Repair methods and solutions for the failure of electric bicycle motor magnets falling off

Article from: 12-12-2020


Electric bicycles are economical, practical, easy to ride, and as non-motorized vehicles, they are favored by urban and rural residents. After rapid development in recent years, it has become quite popular. But at the same time, because it is a high-tech product that combines electromagnetic, electrochemical, electronic and mechanical technology, and the working environment varies with climate and region, uneven roads are bumpy, wind and rain are common. Sometimes users improper use, high failure rate is inevitable.
1. Fixing method of magnet and stator

Currently, the motors used on electric bicycles generally use permanent magnet DC motors. The so-called permanent magnet DC motor refers to a motor in which the inner stator of the motor uses the magnetic field generated by the permanent magnet and the energized coil of the outer rotor to generate torque and rotate. The advantage of this design is that it eliminates the need to use the excitation coil to generate the magnetic field on the stator to consume electrical energy, improves the efficiency of the motor, simplifies the structure of the motor, and reduces the manufacturing cost of the motor. This is suitable for electric bicycles that use limited energy. Reduce the working current and extend the mileage.
2. Disadvantages of resin glue fixing method

The method of using resin glue is very firm, and the magnetic steel is very strong, which can be tightly adsorbed on the stator core support. Because the working environment of the motor is very bad, it is inevitable that water or moisture will enter during the rainy weather and rain with high humidity. The stator core bracket is made of iron material, which is very easy to rust. The generated rust is on the magnet and stator iron. When the core bracket expands, the magnetic steel is opened, and the resin glue loses its due role. Only the magnetic force is used to adsorb the magnetic steel on the stator core bracket. At this time, there is the impact of turbulence and the magnetic force of the rotor. It will shift, at least the performance of the motor will decrease, and at the worst, the motor must be repaired.
3. Maintenance method

The repair method for this type of failure is to remove the motor from the electric bicycle, open the end cover, take out the stator, find the fallen or loose magnets, clean up the residual resin glue and rust, bond the magnets with resin glue, and reassemble it. Motor.

This type of failure is relatively common now, and we must consider reducing this type of failure to fundamentally solve the problem of electric bicycle magnets falling off.
4. Solution to the problem of magnetic steel falling off

Use screws to fix. Drill two holes in the magnet, and drill and tap the two holes in the corresponding position of the stator core support. Use countersunk screws to fix each magnet on the stator core support, so that no magnet will appear For the problem of falling off, we have tried to implement this idea on a motor with such a fault, because the magnet is too hard to drill holes in the magnet with ordinary drills. To adopt this solution, only the motor and the magnet manufacturer must coordinate , Reserve two holes in the production process of magnet, so the problem is solved. The possible problem with this solution is that because the magnetic steel has two more holes, it affects the magnetic induction intensity of the stator, so that the magnetic field of the stator is not as strong as before. As for the weakening, it needs to be verified and measured in practice.