Lotus Engineering and Continental Division Powertrain Present Results of “Low CO2” Mild-Hybrid Project
|The Low CO2 concept uses engine downsizing and a mild hybrid drive to reduce CO2 emissions some 15% from a stock version of the same Astra vehicle.
Lotus Engineering, the automotive consultancy division of Lotus, and Continental Division Powertrain have presented the results of their “Low CO2” research collaboration. The primary objective of the Low CO2 project was to deliver greatly reduced CO2 emissions while maintaining an engaging driving experience from an affordable set of technologies. The solution employs an integrated set of powertrain systems within a downsized overall package.
The Low CO2 vehicle concept is demonstrated in an Opel Astra, and produces 149 g/km CO2—a reduction of 15% against the naturally aspirated 1.8-liter 4-cylinder engine version of the same vehicle.
Lotus brought to the project its powertrain design, development, testing and validation capabilities, with specific expertise in engine downsizing and systems integration. Continental Division Powertrain supplied its experience in powertrain management and control systems, especially in the areas of direct fuel injection systems, hybrid drives, energy management, emission after-treatment and a number of new technologies.
The Low CO2 Astra features:
A Lotus Engineering-designed pressure-charged three-cylinder 1.5-liter gasoline engine;
An innovative integrated exhaust manifold design;
Cam profile switching for variable lift and timing;
A high-pressure fuel pump; and
A mild hybrid drive with supercapacitors for energy storage.
|The Low CO2 engine uses a new advanced cylinder head design featuring an integrated exhaust manifold. Click to enlarge.
The engine exploits the findings of the HOTFIRE (Homogeneous and Throttleless for Fuel efficiency with Reduced Emissions) project, a three-year research program led by Lotus Engineering and also including Siemens VDO (since acquired by Continental), Loughborough University and University College London.
HOTFIRE, which started in October 2004, was based at Loughborough University to explore a permanent homogeneous charge direct injection strategy through a fully variable valve train system with the use of centrally-mounted injectors.
The cylinders in the engine have a bore of 88mm and a stroke of 82mm. Compression ratio is 10.2:1. Continental Division Powertrain’s single cylinder fuel pump is driven directly from the tri-lobe cam on the exhaust camshaft. Fuel pump pressure is 200 bar. Both fuel pump and water pump are electric, providing fuel savings of up to 2%.
The fuel injectors are affordable, 200 bar, solenoid, direct injection centrally mounted injectors provided by Continental Division Powertrain.
Lotus Engineering designed and developed a new advanced cylinder head design featuring an integrated exhaust manifold. The production-ready technology can significantly reduce manufacturing costs, emissions and weight on most gasoline-engined passenger vehicles, according to Lotus. An integrated exhaust manifold has potential to:
Reduce parts count: 35% fewer components resulting in lower inventory, production, logistics and aftermarket costs;
Reduce weight: total system mass reduction of 20% resulting from elimination of separate exhaust manifold; and
Lotus Engineering’s Cam Profile Switching system incorporates lobed tappets that vary valve lift and timing. The system is produced under licence by INA and features in Porsche products in its ‘VarioCam Plus’ system.
Maximum power from the engine is 159 hp (118 kW) @ 5,000 rpm, with maximum torque of 240 Nm (177 lb-ft) @ 2,500-4,000 rpm. The mild hybrid motor, which is placed between the engine and the transmission, delivers 12 kW of output. 60V supercapacitors provide the energy storage for the mild hybrid system.
James W. G. Turner, et. al. The HOTFIRE Homogeneous GDI and Fully Variable Valve Train Project - An Initial Report (SAE 2006-01-1260)