Automobile Electrical system

 2.1. Introduction

Automobile engineer must have knowledge about an electrical and electronic systems corresponding to automobile engineering, because proper function of automobile depends on some important parts of electrical and electronic system. Nowadays use of electric microprocessor rapidly goes on increasing. The main objectives are, to impart the basic knowledge of AUTOMOBILE ELECTRICAL SYSTEMS and ELECTRONIC DEVICES as well as basic functioning in modern vehicles. The electrical and electronic systems of the motor vehicle are often the most feared, but at the same time can be the most fascinating aspects of an automobile. The complex circuits and systems now in use have developed in a very interesting way.

Fig 2.1-a: Automobile Electrical Systems

One of the important and essential groups of systems belongs to the area of auto electrical. The electrical systems of an automobile are meant to serve the following purposes:-

1. To generate electricity for charging of the battery.
2. To store electricity in the battery and then supply the same to various units.
3. To supply current to starting motor for cranking.
4. To supply current to ignition coil for producing spark in petrol and gas engines.
5. To supply current to the lighting system.
6. To supply current to the horn, dashboard instruments and the control gauges.
7. To supply power to various other electrical accessories.

To accomplish these functions, several systems or circuits are contained in automotive electrical line-up. These major automotive electrical system and their components are shown in Fig. [2.1-b].

2.2 The major electrical systems in automobile:

The components of the automobile electrical system are of complicated construction, but all of them are applications of the various actions made possible by the flow of electricity. Before taking up the construction and operation of these various electric components, the fundamentals of electricity will first be reviewed. Electricity is a form of energy and it is produced by the movement of small atomic particles known as electrons. It can be easily transmitted or converted to other forms, such as mechanical or heat energy. To transmit electricity, conductors such as copper, steel, carbon or an electrolyte are used. Insulators such as rubber, porcelain or Bakelite are used to prevent electrical leakage from conductors.

Electricity is used for a number of purposes in the automobiles. By means of electric current engine is cranked, spark is provided, battery is charged, horn is blown, different lights are put on and many other components such as fornicators, fan, heater, wiper machines, music system, clock etc. are put into working order.

The electrical parts of automobiles according to their functions, mainly divided into two categories: Primary and Auxiliary Electrical system. In primary electrical system includes namely Starting system, Charging system, Ignition system, and Wiring system. In an auxiliary electrical systems including lighting system, signaling system, instrument system, electronic control system, etc.

Fig: 2.1-b: Automobile electrical system

The major electrical systems in automobile:

1. Starting system:

• Switches

• Battery

• Starting motor

• Wiring

2. Charging (Generation or Distribution) system:

• Alternator and regulator, with wiring, Storage Battery.

3. Ignition system:

• Contact -point ignition system

• Electronic ignition systems.

• Spark plugs or Injectors (in case CI engines)

• Distributor and ignition coils.

4. Wiring system:

• Wiring harnesses and Standard color codes

5. Lighting and Accessory (Auxiliary) system:

• Lighting

• Horns

• Wiper system

• Electric mirrors and window system

• Instrument -panel (Dashboard) warning systems.

• Fuse box.