Flexible Drive Tensioner With Variable Damping Shoe
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional tensioners for flexible drive systems are large, require significant mounting volume, have constant frictional dampening that inhibits tension maintenance, and involve complex manufacturing and assembly processes, leading to high costs.
Innovation Solution
A tensioner design featuring a spindle and tensioner arm with a biasing coil spring and a dampening shoe that provides variable frictional forces, allowing for compact size, efficient tensioning, and simplified manufacturing and assembly, using die-casting techniques and non-circular spring coils to enhance spring force and dampening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional tensioners are used, then sufficient tensioning force is provided, but the package volume is large
Solution Approach 1:
The tensioner arm is received within a housing that contains the spring and dampening mechanisms, creating a nested compact structure. The spindle is mounted within the housing, and the tensioner arm rotates about the spindle while being contained within the housing boundaries, achieving high tensioning force in a reduced package volume.
Solution Approach 2:
The tensioner employs a dynamic spring-based mechanism where the tensioner arm can rotate about the spindle axis. The spring provides dynamic tensioning force that adapts to belt tension requirements, while the dampening mechanism dynamically responds to oscillations. This dynamic design allows compact packaging while maintaining sufficient tensioning capability.
2Stability of the object's composition
If constant frictional dampening is provided, then oscillation is reduced, but the ability to maintain tension is inhibited
Solution Approach 1:
The dampening mechanism is applied locally at specific points where oscillation occurs (at the tensioner arm and pulley), while the spring mechanism maintains tension along the entire belt length. The dampening shoe contacts the tensioner arm at a localized friction interface, providing oscillation control without interfering with the overall tensioning function.
Solution Approach 2:
The dampening mechanism provides asymmetric dampening characteristics - the dampening shoe is positioned to engage the tensioner arm in one direction of rotation while allowing free movement in the opposite direction. This asymmetric design allows the tensioner to maintain tension effectively while providing dampening only when needed to control oscillation.
3Ease of manufacture
If die-casting techniques are used, then manufacturing cost is reduced, but manufacturing precision may be affected
Solution Approach 1:
The tensioner is divided into separate die-cast components including the housing, tensioner arm, and spindle that can be manufactured independently using cost-effective die-casting techniques. These segmented components are then assembled together, allowing each part to be optimized for its specific function while maintaining overall precision through careful design of mating surfaces and assembly features.
Solution Approach 2:
Multiple features are merged into single die-cast components to reduce the number of parts and assembly steps. The housing integrates mounting features, bearing surfaces, and dampening mechanism mounting locations. The tensioner arm combines the rotating element with attached dampening features, reducing the need for separate precision-machined parts.
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 tensioner achieves high tensioning forces with reduced package volume, simplified assembly, and cost-effective manufacturing, while providing asymmetric dampening that increases in the de-tensioning direction and decreases in the tensioning direction, optimizing performance and efficiency.
Implementation Method 1
A biasing coil spring acts between the spindle and the tensioning arm urging the tensioner arm to rotate about the first axis in a tensioning direction
Implementation Method 2
A bushing is mounted between the tensioner arm and spindle to allow the tensioner arm to pivot about the spindle and provide a first frictional force dampening movement of the tensioner arm about the spindle
Implementation Method 3
The dampening shoe is urged into and out of frictionally engagement with the tensioner arm when coils of the spring expand and contract, respectively providing a varying second frictional force
Data Source
AI summary
A tensioner in accordance with the present invention employs a spindle and a tensioner arm which are preferably manufactured by a suitable manufacturing process, such as die casting, negating a requirement for machining operations. The biasing spring of the tensioner is wound with wire having a non-circular cross section to increase the spring force of the spring compared to a similar spring wound with wire of circular cross section and, as the tensioner arm is moved away from the flexible drive, the diameter of the biasing spring expands and the coils press a dampening shoe into contact with a wall of the tensioner arm producing a dampening force. The tensioner is simple to assemble and requires a relatively small package volume for the biasing force it can produce.