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The Wärtsilä RT-flex50 low-speed two-stroke marine diesel engine:
common-rail system for fuel injection.
common rail system for exhaust valve actuation, and
full electronic control of these engine functions
instead of the traditional mechanical camshaft system.
Benefits:
Smokeless operation at all operating speeds
Lower steady running speeds, in the range of 10–15 per cent nominal speed, obtained smokelessly through sequential shut-off of injectors while continuing to run on all cylinders.
Reduced running costs through reduced part-load fuel consumption and longer times between overhauls
Simpler setting of the engine. The ‘as-new’ running settings are automatically maintained.
Reduced maintenance costs through precise volumetric fuel injection control leading to extendable times between overhauls.
The common-rail system with its volumetric control gives excellent balance in engine power developed between cylinders and between cycles, with precise injection timing and equalised thermal loads
Reliability is given by long-term testing of common-rail hardware in component test rigs.
Higher availability owing to the integrated monitoring functions.
High availability also given by the built-in redundancy, provided by the ample capacity and duplication in the supply pumps, main delivery pipes, crank-angle sensors, electronic control units and other key elements.
The common rail for fuel injection is a single-piece pipe running the length of the engine at just below the cylinder cover level.
The common rail and other related pipe work are arranged beneath the top engine platform and readily accessible from above.
The common rail is fed with heated fuel oil at the usual high pressure (nominally 1000 bar) ready for injection.
The supply unit for the fuel has a number of high-pressure pumps actuated by cams driven through gearing from the crankshaft.
Fuel is delivered from this common rail through a
separate injection control unit (ICU), mounted directly on the rail, for each engine cylinder to the standard fuel injection valves which are operated in the usual way by the high-pressure fuel oil.
Using quick-acting Wärtsilä rail valves, they regulate the timing of fuel injection, control the
volume of fuel injected, and set the shape of the injection pattern.
Each ICU serves the two fuel injection valves in its corresponding cylinder cover.
Each injection valve is separately controlled so that, although they normally act in unison, they can also be programmed to operate
separately as necessary.
The exhaust valves are operated in the same way as in RTA engines by a hydraulic pushrod but actuating energy now comes from a servo oil rail at 200 bar pressure.
The servo oil is supplied by high-pressure hydraulic pumps incorporated in the supply unit with the fuel supply pumps. The electronically-controlled actuating unit for each cylinder gives full flexibility for setting the timing of valve opening and closing.
All functions in the RT-flex system are controlled and monitored through the integrated Wärtsilä WECS-9520 electronic control system.
This is a modular system with a separate FCM-20 microprocessor control unit for each cylinder.
An additional FCM-20 unit provides all connections to other systems such as the remote control and alarm systems.
Lower turbocharger efficiencies at part load normally result in low excess combustion air with fixed valve timing.
Another important contribution to fuel economy of the RT-flex50 engines is the capability to adapt easily the injection timing to various fuel properties having a poor combustion behaviour.
Exhaust gas emissions have become an important aspect of marine diesel engines. All Wärtsilä RTA and RT-flex engines as standard comply with the NOX emissions limit set by IMO in Annex VI of the MARPOL 73/78 convention.
RT-flex engines, however, come comfortably below this NOX limit by virtue of their extremely wide flexibility in optimising the fuel injection and exhaust
valve processes.
A visible benefit of RT-flex engines is their smokeless operation at all ship speeds.
The superior combustion with the common-rail system is largely because the fuel injection pressure is maintained at the optimum level irrespective of engine speed.
At very low speeds, individual fuel injectors are selectively shut off and the exhaust valve timing adapted to help to keep smoke emissions below the visible limit.
The Wärtsilä RT-flex50 low-speed two-stroke marine diesel engine:
common-rail system for fuel injection.
common rail system for exhaust valve actuation, and
full electronic control of these engine functions
instead of the traditional mechanical camshaft system.
Benefits:
Smokeless operation at all operating speeds
Lower steady running speeds, in the range of 10–15 per cent nominal speed, obtained smokelessly through sequential shut-off of injectors while continuing to run on all cylinders.
Reduced running costs through reduced part-load fuel consumption and longer times between overhauls
Simpler setting of the engine. The ‘as-new’ running settings are automatically maintained.
Reduced maintenance costs through precise volumetric fuel injection control leading to extendable times between overhauls.
The common-rail system with its volumetric control gives excellent balance in engine power developed between cylinders and between cycles, with precise injection timing and equalised thermal loads
Reliability is given by long-term testing of common-rail hardware in component test rigs.
Higher availability owing to the integrated monitoring functions.
High availability also given by the built-in redundancy, provided by the ample capacity and duplication in the supply pumps, main delivery pipes, crank-angle sensors, electronic control units and other key elements.
The common rail for fuel injection is a single-piece pipe running the length of the engine at just below the cylinder cover level.
The common rail and other related pipe work are arranged beneath the top engine platform and readily accessible from above.
The common rail is fed with heated fuel oil at the usual high pressure (nominally 1000 bar) ready for injection.
The supply unit for the fuel has a number of high-pressure pumps actuated by cams driven through gearing from the crankshaft.
Fuel is delivered from this common rail through a
separate injection control unit (ICU), mounted directly on the rail, for each engine cylinder to the standard fuel injection valves which are operated in the usual way by the high-pressure fuel oil.
Using quick-acting Wärtsilä rail valves, they regulate the timing of fuel injection, control the
volume of fuel injected, and set the shape of the injection pattern.
Each ICU serves the two fuel injection valves in its corresponding cylinder cover.
Each injection valve is separately controlled so that, although they normally act in unison, they can also be programmed to operate
separately as necessary.
The exhaust valves are operated in the same way as in RTA engines by a hydraulic pushrod but actuating energy now comes from a servo oil rail at 200 bar pressure.
The servo oil is supplied by high-pressure hydraulic pumps incorporated in the supply unit with the fuel supply pumps. The electronically-controlled actuating unit for each cylinder gives full flexibility for setting the timing of valve opening and closing.
All functions in the RT-flex system are controlled and monitored through the integrated Wärtsilä WECS-9520 electronic control system.
This is a modular system with a separate FCM-20 microprocessor control unit for each cylinder.
An additional FCM-20 unit provides all connections to other systems such as the remote control and alarm systems.
Lower turbocharger efficiencies at part load normally result in low excess combustion air with fixed valve timing.
Another important contribution to fuel economy of the RT-flex50 engines is the capability to adapt easily the injection timing to various fuel properties having a poor combustion behaviour.
Exhaust gas emissions have become an important aspect of marine diesel engines. All Wärtsilä RTA and RT-flex engines as standard comply with the NOX emissions limit set by IMO in Annex VI of the MARPOL 73/78 convention.
RT-flex engines, however, come comfortably below this NOX limit by virtue of their extremely wide flexibility in optimising the fuel injection and exhaust
valve processes.
A visible benefit of RT-flex engines is their smokeless operation at all ship speeds.
The superior combustion with the common-rail system is largely because the fuel injection pressure is maintained at the optimum level irrespective of engine speed.
At very low speeds, individual fuel injectors are selectively shut off and the exhaust valve timing adapted to help to keep smoke emissions below the visible limit.
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