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Halderman ch052 lecture
 

Halderman ch052 lecture

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  • Figure 52-1 A typical solenoid-operated starter.
  • Figure 52-2 Some column-mounted ignition switches act directly on the electrical ignition switch itself, whereas others use a link from the lock cylinder to the ignition switch.
  • Figure 52-3 To prevent the engine from cranking, an electrical switch is usually installed to open the circuit between the ignition switch and the starter solenoid.
  • Figure 52-4 Instead of using an ignition key to start the engine, some vehicles are using a start button which is also used to stop the engine, as shown on this Jaguar.
  • Figure 52-5 The top button on this key fob is the remote start button.
  • Figure 52-6 This series-wound electric motor shows the basic operation with only two brushes: one hot brush and one ground brush. The current flows through both field coils, then through the hot brush and the loop winding of the armature, before reaching ground through the ground brush.
  • Figure 52-7 The interaction of the magnetic fields of the armature loops and field coils creates a stronger magnetic field on the right side of the conductor, causing the armature loop to move toward the left.
  • Figure 52-8 The armature loops rotate due to the difference in the strength of the magnetic field. The loops move from a strong magnetic field strength toward a weaker magnetic field strength.
  • Figure 52-9 Magnetic lines of force in a four-pole motor.
  • Figure 52-10 A pole shoe and field winding.
  • Figure 52-11 This wiring diagram illustrates the construction of a series-wound electric motor. Notice that all current flows through the field coils, then through the armature (in series) before reaching ground.
  • Figure 52-12 This wiring diagram illustrates the construction of a shunt-type electric motor, and shows the field coils in parallel (or shunt) across the armature.
  • Figure 52-13 A compound motor is a combination of series and shunt types, using part of the field coils connected electrically in series with the armature and some in parallel (shunt).
  • Figure 52-14 A typical starter motor showing the drive-end housing.
  • Figure 52-15 Pole shoes and field windings installed in the housing.
  • Figure 52-16 A typical starter motor armature. The armature core is made from thin sheet metal sections assembled on the armature shaft, which is used to increase the magnetic field strength.
  • Figure 52-17 An armature showing how its copper wire loops are connected to the commutator.
  • Figure 52-18 A cutaway of a typical starter motor showing the commutator, brushes, and brush spring.
  • Figure 52-20 A typical gear-reduction starter.
  • Figure 52-21 A cutaway of a typical starter drive showing all of the internal parts.
  • Figure 52-22 The ring gear to pinion gear ratio is usually 15:1 to 20:1.
  • Figure 52-23 Operation of the overrunning clutch. (a) Starter motor is driving the starter pinion and cranking the engine. The rollers are wedged against spring force into their slots. (b) The engine has started and is rotating faster than the starter armature. Spring force pushes the rollers so they can rotate freely.
  • Figure 52-24 A Ford movable pole shoe starter.
  • Figure 52-26 A palm-size starter armature.

Halderman ch052 lecture Halderman ch052 lecture Presentation Transcript

  • CRANKING SYSTEM 52
  • Objectives
    • The student should be able to:
      • Prepare for ASE Electrical/Electronic Systems (A6) certification test content area "C" (Starting System Diagnosis and Repair).
      • Describe how the cranking circuit works.
  • Objectives
    • The student should be able to:
      • Discuss how a starter motor converts electrical power into mechanical power.
      • Describe the hold-in and pull-in windings of a starter solenoid.
  • CRANKING CIRCUIT
  • Cranking Circuit
    • Parts Involved
      • For engine to start, must first be rotated using external power source.
      • Cranking circuit creates necessary power.
  • Cranking Circuit
    • Parts Involved
      • Starter motor
      • Battery
      • Starter solenoid or relay
  • Cranking Circuit
    • Parts Involved
      • Starter drive
      • Ignition switch
  • Figure 52-1 A typical solenoid-operated starter.
  • Figure 52-2 Some column-mounted ignition switches act directly on the electrical ignition switch itself, whereas others use a link from the lock cylinder to the ignition switch.
  • Cranking Circuit
    • Control Circuit Parts and Operation
      • Engine cranked by electric motor controlled by ignition switch.
      • Ignition switch will not operate unless transmission is in neutral or park.
  • Cranking Circuit
    • Control Circuit Parts and Operation
      • Controls used to be sure vehicle will not move when being cranked.
        • Neutral safety switch
  • Cranking Circuit
    • Control Circuit Parts and Operation
      • Controls used to be sure vehicle will not move when being cranked.
        • Mechanical blocking device in steering column
        • Clutch safety switch
  • Figure 52-3 To prevent the engine from cranking, an electrical switch is usually installed to open the circuit between the ignition switch and the starter solenoid.
  • COMPUTER-CONTROLLED STARTING
  • Computer-Controlled Starting
    • Operation
      • Some ignition systems use vehicle ’s computer to crank engine.
        • Some key-operated ignition systems.
        • Most push-to-start systems.
  • Computer-Controlled Starting
    • Operation
      • Before powertrain control module (PCM) cranks engine:
        • Brake pedal must be depressed.
        • Gear selector must be in park or neutral.
  • Computer-Controlled Starting
    • Operation
      • Before powertrain control module (PCM) cranks engine:
        • Correct key fob (code) must be present in vehicle.
  • Figure 52-4 Instead of using an ignition key to start the engine, some vehicles are using a start button which is also used to stop the engine, as shown on this Jaguar.
  • Computer-Controlled Starting
    • Remote Starting
      • Sometimes called remote vehicle start (RVS).
      • Allows driver to start engine from a distance of up to 200 ft (65 m).
      • Allows heating or air-conditioning to start before driver arrives.
  • Figure 52-5 The top button on this key fob is the remote start button.
  • STARTER MOTOR OPERATION
  • Starter Motor Operation
    • Principles
      • Converts electrical energy from battery to mechanical power to crank engine.
      • Current creates strong magnetic field in starter.
      • Magnetic field rotates armature.
  • Figure 52-6 This series-wound electric motor shows the basic operation with only two brushes: one hot brush and one ground brush. The current flows through both field coils, then through the hot brush and the loop winding of the armature, before reaching ground through the ground brush.
  • Figure 52-7 The interaction of the magnetic fields of the armature loops and field coils creates a stronger magnetic field on the right side of the conductor, causing the armature loop to move toward the left.
  • Figure 52-8 The armature loops rotate due to the difference in the strength of the magnetic field. The loops move from a strong magnetic field strength toward a weaker magnetic field strength.
  • Figure 52-9 Magnetic lines of force in a four-pole motor.
  • Figure 52-10 A pole shoe and field winding.
  • Starter Motor Operation
    • Series Motors
      • Develops maximum torque at initial start.
      • Used for automotive starter motor because of high starting power.
  • Starter Motor Operation
    • Series Motors
      • Develops less torque at high RPM.
      • Torque of the starter decreases as the starter speed increases.
  • Figure 52-11 This wiring diagram illustrates the construction of a series-wound electric motor. Notice that all current flows through the field coils, then through the armature (in series) before reaching ground.
  • Starter Motor Operation
    • Shunt Motors
      • Have field coils in parallel (or shunt) across armature.
      • Does not decrease in torque at higher motor RPM.
      • Does not produce as high starting torque as series motor; not used for starters.
  • Figure 52-12 This wiring diagram illustrates the construction of a shunt-type electric motor, and shows the field coils in parallel (or shunt) across the armature.
  • Starter Motor Operation
    • Permanent Magnet Motors
      • Uses permanent magnets that maintain constant field strength.
      • Have similar operating characteristics to shunt-type motors.
      • Use gear reduction to multiply starter motor torque.
  • Starter Motor Operation
    • Compound Motors
      • Have operating characteristics of series motor and shunt-type motor.
      • Commonly used in Ford, Chrysler, and some GM starters.
  • Figure 52-13 A compound motor is a combination of series and shunt types, using part of the field coils connected electrically in series with the armature and some in parallel (shunt).
  • HOW THE STARTER MOTOR WORKS
  • How the Starter Motor Works
    • Parts Involved
      • Main field housing.
        • Commutator-end (or brush-end) housing
        • Drive-end housing.
          • Contains drive pinion gear.
  • How the Starter Motor Works
    • Parts Involved
      • Field coils.
      • Armature core and shaft.
  • Figure 52-14 A typical starter motor showing the drive-end housing.
  • Figure 52-15 Pole shoes and field windings installed in the housing.
  • Figure 52-16 A typical starter motor armature. The armature core is made from thin sheet metal sections assembled on the armature shaft, which is used to increase the magnetic field strength.
  • Figure 52-17 An armature showing how its copper wire loops are connected to the commutator.
  • How the Starter Motor Works
    • Starter Brushes
      • Four-pole motor has four brushes riding on commutator.
      • Two grounded and two insulated brushes.
        • Held against commutator by spring force.
  • Figure 52-18 A cutaway of a typical starter motor showing the commutator, brushes, and brush spring.
  • How the Starter Motor Works
    • Permanent Magnet Fields
      • Permanent magnets now used in place of electromagnetic field coils and pole shoes in many starters.
      • Eliminates motor field circuit.
  • How the Starter Motor Works
    • Permanent Magnet Fields
      • Eliminates potential for field coil faults.
      • Motor has only an armature circuit.
  • GEAR-REDUCTION STARTERS
  • Gear-Reduction Starters
    • Purpose and Function
      • Increases starter motor speed.
      • Provide torque multiplication necessary to crank engine.
  • Gear-Reduction Starters
    • Purpose and Function
      • Makes for smaller starter with reduced starter amperage requirements.
      • Smaller battery cables can be used.
  • Figure 52-20 A typical gear-reduction starter.
  • STARTER DRIVES
  • Starter Drives
    • Purpose and Function
      • Includes small pinion gears.
      • Mesh with and rotate larger gear on engine flywheel for starting.
  • Figure 52-21 A cutaway of a typical starter drive showing all of the internal parts.
  • Starter Drives
    • Starter Drive Gear Ratio
      • Typical starter pinion gear 9 teeth; turn engine ring gear with 166 teeth.
      • 18:1 gear reduction.
      • Starter motor rotating 18 times faster than engine.
  • Figure 52-22 The ring gear to pinion gear ratio is usually 15:1 to 20:1.
  • Starter Drives
    • Starter Drive Operation
      • Uses one-way (overrunning) clutch that allows starter to rotate engine.
      • Then turns freely if engine speed greater than starter motor speed.
      • Protects starter motor from damage if ignition key held too long.
    ?
  • Figure 52-23 Operation of the overrunning clutch. (a) Starter motor is driving the starter pinion and cranking the engine. The rollers are wedged against spring force into their slots. (b) The engine has started and is rotating faster than the starter armature. Spring force pushes the rollers so they can rotate freely.
  • Starter Drives
    • Failure Mode
      • Major wear occurs in overrunning clutch section of starter drive unit.
      • Worn starter drive can cause starter motor to operate and then stop cranking.
  • Starter Drives
    • Failure Mode
      • "Whining" noise heard.
      • Indicates starter motor operating but not rotating engine.
      • Entire starter drive replaced as unit.
  • POSITIVE ENGAGEMENT STARTERS
  • Positive Engagement Starters
    • Operation
      • Used on Ford engines from 1973 to 1990.
      • Use shunt coil winding and movable pole shoe to engage starter drive.
  • Positive Engagement Starters
    • Operation
      • Movable pole shoe "opens" a set of contact points.
      • Contact points provide ground return path for drive coil operation.
  • Figure 52-24 A Ford movable pole shoe starter.
  • Positive Engagement Starters
    • Advantages
      • Movable metal pole shoe engages starter drive with a lever.
      • Does not use a solenoid.
  • Positive Engagement Starters
    • Disadvantages
      • If grounding contact points severely pitted, starter may not operate starter drive.
      • If contact points bent or damaged, starter will not allow starter motor to operate.
  • SOLENOID-OPERATED STARTERS
  • Solenoid-Operated Starters
    • Solenoid Operation
      • Switch containing two separate, but connected, electromagnetic windings.
      • Engages starter drive and controls current from battery to starter motor.
  • Solenoid-Operated Starters
    • Solenoid Windings
      • Windings contain approximately same number of turns.
      • Are made from different-gauge wire.
  • Solenoid-Operated Starters
    • Solenoid Windings
      • Together produce strong magnetic field; pulls metal plunger into solenoid.
        • Heavier-gauge winding needed to draw in plunger.
  • Solenoid-Operated Starters
    • Solenoid Windings
      • Together produce strong magnetic field; pulls metal plunger into solenoid.
        • Lighter-gauge winding produces enough magnetic force to keep plunger in position.
  • Solenoid-Operated Starters
    • Solenoid Windings
      • Causes starter drive to move into mesh with flywheel ring gear.
  • Figure 52-26 A palm-size starter armature.
  • Solenoid-Operated Starters
    • Operation
      • Operates soon as ignition or computer-controlled relay energizes start terminals.
      • Plunger is drawn into solenoid enough to engage starter drive.
  • Solenoid-Operated Starters
    • Operation
      • Plunger contacts metal disk connecting battery terminal post of solenoid to motor terminal.
      • Full battery current flows through solenoid to operate starter motor.
    ?
  • TECH TIP
    • Don ’t Hit That Starter!
      • In the past, it was common to see service technicians hitting a starter in their effort to diagnose a no-crank condition. Often the shock of the blow to the starter aligned or moved the brushes, armature, and bushings. Many times, the starter functioned after being hit, even if only for a short time.
    BACK TO PRESENTATION
    • However, most starters today use permanent magnet fields, and the magnets can be easily broken if hit. A magnet that is broken becomes two weaker magnets. Some early PM starters used magnets that were glued or bonded to the field housing.
    • If struck with a heavy tool, the magnets could be broken with parts of the magnet falling onto the armature and into the bearing pockets, making the starter impossible to repair or rebuild.
      • Figure 52-19 This starter permanent magnet field housing was ruined when someone used a hammer on the field housing in an attempt to "fix" a starter that would not work. A total replacement is the only solution in this case.
  • FREQUENTLY ASKED QUESTION
    • What Is a Bendix?
      • Older-model starters often used a Bendix drive mechanism, which used inertia to engage the starter pinion with the engine flywheel gear. Inertia is the tendency of a stationary object to remain stationary, because of its weight, unless forced to move.
    ? BACK TO PRESENTATION
    • On these older-model starters, the small starter pinion gear was attached to a shaft with threads, and the weight of this gear caused it to be spun along the threaded shaft and mesh with the flywheel whenever the starter motor spun. If the engine speed was greater than the starter speed, the pinion gear was forced back along the threaded shaft and out of mesh with the flywheel gear.
    • The Bendix drive mechanism has generally not been used since the early 1960s, but some technicians use this term when describing a starter drive.
  • FREQUENTLY ASKED QUESTION
    • How Are Starters Made So Small?
      • Starters and most components in a vehicle are being made as small and as light in weight as possible to help increase vehicle performance and fuel economy.
    ? BACK TO PRESENTATION
    • A starter can be constructed smaller due to the use of gear reduction and permanent magnets to achieve the same cranking torque as a straight drive starter, but using much smaller components.
      • Figure 52-26 A palm-size starter armature.