WO2017090778A1 - 磁性流体シール付き軸受 - Google Patents
磁性流体シール付き軸受 Download PDFInfo
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- WO2017090778A1 WO2017090778A1 PCT/JP2016/085833 JP2016085833W WO2017090778A1 WO 2017090778 A1 WO2017090778 A1 WO 2017090778A1 JP 2016085833 W JP2016085833 W JP 2016085833W WO 2017090778 A1 WO2017090778 A1 WO 2017090778A1
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- ring
- magnetic
- electrode plate
- outer ring
- inner ring
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/72—Sealings
- F16C33/76—Sealings of ball or roller bearings
- F16C33/78—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members
- F16C33/7803—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members suited for particular types of rolling bearings
- F16C33/7806—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members suited for particular types of rolling bearings for spherical roller bearings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/72—Sealings
- F16C33/76—Sealings of ball or roller bearings
- F16C33/762—Sealings of ball or roller bearings by means of a fluid
- F16C33/763—Sealings of ball or roller bearings by means of a fluid retained in the sealing gap
- F16C33/765—Sealings of ball or roller bearings by means of a fluid retained in the sealing gap by a magnetic field
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- 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
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/72—Sealings
- F16C33/76—Sealings of ball or roller bearings
- F16C33/78—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members
- F16C33/784—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members mounted to a groove in the inner surface of the outer race and extending toward the inner race
- F16C33/7843—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members mounted to a groove in the inner surface of the outer race and extending toward the inner race with a single annular sealing disc
- F16C33/7846—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members mounted to a groove in the inner surface of the outer race and extending toward the inner race with a single annular sealing disc with a gap between the annular disc and the inner race
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/40—Sealings between relatively-moving surfaces by means of fluid
- F16J15/43—Sealings between relatively-moving surfaces by means of fluid kept in sealing position by magnetic force
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2300/00—Application independent of particular apparatuses
- F16C2300/40—Application independent of particular apparatuses related to environment, i.e. operating conditions
Definitions
- 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 matters such as dust and moisture from entering inside.
- a rotating shaft installed in various driving force transmission mechanisms is rotatably supported through a bearing.
- 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.
- Patent Document 1 discloses a bearing with a magnetic fluid seal having a sealing function with a magnetic fluid.
- the bearing with a magnetic fluid seal disclosed in Patent Document 1 has a ring-shaped electrode plate attached with a ring-shaped (annular) magnet attached to (inserted into) 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, entry of foreign matter into the inside is prevented.
- the ring-shaped magnet is magnetized in the axial direction, and a ring-shaped electrode plate is attached to the opening side thereof.
- a minute gap generated on the mounting side of the ring-shaped electrode plate (ring-shaped magnet) (hereinafter, a gap is generated on the mounting side).
- the magnetic fluid is also retained in such a manner that the foreign matter does not enter from the outer ring side and the inner ring side.
- the magnetic field strength of the magnetic circuit generated on the gap side is the mounting side (insertion side). It becomes weaker than the magnetic field strength of the magnetic circuit generated in That is, in FIG. 1A, if a gap is formed on the inner ring side, a nonmagnetic material is interposed in that portion, so that the magnetic permeability is reduced, and the magnetic force is reduced from the end face 30a of the pole plate 30.
- the magnetic force (magnetic field strength) toward the inner ring that is a material is weaker than the magnetic force (magnetic field strength) that is directed from the end face 30b of the electrode plate 30 to the outer ring that is a magnetic material.
- the holding force of the magnetic fluid held in the gap is weak, and sufficient and stable sealing performance cannot be obtained.
- the present invention has been made paying attention to the above-described problems, and an object thereof is to provide a bearing with a magnetic fluid seal that can obtain a stable sealing performance in a gap portion.
- a bearing with a magnetic fluid seal includes 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. It is attached to the inner peripheral surface of the outer ring so that a gap is formed between the outer peripheral surface of the outer ring and the ring-shaped electrode plate formed of a magnetic material and the inner surface in the axial direction of the ring-shaped electrode plate.
- a ring-shaped magnet that is magnetized so that the magnetic poles face in the axial direction and forms a magnetic circuit on each of the outer ring side and the inner ring side, and the inner ring side that is held by the magnetic circuit on the inner ring side and seals the gap It has a magnetic fluid and a magnetic field strength improving unit that makes 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.
- a symmetrical magnetic circuit is formed on the inner ring side and the outer ring side by attaching the ring-shaped magnet magnetized in the axial direction to the ring-shaped pole plate.
- 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 formed between the outer ring surface of the inner ring and the magnetic force on the inner ring side is reduced by the magnetic field strength improving unit. 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 a stable sealing characteristic can be obtained.
- the magnetic field strength improving unit described above is such that 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 electrode plate. What is necessary is just to become the structure to perform.
- the magnetic field strength improving portion is configured by forming a ring-shaped electrode plate 30 such that the inner ring side Y1 is thicker than the outer ring side Y2 (T1> T2). With this 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.
- 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 at the gap portion is effectively increased, and the magnetic permeability is reduced by the gap. Even so, it is possible to obtain a sufficient magnetic force. Accordingly, by arranging the ring-shaped electrode plate and the ring-shaped magnet having such a magnetic field strength improving portion between the inner and outer rings, the magnetic field strength on the gap side is the conventional configuration (the configuration shown in FIG. 1A). ) Can be efficiently increased, and stable sealing characteristics can be obtained.
- a ring-shaped electrode plate is formed to have a tapered surface that gradually becomes thinner from the inner ring side toward the outer ring side, or the inner circumference of the ring-shaped electrode plate and the outer ring. It can be configured by interposing a nonmagnetic spacer between the surface and the surface. Further, in a configuration in which a minute gap is generated 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 held in that portion. Preferably, this makes it possible to reliably seal the inside.
- the ring-shaped electrode plate on which the ring-shaped magnet having the above-described configuration is attached is attached to the outer peripheral surface of the inner ring, contrary to the above-described configuration, and a gap is formed on the outer-ring side to form a magnet on the outer-ring side. It may hold the fluid and seal the inside.
- a bearing with a magnetic fluid seal capable of obtaining a stable sealing performance in the gap portion is obtained.
- FIG. 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 enlarged view of the principal part of FIG. The principal part enlarged view which shows the 2nd Embodiment of this invention.
- the principal part enlarged view which shows the 3rd Embodiment of this invention.
- the principal part enlarged view which shows the 4th Embodiment of this invention.
- FIG. 2 and 3 are views showing a first embodiment of a magnetic fluid seal bearing according to the present invention
- FIG. 2 is a cross-sectional view along the axial direction
- FIG. 3 is an enlarged view of a main part of FIG. It is.
- a magnetic fluid seal bearing (hereinafter also referred to as a bearing) 1 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.
- the rolling element 7 it does not necessarily need to be a magnetic body.
- the inner ring 3 and the outer ring 5 of the present embodiment are configured such 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 in the axial direction, and the inner ring 3 may be formed longer than the outer ring 5 in the axial direction.
- a magnetic seal mechanism (magnetic fluid seal) 10 described in detail below is installed on the opening side of the inner ring 3 and the outer ring 5.
- the magnetic seal mechanism 10 having the same configuration is disposed in the openings on both sides of the inner ring 3 and the outer ring 5, the upper right part (main part) of FIG. The description will be given with reference.
- the magnetic seal mechanism 10 includes a ring-shaped magnet (hereinafter also referred to as a magnet) 20 and a ring-shaped electrode plate (hereinafter also referred to as a pole plate) 30 that attaches the magnet 20 to the inner surface in the axial direction. , And a magnetic fluid (in this embodiment, the inner ring side magnetic fluid 25) held in the magnetic circuit formed by the magnet 20, and by these members, dust, It has a function of sealing so that moisture and the like do not enter.
- a ring-shaped magnet hereinafter also referred to as a magnet
- a ring-shaped electrode plate hereinafter also referred to as a pole plate
- a permanent magnet having a high magnetic flux density and a strong magnetic force for example, a neodymium magnet created 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).
- the electrode plate 30 is disposed in contact with the outer surface of the magnet 20 in the axial direction.
- the electrode plate 30 has a ring-like appearance substantially the same as the magnet 20, and is made of a magnetic material, for example, chromium-based stainless steel (SUS440C). Accordingly, as shown in FIG. 1, magnetic circuits M1 and M2 are formed on the inner ring side and the outer ring side, respectively.
- the magnetic fluid held by the magnetic circuit is configured by dispersing magnetic fine particles such as Fe 3 O 4 in a base oil with a surfactant, and has a viscosity and reacts when the magnet is brought close to it. It has. That is, it has a function of sealing such a gap by holding such a magnetic fluid in a gap G, which will be described later, and preventing foreign matter such as dust and moisture from entering inside.
- a step 5b is formed on the inner peripheral surface 5a on the rolling element side, and this 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.
- the step 5b is positioned and fixed by applying a magnet 20 (magnet 20 with the electrode plate 30 attached; electrode plate united with the magnet) that is inserted (inserted) from the opening side and attached at a predetermined position. It has a function. Therefore, the step 5b is preferably a plane perpendicular to the axial direction.
- 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.
- 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.
- the electrode plate 30 is formed to have a size protruding radially inward from the inner ring side edge surface 20 a of the magnet 20, and the magnet 20 is attached to the electrode plate 30 in the state of being attached to the inner ring 3.
- the outer circumferential surface 3a is formed such that a gap substantially equal to the gap G described above (a gap slightly larger than the gap G in the configuration shown in the figure) is formed.
- the magnetic fluid inner ring side magnetic fluid 25
- the magnet 20 and the electrode plate 30 may be fixed by magnetic adsorption, or may be fixed with an adhesive in addition to magnetic adsorption.
- 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.
- the inner ring-side magnetic fluid 25 is held so as to expand in the radial direction, and the sealing performance can be further improved.
- the electrode plate 30 is preferably fixed so as not to protrude in the axial direction from the exposed end surface position P of the inner ring 3 and the outer ring 5.
- the possibility of other objects coming into contact with the magnetic fluid 25 is reduced, and dissipation of the magnetic fluid is prevented. It becomes possible.
- the magnetic seal mechanism 10 is provided with a magnetic field strength improving unit 50 that makes 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 unit 50 may be any unit that relatively increases the amount of magnetic flux that flows to the inner ring side and the outer ring side through the pole plate 30 on both sides in the radial direction between the inner and outer rings.
- the pole plate 30 is provided with the magnetic field strength improving portion 50, and the inner ring side of the pole plate 30 is made thick and the outer ring side is made 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 inner ring on the outer ring. The magnetic field strength of the magnetic circuit formed on the side can be increased.
- the electrode 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 30C on the outer ring side is formed on the magnet 20. And the outer ring side edge surface 20b. According to such a configuration, the magnetic flux by the magnet 20 is biased toward the inner ring side, and the inner ring side magnetic fluid 25 can be stably held without lowering the magnetic force in the gap portion. Further, since the edge 30c on the outer ring side of the electrode plate 30 is made to coincide with the outer ring side edge surface 20b of the magnet 20, the both can be easily positioned.
- the inner ring-side magnetic fluid 25 is held in the inner ring-side gap G.
- a minute gap is formed between the inner peripheral surface 5 a of the outer ring 5 and the magnet 20. Since there is a possibility that this occurs, the sealing performance can be further improved by filling such a minute gap with an outer ring-side magnetic fluid (not shown).
- FIG. 4 is an enlarged view of a main part showing a second embodiment of the present invention.
- the magnetic field strength improving unit 50 of the present embodiment forms a tapered surface 30b that is gradually thinned from the inner ring side toward the outer ring side on the electrode plate 30, and terminates the taper surface at an intermediate portion thereof.
- 30 is formed in a substantially trapezoidal cross section. For this reason, a gap is formed between the thinned edge 30c 'on the outer ring side of the electrode plate 30 and the inner peripheral surface 5a of the outer ring 5, and this part serves as a nonmagnetic spacer. It becomes.
- FIG. 5 is an enlarged view of a main part showing a third embodiment of the present invention.
- the magnetic field strength improving unit 50 of the present embodiment has a ring-shaped spacer 51 made of a nonmagnetic material such as a resin disposed on the outer ring side of the pole plate 30 having a uniform thickness.
- a nonmagnetic spacer 51 By interposing such a nonmagnetic spacer 51 between the outer ring side edge 30c ′ of the electrode plate 30 and the inner peripheral surface 5a of the outer ring 5, it is formed on the inner ring side as in the above-described embodiment. Therefore, the inner ring-side magnetic fluid 25 can be stably held in the gap G.
- the spacer 51 may be a nonmagnetic material, and may be a nonmagnetic metal or a simple air layer.
- the spacer 51 preferably has a length in the radial direction that is longer than the length of the gap G. This makes it possible to more effectively improve the magnetic field strength on the inner ring side and stably hold the magnetic fluid. It becomes.
- the minute clearance between the inner peripheral surface 5a of the outer ring 5 and the magnet 20 is also filled with the outer ring-side magnetic fluid 25a, which makes it possible to further improve the internal sealing performance.
- Such outer ring side magnetic fluid 25a can be disposed by filling the outer ring side magnetic fluid as it is when filling the inner ring side magnetic fluid.
- FIG. 6 is an enlarged view of a main part showing a fourth embodiment of the present invention.
- the magnetic field strength improving unit 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 the ring-shaped electrode plate 30 is held on the inner side in the axial direction without exposing the surface.
- the electrode plate 30 and the magnet 20 can be unitized together with the spacer 53 with high accuracy, and the assembly can be easily performed. Further, in such a configuration, since the opening portion is in a state where the surface of the resin spacer 53 is exposed, the surface of the electrode plate can be protected, and further, the appearance can be improved by adding color or the like. You can also improve.
- the gap G is formed on the inner ring side, and the inner ring-side magnetic fluid is held in that portion.
- the gap G May be formed on the outer ring side.
- FIG. 7 is an enlarged view of a main part showing a fifth embodiment of the present invention.
- a magnetic fluid (outer ring side magnetic fluid) 26 is held between the outer ring side edge 30 c ′ of the electrode plate 30 and the inner peripheral surface 5 a of the outer ring 5 with the same configuration as in the first embodiment.
- the electrode plate 30 has a tapered surface 30b that is gradually thinned from the outer ring side toward the inner ring side, and a thinned edge 30a ′ on the inner ring side. Is matched with the inner ring side edge surface 20a of the magnet 20.
- the magnetic flux by the magnet 20 is biased toward the outer ring side, and the outer ring side magnetic fluid 26 can be stably held without reducing the magnetic force in the gap portion. Further, by aligning the inner ring side edge portion 30a 'of the pole plate 30 with the inner ring side edge surface 20a of the magnet 20, the positioning of the both can be performed easily.
- the inner ring side magnetic fluid is held in a minute gap generated on the inner ring side. You may do it.
- FIG. 8 is a diagram showing a magnetic field strength portion distribution comparing a magnetic circuit having a conventional configuration and a magnetic circuit having the configuration of the present invention.
- the bearings to be compared have the same conditions for 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, as shown in FIG.
- the electrode plate has a normal type shape, a non-magnetic spacer (air layer) is disposed on the outer ring side of the electrode plate, as shown in FIG. A taper surface is formed on the electrode plate.
- FIG. 8 shows a simulation of the magnetic field strength distribution on the personal computer software using the magnetic field analysis software that has been widely distributed for these three types of bearings.
- the magnetic field generated on the gap side is The strength is weak, and thus the magnetic fluid is retained, but the retaining force is weak.
- the 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 the magnetic fluid Is also stable.
- the length of the spacer in the radial direction is simulated to be slightly larger than the length of the gap. By further widening the length, it is possible to further increase the magnetic field strength on the gap side.
- the magnetic field strength improving portion described above in a normal arrangement configuration in which a ring-shaped electrode plate is disposed on a ring-shaped magnet, when this is incorporated between the inner and outer rings, If the magnetic field strength of the magnetic circuit generated on the gap side is improved as shown in FIG. 1B, for example, as shown in FIG.
- the magnet may be biased to the gap side
- the pole plate may be made of a material that increases the permeability and saturation magnetic flux density on the gap side.
- the magnet 20 is positioned and fixed by being applied to the step 5b formed on the outer ring side or the step 3b formed on the inner ring side, but without forming a step.
- a configuration in which the magnet 20 is fitted (press-fitted) and fixed may be used, or a configuration in which the electrode plate with the magnet attached is applied to a step or the like and positioned and fixed may be used.
- the electrode plate may be separately provided with irregularities or the like that contact the step.
- the surfaces of the inner ring 3 and the outer ring 5 are subjected to electrolytic chromic acid treatment.
- electrolytic chromic acid treatment 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.
- a ring-shaped shield (sealing cover) may be press-fitted and fixed to the outer surface in the axial direction from the outside in the axial direction.
- 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 20.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Sealing Using Fluids, Sealing Without Contact, And Removal Of Oil (AREA)
- Rolling Contact Bearings (AREA)
- Sealing Of Bearings (AREA)
Abstract
Description
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。
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。
磁界強度向上部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部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、磁界強度向上部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。
本実施形態の磁界強度向上部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。
本実施形態の磁界強度向上部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。
本実施形態の磁界強度向上部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。
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。
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。
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 磁界強度向上部
G 隙間
Claims (12)
- 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、磁性材で形成されたリング状の極板と、
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部と、
を有することを特徴とする磁性流体シール付き軸受。 - 前記磁界強度向上部は、内輪側が肉厚で外輪側が薄肉に形成された前記リング状の極板を有することを特徴とする請求項1に記載の磁性流体シール付き軸受。
- 前記リング状の極板は、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ことを特徴とする請求項2に記載の磁性流体シール付き軸受。
- 前記磁界強度向上部は、前記リング状の極板と外輪の内周面との間に介在される非磁性のスペーサを有することを特徴とする請求項1から3のいずれか1項に記載の磁性流体シール付き軸受。
- 前記非磁性のスペーサは樹脂材で形成されており、前記内外輪間の開口部分に表面が露出した状態で、前記リング状の極板を保持していることを特徴とする請求項4に記載の磁性流体シール付き軸受。
- 前記外輪の内周面と、前記リング状の極板及びリング状の磁石との間に生じる微小隙間に外輪側磁性流体を保持したことを特徴とする請求項1から5のいずれか1項に記載の磁性流体シール付き軸受。
- 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、磁性材で形成されたリング状の極板と、
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部と、
を有することを特徴とする磁性流体シール付き軸受。 - 前記磁界強度向上部は、外輪側が肉厚で内輪側が薄肉に形成された前記リング状の極板を有することを特徴とする請求項7に記載の磁性流体シール付き軸受。
- 前記リング状の極板は、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ことを特徴とする請求項8に記載の磁性流体シール付き軸受。
- 前記磁界強度向上部は、前記リング状の極板と内輪の外周面との間に介在される非磁性のスペーサを有することを特徴とする請求項7から9のいずれか1項に記載の磁性流体シール付き軸受。
- 前記非磁性のスペーサは樹脂材で形成されており、前記内外輪間の開口部分に表面が露出した状態で、前記リング状の極板を保持していることを特徴とする請求項10に記載の磁性流体シール付き軸受。
- 前記内輪の外周面と、前記リング状の極板及びリング状の磁石との間に生じる微小隙間に内輪側磁性流体を保持したことを特徴とする請求項7から11のいずれか1項に記載の磁性流体シール付き軸受。
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