engine accessory system notes

1. Roger C. Montepio
Flywheel – absorb the violent thrust of power stroke
and then release the energy back to the crankshaft
- provide additional power to the engine to run
smoothly and helps overcome increased load
- Contributes uniform rotation of crankshaft
during intervals when it is not receiving energy
from piston
Lubrication system – provides a constant supply
of oil to the engine
- to lubricate and cool the moving parts
Engine Accessory System
REVIEW

2. Roger C. Montepio
Engine Accessory System
REVIEW
Fuel system – supplies the engine
with the properly proportioned
fuel and air mixture
-regulates the amount of the
mixture supplied to the engine to
control engine speed and power
output

3. Roger C. Montepio
Ignition system – ignites the fuel and air
mixture in the combustion chamber at the
precise moment needed
Cooling system – removes the excess heat
from the engine, generated by combustion
Engine Accessory System
REVIEW

4. Roger C. Montepio
Valve train/system
-Operates the valves (intake and
exhaust valves)
-Operates the valves in timed
sequence
-Valve construction (L-head and
in-head type)
L-head
constructionMechanisms consist of 1) Small gears on
crankshaft, 2)half time or cam gear, 3)cam,
4)tappet or short push rod

5. Roger C. Montepio
Parts of valve system
-Raised piece on the
camshaft called the
camlobe
-function of valve
spring closes the
valve after it has
been opened and to
hold it tightly closed
against its seat

6. Roger C. Montepio
Timing gears or chain

7. Roger C. Montepio
Valve in-head
construction
-Valves are of the poppet or
mushroom type
-consist of flat head and stem
-flat head has beveled edge
called the face
-beveled edge found in the
cylinder block or head called the
valve seat
-seat angle usually 45˚, 30˚ angle
is frequently used for intake
valve

8. Roger C. Montepio
Parts of engine valves
 head
 Lip/edge
 Face
 Shoulder
 Stem
 Lock groove

9. Roger C. Montepio
When can we say that the Valve is
correctly timed
if a valve starts to open and then closes at specified
time wrt the crankshaft and piston position
Valves action is gradual, that is , the valve is pushed
slowly and it open and close.
This sequence are determined by:
1. Timing of crankshaft and camshaft gears
2. Shape of the cam
3. Tappet or rocker arm clearance

10. Roger C. Montepio
Valve timing
Two revolution crankshaft = 4-stroke
completes the cycle (Intake,
Compression, Power, Exhaust)
Timing gears are arranged to allow
2-revolution crankshaft for each
revolution of the camshaft
Engine operate efficiently only if
it is correctly timed

11. Roger C. Montepio
Range of operation and cam shape
Range of operation – number of degrees through w/c
the crank rotates from the point where the valve starts
to open to the point where it is just completely closed
- 235 to 240 degrees
- determined by:
1. camshaft shape (if angle of action and
cam lobe height/lift are greater and longer
– wide range of operation)
2. valve clearance (too much – decrease the
range of operation)

12. Roger C. Montepio
Valve clearance
- space allowed between the end of the valve stem and
rocker arm (In-head type)
- space allowed between the valve stem and the
tappet (L-head type)
Too much valve clearance would produce a very pronounce noise
Type Intake Exhaust
Auto engine 0.006-0.012 inch 0.010-0.020 inch
Tractor engine 0.010-0.020 inch 0.012-0.030 inch

13. Roger C. Montepio
What are the effects of
incorrect valve timing?
- longer time of valve opening, would results
to a generation of more power and operate
efficiently
- short time (vice versa)
- high-speed engine closes as much as 45˚ to
60˚ after BDC
 Incorrect intake valve timing

14. Roger C. Montepio
What are the effects of
incorrect valve timing?
- earlier time of valve opening, results to a
more satisfactory, it gives:
1. more power,
2. run cooler,
3. uses less fuel, and
4. better cleaning of cylinder
- too late time - overheating
- most engine open 45˚ before BDC
 Incorrect exhaust valve timing

15. Roger C. Montepio
Fuel Supply and
Carburetion System
In gasoline engine, fuel is admitted into the
cylinder of the engine by the carburetion
process.
Carburetion process takes place in the carburetor

16. Roger C. Montepio
Carburetors
Purpose of the carburetor is to produce a
mixture of fuel and air on which the engine
can operate
Supply definite proportion / metered to suit fuel
requirements of the engine
Air-fuel ratio:
 1:2 ratio when the engine is started
1:9 ratio during cruising/traveling speed

17. Roger C. Montepio
Carburetors
Idling speed- speed of the engine in which
butterfly valve partially closed, only a limited
amount of air is admitted and only idling jet
operates to supply minimal amount of fuel
Must produce economical fuel consumption and
smooth engine operation over a wide range of
speeds
Requires complicated device rather than a
simple mixing valve; price is very important!

18. Roger C. Montepio
Venturi (nozzle)
• Use force of atmospheric
pressure and artificially
created low pressure area to
mix fuel and air
• Use a venturi nozzle to lower
air pressure in carburetor to
create suction to “pull” fuel
into air
Venturi (nozzle)
P+1/2 V2 = ConstantBernoulli Principle:

19. Roger C. Montepio
Venturi-type Carburetor
Ref. Obert
Constant level is
maintained in bowl -as
float moves down,
valve stem moves down,
allowing more fuel into
bowl, float moves up
and closes valve
Valve StemFuel Inlet
Float
Metering Orifice
Throttle Plate
Air/Fuel Mixture To Engine
Choke Plate
Fuel
Nozzle
Inlet Air
Bowl
Atomized Fuel
Venturi

20. Roger C. Montepio
Flo-Jet Carburetor
• Fuel tank is above
carburetor
• Fuel is fed directly to
carburetor by gravity
• Vent connected to
float (fuel chamber or
cup) …..Why the
vent?

21. Roger C. Montepio
Flo-Jet Carburetor
Fuel from tank
Air flow
Air-fuel
mixture

22. Roger C. Montepio
Pulsa-Jet Carburetor
• Incorporates a diaphragm type fuel pump and
a constant level fuel chamber

23. Roger C. Montepio
Pulsa-Jet Carburetor Operation
 Intake stroke of piston creates a
vacuum in carburetor elbow
 Pulls cap A and pump
diaphragm B inward and
compresses spring
 Vacuum thus created on “cover
side” of diaphragm pulls fuel up
suction pipe S into intake valve
D

24. Roger C. Montepio
Pulsa-Jet Carburetor Operation
 When engine intake stroke is
complete, spring C pushes
plunger A outward
 Gasoline in pocket above
diaphragm to close inlet valve D
and open discharge valve E
 Fuel is then pumped into fuel
cup F

25. Roger C. Montepio
Pulsa-Jet Carburetor Operation
 Venturi in carburetor is connected
to intake pipe I which draws
gasoline from fuel cup F
 Process is repeated on the next
stroke, keeping the fuel cup full
 Since fuel cup level is constant,
engine gets constant air-fuel ratio

26. Roger C. Montepio
Fuel Injection in CI Engines
Fuel injection is a critical process in CI engines
Injection pump use to deliver individual fuel injections via high
strength lines to injectors.
Classed of injection of fuels into
the engine cylinder
1. directly
2. indirectly
Basic objectives - to atomize and inject the fuel
- provide right quantity at right time

27. Roger C. Montepio
Modern Fuel Injection System
Electronic injection system
Electronic control unit controls the timing
and duration of injections by opening
solenoid valves
Injection timing and duration can be
customized to meet various objectives,
including maximizing power or fuel economy
or minimizing exhaust emissions

28. Roger C. Montepio
Fuel injection system
components
Gravity feed injection pump of a diesel engine
Day-tank
Stop cork/fuel valve
Fuel line
Primary and secondary Fuel filter
Cam follower
Transfer pump, Injection pump and injector unit
High pressure fuel line
Nozzle
INJECTOR UNIT- fuel
injector and meterer at the
same time
NOZZLE - atomizer

29. Roger C. Montepio
Injection pump and unit injector
Injection pump
Considered as the heart of diesel engine
Delivers the needed amount of fuel at proper time and form
Operates at high hydraulic pressure at ranges from 70 to 700
kg/cm2
Basic parts:
1. Plunger
2. Barrel
 It operates very much alike that of the syringe

30. Roger C. Montepio
Methods of controlling the amount
of fuel
Depends upon the length of plunger stroke
Depends on the manner of bypassing the excess fuel
from the barrel
The variation of the plunger stroke and by-
passing of fuel from the barrel is acted on by the
GOVERNOR

31. Roger C. Montepio
Governing system
GOVERNOR
 a device that controls the speed of the engine
Varies the air or fuel supply requirement of the engine
Types of governor
Hydraulic /pneumatic controlled
Mechanically controlled

32. Roger C. Montepio
GOVERNOR
Three physical principles involved in which the
governors will work
Creating vacuum – pneumatic controlled governor
Creating hydraulic pressure – hydraulic controlled
governor
Creating centrifugal force – mechanical controlled
governor

33. Roger C. Montepio
Mechanical Governor
Works alike the principle of the sling
Consists of flyweights, sleeve, yoke, and return
spring
The mechanical governor drive gear engages with
the engine camshaft. The drive gear turns the entire
governor assembly. The flyweights move outward from the
drive shaft axis as the governor assembly turns. There is
then a chain of movements to the sleeve, yoke, control rack
and finally with the plunger w/c is a part of the injection
pump that controls the amount of fuel for the engine.

34. Roger C. Montepio
Lubrication system
The lubrication system
 supplies a constant supply of oil to all moving parts
 constant supply of fresh oil is to minimize wear, flush
bearing surfaces clean
 remove the localized heat that develops between
moving parts as a result of friction
 oil that is supplied to the cylinder walls helps the
piston rings make a good seal to reduce blowby

35. Roger C. Montepio
Ignition system

36. Roger C. Montepio
Purpose of Lubrication
a. Oil as a Lubricant.
primary function of engine oil is to reduce
friction between moving parts (lubricate)
Without lubrication??????????
Lubrication system

37. Roger C. Montepio
Without lubrication
addition to wasting engine power,
creates destructive heat and rapid wear of parts or
(melts)
greater energy required to overcome that friction
Purpose of Lubrication
b. Oil as a Coolant.
 also serves to remove heat from the friction points
Lubrication system

38. Roger C. Montepio
1) How Oil Lubricates
(a) oil is fed to the surface it forms a film, preventing the moving
part from actually touching the surface
(b) As a part rotates, the film of oil acts as a series of rollers
It is important that sufficient clearance be allowed between the
part and the bearing; otherwise the film might be too thin.
It also is important that the clearance not be too large between
rotating parts and their bearings – cause bearing failure
Lubrication system

39. Roger C. Montepio
 How Oil Lubricates

40. Roger C. Montepio
(2) Oil Contamination
Lubrication system
Oil does not wear out, but it does become
contaminated
How oil becomes contaminated??????
foreign matter enters through the air intake,
will pass by the piston rings
enter the crankcase
CASE 1

41. Roger C. Montepio
combined with foreign matter entering through
the crankcase breather pipe
 mixes with the oil,
forced into the bearings,
Water will emulsify with the oil to form a thick
sludge
crankcase
(2) Oil Contamination
Lubrication system
CASE 2 products of combustion is WATER,
condense in the
crankcase
will seep by the
piston rings as
steam

42. Roger C. Montepio
How oil becomes contaminated??????

43. Roger C. Montepio
Lubrication system
(2) Oil Contamination
What happen when the oil, mixed with the
contaminants?
 loses its lubricating qualities
Becomes acidic
Engine oil must be changed periodically to prevent
contaminated oil from allowing excessive wear and
causing etching of bearings

44. Roger C. Montepio
How to control engine
contamination
a) Control engine temperature;
b) The use of oil filters
c) An adequate crankcase ventilation system
d) The use of air intake filters

45. Roger C. Montepio
Oil Dilution
 Engine oil thins out when mixed with gasoline,
causing a dramatic drop in its lubricating qualities
Some of the causes of oil dilution are the
following:
(a)Excessive use of a hand choke
(b)defective ignition system
(c)a malfunctioning thermostat, or an engine
that is operated for short durations only,
Lubrication system

46. Roger C. Montepio
American Petroleum Institute (API) Rating System.
Lubrication system
The API system for rating oil classifies oil according to its
performance characteristics (quality). The higher rated oils
contain additives that provide maximum protection against rust,
corrosion, wear, oil oxidation, and thickening at high
temperatures.
six oil classifications for gasoline engines (SA, SB, SC, SD, SE,
and SF)
four classifications for diesel engines (CA, CB, CC, and CD).

47. Roger C. Montepio
API Designations
Lubrication system
(a)SA (Utility Gasoline Engines).
 Adequate for utility engines subjected to light loads, moderate
speeds, and clean conditions.
 SA-rated oils generally contain no additives.
(b) SB (Minimum Duty Gas Automotive)
Adequate for automotive use under favorable conditions (light
loads, low speeds, and moderate temperatures) with relatively
short oil change intervals.
 SB-rated oils generally offer minimal protection to the engine
against bearing friction, corrosion, and oil oxidation.

48. Roger C. Montepio
API Designations
Lubrication system
(c) SC. Meets all automotive manufacturers'
requirements for vehicles manufactured from 1964 to
1967.
(d) SD. Meets all automotive manufacturers'
requirements for vehicles manufactured from 1968 to
1970. SD oil offers additional protection over SC oils,
necessary with the introduction of emission controls.

49. Roger C. Montepio
(e) SE. Meets all automotive manufacturers‘
requirements for vehicles manufactured from 1971 to
1979.
API Designations
Lubrication system
(f) SF. Meets all automotive manufacturers'
requirements for vehicles manufactured after 1980. SF
oil is designed to meet the demands of the small, high-
revving engines made necessary by the trend toward
smaller vehicles. An SF oil can be used in all automotive
vehicles.

50. Roger C. Montepio
Viscosity and Viscosity Measurement.
Lubrication system
viscosity of an oil refers to its resistance to flow
When oil is hot, it will flow more rapidly than when
it is cold
In cold weather, oil should be thin (low viscosity)
to permit easy flow
 In hot weather, oil should be heavy (high
viscosity) to permit it to retain its film strength

51. Roger C. Montepio
Viscosity Measurement
Lubrication system
Oils are graded according to their viscosity by a series of
Society of Automotive Engineers (SAE) numbers. The viscosity of
the oil will increase progressively with the SAE number.
SAE 5 oil would be very light (low viscosity)
SAE 90 oil would be very heavy (high viscosity)
 oil used in gasoline engines generally ranges from SAE 5
(arctic use/colder region) to SAE 60 (desert use).

52. Roger C. Montepio
Lubrication system
The viscosity number of the oil is determined by
heating the oil to a predetermined temperature and
allowing it to flow through a precisely sized orifice while
measuring the rate of flow.
The faster an oil flows, the lower the viscosity
The testing device is called a viscosimeter.
Any oil that meets SAE low temperature requirements
will be followed by the letter W. An example would be
SAE 10W.
Viscosity Measurement

53. Roger C. Montepio
Multiweight Oils
are manufactured to be used in most climates
because they meet the requirements of a light oil in
cold temperatures and a heavy oil in hot
temperatures
 viscosity rating will contain two numbers
An example of this would be 10W-30
An oil with a viscosity rating of 10W-30 would be as thin
as a 10W-weight oil at 0° F (-17.7° C) and as thick as a 30-
weight oil at 210° F (99° C).
Lubrication system

54. Roger C. Montepio
Detergent Oils
Oil contain additives that help keep the engine clean
by preventing the formation of sludge and gum
All SE and SF oils are detergent oils
Lubrication system

55. Roger C. Montepio
Oil Pumps
Lubrication system
mounted either inside or outside of the crankcase,
depending on the design of the engine
 They are usually mounted so that they can be driven
by a worm or spiral gear directly from the camshaft
Oil pumps generally are of:
 the gear
the rotor type.

56. Roger C. Montepio
Lubrication system
Oil Pumps
RotorType Oil Pump
The rotor oil pump
makes use of an inner
rotor with lobes that
match similarly shaped
depressions in the
outer rotor

57. Roger C. Montepio
 GearType Oil Pump
Gear-type oil pumps have a
primary gear that is driven by an
external member, and which drives
a companion gear
Oil Pumps
Lubrication system

58. Roger C. Montepio
Oil Strainer and Pickup
Lubrication system
Strainer/ screen is usually a fine mesh bronze screen, located in
the oil sump on the end of the oil pickup tube
The oil pickup tube is then threaded directly into the pump
inlet or may attach to the pump by a bolted flange
A fixed-type strainer, like the one described, is located so
that a constant supply of oil will be assured
 The pickup is designed to float on top of the oil, thus
preventing sediment from being drawn into the oiling system.

59. Roger C. Montepio
Lubrication system
Oil Strainer and Pickup figure

60. Roger C. Montepio
Oil Filters.
Lubrication system
removes most of the impurities that have been picked
up by the oil as it is circulated through the engine
 The filter is mounted outside the engine and is
designed to be readily replaceable
Two basic filter element configurations:
the cartridge-type
the sealed cam-type

61. Roger C. Montepio
Oil Filters.
Lubrication system

62. Roger C. Montepio
Lubrication system
Oil Filters.
(a) cartridge-type filter element fits into a permanent metal
container
 The element is changed easily by removing the cover from
the container when this type
of filter is used
(b) sealed cam-type filter element is completely self-contained,
consisting of an integral metal container and filter element.
This type of filter is screwed onto its base and is removed by
spinning it off

63. Roger C. Montepio
Filter Medium Materials
Lubrication system
most popular automotive filter mediums
1. Cotton waste
2. resin-treated paper
They are held in place by sandwiching them between
two perforated metal sheets
3. layers of metal that are thinly spaced apart for
heavy-duty applications

64. Roger C. Montepio
Filter Medium Materials
Lubrication system

65. Roger C. Montepio
Filter System Configurations.
Lubrication system
Two-filter system configurations
the full-flow system
bypass system. Operation
(a)full-flow system
 the most popular in current automotive design
 All oil in a full-flow system is circulated through the filter before
it reaches the engine
 It incorporate a bypass valve in the oil filter to allow the oil to
pass through the element in the event it becomes clogged. This will
prevent the oil supply from being cut off to the engine.

66. Roger C. Montepio
(a)full-flow system
Filter System Configurations.

67. Roger C. Montepio
(b) bypass system
diverts only a small quantity of the oil each time it is
circulated and returns it directly to the oil pan after it is
filtered.
Filter System Configurations.
Lubrication system

68. Roger C. Montepio
Lubrication system

69. Roger C. Montepio
Oil Coolers.
Lubrication system
be able to dissipate more heat from their oil than
normal airflow can accomplish
Oil Temperature Regulator
used to prevent the oil temperature from rising
too high in hot weather, and to assist in raising the
temperature during cold starts in winter weather
The regulator makes use of the liquid in the
cooling system
provides a more positive means of controlling oil
temperature than does cooling by radiation of heat
from the oil pan wells.

70. Roger C. Montepio
Lubrication system
Oil Temperature Regulator
made up of a core and a housing
The core through which the oil
circulates is of cellular or bellows
construction, built to expose as much oil
as possible to the coolant that circulates
through the housing
attached to the engine so that the oil
will flow through the regulator after
passing through the pump

71. Roger C. Montepio
Oil Cooler
consist of a radiator through which air is circulated by
movement of the vehicle, or by a cooling fan
 Oil from the engine is circulated through this radiator
and back to the sump or supply tank
Lubrication system

72. Roger C. Montepio
Lubrication system

73. Roger C. Montepio
Oil Level Indicator
The oil level indicator is usually
of a bayonet type
consists of a small rod, known
as a dipstick, that extends
through a tube into the crankcase
 It is marked to show when the
crankcase is full or, if it is low,
how much oil is needed
Lubrication system

74. Roger C. Montepio
Lubrication system
Pressure Regulator

75. Roger C. Montepio
Pressure Regulator
The oil pump will produce pressures in great
excess to those necessary
This excess pressure, if uncontrolled, would cause
excess oil consumption due to flooded cylinder walls
and leakage through oil seals
spring-loaded regulator valve is installed in the
lubrication system to control pump pressure
Lubrication system

76. Roger C. Montepio
Lubrication system
Types of Lubrication Systems
a. Splash System
 no longer used in automotive
engines,
 it is used in small equipment
engines
 Operation
 dippers on the connecting
rods enter oil in the
crankcase with each
crankshaft revolution, thus
splashing the oil.

77. Roger C. Montepio
Lubrication system
Types of Lubrication Systems
b.Combination Splash and
ForceFeed System
oil is delivered to some parts by
means of splash and to other parts
through oil passages, under pressure
from a pump in the crankcase
The main and the camshaft bearings
are usually the items that are force
fed while the connecting rods are
fitted with dippers that supply oil to
the rest of the engine by splash

78. Roger C. Montepio
Lubrication system
Types of Lubrication Systems
c. ForceFeed
Lubrication System
 more complete
pressurization of
lubrication
 oil is forced by the oil
pump from the
crankcase to the main
bearings and the
camshaft bearing

79. Roger C. Montepio
Lubrication system
Types of Lubrication Systems
all of the bearings are
lubricated by oil under
pressure
includes main bearings,
rod bearings, camshaft
bearings, and the complete
valve
provides lubrication
under pressure to the
pistons
d.Full ForceFeed Lubrication System

80. Roger C. Montepio
Cooling system
Cooling medium
(1)Liquid
 is the most popular coolant in automotive use
 cooling system provides the most positive cooling
 best for maintaining uneven engine temperature
(2) Air
 most practical for small vehicles and equipment because no
radiator or hoses are required
do not run at even temperatures and require extensive use of
aluminum to dissipate heat.

81. Roger C. Montepio
Cooling system
other sources of heat dissipation for the
engine in addition to the cooling system
(1) The exhaust system dissipates as such, if not more, heat than the
cooling system, although that is not its purpose
(2) The engine oil, removes heat from the engine and dissipates it to
the air from the sump
(3) The fuel provides some engine cooling through vaporization
(4) A measurable amount of heat is dissipated to the air through
radiation from the engine.

82. Roger C. Montepio
Types of cooling system
Cooling system
Air Cooling system
 Use air as a cooling medium
 Cooling effect is produced by means of fins or
projections on the walls of the cylinder
Common examples of air-cooled engine
 airplane
Motorcycle
Lawn mower, garden tractor
Small and medium diesel tractor

83. Roger C. Montepio
Cooling system
Types of cooling system
Advantages
 Lighter in weight
Simpler in construction
More convenient and less trouble
No danger of freezing in cold weather
Disadvantage
 Difficult to maintain proper cooling under all
conditions
 impossible to fully control cylinder temperature
Usually run a little hotter than water cooled engine

84. Roger C. Montepio
Cooling system
Types of cooling system
Liquid Cooling system
 Use liquid as a cooling medium
 use in all types of engine
Advantages
Plentiful and available anywhere
absorbs heat well
Circulates freely at all temperature between freezing
to boiling
No danger

85. Roger C. Montepio
Cooling system
Types of cooling system
Liquid Cooling Systems