the marine diesel prime mover

Sulzer RT Flex Marine Diesel Engine The common rail system described Authored by: Journal of the Norwegian Union of Marine Engineers , 2004 Brought to you by www.dieselduck.net , comments to [email protected] This web page provides a description of the Sulzer RT Flex electronically-controlled common-rail system embodied in Sulzer RT Flex low-speed, two stroke marine engines. It covers the main elements of the RT Flex syst em - the supply unit, rail unit and electronic control system. The system's benefits a re reviewed , together with it s reliability and built-in redundancy. Introduction Although common -rail fuel injection is certainly not a new idea, it has only become truly practical in recent years through the use of fully-integrated electronic control based on high-performance computers which allow the best use to be made of the flexibility possible with common-rail injection. The traditional camshaft has t he consider able limitation of fixed timing given mechanically by the cams. Although Sulzer low-speed engines have long had the benefits of double valve-controlled fuel injection pumps with variable injection timing (VIT), and a degree of variable exhaust valve timing being achieved hydra ulically in the VEC system, t he variation in t iming so obtained has been very limited. Instead electronically-controlled common-r ail syst ems have been adopted in the new Sulzer RT Flex engines to give complete control of the timing, rate and pressure of fuel injection and the exhaust valve operation, allowing patterns of operation which cannot be achieved by purel y mechanical systems. Rather than 'electronically controlled', it would be more accurate t o describe Sulzer RT Flex engines as being computer controlled . This is because in t he RT Flex syst em, engine functions are fully programmable, perhap s limited only by t he designers' imagination and the laws of nature. The challenge is to use this freedom to create pr actical benefits for engine users. The common-rail con cept was adopted also because it has the advantage that t he functions of pumpin g and injection control are separated. This a llows a st raightforwar d approach to the mechanical and hydra ulic aspects of t he design, with a steady generation of fuel oil supply at t he desired pr essure ready for injection. The common-rail concept also has t he unique advantage that it allows t he fuel injection valves to be individually controlled. Usually there are three fuel injection valves in each cylinder cover, and in the Sulzer RT Flex engines t hey are operated mostly in unison but under certain circumstances they are operated separ ately for optimum combustion performance. The common-rail concep t t hus provides an ideal basis for the application of a fully-integrated electronic control. The combined flexibilities of common rail and electronic control provide improved low-speed operation, engine acceleration, balance between cylinders, load control, and longer times between overhauls. They also ensure better combustion at all operating speeds and loads, giving benefits in lower fuel consumption, lower exhaust emissions in t erms of both smokeless operation at all operating speeds and less NOx, emissions, and also a cleaner engine internally with less deposits of combustion residues. Engine diagn ostics are built into t he system, improvin g engine monitoring, reliability a nd availability. The m arine die sel pri me mover. - The two stroke pl ant http:/ /www.die seld uck.ca/m achin e/0 1 p ri me m overs/r t fle x/i ndex.ht 1 of 7 11-07-2011 21:2

the marine diesel prime mover

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