R901385233 Bosch Rexroth Proportional pressure relief valve

Function, section Valves of type DBEM are pilot-operated pressure relief valves. They are used to limit the operating pressure in hydraulic systems. These valves can be used for the stepless setting of the pressure to be limited dependent on the electrical command value. The valves basically consist of the housing (1) with main spool insert (3), the sandwich plate valve with maximum pressure limitation (2) and the proportional pilot control valve (11). Type DBEM... The pressure applied to channel P acts on the main spool (3). Simultaneously, the pressure at port P is applied to the spring-loaded side of the main spool (3) via the control lines (6, 7) provided with nozzles (4, 5). Via the connecting bore (9), the pressure is simultaneously applied to the poppet (10) of the proportional pilot control valve (11). The hydraulic force at the pilot poppet (10) acts against the command value-dependent force of the proportional solenoid (12). If the hydraulic force exceeds the solenoid force, the pilot poppet is opened (10). The pilot oil can now flow via the control line (13) into port Y (14) and to the tank; thus, a pressure drop results at the main spool (3) over the control lines (6, 7). The connection from port P to T is released. The main spool (3) controls the set operating pressure at port P. As hydraulic protection against inadmissibly high pressures, a spring-loaded pressure relief valve (2) has been integrated. This maximum pressure limitation is pre-set to the relevant pressure rating (see table page 6). In the operating range of the valve, the poppet (15) is held on the valve seat (17) by the spring (16) and is thus closed. If the pressure in the spring chamber of the main spool (3) exceeds the maximum admissible set pressure of the valve, the poppet (15) is pressed against the compression spring (16) and the connection into the spring chamber is opened. Via port Y (14), the pilot oil flows into the tank. Due to the control lines (6, 7), a pressure drop occurs at the main spool (3). The connection from port P to T is released. The main spool (3) controls the set maximum operating pressure in port P. Via the adjustment element (19), the pre-set pressure can be reduced, if necessary. Port Y (14) must be externally piped to the tank. The connection to the tank should be depressurized. Via port X (18), the valve may be unloaded or the maximum pressure may be limited.