Search Results

Engine and vehicle manufacturers are facing increasing pressure from legislation to reduce vehicle emissions and deliver improved fuel economy. Significant reductions in carbon dioxide (CO2) emissions will need to be achieved to meet these requirements whilst also satisfying the more stringent forthcoming emissions regulations. This focus on techniques to reduce the tailpipe CO2, whilst also being able to operate over the whole map without the use of fuel enrichment for component protection, is increasing the interest in novel combustion technologies. The pre-chamber-based Jet Ignition concept produces high energy jets of partially combusted species that induce ignition in the main combustion chamber to enable rapid and stable combustion. The present study focusses on the potential of passive jet-ignition to enable increased output whilst maintaining stoichiometric operation through reduce knock sensitivity.

The challenges of ever increasing combustion engine complexity coupled with the introduction of new and ever more stringent emissions regulations place a unique strain on the time available during the base engine hardware development and calibration phase of the product development cycle. Considering state of the art gasoline engine architecture (dual variable valve timing, direct injection with turbocharger) it is common to have at least 12 degrees of freedom as system inputs. The understanding of interactions and inter-dependencies of these inputs is therefore key in optimising the performance of the engine. MAHLE Powertrain has developed a process using a global Design of Experiment (DoE) technique based on Gaussian processes that can be used to accurately model and optimise many aspects of an engine’s performance.

To improve the speed and accuracy of engine testing, the spark (gasoline)/injection (diesel) timing can be optimized based on the location of the 50% mass fraction burn point (α50) rather than the traditional approach of "sweeping" timing to find the most efficient point. Results from both gasoline and diesel engines show that setting α50 to around 8° ATDC gives optimum efficiency for most circumstances. An exception is the case of highly unstable combustion, where the misfire rate may also be strongly dependent on timing. For diesel engines this method is effective in finding the timing for best efficiency but in practice the chosen injection timing may be driven more by the need to optimize emissions. This technique has been implemented by incorporating a burn angle controller into the MAHLE Flexible ECU (MFE), a powerful and highly adaptable engine controller.

The US is generally considered as the most critical market for emissions and On Board Diagnostics (OBD). Effective calibration of OBD monitors to meet legal and robustness requirements, whilst simultaneously achieving the In Use Monitor Performance Ratio (IUMPR) targets, requires an understanding of real world driving behavior. Failure to achieve the legal minimum fleet average IUMPR could result in a product recall in the US. The planned implementation of IUMPR into Europe for EUV+ makes the understanding of customer drive patterns in the US and EU even more critical. This paper outlines the development of a drive style analysis toolset that defines key metrics, which enable US and EU fleet vehicle drive data to be categorized and compared. The toolset objectively quantifies driving behavior into drive type and drive style. Drive type is simply the recognition of US and EU road infrastructure.