Ring-Type Tensioner D-Shaped Elastic Ring Wear Reduction
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Solution Overview
Problem
Ring-type tensioners with circular cross-sections experience excessive wear due to line contact, leading to instability in chain tension control, bit-locking, and generation of flapping noises, and are difficult to assemble due to manual expansion requirements.
Innovation Solution
A ring-type tensioner with a plunger and elastic ring featuring straight radial profiles for reduced contact pressure, inclined surfaces to control plunger movement, and a ring-diameter retaining tool for easier expansion and assembly, preventing bit-locking and excessive tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a circular cross-section elastic ring is used in the prior art tensioner, then the ring can be easily manufactured and installed, but it causes line contact with the groove wall resulting in excessive wear and bit-locking
Solution Approach 1:
The elastic ring is designed with a D-shaped cross-section instead of a circular cross-section. The straight radial surface of the D-shaped ring contacts the groove wall in a face-to-face manner, converting line contact to surface contact and significantly reducing contact pressure and wear, thereby preventing bit-locking while maintaining manufacturing feasibility
2Ease of manufacture
If manual expansion of the elastic ring is required for assembly, then the ring can be installed, but the assembly process becomes difficult and time-consuming
Solution Approach 1:
A ring-diameter retaining tool is introduced as an intermediary device during assembly. The tool includes a retaining member that engages with the elastic ring to control its diameter, allowing the ring to be expanded and installed onto the plunger without requiring manual finger manipulation, thereby facilitating smooth and efficient assembly
3Ease of operation
If the plunger is allowed to move freely during transport, then installation is easier, but the plunger may jump out of the housing causing safety issues
Solution Approach 1:
The ring-diameter retaining tool serves a dual function: it facilitates ring installation during assembly and acts as a safety device during transport. The retaining member engages with the elastic ring to control plunger movement, preventing the plunger from jumping out of the housing during transportation and storage while not interfering with normal installation operations
4Reliability
If air enters the oil chamber while the engine is stopped, then the hydraulic pressure cannot prevent plunger retraction, but this condition is difficult to prevent
Solution Approach 1:
The elastic ring with straight radial surface and the groove configuration create a preliminary mechanical constraint that works in conjunction with the hydraulic system. The face-to-face contact geometry provides more stable mechanical support that complements the hydraulic pressure, helping to prevent plunger retraction and reduce flapping noises when air enters the oil chamber
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 reduces wear, prevents bit-locking and flapping noises, enhances tension control responsiveness, and facilitates easier assembly and maintenance by using straight radial profiles and inclined surfaces, while the ring-diameter retaining tool secures the plunger during transport and installation.
Implementation Method 1
A spring biases the plunger in its protruding direction
Implementation Method 2
an elastic ring, capable of radial expansion and contraction, is disposed around the plunger
Implementation Method 3
the pressure of oil supplied to an oil chamber formed by the housing and the plunger
Data Source
AI summary
In a ring-type tensioner, an expansible elastic ring disposed in a groove formed in the wall of a plunger-accommodating hole cooperates with teeth formed on the plunger to restrict axial movement of the plunger. The ring and the groove in the wall of the plunger-accommodating hole have flat radial surfaces for mutual engagement. However the ring also has oblique plunger-tooth engaging surfaces. The ring has manipulable end parts that can be locked in fixed relation to each other by a tool to secure the plunger against axial movement. The tool can also be inserted into a gap between the manipulable end parts to expand the ring and thereby release the plunger.