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.

Integrated Starter Generator

One of the newest technologies to emerge is the ⚡ integrated starter generator ⚡ (ISG). Although this system can be used in conventional engine-powered vehicles, one of the key contributors to the Hybrid’s fuel efficiency is its ability to automatically stop and restart the engine under different operating conditions. A typical Hybrid vehicle uses a 14 kilowatt (kW) electric induction motor or ISG between the engine and the transmission. The ISG performs many functions such as fast, quiet starting, automatic engine stops/starts to conserve fuel, recharges the vehicle batteries, smoothes driveline surges, and provide regenerative braking.

The ISG 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. During vehicle deceleration, ISG regenerates the power that is used to charge the traction batteries.

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The ISG can also convert kinetic energy from AC to DC voltage.… READ THE REST

AC Motor Principles

AC three-phase motor used in a HEV

FIGURE. AC three-phase motor used in a HEV.

A few years ago, the automotive technician did not need to be concerned much about the operating principles of the AC motor. With the increased focus on HEVs and EVs, this is no longer an option since most of these vehicles use AC motors.

AC voltage gradually changes. It is rated at the RMS

FIGURE. AC voltage gradually changes. It is rated at the RMS.

AC voltage has a changing direction of current flow. However, this change does not occur immediately. Notice that the AC voltage sine wave indicates that in one cycle the voltage will be zero at three times. Also notice that as the current changes directions, it gradually builds up or falls in the other direction. The sine wave illustrates that the amount of current in an AC circuit always varies. The current rating is based on the average referred to as a root mean square (RMS) value.

AC Motor Construction

Like the DC motor, the AC motor uses a stator (field winding) and a rotor.… READ THE REST

Cranking Motor Designs

The most common type of starter motor used today incorporates the overrunning clutch starter drive instead of the old inertia-engagement bendix drive. There are four basic groups of starter motors:

  1. Direct drive.
  2. Gear reduction.
  3. Positive-engagement (moveable pole).
  4. Permanent magnet.

Direct Drive Starters

Solenoid operated Delco MT series starter motor

FIGURE. Solenoid operated Delco MT series ⚡ starter motor ⚡.

A common type of starter motor is the solenoid-operated direct drive unit. Although there are construction differences between applications, the operating principles are the same for all solenoid-shifted starter motors.

When the ignition switch is placed in the START position, the control circuit energizes the pull-in and hold-in windings of the solenoid. The solenoid plunger moves and pivots the shift lever, which in turn locates the drive pinion gear into mesh with the engine flywheel. When the solenoid plunger is moved all the way, the contact disc closes the circuit from the battery to the starter motor. Current now flows through the field coils and the armature.… READ THE REST

Starter Control Circuit Components

Video: Motor Starter Control Circuit Demonstration

Magnetic Switches

The ⚡ starter motor ⚡ requires large amounts of current (up to 300 amperes) to generate the torque needed to turn the engine. The conductors used to carry this amount of current (battery cables) must be large enough to handle the current with very little voltage drop. It would be impractical to place a conductor of this size into the wiring harness to the ignition switch. To provide control of the high current, all starting systems contain some type of magnetic switch. There are two basic types of magnetic switches used: the solenoid and the relay.

Solenoid-operated starter has the solenoid mounted directly on top of the motor

FIGURE. Solenoid-operated starter has the solenoid mounted directly on top of the motor.

Starter-Mounted Solenoids. A solenoid is an electromagnetic device that uses the movement of a plunger to exert a pulling or holding force. In the solenoid-actuated starter system, the solenoid is mounted directly on top of the ⚡ starter motor ⚡.… READ THE REST

Cranking Motor Circuits

The starting system of the vehicle consists of two circuits: the starter control circuit and the motor feed circuit. These circuits are separate but related. Hie control circuit consists of 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.… READ THE REST

Starter Drives

The starter drive is the part of the starter motor that engages the armature to the engine fly-wheel ring gear. A starter drive includes a pinion gear set that meshes with the flywheel ring gear on the engine’s crankshaft. 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. To help assure smooth engagement, the ends of the pinion gear teeth are tapered. Also, the action of the armature must always be from the motor to the engine. The engine must not be allowed to spin the armature. The ratio of the number of teeth on the ring gear and the starter drive pinion gear is usually between 15:1 and 20:1. This means the starter motor is rotating 15 to 20 times faster than the engine. The ratio of the starter drive is determined by dividing the number of teeth on the drive gear (pinion gear) into the number of teeth on the driven gear (flywheel).… READ THE REST