Transmission device for unmanned aerial vehicle

A transmission system for an unmanned aerial vehicle, the unmanned aerial vehicle including

• an airframe;
• four arms, namely a first arm, a second arm, a third arm, and a fourth arm arranged on the airframe in a clockwise direction;
• propellers provided on each end of the respective arms;
• and
• an inline four-cylinder engine that drives the propellers;
• the transmission system comprising:
• a drive gear mounted on a crankshaft of the inline four-cylinder engine;
• a driven gear mounted on a clutch shaft, meshing with the drive gear;
• a bevel gear mounted on the clutch shaft via a centrifugal clutch, driving a drive shaft perpendicular to the clutch shaft;
• a base gear mounted on the drive shaft and driven by the bevel gear;
• a top gear assembly comprising:
• a main gear mounted on the drive shaft;
• a left sub-gear meshing with the main gear;
• a reverse gear meshing with the main gear;
• and
• a right sub-gear meshing with the reverse gear;
• a first bevel gear and a second bevel gear, each meshing with the left sub-gear, the first bevel gear driving the first arm and the second bevel gear driving the second arm;
• and
• a third bevel gear and a fourth bevel gear, each meshing with the right sub-gear, the third bevel gear driving the third arm and the fourth bevel gear driving the fourth arm.