication or maintenance, making the device self-sufficient and eliminating lubrication requirements
3Ease of operation
If asymmetric friction torque is generated using conventional methods, then differential resistance is achieved, but manufacturing cost and complexity increase
Solution Approach 1:
The device introduces asymmetry through the longitudinal gap in the sleeve and the corresponding compression element geometry. This asymmetric configuration creates different friction characteristics for clockwise versus counter-clockwise rotation, achieving differential resistance for ease of operation. The asymmetry is achieved through a simple gap feature rather than complex asymmetric components, maintaining ease of manufacture
Solution Approach 2:
The compression element changes the normal force parameter asymmetrically based on rotation direction. By applying different compressive forces to either side of the longitudinal gap depending on rotation direction, the device achieves variable friction torque that facilitates differential resistance for ease of operation. This parameter change is achieved through the mechanical deformation of the gapped sleeve rather than complex adjustable mechanisms, keeping manufacturing simple
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 achieves asymmetric friction torque with a simpler design, reducing manufacturing complexity and eliminating the need for lubrication, while providing greater resistance to opening motions and easier closure, thus enhancing the functionality and efficiency of pivot devices in applications like clam-shell designs and locking mechanisms.
Implementation Method 1
a first torque required to rotate the sleeve and the shaft with respect to one another in a first direction differs from a second torque required to rotate the sleeve and the shaft with respect to one another in a second direction opposite to the first direction
Implementation Method 2
utilizing a slotted sleeve and a helical compression element to create a wrap effect and deform the sleeve, thereby generating differential rotational resistance
Data Source
AI summary
A pivot device having asymmetric friction torque is provided. The pivot device includes a shaft extending along a longitudinal axis, a sleeve surrounding the shaft, the sleeve defining a gap extending longitudinally, the sleeve and the shaft being configured for rotation with respect to one another about the longitudinal axis, and a helical compression element surrounding the sleeve and exerting a compressive force onto the sleeve, wherein a first torque required to rotate the sleeve and the shaft with respect to one another in a first direction differs from a second torque required to rotate the sleeve and the shaft with respect to one another in a second direction opposite to the first direction. A method for providing a pivot device asymmetric friction torque is also provided.