In this paper an innovative design solution of a vane pump integrated in to an electric motor will be presented. An integrated motor-pump assembly together with a supply converter and control system will be developed, as well as electromechanical and hydraulic processes in the motor pump group analyzed. Simulation models of motor pump group will be designed in order to investigate its functionality, electromechanical and hydraulic parameters, total efficiency, vibrations, noise and system dynamics. The studies described in this paper relate to the double vane pumps, but these results will also be representative for hydraulic drives with other positive displacement pumps. Developing a new generation of fluid power pumps with integrated electric drive is an innovative solution and characterized by a wide range of possible applications. The proposed solution can be widely used in automation and robotics, aviation, automotive and other applications.

The proposed solution is based on the concept of mechatronic pump drive. In the suggested solution the positive displacement pump is built into the rotor of an electric permanent magnet motor. The inner parts of the pump are stationary, while the housing is spinning. Due to the lack of centrifugal force, the vanes are additionally pressed to the external cam ring using springs. The ability to control the pump flow directly through the speed control of the electric motor simplifies the fluid power control system, reducing the cost of implementation, and increasing the reliability. Results in this paper are presented for the double vane pump but are also applicable for other displacement pumps.

This new solution allows for a substantial (40%) reduction in volume of motor-pump groups compared to conventional solutions and has a significantly lower noise emission. Motors with permanent magnets are used in high performance drives with a wide range of rotational speed control. They have the highest energy efficiency of all electric motors, are characterized by the highest values of the nominal and maximum torque, have a big duty moment and allow high dynamics and precision adjustment of the drive, ie.: quick response to change of the drive load and the settings.

In the paper physical models for the evaluation of the functionality, the controllability, reliability and dynamic behavior of the motor pump group in the hydraulic systems will be presented. The proposed concept of the mechatronic positive displacement pump design solution meets many high requirements concerning hydraulic drives in industrial applications during recent years.

Der Optimierung des Gesamtwirkungsgrades von hydrostatischen Kolbenverdrängern sind physikalische Grenzen gesetzt, die bei einigen Bauarten durch empirische Entwicklung weitgehend erreicht sind.
Der Inhalt dieses Beitrages bezieht sich daher nicht nur auf die Optimierung des Wirkungsgrades im Allgemeinen, sondern speziell auf die Adaptierung bzw. Verschiebung der Bereiche hoher Effizienz in einen spezifischen Arbeitsbereich, der durch die Anwendung bzw. Nutzung der Verdrängermaschine vorgegeben ist.
Voraussetzung für die systematische Beeinflussung des Wirkungsgrades ist neben der Kenntnis der typischen Arbeitspunkte der eingesetzten Einheit insbesondere die möglichst genaue Betrachtung der Verlustmechanismen, um diese mit zutreffenden physikalischen Gesetzmäßigkeiten zu beschreiben und in der Folge auch zielgerichtet beeinflussen zu können.
Als hauptursächliche Verluststellen lassen sich typischerweise Reibung und Leckage zwischen Steuerplatte und Kolbentrommel, Kolben und Buchse sowie Kolbenschuh und Widerlager ausmachen. Durch die gezielte Verlagerung von volumetrischen und hydromechanischen Verlustmechanismen lässt sich der Bereich des theoretisch erzielbaren Gesamtwirkungsgrades deutlich verlagern und führt somit zu einem effizienteren Einsatz der Einheit im gewählten Arbeitsbereich.
Als Versuchsträger, der eine direkte Beeinflussung der besagten Verluststellen ermöglicht, wird die RAC-Einheit (Radialkolbenmaschine mit konischen Steuerplatten) eingesetzt, die gleichwertig als Pumpe und Motor verwendet werden kann.
Die Verlustleistungen an den funktionellen Komponenten werden zunächst analytisch ermittelt und beschrieben, wobei gezielt freie Parameter für die Einflussnahme ausgewählt werden. Anschließend werden diese Parameter miteinander kombiniert, um den Bereich hoher Gesamtwirkungsgrade zu ermitteln und mit dem gewählten Betriebspunkt oder Betriebsbereich abzustimmen.
In einem Wirkungsgradprüfstand werden die nach den Parametervorgaben modifizierten Komponenten in einem gemeinsamen Versuchsträger auf die Wirksamkeit der Betriebspunkt-Adaptierung untersucht. Dies soll für mehrere typische Anwendungsbereiche aus der Mobil- bzw. Stationärhydraulik durchgeführt und verglichen werden.
Ziel ist die Entwicklung eines analytischen Werkzeugs, das dem Konstrukteur schon während der Auslegung ermöglicht, den Bereich der besten Gesamtwirkungsrade in die Bereiche der späteren Nutzung zu verschieben, um so eine auf die Einsatzbedingungen optimal zugeschnittene Verdrängereinheit zu erhalten.

Emitted noise is one of the biggest drawbacks by using fluid power systems. By using variable pump/motor units the fluid power architecture is more flexible and the efficiency is drastically improved. However, the noise level at fragment displacement angles is not proportional to the power output. The noise level is rather increased with decreased setting angle.
This study investigates the oscillations of swash plate due to piston forces acting on the swash plate in in-line pumps. Most of the earlier investigations done in variable axial piston pumps assume fixed swash plate angle, i.e. the swash plate are fixed at different displacement angles. In normal operation conditions the swash plate is controlled by hydraulic actuators which affect the swash plate. The flow pulsation and force and movement oscillations are affected by the additional dynamics from the swash plate control. The states which are considered in this study include flow pulsations, force and moment pulsations as well as energy losses.
A model to understand the pump/motor behavior at variable displacement angles is presented. Model includes the important forces created due to pressure build up in the pump and acting on the swash plate. The pump/motor control cylinder is modeled to enable investigations of the oscillations on the swash-plate caused by the piston forces on the swash-plate. The model is able to separate all different losses caused by the pump pulsations and the controller. The results show behavior which will affect both efficiency and noise.

In the wide range products such as wind turbine generator, engine generator, railway vehicle, ship and so on, the demands for large capacity hydrostatic transmission with high efficiency are increasing as a substitute of conventional transmission such as gearbox in the drive train systems for improvement and differentiation of such products.
For satisfying such demands, large capacity hydrostatic transmission with variable displacement was developed, which is comprised of original hydraulic pump and motors with applying the Digital Displacement ® technology by Artemis Intelligent Power, Ltd.
The hydrostatic transmission to introduce here is comprised of multistage radial piston hydraulic pump and motors. Hydraulic pump is comprised of rotating multi-lobe ring cams and pistons located around ring cam radially, and hydraulic motor is comprised of pistons located radially and crankshaft driven by these pistons. In particular, it is able to change the displacement of pump and motors by controlling each valve individually, where valves are installed in all cylinders. The authors succeeded in the development of large capacity hydrostatic transmission with variable displacement over 7MW by applying these systems.
As a result, the authors confirmed that it is possible to manufacture and provide the compact and light-weighted hydrostatic transmission with high efficiency and large capacity compared with conventional type transmission such as gearbox and there is a possibility to it seems to be able to improve and differentiate various products above mentored by applying these technologies.