Transcript CHAPTER - 4 STRUCTURE OF ATOM

TOPIC 2.
ELECTRONIC SYSTEM
• 2.1 Understand the Electronic
Systems And Components
LECTURER NAME: MR. KHAIRUL AKMAL BIN NUSI
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Electronic Ignition Systems
• Electronic ignition systems are made up of a
primary and secondary circuit. The primary
supports the initial start-up of the ignition
switch, battery and primary coil windings. The
secondary circuit supports the electronic
control module, distributor cap, ignition coil
and spark plugs.
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• Turning the ignition key causes the battery to
send current past the ignition switch; this
energizes the primary coil windings. An armature
within the coil assembly builds up power, and
essentially transforms the low voltage into high
voltage. This high voltage is distributed through
the distributor cap and electronic control module.
The voltage proceeds to the spark plugs for firing.
Function
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Induction Electronic Ignition
Systems
• This type of electronic ignition system contains a
coil which stores the power necessary to create
the spark that sets the engine in motion. When
the ignition is activated, the power supply to the
coil is shut off, which triggers the release of
electrical energy. This very simple design is
sometimes referred to as the "Kettering
system," named after the inventor of the modern
ignition system.
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• With the ignition switch turned on, primary (battery)
current flows from the battery through the ignition
switch to the coil primary windings.
• Primary current is turned on and off by the action of
the armature as it revolves past the pickup coil or
sensor. As each tooth of the armature nears the pickup
coil, it creates a voltage that signals the electronic
module to turn off the coil primary current.
• A timing circuit in the module will turn the current on
again after the coil field has collapsed. When the
current is off, however, the magnetic field built up in
the coil is allowed to collapse, which causes a high
voltage in the secondary windings of the coil. It is now
operating on the secondary ignition circuit, which is the
same as in a conventional ignition system.
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• A Hall effect sensor is a transducer that
varies its output voltage in response to
a magnetic field. Hall effect sensors are
used for proximity switching, positioning,
speed detection, and current sensing
applications.
• In its simplest form, the sensor operates
as an analogue transducer, directly
returning a voltage. With a known magnetic
field, its distance from the Hall plate can
be determined. Using groups of sensors,
the relative position of the magnet can be
deduced.
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Hall Effect Sensors
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• Distributor Hall Effect Type
Used to show Engine Speed
and Cylider Recognitioner
• The Hall effect type
Distributor Provides the speed
and the cylinder potion of the
engine. This type of Distributor
replaced the earlier Points type
Distributor.
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Hall Effect Operation
• The Hall effect sensor is a simple switching circuit. The circuit
is switched by a hall chip. The Hall Chip is located adjacent to a
magnet and a drum mounted to the Distributor shaft rotates
between the magnet and sensor. There are cut outs in the drum
that allow the magnet to trigger the hall sensor. When a cut out
passes between the magnet and the Hall sensor the magnetic
field influences the Hall sensor. When a solid part of the drum
passes the Sensor the magnetic filed is removed from the
sensor. It is this action that produces the on/off switch. This
signal is interpreted by the ignition module, Ignition control unit
or Ecu as a square wave.
• The sensor has 3 terminals marked +, - and 0 The + terminal is
the Ecu to Sensor supply voltage. This will generally be 5 volts.
The - terminal is the earth connection and should read 0 volts.
The 0 Terminal is the signal voltage which is a square wave. The
frequency of the signal increases with engine speed.
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Optical Type Sensors
• Optical Sensor.
• The optical sensor is usually located in the
distributor. The rotor plate has many slits in it
through which light passes from the light emitting
diode (LED) to the photo sensitive diode (light
receiving ). As the rotor plate turns, it interrupts
the light beam from the LED to the photo diode.
When the photo diode does not detect light, It
sends a voltage signal to the ignition module,
causing it to fire the coil.
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2.2 The Supplemental
Restraint Systems ( SRS
Systems )
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Airbag
• An airbag is a vehicle safety device. It
is an occupant restraint system
consisting of a flexible envelope
designed to inflate rapidly during an
automobile collision. Its purpose is to
cushion occupants during a crash and
provide protection to their bodies when
they strike interior objects such as the
steering wheel or a window
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• The IMPACT SENSORS are located on both
sides of the front area of the vehicle. The
sensors are very sensitive to impacts, and are
designed to transmit the information of their
activation to the airbag instantly. All the
electrical contacts of the airbag system are
gold plated to eliminate the possibility of
corrosion forming.
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Cars can be repaired .
. . people are a little
more difficult!!
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seat belt
• A seat belt, sometimes called a safety belt, is a safety
harness designed to secure the occupant of
a vehicle against harmful movement that may result
during a collision or a sudden stop. A seat belt reduces
the likelihood and severity of injury in a traffic
collision by stopping the vehicle occupant from hitting
hard against interior elements of the vehicle or other
passengers (the so-called second impact), by keeping
occupants positioned correctly for maximum benefit
from the airbag, if the vehicle is so equipped, and by
preventing occupants being ejected from the vehicle.
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Types of pretensioner
i. Mechanical Pre Tensioner
This pre tensioner is operated mechanically. It is usually
connected to the seat belt buckle assembly with a long
powerful spring that is compressed in a tube and is kept
compressed by a latching mechanism. If an accident occurs
the impact causes the latch to release the spring which
pulls on the buckle assembly and tightens the seat belt.
ii. Electronic/Pyrotechnic Pre Tensioner
This pre tensioner operates with an ECU and a gas
generator system in a similar way to the airbag. In fact
the electronic pre tensioner usually works together with
the airbag and may even use the same ECU as the airbag
and that increases its effectiveness.
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Types
of
attachment
1. Two-point
A 2-point belt attaches at its two endpoints.
Lap
A lap ("2-point") belt in an airplane
A lap belt is a strap that goes over the waist. This was the
most commonly installed type of belt and is primarily found
in older cars.
• Sash
• A "sash" or shoulder harness is a strap that goes
diagonally over the vehicle occupant's outboard shoulder
and is buckled inboard of his or her lap. The shoulder
harness may attach to the lap belt tongue, or it may have a
tongue and buckle completely separate from those of the
lap belt.
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2. Three-point
• A 3-point belt is a Y-shaped
arrangement, similar to the
separate lap and sash belts, but unitized. Like the separate lapand-sash belt, in a collision the 3-point belt spreads out the
energy of the moving body over the chest, pelvis, and shoulders.
3. Belt-in-Seat (BIS)
• The BIS is a three-point harness with the shoulder belt
attached to the seat itself, rather than to the vehicle structure
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4. 4-, 5-, and 6-point
• A 6-point harness in a racing car.
• Five-point harnesses are typically found
in child safety seats and in racing cars.
The lap portion is connected to a belt
between the legs and there are two
shoulder belts, making a total of five
points of attachment to the seat. A 4point harness is similar, but without the
strap between the legs, while a 6-point
harness has two belts between the legs
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Vehicle safety systems
• Vehicle safety systems are designed to protect
occupants during accidents, and can be
classified as primary, or passive systems and
secondary, or active systems.
• Primary systems are ready to use in any
accident. They include bumper bars, body
panels, seatbelts, crumple zones and collapsible
steering columns.
• A secondary system has to be activated to
work and is only necessary in severe accidents.
The two most popular types of secondary
systems are supplemental restraint system air
bags, and seatbelt pre-tensioners.
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Tire-pressure monitoring system
• A tire pressure monitoring system (TPMS) is
an electronic system designed to monitor
the air pressure inside the pneumatic tires on
various types of vehicles. TPMS report realtime tire-pressure information to the driver of
the vehicle, either via a gauge, a pictogram
display, or a simple low-pressure warning light.
TPMS can be divided into two different
types — direct (dTPMS) and indirect (iTPMS).
TPMS are provided both at an OEM (factory)
level as well as an aftermarket solution.
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• Indirect TPMS
• Indirect TPMS do not use physical
pressure sensors but measure air
pressures by monitoring individual wheel
rotational speeds and other signals
available outside of the tire itself. First
generation iTPMS systems utilize the
effect that an under-inflated tire has a
slightly smaller diameter (and hence higher
angular velocity) than a correctly inflated
one. These differences are measurable
through the wheel speed sensors of
ABS/ESC systems
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• Direct TPMS
• Direct TPMS employ pressure sensors on each
tire, either internal or external. The sensors
physically measure the tire pressure in each
tire and report it to the vehicle's instrument
cluster or a corresponding monitor, sometimes
also the temperature inside the tire. These
systems can identify under-inflation in any
combination, be it one tire or all four,
simultaneously. Although the systems vary in
transmitting options, many TPMS products
(both OEM and aftermarket solutions) can
display real time tire pressures at each location
monitored whether the vehicle is moving or
parked.
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2.3. Understand Security
systems
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Remote control keys
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• Remote control keys and key fobs transmit a
coded signal that is received by the vehicles
theft deterrent module. If the code meets
preset criteria, the module closes a switch that
enables either the drivers’ door or all doors to
be locked and unlocked as required.
• Pressing the button a second time when locking
some vehicle activates the dead lock actuators
and deadlocks the vehicle.
• For the remote key and computer to exchange
information, wireless communication is needed.
High frequency electromagnetic fields known as
“Radio Frequency” or RF is used
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Theft deterrent systems
• Theft deterrent systems aim to prevent the
vehicle being entered, started or driven. The
actuators used to achieve this are the electric
door locks and windows, the starter motor
relay, engine management systems, transmission
shift solenoids, and an audible alarm.
• The computer that controls the system
monitors input signals from various devices.
Switches are located at each door, the hood
and trunk openings, and the fuel filler door.
• Vibration sensors detect any unusual vehicle
movement such as lifting, jacking or towing.
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• Ultrasonic sensors detect any movement
inside the cabin.
• Voltage monitoring sensors check against
operation of the starter motor, ignition
system or fuel pump.
• The immobilization system is enabled by
pressing the lock button on the remote
key, locking the doors manually with the
door key, or when a period of time has
elapsed, typically 15 seconds, after the
engine has stopped. The immobilization
system is disabled by pressing the unlock
button on the remote fob.
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2.4 Understand Entertainment
And Peripheral Systems
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Body controlled lighting systems
• In modern vehicles ambient light
sensors are used to automatically turn
the headlights on in low light situations.
Other body control lighting features
can include: automatic 'dipping'
headlights; delayed 'off' headlights;
and headlight warning alarms.
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Proximity sensors
• Proximity sensors are mounted in
the front or rear bumpers. The
control unit determines the
distance between the sensor and an
obstacle by measuring the time
taken for sound waves to leave and
return to the sensor.
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Reflective displays
• Reflective displays use a mirror
embedded in the dash so the
instruments appear further away than
they actually are. This way the driver's
focal point changes less when looking
from the road to the instruments and
back.
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Integrated communications
• Modern vehicles integrate audio, video and communication
systems into a network. This allows for a high quality, compact
and ergonomic system, which combines entertainment features
with simple operation.
• Controls are centralized with hardware, such as CD stackers,
and DVD players located remotely.
• Communication between components uses a combination of hard
wiring and data buses.
• With data buses being used, audio messages can be broadcast
over the audio system that relate to other vehicle systems. For
example, a voice message can say “the park brake is on” or “left
rear tire is under inflated”
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• 2.5. Understand
Satellite
assisted systems
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• The Global Positioning System or GPS uses a
group of at least 24 satellites orbiting
approximately 12 600 miles or 20 200
kilometers above the earth. The vehicle is
equipped with a receiving antenna and
computer system. The GPS receiver on the
vehicle has to locate four or more of these
satellites, determine the distance to each,
and use this information to establish it's own
location. This operation is based on a
mathematical principle called “trilateration”.
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• The word navigation is a combination of
the Latin words navis, meaning a ship,
and agere, meaning guidance. Satellite
Navigation in the context of Vehicle
Telematics is a means of safely guiding a
vehicle to its destination. Traditionally
finding your way involves, spreading a
paper map inside the car Often, it isn’t
easy to immediately know where you are.
You try and find your bearings by looking
for landmarks, checking the surroundings,
or finding the names of intersecting
streets before determining your current
location.
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Automotive telematics
• Automotive telematics is a satellite-based system
that combines two-way communication and
information technology within the vehicle. The
vehicle is equipped with a satellite transceiver
enabling data to be sent to and from the vehicle.
• Using this system allows for: vehicle tracking,
monitoring of onboard systems, messaging, travel
information, entertainment, security, safety and
fleet management systems which monitor
information such as location, distance traveled,
speed, stops and fuel usage.
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• A vehicle manufacturer may
offer telematics as a service to its customers.
The benefits of this can include: the location &
immobilization of a stolen or lost vehicle,
notification to emergency services after SRS
deployment, engine shut down and door
unlocking in the event of a severe accident,
roadside assistance and remote diagnosis.
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