Radially Expanding Spring Tensioner for Asymmetric Damping
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Solution Overview
Problem
Conventional belt tensioners with high damping for torsional input and transient dynamic conditions can be unresponsive to slack belt conditions, and manufacturing variations, temperature changes, and wear affect damping performance, leading to reduced service life and increased sensitivity to belt slip.
Innovation Solution
An asymmetrically damped tensioner utilizing a radially expanding spring that provides frictional damping by expanding into contact with a bushing, allowing for responsive tensioning while minimizing axial forces and component robustness, thus reducing material costs and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high damping is used to control tensioner arm movement during torsional input and transient dynamic conditions, then the tensioner movement is effectively controlled, but the tensioner becomes unresponsive to slack belt conditions
Solution Approach 1:
The patent implements asymmetric damping by positioning the spring to expand in only one radial direction, creating frictional damping forces that resist tensioner arm movement in one direction while allowing free movement in the opposite direction. This asymmetric spring expansion mechanism enables the tensioner to provide stabilizing damping during torsional input and transient conditions while remaining responsive to slack belt conditions, directly resolving the technical contradiction
2Stability of the object's composition
If axial forces are used to create frictional damping by moving tensioner components, then damping is achieved, but the components must be more robust to withstand axial force over the lifetime of the tensioner
Solution Approach 1:
The patent transitions from conventional axial force-based frictional damping to radial force-based frictional damping. The spring expands radially outward to engage with the bushing, creating frictional damping forces in the radial dimension rather than relying on axial forces. This dimensional change allows the use of lighter, less robust components since radial forces are naturally contained within the support member structure, resolving the contradiction between achieving frictional damping and maintaining component strength
3Stability of the object's composition
If conventional damping mechanisms are used, then damping force is provided, but manufacturing variation, operating temperature and component break-in or wear cause damping variation making the tensioner unresponsive
Solution Approach 1:
The patent employs a self-adjusting spring expansion mechanism that automatically compensates for damping variations. The spring continuously maintains contact with the bushing through its expansion force, and the frictional damping is self-regulating based on the relative movement between components. This self-service mechanism ensures consistent damping performance despite manufacturing variations, temperature changes, and component wear over time, resolving the contradiction between providing damping force and maintaining damping consistency
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 enables effective control of tensioner movement during high torsional input while maintaining responsiveness to slack conditions, reducing material costs and weight by containing radial forces within a support member, thereby enhancing service life and reducing sensitivity to damping variations.
Implementation Method 1
the spring is positioned where it can radially expand into contact with the protrusion of the bushing as the arm is rotated in a direction opposite the direction of tensioning engagement such that the bushing is urged radially outward relative to the arm arbor to provide frictional damping
Implementation Method 2
a spring coupled to the arm urging the arm to rotate about the first axis into tensioning engagement with a power transmitting element
Data Source
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AI summary
A tensioner is disclosed that may be part of a power system where the tensioner provides tension to an endless power transmitting element such as a belt, chain, or other continuous loop. The tensioner has an arm that is rotatable about a first axis and includes an arm arbor having a slot therethrough, a bushing having a protrusion and being positioned adjacent the arm arbor with the protrusion received in the arm arbor's slot, and a spring coupled to the arm urging the arm to rotate about the first axis into tensioning engagement with a power transmitting element. The spring is positioned where it can radially expand into contact with the protrusion of the bushing as the arm is rotated in a direction opposite the direction of tensioning engagement such that the bushing is urged radially outward relative to the arm arbor to provide frictional damping.