JP3988325B2 - Magnetic bearing device - Google Patents

Magnetic bearing device Download PDF

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Publication number
JP3988325B2
JP3988325B2 JP19351799A JP19351799A JP3988325B2 JP 3988325 B2 JP3988325 B2 JP 3988325B2 JP 19351799 A JP19351799 A JP 19351799A JP 19351799 A JP19351799 A JP 19351799A JP 3988325 B2 JP3988325 B2 JP 3988325B2
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Japan
Prior art keywords
rotating body
ball bearing
protective ball
gravity
center
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JP19351799A
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JP2000346069A (en
Inventor
正章 大槻
有宏 藤原
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JTEKT Corp
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JTEKT Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C32/00—Bearings not otherwise provided for
    • F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
    • F16C32/0406—Magnetic bearings
    • F16C32/044—Active magnetic bearings
    • F16C32/0442—Active magnetic bearings with devices affected by abnormal, undesired or non-standard conditions such as shock-load, power outage, start-up or touchdown
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C32/00—Bearings not otherwise provided for
    • F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
    • F16C32/0406—Magnetic bearings
    • F16C32/044—Active magnetic bearings
    • F16C32/0474—Active magnetic bearings for rotary movement
    • F16C32/0489—Active magnetic bearings for rotary movement with active support of five degrees of freedom, e.g. two radial magnetic bearings combined with an axial bearing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C39/00—Relieving load on bearings
    • F16C39/02—Relieving load on bearings using mechanical means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2360/00—Engines or pumps
    • F16C2360/44—Centrifugal pumps
    • F16C2360/45—Turbo-molecular pumps

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Magnetic Bearings And Hydrostatic Bearings (AREA)

Description

【０００１】
【発明の属する技術分野】
この発明は、ターボ分子ポンプ等の高速回転する回転部分を支持する磁気軸受装置に関する。
【０００２】
【従来の技術】
従来の磁気軸受装置は、例えば図４（Ａ）に示されるものが知られている。すなわち、固定部分としての筒状のケーシング１０１に回転体としての軸１０２が挿通されている。この回転軸１０２は、上記ケーシング１０１の内周面１０１ａに配設された一対のラジアル磁気軸受１０３および一対のアキシャル磁気軸受１０４により非接触に支持され、例えば３０，０００〜４０，０００ｒｐｍ程度の高速で回転する。そして、回転軸１０２が停止される場合に、高速回転している回転軸１０２が上記磁気軸受１０３，１０４と接触すると、この磁気軸受１０３，１０４が損傷させられる危険性がある。このため、ケーシング１０１の上下２箇所に離間して、回転軸１０２の停止時に回転軸１０２を支承し、回転軸１０２が磁気軸受１０３，１０４に接触しないようにする保護用玉軸受１０５，１０６が設けられている。例えば、上側の保護用玉軸受１０５には図４（Ｂ）のような深溝形の総玉軸受が使用され、下側の保護用玉軸受１０６にはアキシャル方向の負荷も受けられるように図４（Ｃ）のような斜接玉軸受が２個正面合わせで使用されており、それぞれの外輪１０５ａ，１０６ａが上記ケーシング１０１に固定され、それぞれの内輪１０５ｂ，１０６ｂが回転体に対し隙間をもって対向させられている。そして回転軸１０２が停止時に、回転軸１０２を各内輪１０５ｂ，１０６ｂで接触して支承し、いわゆるタッチダウンさせるものである。また、保護用玉軸受１０５，１０６の内、外輪１０５ａ，１０５ｂ，１０６ａ，１０６ｂは、例えばＳＵＳ４４０Ｃ材で、玉１０７，１０８はセラミックス材あるいはＳＵＳ４４０Ｃ材で形成され、玉１０７，１０８の表面には、銀などのコーティング膜が被覆されている。
【０００３】
【発明が解決しようとする課題】
上記の従来の磁気軸受装置においては、上側の保護用玉軸受５の内輪５ｂ内周面と回転軸２外周面間のラジアル方向隙間Ｓ１と、下側の保護用玉軸受６の内輪６ｂ内周面と回転軸２外周面間のラジアル方向隙間Ｓ２とは、通常同一隙間（半径で０．１〜０．２５ｍｍ）と設定されている。ところで、回転軸２のタッチダウン時の振れ回りが回転軸重心Ｇを中心に行われるため、回転軸２の重心位置により回転軸２の上部と下部とで振れ回り半径が相違する。例えば、図５の模式図においては、回転軸２の重心Ｇ位置が下方にあるため、回転軸２の上部の振れ回り半径ｒ１が下部の振れ回り半径ｒ２より大きくなることがわかる。このような回転軸２の上部と下部とで振れ回り半径が相違すると、各保護用玉軸受５，６の内輪５ｂ，６ｂと回転軸２とのラジアル方向隙間Ｓ１，Ｓ２が上述のように同一であることから、振れ回りが大きい回転軸２部位とその部位に対向する内輪のみが接触して減速するため、一方の保護用玉軸受のみが早期に破損することがある。
【０００４】
従って、図４においては、上側の保護用玉軸受５と下側の保護用玉軸受６間の距離Ｌの半分である１／２×Ｌの位置（中間位置）よりも下方に、回転軸２の重心Ｇが位置しており、回転軸２が図５の模式図のように上方で大きく振れ回り、その結果、回転軸２が上側の保護用玉軸受５の内輪５ｂのみに接触して減速するため、上側の保護用玉軸受５のみが早期破損することがある。
【０００５】
そこで、この発明は、上下の保護用玉軸受で回転体をほぼ同時に接触させて、一方の保護用玉軸受のみの早期破損を防止する磁気軸受装置を提供することを目的としている。
【０００６】
【課題を解決するための手段】
上記課題を解決するための手段として、回転体をラジアル磁気軸受とアキシアル磁気軸受とにより非接触状態に支持する固定部分の軸方向に離間し上記回転体の重心を軸方向に挟んだ２箇所に、回転体の停止時に回転体を支承する深溝玉軸受からなる第１の保護用玉軸受と、斜接玉軸受を２個合わせた第２の保護用玉軸受とをそれぞれ配設し、上記第１の保護用玉軸受は、上記重心より軸方向上側にてその外輪を上記固定部分に固定するとともにその内輪の内径と上記回転体との間にラジアル隙間を有し、上記第２の保護用玉軸受は、上記重心より軸方向下側でかつ上記アキシアル磁気軸受より軸方向上方の位置にてその外輪を上記固定部分に固定するとともにその内輪の内径と上記回転体との間にラジアル隙間を有し、かつ上記内輪は、上記回転体のアキシアル負荷を受けられるよう上記回転体に設けられた上記内輪より大径の段部に対向している磁気軸受装置において、上記第１の保護用玉軸受と上記回転体の重心との間に第１のラジアル磁気軸受を配設するとともに、上記第２の保護用玉軸受と上記回転体の重心との間に第２のラジアル磁気軸受を配設し、上記回転体の重心と上記第１の保護用玉軸受との距離を、上記回転体の重心と上記第２の保護用玉軸受との距離より遠いものとし、回転体の重心から遠い側の上記第１の保護用玉軸受の内輪の内径と回転体間のラジアル方向隙間を、他方の上記第２の保護用玉軸受の内輪の内径と回転体間のラジアル隙間よりも大きくしたことを特徴とする。
上記の磁気軸受装置においては、さらに、上記第１の保護用玉軸受および上記第２の保護用玉軸受の少なくとも一方の玉の表面に固体潤滑剤が被覆されている構成としてもよい。
【０００７】
【発明の実施の形態】
以下、この発明の具体的実施の形態について図１を参照して説明する。
なお、本願発明の実施形態は、従来構造の図４と同一構造であるため、同一部品には同一符号を付して重複構造説明は避け、特徴事項について説明する。この実施形態においては、回転軸２の重心Ｇが上側の保護用玉軸受５よりも下側の保護用玉軸受６の方に位置している。すなわち、回転軸２の重心Ｇが、上側の保護用玉軸受５と下側の保護用玉軸受６間の距離Ｌの半分である１／２×Ｌの位置（中間位置）よりも下方に位置している。そして、上側の保護用玉軸受５の内輪５ｂ内周面と回転軸２外周面間のラジアル方向隙間Ｓ３を、下側の保護用玉軸受６の内輪６ｂ内周面と回転軸２外周面間のラジアル方向隙間Ｓ４（半径で０．１〜０．２５ｍｍ）よりも半径で０．１ｍｍ以上大きく設定されている。これは模式図である図２においてより理解される。従って、回転軸２のタッチダウン時に、回転軸２が模式図５と同様に上方で大きくなるが、上述のように上側の保護用玉軸受５の内輪５ｂ内周面と回転軸２外周面間のラジアル方向隙間Ｓ３を、下側の保護用玉軸受６の内輪６ｂ内周面と回転軸２外周面間のラジアル方向隙間Ｓ４よりも大きく設定されているため、回転軸２が上下の保護用玉軸受５，６の内輪５ｂ，６ｂとほぼ同時に接触させて減速させることができる。このため、従来のような一方の軸受内輪のみの接触での減速がなくなり、保護用玉軸受５，６の早期破損が防止される。また、１回のタッチダウン減速時間が短くなり、玉７，８の表面にコーティング膜して被覆された銀などの固体潤滑剤の消費が抑えられ、保護用玉軸受５，６の長寿命化が図れる。さらには、タッチダウン減速時間の短縮により、保護用玉軸受５，６の昇温が抑えられ、軸受内部の隙間づまりが発生しにくくなる。
【０００８】
また、別の実施形態は、模式図である図３においてよく判る。この実施形態では、図１の実施形態とは反対に、回転軸２の重心Ｇが上側の保護用玉軸受５の方に位置されている。従って、回転軸２の下方の振れ回りの方が大きくなるため、下側の保護用玉軸受６の内輪６ｂ内周面と回転軸２外周面間のラジアル方向隙間Ｓ６を、上側の保護用玉軸受５の内輪５ｂ内周面と回転軸２外周面間のラジアル方向隙間Ｓ５（半径で０．１〜０．２５ｍｍ）よりも半径で０．１ｍｍ以上大きく設定されている。この構成による効果は上述の図１の場合と同様である。
なお、保護用玉軸受５，６としては、いずれにも深溝玉軸受、斜接玉軸受が適宜用いられる。また、玉軸受は、総玉タイプの他玉保持用の保持器つきであってもよい。
【０００９】
【発明の効果】
このように、本発明では、回転体のタッチダウン時、軸方向両側の保護用玉軸受で回転体をほぼ同時に接触させることができ、軸受の早期の破損が防止される。
【図面の簡単な説明】
【図１】本発明の一実施形態の磁気軸受装置の断面図である。
【図２】図１の磁気軸受装置の模式図である。
【図３】本発明の別の実施形態の模式図である。
【図４】（Ａ）は従来の磁気軸受装置の断面図、（Ｂ），（Ｃ）はそれぞれ保護用玉軸受の拡大図である。
【図５】図４の磁気軸受装置の模式図である。
【符号の説明】
１ ケーシング
２ 回転軸
３ 磁気軸受
４ 磁気軸受
５ 保護用玉軸受
６ 保護用玉軸受
７ 玉
８ 玉
Ｇ 重心[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic bearing device that supports a rotating part that rotates at high speed, such as a turbo molecular pump.
[0002]
[Prior art]
For example, a conventional magnetic bearing device shown in FIG. 4A is known. That is, a shaft 102 as a rotating body is inserted into a cylindrical casing 101 as a fixed portion. The rotating shaft 102 is supported in a non-contact manner by a pair of radial magnetic bearings 103 and a pair of axial magnetic bearings 104 disposed on the inner peripheral surface 101a of the casing 101, and has a high speed of, for example, about 30,000 to 40,000 rpm. Rotate with. When the rotating shaft 102 is stopped, if the rotating shaft 102 rotating at high speed comes into contact with the magnetic bearings 103 and 104, there is a risk that the magnetic bearings 103 and 104 are damaged. For this reason, the ball bearings 105 and 106 for protection which are spaced apart in two places on the upper and lower sides of the casing 101, support the rotary shaft 102 when the rotary shaft 102 is stopped, and prevent the rotary shaft 102 from contacting the magnetic bearings 103 and 104. Is provided. For example, a deep groove type full ball bearing as shown in FIG. 4B is used for the upper protection ball bearing 105, and the lower protection ball bearing 106 is also subjected to an axial load as shown in FIG. Two oblique contact ball bearings as shown in (C) are used face-to-face, each outer ring 105a, 106a is fixed to the casing 101, and each inner ring 105b, 106b is opposed to the rotating body with a gap. It has been. When the rotary shaft 102 is stopped, the rotary shaft 102 is contacted and supported by the inner rings 105b and 106b, so-called touchdown is performed. Of the protective ball bearings 105, 106, the outer rings 105a, 105b, 106a, 106b are made of, for example, a SUS440C material, and the balls 107, 108 are made of a ceramic material or a SUS440C material. A coating film such as silver is coated.
[0003]
[Problems to be solved by the invention]
In the above conventional magnetic bearing device, the radial clearance S1 between the inner peripheral surface of the inner ring 5b of the upper protective ball bearing 5 and the outer peripheral surface of the rotary shaft 2, and the inner periphery of the inner ring 6b of the lower protective ball bearing 6 The radial clearance S2 between the surface and the outer peripheral surface of the rotating shaft 2 is normally set to the same clearance (0.1 to 0.25 mm in radius). By the way, since the whirling of the rotating shaft 2 at the time of touchdown is performed around the rotating shaft center of gravity G, the swinging radius is different between the upper portion and the lower portion of the rotating shaft 2 depending on the position of the center of gravity of the rotating shaft 2. For example, in the schematic diagram of FIG. 5, since the center of gravity G position of the rotating shaft 2 is below, it can be seen that the upper turning radius r1 of the rotating shaft 2 is larger than the lower turning radius r2. When the swing radius is different between the upper part and the lower part of the rotary shaft 2, the radial clearances S1 and S2 between the inner rings 5b and 6b of the protective ball bearings 5 and 6 and the rotary shaft 2 are the same as described above. For this reason, since only the portion of the rotating shaft 2 with a large run-out and the inner ring facing the portion are brought into contact with each other and decelerated, only one of the protective ball bearings may be damaged early.
[0004]
Accordingly, in FIG. 4, the rotary shaft 2 is positioned below a position of 1/2 × L (intermediate position) that is half the distance L between the upper protective ball bearing 5 and the lower protective ball bearing 6. The center of gravity G of the rotating shaft 2 is located, and the rotating shaft 2 swings upward as shown in the schematic diagram of FIG. 5. As a result, the rotating shaft 2 comes into contact with only the inner ring 5 b of the upper protective ball bearing 5 and decelerates. Therefore, only the upper protective ball bearing 5 may be damaged early.
[0005]
Accordingly, an object of the present invention is to provide a magnetic bearing device in which a rotating body is brought into contact with upper and lower protective ball bearings almost simultaneously to prevent early breakage of only one protective ball bearing.
[0006]
[Means for Solving the Problems]
As means for solving the above-mentioned problems, the rotating body is separated in the axial direction of a fixed portion that supports the rotating body in a non-contact state by a radial magnetic bearing and an axial magnetic bearing, and the center of gravity of the rotating body is sandwiched in two axial directions. A first protective ball bearing comprising a deep groove ball bearing that supports the rotating body when the rotating body is stopped, and a second protective ball bearing comprising two oblique contact ball bearings . The protective ball bearing No. 1 has an outer ring fixed to the fixed portion axially above the center of gravity and a radial gap between the inner ring inner diameter and the rotating body, and the second protective ball bearing The ball bearing fixes its outer ring to the fixed portion at a position axially below the center of gravity and above the axial magnetic bearing, and has a radial clearance between the inner diameter of the inner ring and the rotating body. And the inner ring is A magnetic bearing device from the inner ring provided on the rotating body so as to receive the axial load of the rotary member facing the stepped portion of large diameter, the center of gravity of the first protective ball bearings and said rotary member A first radial magnetic bearing is disposed therebetween, a second radial magnetic bearing is disposed between the second protective ball bearing and the center of gravity of the rotating body, and the center of gravity of the rotating body and the above-mentioned The distance between the first protective ball bearing and the first protective ball bearing is greater than the distance between the center of gravity of the rotating body and the second protective ball bearing, and the first protective ball bearing on the side farther from the center of gravity of the rotating body. an inner ring having an inner diameter of the radial clearance between the rotating body and is characterized in that it is larger than the radial clearance between the other of the second inner ring having an inner diameter of the protective ball bearing rotor.
In the magnetic bearing device, a solid lubricant may be coated on the surface of at least one of the first protective ball bearing and the second protective ball bearing.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
A specific embodiment of the present invention will be described below with reference to FIG.
In addition, since embodiment of this invention is the same structure as FIG. 4 of a prior art structure, the same code | symbol is attached | subjected to the same component, duplication structure description is avoided and a characteristic matter is demonstrated. In this embodiment, the center of gravity G of the rotary shaft 2 is located on the lower protective ball bearing 6 relative to the upper protective ball bearing 5. That is, the center of gravity G of the rotary shaft 2 is positioned below a position of 1/2 × L (intermediate position) that is half the distance L between the upper protective ball bearing 5 and the lower protective ball bearing 6. is doing. Then, a radial clearance S3 between the inner peripheral surface of the inner ring 5b of the upper protective ball bearing 5 and the outer peripheral surface of the rotary shaft 2 is defined between the inner peripheral surface of the inner ring 6b of the lower protective ball bearing 6 and the outer peripheral surface of the rotary shaft 2. Is set to be larger by 0.1 mm or more than the radial clearance S4 (0.1 to 0.25 mm in radius). This is better understood in FIG. 2, which is a schematic diagram. Therefore, when the rotary shaft 2 is touched down, the rotary shaft 2 becomes larger upward as in the schematic diagram 5. However, as described above, between the inner peripheral surface of the inner ring 5 b of the upper protective ball bearing 5 and the outer peripheral surface of the rotary shaft 2. The radial clearance S3 is set larger than the radial clearance S4 between the inner peripheral surface of the inner ring 6b of the lower protective ball bearing 6 and the outer peripheral surface of the rotary shaft 2, so that the rotary shaft 2 is used for upper and lower protection. The ball bearings 5 and 6 can be decelerated by being brought into contact with the inner rings 5b and 6b of the ball bearings 5 and 6 almost simultaneously. For this reason, there is no deceleration due to the contact of only one bearing inner ring as in the prior art, and early breakage of the protective ball bearings 5 and 6 is prevented. In addition, the time for one touch-down deceleration is shortened, the consumption of solid lubricant such as silver coated on the surface of the balls 7 and 8 is suppressed, and the life of the protective ball bearings 5 and 6 is extended. Can be planned. Furthermore, the shortening of the touch-down deceleration time suppresses the temperature rise of the protective ball bearings 5 and 6 and makes it difficult for gaps inside the bearing to be clogged.
[0008]
Another embodiment is best seen in FIG. 3, which is a schematic diagram. In this embodiment, contrary to the embodiment of FIG. 1, the center of gravity G of the rotating shaft 2 is located toward the upper protective ball bearing 5. Accordingly, since the downward swing of the rotary shaft 2 becomes larger, the radial clearance S6 between the inner peripheral surface of the inner ring 6b of the lower protective ball bearing 6 and the outer peripheral surface of the rotary shaft 2 is changed to the upper protective ball. The radial clearance S5 (0.1 to 0.25 mm in radius) between the inner peripheral surface of the inner ring 5b of the bearing 5 and the outer peripheral surface of the rotary shaft 2 is set to be 0.1 mm or more larger in radius. The effect of this configuration is the same as in the case of FIG.
As the protective ball bearings 5 and 6, deep groove ball bearings and oblique contact ball bearings are used as appropriate. The ball bearing may be provided with a cage for holding other balls of the total ball type.
[0009]
【The invention's effect】
Thus, in the present invention, when touchdown of the rotating body, it is possible to substantially simultaneously contacted the rotating body in the axial direction on both sides of the protective ball bearing, premature failure of the bearing is prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a magnetic bearing device according to an embodiment of the present invention.
2 is a schematic diagram of the magnetic bearing device of FIG. 1. FIG.
FIG. 3 is a schematic view of another embodiment of the present invention.
4A is a cross-sectional view of a conventional magnetic bearing device, and FIGS. 4B and 4C are enlarged views of protective ball bearings, respectively.
5 is a schematic diagram of the magnetic bearing device of FIG. 4. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Casing 2 Rotating shaft 3 Magnetic bearing 4 Magnetic bearing 5 Protective ball bearing 6 Protective ball bearing 7 Ball 8 Ball G Center of gravity

Claims (2)

回転体をラジアル磁気軸受とアキシアル磁気軸受とにより非接触状態に支持する固定部分の軸方向に離間し上記回転体の重心を軸方向に挟んだ２箇所に、回転体の停止時に回転体を支承する深溝玉軸受からなる第１の保護用玉軸受と、斜接玉軸受を２個合わせた第２の保護用玉軸受とをそれぞれ配設し、上記第１の保護用玉軸受は、上記重心より軸方向上側にてその外輪を上記固定部分に固定するとともにその内輪の内径と上記回転体との間にラジアル隙間を有し、上記第２の保護用玉軸受は、上記重心より軸方向下側でかつ上記アキシアル磁気軸受より軸方向上方の位置にてその外輪を上記固定部分に固定するとともにその内輪の内径と上記回転体との間にラジアル隙間を有し、かつ上記内輪は、上記回転体のアキシアル負荷を受けられるよう上記回転体に設けられた上記内輪より大径の段部に対向している磁気軸受装置において、
上記第１の保護用玉軸受と上記回転体の重心との間に第１のラジアル磁気軸受を配設するとともに、上記第２の保護用玉軸受と上記回転体の重心との間に第２のラジアル磁気軸受を配設し、
上記回転体の重心と上記第１の保護用玉軸受との距離を、上記回転体の重心と上記第２の保護用玉軸受との距離より遠いものとし、
回転体の重心から遠い側の上記第１の保護用玉軸受の内輪の内径と回転体間のラジアル方向隙間を、他方の上記第２の保護用玉軸受の内輪の内径と回転体間のラジアル隙間よりも大きくしたことを特徴とする磁気軸受装置。The rotating body is supported when the rotating body is stopped at two locations that are spaced apart in the axial direction of the fixed part that supports the rotating body in a non-contact state by a radial magnetic bearing and an axial magnetic bearing and sandwiches the center of gravity of the rotating body in the axial direction. A first protective ball bearing composed of a deep groove ball bearing and a second protective ball bearing in which two oblique contact ball bearings are combined, and the first protective ball bearing includes the center of gravity. The outer ring is fixed to the fixed part on the upper side in the axial direction, and a radial gap is provided between the inner diameter of the inner ring and the rotating body. The second protective ball bearing is axially lower than the center of gravity. The outer ring is fixed to the fixed portion at a position axially above the axial magnetic bearing and has a radial clearance between the inner diameter of the inner ring and the rotating body, and the inner ring Can receive the axial load of the body A magnetic bearing device facing the stepped portion of larger diameter than the inner ring provided in the Hare said rotary member,
A first radial magnetic bearing is disposed between the first protective ball bearing and the center of gravity of the rotating body, and a second is disposed between the second protective ball bearing and the center of gravity of the rotating body. Of radial magnetic bearings,
The distance between the center of gravity of the rotating body and the first protective ball bearing is farther than the distance between the center of gravity of the rotating body and the second protective ball bearing,
An inner ring having an inner diameter on the far side of the first protective ball bearings from the center of gravity of the rotor and the radial clearance between the rotating body, radial between rotor and the other of the second inner ring having an inner diameter of the protective ball bearings A magnetic bearing device characterized by being larger than the gap. 請求項１に記載の磁気軸受装置において、
上記第１の保護用玉軸受および上記第２の保護用玉軸受の少なくとも一方の玉の表面に固体潤滑剤が被覆されていることを特徴とする磁気軸受装置。The magnetic bearing device according to claim 1,
A magnetic bearing device, wherein a solid lubricant is coated on a surface of at least one of the first protective ball bearing and the second protective ball bearing.
JP19351799A 1999-06-03 1999-06-03 Magnetic bearing device Expired - Fee Related JP3988325B2 (en)

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