Vacuum Pump Rotor Fin for Particle Backflow Prevention
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Solution Overview
Problem
Conventional vacuum pumps face inefficiencies in preventing particle backflow, which affects process outcomes in semiconductor manufacturing, due to large and complex designs that attempt to capture bouncing particles, often resulting in reduced exhaust efficiency.
Innovation Solution
A compact vacuum pump design featuring a rotor with a central portion and extending rotor blade stages, along with a rotor fin that includes a fin shaft and transfer blades, where the height and number of transfer blades are optimized based on particle fall velocity and rotor speed to redirect particles away from the rotor central portion without colliding, thus preventing backflow without impairing exhaust efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a baffle or cylindrical member with annular texture is provided to prevent particles from falling onto the rotor central portion, then particle backflow is reduced, but the device complexity and size increase
Solution Approach 1:
The invention extracts the particle prevention function from separate components (baffle, cylindrical member) and integrates it directly into the rotor structure by providing a rotor fin extending from the rotor central portion. This eliminates the need for additional prevention components while maintaining the function of preventing particle backflow.
Solution Approach 2:
The rotor fin is merged with the rotor structure itself, combining the rotation function and particle prevention function into a single integrated component. The rotor fin extends from the rotor central portion and works in conjunction with the rotor blades to prevent particles from falling onto the rotor central portion, eliminating the need for separate prevention components.
2Productivity
If a conical member with guide blades is provided to improve exhaust efficiency, then gas molecule guidance is improved, but the device size increases and particle capture probability increases
Solution Approach 1:
The invention provides the rotor fin only at the rotor central portion where particles accumulate, rather than providing a conical member with guide blades throughout the entire rotor structure. This localized approach maintains particle prevention functionality while minimizing the overall device size.
Solution Approach 2:
The invention extracts the particle prevention function from the conical member structure and places it directly on the rotor central portion through the rotor fin. This eliminates the need for the large conical member while maintaining the exhaust efficiency function through the rotor blades.
3Object-affected harmful factors
If the rotor fin height and number of transfer blades are increased to prevent particle collision, then particle backflow prevention is improved, but the device complexity increases
Solution Approach 1:
The invention optimizes the height and number of transfer blades by calculating the fall velocity of particles and the rotation speed of the rotor. The rotor fin height is determined based on the formula: height ≥ (fall velocity × rotation period) / 2π, and the number of transfer blades is determined based on the rotation speed. This parameter optimization prevents particle backflow while minimizing device complexity.
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
The solution effectively prevents particle backflow into the chamber while maintaining high exhaust efficiency, ensuring a compact and efficient vacuum pump operation.
Implementation Method 1
a transfer blade that extends from the fin shaft portion and causes particles to bounce back in a direction toward an outer periphery of the rotor, the particles falling toward the end through an inlet port
Implementation Method 2
the height of the transfer blade in a rotor axial direction and the number of transfer blades are set based on a fall velocity of the particles and a rotation speed of the rotor
Data Source
AI summary
A vacuum pump includes a rotor that has a rotor central portion and a plurality of stages of rotor blade portions extending from the rotor central portion and having a predetermined elevation angle, and a casing that houses the rotor therein. The rotor further includes a rotor fin. The rotor fin includes a fin shaft portion connected to an end of the rotor central portion, and a transfer blade that extends from the fin shaft portion and causes particles to bounce back in a direction toward an outer periphery of the rotor, the particles falling onto the abovementioned end through an inlet port. The height of the transfer blade and the number of transfer blades are set based on the fall velocity of the particles and the rotation speed of the rotor, such that the particles are prevented from falling onto the abovementioned end without colliding with the transfer blade.