14 Combusti on engine 14 Combusti on engine Combusti on engine 14
The engine Understanding it in its enti rety 14 Kurt Kirsten
204 Schaeffl er SYMPOSIUM 2010 Schaeffl er SYMPOSIUM 2010 205 14 Combusti on engine Combusti on engine 14
The sum of all these requirements and challeng- Efficiency chain of modern gasoline engines Introducti on es requires a holistic approach so that added value can be achieved with new technologies Thermodynamic Camsha phasing In the past, the development of automobiles and compared with current volume production prod- improvements unit 35.3 % exhaust gas heat their drive systems was influenced and pushed ucts. The development of added value can affect Valve trains forward by the application of the latest technol- customers, society, legislators or producers. – - Par ally-variable ogies in many cases. This meant it was possible Mastering or controlling this complexity is the - Fully-variable 78 % engine for market participants to strengthen their posi- actual challenge of the present time. – losses tion or the position of their product brands 30.0 % heat loss by direct differentiation in a generally growing 100 % energy market. used The current market scenario is infl uenced by: Core issues for 4.2 % pumping losses Mechanical Product life cycles which are conti nuously being 8.5 % engine fric on – Fric on current drive improvements – Damping shortened 4.1 % accessories + mech. losses –NVH Increased segmentati on system development 22 % effec ve 4.0 % rolling resistance power High cost pressure 6.9 % air resistance The core issues for passenger car drive system de- 7.0 % acc. resistance Demanding customers expectati ons velopment are the confl icti ng aims of reducing NEDC related fuel consumpti on (CO emissions) on the one High social expectati ons 2 Reference: Prof. Leohold, U. Kassel hand and limiti ng pollutant emissions on the oth- Figure 2 Gasoline engine effi ciency chain in the NEDC er hand (Figure 1). The situati on is also characterized by: Boundary conditi ons such as costs, brand image, Increased legal requirements driving pleasure, comfort, noise and reliability reference. The starti ng points for making improve- 14 A growing percepti on about the limitati ons of must also be taken into account. ments are in the area of variability in the camshaft Thermodynamic resources drive. These are: Gasoline and diesel engines are positi oned com- improvements Signifi cant overcapacity of producti on pletely diff erent with regard to the confl icti ng Camshaft phasing units aims of fuel consumpti on and emissions. Diff erent regional and market-segment-specifi c Parti ally-variable valve train systems The signifi cantly greater potenti al for improve- requirements The gasoline engine is positioned very much in ment is due to the reducti on in the thermodynam- Fully-variable valve train systems the low-emission cat- ic losses. The thermodynamic improvements are egory due to its very targeted at enabling thrott le-free load operati on. Due to the variability in the valve train, the ther- efficient aftertreat- Instead of controlling the intake normally by means Emissions target modynamic process is infl uenced in the area of the ment of exhaust gas- of a thrott le valve, control of trapped fresh air is low-pressure process so that there is a positi ve ef- es. The diesel engine, transferred to the valves. The required pumping fect on the pumping losses and the combusti on on the other hand, is losses are reduced due to the increase in the intake process is opti mized in the area of the high-pres- positioned very much manifold pressure. The required control of trapped sure process. These interventi ons also have a di- Gasoline in the low consump- fresh air is primarily undertaken by varying the rect infl uence on the formati on of emissions in the
on tion category due to opening ti me of the intake valve or by the design of