Roots Pump Stator Channel for Powder Handling
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Solution Overview
Problem
Roots vacuum pumps in industrial processes, particularly in the semiconductor industry, face issues with handling powders like silica, which can cause pump seizure and reduce operational lifetime due to poor powder-handling capabilities.
Innovation Solution
A Roots pump stator design with a directing means, such as a channel or deflector, that directs solid materials entrained in the gas towards the outlet, preventing them from entering the meshing zone of the rotors, thereby reducing the likelihood of pump seizure. This design includes a channel or deflector positioned between the arcuate surface and the outlet, engaging the surface prior to the bottom-dead-centre position to effectively remove powders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional Roots pump design is used, then the pump can evacuate gas from the chamber, but the pump is prone to seizure and malfunction when handling powdered by-products
Solution Approach 1:
The invention extracts and removes the harmful powdered by-products from the gas stream before they can enter the meshing zone of the rotors. The channel is specifically designed to separate and extract solids from the pumped gas, preventing them from reaching critical components where they would cause seizure.
Solution Approach 2:
The channel acts as an intermediary structure between the pumping volume and the outlet. It provides a dedicated pathway that mediates the separation of gas and solids, allowing gas to pass through while directing solids toward the outlet, thus protecting the rotor meshing zone from powder contamination.
2Reliability
If the pump is designed to handle larger powder loads, then powder-handling capability increases, but the complexity of the pump structure increases
Solution Approach 1:
The stator is segmented into distinct functional zones: the pumping volume for gas evacuation and the channel for solid material removal. This segmentation allows each zone to perform its specific function efficiently, with the channel acting as a dedicated pathway for solids that does not interfere with the rotor meshing operation.
Solution Approach 2:
The channel is strategically positioned and shaped to engage the arcuate surface at a specific location (prior to the bottom-dead-centre position) where it can effectively intercept and redirect solid materials. This localized intervention provides powder handling capability without requiring modification of the entire stator structure.
3Productivity
If the channel engages the arcuate surface prior to the bottom-dead-centre position, then powder is effectively removed from the pumping volume, but the channel design becomes more complex
Solution Approach 1:
The channel is positioned to engage the arcuate surface prior to the bottom-dead-centre position, performing the action of intercepting and redirecting solid materials before they can reach the meshing zone. This preliminary action ensures that powders are removed from the pumping volume in advance, preventing potential seizure before it occurs.
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 improved stator design enhances powder-handling capabilities by up to 400% without significantly affecting pumping efficiency, allowing pumps to handle larger powder loads without seizure, as demonstrated by increased capacity from 50-100 grams to 400 grams per hour.
Implementation Method 1
the solid material is 'flung' towards the outlet or away from a meshing zone where rotors mesh with one another
Implementation Method 2
a channel disposed between the arcuate surface and the outlet, said channel comprising a portion that engages the arcuate surface prior to the bottom-dead-centre position
Data Source
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AI summary
A Roots vacuum pump stator (100) is arranged to house a pair of intermeshing rotors (116,117), said stator being characterised in that it comprises a director or deflector (132,133) arranged to direct solid material entrained in a gas pumped through the pump towards the outlet. In other words, the stator according to the present invention has a means for directing or deflecting powder or solid material entrained in a gas being pumped directly towards an outlet of the pump or out of the pump. The directing means can comprise a channel (125) disposed between the arcuate surface and the outlet, said channel comprising a portion that engages the arcuate surface prior to the bottom-dead-centre position and which extends away from the rotor's axis of rotation towards the pump outlet. Thus, powder entrained in the pumped gas is effectively removed from pumping volume in a way which reduces the likelihood of any solid material causing the pump to seize: the channel can be arranged so that the solid material is "flung" towards the outlet or away from a meshing zone where rotors mesh with one another.