Siemens Sinumerik 840D Series - Page 243

10.03
A.1 Servo solenoid valves
A-243
 Siemens AG, 2003. All rights reserved
SINUMERIK 840D/SIMODRIVE 611 digital, HLA Module (FBHLA) - 10.03 Edition
The stepless spool movement, and thus the change in throttle cross-section at
the control edges, results in a corresponding flowrate, which is represented as a
function of the spool travel s or of the electrical input signal U (manipulated vari-
able). The flow is dependent on the on the pressure drop, in addition to the
opening cross-section,
Q X
Ǹ
D
p
as defined by the law of flow.
OB
PT
P B After
O T
P O
B T
Flow rate Q
Spool travel s
Input signal U
OB
PT
Fig. A-6 Linear flow rate characteristic
ÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎ
Q
U
Window in spool sleeve
Spool stroke
Fig. A-7 Control window in spool sleeve
Flow
characteristic,
linear
A Hydraulics
10.03