autotronics-1-2

U N I T - 1Automotive fundamentals

The engine-components - Drive train- starting & charging systems operation Ignition system- Suspension systems- brakes- ABS- Steering systems.

Dr.Manzoor HM. JNTU Hyderabad.

Charging systems operationCharging SystemsUses mechanical energy from engine to create electrical energy to operate vehicle electrical system and recharge battery


Recharges battery after cranking

Supplies the cars electricity when the engine is running

Provides output voltage slightly higher than battery voltage

Changes output to meet varying loads

Charging System Functions


Types of Charging SystemsTwo types:AC Generator (alternator)DC GeneratorCrankshaft turns the alternator beltPulley and Belt


Generator versus Alternator


Alternator B+Output TerminalRegulator, Diode,& Brush CoverEnd Frame CoverDrive Frame CoverDrive PulleyMounting EarCirculation VentIdentificationLabelAlternator Assembly


Alternator: An iron core (rotor) is rotated by the engine within a stationary coil of wire (stator). A current (field current) is passed through the rotor creating a strong magnetic fieldAs the rotor and strong magnetic field rotate within the stator, an alternating electrical current is induced in the stator coil windingsAlternating current (AC) produced by alternator is converted to direct current (DC) for use by vehicle electrical system by diodesAlternator output is controlled by a voltage regulatorWhen output is too high, regulator reduces field current powerWhen output is too low, regulator increases field current powerNormal charging system voltage: 13.6 to 14.8 voltsHigh voltage can damage light bulbs, motors and electronic componentsLow voltage can prevent battery from recharging properlyAlternator output should be sufficient to operate all electrical accessories and still maintain voltage necessary to recharge battery.

Charging System


Four wires connect the alternator to the rest of the charging system.

B is the alternator output wire that supplies current to the battery.

IG is the ignition input that turns on the alternator/regulator assembly.

S is used by the regulator to monitor charging voltage at the battery.

L is the wire the regulator uses to ground the charge warning lamp.Charging System Circuit


Rectified AC CurrentAutomobiles electrical system requires direct current (DC) which flows one wayAlternator output must be rectified (changed) from AC to DCDiode allows current flow in only one directionSeveral are connected into a rectifier bridge


Understanding the AlternatorThe alternator contains:

A rotating field winding called the rotor.

A stationary induction winding called the stator.

A diode assembly called the rectifier bridge.

A control device called the voltage regulator.

Two internal fans to promote air circulation.

AlternatorOverview


Understanding the AlternatorAlternator drive pulleys either bolt on or are pressed on the rotor shaft.

Both V and Multi-grove types are used.

Note this alternator does not have an external fan as part of the pulley assembly.

While many manufacturers do use a external fan for cooling. This alternator has two internal fans to draw air in for cooling.Drive Pulley


Understanding the Alternator

Removal of the rear cover reveals:

BrushesDiode Rectifier BridgeRegulatorInside the AlternatorThe Rectifier Bridge converts AC voltage to DC voltage.The Brushes conduct current to the rotor field winding.The Regulator controls the alternator output.Slip Rings (part of the Rotor Assembly)


Two slip rings are located on one end of the rotor assembly. Each end of the rotor field winding is attached to a slip ring. Thereby, allowing current to flow through the field winding.Two stationary carbon brushes ride on two rotating slip rings. Bushes are either soldered or bolted Brushes


Understanding the Alternator

Removal of the rear cover reveals:

BrushesDiode Rectifier BridgeRegulatorInside the AlternatorThe Rectifier Bridge converts AC voltage to DC voltage.The Brushes conduct current to the rotor field winding.The Regulator controls the alternator output.Slip Rings (part of the Rotor Assembly)


Understanding the AlternatorSlip RingsBearingInternal Cooling FanRotor AssemblyFinger PolesRotor Field WindingRotor ShaftInternal Cooling Fan


Stator WindingLaminated Iron FrameStator Lead EndsThree Phase WindingsNeutral Junction


As the rotor assembly rotates within the stator winding.

The alternating magnetic field from the spinning rotor induces an alternating voltage into the stator winding.

Both the strength of the magnetic field and the speed of the rotor affect the amount of voltage induced into the stator.

Rotor / Stator Relationship


Body-on-Chassis/Frame Construction


Automobile Engine


Starting SystemsStarting system uses an electric motor mounted to the engine or transmission The starter motor meshes a small gear with the engine crankshaft to rotate crankshaft fast enough to start engineThe starter drive gear is moved into place by the starter solenoid


*Starter MotorThe starter motor has a drive assembly that engages the ring gear and rotates the engine.A Starter DriveB Flywheel Ring GearC Pinion Gear


*Starter MotorThe pinion gear meshes with the ring gear before the motor turnsThe teeth on the pinion gear are tapered to ensure smooth engagementThe drive assembly includes an overrunning clutch.


Starting System Circuit


Starter-Mounted SolenoidSolenoid plunger moves a shift lever to engage the pinion gear


Starting systemsThe starter solenoid is energized by the ignition switch and also provides high current for the starter motorThe over-running clutch allows the starter to rotate the engine while preventing the engine from rotating the starter motor


Starting SystemsThe starter motor contains a rotating conductor called an armatureStationary magnets are mounted inside the starter housingWhen current flows through the armature, strong attracting and opposing magnetic fields are created and react with the stationary magnets to cause the armature to rotate


Starting SystemsGear reduction starters Allows a smaller motor to be used at high speedGear reduction reduces speed while increasing torque


The End


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