V 12 engine
In my opinion, the symbolic meaning of V 12 engine is greater than the actual meaning. 12-cylinder engine cars are mainly concentrated in Europe, with top luxury cars in Germany and Britain and top sports cars in Italy as the mainstay. The technology of V 12 engine is complex, expensive, extremely heavy, and the fuel consumption is so high that you can't find the official data provided by the manufacturer. Also, how can people who buy this kind of car care about its fuel consumption!
At present, luxury cars equipped with V 12 engines are: Mercedes-Benz flagship S600, BMW flagship 760Li, Maibakh and Rolls-Royce new phantom; Sports cars equipped with V 12 engines include Ferrari's 456GT and Enzo, Lamborghini's Devil and Murcielago, Aston Martin's V 12 Vanquish, Bugatti's EB 16-4 and Edonis's BEX38.
Audi is currently one of the manufacturers of 12-cylinder dual V-type or W-type series engines. The design principle of W-type engine has a very remarkable feature: although there are many cylinders and large displacement, the volume of the new engine W 12 is as big as that of V8, but much smaller than that of the traditional engine V 12.
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Features of the new engine W 12 Compared with the previous technology, the new Audi 12 cylinder engine has unparalleled advantages. It has compact structure, strong power and light weight. Because this engine is only 5 13mm long and 690mm wide, it is installed in front of the car and can be combined with the four-wheel drive system. However, other types of 12 cylinder engines can only match the rear wheel drive system because of their large size. Because there is not enough space in the lower part of the engine in front of the car to accommodate the front wheel drive components.
The compact design of the new engine W 12, coupled with the use of light metal materials such as aluminum alloy, gives this 12 cylinder engine another advantage, that is, light weight. The weight of Audi A8 L6.0 quattro dropped to 1980kg, which was lower than all other models. The car only needs 4.7kg per horsepower to accelerate, which is equivalent to a high-performance sports car.
Compared with the previous design, this engine is not a classic W 12 engine, because it does not adopt a three-row split configuration, but puts three connecting rods on the same crankshaft pin. This new 12 cylinder engine jointly developed by Audi and Volkswagen is really different.
If you pay attention to the cylinder arrangement of the engine, you will find that the machine is composed of two groups of subminiature V6 assemblies. Each group has six cylinders arranged at an angle of15. This offset arrangement has the advantages of a classic V6 4 cylinder engine, and its width and length are minimized.
Another advantage of connecting the two rows of cylinders at 72 is that the height of the engine is significantly reduced, which means that the front profile of the car can be designed to be flatter and more streamlined. Another advantage is that it brings a unique sense of movement to luxury cars, which is perhaps what people want most.
The core component of engine W 12 is a seven-bearing crankshaft transmission, which weighs only 20.5kg, and the crankshaft pin is offset, so it can maintain a constant ignition sequence like V6 engine. The overall rigidity of this engine is also unusual. The comfort brought by its excellent vibration resistance even exceeds the expected level of 12 cylinder engine.
Dry lubrication system In order to ensure extraordinary performance, Audi W 12 engine adopts dry lubrication system. The biggest advantage of dry lubrication system is that it can provide lubricating oil to the engine in the best way even in the state of high lateral acceleration. It is different from the ordinary wet lubrication system, and the oil pump provides lubricating oil to the engine from a separate oil tank. This method is more convenient to realize optimal design than the ordinary method.
The lubricating oil tank of Audi W 12 engine is located behind the right front headlight and connected to the engine through two hoses. The oil pump is driven by a chain directly connected to the crankshaft. The water cooling system on the left side of the engine can ensure the sufficient cooling of lubricating oil. This system is rarely used in production cars and can only be used in high-end sports cars.
Optimizing design to reduce exhaust emissions Double overhead camshafts on each row of cylinders are responsible for controlling valve movement. Camshafts are driven by the same chain, and two intake valves and two exhaust valves of each cylinder are operated by roller cam followers with low friction coefficient. This design principle helps to significantly reduce fuel consumption. The adjustable range of the variable valve timing device is very wide, and the intake valve 52 and the exhaust valve 22. This means that the best valve opening time can be achieved in the whole engine speed range, at the same time, good idle emission can be achieved, the emission of incomplete combustion particles can be reduced, and sufficient torque can be maintained in the whole engine speed range.
The oil-gas mixing is completed by Bosch Motoronic ME 7.1.1electronic sequential fuel injection system. The device includes electronic valve control, hot film air flowmeter and variable air-fuel ratio control. Four knock sensors can accurately detect the cylinder that produces knock.
The exhaust emission control of the engine mainly depends on four three-way catalytic converters installed near the engine and two main catalytic converters installed in the muffler. Eight self-heating oxygen sensors continuously monitor the exhaust gas. Therefore, such a powerful engine can easily meet the requirements of Euro III standard for exhaust emission.
There is no doubt that 12 cylinder is worthy of the name, and the charm of 12 cylinder engine lies in its special acoustic quality to a great extent. Therefore, these special acoustic requirements are also attached great importance in the development process.
This requirement is manifested in the excellent and extremely low vibration quality at idle speed, especially during partial load acceleration and constant speed. At the same time, the acoustic engineer designed a dynamic, powerful and elegant audio mode for the engine under partial load acceleration. This unique audio design combines the highest sound quality with warm emotional colors, and becomes a typical feature to show the excellent overall performance of vehicles.
The basis of the above excellent acoustic quality is that the engine can run smoothly, and the latter is attributed to the following components: the crankshaft and camshaft drive system with the best power design, and the connecting parts between the crankcase and the transmission mechanism with special rigidity. Finally, thanks to the careful acoustic fine-tuning of the engine by the design engineer, the intake pipe, exhaust system and the assembly of these components have reached a perfect combination.
As the core component of the extended Audi A8, the new 12 cylinder engine made its debut at this year's Paris International Auto Show. It is powerful, unique and full of energy, which makes Audi's flagship A8 sedan a symbol of Audi's design concept.