Roots Rotor Vacuum Pump Outlet Layout for Particle Discharge
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Solution Overview
Problem
Existing vacuum pumps used in semiconductor manufacturing face issues with particle deposition in the rotor chamber, which hinders the rotation of Roots rotors due to the accumulation of process gas by-products, leading to potential failure.
Innovation Solution
The vacuum pump design features a larger gas outlet width relative to the gas inlet, with the connection between the rotor chamber and gas outlet located outwardly from the rotor center line, facilitating the discharge of particles and reducing deposition in the rotor chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If particles are discharged along with process gas, then gas flow is maintained, but particles accumulate in the rotor chamber and deposit on rotor surfaces
Solution Approach 1:
The patent extracts particles from the gas flow path by positioning the gas outlet connection outwardly from the rotor center line. This creates a separate particle discharge path that removes particles before they can accumulate on rotor surfaces, while maintaining efficient gas discharge through the same outlet configuration.
Solution Approach 2:
The patent changes the spatial dimension of particle discharge by positioning the gas outlet connection in a radial direction outwardly from the rotor center line, rather than along the axial direction. This dimensional change creates a more effective particle discharge path that prevents accumulation on rotor surfaces while maintaining gas flow efficiency.
2Volume of stationary object
If gas outlet connection is positioned inwardly, then rotor chamber volume is maximized, but particles accumulate and hinder rotor rotation
Solution Approach 1:
The patent positions the gas outlet connection in a radial direction outwardly from the rotor center line, changing the discharge dimension from axial to radial. This creates an effective particle discharge path that prevents accumulation, while the outlet width is designed to be sufficient to maintain adequate rotor chamber volume.
Solution Approach 2:
The patent applies local quality by designing the gas outlet with a width that is larger than the gas inlet width. This localized enlargement at the outlet position optimizes particle discharge efficiency in that specific region while maintaining overall rotor chamber volume and rotor rotation functionality.
3Productivity
If gas outlet width is increased, then particle discharge is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by selectively increasing the gas outlet width only at the connection position outwardly from the rotor center line, rather than uniformly increasing all dimensions. This localized modification improves particle discharge efficiency while minimizing increases in overall device complexity and maintaining a simple structural design.
Data Source
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AI summary
A vacuum pump that can discharge particles contained in gas from a rotor chamber well is disclosed. The vacuum pump 1 includes: a pump casing 6 having a rotor chamber 5 therein; a pair of Roots rotors 8 disposed in the rotor chamber 5; and a pair of rotation shafts 9 supporting the pair of Roots rotors 8. The pump casing 6 has a gas inlet 12 and a gas outlet 13 communicating with the rotor chamber 5. A connection 25 between an inner wall 22 forming the rotor chamber 5 and an inner wall 23 forming the gas outlet 13 is located on or located more outwardly than a rotor center line CL extending through a center of rotation RC and a bottom dead center LP of each Roots rotor 8.