It can be thought of as mean effective pressure lost due to friction. P MEP is the pumping mean effective pressure, which is the mean effective pressure calculated from work moving air in and out of the cylinder due to inlet throttling losses and residual gases in outlet.į MEP is the friction mean effective pressure, which is the theoretical mean effective pressure required to overcome engine friction. Direct i MEP measurement requires combustion pressure-sensing equipment. Thus the engine starts by sucking air-fuel mixture into it & then follows the above cycle.I MEP is the indicated mean effective pressure, which is the mean effective pressure calculated from in-cylinder pressure-the average in-cylinder pressure over the engine cycle (720° in a four-stroke and 360° in a two-stroke). The answer is when you insert your key into your car to turn “on”, the battery turns a small motor which is meshed with the larger gear of the flywheel. How does the engine start OR when you start the engine how does the piston come down ? The mixture is so highly compressed that it is able to ignite itself. Spark plug is only used in petrol engines & so used here. You might like – Differences, Advantages & Disadvantages of 4 stroke & 2 stroke engine ! SourceĪgain, it proves that sometimes all we need is simple design. A rotating cam on a camshaft !Ībove animation – A cam on a camshaft converting rotational motion into oscillatory motion of valves thereby opening & closing the valves at the exact times. The camshaft is connected to crankshaft via a gear mechanism or meshed with the help of timing chain. The answer is so amazing & solution is damn easy – Camshaft !
Well, they are not timed with a help of timer or clock (humour me). How do inlet & outlet valves open & close at that particular times of strokes ? 4 strokes = 4 processes !) Suggested article – How do 2 stroke engines work ?
#4 stroke ic engines series#
Here, series of thermodynamic processes happening are during the strokes. Here completes two complete rotation(720°) of the crankshaft along with one cycle ( One cycle because, a thermodynamic cycle is a series of thermodynamic processes which returns a system to its initial state. Exhaust Stroke :-Īgain the momentum of flywheel moves the piston up from BDC to TDC thereby driving the exhaust gases outside through the exhaust valve. This stroke produces mechanical work to rotate the crankshaft.Ĭrankshaft rotation – 180° (total = 540°) 4. Power stroke begins with the expansion of air-fuel mixture ignited with the help of spark plug.
#4 stroke ic engines full#
The second rotation of crankshaft has begun as it completes one full rotation during compression stroke. The momentum of flywheel helps the piston to move upwards.Ĭrankshaft rotation – 180° (total = 360°) source :- 3. Here, the piston moves from BDC to TDC compressing the air-fuel mixture. The piston moves downward sucking the air-fuel mixture from the intake valve.Ĭrankshaft rotation – 180° 2. In this stroke, the piston moves from TDC to BDC. The four strokes of a 4 stroke engine go by the name – 1. Spark Plug– A spark plug delivers electric current to the combustion chamber which ignites the air-fuel mixture leading to abrupt expansion of gas. Inlet & Outlet valves – It allows to enter fresh air with fuel & to exit the spent air-fuel mixture from the cylinder. The piston is able to do this because it is secured tightly within cylinder using piston rings to minimize the clearance between cylinder and piston !Ĭrankshaft – A crankshaft is a part which is able to convert the reciprocating motion to rotational motion.Ĭonnecting rod – A connecting rod transfers motion from a piston to crankshaft which acts as a lever arm.įlywheel– Flywheel is a rotating mechanical device which is used to store energy.
Piston– In an engine, piston is used to transfer the expanding force of gases to mechanical rotation of crankshaft via a connecting rod. Let us come to the parts which a 4 stroke engine has, The four stroke engine was first demonstrated by Nikolaus Otto in 1876, hence it is also known as the Otto cycle. A cycle gets completed when all the 4 strokes get completed. A stroke refers to the piston travelling full in either of the direction. The name itself gives us an idea – it is an Internal Combustion Engine where the piston completes 4 strokes while turning the crankshaft twice. Intake 2.Compression 3.Power 4.Exhaust ! Credits – Zephyris It is very easy to understand until & unless you wanna do all the thermodynamic calculations & all that stuff ! 4 Stroke Engine :- 4 stroke engineĪnimation – 1. These are the most basic engines used in cars & bikes i.e Four stroke cycle petrol engine OR 4 stroke engine(often called).