Hold structure for bearing in electrical motor

Details Hold structure for bearing in electrical motor Hold structure for bearing in electrical motor

1990-05-21

1992-11-24

Stephan, Steven L.

Electrical generator or motor structure

Dynamoelectric

Rotary

310 42, 384537, H02K 516, F16C 35077

Patent

active

051665654

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a hold structure for a bearing in a general-purpose electrical motor having a small size and a large output power, and able to rotate at a high speed.


BACKGROUND ART

In general, an output shaft of an electrical motor is journaled by bearings housed in a housing of the motor at the front and the rear thereof, and when the motor is applied as a drive source to an industrial machine such as a machine tool, a radial load and a thrust load are imposed on the output shaft thereof. Usually, the housing is formed by aluminum castings, and the front and the rear inner surfaces of this housing are often damaged, due to a direct pressure exerted thereon by the bearings. Therefore, a layer containing iron as a main component thereof, which is hard and thus is not easily damaged, is provided at the inner portion of the housing receiving such a pressure, to enable a hold structure for a bearing to withstand a radial load.
Nevertheless, an outside end face of either bearing is held by a member such as a C-shape ring when the bearings are incorporated in the housing, to retain the bearing so that it cannot move in the longitudinal direction of the motor. For this purpose, a groove is provided in the layer so that the member is retained in the inner portion of the housing, i.e., in the layer. The groove receives a thrust load acting on the output shaft through the bearings and the member, and therefore, is made of a ductile material containing iron as a main component thereof, such as FCD (Nodular Graphite Cast Iron) according to the JIS (Japanese Industrial Standard), to prevent damage.
On the other hand, after a central housing integrated with a stator is combined with a front or rear housing provided with the above-mentioned layer containing iron as a main component thereof at the inner portion thereof, an inner surface of the layer of a ductile material, which holds an outer ring of the bearing, is finish-machined to enhance the retain accuracy of the bearing, and a burr is often generated at the end point of the layer when machined, because the layer to be machined is made of a ductile material. When the burr is removed, a problem arises in that it sometimes drops into a stator coil winding, or that it prevents the incorporation of the bearings and a rotor.


DISCLOSURE OF THE INVENTION

Therefore, an object of the present invention is to solve these problems by providing a hold structure for a bearing which prevents the generation of a burr when the portion for holding a bearing is machined.
In view of the above object, the present invention provides a hold structure for a bearing in an electrical motor having a front bearing and a rear bearing journaled on an output shaft, characterized in that an inner portion of a housing for holding an outer ring of one of the front and rear bearings is covered with a layer of a material containing iron as a main component thereof, a longitudinal inside end face of the layer is in tight contact with an end-hold member integrated with the housing, and each inner surface of the layer and the end-hold member is formed with the same diameter.
The housing of an electrical motor is, in general, made of a free-cutting material such as an aluminum casting, and therefore, by adopting a structure wherein the longitudinal inside end face of the layer is in tight contact with the end-hold member constructed as a part of the housing, a burr is not generated at a point of the end face of the layer when the end-hold member as well as the layer is machined.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of an electrical motor having a hold structure for a bearing according to the present invention;
FIG. 2 is an enlarged sectional view of a bearing and the holding portion in FIG. 1;
FIG. 3 is a partially enlarged cross-sectional view of a front housing before finish-machining, taken along a line III--III of FIG. 1; and
FIG. 4 is a plan view of a C-shaped ring.


BEST MODE OF CARRYING OUT THE INVENTION

The present

REFERENCES:
patent: 3757147 (1973-09-01), Lyman, Jr.
patent: 4048530 (1977-09-01), Kaufman, Jr.
patent: 4944611 (1990-07-01), Ankenbauer et al.
patent: 4980587 (1990-12-01), Yonei et al.

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