Proportional Fluid Actuator With Dual Springs for Balanced Spool Response
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fluid-powered actuators with pistons attached to hydraulic valve spools exhibit different response rates when extending and retracting due to unequal effective areas in fluid chambers, leading to inconsistent movement control in applications like dump beds and hydraulic cylinders.
Innovation Solution
A fluid-powered actuator design featuring a piston with springs on both sides, where the spring rates and initial compression are calculated to maintain a neutral positioning force, ensuring proportional movement to applied fluid pressure, and utilizing a channel with an O-ring seal for precise control, allowing for wider pressure range configuration and consistent operation in both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fluid pressure is directed to either side of the piston to move the piston between positions, then the actuator can achieve bidirectional movement, but the response of piston movement to applied pressure is different in extend and retract directions due to unequal effective areas
Solution Approach 1:
The patent applies asymmetry by configuring different spring rates and preloads on each side of the piston to compensate for the unequal effective areas. The first spring has a different rate and preload than the second spring, creating an asymmetric force balance that equalizes the pressure-response characteristics in both extend and retract directions despite the geometric asymmetry of the piston-spool arrangement.
Solution Approach 2:
The patent changes the parameters of the spring system by carefully selecting different spring rates and preloads for the two sides. By adjusting these parameters, the system compensates for the unequal effective areas and achieves proportional response to applied fluid pressure in both directions, transforming the asymmetric mechanical arrangement into a symmetric performance characteristic.
2Manufacturing precision
If springs are added on both sides of the piston to achieve proportional movement, then consistent response in both directions is achieved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by placing springs at specific locations on each side of the piston, with each spring having locally optimized characteristics. The first spring is positioned and configured for the extend direction while the second spring is positioned and configured for the retract direction, with each spring's rate and preload tailored to the local requirements of that side of the piston.
Solution Approach 2:
The spring system is segmented into two independent spring assemblies, one on each side of the piston. This segmentation allows independent optimization of each spring's characteristics and simplifies the overall design by treating each side as a separate controllable unit, making the complex proportional control achievable through modular spring assemblies.
3Adaptability or versatility
If the actuator is attached to the spool of hydraulic valves, then it can control equipment position, but the effective area in the fluid chamber on the spool side is less than the effective area in the opposite chamber
Solution Approach 1:
The patent uses the spring forces as counterbalancing forces to compensate for the unequal pressure application areas. The springs provide opposing forces that counteract the imbalance created by the different effective areas on each side of the piston, allowing the actuator to maintain proportional response despite the asymmetric fluid chamber geometry imposed by the spool connection.
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 actuator achieves precise control and consistent movement in both extend and retract directions, enabling more precise control of equipment like dump beds and hydraulic cylinders, with a wider range of pressure control and simpler assembly using readily available components.
Implementation Method 1
An O-ring or other seal mechanism resides in the channel to engage an interior wall of the cylindrical chamber and to form a fluid tight seal therewith
Implementation Method 2
The force of the compression springs on the both sides of the piston will urge the piston to a center position
Implementation Method 3
The piston shaft includes multiple steps, an O-ring groove, and a snap ring groove on its surface. The piston shaft passes through a flange bushing and piston while compressing a spring in between them
Implementation Method 4
Fluid to the cylindrical chamber is delivered by one of two fluid passageways, i.e., a first fluid passageway and a second fluid passageway
Implementation Method 5
fluid pressure is directed to either side of the piston within a fluid tight cylinder to move the piston between positions
Data Source
AI summary
A proportional control fluid actuator that is used as a positioning device in applications such as a hydraulic directional control valve. The activating device has a cylinder body attachable to a valve body and has a bore carrying a piston that is coaxially secured to an end of a valve spool. The device is provided with spaced openings in the cylinder body that communicate with the bore therein to introduce fluid to act on opposite sides of the piston. Factory pre-compressed spring means are provided for normally urging the piston and spool to a center position. Since the areas of the fluid pressure applied on both sides of the piston are different (due to a spool on one side of the piston), two pre-compressed springs are used to compensate the area difference to achieve a proportional movement of the spool.