Bosch Rexroth R900933708

Proportional flow control valves of the 2FRE ... type comprise a 2-way function. They are capable of controlling a flow indicated by the electrical command value in a pressure- and temperature-compensated manner. The set-up basically consists of a housing (1), proportional solenoid with inductive position transducer (2), metering orifice (3), pressure compensator (4) as well as check valve (5), optional. Proportional flow control valve, version “B…RV” (without external closing, with check valve) The flow setting is determined by the indication (0 to 100%) at the command value potentiometer. Via the amplifier as well as the proportional solenoid, the indicated command value has an effect on the adjustment of the metering orifice (3). The position of the metering orifice (3) is recorded by the inductive position transducer. Any existing variations from the command value are corrected by the position control. The pressure compensator (4) keeps the pressure drop at the metering orifice (3) at a constant value at all times. Thus, the flow is load-compensated. The low temperature drift is the result of the favorable design of the metering orifice. With command value 0%, the metering orifice is closed. In the event of a power failure or cable break at the inductive position transducer, the metering orifice closes. From the command value 0%, a smooth start-up is possible. Via two ramps in the electric amplifier, the metering orifice can be opened and closed with delay. Via the check valve (5), a free return flow from B to A is possible. With an additional rectifier sandwich plate of the Z4S 6... type under the proportional flow control valve, the supply and return flow from the actuator can be regulated. Type 2FRE 6 B-2X/...RV Proportional flow control valve, version “A…MV” (with external closing, without check valve) The function of this valve is basically the same as that of valve type "B...RV". For the start-up jump suppression with open metering orifice (3) (command value > 0%), a closing of the pressure compensator (4) is provided via port P (6). The internal connection between port A and the pressure compensator (4) is abandoned. Via the external port P (6), the pressure in P upstream to the directional valve (8) has an impact on the pressure compensator (4) and keeps the latter in its closed position against the spring force (7). If the directional valve (8) is switched from P to B, the pressure compensator (4) moves from the closed position into the control position and the start-up jump is thus prevented. Type 2FRE 6 A-2X/...MV