Induction-Heated Vacuum Pump Rotor to Prevent Gas Deposition
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Solution Overview
Problem
Turbomolecular pumps used in semiconductor manufacturing face issues with deposition of process gasses on the interior, leading to reduced performance, as conventional heating methods are inefficient and can only heat the rotating body when the pump is operating.
Innovation Solution
A vacuum pump design that uses an AC magnetic field to heat the rotating body efficiently, generating eddy currents even when the pump is stopped, preventing deposition by intersecting the rotating body with an AC magnetic field of a predetermined frequency greater than ωres/√2, thereby reducing vibration and enhancing heating efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional heating methods are used to heat the rotating body, then the rotating body can be heated, but the heating efficiency is low and the rotating body cannot be heated when the pump is stopped
Solution Approach 1:
The patent replaces conventional mechanical heating methods with electromagnetic induction heating. An AC magnetic field is applied to the rotating body, generating eddy currents that heat the rotating body from the inside. This eliminates the need for direct mechanical contact or thermal conduction, achieving high heating efficiency and the ability to heat the rotating body even when the pump is stopped.
2Loss of energy
If the pump stops operating, then energy consumption is reduced, but deposition of process gasses occurs on the rotating body
Solution Approach 1:
The patent applies preliminary action by maintaining the AC magnetic field heating even when the pump stops operating. The heating is activated in advance or continued during stop periods to prevent process gasses from depositing on the rotating body. This ensures the rotating body remains at a temperature that prevents deposition, eliminating the harmful effect before it can occur.
3Stability of the object's composition
If AC magnetic field frequency is increased to reduce vibration, then vibration is minimized, but heating efficiency may be affected
Solution Approach 1:
The patent applies parameter changes by optimizing the AC magnetic field frequency to a specific range (greater than ωres/√2, where ωres is the rigid body mode natural angular frequency). This frequency optimization simultaneously achieves two goals: minimizing vibration by avoiding resonant frequencies and maintaining effective heating through eddy current generation. The parameter change resolves the contradiction between vibration reduction and heating efficiency.
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 AC magnetic field effectively prevents deposition on the rotating body by generating eddy currents, ensuring continuous heating efficiency and minimizing vibration, even when the pump is stopped, thus maintaining pump performance.
Implementation Method 1
The AC magnetic field generated at the heating electromagnet is made to intersect with the rotating body, thereby generating an eddy current at the rotating body, at a perimeter of the AC magnetic field that intersects the rotating body
Implementation Method 2
Eddy current loss is generated by this eddy current, and accordingly the rotating body can be heated
Implementation Method 3
The AC magnetic field generated at the heating electromagnet is made to intersect with the rotating body, thereby generating an eddy current at the rotating body
Data Source
AI summary
A vacuum pump, which prevents adhesion of products even when a rotating body is stopped, by heating the rotating body using an alternating current (AC) magnetic field. Two heating electromagnets are disposed facing each other across a rotating body. The heating electromagnets receive a supply of AC electric current from a heating electric power source. Excitation of the heating from this AC electric current generates an AC magnetic field. The generated AC magnetic field intersects with the rotating body. Eddy current is generated around the intersecting AC magnetic field. The rotating body is heated by this eddy current. This heating enables deposition of products to be prevented even further, and realize improved pump operation efficiency.