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JP-7855019-B2 - vacuum pump

JP7855019B2JP 7855019 B2JP7855019 B2JP 7855019B2JP-7855019-B2

Inventors

  • 田代 功
  • 横塚 克久

Assignees

  • エドワーズ株式会社

Dates

Publication Date
20260507
Application Date
20240311

Claims (6)

  1. Casing and, The rotor shaft is located inside the casing, A rotor blade that can rotate together with the rotor shaft, A magnetic bearing that supports the rotor shaft by magnetic levitation, A vacuum pump comprising the rotation of the rotor blades which exhausts gas, The vacuum pump has a heating means for heating the gas flow path within the vacuum pump, The heating means is Coil and, The heated part is a magnetic material that is heated by electromagnetic induction caused by passing an alternating current through the coil, The coil comprises a magnetic ceramic covering the side opposite to the front side where the heated portion is located , A vacuum pump characterized in that the frequency of the current applied to the coil is equal to or a multiple of the control frequency of the magnetic bearing .
  2. The vacuum pump according to claim 1, characterized in that the heated portion is connected to or is part of the stator component that forms the gas flow path.
  3. The vacuum pump according to claim 1, characterized in that the heated portion is connected to or is part of the rotor blade.
  4. The vacuum pump according to claim 1, characterized in that a portion of the magnetic ceramics is arranged on the side perpendicular to the direction from the coil to the heated part in a cross section perpendicular to the direction of current flow of the coil.
  5. The vacuum pump according to claim 1, characterized in that the coil is arranged within the gas flow path.
  6. The vacuum pump according to claim 1, characterized in that the magnetic ceramic is a soft magnetic ferrite containing manganese and zinc.

Description

This invention relates to a vacuum pump. Semiconductor manufacturing equipment, liquid crystal manufacturing equipment, electron microscopes, surface analysis equipment, and microfabrication equipment, etc., require a high vacuum environment within the equipment. Vacuum pumps are used to achieve this high vacuum inside these devices. An example of a vacuum pump used is a combined pump that combines a turbomolecular pump and a screw-groove pump. A vacuum pump combining a turbomolecular pump and a screw-groove pump has the screw-groove pump positioned downstream of the turbopump, which has rotating and stationary blades arranged alternately in the axial direction. Exhaust gas drawn in through the intake port is compressed by the turbomolecular pump and screw-groove pump and discharged outside the vacuum pump through the exhaust port. Exhaust gases exhibit viscous flow-like behavior, particularly in the downstream flow path where pressure is relatively high. Therefore, by-products tend to precipitate in areas of the vacuum pump's flow path where the exhaust gas flow stagnates. When by-products precipitate in the flow path, contact occurs between areas that would not normally be in contact, potentially leading to damage to the vacuum pump and changes in the internal heat transfer performance, resulting in variations in temperature distribution and compromising safety and productivity. Therefore, vacuum pumps sometimes include heating means to heat the components forming the gas flow path in order to suppress the deposition of by-products in the gas flow path. For example, Patent Document 1 discloses a structure in which a heating unit is provided to heat the stator components on the fixed-blade side by electromagnetic induction heating. The heating section comprises a yoke fixed to the stator component, a coil positioned on the yoke, and a heating plate connected to the stator component. The heating plate and yoke are made of magnetic materials such as iron-based materials or stainless steel. When a high-frequency alternating current is passed through the coil, the coil, heating plate, and yoke electromagnetically couple, generating eddy currents within the heating plate and yoke. Because the heating plate and yoke have inherent electrical resistances, they generate Joule heat. Furthermore, iron loss heat is generated in the heating plate and yoke, and copper loss heat is generated in the coil; these heats also heat the stator component. International Publication No. 2014/119191 This is a longitudinal cross-section of a vacuum pump.This is a circuit diagram of an amplifier.This is a time chart showing the control when the current command value is greater than the detected value.This is a timing chart showing the control when the current command value is smaller than the detected value.This is a longitudinal cross-sectional view of a vacuum pump according to the first embodiment.This is a perspective view showing the heating means.This is an enlarged cross-sectional view of the vicinity of the heating means of the vacuum pump according to the first embodiment.This is a longitudinal cross-sectional view of a vacuum pump according to the second embodiment.This is an enlarged cross-sectional view of the vicinity of the heating means of the vacuum pump according to the second embodiment.This is a partially enlarged cross-sectional view showing a modified example of the vacuum pump according to the first embodiment. The embodiments of the present invention will be described below with reference to the drawings. Note that the dimensions in the drawings may be exaggerated for illustrative purposes and may differ from the actual dimensions. Furthermore, in this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals to avoid redundant explanations. The vacuum pump 100 is a turbomolecular pump that exhausts gas by using rotating blades of a high-speed rotating body to dislodge gas molecules. The turbomolecular pump 100 is used, for example, to draw in and exhaust gas from a chamber in semiconductor manufacturing equipment. First, the basic configuration of the turbomolecular pump 100 will be explained. Figure 1 shows a longitudinal cross-sectional view of the turbomolecular pump 100. In Figure 1, the turbomolecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer casing 127. Inside the outer casing 127 is a rotor 103, which has multiple rotating blades 102 (102a, 102b, 102c...) arranged radially and in multiple stages around its circumference. A rotor shaft 113 is mounted at the center of the rotor 103, and this rotor shaft 113 is suspended in the air and its position is controlled, for example, by a five-axis controlled magnetic bearing. The rotor 103 is generally made of a metal such as aluminum or an aluminum alloy. The upper radial electromagnet 104 consists of four electromagnets arranged in pairs along