Danfoss Power Solutions Gmbh & Co Ohg

Rolf Rathke

Suenje Marsch

Stephan Kaiser

Edat Kaya

Method for the load-dependent regulation of a hydrostatic drive (), with a closed hydraulic fluid circuit comprising a first hydraulic motor () and, parallel to this, a second hydraulic motor (), whereby both hydraulic motors (and) are capable of being powered by a hydraulic pump () via a high-pressure line () and a low-pressure line () and are mechanically coupled to each other via a transmission (). The displacement of the first hydraulic motor () can be adjusted proportionally to an electrical signal of an electronic control system () by means of an electro-proportional control valve () and the displacement of the second hydraulic motor () can be adjusted by means of a pressure-proportional control valve () which is hydraulically connected to the high-pressure line () via a control pressure line (). The pressure-proportional control valve can be activated by means of a control pressure which is dependent on the high pressure. By means of automatic opening of the pressure-proportional control valve () dependent on the high pressure, proportional to the exceedance of a predefinable pressure limit in the high-pressure line (), the displacement of the second hydraulic motor () is adjusted by means of a second servo control unit which can be controlled via the pressure-proportional control valve (). By means of the electronic control system (), the actual volume flow passing through the first hydraulic motor () is determined and compared with a target value for the volume flow. Based on a deviation between the actual and target value for the volume flow, the electronic control system () calculates an adapted control signal and transmits this to the electro-proportional control valve (), as a result of which the displacement of the first hydraulic motor () is adaptable by means of a first servo control unit (), which is controlled via the electro-proportional control valve ().

Load-dependent regulation of hydraulic motors

The invention relates to a method and a device for determining of at least one end position of a displacement element of an adjustable hydraulic machine, in particular of the axial piston type, shiftable or displaceable between two ends position a by means of a displacement unit between a first end position and a second end position. According to the invention the determination of having reached an end position of displacement takes place by means of a measurement circuit, whose electrical characteristics are changed jumpily when an end position is reached. This is done by connecting a partial branch of the measuring circuit with earth, when a moveable element comes into electric contact with a limit stop assigned to the corresponding end position.

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Munich, Georgia

Rolf Rathke