Hey there! the most fascinating thing on the planet for a mechanical engineer is a machine and this machine is a movable asset. Almost every guy go gaga?? while seeing a super car, girls think what is there in it !!?? . For most people, a car is a thing that takes fuel in it and moves from point A to B. But, have you ever thought how does it work? there is magic under the hood, of course, that magic can’t be seen in an electric car if you have adopted it. So, how does a car engine work exactly?
A car’s heart is an engine and that engine is based on an internal combustion engine that means a blast happening inside which converts into mechanical energy to drive that thing. Here is the glimpse of that heart ❤
Specifically, an internal-combustion engine is a heat engine that converts energy from the heat of burning fuel (petrol/diesel) into mechanical work or torque. That torque is applied to the wheels to make the car move. And unless you are driving an ancient two-stroke (which sounds like an old chain saw and belches oily smoke out its exhaust), your engine works on the same basic principles whether you’re wheeling a Maruti or a Ferrari.
Engines have pistons that move up and down inside metal tubes called cylinders. It is like riding a bicycle with legs you paddle and the chain just pushes your forward through wheels. Here, your legs are pistons and connecting rods are a chain. Depending on the vehicle, there are typically between two and 16 cylinders in its engine, with a piston moving up and down in each.
Arrangement of both petrol and diesel engine components is the same along with mechanism but the only difference that diesel engine makes is it doesn’t have a spark plug, you will be thinking without spark how come diesel is burning in the engine.
Diesel has particles (a tiny thing which we can’t see from eyes) that are pressurized ( through nozzles) in the combustion chamber, thus they reach the auto-ignition (self blasting) temperature. Like this, it completes it’ s cycle of combustion.
What Are The Main Parts Of an Engine?
The main components of internal combustion engine are:-
- Cylinder head
- Combustion chamber
- Connecting rod
- Valve spring
- Piston rings
- Inlet and Exhaust valves
- Spark Plug
How The Torque Or Mechanical Work Is Generated :-
There are two types of internal combustion engine :-
- Two Stroke Engine – ( Bajaj Chetak, RX 100, ships are based on this)
- Four Stroke Engine – ( All bikes and cars are based on this)
Two Stroke Engine :-
As the name implies, the two-stroke engine only requires two-piston movements (one cycle) to generate power. The engine can do produce power after one cycle because the exhaust and intake of the gas occur simultaneously, there is a valve for the intake stroke that opens and closes due to changing pressures.
Besides, due to its frequent contact with moving components the fuel is mixed with engine oil to add lubrication, allowing smoother strokes. Generally, we see at the petrol pump, scooter riders will ask for 4T or 2T oil to pour along with petrol.
Overall, a two-stroke engine contains two processes:
- Compression stroke: The inlet port opens, the air-fuel mixture enters the chamber and the piston moves upwards compressing this mixture. A spark plug ignites the compressed fuel and begins the power stroke.
- Power stroke: The heated gas exerts high pressure on the piston, the piston moves downward (expansion), waste heat is exhausted.
The thermal efficiency of these petrol engines will vary depending on the model and design of the vehicle. However, in general, petrol engines convert 20% of the fuel (chemical) energy to mechanical energy—in which only 15% will be used to move the wheels (the rest is lost to friction and other mechanical elements). There is not enough time in two-stroke for complete exhaust and intake so carbon deposits and complete combustion of fuel don’t happen in it. Thus, this engine has less efficiency in general sense mileage.
Compared to four-stroke engines, two strokes are lighter, more efficient, can use lower-grade fuel, and more cost-efficient. Therefore, the lighter engines result in a higher power-to-weight ratio (more power for less weight). However, they lack the maneuverability possible in four-stroke engines and require more lubrication. This makes two-stroke engines ideal for ships (need to carry a lot of cargo), motorcycles, and lawnmowers—whereas a four-stroke would be ideal for automobiles like cars and trucks.
Four stroke Engines :-
The four-stroke engine is the most common types of internal combustion engines and is used in various automobiles (that specifically
use petrol as fuel) like cars, trucks, and some motorbikes (many motorbikes use a two stroke engine). A four stroke engine delivers one power stroke for every two cycles of the piston (or four piston strokes). There is an animation of a four-stroke engine and further explanation of the process below.
- Intake stroke: The piston moves downward to the bottom, this increases the volume to allow a fuel-air mixture to enter the chamber.
- Compression stroke: The intake valve is closed, and the piston moves up the chamber to the top. This compresses the fuel-air mixture. At the end of this stroke, a spark plug provides the compressed fuel with the activation energy required to begin combustion.
- Power Stroke: As the fuel reaches the end of it’s combustion, the heat released from combusting hydrocarbons increases the pressure which causes the gas to push down on the piston and create the power output.
- Exhaust stroke: As the piston reaches the bottom, the exhaust valve opens. The remaining exhaust gas is pushed out by the piston as it moves back upwards.
The thermal efficiency of these petrol engines will vary depending on the model and design of the vehicle. However, in general, gasoline engines convert 20% of the fuel (chemical energy) to mechanical energy—in which only 15% will be used to move the wheels (the rest is lost to friction and other mechanical elements).
One way thermodynamic efficiency can improve in engines is through a higher compression ratio (this is for our mechanical enthusiast). This ratio is the difference between the minimum and maximum volume in the engine chamber. A higher ratio will allow a larger fuel-air mixture to enter, causing higher pressure, leading to a hotter chamber, which increases thermal efficiency.
As we have read and learned how the main component of a car works. Now, we will see how this chemical work that has been converted into thermal energy is been used to run the car mechanically.
How This Four Stroke Engine’s Thermal Energy Is Converted Into Mechanical Work :-
The combustion engine is assembled into the car with different parts, which help in moving that thing and to call it a car!!
Now, as the engine has pushed this thermal energy and moved the piston down after the first combustion this whole process of four-stroke continues till the engine is switched off.
Thus, the crankshaft is continuously rotating and this rotating energy is transmitted to the flywheel (A flywheel is a mechanical device specifically designed to efficiently store rotational energy) which is connected to the output shaft.
This flywheel has the clutch plates the other side which is engaged (while in running in gear) and disengaged (when depressed the clutch pedal) to change the gear.
This clutch has a mechanism that connects with the gears’ input shaft and transmits this rotary energy from our I.C. Engine to the main transmission shaft that is connected to the wheels through differential gears (a bunch of gears that can share the shaft energy with other gears to rotate the wheels).
Thus, this is how the engine output is used to move the entire vehicle by a clutch, gears, shafts, differential gears, and multiple components that are linked. All the touch-ups of luxury, comfort, and visibility are added to make a car worth buying.
Finally, you got to know the working of your car in detail. I hope this will help you out to understand your vehicle in a better way. You can now identify the vehicle’s problem by just running a mental image of what kind of repair your vehicle needs.
If you liked the content and want more interesting topics to be explained in detail for your understanding, do leave them in comments and subscribe. In case you missed my previous blog here is the link:-http://educationblogs.in/health-body-facts-of-water-that-you-never-know/
Praveen · 13 June 2020 at 8:15 am
Awesome explanation. Liked the simplified working steps of the the engine and the pictorial graphical representation.
karthikb92 · 13 June 2020 at 9:04 am
Thank you pravin ???? am glad you liked it!!
Vijay Kumar · 13 June 2020 at 4:32 pm
It’s nice. Clearly explained.
karthikb92 · 14 June 2020 at 4:26 am
Thank you Vijay ????????