Four-stroke cycle

Both two- and four-stroke cycle engines are used in commercial applications. For the purpose of this discussion, however, comments will be limited to applications normally encountered in the oil and gas industry. Some of the advantages and disadvantages associated with each engine type are as follows ... 

Vierstundenlack, m. four-hour varnish. Viertakt, m. Mach.) four-stroke cycle, vierte, a. fourth, vierteilen, v.t. quarter. 

Both gasoline and diesel engines are available in either a two-stroke- or a four-stroke-cycle design. The fundamental difference between the Otto engine cycle (named after Nikolaus Otto, who developed it in 1876) and the diesel engine cycle involves the conditions of the combustion. In the Otto cycle. 

Four-stroke cycle. TDC and BDC = top dead center and bottom dead center positions of the piston, respectively. Vj = displacement. V, = clearance volume. Compression ratio = (Vj -I-... 

The horizontal line at the bottom of the pressure-volume diagram of Figure 4 traces the other tv o strokes of the four-stroke cycle. On the exhaust stroke, from 5 to 6, the rising piston expels most of the remaining combustion products from the cylinder. On the intake stroke, from 6 to 7 (= 1), the descending piston inducts a fresh charge for repetition of the cycle. The net thermodynamic work developed in this cycle is proportional to the area enclosed by the pressure-volume diagram. In the ideal case, both the exhaust and intake strokes occur at atmospheric pressure, so they have no effect on the net output work. That justifies their exclusion from the thermodynamic representation of the ideal Otto... 

Pressure-volume diagram for ideal Otto cycle (1-2-3-4-5), with exhaust and intake of four-stroke cycle (5-6-7) added. ... 

Figure 15.1 Four-stroke cycle for an internal combustion engine...

Jones, B., etal., A Comparative Analysis of Ethanol Versus Gasoline as a Fuel in Production Four-Stroke Cycle Automotive Engines, SAE Paper No. 952749, Society of Automotive Engineers, Warrendale, Pa., 1995. 

Service category CG-4 designated to meet 1995 exhaust emission standards for use in high speed four-stroke-cycle diesel engines New classification for the generation of heavy-duty engine oils. The process of adsorption characterized by a chemical reaction between the adsorbate and adsorbent, where exchange of orbital electrons occurs. 

The diesel engine works following a four-stroke cycle analogous to that of a petrol engine. There are however, very important differences, which can be explained using... 

Most internal-combustion engines operate on a four-stroke cycle (see Figure 12-13). 

Study this text on the four-stroke cycle. Then label each stroke correctly in Fig. 2 opposite. 

The car engine still in use in the majority of motor transport is based on the four-stroke cycle developed by Nikolaus Otto in the 19th century. This cycle places key requirements on the fuel at the various stages (Figure 10.63). 

Figure 10.63 The stages of the four-stroke cycle of a gasoline engine...

Four-stroke cycle engine An engine completing one cycle in four strokes of the piston or two shaft revolutions. The cyclic events are designated by the following strokes (1) induction or suction stroke, (2) compression stroke, (3) power or expansion stroke, (4) exhaust stroke. ... 

Engine types fall into two categories two-stroke cycle and four-stroke cycle. Typical two-stroke-cycle engine arrangements are shown in Figs. 6.87 and 6.88. A typical four-stroke-cycle engine arrangement is shown in Fig. 6.89. 

The Otto cycle is essentially the cycle describing the internal-combustion automobile engine. This is a four-stroke cycle, in contrast to the simpler two-stroke Carnot cycle and the various others, such as the Stirling and Brayton cycles, that operate on a single oscillation of the piston. The Otto cycle consists of an intake expansion, a compression, an expansion resulting from ignition... 

The four-stroke cycle spark ignition (SI) internal combustion engine (ICE) was initially proposed by Beau de Rockas in 1862 and first built by N. A. Otto in 1876. This engine has become the major piston engine in use today. The PV cycle of the engine is shown in Fig. 4.3 where the four strokes are indicated. 

Figure 11.6. P-Vq diagram for four-stroke cycle IC engine (Otto cycle).

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