Two-Stage Roots Vacuum Pump with Optimized Displacement Ratios
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Solution Overview
Problem
Existing pumping units, particularly those used in semiconductor manufacturing and CVD applications, face challenges in achieving high pumping performance with minimal power consumption, especially within the operating range of 53 Pa to 266 Pa and at ultimate pressure, due to significant losses and high energy intensity.
Innovation Solution
A pumping unit comprising a primary multistage dry vacuum pump with at least four stages in series and a two-stage Roots vacuum pump, where the second stage of the Roots pump is upstream of the primary pump, with a volume displacement ratio less than six, and a relief module to manage pressure differences, optimizing performance and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a Roots vacuum pump with large volume displacement is used to achieve high pumping flow rates, then pumping performance in the operating range is improved, but power consumption increases significantly
Solution Approach 1:
The Roots vacuum pump is divided into two pumping stages with different volume displacements. The first stage has a larger volume displacement to handle high flow rates, while the second stage has a smaller volume displacement to operate efficiently at lower pressures. This segmentation allows the system to achieve high pumping performance in the operating range while reducing power consumption by matching each stage's capacity to its specific operating conditions.
2Device complexity
If the volume displacement ratio between Roots pump stages is increased to reduce the number of stages, then device complexity is reduced, but pumping performance is lost at ultimate pressure
Solution Approach 1:
Each pumping stage is designed with locally optimized volume displacement characteristics. The first stage is optimized for high flow rate conditions with larger volume displacement, while the second stage is optimized for ultimate vacuum conditions with smaller volume displacement. This local quality optimization ensures that each stage performs its specific function efficiently, achieving both reduced complexity and maintained reliability.
3Device complexity
If a single-stage Roots pump is used, then device complexity is reduced, but pumping performance is insufficient both in operating range and at ultimate pressure
Solution Approach 1:
The single-stage Roots pump is segmented into two pumping stages with different volume displacements. This segmentation enables the system to achieve high pumping flow rates in the operating range through the first stage while maintaining effective pumping performance at ultimate pressure through the second stage, thereby improving overall productivity without excessive complexity.
4Reliability
If the volume displacement ratio between stages is made very small to optimize ultimate pressure, then pumping performance at ultimate vacuum is improved, but pumping flow rate in operating range decreases
Solution Approach 1:
The volume displacement of each stage is locally optimized for its specific operating conditions. The first stage has a larger volume displacement ratio optimized for high flow rate conditions in the operating range, while the second stage has a smaller volume displacement ratio optimized for ultimate vacuum conditions. This local quality approach ensures that each stage contributes maximally to its designated function, achieving both high productivity and reliability.
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 achieves maximum pumping performance up to 3000 m3/h in the desired range and maintains low power consumption, with satisfactory ultimate vacuum performance and reduced energy usage.
Implementation Method 1
a primary vacuum pump of the multistage dry type, comprising at least four pumping stages fitted in series... a two-stage Roots vacuum pump, comprising a first and a second pumping stage fitted in series
Data Source
AI summary
A pumping unit is provided, including a primary vacuum pump of a multistage dry type, including at least four pumping stages fitted in series; and a two-stage Roots vacuum pump, including a first pumping stage and a second pumping stage fitted in series, the second pumping stage being fitted in series with and upstream of a first pumping stage of the primary vacuum pump in a direction of flow of gases to be pumped, in which a ratio of a volume displacement of the first pumping stage of the two-stage Roots vacuum pump to a volume displacement of the second pumping stage of the two-stage Roots vacuum pump is less than six, and in which a ratio of a volume displacement of the second pumping stage of the two-stage Roots vacuum pump to a volume displacement of the first pumping stage of the primary vacuum pump is less than six.