Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-11-13
2001-12-25
Waks, Joseph (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S242000
Reexamination Certificate
active
06333580
ABSTRACT:
FIELD OF AND BACKGROUND OF THE INVENTION
The invention relates to a commutator motor with a retention device that retains a brush during assembly. Commutator motors of this type are provided, in particular, as drive motors for motor-driven pump units in automatic brake systems (ABS) in motor vehicles and must be protected from moisture.
In a motor-driven pump unit, especially for an ABS drive such as is known through EP 0 682 398 B1, for example, a vat-like motor housing is provided to seal the motor. The motor housing has an open side with an edge that rests axially against the pump housing. The vat-like motor housing is sealed on the apical side through a brush carrier plate in such a manner that the brushes, positioned on the brush carrier plate on the inner side of the motor, are not accessible upon assembly in the motor housing. During the assembly, the rotor and the commutator are mounted in the motor housing before the brush carrier plate is sealingly mounted.
A commutator motor with an axially flanged drive housing that is sealed against moisture is known from Laid Open German Application DE 42 35 962 C2. In this reference, a brush carrier plate with brushes that are displaceable against a commutator is disposed between the apical faces of a motor housing and a drive housing. The brush carrier plate simultaneously serves as a flat sealing element sealing against moisture between the apical faces of the motor housing and the drive housing.
Finally, U.S. Pat. No. 5, 444, 320 teaches an assembly procedure for a commutator motor in which brushes are initially held fixed in a retention position for the assembly by a sleeve encircling the commutator. Following assembly of the rotor, the brushes are released into their operational end position by axial displacing the sleeve.
OBJECTS OF THE INVENTION
According to one objective of the present invention, it is sought to provide a simple assembly both of a rotor-side commutator suitable for mass production, and of a stator-side brush carrier plate that is already assembled with brushes on its inaccessible, inner side facing the commutator. In addition, the assembly should ensure a moisture-proof seal that is, in particular, sufficient for protecting a commutator against the penetration of leaking fluids.
SUMMARY OF THE INVENTION
These and other objectives are achieved by the present invention by providing a commutator motor according to the invention, which not only provides moisture protection, but also includes a retention mechanism that retains the brushes facing the commutator during assembly.
According to one formulation, the invention provides a commutator motor including a brush holder, and a commutator having a brush contact surface, where the commutator and the brush holder have a mutual end position. The commutator motor also includes a plurality of brushes positioned in the brush holder, and a protective sleeve encircling the brush contact surface at a first radial distance. The protective sleeve includes a cover area having a plurality of plug-through openings for the plurality of brushes. The protective sleeve is axially movable from a retention position for assembly and an operational final position and secures the plurality of brushes in the retention position at a second radial distance from the brush contact surface during mutual axial assembly of the commutator and the brush holder. Upon the commutator reaching the mutual end position, the protective sleeve is axially moved to the operational final position and releases the plurality of brushes to extend through the plurality of plug-through openings to contact the brush contact surface.
Preferably, the present invention provides a protective sleeve encircling a brush contact surface of a commutator at a small radial distance. The protective sleeve protects the brush contact surface from moisture and leaking fluids that could otherwise encroach, even after the brush holder is closed. Due to the axial displaceability of the protective sleeve, the protective sleeve can be used to first secure the brushes in a non-obstructing retention position for assembly, thereby permitting the axial assembly of the rotor-side commutator and the brush holder onto one another. The protective sleeve can then be used to automatically release the brushes into their operational position to rest on the brush contact surface only once the components, namely the commutator with rotor, on the one hand, and the brush carrier plate with premounted brushes, on the other hand, are assembled together.
The present invention further achieves independent axial displacement of the protective sleeve from its retention position into its operational final position, while still allowing sizing to be compact. The invention further ensures operation free of grinding between the rotating commutator and the stationary encircling protective sleeve, despite the rotational tolerance inherent in mass production. These additional advantages are achieved by a second aspect of the present invention that provides a protective sleeve having a smaller radial distance from the brush contact surface of the commutator to the area retaining the brushes than to the area of the actual protective cover. Expediently, the protective sleeve is secured preferably, by means of scraping ribs, to be axially displaceable in the brush retention portion in a sliding press-fit connection. This permits easy axial displacement of the protective sleeve during assembly of the commutator to the brush holder and also ensures that the protective housing will be fixed in an operational end position that is secure against the vibrations associated with operation.
The axial displacement of the protective sleeve from its brush retaining position, wherein the brushes arc held in a retracted portion, into its operational end position, wherein the brushes are released, is performed in a particularly simple manner. Namely, the commutator axially displaces the protective sleeve by striking the free apical side of the protective sleeve, thereby causing axial entrainment of the protective sleeve as the result of the relative movement between the commutator and the brush holder during the assembly operation.
REFERENCES:
patent: 4293789 (1981-10-01), King
patent: 4694214 (1987-09-01), Stewart, Sr.
patent: 5004943 (1991-04-01), Gagneux
patent: 5006747 (1991-04-01), Stewart, Sr.
patent: 5296772 (1994-03-01), Bradfield et al.
patent: 5444320 (1995-08-01), Clarke et al.
patent: 5747911 (1998-05-01), Kikly
patent: 4 235 962 C2 (1994-05-01), None
patent: 0 682 398 A1 (1995-11-01), None
patent: 2 625 628 (1989-07-01), None
patent: 08-186957 (1996-07-01), None
Seuffert Werner
Steinbart Dagmar
Siemens Aktiengesellschaft
Sughrue & Mion, PLLC
Waks Joseph
LandOfFree
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