Main Engine Control System for Internal Combustion Marine Diesel Engines

Main engine control system is used for automatic remote control and protection of main ship's diesels. It permits to change direction and speed rotation of propeller directly from the bridge by navigators. The system consists of the equipment installed on the bridge, engine control room (ECR) locally mounted near the engine.

The set of Engine Remote Control equipment in ECR essentially consists of a panel fitted up with the various signalling, alarm and control facilities, in addition to the electronic modules (both logic and analog).

Electronic Control Modules Rack comprises:
a) Engine starting and reversal logic module, with LED display (direction of rotation indicator) of logic status and starting set-point adjust potentiometer status;
b) Digital/analog engine RPM converter with cut-in thresholds and LED display of the status of the thresholds and thresholds adjusting potentiometers.
c) Engine control programmer with LED display of stand-by, RPM reduction, emergency, etc. and acceleration gradient adjusting potentiometer.
d) RPM controller with potentiometers for variables and operating limits adjustment.
e) Torque lirniter, with limit indicator.

Locally Mounted Equipment comprises electro-hydraulic type actuator, for remote control of the fuel linkages; the said actuator is continuously linked mechanically to the lever and is therefore driven by the manual handwheel when it is deenergized.

The equipment also comprises induction type pick-ups to monitor the number of RPM's and rotating direction, as well as a five-position servo-motor, complete with four devices to position the engine local control lever for reversing gears and starting air distributors for engine stop, running ahead, starting ahead, running astern, starting astern. Equipment on Bridge comprises:

1. Engine telegraph.
2. Automatic control panel. It has the following items mounted on panel front:
a) Manual power limiter.
b) Engine speed fine adjustment potentiometer.
c) Illuminated push-button for bridge control demand.
d) "Control transfer inhibited" signal display.
e) "Control on the bridge/ECR" signal display.
f) Direction of engine rotation indicator (LED).
g) Engine RPM indicator.
h) Fuel oil lever actuator position indicator.
3. Shield push-button for emergency stop and emergency manoeuvring.

Starting Control from ECR. Navigation

By shifting the telegraph lever from FULL AHEAD to NAVIGATION, a gradual acceleration program is activated; the program is adjustable and enables the engine to reach navigation RPM's in the desired lapse of time. If any fault occurs during gradual load take-over the engine load increase is interrupted; the engine stabilizes at the value reached at the moment in which the fault occurred and remains in that condition until the fault disappears.

Automatic resumption of power increase takes place according to the preset gradient.

If one of the stand-by causes persists beyond a given time the device automatically starts decreasing the load, beginning from stand-by position and persists until its determining cause disappears. The decrease may occur according to two adjustable speeds which are automatically selected by the programme as a function of the seriousness of the fault.

The following are some of the anomalous conditions which determine the limiting and safety functions described above:

• fresh cooling water high temperature at the outlet of each cylinder; 
• cylinder exhaust gas high temperature versus average value; 
• cylinder exhaust gas mean temperature;
• thrust bearing, journal bearing, stern tube bearing, crosshead bearing, and big end bearing high temperatures;
• cylinder average high temperature, piston cooling fluid low flow rate;
• engine luboil high temperature;
• fuel injectors cooling fluid flow failure.

If any of the above variables, in particular bearing temperature and luboil pressure, reach exceptionally critical values, RPM reduction is converted to an engine lockout.

Emergency

Shield push-buttons are provided both on Bridge and ECR. By means of these push-buttons some safety and protection facilities may be excluded (RPM reduction, torque limitation, acceleration gradient, engine power manual limitation).

If a "crash stop" is affected in this condition, the admission of starting air takes place at a number of RPM's higher than required for normal reversal and the RPM set-point, as well as positioning limit of the fuel oil lever are automatically brought to a third emergency level.

If said emergency starting RPM's are not reached within a certain limit, the air valves close and a starting failure alarm is displayed.

To repeat the "crash stop" operation, the operator must reset the engine telegraph on STOP position and then set the desired number of RPM's.