Mitsubishi Corrosion Resistance Steel (MCRS), which has superior material characteristics has been developed to improve propulsive efficiency of marine propellers. The reduction in weight and moment of inertia of MCRS propeller also makes shafting system so compact in comparison with the case of nickel aluminum bronze (NiAlBz) propeller. More than 20 MCRS propellers were put in service in these 10 years after the initial development of the material with fundamental tests and the actual ship tests including observation of cavitation erosion.
It is expected that, in the future, ships will operate under ideal conditions which take into account safety, reliability and cost. Propulsion engines installed on such ships are required to have greater versatility which can secure optimal operation in response to changing conditions ( including engine load and speed, fuel properties, and atmosphere ) . Electronic control is a vital technology which realizes the greater versatility of marine diesel engines. The fuel injection and inlet/exhaust valve systems remarkably influence the engine performance. However, these systems are not yet fully controlled electronically in practical use. This paper describes newly-developed, hydraulically-actuated mechanisms that can conduct both the fuel injection and the inlet/ exhaust valve operation of diesel engine through solenoid valves, thus obviating the conventional cam-driven mechanism. We combined these mechanisms with the electronic control unit, that was also developed in our study, and mounted them as a “mechatronics system” on an uprated, single cylinder test engine for the verification test. The test results proved that not only can these mechanisms provide stable operational characteristics over a wide range of operation, but they also can operate accurately and smoothly under various conditions through electronic control. This paper describes the fruit of the Technological Research Association of Highly Reliable Marine Propulsion Plant.
During the past several years we have been intereseted in and have conducted research and development on the electronic control technology of marine diesel engines. In the electronically controlled engine, the inlet valve, the exhaust valve and the fuel injection valve are driven by a hydraulically powered system. We decided to use a solenoid valve, which is superb in reliability, for the electro-hydrauslic conversion part which converts the electric signal into hydraulic oil pressure in the hydraulically powered system. We successfully developed a high-speed solenoid valve which operates in 1 msec. Then, a micro-computer based digital control system was chosen for the control equipment which plays a major role in the hydraulically powered electronic control system. An engine simulator was also developed to confirm the operation and checked the functions of the electronic control equipment. After fully confirming its relibability, the electronic control equipment was connected to an actual engine, which produced favorable operation results. This paper describes the fruit of The Technological Research Association of Highly Reliable Marine Propulsion Plant.
Large turbochargers for marine diesel engine application have as a rule been driven by the axial-flow turbine with fixed pitch nozzles, with consequent disadvantage, especially in constant pressure turbocharging, of being poor in part-load performance and in acceleration in the low-load range. Developed by Mitsubishi Heavy Industries, Ltd. this time to remedy this disadvantage is a MET-SR-VG turbocharger, which is driven by the radial-flow turbine with variable-pitch, or variable-geometry (VG), nozzles. The radial-flow turbine employed is of new design specifically devised for the SR-VG turbocharger application and thus can cover the same output -range as the conventional large-size axial-flow turbine. A MET33SR-VG turbocharger, prototype machine of the SR-VG design manufactured in 1986, was tested for matching with an actual diesel engine on shore and then put through a series of various kinds of test aboard a seagoing ship, with highly successfully results as expected. Also, in 1987, a MET66SR-VG machine, the first production unit and then the largest to be manufactured, was completed for installation on an 8UEC75LSII, which itself was also the first production engine of Mitsubishi UEC75LSII design built for VLCC application. Commissioned in service in April 1988, the 66SR-VG machine has since been in successful operation.
This paper discusses structure and characteristics of the power system and the main engine system based on the research report by Electric and Electronic System Committee. This report mainly deals with examples of the power system installed in the recent merchant ships, but does not give the review, comments and characteristics on the marine power system and main engine system. However, observing the examples shown in it in detail, it is clear that there are many common trends and characteristics in the control methods and structure of the power and propulsion system. In particular, though the merchant ship and its engine system depend deeply on the economical conditions and circumstanses, the statistical viewpoints provides us many useful informations about the power system, the marine propulsion system, and the relation between them. First, the first half of this note gives the useful results obtained by the statistical techniques, that is the Weibull probability paper. Next, the second half discusses the structure of the power system, particularly the relationship between power system and the main engine system, which includes the exhaust gas boiler or economizer, and then provides the trends and the characteristics of the automatic control methods or techniques utilized in the power system.