Two Stroke And Four Stroke Engine

Two Stroke And Four Stroke EngineTo understand the differences between a two snap and cardinal bias locomotives, we need to know how the four stroke engine subject fields. In four stroke engine there ar four stagesIntake The plumbers helper travels down the cylinder while the intake valve is opened to allow a change of exit and air to enter the burning bedroom.Compression The intake valve is closed and the piston travels back up the cylinder compressing the shove offses.Combustion The spark plug ignites the compressed gas causing it to explode, which forces the piston down.Exhaust The piston rises up the cylinder as the erase valve is opened, allowing the piston to clear the chamber to start the mental process over.Each time the piston rises and locomote it turns the crankshaft that is responsible for turning the wheels. This is how fuel is converted into forward motion.The spark plug doesnt fire in each revolution but instead fires at once all(prenominal) other rev olution. A camshaft must alternately tip a rock n roll musician arm attached either to the intake or work over valve. The rocker arm returns to its closed position according to the movement of a spring. The valves must be seated properly in the cylinder head to avoid calculus leaks.Now that the four stroke engines mechanism is explained, it is inevitable to learn about the two stroke engine. The main difference between the two engines is that all four stages in the four stroke engine be integrated into only two phases, one downward stroke, and one upward stroke. Intake and exhaust are both integrated into the compression and combustion movement of the piston, eliminating the need for valves. This is accomplished by an gateway and exhaust port in the wall of the combustion chamber itself.Induction the piston travels down the cylinder head, and it applies suction to the air-fuel mixture and exerts it into the cylinder.Compression as the piston travels up to the top of the cylinde r head, it applies pressure to the air-fuel mixture from the inlet port in the top of the cylinder head, making the air-fuel mixture ready for igniting by the spark plug.Ignition the spark plug ignites the pressurized air-fuel mixture (otherwise known as the compressed air-fuel mixture), sometimes referred to as the power stroke.Exhaust as the piston returns back to the top of the cylinder head after the air-fuel mixture has been ignited, the piston pushes the destroy gases out of the cylinder and through the exhaust system.Transfer Port The port in a two stroke engine that transfers the air-fuel mixture from the bottom of the engine to the top of the cylinder.two-stroke-exhaust.gif 0003EDA6CENGIZ B9A1592CFig2 2-Stroke engineAfter the fuel and air experience a relatively weakened explosion, the piston is driven down to the bottom of the stroke where the exhaust port is uncovered. Most of the gases are driven out in this phase. This process is easily seen with an outboard motorboat , evident by the multicoloured oil slick ring the engine, but it happens with all two stroke engines, which is considered one of the disadvantages that makes a designer overlook the use of a two stroke engine in their design. And that is because this process itself (a dogged with burning oil) creates pollution and fuel efficiency issues.DevelopmentThe idea to build a two-stroke engine goes back to the year 1879. But this engine became a qualitatively good product only after many years, when the German DKW company accelerated its development. Because of its disadvantages compared with the four-stroke engine, the two-stroke engine is used practically just in a small range of capacity, e.g. in small motorcycles considering that the processes involved in the two stroke engine only require the use of a small amount of move and chambers, and that is why they are used in small applications. Formerly the engine was even used to power tiny cars.The main disadvantage of the two stroke engin e would be the loss of fuel and oil (as oil is mixed with fuel, or induced with fresh air to lubricate the piston). And this oil is burnt and send through the exhaust, as some of the fresh mixture would leave the combustion chamber unburnt. This would basically cause more emissions and dirtier exhaust that would damage the catalytic converter.In recent years, the re-appearance of direct fuel injectant (as it already existed in diesel, and 1960s petrol Mercedes), is the main cause of this interest. As direct fuel injection (meaning the fuel injector would be in the combustion chamber such as the spark plug, and would induce the fuel directly in there, as opposed to standard injection where fuel is induced in the intake manifold on top of the valve). This direct injection would limit the fresh mixture loss in exhaust.The caloric post combustion there is an air pump, called secondary air pump, pumping fresh air into the exhaust when engine is cold. As on cold starts you have a very r ich mixture, meaning raw fuel leaving through the exhaust. The fresh air induced, along with the high temperatures of the exhaust, would cause the fuel in exhaust to burn, this would render the emissions cleaner, and would heat up the exhaust faster for the catalytic converter and oxygen sensors to work (as catalytic converters and oxygen sensors need temperatures around 600 degrees C to croak and clean the emissions).This thermal post combustion would clean the remaining raw fuel or hydrocarbons, and heat the catalytic converters and oxygen sensors, so they forever and a day work at optimal temperatures.Problems of the two-stroke engineActually, the two stroke engine should perform double the performance of a four stroke engine with the same cube-shaped capacity. Although it is just possible to gain a performance that is about 50% better, but still the reasons are obvious the cylinder cannot be filled up with the same amount of fuel as in the four-stroke engine, because the indi vidual strokes are separated not so clearly which will reduce the amount of plaza and eventually reduce the capacity for carrying more fuel. If more fuel is induced, it leaves the combustion chamber through the ejection pipe without being burnt. Many concepts were developed to provide a better expulsion of the exhaust in way that the fresh gas doesnt leave the combustion chamber. Though all these inventions, the filling of the two-stroke engine is always worse than in the four-stroke engine, which loses fresh fuel only because of the overlap of the valve times (both valves are open for an instant). Beside these performance-technical problems, there are also increasing difficulties with the environment. The fuel mixture of the two-stroke engine often gets shifted with a certain quantity of oil because of the necessary lubrication. Unfortunately the oil gets burnt partly, too, and harmful gases are expulsed by the engine.Two stroke engines already have a lot of advantages over the st andard four stroke enginesTwo-stroke engines do not have valves, which simplifies their construction and lowers their weight.Two-stroke engines fire once every revolution, while four-stroke engines fire once every other revolution. This gives two-stroke engines a significant power boost. Two-stroke engines are lighter, and cost less to manufacture. Two-stroke engines have the potential for about twice the power in the same size because there are twice as many power strokes per revolution.Disadvantages of 2 Stroke Engines-Two-stroke engines dont live as long as four-stroke engines. The lack of a dedicated lubrication system means that the parts of a two-stroke engine wear-out faster. Two-stroke engines require a mix of oil in with the gas to lubricate the crankshaft, connecting rod and cylinder walls. Two-stroke oil can be expensive. Mixing ratio is about 4 ounces per gallon of gas burning about a gallon of oil every 1,000 miles. Two-stroke engines do not use fuel efficiently, yieldi ng fewer miles per gallon. Two-stroke engines produce more pollution from1- The combustion of the oil in the gas. The oil makes all two-stroke engines smoky to some extent, and a badly worn two-stroke engine can emit more oily smoke.2- Each time a new mix of air/fuel is loaded into the combustion chamber, part of it leaks out through the exhaust port.http//www.deepscience.comhttp//www.whitedoglubes.comhttp//www.atzonline.com/index.phpdo=show/site=a4e/sid=10470432604d6722a19884c564334027/alloc=3/id=829