Robert Boschgmbh

Brueninghaus Hydromatik Gmbh

Markus Gepraegs

Reinhold Schniederjan

Karl-Heinz Vogl

Hakan Camurdan

Grit Geissler

Thomas Froehlich

Christian Frick

Stefan Joksch

Patrick Weidele

Stephan Rohde

A hydrostatic valve arrangement for flushing pressure medium from a working line of a hydraulic circuit includes a flushing valve with a first flushing connection for connecting to a first working line and an output connection for connecting to a pressure medium sink. The arrangement also includes a pressure valve arranged in a pressure medium flow path of the arrangement from the output connection in the direction of the pressure medium sink. The pressure valve has a valve body on which a force equilibrium is formed. The force equilibrium includes a pressure equivalent that acts on the valve body in a direction that blocks the pressure medium flow path and an opening pressure that acts in a direction that opens the pressure medium flow path and is dependent on the pressure at the output connection. The arrangement further includes an adjusting device for shifting the force equilibrium.

Hydrostatic valve arrangement, hydrostatic gear having the valve arrangement, and hydrostatic drive having the gear

A hydraulic flushing valve arrangement includes a flushing valve having a housing, flushing piston, and at least one spring. The housing includes a valve bore, two circular housing control edges, two inlet channels fluidically connected to the bore, and an outlet channel opening into the bore between the inlet channels. The piston includes two control collars, a piston neck, and piston control edges that delimit the collars from the neck, and that have circular shapes with a recess. The recess has a portion that, in a cross-sectional plane perpendicular to an axis of the piston, is constant and sized such that a flushing quantity is reduced when the portion of the recess is situated in a region of a corresponding housing control edge relative to a quantity when the piston is in an end position. The collars guide the piston so as to be longitudinally displaceable in the bore, and are spaced apart by the neck. The piston and control edges are configured to control the fluidic connections between the bore, the inlet channels, and the outlet channel. The spring preloads the piston in a middle position whereat the outlet channel is blocked from the inlet channels. The piston is configured to move out of the middle position in response to a specific difference between pressures of the two inlet channels. The control collars are respectively configured to open the fluidic connection between a corresponding inlet channel in which a lower pressure prevails and the outlet channel. Such a flushing valve arrangement is usable in hydrostatic travel drives in which two hydromachines are operated in a closed hydraulic circuit.

Hydraulic flushing valve arrangement

A pressure-maintaining valve arrangement of a purge circuit of a closed hydraulic circuit includes a pressure-maintaining valve configured to be shut off via a pilot valve. In one embodiment, a control pressure chamber, acting in the closing direction, of the pressure-maintaining valve is configured to be relieved via the pilot valve to a tank, and the pressure-maintaining valve is closed via a spring acting in the closing direction. In another embodiment, the valve arrangement includes an additional control pressure chamber acting in the closing direction. The additional control pressure chamber is configured to be loaded via the pilot valve, and the pressure-maintaining valve closes. The pressure of the inlet of the pressure-maintaining valve is used for this purpose.

Pressure-maintaining valve arrangement for a purge circuit of a closed hydraulic circuit

A pressure limiting valve comprises a valve closing body () which comprises a valve closing surface () which together with a first valve seat () opposing the valve closing surface () forms a first seal seat and a valve closing body orifice (), which is surrounded by a second valve seat () which together with a closing head () configured on an axially displaceable valve bolt () forms a second seal seat and with a spring plate () which is connected to the valve bolt () and axially displaceable therewith, and a first return spring () clamped between the spring plate () and the valve closing body (), which pretensions the valve bolt () against the second valve seat () configured on the valve closing body () and a second return spring () which pretensions a valve unit () against the first valve seat (). In the valve bolt () a longitudinal bore () is provided extending over the entire axial length of the valve bolt ().

Pressure limiting valve with reduced differential area

The invention related to a hydrostatic drive comprising a hydraulic pump () which is driven by a drive machine () and pumps into at least one first working line (), and a pressure line () in which a feed quantity dependent on the speed of the drive machine () flows. When a differential pressure value in the pressure line () is exceeded, the pressure means can be extracted from the first working line ().

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Ulm, Germany

Markus Gepraegs