Cylinder Deactivation is a method used to create a variable displacement engine that is able to supply the full power of a large engine under high load conditions as well as the fuel economy of a small engine for cruising.
VARIABLE DISPLACEMENT TECHNOLOGY
Variable displacement is an automobile engine technology that allows the engine displacement to change, by deactivating cylinders, for improved fuel economy. The technology is primarily used in large, multi-cylinder engines. Many automobile manufacturers have adopted this technology as of now, but it is not a new concept. Most variable displacement systems work by turning off a bank of cylinders in a V engine.
The oldest engine technological predecessor for the variable-displacement engine is the hit and miss engine, developed in the late 19th century. These single cylinder stationary engines had a centrifugal governor that cut the cylinder out of operation so long as the engine was operating above a set speed, typically by holding the exhaust valve open.
IMPORTANCE
Cruising down the highway your car is traveling at a set speed not needing the full use of all of its engine power, but eating up precious fuel nevertheless. That V6 or V8 under the hood could be much more efficient if it employed one important piece of modern day technology: cylinder deactivation.
Elevated fuel prices have made consumers scrambling for answers. Some are switching to hybrids, others to diesel, while still others are choosing smaller and lighter vehicles all in a bid to save on fuel. While no one quite knows what the long term fuel prices will be, automotive manufacturers are able to squeeze out better fuel mileage through a rather simple technological change: cylinder deactivation. Cylinder deactivation works this way: let’s say you are cruising down the interstate at a set speed of about 65 miles per hour. The road surface is flat therefore there isn’t a whole lot of demand on your engine. Instead of running all six or eight cylinders, why not run your engine on three or four?
CYLINDER DEACTIVATION
Cylinder Deactivation is a method used to create a variable displacement engine that is able to supply the full power of a large engine under high load conditions as well as the fuel economy of a small engine for cruising.
The idea of cylinder deactivation is becoming increasing popular as car manufacturers strive to reduce fuel consumption. Cylinder deactivation effectively creates a variable displacement engine, which means you can enjoy the on-demand power of a large capacity engine together with the fuel economy of a smaller engine.
Cylinder deactivation is used to reduce the fuel consumption and emissions of an engine during light load operation. In typical light load driving the driver uses only around 30 percent of an engine’s maximum power. In these conditions, the throttle valve is nearly closed and the engine needs to work to draw air. This causes an inefficiency known as pumping loss. Some large capacity engines need to be throttled so much at light load that the cylinder pressure at top dead centre is approximately half that of a small 4 cylinder engine. Low cylinder pressure means low fuel efficiency. The use of cylinder deactivation at light load means there are fewer cylinders drawing air from the intake manifold which works to increase its fluid (air) pressure. This reduces pumping losses and increases pressure in each operating cylinder. Fuel consumption can be reduced by around 20 percent in highway conditions.
Nowadays cylinder deactivation is becoming more popular and accepted. This process is employed in several vehicles; different engine manufacturing firms use different abbreviations for this same process, they are:
General Motors- Active Fuel Management (AFM)
DaimlerChrysler- Multi-Displacement System (MDS) (for Chrysler)
DaimlerChrysler -Active Cylinder Control (ACC) (for Mercedes-Benz)
Honda- Variable Cylinder Management (VCM)
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