Auto startign by robham solomon on WSU Ethiopia

Starting system presentation

1. Engine Starting (Cranking) System The starting system provides a method of rotating (cranking) the vehicle’s internal combustion engine (ICE) to begin the combustion cycle. Modern vehicles use an electric starter motor that draws its electrical power from the vehicle’s battery. The starter is designed to work for short periods of time and must crank the engine at sufficient speed in order for it to start. Modern starting systems are very effective provided that they, and the battery , are well maintained.

2. The starting/cranking system consists of the battery, high and low-amperage wires, a solenoid, a starter motor assembly ring gear , and the ignition switch. During the cranking process, two actions occur. The pinion of the starter motor engages with the flywheel ring gear, and the starter motor then rotates to turn over, or crank, the engine. The starter motor is an electric motor mounted on the engine block or transmission . It is typically powered by the 12-volt storage battery and is designed to have high turning effort (torque) at low speeds.

3. Starter Motor Principles The starter motor converts electrical energy to mechanical energy for the purpose of cranking the engine over. There are three basic sections to the typical starter—the electric motor , the drive mechanism , and the solenoid . The starter motor is mounted on the transmission or cylinder block in a position to engage a ring gear around the outside edge of the engine flywheel , flex plate , or torque converter.

4. Starting is usually accomplished by the operator activating a starter switch built into the ignition lock assembly, or a start button . A relatively small current flows through a neutral safety switch or clutch switch to a starter relay that controls a larger current to operate the starter solenoid, which is typically mounted on the starter motor. The solenoid plunger moves the drive pinion gear into engagement with the ring gear and also closes a set of heavy-duty contacts . This allows a very large current to flow from the battery to the starter motor, rotating the armature and drive pinion gear, causing the crankshaft to rotate. When the engine starts and is able to run on its own, the operator usually releases the key and the solenoid spring withdraws the pinion gear from the ring gear and brings the armature to a halt.

5. Starter motors can be designed to drive the ring gear in one of two ways: either direct drive or gear reduction. In the direct drive system, the starter drive is mounted directly on one end of the armature shaft. The starter drive transfers the rotating force of the armature directly to the engine flywheel In this arrangement, the only gear reduction is the reduction between the pinion gear and the ring gear. Direct Drive/Gear Reduction Systems Gear reduction starters use an extra gear between the armature and the starter drive mechanism. They have a reduction of about 4:1, which allows the starter to spin at a higher speed while drawing less current from the storage battery

6. In today’s vehicles, there are several types of starter motors that are in use, and each type of starter motor is constructed a bit differently. Keep in mind that the basic principles of operation will remain the same across each type of starter. The parts and pieces employed to establish starter operation may vary between starter designs, be it a pole-shoe type starting motor , a permanent magnet type starting motor , a direct-drive starter , or a gear reduction unit . Starter Motor Construction

7. Starter motors use two magnet types: electromagnetic and permanent magnet Electromagnetic starter fields are formed by current flow through heavy copper windings, wound around iron pole shoes, which are then fastened to the starter case/barrel. Permanent magnet-type starters have large permanent magnets mounted in the same position as pole shoes. Since these types of magnets do not need electricity to produce a magnetic field, this type of starter motor is smaller than a starter motor that uses electromagnets. The starter case is made of iron on both types of starters, and serves to concentrate the magnetic field produced by the magnets. Starter Magnet Types