Manually adjusted marking oscillation angle adjustment device for electric fan

A manually adjusted marking oscillation angle adjustment device for an electric fan, comprising a plastic marking disc, a plastic angle adjustment knob, a hollow shaft, a central shaft, and a central gear, wherein a circumferential angle of every two adjacent teeth of the central gear is equal to a circumferential angle of every two adjacent markings of the plastic marking disc;

• a plastic marking disc intermediate connection device with unique positioning connection is provided between the hollow shaft and the plastic marking disc;
• a plastic angle adjustment knob intermediate connection device with unique positioning connection is provided between the central shaft and the plastic angle adjustment knob, and the plastic angle adjustment knob intermediate connection device comprises a two-position connecting block fixedly installed on an upper end of the central shaft through a screw;
• the oscillation angle adjustment device further comprises a gear box housing, a housing cover, and a gear transmission mechanism;
• the gear transmission mechanism comprises a worm shaft gear and a large gear, and a lower end of the hollow shaft is clamped and inserted into the large gear;
• the large gear is arranged with an inner cavity, and a variable-length crank mechanism and a spring-fastener device are provided in the inner cavity, the variable-length crank mechanism comprises the central gear, a crank and an eccentric internal gear engaged with the central gear;
• a limiting cover is installed below the large gear to close the inner cavity of the large gear and arranged with a first arc limiting groove, and the crank passes through the first arc limiting groove to the outside of the large gear;
• a second arc limiting groove and a limiting block mechanism are provided between the plastic marking disc and the plastic angle adjustment knob, and an inner wall of the second arc limiting groove is provided with an opening oriented radially toward a grading marking of the plastic marking disc;
• a plastic clamping and positioning mechanism and a radial sliding-fit device are provided between the plastic marking disc and the plastic angle adjustment knob, the plastic clamping and positioning mechanism comprises a first grading concave-convex body and a positioning bump that are configured for plastic clamping and positioning;
• an outer wall of the inner eccentric gear is provided with second grading concave-convex bodies, and a circumferential angle of every two adjacent second grading concave-convex bodies is equal to a circumferential angle of every two adjacent inner teeth of the inner eccentric gear;
• a fastener of the spring-fastener device is in elastic fastening contact with a wall surface between two adjacent second grading concave-convex bodies.