FEV to Show Mahindra & Mahindra Diesel-Electric Hybrid Scorpio at SAE World Congress; Other Powertrain Developments
FEV will exhibit a diesel-electric hybrid version of the Mahindra & Mahindra Scorpio SUV at the 2008 SAE World Congress, 14-17 April in Detroit, Michigan. Mahindra developed the diesel hybrid version of the vehicle with support from FEV, a global powertrain and vehicle engineering company.
FEV will also show a number of other powertrain developments at the event, including a 2-step variable compression ratio (VCR) mechanism for medium- and heavy-duty engines; a spray-guided turbocharged gasoline engine; a new diesel aftertreatment control system; and a new low-height cylinder head concept.
The Scorpio hybrid. FEV contributed to the hybrid powertrain systems development and integration, as well as software development to support Mahindra in the hybridization of the Scorpio. The Mahindra Scorpio hybrid combines a 2.2-liter, I-4 diesel common rail engine that delivers 85 kW (114 hp) and 270 Nm (199 lb-ft) of torque with a 6-speed automatic transmission and a 30 kW (peak) electric motor with max torque of 270 Nm and max speed of 8,500 rpm. A 288V, 8.4 Ah NiMH battery pack provides energy storage.
The Scorpio offers the full set of hybrid functions including start-stop; electric launch; torque augmentation; and regenerative braking.
Spray-Guided Turbo. The 1.8-liter I-4 spray-guided turbocharged gasoline engine (SGT) allows a fuel economy improvement of approximately 8% in the vehicle drive cycle using lean burn operating conditions compared to stoichiometric turbocharged gasoline DI engines. It produces 160 kW (215 hp) (89 kW/L or 119 hp/L) of power and 320 Nm (236 lb-ft) of torque with low fuel consumption. With the ability to support homogeneous and lean burn concepts, the BMEP levels in FEV’s spray guided turbo approach diesel levels.
The low fuel consumption enables the SGT to produce significant environmental benefits in terms of reduced CO2 emissions. The SGT emits 130 g CO2/km in a mid-size vehicle over the New European Driving Cycle without the use of alternative fuels. The engine also reduces hydrocarbon and particulate emissions.
The engine is directly adaptable for Flex-fuel operation. Other benefits include:
Reduced knocking through adapted charge motion
Cold start optimal
Enhanced spray penetration
Reduced oil dilution
Support of lean combustion concepts
Reduced charge motion variability
Variable Compression Ratio. FEV developed the 2-step variable compression ratio (VCR) mechanism for use in both gasoline and diesel medium and heavy duty engines. The 2-step VCR mechanism dynamically adjusts the center of the bore at the top end of the conrod, thereby achieving compression ratios of 14:1 – 17:1, depending on configuration, increasing engine efficiency and reducing NOx emissions. Key to the system is its ability to be integrated into existing engine designs due to its carry over piston and pin design. Other benefits derived from the ability to adjust the compression ratio include improved cold startability and the potential to optimize performance while utilizing alternative fuels.
Designed for medium- and heavy-duty engines, the system currently supports peak cylinder pressures of 180 bar and is presently completing durability testing.
Aftertreatment control system. Because the new diesel aftertreatment control system, developed in North America, features a stand-alone control unit that does not need to be integrated with the Engine Control Unit (ECU), the system offers the potential to significantly impact emission control issues in older model vehicles due to the possibility of retrofitting the system.
The Aftertreatment Controller is capable of operation independent of a sophisticated ECU, and actively controls either an SCR or NOx absorber system. The stand-alone controller interfaces with an existing engine management system and provides precise, closed-loop feedback control.
The controller is designed to be highly flexible, with each unit requiring no software modifications, and simple calibration. Its modular structure allows for easy adjustment, replacement, addition, or removal of control modules.
The FEV-patented controller core features multi-variable control algorithms enabling simultaneous lambda and temperature control at all times. The software development environment allows fast porting to various processor platforms.
Low-height cylinder head. The new low-height cylinder head concept allows a reduction in the height of a classical design cylinder head by up to 15 mm. This reduction in head height enables several engine modifications, such as shorter valves, and a narrower cylinder V-angle that provide significant additional packaging space in the engine compartment. Benefits also include stiffer cylinder head structure and reduced valve stem forces, providing a more robust and durable powertrain system. Other benefits include reduced cylinder head bending, reduced valve stem diameter, in addition to its shorter valve length.
The cylinder head was developed in Europe by FEV Motorentechnik, where smaller, higher specific power vehicles have dominated the market for some time. FEV has also implemented this technology in diesel cylinder heads for high performance, where this technique contributes to the achievement of engines with a power density greater than 100 kW/L (134 hp/L).