Abstract:
A pivoting exterior rearview mirror assembly comprises a mirror housing, a base, a support frame, a pivot assembly, and associated elements comprised primarily of a plastic or polymeric material. The pivot assembly is provided with a pivot reinforcement made of a relatively high-strength material, such as steel. The base is provided with a cantilever reinforcement made of a relatively high-strength material, such as steel. The reinforcing steel increases the load carrying capability of the plastic and reduces the potential material failure of unreinforced plastic.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. provisional application Ser. No. 60/481,237, filed Aug. 15, 2003, which is incorporated herein in its entirety. 

   FIELD OF THE INVENTION 
   The invention relates generally to exterior rearview mirrors for motor vehicles, and in particular to a pivotable cantilevered rearview mirror having reinforcing elements integrated into the pivot mechanism and cantilever arm. 
   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 and 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. Nos. 5,684,646 and 5,703,732, which are incorporated herein by reference. 
   Mirrors can be heavy, particularly larger mirrors used on pickup trucks and sport utility vehicles (SUVs), and mirrors incorporating enhanced functionality requiring additional electrical and/or mechanical components. At the same time, fuel economy considerations dictate that the mirror be as light as practical. This has led to an increased use of high-strength plastics for the various structural and operational elements comprising the mirror assembly. However, plastics cannot readily be used for certain structural elements due to unsatisfactory strength and/or performance characteristics, such as vibration resonance. 
   SUMMARY OF THE INVENTION 
   The invention relates to an exterior vehicle mirror system comprises a base having a mounting portion for mounting the mirror system to a vehicle, a reflective element assembly for providing an operator of the vehicle with a rearward view, a connection pivotally mounting the reflective element assembly to the base, and a reinforcing element aligned with the connection to distribute at least one of stresses and forces imposed on the vehicle mirror system to the base bracket along a stress path to enhance the strength of the connection. A reinforcing element is integrally molded with at least one of the base and the reflective element assembly in cooperative relationship with the connection. The reinforcing element is made of a material having a higher strength-to-weight ratio than the material comprising at least one of the base and the reflective element. The reinforcing element surrounds at least a portion of the connection. 
   The reinforcing element further comprises a surface, and the surface is in abutment with the base to resist deflection of the base due to forces imposed on the reflective element assembly. The reinforcing element comprises a first reinforcing element associated with the base and a second reinforcing element associated with the reflective element assembly. The first reinforcing element is vertically spaced from the second reinforcing element. 
   The first reinforcing element comprises a plate having a first end positioned beneath the connection and the second reinforcing element, and a second end extending from the first end and in abutment with the mounting portion of the base. The first reinforcing element is L-shaped between the first end and the second end. The L-shape of the first reinforcing element transfers at least one of forces, stresses, and moments within the vehicle mirror system from beneath the connection at the first end to the mounting portion adjacent to the second end thereof. 
   The reflective element assembly further comprises a recess which receives the second reinforcing element. The recess has a lower surface which forms a portion of the connection, and the second reinforcing element abuts the lower surface. The recess and the second reinforcing element each comprise a coaxially-aligned recess forming a portion of the connection. 
   The second reinforcing element includes a vertically-extending flange, and the vertically extending flange is in alignment with at least one axis of the reflective element assembly. 
   The second reinforcing element further comprises an annular portion surrounding the connection. A portion of the annular portion is integrally formed with the vertically-extending flange, whereby the vertically-extending flange is capable of transferring at least one of forces, stresses, and moments through the connection via the annular portion. At least one of the first and second reinforcing elements is made of metal. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a portion of a motor vehicle comprising an exterior rearview mirror assembly according to the invention. 
       FIG. 2  is an exploded view of the exterior rearview mirror assembly shown in  FIG. 1  illustrating a support frame incorporating a reinforcing pivot reinforcement and a base incorporating a cantilever reinforcement. 
       FIG. 3  is a perspective view of the support frame and the base shown in  FIG. 2  assembled with the pivot reinforcement and the cantilever reinforcement. 
       FIG. 4  is a first close up perspective view of the base shown in  FIG. 2  illustrating the cantilever reinforcement. 
       FIG. 5  is a second close up perspective view of the base shown in  FIG. 2  illustrating the cantilever reinforcement. 
       FIG. 6  is a third close up perspective view of the base shown in  FIG. 2  illustrating the cantilever reinforcement. 
       FIGS. 7A-C  are close up side and perspective views of the cantilever reinforcement shown in  FIG. 2 . 
       FIG. 8  is a perspective view of the mirror assembly shown in  FIG. 1  illustrating various forces and moments acting on the exterior rearview mirror assembly. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings, and to  FIG. 1  in particular, an exterior rearview mirror assembly  10  according to the invention is shown attached to a motor vehicle  12 . Referring also to  FIG. 2 , the mirror assembly  10  comprises a mirror housing  14  enclosing a base  16 , a support frame  18 , and a reflective element assembly  20 . The mirror assembly  10  will be recognized as a generally conventional rearview mirror assembly in many respects, except as otherwise described herein. 
   The reflective element assembly  20  comprises a well-known reflective element  22  mounted to a well-known glass case  24  and attached to the support frame  18 , preferably through a well-known tilt actuator assembly (not shown) enabling the reflective element  22  to be tilted about two orthogonal axes. The base  16  comprises a mounting frame  80  adapted for mounting the base  16  to the motor vehicle  12  in a well-known manner, and a support arm  26  extending outwardly therefrom. The support arm  26  comprises a lower portion of a pivot assembly  28  comprising a pivot post  82  for enabling the support frame  18  to pivot about the pivot post  82  relative to the base  16 . The support arm  26  is also provided with a support arm wall  84  extending outwardly from the mounting frame  80  and defining a generally vertical surface of the support arm  26 . Preferably, the base  16  is fabricated of a generally rigid, high-strength plastic through a conventional thermoforming process such as injection molding. 
   The support frame  18  is an irregularly shaped member adapted for pivotable attachment to the support arm  26  and support of the reflective element assembly  20 , and having a proximal end  50  and a distal end  54 . The distal end  54  is adapted for mounting of the reflective element assembly  20 . The proximal end  50  is adapted for pivotable attachment to the support arm  26  and has a recess portion comprising a pivot assembly housing  34  adapted for cooperative register with the pivot post  82 . Preferably, the support frame  18  is fabricated of a generally rigid, high-strength plastic through a conventional thermoforming process such as injection molding. 
   The pivot assembly housing  34  comprises a distal arcuate wall  36  and a proximal arcuate wall  38  defined by the same radius and lying along the same cylindrical surface. The distal arcuate wall  36  terminates in an arcuate distal upper rim  40 . The proximal arcuate wall  38  terminates in an arcuate proximal upper rim  42 . As shown in  FIG. 2 , the distal upper rim  40  is spaced away from the proximal upper rim  42  and transitions to the proximal upper rim  42  through an inclined arcuate edge  48  lying along the same cylindrical surface as the arcuate walls  36 ,  38 . The arcuate walls  36 ,  38  transition to an annular floor  44  extending radially inwardly therefrom and defining a pivot bore  46  extending axially through the annular floor  44  and adapted for slidable and rotational register with the pivot post  82 . 
   A first reinforcing element comprising a pivot reinforcement  30  is an annular body adapted for slidable register with the pivot assembly housing  34 . The pivot reinforcement  30  comprises a flange-like distal arcuate wall  60  and a proximal arcuate wall  62  defined by the same radius and lying along the same cylindrical surface. The distal arcuate wall  60  terminates in an arcuate distal upper rim  64 . The proximal arcuate wall  62  terminates in an arcuate proximal upper rim  66 . As shown in  FIG. 2 , the distal upper rim  64  is spaced away from the proximal upper rim  66  and transitions to the proximal upper rim  66  through an inclined arcuate edge  72  lying along the same cylindrical surface as the arcuate walls  60 ,  62 . The arcuate walls  60 ,  62  transition to an annular floor  68  extending radially inwardly therefrom and defining a pivot bore  70  extending axially through the annular floor  68  in cooperative register with the pivot bore  46 . The pivot reinforcement  30  is preferably fabricated of a material having a relatively higher strength, and preferably a higher strength-to-weight ratio, than the support frame  18  material, such as steel or aluminum. 
   Referring now to  FIGS. 4-7 , the base  16  incorporates a second reinforcing element comprising a cantilever reinforcement  32 , preferably integrated into the base  16  during the base  16  fabrication process. The cantilever reinforcement  32  is a generally L-shaped, thin, plate-like member, preferably fabricated of a material having a relatively higher strength, and preferably a higher strength-to-weight ratio, than the base  16  material, such as steel or aluminum. As shown in  FIGS. 7A-7C , the cantilever reinforcement  32  comprises a mounting frame leg  90  and a support arm leg  92  extending generally orthogonal from a lower portion thereof. A bend line  94  inclined relative to both the mounting frame leg  90  and the support arm leg  92  separates the mounting frame leg  90  and the support arm leg  92  and defines a line at which the support arm leg  92  is bent relative to the mounting frame leg  90 , as shown in  FIGS. 7B and 7C . 
   It will be understood that the particular geometry of the pivot reinforcement  30  and the cantilever reinforcement  32  is not critical to the scope of this invention and varying reinforcement structures and materials can be employed without departing from the scope of this invention. For example, the bend line  94  in the cantilever reinforcement  32  is not critical to the invention as the shape of the reinforcing components  30 ,  32  would be determined at least in part by the packaging and available space characteristics of a particular vehicular mirror implementation and is not required to have a particular shape to be in accordance with the invention. Further, various additional reinforcing characteristics (such as ribs, beads, etc.) can be provided to the reinforcing components  30 ,  32  without departing from the scope of the invention as well. 
   The mounting frame leg  90  comprises a thin section  96  having an upper edge  104  and a thick section  98  having a medial edge  102 , the thin section  96  transitioning to the thick section  98  through an inclined edge  106  joining the upper edge  104  and the medial edge  102 . The support arm leg  92  has a lateral edge  100  extending from and inclined relative to the medial edge  102 . 
   Referring specifically to  FIGS. 4-6 , the cantilever reinforcement  32  is incorporated into the base  16  so that the mounting frame leg  90  is encased within the mounting frame  80  and the support arm leg  92  extends along the support arm wall  84  in register therewith. As can be seen in  FIG. 6 , the support arm  26  is inclined relative to the mounting frame  80 . The cantilever reinforcement  32  is adapted so that the bend line  94  accommodates the inclination of the support arm  26  relative to the mounting frame  80 . The thick section  98  is configured and positioned in the base  16  to accommodate the high bending stresses in the area where the support arm  26  joins the mounting frame  80 , which are imposed by the weight of the support frame  18 , the reflective element assembly  20 , and other attached components, such as a tilt actuator assembly. It will be evident that the cantilever reinforcement  32  can be configured to accommodate a specific size and configuration of the base  16  and the stresses to which the support arm  26  and the mounting frame  80  are subject. 
   As illustrated in  FIGS. 2 ,  3 , and  8 , the pivot reinforcement  30  is preferably integrally molded into the pivot assembly housing  34  during the fabrication of the pivot assembly housing  34  so that the distal arcuate wall  60  is cooperatively aligned with the distal arcuate wall  36 , the proximal arcuate wall  38  is cooperatively aligned with the proximal arcuate wall  62 , and the upper rims  64 ,  66  are cooperatively aligned with the upper rims  40 ,  42 , respectively. Alternatively, the pivot reinforcement  30  can be fixedly attached to the pivot assembly housing  34  in a suitable manner, such as by welding, an interference fit, an adhesive, and the like, to prevent the movement of the pivot reinforcement  30  relative to the pivot assembly housing  34 . 
     FIG. 8  illustrates the various stresses and moments to which the mirror assembly  10 , the pivot reinforcement  30 , and the cantilever reinforcement  32  are subject. The weight of the mirror housing  14 , the base  16 , the support frame  18 , and the reflective element assembly  20  are represented by a mirror weight W acting downwardly through a center of mass C which defines a moment arm x relative to the pivot assembly  28 . The mirror weight W and the moment arm x define a weight moment M acting about the pivot assembly  28 . This weight moment M is resisted by a tensile force F T  and a compressive force F C  acting on the base  16 . The weight moment M generates an internal resisting moment M S  acting on the cantilever reinforcement  32  and a force F acting on the pivot reinforcement  30 . The reinforcing action of the cantilever reinforcement  32  and the pivot reinforcement  30  results in a stress path S P  that travels from the base  16  through the cantilever reinforcement  32  and the pivot reinforcement  30 . 
   The cantilever reinforcement  32  and the pivot reinforcement  30  carry the stress S P  without deformation or the increased probability of material failure that would be present in a pivot assembly and base composed entirely of plastic. The mirror assembly can be fabricated primarily of a plastic material, thereby reducing weight and cost, yet maintaining an adequate load-carrying capacity. 
   While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible within the scope of the foregoing description and drawings without departing from the spirit of the invention.