•
After the crankshaft has completed one full turn, the timing for the subsequent cycle is
compared to the deadtime of the cycle before and corrected.
6.2.4.2.4
Emergency mode
If a valve stroke sensor becomes defective, the system uses the average time settings from the
serviceable cylinders for the open and close dead-times.
6.2.4.3
Starting valve control
The FCM-20 opens and closes the starting valve directly during each full turn of the crankshaft
at a specified crank angle (and for a specified angle sector) until the engine operates.
6.2.4.4
Crank angle sensor
Two crank angle sensor (CAS) units that operate independently are installed at the center of the
engine. Each CAS unit has three proximity sensors and one reference sensor to calculate the
position of the crankshaft gear wheel. The reference sensors 1 and 2 find the related crank
angle reference mark (TDC or BDC). The proximity sensors are connected to the ACM-20
modules.
The ACM-20 modules calculate the accurate crank angle from signals of the related proximity
sensors. One ACM-20 transmits signals through CAN bus M#4 to FCM-20 #4 of the
WECS-9520. The other ACM-20 transmits signals through CAN bus M#5 to FCM-20 module
#05. The two ACM-20 modules send the crank angle data to all FCM-20 modules through the
SSI bus.
6.2.4.4.1
Crank angle signals
The signals and the power supply for the sensors are monitored. Malfunctions are shown on the
flex View. Also, the LED on the ACM-20 show the status of the CAS unit.
An alarm, slow-down signal or shut-down signal shows if the three signals are not in a specified
tolerance.
6.2.4.4.2
Crank angle algorithm
The ACM-20 module gives the accurate crank angle position. After power-up of an ACM-20
module, the crank angle data are only available when the engine turns the crankshaft to a
position after the related reference mark.
6.2.4.4.3
Function
If power becomes disconnected (which will have an effect on the two ACM-20), the WECS-9520
calculates the crank angle algorithm given below.
The crank angle algorithm starts automatically when:
•
The WECS-9520 sends a signal to start the engine and
•
The two ACM-20 do not have the correct crank angle data (no accurate angle).
X92DF
AA00-0000-00AAB-043K-A
Operation Manual
Engine control system WECS-9520
Winterthur Gas & Diesel Ltd.
- 265 -
Issue 002 2020-08
