Variable Force Tensioner With Integrated Reservoir for Stable Chain Tension
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Solution Overview
Problem
Conventional dual hydraulic variable force tensioners with a separate reservoir face inefficiencies in fluid flow and clearance leakage, leading to inconsistent tension maintenance in engine chains or belts.
Innovation Solution
A dual hydraulic force tensioner with a reservoir integrated into the primary piston, enhancing fluid flow into the high pressure chamber and incorporating check valves and piston springs to maintain consistent tension, while reducing clearance leakage through recycling of oil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a separate reservoir design is used in conventional dual hydraulic variable force tensioners, then the structure is simpler to manufacture, but fluid flow into the high pressure chamber is slower and clearance leakage is higher
Solution Approach 1:
The reservoir is merged with the primary piston to form an integrated unit. The reservoir becomes part of the primary piston structure, eliminating the need for a separate reservoir component and its associated fluid passages. This integration directly improves fluid flow speed into the high pressure chamber while reducing the overall device complexity.
Solution Approach 2:
The reservoir is nested within the primary piston structure. The reservoir is positioned inside the primary piston bore, with the primary piston effectively containing the reservoir. This nesting arrangement allows the reservoir to be part of the primary piston while maintaining compact dimensions and improving fluid flow efficiency.
2Reliability
If a separate reservoir design is used, then manufacturing is easier, but clearance leakage increases and tension consistency deteriorates
Solution Approach 1:
By merging the reservoir with the primary piston, the patent eliminates the fluid passage interface between a separate reservoir and the primary piston. This removal of the interface directly reduces clearance leakage and improves tension consistency, while the integrated design remains manufacturable using standard machining processes.
3Productivity
If fluid flows from a separate reservoir through check valves, then the structure is simpler, but fluid flow efficiency is lower
Solution Approach 1:
The patent extracts the fluid passage complexity from the system by integrating the reservoir directly into the primary piston. This eliminates the need for complex external fluid passages and multiple check valves, allowing fluid to flow directly from the reservoir into the high pressure chamber through a simplified passage within the primary piston structure.
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 design ensures faster fluid flow and reduced clearance leakage, resulting in more consistent tensioner performance and effective maintenance of chain or belt tension across varying loads and wear conditions.
Implementation Method 1
Fluid flows from the reservoir side into both pistons from the bottom of the tensioner through a check valve to fill the high pressure chambers within the pistons
Implementation Method 2
A primary piston is forced, by a high pressure within the piston chamber, to contact a tensioner arm to maintain tension on a chain or belt of an engine
Implementation Method 3
A dual hydraulic force tensioner with a reservoir integrated into a primary piston thereof that can provide for faster fluid flow into a high pressure chamber of the piston
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A variable force tensioner (VFT) system that includes a primary piston split into two chambers disposed within a primary bore. The two chambers including a first low pressure chamber having a primary reservoir therein that feeds fluid through a check valve into a second high pressure chamber to control a biasing force on the primary piston. A piston bore clearance path can extend along a groove in the primary bore to feed oil back to the primary reservoir from the high pressure chamber.