Fluid Valve Position-Independent Return Force
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Solution Overview
Problem
The return force acting on the valve member in existing fluid valves increases as the spring moves further away from its equilibrium position, making it difficult for the actuator to control the valve member, especially at high degrees of movement.
Innovation Solution
A fluid valve design where the return force on the valve member is independent of its position, achieved by using a piston with two portions, one mechanically coupled to the valve member and the other in a cavity connected to a different pressure, and an actuator that modifies the pressure difference between two cavities to generate a movement force on the valve member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a spring is used to provide return force on the valve member, then the valve member can be returned to equilibrium position, but the return force increases as the valve member moves further from equilibrium, making control difficult at high degrees of movement
Solution Approach 1:
The patent replaces the mechanical spring-based return force system with a hydraulic pressure balance system. The valve member is subjected to balanced hydraulic pressures from both sides, with the return force generated by pressure differential across a piston rather than elastic spring force. This substitution eliminates the position-dependent return force characteristic of springs.
Solution Approach 2:
The patent changes the fundamental parameter governing return force from spring displacement (position-dependent) to hydraulic pressure differential (position-independent). By using a piston with equal surface areas exposed to opposite pressures, the return force remains constant regardless of valve member position, as pressure is maintained independently of displacement.
2Force
If the return force increases with valve member displacement, then the valve member can be strongly returned to equilibrium, but the actuator cannot effectively control the valve member at high degrees of movement
Solution Approach 1:
The patent replaces the mechanical spring force system with a hydraulic pressure balance system. The return force is generated by hydraulic pressure differential across a piston rather than spring elasticity, allowing the force to be independently controlled and maintained constant throughout the valve member's travel range.
Solution Approach 2:
The patent introduces a piston as an intermediary element between the valve member and the pressure sources. The piston with equal surface areas on both sides acts as a mediator that translates independent hydraulic pressures into a constant return force, decoupling the force generation from the valve member's position.
3Device complexity
If a spring is used for return force, then the structure is simple, but the control precision deteriorates due to position-dependent return force
Solution Approach 1:
The patent replaces the simple but imprecise spring-based return force mechanism with a hydraulic pressure balance system. Although the hydraulic system adds components, it provides position-independent return force that enables precise control of the valve member at any position within its travel range.
Solution Approach 2:
The patent employs hydraulic pressure balance to generate the return force on the valve member. By using fluid pressure instead of mechanical spring force, the system achieves position-independent force characteristics that enable precise positioning and control of the valve member throughout its entire stroke range.
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 allows for precise control of fluid flow between the inlet and outlets over the entire stroke range, providing stable positions for the valve member and maintaining consistent force, independent of its position, thus enhancing control and mechanical robustness.
Implementation Method 1
movement of the pilot modifies the difference in pressure between the first cavity and the second cavity. This difference in pressure generates a movement force on the valve member
Implementation Method 2
a fixed throttle in said first communication means such that movement of said movable pilot brings about a change in pressure in the first cavity
Data Source
AI summary
A fluid valve includes a valve member located between a first cavity and a second cavity, and an actuator that includes a pilot. The valve member is moved by the balance between the pressure prevailing in the first cavity and the pressure prevailing in the second cavity. The valve member includes a longitudinal hole that can be blocked by the pilot so as to modify the pressure prevailing in the first cavity and the force acting on the valve member so as to vary a fluid flow rate between an inlet and two outlets. The valve member is attached to a piston, one end of which is located in a third cavity. The force acting on the valve member is determined by the pressures prevailing in the various cavities.