This new automatic transmission, whose series production has already begun, has improved consumption by up to 3 percent, and CO2 emissions, which has been accompanied by a greater ease of use and improved driving dynamics.
ZF explains in a note that this new development offers numerous advances, even further reducing drag torque and vibration and biggest jump between gears.
The new automatic transmission ZF 8HP will go on in other BMW models and it will be used by other automakers worldwide.
This new ZF 8HP automatic transmission, whose first generation was produced from 2009, It has been launched in the BMW 520d in July this year. Its about model 8HP50, prepared for engines with up to 500 Nm torque, since for even more powerful engines, up to 750 Nm, ZF 8HP75 provides variant.
ZF explains that in combustion engines There are two ways to continue to achieve compliance with increasingly stringent CO2 emission reductions without reducing the engine torque and power: the 'Downsizing', engines with fewer cylinders and smaller displacement, but supercharged and 'Downspeeding' or reducing engine speed, reaching maximum torque at lower revs.
The reduction of revolutions engine requires a gearboxes with higher jumps between gears, ZF so in its new 8HP, has increased 7.0 to 7.8 breaks through new games optimized gear.
'Now just this concept reduces the revolutions per minute in about 50 in each of the marches, and even low consumption 1 percent ', explains Jürgen Greiner, director of Development Gearbox ZF passenger car.
In addition, ZF engineers They have managed to further reduce internal losses of transmission through a different delamination: integrated in the blades of the switch elements springs ensure that the shifting components are fully opened and thus reduce the drag torque, so that in this new generation loss has been reduced by two thirds, Greiner stresses.
A new feature minimizes moments of slow marches, thanks to the reduction in speed and when the vehicle is completely stopped fully opened one of the clutches. Further, It has reduced the pressure of oil pump gearbox Automatic from 5 to 3.5 bar only therefore requires less energy.
The new ones engines 'downsizing', more efficient and more powerful at the same time, require adaptations to reduce their different vibrations, and it is for this reason that ZF employs in all its 8HP automatic transmission, torsional vibration dampers especially modern eliminating very effectively vibrations from the engine to not transmitted to the drive and the body.
To meet the 'downspeeding', the new torque converter helps hydrodynamic drive, enabling driving with the clutch closed bridging a very low speed. Decoupling Transmission and temporarily engine You can now perform up to a speed of 160 km / h, a formula that helps a lot to reduce consumption.
ZF has also improved the system start / stop (stop and go) Box: when the vehicle is completely stopped, the motor is switched off immediately and not before, after 1.5 seconds.
What it is not reduced driving dynamics despite reduced consumption, says ZF, since the new electronically controlled transmission allows multiple interleaved reductions, bringing the gearbox 8HP reacts even more spontaneously and dynamically.