Starting Systems and Motor Designs: Summary

  • The starting system is a combination of mechanical and electrical parts that work together to start the engine.
  • The starting system components include the battery, cable and wires, the ignition switch, the starter solenoid or relay, the starter motor, the starter drive and flywheel ring gear, and the starting safety switch.
  • The armature is the moveable component of the motor that consists of a conductor wound around a laminated iron core. It is used to create a magnetic field.
  • Pole shoes are made of high-magnetic permeability material to help concentrate and direct the lines of force in the field assembly.
  • The magnetic forces will cause the armature to turn in the direction of the weaker field.
  • Within an electromagnetic style of starter motor, the inside windings are called the armature. Hie armature rotates within the stationary outside windings, called the field, which has windings coiled around pole shoes.
  • The commutator is a series of conducting segments located around one end of the armature.
  • A split-ring commutator is in contact with the ends of the armature loops. So, as the brushes pass over one section of the commutator to another, the current flow in the armature is reversed.
  • Two basic winding patterns are used in the armature: lap winding and wave winding.
  • The field coils are electromagnets constructed of wire coils wound around a pole shoe.
  • When current flows through the field coils, strong stationary electromagnetic fields are created.
  • In any DC motor, there are three methods of connecting the field coils to the armature: in series, in parallel (shunt), and a compound connection that uses both series and shunt coils.
  • A starter drive includes a pinion gear set that meshes with the engine flywheel ring gear on the engine.
  • To prevent damage to the pinion gear or the ring gear, the pinion gear must mesh with the ring gear before the starter motor rotates.
  • The bendix drive depends on inertia to provide meshing of the drive pinion with the ring gear.
  • The most common type of starter drive is the overrunning clutch. This is a roller-type clutch that transmits torque in one direction only and freewheels in the other direction.
  • The starting system consists of two circuits called the starter control circuit and the motor feed circuit.
  • The components of the control circuit include the starting portion of the ignition switch, the starting safety switch (if applicable), and the wire conductor to connect these components to the relay or solenoid.
  • The motor feed circuit consists of heavy battery cables from the battery to the relay and the starter or directly to the solenoid if the starter is so equipped.
  • There are four basic groups of starter motors: direct drive, gear reduction, positive engagement (moveable pole), and permanent magnet.
  • A synchronous motor operates at a constant speed regardless of load.
  • An induction motor generates its own rotor current as the rotor cuts through the magnetic flux lines of the stator field.
  • The principle of operation for all three-phase motors is the rotating magnetic field.
  • In order to start the synchronous motor, the rotor contains a squirrel-type winding to act as an induction motor.
  • An induction motor rotor windings can be in the form of a squirrel cage or constructed by winding three separate coils on the rotor 120° apart.
  • The ISG can also convert kinetic energy to storable electric energy. When the vehicle is traveling downhill and there is zero load on the engine, the wheels can transfer energy through the transmission and engine to the ISG. The ISG then sends this energy to the battery for storage and use by the electrical components of the vehicle.
  • The belt alternator starter (BAS) is about the same size as a conventional generator and is mounted in the same way.
  • The IGS is a three-phase AC motor. At low vehicle speeds, the ISG provides power and torque to the vehicle. It also supports the engine, when the driver demands more power.
  • Both the BAS and the ISG use the same principle to start the engine. Current flows through the stator windings it generates magnetic fields in the rotor. This will cause the rotor to turn, thus turning the crankshaft and starting the engine.