A starter motor is an electrical device used to start an internal combustion engine. The starter motor is a part of a starting system consisting of the starter, a starter solenoid and the battery.
As the ignition switch is turned, it sends an electrical charge to the starter solenoid. This, in turn, sends the charge to the motor that cranks the engine until it starts. Once the engine fires to life, the starter motor clicks off and disengages the starter ring.
HOW STARTER MOTOR WORKS
The typical starter motor is composed of heavy copper wire wound around an armature. This device is
placed inside of a heavy steel or aluminum case equipped with electrical brushes that contact the
armature and pass the electrical charge to the heavy wire. As the electricity flows through the wire, it causes the armature to spin. A small gear is attached to the output shaft of the armature and moved in and out by means of a Bendix. The Bendix engages the small gear with the starter ring, which turns the engine as the armature turns.
STARTER MOTOR FAULTS THAT NEED TO BE DETECTED BEFORE SHIPMENT TO CUSTOMER
- The brushes become burned and fail to transfer the electrical charge to the armature.
- The Bendix can also become sticky and fail to engage the starter gears.
- A bench test, which is accomplished by running an electrical charge through the starter while it is out of the engine bay, will usually determine the problem.
- A starter that fails to run when a charge is placed to it typically implies a brush defect.
- A starter that spins but does not send the starter gear outward is often suffering from a broken or defective Bendix
- Loose mounting bolt(s)
- Starter problems can be caused by worn brushes (carbon pads inside the motor that supply current to the rotating armature), by shorts or opens in the armature or field coils or by worn bushings that increase drag or allow the armature shaft to rub against the pole shoes.
- Sun and Planet gear assembly defects.
FOLLOWING APPROACH WAS FOLLOWED TO DETECT FAULTY MOTORS
- Acoustic Enclosure was designed and used
- Vibration and sound pressure data was simultaneously acquired
- Vibration data was acquired on the stopper platform
- Sound pressure data was acquired just above the motor within the Acoustic Enclosure
- Three sets of motors were used – known to be good, known to be bad and known to be overlapping cases
- In the current case study vibration envelop spectrum analysis has been used as one of the indicators
- Second indicator is sound pressure level on dB and dBA scales
- The starter testing machine can test the voltage,loading,braking,performance,overspeed testing
Pearl
Emily