Operation4002−1/A1
Winterthur Gas & Diesel Ltd.
10/ 22
3.3 Exhaust Valve Control
3.3.1 Exhaust Valve − Function
When the engine operates, the exhaust valve opens and closes once during each full
turn of the crankshaft related to the defined crank angle position (see Fig. 5).
The control valves CV7401−08C are installed on the exhaust valve control unit. The
control valves are connected to the CCM-20 on each cylinder (see Fig. 2 and Fig. 3).
The engine control system activates the control valve CV7401−08C to open/close the
exhaust valve.
The valve stroke sensor ZT5421−28C monitors the movement of the exhaust valve.
On each cylinder, the CCM-20 individually adjusts the stroke and timing to the correct
values.
3.3.2 Exhaust Valve − Control
The exhaust valve movement is controlled as follows:
D The crank angle and the variable exhaust opening (VEO) are used to calculate
the open command of the exhaust valve.
D The open deadtime, the time between the open command and 15% of the valve
stroke, is measured.
D The crank angle and the variable close command (VEC) are used to calculate the
close command of the exhaust valve.
D The close deadtime, from the close command to 15% of the valve stroke, is
measured.
D After one full turn of the crankshaft, the timing for the next cycle is adjusted in
accordance with the deadtime of the cycle before.
3.3.3 Emergency Mode
If a valve stroke sensor becomes defective and there are no valid deadtime values
from the other cylinder control units available, the system default time settings are
used for the open and close deadtimes of the related exhaust valve. If the system
default values are used, the related cylinder operates at reduced power.
Air spring air
Orifice
All components shown in
the CLOSED position
Servo Oil Return
Servo Oil Rail
CV7401−08C
Valve Stroke
Sensor
ZT5421C−
ZT5428C
Exhaust
Valve
Exhaust
Valve
Control
Unit
Fig. 5: Exhaust Valve Control
Engine Control System
2015-12
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