Robert Boschgmbh

Klaus Sopha

Heinz Flaschar

Heinz Gand

Heinz Kleinschmidt

Rainer Hoheisel

Joachim Heiser

Roland Schempp

Manfred Hauser

Horst Hesse

Winfried Arnold

Hermann Sanzenbacher

Eckard Schuttenberg

Walter Kobald

Werner Zeuch

Konrad Braunlinger

Winfried Hommen

The electrohydraulic directional control valve system includes a preliminary directional control valve and a main control valve, the latter having a control spool which is normally brought into its neutral or blocking position by means of two springs arranged in pressure chambers at respective ends of the control spool. The preliminary control valve has a sliding spool which at one end is urged by a spring into an additional safety position in which the pressure chambers of the main control valve are interconnected and pressure relieved, and the intake of the pressure fluid is blocked. A single proportionally operating solenoid counteracts the spring at the other end of the control spool of the preliminary control valve.

Electrohydraulic directional control valve system

A hydraulic control system has a three-position valve which in its central position disconnects the high-pressure and low-pressure sides of a pressure source from outlet lines but connects these sides of the source together through a low-pressure valve. Moved to either of its end positions the valve is disconnected from between the sides of the pressure source and the output lines are connected to the high-pressure and low-pressure source sides. A pressure-limiting valve is connected between the sides of the source. In addition, the high-pressure side is connected via pressure-reducing valve and a restriction to a pair of pilot valves which are in turn connected to the low-pressure side. These pilot valves are also connected to opposite chambers of a pilot cylinder that controls the valve body. The pressure-reducing valve between the pilot valves and the high-pressure side maintains a medium-pressure level in the system when the valves move from its central position.

Hydraulic control system

The system includes a way valve of the type provided with a housing, fluid inflow and consumer ports in the housing, and at least one valve member movable in the valve housing for establishing connections between ports. A positioning arrangement receives an electrical input signal and positions the valve member in dependence thereon. A desired-value selector generates a desired-value signal indicative of the desired volumetric flow rate for the flow of fluid into the fluid inflow port and out one of the consumer ports. Transducers sense the position of the valve member and the pressures at the inflow and consumer ports and generate corresponding electrical feedback signals. A circuit arrangement connected to the desired-value selector and to the transducers compensates for the effect upon such volumetric flow rate of variations in the hydraulic loading of consumers supplied via the way valve by furnishing the aforementioned electrical input signal to the positioning arrangement as a predetermined function of both the desired-value and feedback signals.

Electrohydraulic control system

An electrohydraulic control unit which regulates the flow of hydraulic fluid to and from one or more consumers by way of a directional control valve has a cylinder for a piston which is mechanically connected with or constitutes the spool of the directional control valve and divides the interior of the cylinder into two plenum chambers connected to the outlet of the pump, either directly or by way of a pressure reducing valve. The chambers are further connected with the tank and each of the fluid supplying and evacuating conduits for each of the two chambers contains a flow restrictor. Th flow restrictors in conduits for admission of fluid to the chambers are mounted upstream of check valves and the flow restrictors in conduits for evacuation of fluid from the chambers are mounted upstream of or constitute integral parts of two solenoid-operated auxiliary valves. The four flow restrictors together constitute a hydraulic bridge circuit.

Electrohydraulic control unit

Growing community of inventors

Stuttgart, Germany

Klaus Sopha