Plastic Air Deflector for Rotating Dynamoelectric Machine

Rotating dynamoelectric machines, such as motors and generators (hereinafter motors), have a tendency to build heat up internally during operation. One of the many techniques used to reduce this heat build-up is the circulation of air within the housing or shell thereof and past the windings wherein the heat is generated. In some designs, the rotor carries a plurality of end blades, typically die cast, which propel the air much as a fan propels the air as it is turned. Also in the prior art, there are many designs for baffles, shrouds, and the like for directing the flow of air from a series of ventilating holes in the shell, past the blades, through the windings, and out the other end of the motor. Many different designs are utilized in the prior art in order to accommodate many different air paths as might be considered desirable by the designer. However, these baffles, deflectors and the like can be constructed of multiple pieces, some of which are rotating and others of which are stationary in order to maximize the effect of the rotating blades in drawing cooling air through the shell.

As motors are generally available from a wide variety of manufacturers, and these many different devices are sometimes considered to be functionally equivalent, the cost thereof can be a significant factor in the selection of one competitor's device over another's. Therefore, there has been significant attention paid to many of the various design details, including both motors and generators, over the years.

To solve the problems associated with multi-piece deflectors, including not only the required close manufacturing tolerances of those designs as well as the increased cost thereof in both the manufacture and installation thereof, the inventors herein have succeeded in designing and developing a one-piece, integrally formed, plastic air deflector which can be conveniently mounted to an end bracket of a motor by a mounting ring. The one-piece, integral, plastic construction of the deflector greatly reduces the cost not only of the piece part, but also minimizes installation cost as the deflector is mounted with four screws into an end bracket for the motor. In addition to a generally annularly shaped mounting ring, the deflector includes an axially displaced generally annularly shaped shroud with four webs extending between the inner circumference of the shroud and the outer circumference of the mounting ring. The deflector is oriented within the shell to be adjacent the holes therein through which cooling air passes.

As the webs occupy very little of the space between the shroud and the mounting ring, little interference or blockage of air flow is caused. Thus, cooling air readily flows through the ventilating holes, through the deflector by flowing past the stationary webs, and the air is then drawn into the central portion of the motor by rotating rotor blades which fit and rotate closely against the shroud portion of the deflector. The shroud not only fits closely against the rotor blades, but extends substantially to the inner circumference of the shell, with four notches therethrough for insertion of the thru-bolts which join the end brackets to the shell, as known in the art. This positioning of the shroud prevents re-circulation of the air around the blades which would interfere with the cooling action of the air as it circulates through the motor.

While the major advantages and features of the present invention have been described above, a more complete and thorough understanding of the invention may be attained by referring to the drawings and description of the preferred embodiment which follow.

FIG. 1 is a partial cross-sectional view of a motor incorporating a deflector of a typical prior art design;

FIG. 2 is a partial cross-sectional view of a motor with the deflector of the present invention installed;

FIG. 3 is a partial cross sectional view taken along the plane of Line 3--3 in FIG. 2 detailing the deflector installed in a motor;

FIG. 4 is an end view of the motor detailing the deflector mounting to the end bracket;

FIG. 5 is a partial cross-sectional view of the deflector taken along the plane of line 5--5 in FIG. 4;

FIG. 6 is a perspective of the deflector of the present invention; and

FIG. 7 is an enlarged partial perspective of a mounting hole in the mounting ring of the deflector.

A motor 20 is shown in FIG. 1 and includes therein a generally cylindrically shaped shell 22 which surrounds a stator 24 having stator windings 26 with a rotor 28 rotatably mounted inside stator 24 through a drive shaft 29 supported by an end bearing 30 in end bracket 32, all as well known in the art. The rotor 26 includes a plurality of axially extending, typically cast, fan blades 34 for drawing cooling air through the ventilating holes 36 in shell 22. The fan blades 34 may be a separate part, metal or plastic, assembled on a shaft.

A prior art deflector construction includes a steel shroud 38 which is typically peened over the die cast end ring comprising blades 34, or blades on the shaft mounted fan, such that it rotates with the rotor 26 as the motor 20 is operated, and a steel deflector 40 which is typically pressed into the shell 22. With this construction, the shroud member 38 must have close manufacturing tolerances in order to closely fit against but clear the inside circumference of the deflector 40. Furthermore, they must be axially located to prevent air from re-circulating through the minimal spacing between shroud 38 and deflector 40. As might be expected, there is difficulty, which increases the cost, not only in manufacturing the shroud 38 and deflector 40 to close manufacturing tolerances, but also in installing these parts within the shell 22. Still another problem in locating deflector 40 is that it must have holes therethrough so that thru-bolts 42 may conveniently slide therethrough and be secured to end bracket 32, as known in the art. Thus, the deflector 40 not only has to be axially located but also radially located when it is press fit into shell 22. As the shell 22 is typically painted prior to the installation of these parts, paint is typically undesirably peeled during this installation process.

The present invention provides a dramatic improvement over the prior art design and is shown in the remaining figures of the drawings. Its overall installation and construction is shown in FIG. 2 in the same motor design as depicted in FIG. 1. However, instead of the separate parts, a single, one-piece, integral, plastic deflector 44 is conveniently mounted by four screws 60 into the end bracket 32. As the mounting holes 48 are cored directly into the end bracket 32, the holes or notches 50 in the deflector 44 may be very accurately located and reliably lined up upon installation of the deflector 44 to the end bracket 32. Generally, the deflector 44 includes a shroud portion 52 which is aligned closely to the rotating edge of blades 34 and against the inside surface of shell 22 to prevent the re-circulation of air past the blades 34, around the shroud 52 and back through the blades 34. This prevents the over-heating of air and improves the operation and efficiency of blades 34 as they draw air through the ventilating holes 36, as previously described. Four webs 54 connect the shroud portion 52 with the mounting ring portion 56 wherein the mounting holes 58 are positioned through which screws 60 are inserted to mount the deflector 44 to end bracket 32.

A more detailed depiction of the construction of the deflector 44 is found in the remaining figures of the drawings. For example, as shown in FIG. 6, the shroud portion 52 is generally comprised of an annulus with an inner circumference having substantially the same radius as the outer circumference of mounting ring 56. Shroud 52 is generally co-axial with mounting ring 56. The four webs 54 which join shroud 52 and mounting ring 56 are generally arcuate shaped in cross-section and generally extend from the inner edge or circumference of shroud 52 to the outer edge or circumference of mounting ring 56. At each juncture between a web 54 and the mounting ring 56, a mounting hole 58 is located, as well as a pair of locating nibs 62 for locating deflector 44 on end bracket 32. Thus, deflector 44 may be very accurately located and conveniently installed to end bracket 32 prior to its assembly to shell 22 and attachment with thru-bolts 42 through notches 50. As the thru-bolts are attached to holes drilled and tapped in end bracket 32 itself, notches 50 are reliably positioned accurately by the simple mounting of deflector 44 to end bracket 32 to accommodate the ready insertion of thru-bolts 42.

With the deflector 44 of the present invention, a single, one-piece, integrally formed, plastic part may be pre-assembled to an end bracket 32 and conveniently installed as the end bracket 32 is installed to the motor 20.

There are various changes and modifications which may be made to the invention as would be apparent to those skilled in the art. However, these changes or modifications are included in the teaching of the disclosure, and it is intended that the invention be limited only by the scope of the claims appended hereto.