Abstract:
An extendable, foldable rearview mirror assembly comprises a ball bearing assembly for facilitating the extension of a reflective element assembly relative to a cantilevered extension arm while minimizing unwanted movement of the reflective element assembly. The rearview mirror assembly also comprises a roller bearing assembly for facilitating the pivotal movement of the extension arm relative to a pivot base frame supporting the extension arm while minimizing unwanted movement of the extension arm. A pin connection pivotably attaches the extension arm to the base frame, thereby strengthening the connection between the two parts while minimizing unwanted movement of the extension arm.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. provisional application Ser. No. 60/319,979, filed Feb. 27, 2003, which is incorporated herein in its entirety. 

   FIELD OF THE INVENTION 
   The invention relates to an external vehicle mirror and, more particularly, to an external vehicle mirror having powered folding and powered extension functionality. In another aspect, the invention relates to an extendable vehicle mirror comprising a recirculating ball bearing assembly enabling both a close fit and slidability between a mirror support arm and an extendable mirror assembly. In another aspect, the invention relates to a folding vehicle mirror comprising a pivot assembly incorporating roller bearings enabling a close fit and pivotability between a mirror support arm and a pivot support base. In another aspect, the invention relates to a folding vehicle mirror comprising a pivot assembly incorporating parallel flanges slidably communicating with upper and lower opposed surfaces of a mirror support arm which is pivotably pinned to one of the flanges. 
   DESCRIPTION OF THE RELATED ART 
   External mirrors are ubiquitous for contemporary vehicles and have long been used to aid the driver in operating the vehicle, especially in improving the rearward view of the driver. Over time, more and more functionality has been incorporated into the external mirrors. For example, it is common to pivot or fold the external mirror against the vehicle body to prevent the jarring of the mirror when the vehicle is not operated. The mirror folding function can incorporate a power assist, such as that disclosed in U.S. Pat. No. 5,684,646. External mirrors are also extendable away from the vehicle to increase the field of view, which is useful when towing a trailer. Mirrors incorporating both the powered fold and powered extension functionality are well-known. An example of such a mirror is disclosed in U.S. Pat. No. 6,213,609, assigned to the assignee of the current application, which is incorporated by reference. 
   The extension assembly typically comprises a support arm attached to the vehicle in cantilevered fashion which slidably communicates with a mating receptacle in a reflective element assembly. The support arm and the mating receptacle are typically provided with cooperative bearing surfaces suitable for the slidable movement between the support arm and the reflective element assembly. An extension actuator in the support arm drives the reflective element assembly along the support arm to selectively extend and retract the reflective element assembly. 
   In order to provide the operator with an adequate rearward view, particularly when the vehicle is used to tow a trailer, the rearview mirrors are typically large, relatively heavy assemblies. The large mirror size also contributes to large wind loads imposed on the reflective element assembly when the vehicle is in use. To facilitate the extension of the reflective element assembly along the support arm, the tolerances between the bearing surfaces must not be so close as to impede their slidable movement. Otherwise, a more robust actuator must be used to overcome the friction between the bearing surfaces, thereby adding weight to the mirror assembly, increasing cost, increasing power consumption, and reducing durability. On the other hand, greater tolerances between bearing surfaces can lead to unacceptable vibration of the mirror assembly, and the imposition of excessive forces on the support arm, which can contribute to premature failure of mirror components and adversely impact the performance of the extension mechanism. This is particularly significant with large mirrors supported on a cantilevered support arm. 
   If the mirror is also foldable, the pivot mechanism must also be capable of easily pivoting the support arm while providing adequate structural support to the cantilevered support arm and the weight of the supported reflective element assembly. Overly close tolerances between rotating bearing surfaces, while enhancing the structural strength of the pivot mechanism, can impede the relative movement of the pivot arm about its support base. However, greater tolerances can lead to vibration of the mirror assembly, and the imposition of excessive forces on the component parts, which can also contribute to premature failure of mirror components and adversely impact the performance of the folding mechanism. 
   SUMMARY OF THE INVENTION 
   In one aspect, the invention relates to a vehicular rearview mirror assembly, comprising: a base assembly comprising a base frame for mounting the rearview mirror assembly to a vehicle; a reflective element mounted to the base frame for providing an occupant of the vehicle with a rearward view; and a low friction bearing interposed between the base frame and the reflective element for facilitating movement of the reflective element relative to the base frame. 
   In another aspect, the invention relates to a vehicular rearview mirror assembly, comprising: a reflective element mounted to a mounting frame for providing an occupant of the vehicle with a rearward view; an extension arm mounted to a vehicle and moveably attached to the reflective element assembly; and a low friction bearing interposed between the mounting frame and the extension arm for facilitating movement of the reflective element relative to the extension arm. 
   In a further aspect, the invention relates to a vehicular rearview mirror assembly, comprising: a base assembly comprising a base frame for mounting the rearview mirror assembly to a vehicle; at least one support arm for supporting a reflective element and moveably connected to the base frame for selectively folding the reflective element against the vehicle and extending the reflective element away from the vehicle; and a low friction bearing interposed between the base frame and the at least one support arm for facilitating movement of the reflective element relative to the vehicle. 
   In yet another aspect, the invention relates to a vehicular rearview mirror assembly, comprising: a base assembly comprising a base frame for mounting the rearview mirror assembly to a vehicle; at least one support arm for supporting a reflective element and pivotably connected to the base frame for selectively folding the reflective element against the vehicle and extending the reflective element away from the vehicle; and a pair of parallel spaced-apart flanges, wherein the at least one support arm is interposed between the parallel flanges to form the pivot connection. 
   Various embodiments of the invention are also contemplated. For example, the low friction bearing can comprise a ball bearing. The low friction bearing can comprise a roller bearing. The reflective element can further comprise a mounting frame attached to the reflective element, and the base assembly can further comprise at least one arm moveably connected to the mounting frame, and the low friction bearing is interposed between the at least one arm and the mounting frame for facilitating the movement of the mounting frame relative to the base assembly. The base assembly can further comprise at least one arm moveably connected to the base frame and the low friction bearing is interposed between the at least one arm and the base frame for facilitating the movement of the at least one arm relative to the base frame. 
   The moveable connection can comprise a pivot connection, the base frame can comprise parallel spaced-apart flanges, and the at least one arm is interposed between the parallel flanges to form the pivot connection. The low friction bearing can be interposed between the at least one arm and the parallel flanges. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  is a front perspective view of a mirror assembly according to the invention. 
       FIG. 2  is a rear perspective view of the mirror assembly shown in  FIG. 1 . 
       FIG. 3  is a front perspective view of the interior components of the mirror assembly shown in  FIG. 1 . 
       FIG. 4  is a rear perspective view of the interior components of the mirror assembly shown in  FIG. 2 . 
       FIG. 5  is an exploded view of the interior components of the mirror assembly shown in  FIG. 3 . 
       FIG. 6  is a close-up view of a ball bearing race comprising a portion of a mirror extension assembly according to the invention. 
       FIG. 7  is a perspective view of the underside of a support arm comprising a portion of a mirror extension assembly according to the invention. 
       FIG. 8  is a perspective view of a portion of a mirror extension assembly comprising the ball bearing race shown in  FIG. 6  and the support arm shown in  FIG. 7 . 
       FIG. 9  is a perspective view of a support frame adapted to translate along the support arm shown in  FIG. 8 . 
       FIG. 10  is a sectional view taken along line  10 - 10  of  FIG. 1 . 
       FIG. 11  is a perspective view of a portion of a pivot assembly comprising a pivot actuator and a ring race according to the invention. 
       FIG. 12  is an exploded view of a portion of a pivot assembly comprising a pivot actuator, a ring race, a ring block, and a pivot pin. 
       FIG. 13  is a sectional view taken along line  13 - 13  of  FIG. 3 . 
       FIG. 14  is a partial exploded view of the support arm and a support base showing a pivot connection according to the invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the figures, and particularly to  FIGS. 1-4 , a rearview mirror assembly  10  comprises a base housing  12  enclosing a base assembly  18  and a mirror housing  14  enclosing a reflective element assembly  16  comprising a reflective element  24 . The rearview mirror assembly  10  is attached through the base assembly  18  to the exterior of a motor vehicle (not shown) in a well-known manner for providing an operator of the motor vehicle with a rearward view. The reflective element assembly  16  is attached to the base assembly  18  through a pivot assembly  20  for selectively folding the mirror against the motor vehicle. 
   As shown in  FIG. 3 , the base assembly  18  comprises a base frame  26  which is rigidly attached to the side of the motor vehicle. The reflective element assembly  16  comprises a mounting frame  22  for supporting elements of the rearview mirror assembly  10  such as a tilt actuator assembly  28  for adjusting the vertical and horizontal inclination of the reflective element  24 , the mirror housing  14 , external lights, such as puddle lights (not shown), and associated electrical wiring (not shown). The tilt actuator assembly  28 , the reflective element  24 , and the mirror housing  12 ,  14  are well-known and will not be described herein except where necessary for an adequate understanding of the invention. 
   As shown in  FIGS. 4 and 9 , the mounting frame  22  is an elongated, irregularly-shaped member comprising a rear frame element  30  and a front frame element  32 . The rear frame element  30  is a somewhat rectilinear piece comprising a rear wall  160  terminating in an upper wall  162  and a lower wall  166  in parallel, spaced-apart juxtaposition extending orthogonally from the rear wall  160 , an upper front wall  164  and a lower front wall  168  in coplanar, spaced-apart juxtaposition extending orthogonally inwardly from the upper wall  162  and the lower wall  166 , respectively and parallel to the rear wall  160 . The upper portion of the rear wall  168  and the upper front wall  164  define a rectilinear upper bearing block chamber  172 . The lower portion of the rear wall  168  and the lower front wall  168  define a rectilinear lower bearing block chamber  174 . 
   The front frame element  32  is a somewhat rectilinear piece adapted for mating communication with the rear frame element  30 . When assembled, the front frame element  32  and the rear frame element  30  together define an elongated, rectilinear arm chamber  170 . Preferably, the front frame element  32  and the rear frame element  30  are fabricated of a structural plastic having sufficient strength and rigidity for the purposes described herein. 
   Referring now to  FIGS. 5-8 , an extension arm  34  is an elongated, generally rectilinear member having a cantilever end  36  and a pivot end  38 . Intermediate the cantilever end  36  and the pivot end  38  is a center portion comprising a top wall  40 , and a front sidewall  42  and a rear sidewall  44  in parallel, spaced-apart juxtaposition depending orthogonally from the top wall  40 . An elongated rib  46  having a generally triangular-shaped cross-section extends upwardly from the top wall  40  parallel to the longitudinal axis of the extension arm  34 . Intermediate the rib  46  and the cantilever end  36  is a gap  48  extending through the top wall  40 . 
   A first arcuate wall  64  extends from the front sidewall  42  and transitions to a second arcuate wall  66  at the pivot end  38 . The arcuate walls  64 ,  66  enclose an annular wall  68  depending orthogonally from the top wall  40  and, with the top wall  40 , defining a cylindrical pivot actuator chamber  76 . Extending radially outwardly from the arcuate wall  68  are a plurality of regularly-spaced radial ribs  74 . The portion of the top wall  40  circumscribing the annular wall  68  comprises a plurality of mounting apertures  72  therethrough and a plurality of interspaced bosses  86  surrounding a pin aperture  62 . Preferably, the extension arm  34  is fabricated of a structural plastic having sufficient strength and rigidity for the purposes described herein. 
   Referring specifically to  FIGS. 5 and 6 , a frictionless bearing assembly is illustrated as comprising an upper ball bearing assembly  51 , which comprises an upper ball bearing race  50  and an upper bearing block  82 . The upper ball bearing race  50  comprises an elongated, rectilinear member having a truncated triangular cross-section, and a first inclined face  78  and a second inclined face  80  preferably oriented at 90° to one another. An elongated, oval-shaped upper ball bearing raceway  52  is cut into each inclined face  78 ,  80  and adapted to receive a plurality of recirculating ball bearings  54 . A lower ball bearing assembly  57  comprises lower ball bearing race  56  and a lower bearing block  84 . The lower ball bearing race  56  comprises an elongated, rectilinear member identical to the upper ball bearing race  50 , and a lower ball bearing raceway  58  containing a plurality of recirculating ball bearings  60 . The upper ball bearing race  50  is fixedly inserted into the gap  48  in cooperative, collinear alignment with the rib  46 , as shown in  FIG. 8 . The lower ball bearing race  56  is similarly fixedly attached to a lower rib mount along the underside of the extension arm  34 , as shown in  FIG. 8 . 
   The upper bearing block  82  is an elongated, rectilinear member defining a truncated triangular channel  83  adapted for cooperative, slidable communication with the upper ball bearing race  50 . The lower bearing block  84  is an elongated, rectilinear member identical to the upper bearing block  82  defining a truncated triangular channel  85  adapted for cooperative, slidable communication with the lower ball bearing race  56 . The upper bearing block  82  is further adapted to be received in the upper bearing block chamber  172 , and the lower bearing block  84  is adapted to be received in the lower bearing block chamber  174 . The bearing blocks  82 ,  84  are fixedly retained in the bearing block chambers  172 ,  174  through a suitable attachment such as a snap-fit attachment, an adhesive, pins, or threaded fasteners. The upper ball bearing race  50 , the lower ball bearing race  56 , the upper bearing block  82 , and the lower bearing block  84  are fabricated of a material having suitable strength and abrasion resistance for the purposes described herein, such as aluminum or a high strength plastic. 
   The extension arm  34  and the mounting frame  22  are adapted so that the cantilever end  36  can be inserted into the arm chamber  170  with the upper ball bearing race  50  in slidable communication with the upper bearing block channel  83  and the lower ball bearing race  56  in slidable communication with the lower bearing block channel  85 . A conventional extension actuator  150 , shown in  FIG. 5 , is attached to the extension arm  34  in a conventional manner. An extension nut housing  154  containing an extension nut  152  adapted for threaded communication with the extension actuator  150  is attached to the mounting frame  22  so that activation of the extension actuator  150  will drive the mounting frame  22  in linear, arcuate, or other selected ranges of motion relative to the extension arm  34 , with the ball bearing races  50 ,  56  traveling along the bearing block channels  83 ,  85 , respectively. 
   While the frictionless bearing assembly has been illustrated in  FIGS. 5 and 6  as comprising a ball bearing assembly, it will be evident to a person of ordinary skill in the art that alternate bearings, such as a roller bearing assembly, can also be utilized. 
   Referring now to  FIGS. 5 , and  11 - 13 , a pivot actuator  90 , as disclosed in U.S. Pat. No. 6,213,609, assigned to the assignee of the current application and incorporated herein by reference, comprises a generally cylindrical, hollow base housing  92 , a generally circular base plate  93 , and a generally cylindrical, hollow rotating annular shell  94 . The base housing  92  comprises an annular shoulder  91  at an upper portion thereof, and is adapted to slidably communicate with the annular shell  94 , as shown in  FIG. 13 . The base portion  92  is also provided at a lower circumferential portion thereof with a ring boss  114 . The base plate  93  is provided with a plurality of mounting apertures (not shown) for mounting the base plate  93  to the base frame  26 . The base housing  92  and the base plate  93  are adapted for mating cooperation and are fixedly connected, such as by a snap-fit mechanism, welding, or threaded or pin-type fasteners (not shown), to form a chamber  136  for enclosing the rotating annular shell  94 . 
   The rotating annular shell  94  comprises an annular shoulder  99  at an intermediate portion thereof, and terminates in an annular upper wall  88  provided with a plurality of regularly-spaced mounting apertures  96  therethrough. The upper wall  88  is castellated with a plurality of regularly-spaced slots  98 , and comprises a pin aperture  100  extending coaxially therethrough. As shown in  FIG. 13 , the rotating annular shell  94  is slidably retained in the chamber  136 , and encloses a drive motor  134  for rotating the rotating shell  94  relative to the base portion  92 . 
   An annular ramp  89  comprises an annular ring-like body adapted for slidable communication with the upper exterior of the rotating shell  94  and the upper interior of the base housing  92 . A helical spring  87 , such as a well-known wave spring, is adapted to encircle the upper exterior of the rotating shell  94  between the annular shoulder  99  and the annular ramp  89 , as shown in  FIG. 13 . 
   A frictionless bearing assembly is illustrated as comprising a roller bearing assembly  101 , which comprises a ring race  102  and a ring block  118 . The ring race  102  is an annular body comprising a circumferential conical face  108  and an annular face  110  defining a truncated cone. The conical face  108  is provided with a plurality of regularly-spaced roller bearing seats  104  adapted to seat a plurality of conventional roller bearings  106 . The annular face  110  defines a base aperture  113  adapted to slidably receive the base portion  92  therethrough, and is provided with at least one inner slot  112  adapted to slidably communicate with the ring boss  114  to prevent rotation of the ring race  102  relative to the base portion  92 . In the preferred embodiment, the roller bearings  106  are fabricated of high-strength structural plastichaving a high surface hardness, such as nylon, polyester, or PBT. It will be evident to a person of ordinary skill in the art that a ball bearing assembly can be utilized as an alternate frictionless bearing in place of the roller bearing assembly described herein. 
   The ring block  118  comprises an annular body having an inner annular wall  120  defining a base aperture  125  and transitioning to a conical face  124  at a lower portion thereof. The upper portion of the ring block  118  is castellated to define a plurality of regularly-spaced radial slots  122 . The base aperture  125  is adapted to be slidably received over the annular wall  68  of the extension arm  34 . The conical face  124  is adapted for cooperative juxtaposition with the conical face  108  and contact with the roller bearings  106 . The radial slots  122  are adapted to slidably communicate with the radial ribs  74  so that the ring block  118  is urged to rotate with the extension arm  34 . 
   Referring again to  FIGS. 7 ,  12 , and  13 , the pivot actuator  90  is assembled to the extension arm  34  by inserting the ring block  118  into the pivot end  38  of the extension arm  34  so that the ring block  118  encircles the annular wall  68  and the radial ribs  74  are received within the radial slots  122 . The pivot actuator  90  with the ring race  102  slidably received thereover is inserted into the pivot actuator chamber  76  so that the upper surface  88  is brought into proximity to the top wall  70 , the mounting apertures  96  are aligned with the mounting apertures  72 , and the bosses  86  are received in the slots  98 . The ring race  102  will be positioned toward the ring block  118  so that the roller bearings  106  will contact the conical face  124 . The pivot actuator  90  and the extension arm  34  are adapted so that a slight gap  123  between the top wall  70  and the upper wall  88  will remain when the pivot actuator  90  is inserted into the pivot actuator chamber  76 . The pivot actuator  90  is then secured to the extension arm  34  preferably by suitable threaded fasteners  97  threaded into the apertures  72 ,  96 . As the fasteners  97  are tightened, the upper wall  88  will be drawn toward the top wall  70 , thereby closing the gap  123  and drawing the shoulder  99  toward the shoulder  91  against the force of the spring  87 . The roller bearings  106  will be pressed into contact with the conical face  124  against the force of the spring  87 , which will tend to coaxially align the ring race  102  with the ring block  118 . The extension arm  34  can then rotate with the rotating ring  94  relative to the base portion  92 . 
   Referring to  FIGS. 3 ,  5 ,  11 ,  12 , and  14 , a pivot pin  126  comprises a circular top flange  128  in coaxial alignment with a cylindrical shaft  130  rigidly attached thereto. The base frame  26  comprises a plate-like extension arm flange  140  and a plate-like pivot actuator support flange  142  in parallel, spaced-apart juxtaposition for slidable insertion of the pivot end  38  of the extension arm  34  therebetween. The extension arm flange  140  is provided with a pivot aperture  144  coaxially therethrough. The pivot actuator support flange  142  is provided with a plurality of mounting apertures  146  therethrough adapted for cooperative alignment with mating apertures (not shown) in the base portion  92  of the pivot actuator  90 . The pivot actuator  90  is attached to the pivot actuator support flange  142  through suitable fasteners, such as threaded screws, inserted through the mounting apertures  146  into mating apertures (not shown) in the base portion  92 . As so assembled, the pin aperture  62  in the extension arm  34 , the pivot aperture  144  in the extension arm flange  140 , and the pin aperture  100  in the rotating ring  94  will be coaxially aligned, as shown in  FIG. 13 . The cylindrical shaft  130  of the pivot pin  126  is adapted for an interference fit in the pivot aperture  144  and a slidable fit in the apertures  62 ,  100  so that the pin will be retained in the pivot aperture  144  and will accommodate the rotation of the extension arm  34  and the rotating ring  94 . 
   The use of the frictionless ball bearing assemblies  51 ,  57  between the extension arm  34  and the mounting frame  22  enable the extension arm  34  and the mounting frame  22  to be tightly fit together while providing for slidable movement between the two parts. The enhanced slidability between the extension arm  34  and the mounting frame  22  enables a smaller, lighter extension actuator to be used. The close fit between the two parts reduces the potential for unwanted relative movement. 
   Similarly, the use of the frictionless roller bearing assembly  101  in the pivot assembly  20  enables a tight fit between the extension arm  34  and the base frame  26 , while enabling unrestricted pivoting of the extension arm  34 . The enhanced pivotability between the extension arm  34  and the base frame  26  enables a smaller, lighter pivot actuator to be used. The close fit between the two parts increases the strength of the pivot assembly  20  even when the mirror is fully extended, reduces the development of a precession-type movement of the pivot end  38  relative to the base frame  26 , and reduces the potential for unwanted relative movement of the extension arm  34  as a result of torsional forces as well as static and dynamic loading. The use of the extension arm flange  140  in the pivot assembly  20  with the pivot pin  126  securing the extension arm  34  to the base frame  26  also strengthens the pivot assembly  20  and reduces the potential for unwanted relative movement between the extension arm  34  and the base frame  26 . The use of the ball bearing assemblies  51 ,  57  also enables the use of closer tolerance components. 
   While particular embodiments of the invention have been shown, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. Reasonable variation and modification are possible within the scope of the foregoing disclosure of the invention without departing from the spirit of the invention.