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In the near future, emissions legislation will become more and more restrictive for direct injection SI engines by adopting a stringent limitation of particulate number emissions in late 2017. In order to cope with the combustion system related challenges coming along with the introduction of this new standard, Hitachi Automotive Systems Ltd., Hitachi Europe GmbH and IAV GmbH work collaboratively on demonstrating technology that allows to satisfy EU6c emissions limitations by application of Hitachi components dedicated to high pressure injection (1). This paper sets out to describe both the capabilities of a new high pressure fuel system improving droplet atomization and consequently mixture homogeneity as well as the process of utilizing the technology during the development of a demonstrator vehicle called DemoCar. The Hitachi system consists of a fuel pump and injectors operating under a fuel pressure of 30 MPa.

Given the fact that, in an endeavor to achieve the goals of engineering for a trade-off between cleaning up exhaust emissions and maximizing fuel economy, two main paths are being followed in advancing and optimizing SI-engine operating strategy in the upper part-load range. On the one hand, homogenization and operation in the compression ignition mode seem to offer a promising means of minimizing NOx emission by keeping the combustion temperature below the formation borderline and accepting a high cylinder-pressure gradient to obtain benefits in fuel economy. On the other hand, there are ambitions to widen the range of stratified operation using a supercharger or turbocharger. This way, efficiency of the engine cycle can be improved by operating at a higher global air-fuel ratio and, with this, a higher polytropic exponent, thereby taking the efficiency chain to a higher level.

In Gasoline Direct Injection engines, direct exposure of the injector to the flame can cause combustion products to accumulate on the nozzle, which can result in increased particulate emissions. This research observes the impact of injector fouling on particulate emissions and the associated injector spray pattern and shows how both can be reversed by utilising fuel detergency. For this purpose multi-hole injectors were deliberately fouled in a four-cylinder test engine with two different base fuels. During a four hour injector fouling cycle particulate numbers (PN) increased by up to two orders of magnitude. The drift could be reversed by switching to a fuel blend that contained a detergent additive. In addition, it was possible to completely avoid any PN increase, when the detergent containing fuel was used from the beginning of the test. Microscopy showed that increased injector fouling coincided with increased particulate emissions.

The combination of geometrically variable compression (VCR) and early intake valve closure (EIVC) proved to offer high potential for increasing efficiency of gasoline engines. While early intake valve closure reduces pumping losses, it is detrimental to combustion quality and residual gas tolerance due to a loss of temperature and turbulence. Large geometric compression ratio at part load compensates for the negative temperature effect of EIVC with further improving efficiency. By optimizing the stroke/bore ratio, the reduction in valve cross section at part load can result in greater charge motion and therefore in turbulence. Turbocharging means the basis to enable an increase in stroke/bore ratio, called β in the following, because the drawbacks at full load resulting from smaller valves can be only compensated by additional boosting pressure level.

Reduction of the CO2 greenhouse gas emissions is one major challenge the automotive industry as a part of the transportation sector is facing. Hydrogen is regarded as one of the key energy solutions for CO2 reduction in the future transportation sector. First, a hydrogen-powered single-cylinder test rig for 2 liter heavy-duty engine will be introduced. Followed by a discussion of experimental results including variations of engine speed, torque, ignition strategy, air-fuel ratio, etc. In addition, the paper proposes a new phenomenological model for the prediction of hydrogen combustion. The model is based on the well-known two-zone Entrainment approach, supported by newly developed hydrogen-specific submodels for the calculation of the laminar flame speed and auto-ignition in the unburned mass zone. The developed physical-based combustion model is extensively validated based on the experimental single-cylinder results.

A simulation method is presented for the analysis of combustion in spark ignition (SI) engines operated at elevated exhaust gas recirculation (EGR) level and employing multiple spark plug technology. The modeling is based on a zero-dimensional (0D) stochastic reactor model for SI engines (SI-SRM). The model is built on a probability density function (PDF) approach for turbulent reactive flows that enables for detailed chemistry consideration. Calculations were carried out for one, two, and three spark plugs. Capability of the SI-SRM to simulate engines with multiple spark plug (multiple ignitions) systems has been verified by comparison to the results from a three-dimensional (3D) computational fluid dynamics (CFD) model. Numerical simulations were carried for part load operating points with 12.5%, 20%, and 25% of EGR. At high load, the engine was operated at knock limit with 0%, and 20% of EGR and different inlet valve closure timing.

Mesh generation is frequently one of the most labor-intensive aspects of in-cylinder engine simulation with computational fluid dynamics (CFD). This expense makes parameter studies, such like engine geometry, valve timing or injection timing, a particularly challenging endeavor. The present paper introduces a CFD approach for the simulation of the in-cylinder processes of an internal combustion engine that minimizes user-required meshing effort and can handle almost unlimited boundary motion. The adaptation is fully automated and avoids the use of target meshes and global solution remapping. The intention of the approach is to use CFD for numerous parameter variations involving combustion system variabilities. Therefore, an open source base is chosen to avoid limitations of individual simulations due to a finite number of commercial licenses. The approach is used here for the simulation of a modern direct injection spark igniton (DISI) engine.