BMW's brand-new 7 Series began to meet the public in the autumn of 200 1. Two models with V8 engines were initially launched. With its first-class power, handling and high level of ride comfort, it soon became a trend-setting model in luxury cars. Since the autumn of 2002, the new 7 Series equipped with six-cylinder and eight-cylinder diesel engines has also entered the market.
With the launch of 760i/760Li, the most outstanding member of this "family" is putting a perfect end to BMW's flagship model series. Both models are equipped with a 6.0-liter 12-cylinder gasoline engine with a maximum power output of 327 kW (445 HP). The difference between 760i and 760L is that the wheelbase of 760l is longer 14cm. The most outstanding part of the 760i/760Li masterpiece is the 12 cylinder power plant, which is the world's first direct injection 12 cylinder engine. Therefore, 760i/760Li marks the birth of the third generation 12 cylinder car of BMW.
The structure of V 12 is recognized as the best engine structure in the industry, which is very suitable for top-class cars. Physically perfect: 12 cylinders are arranged in a 60-degree V shape through two cylinder groups, which is very balanced and can obtain extremely smooth driving force.
The technical features of BMW's new 12 cylinder are: direct fuel injection, 4-valve technology and Valvetronic electronic valve. The displacement of Vl2 power unit is 5.972cc, the output is 327 kW at 6000 rpm, the maximum torque is 600 Newton meters at 3950 rpm, and the torque can reach 500 Newton meters in a larger speed range of 1500-6000 rpm. The fuel consumption conforms to the European standard, with 100 kilometers 13.4 liters, and the acceleration from 0 to 100 kilometers only takes 5.5 seconds, with a top speed of 250 kilometers per hour.
Let's take a look at some important new technologies adopted by this new engine: direct fuel injection, that is, direct fuel injection into the combustion chamber. BMW's engine engineers chose this technology to achieve stronger power output and higher fuel efficiency than the traditional fuel injection system. BMW's system adopts the most suitable fuel-air mixture ratio and controls emissions by using common technologies, such as the current three-way catalytic technology. Comparatively speaking, the concept of direct injection (such as lean burn or stratified burn) adopted by other automobile companies can achieve higher fuel efficiency than that chosen by BMW, but these must rely on unproven "deNOx" catalytic technology and have very strict requirements on the sulfur content in fuel, and such fuel is not available everywhere. So the technology adopted by BMW can really be said to be universal.
The nozzle of the fuel injector is located in the dry combustion chamber, close to the intake valve, and the fuel is supplied to the nozzle at high pressure through the "* * * rail" mode, which can form fuel droplets more conducive to combustion. Each cylinder group has a mechanical pump to provide the required pressure, which is located above the exhaust camshaft and driven by a special cam. The compression ratio of the engine is very high (1 1.3: 1). Compared with V8 engine (10.5: 1), this engine can provide high performance and excellent combustion efficiency relative to its capacity.
The new Vl2 engine also enjoys many advanced technologies of the new V8 engine code-named N62 on the 7 Series one year ago. One of them is Va 1vetronic. This is a revolutionary concept of "breathing", which is the first in BMW patent field. Va 1vetronic cancelled the traditional throttle valve and replaced it with variable valve lift to control the engine power. The valve mechanism is located above the intake valves of two cylinder banks, and each of the 48 valves on the engine is driven by the rotating finger rocker arm of the camshaft boss. On the intake side, there is an additional element located between the cam boss and the rocker arm, which is called the intermediate follower. The middle follower drives the rocker arm, and then drives the valves in turn. Its position is determined by the eccentric shaft of the servo motor. The driver's control of the accelerator pedal sends instructions to the eccentric shaft through the engine management system, and then the shaft changes the shaft point of the intermediate follower to determine the degree of valve lift.
Doub 1e VANOS variable valve timing technology: In addition to the variable valve lift of Va 1vetronic, BMW's DOub 1e VANOS system changes the valve lift by rotating the intake and exhaust camshafts to further optimize engine power, emissions and fuel efficiency. VANOS is short for "variable camshaft control" in German. This feature is not unique to N62 and N73 engines. At present, other BMW engines also have this technology, but VANOS plus Valvetronic technology is only available in N-prefix engines.
1987, after the legendary Horch and Maybach 12 cylinder engines disappeared for many years in 1930s, BMW made the myth of 12 cylinder come true in Germany. BMW's first generation 12 cylinder and 5-liter light alloy power plant have a power of 220kW (300 HP) and a maximum torque of 450 Nm. This engine was immediately applied to the BMW 750iL sedan with the same excellent design, so that the top speed of the car can reach the electronic speed limit of 250 km/h.
The first generation V 12 was developed based on two 6-cylinder powerplants, and its development started with 1982, which is the first time in BMW's history to produce 12 cylinder engines. At that time, the crankcase was made of aluminum-silicon alloy and the piston was cast iron. The coating on the cylinder surface is high-hardness silicon crystal, which minimizes wear. DME control unit separates each row of cylinders. This means that all related systems such as butterfly valve, air flow meter, control unit and fuel pump must be assembled twice. 1994, when the second generation BMW 7 Series appeared, a brand-new V 12 engine followed. With the increase of stroke and cylinder diameter, the engine displacement increased from 5.0 liters to 5.4 liters, the output power was 240 kW (325 HP), and the maximum torque was 490 Nm. However, this more complicated V 12 pays more attention to fuel economy and emission control: under the comprehensive road conditions of three speeds (90 km/h and 120 km/h), the fuel consumption per 100 kilometers of the 750i is only 1 1.9 liter, which is much lower than the previous 23.7 liter/. With a capacity of 200 1 year, BMW introduced the 750iL with a 12 cylinder engine powered by Vl2, 5.4-liter single overhead camshaft and a 2-valve engine per cylinder. The maximum power of this engine is 240 kW (326 HP), which is the same as the current 7 Series V8 engine. The V 12 engine used by 760Li this time is brand-new, with 6.0 liter displacement, double overhead camshafts and 4 valves per cylinder.