Mitsubishi Fuso Truck of America Inc. (MFTA) has announced that its parent company, Mitsubishi Fuso Truck Bus Corp. (MFTBC), of Kawasaki, Japan, unveiled a new, highly evolved powertrain to be introduced in the next generation of Mitsubishi Fuso Class 3-5 commercial trucks in North America.
The integrated powertrain will meet EPA 2010 emissions standards and provide enhanced drivability, according to the company. It is expected to increase fuel economy well over 10% compared to the previous-generation Mitsubishi Fuso 4M50 engine designed for EPA 2007 emissions standards, the truck maker said.
4P10 engine
The powertrain’s new 4P10 engine is a lightweight, highly efficient, 3-liter, in-line 4-cylinder diesel powerplant designed for rugged service and low fuel consumption. The engine features an intercooled, 2-stage turbocharger, piezo-type fuel injectors, common-rail injection system, dual overhead cams and lightweight block. Careful tuning and higher-revolution operation, combined with the rapid response of the piezo fuel injectors, provide a flat torque curve with excellent response and smooth operation, according to the company.
Duonic transmission
The powertrain’s Duonic transmission is the first ever application of a dual-clutch transmission in a commercial truck, and brings significant customer benefits, the company said. The 6-speed transmission works in sync with the new engine to meet the company’s drivability, emissions and fuel efficiency goals. Specifically, this new transmission technology will integrate the simple operation of an automatic transmission with the performance and fuel economy of a manual transmission.
According to MFTBC, the driver will drive the vehicle just as a standard automatic, using only a throttle and brake pedal – no clutch manipulation is required and no clutch pedal is installed. The transmission’s electronic control system uses a multi-value control system to match transmission shift points to vehicle load, speed, driving conditions and accelerator angle, minimizing torque interruption (power decline) during gear changes. Gears change smoothly, without power loss during shifts.
The system also is programmed to optimize gear selection. These improvements combine to provide maximum fuel savings while maintaining power delivery to the drive wheels and easy drivability for the operator, the truck maker said.
For urban environments, the Duonic transmission offers further enhancements. An “Eco mode” allows the driver to adjust shift points to reduce fuel consumption during heavy traffic operation, and a “creep” function has been added to make control of the vehicle easier when subtle adjustments to vehicle speed are needed in heavy stop-and-go traffic and for hill starts. For added convenience, and as with most automatic transmissions, a park function has also been included, which locks an internal transmission gear to help ensure safety and stability when the vehicle is parked, the company added.
Advanced emission reduction system
BlueTec emissions technology requires no complex changes to the engine’s operation. It provides full emissions compliance by treating the downstream exhaust gas, so engine and transmission characteristics can be optimized exclusively for performance and fuel economy, according to MFTBC.
The system consists of components already introduced to meet US EPA 2007 emissions regulations (the diesel particulate filter, or DPF, and diesel oxidation catalyst, or DOC), which have been enhanced with new BlueTec selective catalytic reduction (SCR) treatment.
The SCR system consists of a catalyst and DEF tank, a DEF doser, and a control module. During operation, the DEF doser atomizes and sprays small, carefully regulated amounts of diesel exhaust fluid into the exhaust stream. Once in the presence of the SCR catalyst, the NOx in the exhaust gas reacts with the DEF to form water and nitrogen. The company said DEF consumption is expected to be about 2% to 3% of the vehicle’s fuel consumption rate, under most common operating conditions.
A high-efficiency exhaust-gas recirculation (EGR) system with integrated EGR cooler also contributes to NOx reduction, the truck maker said.
The new powertrain has undergone durability tests accumulating nearly 2 million miles in Asia, Europe and the U.S. In addition, the 4P10 engine and BlueTec system already are installed in selected Mitsubishi Fuso trucks operating in Europe, and have recently been introduced into Mitsubishi Fuso’s product line in Japan, according to the company.
