Schnellschaltende elektromagnetische Ventile spielen in vielen Anwendungen der Pneumatik, Hydraulik und des Automobilbaus eine immer wichtigere Rolle. Weitere Impulse der Entwicklung von modernen Ventilsystemen werden durch die Effizienzforderungen der Politik gegeben. Diese zwei bisher gegensätzlichen Optimierungsziele können durch polarisierte Elektromagnete nach dem Resonanzprinzip erreicht werden.
Im Gegensatz zu herkömmlichen Ventilmagneten wird bei dem als Doppelhubmagnet ausgeführten Prinzip eine Feder eingesetzt, welche in einem großen Hubbereich stärker ist als die Magnetkraft. Nur in den Endlagen übersteigt die typisch hyperbolisch geformte Magnetkraftkennlinie die Federkraft. Dadurch wird die Schaltzeit vorwiegend durch das Feder-Masse-System bestimmt und kann auf sehr kleine Werte dimensioniert werden. Das Magnetsystem kann große Hübe schalten, besitzt Soft-Touch-Eigenschaften und kann durch den Einsatz von Permanentmagneten als polarisierter Reihenkreis leistungslos halten. Die Positionserkennung, die Haltezeiten sowie die Initialisierungsbewegung kann durch intelligente Mikroprozessoransteuerung realisiert werden.
Durch ein neuartiges integriertes Anker-Feder-System ist ein Demonstrator für miniaturisiertes 3/2-Pneumatikventil entstanden, dass mit geringen Leistungen versorgt wird. Experimente haben für einen auf 25 Hz ausgelegtes System einen Maximaldruck von 7 bar bei 7 V Versorgungsspannung und 2,5 bar bei 5V-USB-Spannung ergeben. Die Stromaufnahme betrug dabei 500mA Peak und weniger als 100mA kontinierlich.
Der Beitrag erläutert den Entwurfsprozess des Magnetkreises, die konstruktive Gestaltung des integrierten Anker-Feder-Systems sowie des Dichtsitzes und zeigt die Möglichkeiten einer intelligenten Ansteuerung auf.

In the previous report, a novel linear motor for fluid power valve technology was successfully developed. It was proved that the linear effective stroke is around 1 mm and the maximal output force is 15 N for the maximal excitation current of 1 A. However, one minor fault of such a linear motor was its short and limited stroke. Based on this so-called short-stroke linear motor, a quasi 2-D linear motor with larger stroke ( 10 mm) is proposed in the paper. The basic idea to enlarge the available stroke is to design a larger linear motor, in which the hollow stator with embedded coil and permanent magnet covers and incorporates the existing short-stroke linear motor. Thus, the so-called quasi 2-D linear motor with two coaxial displacement outputs is developed. It is observed that both the stator and armature of the short-stroke linear motor are independently movable and form the two-dimensional motion. Further experiments also show that such a quasi 2-D linear motor can produce diverse modes of motion output even though the motions of the two armatures in the quasi 2-D linear motor are translational rather than rotational. In the following, some design features of the quasi 2-D linear motor are described. The stator of the short-stroke linear motor serves as the armature of the larger linear motor. It is worth mentioning that the output force/stroke characteristic of the larger linear motor is actually nonlinear. However, such a non-linearity is not of great importance since the final precision linear force output control and the precision plunger position control are both accomplished by the armature of short-stroke linear motor. The larger linear motor drives the stator of the short-stroke linear motor and moves the output plunger against a spring to a definite large stroke according to Hook’s law. After that, the armature of short-stroke linear motor takes over the remaining precision position control of the plunger. In order to have consistent control environment for these two coaxial linear motors, the maximal output force of the larger linear motor is designed to be around 15 N for the excitation current of 1 A, which is almost identical to that of the short-stroke linear motor. In this paper, the electro-magnetic software FLUX2D is used as a tool to accomplish this design task. Finally, to investigate the precision of the plunger position control, both open loop and closed-loop control schemes are utilized. It is observed that the performance of the latter is better that of the former. Therefore, it is expected that such a new quasi 2-D linear motor may find some potential application fields in fluid power valve technology in the future.

Oil contamination is the major source of failure of hydraulic system. Sticking for oil contamination is one of the common failure mode of hydraulic spool valve and it leads to lagging and failure. Oil contamination has a serious influence on the reliability of hydraulic valve. This article presents research on solid particles motion and distribution in hydraulic spool valve gap by using Eulerian-Eulerian Model of software FLUENT aiming at hydraulic spool sticking induced by solid particles. Compared with the spool valve gap without ring groove, the solid particles gather densely and distribute in semilunar shape near the housing wall in the spool valve gap with ring groove. When the direction of the spool motion reverses to the pressure gradient, the gap near ring groove outlet is about to approach to the semilunar zone. Partial particles will implant into the gap followed the ring groove under pressure difference leading to spool sticking. The authors put forward the simplified mechanical model of spool clamping induced by solid particles and divide solid particles into free particles and implanted particles. Implanted particles are defined as particles contacted with the surfaces of valve housing and spool simultaneously. The implanted particles may lead to spool sticking while free particles have no effect on the spool motion. The research has an important guiding significance on investigation the mechanism of the influence of polluted oil on the hydraulic valve performance and the innovation of high reliability hydraulic valve.

A new actuator based on voice coil motor (VCM) has been proposed in this paper. The actuator, which
uses Lorentz principle to generate force, is a new-style direct drive motor with special geometry of the magnetic
circuit. A particular arrangement of three coils, leads to the improvement of transient behaviour by decreasing
the electrical time constant. The use of magnetic fluids within the electromagnetic circuit yields an increase in
the force factor, improves the damping and thermal behaviour and the linearity. Easy to be controlled, with high
acceleration, high speed, high force and fast actuation makes it an alternative replacement for expensive and
sensitive actuators. Numerical simulations were performed with dedicated software, in order to complete
experimental research, and to predict some further developments.