Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2002-05-08
2004-06-29
Footland, Lenard A. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C384S476000, C384S488000
Reexamination Certificate
active
06755572
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a rolling bearing and, more particularly, a rolling bearing in which a current can be passed between the inner ring and the outer ring, that are rotated relatively.
BACKGROUND ART
Normally, in case the motor is driven by the sinusoidal wave of the commercial power supply, the electrolytic corrosion of the rolling bearing due to the charges that are generated in the rotating shaft of the rotor is not caused. Thus, it is the existing circumstances that no countermeasure for the electrolytic corrosion of the bearing is taken.
However, in the case that the motor is driven by using the inverter unit, the rotor is brought into the state that it is floated electrically over the stator, and thus the charges are generated in the rotating shaft by the harmonics and the electrostatic capacity. Then, the accumulated charges can be discharged only via the rolling bearing as the support point of the rotating shaft. Thus, the charges are discharged from inner ring of the rolling bearing to the outer ring via the rolling elements to electrolytically corrode the race surfaces.
For this reason, there is proposed the rolling bearing that can prevent the electrolytic corrosion by connecting the rotating shaft and the structural body such as the bracket, etc., that holds the rolling bearing, via the rolling bearing, that is made electrically conductive, such that the charges accumulated in the rotating shaft of the rotor are caused to escape to the structural body such as the bracket.
FIG. 5
is a sectional view of the rolling bearing in the prior art, that is set forth in the Unexamined Japanese Patent Application Publication No. Hei1-307516. In
FIG. 5
, in the rolling bearing
30
, the balls (rolling elements)
33
arranged between the inner ring
31
and the outer ring
32
are held by the holders
34
,
34
, and the sealing member
35
is spread between the inner ring and the outer ring in the situation that the lubricating grease containing the carbon black to have the conductivity is filled between the inner ring
31
and the outer ring
32
. Also, the raceway surface
31
a
of the inner ring
31
has a radius larger than the balls
33
, and the clearance
36
between the balls
33
and the raceway surface
31
a
of the inner ring
31
acts as the grease guiding means.
The lubricating grease containing the carbon black to have the conductivity is filled between a pair of races that guide the balls
33
held by the holders
34
, and such lubricating grease is sealed by the sealing member
35
, and the grease containing the carbon black is guided to the raceway surfaces of the races as it is by the grease guiding means
36
, so that the contact to the balls
33
with the conductivity can be accomplished.
In the above rolling bearing, there is the problem that, since the lubricating grease containing the carbon black to have the conductivity is employed, such grease is inferior in lubricity and life to the normal lubricating grease.
FIG. 6
is a sectional view of the rolling bearing in the prior art, that is set forth in the Unexamined Japanese Patent Application Publication No. Hei9-291943. In
FIG. 6
,
40
is the rolling bearing,
41
is the metal inner ring for rotatably supporting the rotating shaft (not shown),
42
is the rolling element such as the steel ball, etc.,
43
is the metal outer ring held to the structural body such as the bracket (not shown), etc.,
44
is the sealing member formed of the conductive flexible member that comes in contact with the inner ring
41
and the outer ring
43
to cover the rolling elements
42
from both ends away therefrom, and
45
is the lubricating grease for lubricating the rolling surfaces of the inner ring
41
and the outer ring
43
.
Since the inner ring
41
and the outer ring
43
are brought into contact with each other via the sealing member
44
formed of the conductive flexible member, the charges generated in the rotating shaft (not shown) are caused to escape from the inner ring
41
to the structural body such as the bracket (not shown), etc. via the sealing member
44
and the outer ring
43
.
In the above rolling bearing, since the sealing member
44
formed of the conductive flexible member is brought into contact with the inner ring
41
and the outer ring
43
by the spring force of the flexible member, there is the problem in aspects of wear and dustproof property.
The present invention is made to overcome above problems, and it is an object of the present invention is to get a rolling bearing having lubricity and life that are equivalent to those of the normal rolling bearing using the lubricating grease and having conductivity between an inner ring and an outer ring.
DISCLOSURE OF THE INVENTION
A rolling bearing of the present invention which has a metal inner ring for rotatably supporting a rotating shaft, a metal outer ring held in a structural body such as a bracket, and rolling elements arranged between the inner ring and the outer ring and in which a grease for lubricating rolling surfaces of the inner ring and the outer ring is sealed, the rolling bearing has a current passing sealing structure which comprises a first current passing plate fitted to an end portion of the inner ring, and a second current passing plate fitted to an end portion of the outer ring, and in which a conductive grease is sealed between the first current passing plate and the second current passing plate.
Also, the current passing sealing structure is constructed such that the second current passing plate is formed to have a U-shaped sectional shape whose opening portion is directed to an inner ring side, the first current passing plate is arranged on an inside of the U-shaped sectional shape, and the conductive grease is sealed in the inside of the U-shaped sectional shape.
Also, the current passing sealing structure is constructed such that the second current passing plate includes two current passing plates arranged on both sides of the first current passing plate, and the conductive grease is sealed in a space formed between two current passing plates.
Also, a rolling bearing which has a metal inner ring for rotatably supporting a rotating shaft, a metal outer ring held in a structural body such as a bracket, rolling elements arranged between the inner ring and the outer ring, a grease for lubricating rolling surfaces of the inner ring and the outer ring is sealed, and a sealing plate for sealing the grease, the rolling bearing has a current passing sealing structure which comprises a first current passing plate fitted to be put between an end portion of the inner ring and a contact surface of stepped portions of the rotating shaft, a second current passing plate fitted to the sealing plate to surround the first current passing plate by putting between the outer ring and an inside of the bracket, and a conductive grease sealed into a space between the second current passing plate and the sealing plate.
REFERENCES:
patent: 6109794 (2000-08-01), Bertetti et al.
patent: 1-307516 (1989-12-01), None
patent: 6-80956 (1994-11-01), None
patent: 7-127647 (1995-05-01), None
patent: 9-291943 (1997-11-01), None
Footland Lenard A.
Mitsubishi Denki & Kabushiki Kaisha
Sughrue & Mion, PLLC
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