The triumph of the diesel engine

Drivers see how economical a diesel engine is every time they need to refuel at a gas station. But the triumph of the diesel engine is also due to innovations from Bosch which make sure that driving the new diesel generation is getting more enjoyable all the time. Today, fuel economy and driving dynamism are no longer in conflict.

When the first diesel engine was taken into operation in 1897, Rudolf Diesel had achieved his objective: to develop an engine that would be more economical and efficient than all motor types known at the time. The steam engine, for example, used only 10 per cent of the energy applied. But the diesel engine - which was then a 4.5 ton prototype for stationary machines - already used 30 per cent. Otto spark ignition engines only reached that value by the early 1990s.

The first utility vehicles with diesel engines came to market in the golden 1920s. Shipping and aviation were also interested in the new development. Diesel engines provided the propulsion for the "Zeppelin" airship, for example.

The first diesel passenger car was the Mercedes 260 D model built in 1936. But diesel engines remained rare in passenger cars. Though economical and durable, the diesel engine was still regarded as noisy, slow and graceless in the 1970s.

The success story of the diesel engine only really began with the introduction of the first direct injection engine for Audi cars. Now Diesel was not only economical, but also began to display unexpected driving dynamism. And emissions were cut continuously.

In 2003, 44 per cent of all newly registered cars in Europe were diesels - some three per cent more than the year before. And the success story continues: A diesel share of some 50 per cent of new registrations is expected in 2005.

Clean driving pleasure has triumphed. Diesel is now established in all vehicle categories - from small cars to luxury models.

Only Bosch injection systems have made diesel engines what they are today: economical, dynamic, clean and quiet. They are the key to the success and growing popularity of diesel engines.

Different systems are used by different manufacturers, but they were all created by Bosch and are equivalent in terms of quality and effectiveness: the "Unit Injector System" (UIS) and the Common Rail System" (CRS).

In both systems, the fuel is injected into the cylinders under very high pressure. The injection process itself is controlled electronically, so that the ideal fuel volume is always injected at exactly the right moment. And that ensures maximum performance at minimum consumption and low emission levels.

The Unit Injector System (UIS)

In the Unit Injector System (UIS), each engine cylinder has a unit injector that generates a pressure of up to 2050 bar in passenger cars.The injection nozzle is integrated into the injector and projects into the combustion chamber. Unit Injector Systems permit precise injection at variable injection durations. This injection process and the high pressure applied result in excellent combustion. That ensures higher performance, lower fuel consumption and reduced exhaust gas and noise emis-sions.

The Common Rail System (CRS)

In the Common Rail System, the fuel for all cylinders is stored in a common rail under high pressure of up to 1600 bar. Electronically controlled high-performance magnetic valves control the injection time and injection duration for every cylinder. Functional separation of pressure generation and injection thereby affords more scope for improving the combustion process.

Third generation Common Rail Systems use especially fast piezo inline injectors that cut emissions by another twenty and fuel consumption by three per cent, while also reducing engine noise.

Perfect control

Electronic Diesel Control (EDC) from Bosch provides optimal control of the diesel injection process in every operating moment. The system analyzes the information provided by the sensors in the engine to calculate the best injection process.

Still cutting emissions

Additional exhaust gas treatment processes are used to cut emissions even further.

Diesel particle filters with an additive or catalytic coating ensure that the engine already meets or even undercuts the very demanding emissions regulations of the future today.

Bosch technology wins

Efficient high-precision diesel technology from Bosch is now the standard in modern diesel engines.

Bosch expects to produce seven million high-pressure (Common Rail and Unit Injector) injection systems in 2004. That makes Bosch the biggest and technologically most advanced manufacturer of such systems worldwide.

Dynamic research and many innovations from Bosch will continue to support the triumph of the diesel engine as a clean and efficient alternative.