Leak Detection Pump System with Intermediate Gas Inlets
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Solution Overview
Problem
Mass spectrometric leak detection devices face issues with test gas accumulation due to insufficient pre-vacuum pump capacity, leading to background signals and offset errors in the mass spectrometer.
Innovation Solution
A device with a three-stage turbomolecular pump and a booster pump is configured to include additional intermediate gas inlets and connecting branches, allowing the output of the booster pump to be evacuated by both the pre-vacuum pump and the turbomolecular pump, creating a higher test gas partial pressure difference and reducing offset errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the pre-vacuum pump capacity is insufficient to discharge test gas, then the device complexity is reduced, but test gas accumulates at the booster pump outlet causing background signals and offset errors
Solution Approach 1:
The patent segments the vacuum pump system into multiple functional stages: a three-stage turbomolecular pump divided into input stage, intermediate stage, and output stage, each with dedicated intermediate gas inlets. This segmentation allows test gas to be evacuated at multiple points along the pump trajectory, preventing accumulation at the booster pump outlet while maintaining manageable complexity through modular design.
Solution Approach 2:
The patent introduces intermediate gas inlets as intermediary connection points between pump stages and the booster pump outlet. These intermediaries provide additional evacuation pathways for test gas, allowing it to be removed before reaching the mass spectrometer, thus improving measurement precision without requiring a single oversized pump system.
2Device complexity
If test gas is not efficiently evacuated from the booster pump outlet, then the device structure is simplified, but test gas flows countercurrently into the mass spectrometer generating offset errors
Solution Approach 1:
The patent implements preliminary evacuation action by providing intermediate gas inlets at the input stage and intermediate stage of the turbomolecular pump. These inlets allow test gas to be removed before it can accumulate and flow countercurrently into the mass spectrometer, preventing the harmful effect before it occurs.
Solution Approach 2:
The patent applies local quality by providing dedicated intermediate gas inlets at specific locations along the pump stages where test gas accumulation is most likely to occur. Each intermediate gas inlet is positioned to address local evacuation needs, efficiently removing test gas from critical areas without requiring complex global system changes.
3Device complexity
If a single pre-vacuum pump evacuates both the turbomolecular pump and booster pump, then the device complexity is reduced, but the test gas partial pressure difference is insufficient for efficient test gas removal
Solution Approach 1:
The patent adds another dimension to the evacuation system by introducing intermediate gas inlets that create additional evacuation pathways parallel to the main pre-vacuum pump path. This multi-dimensional approach increases the test gas partial pressure difference and evacuation capacity without requiring a completely different system configuration.
Solution Approach 2:
The intermediate gas inlets serve multiple functions: they evacuate test gas from different pump stages, maintain pressure gradients, and prevent test gas accumulation. This multi-functionality increases evacuation efficiency while using the existing pre-vacuum pump infrastructure, avoiding the need for additional dedicated pumps.
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 efficiently removes test gas, reducing or eliminating offset errors in the mass spectrometer by ensuring effective evacuation of test gas through the turbomolecular pump, thereby improving the accuracy of leak detection.
Implementation Method 1
This results in a higher test gas partial pressure difference between the input stage of the booster pump and the inlet of the pre-vacuum pump, so that the test gas—e.g. helium—is taken away more efficiently
Data Source
AI summary
A device for leak detection on a test specimen, comprising a mass spectrometer (12), an at least three-stage turbomolecular pump (14), the input stage (18) of which is connected to the mass spectrometer (12) and which has a first intermediate gas inlet arranged between the input pump stage and the intermediate pump stage (26) and a second intermediate gas inlet arranged between the intermediate pump stage (26) and the output pump stage (24), an at least two-stage booster pump, the input pump stage (46) of which can be connected to the test specimen to be examined and which has an intermediate gas outlet (54) arranged between the input pump stage (46) and the output pump stage (48) and a pre-vacuum pump (22) which is connected to the outlet (20) of the output pump stage (24) of the turbomolecular pump (14) and is configured to generate a pre-vacuum pressure of less than 50 mbar at the outlet (20) of the turbomolecular pump (14) and to evacuate it against atmospheric pressure, characterized in that the intermediate gas outlet (54) of the booster pump is connected in a gas-conducting manner to the first intermediate gas inlet (36) of the turbomolecular pump (14) via a first connecting branch (62), and in that the outlet of the output pump stage (48) of the booster pump is connected in a gas-conducting manner to the second intermediate gas inlet of the turbomolecular pump (14) via a second connecting branch (64).