Maximum Efficiency and Minimum Emissions
The automotive engineering provider IAV shares its vision of the intelligent powertrain for tomorrow. It encompasses smart engineering solutions as well as new modules and units that work together to achieve maximum efficiency and minimum emissions. At the 39th Vienna Engine Symposium (April 26 and 27, 2018), the company will be presenting a modular powertrain concept for future vehicle fleets.
The elements in this powertrain unit consist of the completely redesigned base engine that stands out with pre-chamber ignition and a particularly long stroke, together with highly efficient dedicated hybrid transmission with up to 190 kW electric output.
Stricter CO2 regulations will be coming into force from 2020, with current discussions talking about a further decrease of 15% as early as 2025 and even 30% by 2030. There will therefore continue to be a demand for a broad range of drive configurations, while manufacturers also want to launch additional vehicle derivatives. Smart solutions will be needed to keep powertrain variety in manageable limits. In Vienna, IAV will be presenting such a powertrain concept consisting of a three-cylinder base engine with 1.1-liter displacement that has been conceived for a CO2-optimized fleet with several power output levels: as a 72 kW naturally aspirated engine for smaller models, and as a supercharged version with 90 or 120 kW for larger vehicles.
It has been designed with a particularly long stroke to support modern combustion processes. The base engine is optimized in terms of fuel consumption and costs and comes with small package demands and a modular structure. For example, it can be supplemented with valve-lift changeover, balancer shafts or electric accessory units. 3D-printed pistons and advanced thermal management demonstrate technologies that will help to improve engine efficiency even further. Another option for the engine is a new module for all secondary air systems. The module groups together the individual systems used on the engine and in the vehicle so that fewer components are needed.
The corresponding DHT (dedicated hybrid transmission) will also be on show in Vienna. It has just two planetary gear sets and four shifting elements. The transmission is rated for a combined drive torque of maximum 750 Newton meters from the combustion engine and electric motor. The integrated electric motor with a maximum input engine speed of 7,000 rpm can be used in a broad operating range. This particular version proved to be the best among the more than 475,000 transmissions computed with IAV’s “Transmission Synthesis” tool. It stands out with optimum efficiency and small package demand. The electric motor consists of a permanent magnet synchronous motor. Depending on the specific configuration, it supplies between 25 and 190 kilowatts in output with torques from 150 to 500 Newton meters. It is so well integrated in the transmission that it needs little installation space, making it possible for the hybrid powertrain to fit in even smaller vehicles.
Pre-chamber ignition: key technology for spark-ignition engines
Combustion engines will continue to be important elements of future powertrains and therefore have to be made even more efficient. The pre-chamber ignition system presented by IAV in Vienna is a key technology for gradually reducing fuel consumption of spark-ignition engines. The basic idea is that around the spark plug in the cylinder head, a small chamber with a perforated cap is separated from the main combustion chamber. With passive pre-chamber ignition, the compression stroke pushes the mixture through these openings into the pre-chamber where it is ignited by the spark plug. In active pre-chamber ignition, a separate fuel metering device is added that ensures a constant supply of stoichiometric mixture in the pre-chamber, even during lean operation in the main combustion chamber.
Both versions improve engine efficiency: the passive pre-chamber with stoichiometric mixture uses the advantage of reduced knock tendency by increasing geometric compression by about two to three units. The active pre-chamber allows for homogeneously lean engine operation with very low engine-out nitrogen oxide emissions. Tests with the single-cylinder engine show up to 3% improvements in fuel consumption with the passive pre-chamber and up to 8% with the active pre-chamber in the WLTC. In Vienna, IAV will be presenting a near-production exhibit. In addition, Marc Sens, Senior Vice-President of Advance Engineering for Powertrain SI Engine at IAV, will be giving a lecture on “Pre-chamber ignition as key technology for highly efficient spark-ignition engines: new approaches and operating strategies”.
“There is no one drive technology that will be suitable as an all-rounder for every single customer”, says Matthias Kratzsch, Executive Vice-President of Powertrain Development and interim Chief Technology Officer at IAV. “That means we have to find the best powertrain for each specific set of requirements depending on the mobility demands and markets. We aim to get the best out of every powertrain in technological terms, with maximum efficiency and minimum emissions. We see ourselves as working in partnership with our customers to put together the best possible drive system from a wide range of different components.”
Inside view with AR technology
Visitors to the IAV booth can get more than just an outside view of the three-cylinder engine and pre-chamber ignition: an AR (augmented reality) application also gives a virtual inside view of what’s going on.