BMW ActiveHybrid 5 to arrive in US showrooms in March 2012

The BMW ActiveHybrid 5. Click to enlarge.

BMW’s newest hybrid, the BMW ActiveHybrid 5, will arrive in US showrooms in March 2012. BMW unveiled the Concept version of the 5 Series ActiveHybrid at the Geneva Motor Show in 2010. (Earlier post.)

Based on the BMW 535i Sedan, the ActiveHybrid 5 brings together BMW’s 3.0-liter TwinPower Turbo inline six-cylinder engine, an electric drive system and an eight-speed automatic transmission for the first time. The latest generation of BMW ActiveHybrid technology also adds controlled energy management to the mix. The drive system generates combined output of 335 hp (DIN) (250 kW) a with maximum torque of 330 lb-ft (447 N·m); allows the car to be driven on electric power alone up to 37 mph (60 km/h); and accelerates the BMW ActiveHybrid 5 from 0 to 60 mph in 5.7 seconds (preliminary).

Under the hood. Click to enlarge.

The BMW ActiveHybrid 5 delivers a double-digit percentage improvement in fuel economy over the BMW 535i based on preliminary results. (At the 2010 Geneva Motor Show, BMW said the Concept version would reduce fuel consumption 10%.)

This is the first time BMW has mated an inline six to a BMW ActiveHybrid system. The 3.0-liter engine, which develops 300 hp (224 kW) and peak torque of 300 lb-ft (407 N·m), has won the international Engine of the Year Award two years running. The BMW TwinPower Turbo technology of the six-cylinder engine combines a twin-scroll turbocharger, High Precision Direct Injection, Double VANOS variable valve timing and VALVETRONIC intake control.

The synchronous electric motor of the BMW ActiveHybrid 5 is integrated into the housing of the eight-speed automatic transmission, saving space. The interplay between the electric motor and gearbox is controlled by a clutch. The motor’s operating temperature is regulated by the combustion engine’s cooling system.

The electric drive system develops 55 hp (41 kW) and makes 155 lb-ft (210 N·m) of torque available from rest. The motor is supplied with energy by a high-performance lithium-ion battery, specially developed for the BMW ActiveHybrid 5. The high-voltage battery is encased in a special high-strength housing and positioned between the wheel arches in the trunk, providing it with optimum protection. It consists of 96 cells, has its own cooling system and offers usable energy capacity of 675 Wh.

The BMW ActiveHybrid 5 has both a conventional 14-volt power supply and a high-voltage supply with an operating voltage of 317 volts. They are linked by a voltage transformer which ensures that maximum electric energy can be used to enhance driving dynamics and comfort in any operating phase. Like the electric motor, the air conditioning compressor is also fed with power from the lithium-ion battery exclusively via the high-voltage supply. In addition, the stationary climate control function can be used to cool the interior before the engine is started.

The high-performance lithium-ion battery is charged when the car is coasting or braking. The electric motor acts as a generator feeding energy into the high-voltage battery; under acceleration, the electric motor takes on a boost function. Here, it assists the inline six by generating an extra burst of power.

Integrated into the standard Driving Dynamics Control is an ECO PRO mode. It tailors the driving systems for maximum efficiency, including making more frequent use of all-electric mode. In ECO PRO mode, the combustion engine can be switched off and fully decoupled while coasting at speeds of up to 100 mph (160 km/h). In coasting mode, as with all-electric mode for urban driving, all safety and comfort functions remain fully operational. To avoid periods with the engine running at idle, the BMW ActiveHybrid 5 is equipped with a hybrid start-stop function.

Further, the power electronics in the BMW ActiveHybrid 5 are linked up with the standard navigation system, enabling proactive analysis of driving conditions based on the selected route. This enables the drive components to be primed to deliver maximum efficiency (the effect may vary according to the quality of the available navigation data). All the hybrid-specific components of the drive technology and energy management systems have been developed specially for use in the BMW ActiveHybrid 5.

The BMW ActiveHybrid 5 can operate in all-electric mode up to a speed of 37 mph (60 km/h), for zero emissions in town. The lithium-ion high-voltage battery can store sufficient energy to give an all-electric driving range of up to approximately 2.5 miles (4 km) at an average speed of 22 mph (35 km/h).

The operating status of the powertrain components is shown in displays, unique to the ActiveHybrid 5, in the instrument cluster and in the Control Display. As well as the energy flow and energy recuperation display, these include an additional gauge next to the tachometer which shows the boost effect being provided by the electric motor during acceleration. A display in the iDrive interface provides a variety of information – for example on the battery’s current charge level and the power-sharing between the internal combustion engine and the electric motor during the course of a journey.

The chassis specifications of the BMW ActiveHybrid 5 include double-wishbone front and integral rear suspensions, Servotronic speed-sensitive power steering, a high-performance brake system and 18-inch alloy wheels. Dynamic Damper Control, featuring electronically controlled shock absorbers, is available as an option. The Dynamic Stability Control system, which stabilizes the vehicle by individually applying the brakes and reducing engine power, also incorporates functions such as Dynamic Traction Control, the Anti-lock Braking System, Cornering Brake Control, Dynamic Brake Control, Brake Assist, Brake Fade Compensation, Brake Drying and Start-Off Assistant.

The hybrid-specific safety features, which protect the high-voltage lithium-ion battery and the power electronics, are integrated into the BMW 5 Series’ existing active and passive safety systems. In a collision, high-strength structural components and large deformation zones help to keep impact forces away from the passenger cell and also from the hybrid drive components.

In the BMW ActiveHybrid 5 the standard Driving Dynamics Control switch offers not only Sport+, Sport and Comfort set-ups (as well as Comfort+ mode if the optional Dynamic Damper Control is specified), but also the ECO PRO mode. As an alternative to the standard 8-speed automatic transmission, an 8-speed sport automatic with faster shift times is available.

A number of BMW ConnectedDrive features are available for the BMW ActiveHybrid 5 including Park Distance Control, a rear-view camera, Surround View, High-Beam Assistant, Parking Assistant, Active Blind Spot Detection, Lane Departure Warning, BMW Night Vision with pedestrian recognition and Head-Up Display. The BMW Apps option offers integration of the Apple iPhone.

Source: Green Car Congress