Contents: Safety precautions when servicing…⤓ Charging system ⤓ Engine starting system ⤓ Ignition system ⤓ Diesel engine preheating system ⤓ Precautions when working with…⤓
Safety precautions when servicing vehicles equipped with an additional passive restraint system (SRS)
The SRS system includes the following components: SRS control unit, SRS indicator lamp, air bag modules, clock spring and connecting wires.
Unqualified maintenance or repair of any component of the SRS system (as well as an associated component of the SRS system) may result in injury or death to service personnel (as a result of unauthorized activation of the inflatable airbag), as well as to the driver and front passenger (as a result of inoperable SRS system after unqualified maintenance or repair).
Service or repair of any SRS component (or related component) must be performed only by an authorized Mitsubishi dealer.
Consumers are connected to the positive power source by a wire, and to the negative one - through the car body ("ground"). This method allows to reduce the number of wires and simplify installation.
Charging system
The charging system uses energy from the alternator to maintain the battery in a charged state regardless of changes in the electrical load.
The alternating magnetic field generated by the rotation of the generator rotor induces an EMF (alternating voltage) of variable magnitude and direction in the stator winding.
Passing through rectifier diodes, the alternating voltage is converted into direct voltage. The average value of the generator output voltage changes slightly depending on the load.
When the ignition key is turned to the "ON" position, current passes through the rotor winding and the initial magnetization of the winding occurs (excitation of the generator).
When voltage is generated on the stator winding after the engine is started, the excitation winding (rotor) is fed from the output current of the stator winding, rectified by three rectifier diodes. When the excitation current increases, the generator output voltage increases, and when the excitation current decreases, it decreases.
When the battery voltage reaches the set value of 14.4 V (terminal "S" of the generator), the excitation current is switched off. When the battery voltage decreases below the set value, the voltage regulator, controlling the excitation winding current, maintains the generator output voltage at a constant level. In addition, when the excitation current value is constant, the generator output voltage increases with an increase in the engine crankshaft speed.
Engine starting system
When the ignition key is turned to the "START" position, current flows through the pull-in winding of the starter traction relay, moving the anchor of the traction relay.
The anchor of the traction relay moves the drive lever (fork), which in turn engages the drive pinion with the flywheel ring gear. At the same time, the movement of the anchor of the traction relay closes contacts "B" and "M".
As a result, current begins to flow through the starter armature windings (as well as the holding winding of the traction relay), thereby turning on the starter electric motor. When the ignition key is returned to the "ON" position after the engine has started, the starter overrunning clutch disengages the drive pinion from the flywheel ring gear.
To prevent the starter from being carried away by the engine, a freewheel clutch is installed between the starter drive gear and the anchor.
Ignition system
The ignition system ignites the fuel-air mixture in the engine cylinders at a certain moment depending on the engine crankshaft speed and load. Various types of ignition systems are installed on cars.
The ignition system is powered by the vehicle's electrical system. The ignition coil converts the vehicle's electrical system voltage into high voltage. High voltage is used to create a spark between the spark plug electrodes in the engine cylinders during the compression stroke. The low voltage or primary circuit consists of the wiring that connects the battery, ignition switch, primary winding of the ignition coil, and the electronic ignition unit. The high voltage or secondary circuit consists of the high voltage winding of the ignition coil, the central high voltage wire, the ignition distributor, the distributor rotor, the high voltage wires of the spark plugs, and the spark plugs.
The ignition coil converts the intermittent low-voltage current (+12 V) into high-voltage current to break down the air gap between the spark plug electrodes. The ignition coil is a transformer with an open magnetic circuit, which consists of an inner core and an outer ring magnetic circuit. The secondary winding, which has a large number of turns, is wound around the core. The primary winding (with a smaller number of turns) is wound on top of the secondary.
The ignition system works as follows. When voltage is applied to the primary winding of the ignition coil, a magnetic field is created in it. An electronic unit is used to turn on and off the voltage supplied to the primary winding of the ignition coil.
When the voltage on the primary winding of the ignition coil is switched off, the voltage drop of the magnetic field in the secondary winding generates high voltage, which is supplied via the ignition distributor to the spark plug of the corresponding cylinder. The voltage is then supplied again to the primary winding of the ignition coil, as a result of which the magnetic field increases and the cycle is repeated to supply high voltage to the next spark plug.
Diesel engine preheating system
Glow plugs reduce the time required to start the engine in low ambient temperatures.
The engine control unit monitors both the time it takes for the current to heat the glow plugs after the ignition is turned on and the operating time of the glow plug indicator lamp in accordance with the engine coolant temperature.
Precautions when working with electrical equipment system
When working on an electrical system, in order not to damage semiconductor devices (diodes and transistors), the following requirements must be met:
- do not disconnect the battery, alternator or any electrical connectors while the engine is running;
- when performing any work, remove the wire from the negative terminal of the battery;
- when performing electric welding work on a vehicle, turn off the alternator and electronic control device;
- do not allow the engine to run with the generator disconnected from the electrical system;
- do not check the generator's functionality by short-circuiting its output contacts to ground.