Siemens SINUMERIK 840D Description Of Functions page 237

02.99
Flow
characteristic,
linear
 Siemens AG 2000. All rights reserved
SINUMERIK 840D/SIMODRIVE 611 digital Descr. of Functions HLA Module (FBHLA) – 04.00 Edition
The stepless slide movement, and thus the change in the throttle cross-section
at the control edges, results in a corresponding flow which is represented as a
function of spool travel s or of electrical input signal U (manipulated variable).
The linearity is determined by the geometry of the control edges of the spool
sleeve.
The flow is not only dependent on the opening cross-section, but also on the
pressure drop in accordance with the law of flow:
Q Y
auch vom Druckabfall abhängig.
Flow Q
P
B
A B
P T
P B to
A T
Fig. A-6 Flow characteristic
Window in spool sleeve
Î Î Î Î Î Î Î
Î Î Î Î Î Î Î
Î Î Î Î Î Î Î
Î Î Î Î Î Î Î
Î Î Î Î Î Î Î
Spool stroke
Fig. A-7 Control edge on spool sleeve
A.1 Servo solenoid valves
p
np
A to
T
A B
P T
Spool travel s
Input signal I
Q
A Hydraulics
n
p per control
NOM
edge = 35 bar
n n
p p
PA BT
U
E
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