Electrically powered foldable outer rearview mirrors for motor vehicles

The rearview mirror has a shaft attached to a base, a mirror body rotatably mounted on the shaft, a frame fixed to the mirror body, an electric drive motor and a speed reduction gear mechanism fixed to the frame, and a clutch gear mounted on the shaft and engaged with a final stage gear of the speed reduction gear mechanism. The clutch gear has a clutch device for halting the mirror body in a mirror erected position including teeth circumferentially disposed on the undersurface of the clutch gear, ball holding recesses in the upper surface of the frame root portion and steel balls located between the clutch gear undersurface and the frame root portion upper surface and engagable with the teeth so as to be engagable in and disengagable from the ball holding recesses; and a clutch device for avoiding shocks due to halting the mirror body including ball retaining recesses in the clutch gear upper surface, a ball guide having throughgoing holes and steel balls engaged in the throughgoing holes of the ball guide and engagable in and disengagable from the ball retaining recesses to restrain the frame from unnecessary vertical motion during operation so that mirror surface chattering is prevented and the clutch gear load is relieved.

BACKGROUND OF THE INVENTION 
The present invention relates to an electrically powered foldable outer 
rearview mirror for a motor vehicle. 
An electrically powered foldable outer rearview mirror for a motor vehicle 
is known comprising a mirror body rotatably supported on a shaft mounted 
on a base, an electric drive means and speed reduction gear mechanism 
mounted on a frame of the mirror body, and a clutch gear mounted on the 
shaft so as to be fixed to the shaft when the mirror is electrically 
powered and to be free of the shaft when the mirror is forcibly rotated. 
The erected state and the folded state of the mirror body are maintained 
by engaging recesses formed on a shaft base portion with steel balls which 
are arranged on the frame root portion or on the undersurface of the 
clutch gear. 
In electrically powered foldable outer rearview mirrors as described 
hereinbefore, as disclosed by Japanese Published Patent No. Hei 3-16841, 
several steel balls are provided on a frame (or a bracket) root portion in 
the mirror body, while first and second recesses are provided in the shaft 
base portion according to the erected mirror position and folded mirror 
position. The steel balls are engaged in the first and second recesses in 
the respective mirror erected and folded mirror position. When the mirror 
body is rotated, each steel ball is rotated on a sliding surface of the 
shaft base extending through the recesses. Also in another system 
disclosed in Published Japanese Utility Model Registration Application No. 
Hei 3-69552, the clutch gear is provided between the frame root portion 
and the shaft base portion and several steel balls are arranged between 
the upper surface of the clutch gear and the frame root portion, and 
between the lower surface of the clutch gear and the shaft base portion, 
respectively. 
In a conventional system for automatically folding the outer rearview 
mirror, however, chattering of the mirror surface occurs, which is caused 
by a vertical movement of the mirror body during rotation because: 
1. the clutch gear or a stopper plate is arranged between the shaft and the 
frame and the positioning of the mirror and the shock avoidance properties 
are determined by the steel balls so that the system does not have good 
stability and chattering is easily caused by inaccurate engagement of the 
parts of the operating mechanism during vehicle operation; 
2. the clutch gear or the stopper plate is provided between the shaft and 
the frame so that the system is not waterproof and dustproof; 
3. the frame moves vertically when the mirror is electrically rotated to 
erect and fold the mirror body and the mirror body can be forcibly 
rotated; and 
4. in the system described by Published Japanese Patent Application No. Hei 
3-16841, both clutches are simultaneously released at the time the mirror 
is forcibly rotated so that the gear teeth bear a much heavier load. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an electrically powered 
foldable outer rearview mirror for a motor vehicle in which the frame is 
prevented from moving vertically during electrical rotation of the mirror 
to erect or fold it or during forced rotation of the mirror to relieve the 
load on the gear teeth. 
According to the present invention, the electrically powered foldable outer 
rearview mirror comprises a shaft having a shaft base portion mounted on a 
base; a mirror body rotatably mounted on the shaft and having a mirror 
erected position and a mirror folded position; a frame fixed to the mirror 
body and having a root portion provided with a throughgoing hole through 
which the shaft extends and having an upper surface and an undersurface 
acting as a bearing surface for the shaft base portion; a stop element 
provided between an undersurface of the frame root portion and the shaft 
base portion for determining a forward and rearward boundary of the mirror 
folded position; electric drive means for rotating the mirror body around 
the shaft and a speed reduction gear mechanism connected to the electric 
drive means, the electric drive means and the speed reduction gear 
mechanism respectively fixed to the frame and the speed reduction gear 
mechanism having a final stage gear; a clutch gear mounted on the shaft 
and engaged with the final stage gear of the speed reduction gear 
mechanism; and clutch means for avoiding shocks due to halting motion of 
the mirror body located on an upper surface of the clutch gear and clutch 
means for halting the mirror body in the mirror erected position located 
on an undersurface of the clutch gear, the clutch means for halting the 
mirror body in the mirror erected position being mounted not between the 
frame root portion and the shaft base portion but on the upper surface of 
the frame root portion and engaged in the frame root portion upper surface 
to prevent the frame from vertically moving when the mirror body is 
electrically rotated and forcibly rotated. 
The clutch means for avoiding shocks due to halting motion of the mirror 
body includes a plurality of ball retaining recesses provided in the upper 
surface of the clutch gear and arranged circumferentially disposed on the 
clutch gear upper surface, a ball guide mounted on the shaft and spaced 
from the upper surface of the clutch gear and formed with a plurality of 
circumferentially disposed throughgoing holes and a plurality of steel 
balls engaged in the throughgoing holes of the ball guide, so the steel 
balls are movable over the clutch gear upper surface so as to pass over 
the ball retaining recesses when the mirror body is forcibly rotated and 
so they are engaged in the ball retaining recesses when the clutch means 
for avoiding shocks due to halting motion of the mirror body is not 
released. 
The clutch means for halting the mirror body in the mirror erected position 
includes teeth formed along a circumferential direction on the clutch gear 
undersurface, a plurality of ball holding recesses formed in the frame 
root upper surface and a plurality of steel balls provided between the 
undersurface of the clutch gear and the frame root upper surface for 
engagement with the teeth and the ball holding recesses. 
When the motor is operated the final stage gear of the speed reduction gear 
mechanism engaged with the clutch gear rotates and the clutch gear is then 
rotated. When the final stage gear rotates and the clutch means for 
avoiding shocks due to halting the mirror body is engaged or "on", so that 
the balls are engaged in the ball retaining recesses, the mirror body is 
electrically driven to rotate toward an erected or folded position. When 
the mirror body is rotated to the erected state from the folded state, the 
electric drive means is halted by operation of the clutch means for 
halting the mirror body in the mirror erect position and the rotation of 
the mirror body is halted to keep it in the erected position. 
When the mirror body is forcibly rotated, the clutch gear and the final 
stage gear of the speed reduction gear mechanism are not disengaged and 
rotate together with the mirror body. When the mirror body is forcibly 
rotated, only the clutch means for avoiding shocks due to halting the 
mirror body located on the upper surface of the clutch gear is released. 
When this clutch means is released, the steel balls of it move on the 
upper surface of the clutch gear after leaving the ball retaining recesses 
on the clutch gear upper surface and they slide up in the throughgoing 
holes of the ball guide so that the shock avoidance clutch means is 
released. After the mirror body is forcibly rotated and is electrically 
moved again, since the shock avoidance clutch means has been already 
released, the clutch gear runs idle on the shaft and the steel balls run 
over the teeth of the gear undersurface and drop into the ball holding 
recesses so that the mirror body can

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An electrically powered foldable outer rearview mirror assembly for a motor 
vehicle according to the invention is shown in FIG. 1. 
In the electrically powered foldable outer rearview mirror assembly 10 
according to the invention, a mirror body 15 is rotatably supported on a 
hollow shaft 13 which is mounted on an extended part 12 of a base 11. An 
electric drive means (motor) 20 and a speed reduction gear mechanism 22 
are respectively accommodated in a root portion 18 of a frame fixed to the 
mirror body 15. A clutch gear 30 is provided around the periphery of the 
shaft so as to be fixed to the shaft when the mirror body 15 is 
electrically folded and to be free of the shaft when the mirror body is 
forcibly rotated. A worm 54 is mounted on an output shaft 21 of the motor 
20 to be connected with the speed reduction gear mechanism 22 and the 
final stage gear 23 of the speed reduction gear mechanism 22 is engaged 
with the clutch gear 30 mounted on the shaft 13. In FIG. 1, a sealing cap 
60 covers the whole electric drive means 20 and a printed circuit board 61 
for a motor control circuit. 
The frame 17 comprises the root portion 18 provided with a hole 24 through 
which the shaft 13 extends and a wing portion 19. The wing portion 19 is 
secured on an inner wall of the mirror body 15 by several screws. A mirror 
element 16 is mounted in the mirror body 16 via an actuator unit (not 
shown) for adjusting a reflecting angle of the mirror. For enabling a 
smooth rotation about the shaft, the undersurface of the root portion 18 
of the frame provides a bearing surface 25 for a shaft base portion 14 of 
the shaft 13. 
The clutch gear 30, a ball guide 40, a washer 43, a sleeve 44, a coil 
spring 45, a spring retainer 46 and a fastener 47 are mounted in that 
order on the shaft 13 which penetrates through the hole 24 in the frame 
root portion. Steel balls 34, 36 are mounted between a plate portion 41 of 
the ball guide 40 and an upper surface of the clutch gear and also between 
the undersurface of the clutch gear and the upper surface of the frame 
root portion 18 (See FIG. 1 and FIG. 6). For determining a position to 
which the mirror body is rotated, a stop element 26 (see FIG. 8) is 
provided protruding from the shaft base portion 14 and a guide groove 27 
having an arc-shaped plane surface is formed in the undersurface of the 
frame root portion 18 to engage with the stop element 26 (FIGS. 3 and 8). 
Although it is not shown in the embodiment in the drawing, alternatively, 
it is possible to form the recess of the shaft base portion 14 and to 
provide the stop element on the undersurface of the frame root portion 18. 
In the present embodiment the motor is transversely mounted on the frame 
provided in the mirror body. Although it is not so mounted in the present 
embodiment, it is possible to mount the motor vertically on the frame with 
the output shaft downwardly directed to engage the pinion with the speed 
reduction gear. FIG. 6 is a detailed longitudinal cross-sectional view of 
the apparatus in FIG. 1. FIG. 8 is an exploded perspective view of a 
plurality of parts around the shaft including a number from the speed 
reduction gear mechanism, however respective washer 43, sleeve 44, coil 
spring 45, spring retainer 46 and fastener 47 are eliminated therefrom. As 
shown in FIGS. 6 and 8, several protruding elements 28 are provided around 
the shaft 13 extending in the direction of the shaft axis for mounting the 
ball guide 40 and grooves 49 are formed through the hole 48 to receive and 
engage with the protruding elements 28 so that the ball guide 40 is held 
nonrotatably on the shaft 13. A plurality of throughgoing holes 38 (four 
holes in FIG. 8) are formed on the circumference of the plate 41 of the 
ball guide 40 and arc shaped cutouts 50 are also formed in the outer 
periphery of the plate portion 41 for avoiding engagement with the final 
stage gear 23. 
The clutch gear 30 is provided with a hole 31 (see FIG. 8) in a center 
thereof for receiving the shaft 13 and is formed with a clutch means for 
avoiding shocks due to halting the mirror body on the upper surface 
thereof and a clutch means for halting the mirror body in a mirror erected 
position on the undersurface thereof respectively. 
The clutch means for avoiding shocks due to halting the mirror body 
comprises a plurality of ball retaining recesses 32 circumferentially 
disposed in the upper surface of the clutch gear 30, the ball guide 40 
mounted on the shaft 13 spaced from the upper surface of the clutch gear 
and having a plurality of throughgoing holes 38 circumferentially disposed 
in a plate portion 41 thereof and a plurality of steel balls 34 engaged in 
the throughgoing holes 38. When this clutch means is engaged or "on", the 
steel balls 34 are engaged in the ball retaining recesses 32 and the 
clutch gear 30 is fixed on the shaft 13. When this clutch means is 
disengaged or released, the steel balls 34 are dislodged from the 
retaining recesses 32 and move over the upper surface of the clutch gear 
30 and over the ball retaining recesses 32 which occurs when the mirror is 
forcibly rotated (FIGS. 6 and 8). 
Furthermore the clutch means for halting the mirror body in the mirror 
erected position includes a plurality of teeth 33 circumferentially 
disposed on the undersurface of the clutch gear 30, a plurality of ball 
holding recesses 35 formed on the upper surface of the frame root portion 
18 and a plurality of steel balls 36 mounted between the undersurface of 
the clutch gear 30 and the upper surface of the frame root portion 18 and 
engagable with the teeth 33 so that the steel balls 36 can be engaged in 
the ball holding recesses 35 (FIGS. 5 and 7). 
The structure of the gears of the speed reduction gear mechanism 22 
connected to motor 20 is not limited to one embodiment illustrated by 
FIGS. 2 to 4 and FIG. 8. In the embodiment of the speed reduction gear 
mechanism 22 illustrated in the drawing, gears mounted for rotation around 
first to the fourth axes 51 to 53 and 59 are provided. The worm wheel 55 
is supported rotatable around first axis 51 and engages with the worm 54 
which is fixed to the output shaft 21 of the motor 20. The worm wheel 55 
is connected nonrotatably and coaxially with the twin gear 55a, which is 
engaged with a first intermediary gear 56 rotatable about the second axis 
52 and having a coaxial twin gear 56a, which, in turn, is engaged with a 
second intermediary gear 57 rotatable about the third axis 53 and having a 
twin gear 57a. The twin gear 57a drives, in turn, the third intermediary 
gear 58 coaxial with the first intermediary gear 56 and having the 
connected twin gear 58a engaged with final stage clutch gear 23 rotatable 
about the fourth axes 59. The final stage gear 23 is engaged with and 
drives clutch gear 30. 
As described hereinabove, the contact of the frame and the shaft 13 is 
composed in a surface contact in which the clutch gear 30 composed of the 
locating clutch means and the shock avoidance clutch means on both 
surfaces is disposed on the frame root portion. In operation of the device 
described above, when the motor 20 is electrically actuated, the final 
stage gear 23 of the speed reduction gear mechanism 22, which engages the 
clutch gear 30, is driven rotatably. During the rotation of the final 
stage gear 23, since the steel balls 34 on the upper surface of the clutch 
gear 30 are engaged in the ball retaining recesses 32 and the clutch means 
for avoiding shocks due to halting the mirror body is kept "on" or 
engaged, the mirror body is rotated by the motor 20 into the erected state 
or the folded state and is stopped in the erected or folded position by 
operation of the clutch mechanism. That is, when the mirror body is 
rotated by the motor 20, the clutch means for avoiding shocks due to 
halting or stopping of the mirror body comprising the recesses 32 of the 
upper surface of the clutch gear 30, steel balls 34 and the plate portion 
41 of the ball guide 40, is maintained in an "ON" or engaged condition, so 
that the clutch gear 30 is fixed on the shaft 13 and then the final stage 
gear 23, that is, the frame 17, rotates around the clutch gear 30. 
When the mirror body 15 is folded, the stop element 26 engages in the guide 
groove 27 (as shown in FIG. 8), so that the motor 20 is locked to halt it. 
When the mirror body 15 is being erected, the motor is locked to halt it 
after the steel balls 36 contact with teeth 33 of the undersurface of the 
clutch gear 30. In this state, the output torque of the final stage gear 
23 is adjusted for rotation in one direction, but not in the opposite 
direction. 
When the mirror body 15 is forcibly rotated, the engagement of the clutch 
gear 30 with the final stage gear 23 of the speed reduction gear mechanism 
22 is not released and they rotate with the mirror body. The locating 
clutch means comprises steel balls 36 engaged in the ball holding recesses 
35 of the frame root portion 18 and the teeth 33 of the undersurface of 
the clutch gear 30 and cannot be released when the frame position is 
changed. In releasing the clutch means for avoiding shocks due to halting 
the mirror body, the steel balls 34 are rotated on the upper surface of 
the clutch gear 30 running over the ball retaining recesses 32 on the 
upper surface of the clutch gear and are held in the throughgoing holes 38 
which are formed on the plate portion 41 of the ball guide and thereafter 
the steel balls 34 slide over the clutch gear upper surface, so that the 
shock absorbing clutch means is released or not engaged. After the mirror 
body 15 is forcibly rotated, when the mirror body 15 is rotated by the 
motor 20 again, since the shock avoidance clutch means (i.e. means for 
avoiding shocks due to halting of the mirror body) has been already 
released, the clutch gear 30 runs idle with respect to the shaft 13 to let 
the steel balls 36 run over the teeth 33 of the gear undersurface so that 
the steel balls fall into the ball retaining recesses 32 so that the 
mirror body 15 is folded. 
According to the present invention, the bearing of the frame and the shaft 
base is a surface bearing so that the improved electrically foldable outer 
rearview mirror resists chattering and has an improved vertical frame 
movement when the mirror body is rotated by the electric motor. Also the 
locating clutch means is not released when the mirror body is forcibly 
rotated by hand so that gear teeth do not bear a burden. The clutch gear 
of the rearview mirror which has both clutch means mounted on the upper 
part of the frame root portion provides water resistance and dust 
resistance properties to the structure. The number of assembly steps has 
been reduced and a compact mirror structure has resulted. 
While the invention has been illustrated and embodied in an electrically 
powered foldable outer rearview mirror for a motor vehicle, it is not 
intended to be limited to the details shown, since various modifications 
and structural changes may be made without departing in any way from the 
spirit of the present invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.