The international automotive supplier Continental will report on further potential for making gasoline engines even more economical. To comply with future exhaust-gas legislation and CO2 limits, efficiency within the engine must be further increased. “Since the gasoline engine is the most widespread drive system for passenger cars worldwide, and will remain so in the foreseeable future, every improvement here will potentially have a large-scale effect. This applies equally to engines with port fuel injection systems as well as to those with direct injection,” says José Avila, head of the Powertrain division and member of the Executive Board at Continental. “The central challenges for the automotive industry are first to develop ever more efficient vehicles and second to make these vehicles fun to drive. We see ourselves as one of the leading technology companies, developing a variety of innovations.”
In Vienna, Continental will present enhanced technologies that will help to make gasoline engines even more efficient. The package of technology on show will consist of leaving the intake valve open longer (the Miller cycle), coupled with a higher compression ratio and low-pressure exhaust-gas recirculation (EGR). The desired optimization of the radial compressor and use of Continental radial-axial turbine technology (RAAX ™) demonstrates that modern turbocharger systems can compensate for the disadvantages of a Miller process even with conventional single-stage turbocharging systems. To further optimize the combustion process itself, the automotive supplier is developing new high-pressure injectors in test engines. “To achieve the European CO2 targets for 2020, there will also be an increasing proportion of hybridization with electric drives of 48 V and above, particularly in the medium to higher vehicle segments. In the future, systems expertise for all efficiency modules will be even more important when it comes to maximizing vehicle efficiency,” says Avila.
Diverse CO2 technologies
One of the aims of optimization within the engine is to improve the position of the central combustion point in the knock-limited load range of the gasoline engine. Continental achieves this in a 1.0 l turbocharged engine by keeping the inlet valves open longer and through cooled low-pressure exhaust-gas recirculation, which improves fuel consumption by 3–6 g per kWh. Forced induction is carried out by a Continental turbocharger with radial-axial turbine technology (RAAX). It improves drivability when using the Miller strategy, because a turbocharger with a RAAX turbine achieves higher boost pressure at lower engine speeds than a standard turbocharger with a conventional turbine. This enables the engine to generate more torque. Continental is also working on multi-stage forced-induction techniques that use an additional turbocharger and even an electrically powered booster. This can significantly improve the responsiveness of the combustion engine, which in turn improves power output and drivability. The majority of harmful emissions from a modern gasoline engine is produced during the cold-start and warm-up phases, which is why Continental will also present a dynamic thermal management system that can significantly shorten the time it takes for an engine to warm up in the New European Driving Cycle (NEDC). Controlling the flow of coolant is also particularly important for hybridization in order to keep the heat in the engine’s cooling system during hybrid driving strategies such as coasting (switching off and disconnecting the combustion engine). The integrated electrically heated catalytic converter also supports engine-off strategies. The rapid electric heating of the catalytic converter dispenses with the need to use fuel to heat the catalytic converter and prevents additional consumption and hydrocarbon emissions that would otherwise occur when the combustion engine is restarted due to the catalytic converter not yet being up to operating temperature.
Injection and control for greater efficiency
Fuel injection is key to high efficiency, both in engines with port fuel injection and in gasoline direct-injection engines (GDI). The new Deka 10 injectors for port fuel injection (PFI) have a greater spread between the smallest and largest possible flow, which is important for higher-powered engines as well as for turbocharged engines. Deka 10 injectors produce smaller droplets, which leads to better carburetion and thus more efficient combustion. On the subject of optimization within engines with gasoline direct injection systems, Continental will report in Vienna on the potential shown by a 1.8 l test engine.
Increasing the injection pressure from 250 to 350 bar, using the new XL5 injectors with an optimized injector-hole design and the GHP 2.5 high-pressure pump (GHP = gasoline high pressure), could reduce particulate emissions in exhaust gas by 80%, with fuel consumption remaining the same. This will help achieve the urgent objectives for DI engines.
As valve control variability and low-pressure exhaust-gas recirculation become more common, the freedom in engine control will increase. Conversely, this can lead to a significant increase in the number of calibration-data maps in the engine control unit. To limit the need for storage and the cost of calibration, Continental is further developing its EMS3 engine-control and powertrain system platform for use in multi-core processors. These processors can compute powerful polynomial models in real time, for example for engine injection with high precision.
48-Volt Eco Drive: electrification in figures
Hybridization is the ideal addition to help increase the efficiency of the combustion engine, and it will also help reduce emissions. Recuperation makes energy available for efficient driving strategies and gives the combustion engine a power boost. The Continental 48-Volt Eco Drive System, for example, has demonstrably reduced fuel consumption by up to 21% in urban areas. Thanks to the favorable cost-benefit ratio of the 48-volt architecture, hybridization is moving closer to high-volume models in the C and D segments. Production ramp-up for the first 48-Volt Eco Drive in Europe has been planned for 2016. Further production orders have already been received from the U.S.A. and from Asia. The automotive supplier forecasts that around 20% of all new vehicles will feature electrification in their drive systems by 2025, almost half of which will have a 48-volt system.
Intelligent driving strategies thanks to connected energy management
Today, an engine control unit relies exclusively on signals from vehicle sensors. But in the future it will also be able to use information from external sources such as other vehicles or a cloud.
Connecting the vehicle powertrain to the cloud makes connected energy management possible, giving the end customer significant added value in the form of reduced fuel consumption. In hybrid vehicles this helps to optimize drive management, while electric vehicles can improve their range.
This is based upon real-time traffic and route data as well as, for example, traffic light phases. Vehicles with connected energy management will know in advance when to switch the engine off without negatively affecting traffic flow or the duration of the journey. The first test vehicles are already in the test phase.