Daihatsu Diesel's 3DK-20 Type Engine
The three-cylinder 3DK-20 engine is the latest model of the DK-20 series, which, together with the five-, six-, and eight-cylinder versions, cover a wide range of power outputs with the same design concept. The 3DK-20 model is aimed at the 400kW market to meet the high demand for marine power generation engines in this range.
Having the same basic structure as the other DK series diesel engines (the 5DK-20, 6DK-20, and 8DK-20 engines), the 3DK-20 solves vibration problems by the use of a balancer shaft located opposite the cam shaft.
1) With the introduction of the 3DK-20, Heavy Fuel Oil (H.F.O) can now be used in the output range previously covered by high-speed diesel engines running on Marine Diesel Oil.
2) Reduction in number of cylinders means higher mean effective pressure at the same power output compared to that of six cylinder engines. This enables stable running on H.F.O. even under low-load conditions commonly encountered by generator engines.
3) Although the time taken for maintenance per cylinder does not vary much with change in cylinder bore, the maintenance time of an engine is proportional to the number of cylinders. Accordingly, the 3DK-20 requires only half the maintenance time as six-cylinder engines.
The cost of replacement parts is also greatly reduced due to less cylinders.
4) The 3DK-20 engine satisfies the IMO's NOx control requirements with no modification to standard specifications and without sacrificing low fuel consumption. This is achieved by the use of well matched turbochargers, combustion chamber profile and fuel injection system matching, and an appropriate compression ratio.
5) By using an optimal balance weight capacity and a balancer shaft, the vibration is suppressed to a level comparable to the best balanced six-cylinder engine.
6) Main parts, such as pistons, piston rings, air intake and exhaust valves, fuel nozzles, crank pin bearings, main bearings, and cylinder liners are the same as those used in the other DK-series engines. With more than 800 DK-series engines sold, the reliability of these parts is tried and proven.
7) The cylinder head bolts are fastened by a hydraulic tool for easy handling. Bolts of the same type are also used to fasten the main bearing cap, so that the same tool can be used. The connecting rod can be split into three parts, so that shank of the connecting rod can be detached from the big-end portion. This leads to reduction in maintenance time, and a lower piston extraction height.
8) Compared with other makers' six cylinder generator sets, the generator set with the 3DK-20 is about 500 mm shorter in length.
Daihatsu Diesel Mfg. Co., Ltd.
Address： 2-10, Nihonbashi-Honcho 2-chome, Chuo-ku, Tokyo 103-0023
Tel： +81-3-3279-0827 Fax： +81-3-3245-0395