7.1.2.2 Cut-Off Valve Monitoring For Ehi-H - Danfoss PVED-CLS User Manual

ENGINEERING TOMORROW
This check ensures that the cut-off valve can achieve the blocked state, when the cut-off solenoid valve is de-energized.
By moving the EH-valve main spool in the mechanical deadband, it is ensured that no oil flow is send to the steering
Important
Electro-hydraulic steering (Auto-guidance, Fast-steering and AUX-steering) will not be enabled before the PVED-CLS
has passed this test.
Warning
:
By setting P3078 Cut-off valve monitoring POST timeout to 0 (Bypass off-road safety check), the Cut-off valve
diagnostics are disabled.
Important
•
In most cases this test will be completed within 1 second, but if the oil has a very high viscosity, the time for
completing this test will increase; hence Danfoss recommends a relatively high value for P3078 to ensure the
PVED-CLS does not goes into fail safe mode in cold conditions.
•
If PVED-CLS is commanded to go to off-road mode before pump pressure is available, PVED-CLS will not be
able to perform this self-test and hence fail after the specified timeout set by P3078.
Name
Cut-off valve
monitoring POST P3078 U16
timeout

7.1.2.2 Cut-off valve monitoring for EHi-H

This safety check will be executed if P3081: Valve type is set to 2 (EHi-H) and a mode change from on-road mode to
off-road mode is requested. The cut off valve monitoring for EHi-H consists of IMD safety checks.
The PVED-CLS will set the EH-valve main spool set-point to a positive value inside the hydraulic deadband and
alternately turn the cut-off solenoid valve on and off. Each time the COV solenoid valve is toggled, the time is measured
from it is toggled until the EH-valve main spool has been observed moving. The measured time is then evaluated against
the value of P3098: Safety-checks IMD – Rise time limits and P3099: Safety-checks IMD – Fall time limit, for the rise
time (cut-off solenoid valve turned on) and the fall time (cut-off solenoid valve turned off) respectively. Once the
consecutive number of test passed, both rise times and fall times, is equal to the value of P3100: Safety-checks IMD –
Pass criteria, the test is evaluated as passed and it will be repeated with a negative EH-valve main spool set-point. Once
this test has passed as well, the PVED-CLS will be allowed to go into off-road mode.
© Danfoss | August 2018
Description of parameter
Cut Off Valve Activation Timeout for COV Monitoring feature while
x10mSec entering Off Road state.
INFO: Setting this parameter to 0 will bypass off-road safety check
OEM
Table 9
Range
0 1000 900
AQ00000211 | 39
S