A three-phase alternator with electromagnetic excitation, a diode rectifier unit and a built-in voltage regulator is installed on a Renault / Dacia Sandero car
The generator is driven by a V-ribbed auxiliary drive belt from the crankshaft pulley.
The generator consists of a rotor, a stator, a rectifier unit, a brush assembly with a voltage regulator and two covers.
A pulley is mounted on the rotor shaft. To cool the parts of the generator, ventilation holes are made in its covers, and an impeller is made on the rotor from the side of the front cover.
The stator has a three-phase winding connected by a "star".
The winding leads are soldered to the rectifier unit.
The rectifier unit is installed under the generator casing together with the brush assembly and voltage regulator.
The rotor has an excitation winding, the leads of which are soldered to two slip rings.
The generator rotor shaft rotates on two ball bearings.
The front bearing is pressed into the front cover of the generator, and the rear bearing is pressed onto the rotor shaft and held on the rear cover of the generator.
Voltage regulator - non-contact, electronic, combined with a brush assembly in a common non-separable housing.
Brushes - carbon, spring-loaded.
Possible generator malfunctions, causes and remedies
- Reason
Remedy
When the ignition is switched on, the battery discharge warning light does not light up:
- Broken wire between the generator, the ignition switch and the signal lamp
Fix the break
- Signal lamp burned out
Replace the lamp
- Faulty generator
Replace or repair the generator
Battery discharge warning light does not go out after starting the engine:
- Weak alternator drive belt tension
Adjust belt tension
- Faulty generator diode bridge
Repair the generator
- Closing the wire between the generator and the signal lamp to ground
Insulate the wire
Battery discharge warning light on when the ignition is off:
- Faulty generator
Replace or repair the generator
The generator does not charge the battery:
- Oxidation of battery terminals
Clean, secure, and lubricate wire ends
- Faulty battery
Replace battery
- Weak alternator drive belt tension
Adjust belt tension
- Faulty generator (diode bridge)
Repair the generator
Battery is being recharged:
- Faulty generator (voltage regulator, diode bridge)
Repair the generator
- Increased voltage drop in the generator-battery circuit
Check, clean, tighten or replace the contact connections in the ignition switch, fuses, connectors; check the ground connection of the alternator housing.
Removing and installing the generator
Let's consider the removal process using the example of a car with a complete set with a K7J and K7M engine, with a K4M engine, the difference is only in the generator mounting.
Removing the accessory drive belt (Checking and replacing the Renault Sandero auxiliary drive belt)
Disconnect the wire block from the generator by wringing out the block lock with a screwdriver
Unscrew the nut securing the wire end
Disconnect the wire from the generator output
We remove the front bumper (article - Removing the fender liner and bumpers of a Renault Sandero car)
We unscrew the air conditioning compressor mounting bolts onera and, without disconnecting the pipelines, we take the compressor to the side
We unscrew the bolts of the power steering pump, do not disconnect the pipeline and hose from the pump
Using a screwdriver, remove the harness holder from the attachment bracket
We unscrew the three bolts securing the generator
We set aside the power steering pump so that the hose does not interfere with the extraction of the generator, and remove the generator.
Install parts in reverse order. We tighten the generator mounting bolts with a torque of 21 Nm (2.1 kgf.m)
Generator repair
Let's look at how to replace the voltage regulator and rectifier unit.
If the rotor or stator winding fails, the generator must be replaced as an assembly.
Remove the generator as described above
Unscrew the screw securing the back cover
Unscrew the two nuts
Remove the back cover of the generator
We unscrew the three screws securing the voltage regulator
Remove the voltage regulator
Check the ease of movement of the brushes in the brush holder and their protrusion.
If the protrusion "A" of the brushes from the holder is less than 5 mm, we change the voltage regulator assembly with the brush holder
We check the resistance of the rotor winding with a tester in the ohmmeter mode by connecting it to slip rings.
If the ohmmeter shows infinity, then there is a break in the windings and the rotor must be replaced (it is better to replace the generator)
Checking the diodes of the rectifier unit.
We connect one wire to the mass of the rectifier unit, and the second to the output of the diode
Then swap the wires. The diode should only conduct current in one direction.
If the diode passes current in both directions or does not pass at all, then it is faulty.
We check all the valves in this way.
To replace the rectifier unit, open the twelve contacts with a screwdriver
We unscrew the two fastening screws and remove the rectifier unit
Assemble the generator in reverse order.