Bracket assembly having a plurality of plates for a dynamoelectric machine

A bracket assembly for a dynamoelectric machine includes a base plate and a bracket support assembly. The bracket support assembly includes a first end plate, a second end plate and a support member connected to at least one support plate. The bracket support assembly reinforces the bracket assembly and provides a configuration effectively achieving a desired natural frequency which is unlikely to be excited in use.

BACKGROUND OF THE INVENTION

This invention relates generally to dynamoelectric machines, and more particularly, to support brackets for bearing assemblies in dynamoelectric machines.

Dynamoelectric machines typically include a stator and a rotor positioned within a bore of the stator. In certain dynamoelectric machines, energization of the stator causes the rotor to rotate with respect to the stator. In other dynamoelectric machines, rotation of the rotor with respect to the stator causes an electric current to be generated. The rotor typically includes an extended rotor shaft rotatably mounted upon bearings. These bearings are generally mounted to a machine housing via bearing support brackets.

Bearing support brackets are subject to static and dynamic stresses from supporting the dynamoelectric machine rotor and associated components coupled to the rotor shaft. In use, a varying degree of vibration is experienced by the bearing support brackets due to varying loads and operating conditions. Typically, bearing support brackets are specifically designed for use with a particular dynamoelectric machine to avoid possible excitation of the brackets at their natural frequencies. These brackets, however, become excessively heavy and costly as the dynamoelectric machine size increases.

Accordingly, it would be desirable to provide a low cost bracket having a stiffness sufficient to avoid excitation thereof at selected undesirable frequencies.

BRIEF SUMMARY OF THE INVENTION

In an exemplary embodiment, a dynamoelectric machine includes a bearing support bracket assembly including a base plate and a bracket support assembly connected thereto. The bracket support assembly includes a curved support member contacting a first end plate and a second end plate. At least one support plate extends from the support member and contacts the first end plate and the second end plate. In addition, the bracket support assembly includes a side plate opposite the support member that extends between the base plate and the support plate. The support plate is separated from the base plate by a distance and contacts the support member, the end plates and the side plate.

Attachment of the bracket support assembly to the base plate reinforces the bearing support bracket assembly and provides a configuration effectively achieving the desired natural frequency which is unlikely to be excited in use.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1illustrates a known dynamoelectric machine10, the construction and operation of which is well known, and with which the present invention may be practiced. It is contemplated, however, that the present invention is equally applicable to other types of dynamoelectric machines, and the description of machine10is therefore provided for illustrative purposes only rather than by way of limitation. Machine10includes a frame12, a first bearing support bracket assembly14coupled to frame12at a first end16, and a second bearing support bracket assembly (not shown) coupled to frame12at a second end18.

Motor assembly10also includes a stator20and a rotor22. Rotor22includes a rotor core (not shown) and a rotor shaft24extending through the rotor core. Stator20is mounted in frame12and includes a bore (not shown) extending therethrough. Rotor22is rotatably mounted in frame12with the rotor core extending through the stator bore and rotor shaft24rotatably supported by a bearing assembly26. Bearing assembly26is supported by first bearing support bracket assembly14.

FIG. 2illustrates an exemplary frame30, such as for dynamoelectric machine10(shown in FIG.1), with which the invention may be practiced. A bearing support bracket assembly32is mounted, coupled, or otherwise attached to frame30and supports a bearing assembly34. Bearing assembly34includes a bore36which receives, and allows rotation of, a rotor shaft, such as rotor shaft24(shown in FIG.1). It is contemplated that the present invention may be practiced with a variety of bearing assemblies similar or dissimilar to bearing assembly34. Therefore, bearing assembly34is illustrated for exemplary purposes only and is not intended to limit the invention to any particular type of bearing assembly. It is further contemplated that other frames may be used to receive bearing support bracket assembly32within the scope of the present invention.

FIG. 3illustrates bracket assembly32including a base plate40having a bearing mounting surface42. Bracket assembly32also, includes a bracket support assembly44including a support member46, a first end plate48and a second end plate50. Support member46is a semi-annular ring extending between first end plate48and second end plate50. In an alternative embodiment, support member46is fabricated from a plurality of members to form a curved section that extends between first end plate48and second end plate50. End plates48and50extend substantially perpendicularly from a base plate outer surface52. In one embodiment, plates48and50are substantially flat and contact support member46.

In one embodiment, a first support plate54extends from first end plate48and support member46and is spaced a distance (not shown) from base plate40. A first intermediate end plate56and a first side plate58extend from base plate40to first support plate54. A first enclosure60is formed by base plate40, first support plate54, first end plate48, first intermediate end plate56and first side plate58. First enclosure60has a hollow space therein. A second support plate62extends from second end plate50and support member46and is spaced a distance (not shown) from base plate40. A second intermediate end plate64and a second side plate66extend from base plate40to second support plate62. A second enclosure68is formed by base plate40, second support plate62, second end plate50, second intermediate end plate64and second side plate66. Second enclosure68has a hollow space therein. Support member46defines an inner edge of first support plate54and second support plate62.

First support plate54and second support plate62are separated by a base plate intermediate region or arc segment70. Enclosures60and68reinforce bracket assembly32and provide a configuration effectively achieving the desired natural frequency which is unlikely to be excited in use. In one embodiment, first and second intermediate end plates56and64are substantially flat and extend substantially radially from support member46. In addition, first side plate58and second side plate66are substantially flat In alternative embodiments, plates48,50,56,58,64and66are not substantially flat.

A base plate intermediate region70is substantially centered, or positioned equidistant from first end plate48and second end plate50. In one embodiment, support plates54and62and base plate40are substantially planar and base plate40is substantially parallel to support plates54and62. In an alternative embodiment, a third support plate extends across base plate intermediate region70and forms a third enclosure. In a further alternative embodiment, a single support plate extends from first end plate48to second end plate50. In still further alternative embodiments, any number of support plates can be utilized to extend wholly or partially between first end plate48and second end plate50.

The stiffness of bracket assembly32is altered by altering the size of enclosures60and68. Bracket assembly32is stiffened by positioning support plates54and62further from base plate40. In addition, the stiffness of bracket assembly32is altered by altering the thickness of plates40,48,50,54,56,58,62,64and66and support member46.

Bracket assembly32is fabricated by connecting support member46, end plate48, intermediate end plate56, and side plate58to base plate40and support plate54by welding. Similarly, support member46, end plate50, intermediate end plate64, and side plate66are connected to base plate40and support plate62by welding. Alternatively, the connections are other than by welding.

In an alternative embodiment, bracket assembly32is fabricated by casting a single plate having a substantially flat portion and an incorporated stiffening portion. The plate is thinner at the bottom and becomes thicker towards the top. In one embodiment, the transition between the flat portion and the stiffening portion is gradual. In an alternative embodiment, the transition between the flat portion and the stiffening portion is substantially immediate.

While one exemplary embodiment has been described, it is contemplated that other shapes of bracket support assembly44and relative positioning of base intermediate region70are used in alternative embodiments while achieving the benefits of the present invention.

In practice, bracket assembly32is subject to static and dynamic stresses from supporting a dynamoelectric machine rotor structure and associated components coupled to the machine. A varying degree of vibration is experienced by bracket assembly32due to varying loads and operating conditions. Bracket support assembly44adds stiffness to bracket assembly32and reinforces bracket assembly32. Because of the reinforcement, bracket assembly32provides a configuration effectively achieving the desired natural frequency which is unlikely to be excited in use.