Recent improvement in Diesel engine techniques has always been demanding the high quality crankshaft with higher strength and service reliability. The first part of this paper deals with the improvement of fatigue limit and reliability of both solid type crankshafts made of C-steel and Cr-Mo higher tensile strength steel associated with continuous grain flow forging (RR crankshafts) . After then, it describes the strengthening effects of fillets cold rolling for a Cr-Mo higher tensile strength steel crankshaft. The second part deals with the relationships between hardening features and operational conditions of fillets cold rolling. It describes the hardening features are mainly influenced by the two factors of the roll pushing force and yield point of material, and scarcely affected by other operational conditions. In connection with this, it suggests that as an assurance measures of fillets cold rolling, the roll contact width after the treatment and the hardness increase of fillets on completion of crankshafts will be preferable.
Based on the data obtained through design research and various tests made with the charging system used in the prototype of the supercharged 4-cycle medium-speed diesel engine, this paper deals with the three major problems in the supercharging system through comparative studies between theoretical calculations and actual surveyed values. The three major points are: - 1. Pump work during suction/exhaust strokes. 2. Effective utilization of exhaust gas energy. 3. Optimum designing of the turbine.
In order to study the blade stress of a propeller in operation, full scale measurements were performed on the container ship “HAKONE MARU” in her 39th voyage between Japan and the west-coast of the United States, as a part of the research programme of Shipbuilding Research Association of Japan. The protection of gauges against sea-water, which was one of the most difficult problems in this kind of the test, was overcome by the newly developed method of double coating with the low-temperature solder and the epoxi-resin. Not only the fluctuation of the blade stress in calm sea, but also that in steady turn and in rough sea, which were scarcely reported up to the present, were obtained with success. A comparison of the measured data with those of calculation based on a quasi-steady approach was made and the validity of this calculating method is discussed.
Most of the endurance tests regarding the strength of diesel engines are intended to examine whether the structural parts can stand more than 107 cycles of gas pressure stress through a long period continuous operation under a certain constant load. However, the combustion chamber wall is particularly required to stand the combined fatigue strength for the repeated thermal stresses and repeated gas pressure stresses. Therefore, an endurance test method for the strength of the diesel engine combustion chamber was studied. And in order to ascertain a method of fatigue life estimation which becomes a basis of the above endurance test, a comparison was made between the results of the engine fatigue test of the cast iron-made piston and cylinder cover and the results of theoretical fatigue life estimation which is based upon a concept of the combined fatigue strength.
The author has conceived the idea of Electromagnetic Gears, in order to provide power transmitting devices of high efficiencies expected to be used in ship propulsion systems of large outputs. An electromagnetic gear is constructed by incorporating an electromagnetic coupling with a synchronous motor connected electrically with each other. It is composed of an inner rotor adapted to be driven by a prime mover for ship propulsion, an outer rotor adapted to drive a propeller, and a stator. The electromagnetic gear has a special feature that the propeller can be driven in directions same as and opposite to the direction of rotation of the prime mover, besides features that the construction is stable and reliable, that large capacity, for instance 80, 000 PS. of Electromagnetic Gear can be easily manufactured, and that the efficiency of the gear itself is considerably high. However, the most important thing is that synthetic efficiency, cost and arrangement of whole ship system plant using Electromagnetic Gear are superior to those of other systems. It is believed, considering the present circumstances of Petroleum, that Electromagnetic Gear systems combined with 4 or 2 cycle diesels can be used in VLCC, ULCC, super-high speed ships or special vessels. The fundamental conception and theory of Electromagnetic Gears are described, results of tests for supporting the theory are introduced, and the applications are outlined in this paper, which can be a guidance for testing a 16, 000 PS. electromagnetic gear being constructed now.
The flow pattern on the gas flow through exhaust valves in Diesel engines is considered very important in relating to the utilizing exhaust gas energy, the charging efficiency, and the contamination of exhaust valves. But this problem has not satisfactorily been made clear. We have done visualization test gas flow through the exhaust valves using the chimney tunnel and found that these air flow have a two different flow pattern according to the increase valve lift. The first flow pattern until some definite amount of lift is seen as a flow along the surface of valve stem and apart from the inside of valve seat accompanying a dead water region. The second flow pattern after some definite amount of lift is seen as a flow apart from both of the surface of valve stem and inside of valve seat accompanying dead water region. We have known that the flow quantity at the second flow pattern is no significant change for the increasing of valve lift, since air flow passage is nearly no change. For the analytical investigation of this flow, we analysed using the flux analysis. For example, we have calculated 20mm of valve lift and have obtained its flow pattern and the shape of the dead water region.