Two-Stroke Cycle Engine

As the piston begins its leftward stroke from bottom dead center (BDC), both inlet and exhaust ports are uncovered and air from some external source is flowing through the cylinder. Directional control is provided through port and/or piston design to ensure the most complete cylinder scavenging possible. 

At Point 2, the air intake is closed, but compression does not begin until the exhaust port is covered also. Shortly after the exhaust port is closed and compression of the trapped air begins, fuel is injected at Point 3 into the cylinder through a high pressure fuel valve. At Point 4, just prior to completion of the compression stroke, a spark ignites the fucl/ iir mixture and the pressure rises rapidly through the remainder of the compression stroke and the beginning of the power stroke. 

The area contained within the P-V diagram represents the total mechanical work performed by the piston. Some of this work is required to sustain the cycle and must be subtracted from the work calculated tiom the P-V diagram to determine the total external work available from ilie piston. 

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Two-stroke cycle machines must be equipped with a scavenge air system that may include a separate scavenge air cylinder, gear-driven blower, or turbochargers. It should be noted, however, that a method must be provided to supply a turbocharged two-stroke cycle engine with air to start. 

Two-Stroke Cycle Engine An engine which produces one power stroke for each crankshaft revolution. Fuel combustion proceeds as follows ... 

CD introduced 1955 for certain naturally aspirated and turbocharged engines, CD-II introduced 1985 for two-stroke cycle engines and CE introduced 1985 for high-speed, naturally aspirated and turbocharged engines. Can replace CC and CD lubricants. 

Uses Lubricant for two-stroke cycle engines, rubber, greases, textiles reactive intennediate for resins, plasticizers, modifiers, and surfactant mfg. antifoam in boiler water, latex processing, washing soi ns.. paints, adhesives, salt water evaporators solvent for inks and dyes solvent, softener, and plasticizer for textile and paper coalings, NC coatings mold release agents and dye solvents for vinyl resins demulsifier cosmetic emollient... 

Uses Lubricant for two-stroke cycle engines, rubber, greases, textiles reactive intermediate for resins, plasticizers, surfactants antifoam in boiler water, latex processing solvent for inks and dyes antistat in cosmetics... 

Two-stroke cycle engine An engine completing one cycle in two strokes of the piston or one shaft revolution. The cyclic events are designated by the following strokes (1) induction and compression stroke, (2) expansion and 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. 

Figure 11.7 shows theP-Fo diagram for a two-stroke cycle engine. In this case, the exhaust valve opens before the piston reaches its bottom position and the remainder of the downward power stroke is used to expel the combustion products. Introduction of the new charge starts just before the piston reaches bottom and continues for a short time after the piston starts up. This is made possible by use of a blower to increase the fuel intake pressure. 

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