192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
1999-12-23
2001-08-14
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C192S11000B, C384S540000, C384S516000
Reexamination Certificate
active
06273230
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetic clutch which transmits and cuts off power to a compressor employed in a freezing cycle of a vehicle such as a car or the like, and also a ball bearing for applicable in the above electromagnetic clutch.
In a vehicle such as a car or the like, there is employed an electromagnetic clutch which is used to transmit or cut off rotation drive force generated by a running engine to a compressor provided in a freezing cycle such as an air conditioner (an air conditioning system) or the like.
The electromagnetic clutch comprises a rotary body made of metal used as magnetic material such as iron or the like, a body to be rotated made of metal used as magnetic material such as iron or the like, an electromagnetic coil, a bearing for supporting the rotary body in a freely rotatable manner, and the like; and, the electromagnetic clutch allows the rotary body and the to-be rotated body to attract each other due to the attracting force of an electromagnetic coil, thereby being able to carry out the above-mentioned transmission and cut-off of the rotation drive force.
Japanese Patent Unexamined Publication No. Hei. 8-114241 discloses the rotary body of the above-mentioned electromagnetic clutch. The rotary body is supported by a double row ball bearing in which a plurality of balls are arranged along the axis of the ball bearing serving as a center of rotation. This raises a tendency that the width of the double row ball bearing along the axial direction thereof becomes large and thus the electromagnetic clutch itself becomes large in size. As a result of this, the weight of the electromagnetic clutch is caused to increase, thereby increases the manufacturing cost of the electromagnetic clutch.
Also, in the case when, to support the rotary body in a freely rotatable manner, there is used a single row ball bearing in which a single ball is arranged along the axis of the ball bearing, since the sections of grooves formed in the outer and inner races of the single row ball bearing are each formed in a single arc shape, there arises a tendency that a relative shift (which is hereinafter referred to as an axial shift) between the inner and outer races along the axis of the ball bearing becomes large. In general, with limit of elements such as a voltage capable of generating the attracting force of the electromagnetic clutch and the like taken into account, a clearance between the rotary body and the to-be rotated body of the electromagnetic clutch, preferably, may be relatively small, for example, about 0.5 mm.
Further, if the conventional single row ball bearing is used to support the rotary body of the electromagnetic clutch, because the axial shift of this single row ball bearing is large, even when the electromagnetic coil does not generate an attracting force, there is a possibility that the rotary body and the to-be rotated body can be contacted with each other, so that there is a fear that the rotary body and the to-be rotated body can be damaged due to such mutual contact.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to solve the above-mentioned conventional problem. It is an object of a first aspect of the present invention to provide a ball bearing which is able to restrict the relative shift between the inner and outer races thereof along the axis of the ball bearing. In addition, it is also an object of a second aspect of the present invention to provide an electromagnetic clutch having the same, which can prevent a rotary body and a to-be rotated body from contacting each other.
In attaining the above-object, according to a first aspect of the present invention, there is provided a ball bearing comprising an outer race, an inner race, and a ball rollably interposed between the outer and inner races, each of the outer and inner races including a groove having an arc-shaped section formed in the contact surfaces thereof with respect to the ball so as to extend in the peripheral direction thereof, wherein the radius of curvature re of the groove of the outer race and the radius of curvature ri of the groove of the inner race each satisfies at least one of three equations below,
1.0≦(re+ri)/Da≦0.9746(Da/dm)
−0.0304
, (1)
1.0≦(re+ri)/Da≦0.976(Da/dm)
−0.0255
, (2)
and
1.0≦(re+ri)/Da≦0.9638(Da/dm)
−0.0315
, (3)
where Da: the diameter of the ball, and dm: the mean value of the diameters of the grooves of the inner and outer races.
With a ball bearing according to the present invention, the axial shift of the ball bearing can be restricted.
Moreover, the above-mentioned object can also be achieved by an electromagnetic clutch which comprises: a rotary body, a to-be rotated body, an electromagnetic coil, and a ball bearing. The rotary body is made of metal serving as magnetic material, can be driven or rotated by a drive source and includes a friction surface. The to-be rotated body is made of metal serving as magnetic material and includes a to-be rubbed surface disposed opposed to the friction surface of the rotary body. The electromagnetic coil is that when energized, generates a magnetic force to attract at least one of the rotary body and the to-be rotated body, thereby allowing the friction surface of the rotary body and the to-be rubbed surface of the to-be rotated body to attract each other. The ball bearing supports the rotary body in such a manner that the rotary body is free to rotate.
In the above-mentioned electromagnetic clutch according to the present invention, it is preferable that the ball bearing comprising an outer race, an inner race, and a ball rollably interposed between the outer and inner races, each of the outer and inner races including a groove having an arc-shaped section formed in the contact surfaces thereof with respect to the ball so as to extend in the peripheral direction thereof, wherein the radius of curvature re of the groove of the outer race and the radius of curvature ri of the groove of the inner race each satisfies at least one of three equations below,
1.0≦(re+ri)/Da≦0.9746(Da/dm)
−0.0304
, (1)
1.0≦(re+ri)/Da≦0.976(Da/dm)
−0.0255
, (2)
and
1.0≦(re+ri) /Da≦0.9638 (Da/dm)
−0.0315
, (3)
where Da: the diameter of the ball, and dm: the mean value of the diameters of the grooves of the inner and outer races.
With the electromagnetic clutch according to the present invention, since there is used the ball bearing in order to support the rotary body in a ratable manner, the width of the electromagnetic clutch along the axial direction of the ball bearing can be restricted.
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Hochleistungskeramik in FAG Wälzlagern: Erkennmisse aus der Entwicklungstätigkeit, Pub. No. WL 40 204 DA, p. 2, FAG Kugelfischer Georg Schäfer KGaA, Apr. 1991.
Aramaki Hirotoshi
Ishiguro Hiroshi
Nakano Yuji
Lorence Richard M.
NSK Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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