On the other hand, FEM analysis has been implemented for the thrust block of the bed plate and crankshaft using a three-dimensional solid model.
Deformations and stresses of the thrust bearing parts and the aftermost main bearing saddle have been analyzed at the time when thrust force is acting during ahead and astern operation of the engine.
Thus, it has been confirmed that fatigue safety factors and rigidity of this component are the same as or even higher than those of previous engines thanks to proper arrangement of libs and optimization of wall thickness.
As for crankshaft, stress magnification factor at fillet part were analyzed and to keep same level as conventional engine.
5-2. TEMPERATURE AND STRENGTH OF COMBUSTION CHAMBER
Fig.6 shows results of temperature analysis around the combustion chamber. Temperature evaluation around the combustion chamber has been implemented, setting calculating conditions for each part from results of temperature measurement on developed engines in the past and accumulated results of its inverse analysis.
However, the temperature measurement around the combustion chamber has been implemented on a previous engine in operation under the condition of its brake mean effective pressure nearly the same as that of UEC52LSE, since the brake mean effective pressure of this engine is higher by about 10 percent in comparison to those of previous engines. (See Fig.7.)
From this measurement result, the adequacy of the temperature analysis conditions for the UEC52LSE has been cross-checked.
As a results of due optimization of configurations of combustion chamber components of the UEC52LSE engine using analysis conditions mentioned above, its temperature of combustion chamber components could be kept at the level equal to those of actual values of previous engines. Fig.6 shows results of the evaluation of fatigue strength at various parts using thermal stresses according to results of this temperature analysis and mechanical stresses when imposed maximum cylinder pressure. It has been confirmed that fatigue strength of components around the combustion chamber is at approximately equal levels to these of previous engines and has enough fatigue safety factors thanks to the optimization of their configurations.
5-3. MAIN BEARINGS
Fig.8 shows examples of calculated results of main bearing oil film pressure. We have developed the calculating method for highly accurate bearing loads taking account of the rigidity of crank-shaft, main bearings and housings around main bearings, and the evaluating method for bearing oil film characteristics (EHL) taking account of elasticity as evaluating technology for improving main bearings of UE engines.
The change of oil film pressure distribution on main bearings every moment and its relation to the movement of crankshafts can be grasped by these analyzing methods. Thanks to these methods, the accuracy of analysis of main bearing characteristics has remarkably been improved. These technologies have already been applied to investigation and evaluation for improving main bearings of ships in service. (Fig.9)
For the UEC52LSE engine, the rigidity of the crankshaft and that around the main bearing as well as bearing clearance have been optimized by actively using these new technologies. Thus, generated oil film pressure could be kept under pressure levels of previous well-established engines.
5-4. EXHAUST VALVE ACTUATING SYSTEM AND FUEL INJECTION SYSTEM
High pressure hydraulic oil pipes for the exhaust valve actuating system and fuel injection system have been lengthened compared with those of previous engines due to the integration of the camshaft casing, which has previously been at the lower part of the cylinder jacket, into the column.
Cam profiles and particulars in relation to hydraulic oil pipes have been optimized by using the newest simulators into which measured results on previously developed engines were incorporated.
As a result, neither secondary injection nor cavitation has been found on the fuel injection system. Fuel injection characteristics with water addition (the rate of water addition 50%) has also been calculated. In case of water addition, this system is engineered so that cam lifts are increased to fulfill increase in delivery volume and excessive rises in fuel oil pressure are suppressed by adjusting cam speed by modification of cam profile. Thanks to this contrivance, increase in camshaft driving torque can be suppressed. Taking account of the case of water addition, it has been confirmed that the strength of components in relation to the camshaft driving system have safety factors at the equal level to those of previous engines.
On the other hand, for the operation of exhaust valves, it has been found from analyzed results of hydraulic oil driving simulation that the fluctuation range of hydraulic oil is larger a little during the time of exhaust valve opening in comparison to those of previous engines.
However, the duration of exhaust valve opening could be kept as expected, and the pressure drop of hydraulic oil as well as valve speed at the time of exhaust valve seating could be kept at the equal level to those of previous engines. (Figs. 10 and 11)
5-5. MEASURES TO COUNTER NO* REGULATION
The UE engines can meet NOx regulation by IMO in 2000 (MARPOL ANNEX VI) by adopting fuel valves with low NOx specifications basically. (See Fig.12.)
Moreover, in the development stage of the UEC52LSE, its structure and strength were examined in advance so as to be able to adopt a water addition system (water injection system or water emulsion fuel system) in order to meet anticipated future NOx regulation.
The NOx emission level of this engine can be reduced by about 50% (about 10g/kWh for E3 mode) from those of engines with standard specifications by adding water by about 50% of fuel quantity through the water addition system. Thus this engine becomes environmentally friendly.
6. CONCLUSION
This paper reported the development concept and verified results of the design of the UEC52LSE for reliability. The first engine of this type will undergo operation test in April next year and its expected performance and reliability will be confirmed. After that, this engine will be introduced into market and meet the expectation of customers as an engine with high output and ability to meet future environmental requirements.
