Dual Piston Tensioner with Variable Spring Force Control
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Solution Overview
Problem
Existing chain and belt tensioners in internal combustion engines face inefficiencies due to constant high spring force, which is not adaptable to varying operating conditions and wear over time, leading to suboptimal tensioning and reduced efficiency.
Innovation Solution
A tensioner system with two pistons, where one piston provides damping and the other offers variable and adjustable spring force, automatically adjusting to maintain optimal chain or belt tension across different conditions, including new and worn states, and dynamic loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single piston with constant spring force is used, then the tensioner can handle worst case operating conditions, but the spring force is too high for most operating conditions leading to reduced efficiency
Solution Approach 1:
The tensioner is divided into two separate pistons: a first piston for damping high-frequency vibrations and a second piston for providing variable spring force. This segmentation allows each piston to specialize in its function, enabling the second piston to provide lower average spring force (improving efficiency) while the first piston handles dynamic loads (maintaining reliability).
Solution Approach 2:
The second piston is designed with variable spring force capability that automatically adjusts to operating conditions and chain wear. This dynamic adjustment allows the spring force to be optimized for current conditions rather than being constantly oversized, reducing energy loss while maintaining adequate tensioning capability.
2Reliability
If high spring force is used to maintain chain tension, then chain control is ensured, but drive efficiency is reduced due to excessive tension
Solution Approach 1:
By separating the damping function (first piston) from the spring force provision (second piston), the system can maintain adequate chain control with lower average spring force. The first piston handles dynamic tension variations, allowing the second piston to operate with optimized, lower spring force that improves drive efficiency.
Solution Approach 2:
The second piston's spring force is made variable and automatically adjustable, allowing the system to optimize the spring force parameter for different operating conditions. This enables maintaining chain control while minimizing excessive tension that would reduce drive efficiency.
3Device complexity
If the tensioner spring force is kept constant, then the system is simple, but it cannot adapt to chain wear and stretching over time
Solution Approach 1:
The second piston is designed with variable spring force that automatically adjusts to account for chain wear and stretching over time. This dynamic capability allows the tensioner to maintain optimal performance throughout the chain's service life without requiring complex manual adjustment mechanisms.
Solution Approach 2:
The variable spring force mechanism in the second piston automatically adapts to changing conditions (chain wear, stretching, operating conditions) without external intervention. This self-adjusting capability provides adaptability while keeping the overall system relatively simple.
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 solution maintains low chain or belt tension while ensuring control, significantly improving drive efficiency by adapting to changing conditions and loads, thus extending the life and performance of the tensioning system.
Implementation Method 1
The first piston provides damping to the chain or belt span
Implementation Method 2
a second piston provides variable and automatically adjusting spring force to the chain or belt span
Data Source
AI summary
A tensioner for tensioning a chain or belt span which uses two pistons. The movement of the two pistons may be coupled together. The first piston provides damping to the chain span and a second piston provides variable, dominant and automatically adjusting spring force to the chain span. The tensioner automatically adjusts the mean tension force to keep the chain or belt tension as low as possible without sacrificing chain or belt control, significantly improving drive efficiency at new chain or belt conditions and conditions with dynamic loads.