Här får ni se hur dom vanligaste motorerna fungerar även 2olika bränsle system. Kolla spoilern under varje animation för en genomgång (på engelska) hur dom fungerar.
Motorer
All ära till Matt Keveney för dessa fina animationer och förklaringar!
The four stroke engine was first demonstrated by Nikolaus Otto in 18761, hence it is also known as the Otto cycle. The technically correct term is actually four stroke cycle. The four stroke engine is probably the most common engine type nowadays. It powers almost all cars and trucks.
The four strokes of the cycle are intake, compression, power, and exhaust. Each corresponds to one full stroke of the piston; therefore, the complete cycle requires two revolutions of the crankshaft to complete.
Larger four stroke engines usually include more than one cylinder, have various arrangements for the camshaft (dual, overhead, etc.), sometimes feature fuel injection, turbochargers, multiple valves, etc. None of these enhancements changes the basic operation of the engine.
Intake
During the intake stroke, the piston moves downward, drawing a fresh charge of vaporized fuel/air mixture. The illustrated engine features a poppet intake valve which is drawn open by the vacuum produced by the intake stroke. Some early engines worked this way; however, most modern engines incorporate an extra cam/lifter arrangement as seen on the exhaust valve. The exhaust valve is held shut by a spring (not illustrated here).
Compression
As the piston rises, the poppet valve is forced shut by the increased cylinder pressure. Flywheel momentum drives the piston upward, compressing the fuel/air mixture.
Power
At the top of the compression stroke, the spark plug fires, igniting the compressed fuel. As the fuel burns it expands, driving the piston downward.
Exhaust
At the bottom of the power stroke, the exhaust valve is opened by the cam/lifter mechanism. The upward stroke of the piston drives the exhausted fuel out of the cylinder.
The two stroke engine employs both the crankcase and the cylinder to achieve all the elements of the Otto cycle in only two strokes of the piston.
Since the two stroke engine fires on every revolution of the crankshaft, a two stroke engine is usually more powerful than a four stroke engine of equivalent size. This, coupled with their lighter, simpler construction, makes the two stroke engine popular in chainsaws, line trimmers, outboard motors, snowmobiles, jet-skis, light motorcycles, and model airplanes.
Unfortunately, most two stroke engines are inefficient and are terrible polluters due to the amount of unspent fuel that escapes through the exhaust port.
Intake
The fuel/air mixture is first drawn into the crankcase by the vacuum that is created during the upward stroke of the piston. The illustrated engine features a poppet intake valve; however, many engines use a rotary value incorporated into the crankshaft.
Crankcase compression
During the downward stroke, the poppet valve is forced closed by the increased crankcase pressure. The fuel mixture is then compressed in the crankcase during the remainder of the stroke.
Transfer/Exhaust
Toward the end of the stroke, the piston exposes the intake port, allowing the compressed fuel/air mixture in the crankcase to escape around the piston into the main cylinder. This expels the exhaust gasses out the exhaust port, usually located on the opposite side of the cylinder. Unfortunately, some of the fresh fuel mixture is usually expelled as well.
Compression
The piston then rises, driven by flywheel momentum, and compresses the fuel mixture. (At the same time, another intake stroke is happening beneath the piston).
At the top of the stroke, the spark plug ignites the fuel mixture. The burning fuel expands, driving the piston downward, to complete the cycle. (At the same time, another crankcase compression stroke is happening beneath the piston.)
The Wankel rotary engine is a fascinating beast that features a very clever rearrangement of the four elements of the Otto cycle. It was developed by Felix Wankel in the 1950s.
In the Wankel, a triangular rotor incorporating a central ring gear is driven around a fixed pinion within an oblong chamber.
The rotary motion is transferred to the drive shaft by an eccentric wheel (illustrated in blue) that rides in a matching bearing in the rotor. The drive shaft rotates once during every power stroke instead of twice as in the Otto cycle.
The Wankel promised higher power output with fewer moving parts than the Otto cycle engine; however, technical difficulties interfered with widespread adoption. In spite of valiant efforts by Mazda, the four stroke engine remains much more popular.
Intake
The fuel/air mixture is drawn in the intake port during this phase of the rotation.
Jag tycker detta är bra för er som sitter och funderar ;)
2010-12-27, 02:19
pAd105
Kanon sammanfattning av bilder, detta gillas!
2010-12-27, 15:00
Rexxy
Den första animationen är ju felgjord gällande brytaren. Gnistan ska ju komma när brytaren öppnar, inte när det stänger? Så är det i alla fall på mopeder, kanske annorlunda på bil...?
