You determine the dynamics of a system. must meanwhile withstand even the demands of the highest dynamics. Therefore, when procuring such central components, it is essential to ensure optimal adaptation to the application, the respective medium and the respective environment. This is the only way to achieve a high level of safety, reliability and longevity for your applications and products. Off-the-shelf solutions can meet the massively increased requirements for fail-safe operation. Unfortunately, as a rule, stability cannot be met.
1. Microvalves – General
A microvalve is a particularly small component for regulating or shutting off the flow of gases or liquids (= fluids). To achieve this, a closure section (z.B. a plate, a sphere or a cone) moving almost parallel to the direction of flow of a fluid. By pressing the entire closure part against the appropriate opening, the flow is either reduced or interrupted.
2. Microvalves – The terminology (Glossary)
Before you get into the sourcing of microvalves, it's worth looking at the basic terminology in this context. Our compact glossary gives you a good overview on this subject.
Just click on the term you want to know more about.
The nominal size is given as nominal diameter (DN). DN is the diameter of the smallest cross-section, measured in [mm], through which the fluid flows in a valve.
The prere difference is the maximum prere drop across the valve at which the function is guaranteed. Valves for AC voltage have higher values than DC valves. The minimum differential prere is the smallest prere drop at which the valve still operates reliably.
The flow coefficient Kv is a specific volumetric flow related to the medium water (temperature 5 °C to 40 °C), which flows through a valve with a certain nominal size, at a prere drop of 1 bar.
The static prere is the maximum prere that can be applied to the ports of the valve during operation.
The viscosity is the flow resistance of a medium caused by the internal friction in the valve. The kinematic viscosity is expressed with the units mm²/s (Centistroke) and °E ( °Engler).
The switching frequency is specified as the maximum number of switching cycles per second. The switch-on time is the time between the closing of the current circuit. Reaching the stroke end position of the armature. The switch-off time is the time between opening the circuit and reaching the armature rest position.
3. Microvalves – valve types and operating principles
Valves exist in countless designs and variants, some of which fulfill completely different functions. In order to get an overview of the confusing product landscape, different segments have been formed to categorize and distinguish valves.
3.1 Differentiation according to task
Since microvalves are used for a wide variety of tasks in hydraulic or pneumatic systems, a distinction can be made according to the specific tasks of the valves.
3.1.1 Switching/blocking valves (on/off)
Switching valves or shut-off valves control the flow of a fluid by either blocking or opening the fluid channel. With microvalves that can withstand a high switching frequency, quasi-proportional control of the fluid can still be achieved through lightning-fast switching.
3.1.2 flow valves (proportional valves)
In flow valves or proportional valves, the flow in the fluid channel can be only partially opened or closed, depending on the applied voltage (current). Gases or liquids can be metered with extreme precision.
3.1. Microvalves can be distinguished by the number of ports per switching position. The number of switching positions can be distinguished. For example, a 2/2-way valve has two ports (A, P) and two switching positions (closed, open).
In the rest position, the shaped spring presses the seal into the lower end position. The medium can flow from P to A. After switching on the solenoid coil, the plunger is tightened. The seal is pressed against the valve seat, the valve is closed.
2/2-way micro valve
In the rest position, the compression spring presses the seal against the lower valve seat. The valve is closed, A can vent to R. After switching on the solenoid coil, the plunger is tightened. The seal is pressed against the upper valve seat. The valve is open, the medium can flow from P to A.
3/2-way micro valve
In the rest position, the shaped spring presses the seal against the lower valve seat. The medium can flow from P to A. After switching on the solenoid coil, the plunger is attracted. The seal is thereby pressed against the upper valve seat. The valve is closed, A can vent to R.
3/2-way Spider® micro valve
In the rest position, the shaped spring presses the plate armature with the seal carrier onto the valve seat P. The output A is connected to R. After switching on the magnetic coil, the plate anchor is tightened. Closes the vent R. The connection from P to A is open. The connection from P to A is open. The medium flows around the anchor. After switching off the solenoid, the shaped spring pushes the plate armature back into the rest position, the valve is closed.