Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2000-07-26
2001-10-09
Footland, Lenard A. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
Reexamination Certificate
active
06299357
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a ball bearing for an electromagnetic clutch and pulley and for a driveshaft of a compressor for an automobile air conditioner. The bearing comprises an inner ring secured to a fixed shaft of the compressor, an outer ring integrally and rotatably secured to the pulley of the compressor, and balls therebetween, wherein the bearing is adapted to bear a radial load by the pulley, an axial load by the electromagnetic clutch disposed adjacent the pulley and a rotational moment load owing to an offset between the centers of load of the bearing and the pulley in an axial direction.
2. Description of the Related Art
A prior art double-row ball bearing for an electromagnetic clutch and pulley and for a driveshaft of a compressor for an automobile air conditioner is shown, for example, in FIG.
8
. The double-row ball bearing
80
has an one-piece inner ring
92
secured to a fixed shaft
86
protruded from a compressor housing
82
of the compressor
81
, an one-piece outer ring
93
secured to an inner surface
87
of a pulley hub
91
integrally and rotatably formed with the pulley
88
of the compressor
81
, and double-row balls therebetween. An electromagnetic coil windings
94
is secured to the compressor housing
82
and enclosed within the pulley hub
91
. The pulley hub
91
includes a radial portion having a friction clutch surface
90
situated directly adjacent a friction clutch engagement plate
85
having an armature
89
thereon. A compressor driveshaft
83
is connected drivably to the engagement plate
85
on its free end. When the electromagnetic coil windings
94
is energized, the armature
89
is attracted toward the coil windings
94
and the clutch engagement plate
85
is engaged with the friction clutch surface
90
, thus the electromagnetic clutch is engaged, and a rotational driving force by the pulley
88
is transmitted to the driveshaft
83
through the armature
89
and the engagement plate
85
. The driveshaft
83
rotates a rotor fixed to it and the compressor is operated.
By such an arrangement, the bearing
80
is adapted to bear a radial load by the pulley
88
loaded by belts not shown, an axial magnetic load by an electromagnetic clutch coil windings
94
when the coil windings
94
is energized. Usually, due to limited spaces for automobile engine auxiliary parts not shown, the centers of load of the bearing
80
and the pulley
88
are offset or discrepant in an axial direction. Such offsetting of the centers of load acts a rotational moment load againist the plane perpendicular to the axis of the bearing
80
to rotate the bearing
80
in an axial direction. This rotational moment load results a relative inclination between the axes of inner and outer rings
92
,
93
. Further, when this relative inclination become greater, an air gap G in an axial direction between the friction clutch surface
90
and the armature
89
is also enlarged, thereby results that an attractive force by the coil windings
94
is weakened. This further leads to fail an engagement between the friction clutch surface
90
and the armature
89
, or due to the weakened attractive force a relative slippage therebetween occurs, causing the rotational driving force by the pulley
88
is not transmitted to the driveshaft
83
, or causes to generate a heat between the friction clutch surface
90
and the armature
89
. On the other hand, when this air gap G is smaller, portions of the friction clutch surface
90
and the armature
89
are made always to contact causing a generation of heat or malfunctions.
It is required that a relative inclination between the axes of inner and outer rings of a compressor bearing must be less than 0.3 degree, when the bearing is loaded with a radial load by a pulley, an axial magnetic load by an electromagnetic clutch and a rotational moment load at the same time, further, number of revolution of the bearing is required to be high revolutions of about 10,000 rpm.
By these reasons, as a ball bearing for an electromagnetic clutch and pulley and for a driveshaft of a compressor for an air conditioner, conventionally, the double-row ball bearing
80
as shown in
FIG. 8
, or a pair of single-row deep-groove ball bearings as shown in U.S. Pat. No. 5,275,269 is used to keep a relative inclination between the axes of inner and outer rings small when the bearing is loaded with the radial, axial and rotational moment loads at the same time. However, since the double-row ball bearing
80
or a pair of single-row deep-groove ball bearings is expensive and requires much space in an axial direction.
The inventors of this invention know that a single-row three-point-contact ball bearing as disclosed in G. B. patent No. 1257658 or a single-row multi-point-contact ball bearing including a four-point-contact ball bearing is less expensive and requires a less space in an axial direction during to the relative displacement between its both rings is small when such bearing is loaded with the above radial, axial and rotational loads at the same time. However, the inventors do not know that any one of these bearings is used for a bearing for a compressor for an air conditioner which is affected by the above radial, axial and rotational loads at the same time under a required high revolutions of about 10,000 rpm.
SUMMARY OF THE INVENTION
The object of this invention is provide a single-row multi-point-contact ball bearing for an electromagnetic clutch and pulley and for a driveshaft of a compressor for an automobile air conditioner which bearing is adapted to bear a radial load by a pulley, an axial load by an electromagnetic clutch disposed adjacent the pulley and a rotational moment load during to an offset or discrepancy between the centers of load of the bearing and the pulley in an axial direction, in which the bearing has a low relative inclination between the axes of the inner and outer rings and rotatable at high revolutions of about 10,000 rpm, and yet inexpensive as well as requiring small axial space.
The inventors of this invention have discovered that a single-row four-point-contact ball bearing may be able to bear a radial load and an axial rotational moment load, however, when these loads are loaded at the same time, since each of bearing balls cause a revolution around the bearing axis and a rotation or spin on its axis which differs from the bearing axis, each of bearing balls has a significant slide or slip between its inner and outer rings. Further, the inventors have discovered that this slide or slip is able to minimize by minimizing the generation of this slide or slip against the radial load and the axial rotational moment load.
According to the first aspect of this invention, a single-row four-point contact angular ball bearing for an electromagnetic clutch and pulley and for a driveshaft of a compressor for an automobile air conditioner is provided which comprises an one-piece inner ring secured to a fixed shaft fixed to a compressor housing of the compressor, an one-piece outer ring secured to an inner surface of a pulley hub integrally and rotatably formed with the pulley of the compressor, and balls therebetween, and the bearing is adapted to bear a radial load by the pulley, an axial load by the electromagnetic clutch disposed adjacent the pulley and a rotational moment load arising out of an offset between the centers of load of the bearing and the pulley in an axial direction. Each raceway surface of the inner and outer rings, as seen in each sectional view thereof, is made to form a Gothic-arched configuration having two opposed curved surfaces symmetric with respect to a line passing through each center of the raceway grooves, and a line joining contact points of a ball and the raceway surfaces is inclined to a transverse plane perpendicular to the bearing axis by an angle ranging substantially 15° to 35°. Further, each radius of curvature of the two curved surfaces is made to range substantially 0.515 to 0.55 of the outer diameter of a ball, and each ce
Azuma Kazuo
Takata Takashi
Footland Lenard A.
Frank Robert J.
Kelemen Gabor J.
Nachi-Fujikoshi Corp.
Venable
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