Patent Abstract:
An exterior rear view mirror for a motor vehicle of the breakaway design is disclosed which a mirror support member having a one piece integrally formed clamp mechanism for securing the mirror housing to the pivot post and in which the clamping pressure may be easily and conveniently adjusted without requiring removal of the mirror or its outer housing.

Full Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates generally to exterior rear view mirror assemblies and more specifically to such mirror assemblies of the so called breakaway design. 
     In recent years, motor vehicle manufacturers have incorporated exterior mirror assemblies in which the mirror is movably supported within a housing and the housing is pivotably supported on an upstanding post forming a part of a supporting base which base is in turn secured to the motor vehicle. Such designs offer significant advantages over prior exterior mirrors in that the housing protects the mirror from being bumped and moved out of adjustment by passerbys and the pivotable mounting allows the housing to fold backwardly or forwardly in the event it encounters an obstacle thus preventing damage to the mirror assembly. Typically, a spring loaded detent assembly is incorporated between the mirror housing and supporting base to retain the mirror in an operative position. 
     In order to inhibit any vibrational movement of the mirror assembly, it is important that the pivotable connection between the mirror housing (to which the mirror is secured) and the upstanding post of the supporting base be subjected to a predetermined desired claiming force. A typical manner of providing this clamping force has been to provide a semicircular seat on the mirror housing and a separate strap which is then secured to the mirror housing in overlying relationship to the upstanding post. Suitable threaded fasteners are normally used at opposite ends of the strap to secure it to the housing. While this arrangement provides a satisfactory clamping force when new, there is a tendency for the fasteners to loosen over time due to vibration, temperature cycling and the like. Because the fasteners securing the strap to the housing are generally concealed by an outer case and/or the mirror itself, tightening of the fasteners becomes a difficult and time consuming process requiring removal of the outer case and/or mirror itself. Additionally, the prior clamping arrangement is relatively costly in terms of assembling in that it requires separate fabrication, handling and installation of the strap and plurality of fasteners. 
     The present invention, however, overcomes the disadvantages of the prior clamping arrangement while still providing a strong, reliable, easily adjusted breakaway-type mounting arrangement for the mirror assembly. In the present invention, the fasteners utilized to provide the required clamping force are positioned within the outer case such that they are easily and conveniently accessible by merely tilting the mirror to an extreme inboard position. Once the fasteners have been adjusted, the mirror may be easily tilted back to its normal operative position in which the fasteners are substantially concealed thereby maintaining the aesthetically pleasing clean lines of the mirror assembly. Additionally, the clamping structure of the present invention is integrally formed with the mirror support frame thus eliminating the need to separately fabricate and assemble a strap member. Rather, only a suitable number of fasteners need be assembled to the support frame and tightened to the desired degree to secure the mirror housing to the upstanding post of the bracket frame. Thus, the mirror assembly of the present invention provides a breakaway mounting arrangement which offers the advantage of grater ease of serviceability while also incorporating a more efficient, less costly clamping arrangement while preserving the smooth aesthetically pleasing appearance and durability of the mirror assembly. 
     Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an exterior mirror assembly shown in operative installed relationship to a motor vehicle all in accordance with the present invention; 
     FIG. 2 is a fragmentary section view of the mirror assembly of FIG. 1, the section being taken along line 2--2 thereof; 
     FIG. 3 is a fragmentary view similar to that of FIG. 2 but with the section taken at a location passing through one of the clamping fasteners; 
     FIG. 4 is a fragmentary section view of the mirror assembly of FIG. 3, the section line being taken along line 4--4 thereof; 
     FIG. 5 is a fragmentary elevational view of the mirror assembly with the outer shell removed therefrom as seen looking forwardly from a rear position with respect to the motor vehicle, all in accordance with the present invention; 
     FIG. 6 is a fragmentary view of the mirror assembly of FIG. 3 as seen looking in the direction of arrow 6 shown in FIG. 3; and 
     FIG. 7 is a fragmentary elevational view of the mirror assembly shown in FIGS. 1-3 with portions of the outer shell broken away. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings and more specifically to FIG. 1, an exterior mirror assembly in accordance with the present invention indicated generally at 10 is shown in installed relationship to the door 12 of a motor vehicle. Mirror assembly 10 includes a mirror housing 14 within which a reflective mirror 16 is movably supported and a bracket frame 18 to which mirror housing 14 is pivotably mounted. As shown, bracket frame 18 includes a generally triangular shaped portion 20 by which mirror assembly 10 is secured to door 12 of a motor vehicle. A smoothly surfaced projection 22 extends outwardly from triangular shaped portion 20 of bracket frame 18 and defines a generally horizontal surface 24 from which a generally cylindrically shaped elongated pivot post 26 extends generally vertically upwardly. 
     Mirror housing 14 includes an outer casing 28 within which a mirror support frame 30 is disposed. As shown in FIGS. 2 and 3, mirror support frame 30 includes a main body portion 34 which is designed to pivotably support mirror 16 within housing 14 and may incorporate suitable mechanisms by which mirror 16 may be remotely positioned such as for example suitable remotely controlled electric drive motors. Additionally, other mechanisms may also be supported on frame 30 such as for example information display means, means for heating the mirror, etc. 
     Frame 30 also includes a laterally extending mounting portion 35 integrally formed therewith within which is defined an elongated generally cylindrically shaped opening 36 adapted to receive pivot post 26. A slotted opening 38 extends generally radially outwardly from opening 36 and has the outer end thereof closed off by end wall 40. A pair of threaded fasteners 42, 44 extend across slotted opening 38 intermediate its ends and serve to exert a clamping force between opposed sidewalls 46 and 48 thereof A plurality of reinforcing rigidifying ribs 50 are provided on frame 30 wrapping around portion 34 so as to lend sufficient strength thereto while maintaining a relatively lightweight, economical structure. As shown in FIG. 4, end wall 40 is relatively thin in section and does not include any reinforcing ribs extending across the exterior surface thereof. These features enable it to retain sufficient flexibility to accommodate the slight movement of walls 46 and 48 toward each other as fasteners 42 and 44 are tightened while also providing a limiting action limiting tensional forces exerted in the area where walls 46 and 48 join the portion defining cylindrical opening 36. Thus, as fasteners 42 and 44 are tightened the ends of walls 46 and 48 remote from interconnecting end wall 40 will converge thereby reducing the diameter of opening 36 and exerting the desired clamping action on upstanding post 26. 
     Outer casing 28 provides an aesthetically pleasing smoothly curved shell surrounding frame 30 and includes provisions (not shown) to enable it to be securely fastened to frame 30 in a conventional manner. Casing 28 includes a return flange portion 52 which extends around the periphery of and defines an opening 54 which is sized to accommodate mirror 16. Preferably, flange 52 will be positioned in closely spaced relationship to the peripheral edge of mirror 16 and will extend into the interior area defined by casing 28 sufficiently so as to conceal the interior area from view regardless of the positioning of mirror 16. As best seen with reference to FIGS. 3 and 6, flange 52 of casing 28 includes a pair of spaced cutout portions 56 and 58 which are positioned so as to afford access to respective fasteners 42 and 44 by means of a suitable tool such as screwdriver 60 when mirror 16 is tilted to an extreme inboard position such as is shown in phantom in FIGS. 2 and 3. It should be noted that the positioning of screws 42 and 44 as well as the size of cutout portions 56 and 58 is preferably selected such that the openings defined by cutouts 56 and 58 are substantially concealed from view when mirror 16 is in its normal operative position. 
     As may now be appreciated, the clamping structure of the present invention is well suited to accommodate convenient service access to the fasteners by which the mirror housing 14 is secured to upstanding post 26 without requiring substantial time consuming disassembly. In order to gain access to the clamping fasteners, all one need do is merely tilt mirror 16 to its extreme inboard position and insert the appropriate tool through the access openings. Not only does this serviceability feature facilitate tightening of the clamping arrangement when and if necessary, but it may also allow removal and replacement of mirror housing 14 without requiring removal of bracket frame 18 from the vehicle should such replacement be desired. 
     Additionally, the provision of a clamping arrangement which is integrally formed with the mirror support frame offers the advantages of a reduction in the number of parts required to be fabricated, stocked, handled and assembled while still maintaining a secure reliable clamping structure. Further, because this integral clamping structure requires the use of fasteners on only one lateral side thereof, it lends itself to use in providing the serviceability feature discussed above. Preferably, mirror support frame 30 will be manufactured from a suitable polymeric composition having a desired strength and resiliency such as by injection molding. However, it may also be possible to fabricate this component from metal or other suitable material as well. It should be noted that while the embodiment discussed above showed the use of two such fasteners in the clamping arrangement of the present invention, a greater or lesser number of such fasteners may be utilized in differing applications depending upon various factors such as the size of the mirror assembly being secured, the axial length of the mounting force and the maximum desired clamping force. 
     While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to provide the advantages and features above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

Technology Classification (CPC): 1