Mercedes-Benz Unveils "DiesOtto" - The Future of The Gasoline Engine
Stuttgart August 10, 2007; The performance of a gasoline engine, the high torque and fuel economy of a state-of-the-art diesel together with extremely clean emissions: Mercedes-Benz has combined all the advantages of both engine types in its DiesOtto powertrain. The new technology package, which stands for the future of the gasoline engine, includes features such as direct gasoline injection, turbocharging and a variable compression. At the core of this innovation lies the controlled auto ignition, a highly efficient combustion process similar to that of a diesel. By way of another advantage, and in contrast to comparable developments, the Mercedes system requires no synthetic fuels but can be operated using conventional gasoline.
Optimising the internal combustion engine is one of
the milestones on the Mercedes-Benz roadmap for sustainable mobility.
BLUETEC has already made it possible for Mercedes engineers to make the
powerful and economical diesel as clean as the gasoline engine. In the US
this technology has already been available in the E-Class since 2006, and
it will also become available in Europe from the end of this year. The E
300 BLUETEC will be by far the cleanest diesel in its class, and will meet
the requirements of the EU5 exhaust emission standards in full.
"Our next goal will now be to make the gasoline
engine as economical as a diesel. All the preconditions for this are
provided by our DiesOtto concept, which incorporates the foremost strengths
of both the gasoline engine and diesel engine," says Prof. Dr. Herbert
Kohler, Head of Group Research & Advanced Engineering Vehicle and
Powertrain; Chief Environmental Officer of DaimlerChrysler.
The result of this " marriage " is a four-cylinder
unit with a displacement of just 1.8 litres, which combines the strengths
of the low-emission gasoline engine with the fuel economy of a diesel.
Despite its considerably reduced displacement – downsizing is one of
the major factors for achieving a lower fuel consumption – this
compact power unit delivers superior performance together with refinement
at the level of the luxury class. An output of 175 kW/238 hp and a maximum
torque of 400 newton metres are achieved together with the hybridisation a
fuel consumption of less than six litres of gasoline per 100 kilometres.
This figure by no means relates to a small or compact car, but to a vehicle
the size of the current S-Class, with the level of comfort and safety that
is typical of a Mercedes.
Mercedes-Benz DiesOtto – a further
development of the spark-ignition engine
" In line with the worldwide success of today's
diesel engine, vehicles equipped with gasoline engines will continue to
have a long-term attraction for many customers and in many markets.
Accordingly we are giving our attention to both engine types –
including a full hybrid option for diesel and gasoline vehicles, " says
Prof. Kohler. Mercedes-Benz is working on its DiesOtto concept with
corresponding emphasis. Its key technological features are as
follows:
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Downsizing with fewer cylinders and a smaller displacement
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Turbocharging for superior performance
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Direct gasoline injection as a further fuel economy measure
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Controlled auto ignition, a combustion process similar to that of a diesel
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Variable valve control
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A variable compression ratio leading to even better fuel economy and, depending on customer needs and the type of operation,
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A hybrid module with an integrated starter/generator, which makes the drive unit even more economical.
When starting and under full load, the fuel/air
mixture is ignited by a spark plug, as in a conventional spark-ignition
engine (homogeneous combustion). The controlled auto ignition to which the
DiesOtto automatically reverts within its working cycle occurs under
partial load conditions, i.e. at low and medium engine speeds.
The result is the very low nitrogen oxide emissions
of homogeneous combustion at reduced reaction temperatures. All further
emissions control in the DiesOtto engine is by means of a standard
three-way catalytic converter. A highly efficient engine management and
control system has also been realised to combine the individual sub-systems
into a drive concept.
The current prospects for the future of the internal
combustion engine reveal its great potential, and show that the new drive
concept is a feasible proposition in the mid-term. Some of the intermediate
solutions incorporated, e.g. direct gasoline injection, are already in
series production at Mercedes-Benz. Others will be gradually integrated
into series-production engines until the overall solution has been
realised.