To ensure that the rotor can rotate freely in the stator cavity, an air gap must be maintained between the rotor core and the stator core. Although there is no direct electromagnetic connection between the rotor and the stator, when the stator winding is energized, similar to the principle of a transformer, there is an electromagnetic connection between the rotor and the stator, realizing thus the function of energy conversion between electrical energy. and mechanical energy.
The size of the air gap has a significant impact on asynchronous performance and operational reliability. Excessive air gap will greatly increase the magnetic resistance, thereby increasing the excitation loss, the excitation current will also increase, the power factor of the motor will also decrease, and the performance of the motor will deteriorate. In order to reduce the excitation current and improve the power factor, the air gap should be minimized. However, if the air gap is too small, the harmonic magnetic field of the air gap will increase, the parasitic losses and motor noise will increase, and the maximum torque and starting torque will decrease. At the same time, if the air gap is too small, it is easy for the running rotor and stator to collide, resulting in sweeping phenomenon, making it difficult to start, thereby reducing operating reliability and causing assembly difficulties. Generally, the air gap of small-sized asynchronous motors is between 0.25 and 1.5 mm, and that of medium-sized asynchronous motors is between 0.75 and 2 mm.
The gap between the motor stator and rotor was determined during the motor production process. Unless the gap becomes larger due to various reasons such as rotor sweeping during use, this is usually impossible.
The large current of the motor peut be due to many reasons.
1: Positioning magnet deviation, treatment method: re-gluing;
2: The gap between the carbon brushes is uneven, treatment method: correct the carbon brush gap;< /p> >
3: There is a short circuit between the positive and negative poles of the battery Solution: eliminate the short circuit
4: Short circuit between the turns Solution: Replace the wiring. ;
5: The collector segment is shorted. Solution: Clean and grind the collector segment;
6: The fit between shaft and bearing is too tight. Grind the tree;
7: Electric The vehicle starts from zero, solution: try to avoid it while driving
8: The load is large or the vehicle has high driving resistance, solution: human assistance.