Turbomachine having hybrid bearing structure including magnetic bearing, permanent magnet, and sleeve journal bearing and method of controlling the same

Patent metadata

Field	Value
Publication number	US-11905993-B2
Application number	US-202217956246-A
Country	US
Kind code	B2
Filing date	Sep 29, 2022
Priority date	Jun 17, 2022
Publication date	Feb 20, 2024
Grant date	Feb 20, 2024

Abstract

A turbomachine according to an embodiment of the present disclosure may include a rotary shaft, a magnetic bearing including a core body configured to surround the rotary shaft, a plurality of poles radially extending from an inner surface of the core body toward the rotary shaft, and coils wound around the plurality of poles to levitate the rotary shaft by using a magnetic force generated by a magnetic field formed by applied electric current, a sleeve journal bearing disposed between the rotary shaft and the magnetic bearing so as to surround the rotary shaft and configured to levitate the rotary shaft by generating a dynamic pressure when the rotary shaft rotates, and a permanent magnet disposed between the plurality of poles and configured to support the rotary shaft by using a magnetic force.

First claim

What is claimed is:

1. A turbomachine comprising:
a rotary shaft;
a magnetic bearing comprising a core body configured to surround the rotary shaft, a plurality of poles radially extending from an inner surface of the core body toward the rotary shaft, and coils wound around the plurality of poles to levitate the rotary shaft by using a magnetic force generated by a magnetic field formed by applied electric current;
a sleeve journal bearing disposed between the rotary shaft and the magnetic bearing to surround the rotary shaft and configured to levitate the rotary shaft by generating a dynamic pressure when the rotary shaft rotates; and
a permanent magnet disposed between the plurality of poles and configured to support the rotary shaft by using a magnetic force,
wherein the sleeve journal bearing is made of austenite steel.

2. The turbomachine of claim 1 , wherein an inner surface of the sleeve journal bearing is coated with a solid lubricant to reduce friction or abrasion with the rotary shaft.

3. The turbomachine of claim 2 , wherein the solid lubricant includes at least one of polytetrafluoroethylene (PTFE), MoS 2 , and graphite.

4. The turbomachine of claim 1 , further comprising:
a position sensor disposed at one side of the rotary shaft based on a radial direction and configured to sense a distance from the rotary shaft in the radial direction.

5. The turbomachine of claim 4 , further comprising:
a controller configured to control the amount of electric current to be applied to the magnetic bearing based on a distance between the rotary shaft and the position sensor in accordance with rotational vibration of the rotary shaft.

6. The turbomachine of claim 5 ,
wherein the controller calculates additional electric current to be applied to the magnetic bearing based on the distance between the rotary shaft and the position sensor and
the controller applies the additional electric current to the magnetic bearing.

7. A method of controlling the turbomachine according to claim 1 , the method comprising:
sensing a load applied to the rotary shaft;
applying supporting force generated by the permanent magnet and the sleeve journal bearing;
determining whether the supporting force generated by the permanent magnet and the sleeve journal bearing is equal to or higher than the load applied to the rotary shaft; and
applying electric current to the magnetic bearing based on a situation in which the supporting force generated by the permanent magnet and the sleeve journal bearing is lower than the load applied to the rotary shaft.

Assignees

• Korea Inst Sci & Tech

Inventors

• Lee Yong Bok
• Kim Jungwan
• Ha Yunseok
• An Byul
• Kwak Wonil
• Lee Yeong-Do

Classifications

• F16C32/0442 Primary

  with devices affected by abnormal, undesired or non-standard conditions such as shock-load, power outage, start-up or touchdown · CPC title

• F16C32/0478

  with permanent magnets to support radial load · CPC title

• F16C2360/45

  Turbo-molecular pumps · CPC title

• F16C32/0402 Primary

  combined with other supporting means, e.g. hybrid bearings with both magnetic and fluid supporting means · CPC title

• F16C32/048

  with active support of two degrees of freedom, e.g. radial magnetic bearings · CPC title