Bosch makes double diesel breakthrough

9 October 2001: German electronics and electrical company Bosch is behind two new developments that will ensure diesel continues to be a popular choice for years to come.

Firstly, Bosch has made the second generation of Common Rail high pressure direct diesel injection system ready for production. This further development of the well proven system will make diesel engines even more economic, clean and quiet. In the second generation of Common Rail, a new pump, this time controlled from the intake side, generates pressure more effectively, helping increase pressure in the rail from the current level of around 1300 bar (17,400 psi) to 1600 bar (over 23,000 psi).

In addition, a more efficient control unit shortens the interval between pre-injection and main injection and the injectors themselves are manufactured to finer tolerances.

These improvements combine to create a finer, more accurately measured and timed mixture spray in the combustion chamber, significantly reducing unburned fuel, giving second generation Common Rail the potential to meet future emission guidelines such as Euro IV. Such has been the broad appeal of common rail that, since Bosch started production of the first generation of Common Rail four years ago, more than 5 million systems have come off the company’s lines.

Meanwhile, Bosch has also helped Volkswagen develop a new 1.9 litre Golf TDI diesel, Europe’s first compact family car to satisfy Euro IV emissions legislation, which is so strict on particulates and other emissions it does not come into force until 2005.

This significant step forward is largely thanks to the Golf’s Bosch ‘Unit Injector’ diesel injection system which, coupled with VW’s 1.9 litre four-cylinder diesel engine, makes the new Golf so fuel-efficient, it emits some 40 per cent less carbon dioxide than today’s average.

The secret of the Bosch Unit Injector System is extremely high injection pressure. At more than 2000 bar (29,000 psi) at the injector nozzle, it operates at higher pressures than its direct injection sister technology, common rail.

At the same time, the system’s highly precise ‘solenoid valve control’ guarantees an exact measure of injected fuel and accurately timed injection. As well as helping optimise fuel efficiency, this brings other benefits such as reduced combustion noise.