JP6074468B2 - Bearing with magnetic fluid seal - Google Patents

Description

  The present invention relates to a bearing with a magnetic fluid seal that is disposed in various power transmission mechanisms and rotatably supports a rotating shaft, and prevents foreign matter such as dust and moisture from entering inside.

  Generally, a rotating shaft installed in various driving force transmission mechanisms is rotatably supported via a bearing. In this case, a so-called ball bearing (ball bearing) in which a plurality of rolling elements (rolling members) are accommodated in the circumferential direction between the inner ring and the outer ring is often used as the bearing. By using it, the rotational performance of the rotating shaft is improved.

  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 moisture can be prevented from entering inside the bearing portion. There is something I want to do. In addition, when foreign matter enters the bearing itself, problems such as deterioration in rotational performance and abnormal noise occur. As a countermeasure against such a problem, a seal member made of an elastic material is brought into contact with the outer periphery of the rotating shaft close to the bearing to make the bearing portion waterproof and dust-proof. However, the seal member made of an elastic material is used. The rotational performance of the rotating shaft is degraded due to the influence of the contact pressure.

  Accordingly, a bearing (referred to as a bearing with a magnetic fluid seal) having a magnetic fluid seal mechanism using a magnetic fluid is known as a configuration for preventing foreign matter from entering the bearing portion without deteriorating the rotational performance of the rotary shaft. ing. For example, Patent Document 1 relates to a ball bearing that holds a rolling element between an outer ring and an inner ring, interposing a magnetic body between the outer ring and the inner ring that rotate relative to each other, and fixing one side of the magnetic body, A configuration in which a magnetic fluid is disposed in the seal gap on the other side is disclosed. That is, the rolling element is closed by disposing the magnetic body between the inner ring and the outer ring to close the rolling element, fixing one side of the magnetic body, and disposing the magnetic fluid in the seal gap on the other side. Sealed in a sealed state to prevent foreign matter from entering the rolling elements that affect the rotational performance.

JP-A-57-33222

  According to the bearing with a magnetic fluid seal disclosed in Patent Document 1 described above, the sealing performance is maintained with respect to dust and a liquid with a certain degree of viscosity, but the sealing performance with respect to a liquid with a low viscosity is sufficient. There is a possibility that it cannot be demonstrated. That is, since the magnetic body has lower dimensional accuracy than the members constituting the bearing, the liquid easily enters from one fixed side, and the liquid having a lower viscosity is more likely to enter the rolling element (particularly Seawater dries after intrusion and leaves salt crystals, which leads to deterioration in rotational performance). In this case, if the sealing is surely performed, the productivity is reduced, for example, the size of the magnetic body is precisely controlled or a part for sealing is separately incorporated.

  The present invention has been made paying attention to the above-described problems, and an object of the present invention is to provide a bearing with a magnetic fluid seal having a structure excellent in productivity, in which the seal of the inner rolling element portion is reliably maintained. .

In order to achieve the above-described object, the present invention provides a plurality of rolling elements between an inner ring formed of a magnetic material and an outer ring formed of a magnetic material, and a ring is formed on the opening side of the inner ring and the outer ring. A magnetic fluid seal bearing for holding a magnetic fluid by arranging a magnet and sealing the plurality of rolling elements, wherein the ring-shaped magnet is magnetized so that the magnetic pole faces in the axial direction. A magnetic material that forms a magnetic circuit on each of the outer ring side and the inner ring side, is disposed in contact with the outer surface in the axial direction of the ring-shaped magnet, is substantially the same shape as the ring-shaped magnet, and the outer ring is a fixed material. A ring-shaped electrode plate formed, an outer ring-side magnetic fluid held between at least the outer ring and the ring-shaped magnet by a magnetic circuit formed on the outer ring side, and a magnetism formed on the inner ring side. at least the inner ring of the outer circumferential surface by the circuit, the An inner ring-side magnetic fluid held in the gap formed between the peripheral surface opposite to the ring-shaped electrode plate, and having a.
In the present invention, a plurality of rolling elements are interposed between an inner ring formed of a magnetic material and an outer ring formed of a magnetic material, and a ring-shaped magnet is disposed on the opening side of the inner ring and the outer ring. A magnetic fluid seal bearing that holds the magnetic fluid and seals the plurality of rolling elements, wherein the ring-shaped magnets are magnetized so that the magnetic poles are oriented in the axial direction, respectively on the outer ring side and the inner ring side. A ring-shaped pole that forms a magnetic circuit and is arranged in contact with the outer surface in the axial direction of the ring-shaped magnet, and is formed of a magnetic material having substantially the same shape as the ring-shaped magnet and having an inner ring as a fixed side. An outer ring-side magnetism held in a gap formed between at least the inner circumferential surface of the outer ring and the ring-shaped electrode plate facing the inner circumferential surface by a magnetic circuit formed on the outer ring side with the plate At least in front by a fluid and a magnetic circuit formed on the inner ring side. And having a an inner ring-side magnetic fluid held between the inner race and said ring-shaped magnet.

  According to the configuration described above, the ring-shaped magnet is magnetized so that the magnetic poles are directed in the axial direction, and magnetic circuits are formed on the outer ring side and the inner ring side, respectively. The magnetic fluid can be held in the gap portion of the outer peripheral surface on the inner ring side. For this reason, even if the dimensional accuracy of the ring-shaped magnet is low, sufficient sealing performance against the rolling elements can be ensured, so that it is not necessary to precisely control the size of the ring-shaped magnet, and it is easy to incorporate it. It is possible to improve productivity.

  The magnetic fluid held on the outer peripheral surface on the outer ring side and the outer peripheral surface on the inner ring side as described above may be disposed only on the opening portion on one side of the bearing, or on both side opening portions. It may be arranged.

  According to the present invention, a bearing with a magnetic fluid seal having a structure excellent in productivity can be obtained in which the seal of the inner rolling element portion is reliably maintained.

It is a figure which shows 1st Embodiment of the bearing with a magnetic fluid seal which concerns on this invention, and sectional drawing along an axial direction. The principal part enlarged view of FIG. The figure which shows the modification of 1st Embodiment. It is a figure which shows 2nd Embodiment of the bearing with a magnetic fluid seal concerning this invention, and is a principal part expanded sectional view along the axial direction. The figure which shows the modification of 2nd Embodiment. It is a figure which shows 3rd Embodiment of the bearing with a magnetic fluid seal which concerns on this invention, and sectional drawing along an axial direction.

Hereinafter, embodiments of a bearing with a magnetic fluid seal according to the present invention will be described with reference to the drawings.
1 and 2 are views showing a first embodiment of a magnetic fluid seal bearing according to the present invention. FIG. 1 is a sectional view along an axial direction, and FIG. 2 is an enlarged view of a main part of FIG. is there.

  A magnetic fluid seal bearing (hereinafter also referred to as a bearing) 1 according to this embodiment includes a cylindrical inner ring 3, a cylindrical outer ring 5 surrounding the inner ring 3, and an inner ring 3 and an outer ring 5. And a plurality of rolling elements (rolling members) 7. The rolling element 7 is held by a retainer (cage) 8 extending in the circumferential direction, and the inner ring 3 and the outer ring 5 are relatively rotatable.

  The inner ring 3, the outer ring 5 and the rolling element 7 are made of a magnetic material, for example, chromium-based stainless steel (SUS440C), and the retainer 8 is made of a material having excellent corrosion resistance and heat resistance, for example, stainless steel (SUS304). Is formed by. In addition, about the rolling element 7, it does not necessarily need to be a magnetic body. In addition, the outer ring 5 of the present embodiment is configured such that the exposed end surface 5a is the same (may be substantially the same) as the exposed end surface 3a of the inner ring 3, but in the third embodiment described later. As described above, the outer ring 5 may be formed longer in the axial direction than the inner ring 3 (the outer ring 5 may include an elongated cylindrical portion protruding in the axial direction with respect to the inner ring 3). It may be formed longer in the axial direction.

  A magnetic fluid seal 10, which will be described in detail below, is installed on the opening side of the inner ring 3 and the outer ring 5. In the present embodiment, the magnetic fluid seals having the same configuration are disposed in the openings on both sides of the inner ring 3 and the outer ring 5, and therefore, in the following description, the configuration on one side (left side in FIG. 1) will be described. .

  The magnetic fluid seal 10 includes a ring-shaped magnet (hereinafter referred to as a magnet) 12 and a ring-shaped electrode plate (hereinafter referred to as an electrode plate) disposed in contact with the axially outer surface of the magnet 12. 14 and a magnetic fluid (an outer ring-side magnetic fluid 15a and an inner ring-side magnetic fluid 15b) held in a magnetic circuit formed by the magnet 12, and by these members, in the rolling element 7 It has a function of sealing so that dust, moisture and the like do not enter.

  As the magnet 12, 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. As shown in FIG. X) is magnetized so that the magnetic poles (S pole, N pole) face it. In addition, the electrode plate 14 is disposed in contact with the outer surface of the magnet 12 in the axial direction. The electrode plate 14 has substantially the same shape as the magnet 12, and is made of a magnetic material, for example, chromium-based stainless steel (SUS440C).

  In the present embodiment, the magnet 12 and the electrode plate 14 are bonded in advance, but may not be bonded. In this case, by pre-bonding the two, the magnet 12 can be easily positioned and centered, and the magnet 12 and the electrode plate 14 are unitized so that an assembling operation as described later can be easily performed. .

The outer ring-side magnetic fluid 15a and the inner ring-side magnetic fluid 15b are configured by dispersing magnetic fine particles such as Fe ₃ O ₄ in a surfactant and base oil. Has the property of reacting. Therefore, the magnetic fluids 15a and 15b are stably held at predetermined positions by a magnetic circuit formed between the magnet 12 and the inner ring 3, the outer ring 5 and the pole plate 14 made of a magnetic material. .

  Further, a step 5b is formed on the inner surface of the outer ring 5 on the rolling element side with respect to the magnet 12, and the step 5b causes the outer ring 5 to have a thin area 5A on the opening side and a thick area 5B on the rolling element side. Thus, the inner and outer ring intervals on the outer side in the axial direction are formed larger than those on the inner side. The step 5b is formed so as to generate a gap (step gap) for holding the magnetic fluid. In the present embodiment, the step 5b is formed to be a surface 5c perpendicular to the axial direction ( By using a vertical surface, the magnet 12 can be attracted, positioned and fixed as will be described later. Note that the step is not limited to a vertical surface as in this embodiment, and can be formed in a step shape as long as the magnetic fluid can be stably held between the magnet 12 and It may be formed in an inclined shape (slope). In this case, it is possible to position the magnet 12 and hold the magnetic fluid by using the inclined surface.

  The electrode plate 14 has an outer diameter slightly larger than the inner peripheral surface of the outer ring 5 (the inner peripheral surface of the thin wall region 5A), and is pressed into the opening side of the outer ring 5 together with the bonded magnet 12. It has become so. Further, the electrode plate 14 to which the magnet 12 is bonded is formed in such a size that a predetermined gap G is generated between the electrode plate 14 and the outer ring surface of the inner ring 3 when press-fitted into the outer ring 5. Further, the axial lengths of the magnet 12 and the electrode plate 14 are formed such that a gap G1 is generated with respect to the vertical surface 5c by the step 5b when the magnet 12 and the electrode plate 14 are press-fitted in a state where they are adhered. Yes.

  As described above, when the pole plate 14 to which the magnet 12 magnetized so that the magnetic pole is directed in the axial direction is press-fitted into the outer ring 5, the inner ring 3 side and the outer ring 5 side are Magnetic fluxes (magnetic circuits 3M and 5M) that are symmetric with respect to the direction are formed. Therefore, the inner ring-side magnetic fluid 15b and the outer ring-side magnetic fluid 15a are held in the gap G between the electrode plate 14 and the inner ring 3 and the gap G1 between the magnet 12 and the outer ring 5, respectively. It becomes possible to make it. Specifically, when the magnetic fluid is filled in the gap G with an injection device such as a dropper, the magnetic fluid is held in the gap G by the magnetic circuit 3M, and moves to the gap G1 side as it is and is formed on the outer ring side. The circuit 5M also holds the gap G1.

  According to the bearing 1 having the above-described configuration, a sealing effect is obtained even on the side where the magnet 12 and the electrode plate 14 are fixed (in this embodiment, the inner peripheral surface of the outer ring 5). It is possible to reliably prevent moisture and dust from entering the rolling element 7 side. That is, the conventional bearing with a magnetic fluid seal does not consider the necessity of sealing on the side on which the magnet and the electrode plate are fixed, and the sealing effect on the rolling elements is not sufficient. In addition to the sealing of the inner ring side magnetic fluid 15b, the outer ring side magnetic fluid 15a on the fixed side is also sealed, so that a sufficient sealing effect can be exhibited.

  Further, when sealing, it is only necessary to magnetize the magnetic pole of the magnet 12 which is one member so as to be in the axial direction, and to arrange it so as to be in contact with the pole plate 14, so that the number of parts is small, and Since the magnet 12 does not need to have a precise dimensional accuracy, the assembling work is facilitated and the cost can be reduced. That is, a sufficient sealing effect can be exhibited even when a magnet having a disadvantage in dimensional accuracy is used with respect to other members.

  Furthermore, the magnet 12 that holds the magnetic fluid on both the inner ring side and the outer ring side is configured as one member, and a magnetic fluid seal is formed on the inner ring side and the outer ring side at the same time by lubrication work from one place. Therefore, workability is improved.

  Further, in the present embodiment, since the step 5b is formed in the outer ring 5, a space (step gap) for effectively holding the magnetic fluid can be formed using the step, and the sealing effect can be easily achieved. Can be increased. In FIG. 2, the outer ring-side magnetic fluid 15 a is held in the gap G <b> 1, but the gap between the outer peripheral surface of the magnet 12 and the inner peripheral surface of the outer ring 5, or the inner periphery of the electrode plate 14 and the outer ring 5. It is possible to penetrate even a slight gap between the surfaces, and a sufficient sealing function is exhibited on the outer ring side.

FIG. 3 is a diagram illustrating a modification of the above-described embodiment.
In the embodiment shown in FIGS. 1 and 2, the electrode plate 14 is configured with the same thickness in the radial direction. However, as shown in FIG. 3, a portion for holding a magnetic fluid (in this embodiment, It is preferable to form a taper so that the thickness gradually decreases toward the inner side in the radial direction (the thin-walled portion is indicated by reference numeral 14A).

  According to such a configuration, since the magnetic fluid 15b does not jump out to the outside in the axial direction (outside from the exposed end surfaces 5a and 3a of the outer ring and the inner ring), the magnetic fluid is prevented from being wiped off during the assembling work. It is possible to perform a stable filling operation.

FIG. 4 is a diagram showing a second embodiment of the present invention.
In this embodiment, the size of the electrode plate 14 in the radial direction is formed such that some degree of play (gap G2) occurs with respect to the inner peripheral surface of the outer ring 5.

  Therefore, when the electrode plate 14 to which the magnet 12 is bonded (which may not be bonded) is simply inserted from the opening side of the inner ring and the outer ring, the magnet 12 is attracted to the vertical surface 5c where the magnet 12 is a step. It will be positioned and fixed by force. In such an assembled state, when the magnetic fluid is filled into the gap G and the gap G2 with an injection device such as a syringe, the magnetic fluid is separated by the magnetic circuit 3M from the gap G (the inner ring 3 and the electrode plate 14). And is held in the gap G2 (between the outer ring 5 and the electrode plate 14) by the magnetic circuit 5M. Further, the magnetic fluid filled in the gap G moves to the step side as it is and is also held by the step portion between the magnet 12 and the outer ring 5 (between the magnet 12 and the outer ring 5), so that the sealing effect on the outer ring side is achieved. Get higher.

  According to such a configuration, the work of assembling the electrode plate 14 to which the magnet 12 is bonded can be easily performed, and the direction of the magnet can be easily managed when sealing both side opening portions of the bearing. Further, since the electrode plate 14 is formed so as to have the gap G2, a deformation load is not applied to the outer ring 3 during the assembling work, and the rotational performance of the bearing is not deteriorated. Note that the gap G2 may be set to 10 to 500 μm, preferably 20 to 200 μm in consideration of assembling workability and sealing performance.

FIG. 5 is a diagram showing a modification of the above-described second embodiment.
In this modification, a step 3b is formed on the inner ring side, a surface 3c perpendicular to the axial direction is formed on the inner ring side, and a magnet 12 and a pole plate 14 similar to the configuration shown in FIG. (A structure symmetrical to the structure shown in FIG. 4).
The bearing having such a configuration has a structure suitable for installation on a member that rotates on the outer ring side.

  1 to 3 described above, the magnet 12 and the electrode plate 14 may be mounted on the inner ring side as in the structure shown in FIG.

FIG. 6 is a diagram showing a third embodiment of the present invention.
In this embodiment, the outer ring 5 is formed longer in the axial direction than the inner ring 3 to form an elongated cylindrical part 5D that protrudes from the exposed end surface 3a of the inner ring 3, and the elongated cylindrical part 5D has the same configuration as described above. A magnetic fluid seal 10 is provided.

  In this case, the axial length of the elongated cylindrical portion 5D is the same as that of the exposed end surface 3a of the inner ring 3 in a state where the magnet 12 is attracted to the vertical surface 5c formed by the step 5b on the outer ring side and positioned and fixed. The gap G3 is set to be generated between the two. That is, in the configuration of the present embodiment, the size H in the radial direction of the magnet 12 can be increased as compared with the above-described embodiments and modifications, so that the magnetic force can be increased and the sealing performance is increased ( Magnetic fluid retention). Further, the magnetic fluid 15b on the inner ring side is on the inner side in the axial direction and is not exposed to the outside, so that it is prevented from being wiped off during assembling work or the like, and a stable filling work can be performed. In this embodiment, the outer ring 5 side is the elongated cylindrical part, but the inner ring 3 side may be the elongated cylindrical part.

  In the configuration of the above-described embodiment and modified example, it is preferable that the surfaces of the inner ring 3 and the outer ring 5 are subjected to electrolytic chromic acid treatment. By applying electrolytic chromic acid treatment in this way, it is possible to prevent the surface from cracking and tearing due to rust and corrosion, and it is possible to reliably prevent dust and foreign matter from entering the inside. Become.

  In the above configuration, a ring-shaped shield (sealing cover) may be press-fitted and fixed from the outside in the axial direction on the surface on the outer side in the axial direction of the electrode plate 14 disposed on the opening side. Such a shield can be formed of a material excellent in corrosion resistance and heat resistance, such as stainless steel (SUS304) or resin, and the provision of such a shield makes it more effective to intrude foreign matter. It is possible to effectively prevent magnetic substances (foreign matter) such as iron sand from adhering to the magnet 12.

  Furthermore, in the above-described configuration, a thin washer and a spacer member for positioning may be disposed between the magnet 12 and the outer ring 5 (or the inner ring 3). By disposing such washers and spacers, dimensional management is simplified, and it is possible to further improve the assemblability. These washers and spacers are preferably made of a magnetic material so that a stable magnetic circuit is formed.

  About the bearing provided with the magnetic fluid seal comprised as mentioned above, it can be installed in the rotating shaft part of various apparatuses in which dust resistance and waterproofness are requested | required, and especially has salt content (seawater) Under the environment, it will be a severe condition. That is, since seawater has a low viscosity, it easily penetrates from a small gap, and when it enters and then dries, the salt content crystallizes and remains, and if such crystals adhere to the rolling element part, the rotational performance This is because the remarkably decreases.

For this reason, about the bearing of embodiment mentioned above, it arrange | positions in the drive-shaft part of the power transmission part in the various fishing reels used on the seaside or the sea, and a drive-shaft part is stabilized over a long period of time. It is possible to support.
Here, rotations after immersion of salt water in each of the above-described bearings installed in the rotating shaft portion rotated by the handle of the spinning reel and the conventional bearings installed Table 1 shows the results of testing for performance (smoothness felt when the handle is rotated).

  In Table 1 below, Conventional Example 1 is a handle shaft bearing (rotary shaft) bearing sealed with a generally known rubber packing, and Conventional Example 2 is a magnetic fluid seal. Although equipped with a bearing (the method disclosed in Japanese Utility Model Publication No. 1-91125) in which a magnet is sandwiched between two electrode plates and fixed on the outer ring side and sealed, Example 1 is described above. 1 and FIG. 2 are provided with the bearing of the embodiment, Example 2 is provided with the bearing of the embodiment shown in FIG. 4, and Example 3 is shown in FIG. The bearing of the embodiment is installed.

  In Table 1, as for the rotational resistance, those having a small rotational resistance are indicated by ◯, and those having a large rotational resistance are indicated by ×. As for sensory evaluation, a smooth feeling is indicated by ◯ and a rough feeling is indicated by × when rotating. In this case, the test after immersion in salt water shows the results obtained when the rotating operation was performed while immersing the bearing part in 5% salt water for 1 minute, and then the dried material was rotated. .

  In addition, for the bearings with the sealing function described above, evaluation tests were also conducted on the ease of assembly of the bearings themselves and the productivity with respect to the handleability when incorporated in the handle shaft portion. In Table 1, with respect to ease of assembly, the very easy ones are indicated by も の, the one that takes a little time is indicated by Δ, and the one that takes time is indicated by ×. In Table 1, with regard to handling, very easy items are indicated by ◎, easy items are indicated by ○, and items requiring attention are indicated by △.

  Regarding rotational performance, the rubber packing method (conventional example 1) felt heavy operation because of its large rotational resistance, but the other magnetic fluid seal methods (conventional example 2 and examples 1 to 3) The rotational resistance was small and the operation felt light. Moreover, at the initial stage before immersion in salt water, none of the bearings had a rough feeling during rotation. And when it rotated after salt water immersion, in the structure of the prior art example 2, the rough feeling arose. This is because salt water entered the rolling element portion from the unsealed portion, which dried and crystallized. In this case, although the rough feeling was not felt about the prior art example 1, when it repeats experiment for a long period of time and rubber packing begins to deteriorate, compared with Example 1 to 3, a rough feeling is felt early. It is thought to occur. In addition, about the structure of Examples 1-3, since a magnetic fluid does not flow out, a smooth rotation feeling can be obtained over a long period of time.

  Regarding the ease of assembly, the rubber packing method (conventional example 1) takes some time to arrange the rubber packing, and in Example 1, the press-fitting process of the electrode plate 12 is delicate. It took. In addition, since the method of the conventional example 2 is difficult to be unitized, it takes much time to assemble. On the other hand, in the types of Examples 2 and 3, it was only necessary to insert the electrode plate to which the magnet was bonded from the exposed end face side, and it was easy to assemble because the magnet attracting force was used.

  Regarding the handling property, there is no problem in the rubber packing method (conventional example 1), but in the magnetic fluid seal method, Example 3 has no magnetic fluid, so it was not inadvertently wiped off. Further, in Example 2, the magnetic fluid is slightly behind the opening, so that it is difficult to wipe off. In Example 1 and Conventional Example 2, the magnetic fluid is at the end, so that it may be accidentally wiped off. Yes, care must be taken in terms of handling.

  As is apparent from the above test results, according to the configuration of the present invention, a conventional rubber packing type bearing or a bearing with a magnetic fluid seal in which one of the outer ring / inner ring is fixed and the other is held with a magnetic fluid. In comparison with, excellent results were obtained in terms of sealability and productivity.

DESCRIPTION OF SYMBOLS 1 Bearing with magnetic fluid seal 3 Inner ring 3a Exposed end surface 5 Outer ring 5b Step 5c Vertical surface 5a Exposed end surface 7 Rolling body 10 Magnetic fluid seal 12 Ring-shaped magnet 14 Ring-shaped electrode plates 15a and 15b Magnetic fluids G, G1 to G3 Gap

Claims (6)

A plurality of rolling elements are interposed between an inner ring formed of a magnetic material and an outer ring formed of a magnetic material, and a ring-shaped magnet is disposed on the opening side of the inner ring and the outer ring to hold a magnetic fluid. , A magnetic fluid seal bearing for sealing the plurality of rolling elements,
The ring-shaped magnets are magnetized so that the magnetic poles face in the axial direction and form magnetic circuits on the outer ring side and the inner ring side, respectively.
A ring-shaped electrode plate that is disposed in contact with the outer surface in the axial direction of the ring-shaped magnet, and is formed of a magnetic material having substantially the same shape as the ring-shaped magnet and having an outer ring as a fixed side ;
An outer ring-side magnetic fluid held at least between the outer ring and the ring-shaped magnet by a magnetic circuit formed on the outer ring side;
An inner ring-side magnetic fluid held in a gap formed at least between the outer circumferential surface of the inner ring and the ring-shaped electrode plate facing the outer circumferential surface by a magnetic circuit formed on the inner ring side;
A bearing with a magnetic fluid seal, comprising: The bearing with a magnetic fluid seal according to claim 1, wherein the ring-shaped electrode plate is formed with a taper that gradually becomes thinner toward the inner ring side . A step is formed on the inner surface of the outer ring on the rolling element,
The bearing with a magnetic fluid seal according to claim 1, wherein the ring-shaped magnet is positioned and fixed against the step. A plurality of rolling elements are interposed between an inner ring formed of a magnetic material and an outer ring formed of a magnetic material, and a ring-shaped magnet is disposed on the opening side of the inner ring and the outer ring to hold a magnetic fluid. , A magnetic fluid seal bearing for sealing the plurality of rolling elements,
The ring-shaped magnets are magnetized so that the magnetic poles face in the axial direction and form magnetic circuits on the outer ring side and the inner ring side, respectively.
A ring-shaped electrode plate that is disposed in contact with the outer surface in the axial direction of the ring-shaped magnet, and is formed of a magnetic material having substantially the same shape as the ring-shaped magnet and having an inner ring as a fixed side;
An outer ring-side magnetic fluid held in a gap formed between at least the inner circumferential surface of the outer ring and the ring-shaped electrode plate facing the inner circumferential surface by a magnetic circuit formed on the outer ring side;
An inner ring-side magnetic fluid held at least between the inner ring and the ring-shaped magnet by a magnetic circuit formed on the inner ring side;
A bearing with a magnetic fluid seal, comprising: The bearing with a magnetic fluid seal according to claim 4, wherein the ring-shaped electrode plate is formed with a taper that gradually becomes thinner toward the outer ring side. A step is formed on the outer surface of the inner ring on the rolling element side,
The bearing with a magnetic fluid seal according to claim 4 or 5, wherein the ring-shaped magnet is positioned and fixed against the step.

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