Moog ACV with CANopen bus interface
7 Servo valve functions
Flow / pressure (P) switchover
B99224-DV018-D-211, Rev. A, October 2018
229
7.13.2 Continuous signal switching
The switch-over criteria between the control modes are the PressureDemandValue
(<PrsDemandValue> (0x6390)), the PressureActualValue (<PrsActualValue> (0x6381)), the output of the
PressureControllerOutput (<ControllerOutput> (0x2418)) and the output of the FlowControllerOutput
(<ControllerOutput> (0x520F)). Both controllers are calculated then the switch over function will decide which
controller output is used as input for the pilot spool position controller.
Criterion to switch from flow control to pressure control:
• Positive PressureDemandValue: PressureActualValue > PressureDemandValue
Or
• Negative PressureDemandValue: PressureActualValue < PressureDemandValue
Only if the criterion for the switch over to pressure control is not fulfilled, the criterion for the switch over to flow
control is checked:
• Positive PressureDemandValue: PressureControllerOutput > FlowControllerOutput
Or
• Or negative PressureDemandValue: PressureControllerOutput < FlowControllerOutput
Or
• Or sign of the FlowControllerOutput has changed.
Figure 140: Continuous signal switching
7.13.2.1 Object 0x5204: Switching time constant
Time constants for the PT1 filter elements to get a continuous input signal to the pilot position controller if the
control mode is switching from PressureControllerOutput (<ControllerOutput> (0x2418)) to
FlowControllerOutput (<ControllerOutput> (0x520F)) and back.
Pressure
control
Flow
control
(( PressureDemandValue > 0.0 ) and ( PressureControllerOutput > FlowControllerOutput ))
or
(( PressureDemandValue <= 0.0 ) and ( PressureControllerOutput < FlowControllerOutput ))
or
Change sign of FlowControllerOutput
(( PressureDemandValue) > 0.0) and (PressureActualValue > PressureDemandValue ))
or
(( PressureDemandValue < 0.0) and (PressureActualValue < PressureDemandValue ))
ValveFlowControl
Index
Sub-index
Parameter name
Data type
Access
Per-
sis-
tence
Value range
Default
0x5204
1
SwitchingTimeConstantFlow2Pressure
FLOAT32
rw
Y
0.0…+inf
30.0
0x5204
2
SwitchingTimeConstantPressure2Flow
FLOAT32
rw
Y
0.0…+inf
3.0
