Basics of Automotive systems

By
Prof. Dilip Sharma
Mechanical Engineering Department
M.N.I.T. Jaipur
 Introduction to Automobiles
• Automobile: Self propelled vehicle used to transport
passengers and goods on ground.
• Vehicle: Device used to transport passengers and goods.
• History: 1769 Nicholas Cugnot build a three wheeled
steam engine operated vehicle.
1897 Rudolf Diesel invented IC engine.
1906 Commercial production of automobile
started.
Till date the basic structure of automobiles hasn’t
changed Much, though a lot of improvement has taken
in all directions.
 Classification of Automobiles
• Purpose
• Capacity
• Fuel
• Number of wheels
• Drive of wheels
• Construction
• Body and number of doors
 Power Plants/ Engines
• Cycle of operation
• Cycle of combustion
• Arrangement of cylinders
• Use
• Speed of engine
• Method of ignition
• Method of cooling
• Method of governing
• Type of fuel used
• Fuel supply system
• Air intake process
 Cooling systems

• Air cooled engines

• Water cooled engines
• Liquid cooled engines
Water cooled/ liquid cooled engines
 Transmission system
Clutch Transmission/ Gear Overdrive Propeller Shaft and
box Differential

Friction clutch Sliding Mesh Gear box Free wheel Universal joint
(a)Single plate unit (a) Cross type
(b)Multi plate (i) Wet (b) Ball and trunnion type
(ii) Dry (c) Constant velocity type
(c) Cone clutch (i) External
(ii) Internal
Centrifugal clutch Constant mesh gear box Epicyclic (a) Hotchkiss drive
gear (b) Torque tube drive
Semi centrifugal clutch Synchromesh gear box Solenoid and Differential
pawl
assembly
Diaphragm clutch Epicyclic gear box Rail and fork Rear axle
assembly
Positive clutch Hydraulic torque convertor
Dog and spline clutch
Hydraulic Clutch
Vacuum clutch
Electromagnetic clutch
Single plate friction clutch
Multi plate clutch and cone clutch
Centrifugal and Semi-centrifugal Clutch
Hydraulic, Vacuum and Electromagnetic
Clutch
Sliding mesh and Constant mesh gear box
Synchromesh Gear box
Epicyclic gear box and hydraulic torque
convertor
 Epicyclic Gearbox
Automatic gearboxes typically
use one or more compound
planetary gearsets instead of
chaining regular gearsets
together.
They look just like a regular
planetary gearset from the
outside, but inside there are two
sun gears and two sets of
intermeshing planet gears.
There is still only one ring gear
though.
 Epicyclic Gearbox
• In such gear boxes epicyclic
gear trains are employed to
get the various gear ratios.
• The characteristic feature of
an epicyclic gearing is that at
least one wheel not only
rotates about its own axis
but also rotates about some
other axis.
Epicyclic Gearbox
Overdrive
Universal joints
Hotchkiss drive and Torque tube drive
Differential
 Rear axle

Semi floating Rear axle Three quarter floating Rear axle full floating Rear axle
 Running system
Wheels and Steering Front axle Suspension Brakes
tyres
Wheels Steering Gear (a) Live front axle Rigid axle front Mechanical Brakes
(a) Disc wheels (a) Worm and Sector SG (b) Dead front axle suspension (a) Drum brakes
(b) Wire wheels (b) Worm and roller SG
(c) Split wheels (c) Worm and ball bearing nut SG
(d) Heavy vehicle (d) Cam and peg SG
wheels (e) Cam and double lever SG
(f) Cam and roller SG
(g) Recirculating ball SG
(h) Rack and pinion SG
Tyres Steering Geometry Stub axle Independent front axle Hydraulic Brakes
(a) Tube tyres (a) Camber suspension (a) Drum Brakes
(b) Tubeless Tyres (b) Caster (a) Coil spring type (b) Disc Brakes
(c) King pin inclination (b) Twin I beam
(d) Toe-in and toe-out (c) Torsion bar
Tyre Treads Condition for correct steering Rear suspension Vacuum Brakes

Tyre Inflation Integral power steering Power brakes

Linkage power steering

Electric power steering

 Wheels

Wheels
(a)Disc wheels
(b)Wire wheels
(c)Split wheels
(d)Heavy vehicle wheels
 Tyres and Treads

Cross ply and Radial ply tyres Tyre Treads

Condition for correct steering
Condition for Correct gearing
Steering Geometry
Wheel Angles
1.Camber
Caster
King pin inclination
Toe
1. Worm and sector steering gear
2. Worm and roller steering gear
3. Worm and ball bearing nut steering gear
4. Cam and peg steering gear
5. Cam and double lever steering gear
6. Cam and roller steering gear
7. Recirculating Ball steering gear
8. Rack and pinion steering gear
Steering Linkages
Electronic Power Steering
Integral Power Steering
Linkage Power Steering
Front Axle
 Brakes
Mechanical Drum Brakes
Hydraulic Brake
 Master Cylinder
Typical Master cylinder Tandem Master cylinder
Air Brakes
Vacuum Brake
 Suspension
Leaf Spring Suspension
Independent Front Suspension
 Independent Front Suspension
Double wishbone suspension Macpherson strut assembly
 Independent Front Suspension
Trailing link suspension Sliding pillar independent suspension
Rigid axle rear suspension
 Independent rear suspension

Swing half axle Trailing arm

Chassis and Frames
Electrical systems
 Ignition Coils
Can type or Core type

• Primary winding 200-300 turns of 20 SWG

• Secondary winding 1500- 20000 turns of 40 SWG
 Battery
• Components:
• (i) Container (ii) Plates (iii) Separator (iv) Cell Cover (v) Electrolyte
PbO2 + 2H2SO4 + Pb = PbSO4 + 2H2O + PbSO4 + Q
(+) Electrolyte (-) (+) (-) Energy
Battery Testing
Specific gravity test
Hydrometer is used to measure specific gravity of cell (1280 -1110 at 27 °C )
Open Volt test
Cell voltage of fully charged battery is 2.1 volt. (Drop of 0.01 volt is equal to 0.01 drop in
specific gravity
High discharge test
High current (150 -200 Amp) is drawn for 5 seconds, The cell voltage should not fall below
1.5 volt. Difference of cell voltages should not be more than 0.2 volt.
Cadmium test
When terminal is connected to positive terminal the voltage shown in voltmeter should not
be below 2.5 volt. When connected to negative terminal the voltage should be more than 0.2
volt.
 Vehicular Pollution Problems in India

• High vehicle density in Indian urban centers

• Older vehicles predominant in vehicle vintage
• Inadequate inspection & maintenance facilities
• Predominance of two stroke two-wheelers
• Improper traffic management system & road conditions
• High level of pollution at traffic intersections
• Absence of effective mass rapid transport system &
intra-city railway network
• High population exodus to urban centers
 Emissions from Internal combustion Engines

• Evaporative losses from

fuel tank and carburetor
(15-25% of HC)
• Crankcase blow by (20-
35% of HC)
• Exhaust (50-60% of HC,
almost all of CO, NOx,
smoke, SPM, SO2 and
Lead)
 Action Taken
• Evaporative losses: Use of Evaporative losses control device
(ELCD). It aims at capturing the vapors and
recirculating them at the appropriate time.
• Blow by Losses: Use of Positive crankcase ventilation (PCV)
• Exhaust Emissions:Engine Design Modification
Use of Leaner A/F mixture
Adoption of MPFi system
Retarding ignition timing
Modification in combustion chamber to reduce
quenching areas
Lowering the compression ratio
Reduced Valve overlap
Exhaust Gas Treatment
Use of after burners
Use of manifold reactors
Use of Catalytic converters
Fuel Modification
 Exhaust Pollutants – Causes, Effects and Action taken

Carbon Monoxide (CO)

Causes:
Carbon Monoxide (CO) occurs only in engine exhaust. It is a
result of incomplete combustion. Instead of forming carbon
dioxide by oxidation results in carbon monoxide.
Effects:
 Fatal in large doses
 Aggravates heart disorders
 Affects central nervous system
 Impairs oxygen carrying capacity of blood
Treatment:
 Use of after burners
 Use of manifold reactors
 Use of Catalytic converters
 Unburned Hydrocarbons (HC)
Causes:
Unburned hydrocarbon emissions are the direct result
of incomplete combustion .
Effects:
 Drowsiness, eye irritation and coughing
 Known carcinogen, also cause other life threatening
diseases
 Reacts with oxides of nitrogen and produces the
highly toxic ozone
Treatment:
 Use of after burners
 Use of manifold reactors
 Use of Catalytic converters
 Oxides of Nitrogen (NOx)
Causes:
NOx formation in an engine is primarily a function
of reaction temperature, available oxygen and duration of
availability.
Effects:
 Irritation of respiratory tract
 Increase in acute respiratory infections and bronchitis
 Morbidity in children
Treatment:
 Exhaust gas recirculation (EGR)
 Water injection in the combustion chamber
 Use of Catalytic converters
 Smoke
Causes:
Smoke is produced during acceleration, overloading or even
during full load operation of the engine. Because of high temperature
there is thermal cracking of molecules rather than normal oxidation. This
thermal cracking is in the form of soot/carbon. This soot is a graphite
structure, jet black in colour and is called smoke.
Effects:
 Irritation of respiratory tract
 Increase in acute respiratory infections and bronchitis
 Causes stunted babies
Treatment:
 Running at low loads (Derating)
 Proper maintenance of injector and Combustion chamber geometry
 Use of smoke suppression additives (Some barium compounds reduce
reaction temperature thus reduce thermal cracking)
 Use of Catalytic converters
 Fumigation
 Sulphur dioxides (SO2)
Causes:
Sulphur content in the fuel.
Effects:
 High doses can cause laryngo-tracheal and pulmonary oedema
 Causes Cardiovascular deaths
 Causes suffocation, irritation of throat and eyes
 Combined with smoke, aggravates respiratory problems like
bronchitis and asthma
 Combines with atmospheric water vapor to produce acid rain
 Leads to acidification of lakes and soils. Corrodes buildings
Treatment:
 Use of low sulphur fuel
 Lead (Pb)
Causes:
Present in the fuel.
Effects:
 Adversely affects blood and human nervous system and
causes hypertension
 Causes anemia, brain dysfunction and kidney damage
 A major health threat to children under six, it severely
 Retards mental growth and some times even death
Treatment:
 Use of Lead free fuel
 Indian and EURO Norms for Petrol Driven Passenger Cars

1991-92 1996 1998 1996 2000 2005

INDIA EURO INDIA INDIA EURO INDIA EURO EURO

I II III IV

CO 14.3 - 2.72 8.68 - 4.34 - 2.2 2.72 2.03 1.0

g/km 27.1 12.4 6.20
HC 2.0 -2.9 -- -- -- -- -- 0.20 0.1
g/km
NOx -- -- -- -- -- -- 0.15 0.08
g/km
HC + -- 0.97 3.4 - 1.5 - 0.57 0.97 -- --
NOx 4.36 2.18
g/km
Thank you
 Thanks

Acknowledgments
1. A text book of Automobile Engineering by
R.K. Rajput, Laxmi Publications, New Delhi
2. Automobile Engineering by R.B. Gupta, Satya
Prakashan, New Delhi