Blade Tensioner Spring Retaining Features
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Solution Overview
Problem
Existing blade-type chain tensioners face issues with excessive erosion of the bracket wall due to spring edge-to-wall contact in dynamically active chain drive systems and stress concentration at the central region of the blade shoe, leading to potential damage and reduced durability.
Innovation Solution
The design incorporates a shoe with first and second spring-receiving slots and locking tabs that maintain a minimum stand-off distance between the spring and the bracket wall, preventing direct contact and reducing friction, along with a spring with uninterrupted end edges to minimize wear and stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the spring is allowed to contact the bracket wall directly, then the tensioning force is effectively transmitted, but excessive erosion of the bracket wall occurs due to friction and stress concentration
Solution Approach 1:
The patent introduces locking tabs as intermediary elements between the spring and the bracket wall. These tabs extend into the spring-receiving slot and contact the spring edges, preventing direct contact between the spring and bracket wall while still allowing effective force transmission. The locking tabs act as mediators that transfer the tensioning force from the spring to the bracket structure without causing erosive friction.
Solution Approach 2:
The spring-receiving slot is segmented into multiple functional regions: the locking tabs create contact zones that are spatially separated from the bracket wall. This segmentation allows the spring to be restrained at specific points (at the tabs) while maintaining distance from the erosive contact zone (the bracket wall), thus preventing erosion while preserving force transmission.
2Device complexity
If the spring edges are allowed to contact the bracket wall, then the structure is simpler, but stress concentration occurs at the central region of the blade shoe leading to potential damage
Solution Approach 1:
The locking tabs serve as mediators that redistribute the stress from the spring edges away from the vulnerable central region of the blade shoe. By providing dedicated contact points at the tabs, the stress is concentrated in controlled locations rather than being distributed across the entire spring-bracket interface, preventing stress concentration damage to the shoe.
Solution Approach 2:
The locking tabs are pre-positioned within the spring-receiving slot to establish proper contact geometry before the tensioner is subjected to operational loads. This preliminary positioning ensures that stress is distributed optimally from the beginning of operation, preventing stress concentration and potential damage to the blade shoe central region.
3Reliability
If the spring is restrained closer to the bracket wall, then the tensioning effectiveness is improved, but friction and wear between the spring and bracket increase
Solution Approach 1:
The locking tabs act as intermediaries that maintain the optimal balance between tensioning effectiveness and wear prevention. By positioning the tabs at specific distances from the bracket wall and designing their geometry appropriately, they ensure the spring is restrained sufficiently for effective tensioning while maintaining clearance from the bracket wall to minimize friction and wear.
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
This configuration reduces erosion and stress on the bracket and blade shoe, enhancing durability and maintaining tensioning effectiveness by minimizing contact between the spring and bracket, thus reducing wear and failure rates.
Implementation Method 1
a metal spring installed therein to provide the shoe sub-assembly with the necessary rigidity and damping characteristics
Implementation Method 2
taking advantage of the flexibility, low friction, and good wear properties of the plastic shoe
Implementation Method 3
a metal spring installed therein to provide the shoe sub-assembly with the necessary rigidity and damping characteristics
Data Source
AI summary
A chain tensioner blade assembly shoe includes a first spring-receiving slot and a second spring-receiving slot. The first spring-receiving slot includes: (i) a first lower wall; (ii) a first outer wall; (iii) a first locking tab located adjacent the rear face of the shoe. The second spring-receiving slot includes: (i) a second lower wall; (ii) a second outer wall; (iii) a second locking tab located adjacent the rear face of the shoe. The first and second locking tabs extend only partially toward and are spaced from the inner surface of the shoe central portion. A spring is located in a spring-receiving region and includes a first end located in the first spring-receiving slot between the first outer wall and the first locking tab, a second end located in the second spring-receiving slot between the second outer wall and the second locking tab, and a central portion in contact with the inner surface of the shoe central portion. The first and second locking tabs maintain a stand-off distance between the spring and a bracket on which the shoe is mounted.