JP7528594B2 - Rolling bearing and bearing device - Google Patents

Description

The present invention relates to rolling bearings and bearing devices.

The photosensitive drum of a general information device, for example a copying machine, is repeatedly charged and de-charged to produce an image. Specifically, the surface of the photosensitive drum is first charged with static electricity by a charging electrode, and then the image of the original is exposed to the surface of the photosensitive drum by a lamp and optical system. As a result, the static electricity in the exposed area (white area of the original) is de-charged by the light, and the image area remains charged. Next, when toner is supplied to the surface of the photosensitive drum, the toner adheres to the charged area of the surface of the photosensitive drum and the image appears. The toner adhered to the surface of the photosensitive drum is transferred to the copy paper by a transfer electrode, and the toner (image) transferred to the copy paper is fixed to the copy paper by heat and pressure and discharged. Meanwhile, the static electricity on the surface of the photosensitive drum is de-charged by a de-charging electrode in preparation for the next copy.

As this charging and de-charging is repeated, the photosensitive drum becomes statically charged. A rolling bearing is directly connected to the photosensitive drum, and it is known that when current flows through the contact area between the raceway and the rolling element, sparks occur through the thin lubricating oil film, causing the surface to melt locally and become uneven, i.e., electrolytic corrosion. As a countermeasure to this, it is widely practiced to pass electricity between the inner and outer rings using a conductive member such as a metal brush, as shown in Patent Document 1, for example.

Microfilm of Utility Model Application No. 02-50355 (Utility Model Application No. 04-8820)

One end of a conductive member such as a metal brush is attached to the inner surface of the outer ring and hangs down toward the inner ring, with the other end attached so that it slides against the outer surface of the inner ring. As a result, the distance between the conductive member and the raceway surface is short, which can cause contamination from the conductive member to get into the bearing and degrade the lubrication performance.

The present invention was made in consideration of these circumstances, and aims to prevent contamination from conductive members such as metal brushes from entering the inside of a rolling bearing equipped with such conductive members.

The above problems are solved by the following rolling bearing and bearing device according to the present invention.
(1) an inner ring having an inner ring raceway surface on an outer peripheral surface;
an outer ring having an outer ring raceway on an inner circumferential surface;
a plurality of rolling elements held between the inner ring raceway surface and the outer ring raceway surface so as to be capable of rolling;
A pair of seals are provided to seal a gap between the inner ring and the outer ring,
A rolling bearing in which a lubricant is sealed in a space between the inner ring, the outer ring, and the seal, and the rolling bearing is assembled into a bearing device,
the axial width of the inner ring is greater than the axial width of the outer ring,
a conductive member extending from an axial end of the inner ring on a side not facing the outer ring to an inner circumferential surface of a housing of the bearing device that is electrically conductive between the inner ring and the outer ring, the conductive member electrically connecting the inner ring and the housing;
A rolling bearing characterized in that the outer ring is provided with a through hole for supplying air to the space.
(2) The rolling bearing according to (1 ) above;
an air supply source for supplying air into the space through the through hole;
A bearing device comprising:

According to the present invention, in a rolling bearing equipped with a conductive member such as a metal brush, it is possible to prevent contamination from the conductive member from entering the inside of the bearing.

FIG. 1 is a cross-sectional view showing a first embodiment of a rolling bearing according to the present invention. FIG. 2 is a cross-sectional view showing a rolling bearing according to a second embodiment of the present invention. FIG. 3 is a sectional view showing a rolling bearing according to a third embodiment of the present invention.

The present invention will now be described in detail with reference to the drawings.

First Embodiment
1 is a cross-sectional view showing a first embodiment of a rolling bearing according to the present invention. As shown in the figure, the rolling bearing 1 includes an inner ring 7 having an inner ring raceway surface 6 on its outer peripheral surface 5, and an outer ring 4 having an outer ring raceway surface 3 on its inner peripheral surface 2, and a plurality of rolling elements 8 are held by a cage 9 between the inner ring raceway surface 6 and the outer ring raceway surface 3 so as to be freely rollable. The rolling bearing 1 shown in the figure is an angular bearing in which the outer peripheral surface 5 including the inner ring raceway surface 6 of the inner ring 7 is inclined. Furthermore, the gaps at both ends between the inner ring 7 and the outer ring 4 are sealed by a pair of seals 10, 10, and a lubricant such as grease or lubricating oil (not shown) is filled in the space between the inner ring 7, the outer ring 4, and the seals 10, 10, in other words, the bearing space formed by the seals 10, 10 and the rolling elements 8. In addition, in Figure 1, the pair of seals 10, 10 are shown to be of the contact type in which there is substantially no gap between the inner ring 7 or outer ring 4 and the seal 10, but they may also be of the non-contact type in which there is a predetermined gap between the inner ring 7 or outer ring 4 and the seal 10.

The inner ring 7 is fitted with the shaft 20 of the bearing device, and in this embodiment, it is an inner ring rotating type in which the inner ring 7 rotates as the shaft 20 rotates. The outer ring 4 is fitted into the housing 30. In this way, the rolling bearing 1 is assembled in a state where it is fitted between the shaft 20 and the housing 30 of the bearing device. The inner ring 7 is fitted with the shaft 20, so that the inner ring 7 and the shaft 20 are electrically connected, and the outer ring 4 is fitted with the housing 30, so that the outer ring 4 and the housing 30 are electrically connected.

In this embodiment, the outer ring 4 and the inner ring 7 each extend in the axial direction further toward the bearing end side (the right side in the example of FIG. 1) than the seal 10, and a disk-shaped conductive member 50 that electrically connects the outer peripheral surface 5 of the inner ring 7 and the inner peripheral surface 2 of the outer ring 4 is attached to the extension. In detail, the conductive member 50 extends from the extension of the outer ring 4, and its end 51 abuts against the outer peripheral surface 5 of the inner ring 7.

Therefore, for example, if static electricity (leakage current) generated in the housing 30 flows to the contact area between the outer ring raceway 3 and the rolling elements 8 in the rolling bearing 1, it is conducted from the outer ring 4 through the conductive member 50 to the shaft 20 and is neutralized. Alternatively, if static electricity (leakage current) generated on the shaft 20 flows to the contact area between the inner ring raceway 6 and the rolling elements 8 in the rolling bearing 1, it is conducted from the inner ring 7 through the conductive member 50 to the housing 30 and is neutralized.

The conductive member 50 may be a metal brush as in the past, but may also be, for example, a seal made of conductive rubber. The conductive member 50 may be attached to the extension of the outer ring 4 by adhesive, screwing, or other methods. Furthermore, although not shown, in order to prevent a decrease in conductivity due to wear over time caused by sliding contact, the conductive member 50 may be attached to a spring embedded in the inner ring 7 or the outer ring 4 and biased to the other side.

Here, as the shaft 20 and the inner ring 7 rotate, wear powder is generated from the end 51 of the conductive member 50 and the outer circumferential surface 5 of the inner ring 7, and there is a concern that this powder may become contaminants and enter the inside of the bearing through the pair of seals 10, 10.

However, in this embodiment, the outer ring 4 is provided with a through hole 15 that runs from the outer peripheral surface 14 of the outer ring 4 to a position other than the outer ring raceway surface 3 on the inner peripheral surface 2, for example, the position of the groove shoulder in FIG. 1, in the bearing space formed by the seals 10 and the rolling elements 8, that is, the space between the inner ring 7, the outer ring 4, and the seals 10, 10 (in other words, the bearing space formed by the seals 10, 10 and the rolling elements 8). Air is sent into the through hole 15 from the outside to increase the internal pressure of the bearing space. And by increasing the internal pressure of the bearing space, it is possible to prevent wear debris from entering the inside of the bearing.

As shown in FIG. 1, the housing 30 has a connecting portion 31 that connects to the through hole 15, and an air supply source (not shown) for supplying air is connected to the connecting portion 31.

Second Embodiment
In the first embodiment described above, the conductive member 50 is disposed between the inner ring 7 and the outer ring 4, but it is also possible to widen the outer ring 4 in the axial direction and attach the conductive member 50 between the outer ring 4 and the shaft 20 of the bearing device. Note that, like the first embodiment described above, this embodiment will be described using an example of an inner ring rotating type rolling bearing in which the inner ring 7 rotates together with the rotation of the shaft 20.

In this embodiment, as shown in FIG. 2, the axial width of one side of the outer ring 4 (the right side in the example of FIG. 1) is wider than the axial width of the inner ring 7, and a disk-shaped conductive member 50 is attached near the axial end of the outer ring 4 that does not face the inner ring 7, i.e., the side end face 40, closer to the bearing end side than the seal 10. As shown in the figure, the conductive member 50 extends from the axial end, and its end 51 abuts against the outer peripheral surface 21 of the shaft 20. Therefore, for example, when static electricity (leakage current) generated in the housing 30 flows to the contact portion between the outer ring raceway surface 3 and the rolling element 8 in the rolling bearing 1, it is conducted from the outer ring 4 through the conductive member 50 to the shaft 20 and is discharged.

In addition, there is a concern that wear powder will be generated from the end 51 of the conductive member 50 and the outer peripheral surface 21 of the shaft 20 as the shaft 20 rotates, and this will become contaminants and enter the inside of the bearing through the pair of seals 10, 10. However, in this embodiment, the conductive member 50 is provided at the axial end (near the side end surface 40) of the outer ring 4, which is axially wider than the inner ring 7, on the side that does not face the inner ring 7. Therefore, the end 51 is away from the inner ring 7 and the seals 10, 10, and there is a sufficient distance between the inner ring 7 and the seals 10, 10 and the end 51 of the conductive member 50 where wear powder may be generated, so that wear powder can be prevented from entering the inside of the bearing.

When the conductive member 50 is a seal using conductive rubber as described in the first embodiment, the rolling bearing 1 can be combined with the seals 10, 10 to form a double seal structure, and the conductive member 50 can prevent contamination from entering the inside of the bearing while ensuring sealing inside the bearing.

The distance L of the conductive member 50 to the attachment position on the inner peripheral surface 2 of the outer ring 4 (for convenience, the axial center position C of the conductive member 50 is defined in FIG. 2) is preferably as far away as possible from the side end surface 70 of the inner ring 7, and is determined appropriately taking into account the width of the entire bearing, etc.

Furthermore, in this embodiment, compared to the first embodiment, the concern that wear powder generated from the end 51 of the conductive member 50 becomes contaminants and infiltrates into the inside of the bearing through the pair of seals 10, 10 is reduced. However, in order to more reliably prevent contamination from entering the inside of the bearing, it is preferable to provide a through hole 15 for feeding air into the bearing space formed by the seals 10, 10 and the rolling element 8, as in the first embodiment. This makes it possible to more reliably prevent wear powder from entering the inside of the bearing.

Third Embodiment
This embodiment is an example in which the distance L from the side end face 70 of the inner ring 7 to the attachment position of the conductive member 50 to the inner circumferential surface 2 of the outer ring 4 is longer than in the second embodiment. As described above, the greater the distance L, the more sufficient a distance can be secured between the inner ring 7 or the seals 10, 10 and the end 51 of the conductive member 50 where wear powder may be generated, and the more reliably the wear powder can be prevented from entering the inside of the bearing.

In the second and third embodiments, the outer ring 4 is made axially wider and the conductive member 50 is attached, but it is also possible to make the inner ring 7 axially wider and attach the conductive member 50. Although not shown, in this case, the conductive member 50 is provided at the axial end of the inner ring 7, which is axially wider than the outer ring 4, on the side of the bearing end side of the seal 10, which does not face the outer ring 4. Therefore, the end 51 is away from the outer ring 4 and the seal 10, and there is a sufficient distance between the outer ring 4 and the seal 10 and the end 51 of the conductive member 50, where wear powder may be generated as the housing 30 rotates. In addition to the effect of increasing the internal pressure of the bearing space through the through hole 15, wear powder can be more reliably prevented from entering the inside of the bearing.

In the present invention, there is no restriction on the type of rolling bearing 1, and the rolling elements 8 can be other than the balls shown in the above embodiment, such as cylindrical bearings with rollers. The present invention also includes a bearing device that includes the above-mentioned various rolling bearings 1 and an air supply source for feeding air into the space through the through hole 15 of the rolling bearing 1.

1 Rolling bearing 2 Inner peripheral surface 3 Outer ring raceway surface 4 Outer ring 5 Outer peripheral surface (inner ring side)
6 Inner ring raceway surface 7 Inner ring 8 Rolling element 9 Cage 10 Seal 14 Outer circumferential surface (outer ring side)
15 Through hole 20 Shaft 21 Outer circumferential surface of shaft 30 Housing 31 Connecting portion 40 Side end surface 50 Conductive member 51 End portion

Claims (2)

an inner ring having an inner ring raceway surface on an outer circumferential surface;
an outer ring having an outer ring raceway on an inner circumferential surface;
a plurality of rolling elements held between the inner ring raceway surface and the outer ring raceway surface so as to be capable of rolling;
A pair of seals are provided to seal a gap between the inner ring and the outer ring,
A rolling bearing in which a lubricant is sealed in a space between the inner ring, the outer ring, and the seal, and the rolling bearing is assembled into a bearing device,
the axial width of the inner ring is greater than the axial width of the outer ring,
a conductive member extending from an axial end of the inner ring on a side not facing the outer ring to an inner circumferential surface of a housing of the bearing device that is electrically conductive between the inner ring and the outer ring, the conductive member electrically connecting the inner ring and the housing;
A rolling bearing characterized in that the outer ring is provided with a through hole for supplying air to the space. A rolling bearing according to claim 1 ;
an air supply source for supplying air into the space through the through hole;
A bearing device comprising:

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