Hydraulic Tensioner with Dynamic Flow Control
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Solution Overview
Problem
Existing belt tensioners for vehicular front engine accessory drive systems face challenges in maintaining optimal belt tension with minimal complexity and low cost, as they often require high complexity and high cost to adjust between high and low tension settings effectively.
Innovation Solution
An electrically driven adjustable tensioner with a tensioner strut, control valve, and hydraulic fluid system that allows for dynamic adjustment of belt tension based on operational needs, using a control valve to regulate fluid flow and a biasing member to maintain tension without compressible fluids, ensuring reliable operation regardless of orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high belt tension is maintained in all operating modes, then belt slip is prevented, but energy loss increases and unnecessary tension is applied when not needed
Solution Approach 1:
The tensioner uses a dynamically adjustable hydraulic system with a control valve that can vary the belt tension based on operating conditions. The hydraulic fluid pressure is controlled to provide high tension when needed (preventing belt slip) and low tension when not required, resolving the contradiction between reliability and energy loss.
2Adaptability or versatility
If adjustable tension settings are implemented, then optimal tension for different operating modes is achieved, but device complexity increases
Solution Approach 1:
The patent employs a hydraulic control system using incompressible fluid to adjust belt tension. The hydraulic actuator with control valve provides smooth, precise tension adjustment without complex mechanical linkages, reducing overall device complexity while maintaining adaptability for different operating modes.
Solution Approach 2:
The invention replaces traditional mechanical tension adjustment mechanisms with a hydraulic system. This substitution eliminates complex mechanical linkages, gears, and linkages found in conventional adjustable tensioners, simplifying the overall structure while maintaining the ability to adjust tension for different operating conditions.
3Stress or pressure
If compressible fluids are used in the hydraulic system, then cushioning effect is provided, but reliable operation in varying orientations cannot be ensured
Solution Approach 1:
The patent specifies using incompressible hydraulic fluid instead of compressible fluids. This parameter change eliminates the cushioning effect but ensures consistent, reliable operation regardless of tensioner orientation. The incompressible fluid provides predictable hydraulic pressure transmission in all orientations, resolving the contradiction between cushioning and reliability.
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 enables efficient and cost-effective adjustment of belt tension, maintaining high tension when needed and reducing tension when not required, while preventing leakage and ensuring reliable operation across varying conditions.
Implementation Method 1
a piston movable in a piston chamber defined by an inner wall of the housing and having a piston rod extending from an end of the piston and a second end of the piston chamber opposite the first end. A check valve and control valve are positioned in the second fluid passageway.
Implementation Method 2
A check valve and control valve are positioned in the second fluid passageway. The check valve is positioned in the first fluid passageway and is configured to prevent fluid flow between the piston chamber and the reservoir through the first fluid passageway in a first fluid flow direction.
Implementation Method 3
The control valve is movable between a first position to permit fluid flow between the piston chamber and the reservoir through the first fluid passageway and a second position to prevent fluid flow between the piston chamber and the reservoir through the first fluid passageway.
Data Source
Figure 1
Figure 2
Figure 2A
AI summary
In an aspect, a tensioner includes a pulley, a main piston chamber, a reservoir, and first and second fluid passageways connecting the main piston chamber and reservoir, a main piston that is movable in the main piston chamber, a check valve, a control valve, and a movable reservoir member. The check valve prevents flow in one direction through the second passageway and permits flow in an opposing direction through the second passageway. The control valve is movable between to provide a first flow resistance, or a second flow resistance. The movable reservoir member is movable based on the amount of fluid in the reservoir in such a way as to change the volume of the reservoir, such that the reservoir, the main piston chamber and the first and second passageways together are included in a fluid circuit that is substantially free of any compressible fluids.