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Frankfurt Preview: BMW ActiveHybrid 7
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On the heels of the ActiveHybrid X6, BMW announced the production version of the all-new BMW ActiveHybrid 7, which will also premiere at the Frankfurt Auto Show (IAA) in September.
First shown as 7 Series ActiveHybrid concept last year at Paris Motor Show, the BMW ActiveHybrid 7 is scheduled to reach America shores in Spring, 2010.Based on the newest BMW 7 Series, this unique car sets new standards for performance and efficiency in the premium luxury class.
This symbiosis of an upgraded twin-turbo, High Precision Direct Injection, V8 engine with a 3-phase synchronous electric motor gives the BMW ActiveHybrid 7 a combined output of 455 hp and maximum torque of 516 lb-ft (preliminary figures). Power is transmitted via an 8-speed automatic transmission with the electric motor positioned between the engine and the torque converter. The electric motor receives its supply of energy from a lithium-ion battery developed specifically for use in this automobile.
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BMW ActiveHybrid technology also provides new features that promote efficiency while preserving comfort. As an example, the BMW ActiveHybrid 7 is the first BMW with automatic transmission to feature Auto Start Stop to maximize efficiency by avoiding engine idling when stopped. Another advantage is that the air conditioning and ventilation system remains fully operational when using Auto Start Stop. In this case, power is supplied directly through the 120-volt on-board network powered by the lithium-ion battery.
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Like existing BMW 7 Series models, BMW's first luxury sedan with ActiveHybrid technology will enter the market in two body variants. The extended version of BMW ActiveHybrid 7 has a wheelbase increased by 5.5", all of which is devoted to the enhanced comfort of rear-seat passengers. Both models are available with a wide range of options from the portfolio of equipment and accessories offered on the BMW 7 Series, enabling the tailoring of the ActiveHybrid 7 to individual tastes and requirements.
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The BMW ActiveHybrid 7 takes an innovative approach to ensure outstanding efficiency in this segment. At the same time this unique sport sedan offers dynamic driving characteristics at a level that one would expect from The Ultimate Driving Machine. BMW ActiveHybrid is an important element within the BMW EfficientDynamics philosophy meant to offer technologies able to significantly reduce fuel consumption and emissions on every new model while enhancing driving performance.
BMW uses hybrid technology because it can make an effective contribution to the reduction of fuel consumption and emissions. As a rule, the savings potential of hybrid technology increases with the power of the combustion engine interacting with the system. In the case of the BMW ActiveHybrid 7 precise coordination of the electric motor and the V8 serves to optimize the efficiency of the combustion engine under all operating conditions.
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The ActiveHybrid concept stores energy in a compact, high-performance lithium-ion battery. The processes of charging the battery, supplying power to the electric motor, and electric ancillaries are managed by a control unit developed specifically for the BMW ActiveHybrid 7.
The BMW ActiveHybrid 7 features both a conventional 12-volt on-board network fed by an absorbent glass mat (AGM) battery and an additional battery featuring lithium-ion technology operating at 120-volts. The lithium-ion battery supplies power to the electric motor as required and serves to start the engine. Electric power generated by Brake Energy Regeneration is fed into both on-board networks. The air conditioner compressor on BMW ActiveHybrid 7 is integrated in the 120-volt network. All other electrically operated functions of the car are supplied by the 12-volt network. The two on-board networks are connected by a voltage converter featuring flexible energy management. Both batteries are charged and maintained through Brake Energy Regeneration. The 12-volt battery is fed with energy from the high-voltage network.
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BMW found that lithium-ion battery technology offers sufficient energy storage capability while taking up minimal space. The result is that the BMW ActiveHybrid 7 gives up almost no luggage capacity to its conventional siblings (750i and 750Li), because the 120-volt battery is small enough to be mounted underneath the trunk floor. Furthermore, the weight penalty incurred by this battery is minimal, meaning less energy is consumed to carry it. Using this technology enables the ActiveHybrid 7 to maximize storage capacity and acceleration in the hybrid luxury sedan segment. It is the fastest-accelerating hybrid sedan in the world.
The useful energy provided by this high-performance battery is 400 watt-hours. The battery itself is comprised of 35 cells and an integrated control unit which continuously analyzes the charge level and ensures appropriate dependability under all conditions. Despite its high level of performance, the lithium-ion battery measures just 14.6 x 8.7 x 9.1 inches (37 x 22 x 23 centimeters) and weighs a mere 59.5 lb or 27 kg.
Hence, it is only slightly larger than a conventional car battery and is housed conveniently in the trunk floor between the wheel arches of BMW ActiveHybrid 7, safely surrounded by a high-strength special casing. This location provides protection for the battery and helps to preserve the 7 Series' ideal 50-50 weight distribution. The luggage compartment with its capacity of approximately 13 cu. ft. offers adequate space for four 46-inch golf bags.
Twin-turbocharged V8 gasoline engine with High Precision Direct Injection.
The combustion engine is the innovative reverse-flow V8 introduced in the BMW X6. The world's first V8 gasoline engine with two turbochargers in the V-section between the two rows of cylinders develops power throughout the entire engine speed range. The spontaneous and direct response of this engine results from its compact configuration, which allows the shortest exhaust manifolds.
Displacing 4.4 liters, this outstanding engine delivers its maximum output of 440 hp between 5,500 and 6,000 rpm. Peak torque of 475 lb-ft is maintained from 2,000 to 4,500 rpm, with High Precision Direct Injection ensuring precise supply of fuel at all times. Piezo-injectors positioned in the combustion chambers between the valves ensure a smooth, efficient and clean combustion process. The engine fulfils the European EU5 standard as well as the ULEV II standards in the US.
Compared with the engine featured in the BMW 750i/Li, this version has been modified in numerous respects to the specific requirements of the BMW ActiveHybrid 7. There is no starter, alternator, or belt drive for the air-conditioning compressor and hydraulic pump. The cooling system has been modified for hybrid operation. The result is remarkable power from idle. The response of the engine is enhanced by the electric motor with its additional torque. The direct response to the accelerator pedal is impressive when compared either with conventional 7 Series models or existing hybrid vehicles already in the market. Acceleration to 60 mph in 4.8 seconds (preliminary) ranks it among the fastest and most thoroughbred sports cars in the world. Top speed of BMW ActiveHybrid 7 is electronically limited to 150 mph.
The three-phase synchronous electric motor featured in BMW ActiveHybrid 7 is positioned between the engine and the torque converter, and is connected to the crankshaft. Shaped like a disc, the electric motor weighs 50.7 lb (23 kg). Its compact design ensures full integration in the transmission housing.
The electric motor generates boost of approximately 20 hp and peak torque of 155 lb-ft. When operating as a generator in Brake Energy Regeneration, the electric motor produces approximately 27 hp of brake force.
In total, the BMW ActiveHybrid 7 features a maximum system output of 455 hp and peak torque of 516 lb-ft (preliminary). Normally, this level of power output would require a correspondingly high increase in fuel consumption. The BMW ActiveHybrid 7, in contrast, combines its power with an equally impressive increase in fuel efficiency of about 15%.
8-speed automatic transmission in combination with Auto Start Stop.
To transmit the drive power developed jointly by the V8 and the electric motor, the BMW ActiveHybrid 7 features a newly developed 8-speed automatic transmission specifically tailored to the demands of hybrid technology. This high-tech transmission combines shift comfort, sportiness and efficiency at unprecedented levels.
The new 8-speed close-ratio automatic transmission uses an innovative gear-set configuration providing two additional gears and a larger overall gear range than the 6-speed automatic transmission used by BMW without negative effects on size, weight, or internal efficiency. With the new transmission, the V8 engine is better able to stay in the power peak while ensuring greater overall efficiency.
Overall efficiency is further enhanced with the Auto Start Stop function. Auto Start Stop automatically switches off the combustion engine at idle, eliminating fuel consumption when stopped. Once the driver's foot comes off the brake pedal, the engine restarts instantaneously.
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