The magnet and impeller of the brushless DC magnetic drive pump are molded into an integral part to form the rotor of the motor. There is a shaft sleeve directly molded in the middle of the rotor, which is fixed in the housing through a high-performance ceramic shaft. The stator and circuit board of the motor are sealed in the pump body with epoxy resin glue. There is a thin wall isolation between the stator and the rotor, which does not need to be matched with traditional mechanical shaft seals, so it is completely sealed. The torque of the motor is generated by the magnetic field after the coil on the silicon steel sheet (stator) is energized to drive the permanent magnet (rotor) to work. Magnets are magnetized in n (n is even) order to form a complete coupling magnetic system. When the magnetic pole generated by the stator coil is opposite to the magnetic pole of the magnet, that is, the displacement angle between the two magnetic poles Φ= 0, at this time, the magnetic energy of the magnetic system is the lowest; When the magnetic poles rotate to the opposite of the same pole, that is, the displacement angle between the two magnetic poles Φ= 2 π/n, at this time, the magnetic energy of the magnetic system is maximum. After removing the external force, because the magnetic poles of the magnetic system repel each other, the magnetic force will make the magnet return to the state with the lowest magnetic energy. The magnet then moves and drives the magnetic rotor to rotate.

Brushless DC water pump uses electronic commutation without using carbon brushes. The magnet rotor and stator silicon steel sheets have multistage magnetic fields. When the magnet rotor rotates an angle relative to the stator, it will automatically change the direction of the magnetic pole, making the rotor always maintain the same level of repulsion, so that the brushless DC magnetic isolation pump has a higher speed and efficiency. PW-NH-200PX1.jpg

The stator and rotor of the magnetic isolation pump are completely isolated, which completely avoids the liquid leakage problem existing in the traditional motor brushless DC pump. Moreover, it can be fully submerged and waterproof, effectively improving the service life and performance of the pump.

Compositional decomposition

Brushless DC water pump (magnetic isolation pump) consists of pump body (isolator), motor stator, shaft, bearing and rotor blade (magnet and impeller):

Magnet (NdFeB permanent magnet)

The permanent magnet made of rare earth permanent magnetic materials has a wide working temperature range (- 45-400 ℃), high coercivity, good anisotropy in magnetic field direction, and no demagnetization when the same poles are close to each other. It is a good magnetic field source.

Isolator

When the metal isolation sleeve is used, the isolation sleeve is in a sinusoidal alternating magnetic field, and eddy current is induced on the section perpendicular to the magnetic line of force and converted into heat. The expression of eddy current is: Pe eddy current; K-constant; N - rated speed of pump; T - magnetic transmission torque; F - pressure in the spacer; D - inner diameter of spacer sleeve; - the resistivity of the material; - The tensile strength of the material. After the pump is designed, n and T are given by the working conditions, and only F and D can be considered to reduce eddy current. The isolation sleeve made of non-metallic materials with high resistivity and high strength is very effective in reducing eddy current.