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The Atkinson cycle in practice. The engine on the Atkinson cycle

ICE has been used on cars for a century. In general, the principle of their work has not undergone major changes since the beginning of the issue. But since this engine has a lot of shortcomings, engineers do not stop inventing innovations to improve the motor. Let us turn to the one of them, which is called the Atkinson cycle. Today you can hear that in some machines it is applied. But what is it like and how does the engine get better with it?

The Atkinson Cycle

Nikolaus Otto, an engineer from Germany, proposed in 1876 a cycle consisting of:

  • Admission;
  • Compression;
  • Working stroke;
  • Release.

A decade later, the English inventor James Atkinson developed it. However, figuring out the details, you can call the completely original view the Atkinson cycle .

Internal combustion engines are qualitatively different. After all, the crankshaft has biased attachment points, so that the energy lost in friction is reduced, and the compression ratio is increased.

Also on it there are other gas-distributing phases. On a conventional engine, the piston closes immediately after passing through the dead center. Another scheme has the Atkinson cycle. Here the cycle is much longer, since the valve closes only half way through the piston to the top dead center (where Otto already compresses).

Theoretically, the Atkinson cycle is more effective than Otto by about ten percent. However, it was not used for a long time in practice, because it is able to function in the operating mode only at high speeds. In addition, a mechanical supercharger is needed, which is sometimes referred to as the "Atkinson-Miller cycle". However, it turned out that with him the advantages of the development in question were lost.

Therefore, in cars, such a cycle of Atkinson in practice is almost not used. But in hybrid models, like the Toyota Prius, manufacturers began to use it even serially. This was made possible by the specific work of these types of engines: at a low speed the car moves by electric traction and only when it accelerates passes to the gasoline unit.

Timing

The first engine in the Atkinson cycle had a cumbersome gas distributing mechanism, producing a great deal of noise. But when, thanks to the discovery of the American Charles Knight, instead of the usual valves with a drive, special spools were used in the form of a pair of cartridge cases, which were arranged between the cylinder and the piston, the motor almost ceased to make noise. However, the complexity of the design used was quite expensive, but in the prestigious brands of cars, car owners were willing to pay for such convenience.

Nevertheless, already in the thirties, such an improvement was abandoned, because the engines were short-lived, and the consumption of gasoline and oil was too high.

Engine development in this direction is known today - maybe engineers will be able to get rid of the shortcomings of the Charles Knight model and take advantage of the advantages.

Universal model of the future

Currently, many manufacturers are developing universal engines, which will combine both the power of gasoline units, and the excellent thrust and economy of diesel engines.

In this respect, the fact that gasoline units with direct fuel injection have reached a high compression ratio of about thirteen to fourteen units (diesel engines have a little more than seventeen to nineteen), proves successful steps in this direction. They even work in the same way as compression ignition units. Only the working mixture must be artificially ignited by a candle.

In experimental models, compression is even higher - up to fifteen to sixteen units. But until the autoignition until the level is not reached. But the candle is turned off at a uniform movement, so that the engine switches to a diesel-like mode and consumes little fuel.

Burning is regulated by electronics, making adjustments depending on external circumstances.

The developers assure that this engine is very economical. However, for the serial production of research was not enough.

Variable compression ratio

The indicator is very important. After all, power, efficiency and economy are directly dependent on a high degree of compression. Naturally, you can not raise it infinitely. Therefore, for some time development has stopped. Otherwise, there was a risk of detonation, which could lead to damage to the engine.

This indicator is especially strong on the engines with supercharging. After all, they heat up more, and therefore the percentage of probability of detonation triggering is much higher. Therefore, the compression ratio sometimes has to be reduced, because of what, naturally, the efficiency of the motor falls.

Ideally, the compression ratio should change smoothly depending on the operating mode and load. There were a lot of developments, but they are all too complicated and expensive.

Legendary Saab

The best results were achieved by Saab when it released a five-cylinder engine in 2000, which produced about two hundred and twenty-five horses at 1.6 liters of volume. This achievement seems incredible today.

The engine is divided in two, where the parts are connected to each other in a hinged manner. From below is located the crankshaft, connecting rods and pistons, and at the top - cylinders with heads. The hydraulic actuator is capable of tilting the monoblock with cylinders and heads, changing the compression ratio when the drive compressor is turned on. Despite all the efficiency, the development also had to be postponed because of the high cost of construction.

Easier and more affordable

Thus, it can be concluded that the engine running on the Atkinson cycle played a significant role in improving the mechanism of the motor in the future. It seems that improvements, based on one another, will lead ICE, finally, to the optimal mode of operation.

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