Patent Publication Number: US-11395783-B2

Title: Patient support apparatus with load cell assemblies

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The subject patent application claims priority to and all the benefits of U.S. Provisional Patent Application No. 62/880,937 filed on Jul. 31, 2019, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Patient support apparatuses, such as hospital beds, stretchers, cots, tables, and wheelchairs, facilitate care of patients in a health care setting. Conventional patient support apparatuses comprise a base, a support frame, and a patient support deck upon which the patient is supported. Bariatric patient support apparatuses are generally designed to support heavier weight loads than conventional patient support beds. Certain conventional bariatric patient support apparatuses may comprise load cells for measuring the weight being supported by the base. Loading and unloading of bariatric patients from these types of known bariatric patient support apparatuses can cause high contact forces between the load cell and bed frame interface resulting in metal deformation of the load cell interface leading to inaccurate load scale readings. 
     A patient support apparatus with an additional support assembly between the load cell contact point and bed frame designed to overcome one or more of the aforementioned disadvantages is desired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a patient support apparatus. 
         FIG. 2  is a perspective view of a support structure of the patient support apparatus of  FIG. 1 . 
         FIG. 3  is an exploded view of the support structure shown in  FIG. 2 . 
         FIG. 4  is a perspective view of a portion of the support structure shown in Area  4  of  FIG. 2 , illustrating a load cell assembly. 
         FIG. 5  is an exploded view of the support structure shown in  FIG. 4 , illustrating a load cell assembly. 
         FIG. 6  is an exploded view of the load cell assembly of  FIG. 5  shown comprising a load cell support assembly and a load cell element. 
         FIG. 7  is a perspective view of a portion of the load cell assembly of  FIG. 6 . 
         FIG. 8  is a perspective of a foot pad of the load cell assembly of  FIG. 6 . 
         FIG. 9  is a perspective view of a mounting shoe of the load cell assembly of  FIG. 6 . 
         FIG. 10  is a perspective view of a wear plate of the load cell assembly of  FIG. 6 . 
         FIG. 11  is a perspective view of support structure illustrating the movement of the load cell element of  FIG. 6 . 
         FIG. 12  is a partial sectional view of the support structure, taken along line  12 - 12  in  FIG. 4 , illustrating the movement of the load cell element of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a patient support apparatus  30  is shown for supporting a patient in a health care setting. The patient support apparatus  30  illustrated in  FIG. 1  comprises a hospital bed. In other embodiments, however, the patient support apparatus  30  may comprise a stretcher, cot, table, wheelchair, or similar apparatus utilized in the care of a patient. 
     A support structure  32  provides support for the patient. The support structure  32  illustrated in  FIG. 1  comprises a base  34  and a deck support frame  36 . The base  34  comprises a base frame assembly  35 . The deck support frame  36  is spaced above the base frame assembly  35  in  FIG. 1 . The support structure  32  also comprises a patient support deck  38  disposed on the deck support frame  36 . The patient support deck  38  comprises several sections, some of which are pivotable relative to the deck support frame  36 , such as a back section  41 , a seat section  43 , a leg section  45 , and a foot section  47 . The patient support deck  38  provides a patient support surface  42  upon which the patient is supported. 
     A mattress  49  (shown in hidden lines in  FIG. 1 ) is disposed on the patient support deck  38  during use. The mattress  49  comprises a secondary patient support surface upon which the patient is supported. The base  34 , deck support frame  36 , patient support deck  38 , and patient support surfaces  42  each have a head end and a foot end corresponding to designated placement of the patient&#39;s head and feet on the patient support apparatus  30 . The base  34  comprises or otherwise defines a longitudinal axis L along its length from the head end to the foot end, and a transverse axis T arranged perpendicular to the longitudinal axis L. The base  34  also comprises or otherwise defines a vertical axis V arranged crosswise (e.g., perpendicularly) to the longitudinal axis L (and also to the transverse axis T) along which the deck support frame  36  is lifted and lowered relative to the base  34 . 
     A lift device  70  may be coupled to the base  34  and the deck support frame  36  to raise and lower the deck support frame  36  to minimum and maximum heights of the patient support apparatus  30 , and intermediate positions therebetween. The lift device  70  comprises one or more lift arms  72  coupling the deck support frame  36  to the base  34 . The lift device  70  comprises one or more lift actuators that are coupled to at least one of the base  34  and the deck support frame  36  to raise and lower the deck support frame  36  and patient support deck  38  relative to the floor surface and the base  34 . The lift device  70  may be configured to operate in the same manner or a similar manner as the lift mechanisms shown in U.S. Pat. Nos. 7,398,571, 9,486,373, 9,510,981, and/or U.S. Patent Application Publication No. 2018/0028383, hereby incorporated herein by reference. 
     The deck support frame  36  comprises a second longitudinal axis L 2  along its length from the head end to the foot end. The construction of the support structure  32  may take on any known or conventional design, and is not limited to that specifically set forth above. In addition, the mattress  49  may be omitted in certain embodiments, such that the patient rests directly on the patient support surface  42 . 
     Side rails  44 ,  46 ,  48 ,  50  are coupled to the deck support frame  36  and thereby supported by the base  34 . A first side rail  44  is positioned at a right head end of the deck support frame  36 . A second side rail  46  is positioned at a right foot end of the deck support frame  36 . A third side rail  48  is positioned at a left head end of the deck support frame  36 . A fourth side rail  50  is positioned at a left foot end of the deck support frame  36 . If the patient support apparatus  30  is a stretcher or a cot, there may be fewer side rails. The side rails  44 ,  46 ,  48 ,  50  are movable between a raised position in which they block ingress and egress into and out of the patient support apparatus  30 , one or more intermediate positions, and a lowered position in which they are not an obstacle to such ingress and egress. In still other configurations, the patient support apparatus  30  may not comprise any side rails. 
     A headboard  52  and a footboard  54  are coupled to the deck support frame  36 . In other embodiments, when the headboard  52  and footboard  54  are utilized, the headboard  52  and footboard  54  may be coupled to other locations on the patient support apparatus  30 , such as the base  34 . In still other embodiments, the patient support apparatus  30  does not comprise the headboard  52  and/or the footboard  54 . 
     Caregiver interfaces  56 , such as handles, are shown integrated into the footboard  54  and side rails  44 ,  46 ,  48 ,  50  to facilitate movement of the patient support apparatus  30  over floor surfaces. Additional caregiver interfaces  56  may be integrated into the headboard  52  and/or other components of the patient support apparatus  30 . The caregiver interfaces  56  are graspable by the caregiver to manipulate the patient support apparatus  30  for movement. 
     Other forms of the caregiver interface  56  are also contemplated. The caregiver interface  56  may comprise one or more handles coupled to the deck support frame  36 . The caregiver interface  56  may simply be a surface on the patient support apparatus  30  upon which the caregiver applies force to cause movement of the patient support apparatus  30  in one or more directions, also referred to as a push location. This may comprise one or more surfaces on the deck support frame  36  or base  34 . This could also comprise one or more surfaces on or adjacent to the headboard  52 , footboard  54 , and/or side rails  44 ,  46 ,  48 ,  50 . In other embodiments, the caregiver interface may comprise separate handles for each hand of the caregiver. For example, the caregiver interface may comprise two handles. 
     Wheels  58  are coupled to the base  34  to facilitate transport over the floor surfaces. The wheels  58  are arranged in each of four quadrants of the base  34  adjacent to corners of the base  34 . In the embodiment shown, the wheels  58  are caster wheels able to rotate and swivel relative to the support structure  32  during transport. Each of the wheels  58  forms part of a caster assembly  60 . Each caster assembly  60  is mounted to the base  34 . It should be understood that various configurations of the caster assemblies  60  are contemplated. In addition, in some embodiments, the wheels  58  are not caster wheels and may be non-steerable, steerable, non-powered, powered, or combinations thereof. Additional wheels are also contemplated. For example, the patient support apparatus  30  may comprise four non-powered, non-steerable wheels, along with one or more powered wheels. In some cases, the patient support apparatus  30  may not comprise any wheels. 
     In other embodiments, one or more auxiliary wheels (powered or non-powered), which are movable between stowed positions and deployed positions, may be coupled to the support structure  32 . In some cases, when these auxiliary wheels are located between caster assemblies  60  and contact the floor surface in the deployed position, they cause two of the caster assemblies  60  to be lifted off the floor surface thereby shortening a wheel base of the patient support apparatus  30 . A fifth wheel may also be arranged substantially in a center of the base  34 . 
     Referring to  FIGS. 2 and 3 , illustrations of the base  34  and other parts of the support structure  32  are shown. The base  34  of the support structure  32  is configured to support the patient support deck  38  from a ground surface. The illustrated base frame assembly  35  of the base  34  generally comprises a first frame assembly  74  (also referred to as an “outer frame assembly”) and a second frame assembly  76  (also referred to as an “inner frame assembly”). The first frame assembly  74  comprises a pair of outer frame support members  78  and a pair of cross support members  80 . Each outer frame support member  78  extends along (e.g., substantially parallel to) the longitudinal axis L. The cross support members  80  each extend between the outer frame support members  78  along (e.g., parallel to) a transverse axis T. The wheels  58  are coupled to the first frame assembly  74  to facilitate movement of the base  34  along the ground surface, and are arranged at the ends of the cross support members  80 . 
     The second frame assembly  76  comprises a pair of inner frame support members  82  that each extend along (e.g., parallel to) the longitudinal axis L. One or more lift arms  72  are coupled to the second frame assembly  76  between the deck support frame  36  and the inner frame support members  82  for coupling the patient support deck  38  to the inner frame support members  82 . 
     The patient support apparatus  30  comprises a load cell assembly, generally indicated at  84 , configured to sense weight applied to the first frame assembly  74  by the second frame assembly  76 , as described in greater detail below. In the representative embodiments illustrated herein, the patient support apparatus  30  employs a total of four load cell assemblies  84  which each support the second frame assembly  76  relative to the first frame assembly  74 . More specifically, one load cell assembly  84  is coupled to each end of both of the inner frame support members  82  such that load cell assemblies  84  are arranged in each of the four quadrants of the base  34 . However, and as will be appreciated from the subsequent description below, other arrangements and/or quantities of load cell assemblies  84  are contemplated by the present disclosure. 
     In some embodiments, the patient support apparatus  30  may employ a weigh scale system that comprises a computer control system coupled in communication with one or more of the load cell assemblies  84  for measuring a weight of a patient based on signals received from the load cell assemblies  84 . Additionally or alternatively, the computer control system may comprise one or more microcontrollers, field programmable gate arrays, systems on a chip, discrete circuitry, and/or other suitable hardware, software, or firmware that is capable of carrying out the functions described herein. The computer control system may be carried on-board the patient support apparatus  30 , or may be remotely located. 
     Referring to  FIGS. 4-12 , illustrations of one of the load cell assemblies  84  are shown. As is best shown in  FIGS. 6-7 , the illustrated load cell assembly  84  comprises a load cell support assembly  86  and a load cell element  88 . In the representative embodiments illustrated herein, the load cell support assembly  86  is coupled to the first frame assembly  74 , and the load cell element  88  is coupled to the second frame assembly  76 . However, it will be appreciated that this relationship could be inverted for one or more of the load cell assemblies  84  in certain embodiments, such that the load cell support assembly  86  could be to the second frame assembly  76 , and the load cell element  88  could be coupled to the first frame assembly  74  (not shown). Other configurations are contemplated. 
     As noted above, in the representative embodiments illustrated herein, the load cell support assembly  86  is coupled to the first frame assembly  74 , and the load cell element  88  is coupled to the second frame assembly  76 . More specifically, the load cell element  88  is coupled to one of the inner frame support members  82 . The load cell element  88  is mounted onto the load cell support assembly  86  such that the second frame assembly  76  is movable with respect to the first frame assembly  74  along two axes of translation (e.g., first and second axe of translation  85 ,  87 ; see  FIG. 11 ) and is pivotable with respect to the first frame assembly  74  about three axes of rotation (e.g., first, second, and third axes of rotation  90 ,  92 ,  94 ; see  FIG. 11 ). Each of the components and axes introduced above will be described in greater detail below. 
     Referring to  FIG. 7 , the load cell element  88  generally comprises a load cell beam element  96 , a mounting bar  98 , and a foot pad  100 . The load cell beam element  96  comprises a substantially rectangular cell body  102  that extends between a first end  104  and an opposite second end  106 . A connector assembly  108  extends outwardly from the second end  106  and is configured to be connected (e.g., via wired electrical communication) to the computer control system of the patient support apparatus  30  to transmit data indicating loads sensed by the load cell beam element  96 . To this end, the load cell beam element  96  of the load cell element  88  may comprise one or more strain gauges (not shown, but generally known in the related art) disposed in electrical communication with the connector assembly  108 . Here, those having ordinary skill in the art will recognize the illustrated load cell beam element  96  as being of the “single end shear beam load cell” type, configured so as to be supported via the mounting bar  98  adjacent the second end  106  and loaded via the load cell support assembly  86  adjacent the first end  104 . However, it will be appreciated that other configurations are contemplated, and the load cell element  88  could be of other types, configurations, and the like. 
     The mounting bar  98  is coupled to an upper surface  110  of the load cell beam element  96  (e.g., via one or more fasteners; not shown in detail) and extends outwardly from the second end  106  of the cell body  102 . The mounting bar  98  is also coupled to the second frame assembly  76  (e.g., to the inner frame support member  82 ) to support the load cell beam element  96 . In some embodiments, such as shown in  FIG. 6 , the second frame assembly  76  may comprise an inner surface  112  that defines a frame cavity  114  extending along the length of the inner frame support member  82 , with a frame opening  116  defined at each end of the inner frame support member  82 . Here, the load cell assembly  84  is positioned substantially within the frame cavity  114  and extends outwardly from the inner frame support member  82  through the frame opening  116  and towards the first frame assembly  74 . The mounting bar  98  may be coupled to the inner surface  112  of the inner frame support member  82  with one or more fasteners  118  (see  FIG. 6 ) that extend through an outer surface of the inner frame support member  82 . However, other configurations are contemplated. 
     The foot pad  100  is coupled to the first end  104  of the load cell beam element  96  and is mounted onto the load cell support assembly  86  for movement relative thereto, as described in greater detail below. The foot pad  100  extends outwardly from a lower surface  120  of the load cell beam element  96  along a foot pad centerline axis  122 . In some embodiments, the load cell element  88  is coupled to the inner frame support member  82  such that the foot pad  100  extends outwardly from the load cell beam element  96  along (e.g., parallel to) the vertical axis V. As shown in  FIG. 8 , the foot pad  100  comprises a body  124  having a substantially cylindrical shape, a threaded fastening member  126  extending outwardly from a first end  128  of the body  124  along the foot pad centerline axis  122 , and an arcuate contact surface  130  defined along the second end  132  of the body  124 . The arcuate contact surface  130  is sized and shaped to contact the load cell support assembly  86  and enable the load cell element  88  to pivot with respect to the load cell support assembly  86  about the three axes of rotation  90 ,  92 ,  94  (see  FIG. 11 ). 
     The threaded fastening member  126  is sized and shaped to be received within a corresponding threaded opening  134  defined along the lower surface  120  of the load cell beam element  96  to facilitate coupling the foot pad  100  to the load cell beam element  96 . A plurality of planar surfaces  136  may also be defined along a perimeter of the body  124  to enable a caregiver to rotate the foot pad  100  using a wrench, or other suitable tool, to couple the foot pad  100  to the load cell beam element  96 . In some embodiments, such as is shown in  FIGS. 6-7 , the load cell beam element  96  may comprise a recessed portion  138  defined along an outer surface of the first end  104  of the cell body  102 . Here, the recessed portion  138  comprises the corresponding threaded opening  134  and is sized and shaped to receive the foot pad  100  therein. 
     The load cell support assembly  86  comprises a wear plate  140  and a mounting shoe  142 . The wear plate  140  is coupled to the first frame assembly  74  and comprises a substantially planar body  144  and one or more mounting clips  146  that extend outwardly from the planar body  144 . The mounting clips are sized and shaped to facilitate coupling the wear plate  140  to the first frame assembly  74 . The mounting shoe  142  is slideably mounted on top of the outer surface  145  of the wear plate  140  such that the mounting shoe  142  is slideable along the outer surface  145  of the wear plate  140  along the two axes of translation (e.g., the first and second axes of translation  85 ,  87 ; see  FIG. 11 ). Here, the mounting shoe  142  comprises a substantially disk-shaped body  148  having a concave outer surface  150  defined along a first side  152  of the disk-shaped body  148 , and a planar mounting surface  154  defined along an opposite second side  156  of the disk-shaped body  148 . The planar mounting surface  154  is sized and shaped to contact the outer surface  145  of the wear plate  140  and enable the mounting shoe  142  to slide along the outer surface  145  of the wear plate  140 . The concave outer surface  150  is sized and shaped to receive the foot pad  100  thereon to support the load cell element  88 . 
     As shown in  FIGS. 11-12 , the foot pad  100  is mounted onto the mounting shoe  142  such that the arcuate contact surface  130  contacts the concave outer surface  150  of the mounting shoe  142  to enable the load cell element  88  to pivot with respect to the mounting shoe  142  about the three axes of rotation  90 ,  92 ,  94  (see  FIG. 11 ). 
     During operation, as a patient is loaded onto the patient support apparatus, the load cell assembly  84  enables movement of the second frame assembly  76  with respect to the first frame assembly  74 . Here, for example, the mounting shoe  142  slides along the outer surface  145  of the wear plate  140  to enable the load cell element  88  and the inner frame support member  82  to move with respect to the first frame assembly  74  in a longitudinal direction (represented by arrow  158  in  FIG. 11 ) along the first axis of translation  85  (e.g., parallel to the longitudinal axis L) and in a transverse direction (represented by arrow  160  in  FIG. 11 ) along the second axis of translation  87  (e.g., parallel to the transverse axis T). In addition, the load cell assembly  84  enables the second frame assembly  76  to pivot with respect to the first frame assembly  74  about the three axes of rotation  90 ,  92 ,  94 . Here, for example, the arcuate contact surface  130  of the foot pad  100  is mounted onto the concave outer surface  150  of the mounting shoe  142  to enable the load cell element  88  to pivot with respect to the mounting shoe  142  about the three axes of rotation  90 ,  92 ,  94 . As shown in  FIGS. 11-12 , with the foot pad  100  mounted onto the mounting shoe  142 , the load cell element  88  and the inner frame support member  82  of the second frame assembly  76  may pivot with respect to the first frame assembly  74  about the first axis of rotation  90  (pivoting represented by arrow  157  in  FIG. 11 ) which may be parallel to the longitudinal axis L, about the second axis of rotation  92  (pivoting represented by arrow  159  in  FIG. 11 ) which may be parallel to the transverse axis T, and about the third axis of rotation  94  (pivoting represented by arrow  161  in  FIG. 11 ) which may be parallel to the vertical axis V. 
     In some embodiments, the load cell support assembly  86  may also comprise a support bracket  162  that is coupled to one of the cross support members  80  of the first frame assembly  74 . The support bracket  162  comprises a substantially rectangular cross-sectional shape having an inner surface  164  that defines a bracket cavity  166  extending therethrough. The wear plate  140 , the mounting shoe  142 , and the foot pad  100  are positioned substantially within the bracket cavity  166  via the mounting clips  146  coupling the wear plate  140  to the support bracket  162 . The support bracket  162  may also comprise pin openings  168  for receiving a capture pin  170 . The capture pin  170  is sized, shaped, and orientated to limit a movement of the inner frame support member  82  along the longitudinal axis L. To this end, as shown in  FIG. 12 , the inner frame support member  82  may comprise a notch  172  defined along an outer surface of the inner frame support member  82 . Here, the load cell element  88  is mounted onto the mounting shoe  142  such that that capture pin  170  is positioned within the notch  172  and a gap  174  is defined between the capture pin  170  and the outer surface of the inner frame support member  82 . As the inner frame support member  82  is moved in the longitudinal direction  158 , the inner frame support member  82  may contact the capture pin  170  to limit further movement in the longitudinal direction  158 . It will be appreciated that each corner of the base  34  may employ a capture pin  170  and support bracket  162  adjacent to a respective load cell assembly  84 . However, other configurations are contemplated. 
     In some embodiments, the foot pad  100  may be formed of material comprising 304 SST round bar ASTM A276/A479/A580, the mounting shoe  142  may be formed of material comprising 1144 CD stressproof ASTM A311 electroless nickel plating, and the wear plate  140  may be formed of material comprising annealed  1070 - 1075  strip, austempered to RC 40-45 after forming, nickel plated. The foot pad  100 , mounting shoe  142 , and wear plate  140  may also be formed of other suitable materials that enable the load cell assembly  84  to function as described herein. 
     In this way, the embodiments of the present disclosure afford significant opportunities in connection with patient support apparatuses  30  by, among other things, ensuring that load cell beam elements  96  can be utilized reliably, consistently, and durably. More specifically, it will be appreciated that the load cell assemblies  84  disclosed herein can be employed without utilizing complex load cell beams, in that the components of the load cell element  88  and the load cell support assembly  86  cooperate to facilitate the relative movement between the first and second frame assemblies  74 ,  76  which, among other things, prevents damage to the load cell beam elements  96  and ensures consistent and reliable operation of the load cell assemblies  84 . 
     It will be further appreciated that the terms “include,” “includes,” and “including” have the same meaning as the terms “comprise,” “comprises,” and “comprising.” Moreover, it will be appreciated that terms such as “first,” “second,” “third,” and the like are used herein to differentiate certain structural features and components for the non-limiting, illustrative purposes of clarity and consistency. 
     Several embodiments have been discussed in the foregoing description. However, the embodiments discussed herein are not intended to be exhaustive or limit the invention to any particular form. The terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations are possible in light of the above teachings and the invention may be practiced otherwise than as specifically described.