CAN-connected kinetic energy recovery system (KERS)
Efficient use of energy is the topic of today. Max Mosley, FIA (Fédération Internationale de l’Automobile) president, after some sex-scandal has launched a new toy: Kinetic energy recovery system (KERS). However, all Formula One racecar makers have had serious problems to implement it. It has become ”an impossible project”. Ferrari President Luca di Montezemolo, who is also president of the Formula One Teams’ Association, has described its introduction as a mistake. It is almost certain Ferrari will not run KERS for 2009, with di Montezemolo’s concerns this week supported by Norbert Haug, the boss of McLaren’s engine partners Mercedes-Benz. But nearly all the teams are facing an uphill task to introduce it next year.
Nevertheless, Bosch Motorsport is optimistic: ”In comparison with the hybrid technology of production vehicles, the concepts for motor racing are considerably more powerful, and at the same time more compact,” says Klaus Böttcher, director Bosch Motorsport. ”We are already holding discussions with many teams from various racing series.” Bosch is developing a modular KERS kit, which covers the requirements from Formula One to racing series such as the DTM or 24‑hour races.
Hybrid systems by Bosch Motorsport always comprise a battery, the electric motor, and the CAN-connected KERS controller. This contains the power electronic, the battery management, and the management system for hybrid and engine functions. A lithium-ion battery with scalable capacity or a flywheel energy storage device is used for storing energy. The latter stores up to 750 kilojoules of energy. The electric motors weigh between 4 kg and 8 kg with a maximum power level of 60 kW. Due to its modular structure, KERS from Bosch can be put together individually in terms of weight, robustness, and performance to suit the requirements of the respective race series.
Starting and stopping the engine
The energy savings in Formula One cars is very limited compared to normal passenger cars using the recently introduced start/stop engine technology. Bosch’s CAN-based start/stop technology can be found in more and more passenger cars. Since December 2008, Fiat is presenting its first model to feature a start/stop system: the Fiat 500. Bosch supplies the specially adapted starter, the engine management system, and the battery sensor. Bosch has been manufacturing this start/stop technology since 2007, and has already delivered more than 500 000 starters, for example, to BMW and Mini. Stefan Asenkerschbaumer, president of the Bosch Starter Motors and Generators division, believes this market will grow rapidly in the next few years: “In 2008, roughly five percent of all new vehicles in Europe are equipped with a start/stop system. By 2012, we estimate this will be every second newly registered vehicle – most of them with Bosch technology.” In the next few months, series production of other cars featuring this Bosch technology is to start – the Kia cee’d, for example.
Test drives by Bosch engineers show that start/stop systems reduce fuel consumption, and thus also CO2 emissions, in the New European Driving Cycle (NEDC) by up to five percent. In the urban component of the NEDC, the saving can be as high as eight percent. Start/stop systems automatically stop the engine when the vehicle is stationary, for example at traffic lights. The engine is restarted as soon as the driver depresses the clutch pedal to put the vehicle back into gear. As starter-based systems are largely based on existing components, their cost-benefit ratio is excellent. And unlike other technologies, this approach is also suitable for cold starts in diesel engines. In the Fiat 500, the system will initially be available in combination with the Dualogic automated manual transmission and a 1,2-liter engine. Fiat plans to install the system in other variants and models in 2009. Bosch has adjusted the service life of the starter to the far greater number of starts. Its powerful electric starter motor as well as low-noise, enhanced meshing mechanics guarantee safe, fast, and quiet engine starts in all situations. Bosch also supplies the engine control unit for the Fiat 500, including the software used to analyze all the relevant sensor data and to stop and start the engine. Bosch also supplies the battery sensor. It computes the current state of battery charge and relays this information to the energy management system.
Bosch start/stop systems can draw on the expertise of the company’s starter technology, drivetrain, and energy management fields. Next to the starter, the control software, and a battery sensor, the system as a whole includes a crankshaft sensor and the respective sensors at the pedals. A high efficiency alternator in combination with a deep-cycle resistant battery means that the amount of time the vehicle can remain stationary with the engine switched off is increased.
Source: CAN Newsletter June 2009
