JP6687787B2 - Bearing with magnetic fluid seal - Google Patents
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- JP6687787B2 JP6687787B2 JP2019106919A JP2019106919A JP6687787B2 JP 6687787 B2 JP6687787 B2 JP 6687787B2 JP 2019106919 A JP2019106919 A JP 2019106919A JP 2019106919 A JP2019106919 A JP 2019106919A JP 6687787 B2 JP6687787 B2 JP 6687787B2
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- 239000011553 magnetic fluid Substances 0.000 title claims description 57
- 230000002093 peripheral effect Effects 0.000 claims description 31
- 238000005096 rolling process Methods 0.000 claims description 15
- 239000000696 magnetic material Substances 0.000 claims description 12
- 125000006850 spacer group Chemical group 0.000 description 17
- 230000007246 mechanism Effects 0.000 description 13
- 238000007789 sealing Methods 0.000 description 12
- 230000000717 retained effect Effects 0.000 description 9
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- 229910052742 iron Inorganic materials 0.000 description 1
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Landscapes
- Sealing Of Bearings (AREA)
- Rolling Contact Bearings (AREA)
Description
本発明は、各種の動力伝達機構に配設され、回転軸を回転自在に支持すると共に、内部に埃や水分などの異物が侵入しないようにする磁性流体シール付き軸受に関する。 The present invention relates to a bearing with a magnetic fluid seal, which is provided in various power transmission mechanisms, rotatably supports a rotating shaft, and prevents foreign matter such as dust and water from entering the inside.
一般的に、各種の駆動力伝達機構に設置される回転軸は、軸受を介して回転自在に支持されている。この場合、軸受は、内輪と外輪との間に周方向に沿って複数の転動体（転がり部材）を収容した、いわゆるボールベアリング（玉軸受）を用いることが多く、このようなタイプの軸受を用いることで、回転軸の回転性能の向上を図っている。 Generally, rotary shafts installed in various driving force transmission mechanisms are rotatably supported via bearings. In this case, as the bearing, a so-called ball bearing (ball bearing), which accommodates a plurality of rolling elements (rolling members) along the circumferential direction between the inner ring and the outer ring, is often used. By using it, the rotation performance of the rotary shaft is improved.
このような軸受は、様々な駆動装置における駆動力伝達機構の回転軸の支持手段として用いられるが、駆動装置によっては、軸受部分を通過して、内部に埃、水分等の異物の侵入を防止したいことがある。また、軸受そのものに異物が侵入すると、回転性能が劣化したり、異音が生じる等の問題が生じる。そこで、例えば、特許文献１には、磁性流体によるシール機能を備えた磁性流体シール付き軸受が開示されている。 Such a bearing is used as a support means for a rotating shaft of a driving force transmission mechanism in various driving devices. However, depending on the driving device, foreign matter such as dust and water is prevented from entering the inside by passing through the bearing portion. I have something I want to do. Further, if foreign matter enters the bearing itself, problems such as deterioration of rotational performance and generation of abnormal noise occur. Therefore, for example, Patent Document 1 discloses a bearing with a magnetic fluid seal having a sealing function of a magnetic fluid.
前記特許文献１に開示された磁性流体シール付き軸受は、リング状（環状）の磁石を取着したリング状の極板を内輪又は外輪に装着（嵌入）し、他方の外輪又は内輪に隙間を形成し、その隙間部分に磁性流体を保持することで内部への異物の侵入を防止している。なお、特許文献１に開示された磁性流体シール付き軸受は、リング状の磁石は軸方向に着磁されており、その開口側にリング状の極板を取着したものであり、このような構成では、内輪側と外輪側のそれぞれに磁気回路が形成されることから、リング状の極板（リング状の磁石）の装着側に生じている微小な隙間（以下、装着側に隙間が生じている場合、微小隙間と称する）にも磁性流体を保持し、外輪側及び内輪側から内部に異物が侵入しないようにしている。 In the bearing with a magnetic fluid seal disclosed in Patent Document 1, a ring-shaped electrode plate to which a ring-shaped (annular) magnet is attached is attached (fitted) to an inner ring or an outer ring, and a gap is formed in the other outer ring or inner ring. By forming and holding the magnetic fluid in the gap, foreign matter is prevented from entering the inside. In the bearing with a magnetic fluid seal disclosed in Patent Document 1, a ring-shaped magnet is axially magnetized, and a ring-shaped electrode plate is attached to the opening side thereof. In the configuration, since the magnetic circuits are formed on the inner ring side and the outer ring side respectively, a minute gap (hereinafter, a gap is generated on the mounting side is generated on the mounting side of the ring-shaped electrode plate (ring-shaped magnet). In this case, the magnetic fluid is also held in a small gap) to prevent foreign matter from entering the inside from the outer ring side and the inner ring side.
ところで、上記したように、リング状の磁石を軸方向に着磁し、それをリング状の極板に取着した場合、径方向の両側には、同じ磁界強度の磁気回路が形成される（図１（ａ）の模式図参照）。すなわち、特許文献１に開示されているように、リング状の極板３０及びリング状の磁石２０の肉厚が均一であれば、内外輪間の径方向の両側（内輪側がＹ１、外輪側がＹ２となる）の夫々に形成される磁気回路Ｍ１，Ｍ２の磁界強度は、内輪及び外輪が存在しない状態で極板３０のみを考慮するとおおよそ等しくなる。 By the way, as described above, when the ring-shaped magnet is magnetized in the axial direction and attached to the ring-shaped electrode plate, magnetic circuits having the same magnetic field strength are formed on both sides in the radial direction ( (See the schematic view of FIG. 1A). That is, as disclosed in Patent Document 1, if the thicknesses of the ring-shaped electrode plate 30 and the ring-shaped magnet 20 are uniform, both sides in the radial direction between the inner and outer rings (Y1 on the inner ring side and Y2 on the outer ring side). The magnetic field strengths of the magnetic circuits M1 and M2 formed in each of (1) and (2) are approximately equal when only the electrode plate 30 is considered in the state where the inner ring and the outer ring are not present.
しかし、内輪（又は外輪）と極板との間に隙間を形成し、その隙間に磁性流体を保持させることから、隙間側で発生している磁気回路の磁界強度は、装着側（嵌入側）で発生している磁気回路の磁界強度よりも弱くなる。すなわち、図１（ａ）において、内輪側に隙間を形成していると、その部分は非磁性材が介在した状態になることから透磁率が低下してしまい、極板３０の端面３０ａから磁性材である内輪に向かう磁力（磁界強度）は、極板３０の端面３０ｂから磁性材である外輪に向かう磁力（磁界強度）よりも弱くなってしまう。この結果、隙間に保持される磁性流体の保持力が弱く、十分で安定したシール性能が得られない。 However, since a gap is formed between the inner ring (or outer ring) and the electrode plate and the magnetic fluid is held in the gap, the magnetic field strength of the magnetic circuit generated on the gap side is the mounting side (fitting side). It becomes weaker than the magnetic field strength of the magnetic circuit generated at. That is, in FIG. 1A, when a gap is formed on the inner ring side, the non-magnetic material intervenes at that portion, so the magnetic permeability decreases, and the magnetic force is applied from the end surface 30 a of the electrode plate 30. The magnetic force (magnetic field strength) toward the inner ring, which is a material, is weaker than the magnetic force (magnetic field strength) toward the outer ring, which is a magnetic material, from the end surface 30b of the electrode plate 30. As a result, the holding force of the magnetic fluid held in the gap is weak, and sufficient and stable sealing performance cannot be obtained.
なお、隙間部分で十分なシール力を得るためには、発生する磁界強度が大きい磁石を配設する必要があり、磁性流体シール付き軸受を効率的に小型化することができない。 In addition, in order to obtain a sufficient sealing force in the gap portion, it is necessary to dispose a magnet having a large generated magnetic field strength, and it is not possible to efficiently downsize the bearing with a magnetic fluid seal.
本発明は、上記した問題に着目してなされたものであり、隙間部分で安定したシール性能が得られる磁性流体シール付き軸受を提供することを目的とする。 The present invention has been made in view of the above problems, and an object of the present invention is to provide a bearing with a magnetic fluid seal that can obtain stable sealing performance in a gap portion.
上記した目的を達成するために、本発明に係る磁性流体シール付き軸受は、磁性材で形成された内輪及び外輪と、前記内輪と外輪の間に介装された複数の転動体と、前記内輪の外周面との間に隙間が生じるように前記外輪の内周面に対して装着され、磁性材で形成されると共に径方向の肉厚が変わるリング状の極板と、前記リング状の極板の軸方向内側面に取着され、軸方向に磁極が向くように着磁されて外輪側と内輪側にそれぞれ磁気回路を形成するリング状の磁石と、前記内輪側の磁気回路に保持され、前記隙間をシールする内輪側磁性流体と、前記内輪側で生じる磁気回路の磁界強度を、前記外輪側で生じる磁気回路の磁界強度よりも高くする磁界強度向上手段と、を備え、前記磁界強度向上手段は、前記極板の前記内輪の外周面に対向する側の軸方向肉厚が、前記外輪の内周面に対する軸方向肉厚よりも厚くなるように、前記磁石が取着される領域の前記極板の径方向の肉厚が形成されていることを特徴とする。 In order to achieve the above-mentioned object, a bearing with a magnetic fluid seal according to the present invention comprises an inner ring and an outer ring formed of a magnetic material, a plurality of rolling elements interposed between the inner ring and the outer ring, and the inner ring. inner is attached to the peripheral surface, a ring-shaped electrode plate thickness of Rutotomoni radially formed of a magnetic material is changed, the ring-shaped electrode of the outer ring so that a gap is formed between the outer peripheral surface of the is attached axially inner surface of the plate, a ring-shaped magnet which forms a magnetic circuit respectively on the outer wheel side and the inner race side are magnetized so as to face the magnetic pole in the axial direction, held in the magnetic circuit of the inner ring side The magnetic field strength improving means for increasing the magnetic field strength of the magnetic circuit generated on the inner ring side to the magnetic field strength of the magnetic circuit generated on the outer ring side. strength improvement means pair to the outer peripheral surface of the inner ring of the electrode plate Axial thickness of the side that is to be thicker than the axial thickness relative to the inner peripheral surface of the outer ring, radial thickness of the electrode plate area where the magnet is attached is formed It is characterized by
上記した構成によれば、軸方向に着磁されたリング状の磁石をリング状の極板に取着することによって、内輪側及び外輪側には、対称となる磁気回路が形成される。この場合、内輪の外周面との間で生じている隙間によって内輪側の磁気回路の磁力は、外輪側の磁気回路の磁力と比較すると弱くなるが、前記磁界強度向上手段によって、内輪側の磁気回路の磁力を外輪側の磁気回路の磁力よりも高めているため、隙間に保持される磁性流体の保持力が向上し、安定したシール特性が得られるようになる。 According to the above-mentioned configuration, the ring-shaped magnet magnetized in the axial direction is attached to the ring-shaped electrode plate, whereby symmetrical magnetic circuits are formed on the inner ring side and the outer ring side. In this case, the magnetic force of the magnetic circuit on the inner ring side becomes weaker than the magnetic force of the magnetic circuit on the outer ring side due to the gap generated between the outer ring surface of the inner ring and the magnetic force on the inner ring side by the magnetic field strength improving means. Since the magnetic force of the circuit is higher than the magnetic force of the magnetic circuit on the outer ring side, the holding force of the magnetic fluid held in the gap is improved, and stable sealing characteristics can be obtained.
上記した磁界強度向上手段は、リング状の極板にリング状の磁石を取着した状態で、内輪側で形成される磁気回路の磁力が、外輪側で形成される磁気回路の磁力よりも高くする構成となっていればよい。磁界強度向上手段は、例えば、図１（ｂ）に示すように、リング状の極板３０を、外輪側Ｙ２よりも内輪側Ｙ１を厚く（Ｔ１＞Ｔ２）なるように形成することで構成することができ、このような構成により、内輪側の磁気回路Ｍ１の磁界強度を外輪側の磁気回路Ｍ２の磁界強度よりも高めることが可能となる。すなわち、磁石２０によって発生する磁界強度は、極板３０の表面積に依存しており、隙間側の表面積を多くすることで、隙間部分での磁界強度を効果的に高め、隙間によって透磁率が低下しても十分な磁力を得ることが可能である。したがって、このような磁界強度向上手段を有するリング状の極板及びリング状の磁石を内外輪間に配設することで、隙間側の磁界強度を従来の構成（図１（ａ）に示す構成）と比較して効率的に高めることが可能となり、安定したシール特性が得られる。 In the magnetic field strength improving means described above, the magnetic force of the magnetic circuit formed on the inner ring side is higher than the magnetic force of the magnetic circuit formed on the outer ring side with the ring-shaped magnet attached to the ring-shaped polar plate. It is sufficient if it is configured to do. As shown in FIG. 1B, the magnetic field strength improving means is configured by forming a ring-shaped electrode plate 30 so that the inner ring side Y1 is thicker than the outer ring side Y2 (T1> T2). With such a configuration, the magnetic field strength of the inner ring side magnetic circuit M1 can be made higher than the magnetic field strength of the outer ring side magnetic circuit M2. That is, the magnetic field strength generated by the magnet 20 depends on the surface area of the electrode plate 30, and by increasing the surface area on the gap side, the magnetic field strength in the gap portion is effectively increased, and the permeability decreases due to the gap. Even then, it is possible to obtain a sufficient magnetic force. Therefore, by disposing the ring-shaped pole plate and the ring-shaped magnet having such magnetic field strength improving means between the inner and outer rings, the magnetic field strength on the gap side can be improved by the conventional structure (the structure shown in FIG. 1A). ), It is possible to increase the efficiency more efficiently, and stable sealing characteristics can be obtained.
磁界強度向上手段については、例えば、リング状の極板について、内輪側から外輪側に向けて次第に薄肉厚化するテーパ面を有するように形成したり、前記リング状の極板と外輪の内周面との間に非磁性のスペーサを介在することで構成することが可能である。
また、外輪側の内周面と、リング状の極板及びリング状の磁石との間に、微小隙間が生じる構成では、その部分に磁性流体（外輪側磁性流体）を保持しておくことが好ましく、これにより、内部を確実にシールすることが可能となる。
Regarding the magnetic field strength improving means, for example, a ring-shaped electrode plate is formed so as to have a tapered surface whose thickness is gradually reduced from the inner ring side to the outer ring side, or the ring-shaped electrode plate and the inner circumference of the outer ring are formed. It can be configured by interposing a non-magnetic spacer between the surface and the surface.
Further, in a configuration in which a minute gap is formed between the inner peripheral surface on the outer ring side and the ring-shaped electrode plate and the ring-shaped magnet, the magnetic fluid (outer ring-side magnetic fluid) may be retained in that portion. Preferably, this makes it possible to reliably seal the inside.
なお、上記した構成のリング状の磁石を取着したリング状の極板は、上記した構成とは逆に、内輪の外周面に対して装着され、外輪側に隙間を形成して外輪側磁性流体を保持して内部をシールするものであっても良い。 The ring-shaped pole plate with the ring-shaped magnet having the above-described structure is attached to the outer peripheral surface of the inner ring, forming a gap on the outer ring side, contrary to the above-mentioned structure, to form the outer ring-side magnetic field. It may be one that holds a fluid and seals the inside.
本発明によれば、隙間部分で安定したシール性能が得られる磁性流体シール付き軸受が得られる。 According to the present invention, it is possible to obtain a bearing with a magnetic fluid seal that can obtain stable sealing performance in the gap portion.
以下、図面を参照しながら本発明に係る磁性流体シール付き軸受の実施形態について説明する。
図２及び図３は、本発明に係る磁性流体シール付き軸受の第１の実施形態を示す図であり、図２は軸方向に沿った断面図、図３は図２の要部の拡大図である。
Hereinafter, an embodiment of a bearing with a magnetic fluid seal according to the present invention will be described with reference to the drawings.
2 and 3 are views showing a first embodiment of a bearing with a magnetic fluid seal according to the present invention, FIG. 2 is a sectional view taken along the axial direction, and FIG. 3 is an enlarged view of a main part of FIG. Is.
本実施形態に係る磁性流体シール付き軸受（以下、軸受とも称する）１は、円筒状の内輪３と、これを囲繞する円筒状の外輪５と、前記内輪３と外輪５との間に介装される複数の転動体（転がり部材）７とを備えている。前記転動体７は、周方向に延出するリテーナ（保持器）８に保持されており、内輪３と外輪５を相対的に回転可能としている。 A bearing with a magnetic fluid seal (hereinafter, also referred to as a bearing) 1 according to the present embodiment includes a cylindrical inner ring 3, a cylindrical outer ring 5 surrounding the inner ring 3, and an interposing between the inner ring 3 and the outer ring 5. And a plurality of rolling elements (rolling members) 7 to be formed. The rolling element 7 is held by a retainer (retainer) 8 extending in the circumferential direction, and allows the inner ring 3 and the outer ring 5 to rotate relatively.
前記内輪３、外輪５及び転動体７は、磁性を有する材料、例えばクロム系ステンレス（ＳＵＳ４４０Ｃ）によって形成されており、前記リテーナ８は、耐食性、耐熱性に優れた材料、例えばステンレス材（ＳＵＳ３０４）によって形成されている。なお、転動体７については、必ずしも磁性体である必要はない。また、本実施形態の内輪３及び外輪５は、軸方向（軸受の軸芯方向）Ｘにおける長さが同一（略同一であっても良い）となるように構成されているが、外輪５を内輪３よりも軸方向に長く形成しても良いし、内輪３を外輪５よりも軸方向に長く形成しても良い。 The inner ring 3, the outer ring 5 and the rolling elements 7 are formed of a magnetic material, for example, chrome-based stainless steel (SUS440C), and the retainer 8 is a material excellent in corrosion resistance and heat resistance, for example, a stainless steel material (SUS304). Is formed by. The rolling element 7 does not necessarily have to be a magnetic body. Further, the inner ring 3 and the outer ring 5 of the present embodiment are configured so that the lengths in the axial direction (axial direction of the bearing) X are the same (may be substantially the same). The inner ring 3 may be formed longer than the inner ring 3 in the axial direction, or the inner ring 3 may be formed longer than the outer ring 5 in the axial direction.
前記内輪３と外輪５の開口側には、以下に詳述する磁気シール機構（磁性流体シール）１０が設置されている。なお、本実施形態では、前記内輪３と外輪５の両側の開口に、同じ構成の磁気シール機構１０が配設されているため、以下の説明では、図２の右上の部分（主要部）を参照して説明する。 A magnetic seal mechanism (magnetic fluid seal) 10 described in detail below is installed on the opening sides of the inner ring 3 and the outer ring 5. In the present embodiment, since the magnetic seal mechanisms 10 having the same structure are arranged in the openings on both sides of the inner ring 3 and the outer ring 5, the upper right part (main part) of FIG. 2 will be described below. It will be described with reference to FIG.
磁気シール機構１０は、リング状に構成された磁石（以下、磁石とも称する）２０と、この磁石２０を軸方向内側面に取着するリング状の極板（以下、極板とも称する）３０と、前記磁石２０によって形成される磁気回路に保持される磁性流体（本実施形態では、内輪側磁性流体２５）と、を有しており、これらの部材により、前記転動体７内に、埃、水分等が侵入しないようにシールする機能を有している。 The magnetic seal mechanism 10 includes a ring-shaped magnet (hereinafter, also referred to as a magnet) 20 and a ring-shaped pole plate (hereinafter, also referred to as a pole plate) 30 that attaches the magnet 20 to an inner surface in the axial direction. , And a magnetic fluid (in this embodiment, the inner ring-side magnetic fluid 25) retained in the magnetic circuit formed by the magnets 20. It has a function of sealing so that moisture and the like do not enter.
前記磁石２０としては、磁束密度が高く、磁力が強い永久磁石、例えば、焼結製法によって作成されるネオジム磁石を用いることができ、予め軸方向（軸受の軸芯方向）Ｘに磁極（Ｓ極、Ｎ極）が向くように着磁されている。また、磁石２０の軸方向外側面には、前記極板３０が接するように配設される。極板３０は、前記磁石２０と略同一のリング状の外観形状となっており、磁性を有する材料、例えばクロム系ステンレス（ＳＵＳ４４０Ｃ）によって形成されている。したがって、内輪側及び外輪側には、図１に示したように、それぞれ磁気回路Ｍ１，Ｍ２が形成される。 As the magnet 20, a permanent magnet having a high magnetic flux density and a strong magnetic force, for example, a neodymium magnet produced by a sintering method can be used, and a magnetic pole (S pole) is previously set in the axial direction (axial direction of the bearing) X. , N pole) are oriented so that they are oriented. Further, the pole plate 30 is disposed on the axially outer side surface of the magnet 20 so as to be in contact therewith. The pole plate 30 has a ring-shaped appearance that is substantially the same as the magnet 20, and is made of a magnetic material, for example, chromium-based stainless steel (SUS440C). Therefore, magnetic circuits M1 and M2 are formed on the inner ring side and the outer ring side, respectively, as shown in FIG.
前記磁気回路によって保持される磁性流体は、例えばＦｅ3Ｏ4のような磁性微粒子を、界面活性剤によりベースオイルに分散させて構成されたものであり、粘性があって磁石を近づけると反応する特性を備えている。すなわち、後述する隙間Ｇ部分に、そのような磁性流体を保持することによって隙間をシールし、内部に埃、水分等の異物が侵入することを防止する機能を備えている。 The magnetic fluid held by the magnetic circuit is composed of magnetic fine particles such as Fe 3 O 4 dispersed in a base oil with a surfactant, and is viscous and reacts when a magnet is brought close to it. Is equipped with. That is, it has a function of sealing such a gap by holding such a magnetic fluid in a gap G portion described later, and preventing foreign matter such as dust and water from entering the inside.
本実施形態の外輪５には、転動体側の内周面５ａに段差５ｂが形成されており、この段差５ｂにより、外輪５は、開口側が薄肉領域５Ａ、転動体側が厚肉領域５Ｂとなって、軸方向の外側の内外輪間隔が内側よりも大きく形成されている。この段差５ｂは、開口側から挿入（嵌入）して所定位置に装着される磁石２０（極板３０が取着された磁石２０；磁石とユニット化された極板）を当て付けて位置決め固定する機能を備えている。このため段差５ｂは、軸方向に対して垂直な面とすることが好ましい。なお、段差５ｂは、本実施形態のように、垂直な面に限定されるものではなく、磁石２０を安定して保持できるのであれば、階段状に形成されていたり、傾斜状（斜面）に形成されていても良い。 The outer ring 5 of the present embodiment has a step 5b formed on the inner peripheral surface 5a on the rolling element side. Due to the step 5b, the outer ring 5 has a thin region 5A on the opening side and a thick region 5B on the rolling element side. Thus, the inner and outer races on the outer side in the axial direction are formed to be larger than the inner side. The step 5b is fixed by positioning the magnet 20 (the magnet 20 to which the polar plate 30 is attached; the polar plate unitized with the magnet) that is inserted (fitted) from the opening side and mounted at a predetermined position. It has a function. Therefore, it is preferable that the step 5b be a surface perpendicular to the axial direction. It should be noted that the step 5b is not limited to a vertical surface as in the present embodiment, and may be formed in a step shape or an inclined shape (slope) as long as the magnet 20 can be stably held. It may be formed.
前記極板３０は、内輪３の外周面３ａとの間に隙間Ｇが生じるように磁石２０に対して取着されている。この場合、極板３０は、磁石２０の内輪側縁面２０ａよりも径方向内側に突出する大きさに形成されており、前記磁石２０は、極板３０に取着された状態で、内輪３の外周面３ａとの間で上記した隙間Ｇと略同程度の隙間（図に示す構成では、隙間Ｇよりも僅かに大きい隙間）が生じるように形成されている。前記磁性流体（内輪側磁性流体２５）は、スポイト等の注入器具によって隙間Ｇに充填すると、磁気回路の磁力によって保持される。前記磁石２０と極板３０については、磁気吸着によって固定しても良いし、磁気吸着に加え接着剤を介在して固定しても良い。 The electrode plate 30 is attached to the magnet 20 so that a gap G is formed between the electrode plate 30 and the outer peripheral surface 3a of the inner ring 3. In this case, the pole plate 30 is formed to have a size that projects radially inward from the inner ring side edge surface 20a of the magnet 20, and the magnet 20 is attached to the pole plate 30 and the inner ring 3 Between the outer peripheral surface 3a and the outer peripheral surface 3a, a gap substantially the same as the above-mentioned gap G (a gap slightly larger than the gap G in the configuration shown in the drawing) is formed. The magnetic fluid (inner ring side magnetic fluid 25) is retained by the magnetic force of the magnetic circuit when the gap G is filled with an injection device such as a dropper. The magnet 20 and the electrode plate 30 may be fixed by magnetic attraction, or may be fixed by an adhesive agent in addition to magnetic attraction.
前記内輪３の外周面には、極板３０の内輪側縁面３０ａと対向する部分に、外周面と直交する方向に段差３ｂを形成しておくことが好ましい。このような段差３ｂを形成しておくことで、内輪側磁性流体２５が径方向に拡がるように保持された状態となり、シール性をより高めることが可能となる。また、前記極板３０については、内輪３及び外輪５の露出端面位置Ｐから軸方向に突出しないように固定することが好ましい。極板３０を軸方向に突出させない（好ましくは、露出端面位置Ｐから窪んだ位置に配設する）ことで、磁性流体２５に他物が接触する可能性が減り、磁性流体の散逸を防止することが可能となる。 It is preferable that a step 3b is formed on the outer peripheral surface of the inner ring 3 at a portion facing the inner ring side edge surface 30a of the electrode plate 30 in a direction orthogonal to the outer peripheral surface. By forming such a step 3b, the inner ring-side magnetic fluid 25 is held so as to spread in the radial direction, and the sealing performance can be further improved. Further, the electrode plate 30 is preferably fixed so as not to project axially from the exposed end surface position P of the inner ring 3 and the outer ring 5. By not projecting the electrode plate 30 in the axial direction (preferably, disposing the electrode plate 30 at a position recessed from the exposed end surface position P), the possibility that another object will come into contact with the magnetic fluid 25 is reduced, and dissipation of the magnetic fluid is prevented. It becomes possible.
前記磁気シール機構１０は、内輪側で生じる磁気回路Ｍ１の磁界強度を、外輪側で生じる磁気回路Ｍ２の磁界強度よりも高くする磁界強度向上手段５０が設けられている。
磁界強度向上手段５０は、内外輪間の径方向の両側において極板３０を通じて内輪側及び外輪側の夫々に流れる磁束量を、相対的に内輪側を多くさせるものであれば良く、このような磁界強度向上手段５０を設けることで、磁石２０が取着された極板３０を所定の位置に設置した際、隙間側の磁力が、磁界強度向上手段５０を設けない構成と比較して強くなり、安定して内輪側磁性流体２５を保持することが可能となる。
The magnetic seal mechanism 10 is provided with a magnetic field strength improving means 50 for making the magnetic field strength of the magnetic circuit M1 generated on the inner ring side higher than the magnetic field strength of the magnetic circuit M2 generated on the outer ring side.
The magnetic field strength improving means 50 only needs to increase the amount of magnetic flux flowing to the inner ring side and the outer ring side through the electrode plates 30 on both sides in the radial direction between the inner ring and the outer ring relatively on the inner ring side. By providing the magnetic field strength improving means 50, when the pole plate 30 to which the magnet 20 is attached is installed at a predetermined position, the magnetic force on the gap side becomes stronger than in the configuration without the magnetic field strength improving means 50. Thus, it is possible to stably hold the inner ring-side magnetic fluid 25.
本実施形態では、極板３０に磁界強度向上手段５０を設けており、極板３０の内輪側を肉厚にし、外輪側を薄肉にすることで構成されている。すなわち、磁束量は表面積に依存することから、内輪の外周面に対向する極板３０の肉厚を、外輪の内周面に対する肉厚よりも厚くすることで磁束量が多くなり、結果として内輪側で形成される磁気回路の磁界強度を強くすることが可能となる。 In the present embodiment, the pole plate 30 is provided with the magnetic field strength improving means 50, and the pole plate 30 is configured such that the inner ring side is thick and the outer ring side is thin. That is, since the amount of magnetic flux depends on the surface area, the amount of magnetic flux is increased by making the thickness of the electrode plate 30 facing the outer peripheral surface of the inner ring thicker than the thickness of the outer ring on the inner peripheral surface. It is possible to increase the magnetic field strength of the magnetic circuit formed on the side.
具体的に、本実施形態では、極板３０に、内輪側から外輪側に向けて次第に薄肉厚化するテーパ面３０ｂを形成しており、外輪側の薄肉厚化された縁部３０ｃを磁石２０の外輪側縁面２０ｂと一致させている。このような構成によれば、磁石２０による磁束が内輪側に偏重し、隙間部分の磁力を低下させることなく、安定して内輪側磁性流体２５を保持することが可能となる。また、極板３０の外輪側の縁部３０ｃを磁石２０の外輪側縁面２０ｂと一致させたことで両者の位置決めが容易に行えるようになる。 Specifically, in the present embodiment, the pole plate 30 is formed with a tapered surface 30b that is gradually thinned from the inner ring side toward the outer ring side, and the thinned edge portion 30c on the outer ring side is attached to the magnet 20. Of the outer ring side edge surface 20b. With such a configuration, the magnetic flux generated by the magnet 20 is biased toward the inner ring side, and the inner ring side magnetic fluid 25 can be stably retained without lowering the magnetic force in the gap. Further, since the outer ring side edge portion 30c of the electrode plate 30 is aligned with the outer ring side edge surface 20b of the magnet 20, both can be easily positioned.
上記した構成では、内輪側の隙間Ｇに内輪側磁性流体２５を保持する構成としたが、前記磁石２０の寸法公差によって、外輪５の内周面５ａと磁石２０との間に微小な隙間が生じている可能性もあるため、そのような微小隙間に外輪側磁性流体（図示せず）を充填することでシール性をより向上することが可能となる。 In the above-mentioned configuration, the inner ring side magnetic fluid 25 is held in the inner ring side gap G. However, due to the dimensional tolerance of the magnet 20, a minute gap is formed between the inner peripheral surface 5a of the outer ring 5 and the magnet 20. Since there is a possibility that it has occurred, it is possible to further improve the sealing performance by filling such a minute gap with an outer ring side magnetic fluid (not shown).
次に、本発明の別の実施形態について説明する。なお、以下に説明する実施形態では、前記実施形態と同様な構成については同一の参照符号を付し、詳細な説明については省略する。 Next, another embodiment of the present invention will be described. In the embodiments described below, the same components as those in the above embodiments are designated by the same reference numerals, and detailed description thereof will be omitted.
図４は、本発明の第２の実施形態を示す要部拡大図である。
本実施形態の磁界強度向上手段５０は、極板３０に、内輪側から外輪側に向けて次第に薄肉厚化するテーパ面３０ｂを形成するとともに、その中間部分でテーパ面を終端させて、極板３０を断面略台形状に形成している。このため、極板３０の外輪側の薄肉厚化された縁部３０ｃ´と外輪５の内周面５ａとの間には空隙が形成され、この部分が非磁性のスペーサとしての機能を果たすこととなる。
FIG. 4 is an enlarged view of the essential parts showing the second embodiment of the present invention.
The magnetic field strength improving means 50 of the present embodiment forms a tapered surface 30b on the electrode plate 30 that gradually decreases in thickness from the inner ring side to the outer ring side, and terminates the tapered surface at an intermediate portion thereof to form the electrode plate. The cross section 30 is formed into a substantially trapezoidal shape. For this reason, a gap is formed between the outer ring-side thinned edge portion 30c 'of the electrode plate 30 and the inner peripheral surface 5a of the outer ring 5, and this portion functions as a non-magnetic spacer. Becomes
このような構成によれば、第１の実施形態の構成よりも内輪側に形成される磁気回路の磁力を更に高めることが可能となり、より安定して内輪側磁性流体２５を隙間Ｇ内に保持することが可能となる。 With such a configuration, the magnetic force of the magnetic circuit formed on the inner ring side can be further increased as compared with the configuration of the first embodiment, and the inner ring side magnetic fluid 25 is more stably retained in the gap G. It becomes possible to do.
図５は、本発明の第３の実施形態を示す要部拡大図である。
本実施形態の磁界強度向上手段５０は、極板３０を均一の肉厚とし、その外輪側に配設される樹脂等の非磁性材料で形成されたリング状のスペーサ５１を有している。このような非磁性のスペーサ５１を、極板３０の外輪側の縁部３０ｃ´と外輪５の内周面５ａとの間に介在することで、上記した実施形態と同様、内輪側に形成される磁気回路の磁力を高めることが可能となり、安定して内輪側磁性流体２５を隙間Ｇ内に保持することが可能となる。
FIG. 5 is an enlarged view of the essential parts showing the third embodiment of the present invention.
The magnetic field strength improving means 50 of the present embodiment has a pole plate 30 having a uniform thickness, and has a ring-shaped spacer 51 formed of a non-magnetic material such as resin disposed on the outer ring side thereof. By interposing such a non-magnetic spacer 51 between the outer ring-side edge portion 30c 'of the electrode plate 30 and the inner peripheral surface 5a of the outer ring 5, the non-magnetic spacer 51 is formed on the inner ring side as in the above-described embodiment. The magnetic force of the magnetic circuit can be increased, and the inner ring side magnetic fluid 25 can be stably retained in the gap G.
また、前記スペーサ５１を樹脂材で形成することにより、極板３０及び磁石２０と一体化してユニット化することが容易となり、内外輪の間の組み付け及び位置決めが容易に行えるようになる。なお、スペーサ５１については、非磁性材料であれば良く、非磁性の金属や単なる空気層であっても良い。また、スペーサ５１は、その径方向長さが隙間Ｇの長さよりも長いことが好ましく、これにより、より効果的に内輪側の磁界強度を向上して磁性流体を安定して保持することが可能となる。 Further, by forming the spacer 51 from a resin material, it becomes easy to integrate the electrode plate 30 and the magnet 20 into a unit, and it is possible to easily assemble and position the inner and outer rings. The spacer 51 may be a non-magnetic material, and may be a non-magnetic metal or a simple air layer. Further, it is preferable that the radial length of the spacer 51 is longer than the length of the gap G, so that it is possible to more effectively improve the magnetic field strength on the inner ring side and stably hold the magnetic fluid. Becomes
更に、本実施形態では、外輪５の内周面５ａと磁石２０との間の微小隙間にも外輪側磁性流体２５ａを充填しており、これにより内部のシール性をより高めることが可能となる。このような外輪側磁性流体２５ａは、内輪側磁性流体を充填する際に、そのまま外輪側に充填することで配設することが可能である。 Further, in the present embodiment, the outer ring-side magnetic fluid 25a is also filled in the minute gap between the inner peripheral surface 5a of the outer ring 5 and the magnet 20, which makes it possible to further enhance the internal sealability. . Such outer ring side magnetic fluid 25a can be disposed by filling the outer ring side as it is when filling the inner ring side magnetic fluid.
図６は、本発明の第４の実施形態を示す要部拡大図である。
本実施形態の磁界強度向上手段５０は、第３実施形態と同様、極板と外輪との間に介在される樹脂製のスペーサ５３を備えている。このスペーサ５３の内輪側には、リング状の凹所５３ａが形成されており、この部分にリング状の極板３０が取着されている。すなわち、樹脂製のスペーサ５３は、内外輪間の開口部分に表面が露出した状態となっており、リング状の極板３０を表面に露出させることなく、軸方向内側に保持している。
FIG. 6 is an enlarged view of the essential parts showing the fourth embodiment of the present invention.
Similar to the third embodiment, the magnetic field strength improving means 50 of the present embodiment includes a resin spacer 53 interposed between the electrode plate and the outer ring. A ring-shaped recess 53a is formed on the inner ring side of the spacer 53, and the ring-shaped electrode plate 30 is attached to this portion. That is, the resin spacer 53 has a surface exposed at the opening between the inner and outer rings, and holds the ring-shaped electrode plate 30 axially inward without exposing the surface.
このような構成によれば、スペーサ５３と共に極板３０及び磁石２０を精度良くユニット化することができ、組み付けを容易に行うことが可能となる。また、このような構成では、開口部分は、樹脂製のスペーサ５３の表面が露出した状態になることから、極板の表面を保護することができ、更には、色彩等を付すことにより外観の向上も図れる。 With such a configuration, the electrode plate 30 and the magnet 20 can be accurately unitized together with the spacer 53, and the assembly can be easily performed. Further, in such a configuration, since the surface of the spacer 53 made of resin is exposed in the opening portion, the surface of the electrode plate can be protected, and further, the appearance can be improved by adding a color or the like. It can be improved.
上述した各実施形態における軸受１の磁気シール機構１０は、いずれも隙間Ｇを内輪側に形成し、その部分に内輪側磁性流体を保持するようにしたが、いずれの実施形態においても、隙間Ｇは外輪側に形成しても良い。 In each of the magnetic seal mechanisms 10 of the bearing 1 in each of the above-described embodiments, the gap G is formed on the inner ring side and the inner ring side magnetic fluid is retained in that portion, but in any of the embodiments, the gap G is formed. May be formed on the outer ring side.
図７は、本発明の第５の実施形態を示す要部拡大図である。
この実施形態では、第１の実施形態と同様な構成で、極板３０の外輪側縁部３０ｃ´と外輪５の内周面５ａとの間に磁性流体（外輪側磁性流体）２６を保持している。前記極板３０は、第１の実施形態とは逆に、外輪側から内輪側に向けて次第に薄肉厚化するテーパ面３０ｂを有しており、内輪側の薄肉厚化された縁部３０ａ´を磁石２０の内輪側縁面２０ａと一致させている。このような構成では、磁石２０による磁束が外輪側に偏重し、隙間部分の磁力を低下させることなく、安定して外輪側磁性流体２６を保持することが可能となる。また、極板３０の内輪側の縁部３０ａ´を磁石２０の内輪側縁面２０ａと一致させたことで両者の位置決めが容易に行えるようになる。
FIG. 7 is an enlarged view of the essential parts showing the fifth embodiment of the present invention.
In this embodiment, a magnetic fluid (outer ring side magnetic fluid) 26 is held between the outer ring side edge portion 30c ′ of the electrode plate 30 and the inner peripheral surface 5a of the outer ring 5 with the same configuration as that of the first embodiment. ing. Contrary to the first embodiment, the electrode plate 30 has a tapered surface 30b that gradually becomes thinner from the outer ring side to the inner ring side, and the inner ring side thinned edge portion 30a 'is formed. Is aligned with the inner ring side edge surface 20a of the magnet 20. With such a configuration, the magnetic flux from the magnet 20 is biased toward the outer ring side, and the magnetic force in the outer ring side can be stably held without lowering the magnetic force in the gap portion. Further, since the inner ring side edge portion 30a 'of the pole plate 30 is aligned with the inner ring side edge surface 20a of the magnet 20, both can be easily positioned.
また、外輪側に隙間を形成して、上記した第２実施形態から第４実施形態と同様な磁気シール機構とする場合、内輪側に生じる微小隙間に、内輪側磁性流体を保持するように構成しても良い。 Further, when a gap is formed on the outer ring side to provide the same magnetic seal mechanism as that of the second to fourth embodiments described above, the inner ring side magnetic fluid is retained in the minute gap generated on the inner ring side. You may.
図８は、従来の構成による磁気回路と、本発明の構成による磁気回路とを対比した磁界強度部分布を示す図である。
対比する軸受は、いずれも内外輪の大きさ、磁気シール機構における磁石の大きさ、極板の基本的な厚さ、隙間Ｇの大きさを同一条件としており、図１（ａ）に示したように、極板を通常タイプの形状としたもの、図５に示したように、極板の外輪側に非磁性のスペーサ（空気層）を配設したもの、図３に示したように、極板にテーパ面を形成したものである。このような３つのタイプの軸受について、一般的に流布している磁場解析ソフトを使用してパソコンソフト上で磁界強度分布をシミュレーションしたのが図８である。
FIG. 8 is a diagram showing a magnetic field strength portion distribution in which a magnetic circuit having a conventional configuration and a magnetic circuit having the configuration of the present invention are compared.
In the bearings to be compared, the size of the inner and outer rings, the size of the magnet in the magnetic seal mechanism, the basic thickness of the electrode plate, and the size of the gap G were all set under the same conditions, and are shown in FIG. 1 (a). As shown in FIG. 5, the electrode plate has a normal type shape, a non-magnetic spacer (air layer) is provided on the outer ring side of the electrode plate, as shown in FIG. The electrode plate is formed with a tapered surface. FIG. 8 shows a simulation of the magnetic field strength distribution on the personal computer software using the magnetic field analysis software that is generally used for these three types of bearings.
この磁界強度分布に見られるように、図１（ａ）に示す通常タイプの磁気シール機構では、上述した「発明が解決しようとする課題」の欄で指摘したように、隙間側で生じる磁界の強度が弱くなっており、したがって、磁性流体は保持するものの、その保持力は弱いものとなる。これに対し、極板の外輪側に非磁性のスペーサを介在させたもの、及び、極板を外輪側に向けて次第に薄肉厚化したものは、隙間側で生じる磁界の強度が強く、磁性流体の保持も安定する。 As can be seen from this magnetic field strength distribution, in the normal type magnetic seal mechanism shown in FIG. 1 (a), as pointed out in the above-mentioned “Problems to be solved by the invention”, Since the strength is weak, the magnetic fluid is retained, but the retaining force is weak. On the other hand, the one with a non-magnetic spacer interposed on the outer ring side of the electrode plate and the one with the electrode plate gradually thinned toward the outer ring side have a strong magnetic field generated on the gap side, and Is also stable.
なお、非磁性のスペーサを極板と外輪の内周面との間に介在するタイプでは、スペーサの径方向の長さを隙間の長さよりも若干広くしてシミュレーションしたが、スペーサの径方向の長さを更に広げることで、隙間側の磁界強度をより強くすることが可能である。 In the case of a type in which a non-magnetic spacer is interposed between the electrode plate and the inner peripheral surface of the outer ring, the radial length of the spacer was made slightly wider than the length of the gap, and the simulation was performed. By further increasing the length, it is possible to further increase the magnetic field strength on the gap side.
以上、本発明の実施形態について説明したが、本発明は上記した実施形態に限定されることはなく、適宜変形することが可能である。 Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate.
上述した磁界強度向上手段については、図１（ａ）に示したように、リング状の磁石にリング状の極板を配設した通常の配置構成では、これを内外輪間に組み込んだ際、隙間側の磁界強度が低下することに着目したものであり、これを、例えば図１（ｂ）に示すように、隙間側で生じる磁気回路の磁界強度を向上するように構成したものであれば、極板の形状、配置態様以外にも適宜変形することが可能である。例えば、磁石を隙間側に偏倚して配設しても良いし、極板については、隙間側の透磁率及び飽和磁束密度が高くなるような材料で構成したものであっても良い。 Regarding the above-mentioned magnetic field strength improving means, as shown in FIG. 1A, in a normal arrangement configuration in which a ring-shaped pole plate is arranged on a ring-shaped magnet, when this is assembled between the inner and outer rings, Focusing on the fact that the magnetic field strength on the gap side is reduced, if this is configured to improve the magnetic field strength of the magnetic circuit generated on the gap side as shown in FIG. The shape and arrangement of the electrode plate can be appropriately modified. For example, the magnets may be arranged so as to be biased to the gap side, and the pole plate may be made of a material that increases the permeability and the saturation magnetic flux density on the gap side.
また、上記した実施形態における磁気シール機構では、磁石２０は、外輪側に形成された段差５ｂ、或いは、内輪側に形成された段差３ｂに当て付けて位置決め固定したが、段差を形成することなく磁石２０を嵌入（圧入）して固定する構成であっても良いし、磁石を取着した極板を段差等に当て付けて位置決め固定する構成であっても良い。この場合、極板に、別途、段差に当て付くような凹凸等を形成しておいても良い。 Further, in the magnetic seal mechanism according to the above-described embodiment, the magnet 20 is positioned and fixed by contacting the step 5b formed on the outer ring side or the step 3b formed on the inner ring side, but without forming the step. The magnet 20 may be inserted (press-fitted) and fixed, or the pole plate to which the magnet is attached may be applied to a step or the like for positioning and fixing. In this case, the electrode plate may be separately provided with irregularities or the like to be brought into contact with the step.
また、上記した各実施形態では、内輪３及び外輪５の表面に、電解クロム酸処理を施しておくことが好ましい。このように電解クロム酸処理を施しておくことで、錆や腐食によって表面に亀裂や裂けが生じることが防止でき、埃や異物が内部に侵入して行くことを確実に防止することが可能となる。 Further, in each of the above-described embodiments, it is preferable that the surfaces of the inner ring 3 and the outer ring 5 be subjected to electrolytic chromic acid treatment. By performing electrolytic chromic acid treatment in this way, it is possible to prevent cracks and tears on the surface due to rust and corrosion, and it is possible to reliably prevent dust and foreign matter from entering the inside. Become.
さらに、上記した実施形態の構成において、開口側に極板３０が露出する場合、その軸方向外側の表面に、軸方向外方からリング状のシールド（密閉カバー）を圧入固定しておいても良い。このようなシールドは、耐食性、耐熱性に優れた材料、例えばステンレス材（ＳＵＳ３０４）や樹脂等によって形成することが可能であり、このようなシールドを配設することで、異物の侵入をより効果的に防止できると共に、砂鉄のような磁性物（異物）が磁石２０に付着することを効果的に防止することができる。 Furthermore, in the configuration of the above-described embodiment, when the electrode plate 30 is exposed on the opening side, a ring-shaped shield (sealing cover) may be press-fitted and fixed to the surface on the outer side in the axial direction from the outside in the axial direction. good. Such a shield can be formed of a material having excellent corrosion resistance and heat resistance, for example, a stainless steel material (SUS304), resin, or the like. By disposing such a shield, it is possible to more effectively prevent foreign matter from entering. The magnetic substance (foreign matter) such as iron sand can be effectively prevented from adhering to the magnet 20.
１ 磁性流体シール付き軸受
３ 内輪
５ 外輪
７ 転動体
１０ 磁気シール機構
２０ リング状の磁石
２５ 内輪側磁性流体
２６ 外輪側磁性流体
３０ リング状の極板
５０ 磁界強度向上手段
Ｇ 隙間
DESCRIPTION OF SYMBOLS 1 Bearing with magnetic fluid seal 3 Inner ring 5 Outer ring 7 Rolling element 10 Magnetic seal mechanism 20 Ring-shaped magnet 25 Inner ring side magnetic fluid 26 Outer ring side magnetic fluid 30 Ring-shaped pole plate 50 Magnetic field strength improving means G Gap
Claims (6)
前記内輪と外輪の間に介装された複数の転動体と、
前記内輪の外周面との間に隙間が生じるように前記外輪の内周面に対して装着され、磁性材で形成されると共に径方向の肉厚が変わるリング状の極板と、
前記リング状の極板の軸方向内側面に取着され、軸方向に磁極が向くように着磁されて外輪側と内輪側にそれぞれ磁気回路を形成するリング状の磁石と、
前記内輪側の磁気回路に保持され、前記隙間をシールする内輪側磁性流体と、
前記内輪側で生じる磁気回路の磁界強度を、前記外輪側で生じる磁気回路の磁界強度よりも高くする磁界強度向上手段と、を備え、
前記磁界強度向上手段は、
前記極板の前記内輪の外周面に対向する側の軸方向肉厚が、前記外輪の内周面に対する軸方向肉厚よりも厚くなるように、前記磁石が取着される領域の前記極板の径方向の肉厚が形成されていることを特徴とする磁性流体シール付き軸受。 An inner ring and an outer ring formed of a magnetic material,
A plurality of rolling elements interposed between the inner ring and the outer ring,
And it is attached to the inner peripheral surface of the outer ring so that a gap occurs, a ring-shaped wall thickness of Rutotomoni radially formed of a magnetic material changes electrode plate between the outer circumferential surface of the inner ring,
It is attached axially inner surface of the ring-shaped electrode plate, and a ring-shaped magnet is magnetized so as to face the magnetic pole in the axial direction to form a magnetic circuit respectively on the outer wheel side and the inner ring side,
An inner ring side magnetic fluid that is held in the inner ring side magnetic circuit and seals the gap,
Magnetic field strength improving means for making the magnetic field strength of the magnetic circuit generated on the inner ring side higher than the magnetic field strength of the magnetic circuit generated on the outer ring side,
The magnetic field strength improving means,
The pole plate in the region where the magnet is attached so that the axial thickness of the pole plate on the side facing the outer peripheral surface of the inner ring is thicker than the axial thickness of the outer ring with respect to the inner peripheral surface. The bearing with a magnetic fluid seal is characterized in that the radial thickness of the bearing is formed .
前記内輪と外輪の間に介装された複数の転動体と、
前記外輪の内周面との間に隙間が生じるように前記内輪の外周面に対して装着され、磁性材で形成されると共に径方向の肉厚が変わるリング状の極板と、
前記リング状の極板の軸方向内側面に取着され、軸方向に磁極が向くように着磁されて外輪側と内輪側にそれぞれ磁気回路を形成するリング状の磁石と、
前記外輪側の磁気回路に保持され、前記隙間をシールする外輪側磁性流体と、
前記外輪側で生じる磁気回路の磁界強度を、前記内輪側で生じる磁気回路の磁界強度よりも高くする磁界強度向上手段と、を備え、
前記磁界強度向上手段は、
前記極板の前記外輪の内周面に対向する側の軸方向肉厚が、前記内輪の外周面に対する軸方向肉厚よりも厚くなるように、前記磁石が取着される領域の前記極板の径方向の肉厚が形成されていることを特徴とする磁性流体シール付き軸受。 An inner ring and an outer ring formed of a magnetic material,
A plurality of rolling elements interposed between the inner ring and the outer ring,
And is attached to the outer peripheral surface of the inner ring so that a gap occurs, a ring-shaped electrode plate thickness of Rutotomoni radially formed of a magnetic material is changed between the inner circumferential surface of the outer ring,
It is attached axially inner surface of the ring-shaped electrode plate, and a ring-shaped magnet is magnetized so as to face the magnetic pole in the axial direction to form a magnetic circuit respectively on the outer wheel side and the inner ring side,
An outer ring side magnetic fluid that is held in the outer ring side magnetic circuit and seals the gap,
A magnetic field strength improving means for making the magnetic field strength of the magnetic circuit generated on the outer ring side higher than the magnetic field strength of the magnetic circuit generated on the inner ring side,
The magnetic field strength improving means,
The pole plate in the region where the magnet is attached so that the axial thickness of the pole plate on the side facing the inner peripheral surface of the outer ring is thicker than the axial thickness of the outer ring of the inner ring. The bearing with a magnetic fluid seal is characterized in that the radial thickness of the bearing is formed .
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