Bearings in internal combustion engines
Internal combustion engine
Internal combustion engine is a device converting the energy of a fuel-air mixture burning within a combustion chamber into mechanical energy.
Reciprocating internal combustion engine is an engine, in which burning process occurs within a cylinder equipped with a piston driven by the pressure of the combustion gases. The gas pressure force is transmitted to the crankshaft linked to the piston by means of a connecting rod. Such mechanical device called crank mechanism transforms the alternating linear motion of the piston into the rotation of the shaft.
Reciprocating engines are the most common type of internal combustion engines.
The figure below presents a scheme of a typical four-stroke reciprocating combustion engine.
The engine consists of four cylinders in different phases of the engine cycle (intake, compression, expansion and exhaust). Each cylinder has an inlet and exhaust valves, opening and closing of which is controlled by the cam mechanism.
Each piston is joined to the crank pin of the crankshaft though the connecting rod.
The four-stroke cycle:
http://en.wikipedia.org/wiki/EngineReciprocating internal combustion engine is an engine, in which burning process occurs within a cylinder equipped with a piston driven by the pressure of the combustion gases. The gas pressure force is transmitted to the crankshaft linked to the piston by means of a connecting rod. Such mechanical device called crank mechanism transforms the alternating linear motion of the piston into the rotation of the shaft.
Reciprocating engines are the most common type of internal combustion engines.
The figure below presents a scheme of a typical four-stroke reciprocating combustion engine.
The engine consists of four cylinders in different phases of the engine cycle (intake, compression, expansion and exhaust). Each cylinder has an inlet and exhaust valves, opening and closing of which is controlled by the cam mechanism.
Each piston is joined to the crank pin of the crankshaft though the connecting rod.
The four-stroke cycle:
- Intake: The intake valve is open. The piston moves downwards from the Top Dead Center (TDC) to the Bottom Dead Center (BDC) sucking the fuel-air mixture into the cylinder.
- Compression: Both valves are closed. The piston moves from BDC towards TDC compressing the gaseous fuel-air mixture. The compression causes pressure and temperature increase of the gas in the cylinder. When the crankshaft reaches some angle before TDC the fuel-air mixture is ignited and fuel combustion starts. Combustion further increases the gas pressure and temperature. In the gasoline (petrol) engines ignition is as a result of a spark produced by the spark plug. The engines of such type are called Spark Ignition (SI) engines. In the diesel engines the fuel-air mixture is ignited by the heat of the compressed gages. The engines of such type are called Compression Ignition (CI) engines.
- Power (expansion): Both valves are closed. The piston travels from TDC to BDC under the high pressure of hot burning gases. The power of the the gases is transmitted to the crankshaft through the connecting rod. Just before the piston reaches the Bottom Dead Center the exhaust valve opens.
- Exhaust: The exhaust valve is open. The piston moves towards TDC forcing the combustion gases out of the cylinder. When it reaches TDC the exhaust valve closes and the intake valve opens - the cycle returns to the initial state.
