Structural Optimization of Oil‑free Vacuum Pump Scroll Tooth Clearance, Reduce Gas Backflow and Stabilize Ultimate Vacuum Degree

The scroll tooth clearance is one of the core influencing factors determining the ultimate vacuum performance of oil‑free scroll vacuum pumps. Excessive clearance will cause serious gas backflow inside the pump cavity, which directly lowers the achievable vacuum degree and deteriorates pumping efficiency. Too small clearance will bring about risks of friction, scraping and jamming between moving scroll and fixed scroll under high‑temperature continuous operation due to thermal expansion of components.

During structural optimization, comprehensive consideration shall be given to machining tolerance, assembly clearance and thermal deformation compensation. Optimize the profile accuracy of scroll tooth, control the unilateral clearance within reasonable interval, adopt targeted thermal compensation structure to offset dimensional variation caused by temperature rise. Meanwhile, strengthen flatness control of scroll base plate to avoid local clearance deviation induced by plate deformation.

Strict assembly process management is required in actual production. Standardize positioning tooling and torque parameters for installation of moving and fixed scrolls, prevent offset installation which leads to partial clearance over‑range. Conduct air‑tightness inspection and ultimate vacuum test after assembly, screen out unqualified products with obvious backflow phenomenon.

Under actual working conditions, regular inspection on scroll tooth wear status shall be arranged. Medium containing dust and granular impurities will accelerate scroll tooth surface abrasion, resulting in gradual enlargement of clearance and performance attenuation. Matching inlet filtering device can reduce particle entering the pump cavity, extend the effective service period of optimized clearance structure, and keep the ultimate vacuum of oil‑free vacuum pump stable in long‑time running process.