Chain Tensioner Pivot Pin Design for Assembly and Wear Reduction
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Solution Overview
Problem
Existing chain tensioners face issues with component complexity, assembly difficulties, and poor durability due to elastic deformation and looseness, leading to instability and increased wear in maintaining chain tension between close-spaced shafts.
Innovation Solution
A chain tensioner design featuring a pivot pin part with a first pin portion and a second pin portion, where the guide shoe has a mating hole and a guide part with a slit, allowing for stable pivot support without deformation, reducing wear and breakage, and improving durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the guide shoe is pivotally supported directly on the arm using a through hole and pin structure, then the assembly process becomes complex requiring alignment and retention steps, but the pivot support is stable
Solution Approach 1:
The patent merges the pin and bushing into an integrated pivot pin part with a non-cylindrical surface that directly engages the guide shoe's pivot hole, eliminating the need for separate pin members and retention steps. This integration simplifies the assembly process while maintaining stable pivot support.
Solution Approach 2:
The pivot pin part serves multiple functions: it acts as both the pivot axis and the retention mechanism through its non-cylindrical surface engagement. This multi-functionality reduces the number of components needed while ensuring stable pivot support without requiring separate retention features.
2Ease of manufacture
If the frame with U-shaped cross section is elastically deformable to allow easy assembly, then the guide shoe can be installed without complex alignment, but the guide shoe displaces relative to the tensioner body during use compromising chain stabilization
Solution Approach 1:
The patent applies local quality by making only the specific engagement region (the pivot hole and non-cylindrical surface interface) capable of slight elastic deformation for easy assembly, while the overall frame structure and guide shoe body remain rigid to maintain chain stabilization function during operation.
Solution Approach 2:
The patent changes the geometric parameter of the pivot pin part by using a non-cylindrical surface instead of a cylindrical one. This geometric change allows the engagement to be slightly elastic for easy assembly while maintaining positional stability during use, resolving the contradiction between assembly ease and operational reliability.
3Ease of manufacture
If the bushing part is formed as a tube with a notch that is elastically spread to fit the pin, then assembly is simplified, but the bushing part undergoes deformation during use leading to poor chain stabilization and durability
Solution Approach 1:
The patent extracts the problematic elastic deformation feature (the notch) from the bushing part and replaces it with a non-cylindrical surface engagement. This extraction eliminates the source of repeated deformation while maintaining the simplified assembly advantage, thereby improving durability.
Solution Approach 2:
Instead of making the bushing part elastically deformable to achieve easy assembly (conventional approach), the patent inverts the approach by making the pivot pin part have a non-cylindrical surface that engages the circular pivot hole. This inversion allows easy assembly without requiring the bushing part to undergo repeated elastic deformation, thus improving durability.
4Ease of manufacture
If the pivot pin part has a non-cylindrical surface to pass through a groove at a predetermined angle, then assembly is simplified without elastic deformation, but the sliding area and cross-sectional area are reduced leading to looseness and severe wear
Solution Approach 1:
The patent applies asymmetry by giving the pivot pin part a non-cylindrical surface that is asymmetric in cross-section. This asymmetric shape provides both the angle-guiding function for simplified assembly and sufficient contact area for precise pivot support, resolving the contradiction between assembly ease and pivot precision.
Data Source
AI summary
To provide a simple design chain tensioner that enables formation with fewer components and simplifies assembling process, and is capable of driving a chain stably, thereby reducing wear or occurrence of breakage and improve durability. The chain tensioner 100 includes a chain-drive guide shoe 130 pivotally supported on an arm 120 provided to a tensioner body 110. A bushing part 140 of the chain-drive guide shoe 130 includes a mating hole 141 to mate with a first pin portion 122 that extends from the distal end of the arm 120 to one lateral side, and a guide part 142 guided by a part of a second pin portion 123 that extends to the other lateral side, and a slit 143 wider than a portion of the arm 120 facing the chain-drive guide shoe 130 is provided between the mating hole 141 and the guide part 142.