Plastic air deflector for rotating dynamoelectric machine

A one-piece, plastic, integrally formed deflector for a motor includes a generally annularly shaped shroud portion, an axially offset generally annularly shaped mounting ring portion, and four generally axially extending webs interconnecting them. The deflector may be conveniently mounted to an end bracket with a screw placed through a mounting hole in the mounting ring located at each web such that as the end bracket is assembled to the motor, the shroud portion closely fits nearly adjacent the rotating rotor blades and the inside of the motor shell to restrict the flow of ventilating air through the motor and prevent its re-circulation past the blades.

BACKGROUND AND SUMMARY OF THE INVENTION 
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.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
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.