When it comes to harmonic reduction gears, have you ever been bewildered by the complex simple harmonic curves in college physics, leaving you confused about how they work?
In fact, the structure of a harmonic reduction gear is not complicated. It is a new type of reducer based on the principle of planetary gear transmission, widely used in fields such as aviation, aerospace, energy, and maritime.
The main components of a harmonic gear reducer include the circular spline, flexspline, and wave generator. These basic components work together to enable the harmonic gear reducer to efficiently transmit power and achieve speed reduction.
Detailed Component Description
The primary components of a harmonic gear reducer include the wave generator, flexspline, and circular spline. The circular spline is a rigid internal gear with a stable structure; the flexspline, a deformable cylindrical external gear, has the same tooth profile and pitch as the circular spline but has a few fewer teeth (usually two). The wave generator, composed of an elliptical disk and a flexible ball bearing, accurately drives the flexspline to produce elliptical deformation when it rotates.
The core of a harmonic reduction gear lies in its precise assembly and unique working principle. By rotating the wave generator, the flexible ball bearing and elliptical disk work together to accurately drive the flexspline to produce the necessary elliptical deformation. This deformation causes controlled elastic deformation between the flexspline and circular spline, achieving high-precision speed and force transmission.
During the operation of the harmonic reduction gear, the wave generator typically acts as the driving component, while either the flexspline or the circular spline serves as the driven component and the other as the stationary component. The wave generator closely presses against the flexspline, causing it to deform into an elliptical shape. This deformation results in the teeth at the long axis ends of the flexspline fully meshing with the circular spline's teeth, while the teeth at the short axis ends completely disengage. The teeth in other regions are in a transitional state between meshing and disengagement.
As the wave generator continues to rotate, the flexspline's deformation continuously changes, altering the meshing state between the flexspline and circular spline in a cycle of engagement, meshing, disengagement, and re-engagement. If the circular spline is set as the stationary component, the flexspline will slowly rotate relative to the circular spline, thereby outputting transmission and driving the load to move.
The working principle of a harmonic reduction gear is based on its unique structure. Through the rotation of the wave generator, the flexspline produces elliptical deformation, which changes the meshing state between the flexspline and circular spline. This constantly changing meshing state, including engagement, meshing, disengagement, and re-engagement in a cycle, achieves efficient transmission.
The gear ratio calculation is done based on the ratio between the rotational speed of the wave generator and the output speed of the flexspline, reflecting the speed conversion relationship during transmission. Due to the tooth number difference between the circular spline and flexspline, every 180-degree rotation of the wave generator causes the tooth meshing to produce a slight counterclockwise rotation of the flexspline relative to the wave generator. In other words, for every tooth advancement of the flexspline teeth meshing with the circular spline, the wave generator rotates exactly 180 degrees.
When the circular spline is fixed and the wave generator actively drives the flexspline, the transmission ratio of the harmonic gear drive can be calculated using the formula i = -z1/(z2-z1), where z2 and z1 represent the number of teeth on the circular spline and flexspline respectively. This transmission mechanism provides the harmonic gear reducer with high efficiency and a compact transmission advantage.
Excellent Transmission Precision
In the process of harmonic transmission, due to the simultaneous meshing of multiple teeth, this design averages out errors, meaning that the meshing between teeth compensates for each other, significantly improving transmission precision.
Wide Transmission Ratio Range
The gear ratio of single-stage harmonic transmission can reach 70 to 320, and in specific applications, it can even reach 1000, with multi-stage transmissions further expanding this range.
Simple Structure and Easy Installation
The harmonic reduction gear consists of only three basic components, and the input and output are coaxial, making its structure extremely simple and compact, and easy to install.
Strong Load Capacity
Thanks to the design of multiple teeth meshing, the load capacity of the harmonic drive is significantly improved, with the number of teeth meshing simultaneously in dual-wave transmission even reaching 30% of the total number of teeth.
