07-09-2012, 10:52 PM
I am Mr. Bhabani Prasad Mishra ,mechanical engg student of ghitm under BPUT in 7th sem.
I want a detail description about valvetronics to attend in seminar class
07-09-2012, 10:52 PM
I am Mr. Bhabani Prasad Mishra ,mechanical engg student of ghitm under BPUT in 7th sem. I want a detail description about valvetronics to attend in seminar class
17-11-2012, 11:14 AM
VALVETRONICS VALVETRONICS.pptx (Size: 381.46 KB / Downloads: 42) What Is Valvetronic.?. The Valvetronic engine is the world's first engine without a throttle butterfly. Valvetronic allows the engine to run without a throttle butterfly, the cylinder charge being determined under part load as a function of the valve-opening period. The intake and outlet camshafts are driven by variable cam adjustment, BMW’s Vanos technology. A further advantage of this concept is that it allows worldwide use of the proven three-way catalyst for emissions management, thus meeting even the strictest emissions standards in the US.Innovative technology was essential in order to reach the demanding objectives and functional requirements desired. However, at the same time, this concept demanded the utmost of the electronic control and management systems in the engine. Concept Taking nature as the role model: human beings also apply the Valvetronic principle A comparison with the human being clearly explains how Valvetronic works: Whenever we are required to make a great effort, we human beings breathe in a deep and long process of ventilation. Whenever we need less air, we do not throttle the supply of air by, say, closing our nose or our mouth, but simply breathe in a shorter, flatter process of ventilation. In a conventional combustion engine the throttle butterfly is basically comparable to a human being keeping his nose or mouth at least partially closed. With its large valve lift ( deep, long ventilation) and short valve lift ( flat, short process of ventilation), Valvetronic, on the other hand, is able to breathe in the same way as nature – always in line with current requirements, without any kind of throttling effect and therefore with maximum efficiency. Valvetronic Technology Accordingly, the Valvetronic engine no longer requires a throttle butterfly, which has quite literally restricted the free ventilation of the internal combustion engine ever since its invention. Now Valvetronic replaces this conventional function by infinitely variable intake valve lift, offering a quantum leap in technology quite comparable to the changeover from the carburetor to fuel injection. Its most important feature is that it is able to save at least 10 % fuel throughout the entire operating range relevant to the customer, with a corresponding reduction in exhaust emissions, regardless of fuel quality. And a further important point is that the efficient operation of Valvetronic does not require any unusual types and grades of oil possibly difficult to obtain. The Valvetronic system is based consistently on BMW’s proven double-VANOS (VANOS = variable adjustment of the camshafts), with infinite camshaft adjustment to meet specific requirements. The additional, variable valve lift adjusts the effective cam action and, accordingly, the opening cross-section of the valves. This is done by a lever positioned between the camshaft and the intake valves, its distance from the camshaft being adjusted infinitely by an additional eccentric shaft operated by an electric motor. Depending on the position of the Valvetronic control system, the lever converts the cam contour into a larger or smaller valve lift, whatever may be required. Principle of Operation The Valvetronic system is a combination of VANOS and valve lift adjustment. This combination of abilities allows the ECM to control when the intake valves are opened and closed, and also the opening lift. The intake air flow is set by adjusting the valve lift while the throttle valve is fully opened. This improves cylinder filling still further and reduces fuel consumption Advantages Anti-knock control for running on all fuel grades between 87 and 99 octane. Maintenance-free ignition system with individual coils. Maintenance-free valve drive with hydraulic valve play compensation. A Service Interval Indicator to keep the cost of service to a minimum A two-mass flywheel for maximum running smoothness Valve drive with roller bearings throughout in the interest of minimum friction and fuel consumption. Advanced catalysts near the engine in special manifold design for minimum emissions. In Valvetronic engines coolant flows across the head, resulting in a temperature reduction of 60%. The water pump size is cut in half, reducing power consumption by 60%. The power steering fluid is warmed quickly, reducing the power used by the hydraulic pump. Mounting the water and power pump on the same shaft and a heat exchanger between coolant and engine oil reduces oil temperature by 30%. Disadvantages Facing such a high standard of software and hardware complexity, a manufacturer obviously also runs a greater risk of making mistakes. It is essential to acquire a sufficient stock of data under all kinds of operating conditions in order to understand how such a new system behaves. However, such data cannot be provided by the usual sequential test runs. All-round, general use of the latest direct-injection technology, in turn, faces some significant drawbacks such as costs, the need to make the combustion process very robust and the potentials in exhaust emissions treatment. CONCLUSION In summary, these innovative developments provide a combination of product features thus far inconceivable with a spark-ignition engine. The introduction of the world’s first intake manifold providing infinite variation in manifold length serves to improve the torque level, which is already very good to begin with. A particular highlight of engines with Valvetronic load management is the significantly improved fuel/air mixture guaranteeing minimum fuel consumption, maximum spontaneity and optimum refinement. DFI with a stochiometric air/fuel ratio provides the highest level of specific output as well as a combustion process helping to fulfill all exhaust emissions standards worldwide. All-round, general use of the latest direct-injection technology, in turn, faces some significant drawbacks such as costs, the need to make the combustion process very robust and the potentials in exhaust emissions treatment. Valvetronic combines a significant improvement of fuel consumption with excellent engine response and control, allowing optimum valve timing under all running conditions. The result is smooth and free operation of the engine under part load with very little throttle effect. Optimized fuel/air mixture management ensures significant advantages in fuel efficiency compared with a conventional four-cylinder engine, reaching the same standard as today’s lean-burn concepts. Since such an engine with Valvetronic does not require an NOx removal catalyst, it can be used worldwide with all types and grades of fuel. |
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