BMW ActiveHybrid technology: How it works

 

 

 

 

Hybrid technology may be a fine technical achievement, but makes more sense for countries with no diesel infrastructure. The development of such technology has been mainly led by Japanese manufacturers (relevant post from Japanese Green Cars blog), but now every car manufacturer wants to add a hybrid model/version in its lineup. By 2015, Goldman Sachs expects the hybrid-vehicle market (including plug-in hybrids) to grow to 2.5 million, up from 500,000 in 2007, with Toyota and Honda in the lead.

BMW ActiveHybrid technology is the result of BMW's collaboration with GM and the former DaimlerChrysler, the Global Hybrid Cooperation. Parallel to the Global Hybrid Cooperation, the BMW Group has entered also into yet another joint venture with the Mercedes-Benz, developing components for hybrid drive in the luxury performance sedan.

Following EfficientDynamics technologies,  BMW sees ActiveHybrid technology as the next step.  A key component of the system is the two-mode active transmission which links the combustion engine with two high-performance electric motors. The two-mode active transmission uses planetary gear sets to variably split the power between the different units. The system switches between two operating modes according to need: one is used for moving off at high torque and low speed, the other for faster travelling speeds.

 

 

 

This ensures that power is optimally exploited depending on the particular driving situation. Fixed-ratio gears within the two operating modes furnish additional benefits, boosting efficiency and driving dynamics across the entire speed range. Here the two electric motors can be used both during acceleration and for the recovery of brake energy. This energy, which is subsequently on tap to drive the vehicle, is provided practically free of charge. Thus BMW ActiveHybrid cars can be driven either in full electric mode, solely on power from the combustion engine, or in a combination of both drive sources. 

ActiveHybrid models feature also Auto Start/Stop function, as well as an air conditioning and ventilation system which remains fully operational also with the engine switched off, power being supplied directly through the 120 volt on-board network operating on the lithium-ion battery. This unique concept of engine management allows, for the first time, truly effective climate control also at a standstill, cooling the interior to a significantly lower temperature right from the start, before the driver even fires the engine.

It's almost certain that Rolls-Royce will come up with a version of Ghost equipped with ActiveHybrid technology.