1. The document discusses various engine auxiliary systems including carburetors, ignition systems, fuel injection systems, and their components and workings. 2. It describes the types and parts of carburetors like the float chamber and venturi, as well as defects like improper air-fuel mixtures at different speeds. 3. Electronic fuel injection systems and their sensors that allow for precise fuel delivery controlled by an electronic control unit are also covered.

1. ENGINE AUXILIARY SYSTEMS
UNIT-II

2. Syllabus

3. Carburetor
• Carburetor is a device used for atomizing and
vaporizing the fuel and mixing it with the air
at varying proportions to suit for changing the
operating conditions of Engine.
• Mixture ratios- rich mixture 12:1 or 9:1
• Lean Mixture 16:1.

4. Air fuel Ratio

6. Function of the Carburetor
• It prepares a mixture of petrol and air in
correct proportions.
• It maintains a small reserve of petrol in the
float chamber at constant head.
• It atomizes and vaporizes heads.
• It Supplies a fine spray of petrol.

7. Types of Carburetor
• According to the direction-
1. Uplift Carburetor.
2. Down draft Carburetor.
• According to Number of units-
1. Single Carburetor.
2. Double Carburetor.

8. Simple Carburetor
• The main component of a simple carburetor
are
1. Float Chamber.
2. Float.
3. Nozzle.
4. Venturi.
5. Throttle Valve.
6. Inlet Valve.

9. Simple Carburetor

10. Float Chamber
• Float Chamber is ventilated to atmosphere, it
is used to maintain the atmosphere pressure
inside the chamber.
• The float chamber is in metallic cylindrical
shape rises and closes the inlet valve as the
fuel level in the float chamber.

11. Mixing chamber
• The mixing chamber consist of Venturi, nozzle
and throttle valve.
• The venturi tube is fitted with inlet manifold,
there are two butterfly valves, where one is to
allow air into the mixing chamber known as
choke valve.
• Other on is to allow the air fuel mixture to the
engine known as throttle valve.

12. Defects in Carburetors
• It will not work properly either at high speed
or low speed when there is no enough vaccum
created in the nozzle tip.
• With different pressure heads the co-efficient
of discharge for air and fuel varies, at certain
the coefficient of discharge is constant.

13. Numbers of Defects in Carburetor
• Starting Problem- For starting the Engine it
requires Rich Mixture of A/F Mixture.
• In Order to Avoid it
1. Ticklers.
2. Choke.
3. Adjustable Area Jet.
4. Separate air Passage.

14. Ticklers

15. Choke

16. Adjustable Area

17. Separate Air Passage

18. Defects in Carburetor
• Idling Condition- In idle Condition or Slow
speed running, a rich mixture is needed by the
Engine. Although it is less than the rich
mixture 10:1 when compared to the Starting.
• It Requires the more amount of air fuel
Mixture.

19. Defects in Carburetor

20. Solex Carburetor
• Solex Carburetor is best known for its Ease
Starting, good Performance and Realiability.
• The Solex Carburetor is knowns as down
draught Carburetor.
• This has the provision for the supply of richer
mixture during crusing the vehicle.
• It consist of various fuels circuits as Starting,
Idling and Normal running, accelerations.

21. SOLEX CARBURETOR
TYPES OF CIRCUITS
1. Float circuit
2. Starting circuit
3. Idle and slow running circuit
4. Normal running circuit
5. Acceleration circuit

23. Parts of Solex Carburetor
• Float Circuit- The float Circuit consist of Float,
Float Chamber and Needle Valve arrangement
float is pivoted to the Float Chamber in a
lever.
• When the fuel reaches the predetermined
height, the needle closes the passage as the
float moves up.

24. Starting circuit

25. Idling Circuit

26. Normal Speeding

27. Accelerating Circuits

28. Carter Carburetor
• It is normally used in Jeeps. It is multiple jet,
plain tube type of Carburetor with only one
adjustment which is for idling or low speed
operation.
• Jet on the nozzles comes into operations in
direct proportion to the throttle postion.

29. Carter Carburetor

30. Carter Carburetor
• It consist of following circuits-
• Float Circuit.
• Starting Circuit.
• Idle and Low speed circuit.
• Part throttle circuit.
• Full throttle.
• Acceleration pump circuit.

31. Float Circuit
• The float chamber contains float. The inlet
needle valve operated by a float control the
simple of fuel from the fuel into float
chamber.

32. Starting Circuit
• The choke valve of usual type is used for
starting purpose. During starting the choke
valve is closed postion, the whole of the
engine suction is applied to the main nozzle
which delivers the fuel.
• As the air flow is quite small, the mixture
supplied is very rich.

33. Idling and low speed running
• For idling, rich mixture of small quantity is
required. During idling , the throttle valve is
almost closed. The whole of engine suction is
applied to the idle port.

34. Part throttle circuit
• Throttle valve is opened further for increasing
the speed. The fuel is delivered by the main
nozzle only.

35. Full throttle circuit
• Now the throttle valve is full opened. The
maximum amount of air is passed through the
venture. The higher rate fuel flow is required.
• It is achieved by means of the metering rod.
The metering rod has two or more steps of
diatmeter.

36. Acceleration circuit
• The acceleration pump is used to overcome
flat spot during acceleration. When the
throttle is suddenly opened by pressing
accelerator pedal as pump will be actuated
and a small quanitity of petrol is spruted into
choke by the acceleration jet.

37. ELECTRONIC FUEL INJECTION SYSTEM
FOR SI ENGINE

38. Electronic Controlled Gasoline
Injection
• Limitations of Carburater-
1. The carburetor has more wearing parts.After
wear, it is operates less efficiently.
2. There is loss of volumetric efficiency due to
restricted flow of mixture in various parts
such as choke tubes, jets, throttle valve, inlet
valve.

39. GASOLINE INJECTION SYSTEM
1. Multi-point injection system
2. Monopoint injection system
Function- The injector valve sprays fuels into the
air just before it passes through the throttle
valve and enters the intake manifold. The
method simplifies the construction of the
engine block.

42. Electronically Controlled Gasoline
Injection System
• Fuel delivery system
• Air induction system
• Sensors and air flow control system
• Electronic control unit

43. Sensors and air flow control system
1. Air flow sensor
2. Intake air temperature sensor
3. Exhaust gas oxygen (EGO) sensor
4. Manifold absolute pressure (MAP) sensor
5. Speed/crankshaft sensor
6. Engine temperature sensor
7. Crankshaft position sensor
8. Knock sensor

45. Electronic Control Unit
• It is the heart of the Fuel injection system. It
contains various information from the sensors
and controls the amount of fuel injected by
operating injectors for just the right amount of
time.

46. Advantages
• It reduces the specific fuel consumption due
to better distribution of mixture to each
cylinder.
• Better starting and acceleration are ensured
than carburetor system.

47. Disadvantages
• Initial cost is very high because of precise and
complicated comparsion of the electronic
component.
• More noise is generated.
• Weight and space requirement are more than
a conventional carburetor.

48. ELECTRONIC DIESEL INJECTION
SYSTEM
1. Unit injector system
2. Rotary Distributor system
3. Common rail direct injection system

49. Electronic Diesel Injection system
• Components of electronic diesel injection
system.
• Electronic sensor.
• Actuators or solenoids.
• ECU Electronic control.

50. Unitary Injector system
• This system is called as individual pump
system, the unit injector system (UIS)
Combines the injection nozzle and high
pressure pump in a single assembly.
• The basic operation can be described as a
sequence of four separate phases such as
filling phase, spill phase, injection phase and
pressure regulator reduction phase.

51. UNIT INJECTOR SYSTEM

52. Rotary Distribution system
• A pump which pressurizes the fuel also meters
the fuel and times the injection.
• The Fuel pump supplies the right amount of
fuel to the injector it to a rotary distributor at
the correct time for each cylinder.
• The fuel is supplied to the cylinder to the
correct firing order operated valves which are
opened to admit the fuels in nozzles.

54. Common Rail Direct Injection system
(CRDI)
• Diesel Engine have the specific advantages of
good fuel efficiency and low CO2 Emission,
therefore various new technologies have been
developed in order to reduce harmful
emission.
• A common rail is basically known as Fuel
distribution pipe, which is assemble in the
block.

56. Battery Coil Ignition system
• Generally 6-12 volt battery is used.
• The ignition coil consist of two windings
primary winding and secondary winding.
• The primary winding consist of thick wire with
less number of turns.
• The primary winding has 200-300 turns and
secondary has 21,000 turns with sufficient
insulation to withstand voltage.

57. Battery coil Ignition system
• The condenser is connected with Contact
breaker so it prevents excess arcing and pitting
of a contact breaker points.
• The contact breaker is housed in the
distributor itself.

59. Magneto Ignition system
• In this system the battery is replaced with
magneto.
• The magneto ignition system consist of
rotating magnet assembly driven by an engine
and a fixed armature.
• The armature consist of primary and
secondary winding. The primary circuit consist
of a primary winding, condenser and contact
breaker.

61. ELECTRONIC IGNITION SYSTEM
• There are some drawbacks in the magneto
ignition system. Firstly contact breaker is only
a mechanical device which cannot operate
precisely at high speed and the it gets burned.
• The conventional contact breaker is given the
satisfactory performance only about 400
sparks per second.

62. ELECTRONIC IGNITION SYSTEM
• The disadvantages of convection contact
breaker assisted ignition system can be
completely eliminated by used of electronic
controlled ignition system using contactless
triggers to give timing system.

63. ELECTRONIC IGNITION SYSTEM

64. Transistorised ignition system
• A transistorized interrupt a relatively high
current carrying circuit, i.e., it controls high
current in the collector circuit with less
current in the base circuit.
• A transistor is used to assist the work of
contact breaker. Hence this system is known
as transistor assisted ignition system or
transistorized ignition system.

66. Construction
• It consist of battery, ignition switch, Transistor,
Emitter, ballast resistor, contact breaker,
ignition coil, distributor and spark plug.
• The emitter of the transistor is connected to
the ignition coil through a ballast resistor.

68. When the contact breaker point are
closed
• A small current flows in the base circuit of the
transistor.
• A large current flows in the emitter or
collector circuit of the transistor and the
primary winding of the ignition coil due to the
normal transistor transistor action.
• A magnetic field is set up in the primary
winding of the coil.

69. When the construction breaker points
are open
• The current flow in the base circuit is stopped.
• The primary current and the magnetic field in
the coil collapse suddenly due to immediate
reverting of the transistor to the non-
conductive state.
• It produces a high voltage in the secondary
circuit.

70. When the construction breaker points
are open
• This high voltage is directed to the respective
spark plugs through the rotor of the
distributor.
• This high voltage produces a spark when it is
tried to jump the spark plug gap. It ignites air-
fuel mixture in the cylinder.

71. advantages
• It increases the life of contact breaker points.
• It gives higher ignition voltage.
• It gives longer duration of spark.
• It has very accurate control of timing.
• It needs less maintenance.

72. Disadvantages
• More Mechanical Points are needed similar to
a conventional system.
• It has a tendency to side tracking.

73. Capacitive Discharge Ignition system
• Capacitive discharge Ignition (CDI) is most
widely used today on automotive and marine
engines.
• A CDI module has a capacitor storage of its
own and it sends a short high voltage (about
250+ volts) pulse through the coil. The coil
now acts similar to a transformer and it
multiplies this voltages even higher.

76. Capacitive Discharge ignition system
• The huge advantages of CDI is the higher coil
output and hotter spark.
• The spark duration is much smaller amount
10-20 microseconds and accurate.
• It is better at high RPM but it can be a
problem for both starting period ad lean
mixture or high compression situation.

77. Distributed Ignition system
• An ignition system does not use a distributor
to route high voltage spark plugs called
distributorless ignition system.
• The high voltage plug wire runs directly from
the ignition coil to the spark plug.
• The spark timing is controlled by an ignition
control unit ICU and Engine Control Unit.

78. Distributorless Ignition System
• This system uses either a magnetic crankshaft
sensor, Camshaft position sensor or both to
determine crankshaft position and engine
speed.

81. Distribution Ignition System
• Advantages
• No timing adjustments are required.
• No distributor cap and rotor are required.
• There are no moving parts to wear out.
• Less maintenance is required.

82. SUPERCHARGING
• Supercharging is the process of supplying the
air fuel mixture to the engine just above the
atmosphere pressure. A supercharger
increases the pressure of the air fuel mixture
from the carburettor before it enters the
engine.

83. Super charger

84. Types of super chargering
• Positive Displacement type-
Positive displacement blowers and compressor
deliver at constant level of pressure increase at
all engine speed in RPM.
• Dynamic compressor type-
Dynamic compressor do not deliver pressure at
low speed and above threshold speed, the
pressure increases with the engine speed.

85. Types of super charging
a)Centrifugal type supercharging-
centrifugal supercharging compresses the
air inside the case of the supercharger using at
impeller. Then, it discharge the air out of the
scroll to the motor.
This design is similar to turbocharging except for
centrifugal supercharger which do not use the
exhaust to build pressure.

86. Centrifugal pump

87. Root type supercharging

88. Turbo charger
• A centrifugal or axial flow or displacement
type pump supercharger are driven by the
crankshaft in IC Engine.
• Some super chargers are driven by a gas
turbines which are driven by using the exhaust
gases.

89. Purpose of turbocharger
• To reduce the weight per horse power of the
engine as required in aero engines.
• To reduce the space occupied by the engine as
required in marine engines.
• To have better turbulence and it ensures more
complete combustion giving greater power
and low specific fuel consumption.

90. Principle of working of a turbocharger

91. TURBO CHARGERS

92. Methods of turbocharger
• Turbocharging is carried out in six method
such as-
• Constant pressure turbocharging.
• Pulse turbocharging.
• Pulse converter turbocharging.
• Two-stage turbocharging.
• Miller turbocharging.
• Hyperbar turbocharging.

93. Advantages of turbocharger
• It provides high power to weight ratio.
• High brake mean effective pressure can be
obtained.
• Thermal loading is moderate.
• Surge pre-operation is possible by using a by-
pass control.
• Good torque and acceleration can be
achieved.

94. disadvantages
• Fuel consumption increase throughout the
operation due to low compression ratio.
• System is more complex.
Limitation of turbochargers-
• Special Exhaust manifolds are required for the
turbocharging system.
• In order to inject more fuel per unit time, fuel
injection needs modification.

95. Engine emission and its control
• During the combustion , the oxygen combines
with carbon in various combination. During
combustion oxygen combines with hydrogen
and carbon to form water, carbon mono
oxides, and carbon dioxides.
• The oxides of nitrogen together with hydrogen
reacts in the presence of sunlight and they
form petrochemical smog.

96. Diesel Engine Emission
• Diesel Smoke is another pollutant in case of
diesel engine.
• The types of smoke are-
• White smoke.
1. it is mainly caused because of low operating
temperature.
2. Long delay between start of injection and
beginning of combustion
• Black smoke.

97. Diesel Engine Emission
• Blue smoke-
1. It is occur due to combustion of lubricating
oil.
2. It is the emission that indicates that the
Piston Rings have worn out.

98. S I Engine Emission
• There are three main sources of air pollution
due to petrol engine-
1. Evaporative Emission.
2. Crankcase blow-by, and
3. Exhaust Emission.

99. EXHAUST GAS RECIRCULATION SYSTEM

100. Exhaust gas recirculation
• The valve controls the passage of the exhaust
gas. The chamber is connected by a tube to
vacuum port in the throttle body.
• Therefore no exhaust gas recirculation. It
happens during idle when NO2 formation is at
minimum.

101. Engine Emission Control by Catalytic
Converter
• The term catalytic convertor convers a
stainless steel box mounted in the exhaust
system.
• The catalytic is inside the cover which is
ceramic or metallic base with an active coating
incorporating alumina, ceria and other oxides
and combinations of precious metallic such as
platinum, palladium and rhodium.

102. Engine Emission Control by Catalytic
Converter
(platinum, rhodium, palladium)

103. Catalytic convertor

104. (i) Reduction catalyst:
The reduction catalyst is the first stage of the
catalytic converter. It uses platinum and rhodium to help in
reducing NOx emissions. When an NO or NO2 molecule
contacts the catalyst, the catalyst rips the nitrogen atom out
of the molecule and holds on to it, freeing the oxygen in the
form of O2. The nitrogen atoms bond with other nitrogen
atoms which are also stuck to the catalyst, forming N2.
2NO => N2+ O2

105. (ii) .Oxidation catalyst:
The oxidation catalyst is the second stage of the
catalytic converter. It reduces the unburned hydrocarbons
and carbon monoxide by burning (oxidizing) them over a
platinum and palladium catalyst. This catalyst aids the
reaction of the CO and hydrocarbons with the remaining
oxygen in the exhaust gas.
2CO + O2 => 2CO2

106. Major Drawbacks in Catalytic
convertor
• Owing to the exothermic reaction in the
catalyst bed the exhaust system are hotter
than normal.
• Cars equipped with such convertor should not
use leaded fuel as lead destroys complete
catalytic activity.
• If the fuel contains Sulphur (as Diesel oil)
emission of SO3 is increased.

107. Failures in catalytic convertor
• Converter of catalytic melt down.
• Catalyst Fracture.
• Carbon deposit.
• Poisoning.

108. EMISSION NORMS (EURO AND BS)
• Emission norms for automobiles are the standards set by the
authority of different countries focusing on controlling the
amount of pollutants released into the environment from
automobiles.
• Each stage of emission standards specifically describes the
amount of pollutants from vehicles such as carbon monoxide
(CO), nitrogen oxides (NOx), sulphur dioxide, carbon dioxide
(CO2), hydrocarbons (HC) and particulates which can be
emitted from an automobile into the environment. These
regulatory standards differ from bottom to nation. But the
aim is common to control the environmental pollution.

109. Parameters determining emission from vehicles:
• Vehicular technology
• Fuel quality
• Inspection & maintenance of in-use vehicles
• Road and traffic management.

111. Bharat stage Norms
• BS emission standards are emission standards
instituted by the Government of India to
regulate the output of air pollutants from IC
Engines.
• The first Indian Emission regulation Limits
which was started in 1989, Supreme court of
India order to follow the Euro-I or India 2000.