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CHAPTER 26 diessel injection.PPT
- 1. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Publisher
The Goodheart-Willcox Co., Inc.
Tinley Park, Illinois
by
Russell Krick
- 3. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Basic diesel injection system
Diesel injection system accessories
- 4. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Diesel Fuel Injection
System
High-pressure mechanical system that
delivers fuel directly into the
combustion chambers
Unlike a lower-pressure gasoline
system, which meters fuel into the
intake manifold
- 5. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Diesel versus Gasoline
High compression
17:1 to 25:1
Compression ignition
No throttle valve
Compresses air
Direct injection into
combustion chamber
Engine power
controlled by the
amount of fuel injected
Lower compression
8:1 to 10:1
Spark ignition
Throttle valve
Compresses air/fuel
Fuel metered into
intake manifold
Engine power
controlled by
regulating air and fuel
flow
- 6. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Diesel Injection
System
Injection pump
plunger produces
high pressure to
open the injector
- 7. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Components
Injection pump
high-pressure mechanical pump
meters fuel to each injector nozzle at the
proper time
Injection lines
high-strength steel tubing
carry fuel to each injector nozzle
- 8. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Components
Injector nozzles
spring-loaded valves
spray fuel into each combustion chamber
Glow plugs
electric heating elements
warm air in the cylinder precombustion
chambers
aid starting of a cold engine
- 9. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Components
Diesel fuel supply system
feeds fuel from the fuel tank to the
injection pump
components
inline electric pump or engine-driven
mechanical pump
filters and water separator to clean the fuel
fuel return lines to carry unused fuel back to
the tank
- 10. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Complete Diesel
System
Supply pump
feeds the
injection pump
- 11. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Diesel Injection Pumps
Bolted to the top or side of the engine
Meter correct amount of fuel to the
injectors
Time fuel injection
Control idle speed and maximum
speed
Provide a means of shutting off the
engine
- 12. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Diesel Injection Pump
Located on the right
side of
the engine
- 14. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Inline Injection Pump
Components
Camshaft
acts on roller
tappet
Tappet
pushes on
plunger
- 15. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Camshaft
Operates one plunger per cylinder
When the engine turns the pump
camshaft, lobes push on the roller
tappets to move them up, forcing
plungers up
Plunger return springs force plungers
back down as the lobes rotate away
from the roller tappets
- 16. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Pump Plungers
Small pistons that slide in individual
barrels to push fuel
Plungers pressurize the fuel, forcing it
through the injector lines and to the
injector nozzles
- 17. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Inline Pump Components
Control sleeves alter amount of fuel to
each injector nozzle
- 18. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Control Rod or Rack
Toothed shaft
Acts as a throttle to control speed and
power
Rotates the control sleeves
Delivery Valves
Spring-loaded valves in the outlets to
the injection lines
Ensure quick, leak-free closing of the
injector nozzles
- 19. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
The fuel supply pump fills the barrel
with fuel
The camshaft forces the roller tappet
and plunger upward in the barrel
Fuel is forced through the delivery
valve, through the injection line, and
out the nozzle
The delivery valve closes when the
plunger reaches the end of its stroke
Pump Operation
- 20. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Pump Operation
Plunger action in an inline pump
- 21. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
The rack slides across the control
sleeves to rotate them
A helix-shaped (spiral) groove and a
slot are cut into the side of the plunger
When the helix is aligned with the port
(hole) in the side of the barrel, the
plunger cannot develop pressure
Fuel flows down the slot, through the
helix groove, and out the port
Metering
- 22. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Metering
Control rack is linked to the gas pedal
and governor
- 23. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Amount of plunger movement that
pressurizes the fuel
When the plunger moves up and the
helix is not aligned with the port, fuel is
trapped and pressurized
Sleeve rotation regulates how much
fuel is injected
Effective Plunger
Stroke
- 24. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Inline Pump
Governor
Controls idle
speed and limits
maximum engine
speed
- 25. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Uses weights, springs, and levers
Levers are connected to control rack
As engine speed increases, weights
are thrown outward (centrifugal force)
This moves the levers and control rack
to reduce effective plunger stroke
Engine speed is limited
Governor Operation
- 26. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
When driver presses the gas pedal,
throttle lever spring pressure
overcomes governor spring pressure
The control rack is moved to increase
fuel delivery (effective plunger stroke is
increased)
When engine speed reaches the
desired level, the governor overcomes
throttle lever spring pressure
Governor Operation
- 29. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Accelerator-Injection
Pump Linkage
- 30. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Injection Timing
Relationship between the moment fuel
is injected into cylinder and piston
position
Controlled by spring-loaded weights in
an inline injection pump
As engine speed increases, weights fly
outward to advance injection timing,
providing more time to ignite and burn
fuel
- 32. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Distributor Injection
Pumps
Only one or two plungers supply fuel
for all the cylinders
Most common type of pump used on
passenger cars
There are two common types of
distributor injection pumps:
single-plunger pumps
two-plunger pumps
- 33. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Single Plunger Pumps
Components
Operation
Metering
Timing
- 35. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Transfer Pump
Forces fuel into the injection pump
Lubricates injection pump
Fills the pumping chambers
Cam Plate
Rotating lobed disc
Operates plunger
Forces plunger to move and develop
injection pressure
- 36. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Fuel Metering Sleeve
Can be slid sideways on the plunger to
change effective plunger stroke
Surrounds the plunger
Hydraulic Head
Housing around the plunger
Contains passages for filling the barrel
and injecting fuel into the delivery
valves
- 37. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Centrifugal Governor
Controls amount of fuel injected and
engine speed
Flyweight action moves the metering
sleeve to limit top speed
- 38. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Single Plunger Pump
Note the system fuel flow
- 40. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Operation
As the shaft rotates, the fill port in the
hydraulic head lines up with the port in
the plunger
The transfer pump forces fuel into the
high-pressure chamber in front of the
plunger
The fill port moves out of alignment
The injection port lines up
The cam plate lobe pushes the plunger
sideways, forcing fuel to the injector
nozzle
- 42. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
As speed increases, injection must
occur sooner
Transfer pump turns faster, increasing
pressure output
Increased pressure moves an injection
advance piston
Cam plate ramps engage plunger
sooner
Injection Timing
- 43. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Injection Timing
Vane pump pressure can be used to
control injection timing
- 45. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Components
Two plungers
force fuel to each injector nozzle
Distributor rotor
controls fuel flow to each injector nozzle
Internal cam ring
acts as a cam to force plungers inward
Fuel metering valve
regulates injection quantity by controlling
how far plungers move apart on the fill
stroke
- 46. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Operation
The transfer pump pulls fuel into the
injection pump
When charging ports line up, fuel fills
the high-pressure chamber
Charging ports move out of alignment
Discharge ports line up
Plungers are forced inward by the cam
ring, forcing fuel out of the hydraulic
head and to the injector nozzles
- 48. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Injector Nozzles
Spring-loaded
valves that spray
fuel directly into
precombustion
chambers
- 50. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Injector Nozzle
Operation
High pressure fuel flows into the
injector nozzle inlet
Fuel flows down the fuel passage in the
body into the pressure chamber
The needle is forced upward,
compressing the spring
Fuel sprays out in a conical pattern
Fuel that leaks past the needle returns
to the fuel tank through return lines
- 51. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
With enough
injection pressure,
the needle valve is
pushed up and fuel
sprays into the
precombustion
chamber
Injector Nozzle
Operation
- 53. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Nozzle Types
Spray patterns for different
types of injectors
- 54. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Glow Plugs
Heating elements that warm air in
precombustion chambers
Threaded into the cylinder head
Control circuit automatically
disconnects the glow plugs after a few
seconds of operation
- 55. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Glow Plug
Tip protrudes into the
precombustion chamber
- 56. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Current flow through the plug heats
the element to warm air in the
precombustion chamber
Glow Plug
- 57. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Control Circuit
Components
Engine coolant temperature sensor
Glow plug control unit
Indicator lights
- 59. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Engine Temperature
Sensor
Senses coolant temperature
Input to control unit
If engine is warm, the control unit will
not turn on glow plugs
- 60. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Indicator Lights
Operated by control unit
Inform driver if engine is ready to start
because glow plugs are fully heated
- 61. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Glow Plug Operation
Engine cold
The driver turns on ignition switch
High current flows from battery to glow
plugs
Glow plugs heat to a dull red glow
When the indicator light goes out, the
engine is ready to crank
Glow plug heat supplements the heat
of compression to ignite mixture
- 62. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Water detector
Fuel heater
Block heater
Vacuum pump
- 63. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Water Detector
Warns driver of water in fuel
Water and other contaminants are very
harmful to the fuel injection pump and
injectors
Fuel Heater
May be used to warm diesel fuel
Prevents fuel from jelling in very cold
weather
Electric heating element is located in the
fuel line, ahead of the injection pump
- 64. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Water Detector and
Fuel Heater
- 65. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Diesel
Injection
Electrical
Circuit
- 66. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Block Heater
May be used to warm the engine in
cold weather
Cold starting aid
Heating device plugs into wall electric
outlet
- 67. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Vacuum Pump
Diesel engines have little manifold
vacuum since there is no throttle valve
Provides a source of vacuum for
vehicle systems:
power brakes
A/C ventilation controls
emission control devices (EGR)
- 69. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Vane-Type Vacuum
Pump
Mounted in back of the alternator
- 70. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Computer-Controlled
Diesel
Uses a computer,
sensors, and
actuators to
increase efficiency
- 71. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Injection Pump
Solenoids
Control injection timing and quantity
Controlled by the computer
When energized or de-energized
electrically, solenoids open or close fuel
passages to alter pump operation
- 72. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Diesel Injection
Sensors
Monitor temperature, speed, and other
variables that affect fuel needs
Similar to those on gasoline systems
- 73. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only
Diesel Injection
Computer
Monitors sensor inputs
Calculates fuel needs
Controls outputs such as pump
solenoids and emission control devices
Precisely controls mechanical high-
pressure plungers inside the injection
pump