4.5 CARS 94 The cylinder is generally made of cast iron or aluminium. In some engines, the cylinders are lined with sleeves (metal tubes that form the inner surface of the cylinder) that can be replaced when they become worn. THE ICE ENGINE What is an engine? An engine is a device that transforms some type of energy into mechanical motion. Heat engines (also called combustion engines) use fuel that is burnt to produce heat, which is then converted into work. There are two main kinds of combustion engines: Internal Combustion Engine Sparkplug Intake Intake valve Cylinder block Gudgeon pin Crankcase the external combustion engine, where the fuel burns outside the system to heat water and produce steam, which then drives motion inside the engine like in old steam locomotives and steamboats; the internal combustion engine, which burns fossil fuels directly inside the engine. This type of engine is more efficient (needing less fuel per distance) and also more compact. ONLINE RESOURCES The Otto cycle engine crankshaft: albero (meccanico) gudgeon pin: spinotto intake: aspirazione manifold: collettore rod: asta sleeve: manica sparkplug: candela (di accensione) worn: usurato 224 MECHANICS The internal combustion engine An internal combustion engine (ICE) is a machine where fuel is burnt inside the engine itself to release energy, which then moves parts like pistons to produce mechanical power. In this type of engine, fuel burns with some air inside a space called the combustion chamber placed at the top of the cylinder , the part where the piston moves up and down. The cylinder block is the main structure of the engine that houses the cylinders, whereas the main components of the cylinder are: the sparkplug, used to deliver electric current from the ignition system to the combustion chamber; the valves (intake and exhaust) which control the flow of gases into and out of the cylinder; Exhaust Exhaust valve Cylinder Cooling water Piston Connecting rod the inlet manifold, which brings the air-fuel mixture into the cylinder for combustion; the exhaust manifold that carries the burnt gases out of the cylinder after combustion; the piston, whose purpose is to transfer force from the expanding gas in the cylinder to the crankshaft; the connecting rod, which connects the piston to the crankshaft and transmits the compressive and tensile forces from the piston; the gudgeon pin, which connects the piston to the connecting rod, allowing the piston to rotate as it moves up and down; the crankshaft, which is a rotating shaft that converts the motion of the pistons into rotational motion; the cooling water jacket, which is a series of hollow passages or channels that allow coolant to circulate around the engine to maintain temperature.