Chain Guide Bushing Structure for Stable Timing Assembly
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Solution Overview
Problem
The existing chain guides in engine timing systems face issues with thermal shrinkage differences between metal mounting bolts and resin guide bodies, leading to looseness and instability, which complicates assembly and transportation due to the need for metal bushing members.
Innovation Solution
A chain guide design featuring a guide body with a shoe support and a bushing structure that includes a cylindrical insertion hole and a flange part with a front-side restricting portion to prevent accidental drops and enhance assembly efficiency, featuring a flexible extended part and a rotation restricting mechanism to secure the bushing member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal bushing member is interposed inside the bolt passage hole to alleviate looseness from thermal shrinkage difference, then the mounting stability is improved, but the assembly complexity and risk of accidental drop during transportation increase
Solution Approach 1:
The bushing member is nested within the guide body's bolt passage hole, with the flange part positioned inside the guide body and the cylindrical part extending through. This nesting arrangement secures the bushing member in place during transportation while maintaining its function of preventing looseness between the metal bolt and resin guide body.
Solution Approach 2:
The bushing member is segmented into two distinct parts: a flange part that remains inside the guide body to prevent accidental drop, and a cylindrical part that extends through to accommodate the mounting bolt. This segmentation allows each part to fulfill its specific function independently.
2Reliability
If a metal bushing member is interposed inside the bolt passage hole to alleviate looseness from thermal shrinkage difference, then the mounting stability is improved, but the work efficiency during assembly decreases
Solution Approach 1:
The bushing member is pre-installed and secured within the guide body's bolt passage hole before the actual mounting process. The flange part is positioned inside the guide body in advance, creating a ready-to-use structure that simplifies the subsequent assembly steps and improves work efficiency.
3Reliability
If the bushing member is secured with multiple restricting portions, then the transportability is improved, but the ease of manufacture decreases
Solution Approach 1:
Instead of providing restricting portions all around the bushing member, the invention applies the restricting function locally at specific locations. The front-side restricting portion is provided only in one location on the outer circumference of the cylindrical insertion hole, and the backside restricting part is positioned at the back end, providing adequate security during transportation while simplifying the manufacturing process.
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 design improves transportability and assembly efficiency by preventing accidental drops and ensuring secure attachment of the bushing member, maintaining stability and reducing assembly complexity.
Implementation Method 1
the difference in thermal shrinkage occurs between the synthetic resin guide body and the metal mounting bolt due to the heat of the running engine
Implementation Method 2
a backside restricting part that restricts movement of the flange part toward the back side in the guide width direction
Implementation Method 3
a front-side restricting portion that is positioned on the front side in the guide width direction of the flange part and restricts movement of the flange part to the front side in the guide width direction
Data Source
AI summary
A chain guide is provided that can improve the work efficiency during assembly and transportability with a simple structure. The chain guide includes a bushing structure where a bushing member is attached to a guide body at least in one location. The guide body includes a cylindrical insertion hole through which a bushing cylindrical part is inserted, and a backside restricting part that restricts movement of a flange part to the back side in the guide width direction. The guide body is provided, in each bushing structure, with a front-side restricting portion that restricts movement of the flange part to the front side in the guide width direction only in one location on the outer circumference of the cylindrical insertion hole when viewed in the guide width direction.