Abstract:
A vehicle external review-view mirror assembly having an extension and retraction mechanism for a telescopic arm support that connects a mirror head to a mirror mounting bracket is disclosed. The assembly comprises: a hollow outer arm extending from the bracket, an inner arm mounted to the head and extending into the outer arm for relative sliding movement out of and into the outer arm; a driving wheel rotatably mounted to the inner arm or the head; a driven wheel rotatably mounted to the inner arm and positioned within the outer arm at a location spaced apart from the driven wheel; and a toothed belt extending between the driving wheel and the driven wheel for power transmission between them. A pair of laterally spaced apart contact rollers are mounted coaxially with the driven wheel, the pair of contact rollers engaging spaced apart bearing surfaces depending from the outer arm.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a National Stage of International Application No. PCT/AU02/01237, filed Sep. 9, 2002, which claims priority to Australian Patent Application Serial No. PR  7522 , filed Sep. 7, 2001. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     This invention relates to powered telescoping vehicle mirrors. More specifically, the invention relates to mechanisms for the extension or retraction of telescopic supports that are used to secure a mirror head of a rear vision mirror to a mounting bracket on a motor vehicle.  
         [0003]     It is desirable to be able to move a mirror head, which holds a mirror, with respect to a mounting bracket on a motor vehicle away from or back towards the mounting bracket. This enables the mirror head to be positioned either close to the side of the motor vehicle, or to be extended away from the motor vehicle. In its extended position, an increased field of view behind the vehicle is provided. This is useful where the rear view may be obstructed by a load on the vehicle or a trailer that is being towed for instance.  
         [0004]     Accordingly, it is an aim of the invention to provide a mechanism to extend or retract a mirror head.  
         [0005]     It is a further object of this invention to provide a means whereby a mirror head can be both manually or automatically moved away or towards the mounting bracket of a motor vehicle mirror.  
         [0006]     It is a still further object of the invention to provide a mechanism that has a high degree of efficiency enabling the use of a relatively small drive motor and associated gear train.  
       SUMMARY OF THE INVENTION  
       [0007]     According to a first aspect of the invention, there is provided a vehicle external review-view mirror assembly having an extension and retraction mechanism for a telescopic arm support that connects a mirror head to a mirror mounting bracket, the assembly comprising: 
        a hollow outer arm extending from the bracket;     an inner arm mounted to the head and extending into the outer arm for relative sliding movement out of and into the outer arm;     a driving wheel rotatably mounted to the inner arm or the head;     a driven wheel rotatably mounted to the inner arm and positioned within the outer arm at a location spaced apart from the driven wheel;     a looped transmission member extending between the driving wheel and the driven wheel for power transmission between them;     a pair of laterally spaced apart contact rollers mounted coaxially with the driven wheel, the pair of contact rollers engaging spaced apart bearing surfaces depending from or integral with the outer arm; and     a power transmission arrangement for transmitting power from the driven wheel to the outer arm,     wherein rotation of the driving wheel drives the driven wheel through the looped transmission member which causes the outer arm to move telescopically with respect to the inner arm.        
 
         [0016]     A pair of laterally spaced apart contact rollers and associated bearing surfaces contribute to the stability of the inner arm, and hence the head, with respect to the outer arm (and hence the bracket). This assists in preventing vibration of the mirror head and glass.  
         [0017]     Transmission power from the driven wheel to the outer arm can be achieved in a number of ways. In a simple arrangement, the driven wheel is biased towards the transmission portion sandwiching the outer surface of the looped transmission member belt against an inside surface of the outer arm and providing a friction drive.  
         [0018]     Preferably the power transmission arrangement for transmitting power comprises: 
        a rack substantially within and depending from the outer arm; and     at least one final drive pinion coaxially mounted to and driven by the driven wheel,     wherein the pinion meshes with the rack for power transmission thereto.        
 
         [0022]     Preferably the driving wheel is a driving sprocket, the driven wheel is a driven sprocket and the looped transmission member is a toothed belt.  
         [0023]     Preferably the assembly has a pair of final drive pinions arranged one on each side of the driven sprocket.  
         [0024]     Preferably each contact roller has an outside diameter substantially equal to that of the pitch circle diameter of the pinions and wherein the spaced apart bearing surfaces are arranged and constructed such that the contact rollers control the extent to which the pinions mesh with the rack. By controlling the extent to which the pinions mesh with the rack, wear can be minimised and power transmission can be optimised.  
         [0025]     According to a second aspect of the invention, there is provided a vehicle external review-view mirror assembly having an extension and retraction mechanism for a pair of telescopic arm supports that connect a mirror head to a mirror mounting bracket, the assembly comprising: 
        a pair of spaced apart substantially parallel hollow outer arms extending from the bracket;     a pair of spaced apart substantially parallel inner arms mounted to the head and extending into respective outer arms for relative sliding movement out of and into respective outer arms;     a drive motor mounted to the head;     a drive shaft mounted to the head and extending between the inner arms;     a pair of spaced apart driving wheels mounted to the drive shaft at opposite ends thereof and positioned substantially in line with respective inner arms; and     a pair of arm drive mechanisms extending from respective drive wheels into respective outer arms, each arm drive mechanism having a looped transmission member extending into its respective outer arm to a driven wheel,     wherein the drive motor drives the outer arms to move telescopically with respect to their respective inner arms.        
 
         [0033]     Preferably each arm drive mechanism further comprises a pair of laterally spaced apart contact rollers mounted coaxially with the driven wheel, the pair of contact rollers engaging spaced apart bearing surfaces depending from or integral with its respective outer arm.  
         [0034]     Preferably each arm drive mechanism further comprises: 
        a rack substantially within and depending from its respective outer arm; and     at least one final drive pinion coaxially mounted to and driven by the driven wheel,     wherein the pinion meshes with the rack for power transmission thereto.        
 
         [0038]     Preferably each driving wheel is a driving sprocket, each driven wheel is a driven sprocket and each looped transmission member is a toothed belt.  
         [0039]     Preferably each arm drive mechanism comprises a pair of final drive pinions arranged one on each side of the driven sprocket.  
         [0040]     Preferably each pair of contact rollers has an outside diameter substantially equal to that of the pitch circle diameter of the pinions and wherein the spaced apart bearing surfaces are arranged and constructed such that the contact rollers control the extent to which the pinions mesh with the racks.  
         [0041]     Preferably the assembly further comprises a clutch operably positioned between the drive motor and the drive shaft, the clutch limiting the torque that can be transmitted between the drive motor and the drive shaft.  
         [0042]     Preferably the clutch is a cone clutch. This type of clutch enables the mirror assembly to have a manual adjustment feel similar to that of existing manual telescoping mirrors such as that disclosed in the applicant&#39;s earlier file U.S. patent application Ser. No. 09/399,293 filed on 17 Sep. 1999 and its published corresponding Australian Application No. 56615/00.  
         [0043]     A specific embodiment of the invention will now be described in some further detail with reference to and as illustrated in the accompanying figures. This embodiment is illustrative, and is not meant to be restrictive of the scope of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0044]     A preferred embodiment of the invention is illustrated in the accompanying representations in which:  
         [0045]      FIG. 1  is a perspective view of a telescoping vehicle external rear view mirror assembly.  
         [0046]      FIG. 2  is a cutaway perspective view of a telescoping vehicle external rear view mirror assembly according to the invention.  
         [0047]      FIG. 3  is a cutaway perspective view of a part of the assembly of  FIG. 2 .  
         [0048]      FIG. 4  is an exploded perspective view of the assembly of  FIG. 2 .  
         [0049]      FIG. 5  is a partial front view of the assembly of  FIG. 2  showing two parallel arms of the assembly and associated drive components.  
         [0050]      FIG. 6  is a vertical sectional view taken through section A-A as shown on  FIG. 5 .  
         [0051]      FIG. 6   a  is a magnified partial view of  FIG. 6 .  
         [0052]      FIG. 7  is a vertical sectional view taken through section B-B shown on  FIGS. 6 and 6   a.    
         [0053]      FIG. 8  is a vertical sectional view taken through section C-C shown on  FIG. 7 .  
         [0054]      FIG. 8   a  is a magnified partial view of  FIG. 8 .  
         [0055]      FIG. 9  is a vertical sectional view taken through section D-D shown on  FIG. 7 .  
         [0056]      FIG. 10  is a vertical sectional view taken through section H-H shown on  FIG. 11  showing an alternative embodiment of the invention.  
         [0057]      FIG. 11  is a vertical sectional view taken through section B-B shown on  FIGS. 6 and 6   a.    
         [0058]      FIG. 12  is a vertical sectional view taken through section G-G as shown on  FIG. 5 . 
     
    
       [0059]     A perspective view of a “Trailer Tow” type vehicle external mirror assembly is shown in  FIG. 1 . This mirror assembly includes a mounting bracket  12 , a pair of spaced apart substantially hollow parallel outer arms  22  extending from the bracket  12  and a mirror head  15 . The mirror head  15  is movable with respect to the outer arms  22  from a retracted position to an extended position. In its extended position, the head is further displaced from the vehicle&#39;s side providing the vehicle driver with a wider field of view behind the vehicle. The mirror head  15  is also pivotable about a rotation axis  14 .  
         [0060]     Mirrors of the kind described above and shown in  FIG. 1  can either be manually adjustable or can be both manually and automatically adjustable away from or towards the mounting bracket  12 .  
         [0061]     Referring now to  FIG. 2 , a vehicle external rear view mirror assembly having an extension and retraction mechanism for a pair of telescopic arm supports that connect a mirror head  15  to a mirror mounting bracket  12  (not shown in this Figure) is shown in a cut-away perspective view.  
         [0062]     The mirror assembly includes a pair of spaced apart substantially parallel hollow outer arms  22  extending from the bracket  12  (not shown in  FIG. 2 ).  
         [0063]     Componentry associated with the outer arm  22  and inner arm  24  is more clearly shown in the cut-away perspective view of  FIG. 3 . The inner arm  24  is provided with a low friction wear strip  25  which slides along the inner surface of the tubular outer arm  22 .  
         [0064]     Now referring to  FIG. 3 , together with  FIG. 4 , a motor  60  (shown in  FIG. 4 ) which is mounted to the head  15  drives a shaft  70  through a gear train and cone clutch assembly  72 . Each end of pulley drive shaft  70  has a driving wheel  80  in the form of a sprocket. Shown most clearly in  FIG. 3 , driving sprocket  80  drives driven sprocket  34  through a looped transmission member in the form of a toothed belt  32 .  
         [0065]     A toothed belt has been found to be suitable as a synchronous flexible mechanical drive, however, other types of looped transmission members such as chains may also be used.  
         [0066]     The arm drive mechanisms, that drive the outer arms outwards and inwards telescopically with respect to their respective inner arms are more clearly shown by  FIG. 5  and cross-sectional drawings  6 , 7 ,  8  and  9 .  
         [0067]      FIGS. 6 and 8  are vertical sectional views taken through sections A-A and C-C respectively as shown on  FIG. 5 .  FIGS. 6   a  and  8   a  are magnified partial views of  FIGS. 6 and 8  respectively.  FIG. 8   a  shows a final drive wheel in the form of a pinion  35  engaging with a transmission portion in the form of a rack  30  attached to the outer arm  22 . Pinion  35  is part of a single combination driven wheel  28  as shown in  FIG. 4 . Rotation of pinion  35  causes the rack  30 , and hence the outer arm  22 , to move linearly with respect to the inner arm  24 .  
         [0068]     Viewing the perspective view of the combination driven wheel  28  shown in  FIG. 4 , together with the sectional views of  FIGS. 6   a ,  8   a  and  7 , it can be seen that wheel  28  has a central driven sprocket  34  sandwiched between a pair of pinions  35 . This arrangement enables balanced transmission of movement from the toothed belt  32 , through pinions  35  to the rack  30  and hence the outer arms  22 .  
         [0069]     In order to control the meshing of the pinions  35  with the rack  30  and in order to stabilize the arms with respect to each others contact, rollers  36  are provided on the outsides of the pinions  35 . These contact rollers  36  roll against flat portions  90  which form tracks located adjacent the rack  30 . The diameter of the contact rollers  36  are equal to the gear pitch circle diameter of the pinions  35  that mesh with rack  30 . As a result, the rubbing velocity of the contact rollers  36  with respect to the tracks  90  alongside the rack  30  is zero or approximately zero. Therefore, less power is required to drive the mirror head  15  in and out with respect to the mirror bracket  12 .  
         [0070]     Contact rollers  36  are biased into engagement with flat portions  51  adjacent the rack  30  by a spring  41  as shown in  FIG. 3 . The spring is mounted to the inner arm  24 . The combination wheel  28  is rotatably mounted to a carrier  40  which is positioned on one end of spring  41 . The other end of spring  41  is retained against the inner arm  24  as shown in  FIG. 3 . Carrier  40  is guided within the inner arm  24  by guide ribs  43  as shown in  FIG. 9  (section D-D). Carrier retention clips  46 , shown in  FIGS. 6   a  and  8   a  retain the carriers  40  and  50  during assembly. They also hold wear strip  25  against the inner arm  24  during assembly.  
         [0071]     A second spring  41 , carrier  40  and idler wheel  38  is shown in  FIGS. 6   a  and  3 . This second assembly, in conjunction with the first assembly, ensures that the inner arm  24  is held in a stable telescopic relationship with respect to outer arm  22 . The action of the springs  41  and  51  at spaced apart positions along the inner arm  24  causes stability to be achieved between the outer arms  22  and the inner arms  24  and hence the mirror head  15  and mirror base  12 . A wedging action between wear strip  25  and outer arm  22  as shown in  FIG. 7  provides a high level of stability which reduces vibration-induced image displacement.  
         [0072]     The combination wheel  33  performs two functions simultaneously. Firstly it transmits motive power through its pinions  35  to telescopically drive the mirror head  15  in and out from the bracket  12 . Secondly it transmits the force generated by the compressed spring  41  from the inner arm  24  to the outer arm  22  so as to wedge the wear strip  25  against the outer arm  22  thereby eliminating, or at least reducing any slop between the inner and outer arms  24  and  22 . The use of a single combination wheel to perform these two distinct functions simplifies the overall mirror assembly significantly.  
         [0073]     A reinforcement member  16  shown in  FIGS. 4, 6 ,  8  and  9  is attached to the inner arm  24  and mirror head  15  as best shown in  FIG. 9  (a vertical sectional view taken through section D-D shown on  FIG. 7 ). The reinforcement member  16  supports components including guide roller  17  as shown in  FIG. 6   a.    
         [0074]     Guide roller  17  guides the toothed belt  32  and tensions the belt  32  as the mirror assembly is assembled.  
         [0075]     Power for the drive mechanisms is provided by motor  60  shown most clearly in  FIGS. 4 and 5 . The motor  60  drives a reduction gear box terminating in a worm gear  65  that meshes with a clutch gear  74 . The motor gear drive mechanism is non-back drivable due to the provision of the worm gear  65  that engages the clutch gear  74 . This prevents the clutch gear  74  from rotating when the mirror head  15  is forced towards or away from the mirror bracket  12 . This ensures that the gear train does not back drive and that the clutch  72  operates.  
         [0076]     Meshing between worm gear  65  and clutch gear  74  is most clearly shown in the sectional view of  FIG. 12  (taken through section G-G shown in  FIG. 6 ). This Figure also shows a cone clutch assembly  72  comprising clutch gear  74  and cone-shaped clutch disc  73 .  
         [0077]     Clutch disc  73  is keyed to a shaft  70  that is mounted to the head  15  on bearings  78  and extends between the inner arms. The clutch assembly  72 , positioned between the worm gear  65  and the drive shaft  70  limits the torque that can be transmitted between the drive motor  60  and the drive shaft  70 . The cone clutch design enables a relatively low spring force (spring  76 ) to be used and enables the components to be kept to a compact size while at the same time providing a smooth, friction adjustment feel to the mirror head as it is moved manually out from or towards the bracket  12 . The result is an adjustment feel that is similar to existing manual telescoping mirrors.  
         [0078]     Alternative designs using different clutching arrangements can also be used. For instance, clutches incorporating detenting ramps can also be used which would provide a ratcheting type manual override adjustment feel with associated indexing clicking noises.  
         [0079]     Drive shaft  70  extends between the two inner arms  22  as best shown in  FIG. 2 . A pair of spaced apart driving pulleys in the form of drive sprockets  80  are provided at opposite ends of drive shaft  70 . Driving sprockets  80  are positioned substantially in line with respective inner arms  22  and drive driven sprockets  34  through toothed belts  32 .  
         [0080]     The use of a synchronized flexible mechanical drive in the form of toothed belts  32  to remotely drive the rack and pinion mechanism within each arm provides an efficient and compact synchronized drive to the pair of arms. Both toothed belts  32  are driven by a single connecting drive shaft  70 , so that the drive between each arm remains the same and makes the potential problem of skew drive jamming unlikely, if not impossible.  
         [0081]     End of travel stops are provided by components independent to the drive mechanism so that damage to the drive train is not caused by impact or external forces that the mirror head  15  may be subjected to. Clips  18 , shown in  FIG. 4  provide an end stop against shoulder  19  on inner arm  24 .  
         [0082]     Referring to  FIG. 7 , it can be seen that the spring loaded pinion drive comprising spring  41 , carrier  40 , combination driven wheel  33  and rack  30  together with tracks  90 , provides a compact assembly for driving the outer arms  22  with respect to the inner arms  24 . A cabling harness conduit  31  is provided above the rack  30 .  
         [0083]     An optional current sensing circuit can be included to turn off the electric motor  65  thereby preventing the clutch assembly  72  from slip disengaging at the ends of travel and therefore preventing the unnecessary running of the motor, reduction gears and clutch.  
         [0084]     The embodiment described above is a dual arm mirror assembly. However, the invention is also applicable to a single arm mirror.  
         [0085]     In a second embodiment of the invention, the wear strip  25  shown in  FIG. 9  is replaced with an arrangement including a pair of rollers pair  91 , as shown in  FIG. 10  (a vertical sectional view taken through section H-H shown in  FIG. 11 ). One of the roller pair is shown in cross section in  FIG. 11 . The second embodiment of the invention eliminates sliding contact between the inner and outer arms  24  and  22  and therefore reduces the friction between them.  
         [0086]     Australian Patent Application No. 68997/98 titled “A mirror operating mechanism”, International Patent Application No. PCT/AU00/00009 titled “A mirror rotation mechanism” and International Patent Application No. PCT/AU00/00076 titled “Mirror parking mechanism” described power fold mechanisms which move a mirror head from its normal in use position to a parked position where the mirror head is rotated towards the body of the vehicle. Any of these inventions could be used with the assembly described in this invention and the disclosure of these specifications is herewith incorporated in their entirety into this specification.  
         [0087]     International Application No. PCT/AU02/00353 titled “External vehicle mirror having self-loading pivot and improved end stop” discloses a mirror assembly having a self-loading pivot mechanism wherein initial rotation of the mirror head with respect to the mirror base causes pre-loading of a spring. These features and other features disclosed could be used with the present invention and the disclosure of PCT/AU02/00353 is herewith incorporated in its entirety into this specification.  
         [0088]     International Application No. PCT/AU00/00413 titled “Method of producing a plastic moulded part including a film covering” discloses a method of forming a moulding component comprising an outer thin film component with an adhered moulded shell. The method of that disclosure could be used to mould the hollow form components subject of this invention and the disclosure of this application is incorporated herewith in its entirety.  
         [0089]     It would also be possible to incorporate other components with the mirror mounting bracket head and/or arms. Such components include electronic sensors such as proximity sensors to determine if the vehicle mirror is close to an obstruction, sensors that sense external temperature and humidity, and sensors incorporated with the car security system such as motion detectors. Other various electronic equipment may be incorporated into the mirror mounting brackets such as lights used to light the area around the vehicle, or lights that may be controlled from within the vehicle that enable the light to be moved so as to provide directional lighting. Speakers and microphones used to communicate to people external of the vehicle may also be incorporated as well as antennas for various apparatus such as mobile phones, GPS devices and other radio communication devices. In addition, transmitters may be incorporated into the mounting bracket, which are used for controlling external objects such as garage doors or providing radio transmissions which may be used, for example, to track or locate the vehicle. Other electronic devices such as automatic toll payment systems or remote transaction systems may be incorporated into the mounting bracket to enable electronic registration of various toll payments.  
         [0090]     Cameras may also be incorporated into the mounting bracket, which are both forward and rearward looking which are designed to continuously record digital images and to store those images either on command or as a result of an accident or incident. Motion sensors including accelerometers can be used to determine the occurrence of an accident or incident so that images before and after the event are stored.  
         [0091]     While the present invention has been described in terms of preferred embodiments in order to facilitate better understanding of the invention, it should be appreciated that various modifications can be made without departing from the principles of the invention. Therefore, the invention should be understood to include all such modifications within its scope.