The Characteristics And Advantages Of Magnetic Pump Structure

The magnetic pump will arrange the magnet (n is an even number) on the inner and outer magnetic rotor of the magnetic drive according to the rule, so that the magnet parts form a complete coupling magnetic system with each other. When the inner and outer magnetic poles are opposites, that is, the displacement Angle between the two magnetic poles Φ = 0, the magnetic energy of the magnetic system is the lowest. When the magnetic pole rotates to the opposite pole, that is, the displacement Angle between the two magnetic poles Φ = 2π/n, 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 restore the magnet to the lowest magnetic energy state. The magnet then moves, driving the magnetic rotor to rotate.
Structural characteristics
1. Permanent magnet pump valve
Permanent magnets made of rare earth permanent magnet materials have a wide operating temperature range (-45-400℃), high coercivity, good anisotropy in the magnetic field direction, and no demagnetization occurs when the homopolar is close, so they are a good magnetic field source.
2. Isolate sleeve pump valve
In the case of metal isolating sleeve, the isolating sleeve is in a sinusoidal alternating magnetic field, and the eddy current is induced and converted into heat on the section perpendicular to the direction of the magnetic field line. The expression of eddy current is: where Pe- eddy current; K - constant; n - rated speed of the pump; T-magnetic driving torque; F- Pressure in spacer sleeve; D- inner diameter of spacer sleeve; The resistivity of a material; - Tensile strength of the material. When the pump is designed, n and T are given by the working condition, and the eddy current can only be considered from F and D. The use of high resistivity, high strength non-metallic materials to make the isolation sleeve, in the reduction of eddy current effect is very obvious.
3. Control of cooling lubrication flow
When the pump is running, a small amount of liquid must be used to wash and cool the annular gap area between the inner magnetic rotor and the isolation sleeve and the friction pair of the plain bearing. The flow rate of the coolant is usually 2%-3% of the designed flow rate of the pump, and the annular gap area between the inner magnetic rotor and the isolation sleeve generates high heat due to eddy currents. When the cooling lubricant is not enough or the flushing hole is not smooth and blocked, the medium temperature will be higher than the working temperature of the permanent magnet, so that the internal magnetic rotor will gradually lose magnetism and the magnetic drive will fail. When the medium is water or water-based liquid, the temperature rise in the annular gap region can be maintained at 3-5℃. When the medium is hydrocarbon or oil, the temperature rise in the annular gap region can be maintained at 5-8℃.
4. Plain bearings
The materials of magnetic pump sliding bearings are impregnated graphite, filled with polytetrafluoroethylene, engineering ceramics, etc. Because engineering ceramics have good heat resistance, corrosion resistance and friction resistance, the sliding bearings of magnetic pump are mostly made of engineering ceramics. Because the engineering ceramics are very brittle and the expansion coefficient is small, the bearing clearance should not be too small to avoid shaft holding accidents.
Since the sliding bearings of the magnetic pump are lubricated by the medium transported, different materials should be selected to make bearings according to different media and working conditions.
5. Protective measures
When the driven parts of the magnetic drive are running under overload or the rotor is stuck, the main and driven parts of the magnetic drive will automatically slip off to protect the machine pump. At this time, the permanent magnet on the magnetic drive will produce eddy loss and magnetic loss under the action of the active rotor alternating magnetic field, resulting in the temperature of the permanent magnet rising and the slippage failure of the magnetic drive.
Advantages of magnetic pump
Compared with centrifugal pumps using mechanical seals or packing seals, magnetic pumps have the following advantages:
1. The pump shaft is changed from a dynamic seal to a closed static seal, completely avoiding medium leakage.
2. No need for independent lubrication and cooling water, reducing energy consumption.
3. The coupling drive becomes synchronous drive, without contact and friction. With low power consumption, high efficiency, and damping damping, the effect of motor vibration on the pump and pump cavitation vibration on the motor is reduced.
4. When overloaded, the inner and outer magnetic rotors are relatively slip-off, which has a protective effect on the motor and pump.