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Automotive Industry

Pressure is on SI injection: Siemens views future for direct injection systems for gasoline engines

Automotive Industries, June, 2004 by Roberto Chellini

Through various companies that now are a part of Siemens VDO Automotive, based in Regensburg, Germany, Siemens has been involved in the production of fuel components for gasoline and diesel engines since 1971 when the Newport News, Va., facility began operation doing primarily diesel oriented work.

A further boost to this activity in the U.S. took place in 1988 with the acquisition of Bendix Electronics. One year later, in Europe, the San Piero a Grado engineering and production center began operation a few miles from Pisa, Italy.

The Italian operation was initially comprised of specialists from Spica of Leghorn, a company owned by Alfa Romeo. It was spun off when Aria Romeo was purchased by Fiat.

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Under Siemens the San Piero activities developed to the point where a new production unit was added in 1996 a few miles away in Fauglia, is also in the Pisa area.

The two groups are working in close cooperation, with the R&D concentrated in San Piero, and also some production--such as the Deka II injectors. Mass production, however, is based in Fauglia where the Deka VII injector is produced at a rate of 60,000 pieces per day (for 15,000 4-cylinder engines/day) giving to the company a close to 30 percent European market share. Production of the Deka VII began in November, 2003.

To serve the American market, the Deka VII injector went into production just this year at Newport News. By 2006, Siemens VDO Automotive hopes to increase worldwide manufacturing to 16 million injectors per year, more than half of which will be produced in Italy.

The Deka VII injector for is used for multipoint port injection systems, which seem to be the state-of-the-art for today's automotive gasoline engines.

Thanks to its flexibility, the Deka VII can be located on an engine in the position desired by the engine designer. No need to build the engine around the injector.

This injector family is available with different overall lengths (long, standard and short) and several valve body tip lengths, standard, extended (10 mm) and extra-extended (15 mm). The configuration of the electrical connector is also tailored to the specific application.

The design of this injector combines enhanced performance and reliability with best price. Such a combination was achieved by streamlining the manufacturing process.

The number of components has been reduced from 28 to 19 (a 30 percent savings) and assembly operations from 120 to 50 (a savings of 60 percent). The manufacturing process has been simplified by reducing the machined components by half, eliminating internal O-rings, increasing the use of laser welding and standardizing the coil sub-assembly-regardless of injector length or electrical connector type.

The entire assembly process takes place in clean rooms to minimize dust contamination of metal--to-metal seals.

The Deka VII injector operates at a pressure of 3 to 5 bar (1 bar = 14.5 psi) and ensures an average droplet size of less than 70 microns. When combined with the right engine control unit (ECU) they are suited to meet the next generation of emission standards (Euro V).

Siemens VDO reported that in fiscal year 2003 they had a market share of nearly 17 percent worldwide. With the introduction of the Deka VII, it expects to become the market leader by 2008 with over 25 percent market share world wide--forecast at 190 million injectors.

Multipoint port injection is in its infancy

The R&D department of Regensburg and the Pisa team are developing injectors with medium (20 bar) and high pressure (200 bar) fuel pumps as well as more advanced electronic control units (ECU) for the gasoline fuel systems.

Back in 1909 Siemens VDO became the first European supplier of DI injectors for the homogeneous charged engines [or the Renault Megane and Laguna. In 2001, PSA purchased DI injectors for the stratified operating engines of the C5 and 406. Then in 2003, DaimlerChrysler went to DI injectors on the Mercedes DC C Class turbocharged stratified charge engine and Opel on the Signum homogeneous charged engine, both responding to Euro IV emission limits. Looking into the near future, Siemens says 2006 will see the first application of high pressure pumps and spray guided stratified engines. In 2007, homogeneous charged naturally aspirated and turbo engines will follow.

American, European and Asian emission legislation are imposing reduction in NOx, CO, HC and particulate emissions. Primary automobile associations (ACEA, JAMA, KAMA) are also committed to reducing fuel consumption thus lowering the CO2 emissions from 170 g/km in 2003 to 140 g/km in 2008.

According w Siemens VDO, the high pressure piezo direct fuel injection will provide engines ratings of over 80 hp/liter fuel savings on the order of 20 percent compared to conventional furl systems. At the same time, engine performance and torque characteristics will improve. That translates into more fun to drive.

The two main applications for future gasoline DI are for stratified combustion engines with spray guided combustion systems and homogeneous combustion engines in both the naturally aspirated and turbocharged versions.

Automotive Industry

Pressure is on SI injection: Siemens views future for direct injection systems for gasoline engines

Automotive Industries, June, 2004 by Roberto Chellini

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