Vacuum Pump Exhaust Conductance via Stator Taper
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Solution Overview
Problem
Vacuum pumps, particularly turbo-molecular pumps, face challenges in maintaining high exhaust performance while being compact enough to fit within the height restrictions of dry etching and CVD apparatuses, often leading to deteriorated conductance due to narrowed exhaust paths when the exhaust port faces the screw stator.
Innovation Solution
The design incorporates a conductance increasing function section on the stator and base, featuring a tapered structure on the stator and an annular groove on the base, which expands the exhaust path, ensuring that the exhaust port faces the stator's outer peripheral surface, thereby enhancing conductance without compromising height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the exhaust port is arranged to face the screw stator to reduce pump height, then the height of the vacuum pump is reduced, but the conductance of the exhaust path is deteriorated
Solution Approach 1:
The patent applies local quality by creating a tapered structure on the stator's outer peripheral surface and forming a groove on the base's inner peripheral surface. These localized structural modifications specifically enhance the conductance of the exhaust path region without altering the overall pump height, thus resolving the contradiction between compact size and exhaust performance
Solution Approach 2:
The patent transitions from a uniform cylindrical stator shape to a tapered structure with varying radial dimensions. By changing the dimensional characteristics of the stator surface (creating a gradient from larger to smaller radius), the exhaust path conductance is improved while maintaining the same axial height, effectively resolving the height-performance contradiction
2Productivity
If the number of stages in the vacuum pump is increased to improve exhaust performance, then the exhaust performance is improved, but the height of the vacuum pump increases
Solution Approach 1:
Instead of increasing the number of stages (which would increase height), the patent changes the geometric parameters of the existing stator structure by implementing a tapered profile and base groove. This parameter modification optimizes the exhaust path conductance within the same height constraint, avoiding the need for additional stages
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves the exhaust performance of the vacuum pump by increasing conductance, preventing the deterioration of exhaust performance even when the pump is downsized, and reduces material costs by maintaining a higher temperature on the screw stator to prevent substance adherence.
Implementation Method 1
The rotor rotates at high speed, specifically, at several tens of thousands revolutions per minute. The rotation of the rotor causes the rotor blades and the stator blades to cooperate with each other and causes the rotary cylindrical section and the screw stator to cooperate with each other. As a result, gas inside the vacuum chamber is discharged
Implementation Method 2
a shape of the outer peripheral surface of the stator allows a distance between the outer peripheral surface of the stator in a region facing the exhaust port and the inner peripheral surface of the base to be larger than a distance between the outer peripheral surface of the stator in a region locating on the suction port side and not facing the exhaust port and the inner peripheral surface of the base
Data Source
AI summary
A vacuum pump comprises a vacuum exhaust section, the vacuum exhaust section including a stator, and a rotor having a rotor cylindrical section, the rotor cylindrical section discharging gas in cooperation with the stator, a suction port; a base; an exhaust port disposed on the base, wherein at least a part of the exhaust port faces an outer peripheral surface of the stator, and gas sucked through the suction port by the vacuum exhaust section is discharged through the exhaust port; and a conductance increasing function section formed on at least one of the outer peripheral surface of the stator and an inner peripheral surface of the base, the outer peripheral surface and the inner peripheral surface facing an exhaust path for gas discharged by the rotor cylindrical section and the stator leading to the exhaust port.