Thermodynamic cycle for spark ignition piston engines
See also: Otto engine and Four-stroke engine
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Otto cycle pressure–volume diagramThe idealized diagrams of a four-stroke Otto cycle Both diagrams: the intake (0-1 and colored green) stroke is performed by an isobaric expansion, followed by an adiabatic compression (1-2 and colored orange) stroke. Through the combustion of fuel, heat is added in a constant volume (isochoric process) process (2-3), followed by an adiabatic expansion process power (3-4 and colored red) stroke. The cycle is closed by the exhaust (4-0 and colored blue) stroke, characterized by isochoric cooling and isobaric compression processes.Temperature-Entropy diagram
An Otto cycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine. It is the thermodynamic cycle most commonly found in automobile engines.[1]
The Otto cycle is a description of what happens to a gas as it is subjected to changes of pressure, temperature, volume, addition of heat, and removal of heat. The gas that is subjected to those changes is called the system. The system, in this case, is defined to be the fluid (gas) within the cylinder. By describing the changes that take place within the system, it will also describe in inverse, the system's effect on the environment. In the case of the Otto cycle, the effect will be to produce enough net work from the system so as to propel an automobile and its occupants in the environment.
The Otto cycle is constructed from:
Top and bottom of the loop: a pair of quasi-parallel and isentropic processes (frictionless, adiabatic reversible).
Left and right sides of the loop: a pair of parallel isochoric processes (constant volume).
The isentropic process of compression or expansion implies that there will be no inefficiency (loss of mechanical energy), and there be no transfer of heat into or out of the system during that process. The cylinder and piston are assumed to be impermeable to heat during that time. Work is performed on the system during the lower isentropic compression process. Heat flows into the Otto cycle through the left pressurizing process and some of it flows back out through the right depressurizing process. The summation of the work added to the system plus the heat added minus the heat removed yields the net mechanical work generated by the system.
^Wu, Chih. Thermodynamic Cycles: Computer-aided Design and Optimization. New York: M. Dekker, 2004. page 99
An Ottocycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine. It is the thermodynamic cycle...
of the four-stroke cycle in a single turn of the crankshaft, and was designed to avoid infringing certain patents covering Otto-cycle engines. Atkinson's...
due to the Ottocycle, also designed by Otto. Three types of internal combustion engines were designed by German inventors Nicolaus Otto and his partner...
is acknowledged as the "Otto" cycle engine. The term "Ottocycle" is applied to all compressed charge, four cycle engines. Otto married Anna Gossi and...
0 {\displaystyle dS-{\frac {dQ}{T}}=0} . The OttoCycle is an example of a reversible thermodynamic cycle. 1→2: Isentropic / adiabatic expansion: Constant...
this period, but it is less pronounced than in the Ottocycle. In contrast, the idealized Ottocycle of a gasoline engine approximates a constant volume...
engine. In 1876, Nicolaus Otto began working with Gottlieb Daimler and Wilhelm Maybach, patented the compressed charge, four-cycle engine. In 1879, Karl Benz...
the four-stroke Ottocycle or the two-stroke cycle. Petrol engines have also been produced using the Miller cycle and Atkinson cycle. Most petrol-powered...
the gas will increase, but the volume will remain the same. The ideal Ottocycle is an example of an isochoric process when it is assumed that the burning...
Otto fuel II, sometimes known simply as Otto fuel, is not related to the Ottocycle; it is named after Reitlinger and for being the second iteration of the...
his cars used the four-stroke Alphonse Beau de Rochas cycle or Ottocycle and not the Brayton-cycle engine used in the Selden auto. Ford won the appeal...
Miller cycle, the intake valve is left open longer than it would be in an Otto-cycle engine. In effect, the compression stroke is two discrete cycles: the...
expansion than compression—making it a simulated Atkinson cycle, rather than a conventional Ottocycle. The reduction in cylinder charge means reduced torque...
the common thermodynamic cycles have been studied, for example the Carnot cycle, Stirling cycle and Ottocycle. The Ottocycle can serve as a template...
to lower thermal efficiency than the more well known Ottocycle and Diesel cycle. In the cycle, an ideal gas undergoes 1–2: Constant volume (isochoric)...
cycle in a diesel engine or specific types of Ottocycle in petrol engines, namely petrol direct injection) or an air/fuel mixture (traditional Otto cycle...
engine cycle equations below, and when this approximation is made the cycle is called an air-standard cycle. Ottocycle: automobiles The Ottocycle is the...
under low loads for additional fuel economy with the ability to shift to Ottocycle on demand under high loads or for extra acceleration.[citation needed]...
commercially successful was made during 1860 by Etienne Lenoir. In 1877, the Ottocycle was capable of giving a far higher power-to-weight ratio than steam engines...
capable of 300 hp (220 kW). The engine can operate on the Ottocycle, Miller cycle or the Atkinson cycle. Further advantages of the camless engine is that a...
to prevent pre-ignition and backfire. In a rotary engine, each cycle of the Ottocycle occurs in different chambers. Importantly, the intake chamber is...
in Austria Mercedes-Benz Zetros In this article, the terms Ottocycle engine and Diesel cycle engine are used to differentiate between a traditional petrol...
(207 cubic inches) V6 turbocharged direct injection four-stroke piston Ottocycle 620 hp fuel-efficient engine developed and built by Mecachrome, and maintained...
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