Abstract:
A minor parking mechanism for an exterior rear view mirror that rotates a mirror head to a parked position. The mechanism has a mirror mounting bracket, a mirror head pivotally connected to the mirror mounting bracket so the mirror head can rotate from a deployed position to a parked position. A detent acting between the mirror mounting bracket and the mirror head to lock and unlock the mirror head. A spring acts against and locks the detent in position. A worm drive in the mirror head moves longitudinally along a shaft and rotates about an axis to act against the spring, which in turn reduces the spring force applied to the detent to enable it to disengage whereupon continued rotation of the worm drive causes the mirror head to rotate.

Description:
This invention relates to an mirror parking mechanism, and in particular to a parking mechanism which is able to move a mirror from an in use or deployed position to a second position where the outermost portion of the mirror head is closer to the vehicle body on which it is mounted. 
   BACKGROUND OF THE INVENTION 
   The invention subject of this specification is a variation of the invention described in corresponding Australian Patent Application No 68997/98 entitled “A Mirror Operating Mechanism”. It has a similar operating principle in that a drive means is used to move the mirror from a deployed position to what is termed a parked position with the outermost portion of the mirror head is closer to the vehicle body. This invention also has a similar operating principle in that the initial action of the drive means is to unload the detent which holds the mirror head in the deployed position before moving it to a parked position. 
   This has the advantage that the detent can provide sufficient holding force to prevent unwanted movement of the mirror head, while at the same time reducing the motor force required to overcome the detent to rotate the mirror head. 
   SUMMARY OF THE INVENTION 
   Accordingly, in its broadest form, the invention is a mirror parking mechanism for a vehicle exterior rear view mirror that rotates a mirror head to a parked position comprising:
         a mirror mounting bracket,   a mirror head pivotally connected to said mounting bracket so that said mirror head can rotate from a deployed position to a parked position where the outermost portion of said mirror head is positioned closer to said vehicle,   a detent acting between said mirror mounting bracket and said mirror head that changes from a locked position, where said mirror head is held with respect to said mirror mounting bracket, to a disengaged position where said mirror head is able to be rotated with respect to said mirror mounting bracket,   a spring acting against said detent to hold it in said locked position,   a gear wheel secured with respect to said mirror head,   a worm drive having a shaft that is journalled in bearings in said mirror mounting bracket, that allows movement of said worm drive in a longitudinal direction as well as rotation about its longitudinal axis, said worm drive engaging said gear wheel and one end of said shaft acting against said spring, and   a motor to drive said worm drive wherein during the initial rotation of said worm drive said detent prevents rotation of said gear wheel which causes said worm drive to move longitudinally and push against said spring to in turn reduce the spring force applied to said detent to enable it to disengage whereupon continued rotation of said worm drive causes said gear wheel and mirror head to rotate.       

   The axis of rotation of the mirror head with respect to the mounting bracket will be generally vertical, however, in some instances, this axis may be inclined from the vertical. Further, the axis may lie in a completely different plane, such as horizontal, in the case of where the mirror is folded against a vehicle in a substantially vertical plane. 
   As with the abovementioned earlier patent specification, the drive means preferably comprises an electric motor in combination with associated drive gears. The worm drive, which is operated by the drive means, initially causes movement of the spring holding the detent in place before it causes any rotation of the mirror head. This reduction in the force applied to the detent continues until the force required to move the spring is greater than the force required to rotate the mirror head out of the engagement with the detent. When this occurs, the worm drive remains stationery with respect to its bearings and rotates the gear wheel and mirror head. 
   Preferably, the mirror head is pivotally attached to the mounting bracket by a spigot or pin connection. Either of the parts may be provided with a spigot with the other part having a corresponding aperture within which the spigot locates. Alternatively, each part may be provided with an aperture through which a pin locates to pivotally connect the components. 
   The axis of the gear wheel is preferably coaxial with the pivot connection between the mirror head and mounting bracket. The gear wheel may also be releasably held with respect to the mirror head so that, in normal circumstances, rotation of the gear wheel will cause rotation of the mirror head. However, this engagement is releasable so that if the mirror head is manually moved or impacted, the connection between the gear wheel and the mirror head can be released to allow rotation of the mirror head. 
   Preferably, the interface between the gear wheel and the mirror head comprises a clutch that in normal circumstances provides sufficient coupling between the gear wheel and the mirror head. If force is applied directly to the mirror head, the clutch can disengage to thereby enable the mirror head to rotate freely with respect to the gear wheel. 
   Preferably, the clutch comprises a plurality of projections on the gear wheel which locate within correspondingly shaped recesses within the mirror head. A spring is used to force the projections into engagement with the recesses and therefore provide the necessary coupling between the gear wheel and the mirror head. If manual force is applied to the mirror head, then the gear wheel will not be able to rotate as a result of its engagement with the worm drive. Continuous rotation of the mirror head will overcome the spring force applied to the gear wheel and cause the gear wheel to separate with respect to the mirror head thereby disengaging the projections from the corresponding recesses. 
   The extent to which the mirror head is driven by the drive means will depend upon either abutment of the mirror head against the vehicle, or abutment of a portion of the mirror head against the mounting bracket that prevents further rotation. Preferably, the drive means motor is provided with current sensing circuitry which can sense an increase in current drawn upon the mirror head reaching the limit of its travel. The circuitry is able to de-energise the motor upon the increase in current being sensed. 
   From the parked position, the operation of the drive means is reversed and will drive the mirror head back to its deployed position. The detents will re-engage at the deployed position resulting in stalling of the drive means, an increase in current draw and resultant de-energisation of the motor. 
   In another aspect of the invention, the pivot connection between the mirror head and mirror bracket may be such as to allow movement of the mirror head in a direction which is normal to the axis of the pivot connection. The resilient means may comprise springs which are used to force the mirror head against detents which hold the mirror head in its deployed position. The drive means may be secured to the mirror head so that it operates a roller along a ramped surface that initially applies a force against the mirror head so that the mirror head is moved away from engagement with the detent. Once the detent holding force is reduced sufficiently, continued operation of the drive means will disengage the mirror head from the detents and will in turn rotate the mirror head with respect to the mounting bracket. 

   
     DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention will now be described, but it should be realised that the scope of the invention is not to be limited to the specific detail of the embodiments. The embodiments are illustrated in the accompanying drawings in which: 
       FIG. 1  shows a perspective view of a rear view mirror assembly according to this embodiment, 
       FIG. 2  shows a part perspective view that is partly cut-away to reveal aspects of the drive means, detent and resilient means, 
       FIG. 3  shows a part cross-sectional view of the mirror parking mechanism, 
       FIG. 4  shows a part cross-sectional view of a second embodiment of a mirror parking mechanism, 
       FIG. 5  shows a part plan view of the embodiment illustrated in  FIG. 4 ; and 
       FIG. 6  shows a cross-sectional view of the drive mechanism used in the second embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  illustrates a rear view mirror assembly  10  which comprises a mirror head  11 . The mirror head  11  has a mirror case  12  that supports mirrors  13 . The mirror head  11  is attached to a mounting bracket  14  via an upper and lower arms  15  and  16 . The mounting bracket  14  is designed to attach to the side of a motor vehicle. 
   Each of the upper and lower arms  15  and  16  pivotally attach to the mounting bracket  14 . According to this invention, drive means is provided which can move the mirror head  11  from a deployed position to a parked position where the outermost portion of the mirror head is brought as close as possible to the side of the motor vehicle. Preferably, the mirror head  11  is rotated so that the mirrors  13  face towards the side of the vehicle. 
     FIG. 1  shows a rear view mirror assembly  10  for use on the left-hand side of a vehicle. It will be obvious that the invention is equally suited to a mirror for use on the right-hand side of a vehicle. Some components will be a mirror image to those on the other side of the vehicle, although many of the components will be interchangeable between the left-hand and right-hand version. 
     FIG. 2  shows the upper arm  15  pivotally attached to the mounting bracket via pivot pin  20 . The lower arm  16  is pivotally attached to the mounting bracket by a similar pivot pin  20 . The pivot pin  20  on both the upper and lower arms  15  and  16  enable the mirror head  11  to rotate with respect to the mounting bracket  14 . 
   The detent comprises a detent roller  22  that engages within a detent recess  23  that is in the end of each of the upper and lower arms  15  and  16 . Each of the detent rollers  22  are pivotally mounted in a spring plate  25  that, as will be explained later, comprises a resilient means that forces each of the detent rollers  22  into the detent recesses  23 . The mirror head  11  is held in a deployed position while the detents are engaged. 
     FIG. 3  shows a cross-sectional view of the mounting bracket  14  and the pivot connections between the upper and lower arms  15  and  16  and the mounting bracket  14 . The drive means  27  comprises an electric motor with a common drive shaft that extends either side of the motor. There is a first worm drive on either side of the electric motor that engage secondary drive gears  28 . The secondary drive gear  28  is mounted on a shaft  29 . In addition to carrying the secondary drive gear  28 , the shaft  29  also carries the main drive worm  30 . The shaft  29  is journalled for rotation about its axis, and an end of the shaft  32  locates within a depression formed in the spring plate  25 . 
   The main drive worm  30  on each shaft  29  engages the main gear wheel  35 . The main gear wheel  35  is journalled for rotation about spigot  36  through which the pivot pin  20  locates. Each main gear wheel  35  is held to each of the spigots  36  via a belleville washer  37  and a retainer clip  38 . The belleville washer  37  provides a resilient spring force to an outer surface of the main gear wheel  35 . 
   The main drive gear  35  is also provided with a release to allow break-away of the mirror head  11  which comprise projections  40  that are located within corresponding recesses  41  in the upper and lower arms  15  and  16 . The projections and recesses  40  and  41  together comprise a clutch, the operation of which will be described below. 
   When the drive means  27  is operated, the motor worm drives the secondary drive gear  28  and main drive worm  30 . As the spring plate  25  is applying maximum force to the detent rollers  22 , the main gear wheels  35  resist rotation. Accordingly, as the secondary drive gear  28  and the main drive worm  30  rotate, the shaft  29  is caused to move along its longitudinal axis. This results in the end of each shaft  32  pressing against the spring plate  25 . 
   As operation of the drive means  27  continues, the spring plate  25  is progressively pushed and thereby reduces the load applied to each of the detent rollers  22 . When the force applied by each of the detent rollers  22  reduces sufficiently, the force required to further displace the shaft  29  is greater than the force required to rotate each of the main gear wheels  35 . At this point, the main drive worms  30  rotate the main gear wheels  35  and the upper and lower arms  15  and  16 , which are coupled to the main gear wheels  35  about pivot pins  20 . This results in rotation of the mirror head  20 . This rotation continues until the detent rollers  22  either engage further detents, or the mirror head  11  reaches a predetermined stop point which in turn causes the electric motor of the drive means  27  to stall. This results in a sudden increase in current drawn by the motor which is sensed by electronic control means. The motor is then de-energised. 
   Additional detent recesses may be provided for when the mirror head moves to its parked position. These additional detent recesses are preferably not as deep as the detent recesses  23  which provides sufficient holding force while at the same time allowing the drive means  27  to disengage the detent roller  22  without having to move the spring plate  25 . In the reverse direction, the main drive worm  30  drives the main gear wheels  35  until the detent rollers  22  relocate within detent recesses  23 . As soon as this occurs, the current drawn by the electric motor of the drive means  27  increases. This is sensed by electronic control means, whereupon it de-energises the motor. 
   The position of the worm drive  30  shown in  FIG. 2  will result in the mirror head  11  and the upper and lower arms  15  and  16  rotating in an anti-clockwise direction when viewed from above. The direction of rotation of the mirror head  11  can be reversed by locating the worm drive  30  on the opposite side of the gear wheels  35 . 
   If the mirror head  11  is to be manually moved to a parked position, or if the mirror head is impacted then the projections  40  will disengage from the recesses  41 . The projections  40  are shaped so that when sufficient force is applied to the mirror head  11 , the main gear wheel  35  is caused to move laterally along each spigot  36 . This movement is resisted by the belleville washer  37  which provides a spring force to the main gear wheel  35 . As soon as the projections  40  disengage from each of the recesses  41 , the upper and lower arms  15  and  16  are free to rotate about the pivot pin  20 . Mirror head  11  can be returned to the deployed position either manually or by operation of the drive means  27 . 
   The drive means  27  may be arranged to operate automatically such as when the ignition key is turned to the off position. In addition, the mirror will move to the deployed position as soon as the ignition key is switched on. Alternatively, switch means may be provided to initiate movement to either the parked or deployed position. 
   A second preferred embodiment is illustrated in  FIGS. 4  to  6 . This embodiment uses the similar principle of unloading the detents that hold the upper and lower arms  15  and  16 . 
   In this embodiment, springs  43  pull both the upper and lower arms  15  and  16  inwards with respect to the mounting bracket  14  so that the ends of the arms  15  and  16  bear against the detent pins  45 . The ends of each arm  15  and  16  are provided with detent recesses  46  into which the detent pins  45  locate. The detent pins  45  are rigidly connected to the mounting bracket  14 . 
   As with the first embodiment, the upper and lower arms  15  and  16  are pivotally attached to the mounting bracket  14  via pivot pins  20 . However in this embodiment, each of the ends of the upper and lower arms  15  and  16  are provided with a slot  48  through which the pivot pins  20  locate. This enables some movement of the upper and lower arms  15  and  16  in a direction normal to the axis of the pivot pins  20 . This movement is resisted by springs  43 . 
   An electric motor  50  is used to both push the upper and lower arms  15  and  16  away from the detent pins  45  and to then rotate the upper and lower arms  15  and  16  to a parked position. The electric motor  50  and associated drive components are located within a housing  51  that is secured to the upper and lower arms  15  and  16  by links  52 . The links  52  are pivotally attached to the housing  51  and to a spigot  53  on each of the upper and lower arms  15  and  16 . The housing  51  is restrained from rotating with respect to the mounting bracket  14  by an arm  58  that slides within an aperture  62 . An alternative means of restraining the housing  51  would be to connect the links  52  to the housing  51 . 
   The electric motor  50 , when energised, drives a worm drive  54  that in turn drives a gear  55 . The gear  55  drives a second worm drive  56  which in turn drives a gear  57 . The gear  57  is journalled around a shaft  59  which itself is journalled for rotation within the housing  51 . The gear  57  is coupled to the shaft  59  via clutch plates  60 . 
   The clutch plates  60  are linked to the shaft  59  via splines. However, if the gear  57  were to disengage from the clutch plates  60 , then it would be free to rotate about the shaft  59  A spring  61  is used to force the clutch plates  60  into contact with the gear  57 . 
   As with the previous embodiment, the gear  57  and clutch plates  60  are provided with projections on one of the components which engage recesses in the other component. In normal operating conditions, the spring  61  enables the engagement of the gear  57  with the clutch plates  60  to be maintained to ensure that operation of the electric motor  50  drives the shaft  59 . 
   Gears  63  are fixed to each end of the shaft  59 . The gears  63  drive gear sectors  64  which are formed in the ends of the upper and lower arms  15  and  16 . Rotation of the gears  63  will attempt to rotate the upper and lower arms  15  and  16  about pivot pins  20 . However, the detent pins  45  resist the rotation of the upper and lower arms  15  and  16  which in turn results in the gear sectors  64  remaining stationary with the gears  63  moving the shaft  59  and housing  51  with respect to the gear sectors  64 . 
   The shaft  59  is provided with rollers  65  at each end which engage ramps  66 . The ramps  66  are fixed with respect to the mounting bracket  14 . 
   Accordingly, initial operation of the motor  50  will result in the shaft  59  moving along the ramped surface  66 , and due to the angle of the ramped surface  66 , the shaft  59  will move towards the end of the upper and lower arms  15  and  16 . As the housing  51 , and therefore the shaft  59 , are linked to the upper and lower arms  15  and  16 , and as the housing  51  is prevented from rotating about shaft  59  by the arm  58 , movement of the shaft  59  will also cause movement of the upper and lower arms  15  and  16 . This movement will be against the force provided by the springs  43  which will in turn reduce the force applied to the detent pins  45 . 
   This outward movement of the upper and lower arms  15  and  16  will continue until the force required to move the shaft  59  along the ramps  66  will be greater than the resistance to rotation of the upper and lower arms  15  and  16 . At this point, the shaft  59  will remain stationary and the gear sectors  64  will rotate the upper and lower arms  15  and  16  about the pivot pins  20 . 
   The gear ratio between the gears  63  and gear sectors  64  may be of the order of 3:1. A 90° rotation of the mirror head  11  would thus result from a 270° rotation of the shaft  59 . 
   In the case of manual movement of the mirror head  11 , the detent force provided by the spring  43  will be overcome, and the gear sectors  64  will drive the shaft via gears  63 . This rotation will be resisted due the engagement of the clutch plates  60  with the gear  57 . This will result in the projections and recesses between the clutch plates  60  and the gear  57  forcing the gear  57  to separate from the clutch plates  60  against the force provided by spring  61 . Once the gear  57  disengages from the clutch plates  60 , the shaft  59  will be free to rotate. 
   Preferably, the clutch plates  60  are designed so that they will only re-engage through alignment of the projections and recesses once the clutch plates  60  have rotated through a full 360°. This will mean that there will be no unwanted re-engagement of the clutch plates  60  during the normal range of movement that would occur in either a forward to rearward manual movement of the mirror head  11 . 
   As will be seen from the above description, both embodiments provide designs which minimises the motor size required to drive the mirror head  11  to a parked position while at the same time providing sufficient detent force to hold the mirror head  11  in its deployed position. 
   In addition, the designs provide failsafe detents. The detents will re-engage even if the mirror head  11  has been electrically rotated to a parked position and is then manually rotated to its deployed position. This is an important safety feature.