|The GETRAG Boosted Range Extender provides of all-electric or combined electric and mechanical drive. Click to enlarge.|
The Boosted Range Extender combines a two-cylinder combustion engine with an electric motor, alternator and power-shiftable two-speed transmission. When driving, the electric drive takes over the major portion of the dynamic driving conditions so that the internal combustion engine is only used for a small portion of the total characteristics map. Optimization of the system is therefore possible with regard to degree of efficiency, costs and installation space.
The electric motor provides continuous output of 30-45 kW, depending upon vehicle platform, with maximum output of 45-80 kW. Maximum drive torque is 220 N·m (162 lb-ft). The alternator provides continuous output of 10-20 kW (again, depending upon vehicle platform), with maximum drive torque of 30 N·m (22 lb-ft).
|The transmission in the range extender. Click to enlarge.|
The power shift transmission is actuated via a compact integrated control module/hydraulics unit. When starting off, the system is in electric mode in which the electric motor provides the propulsion in first gear. The increased wheel torque provides very good acceleration values and strong climbing power.
At a low state of charge for the energy storage system, the internal combustion engine starts and provides the energy supply via the alternator connected to it in serial operation. At typical speeds in city traffic, the combustion engine can then be directly coupled to the output in parallel operation.
Second gear is engaged outside the city limits. The internal combustion engine—if it is active—now runs in the range of the best possible specific consumption. In this driving mode, the electric motor takes over the dynamics where necessary.
The output is performed via a conventional bevel gear differential that was selected from GETRAG’s standard components catalog, just like a variety of other components. This design makes it possible to install standard components with a high production volume.
The total range—some 600 km (373 miles)—is comparable with one of a conventional vehicle, according to GETRAG. Compared to full hybrids, the Boosted Range Extender system packs in up to 60% less total drive performance (i.e. internal combustion engine, electric motor and alternator) with the same vehicle performance. The special torque characteristic ensures that none of the driving fun is lost.
The design of the Boosted Range Extender requires no revolutionary changes to the infrastructure and can go on the market for use with existing systems. So it should be possible to go for a fast market launch. It offers a solution that the market needs now and will be more than adequate to cope with tighter requirements in future. That has led to a great deal of interest in this product and we are currently in talks with a lot of interested potential customers.
—Rolf Najork, Executive Vice President for Research & Development
The Boosted Range Extender would be particularly useful for vehicles driven mainly within city limits, GETRAG suggests. A plug-in function also provides for charging from the power grid.
The Boosted Range Extender is part of GETRAG’s eDrive product line, which also include hybrid transmissions and electric drive units. GETRAG has also built battery electric and hybrid vehicle demonstrators.