Ground wire attachment for a motor end-shield

An integral ground lug assembly for a dynamoelectric machine in the form of a motor is provided which permits quick attaching for a ground wire. The assembly includes a lug integrally formed with an end-shield of the motor. The lug extends radially from the end-shield and has both an axially extending bore and a radially extending bore which intersect one another. In addition, the lug may incorporate a transverse bore intersecting the axial bore. A clip is received in the axially extending bore and interacts with the bore to prevent movement of the clip relative to the bore. This maintains the clip in place during shipment and thereafter. A fastener extends through the radial bore to press the clip legs together to pinch or hold the ground wire in place. The clip operation within the lug may be varied so that ground wire attachment may be made from a number of directions, depending, for example, on the applicational use of the matter.

BACKGROUND OF THE INVENTION 
This invention relates to electric motors, and, in particular, to an 
improved manner of securing a ground wire to an end-shield of the motor. 
Although the invention is described with respect to electric motors, those 
skilled in the art will recognize the broader applicability of the 
invention described hereinafter. 
Dynamoelectric machines have been grounded in applications since antiquity. 
Until recently, it has been common to provide a terminal consisting of a 
strap, clamping hood, and screw which are attached to the motor by a 
threaded fastener. The grounding wire is attached to the strap with 
another threaded fastener which generally includes a grounding wire to 
ground the machine's circuitry. The grounding assembly thus includes four 
separate parts--the strap, clamping head, and two screws. During shipping, 
either of the two screws can come loose due to jostling of the machine. If 
the screw which holds the strap to the end-shield comes loose, the 
terminal will separate from the end-shield. If the hood screw loosens, the 
hood can separate from the strap. This creates difficulty for the one who 
installs the machine into a product because he must find the loose parts 
and reattach them. It is then desirable to provide a grounding assembly 
which cannot easily be separated from an end-shield. 
SUMMARY OF THE INVENTION 
One object of the present invention is to provide a motor having an 
improved manner of securing a ground wire to it. 
Another object is to provide such a motor wherein the ground wire 
attachment uses a minimum number of separable pieces. 
Another object is to provide a terminal and end-shield assembly for the 
motor in which the terminal cannot be easily removed from the end-shield 
by simple jostling of the motor, but which may be easily positioned with 
respect to the end-shield. 
Another object is to provide such an end-shield wherein the ground wire may 
be easily and securely attached to the motor. 
Another object of the invention is to provide a ground assembly which 
accepts a ground wire from a plurality of directions; 
Still another object of the invention is to provide a ground assembly which 
accepts a wide range of solid or stranded wire gauges in performing 
grounding functions. 
These and other objects will become apparent to those skilled in the art in 
light of the following disclosure and accompanying drawings. 
In accordance with the invention, generally stated, an improved manner of 
securing a ground wire to an electric motor is provided. Conventionally, 
the motor includes a casing or shell housing a stator and rotor assembly. 
A rotor shaft extends axially from the rotor and the casing is closed by 
at least one end-shield. The improvement comprises a lug formed in the 
end-shield of the motor. The lug has a bore formed in it which extends 
axially through the lug. A clip is received in the bore to hold the ground 
wire. The interaction of the clip with the lug prevents the clip from 
sliding out of the lug without the intervention of a person. 
The clip is generally hair-pin shaped and resilient. It has a front leg and 
a back leg joined by an arched section. The front leg includes an end 
portion extending away from the back leg. When the clip is received in the 
bore, the front leg end portion bears against a bottom surface of the lug 
to prevent movement of the clip with respect to the lug in one direction. 
The lug also includes an upper surface, spaced from the lug's bottom 
surface, which interacts with the clip's arched portion to prevent 
movement of the clip relative to the lug in a second direction. In one 
embodiment, the lug includes projections which extend inwardly from the 
wall of the bore. The arched section or web of the clip sits on this 
projection and is prevented from passing through the bore. The projection 
is preferably flush with the top of the lug, but can be spaced below the 
top of the lug. In another embodiment, the lug includes a surface offset 
or extending from the bore and which is spaced below the top surface of 
the lug. The clip includes wings or projections which extend outwardly 
from the clip's arched portion and sit on this surface to prevent the clip 
from passing through the bore. The mating of the clip wings and the lug 
projections orient the position of the clip so as to hold the clip in a 
restrained manner and to prevent rotation of the clip about a centerline 
parallel to the lug bore. In addition, the depth of the recesses above and 
below the lug projections insure proper installation and orientation of 
the clip. 
To secure the ground wire in the clip, the legs are urged together by a 
screw. The screw is received in the lug, through a radial bore which 
intersects the axial bore. To better hold the wire in place, the clip legs 
each include spaced apart pegs. The pegs of one leg are preferably offset 
from the pegs of the other leg. The pegs thus crimp the ground wire when 
the legs are brought together to secure the ground wire between the legs. 
The clip also includes a rib which extends down the center of the legs. 
The rib is positioned such that the screw bears against the rib. During 
shipping, the screw is set so that it slightly compresses the clip. The 
resilient nature of the clip will prevent rotational movement of the screw 
and the screw will thus not come loose from the lug. 
The ground wire may be received in the clip in a variety of fashions. It 
may be received through the bottom of the axial bore to extend up toward 
the clip arched section. The clip has a hole formed in its arched section 
and the ground wire may be passed through this hole. Lastly, the lug 
includes a transverse bore which communicates with the space between the 
clip legs. The wire may be placed through this transverse bore. No matter 
how the wire is passed to the area between the legs of the clip, the wire 
will be securely held in place by the clips pegs.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
A dynamoelectric machine 1 is shown in FIG. 1. Machine 1 includes a housing 
or shell 3 in which a rotor and stator assembly (not shown) are mounted. 
At least one end-shield 5 closes one end of the housing. A rotor shaft 7, 
which extends axially from the rotor, extends through the end-shield so 
that the output of the motor may be harnessed by a device such as a 
washing machine, dryer, fan, etc. 
In FIG. 1, end-shield 5 has a block or lug 9. Lug 9 can be formed 
integrally with the motor end-shield or physically attached to the 
end-shield. Although the lug is shown being formed with the end-shield, it 
could also be formed with the motor shell or casing, if desired. A ground 
wire 11 is secured to block 9 by a clip 41 to connect the dynamoelectric 
machine to a ground. As will be discussed below, block 9 and clip 41 can 
receive ground wire 11 either generally vertically, as shown in FIG. 1, or 
generally transversely, as shown in FIG. 2. In FIG. 3, lug 9 preferably 
extends radially outwardly from end-shield 5. Radially inwardly of lug 9 
and on a top surface of end-shield 5, a surface 13 is provided in which 
information or indicia 15 may be inscribed or cast. The lug 9 includes an 
axially extending bore 17 and a radially extending bore 19. 
A second embodiment 9' of the lug is shown in FIGS. 5, and 11-13. Lug 9' 
includes the axial and radial bores 17 and 19, as well as a transverse 
bore 20 (FIGS. 12 and 13). Transverse bore 20 is generally perpendicular 
to both the bore 19 and the bore 17. Bore 20 can formed by molding it into 
the lug or by drilling the hole in the lug. 
Bore 17, as shown in FIGS. 3 and 4, is generally rectangular. A pair of 
oppositely disposed ears 21 extend inwardly from the wall which defines 
bore 17. As shown in FIG. 5, bore 17' has a generally rectangular center 
portion 23 and a pair of winged recesses 25. A surface 27 is disposed in 
each wing 25 below the top surface of lug 9. 
A clip 41 (FIG. 9) is received in axial bore 17 (FIG. 12). Clip 41 is 
generally U-shaped and includes a back leg 43 and a front leg 45 joined by 
a web 47. Legs 43 and 45 are narrower than web 47, and the transition from 
the web to the legs define shoulders 44 and 46. Clip 41 is formed from a 
blank 49 (FIG. 6) from which clip 41 is stamped. After stamping, blank 49 
includes an unformed clip 41' which is joined to adjacent clips 51 by 
strips 53 which extend perpendicularly from web section 47. To form-clip 
41, stamped clip 41' is separated from adjacent clips 51 and bent about 
central portion 47 and a front portion 55 of front leg 45 is bent 
outwardly, away from back leg 43 and out of the plane of the front leg. 
(FIG. 9) Leg portion 55 preferably forms an angle of about 45.degree. with 
the rest of leg 45. Strips 53 may be retained or removed, depending on 
which bore formation is used. 
Clip 41 is resilient and flexible, as shown in phantom in FIG. 12. To 
insert clip 41 into axial bore 17, legs 43 and 45 are pinched together an 
amount sufficient to allow portion 55 to pass into and through bore 17. 
Once through bore 17, clip 41 springs back towards its relaxed position. 
In this position, front portion 55 extends outwardly from beneath lug 9. 
Front portion 55 thus creates a stop which interacts with the bottom 
surface of lug 9 to prevent clip 41 from sliding upwardly out of bore 17. 
Further, the ears 21 of FIGS. 3 and 4 interfere with web 47 and prevent 
clip 41 from slipping downwardly though, or rotating in, bore 17, as shown 
in FIGS. 12 and 13. In the embodiment of FIG. 5, the surfaces 27 provide 
stops on which clip shoulders 44 and 46 sit or abutt to prevent clip 41 
from slipping downwardly through, or rotating in, bore 17. Thus, the clip 
interacts with the bore to positively locate and retain the clip in bore 
17. 
Clip 41 includes a hole 57 in web 47 (FIG. 10). In blank 49, hole 57 is 
preferably elongate. When clip 41 is inserted in slot 17, hole 57 is 
exposed at the top of the lug 9. Ground wire 11 is passed through axial 
bore 17, or tansverse bore 20, between clip legs 43 and 45. A screw 59 
(FIG. 1) is screwed into radial bore 19 to press legs 43 and 45 together 
to pinch or hold wire 11 in place. The information or indicia 15 can 
include a ground symbol and the maximum torque which should be applied to 
the screw so that the assembler will not damage the clip or lug. 
Although wire 11 is shown passing upwardly into axial bore 17 in FIG. 1, it 
could be passed downwardly through bore 17 through clip hole 57, or 
transversly through bore 20 which is aligned with the area between the 
clip legs. (FIG. 2) 
A rib 61 is formed on the outer surface of legs 43 and 45. Rib 61 on leg 45 
is positioned so that screw 59 contacts rib 61. Rib 61 is provided to add 
strength to the legs so that the legs can better withstand the pressures 
applied by the screw to clip 41. Screw 59 thus cannot easily be passed 
through clip 41 to contact wire 11 where it could mar or cut the wire. 
To better hold the wire in place within clip 41, clip legs 43 and 45 are 
provided with projections 63 on an inner surface of the legs. Projections 
63 are defined by depressions 65 formed on the legs inner surface. The 
projections 63 are positioned to be generally aligned with the depressions 
65 (FIG. 9). Thus, the legs are brought together by screw 59, and the 
projections 63 and depressions 65 will be brought together. They will 
therefore provide a joggled crimp to wire 11 to positively hold the wire 
in clip 41. 
A groove 69 (FIG. 7) is also provided on the inner surface of the legs. 
Groove 69 is generally centered with respect to the legs and extends a 
substantial length of the legs. When the legs are brought together by the 
screw, the wire is forced toward the groove to center the wire with 
respect to the legs. This helps in better centering and retaining the wire 
in the clip 41 and substantially eliminating the possibility that the wire 
will slip out of the clip while tightening the screw 59. 
During shipping, the clip and bore 17 interact, as described above, to 
prevent the clip from falling out of the bore. The screw 59 is screwed 
into bore 19 a distance sufficient to slightly push leg 45 towards leg 43. 
The spring quality or resiliency of the clip will then act against the 
screw to prevent the screw from turning in bore 19. The screw will thus 
not loosen and fall out of hole 19 during shipping. 
As can be appreciated from the foregoing, the novel lug and clip 
arrangement described above provides a ground clip which is easily applied 
to a ground lug and will not slip out of the ground lug during shipping. 
The assembly, as can be seen, also reduces the parts to a minimum number 
of separable parts required to hold the ground wire in place. The 
arrangement can accept a plurality of sizes of wire and can accommodate 
solid or stranded wire and the wire can be oriented either axially or 
transversly to the clip. 
The above description is set forth for illustrative purposes only. 
Variations within the scope of the appended claims may be apparent to 
those skilled in the art. For example, the shape of bores 17 and 20 may be 
varied in shape and may be formed by machining, casting, or molding 
processes. Hole 57 in clip 41 could be omitted. The lug could be 
positioned elsewhere on the motor or end-shield, for example on the motor 
housing or within the end-shield itself. The lug need not extend radially 
outwardly of the motor assembly. These examples are merely illustrative.