Patent Publication Number: US-2003234122-A1

Title: Fork tine scale technology

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS, IF ANY  
     [0001] This application claims the benefit under 35 U.S.C. §119(e) of copending provisional application Serial No. 60/299,127, filed Jun. 18, 2001, which is hereby incorporated by reference. 
    
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002] Not applicable.  
       REFERENCE TO A MICROFICHE APPENDIX, IF ANY  
       [0003] Not applicable.  
       BACKGROUND OF THE INVENTION  
       [0004] 1. Field of the Invention  
       [0005] The present invention relates, generally, to weighing apparatus. More particularly, the invention relates to portable, low profile weighing scales. Most particularly, the invention relates to a weighing scale system for use with a lifting device. The weighing scale provided by this invention is useful for efficiently, reliably and accurately weighing articles having a large and/or irregular support base.  
       [0006] 2. Background Information.  
       [0007] Applicants Kroll et al. discloses scales in U.S. Pat. Nos. 4,714,121, 4,979,581, 5,232,064, 5,646,376, and 5,894,112, and load cells in U.S. Pat. Nos. 4,775,018, 4,813,504, and 5,228,527. The scales and load cells handle abroad range of capacities and have varying degrees of accuracy. Additionally, the scales have varied designs in terms of height, weight, portability and method of use. A common design factor shared by all of these scales and load cells is that in each, the mounting of the load cell in and to the scale is unique and provides a significant advantage over the prior art.  
       [0008] Wheel scales or platform scales are commonly used to measure axle weight loads of vehicles and aircraft. These scales are designed to be used singly, or multiply in concert, with the vehicle rolled onto the scale(s) and the weight of the vehicle thus determined with the wheels resting on the scale(s). However, these small footprint scales are not ideally suited for articles having a large and/or irregular support base that contacts the surface on which the articles rests.  
       [0009] Scales with large weighing platforms are known, but their size renders the scale immobile. Thus, the large/irregular support base article must be moved onto and off the platform for weighing, or articles to be weighed must be moved to a permanently placed scale, which may be a long distance away. Fork lift truck scales and pallet truck scales are available for weighing articles elevated on the tines of these lifting devices. The weighing scale is interposed between the tines and the lifting mechanism of the lifting device, resulting in a complex arrangement.  
       [0010] Thus, there is an unmet need for a weighing scale that can be fitted to a lifting device, transported to such large/irregular support base articles, and obtain the article weight efficiently, reliably and accurately, without excessive movement of the article. The invention provides a weighing scale system, which is believed to fulfill the need and to constitute an improvement over the background technology.  
       [0011] All U.S. patents and patent applications, and all other published documents mentioned anywhere in this application are incorporated by reference in their entirety.  
       BRIEF SUMMARY OF THE INVENTION  
       [0012] The present invention provides an apparatus and method for weighing articles that can be elevated by a lifting device. In one embodiment, the apparatus includes a weighing scale comprising a base mountable on a tine of a lifting device, the base having a predetermined number of load cell mounts, each one of the load cell mounts providing a deflection gap between the load cell and the base. A platform for contact with a load is disposed above and in operational contact with the base. A number of load cells equal to the number of load cell mounts is present, with each one of the load cells attached to one of the load cell mounts of the base and positioned between the base and the platform. A number of engagement members equal to the number of load cells are present, with each one of the engagement members in operational contact with the platform and one of the load cells.  
       [0013] In another embodiment, the apparatus includes a tine mounted weighing scale apparatus comprising a pair of weighing scale units, each unit mountable to one tine of a lifting device. Each weighing scale unit includes a base mountable on a tine of a lifting device, the base having a predetermined number of load cell mounts, each one of the load cell mounts providing a deflection gap between the load cell and the base. A platform for contact with a load is disposed above and in operational contact with the base. A number of load cells equal to the number of load cell mounts is present, with each one of the load cells being attached to one of the load cell mounts of the base and positioned between the base and the platform. A number of engagement members equal to the number of load cells are present, with each one of the engagement members being in operational contact with the platform and one of the load cells. An electrical control/display and a power supply are operatively connected to the pair of weighing scale units for displaying the total weight supported by the scale apparatus.  
       [0014] In another embodiment, the apparatus includes a tine mounted weighing scale apparatus comprising a pair of weighing scale units, each unit mountable to one tine of a lifting device. Each weighing scale unit includes a base mountable on a tine of a lifting device, the base having a predetermined number of load cell mounts, each one of the load cell mounts providing a deflection gap between the load cell and the base. The base includes a sheath adapted for receiving a tine of a lifting device and a fastener for securing the sheath-containing base to the tine of the lifting device. A platform for contact with a load is disposed above and in operational contact with the base. A number of shear beam load cells equal to the number of load cell mounts is present, with each one of the shear beam load cells attached to one of the load cell mounts of the base and positioned between the base and the platform. A number of engagement members equal to the number of shear beam load cells is present, with each one of the engagement members in operational contact with the platform and one of the shear beam load cells. The engagement members include a fork nut secured to a bottom surface of the platform, the fork nut having a threaded cavity therein, and a threaded fastener traversing the load cell and secured within the nut threaded cavity. A summing box for summing output from the predetermined number of shear beam load cells is present. An electrical control/display and a power supply are operatively connected in series to the pair of weighing scale units for displaying the total weight supported by the scale apparatus.  
       [0015] In another embodiment, the method of weighing an article with a lifting device includes the steps of providing a tine mounted weighing scale apparatus having a pair of weighing scale units, each unit mountable to one tine of the lifting device. Each weighing scale unit includes a base mountable on a tine of a lifting device, the base having a predetermined number of load cell mounts, each one of the load cell mounts providing a deflection gap between the load cell and the base. A platform for contact with a load is disposed above and in operational contact with the base. A number of load cells equal to the number of load cell mounts are present, with each one of the load cells attached to one of the load cell mounts of the base and positioned between the base and the platform. A number of engagement members equal to the number of load cells are present, with each one of the engagement members in operational contact with the platform and one of the load cells. An electrical control/display and a power supply are operatively connected to the pair of weighing scale units for displaying the total weight supported by the scale apparatus.  
       [0016] Each scale unit of the weighing scale apparatus is secured to the tine of a lifting device. The article is elevated off a support surface using the lifting device fitted with the scale apparatus, and the weight determined by observing the output of the electrical display.  
       [0017] The features, benefits and objects of the invention will become clear to those skilled in the art by reference to the following description, claims and drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
     [0018]FIG. 1 is a top view of a weighing scale of the present invention.  
     [0019]FIG. 2 is a front view of the display screen of the control/display of the present invention.  
     [0020]FIG. 3 is a top view of the control/display unit of the present invention.  
     [0021]FIG. 4 is an exploded perspective view of one scale unit of the present invention.  
     [0022]FIG. 5 is a perspective view of the base member of the scale unit.  
     [0023]FIG. 6 is a perspective view of the base plate portion of the base member.  
     [0024]FIG. 7 is a bottom perspective view of the base top plate portion of the base member.  
     [0025]FIG. 8 is a perspective view of the platform member bottom of the scale unit.  
     [0026]FIG. 9 is a cross sectional view of one of the load cells secured between the base member and the platform member.  
     [0027]FIG. 10 is an exploded perspective view of another embodiment of one scale unit of the present invention.  
     [0028]FIG. 11 is a perspective view of the platform member bottom of the embodiment of FIG. 10.  
     [0029]FIG. 12 is a cross sectional view of one of the load cells secured between the base member and the platform member of the embodiment of FIG. 10. 
    
    
     DETAILED DESCRIPTION  
     [0030] The present invention is a weighing scale apparatus that is useful for weighing articles having a large and/or irregular support base, such as one or more items loaded on a pallet. Other such articles include containers, large footprint machinery, vehicles and various hard to move items. The weighing scale assembly is secured to the tines of a fork lift truck or pallet truck, and provides weighing of articles, such as a loaded pallet, by elevation of the article off the support surface by the weighing scale apparatus/tine lifting device.  
     [0031]FIG. 1 show one embodiment of the present invention, illustrated and generally indicated by the reference numeral  10 . Referring to FIG. 1, the tine mounted weighing scale apparatus  10  includes a pair of weighing scale units  15 , each mounted on one tine (shown in phantom) of a lifting device, such as a fork lift truck or pallet truck. Each scale unit  15  includes a fastener for securing the scale unit  15  to the tine, such as fastener straps  44  and a locking bar member  48 , as illustrated in FIG. 1. The scale units  15  are connected in series to an electronic control and display unit  20  remote from the scale units  15 . The power unit for the apparatus is preferably one or more batteries, with the power unit preferably contained within the control/display unit  20 . An enlarged top view of the face of the control/display unit  20  is shown in FIG. 3, the face including a number of control buttons  18  and a display screen  19  illustrated in greater detail in FIG. 2. The weighing scale apparatus  10  is readily mounted to or removed from a tined lifting device, such as a fork truck or a pallet truck. The flexible conductor wires  40  between each scale unit  15  and from one scale unit  15  and to the control and display unit  20  provides facile mounting of the weighing scale assembly  10  to various sized and configured tined lifting devices.  
     [0032] Referring now to FIG. 4, one of the weighing scale units  15  is shown in a perspective, exploded view. The weighting scale unit  15  includes a base member  22  and a platform member  24  secured in register to the base member  22 , the scale unit  15  designed for accepting a tine of the lifting device. The base member  22  has an interior, sheath-like longitudinal cavity  26  therein with an open end  27  into which the tine is reversibly positioned. The base member  22 , shown in greater detail in FIGS.  5 - 7 , is composed of a planar base plate portion  28  (FIG. 6) and a U-shaped base top plate portion  30  (FIG. 7). When secured together, the two portions  28 ,  30  form the sheath-like cavity  26  that accepts the lifting device tine. The base plate portion  28  is the same length, but wider than the top plate portion  30 , thereby providing areas exterior the sheath-like cavity  26  for locating a plurality of load cell mounts  32 , each for mounting a load cell  34  thereto. In the present embodiment, there are four load cell mounts  32  and four associated load cells  34 , with one mount  32  and associated load cell  34  disposed at each corner of the base plate portion  28  of the base member  24 . A greater number of load cell mounts  32  and associated load cells  34  may be included in the present invention with equivalent results. The load cells  34  are preferably shear beam load cells  34 , described in detail below. Each rectangular load cell  34  is secured at one end to the load cell mount  32  by a pair of threaded fasteners  36  extending from beneath the base member  24  and through the load cell  34  to engage threaded nuts  36 ′. The load cells  34  engage and vertically support the platform member  24  via engagement members  37 , also described in detail below. Other load cell mount configurations are anticipated. However, the present load cell mount configuration is preferable for the type of load cells being used in this invention.  
     [0033] The load cells  34  are operatively connected to a summing box  38 , also secured to the base plate portion, by conductor wires  40  that are routed exterior the sheath-like cavity  26 . The conductor wires  40  are routed through an end tube member  42  from one side of the scale unit  15  to the other. The summing box  38  of each scale unit  15  is connected in series to the electronic control and display member  20 , as illustrated in FIG. 1. Fastener strips  44  are secured to the base member  22  adjacent the open end  27  of the sheath-like cavity  26  for attaching the scale unit  15  to the lifting device tine. The fastener strips  44  each include an aperture  46  that accepts a locking bar  48  for securing the scale member  15  to the tine, as illustrated in FIG. 1. Alternatively, the apertures  46  may be threaded to accept a set screw (not shown) that engages the tine to secure the scale member  15  thereto.  
     [0034] The platform member  24  includes a top contact surface  50  and downward extending perimeter walls  52  on one end and two sides, with no wall adjacent the sheath-cavity open end  27 . The platform member  24  is sized to cover the top and sides of the base member  22 , thereby covering and protecting the load cells  34 , summing box  38  and associated conductor wires  40 . The bottom surface  54  of the platform member  24  is shown in FIG. 8 where a plurality, in this case four, of fork nuts  56  is secured thereto. Each fork nut  56  is positioned on the platform member bottom surface  54  such that a threaded cavity  58  therein is in register with a load cell  34  on the base member  22 .  
     [0035] Referring now to FIG. 9, the load cell mount  32 , load cell  34  and engagement means  37  are shown in cross section. The load cell  34  has an elongated, generally square cross sectional configuration. A pair of mounting apertures  35  is located proximate one end of the load cell  34 . The apertures  35  permit the load cell  34  to be mounted to the load cell mount  32  of the base plate portion  28  by the mounting bolts  36  positioned in the base mounting apertures  39  of the base member  24 . A spacer  33 , smaller than the load cell  34 , is positioned between the load cell mount  32  and the load cell  34 , adjacent the load cell mounting apertures  35 . The spacer  33  elevates the shear beam load cell  34 , thereby extending the load cell  34  above the base plate portion  28  at an end opposite the threaded fasteners  36  securing the load cell  34  thereto. A threaded fastener  60 , passing through a third load cell aperture  62 , secures the load cell  34  at the elevated end to one fork nut  56  of the platform member  24 , as illustrated in FIG. 9. Thus, the fork nut  56  and the threaded fastener  60  comprise the engagement means  37  between the load cell  34  and the platform member  24 . The base plate portion  28  also contains an access aperture  64  for accessing the threaded fastener  60 , allowing the plate member  24  to be secured to or removed from the base member  22 . The plate member bottom surface  54  also contains a pair of linear supports  66  to provide added stability between the base member  22  and the platform member  24 . Thus, a load placed on the platform member  24  causes a deflection of the load cell  34  at the end opposite the threaded fasteners  36  securing the load cell  34  to the base plate portion  28 . A cable connection  41  is disposed at the end of the load cell  34  to receive an electrical conductor wire  40 . The conductor wire  40  provides electrical communication between the load cell  34  and the summing box  38 . Strain gauges (not shown) are disposed within the load cell  34  to measure dimensional changes in the load cell  34  caused by the load. The operation of a strain gauge is based on the principle that the electrical resistance of a conductor changes when it is subjected to a mechanical deformation. There are a number of resistance strain gauge types that may be used, including bonded strain gauge, wire gauge, foil gauge and semiconductor gauge. As each strain gauge is mechanically deformed, its length and diameter are altered, resulting in a change in its electrical resistance, which is used to calculate a weight.  
     [0036] The proper orientation of the strain gauges on each mounted and aligned load cell  34  permits accurate weighing irrespective of the exact location of the load relative to the contact surface  50  of the platform member  24  that may be due to uneven load placement or tilting of each weighing scale unit  15 . The design of the platform members  24 , engagement means  37 , load cells  34  and base members  22  cooperate to permit the proper deflection of the load cell  34  for accurate and repeatable readings without the potentially damaging side load effects and torquing.  
     [0037] Another embodiment of the tine mounted weighing scale apparatus  110  is shown in FIGS. 10 and 11. The scale apparatus  110  again includes a pair of weighing scale units  115 , each mounted on one tine (shown in phantom) of a lifting device, such as a fork lift truck or pallet truck. Each scale unit  115  includes a means for securing the scale unit  115  to the tine, such as fastener straps  144  and a locking bar member  148 , as illustrated in FIG. 1. The scale units  115  are connected in series to an electronic control and display unit  120  remote from the scale units  115 . The weighing scale apparatus  110  is readily mounted to or removed from a tined lifting device, such as a fork truck or a pallet truck. The flexible conductor wires  140  between each scale unit  115 , and from one scale unit  115  to the control and display unit  120 , provides facile mounting of the weighing scale assembly  110  to various sized and configured tined lifting devices.  
     [0038] Referring now to FIG. 10, one of the weighing scale units  115  is shown in an exploded view. The weighting scale unit  115  includes a base member  122  and a platform member  124  secured in register to the base member  122 , the scale unit  115  designed for accepting a tine of the lifting device. The base member  122  has an interior, sheath-like longitudinal cavity  126  therein with an open end  127  into which the tine is reversibly positioned. The base member  122  is composed of a planar base plate portion  128  and a U-shaped base top plate portion  130  that form the sheath-like cavity  126  that accepts the lifting device tine, and is essentially identical to base member  22  described in detail above. There are four load cell mounts  132  and four load cells  134  disposed at each corner of the base portion  128  of the base member  124  as described in detail above.  
     [0039] The platform member  124  includes a top contact surface  150  and downward extending perimeter walls  152  on one end and two sides with no wall adjacent the sheath-cavity open end  127 . The platform member  124  is sized to cover the top and sides of the base member  122 , thereby covering and protecting the load cells  134 , summing box  138  and associated conductor wires  140 . The bottom surface  154  of the platform member  124  is shown in FIG. 11 where a plurality, in this case four, of fork nuts  156  is secured thereto. Each fork nut  156  is positioned on the platform member bottom surface  154  such that a threaded cavity  158  therein is in register with a load cell  134  on the base member  122 .  
     [0040] Referring now to FIG. 12, the load cell mount  132 , load cell  134  and engagement means  137  are shown in cross section. The load cell  134  has an elongated, generally square cross sectional configuration. A pair of mounting apertures  135  is located proximate one end of the load cell  134 . The apertures  135  permit the load cell  134  to be mounted to the load cell mount  132  of the base plate portion  128  by the mounting bolts  136  positioned in the base mounting apertures  139  of the base member  124 . A spacer  133 , smaller than the load cell  134 , is positioned between the load cell mount  132  and the load cell  134  adjacent the load cell mounting apertures  135 . The spacer  133  elevates the shear beam load cell  134 , thereby extending the load cell  134  above the base plate portion  128  at an end opposite the threaded fasteners  136  securing the load cell  134  thereto. A threaded fastener  160 , passing through a third load cell aperture  162 , secures the load cell  134  at the elevated end to the fork nut  156  of the platform member  126 , as illustrated in FIG. 12. Thus, the fork nut  156  and the threaded fastener  160  comprise the engagement means  137  between the load cell  134  and the platform member  124 . The base plate portion  128  also contains an access aperture  164  for accessing the threaded fastener  160 , allowing the plate member  124  to be secured to or removed from the base member  122 . Thus, a load placed on the platform member  124  causes a deflection of the load cell  134  at the end opposite the threaded fasteners  136  securing the load cell  134  to the base plate portion  128 .  
     [0041] The platform member  124  also includes a plurality of slot apertures  170 , located around the periphery of the flat, top contact surface  150 . Within each slot aperture  170  is mounted a roller member  172  such that the roller circumference surface  174  extends slightly above the platform surface  150 , and with the rotational axes of the roller members  172  in parallel. The roller members  172  are mounted on pins or axles  176  secured between the roller mount members  178  and the downwardly extending perimeter walls  152  of the platform member  124 , as shown in FIG. 11, where the platform member  124  is inverted. Each pin or axle  176  supports a single roller member  172 , although a common pin or axle  176  may be used for roller members  172  at the end of the plate member  124 . Each pin or axle  176  is mounted with at least one end secured to a sidewall  152  of the platform  124 . This configuration of the roller members  172  provides for facile on and off movement of articles from the ends of the weighing scale units  115  opposite the open end  127  of the sheath-like cavity  126  that receives the fork tine.  
     [0042] The slot apertures  170  and roller members  172  are distributed around the periphery of the contact surface  150  so as to avoid the areas occupied by each load cell  134  and by the summing box  138 , as well as the sheath-like cavity  126  that accepts the tine. The roller members  172  allow smooth transfer of articles on and off of the time-mounted scale units  115  of the scale apparatus  110 .  
     [0043] The embodiment of the tine mounted weighing scale apparatus having roller members  172  rotatably secured in slot apertures  170  of the flat, top contact surface  150  is particularly useful in the loading of cargo articles onto aircraft. Fork lifts and pallet trucks are not used within aircraft to exclude possible punctures to the aircraft exterior. Cargo is usually loaded into the aircraft cargo bay via sliding up an inclined ramp having many surface mounted rollers. The tine mounted weighing scale apparatus  110 , having roller members  172  secured to the platform members  24 , provides facile movement of cargo articles off of the tine mounted scale units  115  and onto the inclined ramp having rollers. Such a device is unique to the aircraft cargo industry, finding numerous applications in both the government (military) and private sectors.  
     [0044] Although the scale embodiments having one and two units have been described, the teachings of this invention are applicable to scales having three or more units.  
     [0045] The descriptions above and the accompanying drawings should be interpreted in the illustrative and not the limited sense. While the invention has been disclosed in connection with an embodiment or embodiments thereof, it should be understood that there may be other embodiments which fall within the scope of the invention as defined by the claims. Where a claim, if any, is expressed as a means or step for performing a specified function it is intended that such claim be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof, including both structural equivalents and equivalent structures, material-based equivalents and equivalent materials, and act-based equivalents and equivalent acts.