Daihatsu Diesel Mfg.Co., Ltd. is currently manufacturing and marketing the DK series of diesel engines (200 to 360 mm in cylinder bore), which meet not only the requirements of their direct users but also the needs of environmental conservation. 　They are now followed by new type compact medium-speed diesels which operate in the lowest power output range (900 min-1 (350kW to 610kW) of marine auxiliary engines running mainly on heavier fuel oil.

　These new type engines, introduced at the beginning of the 21st century, are reliable and sturdy machines, embodying the builder's experience accumulated through the production of its DK diesels for years. Their particular feature is a stroke/bore ratio of 1.59, far higher than that of conventional engines of comparative types, for optimal combustion of heavier fuel oil. This has resulted in a higher compression ratio as well as optimal piston and combustion chamber shapes for the burning of heavier fuel oil, making possible combustion of such a fuel even under light load in spite of the small cylinder bore.

　For the design of the air intake port, which greatly impacts the mixing of heavier fuel oil, the optimal swirl coefficient which would be obtained at a satisfactory level of air flow rate coefficient was determined by simulation. A fuel injection pump with a high injection pressure is well matched with a non-cooled fuel nozzle to make possible fuel economy and low exhaust emission.

　An electronic monitoring and control device, attached to the engine, and an electronic fuel injection device are available to enhance the handling ease of the engine and to achieve a further cutback on exhaust emission.

　The engine is cooled with a mixture of fresh water from the cooler line and the jacket line. While jacket cooling water is kept at a constant high temperature, a two-stage cooling system is used for the air cooler, which is supplied with the high-temperature fresh water from the jacket line and with low-temperature fresh water. The air intake temperature is raised to make possible combustion of heavier oil even under light load.

　The cooling water line and passage configuration and the lubricating oil system of earlier engines have been modified, pumps, coolers and other auxiliaries concentrated in the fore part of the engine, and various multifunctional constituent parts adopted, resulting in simplified and easy-to-handle engines substantially reduced in piping complexity and the number of constituent parts. Main moving parts and constituent elements have been verified by structural analysis using state-of-the-art analytical software. At the same time, new type engines will be confirmed in quality through continuous durability tests of actual machines.

Address:4-14, Tokui-cho 2-chome, Chuo-ku, Osaka 540-0025

Tel:+81-6-6945-5319　Fax:+81-6-6945-5301

E-mail:kazutoshi.sato@dhtd.co.jp URL:http://www.dhtd.co.jp/