英语论文网

cle within a piston engine. 'Only 20% of the cycle is power, which results in a power lag 80% of the time which is spent on compressing gasses and a heavy flywheel must compensate for the lag.' (QT Theory Piston Differences) This is where a continuous combustion would be ideal, as found in the Quasiturbine engine.

The Saint-Hilaire family created the Quasiturbine engine in 1996 after intense research and development. This engine is similar to the Wankel rotary engine in that it involves a rotor and housing, but it utilizes a four-blade carriage mechanism compared to the Wankel's three. The four blades rotate about an oval housing with a chain-like motion. At each pivot there is a carriage which houses two wheels, allowing the engine to operate with little to no oil since friction is almost absent. The eight wheels make a tight seal against the housing and create four sealed chambers in which the intake, compression, combustion, and exhaust cycles can occur. 'In a piston engine, one complete four-stroke cycle produces two complete revolutions of the crankshaft. That means the power output of a piston engine is half a power stroke per one piston revolution. A Quasiturbine engine, on the other hand, does not need pistons. Instead, the four strokes of a typical piston engine are arranged sequentially around the oval housing. There is no need for the crankshaft to perform the rotary conversion, yet an output shaft is attached to the rotor by two coupling shafts so it can power an automobile.' (Harris)

Most, if not all gasoline engines use an electrical ignition source. This process produces a flame front which results in an unburned fuel mixture at high rpm, thus reducing the engines efficiency. To combat this, Rudolf Diesel created a piston engine which ignited fuel using high compression. This proved to be more efficient than gasoline engines; however, more pollutants resulted from unburned diesel fuel. There have been recent advancements in Diesel after treatment systems like urea injection and advanced catalyst reduction, but that adds weight and cost to the vehicle. Like the diesel, the Quasiturbine engine can run without an ignition source. Unlike diesels, the QT can operate on gas. The advantage of this high compression cycle results in a more complete combustion without the risks of detonation, thus reducing emissions and eliminating the need for complex after treatment systems. Detonation is premature ignition within piston engines and can cause severe damage. Interestingly, fuel is burned well in detonation situations. (QT Theory Piston Differences)

An improved version of the QT engine has been developed which incorporates photo-detonation as an ignition source. Photo-detonation is a process in which a homogenous air/fuel mixture is spontaneously ignited from tremendously high compression. The result is virtually no emissions and superior fuel efficiency. (Harris) This in turn would eliminate the use of a catalytic converter. Photo-detonation places a significant amount of stress on an engine. General Motors has been experimenting with photonic detonation (or HCCI); however, they are testing it on piston engines. These engines were not designed to endure this combustion process as they are susceptible to detonation and as a result, GM has only been successful at sustaining HCCI for short durations within piston engines. HCCI can however, occur in the QT engine because of its strong and c