Working Principle Of Magneto

The most basic working principle of a magneto is that a permanent magnet rotates in the iron core, and the primary coil on the iron core induces an electromotive force (referred to as the primary potential). When the circuit breaker contacts close, a current (referred to as the primary current) is generated. When the circuit breaker contacts suddenly open and cut off the primary current, the secondary coil induces a relatively high electromotive force (referred to as the secondary potential), causing the spark plug to ignite. In order to obtain the strongest spark plug ignition, the maximum secondary potential should be obtained; In order to obtain the maximum secondary potential, the circuit breaker contact should close when the primary potential is zero and open when the primary potential is maximum.
When does the primary potential reach its maximum? The moment when the primary potential reaches its maximum should be when the pole of the permanent magnet rotates through a neutral position of 80 ° -100 °. This angle is called the "position angle", which ensures that the correct installation position of the circuit breaker contact relative to the cam can obtain the correct position angle. This requirement can be met by aligning the installation marks. For example, when assembling a C210 type magneto, the bottom plate of the circuit breaker should be aligned with the two opposing notches on the casing, and the pointer on the circuit breaker should be aligned with the notches on the cam; When assembling the C244 type magneto, the markings on the large and small transmission gears, the casing, and the bottom plate of the circuit breaker should be aligned separately.
As for the requirement that the circuit breaker contact should close when the primary potential is zero, as long as the position angle is correct and the contact gap is adjusted to the specified value, it can be met. Of course, adjusting the contact gap to the specified value is not only to meet this requirement, but also to ensure that the spark is not too large when the contact is opened, avoiding premature erosion of the contact.