Characteristics and working principle of harmonic gear transmission

Characteristics and working principle of harmonic gear transmission
Harmonic gear transmission is a new type of mechanism that relies on elastic deformation movement to achieve transmission. It breaks the mode of mechanical transmission that uses rigid member mechanisms. It uses a flexible member to achieve mechanical transmission, thereby obtaining a series of other transmission mechanisms. Special functions that are difficult to achieve have been widely used in such areas. But it also brings special problems that must be solved in the design.
Principle: The harmonic gear transmission system consists of three basic components, as shown in the figure: rigid wheel 1 (Circular Spline), flexible wheel 2 (Flexspline) and wave generator 3 (Wave Generator). The principle of harmonic gear transmission is that in the flexible gear component, through the action of the wave generator, a moving deformation wave is generated and meshed with the teeth of the rigid gear to achieve the purpose of transmission.
Features:
　　 advantages:
　　(1) 3, 50%,
　　(2) The transmission ratio range is large 50~300, 3000~60000
　　(3) The number of teeth meshed simultaneously is 30% more. It is precisely because of the unique advantage that the number of teeth meshed at the same time is large, the harmonic transmission has high precision and the tooth load capacity is large, thereby realizing a large speed ratio and a small volume.

　　(4) Large carrying capacity
　　(5) High motion accuracy
　　(6) Smooth movement, no impact, low noise
　　(7) Tooth side clearance can be adjusted
　 (8) The tooth surface wear is small and uniform, and the transmission efficiency is high
　　(9) Good coaxiality
　　(10) can transfer motion and power to confined spaces
　　 Disadvantages:
　　(1), easy to fatigue damage
　　(2) Flexible wheels and wave generators are difficult to manufacture
　　(3) The lower limit of the transmission ratio is high, and the number of teeth cannot be too few
　　(4) The starting torque is large, and the smaller the speed ratio, the more serious;
　　(5) The harmonic gear drive has no intermediate shaft, so intermediate speed cannot be obtained
　　(6) If the structure parameters are not selected properly or the structure timing is not good, the heat is too large, and the transmission load capacity is reduced
　　 At present, scholars from various countries have recognized that the fatigue failure of the flexspline cylinder is the most important failure form of harmonic transmission.

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