High-Speed Valve Actuator with Dual Solenoid and LVDT Feedback
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Solution Overview
Problem
Existing bulk material dispensers struggle to rapidly and precisely control the position of discharge valves for powders, leading to clumping issues as materials pass through the valve and conduit.
Innovation Solution
A high-speed actuator with a hollow rod and solenoid armatures, coupled with a linear variable differential transformer (LVDT) for precise position feedback, and a control system using PID compensation and pulse modulation to control solenoid coils, ensuring accurate valve positioning and breakup of clumped material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional discharge valve is used in bulk material dispensers, then the structure is simple, but the valve cannot be rapidly and precisely controlled between fully open and fully closed positions
Solution Approach 1:
The actuator is divided into two independent solenoid systems (first solenoid for opening, second solenoid for closing) that operate in opposition. Each solenoid has its own coil, armature, and biasing mechanism, allowing independent control of opening and closing actions. This segmentation enables precise position control by selectively activating either solenoid based on the desired valve position adjustment.
Solution Approach 2:
A non-magnetic rod serves as an intermediary element that transmits the opening force from the first solenoid armature to the valve stopper, while the second solenoid armature directly acts on the valve stopper for closing. The rod allows magnetic field isolation between the two solenoid systems while transmitting mechanical force, enabling precise control without direct mechanical coupling between opposing forces.
2Speed
If a potentiometer with wiper is used for position feedback, then the structure is simple, but mechanical friction is relatively high which limits it to low-speed applications
Solution Approach 1:
The mechanical contact-based potentiometer system is replaced with an LVDT (Linear Variable Differential Transformer) system that uses electromagnetic induction for position sensing. The LVDT measures rod displacement through changes in magnetic coupling between the armature and measuring coils, eliminating mechanical friction and wear while enabling high-speed, high-repetition operation with superior position-measuring repeatability.
3Productivity
If powder material flows through the discharge valve and conduit, then dispensing occurs, but the powder tends to clump together
Solution Approach 1:
The actuator employs periodic rapid oscillation of the valve stopper between slightly open and closed positions during the dispensing process. This periodic motion creates pulsating flow that prevents powder particles from settling and clumping in the discharge conduit, while the valve remains in the open position for material flow. The oscillation frequency and amplitude are controlled to optimize powder flow without affecting overall dispensing productivity.
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
Enables precise control of discharge valve openness and effective breakup of clumped powder, enhancing the accuracy and efficiency of bulk material dispensing by minimizing mechanical friction and ensuring high-speed, high-repetition operation.
Implementation Method 1
A first solenoid coil surrounds and is spaced from the rod to bias the first solenoid armature along with the rod and valve stopper toward the valve's open position
Implementation Method 2
A second solenoid surrounds and is spaced from the rod. The second solenoid is axially spaced from the first solenoid to bias the first armature towards the valve's closed position, and thereby urging the rod and valve stopper towards the valve's closed position
Implementation Method 3
A linear variable differential transformer (LVDT) magnetically coupled to the second solenoid armature is included to determine the instantaneous position of the valve stopper relative to the valve's seat
Data Source
AI summary
A high-speed actuator moves a valve stopper to a selected position to control material flow. The actuator includes a rod carrying first and second axially spaced solenoid armatures attached to the stopper. First and second solenoid coil surround and are spaced from the rod to bias the first solenoid armature along with the rod and valve stopper. A linear variable differential transformer (LVDT) responsive to the position of the second armature determines the instantaneous position of the valve stopper. A valve position control circuit receives a valve position set point from a user's input, and a valve position feedback signal from the LVDT. The valve position control circuit includes first and second solenoid coil drive signals that urge the first armature and stopper to the valve position set point. A signal generator circuit vibrates the valve about a set point to enhance material discharge.