Maintenance of Daewoo generator in Korea;

1, stator assembly

Common faults of stator assembly include winding burning, phase-to-phase short circuit, turn-to-turn short circuit and winding grounding.

By comparing the color changes of the paint film on the winding appearance, the burning loss, interphase short circuit and turn-to-turn short circuit of the component can be preliminarily confirmed. The unbalanced resistance of three-phase winding should be measured by high-sensitivity bridge or accurately identified by turn-to-turn short circuit instrument.

Check the grounding fault of winding with multimeter resistance.

Cause analysis of 1. 1

(1) Long-term overload operation, especially in high temperature season;

(2) The paint film is damaged during insert molding;

(3) Impregnation insulation is damaged;

(4) Oil pollution and dust block the air duct;

(5) The position of the motor air inlet is too close to the engine air outlet;

(6) Thermal insulation will naturally age if it is used for too long;

(7) Cleaning and drilling the stator and rotor.

(8) The battery is "aged" and short-circuited internally.

1.2 prevention

(1) Avoid the position where the generator directly faces the outlet of the engine exhaust pipe, and install the heat insulation board when the distance is less than 40cm;

(2) Keep the generator clean, regularly blow off the internal dust with compressed air, and keep the air duct unblocked;

(3) The tension of the drive belt should be appropriate;

(4) It is forbidden to modify and install the electric load;

(5) Ensure that the tightening torque of the mounting bolts meets the requirements, and regularly check whether the connecting bolts are loose.

2. Rotor assembly

The main failure forms of rotor assembly are: lead-out wire disconnected without excitation power generation, abnormal wear of collector ring and brush, and poor contact, which are generally easy to check by visual inspection and multimeter resistance detection. The rotor windings of individual generators are seriously burned or even the skeleton melts, which is less likely to cause defects and hidden dangers of the rotor assembly itself. Therefore, we should focus on investigating the circuit and usage of the charging system.

2. 1 Cause analysis

(1) Long-term vibration fatigue fracture occurred at the lead-out weld of the rotor;

(2) The clearance between the yoke and the spool leads to the lead wire loosening and breaking;

(3) When the regulating voltage rises abnormally, when the regulator is damaged and load rejection occurs at the same time, it is easy to form serious winding burning loss in a short time;

(4) The surface of the slip ring is greasy, the brush and slip ring are excessively worn and poorly connected, and the generator with pump is prone to such failures;

(5) After the engine is "turned off", the ignition switch is not turned off in time and the rotor coil is burned.

2.2 Prevention

(1) When the motor is disassembled for inspection, once a gap is found in the bobbin, reinforcement measures must be taken immediately. Polyester paint or epoxy glue can be used to reinforce joint filling, and users should be reminded in time to check whether the motor installation is firm and reliable.

(2) When oil seeps into the motor, the oil on the slip ring and brush surface should be removed immediately to eliminate the source of leakage. If grooves have been formed on the slip ring surface, the surface should be trimmed or polished in time, but it should be polished with coarse sandpaper, and the carbon brushes and springs that have formed serious wear should be replaced in time;

(3) Turn off the ignition switch in time after the engine flameout;

(4) When the regulated voltage rises abnormally, the reason should be investigated immediately to make the voltage return to normal.

3. Rectifier bridge components

Rectifier bridge fault accounts for a large part of generator fault. Rectifier diode burn-out, lead desoldering and broken, and assembly solder joint virtual welding are three common failure modes. Generally, faults can be eliminated by visual inspection and multimeter resistance measurement. There is no obvious abnormality in the appearance of partial fault rectifier bridge and multimeter inspection, but the generator performance has shown "two-phase" characteristics. At this time, it is necessary to test the diode performance and forward voltage drop with the help of a special test instrument for rectifier diodes, so as to correctly judge whether there are hidden dangers in rectifier tubes.

3. 1 Cause analysis

The causes leading to the failure of rectifier bridge are complicated. In addition to the manufacturing defects in the subsequent manufacturing of the die and the rectifier bridge, the service state of the generator, especially the current intensity, environmental vibration, temperature stress intensity and other factors are closely related, which is also an important reason why the rectifier bridge has become the main failure mode of the generator.

(1) The regulator is damaged and the regulating voltage rises;

(2) Long-term overload of generator in high temperature environment;

(3) The ambient temperature at the air inlet is too high;

(4) The motor has resonance and jitter;

(5) short circuit of electrical equipment;

(6) The water and sediment of the motor affect the normal heat dissipation;

(7) The belt tension is too loose.

3.2 Prevention

(1) For vehicles with increased electric load installed and modified, it is necessary to confirm whether the generator power matches in time, and replace the generator and connecting cable with the same power;

(2) Once the regulating voltage is found to be too high, check it in time;

(3) Always check whether there is any damage or short circuit on the electrical equipment lines, and eliminate hidden dangers in time;

(4) Use fuses that meet the requirements and specifications;

(5) Metal objects falling into the motor must be taken out in time;

(6) avoid causing resonance and jitter of the motor;

(7) Pay attention to control electricity consumption in hot season;

(8) The air inlet of the generator is far away from the air outlet.

4. Regulator

The built-in regulator of integrated generator in our company adopts hybrid integrated single-function electronic regulator, and the regulator shell is magnetic field "F".

The main failure modes of the voltage regulator are "Darlington" tube breakdown and overload burning. The multimeter "ω× 100" can be used to check the regulator, and the resistance change between the "D+-F" and "F-E" pins can be identified.

4. 1 Cause analysis

The breakdown of (1) voltage regulator mainly means that the voltage regulator is damaged by transient peak and surge voltage. The resistance value of "F-E" pin detected by multimeter ω× 100 will be significantly higher than the normal value, but in severe cases, it will form a short circuit, resulting in the burning of the shell, molten hole, Darlington tube and "E" pin. This kind of voltage surge and peak value is mainly caused by various kinds of electronic interference during vehicle operation, especially the sudden and continuous "load rejection" between the battery and the high-power electric load caused by various reasons.

(2) Another failure mode of the regulator is overload burning. Use multimeter Ω×100 to detect the change of resistance at "D+-F" and "F-E" and remove the fault. In severe cases, the resistance value cannot be detected, indicating that the internal welding wire of the regulator is burned by overcurrent. The overload of the regulator is caused by the short circuit of the rotor coil, the reverse polarity of the battery and the grounding short circuit of the regulator housing.

4.2 Prevention

(1) Avoid the short circuit caused by the direct overlap between the regulator housing and the back cover, and avoid the short circuit caused by the overlap between the collector rings, especially for the 28V regulator, even if it is touched for a short time, it will cause the regulator to burn out.

(2) Pay attention to the polarity when connecting the battery. Even if the polarity is reversed instantly, the parasitic diode in the Darlington tube in the regulator will burn out immediately.

(3) Always check whether the line connectors are firmly connected, especially the battery cable connectors, various load switches and load fuses. If poor contact is found, replace them immediately.

(4) In case of "load shedding", line inspection shall be conducted immediately to prevent continuous "load shedding".

5. Vacuum pump

The main failure forms of vacuum pump are pumping failure and lubricating oil leakage. Serious leakage will cause generator burning, which should be paid great attention to.

5. Cause analysis of1

(1) Suction failure is generally caused by rotor blade fragmentation. The oil circuit and oil tank are not cleaned for a long time, and metal chips and rust are mixed in lubricating oil and enter the vacuum pump, which is the main factor inducing blade fragmentation.

(2) The one-way valve is damaged and leaked, which leads to the decrease of vacuum degree.

(3) The air leakage of the pipe joint leads to the decrease of vacuum degree.

(4) The aging of vacuum pump sealing ring leads to leakage.

(5) Cracks in the vacuum pump shell castings lead to leakage.

(6) Wear of oil seal lip leads to leakage.

5.2 Prevention

(1) If the brake booster is found to be weak, check the pipe joint of the vacuum pump booster system in time to eliminate the hidden danger points that lead to the decrease of vacuum degree.

(2) It is very important to clean the oil circuit, oil tank and oil pump regularly to keep the lubricating oil clean and prevent the blade from breaking.

(3) Ensure that the motor is firmly installed and fixed, which is closely related to the eccentric wear of the oil seal.