What is a magnetic coupling?

Structure of magnetic coupling:

Magnetic coupling, commonly known as magnetic drive coupling, is a non-contact coupling, which generally consists of two magnets, namely, an inner magnet and an outer magnet. The two magnets are separated by an isolation cover in the middle, and the inner magnet is connected with the driven part and the outer magnet is connected with the power part. In addition to the function of damping and absorbing vibration of elastic coupling, the magnetic drive coupling is characterized by breaking the structural form of traditional coupling and adopting a brand-new magnetic coupling principle, so that force and torque can be transmitted between the driving shaft and the driven shaft without direct contact, and the dynamic seal can be changed into a static seal to achieve zero leakage. Therefore, it is widely used in occasions with special requirements for leakage. Botou Wansheng coupling

Development of magnetic coupling

Magnetic coupling is widely used in all kinds of general machinery to connect two shafts to rotate together to transmit torque and motion. The traditional coupling must transmit torque through the mutual connection between the driving shaft and the driven shaft, which has complex structure and high manufacturing accuracy, and it is easy to cause the damage of components when overloaded. Especially, when the driving shaft and the driven shaft work in two different media that need to be isolated from each other, sealing elements must be used for dynamic sealing, so there are problems such as increasing the rotation resistance to ensure reliable sealing, or leaking due to lax sealing. In addition, with the wear and aging of sealing elements, the leakage will be aggravated, especially in the system where harmful gas (harmful liquid) exists, once it leaks, it will pollute the environment and endanger life.

traditional couplings are all contact couplings, which can be divided into elastic couplings and rigid couplings according to whether there are elastic parts in them. The elastic coupling has elastic parts made of metal springs or rubber plastics, so it has the function of buffering and absorbing vibration and the ability to adapt to axis deviation. It is suitable for the occasions where it bears the impact of variable load, starts frequently and has positive and negative rotation, and it is also suitable for the occasions where the 2 axes cannot be strictly aligned. There are no elastic parts in the rigid coupling, so there is no ability to buffer and absorb vibration.

magnetic drive coupling is a non-contact coupling, which generally consists of two magnets, an inner magnet and an outer magnet. The two magnets are separated by an isolation cover in the middle, and the inner magnet is connected with the driven part and the outer magnet is connected with the power part. In addition to the function of damping and absorbing vibration of elastic coupling, the magnetic drive coupling is characterized by breaking the structural form of traditional coupling and adopting a brand-new magnetic coupling principle, so that force and torque can be transmitted between the driving shaft and the driven shaft without direct contact, and the dynamic seal can be changed into a static seal to achieve zero leakage. Therefore, it is widely used in occasions with special requirements for leakage.

principle of magnetic coupling

there are two main structures of magnetic coupling: planar magnetic drive coupling and coaxial magnetic drive coupling.

a plane magnetic drive coupling is called when the magnets are magnetized in the axial direction and the coupling poles are arranged in the axial direction.

a coaxial magnetic drive coupling is one in which the magnets are magnetized in radial direction and the coupling poles are arranged in radial direction.

now take the coaxial magnetic drive coupling as an example to illustrate its working principle. The magnetic drive coupling consists of an outer magnet, an inner magnet and an isolation cover. The inner and outer magnets are composed of permanent magnets magnetized in radial direction and opposite magnetizing directions. The permanent magnets are alternately arranged in circumferential direction with different polarities and fixed on the low-carbon steel ring to form a magnetic circuit breaker. The isolation cover is made of non-ferritic (and therefore non-magnetic) high-resistance materials, usually austenitic stainless steel. At rest, the N-pole (S-pole) of the outer magnet and the S-pole (N-pole) of the inner magnet attract each other and form a straight line. At this time, the torque is zero, as shown in Figure 3. When the outer magnet rotates under the drive of the power machine, the inner magnet is still in a static state at first due to the friction and the resistance of the driven part. At this time, the outer magnet begins to deviate from the inner magnet by a certain angle. Because of this angle, the N pole (S pole) of the outer magnet has a pulling effect on the S pole (N pole) of the inner magnet, and the N pole (S pole) of the outer magnet has a pair of the previous N pole (S pole) of the inner magnet. When the N-pole (S-pole) of the outer magnet is just between the two poles (S-pole and N-pole) of the inner magnet, the generated pushing and pulling force reaches the maximum, as shown in Figure 4, thus driving the inner magnet to rotate. In the transmission process, the isolation cover separates the outer magnet from the inner magnet, and the magnetic field lines pass through the isolation cover to transfer the power and movement of the outer magnet to the inner magnet, thus realizing the contactless sealed transmission.

Application field of magnetic coupling:

One of the successful applications of magnetic drive coupling is its combination with pump-magnetic pump. In the past, it was used as a valuable special product only when it was necessary. Now it has a wide range of applications. Most of the liquids in petrochemical, pharmaceutical, film, electroplating, nuclear power and other industries are corrosive, flammable, explosive, toxic and precious, and leakage brings waste of working liquids and environmental pollution; Vacuum and semiconductor industries should prevent the invasion of external gases; Diet, biology and medicine should ensure the purity and hygiene of the medium. Magnetic drive coupling has found its place in these fields. It can be said that magnetic pump is a big market for magnetic materials.

The magnetic drive coupling, especially the permanent magnet coupling, is applied to the valve. The valve stem does not pass through the valve cover, and the stuffing box is omitted, so it is named as the fully enclosed non-packing permanent magnet drive valve. The valve can run safely and reliably for a long time because there is no stuffing box; There is no friction torque between the valve stem and the packing, so the rotation is labor-saving; Negative pressure operation, no external air enters. All industrial valves such as globe valves, gate valves, ball valves and disc valves can be transformed into fully enclosed valves. The reaction kettle is a kind of mixed reaction equipment widely used in chemical plants. The liquid is often stirred under pressure, and the reactants have certain temperature, corrosiveness and volatility. Therefore, the sealing of the rotating shaft has become an important issue in the reaction kettle. The reaction equipment with agitator is driven by magnetic force, which not only realizes absolute sealing, but also avoids oxidation and condensation of medium. Botou Wansheng coupling co., ltd