Bosch Automotive A product history

36 | Supplement 2 | Journal of Bosch History
Left to right:
A look inside the engine
compartment of an Audi
100 TDI (1989). This
model was the first diesel
car in large-scale series
production to feature
high-pressure direct
injection. As a result, the
car reached a top speed
of 195 kph, with an average
fuel consumption of
6 liters per 100 km.
Common rail, the diesel
system most frequently
used today, was first
installed in the Alfa
Romeo 156 JTD (1997).
It achieved uniform injection
pressures of up to
1,350 bar. This technology
enabled multiple
injections.
A look inside the combustion
chamber of a modern
four-valve diesel engine
(2008)
in-line pumps from 1987. These ECU’s
optimized emissions, noise, power, and
consumption. Moreover, they enabled
injection systems to be linked with other
electronic systems, such as the traction
control system (TCS), which stops the
wheels spinning by intervening in engine
management or in the brake control system.
Bosch used this success to further extend
its competence in both systems – in-line
and distributor pumps. In the case of distributor
pumps, collaboration with Audi
resulted in the first systems capable of
injecting fuel directly into the combustion
chamber at a pressure of almost 1,000 bar.
In combination with turbo-charging, this
made the diesel engines built from 1989
on more economical. The engines also
produced less exhaust gas and helped
vehicles achieve remarkable driving performance.
High-pressure fuel injection
marked the diesel engine’s breakthrough
in Europe.
Common rail and multiple injection
The high proportion of passenger cars
equipped with diesel engines – around
30 percent in western Europe in 2000 –
came about as a result of crucial further
developments in high-pressure dieselinjection
technology. Bosch offered a
number of variants, including the radialpiston
distributor pump (1996), the common-rail
system (1997), and unit-injector
technology (1998). They all achieved injection
pressures of up to around 1,500 bar
(and have even exceeded 2,200 bar in
subsequent generations), and were thus
characterized by both economy and performance.
Eventually, the common-rail system won
through. The Fiat subsidiary Elasis was
responsible for the basic idea, but Bosch
refined the system to make it ready for
series production. This system offered
crucial advantages over the other two.
Although the peak pressures of the common-rail
system were lower than those
of the unit-injector system (which could
1986 1989 1993 1995 1996 1997
EDC electronic diesel
control system
VP 37 axial-piston
distributor pump
for direct injection
in passenger-car
engines
Control-sleeve fuel
injection pump
Unit-pump system
(UPS)
VP 44 radial-piston
distributor pump
Common-rail system
for passenger-car
engines