Valve Timing Diagram (2161902) ICE

Valve Timing Diagram for 4 stroke and 2 stroke diesel engine.

1. Gandhinagar Institute of Technology Internal Combustion Engines (2161902) Active Learning Assignment Topics: Valve Timing Diagram For 4 stroke and 2 stroke Diesel Engine Guided By: Prof. Nirav Joshi Branch : Mechanical Engineering Div : 6C-1 Name: Saahil R. Kshatriya Enrolment Number: 150120119164

2. Theoretical Valve Timing Diagram In this type of diagram suction & exhaust valve opens and close at TDC and BDC. Actual Valve Timing Diagram In this type of diagram suction & exhaust valve opens and close after and before TDC and BDC.

3. 4-stroke Diesel & Petrol engine There is mainly four stroke in 4-stroke engine Suction Stroke Compression Stroke Power Stroke Exhaust Stroke

4. STROKE 1 : SUCTION TDC BDC 180 D E G REE Inlet valve SUCTION STROKE During this stroke , inlet valve opens and exhaust valve closed , the pressure in the cylinder will be atmosphere . As the piston moves from the TDC To BDC , the volume in the cylinder increase , while simultaneously pressure decreases. Thi s c r e a t e atmosphere a p r es s u r e di f f e r ence b e t w een the a n d ins i d e o f the c y l i n d e r . D u e t o this pressure difference the petrol and air mixture will enter into the cylinder in S.I.Engine & in C.I.Engine air will enter into the cylinder. Th e c r an k sh a f t ha s n o w made hal f r o ta tion i.e . 180 degree of crank angle. At the end of this stroke, the cylinder will filled completely with charge and inlet valve is closed.

5. COMPRESSION STROKE During this stroke both the inlet valve and exhaust valve are closed, the piston moves from BDC to TDC . As this stroke being performed , the charge contained in the c ylinder wil l be c o m p r essed , t e mpe r a tu r e o f c ha r g e i nc r ea s e s . s o p r es s u r e and The p r oces s of compression is shown in fig. Near the end of this stroke , In S.I.Engine the petrol and air mixture is ignited by the electric spark given out by the spark plug & In C.I.Engine the diesel is spray through nozzle. The combustion of petrol/diesel releases the hot gases which will increases the pressure at the constant volume. TDC BDC

6. POWER STROKE During this stroke both the inlet valve and exhaust valve are closed , the piston moves from TDC to BDC. The high pressure and high temperature burnt gases force the piston to perform this stroke, called power stroke. This stroke is also known as expansion or working stroke. The engine produces mechanical work or power during this stroke. As the piston moves from TDC to BDC , the pressure of hot gases gradually decreases and volume increases. Near the end of this stroke, the exhaust valve opens which will release the burnt gases to the atmosphere. This will suddenly bring the cylinder pressure to the atmospheric pressure. STROKE 3 : POWER OR E X P ANSION

7. EXHAUST STROKE During this stroke, the exhaust valve opens and the inlet valve is closed . The piston moves from BDC to TDC and during this motion piston pushes the exhaust gases (combustion product) out of the cylinder at constant pressure. Again the inlet valve open and the new cycle starts. TDC BDC

8. Theoretical & Actual Valve Timing Diagram For 4-Stroke Diesel Engine

9. Actual Valve Timing For 4-Stroke Diesel Engine I.V.O. → 25° Before T.D.C. I.V.C. → 30° After B.D.C. F.V.O. → 5° Before T.D.C. F.V.C. → 25° After T.D.C. E.V.O. → 45° Before B.D.C. E.V.C. → 15° After T.D.C. Valve Overlap → 30°

10. Theoretical & Actual Valve Timing Diagram For 4-Stroke Petrol Engine

11. Actual Valve Timing For 4-Stroke Petrol Engine I.V.O. → 20° Before T.D.C. I.V.C. → 35° After B.D.C. F.V.O. → 35° Before T.D.C. E.V.O. → 35° Before B.D.C. E.V.C. → 10° After T.D.C. Valve Overlap → 30°

12. 2-Stroke Petrol & Diesel Engine Their is mainly two stroke in 2-stroke engine: Expansion Stroke Compression Stroke

13. At the beginning of the first stroke piston is at the TDC as shown in fig. A. Piston moves from TDC to BDC. The electric spark ignites the compressed charge in petrol engine & Diesel spray in diesel engine when compression stroke is about complete . The combustion of the charge will release the hot gases which increase the temperature and pressure in cylinder. The high pressure combustion engine to force piston downward . The piston perform power stroke till it uncovers the exhaust port As shown in fig. B. The combustion gases which are at the pressure slightly higher than atmosphere pressure escape through exhaust port. The piston uncovers the transfer port the fresh charge flow from the crankcase into cylinder through transfer port as shown in fig. B. Which enters the cylinder pushes the burnt gases , so more amount of exhaust gases come out through exhaust port as shown in fig. B. This swiping out of exhaust gases by incoming fresh charge is called scavenging. This will continue till the piston covers both the transfer and exhaust port during next upward stroke. First stroke

14. Fig. A Beginning of the first stroke Fig. B Piston uncovers transfer port During first stroke First stroke

15. Second Stroke In this stroke piston moves from BDC to TDC. When it covers the transfer port in fig. C. , the supply of charge is stopped and then when it moves further up it covers the exhaust port completely in fig. D stop the scavenging. Further upward motion of the piston will compressed the charge in the cylinder. After the piston reaches TDC the first stroke repeats again .

16. Second Stroke Fig. C. Transfer port covered Fig. D. Compression commenced

17. Theoretical & Actual Valve Timing Diagram For 2-Stroke Petrol Engine

18. Actual Valve Timing For 2-Stroke Petrol Engine → 70° After B.D.C. → 60° Before B.D.C. → 60° After B.D.C. → 50° Before T.D.C. → 50° After T.D.C. E.P.O. → 70° Before B.D.C. E.P.C. T . P . O . T.P.C. I.P.O. I.P.C.

19. Theoretical & Actual Valve Timing Diagram For 2-Stroke Diesel Engine

20. Actual Valve Timing For 2-Stroke Diesel Engine E.P.O. → 80° Before B.D.C. E.P.C. → 80° After B.D.C. T.P.O. → 60° Before B.D.C. T.P.C. → 60° After B.D.C.

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