Abstract:
A vehicle accessory and friction damper includes a rotatable member for rotating relative a stationary mount. The rotatable member includes a pivot axle including a circumferential arcuate channel. The stationary mount includes a cylindrical bearing for journaling the pivot axle. An O-ring is seated in the arcuate channel of the pivot axle and interposed between the pivot axle and the cylindrical bearing dampens rotation of the rotatable member relative to the stationary member, whereby the vehicle accessory moves from a first position to a second position in a controlled manner.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The invention generally relates to a motion damper. More specifically, this invention relates to a motion damper for use with vehicle accessories. 
     BACKGROUND 
     Damping devices are used on a variety of vehicle accessories such as console storage bins, glove boxes, slide-out trays and container holders, grab handles, door handles and coat hooks. For example, with console storage bins, which are often integrated into an overhead console, damping devices are typically incorporated into the pivot for a mounted door to provide a smooth, controlled opening action. Similarly, for spring-loaded slides such as those used in container holders or the like, a damping device is often used to control the slide motion as it is extended and retracted. Also, for grab handles, door handles and coat hooks, a damping device is often incorporated into the pivot for the handle or hook, whereby the pivoting motion is controlled and smooth as the handle or hook is extended and retracted. 
     A conventional damping device is a housing filled with a viscous damping fluid such as silicone, in which a paddle wheel on an axle is mounted with the axle extending from the housing and terminating in an external gear. The housing is typically secured to a structure mounting the movable feature, while a gear on the movable feature engages the gear on the axle of the viscous damping device to slow the movement of the movable feature. Although these damping devices provide the desired control, the devices typically require specific structure that adds to the expense of the vehicle accessory in a highly cost competitive environment. 
     Another difficulty with viscous damping devices for vehicle accessories is that performance changes with the wide range of temperature fluctuations encountered in the vehicle environment. For a viscous fluid, as the temperature decreases, viscosity increases dramatically. Correspondingly, as the temperature increases, the viscosity decreases. The result is an inconsistent feel to the vehicle accessory. Thus, viscous dampers used in present vehicle accessories provide a compromised performance at a premium price. 
     SUMMARY OF THE INVENTION 
     A friction damper for a vehicle accessory according to the invention includes an O-ring on a pivot axle of a rotatable member. The O-ring and pivot axle are received in abearing of a stationary mount. The O-ring is disposed between the pivot axle and the bearing for damping rotation of the rotatable member relative to the stationary member. In a variation of this embodiment, the pivot axle includes a circumferential arcuate channel for seating the O-ring. Alternatively, two or more O-rings can be used for damping rotation of the rotatable member relative to the stationary member. Further, the amount of damping can be varied by changing the fit between the pivot axle, O-ring and bearing. Also, different materials for the O-ring and bearing alter the amount of damping action. 
     In a further variation of the invention, the bearing is slidably received in the stationary mount, and includes a tab for reception in a slot in the stationary mount, whereby the bearing is blocked against rotation relative to the stationary mount. Further, the pivot axle may also be slidably received in the rotatable member for rotation therewith. 
     Also according to the invention, a vehicle accessory includes a rotatable member having a pivot axle, a stationary mount including a bearing for receiving the pivot axle, and a damper including an O-ring disposed between the pivot axle and the bearing for damping rotation of the rotatable member relative to the stationary mount. The rotatable member may, for example, be a grab handle in a vehicle interior. Preferably, the pivot axle includes a circumferential arcuate channel, and the O-ring is seated in the channel. Alternatively, two or more O-rings are disposed between the pivot axle and the bearing for damping rotation of the rotatable member relative to the stationary member. 
     In a variation of this embodiment, the bearing is slidably received in the stationary mount. Preferably, the bearing includes a tab for reception in a slot of the stationary mount, whereby the bearing is blocked against rotation relative to the stationary mount. Similarly, the pivot axle may also be slidably received in the rotatable member for rotation therewith. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various advantages of the present invention will become apparent to those skilled in the art after reading the following specification and by reference to the drawings in which: 
     FIG. 1 is a partial perspective view of a vehicle interior including a grab handle having a friction damper according to the invention; 
     FIG. 2 is a perspective assembly view of the friction damper of FIG. 1; 
     FIG. 3 is a sectional view of the friction damper of FIG. 1; 
     FIG. 4 is a cross-sectional view of an alternative embodiment of the friction damper according to the invention; 
     FIG. 5 is a cross-sectional view of a further embodiment of a friction damper according to the invention; 
     FIG. 6 is an exploded perspective view of yet another friction damper according to the invention; and 
     FIG. 7 is a cross-sectional view of the friction damper taken along section line  7 — 7  of FIG.  6 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the drawings, and in particular to FIGS. 1 and 2, a friction damper  10  according to the preferred embodiment of the present invention is shown. The friction damper  10  is depicted as being part of a vehicle accessory located within the interior of a motor vehicle. In this regard, the friction damper  10  may be connected to a suitable support structure, that is covered by a headliner  14 , by means of a stationary mount  20 . In addition, the friction damper  10  is also connected to a rotatable member  30  that forms part of the vehicle accessory as will be more fully discussed below. The vehicle accessory disclosed herein is a grab handle  32  which may be used in a conventional motor vehicle. However, the friction damper  10  may also be used in a wide variety of applications such as console storage-bin doors, glove box doors, slidable trays and container holders, interior and exterior handles, visors, coat hooks and other similar movable vehicle accessories. In addition, the headliner  14  may be formed from a suitable composite material covered by an upholstered fabric to conform to the interior of the vehicle. 
     The grab handle  32  includes a central hand grip portion  34  journaled at opposite ends within a cylindrical bearing of each stationary mount  20 . As shown more clearly in FIG. 2, each end of handle portion  34  includes a generally transversely extending pivot axle  40 , each including a damper ring  50 . The pivot axle  40  and damper ring  50  are received within cylindrical bearing of the stationary mount  20  for rotation therein. The damper ring  50  is at least slightly compressed between cylindrical wall  24  of the bearing and pivot axle  40  to retard the rotation of pivot axle  40  in stationary mount  20 . 
     As shown more clearly in FIG. 3, damper ring  50  is preferably an O-ring seated in an arcuate channel  42  disposed circumferentially on pivot axle  40 . The seated damper ring  50  is coaxial with pivot axle  40  and in contact with cylindrical bearing wall  24  of stationary mount  20 . The damper ring  50  is disposed between the outer diameter of pivot axle  40  and the cylinder bearing wall  24  to retard rotation of rotatable member  30  relative stationary mount  20 . The damper ring  50  is compressed by reducing the distance between pivot axle  40  and cylindrical bearing wall  24 , the more retarded the movement of rotatable member  30  relative stationary mount  20 . 
     The desired damping action resulting from the frictional interface between damper ring  50  and cylindrical bearing wall  24  can also be varied by including more than one damper ring  50 , as is shown in FIGS. 4 and 5. FIG. 4 depicts a pair of damper rings  50 , each seated in its own arcuate channel  42  formed circumferentially on the outer surface of pivot axle  40 , to increase the surface area of frictional interface within cylindrical bearing wall  24 . Similarly, FIG. 5 illustrates three damper rings  50  for further increasing the amount of frictional interface, and thus further retarding the rotation of rotatable member  30  relative stationary mount  20 . 
     The desired damping action from the frictional interface between damper ring  50  and cylindrical bearing wall  24  can also be varied by the properties of the particular materials chosen for cylindrical bearing wall  24  and damper ring  50 . Preferably, damper ring  50  is a silicone O-ring and cylindrical bearing wall  24  is made of nylon. Both of these materials are relatively self-lubricating, but can be replaced with drier materials such as a urethane O-ring or a styrene cylindrical bearing wall to variably increase the friction between damper ring  50  and cylindrical bearing wall  24 . Other self-lubricating and non-self-lubricating materials can also be used for damper ring  50  and cylindrical bearing wall  24 , as will be readily recognized by those of skill in the art. Accordingly, he desired damping action between rotatable member  30  and stationary mount  20  can be achieved by varying the space between the outer diameter of the pivot axle  40  and the inner diameter of the cylindrical bearing, changing the number of damper rings  50  employed, or selecting appropriate materials for both the damper ring  50  and the cylindrical bearing wall  24 . Significantly, the arrangement of damper ring  50  variably compressed between the pivot axle  40  of a rotatable member  30  and a cylindrical bearing wall  24  of a stationary mount  20  is relatively unaffected by environmental temperature variations. Rather, the amount of damping is directly related to fit, area of frictional interface, and materials. 
     An alternative embodiment of a friction damper according to the invention is shown in FIGS. 6 and 7. With reference to FIG. 6, a friction damper  60  includes a pivot axle  70  journaled in a cylindrical bearing  80 . Both bearing  80  and pivot axle  70  are keyed for connection to a stationary mount  90  and a rotatable member  100 , respectively. 
     More specifically, cylindrical bearing  80  includes an exterior housing  88  having a generally cylindrical shape and an outwardly extending tab  82 . Stationary mount  90  includes a complementary shaped opening  92  including a slot  94  keyed to receive tab  82  of cylindrical bearing  80 . Accordingly, after cylindrical bearing  80  is inserted into opening  92  of stationary mount  90 , it is prevented from rotation with pivot axle  70  by the reception of tab  82  in slot  94 . 
     The pivot axle  70  also includes a keyed tab  72  for reception in an opening  102  in rotatable member  100 . The tab  72  extends generally axially from an end of cylindrical pivot axle  70 . Opening  102  includes a keyed slot  104  extending axially inward of opening  102  for reception of tab  72  of pivot axle  70 . When opening  102  of rotatable member  100  receives pivot axle  70  and tab  72  is received in slot  104 , pivot axle  70  is fixed for rotation with rotatable member  100 . 
     Preferably, both cylindrical bearing  80  and pivot axle  70  are received in openings  92 ,  102  in stationary mount  90  and rotatable mount  100 , respectively, in a friction-fit manner. Alternatively, adhesive can be used to secure the respective parts to one another, or appropriate tolerances in the assembly of rotatable member  100  to stationary mount  90  can hold pivot axle  70  and cylindrical bearing  80  together. 
     With reference to FIG. 7, the assembly of pivot axle  70 , cylindrical bearing  80 , stationary mount  90 , and rotatable member  100  is more clearly shown. Specifically, pivot axle  70  includes a narrowed axle portion  74  for seating multiple damper rings I  10 . While three damper rings  110  are illustrated, more or fewer can be used depending on the desired damping action, as discussed above. Further, pivot axle  70  includes a flanged end  76  seated in a circumferential channel  84  at an end of cylindrical bearing  80 . As before, each damper ring  110  is at least slightly compressed between an inner cylindrical bearing wall  86  and circumferential arcuate channels  42  formed in pivot axle  70 . 
     Upon assembly of friction damper  60 , pivot axle  70  is journaled for rotation within cylindrical bearing  80 . Further, pivot axle  70  is locked for rotation with rotatable member  100  through reception of tab  72  of pivot axle  70  in slot  104  of opening  102 . Also, cylindrical bearing  80  is received within opening  92  of stationary mount  90 , including the reception of tab  82  of cylindrical bearing  80  in slot  94  of stationary mount  90  to prevent rotation of cylindrical  80  relative stationary mount  90 . 
     In either embodiment of the invention, friction damper  10 ,  60  dampens rotation of the rotatable member  30 ,  100  relative to stationary mount  20 ,  90 . The damping is varied by selection of materials for damper rings  50 ,  110  as well as cylindrical bearing wall  24 ,  86 . Further, the amount of damping is varied by the number of damper rings  50 ,  110  frictionally interposed between cylindrical bearing wall  24 ,  86  and pivot axle  40 ,  70 . Also, the space between cylindrical bearing wall  24 ,  86  and pivot axle  40 ,  70  filled by damper ring  50 ,  110  is variable to affect the amount of damping action. 
     While not shown, it is often preferred to include a spring for biasing the rotatable member  30 ,  100  in one direction. The invention described herein is simply modifiable to include a spring for biasing rotatable member  30 ,  100  in such a direction. The spring, of course, should provide a force greater than the damping resistance provided by the materials, fit, and number of damper rings included in the friction damper  10 ,  60 . 
     While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the spirit thereof