The tooth profile characteristics of a twin-screw air compressor are as follows:

1. Meeting the conjugate condition: The tooth profiles of the two screws must satisfy the conjugate condition to ensure smooth meshing between the gears.
2. Good air tightness: The tooth profile design should consider both axial and radial air tightness to minimize gas leakage and improve compression efficiency.
3. Large volume and exhaust port: The tooth profile should provide a larger volume to achieve higher displacement and a larger exhaust port to reduce airflow velocity.
4. Tooth profile composition: The tooth profile is mainly composed of trochoids and arcs, among other elements.

The improvement of tooth profiles has gone through three generations. The first generation is symmetrical tooth profiles. The second generation is represented by the X-type tooth profile, which is asymmetrical. The third-generation tooth profiles aim to approach the limits of parameters and material strength for both symmetrical and asymmetrical profiles. It breaks away from the traditional 4:6 tooth ratio and achieves approximately 10% energy savings compared to the second-generation tooth profiles.