Abstract:
A floating bumper is provided for a drawer slide rear stop. The bumper has a slot for receiving a rear stop tab. The bumper slot is wider than the tab to permit slight side to side movement of the bumper when the drawer slide is fully retracted and to eliminate tension on the bumper. The rear stop tab has notches to accommodate projections formed within the bumper slot. The bumper projections fit loosely and do not engage the notches unless disengagement of the bumper from the rear stop is attempted. The peripheral edges as well as the slot edges of the bumper are chamfered.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an improved stop for a drawer slide and specifically to a floating bumper for stopping and holding a drawer slide in a closed position. 
     Individual drawer slides consist of two or more members, a stationary member and at least one telescoping member. The stationary member is typically mounted in a cabinet or desk, while the telescoping member is typically connected to a drawer which is to be extended and retracted from the cabinet or desk. Drawer slides are typically provided in pairs, one for each side of the drawer. A three member slide has an intermediate member engaged by means of roller bearings and bearing retainers with the stationary member and the drawer member to enable longer drawer extensions. 
     In two member and three member slides, the members are coupled to each other by means of ball bearings. These ball bearings are preferably fitted within a channel shaped bearing retainer located between the slide members. Bearing retainers are fitted between slide members, e.g. the inner and intermediate slide member and between the intermediate and outer slide member. Each slide member also has a channel shape comprising a central web and two bent leg portions extending longitudinally along opposite sides of the central web. 
     When the telescoping member(s) is fully extended, the drawer is at the limit of its travel from the space within the cabinet in which it is mounted. When the drawer is fully retracted, the telescoping member encounters a rear stop. Typically, the rear stop is formed by bending a selected portion of the web of the stationary member such that it extends into the channel defined by the stationary member. The stop is thus a tab extending from the outer member into the pathway of the inner slide member, and into the pathway of the intermediate and inner slide members in a three member slide. In the usual design, a rubber bumper is force fitted over the rear stop member. In such embodiment, the rubber bumper is slotted and pushed down over the tab. Typically the slot is narrower than the width of the tab, and the bumper has to be stretched in order to fit it onto the tab putting the bumper into constant tension. 
     The bumper functions in the following manner. In a three member slide, when the intermediate member slides within a stationary member to its retracted position, its movement stops when the web of the intermediate member strikes the rubber bumper. The inner sliding member continues its travel until it also encounters the rubber bumper. When the inner member encounters the rubber bumper, the inner surfaces of the inner member bent leg portions, bracketing a cutout portion of the inner member web, engage and slide past the sides of the rubber bumper thereby compressing it slightly. As the inner member is slid further, a bent flange portion of the web of the inner member on the front end of the inner member also comes to a stop against a front stop. As the inner member front flange portion comes to a stop, the inner member bent rear legs move past the bumper and a slight inward cant of the bent rear legs causes the inner member to be held in place until a positive extension force is again applied to the slide. This retention action holds the drawer in a closed position until the next subsequent extension. 
     The constant stretching and compressing of the rubber bumper while mounted on the stop member provides fatigue and causes the elasticity of the bumper to deteriorate. Consequently, the bumper cracks and ultimately fails. Since such bumpers are located at the rear end of slide on the stationary member, changing them is a problem after being mounted in a desk or cabinet. As such, there is a need for a rubber bumper for mounting on a stop member of a slide which has an enhanced operating life. 
     Moreover, when in a closed position, a significant section of the inner member rear end extends beyond the interior end of the ball retainer. The longer the slide, the longer the portion of the rear end of the inner member that extends beyond the retainer when the slide is in a closed position. Consequently, as the inner members slid rearwards to close the slide, the inner member rear portion may flex or bend slightly or be out of alignment. As a result, the inner member rear web may dig into the bumper and tend to cause the bumper to disengage from the rear stop tab as the inner member is slid back further. As such, there is a need for a bumper that will not disengage from the rear stop tab when a inner member accidentally contacts it. 
     SUMMARY OF THE INVENTION 
     In one aspect, the invention provides a bumper intended for use on a stop of a slide member, such as a rear stop formed in a stationary member of a drawer slide. The rear stop is a tab formed by bending a central portion of the web up into the channel defined by the stationary slide member. The bumper is fabricated of an elastomeric material in a generally flat configuration and has a central slot for receiving the stop tab. The slot in the bumper has a longitudinal dimension which is longer than the longitudinal dimension of the stop tab so that the bumper is not under tension when mounted on the tab. 
     In one embodiment, the stop tab has a notch formed on each of its vertical edges. Two projections formed inside the central slot of the bumper correspond to the notches on the tab to restrain the bumper from popping off the tab. Each interior projection in the slot has a length such that it penetrates into the space defined by each notch of the tab when the bumper is fitted in place over the stop tab. The projections approach, but do not engage the edges of the notches providing a loose fit. However, the length of the projections is such, that when attempting to disengage the bumper from the stop tab, the projections will engage the edges of the notches and thereby resist bumper disengagement. 
     To stiffen and prolong the life of the stop tab, the stop tab is sometimes supported by a gusset which is attached to the tab. To accommodate the gusset, a tubular passage is formed in the interior of the bumper extending upwardly into the slot. The tubular passage preferably extends through the bumper from one end to the other. The passage is larger than the gusset to provide a loose fit. 
     Preferably, the peripheral edges of the slot and the peripheral edges of the bumper are chamfered. When mounting the bumper on the tab, the chamfered slot edges engage and guide the tab into the slot. In case the inner slide member flexes or is misaligned, the bumper chamfered peripheral edge guides the inner member web over the bumper preventing bumper disengagement. 
     In another aspect, the invention provides a drawer slide assembly which comprises an outer slide member and an inner slide member slideably coupled to the outer slide member. The inner slide member has a web and a bent leg portion extending along each edge of the web defining a channel. A tab is located at the end of the outer slide member extending into the space defined by the channel. An elastomeric bumper having an upper and a lower end is mounted on the tab by means of a central slot extending through the bumper. When mounted on the tab, the slot length is wider than the tab permitting the bumper to “float” or slide from side to side on the tab and the legs of the inner slide member engage an outer surface of the bumper for slideably moving the bumper on the tab when the slide member is in a closed position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a drawer slide according to the prior art. 
     FIG. 2 is a rear end view of the stationary member of a typical prior art drawer slide having a rear stop tab and a bumper in cross section prior to mounting on the tab. 
     FIG. 3 is a top view of portion of the rear end of a typical prior art three member drawer slide. 
     FIG. 4 is a top view of a typical bumper used with the stop tab shown in FIG.  2 . 
     FIG. 5 is a front end elevation view of a drawer slide according to the prior art. 
     FIG. 6 is a rear end view of a stationary member having a rear stop tab for accommodating the bumper of the present invention. 
     FIG. 7A is a top view of the bumper according to the present invention. 
     FIG. 7B is a cross-sectional view of the bumper taken along lines  7 B— 7 B of FIG.  7 A. 
     FIG. 7C is a perspective view of the bumper according to the present invention. 
     FIG. 8 is an end view of the bumper of the present invention mounted over the rear stop tab of a two member slide. 
     FIG. 9 is an end view of the bumper of the present invention mounted over the rear stop tab of the intermediate member of a three member slide. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Drawer slides according to the prior art typically consist of a stationary member and one or more telescoping member. The stationary member is typically mounted on a cabinet while one of the telescoping member is connected to the drawer. A typical three drawer slide, for example, comprises a stationary channel-shaped member  10  (FIG.  1 ). An intermediate channel-shaped slide member  12  is coupled to slide within the “channel” of the stationary member  10 . An inner channel-shaped slide member  14  is coupled to slide within the “channel” of the intermediate member  12 . 
     In cross-section, the stationary member has web  16  having an upper and a lower end. A leg  18  extends from each end perpendicularly to the web  16  forming a channel. Each leg spans the length of the stationary member. A lip  20  is formed at the end of each leg and extends the length of the stationary member. The lip is formed by perpendicularly bending an end portion of each leg 90° toward the web. 
     The intermediate channel member  12  has a height that is smaller than the height of the outer channel member. The intermediate member also has a web  22  as well as a perpendicular leg  24  extending from each end of the web so as to form a channel. Each leg of the intermediate member is “S” shaped in cross-section so as to form an outer  26  and an inner  28  bearing raceway along its length. 
     The intermediate member is coupled to the channel of the stationary member via ball bearings  30 . These ball bearings ride on the inner surface of each of the stationary member legs and on the outer raceway formed on each of the intermediate member legs. The lip on each leg of the stationary member serves as a retainer wall for the ball bearings. The ball bearings are fitted within retainers  32  which are themselves retained by the lips  20 . 
     The inner channel-shaped sliding member has a height smaller than that of the intermediate member. The inner channel member is slidably mounted within the intermediate slide member. The legs  34  of the inner member are curved in cross-section having an outer concave bearing raceway  36  and an inner concave surface  38 . These legs also extend perpendicularly from a web  39 . 
     The inner member is coupled to the intermediate member using ball bearings  40 . These ball bearings are preferably fitted within a channel-shaped retainer  42  which is fitted between the inner and intermediate slide members. The ball bearings between the intermediate and inner members ride on the inner bearing raceways formed on the legs of the intermediate member and on the outer raceways formed on the inner member legs. 
     A rear stop element is located at the rear end of the stationary slide member (FIG.  2 ). The rear stop is formed by bending a central portion of the web  16  such that it extends into channel defined by the stationary slide member. As shown, the rear stop member is a tab  44  extending up and into the pathways of the intermediate and inner slide members (FIGS.  2  and  3 ). An elastomeric bumper  46  having a central slot  48  is shown above the tab  44  prior to its being mounted on the tab. As shown, slot  48  is narrower than the width of tab  44  requiring the bumper and slot to be stretched and tensioned and force fitted over the tab. Bumper  46  is forced over the rear stop member such that it encloses the stop member except at its open ends (FIG.  4 ). The slot  48  extends through the body of the bumper  46  from its top end to its bottom end. Since the slot  48  is narrower than the width of the stop member, this causes the bumper to be stretched when placed on the tab. A circular recess  50  is formed in the center of the bumper intersecting the slot. The bumper outer surface is defined by three intersecting cylindrical sections having their centers aligned along the plane of the slot, two end cylindrical sections  52  and a center cylindrical section  54 . 
     A second stop member  56  is located on the stationary member at the front end of the slide (FIG.  5 ). A bent flange portion  58  of the web  39  of the inner member extends upwardly into the channel defined by the inner member legs  34 . The flange portion  58  is bent inward at a 90° angle and is longer than the depth of the inner member legs channel and extends to the point where it overlaps a substantial portion of stop member  56 . When the inner member is retracted to the closed position, the bent flange  58  engages the stop member  56  to stop travel of the inner member. 
     When fitted over the rear stop member, the overall dimension  60  of the bumper is slightly longer than the shortest distance between the inner surfaces of the legs  34  of the inner member. In the usual configuration, a section of the web of the inner member at its rear end is cutout or relieved such that the two inner member legs extend beyond the end of the web. The portions of the legs  62  extending beyond the cutout  63  are squeezed or bent toward each other a small distance such that the distance between the interior surface of each leg at the rear end of the inner member is shorter than dimension  60  of the stop member. The cutout  63  facilitates the bending of the ends without buckling the web. 
     The bumper according to the present invention preferably has the same outer dimensions as the bumpers described in the background of the invention herein (as shown in FIG.  4 ). Tab  44  is provided with a cutout or notch  70  along each of its side edges. While a notch on one of the side edges of the tab is sufficient, a cutout  70  on each side edge is preferred. Each cutout  70  preferably has a horizontal upper edge  72  and a tapering lower edge  74 . While tab  44  is shown as being located on the inner slide member, in alternative embodiments, the tab is located on the outer slide member in one embodiment and an intermediate slide member in a second embodiment. In each case, the self centering bumper according to the present invention is mounted on the tab. 
     The bumper of the present invention has a slot  76  to receive the rear stop tab. The slot has a length  78 , width  80  and height  82  dimension (FIGS. 7A,  7 B). The slot extends through the bumper from top to bottom. A projection  84  is formed in each interior side wall of the slot and projects within the slot, i.e. along the length or longitudinal dimension. Each projection is designed to extend into notches  70  when the bumper is in place. It is preferred that the bumper has a projection for each notch formed on the stop tab. Therefore, if the stop tab has a cutout  70  on each of its side edges, it is preferable that a projection  84  is provided on each side edge of the slot. 
     All of the edges  86 ,  87  of the slot on the upper and lower end of the bumper are chamfered (FIGS.  7 A and  7 B). Chamfering of the slot edges facilitates the installation of the bumper on the rear stop tab. The chamfered slot edge  86  serves as a guide causing the bumper slot to align and slide over the tab during installation. It is preferable that the slot edges at both bumper ends are chamfered so as to facilitate insertion of either end of the bumper onto the tab. 
     The bumper perimeter edges  88  are also chamfered. In this regard, if the inner member inclines toward or bears against the outer or intermediate member when approaching a closed position, the inner member web rear end comes into contact with the chamfered edge  88 . As a result, the chamfer in the edge guides the web over the bumper, thereby, preventing the web from digging into the bumper and lifting the tab. It is preferred that all peripheral edges on the bumper be chamfered to facilitate mounting the bumper from either end. 
     Making the bumper orientation neutral provides a big advantage in that the person mounting the bumper on the rear stop tab will not have to worry about the bumper orientation relative to the tab. In an automated process of mounting the bumper to the tab, an orientation neutral bumper simplifies the operation. 
     In many slides the rear stop tab fails prematurely by breaking off. To prolong the life to the tab, a gusset  90  is typically attached to the rear surface of the tab  44  (FIG.  6 ). Because the slides which incorporate the inventive bumpers are generally the same as the slides of the prior art, the components of the slides incorporating the inventive bumpers are not described herein since they have already been described in relation to the prior art. Moreover, for convenience, the reference numerals used on the slide components of the slide members shown in FIGS. 6,  8  and  9  incorporating the inventive bumpers are the same as the reference numerals used for the same components on the prior art slide members disclosed in FIGS. 1-5. The gusset typically extends from the base  92  of the tab to a level  93  above the tab mid-height. Preferably, the gusset is attached along the center of the tab. To accommodate the gusset, an opening  94  is formed in the bumper (FIGS. 7A,  7 B and  7 C). The opening intersects the slot. To make the bumper orientation neutral however, a cylindrical opening is formed spanning the entire height of the bumper i.e., from the bumper upper end to the bumper lower end. The diameter of the opening is such that when the bumper is mounted on the tab, the gusset does not exert any pressure on the bumper. This freedom to move from side to side enables the bumper to center itself between the legs of the engaging slide member. 
     The length dimension  78  of the slot is specifically configured to be greater than the maximum dimension  96  of the stop tab to eliminate any tension on the bumper when mounted and allow the bumper to move from side to side on the tab during extension and retraction of the slide inner member. 
     The length  98  of the projection  84  is such that when the bumper is mounted over the stop member, each projection extends into the space defined by each cutout  70  (i.e. notch) on the stop tab without contacting the notches (FIG.  8 ). When attempting to disengage the bumper from the stop tab, the projections engage the upper edges  72  of the cutouts and resist the disengagement. 
     The function of the floating bumper of the present invention remains the same as in the prior art. As the inner slide member is retracted, the rear end  62  of the legs of the inner member which are slightly canted inwardly engage and compress the rubber bumper (FIG.  9 ). As the inner member is slid farther backwards, the canted portions of the bent legs move past the rear bumper allowing the bumper to expand and retain the slide and drawer in a closed position. The retention force in the closed position is determined by the bumper shape and composition. Thus, manufacturing variations in dimensions of mounting tabs do not affect retention force as in prior art. 
     The relative dimensions of the tab and slot are chosen in order to permit the bumper to slide from side to side when engaged by the inner slide member to center itself between the bent legs of the inner member thereby reducing the wear and tear normally encountered by a prior art force fitted bumper and significantly extending the bumper life. As can be seen from FIG. 8, when the bumper is mounted over the stop member, it is a “floating bumper,” i.e., it is not being stretched by the rear stop tab. 
     The retention force for bumpers of other shape and design can also benefit from this “floating bumper,” concept and though not illustrated, will be understood by others skilled in the art. Likewise, those skilled in the art can easily see other common mounting arrangements, such as mounting the “floating bumper” on the inner member and engaging with formed up tabs from the outer member.