GETRAG Develops Boosted Range Extender

The GETRAG Corporate Group has developed a cost-effective electric drive train architecture that combines and even outperforms the advantages of conventional drive trains, hybrid drives and state of the art electric drives.

GETRAG will present its newly developed Boosted Range Extender at this year’s international trade fair for manufacturing technology and automation, in Düsseldorf.

The combination of a combustion engine with an electric motor allows excellent performance data despite of the CO2- and fuel-efficient setting. In driving mode the vehicle is usually propelled by the electric motor.

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.

Thanks to the very low CO2 emissions of less than 50 g CO2/km (NEDC), this design also fulfills the more stringent requirements of future legislation. Compared to the full hybrids, up to 60 % less total drive performance (internal combustion engine, electric motor and alternator) is installed with the same vehicle performances.

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 power-shiftable two-speed transmission from GETRAG mechanically connects the internal combustion engine with the electric motor when needed.

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.

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. Thanks to the increased wheel torque, very good acceleration values and an outstanding climbing power are achieved. At a low charge status of the electric storage unit the internal combustion engine is started 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 status, the electric motor takes over the dynamics where necessary.

Technical specification:

Transmission 2RET300

Type: planetary gear set power shift

Number of gears: 2

Actuation: hydraulic

Lubrication: internal 1-chamber lubrication, no external cooling

Maximum driving torque: 3,500 Nm

Maximum width: 516 mm

Installation length: 390 mm (with electric motor)

Installation height: 536 mm (with electric motor)

Weight: approx. 55 kg (without electric motor)

Electric Motor

Continuous output (@UHB): 30 kW – 45 kW (depending on vehicle platform)

Maximum output (@300 V): 45 kW – 80 kW (depending on vehicle platform)

Cooling design: water-cooled

Maximum drive torque: 220 Nm

Maximum drive speed: 12,000 rpm

Alternator

Continuous output (@UHB): 10 kW – 20 kW (depending on vehicle platform)

Cooling design: water-cooled

Maximum drive torque: 30 Nm

Maximum drive speed: 15,000 rpm

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