Pneumatic-Hydraulic Valve Stem Geometry for Low Opening Force
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Solution Overview
Problem
Conventional pneumatic-hydraulic control valves face issues with insufficient sealing due to fluid closing forces being insufficient or excessive, affecting the balance between valve opening and closing forces, which limits the use of mechanisms with less opening force.
Innovation Solution
A pneumatic-hydraulic control valve design featuring a valve base and stem with differently sized stressed portions to create a slight imbalance in fluid forces, ensuring a greater fluid closing force than opening force, allowing for reduced opening force requirements without compromising sealing, utilizing a two-piece structural design and sealing units for enhanced assembly and sealing efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fluid closing force is increased to improve sealing effect, then the sealing effect is improved, but the valve opening force becomes excessively large
Solution Approach 1:
The patent changes the geometric parameters of the stressed portions on the valve stem. The first stressed portion (exposed to closing pressure) has a larger outer diameter than the second stressed portion (exposed to opening pressure). This parameter change creates the desired force imbalance where closing force exceeds opening force by a controlled amount, improving sealing while keeping opening force manageable.
Solution Approach 2:
The patent introduces asymmetry in the valve stem design by creating two stressed portions with different outer diameters. The first stressed portion has a larger diameter than the second stressed portion, breaking the symmetry that would otherwise result in equal opening and closing forces. This asymmetric design allows the closing force to be greater than the opening force, ensuring proper sealing while maintaining reasonable opening force requirements.
2Force
If the fluid closing force is made equal to or near zero on the isolator, then the valve opening force is reduced, but the sealing effect becomes insufficient
Solution Approach 1:
The patent modifies the geometric parameters of the valve stem stressed portions to achieve the desired force balance. By setting the outer diameter of the first stressed portion larger than that of the second stressed portion, the patent creates a controlled imbalance where the closing force exceeds the opening force, ensuring adequate sealing while maintaining reduced opening force requirements.
Solution Approach 2:
The patent applies different local qualities to different parts of the valve stem. The first stressed portion has a larger outer diameter to withstand the closing force, while the second stressed portion has a smaller outer diameter corresponding to the reduced opening force requirement. This local differentiation allows each part of the valve stem to be optimized for its specific functional requirement.
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 design ensures effective sealing while allowing for reduced valve opening force requirements, accommodating various pneumatic-hydraulic actuating devices by maintaining a slight increase in fluid closing force with rider weight, enabling the use of mechanisms with less opening force, such as motors, without compromising sealing efficacy.
Implementation Method 1
the fluid closing force is slightly greater than the fluid opening force... the fluid closing force acting on the first stressed portion is slightly greater than the fluid opening force acting on the second stressed portion
Data Source
AI summary
A pneumatic-hydraulic control valve includes a valve base and a valve stem movably disposed in the valve base. A first inner oil guiding hole of the valve stem communicates with a first outer oil guiding hole of the valve base. A second inner oil guiding hole of the valve stem does not communicate with a second outer oil guiding hole of the valve base when the valve stem is closed, and communicates with the second outer oil guiding hole of the valve base when the valve stem is opened. Further, the valve stem has a first stressed portion for bearing a fluid closing force and a second stressed portion for bearing a fluid opening force. The outer diameter of the first stressed portion is larger than that of the second stressed portion. Thus, the present invention reduces a valve opening force without affecting the sealing effect.