ABOUT OF ENGINE AND COMPONENTS OF IC ENGINE

   

ENGINE & WORKING PRINCIPLES

                A heat engine is a machine, which converts heat energy into mechanical energy. The      combustion of fuel such as coal, petrol, diesel generates heat. This heat is supplied to a      working substance at high temperature. By the expansion of this substance in suitable      machines, heat energy is converted into useful work.

CLASSIFICATION OF ENGINE

COMPONENTS OF IC ENGINE

 Cylinder:

        The cylinder of an IC engine constitutes the basic and supporting portion of the engine power

   unit. Its major function is to provide space in which the piston can operate to draw in the fuel

   mixture or air (depending upon spark ignition or compression ignition), compress it, allow it

   to expand and thus generate power. The cylinder is usually made of high-grade cast iron. In

   some cases, to give greater strength and wear resistance with less weight, chromium, nickel

   and molybdenum are added to the cast iron.

Piston:

        The piston of an engine is the first part to begin movement and to transmit power to the

  crankshaft as a result of the pressure and energy generated by the combustion of the fuel. The

  piston is closed at one end and open on the other end to permit direct attachment of the

  connecting rod and its free action.

Piston Rings:

       These are made of cast iron on account of their ability to retain bearing qualities and elasticity

  indefinitely. The primary function of the piston rings is to retain compression and at the same

  time reduce the cylinder wall and piston wall contact area to a minimum, thus reducing

  friction losses and excessive wear. The other important functions of piston rings are the

  control of the lubricating oil, cylinder lubrication, and transmission of heat away from the

  piston and from the cylinder walls. Piston rings are classed as compression rings and oil rings

  depending on their function and location on the piston.

  Compression rings are usually plain one-piece rings and are always placed in the grooves

  nearest the piston head. Oil rings are grooved or slotted and are located either in the lowest

  groove above the piston pin or in a groove near the piston skirt. Their function is to control

  the distribution of the lubricating oil to the cylinder and piston surface in order to prevent

  unnecessary or excessive oil consumption.

Piston Pin:

        The connecting rod is connected to the piston through the piston pin. It is made of case

  hardened alloy steel with precision finish. There are three different methods to connect the

  piston to the connecting rod. 

Connecting Rod:

       This is the connection between the piston and crankshaft. The end connecting the piston is

 known as small end and the other end is known as big end. The big end has two halves of a

 bearing bolted together. The connecting rod is made of drop forged steel and the section is of

 the I-beam type.

Crankshaft:

         This is connected to the piston through the connecting rod and converts the linear motion of

  the piston into the rotational motion of the flywheel. The journals of the crankshaft are

  supported on main bearings, housed in the crankcase. Counter-weights and the flywheel

  bolted to the crankshaft help in the smooth running of the engine. 

  Engine Bearings:

       The crankshaft and camshaft are supported on anti-friction bearings. These bearings must be

  capable of with standing high speed, heavy load and high temperatures. Normally, cadmium,

  silver or copper lead is coated on a steel back to give the above characteristics. For single

  cylinder vertical/horizontal engines, the present trend is to use ball bearings in place of main

  bearings of the thin shell type.

Valves:

        To allow the air to enter into the cylinder or the exhaust, gases to escape from the cylinder,

  valves are provided, known as inlet and exhaust valves respectively. The valves are mounted

  either on the cylinder head or on the cylinder block.

Camshaft:

        The valves are operated by the action of the camshaft, which has separate cams for the inlet,

  and exhaust valves. The cam lifts the valve against the pressure of the spring and as soon as it

  changes position the spring closes the valve. The cam gets drive through either the gear or

  sprocket and chain system from the crankshaft. It rotates at half the speed of the camshaft.

Flywheel:

       This is usually made of cast iron and its primary function is to maintain uniform engine speed

  by carrying the crankshaft through the intervals when it is not receiving power from a piston.   The      size of the flywheel varies with the number of cylinders and the type and size of the

  engine. It also helps in balancing rotating masses.