Micropneumatic Printhead Valve With Membrane Closure for Low Wear
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Solution Overview
Problem
Micropneumatic print heads face issues with wear and reduced service life due to harsh closing processes, leading to increased manufacturing costs and decreased performance, particularly in the micropneumatic control units and pilot valves used in drop-on-demand fluid jet applications.
Innovation Solution
A pneumatically actuated multi-channel coating head with a micropneumatic control unit featuring a valve element with a membrane closing element and a micro-actuator, which reduces mechanical load on the piezo bending transducer and enhances closing times by utilizing a membrane layer with recesses to support valve closure, and a series connection of pneumatic elements to manage pressure drops effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a discrete closing element with sufficient hardness and durability is used in the pilot valve, then the reliability and durability of the valve are improved, but the mass of the closing element increases, which reduces the closing speed and requires additional micro-spring elements
Solution Approach 1:
The patent replaces the traditional mechanical discrete closing element (ball or plug) with a membrane closing element that is actuated by a piezoelectric bending transducer. This substitution eliminates the need for heavy durable materials while achieving reliable closure through the flexible membrane's ability to seal against the valve seat under piezoelectric actuation.
Solution Approach 2:
The patent employs a membrane closing element instead of a rigid discrete closing element. The membrane's flexibility allows it to conform to the valve seat and achieve effective sealing with minimal mass, while the piezoelectric bending transducer provides the necessary actuation force to open and close the valve rapidly.
2Reliability
If harsh closing operations are performed to ensure reliable valve closure, then the sealing effectiveness is improved, but the wear of the valve seat and plunger increases, reducing service life
Solution Approach 1:
The patent replaces the harsh mechanical closing operation with a gentler piezoelectrically actuated membrane closure. The membrane closing element, actuated by the piezoelectric bending transducer, achieves reliable sealing without the high-impact mechanical forces that cause wear to the valve seat and plunger in traditional designs.
Solution Approach 2:
The flexible membrane closing element conforms to the valve seat geometry and achieves effective sealing through elastic deformation rather than hard impact. This flexible closure mechanism eliminates the harsh mechanical contact that leads to wear, extending the service life of the valve components while maintaining reliable sealing.
3Speed
If high pressure gradients are achieved during switching operations to improve response time, then the closing speed is improved, but the mechanical stress peaks increase, reducing the service life of piezoelectric flex transducers
Solution Approach 1:
The patent uses a piezoelectric bending transducer to actuate the membrane closing element, providing precise control over the valve opening and closing process. The piezoelectric actuation generates the necessary pressure gradients for rapid response while avoiding the high mechanical stress peaks that occur in traditional mechanical systems, thereby extending the service life of the transducer.
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 configuration reduces wear, extends the service life of the piezo bending transducer, and improves the performance and manufacturing costs of micropneumatic control units, enabling efficient and precise control of fluid delivery in coating applications.
Implementation Method 1
a microactuator with a plunger that actuates the membrane closing element through the valve bore, so that the valve element opens
Implementation Method 2
the shape of which is determined by recesses located laterally to the valve bore
Implementation Method 3
a pressurization of the series circuit, which is directed such that, with respect to the valve element, there is a pressure gradient from the membrane side to the valve bore
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
A micropneumatic control unit (3) with a plurality of control channels (2) for generating the control pressures pc in a pneumatically actuated multi-channel coating head (1) for coating components with a coating agent is presented, wherein a control channel (2) is characterized by a valve element (11) consisting of a valve bore (12) in a valve plate (10) and a membrane layer (20) which lies below the valve plate (10) and is designed in the area of the valve bore (12) as a membrane closing element (21), the shape of which is determined by recesses located laterally to the valve bore (12), by a microactuator (25) with a plunger (26) which actuates the membrane closing element (21) through the valve bore (12) so that the valve element (11) opens, by a second micropneumatic element (15) in series connection with the valve element (11),wherein the control pressure (pc) is formed at their connection node and a cavity (9) is located which is connected to at least one pneumatically operated coating agent ejector (5), and by a pneumatic pressurization of the micropneumatic control unit (3) which is directed such that, with respect to the valve element (11), there is a pressure gradient from the diaphragm closing element (21) to the valve bore (12) in the valve plate (10).