Fig.5: Four examples of fuel injection pressures at the fuel valve, and the corresponding fuel valve spindle lifting curves
Some examples of the capability of the fuel injection system are shown in Fig.5. The pressure in the fuel valve and the needle's lifting curve are shown for each of the four injection patterns. Tests on the engine with such patterns have confirmed that the 'progressive injection' type (which corresponds to the injection pattern with our optimised camshaft driven injection system) is superior in terms of fuel consumption. The 'double injection' type gives a slightly higher fuel consumption, but some 20% lower NOx emission. The role of the IE concept in ensuring compliance with emission regulations is dealt with in our paper from Panel Discussion 2.
2.4 Exhaust valve actuation system
The exhaust valve is driven by the same servo oil system as that used for the fuel injection system, using pressurised cool, clean lube oil as the working medium. However, the necessary functionality of the exhaust valve comprises only control of the opening and closing timing of the valve. This can be obtained by using a simple fast-acting on/off control valve to control the movement of the exhaust valve.
The system features well-proven technology from the present engine series. The actuator for the exhaust valve system is of a simple two-stage design. The first-stage actuator piston is equipped with a collar for damping in both directions of movement. The second-stage actuator piston has no damper of its own, and is in direct contact with a gear oil piston which transforms the hydraulic system oil pressure into oil pressure in the oil push rod. The gear oil piston includes a damper collar that becomes active at the end of the opening sequence, when the exhaust valve movement will be stopped by the standard air spring.
2.5 Control system
Redundant computers provide the control functions of the camshaft (timing and rate shaping). This new Engine Control System (see also [5]) is an integrated part of the Intelligent Engine that brings completely new characteristics to the engine. It comprises two Engine Control Units (ECU), a Cylinder Control Unit (CCU) for each cylinder, a Local Control Terminal and an interface for an external Application Control System. The ECU and the CCU have both been developed as dedicated controllers, optimised for the specific needs of the intelligent engine.
The Engine Control Unit controls functions related to the overall condition of the engine. It is connected to the Plant Control System, the Safety System and the Supervision & Alarm System, and is directly connected to sensors and actuators. The function of the ECU is to control the action of the following components and systems:
・The engine speed in accordance with a reference value from the application control system (i.e. an integrated governor control)
・Engine protection (overload protection as well as faults)
・Optimisation of combustion to suit the running condition
・Start, stop and reversing sequencing of the engine
・Hydraulic (servo) oil supply (lube oil)
・Auxiliary blowers and turbocharging.
The Cylinder Control Unit is connected to all the functional components to be controlled on each cylinder. Its function is to control the activation of features like:
・Fuel injection
・Exhaust valve
・Starting valve
・Cylinder lubricator for the specific cylinder.
As faults can never be completely ruled out, even with the best design of electronic (or mechanical) components, the concept for the intelligent engine has been designed with great care regarding fault tolerance and easy repair, to ensure the continuous operation of the ship. Since each cylinder is equipped with its own controller (the CCU), the worst consequence of a CCU failure is a temporary loss of power from that particular cylinder (similar to, for instance, a sticking fuel pump on a conventional engine). The engine controller (ECU) has a second ECU as a hot stand-by which, in the event of a failure, immediately takes over and continues the operation without any change in performance (except for the decreased tolerance for further faults until repair has been completed).
In the event of a failure in a controller, the system will identify the faulty unit, which is simply to be replaced with a spare. As soon as the spare is connected, it will automatically be configured to the functions it is to replace, and resume operation. As both the ECU and the CCU are implemented in the same type of hardware, only a few identical spares are needed. If failures occur in connected equipment - sensors, actuators, wires, etc. - the system will locate the area of the failure and, through built-in guidance and test facilities, assist the engine operating staff in the final identification of the failed component.
2.6 Cylinder pressure measuring system (PMI)
A reliable measurement of the cylinder pressure is essential for ensuring 'as new' engine performance. A conventional mechanical indicator in the hands of a skilled and dedicated crewmember can provide reasonable data. However, the necessary process is quite time-consuming and the cylinder pressure data obtained in this way is not available for analysis in a computer, which means that some valuable information is less likely to be utilised in a further analysis of the engine condition. A computerised measuring system with a high quality pressure pick-up connected to the indicator bore may provide this. We have developed such a system, PMI Off-Line, of which more than 100 sets have been sold for application on our conventional engines.
For the Intelligent Engine, on-line measurements of the cylinder pressure are necessary or at least greatly desirable. In this case, the indicator cock cannot be used since the indicator bore will clog up after a few days of normal operation, making further measurements useless.
