The modular system for the more economy-minded driver: hybrid development milestones

Continental's progress from the initial development work to the successful start of series production of lithium-ion batteries as the energy storage unit for the latest generation of hybrid vehicles has taken more than a decade.

1996 saw work commence on ISAD (Integrated Starter Alternator Damper), also known as the crankshaft starter generator, which replaces the traditional alternator and the starter motor. ISAD also provides functions such as automatic start-stop, braking energy recuperation and acceleration assistance, all of which are still essential for hybrid vehicles. The system, including battery, power electronics and electric engine, went into series production in 2003.

2002 Start of lithium-ion battery system development with the aim of producing higher-performance batteries with greater storage capacity. Lithium-ion technology is the key to the success of hybrid and electric vehicles.

2003 Start of series production of a mild hybrid system with a lead acid AGM battery, installed in both GMC's Sierra and in Chevrolet's Silverado pickup in conjunction with an eight cylinder gasoline engine and automatic transmission.

2005 The first fully-functional lithium-ion battery system.

2006 Start of the project together with the Daimler Group to develop a hybrid system with lithium-ion batteries for the planned Mercedes S400 BlueHYBRID, the S-Class hybrid model. The vehicle will be available from the middle of 2009.

2007 Build-up of small series production of lithium-ion batteries.

2008 Series production starts at the new Nuremberg production site.

The modular principle: scalable electric drive systems

The electric drive in hybrid and fully electric vehicles consists of a wide assortment of components capable of carrying out a variety of tasks. This includes:

• Mild hybrid drives which give the combustion engine a noticeable torque boost when accelerating and which recharge the energy storage unit through regenerative brake functions

• Full hybrid drives with the option of driving purely on electric power for short distances

• Plug-in hybrids with the option of driving purely on electric power for longer distances

• Electric vehicles (for driving purely under electric power with no combustion engine)

The flexible modular design includes the energy storage unit (high-performance battery), a voltage transformer for powering the 14-volt vehicle power supply, an electric motor and the inverter for different engine-power classes. The components compose scalable hybrid systems with additional electric outputs of up to more than 150kW (204 bhp), which reduce consumption but also make driving much more enjoyable. The modular components are also suitable for the purely electric or fuel-cell vehicles of the more distant future.

The inverter occupies a position of vital importance in the hybrid drive system. Depending on the amperage and the voltage status, the inverter is a crucial factor in the overall efficiency of the hybrid drive because it ensures that as much kinetic energy as possible is re-converted in overrun phases and fed back to the energy storage unit. The more often and the quicker the storage unit is charged, the more frequently the electric engine can relieve the combustion engine.

In the next generation, Continental will reduce the installation volume of the electronics by a further 30 percent to five liters, i.e. the power electronics will require less space. They will be fitted into a housing which takes up the same space as the alternator which is now superfluous in a hybrid vehicle. This will further significantly reduce production costs. The first samples have already been delivered to customers. Continental is also developing an electric final drive. This will allow greater flexibility when integrating the electric drive, offering possible alternative uses and further potential for cutting costs.

Great interest shown in buying hybrid vehicles

There is worldwide interest in vehicles with a hybrid or electric drive system according to a representative survey, the first of its kind, conducted on behalf of Continental by the market research institute TNS/Infratest. Over 8,000 drivers were questioned in China, Germany, France, the UK, Japan, Austria, Switzerland and the USA. Among other comments, more than a third of all those questioned could see themselves either definitely or at least very probably choosing a hybrid drive vehicle when they next bought a car. If the government were to offer tax incentives for buying hybrid vehicles, more than 50 percent of those questioned would be persuaded to buy a hybrid car even though it had not been their intention to do so beforehand. 85.7 percent of all those questioned also said that their annual mileage was less than 19,000 miles (30,000 kilometers); and 69 percent drive mainly in urban areas. Over 60 percent of Americans and Japanese who drive a hybrid vehicle either consider their car to be good or have an overwhelmingly positive impression of its performance. In Germany, too, hybrid vehicles are the coming thing. Last year, 7,591 car owners registered hybrid vehicles. According to the study, the annual mileage driven by 54.4 percent of Germans is less than 10,000 miles (15,000 kilometers).