The primary purpose of piston rings is to do what?

The primary purpose of piston rings is to seal the combustion chamber and control oil consumption. This sealing action is crucial because it prevents the escape of combustion gases during the engine's power stroke, which optimizes engine efficiency and power output. Additionally, piston rings help to control the flow of oil into the combustion chamber, minimizing oil consumption and preventing excessive smoke from the exhaust.

In contrast, supporting the crankshaft is a function handled by bearings, not piston rings. Regulating the fuel mixture is achieved through the fuel injection system or carburetor, while controlling crankcase pressure relates to the overall engine ventilation system. These functions are separate from the role of piston rings, which focus specifically on sealing and lubrication within the cylinders.