Gear Pump Magnetic Coupling

Permanent Magnetic coupling is a coupling that transfers torque from one shaft but using a magnetic field rather than a physical-mechanical connection.

While all magnetic couplings use the same magnetic properties and basic mechanical forces, there are two types that differ by design.

The two main types include:

Disc-type couplings featuring two face-to-face disc halves embedded with a series of magnets where torque is transferred across the gap from one disc to the other
Synchronous-type couplings such as permanent magnet couplings, coaxial couplings and rotor couplings where an internal rotor is nested inside of an external rotor and permanent magnets transfer torque from one rotor to the other

In addition to the two main types, magnetic couplings include spherical, eccentric, spiral, and nonlinear designs. These magnetic coupling alternatives aid in the use of torque and vibration, specifically used in applications for biology, chemistry, quantum mechanics, and hydraulics.

In the simplest terms, magnetic couplings work using the fundamental concept that opposite magnetic poles attract. The attraction of the magnets transmits torque from one magnetized hub to another (from the driving member of the coupling to the driven member). Torque describes the force that rotates an object. As external angular momentum is applied to one magnetic hub, it drives the other by transmitting torque magnetically between the spaces or through a non-magnetic containment barrier such as a dividing wall.

The amount of torque generated by this process is determined by variables such as:

Working temperature
The environment in which processing occurs
Magnetic polarization
Number of pole pairs
Dimensions of pole pairs, including gap, diameter, and height
Relative angular offset of the pairs
The shift of the pairs

Depending on the alignment of the magnets and discs or rotors, the magnetic polarization is radial, tangential, or axial. Torque is then transferred to one or more moving parts.

Magnetic couplings are most often used for liquid pumps and propeller systems since a static, physical barrier can be placed between the two shafts to separate the fluid from the motor operating in air. Magnetic couplings preclude the use of shaft seals, which eventually wear out and fail from the sliding of two surfaces against each other. Magnetic couplings are also used for ease of maintenance on systems that typically require precision alignment when physical shaft couplings are used since they allow a greater off-axis error between the motor and driveshaft.
Magnetic Coupling for Gear Pumps