For the American market, diesel engines are in creasingly becoming a real alternative to the dominance of the gasoline engine. The main advantages of the diesel engine are its much lower fuel consumption and, as a result, its greater driving range. However, for the engine to met what is currently the strictest emissions standard (Tier2 BINS), there had to be significant reductions in particulate mater and NOx emissions.
Thanks to a comprehensive optimization of the combustion process, the 2.0-litre TDI engine installed in the VW jetta in the USA complies with the stringent emissions legislation with thee aid of technologies from Borg Warner, while at the same time offering a significantly higher power output than the predecessor model. The exhaust gas turbocharger of the EUS basic engine was optimized for use in combination with low pressure exhaust gas recirculation.
To offer protection against high temperatures and acidic exhaust components, Borg Warner developed a special coating for the compressor housing and the compressor wheel of the VTG turbocharger. With its PSG Pressure Sensor Glow Plug, BERU is supplying one of the key technologies for higher engine output and improved efficiency due to the precise measurement of the cylinder pressure, thus helping to reduce emissions by optimizing the combustion process. The six-speed direct shift transmission ( DSG) with wet multi-plate clutches from Borg Warner allows super quick gearshifts with no interruption in torque to the drive shaft-without any loss of engine output and with no fuel consumption penalties.
The most effective way of reducing the formation of NOx inside the cylinder is to provide the highest possible exhaust gas recirculation rates. The se can be achieved by low-pressure exhaust gas recirculation, which allows a further reduction in nitrogen oxides. In the low pressure EGR system, the exhaust gas is tapped from the exhaust line downstream of the particulate filter and reintroduced upstream of the turbocharger compressor.
Until now, this has been impossible due to the high temperatures and the residues in the exhaust gas. In further developing the turbocharger with variable turbine geometry (VTG), Borg Warner was able to draw on its many years of experience, enabling it to optimize the turbocharger compressor in such a way that it can withstand even the highest thermal loads and offer outstanding reliability. The result was a new milled and specially coated compressor wheel and a nano-coated compressor housing, both of which are now able to withstand the temperatures of the recirculated exhaust gas and are not damaged by residues.
A further key component of the clean diesel effect in the new VW diesel engine is the PSG pressure sensor glow plug from Beru, which allows the combustion processes in the engine tube controlled extremely recisely, thus ensuring that fewer pollutants are produced during combustion. The glow plug consists of an especially robust steel heating rod and a piezo resistive sensor. It measures the pressure in the combustion chamber by selecting the cylinder and continuously sends a signal to the engine management system. The ECU then uses this measured signal to calculate the cylinder pressure features required. The main advantage of this precise measurement is that higher peak pressures can be implemented, thereby improving engine output and efficiency. The cylinder-selective optimization of the combustion process also compensates for inaccuracies in fuel metering, component tolerances and different operating conditions individually in each cylinder. The Pressure Sensor Glow Plug, which is manufactured using sophisticated process technology at the company's headquarters in Ludwig burg, Germany, will have other series-production launches on the North American and European markets.
The six-speed direct-shift gearbox is essentially two identical gearboxes in
one. One clutch controls the odd gears plus reverse, while the other operates
the even gears. As soon as the ideal shift point is reached, the clutch for the
engaged gear opens and the clutch for the next selected gear closes
simultaneously. The transfer of power from the first clutch to the second is
absolutely smooth, without any interruption in torque to the drive shaft. In
this way, Dual Tronic technology eliminates the uncomfortable torque-interrupt
feeling that occurs when a manual or automated manual transmission shifts gears.
When the vehicle is pulling away and during gear shifts, the clutch system is
actively cooled via an oil flow.