FIG. 2 is a cross-sectional end view of the same as
MOLDED RESIN MOTOR HOUSING sembly along line 2—2 of FIG. 1 also showing flange
portions in phantom line.
TECHNICAL FIELD FIG. 3 is a cross-sectional view of the assembly taken
... . A . « i . • , 5 along line 3—3 of FIG. 2.
My mvention relates to small electric motors having pfG 4 .g a , ^ vjew Qf ^
cup-shaped housings and, in particular, to direct current ... tQ a w^dshield wi drive casti
(DC) motors with permanent magnets and of the type FIG 5 is a simplified croSs-sectional view through an
used to power auxiliary systems in automobiles. injection mold for making the assembly.
BACKGROUND OF INVENTION 10 DETAILED DESCRIPTION
Small electric motors are used for many purposes in A windshield wiper motor housing assembly 10 is automobiles. For example, a fully equipped automobile illustrated in FIGS. 1 through 3 as a preferred embodiincludes individual motors for powering each wind- ment of my invention. The assembly 10 includes a cupshield wiper system, fan, and window lift system and 15 shaped housing 12 having an open end 14 and a closed three additional motors for powering each adjustable end 16. The housing 12 is molded of a resin material seat. Electric motors are also used as sunroof, mirror, such as AMODEL A-1565 HS NT from Amoco Perand antenna drives. formance Products, Inc. of Atlanta, Ga. The preferred
Ordinarily, these motors have metal housings that are resin is a sixty-five percent glass and mineral reinforced
formed from drawn steel cans. C-shaped permanent 20 polyphthalamide that exhibits high stiffness and good
magnets are attached to the sides of the can with adhe- dimensional stability at elevated temperatures,
sives, clips, or screws that are tapped into the magnets. An armature bearing 18 in the form of a thin sleeve
The steel body of the can functions as a flux ring sur- havin8 inner and «"« cylindrical surfaces 20 and 22 is
rounding the magnets. A self-centering bearing is molded m place withm the closed end 16 of the housing.
«„j „. „ „i„„„j J „f,i„ „„„ „„j „<• „„„„ 25 The armature bearing 18 is also preferably made of a
mounted at a closed end of the can. One end of an arma- ^ . , , °___T *,_„,. ,' ^
. f. . • , . . . , . resin material such as TORLON 4203L from the same ture shaft is journaled in the bearing, and the armature . „ _,, - , ^ . , ... u a. v ".-i* J -.i. .i. u ■ . i- . •.. manufacturer. The preferred resin material of the annashaft can be tilted with the bearing into alignment with „ , ... , -j • j .i_ . fi_-.fi.
, . , . , r 6 ture bearing 18 is a polyamide-imide that exhibits high
another bearing earned m a housing cover th Jd wear ^J^nce at elevated temperatures,
The drawn steel cans are expensive and add consider- 3Q ]ow ... and a w he_ meUi im than thfi fesin
able weight to the motors. The self-centenng beanngs material of the housing 12 t0 permit the armature bear,
also add cost and require additional clearance between ing t0 be molded in piace within the housing.
the armature and the permanent magnets to align the A flange M is molded at the open end 14 of the hous
armature shaft between the bearings. The additional mg for mounting the housing assembly 10 on a cover
clearance detracts from motor performance. 35 portion 26 of a wiper drive casting 28 shown in FIG. 4.
SUMMARY OF THE INVENTION Mounting holes 30 are formed through the flange 24 for
aligning the housing assembly 10 with similar mounting
My new electric motor housing assembly overcomes holes formed in the cover portion 26. Fasteners 32 in the problems with prior drawn steel housings by replacing form of screws or rivets extend through the mounting the steel housings with resin housings and feromagnetic 40 holes in the flange 24 and cover portion 26 for attaching flux rings. The resin material weighs much less than the the housing assembly 10 to the wiper drive casting 28. steel and can be more easily formed to a desired shape. Both the mounting holes 30 and the inner cylindrical The flux rings are also much easier to form. In addition, surface 20 of the armature bearing are molded within armature bearings and magnet mounts can be molded in the housing 12 in positions that are centered with redesired positions within the housing. 45 spect to a central axis 34. This eliminates the need for
One example of my motor housing assembly includes angularly adjusting the armature bearing into alignment
a cup-shaped housing that is injection molded from a w'tn tne central axis.
resin material. A flux ring is molded in place within a A steel flux rinS 38 als0 having inner and outer cylm"
center portion of the housing; an armature bearing is drical surfaces 40 and 42 is mounted in place within the
molded in place within a closed end of the housing; and 50 houslnS 12 Preferably, the flux nng 38 is molded in
alignment elements for mounting a housing cover are Plaf m * P0TM I ""^ ...
molded in place within an open end of the housing. surfa5f £ °? the flu,x ... f ^central
., . . ,, , , ■ .if 3X15 34. The inner cylmdncal surface 40 of the flux nng
Also, protrusions are molded through openings in the ., _r * 1 «•
flux n for h ldin erman nt ma nets in lace provides a mounting surface for locatmg a pair of per
ux nng or o mg permanen magne s in p ace J5 manent magnets 44 and 46 within the housing assembly
against the flux nng. 10. Since the inner cylindrical surfaces 20 and 40 of the
Inner cylmdncal surfaces of both the flux nng and beari and flux nng can be mounted mde
the armature beanng are centered wnhin the housing dent of any diametrai variations of their respective
with respect to alignment elements. This helps to re- outer cyiindncai surfaces 22 and 42, a gap between an
duce runout of a motor armature and assures a precise ^ armature coil (not shown) and the permanent magnets
positional relationship between the armature and the 44 and 46 can be reduced for improving motor perfor
magnets. Motor performance is improved by reducing mance.
an amount of clearance space between the armature and A slot 48 is formed through the periphery of the flux
the magnets. ring 38 to provide some mounting flexibiliy for molding
DRAWINGS ^5 t'le ^UX nn^ w'l^'n nousmS 12. A series of apertures
50 are also formed through the flux ring in positions
FIG. 1 is an perspective view of my new motor hous- diametrically opposed to the slot 48. Respective protru
ing assembly. sions 52 and 54 are molded through the slot 48 and the