JPH0723613Y2 - Bearing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a bearing device using a magnetic fluid for a sealing device.

[Conventional technology]

As a conventional bearing device of this type, for example, there is one used for a magnetic disk spindle. This is what is shown in FIGS. 2 and 3, and FIG. 2 is a sectional view thereof, and FIG. 3 is an enlarged view of a main part of FIG.

In the figure, H is a housing, S is a shaft, B is a bearing interposed between the housing H and the shaft S, C is a sealing device, R is a rotor mounted on the shaft S, and D is an outer peripheral portion of the rotor R. The magnetic disk P provided is a pulley attached to the shaft S, and is driven by a drive belt (not shown). F is a dustproof case.

The bearing B has a ball (rolling element) 3 between the outer ring 1 and the inner ring 2.
And a grease seal plate 4 that covers the opening between the outer ring 1 and the inner ring 2 at the end of the outer ring 1 by means of a retaining ring 5 attached to the housing H to keep a predetermined distance. It has been positioned.

As shown in FIG. 3, the sealing device C includes a pair of pole pieces.
A ring-shaped seal member 8 which is integrally bonded by sandwiching the magnet 7 with 6, 6 is arranged on the rotor side of the bearing B via a spacer 9 of a non-magnetic material, and the outer peripheral surface of the seal member 8 is disposed. Is bonded and fixed to the inner peripheral surface of the housing H, and a seal gap g is provided between the shaft H and the shaft S.
It is constructed by injecting 10.

With such a configuration, a magnetic circuit 11 is formed between the pole pieces 6, 6 and the shaft S, and the magnetic fluid 10 injected into the seal gap g is retained with sufficient pressure resistance. As a result, the lubricant contained in the bearing B, for example, the mist from which oil such as grease has evaporated can be completely sealed so as not to leak to the magnetic disk D side.

[Problems to be solved by the device]

However, in such a conventional bearing device,
Since the seal member 8 has a three-layer structure of a pair of pole pieces 6, 6 and the magnet 7, and the member 8 and the bearing B are arranged in parallel via the spacer 9, The volume occupied in the direction of the shaft S, that is, the total thickness t obtained by adding the thickness of the spacer 9 to the thickness of the seal member 8 (2h ₁ + h ₂ ).
However, there is a problem in that it is not suitable for a motor that is required to be thin, such as a magnetic disk motor.

The present invention has been made in order to solve such a conventional problem, and a magnetic circuit of a seal device is formed by using a magnetic seal plate and a bearing, and an annular cut provided on an inner ring or an outer ring. (EN) Provided is a bearing device which can be made thin by mounting a sealing device on the notch part and which can sufficiently maintain the pressure resistance of magnetic fluid by making the pole piece and the outer ring a short circuit. With the goal.

[Means for Solving the Problems]

The bearing device according to the present invention includes a first magnetic orbital theory, a second magnetic orbital theory that rotates relative to the first magnetic orbital theory via magnetic rolling elements coaxially with the first magnetic orbital theory, and a seal installed between the two orbital theories. The first magnetic orbital theory has an annular cutout portion on the outer surface on the side of the magnetic rolling element, and the sealing device is inserted into the cutout portion and A seal gap is provided between the annular magnetic plate fixed to the side wall, the annular magnet fixed to the outer surface of the magnetic plate by partially inserting it into the notch, and the second magnetic orbit theory. An annular pole piece provided and fixed to the annular magnet, and a magnetic fluid interposed in the seal gap.

[Action]

(1) Since the magnets are fixed to the first magnetic orbit theory and arranged in parallel with the magnetic plate attached to the first magnetic orbit theory, the passage of the magnetic flux flowing from the magnet to the bearing is widened and the number of magnetic fluxes is increased. Therefore, the magnetic flux passing through the seal gap also increases,
The magnetic flux density of the gap becomes high.

Further, the magnetic circuit formed between the seal device, the bearing and the shaft is provided with only one seal gap. That is, one seal gap is provided between the seal device and the bearing, and the bearing functions as a pole piece. Therefore, the magnetic flux density of the seal gap becomes higher than that of the conventional two seal gaps.

For the above two reasons, the pressure resistance of the magnetic fluid held in the seal gap increases.

(2) Since the bearing is used as a pole piece, only one annular pole piece is required, and if the magnetic flux density in the seal gap is brought close to the conventional level, the thickness of the annular magnet can be reduced accordingly. Moreover, the spacer provided between the seal device and the bearing is not required.

Further, since the magnetic seal plate and a part of the annular magnet are attached by being inserted into the annular cutout portion provided in the first magnetic track member, the thickness of the sealing device becomes thin and at the same time, the entire magnet is removed. Since it is not inside the notch, the pole piece and the first magnetic orbit theory do not create a short circuit.

〔Example〕

An embodiment of this invention will be described below with reference to FIG. First
The same or equivalent parts as those in FIGS. 2 and 3 are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, k ₁ is an annular notch provided on the axial side surface of the outer ring 1, and k ₂ is an annular notch provided on the axial side surface of the inner ring 2. Both notches k ₁ and k ₂ form a recess extending over the outer ring 1 and the inner ring 2. The grease seal plate 4 is contained in the annular cutout portion k ₁ and is fixed to the side wall of the cutout portion.

C ₁ is a sealing device, which is an annular magnet 12 fixed to the grease seal plate 4 and an annular pole piece fixed to the magnet 12.
13 and a magnetic fluid 14 injected into a seal gap g provided between the pole piece 13 and the shaft S. The magnet 12 and the pole piece 13 are both plate-shaped, and are integrally bonded beforehand to form a seal member e, and then fixed on the grease seal plate 4. At this time, the inner peripheral edge of the magnet 12 faces the cutout portion k ₂ so that it does not interfere with each other with a certain gap therebetween.

The outer ring 1, inner ring 2, balls 3, grease seal plate 4 and shaft S are all made of a magnetic material.

In the case of this embodiment, the outer ring 1 is the first magnetic orbit theory of the present invention, and the shaft S and the inner ring 2 attached thereto are the second magnetic orbit theory of the present invention.

With such a structure, a magnetic circuit 15 is formed between the seal device C ₁ , the shaft S and the bearing B, and the magnetic fluid 14 in the seal gap g is sufficient to maintain the sealing function. It is held with pressure resistance.

The magnetic circuit 15 configured in the embodiment, unlike the conventional one, has a gap only in the portion sealed with the magnetic fluid, and the other is in contact with the inner ring from the outer ring through the rolling elements (balls), Since the oil film thickness is very small, it is directly connected if ignored.

Further, in this embodiment, the grease seal plate 4 is a magnetic body, but the magnetic path is formed by passing through the outer ring, balls, and inner ring that are in direct contact with each other, rather than passing between the grease seal plate 4 and the inner ring.

In the conventional seal structure, the magnetic path can be formed only through the two seal gaps g, whereas the seal structure of the embodiment directly communicates with the magnetic material except the magnetic fluid injection part. The magnetic flux density can be increased. Conversely, the thickness of the magnet for obtaining the required predetermined withstand pressure can be made much smaller in the present invention than in the conventional product.

In this way, a thin seal structure is possible due to the two effects that only one pole piece is required and the thickness of the magnet can be reduced.

Next, and one of the pole pieces 6,6 were using two conventional, since the spacer 9 which has been interposed between the bearing B is not necessary, that amount of the sealing device C ₁ volume occupied by the shaft S direction, i.e. the thickness t ₁ of the sealing device C ₁ can be reduced than the thickness t of the conventional seal device C.

Further, since the grease seal plate 4 and a part of the magnet are mounted in the annular notch k ₁ provided in the outer ring 1 so as to be closer to the ball 3 side, the thickness of the sealing device becomes thin and at the same time. Since the magnet 12 is not entirely in the notches k ₁ and k ₂ , the pole piece 13 and the outer ring 1 do not form a short circuit. Therefore, the magnetic disk motor or the like can be made thinner.

Further, in this embodiment, the seal member e can be formed only by bonding the magnet 12 and the pole piece 13 together. For this reason, not only the number of man-hours required for the bonding is small and the bonding work is not troublesome, but it is not necessary to provide the concentricity between the pole pieces 6 and 6 as in the conventional case, so that the concentricity with respect to the shaft S is easily achieved. . For this reason, the assembling accuracy of the sealing device can be increased, and therefore, also in this aspect, the pressure resistance of the magnetic fluid is improved.

Next, as described above, using the bearing as one of the magnetic poles (pole pieces) brings great benefits.
In general, as a problem, there is a concern that the acoustic life is shortened by passing the magnetic flux through the bearing. It is considered that the decrease in the acoustic life is caused when the wear is generated in the bearing, because the abrasion powder is magnetically captured and is difficult to be separated from the rolling portion, and the rolling surface is damaged.

In this respect, the inventor also conducted a number of durability tests.

As a result, although it is usually disliked to let the magnetic flux pass through the bearing regardless of size, experiments have shown that, like magnetic disk motors, the ambient temperature, load, rotational speed, mounting accuracy, etc. It proved unlikely that problems would occur if the conditions were mild and blessed with very little wear itself. However, the part that is most likely to wear is the cage that slides between the balls, so it is preferable to use non-magnetic stainless steel or plastic for this cage. It is not worn and is the most suitable bearing device of the present invention. That is, if a bearing device using this plastic retainer is applied to this invention, a bearing device having a higher function can be obtained. Further, the magnetic flux in the bearing can be positively used to hold the magnetic fluid at the rolling element, and the bearing can be lubricated with the magnetic fluid itself instead of the grease.

Currently, hard grease that does not easily generate mist is used as grease, so there is a problem that abnormal noise is likely to occur in the bearing.However, since magnetic fluid is oil, it has extremely high lubricity and lowers torque. This has a great advantage that no abnormal noise is generated.

[Effect of device]

As described above, according to the present invention, the magnetic circuit for holding the magnetic fluid of the seal device is configured by using the bearing and the magnetic seal plate, and the annular circuit provided in the first magnetic orbit theory is used. Since the magnetic plate is put in the cutout part and a part of the magnet is put in and installed, it is possible to make the device such as a magnetic disk device thinner, and the whole magnet has a cutout part. Since it does not enter the inside, the pole piece and the first magnetic starting member do not form a short circuit, and the pressure resistance of the magnetic fluid can be sufficiently maintained.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the present invention, FIG. 2 is a sectional view of a conventional bearing device, and FIG. 3 is an enlarged view of an essential part of FIG. H ... Housing S ... Shaft (second magnetic orbit theory) B ... Bearing 1 ... Outer ring (first magnetic orbit theory) 2 ... Inner ring (second magnetic orbit theory) 3 ... Ball (magnetic rolling element) 4 ... Grease seal plate (magnetic plate) C ₁ ...... Sealing device 12 ...... Ring magnet 13 …… Ring pole piece g …… Seal gap 14 …… Magnetic fluid k ₁ , k ₂ …… Ring notch Department

Claims (1)

[Scope of utility model registration request] 1. A first magnetic orbital theory, a second magnetic orbital theory which relatively rotates relative to the first magnetic orbital theory via magnetic rolling elements, and a sealing device mounted between the two orbital theories. Becomes
Further, the first magnetic orbit theory has an annular cutout portion on the magnetic rolling element side of the outer surface, and the sealing device is put in the cutout portion and fixed to the side wall of the cutout. Seal gap between the grease seal plate, the annular magnet fixed to the outer surface of the grease seal plate by partially inserting it into the notch, and the shaft to which the second magnetic orbit theory is attached. Is provided on the side surface of the annular magnet,
A bearing which is located outside the end face of the first orbital theory and is composed of a fixed annular pole piece so as not to contact the first orbital theory and a magnetic fluid interposed in the seal gap. apparatus.