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240 Landmarks TopDiesel Engine > Mitsubishi Fuso MIQCS combustion system
 Mitsubishi Fuso MIQCS combustion system
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This system achieved both low exhaust gas and fuel consumption by combining low swirl, large bore combustion chambers and high-pressure fuel injection to lower combustion temperature.
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The concept of combustion that achieves both low emissions and good fuel economy in diesel engines is to control the pre-mixed combustion and activate diffusive combustion. For this purpose, the injected fuel and air should be mixed to a uniformly lean mixture, and combustion at low flame temperature should be realized. Therefore, the MIQCS system was developed combining the high-pressure injection of the common rail system, small-diameter multi-injection nozzle holes, and a low swirl intake air port and large bore shallow dish type combustion chamber. Two-stage combustion realized low emissions with high thermal efficiency. MIQCS was installed in heavy-duty trucks and released in 2000.
In 2003, a highly accurate cooled EGR and electronic control technology were introduced to MIQCS for further NOx and PM reduction. Additionally, a positive crankcase ventilation (PCV) system and an on board diagnosis (OBD) system were employed. Furthermore, the newly developed continuously regenerating DPF was added, achieving substantial reduction in PM emissions. MIQCS conformed to the new short-term emissions regulations and ultra-low PM emission diesel vehicle accreditation system (75% or more reduction from the new short-term PM regulation value). This enabled the delivery to customers of clean diesel vehicles with low fuel consumption and high reliability.
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Year manufactured:2000
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Manufacturer:Mitsubishi Fuso Truck and Bus Corporation (then Mitsubishi Motors Corporation)
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Classification:Mass-production system
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Model / Manufacture
Type:Diesel
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Company name:Mitsubishi Fuso Truck and Bus Corporation
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Usage:Exhaust gas treatment, fuel efficiency improvement
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Location:Japan
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Installation model:Large trucks, buses
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Year of manufacture:2000~2000
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Designed by:Cooperation: Bosch
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Specification
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Performance
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Device
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Points of interest, topicality:The combustion system was the major issue in developing a new engine for compliance with the long-term regulations. Opinions were divided between using a jerk unit injector and a common rail system. Introduction of an EGR system was essential, and fuel efficiency improvement in addition to low emissions was the top priority. This was because the engine to be discontinued had good fuel efficiency and was sweeping across the market. This was the engine that cemented Mitsubishi's reputation for good fuel efficiency. The engineers involved in the engine development worked hard to realize an engine with low emissions and good fuel economy. One issue was how to divide the air and fuel injection energy of the diesel engine. Another issue was reviewing and improving the rate of air use for rich and lean two-stage combustion to understand how to realize combustion under introduced EGR but with low NOx and good fuel economy. All characteristics, performance and functions of components were clarified and the engineers kept on searching for new combinations. Finally, MIQCS was developed. Three difficult years of work reached a satisfying conclusion thanks to the combined efforts of all the R&D staff. The new engine containing MIQCS was installed in vehicles and finally released.
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Features:To realize low NOx emissions, air flow was controlled by a combination of low swirl combustion and a large bore shallow dish type combustion chamber for pre-mixed combustion at low temperature. Moreover, for reducing black smoke and fuel consumption, lean diffusive combustion at low temperature was realized. This was achieved as a result of increasing the flow coefficient of the intake port, increasing the air volume by VG supercharger control, and active utilization of cylinder peripheral air outside the combustion chamber. The injection system combines the high-pressure injection of the common rail system with small-diameter multi-injection nozzle holes. This was the world's first combustion system that realized so-called two-stage combustion in a direct injection diesel engine. Moreover, air flow control accompanied by low swirl reduced heat loss, enhancing the effect of reduced fuel consumption.
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Reference materials:・SAE2000-01-1811 (Kazutoshi Mori, Hiroshi Jotaki, Kenji Sakai, et al.)
・Proceedings of JSAE, 20005034 (Hiroshi Jotaki, Kenji Sakai, Kazutosi Mori, et al.)
・JSAE Symposium Text, "Newly Developed Engine", 20014124 (Seiji Okada, Motonobu Toshin, Ryuya Matsuguchi, Noriyuki Utsumi)
・Mitsubishi Motors Technical Review No. 13 (Hirosi Jotaki, Kazutoshi Mori, Kenji Sakai, et al.)
・Mitsubishi Motors Technical Review No. 15 (Hiroshi Jotaki, Lazutoshi Mori, Kenji Sakai, Seiji Okada)
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