The Otto Cycle
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| An internal-combustion engine uses either a four-stroke cycle or a two-stroke cycle. In the four-stroke or Otto cycle, the downward movement of the piston within a cylinder creates a partial vacuum. For the intake stroke, a fuel-air mixture fills the vacuum in the cylinder as the piston moves down. During the compression stroke, the piston moves up and compresses the mixture. The spark plug fires, the mixture ignites and forces the piston down in the power stroke. The combustion products are pushed out the exhaust valve during the exhaust stroke. Then the cycle repeats. |
Figure 5 |
