The document provides an overview of automobile engineering, including the classification and components of engines, engine systems, and types of vehicles such as four-wheel drive and multi-cylinder engines. It details the functions and structures of essential engine parts like the crankshaft, camshaft, and piston, as well as the significance of balanced firing orders for optimal performance. Additionally, it highlights the advantages and disadvantages of different engine settings and outlines the core engine systems necessary for operation.

1. Subject
Automobile Engineering
Unit No 1
By:- Prof. Prashant B. Borakhede
Assistant Professor,
MGI-COET, Shegaon

2. History of Development

6. Classification of Automobile

8. Components of Automobile

9. General Layout of Automobile

15. Types of Chassis Layout

24. Four Wheel Drive
• Four-wheel drive (4WD) refers to vehicles with two axles providing
torque to four axle ends.
• Selectable 4WD has both axles rigidly coupled together, which has
some advantages in very poor off-road conditions.
• To gain the same advantage in a permanent AWD system with a
differential, the differential can be locked manually with a differential
lock.
• To get enough Traction between wheels and road surfaces.
• To move vehicles on slippery surface, dirt, muddy roads, sand roads,
snowy roads etc.

25. Disadvantages
• The main disadvantage of 4WD is added cost for purchase,
maintenance, and fuel.
• The extra equipment (differentials, transfer case, etc.)
adds complexity and weight to the vehicle,
increasing initial market value, tire wear,
and the cost of repairs and maintenance.

26. Automobile Engine
Classification

29. Engine Components

30. Parts of Engine
• Engine block
• Piston
• Cylinder Head
• Crank Shaft
• Camshaft
• Timing belt
• Engine Valves
• Oil Pan
• Combustion
chamber
• Intake manifold
• Exhaust manifold
• Intake and Exhaust
• valves
• Spark Plugs
• Connecting Rod
• Piston Ring
• Gudgeon pin
• Cam
• Flywheels
• Head gasket
• Cylinder Liner
• Crank Case
• Distributor
• Distributor o ring
• Cylinder head cover
• Rubber grommet
• Camshaft pulley
• Oil filter
• Water pump
• Timing belt drive
pulley
• Oil pan drain bolt

31. Parts of Engine
Engine Block –
• Often made of aluminum or iron, it has several holes to contain the cylinders
as well as provide water and oil flow paths to cool and lubricate the engine.
• Oil paths are narrower than the water flow paths. The engine block also
houses the pistons, crankshaft, camshaft, and between four and twelve
cylinders—depending on the vehicle, in a line, also known as inline, flat or in
the shape of a V.

32. Pistons –
Are a cylindrical apparatus with a flat surface on top.
• The role of the piston is to transfer energy created from
combustion to the crankshaft to propel the vehicle.
• Pistons travel up and down within the cylinder twice
during each rotation of the crankshaft. Pistons on
engines that rotate at 1250 RPM, will travel up and
down 2500 times per minute.
• Inside the piston, lie piston rings that are made to help
create compression and reduce the friction from the
constant rubbing of the cylinder.
Piston Ring-
• It is used to form a seal for the high pressure gases from
the combustion chamber against leak into crank case.
• To provide easy passage for heat flow from the piston
crown to the cylinder walls.

33. Crankshaft–
• The crankshaft is located in the lower
section of the engine block, within the
crankshaft journals (an area of the shaft
that rests on the bearings).
• This keenly machined and balanced
mechanism is connected to the pistons
through the connecting rod.
• Similar to how a jack-in-the-box
operates, the crankshaft turns the
pistons up and down motion into a
reciprocal motion, at engine speed.

34. Camshaft –
• Varying from vehicle to vehicle, the camshaft
may either be located within the engine block or
in the cylinder heads.
• The role of the camshaft is to regulate the timing
of the opening and closing of valves and take
the rotary motion from the crankshaft and
transfer it to an up and down motion to control
the movement of the lifters, moving the
pushrods, rockers, and valves.
Cylinder Head
• Attached to the engine through cylinder bolts,
sealed with the head gasket.
• The cylinder head contains many items
including the valve springs, valves, lifters,
pushrods, rockers, and camshafts to control
passageways that allow flow of intake air into
the cylinders during the intake stroke as well as
exhaust passages that remove exhaust gases
during the exhaust stroke.

35. Timing Belt/Chain –
• The camshaft and crankshafts are
synchronized to ensure the precise timing in
order for the engine to run properly.
• The belt is made of a heavy-duty rubber with
cogs to grasp the pulleys from the camshaft
and crankshaft.
• The chain, similar to your bicycle chain wraps
around pulleys with teeth.

36. Engine Systems
1. Cooling Systems
This prevents the engine from overheating. It may be of air cooling or water
cooling.
2. Fuel System
This includes storage tank of fuel, piping work for supply to the engine and
arrangement for mixing with air and spraying into the engine cylinder.
3. Exhaust System
Its function is to vent exhaust gases with least back pressure and also to
reduce engine noise with the help of muffler.
4. Lubricating System
It reduces friction to decrease wear of moving parts. Relatively less viscous
lubricating oils are used in engine, whereas heavier oils and greases are used
in transmission and wheel bearing.

37. 5. Ignition System
Its function is to supply high voltage surge at the desired instant and of
adequate strength to produce a spark in the engine.
6. Electrical System
It consists of a storage battery, charging system and starting system.
Battery supplies electricity for starting the engine, providing energy for
spark and for all the electrical devices in the vehicle e.g. lighting,
heating, visiting, music system etc.

38. Multi cylinder Engines
• A multi-cylinder engine is a reciprocating internal combustion engine with
multiple cylinders.
• It can be either a 2-stroke or 4-stroke engine, and can be either Diesel or
spark-ignition.
• Multi-cylinder engines offer a number of advantages over single-cylinder
engines, chiefly with their ability to neutralize imbalances by having
corresponding mechanisms moving in opposing directions during
the operation of the engine.
• A multiple-cylinder engine is also capable of delivering higher revolutions
per minute (RPM) than a single-cylinder engine of equal displacement,
because the stroke of the pistons is reduced, decreasing the distance
necessary for a piston to travel back and forth per each rotation of the
crankshaft, and thus limiting the piston speed for a given RPM.

39. • Although there are 1, 3 and 5-cylinder engines, almost all other inline engines
are built with even numbers of cylinders, as it's easier to balance out the
mechanical vibrations.
1. Single Cylinder Engine:-
i. It has a power stroke every 720 degree of crankshaft rotation for a four
stroke engine.
ii. These are genrally used for scooters and motor cycles.
2. Two cylinder Engine:-
i. This type of engine provides more power, gives more torque and balancing
is better as compared to single cylinder engine.
ii. There are three types of these engines
a) Inline type cylinders placed side by side.
b) Inline cylinders 180 degree out of phase.
c) V type .

40. 3. Four Cylinder Engines
• In this type, torque obtained, as compared to a single cylinder engine, is
much more uniform because two working strokes per revolution are
obtained. Further balancing is also better.
• Maintenance is also easy .
• Four cylinder engine are all inline.
Second and third cylinders are in phase
Also first and fourth cylinders are in phase but
direction is opposite. Thus reciprocating forces
are also nearly balanced. Firing order 1-3-4-2 or 1-2-4-3.
Types
a) Inline Vertical Type
b) V type
c) Horizontal opposite flat type.

41. 4. Six cylinder Engines
• For higher h.p. and smoother torque, six and eight cylinder engines
have been used.
• In six cylinder engine, there is a power
Impulse every 120 degree of crankshaft
Rotation. Thus crankshaft consist of six cranks
Arranged in pairs in three planes.
Commonly employed firing order is 1-5-3-6-2-4
Engine has smoothness of torque and excellent dynamic balance.

42. Engine Balancing
• Due to the presence of the number of reciprocating parts, like piston,
connecting rod, etc. which move once in one direction and then in other
direction, vibration develops during operation of the engine.
• Excessive vibration occurs if the engine is unbalanced. It is, therefore,
necessary to balance the engine for its smooth running.
• The vibration may be caused due to design factors or may result from poor
maintenance of the engine.
• In order to minimize the vibration, attention must be given to the following
parameters :
i) Primary balance
ii) Component balance
iii) Firing interval
iv)Secondary balance.

43. Primary Balance
• When a piston passes through TDC and BDC, the change of direction
produces an inertia force due to which the piston tends to move in the
direction in which it was moving before the change.
• This force, called the primary force, increases with the rise of the engine
speed, and unless counteracted produces a severe oscillation in the vertical
plane, i.e., in line with the cylinder axis.
• Component Balance
• To minimize vibration, all components that rotate at high speeds must be
balanced.
• This is specifically important for large heavy components such as a flywheel
and clutch assembly.
• Ideally the balancing of both the crankshaft and flywheel assembly as one
unit is desirable because it avoids the ‘build-up of tolerances’.

44. Firing Interval
• The angle turned by the crankshaft between power strokes of a multi-
cylinder engine should be regular to achieve maximum smoothness.
• Also if the more cylinders are fired during the 720
degrees period of the four-stroke cycle, the lower is the variation in
the output torque, and the smoother is the flow of power to the road
wheels.

45. Firing Order
• Engine has pistons which convert their reciprocating motion to rotary of
the crankshaft.
• The power to turn the crankshaft is made available to the piston by the
occurrence of combustion inside the combustion chambers (cylinders)
that house the pistons.
• Therefore the movement of the pistons, must be coordinated to ensure
continuous production of power as long as the ignition is on, engine is
running, and all other enabling
• Firing order of a multi cylinder engine is the power delivering
sequence of each cylinder which is set by the designer such that the
combustion of fuel in different cylinders occurs in a predefined order
that can produce uninterrupted and maximum power output through the
crankshaft of an multi-cylinder engine conditions are met.

46. Firing order of Inline 4 cylinder Engine (Maruti Suzuki Swift)
• The firing order is configured as 1-3-4-2 which means all the cylinders will
have firing or the spark plug ignition according to the 1-3-4-2 sequence.
• In a 4 cylinder engine a complete firing
order gives 720 degrees of the crankshaft
rotation which means each power stroke
by the individual piston gives 180 degree
of rotation to the crankshaft.
• For the smooth working of a 4-cylinder
• engine it is required that each cylinder will have different stroke at any
instant for example:-
At any instant in a inline 4-cylinder engine usually it is seen that when cylinder 1
is having power stroke than cylinder 4 is usually seen to be suction stroke,
cylinder 2 and cylinder 3 are usually seen to be at exhaust and compression
stroke respectively.

47. Firing order of Inline 6 cylinder Engines
• In the high end cars like Honda Accord
and Audi A-8, high power engine having
multiple cylinders are used as in Honda
Accord, 6 cylinder engine placed in
V-shape is used in which a proper and effective firing order is required.
• Firing order is 1-5-3-6-2-4 means the crank pins having piston mounted are
arranged in every 60 degree of the crankshaft.
• As the power impulse is generated in every 720 degree rotation of the
crankshaft which means that power stroke in V6 engine is obtained in every
120 degree rotation of the crankshaft.

48. Requirement of firing order
• Four stroke engine includes suction, compression, expansion, exhaust
strokes.
• If cylinders are more than one then working process is complex so a pre-
defined sequence of combustion or firing of fuel is required as-
i) If pistons are more than one load over the crankshaft increases as all the
pistons are connected to the single crank shaft and if the proper firing
order is not provided to the engine than there will be the chances of the
crankshaft failure.
ii) Out of the all 4-strokes power stroke is the strongest and generates
various stresses (mechanical or thermal both) that can cause engine
failure like knocking, so it is essential for a multi-cylinder engine that the
power strokes in any 2 adjacent cylinders must not occur at the same time
due to which an engine must have a pre-defined and proper firing order.
iii) The improper firing order can affect the engine and crankshaft balancing
due to the generation of uncontrolled stresses due to which harsh running,
unwanted sound and unwanted vibration can be obtained.