Diesel Engine

       A diesel engine is an internal combustion engine.  Diesel engine ignition system, such as the diesel engine and Homogeneous charge compression ignition engines, rely solely on heat and pressure created by the engine in its compression process for the engine. The engine works on the principle of diesel cycle. It uses the heat of compression to initiate ignition to burn the fuel that has been injected into the combustion chamber. The compression that occurs is usually more than three times higher than petrol engine. Diesel engines will take air only, and shorty before peak compression, a small quantity of diesel fuel is sprayed into the cylinder via a fuel injector that allows the fuel to instantly ignite. The compression air produced force the piston down, generating power. The engine operating cycle is repeated every four strokes (upward or downward movement) of the piston, this being known as four stroke cycle as shown in figure1.7 (a).

Figure 1.7(a) Four Stroke CI Engine(Diesel Engine)

Four stroke CI engine:-             

               Conventional CI engine operates using four “strokes”, with either an up or down movement of each piston. These strokes are named:  Intake, Compression, Combustion and exhaust. This cycle is same as that of the four stroke petrol engine
              It consist of 4 strokes, one cycle operation is completed in 4 stroke of the piston that is one cycle is completed in every 2 revolutions of the crankshaft. Each stroke consists of 180°, of crankshaft rotation and hence a cycle consists of 720°, of crankshaft rotation.
Essential part of four stroke diesel engine as shown in figure1.7(b).

Figure1.7(b) Essential part of 4 stroke Diesel engine

Intake Stroke:-

         Diesel engines typically use direct injection which injects fuel directly into the combustion chamber during the compression stroke. The stroke on a diesel engine only draws air into the cylinder.In suction stroke piston starts at Top Dead Center (TDC) of the cylinder and moves to the Bottom Dead Center (BDC). Outlet valve will be closed and inlet valve will be open to allowing the mixer of fuel & air into the cylinder. Figure1.7(c) shows the intake stroke of the diesel engine                                              

          Figure1.7(c) Intake stroke

Compression stroke:-

                             In diesel engine fuel is injected under high pressure towards the top of the compression stroke. In compression stroke, once piston reaches BDC & moves back TDC, inlet valve will be closed. As the piston moves towards TDC.It compresses air inside the cylinder & compression takes place. Hence it is called compression stroke. Figure1.7 (d) shows the compression stroke of the diesel engine.

 Figure1.7(d) Compression stroke

Combustion stroke:-

          Compression ignition engines such as the diesel engine do not use the spark plugs to ignite the fuel-air mixture.When the piston reaches the top of the compression stroke the temperature and pressure in the combustion chamber is sufficient to ignite the mixture.In expansion stroke, both the valves are closed. When piston reaches top of its stroke, the fuel is sprinkled by the Fuel Injector andthe fuel mixture is ignited due to high temperature & pressure generated inside the cylinder & push down the piston to BDC.Hence it is known as combustion or expansion stroke. . Figure1.7 (e) shows the combustion stroke of the diesel engine
 

Figure1.7(e) Combustion stroke

 Exhaust stroke:-

              Exhaust gases are pushed out of the cylinder by the upward motion of the piston following the ignition stroke. During this stroke, the outlet valve is open and inlet valve is closed.The piston moves from bottom to top and during this motion piston pushes the exhaust gases out of the cylinder at constant pressure.Typically exhaust gases contain oxygen, nitrogen, water vapor, carbon dioxide, carbon monoxide, hydrogen, nitrous oxides, particulates and unburned hydrocarbons.

Figure1.7 (f) shows the Exhaust stroke. At the one movement the inlet valve open and the new cycle starts.

Figure1.7(f) Exhaust stroke

Two stroke CI Engine:-

Two stroke engine is widely used where small power required for motor cycle like auto rickshaw, scooter. This type of engine is compact in size, easy for manufacturing and simple in operation. In two strokes engine there is no inlet or exhaust valve as in four 

stroke engines.Internal combustion engine which completes a power cycle in only one crankshaft revolution and with two strokes, or up and down movements, of the piston in comparison to a "four-stroke engine",which uses four stroke. Two stroke CI engine as shown in figure1.7 (g).

Figure 1.7(g) Two Stroke CI Engine(Diesel Engine)

Intake/Compression:- 

              When piston moves from BDC to TDC, it first closes the transfer port and then exhausts port.The charge of air-fuel mixture in the chamber is pressurized and creates high temperature.At the same time a vacuum is developing in the crankcase, so the fresh charge is being drawn into the intake port.. As the piston moves towards TDC, the diesel is added to the pressurized and high temperature gas which in turn ignites the whole mixture inside the cylinder and forces the piston to move downwards. Figure1.7 (h) shows the Intake/Compression stroke in two stroke diesel engine.

Figure 1.7(h) Compression Stroke

Combustion/Exhaust:-                                                                                                                     In this stroke both the ports still closed condition , the pressure of the expanding gases forces the piston towards BDC.The pressure in the crankcase is already rising. Later in down stroke exhaust port will be open & force out the burnt gases.Very shortly after that the Inlet / Transfer port will also open to intake the fresh charge of fuel mixture and engine is ready to start of the cycle.Figure1.7 (i) shows the Combustion/Exhaust stroke in two stroke diesel engine.

Figure 1.7(h) Combustion Stroke

Comparison of petrol and diesel engines:-

Comparison of two stroke and four stroke engine:-

Petrol Engine

           Petrol engine is an internal combustion engine with the spark ignition so it is also known spark ignition that means S I Engine. Fuel used in petrol engine is petrol and similar volatile fuel. The petrol engine works on principle of constant volume cycle. In most petrol engine the fuel and air are usually premixed before compression. It is a reciprocating piston engine, in which a number of piston move down and up in cylinder.                                                                                          

 A mixture of petrol and air is introduced into the space above the piston and ignited. The gases produced force the piston down, generating power.The engine operating cycle is repeated every four strokes (upward or downward movement) of the piston, this being known as four stroke cycle as shown in figure1.4. 

                                            

                         Figure1.4 4-Stroke S I engine (petrol engine)

Four stroke SI engine:-                                                                                                                    Conventional SI engine operates using four “strokes”, with either an up or down movement of each piston.

These strokes are named:    Intake, Compression, power and exhaust.
                      One complete cycle in the 4-strokr/cycle SI engine requires two complete rotation of the crankshaft. As the crankshaft rotates, the piston moves up and down in the cylinder.In the two complete revolution of the crankshaft that make up one cycle. 

Intake Strokes:-

                 Intake stroke of the combustion cycle is when the piston travels down the cylinder with the intake port open. During this stroke, inlet valve open and exhaust valve closed, the pressure in the cylinder will be atmosphere.As the piston moves from top to bottom, the volume in the cylinder increases, while simultaneously pressure decreases.
               This creates a pressure difference between the atmosphere and inside of cylinder. Due to this pressure difference the petrol and air mixture will enter into the cylinder through fuel injection system or carburetor.In a carbureted engine, during the intake stroke of the piston a vacuum is created in the inlet manifold. With a multi cylinder engine the vacuum is almost constant. Electronic fuel injection system spray fuel at high pressure either directly into the combustion chamber or into the intake port of the cylinder during the intake stroke. Using fuel injection enables improved control over the air-fuel mixture and reduces the power required to draw fuel from the jets. The diagram below shows a typical electronic fuel injection system.

      Figure 1.5(a) Intake stroke

Compression stroke:-

                              The compression stroke is the upward movement of the piston in the cylinder with the valves closed following the intake stroke. During this stroke both the inlet valve and exhaust valve are closed, the piston moves from bottom to top as shown in figure 1.5(b).This upward motion compress the fuel/ petrol air mixture inside the combustion chamber raising the pressure.   

Near the end of this stroke, the petrol and air mixture is ignited by the electric spark given out by the spark plug. The difference between the initial volume of the cylinder and the final volume at the top of the compression stroke is known as the compression ratio. The fuel/petrol –air mixture and compression ratio is critical to avoid pre-ignition which is the abnormal ignition of fuel in the combustion chamber before the combustion stroke

                                             Figure1.5 (b) Compression stroke

Power stroke:-

                    The power stroke is the downward movement of the piston in the cylinder with the valves closed. During this stroke both the inlet valve and outlet valve are closed, the piston moves from top to bottom.                                                        

The high pressure and high temperature burnt gases force the piston to perform this stroke, called power stroke. This stroke is also known as combustion stroke or working stroke. The engine produces power during this stroke.

As the piston moves from top to bottom, the pressure of hot gases decreases and volume increases.

Near the end of this stroke, the exhaust valves open which will release the burnt gases to the atmosphere. Figure1.5(c) shows the power stroke.

                                               Figure1.5(c) Power stroke

Exhaust stroke:-

               Exhaust gases are pushed out of the cylinder by the upward motion of the piston following the ignition stroke. During this stroke, the outlet valve is open and inlet valve is closed. The piston moves from bottom to top and during this motion piston pushes the exhaust gases out of the cylinder at constant pressure.

Typically exhaust gases contain oxygen, nitrogen, water vapor, carbon dioxide, carbon monoxide, hydrogen, nitrous oxides, particulates and unburned hydrocarbons.  

Figure1.5 (d) shows the Exhaust stroke. At the one movement the inlet valve open and the new cycle starts

                                           Figure 1.5(d) Exhaust stroke

Two stroke SI Engine:-

                       The engine cycle is completed after just two strokes (up or down) of the piston, which is differentiates it from the more common four-stroke cycle.

Some power mowers and lightweight motorcycle use two-stroke petrol engines, which are cheaper and simpler than four-strokes. In a typical two-stroke motorcycle engine, fuel mixture is drawn into the crankcase as the piston moves up on its first stroke to compress the mixture above it. Then the compressed mixture is ignited, and hot gases are produced, which drive the piston down on its second stroke.

 As it moves down, it uncovers an opening (port) that allows the fresh fuel mixture in the crankcase to flow into the combustion space above the piston.

At the same time, the exhaust gases leave through another port. In two stroke SI engine only two strokes is used by combing the two strokes in half cycle.

These strokes are named: intake/compression, power/exhaust.
Figure 1.6(a) show the Two Stroke S.I Engine

                             Figure 1.6(a) Two Stroke S.I Engine

Intake/compression stroke:-

           The fuel-air mixture has entered the cylinder, and the piston begins to move up i.e. Bottom to Top. This compresses the charge in the cylinder and draws a vacuum in the crankcase, pulling in more air, fuel, and oil from the carburetor.    The compressed charge is ignited by the spark plug, and the cycle begins.The figure 1.6(b) shows the Intake or Compression stroke .
                                             

  Figure 1.6(b)  Copression Stroke

Power/exhaust stroke:-

                                This stroke occurs immediately after the ignition of the charge. The piston is forced down i.e. movement from Top Dead Centre to Bottom Dead Centre.                                                                                                                                        After a certain point, the top of the piston passes the exhaust port, and most of the pressurized exhaust gases escape. As the piston continuous down, it compress the air/fuel/oil mixture in the crankcase. Once the top of the piston passes the transfer port, the compressed charge enters the cylinder from the crankcase and any remaining exhaust is forced out. The figure 1.6(c) shows the Power or exhust stroke .
                                     

                                   Figure 1.6(c)  Power or exhust stroke .

Diesel Engine

Types Of Engine

           Engine is the major part of an automotive system, Engine are of various types. Major types of engine are External combustion Engines and Internal combustion engine.  Mainly used type of engine in vehicle is internal combustion engine. The internal combustion engine is an engine in which the combustion of fuel and a right mixture of air occur in a limited space called a combustion chamber.

Which type of fuel used in engine there are various type of internal combustion engine as shown in figure 1.3                            

                                         Figure 1.3 Types of Engine

Petrol Engine

Introduction of Engine

                 Engine is the most important part of the vehicle. I will give brief information about engine I hope this will clear the basic idea of engine.

                       There are various types of engine available but widely used engine is the internal combustion Engine, piston-type, 4-stroke /cycle, 2-stroke/cycle, gasoline fueled and spark ignited. The SI engine configuration is shown in figure 1.1, which commonly found in the period.

                                       

                           

                                       Figure1.1: Engine-system

Components of an Engine:-

                                 The major components of an engine as follows

·         Engine block

·        Cylinder

·        Crankshaft

·        Pistons

·        Connecting rods

·        Camshaft

·        Cylinder head

·        Valves

·        Fuel control system

·        Ignition system

·        Exhaust system

·        Cooling system

      As the subject name is Automotive Electronics, one should understand the role of an electronics in Automobiles.

The electronics play a direct role in only the fuel control, ignition and exhaust.

In the present days most of the vehicle are automotive based which mean’s that in future the most number of vehicle are automated. So this blog is helpful for  built up your automotive electronics knowledge.  

·  Engine Block:-
                      
              The engine block is the most important part of vehicles that on internal combustion, providing the power house for the vehicle.

The internal combustion engine is engine which converts the movement of piston to the rotational energy used to drive wheels.

The cylinder are cast in the engine block and machined to smooth finish.

The piston are connected to crankshaft by using connecting rods, as shown in figure 1.2(a)The crankshafts convert the up and down motion of piston to the rotary motion which is used for to drive the wheels.

                             Figure1.2(a) Piston connection to crankshaft

•         Cylinder head :-

                    Cylinders are linear actuators which convert fluid power into mechanical power. Cylinder is used at high pressure and produce large forces and precise movement for this reason they are constructed of strong material like steel.

The cylinder head is having two valves one is for intake and another is for outlet. When both valves are closed, the head remains at the top of the cylinder and the piston rings remains at the bottom of the cylinder.

The fluid pushes against the face of the piston and produces a forces. The force produced is given by the formula

                        F=pA

Where, p=pressure in N/m^2

             A=area the pressure act on in m^2.
    ·        Camshaft:-

                   In internal combustion engines with piston, the camshaft is used to operate poppet valves. It then consists of a cylindrical rod running the length of the cylinder bank with a number of oblong lobes protruding from it, one for each valve.
The camshaft as shown in figure1.2(b).

The cam lobes forces the valves open by pressing on the valve or on some intermediate mechanism as they rotate.

                                          Figure1.2(b) Camshaft

·        Crankshaft:-

                       The crankshaft is located in the engine of vehicle and the force which will generated in engine by piston moving up and down motion this force is converted in circular motion so the vehicle can go forward.

Crankshaft is connected to all pistons in the engine and to the flywheel as shown in figure 1.2(c)

The crankshaft is the part of an engine that translates reciprocating linear piston motion into rotation. To convert the reciprocating motion into rotation, the crankshaft has crank throws or crankpins, additional bearing surface whose axis is offset from that of the crank, to which the big ends of the connecting rods from each cylinder attach.

                                       Figure1.2(c) Crankshafts

Types Of Engine

Main Topics

Concept of this subject is used in Automotive Industries, bike, car, buses and trains.

Which will help full for comfortable, safety traveling and which required minimum effort and force?

•   Introduction of engine
•   Break system
•   Sensors
•   Transmission system
•   Electronic Control Unit
•   Communication Protocol
•   Micro-controller
•  Avr Programing

     
    

Introduction Of Engine

Introduction

Hi friends, This blog is about Automotive Electronics. I will try to cover all the topics of automotive electronics like engines, micro controllers, sensors, communication protocols, embedded c programming, etc.
Our subject is totally based on Application Oriented Subject  "Which will definitely boost up your knowledge level if you have interested to know " how things work?"

This is a subject which you will start loving if you like car, bike and electronics fusion.

      If anyone is looking for a future in Automotive Electronics ,whether a job or self implemented projects (college project's/freelancing) or query is in automotive electronics Please,visit my blog.

                                 I will give detail information about this subject. 

                                   

Main Topics