Mitsubishi Fuso unveils new Class 3-5 powertrain

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Updated Dec 7, 2010

Mitsubishi Fuso Truck of America Inc. on Wednesday, Dec. 1, announced that its parent company, Mitsubishi Fuso Truck & Bus Corp. of Kawasaki, Japan, has 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 is designed to meet U.S. Environmental Protection Agency 2010 emissions standards and provide enhanced drivability, and to increase fuel economy more than 10 percent compared to the previous-generation Mitsubishi Fuso 4M50 engine designed for EPA 2007 emissions standards.

The new 4P10 engine – a lightweight, efficient 3-liter in-line 4-cylinder diesel powerplant – is 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, are intended to provide a flat torque curve with excellent response and smooth operation.

The new Duonic dual-clutch transmission, the culmination of a 30-year development effort by MFTBC, is described as the first-ever application globally of a dual-clutch transmission in a commercial truck. The new 6-speed transmission – made to integrate the simple operation of an automatic transmission with the performance and fuel economy of a manual transmission – is designed to work in sync with the new engine to meet the company’s drivability, emissions and fuel-efficiency goals.

MFTA says 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 multivalue 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 are designed to change smoothly without power loss during shifts, and the system is programmed to optimize gear selection, providing fuel savings while maintaining power delivery to the drive wheels and easy drivability for the operator.

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, a Park function used by most automatic transmissions also has been included, which locks an internal transmission gear to help assure safety and stability when the vehicle is parked. Finally, the transmission uses a wet-clutch design, which eliminates the need for regular clutch changes due to wear, thus reducing maintenance costs and contributing to low cost of ownership.

Like MFTA’s previous-generation powertrain, the new setup will use Daimler’s selective catalytic reduction-based BlueTec emissions technology to meet EPA’s 2010 emissions mandate. MFTA says the new powertrain has undergone durability tests accumulating nearly 2 million miles in Asia, Europe and the United States. In addition, the 4P10 engine and BlueTec system already are installed in selected Mitsubishi Fuso trucks operating in Europe, and recently have been introduced into Mitsubishi Fuso’s product line in Japan.