Siemens SINUMERIK 840D Description Of Functions page 243

02.99
Valve amplifier
+U B
+15V
DC
–15 V
DC
Logic
+
PID
–
S
U
Fig. A-15 Block diagram of sizes 6 and 10 directly actuated servo solenoid valves
 Siemens AG 2000. All rights reserved
SINUMERIK 840D/SIMODRIVE 611 digital Descr. of Functions HLA Module (FBHLA) – 04.00 Edition
The functions of the integrated valve amplifier are implemented with analog
electronics and illustrated in a block diagram (see Fig. A-15).
The main amplifier functions are:
S
Supply and evaluation of the position sensor (AC/DC converter)
S
Comparison of setpoint input signal with spool actual value
S
Formation of manipulated variable via a PID controller for the output stage
S
Timing output stage with pulse length modulation
The amplifier is calibrated to match the valve at the factory. A zero-point adjust-
ment is made via the NC during start-up.
+U B
A.1 Servo solenoid valves
2.5 AF
+24 V=
A
B
C
D
100k
E
100k
F
10k
A Hydraulics
Supply
0 V
0 V Reference point
Actual value spool
value
+ – 10 V
Setpoint 0...
Sign.
Actual value spool
value
Protective earth
Screening
A-243