Abstract:
A motor housing and brush holder device is constructed, as by molding, in such a manner as not to require any machining operations subsequent to its being molded and assembled, and it can be molded of either conductive or nonconductive materials. The housing, in this case, is of nonconductive high impact strength material and is a single preformed molded piece. The housing includes an integrally molded generally cylindrical stepped bearing recess or pocket for the end of an armature shaft and brush holders spaced axially and radially of the bearing recess. The shape of the bearing and its keeper is unique as well as the brushes and associated structures and the manner in which they supply power to the windings of the stator field coils.

Description:
BACKGROUND OF THE INVENTION 
     The invention is generally related to the art of small electric motors. Numerous types and variations of small electric motors have been constructed and include a fixed stator portion and a rotor or an armature portion which is provided with a contact surface such as a commutator and with brushes or the like for establishing electrical contact with the rotor. Brushes have been maintained in proper orientation in numerous different manners, and interconnections between brush leads and stator leads, in the case of wound stators, have been conducted in numerous ways. Connections between stator windings and brushes are conventionally made by (1) stripping the wire or lead ends and splicing them together, (2) crimping female quick-connect-disconnect terminals that cooperate with male contact members, and (3) screw-and-nut type interconnections. Brush holding structures have been constructed in various ways and typically include some type of mounting plate, through which a rotor shaft passes, made of an insulating material, and brush guide tubes, or boxes of conductive material. In recent years it has been proposed to mold end housing having brush holder structure from high temperature withstanding plastic material. The patents to MacFarland, U.S. Pat. No. 3,875,436; Spitler et al., U.S. Pat. No. 4,384,244; Horne, U.S. Pat. No. 4,342,929; Dieringer, U.S. Pat. No. 4,513,214; and O&#39;Hara et al., U.S. Pat. No. 4,491,752, are fairly typical of the most recent development in this area. Other prior art brush holders are also shown by Maher, U.S. Pat. No. 3,656,018; Preston, U.S. Pat. No. 3,784,856; Parzych, U.S. Pat. No. 4,074,162; and Niemels, U.S. Pat. No. 4,266,155. Bearing arrangements are shown in Sellers et al., U.S. Pat. No. 3,770,331; Cole, U.S. Pat. No. 4,074,158; and Langdon, U.S. Pat. No. 4,355,250. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to overcome the disadvantages of providing elongated wire leads connecting field coil terminals to brush connections and the associated labor expenses after assembly. Also, the present invention permits the automatic assembling of end housings of the motors whereby the field coil terminal and brush connection is automatically made as the housing is assembled with the remainder of the motor. The foregoing and other objects of the invention have been attained by providing a molded plastic combination motor end cap, housing or bracket, brush housings, and a bearing pocket for the commutator end (shaft) of the motor, hereinafter referred to as the &#34;front&#34; motor bracket or housing. It is also an object of the invention to provide a &#34;rear&#34; motor bracket supporting a bearing, a fan, and a fan cover of like plastic material. One major contribution to the art lies in the orientation of the brush connection contact terminal with the field coil terminals during assembly, thus eliminating wire leads and terminals of the customary arrangement when the &#34;front&#34; motor bracket is assembled with the remainder of the motor, and thus substantially reducing the expenses involved in this art field. 
    
    
     BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWING 
     FIG. 1 is a view of the interior of an end housing or cap of a conventional prior art assembly showing leads, brushes, and armature shaft supporting structure; 
     FIG. 2 is a perspective view of a small motor with the improved novel end housing or cap thereon; 
     FIG. 3 is a view of the interior of an end housing or cap similar to the prior art of FIG. 1 showing the improvement thereover; 
     FIG. 4 is an exploded perspective view of the novel brush holder, contact terminal, and the field coil terminal employed in the motor of FIG. 2; 
     FIG. 5 is a view similar to that of FIG. 4 showing a modification thereof; 
     FIGS. 6 and 7 are views detailing features of the novel armature shaft supporting spherical bearing arrangement; 
     FIG. 7A is a cross-sectional view of the bearing keeper shown in FIGS. 6 and 7; 
     FIGS. 8 and 9 are views similar to those of FIGS. 6 and 7 illustrating a ball bearing; 
     FIG. 10 is a view similar to FIG. 2 with the lower area removed showing a larger or heavy duty motor end cap or housing; 
     FIGS. 11 and 12 are similar to FIGS. 4 and 5 which show corresponding arrangements but of a larger or heavy-duty design. 
    
    
     DETAILED DESCRIPTION 
     As broadly illustrated in FIG. 2, the basic electric motor, insofar as this invention is concerned, includes a stator assembly SA with a conventional laminated stator stack LS carrying field coils FC, terminals T, an armature A, and a commutator C. Normally the armature has a shaft S, FIG. 6, which supports the commutator at an end thereof. The opposite end of the armature shaft projects beyond the armature and usually supports a conventional cooling fan and a power-take-off PTO asssembly. The ends of the shaft are also supported by bearings located in end units variously known as end housings, caps, brackets, etc., EU. The spaced housings etc. are normally fixed to the stator assembly and confine the stator and armature therebetween. 
     The several novel features of the present invention are concerned with features of an end housing, cap etc. on the commutator end of the motor which electrically connect brush leads to leads of the stator field coils. As previously pointed out, the present invention is an improvement over that illustrated in FIG. 1 which shows elongated leads L which must be attached to the brush assembly BA as well as the field coils of the stator either before or after the end cap has been assembled with the remainder of the motor. It should also be noted that connecting aperture CA is located below and in alignment with brush assembly BA; e. g., presenting a blind aperture CA, thereby requiring the connection pin, bolt, screw, etc. to be inserted from the bottom housing end unit EU through the stator assembly into the blind connecting aperture. Fabricating the lead, assembling the same to the brush and stator coil terminal and attaching the housings to the stator assembly require substantial manual effort which obviously does not lend itself to automatic or robotic assembly. 
     The present invention by its novel design lends itself to automatic assembly which eliminates all the above noted manual assembly and conserves substantial time, effort, and expense. As shown specifically in FIGS. 2 and 3, an end housing 1, which is of molded plastic construction and requires no machining, etc., has been designed to relocate brush holders 2 approximately 45°, as compared to the prior art shown in FIG. 1, in this case clockwise relative to stator engaging depending skirts SK, as shown in FIG. 2. In FIG. 3, a counterclockwise direction is shown since it is inverted as compared to FIG. 2. By relocating brush holders 2 relative to skirt SK, the elongated lead and its shortcomings relative thereto are eliminated. The elongated lead was necessary because the field coil terminal T was displaced or radially spaced from the brush holder BA, contact T, etc. By such relocation, the connecting apertures CA are out of alignment with brush holders 2 and such apertures can extend through skirts SK and thus define an arrangement whereby housing 1 can be assembled from the top via bolt B and nut N. This lends to automatic assembly of the housing 1 to the remainder of the motor. For example, the motor without housing 1 is conveyed to a work station with bolts B exposed, the housing 1 oriented with apertures CA aligned with bolts B is placed thereon, and nuts N are applied to complete the assembly. This new development of reorienting the brush holders 2 locates the same directly above the field coil terminal T, FIGS. 2 and 4. Each brush holder 2 is provided with an elongated cavity 3, a notch 4, a terminal retaining post 5, and terminal positioning shoulders 6, 6 as shown by FIGS. 2, 3, and 4. A commutator engaging brush 7 and conducting spring 8 are housed within cavity 3. In FIGS. 4 and 5, a contact terminal 10 for electrically connecting the commutator brush assembly to the stator coil terminal T is illustrated and includes a resilient, wavy or sine curve configuration end section 11, a midsection 12 having post gripping aperture 13 defined by resilient fingers or the like, a forward spring retaining end 14 having a brush spring confining tab 15, and a locking tab 16. The area between midsection 12 and the forward end 14 is a reduced area 17 adapted to be received in notch 4 of the brush holder 2 by first pressing post gripping fingered aperture 13 over the post 5 with a part of section 11 confined or located between spaced shoulders 6, 6, FIG. 4. Having attached conductive contact terminal 10 to the lower surface of holder 2, commutator brush 7 and conductive spring 8 are inserted into cavity 3. Retaining end 14 is then bent upwardly approximately 90° with reduced area 17 received in slot 4, and with spring retainer tab 15 engaging spring 8 and locking tab 16 pressed into cavity 3 and frictionally engaging the upper surface thereof. The end cap or housing is now ready to be assembled to the remainder of the motor. The structure as described above when assembled will automatically form an electrical connection between the armature&#39;s commutator and the stator&#39;s field coil terminal T as the resilient, wavy or sine curved portion 11 of contact terminal 10 is now in vertical alignment with terminal T and will be pressed thereagainst when the assembly is complete. The resilience of sine curve or wavy portion 11 of contact 10 maintains constant contact between same and terminal T. 
     A modification is illustrated in FIG. 5 for motors with varying spaces between brush housings and stator field coil terminals. All structural elements are the same as that described above except that a conductive coil spring 100 is provided to frictionally grip and extend beyond the upper end of the post of terminal T to engage the lower surface of contact terminal 10. 
     A further modification is illustrated in FIG. 5 for motors with varying spaces between brush housings and stator field coil terminals. All structural elements are the same as that described above except that a conductive coil spring 100 is provided to frictionally grip and extend beyond the upper end of the post of terminal T to engage the lower surface of contact terminal 10. 
     A further modification is illustrated in FIGS. 11 and 12 which also concerns the connecting of field coil terminals to brush connections without using elongated leads and terminals and specifically used in heavy-duty or larger motors. This connection is also automatically made during the assembly operation. As illustrated here, brush housing 200 has driven therein a tube 201 of brass or other conductive material providing a good tight friction fit, which tube provides a cavity for receiving a spring-biased commutator brush assembly 202. Tube 201 has a prong 203 at the rear thereof adapted to be bent downwardly to confine the brush assembly therein. The underside of housing 200 has an aperture 204 therein exposing an area of tube 201 to form a connection with a field coil terminal. A heavy conductive spring 205 is provided to make contact between tube 201 and the post of terminal T with the spring extending through aperture 204. As previously pointed out, as the end cap or housing is assembled with the remainder of the motor, the connection between the brush and field coil terminal is made as a result of such assembly, thereby eliminating the employment of the elongated lead, etc., and the necessary labor, expense, etc. connected therewith. 
     As noted above, another object of the invention is the provision of a unique bearing arrangement for the commutator end of the armature shaft. As illustrated in FIGS. 2, 3, and 6-9, a bearing pocket, cavity, recess, etc. BP is formed during the molding of the end housing, cap, or the like and requires no machining prior to the bearings being assembled therewith. In FIGS. 6 and 7 there is illustrated a spherical bearing arrangement which includes a bearing 30 having a shaft receiving aperture 31 and opposite, spherical, or convex ends 301 receivable respectively in corresponding concave-shaped sections of a keeper 32 and pocket BP. Concave surface 33 of keeper 32 receives and supports one end of bearing 30 while concave surface 34 of the bearing pocket receives and supports the other end when assembled. As shown in FIG. 7, lubrication slots 35 are provided in concave section 34 to permit lubrication to flow from relatively large cavity area 36 to shaft S through smaller cavity 37. The lubricant may be in the form of granules or liquid or any number of forms. The annular keeper 32 with its unique design or shape is a very critical part of the whole bearing assembly and includes the already mentioned concave area 33, a relatively sharp-edged locking lip 38, a slightly concaved surface 39 facing a direction opposite concave area 33, and a shaft receiving aperture 40. Surface 39, due to its location and shape, defines a spring or resilient section or area which allows keeper 33 to be pressed into the bearing pocket with the sharp edge of locking lip 38 digging into the inner circular or annular surface 41 of the bearing cavity. When assembled, FIG. 6, locking lip 38 also serves as a lubrication seal due to the fit between said lip and surface 41. Once the keeper is pressed into position, it is very difficult to remove since concave area 39 tends to expand lip 38 due to its tendency to straighten out or expand radially, thereby preventing any linear displacement. With this bearing arrangement there is no machining of the pocket or keeper. The pocket is formed during the molding process and the surfaces thereof are of such character as not to require machining or polishing thereof and the keeper is formed by a common punch-press or stamping operation. 
     The ball bearing assembly BB mentioned above is illustrated in FIGS. 8 and 9 and includes a fixed outer race 50, inner race 51 and ball bearings 52 therebetween. The bearing cavity or pocket BP encompasses outer race 50 of the ball bearing when the bearing assembly is pressed therein. A keeper 54 having a locking lip arrangement 55 and concave area 56, similar to that disclosed with respect to that illustrated in FIGS. 6 and 7 and described above, includes an annular projection or bead-like section 57 formed between the locking lip and a shaft receiving aperture 58 therein. This annular projection 57 engages the outer race 50 of the bearing and maintains same in position upon pressing the keeper 54 into position. Like the spherical bearing keeper, this ball bearing keeper digs into the concerned surface of the bearing cavity and forms a locking lip connection and a lubricating seal. 
     It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. Therefore, while the illustrated and described details preferred embodiments of this invention, it is of course understood that various other modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.