Abstract: In the profiles design of scroll compressor, aiming at the problem of low compression ratio and inadequate area utilization ratio of the orbiting and the fixed scroll in the traditional constant cross-section scroll profiles，a new type of variable cross-section scroll profiles was proposed. Scroll profiles composed of circle involutes and three-order curve were constructed piecewise by using the Frenet frame. The basic geometrical theory of the profile was established. Displacement volume, compression ratio，area utilization coefficient，axial gas force and tangential gas force were introduced to evaluate the performance of scroll profiles. The results show that the newly constructed variable cross-section scroll profiles have better geometric performance than traditional constant cross-section scroll profiles composed of the single circle involute, and the changing range of dynamic performance are small. The displacement volume, compression ratio and area utilization coefficient are improved by 8.80%, 10.57% and 8.84% respectively.

Key words: scroll compressor； constant cross-section scroll profile； variable cross-section scroll profile； Frenet frame； geometric performance； dynamic performance