The magnetic coupling consists of an outer magnet, an inner magnet and a spacer. The inner and outer magnets are composed of permanent magnets that are magnetized in the radial direction and opposite in magnetization direction. The permanent magnets are alternately arranged in the circumferential direction with different polarities, and are fixed on the low carbon steel steel ring to form a magnetic circuit breaker. The spacer is made of a non-ferritic high-resistance material, generally austenitic stainless steel. In the stationary state, the N pole (S pole) of the outer magnet and the S pole (N pole) of the inner magnet attract each other and are in a straight line, and the torque is zero at this time.

When the external magnet rotates under the driving of the power machine, the inner magnet is still in a static state due to the frictional force and the resistance of the transmission member. At this time, the outer magnet starts to be offset from the inner magnet by a certain angle, due to the existence of this angle. The N pole (S pole) of the outer magnet has a pulling action on the S pole (N pole) of the inner magnet, and the N pole (S pole) of the outer magnet has a push on the front N pole (S pole) of the inner magnet. The role of the inner magnet has a tendency to follow the rotation, which is the working principle of the magnetic coupling of the magnetic coupling. When the N pole (S pole) of the outer magnet is located between the two poles (S pole and N pole) of the inner magnet, the generated pushing force is maximized, thereby driving the inner magnet to rotate. During the transmission process, the spacer separates the outer magnet from the inner magnet, and the magnetic flux passes through the spacer to transmit the power and motion of the outer magnet to the inner magnet, thereby achieving a contactless seal transmission.