Four-stroke engine
The four-stroke engine is an internal combustion engine. The four strokes are:
| Stroke | Alias | Piston | Intake valve | Exhaust valve |
|---|---|---|---|---|
| intake | suck | opens, sucks in air + fuel | open | closed |
| compression | squeeze | closes, compressing the air + fuel | closed | closed |
| combustion | bang | opens, because air + fuel combust, expanding gas in cylinder | closed | closed |
| exhaust | blow | closes, blowing out the used gasses | closed | open |
Four-stroke Engine Media
Four-stroke cycle used in gasoline/petrol engines: intake (1), compression (2), power (3), and exhaust (4). The right blue side is the intake port and the left brown side is the exhaust port. The cylinder wall is a thin sleeve surrounding the piston head which creates a space for the combustion of fuel and the genesis of mechanical energy.
An Otto Engine from 1880s US Manufacture
This 2004 Toyota Prius hybrid has an Atkinson-cycle engine as the petrol-electric hybrid engine
Atkinson or Miler cycle in p-V diagram.
Audi Diesel R15 at Le Mans
The idealized four-stroke Otto cycle p-V diagram: the* intake (A) *stroke is performed by an isobaric expansion, followed by the* compression (B) *stroke, performed as an adiabatic compression. Through the combustion of fuel an isochoric process is produced, followed by an adiabatic expansion, characterizing the* power (C) *stroke.
The four-stroke cycle*1=TDC*2=BDC* A: Intake * B: Compression * C: Power * D: Exhaust
Top dead center, before cycle begins
Illustration of the Four-stroke cycle
