romero2005
03-31-2008, 04:09 AM
The rotary engine works on the four-stroke principle. Läuft der Kolben am Einlassschlitz vorbei, wird durch Volumenzunahme des Arbeitsraumes eine dem Kammervolumen entsprechende Menge Kraftstoff -Luft-Gemisch angesaugt. Runs on the piston inlet slot past, by volume growth of a working space the chamber volume corresponding amount of fuel-air mixture applied. Durch den bei der weiteren Drehung des Kreiskolbens immer kleiner werdenden Arbeitsraum wird das Kraftstoff-Luft-Gemisch im zweiten Arbeitstakt verdichtet. Through the in the further rotation of the circle piston always smaller work space, the fuel-air mixture in the second work cycle summarized. Nach dem Gasgesetz erwärmt es sich bereits durch die Verdichtung. After the heated gas is already covered by the compaction. Wenn das Kraftstoff-Luft-Gemisch seine höchste Dichte erreicht und die Zündkerze passiert hat, wird das Gemisch gezündet. If the fuel-air mixture reaches its highest density and the spark plug has happened, the mixture is ignited. Die bei der Verbrennung freiwerdende Wärme führt zu einer Druckzunahme , wodurch am Kreiskolben nutzbare Arbeit verrichtet wird. The released by the combustion heat leads to an increase in pressure, making the rotary usable work. Bei dieser Drehung des Arbeitsraumes vergrößert sich das Brennraumvolumen wieder. This rotation of the work space increases the combustion chamber volume. Man spricht dabei vom Arbeitstakt. It speaks of working stroke.
For More click here (http://translate.google.com/translate?hl=en&sl=de&u=http://de.wikipedia.org/wiki/Wankelmotor&sa=X&oi=translate&resnum=3&ct=result&prev=/search%3Fq%3DWankelmotor%26hl%3Den%26sa%3DG)
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How RX8 engine works
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Disadvantages
Compared to four stroke piston engines, the time available for fuel to be injected into a Wankel engine is significantly shorter, due to the way the three chambers rotate. The fuel-air mixture cannot be pre-stored as there is no intake valve.
In terms of fuel economy, Wankel engines are less efficient than four stroke piston engines[citation needed].
The surface/volume-ratio problem is so complex that one cannot make a direct comparison between a reciprocating piston engine and a Wankel engine in relation to the surface/volume-ratio. The flow velocity and the heat losses behave quite differently. Surface temperatures behavior absolutely different, the film of oil in the Wankel engine acts as isolator. Engines with higher compression ratio have a worse surface/volume-ratio. The surface/volume-ratio of a Diesel engine is much worse than a gasoline engine, but Diesel engines are well known for a higher efficiency factor than gasoline engines. Thus we should compare engines with equal power: a naturally aspirated 1.3 liter Wankel engine with a naturally aspirated 1.3 liter four stroke reciprocating piston engine with equal power. But such a four stroke engine is not possible and needs twice the displacement for the same power as a wankel engine. The extra or "empty" stroke(s) we should not ignore, as a 4-stroke cylinder produces a power stroke only every other rotation of the crankshaft. In actuality, this doubles the real surface/volume-ratio for the four stroke reciprocating piston engine. [9]
Also, problems occur with exhaust gases at a peripheral port exhaust, where the prevalence of hydrocarbon can be higher than from the exhausts of four stroke piston engines.
The trailing side of the rotary engine’s combustion chamber develops a squeeze stream which pushes back the flamefront. With the conventional two-spark-plug or one-spark-plug system, this squeeze stream prevents the flame from propagating to the combustion chamber's trailing side in the mid and high engine speed ranges. This is why there can be more carbon monoxide and unburnt hydrocarbons in a Wankel's exhaust stream. A side port exhaust, as is used in the Mazda Renesis, avoids this because the unburned mixture cannot escape. The Mazda 26B avoided this issue through a 3-spark plug ignition system. (As a result, at the Le Mans 24 hour endurance race in 1981, the 26B had significantly lower fuel consumption than the competing reciprocating piston engines. All competitors had only the same amount of fuel available, because of the Le Mans 24h limited fuel quantity rule.[10])
All Mazda-made Wankel rotaries, including the new Renesis found in the RX8 burn a small quantity of oil by design; it is metered into the combustion chamber in order to preserve the apex seals. Owners must periodically add small amounts of oil, slightly increasing running costs; though it is still reasonable when compared to many reciprocating piston engines.
For More click here (http://translate.google.com/translate?hl=en&sl=de&u=http://de.wikipedia.org/wiki/Wankelmotor&sa=X&oi=translate&resnum=3&ct=result&prev=/search%3Fq%3DWankelmotor%26hl%3Den%26sa%3DG)
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How RX8 engine works
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Disadvantages
Compared to four stroke piston engines, the time available for fuel to be injected into a Wankel engine is significantly shorter, due to the way the three chambers rotate. The fuel-air mixture cannot be pre-stored as there is no intake valve.
In terms of fuel economy, Wankel engines are less efficient than four stroke piston engines[citation needed].
The surface/volume-ratio problem is so complex that one cannot make a direct comparison between a reciprocating piston engine and a Wankel engine in relation to the surface/volume-ratio. The flow velocity and the heat losses behave quite differently. Surface temperatures behavior absolutely different, the film of oil in the Wankel engine acts as isolator. Engines with higher compression ratio have a worse surface/volume-ratio. The surface/volume-ratio of a Diesel engine is much worse than a gasoline engine, but Diesel engines are well known for a higher efficiency factor than gasoline engines. Thus we should compare engines with equal power: a naturally aspirated 1.3 liter Wankel engine with a naturally aspirated 1.3 liter four stroke reciprocating piston engine with equal power. But such a four stroke engine is not possible and needs twice the displacement for the same power as a wankel engine. The extra or "empty" stroke(s) we should not ignore, as a 4-stroke cylinder produces a power stroke only every other rotation of the crankshaft. In actuality, this doubles the real surface/volume-ratio for the four stroke reciprocating piston engine. [9]
Also, problems occur with exhaust gases at a peripheral port exhaust, where the prevalence of hydrocarbon can be higher than from the exhausts of four stroke piston engines.
The trailing side of the rotary engine’s combustion chamber develops a squeeze stream which pushes back the flamefront. With the conventional two-spark-plug or one-spark-plug system, this squeeze stream prevents the flame from propagating to the combustion chamber's trailing side in the mid and high engine speed ranges. This is why there can be more carbon monoxide and unburnt hydrocarbons in a Wankel's exhaust stream. A side port exhaust, as is used in the Mazda Renesis, avoids this because the unburned mixture cannot escape. The Mazda 26B avoided this issue through a 3-spark plug ignition system. (As a result, at the Le Mans 24 hour endurance race in 1981, the 26B had significantly lower fuel consumption than the competing reciprocating piston engines. All competitors had only the same amount of fuel available, because of the Le Mans 24h limited fuel quantity rule.[10])
All Mazda-made Wankel rotaries, including the new Renesis found in the RX8 burn a small quantity of oil by design; it is metered into the combustion chamber in order to preserve the apex seals. Owners must periodically add small amounts of oil, slightly increasing running costs; though it is still reasonable when compared to many reciprocating piston engines.