Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1997-09-30
1999-11-02
Ramirez, Nestor
Electrical generator or motor structure
Dynamoelectric
Rotary
310 42, 310247, H01R 3938, H01R 3940, H02K 1500
Patent
active
059776838
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a brush holder plate, attached to which are casings accommodating brushes, the brushes extending under spring load in a radial direction towards a central aperture in the brush holder plate. Further, a retaining ring is provided on whose external periphery the brushes abut, the retaining ring being slidable in an axial direction.
The retaining ring serves to facilitate the assembly. Initially, the retaining ring keeps the brushes in retracted positions. As soon as the brush holder plate is slipped on the armature shaft of the motor and the collector secured to it, the collector gradually displaces the retaining ring from its position. As a result of that, the brushes slide from the external periphery of the retaining ring towards the periphery of the collector. This permits an easy and rapid assembly.
German patent application No. 41 05 349 discloses such an arrangement, for example. The holder or prop ring described in the application has a rigid design. During the assembly, the holder is slid by the collector into an accommodating chamber provided in a support of the electric motor housing.
Because it is impossible to conform the outside diameter of the retaining ring exactly to the inside diameter of the accommodating chamber, the retaining ring is likely to have a certain clearance in relation to the accommodating chamber. This means that rattling noise cannot be prevented. Also, wear is caused by the movement of the retaining ring relative to the housing which possibly limits the operability of the electric motor.
SUMMARY OF THE INVENTION
To avoid these shortcomings, it is proposed that the retaining ring of the brush holder plate has a radially resilient design.
The associated electric motor includes an accommodating chamber having a diameter which is smaller than the diameter of the retaining ring in the absence of counteracting load. The result is that the retaining ring, when it is slipped into the accommodating chamber during the assembly, is expanded due to its resilient design and moves into yielding abutment on the walls of the accommodating chamber.
The friction forces between the wall of the accommodating chamber and the outside periphery of the retaining ring, which are caused by the spring forces, prevent movement of the retaining ring. Thus, the retaining ring is frictionally locked in the accommodating chamber.
To generate the radial spring effect of the ring, the ring is made of an elastic material. Further, a slot is provided so that the retaining ring is open in one point and may be expanded in the absence of counteracting forces.
To reliably fix the ring in position on the casings during preassembly, the ring may include a circumferential edge to extend radially outwardly and abut on the bottom side of the casings in the preassembly position.
The support (the accommodating chamber of which houses the retaining ring after the assembly) may be part of a pump housing or transmission housing.
The brush holder plate is secured directly to the support or is integrally designed with the support, and the accommodating chamber of the support is arranged coaxially to the aperture in the brush holder plate.
One embodiment will be explained in detail hereinbelow, making reference to three Figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2 show views of a brush holder plate, i.e.
FIG. 1 is a cross-sectional view and
FIG. 2 is a top view of the brush holder plate.
FIG. 3 is a cross-sectional view of an electric motor after the assembly and the resulting new position of the retaining ring.
DETAILED DESCRIPTION OF THE INVENTION
Initially, FIGS. 1 and 2 will be referred to. Reference numeral 1 designates the holder plate (brush holder plate) in total. The brush holder plate has a generally circle-ring shaped design, i.e., its outer edge is conformed to the contour of the housing of the electric motor. Aperture 2 in the brush holder plate is of circular design and has a diameter which mainly corresponds to the diameter of the
REFERENCES:
patent: 4293789 (1981-10-01), King
patent: 4516047 (1985-05-01), Duverger
patent: 5006747 (1991-04-01), Stewart et al.
patent: 5089735 (1992-02-01), Sawaguchi et al.
Search Report of the German Patent Office for Application P4430954.6.
Merriam Webster's Collegiate Dictionary, Tenth edition, Merriam-Webster, Inc., p. 383, 1997.
Buhl Harro
Huber Walter
Scheele Hubert
Dinh Le Dang
ITT Manufacturing Enterprises Inc.
Lewis J. Gordon
Ramirez Nestor
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