Compound Vacuum Pump Segmentation for Heat and Power Trade-offs
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Solution Overview
Problem
Multiple inlet vacuum pumps face challenges in achieving higher mass throughput while maintaining low partial pressure in high vacuum chambers, leading to excessive heat generation and performance loss due to high backing pressures, and increased power consumption in non-molecular flow conditions.
Innovation Solution
A compound vacuum pump configuration with a turbo-molecular sub-stage on the final pump stage and a molecular drag sub-stage on a turbo-molecular stage prior to the final stage, optimizing inter-stage volumes and arrangements to enhance gas throughput and reduce power consumption, featuring a Seigbahn molecular drag configuration for compactness and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high backing pressure is used in turbo-molecular pump stages, then pumping speed and capacity are improved, but excessive heat generation occurs and performance is lost
Solution Approach 1:
The pump stages are divided into turbo-molecular sub-stages and molecular drag sub-stages. The molecular drag sub-stages operate at higher backing pressures to handle gas flow, while turbo-molecular sub-stages operate at lower pressures to achieve high vacuum, segmenting the pressure ranges and reducing heat generation in each stage
Solution Approach 2:
Molecular drag sub-stages act as intermediary components between the high-pressure inlet and the low-pressure turbo-molecular stages. These drag stages absorb the high backing pressure and gradually reduce it, protecting the turbo-molecular stages from excessive heat generation while maintaining high pumping speed
2Productivity
If multiple pump stages are added to increase pumping speed, then capacity is improved, but power consumption increases in non-molecular flow conditions
Solution Approach 1:
The invention changes the operating parameters of different pump stages by using molecular drag sub-stages at higher pressures and turbo-molecular sub-stages at lower pressures. This parameter optimization allows the system to achieve high pumping speed while minimizing power consumption in non-molecular flow conditions
Solution Approach 2:
The pump system dynamically adapts to different flow conditions by combining molecular drag and turbo-molecular mechanisms. The molecular drag sub-stages are more efficient at higher pressures, while turbo-molecular sub-stages excel at lower pressures, creating a dynamic system that optimizes power consumption across varying operating conditions
3Quantity of substance
If pump stages are configured for high backing pressure, then gas throughput is improved, but severe performance loss occurs
Solution Approach 1:
The pump is segmented into molecular drag sub-stages for handling high gas throughput at higher pressures and turbo-molecular sub-stages for maintaining performance at lower pressures. This segmentation allows each sub-stage to operate in its optimal pressure range, preventing performance loss
Solution Approach 2:
Molecular drag sub-stages serve as intermediary components that handle the bulk gas throughput at higher backing pressures, protecting the turbo-molecular sub-stages from operating conditions that would cause severe performance loss. The drag stages mediate between the high-throughput requirement and the performance maintenance requirement
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 increases pumping speed and capacity without substantial power consumption increases, achieving twice the pumping speed at 0.1 mbar and improved performance in the transitional pressure regime, while maintaining a compact design and low power usage.
Implementation Method 1
a molecular drag sub-stage on a turbo-molecular stage prior to the final stage
Implementation Method 2
a turbo-molecular sub-stage on the final pump stage
Data Source
AI summary
First and second pump stages provide a flow-path from an inlet to the outlet (30), the flow-path being arranged so that molecules entering the first inlet (26) pass to the outlet through the first (120) and second (122) pump stage, and so that molecules entering the second inlet (28) pass to the outlet through an inter-stage volume (121) and second pump stage (122); wherein the first (120) and second (122) pump stages each comprise a turbo-molecular sub-stage (120a, 122a) and a molecular drag sub-stage (120b, 122b).