4/20 DBEM(E) | Proportional pressure relief valve, pilot operated
Bosch Rexroth AG, RE 29361, edition: 2013-07
Valves of type DBEM are pilot operated pressure relief
valves. They are used to limit the operating pressure in
hydraulic systems. By means of these valves, the pressure
to be limited can be continuously adjusted depending on
the electric command value.
These 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). At the same time, 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
connection 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 propor-
tional 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,
apressure 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 inte-
grated. 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 pres-
sure 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 pres-
sure 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 pressureless. Via port X (18), the valve may be
unloaded or the maximum pressure may be limited.
Function, section
Type DBEM10-7X/..XYG24K4..