Abstract:
An apparatus ( 10 ) for weighing wheeled or wheel- or caster-supported loads, including non-ambulatory patients confined to wheeled beds, which combines lift, support, and weight-measuring functions. The apparatus ( 10 ) is lightweight, portable, and employs a foot-activated lever-based design, including a foot bar ( 51 ) and pivoting wheel receptacle ( 50 ), for raising both the load and the load&#39;s wheeled support, if any. The apparatus ( 10 ) can be positioned for use without moving the load, and, because the apparatus utilizes leg and lower body strength, operators need not possess substantial arm or upper body strength. Thus, injuries which result from improper lifting techniques are avoided.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to weight-measuring devices, and, more particularly, to apparatuses for measuring the weights of wheeled or wheel-supported loads. 
     2. Description of the Prior Art 
     It is often desirable to weigh wheeled or wheel-supported loads, and various devices and methods exist for doing so. Weight-measuring devices exist, for example, which require the operator to push, pull, lift, lever, drive, or roll the load into position. All have their drawbacks-pushing, pulling, and lifting may require substantial strength; rolling, pushing, and pulling can be difficult and dangerous on smooth floors or uneven ground; driving requires a means of propulsion; and lever-based designs typically require substantial upper body strength or cumbersome and unwieldy lever attachments. These devices are also typically voluminous, heavy, clumsy to operate, complex or expensive. Furthermore, where the device is effectively non-portable, either the load must be transported to the weight-measuring device, or a separate device must be purchased and installed for each load. 
     Some weight-measuring devices are designed with particular types of loads in mind. Specialized devices exist, for example, for weighing non-ambulatory persons without removing them from their wheel-supported beds. These devices are desirable where an illness requires frequent or constant monitoring of a patient&#39;s weight and it is impractical or injurious to remove the patient from their bed for each weighing. Patients and beds, particularly specialized beds, can be very heavy. Frequently, the operator attempting to weigh a patient lacks the substantial strength needed to lift or push or pull a patient and their bed into position for weighing. Furthermore, a poor lifting technique can result in injury to the operator. Where the device requires that the bed be rolled, pushed, or pulled into position, smooth or waxed hospital floors may make doing so difficult or dangerous. Lever-based devices typically require substantial upper-body strength, particularly arm strength, which hospital personnel may not possess, or incorporate cumbersome, unwieldy lever attachments that are impractical for use in a confined room or other hospital setting. 
     SUMMARY OF THE INVENTION 
     The weight measuring apparatus of the present invention includes novel advancements in weight measuring technology which make the weighing of wheeled or wheel-supported loads easier and more efficient. This apparatus overcomes many of the drawbacks present in the art by employing a foot-activated lever to raise and position the wheeled or wheel-supported load for weighing. This design harnesses the naturally superior strength of the legs and lower body, and does not require that the operator possess substantial arm or upper body strength. The present apparatus is also lightweight and portable, allowing it to be easily moved from one application to another. Furthermore, being easily moved and positioned, the present apparatus does not require that the load be moved across smooth or slippery, possibly waxed, floors. 
     In use, an operator places one weight measuring apparatus of the present invention in front of and in contact with each wheel of the wheeled or wheel-supported load, and then steps upon each footbar to lift the load into position for weighing. The load&#39;s total weight is obtained by summing the outputs of the individual apparatuses. Though the invention also has broad application in weighing any wheeled or wheel-supported load whose weight does not exceed a human operator&#39;s ability to lever the load into position, the primary application of the present invention is in weighing non-ambulatory patients confined to wheeled beds. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the present invention is described in detail below with reference to the attached drawing figures, wherein: 
     FIG. 1 is an exploded view of a preferred embodiment of the weight-measuring apparatus of the present invention illustrating the relationships between the major components. 
     FIG. 2 is a vertical side sectional view of the apparatus which illustrates the initial stage of operation of the apparatus. 
     FIG. 3 is a vertical side sectional view of the apparatus which illustrates an intermediate stage of operation of the apparatus. 
     FIG. 4 is a perspective view of the apparatus with portions broken away which illustrates the relationships of the assembled components. 
     FIG. 5 is a side elevational view of the apparatus in partial section which further illustrates the relationships of the assembled components. 
     FIG. 6 is a block diagram which illustrates the operational relationship between several load cells that are a part of a preferred embodiment of the weight-measuring apparatus of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawing figures, and particularly to FIG. 1, a weight-measuring apparatus  10  constructed in accordance with a preferred embodiment of the present invention is illustrated. Such an apparatus  10  can be used for measuring the weight of a wheeled or wheel-supported load. In the preferred embodiment, several of the apparatuses  10  are used to measure the weight of a non-ambulatory patient without removing the patient from his or her wheeled bed. The apparatus  10  includes four major components: a base  20 ; left and right protective covers  30 , 31 ; left and right weight-measuring sensors  40 , 41 ; a wheel receptacle  50 ; and a foot bar  51 . 
     The base  20  supports the other components of the apparatus  10 . The base  20  is comprised of a top portion  22  and a bottom portion  21 , both of which are substantially flat and U-shaped. The bottom portion  21  is an anti-skid pad or floor protector, and is fixedly attached to the underside of the top portion  22 . From the interior edges of the top portion  22 , a left flange  23  and a right flange  24  extend perpendicularly upward from the base  20 . The left and right flanges  23 , 24  have holes to allow for bolting the left and right protective covers  30 , 31 , left and right weight-measuring sensors  40 , 41 , and other components to the flanges  23 , 24 . The bottom portion  21  of the base  20  is made of a non-skid or non-abrasive material. The top portion  22  is made of heavy gauge metal or other suitable material. 
     The left and right protective covers  30 , 31  cover and protect the left and right weight-measuring sensors  40 , 41 . The left and right protective covers  30 , 31  are made of light gauge metal or other suitable material, and are substantially rectangular, hollow, and open at their respective bases in order to accommodate the left and right weight-measuring sensors  40 , 41 . Furthermore, each protective cover  30 , 31  has a circular opening  34 , 35  near its top to allow portions of the wheel receptacle  50  to pass through unobstructed to the weight-measuring sensors  40 , 41  and to allow the wheel receptacle  50  to rotate freely. The left and right protective covers  30 , 31  are bolted to the left and right flanges  23 , 24 , and extend perpendicularly upward from the base  20 . 
     The left and right weight-measuring sensors  40 , 41  support the wheel receptacle  50  and are positioned and operable to measure a weight suspended in the wheel receptacle  50 , as described below. The left and right weight-measuring sensors  40 , 41  are rectangularly-shaped, with intermediate cut-outs  42 , 43 , and have circular openings  46 , 47  near their respective tops which correspond to similar, though larger, circular openings  34 , 35  in the left and right protective covers  30 , 31 . Any type of force-sensing transducer may be used to determine the weight of the load as it is applied to the left and right weight-measuring sensors  40 , 41 . The preferred embodiment uses strain gauges  48 , 49  mounted upon the left and right weight-measuring sensors  40 , 41  to detect the strain in the left and right weight-measuring sensors  40 , 41  from the force applied to them when a load is positioned in the wheel receptacle  50  (see FIG.  5 ). The strain in the left and right weight-measuring sensors  40 , 41  is converted to an electrical signal by the strain gauges  48 , 49  and transmitted to a weight indicator  33  via an electrical connector  32  (see FIG.  5 ). The left and right weight-measuring sensors  40 , 41  are bolted to the left and right flanges  23 , 24 , extend perpendicularly upward from the base  20 , and are housed within the left and right protective covers  30 , 31 . A left spacer block  25  is bolted between the left protective cover  40  and the left weight-measuring sensor  30 , and a right spacer block  26  is bolted between the right protective cover  41  and the right weight-measuring sensor  31 , to prevent the protective covers  30 , 31  from directly contacting the weight-measuring sensors  40 , 41  and affecting the weight measurement. The left and right spacer blocks  25 , 26  are rectangular and made of metal or some other suitable material. 
     The weight indicator  33  is operable to receive the summed electrical signals produced by a plurality of weight-measuring sensors  40 , 41 , and to output or otherwise display the result (see FIG.  6 ). 
     The wheel receptacle  50  is operable to receive a wheel  60  and then pivot with the wheel  60  about a horizontally-extending axis, thereby lifting the wheel  60  so that neither the wheel  60  nor the wheel receptacle  50  are in direct contact with the ground, floor, or base  20  of the apparatus  10  (see FIGS.  2  and  3 ). The wheel receptacle  50  comprises a left side wall  52 , a right side wall  53 , a bottom wall  54 , a left pivot pin  55 , a right pivot pin  56 , and a foot bar  51 . In the preferred embodiment, the left and right side walls  52 , 53  are semi-triangular in shape, with the base of the triangle being rounded in order to accommodate the bottom wall  54 , which is preferably concave in order to more easily receive a wheel  60  or caster (see FIGS.  2  and  3 ). 
     Together, the left and right pivot pins  55 , 56  provide an axis around which the wheel receptacle  50  is free to rotate. The left and right pivot pins  55 , 56  are fixedly mounted to the left and right side walls  52 , 53  so that they extend perpendicularly therefrom, pass through the circular openings  34 , 35  of the left and right protective covers  30 , 31 , and are rotatably received within the circular support openings  34 , 35  of the weight-measuring sensors  40 , 41 . Bushings  44 , 45  may be used to line the circular support openings  34 , 35  of the weight-measuring sensors  40 , 41  in order to reduce wear and facilitate rotation. 
     The footbar  51  is attached to the left and right side walls  52 , 53  of the wheel receptacle  50  in such a manner and position that a force acting upon the footbar  51  will cause the wheel receptacle  50  to rotate about the axis formed by the left and right pivot pins  55 , 56 . Protective endcaps  57 , 58  may cover both ends of the footbar  51 . Because the footbar  51  and left and right side walls  52 , 53  act as a lever, with the fulcrum being the left and right pivot pins  55 , 56 , the footbar  51  is preferably attached to the left and right side walls  52 , 53  as far as possible from the left and right pivot pins  55 , 56 . 
     The assembled apparatus  10  is illustrated in FIG. 4. A portion of the left and right protective covers  30 , 31  are shown broken away in order to more clearly illustrate the relationship between the left and right weight-measuring sensors  40 , 41  and the left and right protective covers  30 , 31   
     Referring to FIGS. 2 and 3, in operation, an operator places one weight-measuring apparatus  10  of the present invention in front of and in contact with each wheel  60  of a wheeled or wheel-supported load, such as a hospital bed. For illustration, the wheel  60  is shown attached to the leg of a hospital bed  61 . The operator then steps upon each footbar  51  to lift the load into position for weighing. FIG. 3 illustrates the weighing position, with the wheel  60  being held within the wheel receptacle  50  and suspended between the left and right weight-measuring sensors  40 , 41  (see also FIG.  1 ). The load&#39;s total weight is obtained by summing the signals from each weight measuring apparatus  10  and sending the resulting signal to the weight indicator  33 , as shown in FIG.  6 . 
     From the preceding description, it can be seen that the weight-measuring apparatus of the present invention alleviates problems encountered when weighing wheeled or wheel-supported loads. The apparatus is portable, lightweight, and can be positioned for use without moving the load to be weighed. More particularly, the apparatus of the present invention employs a foot-activated lever-based design which allows an operator possessing limited arm or upper body strength to lift, support, and weigh the load in one movement. 
     Although the invention has been described with reference to the preferred embodiment illustrated in the attached drawings, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims. Furthermore, the present invention is for a positioning apparatus which is independent of and can be adjusted to a variety of weight measuring sensors.