Federal-Mogul Powertrain in Southfield Friday announced it is launching its new electrification system for medium- and heavy-duty vehicles. The system is cost-effective, fully scalable, and modular, and can also be customized to meet emission and efficiency targets, the auto supplier reports.
“One of the key questions that motivates us at Federal-Mogul is how we can improve fuel economy and CO2 emissions in commercial vehicles by harvesting waste energy, including both vehicle kinetic energy that is lost during braking, and exhaust gas energy. Our solution must include how to then store it efficiently and return it to do useful work,” says Gian Maria Olivetti, chief technology officer of Federal-Mogul.
Diesel engines are highly efficient in a steady state but are less efficient during transients, or changes in torque request. Federal-Mogul Powertrain engineers are using electrification to further enhance the efficiency of the internal combustion engine during steady-state operation to improve the fuel-economy and emissions impact of the transient conditions.
The new approach involves supplementing kinetic energy recovered through an engine or driveline-mounted generator by electricity generated from an exhaust-driven generator. Energy is then returned either through an electric motor supporting the engine and driveline or by electric supercharging.
Independently controlled tests have shown that a highly-responsive Federal-Mogul motor-generator as small as 12 kW applied to the engine or driveline can enable fuel savings of up to 8 percent on a full-size bus by recuperating energy as the vehicle decelerates and boosting the engine’s torque as it accelerates. The machine’s compact size, fully integrated electronics, and efficient thermal management, combined with increasingly standardized control protocols and a wide range of design and simulation tools, makes integration of the motor-generator possible on existing powertrain designs.
Federal-Mogul’s engineers are seeing further opportunities for waste energy recovery by electrification of the air-loop system. While turbocharging recovers some of the 20-30 percent of the fuel’s energy that leaves the engine in the exhaust gas, there is more to be captured and returned.
The on-board electrical energy, ideally recovered from the vehicle’s kinetic energy or exhaust gas, can be used to improve the dynamic response of the airflow by supercharging. This can enable engine-downsizing, improve emissions, and yield up to 5 percent fuel economy improvement by reducing pumping losses combined with improved fueling and re-optimized gear shift strategies.
“The first few tenths of a second during a transient event, when the combustion system is most heavily challenged, are the worst with regards to the production of toxic emissions, including NOx and particulates,” says Nick Pascoe, managing director of Federal-Mogul Controlled Power Ltd. “The latest fuel systems can respond far more quickly than the airstream, so our strategy allows more benefit to be derived from existing investments in these highly-capable vehicle technologies. By speeding up the supply of air to match the response of the fuel system, we can improve both fuel economy and emissions performance by maintaining better control of the air-to-fuel ratio.”
Rigorous, high-speed control of air-to-fuel ratio is also vital for avoiding detrimental effects to the base engine performance and for managing the temperature and chemical combustion of the exhaust gas.
The key elements in the air-loop electrification approach are Turbo-generator Integrated Gas Energy Recovery System (TIGERS) and Controlled Boosting for Rapid Response Application (COBRA). TIGERS combines an exhaust-driven turbine and liquid-cooled switched reluctance generator to produce a system that converts exhaust gas energy into electrical energy. COBRA liquid-cooled electric superchargers provide the engine with an on-demand air supply able to match drive and operating cycles. When combined with the company’s CPT SpeedTorq highly-responsive electric assist motor/generator technology, the portfolio offers a modular approach that allows the optimum solution to be specified for each vehicle weight and application.
The need to capture large amounts of energy quickly, then return it to the driveline quickly without the long-term storage needed for traction applications, means that smaller, more affordable energy storage solutions are well-suited to the Federal-Mogul Powertrain strategy, says Pascoe. CPT SpeedTorq, TIGERS and COBRA can each be specified for 12 volts, 24 volts or 48 volts.
