Protector for combustion-supporting fan of tunnel furnace

The invention discloses a protector for a combustion-supporting fan of a tunnel furnace. The protector comprises a straight tube, a bend tube, an electromagnet, a spring and an iron baffle plate. An inlet of the bent tube is connected with an air flow outlet in a pipe wall of an inlet section of the straight tube in a sealing mode. An air outlet end of the bent tube does not intersect an air outlet end of the straight tube. The central axis of the straight tube and the central line of the bent tube are on the same vertical plane. The baffle plate is connected with the spring. The spring is connected with the electromagnet. The baffle plate moves up and down in a groove of the straight tube. A power line of the electromagnet is connected with a power supply wiring hole of the combustion-supporting fan in the controller. When the electromagnet is electrified, the lowest point of the baffle plate is lifted to the highest position of an inner cavity of the straight tube. Air blast of the fan flows through the str