Types of magnetic coupling
Before introducing the boring content（Because this is a very long article）, let’s show you the types of magnetic coupling.
Standard Coupling For Small Power (OS Series)
Standard Coupling For Big Power (OFS Series)
Torque Limited With Small Power (OX Series)
Torque Limited For Big Power (OFX Series)
Synchronous Magnetic Coupling (OTB Series)
Mining Magnetic Coupling (BX Series)
Adjustable Speed Magnetic Coupling
Drum Magnetic Coupling
What is Magnetic Coupling
What is magnetic coupling?
Magnetic coupling transmission is also called magnetic transmission, magnetic coupler or magnetic drive. It is based on modern magnetic theory and applies the magnetic force of permanent magnet materials or electromagnets to realize a new technology of contactless transmission of force or torque (power). The main difference between the magnetic coupling transmission and the magnetic coupling transmission is that a mechanical device is added on the basis of the magnetic coupling transmission.
In the current large-scale industrial production, many processes are realized under the operation of transmission, reaction, stirring, heating, cooling, absorption, cleaning, diffusion, separation, etc. The functions of conveying, switching, controlling, transforming, and adjusting must pass through A certain transmission control device is implemented. This kind of transmission control device should not only be able to operate normally with the working parts, automatically adjust the position and realize control functions, but also meet the technical requirements of flexible operation, free control, full sealing, and non-leakage and non-proliferation. If such a transmission control device can be applied in modern industrial production equipment, it will bring obvious economic benefits. In addition, there are some transmission devices in the mechanical transmission, such as input and take-out of sample transmission, load-displacement and motion, and transmission of some high-precision forces and torques, so that the transmission structure can realize the master and follower parts during the transmission process. Separating and making the motion direction or motion state complete the requirements of their respective motion trajectories under synchronous or asynchronous conditions. For these transmission forms with special requirements, if a comprehensive transmission method combining magnetic coupling transmission and mechanical transmission is used instead of The simple and complex mechanical transmission form can not only simplify the transmission device but also improve the reliability and transmission efficiency of the device operation. The magnetic coupling transmission device described here is a brand-new technology that can fully realize the combination of the magnetic coupling transmission and the mechanical transmission, and can also realize the automatic control of the moving process to a certain extent.
Application characteristics of magnetic coupling
It can convert the dynamic seal of the shaft to transmit the power into the static seal, so as to realize the zero leakage transmission of the power. Magnetic coupling transmission transmits force or torque, which is realized by using the characteristics of the magnetic field force. Magnetic coupling transmission does not require relative contact or connection of two permanent magnets. Therefore, when the driving member rotates, the driven member can be rotated at the same time under the action of the magnetic field force, and there is no need for active movement between the inside and outside of the working container. The shaft (or transmission rod) passes through the container wall to achieve the purpose of work, so that the static sealing state of the power transmission process can be achieved, and zero leakage can be completely achieved.
It can avoid the transmission of vibration and realize the smooth operation of the working machine. There is no contact between the active part and the driven part, and there is no rigid connection problem. The active part will not be directly transmitted to the driven part when there is a sudden change or vibration, and the active part will not be affected when the driven part has sudden change or vibration. Therefore, the transmission of vibration or sudden change can be avoided, and the smooth operation of the working machine can be realized.
It can realize overload protection during the operation of working machinery. Under the condition that there is no rigid connection between the driving part and the driven part. The working torque can be appropriately increased in the design to increase the sense of safe movement. When the load of the driven part increases suddenly and the overload is too large, the two parts may slip out. The transmission of torque avoids the danger of the follower being easily damaged when it does not work normally (such as the driving shaft lock, sweeping, etc.), and also protects the motor.
Compared with rigid couplings, it is more convenient to install, disassemble, debug and maintain. The magnetic coupling transmission device is relatively simple in structure, and there is a gap between the driving part and the driven part, which is easy to install, disassemble and maintain, which can not only reduce the difficulty and labor intensity of equipment maintenance but also improve the working efficiency of the equipment.
Easy transmit power
The movement mode of the magnetic coupling transmission transmits the power. When the magnetic coupling transmission transmits power, it can perform the linear motion, rotary motion, and helical compound motion that combines linear motion and rotary motion; the combination of magnetic coupling transmission and different mechanical structure designs can realize orderly motion in three-dimensional space, and some other differences. Movement in a certain way or displacement at a certain distance and directional movement at any angle of rotation.
It can purify the environment, eliminate pollution and realize civilized production. Environmental protection is a basic national policy to achieve sustainable economic development. It is developed by applying magnetic coupling transmission technology in production. Like the process of petroleum, chemical, pharmaceutical, offshore oil well operations, non-ferrous metal smelting, wet mineral processing, food and other industries. The magnetic coupling pump can completely avoid the leakage of corrosive media such as toxic, harmful, flammable, explosive, strong acid, strong alkali, etc.. Which not only protects the safety of operators but also prevents environmental pollution.
Problems with magnetic coupling
Magnetic fields can disturb the surrounding equipment
The existence of a magnetic field in a certain space interferes with the surrounding environment, which limits the use of certain instruments and equipment that should avoid magnetic field interference.
Hysteresis in the starting process
During the start-up operation, the magnetic rotation angle of the active magnetic rotor and the magnetic rotation angle of the driven magnetic rotor have a rotation angle difference and change with time; in normal operation, the magnetic field force-torque also changes when the load torque changes, so that it can be Lead to misalignment between the master and the slave. Therefore, the use of magnetic coupling in devices requiring precision is limited.
This is mainly because the metal material is used as the isolation sleeve. Since the metal isolation sleeve is in a sinusoidal alternating magnetic field, the magnetic field not only changes in size but also in direction, resulting in eddy currents induced in the metal isolation sleeve on the section perpendicular to the direction of the magnetic field lines. current. The generation of this eddy current can not only weaken the working magnetic field, reduce the transmission torque, but also generate eddy current loss and release energy in the form of Joule heat, thus consuming part of the transmission power of the main shaft and reducing the transmission efficiency.
Features of magnetic coupling
In addition to the conventional magnetic coupling transmission, the magnetic coupling transmission has the dynamic seal that can convert the shaft to transmit power to a static seal, which realizes smooth operation, avoids vibration transmission, realizes overload protection of the working device during operation, and is connected with the rigid coupling. In addition to a series of characteristics such as easy installation and debugging, disassembly and maintenance, purification of the environment, elimination of pollution, and realization of civilized production, it also has the characteristics of more power transmission methods and complete structure and functions.
① The magnetic coupling transmission technology is changed from a simple two-dimensional plane circular motion to a four-dimensional space helical compound motion, which well solves the control technology of the maximum rotation angle and rotation range, and localizes the complex helical compound motion in an effective space.
② The magnetic circuit design and the mechanical structure design are organically combined into a moving whole to complete the complex motion trajectory; it breaks through the traditional mechanical linkage mechanism of the transmission system, and realizes the dynamic static seal well.
The helical motion operates in three-dimensional space. It can be said that it superimposes the axial propulsion displacement and the time factor on the basis of the plane circular motion, and at the same time solves the quantitative relationship between the rotation angle and the propulsion displacement (both are functions of time); The vector relationship between rotational torque and axial propulsion is solved.
③ The compact arrangement, symmetrical arrangement and asymmetric arrangement of the magnetic poles should be reasonably arranged so that the coupled two groups of separated components can perform relative motion in two-way relative shapes that are correlated, synchronous and asynchronous.
④ Exploring universally applicable laws for the operation of arbitrary conditions and arbitrary states.
Classification of magnetic coupling
Magnetic coupling is classified as follows according to their different classification methods.
Principle of magnetic coupling,
it can be divided into three types: synchronous type, eddy current type, and hysteresis type.
If the rotational speed of the driving element is n1, the rotational speed of the driven element is n2, and the transmitted torque is T, the maximum torque that can be transmitted is Tmax, and the intrinsic coercive force of the permanent magnet is JHc1. Permanent magnets are used in both parts, and when the coercive forces in the two parts are equal and large enough, under the condition of n1=n2 and T < Tmax, the magnetic coupling drive is called synchronous magnetic coupling.
Eddy current type
If the main part and the driven part are two parts, the active part is a conductor, and the conductivity σ is not equal to zero, the driven part is a permanent magnet, and the magnetic coupling drive is called eddy current.
If the active element is a hysteresis material, the intrinsic coercive force is jHC1, the driven element is a permanent magnet, and the intrinsic coercive force is jHC2, jHC1 > jHC2; when T < Tmax, n1 = n2, there is no energy loss (hysteresis loss), the magnetic coupling actuator is called hysteresis at this time.
it can be divided into linear motion, rotary motion, compound motion and some other special motions.
Linear motion magnetic coupling actuator
Its structure is shown in Figure 1.1. When the driving part moves in a straight line, the driven part also moves in a straight line. The active part is annularly arranged on the outside of the isolation sleeve, and is usually composed of parts such as an outer magnet, a magnetic shield, an outer cover, and a transmission part. The follower is also annular, which is composed of inner magnets, isolation sleeves, magnetic circuits, fasteners, transmission parts and other parts.
Rotary kinematic magnetic coupling
Its structure is shown in Figures 1-2. When the outer magnetic rotor 3 rotates by the motor, the inner magnetic rotor 7 also rotates accordingly. The driving part and the driven part of this magnetic coupling transmission are composed of a rotating shaft, a permanent magnet, an isolation sleeve, a magnetic circuit, and a bearing. , bearing housing and other components.
Compound motion magnetic coupling
Its structure is more complicated, but its shape is basically close to the linear motion magnetic coupling. When the driving element of compound motion magnetic coupling performs compound motion of linear and rotation, the driven element also performs compound motion at the same time.
A magnetic coupling that uses permanent magnets for compound driving, as shown in Figure 1-3. This structure can not only transmit linear motion and rotation, but also transmit the motion of the combination of the two motions, such as helical motion and clamping motion. The linear transmission mechanism is similar. Because the outer magnetic pole not only pushes the inner magnetic pole to do linear motion but also rotates, and the transmission rod still needs to do linear motion on the ball bearing guide rail, a rotating shaft should be installed in the center of the transmission rod to complete the rotation.
Figure 1-2 Schematic diagram of the structure of the rotary motion magnetic coupling
1—Driven shaft; 2—Isolation sleeve; 3—External magnetic rotor; 4—Permanent magnet for external magnetic rotor;
5—Permanent magnets for internal magnetic rotor; 6—Working air gap; 7—Internal magnetic rotor; 8—Drive shaft
The sample holder can be fixed on one end of the rotating shaft. When it rotates, it rotates with the rotating shaft, and the transmission rod does not move. When it moves linearly, it moves with the rotating shaft together with the transmission rod. The coaxiality and parallelism of the movement center line and the pipe center line of the transmission rod can be adjusted by rollers, and the guide rail frame is integrated with the flange, which is convenient for overall disassembly and assembly. One end of the sealing tube is welded on the flange, and a ruler is installed outside the sealing tube to display the moving distance. The outer magnetic pole is equipped with a dust-proof pad and a corner stopper. When no rotation is required, the stopper clamps the ruler, and the outer magnetic pole does not If there is an angle scale on the stopper, the size of the rotation angle can be measured; loosen the stopper, the magnetic pole can rotate at any angle, and if the ruler is equipped with a positioning clip, the reciprocating stroke of the transmission rod can also be fixed. The other end of the sealing tube is welded with a plug, and a bracket can be installed on the plug to hold the sealing tube and prevent the sealing tube from becoming a cantilever beam.
Figure 1-3 Schematic diagram of the structure of the composite motion magnetic coupling transmission device
1—rolling bearing; 2—cylindrical isolation sealing sleeve; 3—outer rolling bearing; 4—outer magnetic rotor; 5—inner magnetic rotor
The magnetic coupling transmits special motions.
It can also be realized by a combination of the electromagnetic field and permanent magnetic field. This structure can transform the transmission of reciprocating motion into intermittent rotational motion.
As shown in Figure 1.4. In figure (a), the solenoid coil drive is placed on component 1 in the sealed container, and the ratchet mechanism can be used to ensure the intermittent rotation of the ratchet wheel 2. In figure (b), when electromagnet 5 attracts the armature 6, the ratchet wheel 4 is rotated by an angle through the lever 3 and the pawl, and the reciprocating motion of the armature 6 can be converted into a rotary motion.
The structures shown in Figures 1-5 can be used when periodic oscillations need to be delivered into the sealed container. This magnetic coupling swing structure places the electromagnetic coil in the atmosphere, and swing member 2 is realized through an isolation sleeve.
According to the structure of magnetic coupling,
it can be divided into two types: Drum type magnetic coupling and Disc type.
Figure 1-4 Schematic diagram of the sealing structure that uses electromagnetic force to change reciprocating motion into intermittent rotating motion
1—transmission rod; 2, 4—ratchet; 3—lever; 5—electromagnet; 6—armature
Figure 1-5 Magnetic coupling swing seal structure
1—electromagnetic coil; 2—oscillating piece; 3—iron core; 4—sealing plate
The layout of permanent magnets
it can be divided into two types: gap dispersion type and combined pull-push type.
Gap Distributed Magnetic Coupling
The arrangement of permanent magnets is shown in Figure 14. When arranging the permanent magnets, there is a certain distance between the permanent magnets to avoid the short circuit of the magnetic field interacting between the two permanent magnets or the demagnetization caused by the action of the same pole magnetic field.
Figure 1-6 Arrangement of permanent magnets of gap-dispersed magnetic coupling
Combined pull-push magnetic coupling
The arrangement of permanent magnets is shown in Figure 1.7. It consists of permanent magnets with high coercivity closely arranged with each other. Its main features are magnetic field concentration, large transmission torque and small relative volume. It is a new type of magnetic circuit arrangement that is most commonly used in magnetic coupling.
Figure 1-7 Arrangement of permanent magnets of combined pull-push magnetic coupling drive