JP2821592B2 - Radial ball bearings for protection in magnetic bearing devices - Google Patents

Radial ball bearings for protection in magnetic bearing devices

Info

Publication number
JP2821592B2
JP2821592B2 JP62123216A JP12321687A JP2821592B2 JP 2821592 B2 JP2821592 B2 JP 2821592B2 JP 62123216 A JP62123216 A JP 62123216A JP 12321687 A JP12321687 A JP 12321687A JP 2821592 B2 JP2821592 B2 JP 2821592B2
Authority
JP
Japan
Prior art keywords
bearing
ring
ball
coated
outer ring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP62123216A
Other languages
Japanese (ja)
Other versions
JPS63289319A (en
Inventor
善久 川上
正章 大槻
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koyo Seiko Co Ltd
Original Assignee
Koyo Seiko Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koyo Seiko Co Ltd filed Critical Koyo Seiko Co Ltd
Priority to JP62123216A priority Critical patent/JP2821592B2/en
Publication of JPS63289319A publication Critical patent/JPS63289319A/en
Application granted granted Critical
Publication of JP2821592B2 publication Critical patent/JP2821592B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • 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
    • 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
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/02—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
    • F16C19/04—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for radial load mainly
    • F16C19/06—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for radial load mainly with a single row or balls
    • 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
    • F16C2240/00—Specified values or numerical ranges of parameters; Relations between them
    • F16C2240/40—Linear dimensions, e.g. length, radius, thickness, gap
    • 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
    • F16C2300/00—Application independent of particular apparatuses
    • F16C2300/40—Application independent of particular apparatuses related to environment, i.e. operating conditions
    • F16C2300/62—Application independent of particular apparatuses related to environment, i.e. operating conditions low pressure, e.g. elements operating under vacuum conditions

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Rolling Contact Bearings (AREA)
  • Sliding-Contact Bearings (AREA)
  • Magnetic Bearings And Hydrostatic Bearings (AREA)

Description

【発明の詳細な説明】 産業上の利用分野 この発明は、たとえば真空ポンプなどの磁気軸受装置
における保護用玉軸受に関する。 従来の技術とその問題点 第４図は従来の磁気軸受装置の１例を示し、垂直固定
軸（１）の周囲に円筒状のロータ（２）が配置されてい
る。ロータ（２）は、固定軸（１）に設けられたラジア
ル磁気軸受（３）（４）およびアキシアル磁気軸受
（５）（６）で非接触状態に支持され、たとえば30000r
pm程度の高速で回転する。固定軸（１）の上下２箇所
に、ロータ（２）の停止時にこれを受けるための保護用
玉軸受（７）（８）が設けられている。各保護用軸受
（７）（８）には負荷能力を増すため総玉軸受が使用さ
れ、その内輪（7a）（8a）が固定軸（１）に固定されて
いる。ロータ（２）が正常に回転しているときは、ロー
タ（２）と保護用軸受（７）（８）の外輪（7b）（8b）
との間にはたとえば0.1〜数mm程度のすきまがある。そ
して、ロータ（２）が停止するときには、ロータ（２）
が保護用軸受（７）（８）の外輪（7b）（8b）に接触し
てこれに受けられ、ロータ（２）が磁気軸受（３）
（４）（５）（６）などに接触してこれらを損傷しない
ようになっている。なお、このようにロータが保護用軸
受に受けられて停止する動作をタッチダウンという。 ところで、磁気軸受装置が正常な状態で停止する場
合、ロータ（２）は徐々に減速され、かなり低速になっ
てから保護用軸受（７）（８）の外輪（7b）（8b）に接
触して低速でタッチダウンするため、保護用軸受（７）
（８）が損傷することはない。これに対し、停電その他
の故障により磁気軸受（３）（４）（５）（６）が作用
しなくなった場合は、高速で回転しているロータ（２）
が保護用軸受（７）（８）の外輪（7b）（8b）に接触し
て高速でタッチダウンするため、とくに真空ポンプの磁
気軸受装置の場合、保護用軸受（７）（８）の外輪（7
b）（8b）が真空中（たとえば10-2〜10-3Torr）におい
て急激な立上りで高速回転（たとえばdmn＞300×104）
することになる。このため、従来の保護用軸受（７）
（８）では、玉（7c）（8c）ならびに内輪（7a）（8a）
および外輪（7b）（8b）が摩耗しやすく、耐久性が劣っ
ており、１回の高速タッチダウンの途中で保護用軸受
（７）（８）が損傷するというような問題があった。 磁気軸受装置には、上記のように固定軸の周囲を筒状
のローラが回転する形式の他に、筒状の固定ケースの内
側をロータ軸が回転する形式もある。この場合、ケース
の上下２箇所に保護用玉軸受が設けられ、軸が停止する
ときに、軸が保護用軸受の内輪に接触してこれに受けら
れるが、上記と同様の問題がある。 この発明の目的は、上記のような問題を解決した耐久
性の高い保護用玉軸受を提供することにある。 問題点を解決するための手段 この発明による保護用玉軸受は、固定部分に対し回転
部分を磁気軸受で非接触状態に支持して回転させる磁気
軸受装置において、回転部分の停止時に回転部分を受け
るために固定部分の複数箇所に設けられる保護用玉軸受
であって、軌道輪の軌道みぞに第１の固定潤滑剤がコー
ティングされ、回転部分に対向する軌道輪の周面、端面
および両者をつなぐコーナー部に第２の固定潤滑剤がコ
ーティングされており、回転部分のタッチダウン時に、
回転部分に対向する軌道輪の第２の固定潤滑剤により回
転部分と軌道輪のすべりを助長し、軌道輪の回転立上り
が緩やかに行われるようになされていることを特徴とす
るものである。 作用 高速タッチダウン時に回転部分が高速回転状態のまま
保護用玉軸受の軌道輪に接触すると、この軌道輪も高速
で回転を開始するが、この発明による保護用玉軸受の場
合は、軌道輪の軌道みぞに第１の固体潤滑剤がコーティ
ングされ、回転部分に対向する軌道輪の周面、端面およ
び両者をつなぐコーナー部に固体潤滑剤がコーティング
されて、回転部分のタッチダウン時に、第２の固定潤滑
剤により回転部分と軌道輪のすべりを助長し、軌道輪の
回転立上りが緩やかに行われるようになされているか
ら、耐久性が高く、損傷を受けにくい。すなわち、タッ
チダウン時には、回転部分は保護用玉軸受の軌道輪の周
面および周面と端面との間のコーナー部に接触し、場合
によっては端面にも接触する。このとき、この発明によ
る保護用玉軸受の場合は、回転部分に対向する軌道輪の
周面、端面および両者をつなぐコーナー部にコーティン
グされた第２の固定潤滑剤が回転部分と軌道輪の間のす
べりを助長し、これにより、高速タッチダウン時の軌道
輪の回転立上りが緩やかになり、軌道輪の最高回転数が
小さくなる。また、軌道輪の軌道みぞにコーティングさ
れた第１の固体潤滑剤が玉との間の潤滑剤となり、玉の
回転が滑らかで、玉および軌道みぞの耐摩耗性が向上す
る。したがって、保護用玉軸受の耐久性が向上し、高速
タッチダウン時の保護用玉軸受の損傷の度合いが小さく
なる。なお、回転部分に対向する軌道輪の周面にしか第
２の固定潤滑剤がコーティングされていなければ、回転
部分が上記コーナー部において固体潤滑剤の端部に接触
し、固体潤滑剤がこの部分から剥がれるおそれがある
が、この発明による保護用玉軸受の場合は、回転部分に
対向する軌道輪の周面、端面および両者をつなぐコーナ
ー部に第２の固体潤滑剤がコーティングされているの
で、固体潤滑剤が剥がれるおそれがなく、上記の効果が
持続される。 実 施 例 以下、図面を参照して、この発明の実施例について説
明する。 第１図は、磁気軸受装置の保護用ラジアル玉軸受の１
具体例を示す。 この軸受（10）は総玉軸受であり、玉（11）は全てセ
ラミック製である。また、通常のラジアル玉軸受に比べ
て玉（11）の直径Daは小さく、内輪（12）の肉厚tiは薄
く、外輪（13）の肉厚teは厚くなっている。したがっ
て、玉（11）の中心（０）を通る円の直径（ピッチ円
径）dpは内輪（12）の内径（軸受内径）ｄと外輪（13）
の外径（軸受外径）Ｄの和の半分（平均径）dmよりかな
り小さくなっている。これらの寸法の１例を挙げれば、
軸受内径ｄを90mm、軸受外径Ｄを115mm、平均径dmを10
2.5mm、内輪（12）の肉厚tiを3mm、外輪（13）の肉厚te
を6mm、ピッチ円径dpを平均径dmより2.5mm小さくして10
0mmとし、玉（11）の直径Daを通常の6.747mmより小さく
設定している。 内輪（12）の軌道みぞ（14）の曲率半径（みぞ半径）
riは通常のものより大きく、たとえば約0.55Daとなって
いる。また、内輪（12）および外輪（13）の全表面に固
体潤滑剤たとえば二硫化モリブテンがコーティングされ
ている。したがって、軌道輪（内輪（12）あるいは外輪
（13））の軌道みぞ（14）（15）ならびに回転部分の対
向する軌道輪の周面、端面および両者をつなぐコーナー
部に固体潤滑剤がコーティングされていることになる。
軌道輪の軌道みぞ（14）（15）にコーティングされた固
体潤滑剤を第１の固体潤滑剤、回転部分に対向する軌道
輪の周面、端面および両者をつなぐコーナー部にコーテ
ィングされた固体潤滑剤を第２の固体潤滑剤という。 この軸受（10）を第４図のように固定軸の周囲を筒状
のロータが回転する形式の磁気軸受装置に使用する場
合、内輪（12）が固定軸に固定され、外輪（13）がロー
タに対向する。そして、この場合も、内輪（12）および
外輪（13）の全表面に固体潤滑剤がコーティングされて
いるため、内輪（12）および外輪（13）の軌道みぞ（1
4）（15）に第１の固体潤滑剤がコーティングされ、ロ
ータに対向する外輪（13）の周面（外周面）、端面およ
び両者をつなぐコーナー部に第２の固体潤滑剤がコーテ
ィングされていることになる。 ロータが正常に回転している場合、ロータは磁気軸受
により非接触状態に支持され、ロータと軸受（10）の外
輪（13）との間には適当なすきまがあり、外輪（13）は
停止している。 高速タッチダウンの場合、高速で回転しているロータ
が軸受（10）の外輪（13）に接触し、外輪（13）も高速
で回転を開始する。このため、従来の軸受では、外輪は
第２図に破線（Ａ）で示すように非常に急激な立上りで
高速回転を開始し、外輪の最高回転数（ａ）はロータの
回転数（ｃ）に近くなる。このため、前述のように、軸
受が損傷する。なお、第２図において、鎖線（Ｃ）はロ
ータの回転数の変化を示す。 ところが、上記の軸受（10）の場合、次に説明するよ
うに、耐久性が高く、このような損傷を防止することが
できる。 すなわち、まず、玉（11）がセラミック製であるか
ら、硬さが高く、耐摩耗性が向上する。セラミックは密
度が小さいので、玉（11）に作用する遠心力が小さく、
玉（11）と外輪（13）の間の接触面圧が小さくなる。セ
ラミックは線膨脹係数が小さいため、発熱による軸受す
きま変化が鋼製の玉に比べて小さい。また、セラミック
は弾性係数が大きいため、玉（11）の変形が小さく、回
転がなめらかとなる。したがって、玉（11）をセラミッ
ク製にすることにより、耐久性が向上する。 このことを証明するため、内輪、外輪および玉が軸受
鋼製の通常のラジアル玉軸受（比較例）と、比較例と寸
法、形状が同一で玉だけがセラミック製のラジアル玉軸
受（実施例）とを準備し、これらを使用した磁気軸受装
置について、高速タッチダウンを行なった。その結果を
第３図に示す。この試験より、比較例のものは１回のタ
ッチダウンでしかも３分程度で損傷したが、実施例のも
のは、数回のタッチダウンで合計60分以上の作動が可能
であり、比較例に比べて20倍以上の耐久性のあることが
明らかになった。 上記の軸受（10）では、内輪（12）および外輪（13）
の全表面に固体潤滑剤がコーティングされているため、
とくに軌道みぞ（14）（15）に第１の固体潤滑剤がコー
ティングされ、ロータに対向する外輪（13）の外周面、
端面および両者をつなぐコーナー部に第２の固体潤滑剤
がコーティングされて、回転部分のタッチダウン時に、
第２の固体潤滑剤により回転部分と軌道輪のすべりを助
長し、軌道輪の回転立上りが緩やかに行われるようにな
されているため、次のような効果が奏される。タッチダ
ウン時には、ロータは軸受（10）の外輪（13）の外周面
および外周面と端面との間のコーナー部に接触し、場合
によっては端面にも接触するが、外輪（13）の外周面、
端面および両者の間のコーナー部にコーティングされた
第２の固体潤滑剤がロータと外輪（13）の間のすべりを
助長するため、第２図に実線（Ｂ）で示すように高速タ
ッチダウン時の外輪（13）の回転立上りは緩やかにな
り、外輪（13）の最高回転数（ｂ）も小さくなる。そし
て、このように外輪（13）の最高回転数が小さくなるた
め、外輪（13）および玉（11）の遠心力が小さくなる。
内輪（12）および外輪（13）の軌道みぞ（14）（15）の
第１の固体潤滑剤は玉（11）との間の潤滑剤となる。し
たがって、軸受（10）の損傷の度合が小さくなる。な
お、ロータに対向する外輪（13）の外周面にしか第２の
固体潤滑剤がコーティングされていなければ、ロータが
上記コーナー部において固体潤滑剤の端部に接触し、固
体潤滑剤がこの部分から剥がれるおそれがあるが、上記
の軸受（10）の場合は、ロータに対向する外輪（13）の
外周面、端面および両者をつなぐコーナー部に第２の固
体潤滑剤がコーティングされているので、固体潤滑剤が
剥がれるおそれがなく、上記の効果が持続される。ま
た、修理などのために内輪（12）を固定軸から抜取るよ
うな場合、内輪（12）の内面にも固体潤滑剤がコーティ
ングされていて、固定軸との間の摩擦力が小さくなって
いるので、抜取りが容易である。 また、上記の軸受（10）では、内輪（12）のみぞ半径
ri（＝0.55Da）が大きくなっているので、次のような効
果が奏される。まず、タッチダウン時にロータが軸受
（10）の外輪（13）に接触する場合、軸受（10）に傾き
が生じるが、みぞ半径riを大きくすることにより許容傾
き角が大きくなり、軸受（10）内部に過大な応力が発生
しなくなる。そして、同じ傾き角の場合では、みぞ半径
riが大きい方が玉（11）の公転速度差が小さく、回転が
滑らかとなる。また、みぞ半径riを大きくすることによ
り、玉（11）と軌道みぞ（14）との接触面圧が大きくな
り、高速回転への立上り時に玉（11）が最初から正常な
回転をしやすくなる。なお、みぞ半径riは0.53〜0.58Da
程度であれば上記の効果を奏する。 また、上記の軸受（10）では、外輪（13）の肉厚teが
厚くなっているので、回転時の遠心力による外輪（13）
自身の膨脹が小さく、軸受内部すきま（ラジアルすき
ま）の変化が小さいので、回転が滑らかである。そし
て、外輪（13）の肉厚teが厚くなっていることにより、
ロータと接触したときの外輪（13）の変形が小さくな
り、玉（11）に無理な力が作用しないので、回転が滑ら
かとなる。しかも、玉（11）の直径Daを小さくして玉数
を増しているので、外輪（13）の剛性が高くなる。ま
た、ピッチ円径dpが小さくなっているので、玉（11）の
公転速度が小さくなり、回転時に玉（11）に作用する遠
心力も小さくなる。このため、軸受（10）の耐久性が向
上する。 上記の軸受（10）は、筒状の固定ケースの内側をロー
タ軸が回転する形式の磁気軸受装置にも使用できる。こ
の場合、外輪（13）が固定ケースに固定され、タッチダ
ウン時にロータ軸は内輪（12）に接触する。そして、こ
の場合も、上記とほぼ同様の効果が奏される。 上記実施例では、玉（11）が全てセラミック製である
が、セラミック製の玉と鋼製の玉を組合わせて使用する
ようにしてもよい。また、上記実施例には総玉軸受を示
したが、この発明は保持器付玉軸受にも適用できる。ま
た、玉（11）の直径Da、内輪（12）および外輪（13）の
肉厚ti、teならびにピッチ円径dpは通常のラジアル玉軸
受と同程度にしてもよい。 発明の効果 この発明の磁気軸受装置における保護用玉軸受によれ
ば、軌道輪の軌道みぞに第１の固体潤滑剤がコーティン
グされ、回転部分に対向する軌道輪の周面、端面および
両者をつなぐコーナー部に第２の固体潤滑剤がコーティ
ングされて、回転部分のタッチダウン時に、第２の固体
潤滑剤により回転部分と軌道輪のすべりを助長し、軌道
輪の回転立上りが緩やかに行われるようになされている
から、上述のように、耐久性が高く、高速タッチダウン
時の損傷を防止することができる。Description: TECHNICAL FIELD The present invention relates to a protective ball bearing in a magnetic bearing device such as a vacuum pump. FIG. 4 shows an example of a conventional magnetic bearing device, in which a cylindrical rotor (2) is arranged around a vertical fixed shaft (1). The rotor (2) is supported in a non-contact state by radial magnetic bearings (3) and (4) and axial magnetic bearings (5) and (6) provided on the fixed shaft (1).
It rotates at a high speed of about pm. Protective ball bearings (7) and (8) are provided at two locations above and below the fixed shaft (1) to receive the rotor (2) when it stops. For the protection bearings (7) and (8), full ball bearings are used to increase the load capacity, and the inner rings (7a) and (8a) are fixed to the fixed shaft (1). When the rotor (2) is rotating normally, the outer ring (7b) (8b) of the rotor (2) and the protective bearing (7) (8)
Is between 0.1 and several mm, for example. When the rotor (2) stops, the rotor (2)
Contacts the outer races (7b) and (8b) of the protective bearings (7) and (8) and is received by the outer races (7b) and (8b).
(4) (5), (6), etc., so as not to damage them. The operation in which the rotor is stopped by being received by the protective bearing is called touch-down. By the way, when the magnetic bearing device stops in a normal state, the rotor (2) is gradually decelerated and reaches a considerably low speed before contacting the outer rings (7b) (8b) of the protective bearings (7) (8). Bearings for touch down at low speed (7)
(8) is not damaged. On the other hand, when the magnetic bearings (3), (4), (5), and (6) stop working due to a power failure or other failure, the rotor (2) rotating at a high speed.
Touches the outer rings (7b) and (8b) of the protective bearings (7) and (8) at a high speed, so that the outer ring of the protective bearings (7) and (8) is used, especially in the case of a magnetic bearing device of a vacuum pump. (7
b) (8b) rotates at a rapid rise and high speed in vacuum (eg, 10 -2 to 10 -3 Torr) (eg, dmn> 300 × 10 4 )
Will do. For this reason, the conventional protective bearing (7)
In (8), balls (7c) (8c) and inner rings (7a) (8a)
In addition, the outer rings (7b) and (8b) are liable to be worn and have poor durability, and there is a problem that the protective bearings (7) and (8) are damaged during one high-speed touchdown. In the magnetic bearing device, in addition to the type in which the cylindrical roller rotates around the fixed shaft as described above, there is also a type in which the rotor shaft rotates inside the cylindrical fixed case. In this case, protective ball bearings are provided at the upper and lower portions of the case, and when the shaft stops, the shaft contacts and is received by the inner ring of the protective bearing. However, there is the same problem as described above. An object of the present invention is to provide a highly durable protective ball bearing that solves the above-described problems. Means for Solving the Problems A protective ball bearing according to the present invention is a magnetic bearing device that rotates while supporting a rotating part in a non-contact state with a magnetic part with respect to a fixed part, and receives the rotating part when the rotating part stops. Protection ball bearing provided at a plurality of locations of a fixed portion, wherein a first fixed lubricant is coated on a raceway of a raceway, and a circumferential surface, an end surface of the raceway facing a rotating portion and both are connected. The corner portion is coated with a second fixed lubricant, and when touching down the rotating part,
It is characterized in that the sliding of the rotating part and the bearing ring is promoted by the second fixed lubricant of the bearing ring facing the rotating part, so that the rotating rise of the bearing ring is performed gently. When the rotating part contacts the bearing ring of the protective ball bearing during the high-speed touchdown while the rotating part is in the high-speed rotation state, this bearing ring also starts rotating at a high speed. A track groove is coated with a first solid lubricant, and a circumferential surface, an end face, and a corner portion connecting the both of the track rings facing the rotating portion are coated with a solid lubricant. The fixed lubricant promotes slippage between the rotating part and the raceway, so that the raceway rises gently, so that it has high durability and is not easily damaged. That is, at the time of touchdown, the rotating portion contacts the peripheral surface of the bearing ring of the protective ball bearing and the corner portion between the peripheral surface and the end surface, and in some cases, also contacts the end surface. At this time, in the case of the ball bearing for protection according to the present invention, the second fixed lubricant coated on the peripheral surface, the end surface, and the corner portion connecting both of the bearing rings facing the rotating portion is provided between the rotating portion and the bearing ring. In this way, the rotation rise of the bearing ring at the time of high-speed touchdown becomes gentle, and the maximum rotation speed of the bearing ring is reduced. Further, the first solid lubricant coated on the raceway of the bearing ring serves as a lubricant between the ball and the ball, so that the ball rotates smoothly and the wear resistance of the ball and the raceway is improved. Therefore, the durability of the protective ball bearing is improved, and the degree of damage to the protective ball bearing during high-speed touchdown is reduced. If the second fixed lubricant is not coated only on the peripheral surface of the bearing ring facing the rotating portion, the rotating portion contacts the end of the solid lubricant at the corner, and the solid lubricant is applied to this portion. However, in the case of the ball bearing for protection according to the present invention, since the peripheral surface of the bearing ring facing the rotating part, the end surface and the corner connecting the two are coated with the second solid lubricant, There is no possibility that the solid lubricant is peeled off, and the above effect is maintained. Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a protection radial ball bearing 1 of a magnetic bearing device.
A specific example will be described. The bearing (10) is a full ball bearing, and the balls (11) are all made of ceramic. The diameter Da of the ball (11) is smaller, the thickness ti of the inner ring (12) is smaller, and the thickness te of the outer ring (13) is larger than that of a normal radial ball bearing. Accordingly, the diameter (pitch circle diameter) dp of the circle passing through the center (0) of the ball (11) is equal to the inner diameter (bearing inner diameter) d of the inner ring (12) and the outer ring (13).
Is substantially smaller than half (average diameter) dm of the sum of the outer diameters (bearing outer diameters) D. To give an example of these dimensions,
Bearing inner diameter d is 90mm, bearing outer diameter D is 115mm, average diameter dm is 10
2.5mm, inner ring (12) thickness ti 3mm, outer ring (13) thickness te
6mm, pitch circle diameter dp 2.5mm smaller than average diameter dm and 10
The diameter (Da) of the ball (11) is set smaller than the normal 6.747 mm. Curvature radius (groove radius) of raceway groove (14) of inner ring (12)
ri is larger than usual, for example, about 0.55 Da. Further, the entire surface of the inner ring (12) and the outer ring (13) is coated with a solid lubricant such as molybdenum disulfide. Therefore, solid lubricant is coated on the raceway grooves (14) (15) of the raceway ring (inner ring (12) or outer raceway (13)), and on the circumferential surface, end surface and the corners connecting the raceways facing the rotating part. Will be.
The solid lubricant coated on the raceway grooves (14) and (15) of the bearing ring is coated with the first solid lubricant, and the solid lubricant coated on the circumferential surface, the end surface of the raceway facing the rotating portion, and the corner portion connecting the both. The agent is referred to as a second solid lubricant. When this bearing (10) is used in a magnetic bearing device in which a cylindrical rotor rotates around a fixed shaft as shown in FIG. 4, the inner ring (12) is fixed to the fixed shaft, and the outer ring (13) is Facing the rotor. Also in this case, since the entire surface of the inner ring (12) and the outer ring (13) is coated with a solid lubricant, the raceway (1) of the inner ring (12) and the outer ring (13) is coated.
4) A first solid lubricant is coated on (15), and a second solid lubricant is coated on a peripheral surface (outer peripheral surface), an end surface, and a corner portion connecting the outer ring (13) facing the rotor. Will be. When the rotor is rotating normally, the rotor is supported in a non-contact state by a magnetic bearing, there is a suitable clearance between the rotor and the outer ring (13) of the bearing (10), and the outer ring (13) stops. doing. In the case of high-speed touchdown, the rotor rotating at high speed comes into contact with the outer ring (13) of the bearing (10), and the outer ring (13) also starts rotating at high speed. For this reason, in the conventional bearing, the outer ring starts high-speed rotation at a very steep rise as shown by a broken line (A) in FIG. 2, and the maximum rotation number (a) of the outer ring is equal to the rotation number (c) of the rotor. Become closer to Therefore, the bearing is damaged as described above. In FIG. 2, a chain line (C) indicates a change in the number of revolutions of the rotor. However, in the case of the bearing (10), as described below, the durability is high, and such damage can be prevented. That is, first, since the ball (11) is made of ceramic, the hardness is high and the wear resistance is improved. Since the density of ceramic is small, the centrifugal force acting on the ball (11) is small,
The contact surface pressure between the ball (11) and the outer ring (13) is reduced. Since ceramic has a small coefficient of linear expansion, the change in bearing clearance due to heat generation is smaller than that of steel balls. Further, since the ceramic has a large elastic coefficient, the deformation of the ball (11) is small and the rotation is smooth. Therefore, durability is improved by making the ball (11) made of ceramic. To prove this, a normal radial ball bearing in which the inner and outer rings and balls are made of bearing steel (Comparative Example) is a radial ball bearing in which the dimensions and shape are the same as those in the Comparative Example, and only the balls are made of ceramic (Example). Were prepared, and a high-speed touchdown was performed on the magnetic bearing device using these. FIG. 3 shows the results. According to this test, the comparative example was damaged in one touchdown and in about 3 minutes, but the example was able to operate for a total of 60 minutes or more in several touchdowns. It became clear that it was more than 20 times more durable. In the above bearing (10), the inner ring (12) and the outer ring (13)
Because the solid lubricant is coated on all surfaces of
In particular, the track grooves (14) and (15) are coated with the first solid lubricant, and the outer peripheral surface of the outer ring (13) facing the rotor,
The second solid lubricant is coated on the end face and the corner connecting the two, and at the time of touchdown of the rotating part,
The second solid lubricant promotes the sliding between the rotating part and the bearing ring, so that the rotating rise of the bearing ring is performed gently. Therefore, the following effects are obtained. At the time of touchdown, the rotor contacts the outer peripheral surface of the outer ring (13) of the bearing (10) and a corner portion between the outer peripheral surface and the end surface, and in some cases also contacts the end surface, but the outer peripheral surface of the outer ring (13). ,
Since the second solid lubricant coated on the end face and the corner between them promotes the slip between the rotor and the outer ring (13), as shown by the solid line (B) in FIG. Of the outer ring (13) becomes gentler, and the maximum rotation speed (b) of the outer ring (13) also becomes smaller. Since the maximum rotation speed of the outer ring (13) is reduced in this way, the centrifugal force of the outer ring (13) and the ball (11) is reduced.
The first solid lubricant in the raceway grooves (14) and (15) of the inner ring (12) and the outer ring (13) serves as a lubricant between the balls (11). Therefore, the degree of damage to the bearing (10) is reduced. If only the outer peripheral surface of the outer ring (13) facing the rotor is not coated with the second solid lubricant, the rotor comes into contact with the end of the solid lubricant at the corner, and the solid lubricant is applied to this portion. However, in the case of the bearing (10), since the outer peripheral surface and the end surface of the outer ring (13) facing the rotor and the corner portion connecting the both are coated with the second solid lubricant, There is no possibility that the solid lubricant is peeled off, and the above effect is maintained. Also, when removing the inner ring (12) from the fixed shaft for repair, etc., the inner surface of the inner ring (12) is also coated with solid lubricant, and the frictional force between the fixed shaft and the fixed shaft is reduced. Is easy to remove. In the above bearing (10), only the inner ring (12) has a radius
Since ri (= 0.55 Da) is large, the following effects are achieved. First, when the rotor comes into contact with the outer ring (13) of the bearing (10) at the time of touchdown, the bearing (10) tilts. However, by increasing the groove radius ri, the allowable tilt angle increases, and the bearing (10) No excessive stress is generated inside. And for the same inclination angle, the groove radius
The larger the ri, the smaller the difference in the revolving speed of the ball (11) and the smoother the rotation. In addition, by increasing the groove radius ri, the contact surface pressure between the ball (11) and the raceway groove (14) increases, so that the ball (11) can easily rotate normally from the beginning when rising to high speed rotation. . The groove radius ri is 0.53-0.58 Da
The above effect can be obtained if it is on the order. Further, in the above bearing (10), the outer ring (13) has a large thickness te, so that the outer ring (13) due to centrifugal force during rotation.
Since the expansion of the bearing itself is small and the change in the clearance inside the bearing (radial clearance) is small, the rotation is smooth. And because the outer ring (13) has a thicker wall te,
The deformation of the outer ring (13) upon contact with the rotor is reduced, and no excessive force acts on the ball (11), so that the rotation is smooth. In addition, since the number of balls is increased by reducing the diameter Da of the balls (11), the rigidity of the outer ring (13) is increased. Further, since the pitch circle diameter dp is small, the revolving speed of the ball (11) is reduced, and the centrifugal force acting on the ball (11) during rotation is also reduced. For this reason, the durability of the bearing (10) is improved. The bearing (10) can also be used for a magnetic bearing device in which a rotor shaft rotates inside a cylindrical fixed case. In this case, the outer ring (13) is fixed to the fixed case, and the rotor shaft contacts the inner ring (12) during touchdown. Also in this case, substantially the same effects as described above can be obtained. In the above embodiment, the balls (11) are all made of ceramic. However, a combination of ceramic balls and steel balls may be used. In the above embodiment, the full ball bearing is shown, but the present invention can be applied to a ball bearing with a cage. Further, the diameter Da of the ball (11), the thicknesses ti and te of the inner ring (12) and the outer ring (13), and the pitch circle diameter dp may be the same as those of a normal radial ball bearing. According to the protective ball bearing in the magnetic bearing device of the present invention, the raceway of the raceway is coated with the first solid lubricant, and the circumferential surface, the end surface of the raceway facing the rotating part, and both are connected. The corner portion is coated with a second solid lubricant so that when the rotating portion is touched down, the second solid lubricant facilitates the sliding between the rotating portion and the bearing ring, so that the rotating rise of the bearing ring is performed gently. Therefore, as described above, the durability is high, and damage at the time of high-speed touchdown can be prevented.

【図面の簡単な説明】 第１図はこの発明の実施例を示す保護用ラジアル玉軸受
の主要部縦断面図、第２図は高速タッチダウン時の外輪
の回転速度の変化を示すグラフ、第３図は比較例と実施
例の比較試験結果を示すグラフ、第４図は従来の保護用
玉軸受を組込んだ磁気軸受装置を示す縦断面図である。 （10）……保護用ラジアル玉軸受、（12）……内輪、
（13）……外輪、（14）（15）……軌道みぞ。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a main part of a protective radial ball bearing showing an embodiment of the present invention, FIG. 2 is a graph showing a change in the rotation speed of an outer ring during high-speed touchdown, FIG. FIG. 3 is a graph showing a comparison test result between the comparative example and the embodiment, and FIG. 4 is a longitudinal sectional view showing a magnetic bearing device incorporating a conventional protective ball bearing. (10) ... radial ball bearing for protection, (12) ... inner ring,
(13) ... outer ring, (14) (15) ... track grooves.

Claims (1)

(57)【特許請求の範囲】 １．固定部分に対し固定部分を磁気軸受で非接触状態に
支持して回転させる磁気軸受装置において、回転部分の
停止時に回転部分を受けるために固定部分の複数箇所に
設けられる保護用玉軸受であって、 軌道輪の軌道みぞに第１の固定潤滑剤がコーティングさ
れ、回転部分に対向する軌道輪の周面、端面および両者
をつなぐコーナー部に第２の固定潤滑剤がコーティング
されており、回転部分のタッチダウン時に、回転部分に
対向する軌道輪の第２の固定潤滑剤により回転部分と軌
道輪のすべりを助長し、軌道輪の回転立上りが緩やかに
行われるようになされていることを特徴とする磁気軸受
装置における保護用玉軸受。(57) [Claims] In a magnetic bearing device in which a fixed portion is supported by a magnetic bearing in a non-contact state with respect to the fixed portion and is rotated, the protection ball bearing is provided at a plurality of positions of the fixed portion to receive the rotating portion when the rotating portion stops. A first fixed lubricant is coated on a raceway of a bearing ring, and a second fixed lubricant is coated on a circumferential surface, an end surface, and a corner portion connecting the both surfaces facing the rotating portion; During the touchdown, the second fixed lubricant of the bearing ring facing the rotating part facilitates the sliding of the rotating part and the bearing ring, so that the rotating rise of the bearing ring is performed gently. Ball bearing for use in magnetic bearing devices.
JP62123216A 1987-05-20 1987-05-20 Radial ball bearings for protection in magnetic bearing devices Expired - Lifetime JP2821592B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP62123216A JP2821592B2 (en) 1987-05-20 1987-05-20 Radial ball bearings for protection in magnetic bearing devices

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP62123216A JP2821592B2 (en) 1987-05-20 1987-05-20 Radial ball bearings for protection in magnetic bearing devices

Publications (2)

Publication Number Publication Date
JPS63289319A JPS63289319A (en) 1988-11-25
JP2821592B2 true JP2821592B2 (en) 1998-11-05

Family

ID=14855073

Family Applications (1)

Application Number Title Priority Date Filing Date
JP62123216A Expired - Lifetime JP2821592B2 (en) 1987-05-20 1987-05-20 Radial ball bearings for protection in magnetic bearing devices

Country Status (1)

Country Link
JP (1) JP2821592B2 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2792378B1 (en) * 1999-04-16 2001-06-08 Skf France RIGID BALL BEARING

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5037704U (en) * 1973-08-02 1975-04-19
JPS6140191Y2 (en) * 1981-02-28 1986-11-17
JPS6088828U (en) * 1983-11-24 1985-06-18 トヨセツト株式会社 desk
JPS60176630U (en) * 1984-05-01 1985-11-22 コクヨ株式会社 desk
JPH0136429Y2 (en) * 1986-10-31 1989-11-06

Also Published As

Publication number Publication date
JPS63289319A (en) 1988-11-25

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