Mannesmann Rexroth Ag

Mannesmann Rexroth Corporation

Winfried Rueb

Burkhard Knoell

In a check valve assembly and a valve assembly employing such a check valve assembly, a topping piston may be taken into contact with a main poppet to raise the main poppet from its seat. The main poppet is designed without significant area difference from the valve seat and the topping piston is actuated through a pilot valve, so that the process of raising the main poppet from the valve seat is controllable.

Check valve assembly

A valve assembly for actuation of a user and a method for actuation of the valve assembly, wherein a supply throttle device and a drain throttle device may be actuated independent of each other, is disclosed. In the case of single-action users, the drain throttle device is actuated such that the open cross-section of the drain throttle is maximum upon attaining the desired volumetric flow of hydraulic oil, so that the energy losses in the drain conduit are reduced to minimum.

Valve assembly and method for actuation of such a valve assembly

A valve assembly for pressure adapted and volumetric flow adapted supply of at least one user may be supplied with hydraulic fluid or connected to a tank via two work ports of a continuously adjustable directional control valve. To the two work ports of the valve assembly a common pressure compensator is associated, the piston of which is guided in axial translation in an axial bore of the directional control valve spool, so that one of the two work ports may optionally be connected to the pump port upon suitable actuation of the directional control valve. At both end surfaces of the directional control valve spool and at the spring side of the pressure compensator piston, there acts a respective control pressure which, for example, corresponds to the highest system load pressure, the individual load pressure, or a pressure derived therefrom.

Valve assembly

Directional control valve

A valve arrangement for a hydraulic transmission circuit, in particular for a change-under-load transmission with a clutch valve arrangement for controlling at least one clutch and/or start-up clutch with the aid of a pressure-regulating valve whose normal position can be influenced mechanically by a clutch pedal. The pressure-measuring area of the pressureregulating valve is connected to a control valve whose piston, acted on by the clutch pedal, can be brought, against the force of a spring placed between the pressure-regulating valve and the control valve, first of all out of a position that relieves the pressure-measuring area of load into a floating position in which the pressure-measuring area is connected to the pressure-regulating valve outlet. Then, and after traversing a certain path, it can be brought into contact with the valve body of the pressure-regulating valve. Here the valve body is slaved and is kept in a position in which the pressure-regulating valve outlet is connected by as large a cross-section as possible to the tank connection. The pressure-regulating valve includes a position and a control area which acts in opposition to a force on the pressure-measuring area. A second spring acts on the control area without utilizing a pressure tight chamber. The arrangement can be simply supplemented by a start safety valve that is connected in parallel to the pressure-regulating valve and to the safety valve and that can be brought, exclusively by mechanical action when moving the piston, acted on by the clutch pedal, out of an initial position blocking a neutral shift position valve in the neutral position into an unblocking position in which the neutral shift position valve can be unblocked.

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Neustadt, Germany

Winfried Rueb