Continental celebrates production of 40 million piezo injectors for injection systems

- High-tech injectors have been produced at the Limbach-Oberfrohna/Stollberg site in Saxony in Germany for ten years
- Piezo technology creates the conditions for reducing consumption and emissions

Regensburg/Limbach-Oberfrohna. Ten years on from the start of serial production, the international automotive supplier Continental is producing its 40-millionth piezo injector at its Limbach-Oberfrohna/Stollberg site in the German state of Saxony. The injection nozzles are fitted in the engines of passenger cars and commercial vehicles worldwide. “With this ultramodern injection technology we have created the technological conditions for the production of high-performance yet economical diesel and petrol engines which meet even the strictest environmental standards,” comments José Avila, member of the the Continental AG Executive Board and Head of the Powertrain Division.

Three years of preparation before start of production

Around 1,300 people are currently employed in the production of the injectors in Limbach-Oberfrohna/Stollberg. The injectors, which inject diesel into the cylinders at a pressure of around 2,000 bar, are assembled under clean-room conditions. In 2000, piezo technology revolutionized the common rail injection systems used in diesel engines. In this technology, the nozzle in the injector is controlled not by an electromagnet but by a piezo actuator consisting of more than 300 small, wafer-thin ceramic plates arranged one above another. A switching voltage causes the piezo actuator to expand, which in turn opens the nozzle’s injection holes within milliseconds. These very short response times make it possible for the fuel to be apportioned accurately and repeatedly between up to seven injections per combustion cycle. The result is a highly efficient combustion process because the apportionment of fuel as accurately as possible to the respective operating situation is the principle underlying good thermodynamic engine efficiency. In this respect, piezo technology will help to ensure that the stricter threshold limit values for nitrogen oxides and soot particles under the Euro 6 standard – which will be in  force from 2014 – will be complied with, and will also reduce CO2 emissions by a further three per cent compared with conventional diesel direct injection technology. In addition, piezo common rail injection (PCR) engines offer better performance, yet they are both more economical and quieter.

The technology was first developed in the mid-1990s, with the start of PCR production at the Limbach-Oberfrohna site announced in the year 2000 following a three-year lead time. Dr. Joachim Zirbs, plant manager at the Limbach-Oberfrohna and Stollberg operational facilities where production began in 2004, recalls the first decade: “It was ten years during which hurdles were overcome and successes achieved.” The PCR technology – for which Siemens received the Innovation Award 2004 conferred by the President of Germany – developed into a best seller: “While it was a further two years before the first million injectors were produced, around ten million were produced between 2007 and 2009. This year will see us deliver the 40-millionth injector,” says Zirbs.

Petrol versions are also more economical thanks to piezo technology

Piezo injection technology is now used not only in diesel engines, but also in their petrol counterparts. In 2006, the pioneering piezo technology was launched as a particularly economical option for direct injection in high-volume, layer-charged petrol engines. Piezo petrol injectors extend the layer charge range of such engines compared with solenoid valve injectors courtesy of their constant streaming and large volume spread. This can reduce consumption and CO2 emissions by as much as 20 per cent compared with conventional multi-point injection. In addition to perfected multi-point injection technology, the market will be dominated in future by direct injection technology, which will make petrol engines more economical. Continental is one of the leading providers of modern direct injection technology – not only for conventional motor fuel, but also for alternative fuels such as natural gas, liquefied gas and ethanol.

On top of further development of the current generation of injectors, Continental is looking to a new injector concept: piezo injectors with direct drive. Direct drive enables the nozzle to be controlled even more quickly and with greater precision without a hydraulic ratio. From the engine manufacturer’s perspective, this affords numerous advantages in terms of the particularly challenging applications in diesel engines. Moreover, for the first time, the injection rate of individual injections can be made flexible – a perfect enhancement to the multiple injection process already in established use in modern common rail diesel engines. The piezo actuator acts at the same time as a sensor, as it reports the exact position of the nozzle to the electronic control unit. This, in turn, means that for the first time a closed volume control loop is created. Minor scatterings and deviations – co-called drift processes in the course of a vehicle’s life – can be detected and corrected independently within the system. In addition, the new injector makes it possible to increase the injection pressure to over 2,000 bar.

Simone Geldhäuser
External Communications
Powertrain Division
Siemensstr. 12
93055 Regensburg
Phone: +49 941 790-61302
Fax: +49 941 790-99 61302