CONSEIL INTERNATIONAL DES MACHINES A COMBUSTION INTERNATIONAL COUNCIL ON COMBUSTION ENGINES PAPER NO.: 221 Development of Electronically Controlled Engine Mitsubishi UEC Eco-Engine Katsuhiko Sakaguchi, Mitsubishi Heavy Industries Ltd., Kobe Shipyard & Machinery Works, Japan katsuhiko sakaguchi@mhi.co.jp Masahide Sugihara, Mitsubishi Heavy Industries Ltd., Kobe Shipyard & Machinery Works, Japan Abstract: For one hundred years since the birth of the diesel engine, diesel engines have been developed to improve three major factors, i.e. thermal efficiency, power rate, and reliability. At present, diesel engines are facing new important issue, environmental friendliness, and most technological efforts have been concentrated on this issue. Mitsubishi Heavy Industries, Ltd. (MHI) had completed the development of the electronically controlled engine, the UEC Eco-Engine, with our own technology for more environmental friendliness with much enthusiasm, in addition to high performance and reliability in any operating condition, which are the traditional main features of the UEC engine. The Eco-Engine is driving fuel injection pump, exhaust, starting air, and cylinder lubricator with electronic control system. The UEC Eco-Engine can bring less operating cost and stable operation in addition to reduction of NOx emission and smokeless operation. We have already completed the development of the UEC33LSII-Eco, the UEC50LSII-Eco, and the UEC60LSII-Eco and extend to larger bore size engines. The fundamental mechanism of the electronically controlled engine has been verified on single-cylinder research engines (NC33 and NC45) at MHI Nagasaki Research & Development Center since 1988. The prototype system has been under commercial running on the 7UEC33LSII-Eco as a stationary diesel generating set at MHI Kobe Shipyard & Machinery Works over two and a half years with very good service experience. We are convinced that the UEC Eco-Engine has much flexibility for environmental friendliness based on actual running results. In this paper, we introduce the system construction, the development concepts, and major test results on research engines and the first full-scale Eco-Engine. c CIMAC Congress 2004, Kyoto
INTRODUCTION In the large marine diesel engine industry, the trend of electronically controlled engines has jumped forward rapidly. The UEC Eco-Engine has been developed in response to the increasing demand for environmental friendliness. In addition, the objective of the Eco-Engine is to benefit ship owners and operators in terms of total operating costs, maintenance requirements, and compliance with stricter emission regulations anticipated in the near future. Its development was based on experiences with research engines and a prototype engine. The first full-scale Eco-Engine, the 7UEC33LS-Eco, has been proving its reliability and performance over two and a half years of various operations, as a stationary diesel generating set at the Mitusbishi Heavy Industries Kobe Shipyard & Machinery Works. In the middle of 2005, the first commercial UEC Eco-Engine, the 8UEC60LS-Eco, will begin service in a pure car and truck carrier. Concepts of the UEC Eco-Engine The new engine is named for the letters of Eco, which are found in its design goals of ecology, economy, easy control (better maneuverability), and excellent engine condition (higher reliability), all by electronic control. 1. Electronic control The fuel injection, exhaust actuating and starting air systems are controlled electronically. 2. Ecology NO x emission can be reduced and smokeless operation achieved. In addition, our patented stratified fuel and water injection system, a drastic NO x reduction technology, may be applied in combination with the Eco-system to cope with the stricter NO x emission regulations anticipated in the future. 3. Economy Lower specific fuel oil consumption, especially in partial loads and less maintenance cost can be obtained. 4. Easy control The Eco-Engine assures stable low load operation with good engine performance. Easy change of operating modes and finetuning of operating conditions are possible during operation. 5. Excellent engine condition (higher reliability) Appropriate fuel injection pressure and optimum injection timing, most favorable for the combustion condition at any load, will further enhance the reliability of the hot components proven on the UEC engine. In addition to the above, we have completed development of another advanced system. An epoch-making cylinder lubricating system, the SIP system, can reduce cylinder lubricating oil consumption dramatically and improve the condition of cylinder liner and piston ring. An engine diagnosis system, DOCTOR-DIESEL, assures stable operation and management of the spare parts and maintenance interval. Needless to say, these systems can be combined with the Eco- Engine. History of the UEC Eco-Engine Project Foreseeing possible future requirements, we began study on various solutions as early as 1988. The fundamental system has been verified on single-cylinder research engines, the NC45 (45-cm bore) and NC33 (33-cm bore) at MHI Nagasaki Research & Development Center over a long period. The first generation of the electronic system was tested on the NC45 research engine. This test was carried out from 1988 to 1993, and verified the system performance and reliability for more than 1,200 hours of various operations. The concept of the system proved the expected potential. The second generation of the electronic system was followed on the NC33 research engine and tested until 1997. Its results boosted our belief that the electronically controlled engine will become an advanced engine for complying with the future requirements within the industry. Figure 1 shows the NC33 research engine. CIMAC Congress 2004, Kyoto Paper No.221 2
Based on the above-mentioned good experimental results, the project of the UEC Eco-Engine started in early 2000 to meet the growing market demand. The 7UEC33LS engine, a stationary diesel engine generating set at the MHI Kobe Shipyard & Machinery Works, was converted to the first fullscale Eco-Engine in December 2001 and has been proving its reliability through two and a half years of various operations. In this engine, the electronic control system was retrofitted to the conventional engine. The aspects of the engine can be seen in Fig. 2. The main particulars of the engine are listed in Table 1. Retrofitted electronic-control device view from driving end Figure 1 NC33 research engine at MHI Nagasaki Research & Development Center Table 1 Main Particulars of the 7UEC33LSII-Eco Cylinder Bore mm 330 Piston Stroke mm 1,050 Number of Cylinders - 7 Output kw 3,775 Engine Speed rpm 212 view from fore end Figure 2 The 7UEC33LSII-Eco at MHI Kobe Shipyard and Machinery Works As mentioned above, we concentrated on the reliability and performance of the electonically controlled system through a long span of verification tests and succeeded to confirm the reliability as well as the performance data. We will introduce the first commercial project of the UEC Eco-Engine in a later section. CIMAC Congress 2004, Kyoto Paper No.221 3
MHI s Low Emission Technology In general, our technological plans to cope with further strict NO x regulation are described in Figure 3. cams, camshaft, and driving gears. On the other hand, the electronic control system with the hydraulic oil supply system is added. Accordingly, the maintenance work on these mechanical components is eliminated and the computational tuning of engine operating conditions also eliminates the delicate adjusting work on these parts both in the shop and on board. The ease and fine-tuning of the operating conditions are possible during operation. This means that operation of the engine will be much more flexible compared with the conventional type of engine. The overview of the fuel injection and exhaust actuating mechanism are described in Figure 5. Conventional Engine UEC Eco-Engine Figure 3 Application to low NO x emission technology To comply with the IMO s (International Maritime Organization) first regulation, which is estimated to go into effect in the middle of 2005. We have already delivered all our engines complying with the regulation, by optimization of the fuel injection nozzle and the fine tunings of our traditional engines. For the second regulation, estimated that regulation level will be harder by 20 to 30 % compared with the first regulation, we plan to apply the UEC Eco- Engine or the water injection system combined with the conventional engine. Governor Fuel-linkage Roller guide Camshaft with Cams Camshaft shifting device Camshaft driving gear Figure 4 Fuel injection Fuel injection system Controller Control unit Accumulator block Automatic back-wash filter Hydraulic pump Hydraulic pump driving gear Fundamental structure of engine Fuel Exhaust actuating system Exhaust driving gear For the stricter regulation expected from the third regulation, we would combine the Eco-Engine with the water injection system. According to the regulation level, other technologies will be needed, for example SCR (Selective Catalytic Reactor). Foreseeing future demand, we will maintain our effort to develop the necessary technologies. Control unit Main Fuel injection pump Accumulator block Exhaust driving oil Main Exhaust Control unit Hydraulic oil 320bar to Crankcase Fundamental Structure of the UEC Eco-Engine The fundamental structure of the engine is seen in Figure 4, compared with the conventional engine. By electronic control, the engine structure is much simplified by eliminating conventional large mechanical parts, such as the fuel and exhaust Figure 5 System overview of cylinder component The fuel injection pump and the lower exhaust driving gear are actuated by 320bar hydraulic oil. This pressurized oil is accumulated in the accumulator block mounted at each cylinder. The connection blocks are applied to connect each manifold block. The accumulating mechanism is CIMAC Congress 2004, Kyoto Paper No.221 4
simple and reliable in that pressure compensation during actuating is carried out by the volume in the accumulating chamber. Therefore, a pressurized gas enclosed-type accumulator is not necessary. The hydraulic power for fuel injection and exhaust actuation is controlled by an on-off type solenoid unit and engine control system. The timing of the fuel injection and exhaust open/close are also controlled electronically to achieve the best condition for any operation mode. This concept simplifies readjustments needed to maintain better operating conditions. In the down-stream from the fuel injection pump and the lower exhaust driving gear, the same design concepts of the conventional system are applied in order to reduce crew education for new maintenance work about such components. Fuel Injection System Figure 6 shows a cross section of the fuel injection system for the UEC Eco-Engine. The fuel injection pump has a similar structure to the conventional mechanical one but is rather simplified. This means that the maintenance work for the fuel injection pump is already familiar to the crew and overhaul time is reduced. As one of its main features, two sets of on-off type solenoid s are mounted to control the injection pattern, depending on the operating load, in order to improve the trade-off relationship between thermal efficiency and NO x emission. The experimental results of this mechanism will be introduced in a later section. The mechanism for changing the fuel injection pattern is shown in Figure 7. This is our patented technology that is put into practice by a pair of onoff type solenoid s. Main flow Sub solenoid Larger orifice small flow Smaller orifice Pilot oil Main solenoid Control mechanism to Fuel injection pump Main High pressure hydraulic oil The main opening velocity is controlled with two modes by the sub solenoid. Control of the fuel injection rate contributes to reduction of the NOx emission. Fuel injection pump to fuel injection Main lift Example of fuel injection pattern Original injection Controlled injection Sub solenoid open Main Accumulator block Accumulating chamber Fuel injection pressure (MPa) Original injection Controlled injection Crank angle from control signal (deg) Figure 6 Fuel injection system Figure 7 Control of fuel injection pattern CIMAC Congress 2004, Kyoto Paper No.221 5
In addition, we are now undertaking incorporation of a water injection system with the Eco-Engine in order to comply with the stricter NO x emission regulation expected in the near future. The feedback control function is applied to the control of fuel injection volume to compensate the equivalent thermal load and individual cylinder control. The fuel pump stroke is monitored by twin gap sensors at each cycle. This emphasizes the reliability of the system through observation in the control system. Exhaust Valve Actuating System Figure 8 shows a cross section of the exhaust actuating system for the UEC Eco-Engine. The exhaust open and close timing is controlled by the electro-hydraulic system using the on-off solenoid unit. Accordingly, the timings are optimized depending on the operating load. For precise timing control, the feedback control function is applied by observation of the exhaust lift. The actuating mechanism is similar to the conventional mechanical ones and inherits their reliability and the method of maintenance. Control Valve Unit The solenoid units are key components of the electronically controlled engine. For the unit of a large electronically controlled engine, a very quick response, high flow rate, and long life cycle are required. We therefore started the development of the in 1999 and already confirmed the performance. The most important issue is reliability for a long life cycle. Thus, the endurance test has been undertaken. And, up to now, the has finished a 300-million cycle test corresponding to approximately six years of actual operation on board and has satisfied its requirement. The small size unit for a bore 40-cm class engine has also been verified in the prototype of the 7UEC33LS -Eco. The performance and endurance of the medium size unit for a bore 60-cm class engine was verified on the test bench. This bench is similar to the fuel injection system in Figure 9. Fuel injection pump Upper part of driving gear Lower part of driving gear unit Accumulator block Figure 9 Control unit on test bench Main Accumulator block Figure 8 Accumulating chamber Exhaust actuating system Starting Air System Figure 10 shows a comparison of the starting air system. The conventional starting air control is eliminated and solenoid s and a control air pipe are added. The starting s are controlled electronically to achieve better performance and flexibility for engine starting and crush-astern. CIMAC Congress 2004, Kyoto Paper No.221 6
Starting air main pipe This hydraulic system produces hydraulic power for the above-mentioned systems. This system includes both the engine driven pumps, which supply pressurized oil mainly during engine operation, and the electronically driven pumps, which maintain system pressure when the engine is at a standstill. The engine driven pumps are coupled through a gear drive to the crankshaft and are both direction revolution type axial piston pumps. Conventional engine Eco-Engine Control System Control air main pipe Starting air main pipe The engine control system is prepared for the Eco Main Controller (EMC) installed in the control room and is interfaced with the Remote Control System. The Local Control Box (LCB) and the Eco Cylinder Controller (ECC) are mounted on the engine. These controllers are connected by a duplicated network line. An overview of the control system is provided in Figure 12. Eco-Engine About EMC Figure 10 Comparison of starting air system Hydraulic Oil Supply System A hydraulic oil supply system (see in Figure 11) is also a key component of the Eco-Engine. M Electric motor-driven pump Manifold block Engine-driven pump Electronic control device For redundancy purposes, the controller is comprised of two units operating parallel and performing the same task, as they are duplicates of each other. If the active EMC fails, the stand-by unit will take over control without any interruption. The EMC performs such tasks as: Speed governor functions Start/stop sequences Timing control of fuel injection, exhaust actuation, and starting air systems Control of the hydraulic oil supply system Alternative operation and control modes Network function Malfunction observation of entire control system M High pressure line Low pressure line Return line Figure 11 for flushing line Automatic back-wash filter unit Automatic back-wash filter Redundancy filter Hydraulic oil Crankcase Hydraulic oil supply system Lubricating oil for Engine P Lubricating oil pump About ECC Each ECC is mounted on an individual cylinder. It performs the orders for timing of fuel injection, exhaust actuating and starting air systems. For redundancy purposes, the ECC has the capacity to be able to control two cylinders. If an ECC fails, the one of another cylinder takes over automatically. CIMAC Congress 2004, Kyoto Paper No.221 7
About LCB This controller provides for the engine side control as an emergency if the Remote Control System or both EMCs fail. This means that the operator can choose two operating modes and the third redundancy of the EMC. C/R backup control board Remote Control System Safety system Conventional system In addition, the reliability of the hardware of the control system was evaluated against surrounding conditions, such as vibration, temperature, and noise. Test Results In this section, major results are introduced. EMC Eco-Engine Control System Improvement of engine performance and emission characteristics LCB Cylinder control board (No.1) Network Cylinder control board (No.n) The trade-off relationship between the thermal efficiency and NO x emission was improved in the Eco-Engine. Figure 14 shows the results of the NC33 research engine. Reduction of NO x emission can be obtained at the same specific fuel oil consumption (SFOC). Driver Driver ECC ECC Controlled injection Original injection Figure 12 Control system overview We developed an evaluation tool called the Real Time Simulator (RTS) in Figure 13. This tool simulates engine running conditions, for example, start/stop, crush-astern, rough sea, and malfunctions, to verify control sequences. The image of this tool is to create a virtual engine in the simulator. We verified the first commercial control system by using this tool before running it in our shop. Relative SFOC (%) Figure 14 Change of injection timing Constant Pmax Relative NOx (% ) Results of optimum fuel injection pattern RTS PC I/O interface Eco-Engine Control System ECC EMC Remote Control System Based on our test results, we evaluated actual operating conditions (see Figure 15). To operate the Low Emission Mode, the reduction of NO x emission can be obtained at the same SFOC. On the other hand, to select the Economy Operating Mode, the SFOC can be reduced 1 to 2 percent compared with conventional engines. The engine operation mode can be changed over easily by the switch on the controller. The above advantages are achieved by optimization of the fuel injection timing and injection pattern and the timings of exhaust actuating according to engine operating load, atmospheric condition, and fuel properties. Figure 13 Real Time Simulator CIMAC Congress 2004, Kyoto Paper No.221 8
Conventional engine [Normal operating range] Optimization of the exhaust timing SFOC Eco-Engine 10 15% Constant Pmax Current operating point (assumption) By electronic control, the timings of the exhaust open/close are optimized flexibly according to engine operating load. Low emission mode NOx emission 1 2% Economy operating mode Figure 17 shows the reduction of the SFOC by optimization of the exhaust opening timing. The effect increases in a lower load because the timing of the exhaust in the conventional engine is optimized and fixed at high loads. Figure 15 Improvement of engine performance and NO x emission characteristics Appropriate fuel injection pressure Load 50% Conventional engine (fixed timing) The fuel injection system is improved significantly with the electro-hydraulic system. Thus, smokeless operation can be achieved at any load. Figure 16 is shown the comparison of the fuel injection pressure and the Bosch Smoke Number measured on the research engines. 100 SFOC 100% 75% Eco-Engine (optimally variable) 110 115 120 125 130 135 Opening (deg) timing of exhaust (deg) Fuel injection pressure(mpa) 90 80 70 60 50 40 30 20 10 Eco-Engine Appropriate injection press. from lower load Conventional engine Figure 17 Optimization of exhaust opening timing Service Experiments on the First Full-scale Eco-Engine As introduced in the before section, the first fullscale Eco-Engine, the 7UEC33LS-Eco, has been proving its reliability and performance over two and a half years of various operations. Bosch Smoke Number 0 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 0 20 40 60 80 100 Load (%) Experimental result of diesel oil operation Conventional Engine Eco-Engine 0 20 40 60 80 100 Load (%) Figure 16 Smokeless operation Every year, the mechanical parts of the electronically controlled system have been inspected. Extremely good condition was observed, as seen in Figure 18. However, some minor problems occurred and have been corrected and readjusted at the early period of the operation. These problems are summarized as follow: Software bug of the crank angle detector In the some case of starting, the controller recognized incorrect crank angle. Its cause was the inappropriate transformation from time to crank angle. The averaging revolution speed was used to calculate crank angle in the control system. So, if the revolution changing speed is fast, above-mentioned problem occurred. We had solved this problem by using the instantaneous revolution speed. CIMAC Congress 2004, Kyoto Paper No.221 9
Failure of the amplifier for the hydraulic oil pump Deviation of the hydraulic oil pressure occurred because the electric circuit in the amplifier had the initial problem. So, we solved by exchanging to the improved products. Slightly flatting between the accumulator block and lower part of exhaust driving gear At the first inspection after 1,000hr operation, slightly flatting on the accumulating block was found. We solved this problem by increasing the tightening torque of the bolts for mounting the lower part of exhaust driving gear. Summary of Advantages As a summary, the distinctive advantages of the UEC Eco-Engine are as follows: Environmental friendliness Smokeless operation can be achieved by appropriate fuel injection pressure at any load. Reduction of NOx emission can be obtained by tuning of the fuel injection timing and pattern at any load. Lower SFOC (Specific Fuel Oil Consumption) The timing of fuel injection and exhaust actuation can be optimized flexibly by electronic control according to engine operating loads, atmospheric conditions, and fuel oil properties. Accordingly, lower SFOC can be obtained, especially in partial load. Easy control (better maneuverability) The Eco-Engine assures stable continuous low load operation, even for extremely low loads, with good engine performance because of improvement of combustion conditions thanks to appropriate fuel injection pressure and optimized timing of fuel injection and exhaust actuating in lower load. Higher reliability In the Eco-Engine, appropriate fuel injection pressure, most favorable for the combustion condition at any load, will further enhance the high reliability of the hot components proven on the conventional UEC engines, such as the piston crown, piston ring, cylinder liner, and exhaust. Flexible operation Easy change of operating modes and fine tuning of operating conditions are possible during operation. Less maintenance (b) Exhaust actuating piston Figure 18 (c) Hydraulic piston of Fuel injection pump Inspection result after two and a half year operation With electronic control, the engine structure is significantly simplified by eliminating conventional large mechanical parts. Accordingly, maintenance work on these mechanical components is eliminated and the computational tuning of engine operating conditions obviates the need for delicate adjustment work on these parts both in the shop and aboard. CIMAC Congress 2004, Kyoto Paper No.221 10
The First Commercial UEC Eco-Engine In the middle of 2005, the first commercial UEC Eco-Engine, the 8UEC60LS-Eco, will begin its service in a pure car and truck carrier. The engine, with the exception of the electronically controlled system, is manufactured by Kobe Diesel Co., Ltd., who is one of our licensees. The electronically controlled system is provided by us as the licenser. In addition, its comprehensive test in our shop will start in August 2004. Its main particulars are listed in Table 2. [3] H.Sakabe and K.Sakaguchi, The UEC Engine Development Program and Its Latest Development, CIMAC Kyoto 2004 Table 2 Main Particulars of the 8UEC60LSII-Eco Cylinder Bore mm 600 Piston Stroke mm 2,300 Number of Cylinder - 8 Output kw 15,540 Engine Speed rpm 104 CONCLUSION The UEC Eco-Engine was intorduced with test results on research engines. The advantages and features of the Eco-Engine were also discussed. In addition to the main features of the conventional UEC engine, less fuel oil consumption, less lubricating oil consumption, and high reliability, etc., the Eco-Engine s features will bring various advantages such as less operating cost and stable ship operation to the ship owners and operators, which is attractive to clients within the industry. We expect that the electronical controlled engine will become a leading engine over the next decade. This prediction will be confirmed by the comprehensive tests to be held on the first commercial Eco-Engine in August 2004. In addition, its service experience will also prove its potential. REFERENCES [1] H.Sakabe and M.Okabe, The UEC-LS/LSE Engine Development Program, CIMAC 2001, pp.28-37 [2] S.Lauristen, J.Dragsted and B.Buchholz, Swirl Injection Lubrication, CIMAC 2001, pp.921-932 CIMAC Congress 2004, Kyoto Paper No.221 11