Powertrains of the Future

The average powertrain is a lot like the human circulatory system—it is the vital, yet neglected core of an automobile. Automakers often prioritize advancements in powertrain technology often proceeding at a scorching pace in the effort to be the first to achieve the perfect combination of power, fuel-efficiency, and minimal carbon dioxide emissions. Basically, a drivetrain and powertrain differ in that the former includes the heart—the engine—and the latter does not. Engine advancements are carefully planned and meticulous processes that typically require years of research and testing before a practical prototype can evolve. The powertrain research of today will define the engine construction of tomorrow, states Mark Crawford, a columnist for The American Society of Mechanical Engineers. Some of the key developments in this area include:

Extreme Hybridization

Powertrain hybridization is an area of research that has grown exponentially following the need for compliance with stringent emission guidelines and the business imperative of delivering better energy efficiency. Simple hybridization practices such as regenerative braking have made inner-city driving more efficient. However, the use of multi-axle Through The Road (TTR) hybridization continues to gain popularity among manufacturers of commercial and industrial vehicles. A presentation by the Transportation Research Institute at the University of Michigan states that mechanical hybrids may deliver cost-effective long-term efficiencies when compared to purely electrical systems. Since these hybridized powertrains are instrumental in reducing carbon dioxide emission while the vehicle is in traffic, we can expect to see the rapid adoption of this technology.

HCCI and RCCI

Homogenous-Charge Compression Ignition (HCCI) takes the conventional process of an engine by removing the need for spark plugs. Combining the two best processes of diesel and gasoline engines, HCCI is based on the principle of compression of the oxidizer—usually filtered air—and the injection of fuel at a precise timing using temperature and pressure to create a controlled combustion of the fuel-oxidizer mix. HCCI engines allow for a cleaner lean burn, resulting in manifold improvements in engine efficiency. However, one of the issues that manufacturers need to overcome is the high emissions generated during such a burn. Reactivity-Controlled Compression Ignition (RCCI) is a technology that blends multiple fuels of varying reactivity to optimize the combustion process in multiple-injection engines. Fuel mixes such as gasoline and diesel or ethanol and diesel are used in RCCI engines. RCCI improves on HCCI by avoiding several harmful emissions and improving fuel efficiency. These two technologies also spawn the need for advanced transmission systems.

Engine Downsizing

Downsizing has been the talk of several automotive conferences and manufacturer presentations as stricter carbon dioxide emission norms and the need for improved fuel efficiency dictate drivetrain and powertrain design. As passenger vehicles increase their reliance on alternate fuels and hybridization, downsizing internal combustion engines has become increasingly relevant as a part of the long transitional phase between the old guard of massive gas-guzzling cars to the super-efficient zero-pollution vehicles of the future. However, downsizing also implies the optimization of the drivetrain to be able to deliver comparable performance under normal and stress conditions. As research and development in the area of engine downsizing continue, ancillary electrical and mechanical drivetrain innovations are expected to challenge the “bigger-the-better” ethos of the automotive world.