Fuel economy improvement on medium-duty tactical truck has and continues to be a significant initiative for the U.S. Army. The focus of this study is the investigation of Automated Manual Transmissions (AMT) and mild hybridization powertrain that have potential to improve the fuel economy of the 2.5-ton cargo trucks. The current platform uses a seven-speed automatic transmission. This study utilized a combination of on-road experimental vehicle data and analytical vehicle modeling and simulation. This paper presents the results of (1) establishment of a validated, high fidelity baseline analytical vehicle model, (2) modeling and simulation of two AMTs and their control strategy, (3) optimization of transmissions shift schedules, and (4) modeling and simulation of engine idle stop/start and Belt-Integrated-Starter-Generator (B-ISG) systems to improve the fuel economy. The fuel economy discrepancy between experimental average and the baseline simulation result was 2.87%. The simulation results indicated a 14.5% and 12.2% fuel economy improvement for the 10-speed and 12-speed AMT respectively. A stop/start system followed by a B-ISG mild hybrid system incorporating regenerative braking was estimated to improve fuel economy 3.39% and 10.2% respectively.
The impact of the vehicle fuel economy in tactical convey is amplified due to the fact that much of the present logistics support is devoted to moving fuel. Fuel economy improvement on medium-duty tactical truck has and continues to be a significant initiative for the U. S. Army. The focus of this study is the investigation and analysis of Automated Manual Transmissions (AMT) that have potential to improve the fuel economy of the 2.5-ton cargo trucks. The current platform uses a seven-speed automatic transmission. This study utilized a combination of on-road experimental vehicle data and analytical vehicle model and simulation. This paper presented the results of (1) establishment of a validated, high fidelity baseline analytical vehicle model, (2) modeling and simulation of two AMTs and their control strategy, and (3) optimization of transmissions shift schedules to minimize the fuel consumption. The fuel economy discrepancy between experimental average and the baseline simulation result was 2.87%. The simulation results indicated a 12.2% and 14.5% fuel economy improvement for the 12-speed and 10-speed AMT respectively.
This paper reports the planning efforts and preliminary results of increasing fuel economy in the current fleet of medium-duty tactical truck. A strategic plan was developed through investigation of current and future technology offerings from original equipment manufacturers and after market suppliers. Research efforts consisted of an initial phase where a broad range of integration candidates were collected and a secondary phase where in-depth analysis was conducted to target those to be considered for inclusion in the strategic plan. The strategic plan lays out the integrated technologies in the near term including auxiliary electrification of engine cooling fan and hydrogen injection. For the mid-term time frame, the plan involves implementing an engine stop/start system and electrifying other auxiliaries. The final step in the plan is the development and implementation of a full hybrid population. The preliminary results include simulation of the electric cooling fan and mild hybrid powertrain, and experimental test of hydrogen injection.
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