Abstract: To study the influence of key parameters on the contact characteristic and load bearing capacity of planar enveloping internal-meshing worm drive, contact line function of the planar enveloping internal-meshing worm drive is build based on the gearing meshing theory, also, the contact line calculated by Matlab software are shadowed on the teeth of worm wheel, and then center distance、transmission ratio、axial crossing angle between the worm and the worm wheel、inclination angle of the generating plane、pitch circle coefficient and the main base circle coefficient are used to figure out the ideal design parameters for the planar enveloping internal-meshing worm drive using the tooth contact analyze method. Furthermore, one three-dimension model of the planar enveloping internal-meshing worm drive is generated by using the above ideal design parameters. This study shows that the transmission ratio、inclination angle of the generating plane and rotating angles of the worm wheel has much more influences on the contact zone for the planar enveloping internal-meshing worm drive. However, the inclination angle of the generating plane is between 18°-36°, the axial crossing angle between the worm and the worm wheel is between 30°-54°, the rotating angles of worm wheel is between 90°-138°, planar enveloping internal-meshing worm drive has much better contact characteristic. This study laid the foundation for further theory and practice study on the planar enveloping internal-meshing worm drive.

Key words: internal-meshing worm drive, meshing performance, numerical calculation method, planar enveloping