Note: Descriptions are shown in the official language in which they were submitted.
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ELECTRICALLY OPERATED REMOTE CONTROL REARVIEW MIRROR
BACKGROUND AND SUMMARY OF INVENTION
The present invention relates to drive systems for adjusting the
position of a remotely controlled electically operated automotive rearview
mirror.
It is known in the prior art to adjust the position of an outside
rearview mirror by means of electrically driven rotatable nuts which cause
longitudinal non-rotary movement of two screws which engage the mirror
bQcking plate to cause it to pivot about each of two mutually perpendicular axes.
The rotatable nuts may be driven by either a single motor-driven worm gear
which selectively pivots into engagement with one or the other of the nuts or by
two ~sets of motors and worm gears.
Representative of such prior art patents are U.S. patent numbers
3,972,597, 4~041,7~3, 4,273,417 and 4,324,454.
It is also known to provide an override feature by which the
motor is permitted to continue to run after the mirror has reached the limit of
its movement, or, conversely, to permit the mirror to be manually shifted when
the motor is not operating. Such override feature has been achieved, for
examp1e, by use of a split nut which permits the nut to rotate without causing
longitudinal movement of the screw or permits the screw to move longitudinally
without rotation of the nut. The segments of the split nut are resiliently biased
in a radially inw~rd direction to normally maintain a driving engagement with the
threads of the screw. However, in an overload condition, the nut segments
resiliently yiel~ radially outwardly to disengage the driving relationship between
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the screw and nut threads. Exemplary of such a split nut is the drive system
found in the aforementioned U.S. patent 4,041,793.
The present invention is directed to the creation of an alternative
~nd improvecl overricle construction and to the provision of a screw and nut drive
system which operates smoothly and uniformly irrespective of the angle of the
mirror and the degree of travel of the mirror slong its arc of pivotal movement.
The foregoing objects have been accomplished by the use of a
three-piece assembly comprising a worm gear-driven pinion gear having a
spherical socket which receives a ball-shaped drive nut splined for co-axial
rotation with the pinion gear, and internally threaded to receive a screw member
having radi~lly inwardly and resiliently yieldable male thread segments. The
ball-socket relationship of the pinion gear and nut permit the axis of the nut, and
therefore the axis of the screw, to pivot or skew relative to the fixed axis of the
e r ~ ~ 4 /~
~J pinion gear, while the splined connection between the"~socketed bore
of the pinion gear and the ball-shaped exterior of the nut permit uniform
simultaneous rotation of such members whether their axes are coaxial or skewed.
This feature permits the connection of the screw to the mirror to follow the
arcuate travel of the mirror as its position is adjusted by the screws, with a
smooth and uniform driving relationship irrespective of the angle of the mirror.
.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a partially exploded perspective view of the motor
housing, with a portion of the housing being broken away to reveal one of the two
drive systems snd with a portion of the other drive system being shown in
exploded form.
Pigure 2 is a front view of the motor housing shown with the
mirror housing outlined in phantom snd showing the two pivot axes of the mirror
sssembly.
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Figure 3 is a sectional view through the assembled pinion gear, nut
and screw.
Figure 4 is a sectional view similar to figure 3, but illustrating
only the pinion gear.
Figure 5 is a sectional fragmentary view of the screw, viewed in
the direction of arrows 5-5 of figure 3.
DETAILED DESCRIPTION OF THE INVENTION
Referring first to Figures 1 and 2 of the drawings, there is
illustrated the motor housing 10 which contains a pair of identical motors 11 and
associated drive assemblies, only one of such motors being illustrated in
simpllified form in Figure 1. In Figure 2, the silhouetted outline of motor housing
10 is shown within the outline of the mirror housing 12 shown in phantom. Each
of th~ motors drives an actuator screw 14, one of which causes movement of the
mirror about horizontal pivot axis 16 und the other of which causes pivotal
movement of the mirror about vertical pivot axis 18 as a result of the
connection of such scews to the mirror at actuator connection points 20 and 2a.
The intersection of axes 16 and 18 represents the point of universal attachment
of the mirror to the unillustrated pedestal or base upon which the mirror is
conventionally mounted.
As shown in Figures 1 and 3, each of the drive systems comprises
a motor-driven worm gear 14 which engages the periphery of pinion gear 26. The
other components of the drive system comprise a ball-shaped drive nut 28, which
cooperates with actuator screw 14, and a wave washer 30 which provides a
resilient thrust besring surface between one end of pinion gear 26 and the
interior of motor housing 10 which prevents excess axial play and vibration. The
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1~ upper end of the actuator screw 14 protrudes through an opening in motor
housing 10.
As best shown in Figures 3 and 4, the exterior periphery of pinion
gear 26 is provided with pinion teeth 32 for driving engagement with worm gear
24. The interior of pinion gear 26 has a spherical socket surface 34 which
snuggly receives the ball-shaped exterior surface ~ of drive nut 28, while
permitting pivotal sliding movement there between. A retention lip 38 on one
axial end of spherical socket 34 resiliently yields outwardly to permit the drive
nut to be snapped into place in the direction from top to bottom as viewed in
Figure 4, thereby rele~sably retaining the drive nut within the pinion gear.
The interior of pinion gear 26 is further provided with a pair of
diametrically opposite longitudinally extending driving splines 40 which
cooperate with external grooves 42 in the spherical surface 36 of drive nut 28
(see Figure 1). The ends of grooves 42 are widened or flared to permit the ball to
pivot relative to pinion gear 26 about each of the two axes mutually
perpendicular to the longitudinal axis of the pinion gear.
Drive nut 28 has a threaded bore 44 which is dimensioned to
provide radial clearance with the unthreaded shaft portion 46 of actuator screw
14. The tip of sctuator screw 14 is provided with ball 48 and transverse pins 50which, in conventional fashion, establish a non-rotatable connection between
actuator screw 14 and a slotted socket in the unillustrated back of the mirror.
Actuator screw 14 has a square bore 52 extending along a portion
of its length, and l~iametrically opposite sides of shaft portion 46 have ~ pair of
U-shaped slots extending from the outer surface to bore 52 to define a pair of
fingers 56 which are resiliently yieldable in the radial direction relative to the
main body of shafl partion 46. The free ends of fingers 56 have an outwardly
extending pair of thread segments 58 (see Figure 5) dimensioned to normally
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1 engage the internal threads of bore 44 of nut 28. A hairpin-shaped spring 60 is
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received within bore 52 of screw 14. The legs o~ 0 normally maintain
threaded fingers 56 in their threa~engaging position shown in Figure 5, but
permit fingers to yield resiliently inwardly to disengage the threads in an
override or overload condition. Tips 62 of spring 60 are received in slots 64 ofscrew 14 to anchor the spring in position and to limit the radially outward
movement of the legs of the spring and of fingers 56, thereby limiting the
outward eogagement forces on the thread elements.
In operation, selective actuation of one of the motors, by
conventional means not forming a portion of this invention, causes rotation of
the associated worm gear 24 which in turn causes pinion gear 26 and drive nut 28to rotate. Rotation of drive nut 28 causes longitudinal movement of actuator
screw 14, because pins 50 of the screw engage are anchored in slots in the back
of thls mirror to prevent the screw from rotating. Such longitudinal movement
caus~s the mirror to pivot about one of its two axes of pivotal freedom, i.e., axis
16 or axis 1~1 of Figure 2. As the mirror pivots and its point of connection to tip
48 of actuator screw 14 travels along an arc, the ball and socket portions of
pinion gear 26 and drive nut 28 permit the axis of actuator screw 14 to pivot tofollow such arc of movement, thereby a~suring a smooth ~nd continuous driving
relationship throughout the travel of the mirror.
In the event that the motor-controlling switch continues to
provide current to the motor after the mirror has reached the limit of its travel,
continued rotation of drive nut 28 after screw shaft 14 can no lcnger move
longitudinally will cause the internal threads of the drive nut to resiliently foree
threaded fingers 'i6 of actuator screw 14 to yield inwardly against the outward
bias of spring 60, thereby permitting such continued rotation of motor 11, pinion
gear 26 and drive nut 28 without damage to any of the components. Similarily, inthe event that the mirror is manually repositioned, while motor 11 is inoperative,
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the resulting longitudinal movement of actuator screw 14 relative to the non-
rotating drive nut 28 will similarly cause threaded fingers 56 to resiliently yield
in a radially inward direction to disengage the threads and accomodate such
relative movement.
In the preferred embodiment, the housing, worm gear and actuator
screw are made of duPont Delrin 500, while the pinion gear and drive nut ~re
msde of duPont 801 nylon. The interference between retention lip 38 and the
diameter of drive nut 28 is .008 inches, while the interferences at the other end
of socket 34 is .080 inches. The diameter of the spherical sufrQce of the ball nUt
is .514 inches snd that of the spherical socket is .518 inches.
This invention may be further developed within the scope of the
following claims. Accordingly, the above specification is to be interpreted as
illustrative of only a single operative embodiment of the present invention,
rather than in a stricly limited sense.
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