Dead-Band Hold And Proportional Control; Responding To Flow Requests After Tolsout; Magnetic Valves Off Control; Resolving A Steering Control Conflict - Danfoss pved-cl Operation Manual

Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by High Priority Steering Device – Open Loop
Symbol
Tolsout

Magnetic Valves OFF Control

Symbol
Magnetic valves Off delay time
© Danfoss | May 2016

Dead-band Hold and Proportional Control

Setting Tolsout between 21 and 30000 (ms) defines the maximum time where the main spool is either set
on the valve dead-band or controlled proportionally within the valve dead-band (granted that the flow
request is 0 during this time).
After a flow request to either left or right port, the main spool will be set on the respective left or right
valve dead-band. Any steering device movement within the defined steering device dead-band, db, will
result in proportional main spool movement. Proportional control will be allowed for Tolsout ms. If the
flow request has been 0 for Tolsout ms, the main spool will be set in neutral and any steering device
movements within db will be ignored.
To utilize proportional control, a steering device dead-band, db, needs to be created. If db is set a low
value, the main spool will effectively be operated as dead-band jump control.

Responding to Flow Requests after Tolsout

If the main spool has been set in neutral after Tolsout ms, any flow request will cause the spool to
immediately jump to the relevant spool position with no initial proportional dead-band control.
Index
316
Magnetic valves off delay time disables the magnetic valve bridge after a time specified in ms when the
flow request is 0, otherwise it remains enabled. This parameter is used when electrical energy
consumption by the magnetic valve bridge in the PVED must be reduced or to resolve a steering control
conflict between the OSP and the PVED-CL (implementing EHPS type 1 systems only).
The default value disables this functionality i.e. the magnetic valve bridge is enabled at all times. The
magnetic valve bridge is enabled when the PVED-CL receives a non-zero flow request.
Index
315

Resolving a Steering Control Conflict

On systems utilizing a PVED-CL, an EHPS valve, an OSP, a CAN or analogue steering device but no
steering wheel angle sensor (SASA) (EHPS type 1), the PVED-CL has no means to detect that the steering
wheel is being activated. A steering conflict between OSP steering and steering device steering is thus
possible.
To resolve this conflict, set Tolsout to a value (typically 50 ms – 200 ms) to disable the magnetic valve
bridge when no flow request is being commanded with the steering device.
Default
10 000
Default
30 000
11025583 | AQ00000216en-US0302 | 71
Value range
1 to 30 000 (ms)
Value range
1 to 30 000 (ms)