Electric motor with shaft bearing having alignment feature

An electric motor that includes a case having an axially oriented stamped steel endhead, a motor output shaft projecting from the endhead for coupling to a motor load, and a self-aligning spherical bearing mounted on the endhead for rotatably supporting the shaft. The bearing has a cylindrical extension that projects axially outwardly from the motor case coaxially with the shaft. The bearing extension is constructed and arranged to be engaged by the support structure and/or load coupled to the shaft for locating the same coaxially with the shaft. The bearing, including the extension, is of homogeneously integral unitary construction, preferably of lubricant-impregnated porous metal.

The present invention is directed to electric motors with shaft bearings, 
and more particularly to an improved bearing construction in such an 
electric motor for facilitating alignment of the motor shaft with the 
surrounding support structure and/or load. 
BACKGROUND AND SUMMARY OF THE INVENTION 
In many applications it is desirable or even critical that the output shaft 
of an electric motor be accurately aligned coaxially with the support 
structure and/or load engaged by the motor. In such applications it has 
been the practice to machine or otherwise form a rabbit on the endhead 
casting of the electric motor case coaxially with the shaft that protrudes 
through the endhead. For enhanced accuracy where such alignment is 
critical, it has been conventional practice first to assemble the motor, 
and then to machine the rabbit while locating off of the motor output 
shaft. Such operations, requiring complex and accurate machining fixtures, 
are time consuming and expensive. 
A general object of the present invention is to provide an electric motor 
construction having facility for accurate location of a support structure 
or load coaxially with the motor output shaft that is easy and inexpensive 
to manufacture. A more specific object of the invention is to provide a 
motor construction of the described character that eliminates the 
necessity in the prior art for machining the endhead casting, and in which 
the endhead member may therefore be of less expensive stamped steel 
construction. 
An electric motor in accordance with a presently preferred embodiment of 
the invention includes a case having an axially oriented end member or 
head, a motor output shaft projecting from the end member for coupling to 
a motor load, and a bearing mounted on the end member for rotatably 
supporting the shaft. The bearing has a shoulder or extension that extends 
axially outwardly from the motor case coaxially with the shaft. The 
bearing extension is constructed and arranged to be engaged by the support 
structure and/or load coupled to the shaft for locating the same coaxially 
with the shaft. The bearing, including the extension, is preferably of 
homogeneously integral unitary construction, such as of 
lubricant-impregnated porous metal. The bearing is of sleeve-type or, more 
preferably, self-aligning spherical construction. The end member may be of 
cast or, more preferably, stamped steel construction. The bearing 
extension has a radially outwardly facing surface engagable by the load 
and/or motor support structure. This surface preferably is cylindrical, 
but could also be square or other shape in suitable applications.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
FIG. 1 illustrates a submersible pump 10 that includes an electric motor 12 
in accordance with the present invention mounted within a seal housing 14. 
Seal housing 14 is mounted on a septum 16 within a pump housing 18. 
Electric motor 12 has a substantially cylindrical case 20 with an axially 
oriented end head 22 at one end thereof. A motor output shaft 24 extends 
axially through endhead 22, through a pair of lip seals 26 carried by seal 
housing 14, and is coupled to a pump impeller 28. Within motor 12 there 
are disposed the usual electric motor stator windings that receive 
electric power through the conductors 30, and a rotor coupled to shaft 24. 
The internal stator/rotor construction of motor 18 may be any suitable 
Character, and does not form part of the present invention. 
Referring to FIGS. 1-3, endhead 22 comprises a subassembly that includes a 
stamped steel end plate 32 suitably fastened at its periphery to motor 
case 20. A spherical bearing 34 is mounted to plate 32 by a bearing 
retainer 36 that is welded or otherwise suitably secured to the end plate. 
A snap ring 37 encircles shaft 24 externally of bearing 34. Bearing 34 
preferably comprises an oil-impregnated porous metal bearing of sintered 
brass or other suitable metallic construction. Bearing 34 has an internal 
cylindrical bore 38 for rotatably supporting motor shaft 24, and an 
external spherical surface 40 for self-aligning engagement with bearing 
retainer 36. To the extent thus far described, pump 10, motor 12 and 
endhead 22 are of generally conventional construction. 
In accordance with the present invention, a shoulder or extension 42 
projects axially outwardly from the body of bearing 34 externally of 
endhead 22 and motor 12. Extension 42 is of homogeneously integral unitary 
construction with the remainder of bearing 34, and has a radially 
outwardly oriented surface 44 coaxial with bearing bore 38, and therefore 
coaxial in assembly with motor output shaft 24. Extension surface 44 
preferably is cylindrical, but could be square or other suitable geometry 
in appropriate applications. 
Seal housing 14 has a substantially cylindrical case with an opening 46 in 
the case end wall 48. A molded plastic seat 50 is secured to end wall 48 
within opening 46. Lip seals 26 are mounted within seat 50 surrounding 
shaft 24. Seat 50 has a neck 52 that engages and locates on surface 44 of 
bearing extension 42 so that motor 12 and motor shaft 24 are accurately 
located coaxially with seat 50 and lip seals 26. Thus, neck 52 molded 
integrally with seat 50, and extension 42 formed integrally with bearing 
34 cooperate with each other accurately to locate the axis of motor shaft 
24 without requiring either a heavy and expensive endhead casting or extra 
machining operations thereon. A circumferential array of locking clips 54 
extend from seat 50 and are received in corresponding apertures 56 on 
endhead 22 for fastening motor 12 in position.