Combining the innovative assistance drive with a 1.8 litre BMW four-cylinder engine on the test rig reduced consumption by up to 15% and generated 10 kW more power. At the same time, up to 20 Nm more torque was measured. This increased power and efficiency comes for nothing, as the energy is derived exclusively from the waste heat present in the exhaust gases and cooling water and doesn't cost you a single drop of fuel.
The research project therefore meets all the conditions espoused by the philosophy of BMW Efficient Dynamics - lower emissions and consumption combined with more dynamic driving and performance.
Named the Turbosteamer, the project is based on the principle of the steam engine: fluid is heated to form steam in two circuits and this is used to power the engine. The primary energy supplier is the high-temperature circuit which uses exhaust heat from the internal combustion engine as an energy source via heat exchangers.
More than 80% of the heat energy contained in the exhaust gases is recycled using this technology. The steam is then conducted directly into an expansion unit linked to the crankshaft of the internal combustion engine. Most of the remaining residual heat is absorbed by the cooling circuit of the engine, which acts as the second energy supply for the Turbosteamer.
The innovative assistance drive verifiably increases the efficiency of the combined drive system by up to 15%. "The Turbosteamer reinforces our confidence that the internal combustion engine is undoubtedly a technology fit for the future," comments Professor Burkhard Göschel, Member of the Board of Management responsible for development and purchasing at BMW AG.
The development of the assistance drive has reached the phase involving comprehensive tests on the test rig. The components for this drive have been designed so that they are capable of being installed in existing model series.
Tests have been carried out on a number of sample packages to ensure that a car such as the BMW 3 Series provides adequate space. The engine compartment of a four-cylinder model offers enough space to allow the expansion units to be accommodated.
Ongoing development of the concept is focusing initially on making the components simpler and smaller. The long-term development goal is to have a system capable of volume production within ten years.
BMW Group Research and Engineering has demonstrated the medium-term perspectives of the project BMW Efficient Dynamics. "This project resolves the apparent contradiction between consumption and emission reductions on the one hand and performance and agility on the other," is how Professor Burkhard Göschel summarizes the core concept of the programme.
The BMW Group is committed to the principle that a reduction in consumption amounting to a few percentage points over the entire model range exerts higher overall effects on the general population than lots of percentage points for a niche model.
BMW is therefore focusing on making the latest technologies for reduced consumption accessible to as many people as possible.