Heinz Bühl

New product aimed to optimize air intake system for low end torque enhancement

Low end torque enhancement for turbocharged engines is now more important than ever due to upcoming new regulations after Euro 6 with real drive emission application. With further trend to reduce the weight of next cars generation, there is the need to adapt and reduce continuously the size of engine and its components to find good trade-off between engine size, vehicle performances, fuel consumption and costs. This paper is describing how air intake systems can be optimized taking into account the particularity of small turbo charged Diesel engines of passenger cars. The novelty of the paper is to address the benefit value thanks to the optimization of interaction between all stand-alone components like turbo chargers, charge air coolers, ducts and air intake manifolds. It is described and demonstrated thanks to both simulation and testing, how switchable volume and length can help the performance improvement while reducing the engine displacement. As resonance charging is the physics used here to help low end torque improvement up to more than 10 percent for 4-cylinder engines, and even more for 3-cylinder engines, a special new design of a switchable air intake system is shown, giving good performances in terms of pressure waves propagation and pressure loss. Tests on prototypes made on engine bench are showing the benefits of such a concept compared to state of the art. The complete air intake system composed of plastic parts routing the air from the charge air cooler to different charges air ducts geometry will offer at the end a new possibility for increasing volumetric efficiency thanks to resonance charging also for small turbocharged engines, at a reasonable cost. Also for new turbo charged gasoline engines, as real drive emission could impact scavenging and air/fuel ratio control in a wider engine operating range. In this case again, resonance charging thanks to air intake system geometry could be a way to compensate lack of performance especially at very low engine speed.

A model based system approach to innovative smart intake products: CO2 savings and specific performance

On modern combustion engines, air induction systems are evermore evolving into more complicated elements with an objective to find the best trade-off between fuel consumption, pollutant emissions and engine performance. This pursuit has led to the emergence of the downsized turbocharged engine. For such an engine, it’s necessary to reinforce the low end torque. This is because, at low operating speeds and loads, the lack of enthalpy at the exhaust side causes a poor behavior of the turbocharger which leads to a poor boost pressure and consequently a deficit of engine performance. The proposed idea in this case would be to benefit from an optimized ‘smart’ air intake system to solve this issue while assuring other interesting functions as well. First, cylinder filling can be enhanced by assuring acoustic resonance conditions at the intake. The result is an increase of air flow leading to a better torque response and vehicle responsiveness. Pressure waves induced boosting can also help to reduce the thermal stress on the turbocharger as well as the size of the charge air cooler. Secondly, pressure waves can help to save energy by ‘de-throttling’ at part load operation on an SI engine. This has the effect of reducing the pumping loop and thus enhancing specific fuel consumption. Mechatronic integration into smart systems at the intake is necessary to achieve such goals. The Active Charge Air Duct (ACAD) and the active air intake manifold presented in this paper are innovative plastic products that aim to reduce fuel consumption. This is achieved through geometries with a high flexibility of thermoplastic processes.

Reducing fuel consumption and CO2 emissions by optimizing active intake systems for naturally aspirated and turbocharged engines

Lower fuel consumption and fewer emissions – these are two of the key requirements of modern engines. A decisive and economically efficient influencing parameter in this context is improvement of the gas exchange process in engines through the optimization of active intake systems. Since the end of the 1980s, intensive work has been carried out on improving the gas exchange process for naturally aspirated gasoline engines through the use of optimally adapted intake systems. The pressure pulses of the air intake system caused by the gas exchange process are used to achieve high charge filling of the combustion chamber. To this end, the lengths, diameter and volumes of the intake manifold between the throttle body and the inlet valves are adapted to the desired engine speed range. In order to achieve optimal filling over a wide speed range, active intake manifolds were introduced that permit switchable flow paths for the intake air by means of active switching elements such as flaps and rotary valves. Typically, different resonance runner lengths or resonance volumes are employed.