192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
2000-01-27
2001-10-09
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C310S247000
Reexamination Certificate
active
06298967
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to an electromagnetic clutch suitable for use in a compressor of an automotive air conditioning system.
2. Description of Related Art:
JP-U-1-131028 and JP-U-2-54928 disclose an electromagnetic clutch in which an electromagnetic coil is provided in a rotor.
Applicants also filed a U.S. patent application Ser. No. 09/132,643 that discloses a coil rotating electromagnetic clutch suitable for use in a compressor of an automotive air conditioning system. In this patent application, slip-rings and brushes sliding with respect to the slip-rings are disposed in a space inside a cylindrical boss portion of the compressor housing, and an electric current is supplied to the electromagnetic coil through the slip-rings and the brushes.
However, in this coil rotating electromagnetic clutch, lubrication oil leaking out from a lip-seal sticks to a rotational shaft of the compressor. The oil flows axially frontwardly along the rotational shaft, and reaches the inside of the slip-rings and the brushes. Then, the oil splashes outwardly due to the centrifugal force of the rotational shaft, and sticks to slide surfaces between the slip-rings and the brushes.
When the oil sticks to the slide surfaces between the slip-rings and the brushes, abrasive material is deposited at the end of the brushes due to adhesion of the oil, thereby abnormally wearing the brushes.
This abnormal wear of the brushes reduces the life-span of the brushes, and increases the electric resistance at the slide surfaces, thereby decreasing electric conduction from the brushes to the slip-rings.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a rotating coil clutch in which abnormal wear of a brush caused by adhesion of lubrication oil is prevented.
According to a first aspect of the present invention, a slip-ring rotating with a rotor is attached in the rotor. A brush supplying electric current to the slip-ring is supported by a brush supporter fixed to a fixed member. The brush supporter includes a substantially cylindrical sleeve radially inside the brush, which extends axially outwardly farther than a slide surface between the slip-ring and the brush. That is, the cylindrical sleeve covers the inner side of the slide surface, and effectively prevents oil on a rotational shaft from splashing toward the slide surface due to centrifugal force.
As a result, abnormal wear of the brush caused by adhesion of the oil to the slide surface is prevented, and the electric resistance at the slide surface does not increase, thereby improving electric conduction thereat.
According to a second aspect of the present invention, the brush supporter is disposed between an inner periphery of a cylindrical boss portion axially protruding from a housing of a rotary machine and a rotational shaft of the rotary machine. As the slip-ring and the brush are disposed inside the boss potion, the entire coil rotating electromagnetic clutch is compact. Further, as the brush supporter is placed just outside the rotational shaft, the slip-ring and the brush are disposed near the rotational center of the clutch. Thus, the circumferential speed of the slide surface is small, thereby improving the life-span of the brush.
REFERENCES:
patent: 3718211 (1973-02-01), Schubert et al.
patent: 4190141 (1980-02-01), Bennett et al.
patent: 4337855 (1982-07-01), Bennett
patent: 6012563 (2000-01-01), Aoki et al.
patent: 57-22423 (1982-05-01), None
patent: 1-131028 (1989-09-01), None
patent: 2-54928 (1990-04-01), None
Aoki Yuuichi
Ohguchi Junichi
Sakamoto Hiroyasu
Bonck Rodney H.
Denso Corporation
Pillsbury & Winthrop LLP
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