Dual-Piezo Metering Valve for High-Frequency Viscous Dispensing
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Solution Overview
Problem
Existing metering valves for viscous materials, such as adhesives and insulation pastes, are limited in their switching speed, which affects the frequency of dispensing dot-shaped doses and the minimum amount that can be metered.
Innovation Solution
A metering valve design utilizing two piezo-actuators to open and close the valve independently, with an activation element connected to the closing body, allowing for rapid switching by applying voltage to one actuator to open and the other to close, and using electromagnets and a pneumatic cylinder for holding and safety mechanisms to ensure reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single piezo-actuator is used for opening and closing the valve, then the device complexity is reduced, but the switching speed is limited
Solution Approach 1:
The single piezo-actuator is divided into two separate piezo-actuators: a first piezo-actuator for opening the valve and a second piezo-actuator for closing the valve. This segmentation allows each actuator to be optimized for its specific function, enabling faster and more reliable switching operations while maintaining independent control over opening and closing actions.
Solution Approach 2:
Instead of using one actuator to perform both opening and closing functions sequentially, the invention inverts the approach by using two actuators that can independently and simultaneously control opening and closing actions. This inversion of the functional assignment enables parallel operation and faster switching cycles.
2Productivity
If the piezo-actuators are rigidly coupled with the closing body, then the force transmission is improved, but the switching frequency is reduced
Solution Approach 1:
An activation element is introduced as an intermediary between the piezo-actuators and the closing body. This activation element receives force pulses from the piezo-actuators and transmits them to the closing body, enabling rapid force application without requiring rigid coupling. The activation element can be quickly energized and de-energized, allowing high switching frequencies while maintaining effective force transmission when needed.
Solution Approach 2:
The piezo-actuators operate by applying periodic voltage pulses to the activation element, creating rapid on-off cycles. This periodic action allows the system to achieve high switching frequencies by repeatedly energizing and de-energizing the activation element, which in turn rapidly actuates the closing body without requiring continuous rigid coupling.
3Speed
If the activation element is positioned close to both piezo-actuators, then the response time is reduced, but the reliability decreases
Solution Approach 1:
The activation element has different spatial relationships with the two piezo-actuators: it is positioned closer to the first piezo-actuator for rapid opening response, and at a greater distance from the second piezo-actuator for reliable closing operation. This asymmetric positioning optimizes the local quality of the interaction with each actuator, achieving both fast response and high reliability for their respective functions.
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 enables faster switching and more precise control of the metering valve, enhancing the frequency and accuracy of dispensing viscous materials, while ensuring reliable operation even in power failures.
Implementation Method 1
voltage is applied to the first piezo-actuator, so that it expands on the basis of the piezo effect and, because of its change in length, applies a pulse to the activation element
Implementation Method 2
voltage is applied to the second piezo-actuator, and it expands due to the piezo effect. Because of its length change, it applies a pulse to the activation element
Data Source
AI summary
A metering valve has a closing member and a valve seat. The closing member is movable between a closed position on the valve seat sealing a material outlet, and an open position raised above the valve seat leaving the outlet clear. An actuating element rigidly connected to the closing member is arranged between first and second piezo-actuators at a distance from the first piezo-actuator in the closed position less than the maximum length change of the first piezo-actuator, or lies loosely thereon and at a distance from the second piezo-actuator longer than the maximum length change of the first piezo-actuator. The actuating element in the open position is arranged at a distance from the second piezo-actuator less than the maximum length change of the second piezo-actuator, or lies loosely thereon and at a distance from the first piezo-actuator greater than the maximum length change of the second piezo-actuator.