Meeting today?s need

To meet the future legislative emission limits with today?s medium and high-speed diesel engines, all engine manufacturers have to consider electronic controlled injection systems, which allow optimised combustion and engine control close to the limits with best possible efficiency.

In Germany there are two independent specialists developing standard and advanced injection equipment: Bosch in Stuttgart, with the Austrian offspring company in Hallein, and L?Orange, also located in Stuttgart. As far as electronic engine control is concerned, there is Heinzmann, located in Schoenau in the Black Forest. Also of importance, because of the company?s presence in the high-speed market, is MTU?s electronic engine equipment, which is not available to third parties.

Bosch in Stuttgart has been very reserved concerning the application of common rail technology on medium and large-size diesel engines, especially for marine propulsion plants. The first application of a Bosch common rail system for marine propulsion was introduced on the market with a high-speed yacht engine derived from the large truck engines of MAN Nutzfahrzeuge at the beginning of this year.

The first Bosch CR systems for large marine diesel engines are currently on test and will go into series production next year considering the intended emission limits of 2006. The programme will cover engine sizes between two and 200 litres displacement per cylinder.

At the CIMAC congress in Kyoto the company presented a comparison between different injection systems stating, that the Bosch common rail system for large diesel engines would be “a new type of modular system” in the injection range between 500 and 3000 mm3 per stroke. This corresponds to a power range from about 100 to 500 kW per cylinder.

The main aim for the new modular system was to avoid pressure pulsation in the system. The solution presented features an integrated damping volume in the high-pressure pump and a split rail volume, which is integrated in the injectors leading to a small rail. The damping volume in the injectors is 50 to 70 times larger than the quantity of a single injection stroke. Bosch expects “a high potential for engine performance, fuel economy and emission optimization”.

Heavy fuel oil

Given its ample experience with common rail systems operating with gas oil, it was quite logical for L?Orange to investigate how far the existing technology could be used for operation with heavy fuel oil. The company introduced the first electronically controlled common rail injection system on the MTU 4000 series in 1997. Now, more than 7,000 Injection systems are in service with this series, around 900 of which are marine propulsion plants.

Today?s common rail equipment is more expensive than that of conventional injection systems. Additional effects on the price are caused by the short periods between changes in emission limits, so standardisation saves development and production costs. L?Orange believes that injectors will gain importance and become more individual. On the other hand, pumps will lose importance and offer a chance for standardisation with operational, economical and logistic advantages.

Against this background the company presented at Kyoto a new family of a platform type high-pressure pump, which has main components that can be used either for MDF or HFO operation. Testing started with MDF and 1800 bar rail pressure and with HFO and 1500 bar on customer?s engines. With two and four-cylinder inline type pumps, L?Orange will cover diesel engine power ratings from 1,000 to 12,000 kW, or if four pumps can be mounted on the gear train up to 20,000 kW. One basic design of this platform pump allows easy adaptations by scaling up or down, depending on the application.

Meeting demands

As the proposed IMO 2 emission limits will require further developed common rail systems with even higher rail pressure, L?Orange says the family of platform pumps will best meet the demands. For existing engines retrofit kits are offered for the conversion to common rail, which can lead to 10 % savings in fuel consumption and considerably reduced exhaust emissions.

The first large project of heavy fuel oil common rail systems started some years ago with the development of the injection system for the Wärtsilä W 32 CR engine series (output 460 kW/cylinder at 750rpm). In this case one single cylinder high-pressure pump was used for each two engine cylinders. Field experience was gained with the installation of these engines in the 8,500 TEU post-Panamax container vessel Axel Mearsk and four sister vessels.

MTU Friedrichshafen is now operating under the heading of DaimlerChrysler Off-Highway ? the division that controls the engine and related business, except for the automotive engine sector. As a specialist of high-speed diesel engines up to 9,000 kW, the company decided back in the 1970s to develop and produce its own electronic equipment for the interface between engine and controls, and also dominate the power train. Today?s ADEC (advanced diesel engine control) units, introduced at the beginning of this year, take over both engine control with multiple injection and integrated system control.

These units are developed and produced in a new Electronic Centre in Friedrichshafen which came into operation mid this year after an investment of E7 million. With this electronic centre MTU is the only off-highway engine manufacturer with its own electronic development and production. As Rolf A. Hansen, managing director MTU Friedrichshafen and head of DaimlerChrysler Off-Highway, stated at the official opening, the company policy will follow the principle to fully integrate the electronic units into the engines to make 100 % use of the electronic potential.

Different systems

About 75 % of all electronic units produced are used for marine propulsion ? 50 % for high-speed vessels and 25 % for yacht propulsion. The programme comprises two different systems, the BlueLine and the MCS-5. BlueLine is a standard system for all engine series except the 8000. It can be installed without special knowledge in electronics and is available in three versions: classic, comfort and avantgarde.

The MCS-5 is a sophisticated electronic control system, which follows the trend of ship automation with the effect of having only a crew of four instead of ten, and with only two needing to be qualified. According to Hansen, the intention is to further develop the electronic units to take over monitoring and control functions in an integrated bridge system.

Speed governers

The specialist of engine speed governors, Heinzmann, has enlarged its programme of electronic engine control systems in recent years. The basic unit is the Dardanos I, which is applicable to diesel engines up to 20 cylinders and different injection systems, including common rail with one or two high-pressure pumps. It may be used with input voltages between 24 and 120 VDC and can control the solenoid valves with voltages up to 110 V without any special power supply.

The latest development is a master/slave system consisting of two control units with communication via CAN bus. Engine control under normal conditions is the job of the master; the injector control is split between both units. In case of a failure in one unit, the other can take over the full job. Thus the engine run is not interrupted.. The beginning of this year such a system was installed onboard of the Cornelia Maersk, controlling a 32/40 MAN B&W engine. The aim is to optimise engine operation and to receive the approval of the classification societies. n