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V12 power unit developing dynamic performance BMW style from hydrogen.
Under current conditions, dual-mode drive is the only really practical solution in giving hydrogen the breakthrough it deserves. The combustion engine featured in BMW Hydrogen 7 is perfectly suited for arousing widespread acceptance of this new technology.
Particularly in comparison with the fuel cell, the power unit featured by BMW develops much more engine power. The V12 driving the BMW Hydrogen 7 combines dynamic performance, superior comfort and enhanced safety in a manner typical of all BMW automobiles, regardless of the type of fuel or engine technology.
Displacing 6.0 litres, the power unit develops a maximum output of 191 kW/260 hp. Maximum torque, in turn, is 390 Newton-metres/287 lb-ft at an engine speed of 4,300 rpm. This enables the BMW Hydrogen 7 to accelerate from a standstill to 100 km/h in 9.5 seconds and gives the car an electronically limited top speed of 230 km/h or 143 mph, both on hydrogen and gasoline.
This alternative energy technology brand-new in a series production car is absolutely equal to the gasoline engine with its history of more than 100 years. So the conclusion is clear: A hydrogen car is also able to offer power, performance, driving dynamics, motoring refinement and, as a result, sheer driving pleasure of the supreme standard expected of a genuine BMW.
The twelve-cylinder power unit carried over from the BMW 760i as the basis for the engine in BMW Hydrogen 7 offers further benefits highly relevant to the customer. Indeed, the engine comes with all the qualities gained by BMW from decades of experience in the production of particularly powerful and efficient engines, which also means the supreme reliability so typical of a BMW.
Compared with a fuel cell hardly offering the same kind of power,
the combustion engine is far lighter right from the start. The use of a combustion engine also means lower cost of production, with the BMW Hydrogen 7 not only having gone through the BMW Group’s entire process of series development, but also being fully integrated in the conventional production process as a hydrogen car: The new hydrogen model is built at BMW’s Dingolfing Plant parallel to the other models in the BMW 7, 6 and 5 Series, with the drive unit in BMW Hydrogen 7 coming like all BMW twelve-cylinders from the Company’s engine production plant in Munich.
Direct gasoline injection and hydrogen intake manifold supply.
The hydrogen combustion engine is based on the gasoline power unit featured in the BMW 760i, offering the most advanced and sophisticated highlights in technology, including fully variable VALVETRONIC valve management and variable double-VANOS camshaft control. Further confirmation of the engineering skills of BMW’s engine development specialists is borne out by the modifications required for dual-mode
drive, with fuel being supplied in the gasoline mode through direct injection and with a hydrogen supply pipe integrated in the engine’s intake system.
The key technology is the injection valves required to provide the appropriate fuel/air mixture, blowing exactly the right amount of hydrogen gas into the intake air within fractions of a second.
Burning up to ten times faster than conventional fuel, hydrogen offers a higher level of efficiency. To make use of this potential in full, the V12 power unit
in BMW Hydrogen 7 requires particularly flexible engine management ensured ideally by VALVETRONIC and double-VANOS, where both the gas cycle
and injection rhythm can be perfectly tailored to the specific features and characteristics of the hydrogen/air mixture.
Minimization of nitric oxides.
Under full load the power unit in BMW Hydrogen 7 runs under stochiometric conditions, meaning a complete balance of oxygen and hydrogen (lambda = 1). This mixture ratio also provides the highest level of performance and output
on low emissions in the hydrogen mode.
Unlike fossil fuels, the combustion of hydrogen generates neither hydrocarbons (HC) nor carbon monoxide (CO). If at all, minute traces of HC, CO, and CO2 emissions will be generated by the combustion of lubricant and by rinsing the activated carbon filter while running in the hydrogen mode.
The only relevant factor, therefore, is the emission of nitric oxides (NOX) generated above all at particularly high combustion temperatures.
Highly flexible combustion management, however, allows an operating strategy able to largely control the formation of NOX. In practice,
this means that the engine is run under part load with a high share of
oxygen and, accordingly, a high lambda factor of more than 2.
In this case the temperatures in the combustion process are relatively low, keeping NOX emissions to an absolute minimum.
Such a lean burn mode can be maintained throughout a particularly wide range of operation in the engine control map. And since hydrogen offers particularly broad ignition limits and burns at a fast rate, only a small amount of fuel is required in the mixture to generate a high level of efficiency.
To boost engine output, the share of fuel in the fuel/air mixture is also increased in the hydrogen mode. This, in turn, means an increase in combustion temperatures under higher load. With the fuel/air mixture range creating the maximum amount of nitric oxide lying between lambda = 1
and lambda = 2, the engine management of the BMW Hydrogen 7 cancels out this operating range with its negative effects on emission management without any reduction or change in torque.
NOX emissions are almost completely avoided under full load with a lambda factor of 1. To convert the minimum amounts of NOX still remaining under these operating conditions, all the engine needs is a regular three-way catalyst system, the specific composition of exhaust gases in a hydrogen combustion engine running under stochiometric conditions (lambda = 1) promoting the conversion of nitric oxides possibly contained in the exhaust emissions by way of the three-way catalyst. In practice, therefore, the drive unit featured in
BMW Hydrogen 7 offers the same dynamic performance in the hydrogen mode as when running on gasoline, while emitting virtually nothing but vapor
in the process.
Development in record time: BMW H2R.
The power, performance and the reliability of the engine concept were all impressively proven during the development phase, with the BMW H2R World Speed Record Hydrogen Car showcasing the exceptional potential of this technology. In September 2004, when raced on the high speed track in the French town of Miramas, the BMW H2R broke no less than nine international records for hydrogen drive cars with a combustion engine. The car, powered by a 6.0-litre V12 hydrogen combustion engine, achieved a top speed of more than 300 km/h or 186 mph, setting up new records inter alia for the distance of one kilometre with a flying start and the quarter-mile with a standing start. Acceleration from 0–100 km/h came in just 6 seconds.
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