Robert Boschgmbh

Markus Grammer

Steffen Knapper

Reiner Kunz

Andreas Albrecht

Frank Rieckhof

A valve assembly includes a linearly moving main slider, a pilot valve, a control oil inlet, and a control oil return. The pilot valve is designed as a 4/3 proportional directional valve, via which a first end face and an opposite second end face of the main slider can be fluidly connected selectively to the control oil inlet or the control oil return so that the main slider () is hydraulically movable by adjusting the pilot valve. The pilot valve is electrically adjustable depending on a target current. A position sensor is provided, with which an actual position of the main slider can be measured. A positioner is provided, with which the actual position can be regulated by adjusting the target current to a predefinable target position. The pilot valve is connected to the control oil return via a check valve. The check valve only permits fluid flow from the pilot valve toward the control oil return. The check valve is preloaded to a closed position by means of a first spring so that it opens at a predetermined opening pressure. The leakages at the pilot valve from the control oil inlet toward the check valve are designed to be so large that if the pressure at the control oil inlet exceeds the opening pressure by at least 2 bar, the opening pressure of the check valve is present immediately upstream of the check valve.

Valve assembly with preloaded control oil return

A hydraulic coupling bush which is actuated in order to close or open the coupling includes a coupling housing and a bush body which displaceable therein and which has a plug space for receiving a coupling plug, a supply space for fluidic connection to an external supply channel, a low pressure space for fluidic connection to a pressure medium sink, and an interior space connected fluidically to the supply space, a supply seat valve device being provided, via the actuation of which a supply flow path can be configured between the supply space and the plug space, and a relief seat valve device being provided, via the mechanical actuation of which the interior space can be relieved of pressure toward the low pressure space, and via the hydraulic actuation of which, which is dependent on the pressure in the interior space, the pressure in the interior space can be limited.

Hydraulic coupling bush

A directional control valve arrangement includes a directional control valve with a valve spool. Using the directional control valve, it is possible to control a pressure-medium connection between a pressure port, a tank connection, and at least one working connection. A blocking valve is situated in a working passage that is connected to the working connection. The pressure in the working passage can be reduced using a pressure-release unit; the pressure-medium connection between the working passage and the tank connection is blocked by the valve spool. The pressure-relief unit has an intermediate space which is formed in the pressure-medium flow path between the blocking valve and a control edge of the valve spool that blocks the working passage to the tank port, the intermediate space being provided to accommodate a compression volume of the working passage. The intermediate space can be connected to the working passage by controlling-open the blocking valve, and the connection to the tank port is blocked by the control edge of the valve spool.

Growing community of inventors

Stuttgart, Germany

Markus Grammer