Based upon the number and arrangement of cylinder, automobile engines may be classified as:
1. Single cylinder engines
2. Two cylinder engines
3. Three cylinder engines
4. Four cylinder engines
5. Six and eight cylinder engines
6. Radial engines
These will now be discussed in detail.
SINGLE CYLINDER ENGINES : A single cylinder engine has a power stroke every 720 of crankshaft oration for a four-stroke engine. These are used generally for scooters and motorcycles. It is seen that the maximum size of the signal cylinder engine is restricted to about 500-600 c.c., because of the higher unbalance forces, which become difficult to be balanced. Further the weight of the fly wheel required becomes excessive for height engine sizes.
TWO CYLINDER ENGINES: This type engine, apart from providing more power, gives more uniform torque and balancing possible is also better as compared to single cylinder engines. However, in practice two cylinder engines are rarely employed for automotive three different types of 2-cylinder engines.
(A) In-line type cylinders placed side by side. This type has two single cylinders placed side by side vertically so that their pistons are in phase. Such an engine will have a power impulse every 360 degrees of crankshaft rotation.
(B) In-line, cylinders 180 out of phase. In this the two single cylinders are in effect, placed side by side vertically, so that their cranks are 180 out of phase. This type provides good balancing, but the disadvantage is in unequal firing intervals: the spark takes place at 0 , 180 , 720 , 900, and so on.
(C) V-type. In this two cylinders are placed with their center lines at some angle to each other. Generally this angle is kept 60 , but in some instances angles from 40 to 90. Have also been used.
(D) Horizontally opposed type. The two cylinders are arranged horizontally opposite each other, as shown in this type power impulses occur at even Intervals of 360 of crankshaft rotation. As is evident from the figure, the Piston and the connecting rod movements are identical, i.e. both the pistons approach TDC and BDC posi-tions together. This causes the engine to be perfectly balanced, as regards the reciprocating forces. But because the two cylinders are not in line, the forces in the rods produce a rocking couple, in the vehicle. This hinders proper streamlining of the car.
THREE CYLINDER ENGINES : In-three-cylinder in-line engine the power impulse occurs every 240 of crankshaft rotation. These are dynamically balanced, but there remain some unbalanced rocking forces. However, the three cylinder ders smooth out the cyclic torque adequately so that this has becimb a good improved fuel consump-tion. Maruti 800 vehicles in India employ this engine.
FOUR CYLINDER ENGINES: In this type, the torque obtained, as compared to a single cylinder engine, is much more uniform because two working strokes per revolution are obtained. Further, the balancing is also better. Apart from this, the maintenance is also easier as compared to the engines with larger number number of cylinder.
SIX AND EIGHT CYLINDER ENGINES: Fom higher h.p. and smoother torque, the six and eight cylinder engines have been used. Like the four -cylinder engines, they have also been designed in the from of in-line, V-type and opposed type configurations. In six-cylinder in-line engine, there is a power impulse every 120 of crankshaft rotation. Commonly employed firing order is 1-5-3-6-2-4, whereas equally suitable firing order also used in 1-4-2-6-3-5. This engine has smoothness of torque and excellent dynamic balance. For this reason its use is quite common for engine sizes larger than 2.5 litres, provided length of engine is not the main consideration. V-8 engines with smaller V-angles, say 20 , have also been made. The advantages of narrow V are less torsional vibrations and increased stiffness. However, the valve-operating mechanism is complicated.
RADIAL ENGINES : In this case the various cylinder are arranged in radial directions. About the crankshaft which is placed at the number of cylinders generally used is odd, say 5,7,9stc., To obtain uniform firing intervals. This type of engine is compact and gives higher B.H.P./ weight ratio. The construction is also simpler. However, this engine had a very large frontal area, which crests difficulty in streamlining the vehicle shape.
1. Single cylinder engines
2. Two cylinder engines
3. Three cylinder engines
4. Four cylinder engines
5. Six and eight cylinder engines
6. Radial engines
These will now be discussed in detail.
SINGLE CYLINDER ENGINES : A single cylinder engine has a power stroke every 720 of crankshaft oration for a four-stroke engine. These are used generally for scooters and motorcycles. It is seen that the maximum size of the signal cylinder engine is restricted to about 500-600 c.c., because of the higher unbalance forces, which become difficult to be balanced. Further the weight of the fly wheel required becomes excessive for height engine sizes.
SINGLE CYLINDER ENGINES
TWO CYLINDER ENGINES: This type engine, apart from providing more power, gives more uniform torque and balancing possible is also better as compared to single cylinder engines. However, in practice two cylinder engines are rarely employed for automotive three different types of 2-cylinder engines.
(A) In-line type cylinders placed side by side. This type has two single cylinders placed side by side vertically so that their pistons are in phase. Such an engine will have a power impulse every 360 degrees of crankshaft rotation.
(B) In-line, cylinders 180 out of phase. In this the two single cylinders are in effect, placed side by side vertically, so that their cranks are 180 out of phase. This type provides good balancing, but the disadvantage is in unequal firing intervals: the spark takes place at 0 , 180 , 720 , 900, and so on.
(C) V-type. In this two cylinders are placed with their center lines at some angle to each other. Generally this angle is kept 60 , but in some instances angles from 40 to 90. Have also been used.
(D) Horizontally opposed type. The two cylinders are arranged horizontally opposite each other, as shown in this type power impulses occur at even Intervals of 360 of crankshaft rotation. As is evident from the figure, the Piston and the connecting rod movements are identical, i.e. both the pistons approach TDC and BDC posi-tions together. This causes the engine to be perfectly balanced, as regards the reciprocating forces. But because the two cylinders are not in line, the forces in the rods produce a rocking couple, in the vehicle. This hinders proper streamlining of the car.
THREE CYLINDER ENGINES : In-three-cylinder in-line engine the power impulse occurs every 240 of crankshaft rotation. These are dynamically balanced, but there remain some unbalanced rocking forces. However, the three cylinder ders smooth out the cyclic torque adequately so that this has becimb a good improved fuel consump-tion. Maruti 800 vehicles in India employ this engine.
THREE CYLINDER ENGINES
FOUR CYLINDER ENGINES: In this type, the torque obtained, as compared to a single cylinder engine, is much more uniform because two working strokes per revolution are obtained. Further, the balancing is also better. Apart from this, the maintenance is also easier as compared to the engines with larger number number of cylinder.
FOUR CYLINDER ENGINES
SIX AND EIGHT CYLINDER ENGINES: Fom higher h.p. and smoother torque, the six and eight cylinder engines have been used. Like the four -cylinder engines, they have also been designed in the from of in-line, V-type and opposed type configurations. In six-cylinder in-line engine, there is a power impulse every 120 of crankshaft rotation. Commonly employed firing order is 1-5-3-6-2-4, whereas equally suitable firing order also used in 1-4-2-6-3-5. This engine has smoothness of torque and excellent dynamic balance. For this reason its use is quite common for engine sizes larger than 2.5 litres, provided length of engine is not the main consideration. V-8 engines with smaller V-angles, say 20 , have also been made. The advantages of narrow V are less torsional vibrations and increased stiffness. However, the valve-operating mechanism is complicated.
SIX AND EIGHT CYLINDER ENGINES
RADIAL ENGINES : In this case the various cylinder are arranged in radial directions. About the crankshaft which is placed at the number of cylinders generally used is odd, say 5,7,9stc., To obtain uniform firing intervals. This type of engine is compact and gives higher B.H.P./ weight ratio. The construction is also simpler. However, this engine had a very large frontal area, which crests difficulty in streamlining the vehicle shape.
RADIAL ENGINES
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