Helmut Theissl

Neuer, ganzheitlicher Ansatz zur Antriebsstrang- / Fahrzeug-Simulation für frühzeitige Konzeptentscheidungen trotz ansteigender Parametervielfalt

Die aufgrund der gesetzlichen Anforderungen hinsichtlich Emissionsverhalten und der erwarteten CO2 – Limitierung stetig steigende Systemkomplexitat im Antriebstrang erfordert eine komponentenubergreifende Optimierung des Gesamtsystems. Daruber hinaus spielen bei der Auswahl des Gesamtsystems Kundenakzeptanz, Fahrkomfort und Fahrverhalten eine immer wichtigere Rolle. Die detaillierte Berucksichtigung der Interaktionen zwischen Verbrennungsmotor inklusive Abgasnachbehandlung, Antriebstrang, Motor- und Getriebesteuerung bei unterschiedlichen Fahrzustanden und Umgebungsbedingungen ist bei der Konzeptdefinition unumganglich. Um dies trotz hoher Komplexitat, kostengunstig und in einer fruhen Entwicklungsphase zu ermoglichen, ist es notig, ein virtuelles Abbild des Antriebstranges in der Konzeptphase bereitzustellen.

Impact of CO2 and ultra-low NOx legislation on commercial vehicle base engine

Upcoming most stringent legislations for greenhouse gas emissions (GHG) as well as for criteria pollutant emissions will confront the commercial vehicle industry with new challenges. The recently concluded 2nd phase of GHG regulation in North America demands a GHG reduction of up to 27% of for model year 2027 (MY2027) depending on the individual application. This regulation includes a dedicated reduction of CO2 emissions from engines, e.g. in the magnitude of 5% for heavy heavy-duty tractor applications. At the same time, the California Air Resources Board (CARB) announced plans to introduce a 90% reduction of nitrogen oxide (NOx) emissions compared to current levels (EPA10). In addition, EPA announced plans to lower the nationwide NOx standard. In Europe, a reduction of NOx emission limits is a possible development for the future. A mandatory CO2 declaration for heavy-duty vehicles will be in force in the EU from 2018. Based on the outcome of the monitoring, CO2 limits could follow at a later stage.

Improving commercial vehicle emissions and fuel economy with engine temperature management using variable valve actuation

Commercial vehicles require continual improvements in greenhouse gas emissions to meet upcoming emission regulations and fleet fuel economy needs. Challenges for future emission standards require technologies for engine exhaust temperature management to deal with low engine load operation for optimal aftertreatment performance. The proposed ultra-low NOx emission standards of 10% of today’s US level (0.2 g/hp-hr) is challenging and requires significant temperature management strategies including heat-up strategies during the cold part of the emission cycle. Heavy duty commercial vehicle applications requires a heat source on the order of 30 kW to achieve aftertreatment temperatures for sufficient NOx reduction. There are technologies that can provide such high heat loads in a short period of time. A diesel exhaust burner is an option for fast heat-up at the expense of fuel economy. Variable valve actuation (VVA) solutions are effective for aftertreatment temperature management including early exhaust valve opening, intake valve closing modulation and cylinder deactivation. Further steps of emission legislation focus on in-service operation, including NOx emission reduction during low load operation. Such low engine load operation may result in exhaust temperatures between 100°C and 250°C, where NOx aftertreatment systems are not effective. Thus, technologies are needed to raise the exhaust temperature under such conditions. The use of VVA to vary the air-excess ratio in the cylinder is a fuel efficient method to increase exhaust temperature under low load conditions. Methods of intake air throttling are capable measures such as cylinder deactivation and Miller cycle. Cylinder deactivation during low load engine operation shows a marked increase in exhaust temperature by approximately 100°C which moves aftertreatment systems to a more optimal region, typically significantly above 250°C while also offering fuel economy benefits. The addition of a high efficiency boosting system enables Miller cycle operation to improve fuel economy. Thus, the use of VVA is a leading technology combining the future requirements to simultaneously reduce NOx and fuel consumption. This paper will show the benefits of variable exhaust valve opening, intake valve closing modulation with and without boosting, and cylinder deactivation for meeting future emission regulations and fuel economy needs. Finally, solutions combining VVA and engine braking are provided.

Neue Technologien für Verbrennung – Ladungswechsel – Mechanik – Einspritzung

The development of commercial vehicle on-road applications, such as long haul trucks or busses, is driven by the optimization of the total cost of ownership (TCO) which relates the initial product cost with operating cost. Long haul truck applications have high annual mileage at high engine loads. Thus the operating costs dominate the total cost of ownership. Consequently lowest possible fuel consumption is one of the major drivers for long haul truck applications all over the world.