Abstract:
Disclosed is a light weight handle assembly adapted to transport a heavy duty container which may contain sensitive electronic components. The handle assembly of the present invention generally comprises a stationary bracket which mounts to a container wall and a movable handle pivotally connected to the bracket. The bracket is formed with an inner portion that is adapted to rotatably engage with a pair of pivoting arms extending from the movable handle so that the light weight handle may easily be assembled and disassembled. Each of the pivoting arms is formed with a movable stop member which is advantageously positioned to contact and bear against stationary stop members which are attached to or are a part of the container to which the handle is attached. The stationary stop members and movable stop members each have a substantially planar contact surface which is designed such that when the movable handle is pivoted to the lifting/operative position, the movable stop members are in contact with the at least one stationary stop member with less stress in the materials than in conventional handles. The lower stresses enable a strong handle to be made of plastic material such as polyethylene.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No. 60/071,448, filed Jan. 13, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to handles. More particularly, the invention relates to handles fastenable to a container and which provide a lightweight, yet strong and stable platform for carrying the container. 
     2. Prior Art 
     Handles of one kind or another have been manufactured and used for as long as there have been things to carry. In particular, container handles have experienced significant advances in design and manufacture over the years to provide hidden handles, handles that are maintained away from the container wall, handles which lock in various positions and spring loaded handles. While all of these handles are useful for their intended purposes, they have drawbacks of one kind or another such as excessive weight, excessive size, excessive expense and unacceptable generation of forces in particular areas which may not be desirable. One prior art handle provides significant reduction of stresses in the handle allowing lighter, less expensive materials to be used. This has been a great benefit to the art. Unfortunately, U.S. Pat. No. 5,461,755 is relatively large and can only be employed on larger containers. This is due in part to the size of the stationary bracket that holds the handle to the container. Reducing the size of the bracket and reconfiguring its function is the subject of this disclosure. 
     SUMMARY OF THE INVENTION 
     The above-discussed and other drawbacks and deficiencies of the prior art are overcome or alleviated by the lightweight stress reducing handle of the invention. 
     The handle of the invention is an extremely lightweight handle having a pre-engineered stress reducing construction in combination with handle stop capability which depends upon a feature of the container to which the handle is mounted while maintaining contact zones in stress reduced angles. The handle is even more lightweight and compact than the prior art and advantageously can be mounted on a small container as well as a large container. More particularly, the handle of the invention comprises a stationary bracket portion mountable to a wall of a container adjacent a portion of the container which provides a stop surface upon which the handle portion, pivotally mounted in said stationary bracket, may bear. The handle is engineered such that the contact plane between stop surfaces on the handle portion and the portion of the container acting as a stop surface will be approximately 45° to the mounting surface of the stationary bracket. Providing a cooperating surface designed to contact a feature of a container at a particular preset angle of about 45° significantly reduces stress in the handle and provides for substantially more longevity in the handle. Moreover, the reduced stress in the handle allows the use of cheaper, lighter and less structurally strong materials. Employing the 45° contact surface removes concern regarding the material of the container as well since the force acting thereon is significantly lower than it might otherwise be. 
     The handle of the invention is most preferably spring loaded and easily disassembled from a stationary bracket once such bracket is not attached to the container. 
     The above-discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings wherein like elements are numbered alike in the several FIGURES: 
     FIG. 1 is a front plan view of the handle of the invention mounted on a section of container wall; 
     FIG. 2 is a top plan view of the handle of the invention; 
     FIG. 3 is a bottom plan view of the handle of the invention; 
     FIG. 4 is a rear plan view of the handle of the invention; 
     FIG. 5 is a side view of the handle of the invention in the inoperative position; 
     FIG. 6 is a side view in the operative position; 
     FIG. 7 is a perspective view of the bail of the invention separated from the bracket; 
     FIG. 8 is a perspective view of the bracket of the invention separated from the bail; 
     FIG. 9 is a cross-section view of the invention taken along section line  9 — 9  in FIG. 4; 
     FIG. 10 is a perspective view of the handle of the invention attached to a section of container wall; 
     FIG. 11 is a perspective view of the torsion spring of the invention; and 
     FIG. 12 is a side elevation view of the handle of the invention in the raised position which includes exemplary measurements and force vectors for one particular example of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, the light weight handle assembly according to the present invention is illustrated. The handle assembly  10  generally comprises a stationary bracket  12  mounted to a container wall  14  which may be a wall of a roto-molded container or any other container. The handle assembly  10  further comprises a movable handle  16  which is pivotally connected to the stationary bracket  12 . When the stationary bracket  12  is connected to the container wall  14 , the movable handle  16  may be pivoted between an inoperative position (FIG. 5) and an operative position (FIG.  6 ). When the stationary bracket  12  is not attached to or is removed from the container wall  14 , the movable handle  16  may be easily removed from bracket  12 . Easy removal is facilitated by bracket  12  merely trapping a portion of handle  16  (disclosed hereunder) to container wall  14 . This feature of the present invention allows the handle assembly  10  to be quickly assembled or disassembled, thereby increasing production efficiency and reducing repair time, respectively. 
     To stabilize the handle assembly  10  while the container is being carried by the handle, there is provided at least one stationary stop member. Handle  16  also provides two moveable stop members located advantageously on pivoting arms (further discussed hereunder) which are to contact another structure (or structures). In the preferred embodiment this is a part of the container termed protuberance  17 . The movable stop members  22  and  24  and the protuberance  17  are adapted to contact each other to thereby limit the pivotal movement of the movable handle  16  between its inoperative position (FIG. 5) and its operative position (FIG.  6 ). As will be described more fully herein, the protuberance  17  and the movable stop members  22  and  24  contact one another at about 45° to container wall  14 . This reduces the stress in the handle allowing less expensive materials to be used. 
     Referring to FIGS. 1,  4  and  7 , the movable handle  16  comprises a hand grip  26  adapted to be comfortably grasped by a user&#39;s hand. The movable handle  16  further comprises a pair of pivoting arms  28  and  30  that extend from the hand grip  26  and which are generally parallel to each other. The movable handle  16  further comprises rotating pivot portions  32  and  34  which extend from the distal end of the pivoting arms  28  and  30 , respectively and which are generally disposed parallel to the hand grip  26 . 
     With reference to FIG. 7, the rotating pivot portions  32  and  34  comprise cylindrical portions  36  and  38 , respectively, which are adapted to freely rotate within corresponding cylindrically shaped cavity portions  40  and  42  (FIG. 8) extending inwardly from a rear surface  44  of the stationary bracket  12 . Cylindrical portions  36  and  38  are captured within the first and second cavity portions  40  and  42  when bracket  12  is fastened to container wall  14 . When the movable handle  16  is in its operative position (FIG.  6 ), the cylindrical portions  36  and  38  are in bearing contact with their corresponding cavity portions  40  and  42 . 
     Still referring to FIG. 7, each of the rotating pivot portions  32  and  34  further comprise a semi-circularly shaped flange portion  50  protruding from respective ends of the cylindrical portions  36  and  38  which are adapted to freely rotate within corresponding cylindrically shaped cavity portions  52  which extend inwardly from the rear surface  44  of the stationary bracket  12 . When the flange portions  50  are disposed within the cavity portions  52 , the axial movement of the cylindrical portions  36  and  38  and therefore the handle is limited. 
     The rotating pivot portion  34  further comprises a spring support  56  disposed adjacent to and extending from the cylindrical portion  38 . The spring support portion  56  is of generally cylindrical shape and is adapted to receive a torsion spring  58  (FIG.  4 ). The spring support portion  56  is rotatable within a spring attachment cavity  60  extending inward from the rear surface  44  of the stationary bracket  12 . The spring support  56  further includes a rounded square section  62  that is adapted to secure one end of the torsion spring  58  which has been wound around a square mandrel to produce square spring tang  59 . The spring configuration is illustrated in FIG.  11 . The spring and spring support  56  have been selected to reduce stress in the parts thereby creating a longer lifespan for those parts. Where prior art torsion springs have been engaged in a slot in the part around which they are disposed the slotted material tends to fracture from use. Since the square section  62  is inherently of a thicker cross section, it is better able to handle the stress. The stress is also divided over four corners as opposed to two as in the stated prior art arrangements. The other end of the torsion spring  58  is secured by spring leg  57  receivable within a channel  64  formed adjacent to the cavity  60 . The at least one stationary stop member is preferably protuberance  17  illustrated in FIGS. 5 and 6; alternatives being protrusions of the molded container located differently and separate structures mounted to the container wall at a predetermined location relative to the light weight handle. In each of the possible alternates the paramount point is that for the construction dictated the contact orientation for the moveable stop members is about 45° to the container wall/mounting surface of the handle of the invention when the handle is in the operative position. The movable stop members  22  and  24  are formed on an outside portion  68  of the pivoting arms  28  and  30 . In a preferred embodiment, the at least one stationary stop member supplies a contact surface  70  that is at an angle α to the bracket  12  and container wall  14 . In the preferred embodiment, the angle α is about 45 degrees. Similarly, the movable stop members  22  and  24  are each formed with a substantially planar contact surface  72  which is off-set an angle b from outside surface  68  of the pivoting arms  28  and  30 . In a preferred embodiment, the angle b is about 45 degrees. In operation, when the movable handle  16  is pivoted from its inoperative/stored position (FIG. 5) to is operative/lifting position (FIG.  6 ), the movable stop members  22  and  24  are brought into substantial contact with the stationary stop member  17 . As such, the pivotal movement of the movable handle  16  between its inoperative position (FIG. 5) and its operative position (FIG. 6) is about 90 degrees. The contact surfaces  70  and  72  meet at an angle of about 45° to the plane of container wall  14 . This is beneficial because it reduces shear stress in the handle and allows the use of softer less expensive materials. 
     Referring to FIGS. 2,  4 ,  5  and  6 , the stationary bracket  12  also comprises a plurality of mounting lugs or bosses  82  disposed on the rear surface  44  of bracket  12 . In the preferred embodiment, the mounting lugs or bosses  82  extend from the rear surface  44  and provide shear strength between the bracket  12  and the container wall  14 . In this regard, the hand gripping portion  26  of the movable handle  16  may be upwardly displaced an angle c from a bottom surface  86  of the pivoting arms  28  and  30  to thereby facilitate initial grasping of the hand gripping portion  26 . In the preferred embodiment the angle c is in the range of about 15°-25° and preferably is about 19°. The mounting lugs  82  may further comprise openings  84  adapted to receive a suitable fastener such as a self-tapping screw and the like. Such fasteners are loaded in tension only, and sealing against air passage is accomplished by the employment of rubber-faced washers under the heads of the fasteners. 
     The stress-lowering improvements of the handle of the present invention may best be demonstrated with reference to FIG.  6 . As shown, the handle  16  is placed in its operative/lifting position by an upward force F L  applied to the hand grip  26 . As said handle  16  has two pivoting arms  28  and  30 , the upward force on each arm  28  and  30  is F L /2. Upward rotation beyond 90° is prevented by a compressive stop force F s  in the contact area between the movable stop members  22 ,  24  and stationary stop member  17  and a shear force in the pivot F p . For a specific magnitude of F L , the stop force F s  is inversely proportional to the moment arm J. Thus, to minimize F s , the moment arm J must be as large as possible. This is controlled by the thickness t of the bracket  12  and the diameter of the pivot portions  32  and  34 . When the thickness of the bracket  12  and the handle  16  are approximately the same, the moment arm J will be maximized when the angle of the plane between the axis of the pivot portions  32  and  34  and the stop areas  18 ,  20 ,  22  and  24  is 45° relative to the horizontal. In the preferred embodiment where said angle is 45°, said moment arm J is approximately 1.5 times greater than when contact between the movable stop members and stationary stop member is horizontal. Thus, for the same lifting force F L , the compressive stress in the stop member area of the handle  16  is approximately 33% less. This stress-lowering improvement in the handle  16  makes it possible to produce said handle from polyethylene and other low-cost materials such as polypropylene and acrylonitrile-butadiene-styrene (ABS). Polyethylene is preferred due to its nearly inert properties. 
     As will be clear to those skilled in the art, a change in the ratio of bracket thickness to handle thickness will dictate a change in the angle for maximizing the moment arm J. It will also be understood that although the preferred angle of 45° for the construction dictated is optimum, departures from this angle reduce efficiency in increments. Thus, as long as the angle selected is near 45°, a substantial amount of the benefit of the invention will be retained. Preferably, the range of angles for the contact surfaces should be about 38° to about 52° to the container wall with a more preferred range of about 42° to about 48°. It will be understood by one of ordinary skill in the art, subsequent to exposure to this disclosure, that the force advantage of the present invention deteriorates in each direction of angle when moving away from the optimum of about 45°. Referring to FIG. 12, one example of the invention is provided with measurements taken and forces shown. The calculations set forth hereunder demonstrate the very low pivot and stop forces associated with the handle of the invention. The formulae are intended to be read in conjunction with FIG.  12 :                  F   L                   3.43     =         F     s3                     1.19                 cos                 44.5      °     =   0.713                   F   s     =       2.88        F   L                   sin                 44.5      °     =   0.701                   F   P     =           (     F   PH3     )     2     +       (     F   PV3     )     2                       F   PH3     =         F   s3                   cos                 44.5      °     =       2.88                   F   L                   0.713     =     2.05                   F   L                           P   PH3     +     F   L       =       F   S3                     sin   θ                           P   VH3     =                      F   S3                   sin                 44.5      °     -     F   L       =         2.88                   F   L                   0.701     -     F   L       =       2.01        F   L       -     F   L     -     F   L                       =                1.01        F   L                     F   P     =                        (     2.05        F   L       )     2     +       (     1.01        F   L       )     2         =         F   L                       4.20   +   1.02         =     2.28                   F   L                                              
     The stationary bracket  12  and the movable handle  16  may be made from a variety of materials, including but not limited to, polyethylene or any high strength thermoplastic material. The handles of the invention uniquely may be made of polyethylene which if used in a configuration not adhering to the parameters of the invention is generally not structurally strong enough to act as a functional handle. To realize additional weight reductions and to reduce material costs and molding time, material from the stationary bracket  12  and the movable handle  16  may be removed in various places without significantly reducing the load/strength requirements of the components. By way of example only, the pivoting arms  28  and  30  may be formed with cut-outs  76  (FIG. 5) which eliminate a large amount of material and ribs  78  may be formed to maintain the strength requirements. Similarly, the hand grip  26  may be formed with a hollow inner portion  80  thereby also removing a significant amount of material. 
     Except for the torsion spring  58 , protuberance on the container and mounting bolts (not shown), all of features of the handle assembly  10  heretofore described are formed integral to either the stationary bracket  12  or the movable handle  16 . (Stationary stop members other than those molded as part of the container are additional structures). This feature provides a handle assembly  10  that is compatible with high production environments and which is reliable and durable. The stationary bracket  12  and the movable handle  16  may be manufactured by conventional molding processes suitable for use with thermoplastic materials. 
     While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.