Germany’s Bosch designs and develops injection systems which allow vehicles to run on diesel, gasoline, gasoline and natural gas or gasoline and ethanol, either alternatively or as a mixture. Matthew Beecham talked to Dr Steffen Berns, executive vice president Engineering Gasoline Systems, Bosch and Rolf Leonhard, executive vice president, Engineering Diesel Systems, Bosch.
just-auto: What impact will the stricter emission rules have on your direct injection gasoline (DIG) system business?
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Dr Steffen Berns: The new generation of the gasoline direct injection system makes combustion more efficient and increases overall engine efficiency. With DIG it is possible to reduce fuel consumption and CO2 emission by about 15% and to meet current and future emission regulations. That’s the reason why car manufacturers are more and more interested in using DIG. For Bosch this opens up significant market potential. Since the start of series production, Bosch has already won over a large number of new customers for the current gasoline direct injection system. This year [2007] Bosch will deliver approximately 900,000 gasoline direct injection systems. And the production numbers are continuously rising. By 2010 this figure will already be more than two million. And while only half of our unit sales are currently accounted for by second-generation GDI, this figure will be nearly 100% three years from now.
just-auto: What are the advantages of DIG that are attracting vehicle manufacturers?
Dr Steffen Berns: The second-generation DI-Motronic contributes to improved mixture preparation and provides for considerably reduced emissions of carbon dioxide (CO2), hydrocarbons [HC] and nitrous oxides [NOx]. Using optimized cold-starting combustion processes which provide for faster heat-up of the catalytic converter, emission values are even below the strictest SULEV (super ultra low emission vehicle) limits in the US. And the DI-Motronic even has the potential to fulfil future emission regulations. At the same time our second generation of gasoline direct injection system provides the basis for a whole series of new approaches to reduce consumption and CO2: the spray-guided combustion process, control of intake and exhaust valves, and above all turbocharging, which allows engines to be smaller. This ‘downsizing’ has now been adapted in several series-manufactured engines – and further projects are set to follow.
just-auto: Are there synergies between DIG and diesel direct injection? In the injectors, pumps, sensing, control software?
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By GlobalDataDr Steffen Berns: Regarding injectors and pumps there are nearly no synergies, as pressure for DIG is up to 200 bar, which can not be compared with the pressure required by diesel-injection systems, of up-to 2000 bar. In sensors and control units there are many commonalities, e.g. in architecture and basis software, but engine-specific differences remain.
just-auto: One of the major challenges with diesel common rail has been high precision manufacturing. Now that these are overcome, are the lessons learnt going to be useful to Bosch’s DIG programme?
Dr Steffen Berns: Although both systems are not comparable due to different pressure requirements, we have the same high quality standards regarding high precision manufacturing for diesel and gasoline systems.
just-auto: How does the cost of DIG compare with the cost of alternative technologies such as variable valvetrains?
Dr Steffen Berns: That depends on the Valvetrain System. DIG works best, not instead of, but in combination with simple Valvetrain actuation systems, e.g. double cam-phasing.
just-auto: Are we likely to see more applications of cheaper, ‘homogeneous’ DIG technology in smaller engines?
Dr Steffen Berns: Probably, yes. Because ‘downsizing’ will be one important way to reduce fuel consumption and CO2-emissions.
just-auto: Now that European fuel quality has improved (lower sulphur) are we going to see more rapid uptake of DIG?
Dr Steffen Berns: Low sulphur fuels have been launched in W-EU in the end of the 1990s, therefore this was no barrier for the introduction of DIG.
just-auto: How does the adoption of DIG affect the aftertreatment requirement?
Dr Steffen Berns: For homogeneous combustion, three way catalysts are sufficient to even reach tight emission limits. Faster heat-up of the catalytic converter through optimized cold-starting combustion processes offers the potential to slightly simplify the three way cat. For lean burn concepts Denoxation will be necessary, state-of-the art is the use of a Lean NOx Trap.
just-auto: Going forward, what are your predictions for the DIG market in North America by 2010?
Dr Steffen Berns: At a recent event, we predicted a share of about 14% of passenger cars and light commercial vehicles in North America to be equipped with DIG by 2015.
just-auto: Is piezo actually needed to meet Euro 5 emission rules? Could it be achieved with existing technology, additional filters and adjustments to engine management systems?
Rolf Leonhard: It is entirely feasible to design diesel engines to meet future emissions legislation such as the Euro 5 standard – which is scheduled to come into force in 2009 – using technology that is available today. Hence the Euro 5 standard could be achieved with solenoid valve or piezo injectors in combination with a diesel particulate filter.
just-auto: Are tougher emission rules slowly killing the diesel? Will the addition of particulate filters and other after-treatment devices make the price premium for diesel too high?
Rolf Leonhard: The introduction of particulate filters in Europe had no negative effect on the diesel share. And with improved fuel injection, air management and DeNOx aftertreatment, diesel meets even the US emission standards: which means a NOx reduction of 85% compared to EU4. Although diesel will have a premium price, we expect a considerable increase in diesel share in the US.
See also: RESEARCH ANALYSIS: A review of gasoline direct injection systems
