Mecanica Automotriz

THE MOTOR
An internal combustion engine of any type of machine is that mechanical energy obtained directly from the chemical energy produced by a fuel burning inside a combustion chamber, the main part of an engine. Using internal combustion engines of four types: the cyclic Otto engine, the diesel engine, the rotary motor and the gas turbine.

OTTO ENGINE 4 STROKE PETROL

The cyclic Ottoengine, named after the German coach who invented it, Nikolaus August Otto, is the conventional gasoline engine that is used in automotive and aerospace.

The combustion chamber is a cylinder, usually fixed, closed at one end and inside which slides a piston within very tight. The position into and out of the piston modify the volume between the inner face of the piston and the chamber walls. Theouter face of the piston is connected by a shaft to the crankshaft, which converts rotary motion into linear motion of the piston. In multi-cylinder engines the crankshaft has a starting position, called crank pin and connected to each axis, whereby the energy produced by each cylinder is applied to the crankshaft at a point of rotation. The crankshafts have heavy flywheels and counterweightswhich reduces inertia axis motion irregularity. A motor may have from 1 to 28 cylinders.

The fuel pumping system of an internal combustion engine consists of a tank, a fuel pump and a device vaporized or atomized liquid fuel. It's called the device carburetor used for this purpose in Otto engines. In multi-cylinder engines driving the vaporized fuel to the cylinders through a branch tube calledintake manifold. Many engines have an exhaust manifold or exhaust, which carries the gases produced during combustion. Each cylinder outlet and the fuel gas ejected through the head valves or sliding valves. A spring keeps the valve closed until opened at the right time, to actuate the cams of a camshaft driven by the crankshaft rotation. In the 1980's, this feeding system of a mixture of fuel andair has been displaced by other more elaborate systems as used in diesel engines. These systems, computer controlled, increase fuel economy and reduce the emission of toxic gases.

All engines must have a way to start the ignition of fuel in the cylinder. For example, the ignition system of Otto engines, called ignition coil, a source of continuous electric current of low voltage connected to theprimary of a transformer. The current is cut many times per second with a timer. Fluctuations in the primary current induces a current in the secondary high voltage, which leads to each cylinder through a rotary switch called distributor. The device is produced by the ignition plug, a conductor fixed to the upper wall of each cylinder. The plug contains two separate wires between the high voltageproduces an electric arc generated by the spark which ignites the fuel within the cylinder.

Since the combustion produces heat, all the engines must have some type of cooling system. Some stationary engines of automobiles and airplanes and outboard engines are cooled with air. The cylinder engines that use this system have on the outside with a set of metal sheets that emit heat produced insidethe cylinder. In other engine cooling water is used, which means that cylinders are located within a housing filled with water which in automobiles is circulated by a pump. The water is cooled by passing through the blades of a radiator. In marine engines seawater is used for cooling.

Unlike engines and steam turbines, internal combustion engines produce no torque when starting, which impliesthat the movement should be raised crankshaft so that it can start the cycle. Automotive engines use an electric motor (starter motor) connected to the crankshaft by an automatic clutch is disengaged as soon as the engine starts. On the other hand, some small engines are started by hand turning the crank with a chain or pulling a rope wrapped around the flywheel. Other ignition engine are the...