Siemens SINUMERIK 840D Description Of Functions page 240

A Hydraulics
A.1 Servo solenoid valves
Filtration grade
A-240
SINUMERIK 840D/SIMODRIVE 611 digital Descr. of Functions HLA Module (FBHLA) – 04.00 Edition
More exact information about the dynamic response is provided by the Bode
diagram or frequency response. In this case, a sinusoidal setpoint is applied to
the valve. The frequency up to which the actual value (valve spool) can follow
the setpoint is then noted. The amplitude and phase displacement must be
plotted logarithmically as a function of frequency.
A
[dB]
E
2
0
–2
–4
–6
–8
–10
Fig. A-12 Dynamic response of valve
In order to achieve the longest possible control edge life, thus assuring the qual-
ity of the zero overlap, a certain degree of purity of the hydraulic medium (fluid)
must be maintained.
The objective is contamination class 7...9 to NAS 1638, this can normally be
achieved with a pressure filter β
5 %
100
at –3 dB
Signal 100 U
max
Signal 5% U
max
10 20 40 60 80100 200 300
=75.
10
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02.99
j [5]
–180
–160
–140
–120
–100
at –905
–80
–60
–40
–20
–0
f [Hz]