Normally-Closed Valve Microflow Rate Adjusting Device
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Solution Overview
Problem
Conventional normally-closed valves face difficulties in making fine adjustments to flow rates due to the limitations of adjusting the axial position of a stopper screw-engaged with the cylinder, which is determined by the pitch and angle of rotation, making precise control of flow rates challenging.
Innovation Solution
A microflow rate adjusting device is introduced, featuring a stopper mechanism with a stroke adjustment member screw-engaged coaxially with the cylinder, an annular tapered surface, movable and stationary valve opening control surfaces, and balls that allow for precise adjustment of the piston body's movement, enabling a ratio of axial movement that can be set from 1:1/2 to 1:1/50, thereby allowing for minute valve openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional stopper mechanism with a screw-engaged cylinder is used to adjust flow rate, then the valve opening can be adjusted, but the adjustment precision is limited by the screw pitch and rotation angle, making fine flow rate control difficult
Solution Approach 1:
The invention employs tapered surfaces (conical geometry) instead of parallel surfaces. The first tapered surface on the stroke adjustment member and the second tapered surface on the piston body create a wedge-like effect where small axial movements are amplified into larger radial displacements of the balls, enabling fine flow rate adjustments through coarse screw rotations
Solution Approach 2:
The invention converts one-dimensional screw rotation into two-dimensional control by incorporating tapered surfaces that transform axial movement into radial ball displacement. This dimensional transformation allows the screw mechanism to achieve both coarse positioning and fine adjustment capabilities simultaneously
2Quantity of substance
If the axial position of a stopper is adjusted to control flow rate, then the valve opening can be changed, but the minimum valve opening is limited and fine flow rates cannot be achieved
Solution Approach 1:
The balls serve as intermediary elements between the tapered surfaces and the piston body. These balls transmit and amplify the mechanical action from the stroke adjustment member to the piston, enabling precise control of the valve opening through intermediate mechanical leverage
Solution Approach 2:
The invention changes the geometric parameters of the control surfaces from parallel to tapered. This parameter change in surface geometry transforms the mechanical advantage ratio, allowing the same screw rotation to produce variable valve openings from fully closed to fully open positions, achieving both fine and coarse control
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 solution allows for precise control of flow rates, enabling adjustments from low flow rates (e.g., several c.c. per minute) to high flow rates (e.g., several liters per minute), providing a finely adjustable normally-closed valve capable of handling various fluid flow requirements.
Implementation Method 1
at least one of the movable valve opening control surface and the stationary valve opening control surface comprises a tapered surface which is tapered to reduce a distance between the movable valve opening control surface and the stationary valve opening control surface in a direction toward an outer edge of the tapered surface
Data Source
AI summary
A normally-closed valve having a microflow rate adjusting device includes a valve stem for opening and closing a fluid passage; a biasing device for biasing the valve stem in a direction to close the fluid passage; a piston body which is engaged in a cylinder in an air-tight manner to form a pressure chamber for moving the valve stem in a valve opening direction against the biasing device; and a stopper mechanism, provided on the cylinder, for controlling a limit of movement of the piston body in the valve opening direction. The stopper mechanism comprises a stroke adjustment member which is screw-engaged with the cylinder coaxially with the valve stem so that a position of the stroke adjustment member relative to the cylinder can be adjusted, and includes an annular tapered surface at an end of the stroke adjustment member which faces the piston body.