Turbomolecular Pump Pressure Sensing via Downstream Measurement
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Solution Overview
Problem
Existing vacuum pumps, particularly turbomolecular pumps, face challenges in accurately determining suction-side pressure at high vacuum pressures due to limitations in cost-effective measurement methods.
Innovation Solution
Incorporating a pressure determination unit with a measuring tap positioned downstream of the pump stage, utilizing a cheap pressure sensor like a Pirani vacuum meter, and applying a correction factor to infer suction-side pressure from measured discharge pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a Pirani measurement method or other inexpensive measurement methods are used to determine pressure, then cost-effectiveness is improved, but measurement precision deteriorates at high vacuum pressures (less than 5×10^-4 mbar)
Solution Approach 1:
The patent introduces an intermediary approach by measuring pressure at a location downstream of the pumping stage where the pressure is higher (forevacuum range) rather than directly at the suction side. This intermediary measurement point allows inexpensive Pirani gauges to operate in their accurate measurement range, and the suction side pressure is then derived indirectly through calculation using the known compression capacity of the pump.
2Measurement precision
If direct measurement of suction-side pressure is implemented, then measurement precision is improved, but device complexity increases due to requiring expensive measurement devices
Solution Approach 1:
The patent extracts the measurement function from the high-vacuum environment to a forevacuum environment. By placing the measuring tap downstream of the pumping stage, the measurement is taken out from the problematic high-vacuum zone where expensive devices are needed, to a region where inexpensive devices suffice, while still obtaining the required suction-side pressure information through calculation.
3Measurement precision
If measuring tap is positioned at suction side, then measurement precision is improved, but ease of operation deteriorates due to inability to use inexpensive measurement methods
Solution Approach 1:
The patent inverts the conventional approach by not measuring the suction-side pressure directly, but rather measuring the downstream pressure and calculating the suction-side pressure from it. This inversion allows the use of simple, inexpensive measurement devices while maintaining the ability to determine suction-side pressure accurately through the known compression characteristics of the pump.
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
Enables reliable and cost-effective determination of suction-side pressure, overcoming limitations of existing methods by using indirect measurement and correction factors based on known compression performance.
Implementation Method 1
the Pirani measurement method is used, which is characterized primarily by its cost-effectiveness and high measurement accuracy
Data Source
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AI summary
The present invention relates to a vacuum pump, in particular a turbomolecular pump, with at least one pumping stage and with a pressure measuring unit for determining a pressure prevailing on a suction side of the vacuum pump, which includes a measuring device, wherein a measuring tap of the measuring device is provided in the area of the pumping stage or downstream of the pumping stage.