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March 31, 2021
 A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed. Energy is transferred to a flywheel by applying torque to it, thereby increasing its rotational speed, and hence its stored energy. Conversely, a flywheel releases stored energy by applying torque to a mechanical load, thereby decreasing its rotational speed.






Flywheel is a circular wheel (or Disc) made up of steel or cast iron (depends upon the application). It also acts as part of clutch mechanism and fluid drive unit. It has teeth on its outer edge which is meshed with the teeth of the electric cranking motor driven pinion and it used to crank (to rotate crankshaft) the engine during its starting.


Working of Flywheel

To understand that lets take an example of working of single cylinder four stroke engine. In four stroke engine we have four strokes i.e. suction, compression, power and exhaust stoke. Only in the power stroke we get power and in the rest of the strokes, the power is required to perform different process like suction, compression and exhaust process. So we need a device which can stores the power during power stroke and deliver that power to the remaining strokes when required. This could be done with the use of a flywheel. The flywheel stores the power during the expansion or power stroke and then imparts this power to the remaining strokes of the engine for its working.

The Flywheel is made of heavy steel or cast iron and it is attached to the rear end of the crankshaft. The weight of the flywheel depends upon the nature of the variation of the pressure, number of cylinder and design of engine.

The weight of the flywheel decreases with the increase in the number of cylinder. It means a two cylinder engine has lighter flywheel as compared with single cylinder engine.


Main Function of the Flywheel

  1. It provides constant power output where there is a fluctuation in the power is observed.
  2. It maintains the constant speed of the engine during all the strokes.
  3. It stores the mechanical energy (rotational energy) of the engine and deliver it  when required.


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March 25, 2021
 This is a smart type of fuel injector which is controlled electronically by the electronic control unit of the engine which is also known as brain of modern engines.

Electronically controlled fuel injectors consist of following parts –






  • Injector body- Same as the mechanically controlled fuel injector the body of this type of injector is a precisely designed hollow shell inside which all the other components are arranged.
  • Plunger- Same as the mechanically controlled fuel injector a plunger is used for the opening and closing of the nozzle but in electronically controlled fuel injector the opening of the nozzle is controlled electronically with the help of electromagnets.
  • Spring – Same as the mechanically controlled fuel injector a plunger spring is used to hold the plunger in its position in order to close the nozzle of the fuel injector when required.
  • Electromagnets – Unlike mechanically controlled fuel injector this type of injector is equipped with electromagnets just around the plunger which controls the opening of the nozzle by taking the electronic signal from the electronic control unit of the engine through the electronic plug or connection connecting the fuel injector with the electronic control unit of the engine.
  • Electronic plug/connection- At the top end of electronically controlled fuel injector a connection/plug is present through which the electronic signal from the electronic control unit of the engine is transferred to the electromagnets which in turn opens the nozzle in order to spray the fuel.

Working 

  • The fuel pump start pumping the fuel to the fuel injector and the timing, amount and pressure of the fuel entering the fuel injector is governed by the electronic control unit.
  • The electronic control unit sends the electronic signal to the fuel injector with the help of the electronic connection, due to these electronic signals from the ECU the electromagnets inside the fuel injector got activated which in turn pushes the plunger outward results in opening of the nozzle and finally the spray of the fuel takes place.
  • After completing this particular cycle the electronic signal from the ECU stops which in turn deactivates the electromagnets due to which the plunger returns to its initial position results in closing of the nozzle and the spray of the fuel stops.
  • The closing of the nozzle is maintained by the plunger spring.
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March 24, 2021

A Traction Control System ( TCS ), also known as Anti-Slip Regulation ( ASR ), is typically (but not necessarily) a secondary function of the anti-lock braking system on production vehicles , and is designed to prevent loss of traction of the driven road wheels, and therefore maintain the control of the vehicle when excessive throttle is applied by the driver and the condition of the road surface (due to varying factors) is unable to cope with the torque applied.






The basic idea behind the need of a traction control system is the difference between the slips of different wheels or an apparent loss of road grip that may result in loss of steering control over the vehicle.


Difference in slip may occur due to turning of a vehicle or differently varying road conditions for different wheels. At high speeds, when a car tends to turn, its outer and inner wheels are subjected to different speed of rotation, that is conventionally controlled by using a differential.


Imagine you are accelerating from a stop on an icy road in a front-wheel drive vehicle without Traction Control. If you accelerate very gently, you might be OK, but if you press the gas pedal just a bit harder, one or both front wheels could lose traction and begin to spin on ice, so the vehicle would be very hard to control.


The Traction Control is designed to help in a situation like this. Once the Traction Control System senses that any of the drive wheel(s) starts slipping, it reduces the engine torque and shortly applies the brake to the slipping wheel(s) to slow it down just enough to regain traction, thus helping you to control your vehicle during acceleration.


Typical Traction Control system is based on vehicle's Anti-lock braking system (ABS) and uses many of ABS components. It utilizes the ABS wheel speed sensors to monitor the speed of all four wheels.


When Traction Control system senses that the wheel looses traction (begins to rotate faster) during acceleration, it applies the brakes to that wheel using the ABS hydraulic module and commands the Engine Control Module to reduce the engine power. When Traction Control system operates, you could probably feel that the engine power is reduced and hear some buzzing noise similar to that of ABS. The Traction Control light may also flash.


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March 08, 2021

 A compression ratio (CR) of an I C engine is the ratio of the total volume of the combustion chamber To the volume left after complete compression i.e. clearance volume. In simple words, it is the ratio between the total volume of the combustion chamber which is left when the piston is at its bottom dead center and the volume left inside the combustion chamber when the piston moves to its top dead center.






For example- Let’s consider an engine having 1000cc total volume out of which 900cc is the swept volume i.e. the volume covered by the piston when it moves from BDC to TDC, and having 100cc clearance volume i.e. the volume left inside the cylinder when the piston reached to its TDC. So the compression ratio of this engine will be 1000:100 or 10:1.

It is found that greater the compression ratio more will be the power output of the engine.

The compression ratio of diesel engine is much higher than that of petrol engine. i.e. for petrol engine the CR varies from 10:1 to 14:1 and for diesel engines, the CR varies from 18:1 to 23:1.


1. Petrol Engine-

If we talk about 4-stroke petrol engine the compression ratio has its own significance that are-

  • As we all know the in petrol engine air-fuel mixture enters the combustion chamber during the suction stroke and for proper mixing and for proper combustion of this air-fuel mixture compression of this mixture is required which is done by the engine in its compression stroke, so a good compression ratio of the petrol engine is required for proper combustion of the air-fuel mixture which in turn provides better thermal efficiency.
  • The pressure inside the cylinder increases during compression stroke which in turn raises the temperature of the air-fuel mixture that leads to complete or proper combustion of the fuel when the spark plug produces spark which in turn provides better fuel economy and also prevents the engine from various defects like knocking.
  • The petrol engine with proper CR provides a balanced amount of power and speed.
  • The petrol engine usually comes with 10:1 to 14:1 compression ratio depending upon the application and design requirement.





2. Diesel Engine-

When it comes to diesel engines the compression ratio has its greater significance as-

  • In diesel engine a high CR is required  as the diesel engine doesn’t  have any spark plug so the combustion of the fuel completely depends upon the compression of the air provided by the compression stroke of the diesel cycle because of which diesel engine is also known as compression ignition engine.
  • The diesel engine with high compression ratio provides the engine with high compression i.e. provides high pressure rise, which is required to increase the temperature of the compressing air to the extent of the auto ignition temperature of the fuel that is to be sprayed by the fuel injectors which in turn provide complete or proper combustion of fuel.
  • The diesel engines are known for providing high power output which is due to the high compression ratio of the diesel engine, as we know higher the CR higher will be the thermal efficiency or work output.
  • A diesel engine with high CR provides high fuel economy due to the higher thermal efficiency provided by the high compression combustion.
  • Diesel engines usually come with higher compression ratios varies from 18:1 to 23:1 depending upon the application and the design requirement.






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