Patent Publication Number: US-2023142871-A1

Title: Patient Support Apparatus With Battery Retention System

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The subject patent application claims priority to, and all the benefits of, U.S. Provisional Pat. Application No. 63/277,318, filed on Nov. 9, 2021, the entire contents of which are incorporated by reference herein. 
    
    
     BACKGROUND 
     Patient support apparatuses, such as hospital beds, stretchers, cots, tables, wheelchairs, chairs, and the like are used to help caregivers facilitate care of patients in a health care setting. Conventional patient support apparatuses comprise a base, a support frame, a patient support deck operatively attached to the support frame. Certain patient support apparatuses may also include one or more powered devices, such as a powered lift assembly for lifting and lowering the support frame relative to the base. 
     Power for the powered actuators may be provided via an extension cord or tether plugged into a wall outlet, or by a removable battery carried by the patient support apparatus. During use, the patient support apparatus may occasionally be jostled, knocked, bumped, or otherwise subjected to forces that may cause the battery to undesirably become disconnected from the patient support apparatus. With certain types of battery configurations, however, latches which surely fasten the battery so as to prevent unintentional removal may also sometimes make it difficult for a caregiver to quickly and easily replace a discharged battery. 
     While conventional patient support apparatuses have generally performed well for their intended purpose, there remains a need in the art for a patient support apparatus that overcomes the disadvantages in the prior art. 
     SUMMARY 
     In one aspect a patient support apparatus having a removable battery is disclosed. The patient support apparatus may comprise a support frame with a patient support deck disposed on the support frame and a lift assembly having a powered lift actuator to adjust the support frame. The patient support apparatus may further comprise a battery retention system coupled to the support frame. The battery retention system may comprise a mount base and a battery receiver pivotably coupled to the mount base for movement between a locked state and an unlocked state. The battery receiver may define a channel configured for engaging the battery and an aperture in communication with the channel. The battery retention system may further comprise an electrical interface coupled to the battery receiver and configured for engaging the battery and a latch pawl interposed between the battery receiver and the mount base adjacent to the aperture. The latch pawl may be arranged for movement between a retracted position, in which the latch pawl is substantially outside the channel, and an extended position, in which the latch pawl is at least partially disposed in the channel. The latch pawl may be engaged with the mount base such that pivoting movement of the battery receiver from the locked state to the unlocked state moves the latch pawl from the extended position toward the retracted position for permitting removal of the battery from the battery retention system. 
     In another aspect a patient support apparatus is disclosed. The patient support apparatus may comprise a support frame with a patient support deck disposed on the support frame and a lift assembly having a powered lift actuator to adjust the support frame. The patient support apparatus may further comprise a battery configured for providing power to the lift assembly and a battery retention system coupled to the support frame. The battery retention system may comprise a mount base and a battery receiver pivotably coupled to the mount base for movement between a locked state and an unlocked state. The battery receiver may further define an aperture in communication with the channel. The battery retention system may further comprise an electrical interface coupled to the battery receiver and configured for engaging the battery and a latch pawl interposed between the battery receiver and the mount base adjacent to the aperture. The latch pawl may be arranged for movement between a retracted position, in which the latch pawl is substantially outside the channel, and an extended position, in which the latch pawl is at least partially disposed in the channel. The latch pawl may be engaged with the mount base such that pivoting movement of the battery receiver from the locked state to the unlocked state moves the latch pawl from the extended position toward the retracted position for permitting removal of the battery from the battery retention system. 
     Any of the above aspects can be combined in full or in part. Any features of the above aspects can be combined in full or in part. Any of the above implementations for any aspect can be combined with any other aspect. Any of the above implementations can be combined with any other implementation whether for the same aspect or a different aspect. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Advantages of the present disclosure will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings. 
         FIG.  1    is a perspective view of a patient support apparatus having a base, a support frame supporting a patient support surface, a lift assembly, and a battery retention system coupled to the support frame. 
         FIG.  2    is a perspective view of an exemplary battery retention system and a battery for use with a patient support apparatus. 
         FIG.  3    is a top side view of the battery retention system and battery of  FIG.  2    with a battery receiver in a locked state and latch pawl shown in phantom. 
         FIG.  4    is a top side view of the battery retention system and battery of  FIG.  3    with the battery receiver in an unlocked state. 
         FIG.  5    is a cross-sectional side view of the battery retention system and battery of  FIG.  2    showing the battery receiver and the latch pawl in an extended position. 
         FIG.  6    is a cross-sectional perspective view of the battery retention system and battery of  FIG.  2    with the battery receiver in the locked state and the latch pawl in the extended position. 
         FIG.  7    is a modified cross-sectional perspective view of the battery retention system and battery of  FIG.  6    with the battery receiver in the unlocked state and the latch pawl in the retracted position. 
         FIG.  8    is a bottom-side perspective view of the battery retention system of  FIG.  6    with the battery receiver in the unlocked state, the latch pawl in the retracted position and the battery removed from the battery receiver. 
         FIG.  9    is an exploded perspective view of the battery retention system of  FIG.  2    showing the battery receiver and latch pawl spaced from a mount base. 
         FIG.  10    is an exploded side view of the battery retention system of  FIG.  9    showing the battery receiver, latch pawl, and a latch spring spaced from the mount base. 
         FIG.  11    is a bottom side perspective view of another battery retention system and battery for use with a patient support apparatus. 
         FIG.  12    is a cross-sectional side view of the battery retention system and battery of  FIG.  10    showing a battery receiver in a locked state and a latch pawl in an extended position. 
         FIG.  13    is a cross-sectional side view of the battery retention system and battery of  FIG.  12    showing the battery receiver in an unlocked state and a latch pawl in a retracted position. 
         FIG.  14    is a cross-sectional side view of the battery retention system of  FIG.  12    showing the battery receiver in an unlocked state and a latch pawl in a retracted position with the battery removed from the battery receiver. 
         FIG.  15    is an exploded perspective view of the battery retention system of  FIG.  14    showing the battery receiver, latch pawl, and a latch spring spaced from a mount base. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG.  1   , an exemplary patient support apparatus  100  is shown for supporting a patient in a health care setting. The patient support apparatus  100  illustrated in  FIG.  1    comprises a hospital bed. In other versions, however, the patient support apparatus  100  may comprise a stretcher, cot, table, wheelchair, or similar apparatus utilized in the care of a patient. 
     A support structure  102  provides support for the patient. The support structure  102  illustrated in  FIG.  1    comprises a base  104  movable about a floor surface, a support frame  106 , and a patient support deck  108 . The base  104  may comprise a base frame  110 . The patient support deck  108  may be disposed on the support frame  106 . The support frame  106  and the patient support deck  108  are spaced above the base  104  in  FIG.  1   . The patient support deck  108  provides a patient support surface  112  upon which the patient is supported. 
     A mattress (not shown) may be disposed on the patient support deck  108  during use. The mattress comprises a secondary patient support surface upon which the patient is supported. The base  104 , support frame  106 , patient support deck  108 , and patient support surfaces  112  each have a head-end  114  and a foot-end  116  corresponding to designated placement of the patient’s head and feet on the patient support apparatus  100 . The construction of the support structure  102  may take on any suitable design and is not limited to that specifically set forth above. In addition, the mattress may be omitted in certain versions, such that the patient rests directly on the patient support surface  112 . 
     As will be discussed in greater detail below, the patient support deck  108  has at least one deck section  118  arranged for movement relative to the support frame  106  to support the patient in different positions, orientations, and the like. The deck sections  118  of the patient support deck  108  provide the patient support surface  112  upon which the patient is supported. More specifically, in the representative version of the patient support apparatus  100  illustrated in  FIG.  1   , the patient support deck  108  has four deck sections  118 , which cooperate to define the patient support surface  112 : a fowler section  120  (or back section), a seat section  122 , a leg section  124 , and a foot section  126 . Here, the seat section  122  is fixed to the support frame  106  and is not arranged for movement relative thereto. However, it will be appreciated that the seat section  122  could be movable relative to other deck sections  118  in some versions. Conversely, the fowler section  120  and the leg section  124  are arranged for movement relative to each other and to the support frame  106 , as described in greater detail below, and the foot section  126  is arranged to move partially concurrently with the leg section  124 . Other configurations and arrangements are contemplated. 
     Side rails  128 ,  130 ,  132 ,  134  are coupled to the support frame  106  and are thereby supported by the base  1104 . A first side rail  128  is positioned at a right head end of the support frame  106 . A second side rail  130  is positioned at a right foot end of the support frame  106 . A third side rail  132  is positioned at a left head end of the support frame  106 . A fourth side rail  134  is positioned at a left foot end of the support frame  106 . If the patient support apparatus  100  is a stretcher or a cot, there may be fewer side rails. The side rails  128 ,  130 ,  132 ,  134  are movable to a raised position in which they block ingress and egress into and out of the patient support apparatus  100 , 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  100  may not include any side rails. The Applicant has described versions of patient support apparatuses having side rails equipped with actuators for “motorized” movement in U.S. Pat. Application Publication No. US 2017/0172829 A1, the disclosure of which is hereby incorporated by reference in its entirety. Other configurations are contemplated. 
     The side rails  128 ,  130 ,  132 ,  134  could be of any suitable type, arrangement, or configuration sufficient to selectively limit patient ingress/egress from the patient support apparatus  100 . It will be appreciated that there may be fewer side rails for certain versions, such as where the patient support apparatus  100  is realized as a stretcher or a cot. Moreover, it will be appreciated that in certain configurations, the patient support apparatus  100  may not include any side rails. Similarly, it will be appreciated that side rails may be attached to any suitable component or structure of the patient support apparatus  100 . Furthermore, in certain versions the side rails are coupled to one of the deck sections  40  for concurrent movement. 
     A headboard  136  and a footboard  138  may be coupled to the support frame  106 . In other versions, when the headboard  136  and footboard  138  are included, the headboard  136  and footboard  138  may be coupled to other locations on the patient support apparatus  100 , such as the base  104 . In still other versions, the patient support apparatus  100  may not include the headboard  136  and/or the footboard  138 . 
     One or more grips  140  (or “handles”) are shown in  FIG.  1    as being integrated into the side rails  128 ,  130 ,  132 ,  134 , the headboard  136 , and the footboard  138 . As is described in greater detail below, the grips  140  formed in the side rails  128 ,  130 ,  132 ,  134  are arranged to help facilitate patient egress from the patient support apparatus  100 . It will be appreciated that the grips  140  formed in the side rails  128 ,  130 ,  132 ,  134 , as well as the grips  140  formed in the headboard  136  and the footboard  138 , can also be used by a caregiver to facilitate movement of the patient support apparatus  100  over floor surfaces. Additional grips  140  may be integrated into other components of the patient support apparatus  100 , such as the support frame  106 . The grips  140  are shaped so as to be grasped by the patient or the caregiver. It will be appreciated that the grips  140  could be integrated with or operatively attached to any suitable portion of the patient support apparatus  100  or may be omitted from certain parts of the patient support apparatus  100  in certain versions. 
     In addition to the headboard  136  the patient support apparatus may further comprise user input handles  152 . The user input handles  152  are operable by the caregiver to control various functions of the patient support apparatus such as powered drive wheels, steering, braking, and the like. The user input handles  152  may further comprise buttons for selecting between different operation modes or other user configurable options that change operating parameters of the patient support apparatus  100 . 
     Wheels  142  are coupled to the base  104  to facilitate transportation over floor surfaces. The wheels  142  are arranged in each of four quadrants of the base  104  adjacent to corners of the base  104 . In the version shown in  FIG.  1   , the wheels  142  are caster wheels able to rotate and swivel relative to the support structure  102  during transport. Here, each of the wheels  142  forms part of a caster assembly  144  that is mounted to the base  104 . It should be understood that various configurations of the caster assemblies  144  are contemplated. In addition, in some versions, the wheels  142  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  100  may comprise four non-powered, non-steerable wheels, along with one or more powered wheels. In some cases, the patient support apparatus  100  may not include any wheels. In other versions, one or more auxiliary wheels (powered or non-powered), which are optionally movable between stowed positions and deployed positions, may be coupled to the support structure  102 . In some cases, when auxiliary wheels are located between caster assemblies  144  and contact the floor surface in the deployed position, they cause two of the caster assemblies  144  to be lifted off the floor surface, thereby shortening a wheelbase of the patient support apparatus  100 . A fifth wheel  154  may also be arranged substantially in a center of the base  104 . 
     The patient support apparatus  100  further comprises a lift assembly, generally indicated at  146 , which operates to raise and lower the support frame  106  relative to the base  104  which, in turn, moves the patient support deck  108  relative to the base  104  between a plurality of lift configurations, including a lowered lift configuration where the patient support deck  108  is positioned adjacent to the base  104 , a raised lift configuration where the patient support deck  108  is elevated vertically above the base  104 , or any desired vertical position therebetween. To this end, the lift assembly  146  may comprise powered lift actuators, such as a head-end lift actuator and a foot-end lift actuator, which are each operatively attached between the support frame  106  and the base  104  and arranged to facilitate movement of the patient support surface  112  with respect to the base  104 . 
     The head-end and foot-end actuators may be realized as linear actuators, rotary actuators, or other types of actuators, and may be electrically, hydraulically, and/or pneumatically operated or combinations thereof. It is contemplated that, in some versions, different arrangements of actuators may be employed, such as with rotary actuators coupled to the base  104  and to the support frame  106  with a linkage extending therebetween. The construction of the lift assembly  146 , the head-end actuator, and/or the foot-end actuator may take on any known or conventional design, and is not limited to that specifically illustrated. By way of non-limiting example, the lift assembly  146  could be arranged with the head-end and foot-end actuators between the base  104  and the support frame  106  in a column configuration to facilitate vertical movement of the patient support deck  108 . 
     As mentioned above, the patient support apparatus  100  may comprise powered drive wheels in addition to a powered lift assembly  146 . In some implementations of the patient support apparatus  100 , these systems may be electrically powered and controlled using energy stored in a battery  160 . The battery  160  may be supported on, or in, the support frame  106  and electrically coupled to the powered drive wheels, powered lift actuators, and a controller (not shown) to provide these and other components with electrical power. One exemplary battery  160 , shown best in  FIGS.  5 - 8   , generally includes a battery housing  162  with a handle  164 , one or more cells (not shown) disposed in the battery housing  162 , and one or more terminals  166  in communication with the cells and supported by the battery housing  162  for engaging a corresponding receiver terminal  226  on the patient support apparatus  100 , as will be discussed in further detail below. It will be appreciated that the representative versions of the battery  162  depicted throughout the drawings are shown generically (e.g., not to scale, without cells, and the like) for illustrative purposes. 
     The battery  160  may comprise one cell or a plurality of cells electrically coupled to one another in order to increase storage capacity or voltage of the battery  160 . The battery  160  may utilize cells having a variety of compositions. For example, the cells may be Lithium-ion type, however other types of battery such Nickel-Cadmium, Nickel-metal hydride, or Lithium polymer are also contemplated. To this end, the battery  160  may be configured to provide a suitable voltage to the terminal  166  by way of different arrangement of the cells (e.g. series, parallel, series-parallel, etc). For example, the battery  160  may provide 3.7 V, 5 V, 6 V, 12 V, 18 V, 36 V, 40 V, 60 V, etc, and combinations thereof. The battery  160  may further be configured for recharging by way of a charging assembly (not shown) connected to a mains power supply or another external battery pack (not shown). The battery  160  may comprise an electrical port (not shown) in addition to the terminal  166  that allows the battery  160  to receive power from the charging assembly. While the port may assume various configurations, in one exemplary version, the electrical port comprises a USB port. In another version, the battery  160  may be configured to be wirelessly recharged via an inductive charging circuit. 
     The battery  160  as shown and described herein is configured to be removed from and attached to the patient support apparatus  100  by a caregiver in order to reduce weight and facilitate untethered (e.g., disconnected from mains power) operation of the patient support apparatus  100 . During operation, a discharged battery may be removed by a caregiver and replaced with a charged battery. Said differently, because a discharged battery can quickly and easily be replaced with a charged battery, lower capacity and smaller volume batteries may be utilized without negatively impacting the usability of the patient support apparatus  100 . 
     The patient support apparatus  100  includes a battery retention system  180  for retaining the battery  160  to the patient support apparatus  100  during use. In the representative version depicted in  FIG.  1   , the battery retention system  180  is illustrated as being operatively attached to the support frame  106  adjacent to the foot-end  116 . However, it will be appreciated that other locations are contemplated. The battery retention system  180  prevents the battery  160  from unintentionally becoming disconnected from the patient support apparatus  100 , which may have undesirable effects on the operation of the patient support apparatus  100 . During use, the patient support apparatus  100  may be jostled, knocked, bumped, or otherwise subjected to forces that may be transferred to the battery  160  causing an undesirable disconnection from the patient support apparatus  100 . The battery retention system  180  prevents this undesirable disconnection by latching the battery  160  through the use of a latch pawl  182  . In order to retract the latch pawl  182 , the battery retention system  180  must be placed in an unlocked state SU, which allows the battery  160  to be removed, as will be discussed in further detail below. 
     Turning now to  FIG.  2   , a perspective view of an exemplary battery retention system  180  and a battery  160  are shown. The battery retention system  180  may comprise a mount base  184  and a battery receiver  186  pivotably coupled to the mount base  184  for movement between a locked state SL and an unlocked state SU. As shown here, the mount base  184  is configured to be coupled to the support frame  106 , but other locations are contemplated as noted above. The mount base  184  may be coupled using fasteners (not shown) via one or more mounting holes  188  defined in the mount base  184 . Alternatively, the mount base  184  may be integrally formed with the support frame  106 , or a cover or housing associated with the support frame  106  or the patient support deck  108 . 
     The battery receiver  186  is movable relative to the mount base  184  between the locked state SL and the unlocked state SU. The pivoting movement of the battery receiver  186  relative to the mount base  184  may occur about a pivot axis  190 . In  FIGS.  2  and  3   , the battery receiver  186  is shown in the locked state SL, in which the battery  160  is secured to the battery retention system  180 . Conversely, in  FIG.  4   , the battery receiver  186  is shown pivoted relative to the mount base  184  about the pivot axis  190  in the unlocked state SU, in which the battery  160  is able to be removed from the battery retention system  180  by a caregiver. In this version, the pivot axis  190  is arranged vertically such that the pivoting movement of the battery receiver  186  moves in a horizontal direction. 
     Referring to  FIGS.  2 - 5   , the mount base  184  may define a pivot hole  192 , which may further define the pivot axis  190 . The pivot hole  192  is arranged in the mount base  184  and extends between a first side  194  and a second side  196  of the mount base  184 . The pivot hole  192  may be sized to receive a portion of the battery receiver  186  to facilitate the pivoting movement. The mount base  184  may further define a guide slot  198  that extends between the first side  194  and the second side  196 . The guide slot  198  shown here has an arcuate shape that is curved about the pivot axis  190 . As with the pivot hole  192 , the guide slot  198  may be sized to receive a portion of the battery receiver  186  for constraining the pivoting movement. The mount base  184  comprises a centering peg  200  protruding from the second side  196  toward the battery receiver  186 . As will be discussed in further detail below the centering peg  200  interacts with the battery receiver  186  to bias its pivoting movement. 
     The mount base  184  further comprises a biasing surface  202  arranged on the second side  196  and oriented toward the battery receiver  186 . The biasing surface  202  may comprise one or more portions at different relative heights and angles. Here, the portions of the biasing surface  202  may take the form of discrete surfaces. For example, an intermediate surface  204  may form one discrete surface of the biasing surface  202  recessed into the second side  196  of the mount base  184  and generally parallel thereto. The biasing surface  202  may further comprise a ramp surface  206  adjacent to the intermediate surface  204  and at an angle thereto. In the implementation of the mount base  184  shown here, the biasing surface may comprise two ramp surfaces  206  arranged on opposing sides of the intermediate surface  204 . As will be discussed below, the biasing surface  202  may interact with the latch pawl  182  in order to move the latch pawl  182  between an extended position PE and a retracted position PR in coordination with the pivoting movement of the battery receiver  186 . Said differently, interaction between the latch pawl  182  and the biasing surface  202  may correspond to the state of the battery receiver  186 , such as with the intermediate surface  204  corresponding to the locked state SL of the battery receiver  186  and the ramp surface  206  corresponding to the unlocked state SU. Other configurations are contemplated. 
     Referring again to  FIGS.  2 - 8   , the battery receiver  186  is shown. The battery receiver  186  is pivotably coupled to the mount base  184  for movement between a locked state SL ( FIG.  3   ) and an unlocked state SU ( FIG.  4   ). The battery receiver  186  has a first side  208  and a second side  210 . The battery receiver  186  is arranged with the first side  208  facing the mount base  184 . On the second side  210 , the battery receiver  186  defines a channel  212  configured for engaging the battery  160  and an aperture  214  extending between the first side  208  and the channel  212 . The channel  212  extends between a first end  216  and a second end  218  in a longitudinal direction along a channel axis  220 . The first end  216  has an opening  222  shaped to receive the battery  160  from the first end  216  in a direction along the channel axis  220 . 
     Here, the battery receiver  186  comprises two rails  224  extending between the first end  216  and the second end  218  and on opposing lateral sides of the channel  212 . The rails  224  engage corresponding slots  168  defined in the battery housing  162 . The rails  224  are generally parallel to the channel axis  220  and support sliding engagement of the battery  160  with the battery receiver  186  along the channel axis  220 . Additionally, when the battery  160  is disposed in the channel  212 , the rails  224  constrain two axes of movement of the battery  160  to limit removal and replacement to one direction along the channel axis  220 . As mentioned above, the battery  160  includes a terminal  166  that engages a corresponding receiver terminal  226  as the battery  160  slides along the rails  224  for enabling power transfer to the patient support apparatus  100 . The receiver terminal  226  is coupled to the battery receiver  186  and arranged at the second end  218  of the channel  212 . The receiver terminal  226  may supported on an inner wall  228  of the battery receiver  186  at the second end of the channel  212 . 
     As best shown in  FIG.  9   , the first side  208  of the battery receiver  186  is depicted spaced from the mount base  184  and the latch pawl  182 . The battery receiver  186  comprises a pivot boss  230  and a guide boss  232 , which protrude from the first side  208  toward the mount base  184 . The pivot boss  230  is aligned with and extends along the pivot axis  190  to engage the pivot hole  192  of the mount base  184 . Similarly, the guide boss  232  is spaced from the pivot axis  190  and shaped to engage the guide slot  198 . The guide boss  232  slides within the guide slot  198  as the battery receiver  186  pivots relative to the mount base  184 . The pivot boss  230  and the guide boss  232  are both shaped to facilitate rotational movement about the pivot axis  190  and are arranged such that the pivot axis  190  is perpendicular to the channel axis  220 . The pivot boss  230  and the guide boss  232  are further configured to receive fasteners  234  that couple the battery receiver  186  to the mount base  184 . 
     The battery receiver  186  further defines a centering slot  236  in the first side  208 . The centering slot  236  has an arcuate shape centered about the pivot axis  190  and may be arranged radially outward of the guide boss  232 . The centering slot  236  is further arranged to receive the centering peg  200  of the mount base  184  such that the centering peg  200  slides within the centering slot  236  as the battery receiver  186  pivots between the locked state SL and the unlocked state SU. A return spring  238  may be disposed in the centering slot  236  between the centering peg  200  and the centering slot  236 . The return spring  238  exerts a force on the mount base  184  via the centering peg and the battery receiver  186  to bias the battery receiver  186  toward the locked state SL. In this version, the battery retention system  180  comprises two return springs  238  arranged between the centering peg  200  and opposing sides of the centering slot  236 . As will be described below, an arrangement of two return springs  238  may be implemented in order to bias the battery receiver  186  toward the locked state SL in both a clockwise direction and a counterclockwise direction. Alternative arrangements are contemplated. 
     With continued reference to  FIG.  9   , the battery receiver  186  further defines a latch recess  240  in the first side  208 . The latch pawl  182  is disposed in the latch recess  240  between the battery receiver  186  and the mount base  184 . The latch recess  240  is in communication with the aperture  214  to facilitate movement of the latch pawl  182  into the channel  212 . The latch recess  240  has two pawl sockets  242  arranged on opposing sides and configured for pivotably supporting the latch pawl  182 . 
     As mentioned above, and shown in  FIGS.  5 - 10   , the battery retention system  180  comprises the latch pawl  182  interposed between the battery receiver  186  and the mount base  184 . The latch pawl  182  is arranged for movement between a retracted position PR ( FIG.  7   ) and an extended position PE ( FIG.  6   ). In the retracted position PR, the latch pawl  182  is arranged substantially outside the channel  212 . In the extended position PE, the latch pawl  182  is at least partially disposed in the channel  212 . More specifically, the latch pawl  182  is disposed in the latch recess  240  and movable into and out of the channel  212  for selectively permitting removal of the battery  160  from the battery retention system  180 . To this end, the latch pawl  182  may comprise a latch body  244  having a finger portion  246  arranged for engagement with the mount base  184  and a clasp portion  248  for engaging the battery  160 . 
     The latch pawl  182  may further comprise trunnion arms  250  protruding from the latch body  244  along a latch axis  252 . The latch pawl  182  is pivotable about the latch axis  252  between the extended position PE ( FIGS.  5  and  6   ) and the retracted position PR ( FIG.  7   ). Referring specifically to  FIG.  9   , where the latch pawl  182  is shown spaced from the battery receiver  186 , the trunnion arms  250  are visible on opposing sides of the latch body  244 . The latch axis  252  generally delineates the finger portion  246  and the clasp portion  248 . It is contemplated that the latch axis  252  may not evenly divide the latch body  244  into the finger portion  246  and the clasp portion  248 . In the implementation shown, the length of the finger portion  246  and the clasp portion  248  are unequal. More specifically, a distance between the latch axis  252  and an end of the finger portion  246  is less than a distance between the latch axis  252  and an end of the clasp portion  248 . 
     As mentioned above, the latch pawl  182  is disposed in the latch recess  240  such that the trunnion arms  250  are arranged in the pawl sockets  242  for supporting pivoting movement of the latch pawl  182  about the latch axis  252 . In use, as the latch pawl  182  moves from the extended position PE to the retracted position PR, the finger portion  246  moves away from the second side  196  of the mount base  184  (e.g., toward the bottom of  FIG.  5   ), and the clasp portion  248  moves toward the second side  196  of the mount base  184  (e.g., toward the top of  FIG.  5   ). Conversely, as the latch pawl  182  moves from the retracted position PR to the extended position PE, the finger portion  246  moves toward the second side  196  of the mount base  184  (e.g., toward the top of  FIG.  5   ) and the clasp portion  248  moves away from the second side  196  of the mount base  184  (e.g., toward the bottom of  FIG.  5   ). 
     Further referencing  FIGS.  5 - 7  and  9   , the latch pawl  182  may further comprise a follower surface  254  protruding from the finger portion  246 . The follower surface  254  is arranged so as to generally protrude toward the second side  196  of the mount base  184  and is configured for engagement with the biasing surface  202 . The follower surface  254  may be arranged near the end of the finger portion  246  or spaced inwardly toward the latch axis  252 . A distance D1 between the follower surface  254  and the latch axis  252  may be varied to optimize the ratio between pivoting movement of the battery receiver  186  and the latch pawl  182 . In the implementation shown here, the distance D1 between the latch axis  252  and the follower surface  254  is less than a distance D2 between the latch axis  252  and the end of the clasp portion  248 . As will be discussed below, engagement between the follower surface  254  and the biasing surface  202  controls movement of the latch pawl  182  between the extended position PE and the retracted position PR. More specifically, as the battery receiver  186  is pivoted toward the unlocked state SU, the follower surface  254  engages the ramp surface  206 , which moves the finger portion  246  toward the battery receiver  186  and pivots the latch pawl  182  toward the retracted position PR such that the clasp portion  248  is substantially outside the channel  212 . As the battery receiver  186  is pivoted toward the locked state SL, the follower surface  254  may move out of engagement with the ramp surface  206 , which permits the finger portion  246  to move toward the mount base  184  and to pivot the latch pawl  182  into the extended position PE with the clasp portion  248  at least partially disposed in the channel  212 . 
     Control of the latch pawl  182  movement is facilitated by a latch spring  256  disposed between the latch pawl  182  and the battery receiver  186 . The battery retention system  180  may utilize the latch spring  256  to urge the latch pawl  182  into engagement with the mount base  184 . Said differently, the latch spring  256  may be arranged to bias the latch pawl  182  toward the extended position PE. As shown in the illustrated version, the latch spring  256  is disposed between the finger portion  246  of the latch body  244  and the battery receiver  186 . Pivoting the battery receiver  186  toward the unlocked state SU causes the follower surface  254  to contact the ramp surface  206 , which pivots the latch pawl  182 . As the latch pawl  182  pivots toward the retracted position PR, the latch spring  256  is compressed. From the unlocked state SU, pivoting the battery receiver  186  toward the locked state SL allows the follower surface  254  to disengage from the ramp surface  206  and the latch spring  256  to pivot the latch pawl  182  toward the extended position PE. In some implementations, engagement between the follower surface  254  and the intermediate surface  204  may correspond to the extended position PE of the latch pawl  182 . In other implementations, the intermediate surface  204  may be sufficiently recessed in the mount base  184  (e.g., spaced from the second side  196 ) such that the finger portion  246  of the latch pawl  182  contacts the mount base  184  without the follower surface  254  engaging the intermediate surface  204 . Other configurations are contemplated. 
     With renewed reference to  FIGS.  3  and  4   , the battery retention system  180  is shown in operation to remove the battery  160 . In  FIG.  3   , the battery receiver  186  is shown in the locked state SL in which the battery  160  is secured in the channel  212  preventing unintended removal. In  FIG.  4   , the battery receiver  186  is pivoted (by a user, not shown) into the unlocked state SU in which the battery  160  is able to be removed from the channel  212 . When the battery receiver  186  is in the unlocked state SU, the return spring  238  is compressed by the centering peg  200  in the centering slot  236 . Compression of the return spring  238  biases the battery receiver  186  back to the locked state SL when a user releases the battery receiver  186 . Here, the user has pivoted the battery receiver  186  in an anti-clockwise direction, which compresses the return spring  238  opposite the pivoting direction (e.g., on the right side of  FIG.  4   ). From the locked state SL, the user may alternatively pivot the battery receiver  186  in a clockwise direction in order to move the battery receiver  186  into the unlocked state SU. Said differently, the battery receiver  186  is configured such that the user may move the battery receiver  186  into the unlocked state SU by pivoting in the clockwise direction and the anti-clockwise direction, as shown by the arrows  258  in  FIG.  3   . 
     The guide boss  232  moves between opposing ends of the guide slot  198  to constrain the movement of the battery receiver  186 . The unlocked state SU generally corresponds to the guide boss  232  adjacent to or engaging one of the opposing ends of the guide slot  198 . The locked state SL generally corresponds to the guide boss  232  being positioned near a midpoint of the guide slot  198 . As such, when the battery receiver  186  is pivoted anti-clockwise by the user into the unlocked state SU as shown in  FIG.  4   , the battery receiver  186  is capable of two clockwise pivoting movements, illustrated by the arrows  260  in  FIG.  4   . Said differently, from a first unlocked state SU, the battery receiver  186  may be pivoted in the opposite direction, through the locked state SL, and into a second unlocked state SU. In the second unlocked state SU, the opposite return spring  238  is compressed. In other words, each return spring  238  returns the battery receiver  186  to the locked state SL from one of the unlocked state SUs. 
     As mentioned above, the battery retention system  180  may be used to facilitate removing and replacing a discharged battery from the patient support apparatus  100 . To remove the battery  160 , the caregiver or other user may grasp the handle  164  (or another part of the battery  160 ) and pivot the battery  160  and battery receiver  186  in either direction indicated by the arrow  258  in  FIG.  3   . Pivoting the battery receiver  186  moves the latch pawl  182  such that the follower surface  254  engages one of the ramp surfaces  206 . As the battery receiver  186  continues to pivot, the latch pawl  182  pivots about the latch axis  252  with the finger portion  246  compressing the latch spring  256  and the clasp portion  248  moving out of the battery notch  170 . When the clasp portion  248  is sufficiently outside the channel  212  the battery  160  may be slid along the rails  224  and removed from the battery receiver  186 . When the user releases the battery receiver  186  and removes the battery  160 , the battery receiver  186  is moved by the return spring  238  into the locked state SL and the latch pawl  182  pivots back to the extended position PE. 
     The battery  160  may be reinstalled by first aligning the slots  168  with the rails  224  of the channel  212  and sliding the battery  160  through the opening  222 . As the battery  160  approaches the aperture  214 , the battery housing  162  engages the clasp portion  248  of the latch pawl  182 . Sliding the battery  160  further along the channel axis  220  urges the clasp portion  248  out of the channel  212 . When the battery  160  is fully inserted in the channel  212  such that the battery terminal  166  and the receiver terminal  226  are electrically engaged, the latch pawl  182  is able to pivot into the extended position PE with the clasp portion  248  in the notch  170  of the battery  160 . Interaction between the clasp portion  248  and the notch  170  prevents the battery  160  from being removed from the battery retention system  180 . 
     Some instances of the battery retention system  180  may be implemented and utilized to not only prevent unintended removal of the battery  160 , but also for asset protection. Because the battery  160  is prevented from being removed from the patient support apparatus  100 , the battery retention system  180  may be configured to prevent an unauthorized user from removing the battery  160  (e.g., theft). If the battery receiver  186  is prevented from being pivoted out of the locked state SL and into the unlocked state SU, a user would be unable to remove the battery  160 . The battery receiver  186  may be secured in the locked state SL using, for example, a locking pin (not shown) movable with a physical security device, such as a key. Other physical security devices may be implemented in the alternative. For example, the physical security device may be a combination lock, a hidden lever, a magnetic toggle, and the like. In some versions, the locking pin may be controlled by an electronic solenoid, which may move the locking pin into and out of engagement with the battery receiver  186  and the mount base  184  to prevent relative movement therebetween. The implementation of an electronically controlled locking pin may be further combined with a security device other than the physical key. For example, a numeric keypad may be coupled to the patient support apparatus  100  which requires a code to be correctly entered in order to release the locking pin. The electronic solenoid may be in communication with a controller integrated into the patient support apparatus and used for controlling other functions (e.g. the lift assembly  146 ) such that a particular combination of actions using the buttons on the user input handles  152  may enable a battery removal mode. Other methods such as an electronic key (e.g. RFID, NFC, Bluetooth) may be used to authenticate a user to enable the battery removal mode are contemplated. Further still, the patient support apparatus  100  may utilize a biometric authentication sub-system comprising a non-transitory computer-readable medium having an authorized user’s biometric information stored thereon (e.g. fingerprint, facial scan, voice characteristics, retina scan, etc.). The biometric authentication sub-system may be implemented in a mobile device (e.g. a smart phone), or integrated with the patient support apparatus  100  and coupled thereto. For example, a fingerprint reader may be coupled to the user input handles  152  and configured to send an unlock single to the electronic solenoid when an authorized user has placed their finger on the fingerprint reader. Other implementations are contemplated. 
     It is further contemplated that in addition, or in the alternative, to the locking pin, an electronic solenoid may be operably coupled to the latch pawl  182  for direct control. In this implementation the requirement for an authorized user to first pivot the battery receiver  186  into the unlocked state SU may be eliminated. Said differently, the electronic solenoid may directly control movement of the latch pawl  182  between the extended position PE and the retracted position PR. Once a user has enabled the battery removal mode the step of first pivoting the battery receiver  186  may be skipped. 
     Turning now to  FIGS.  11 - 15   , another version of a battery retention system is shown. As will be appreciated from the subsequent description below, the second battery retention system is similar to the battery retention system  180  described above in connection with  FIGS.  1 - 10   . As such, the components and structural features of the second version of the battery retention system  180 ′ that are the same as, or that otherwise correspond to, the first version of the battery retention system  180  are provided with the same reference numerals with the addition of a prime symbol (e.g.  180  and  180 ′). While the specific differences between these versions will be described in detail, for the purposes of clarity, consistency, and brevity, only certain structural features and components common between these versions will be discussed and depicted in the drawings of the second version of the battery retention system  180 ′. Here, unless otherwise indicated, the above description of the first version of the battery retention system  180  may be incorporated by reference with respect to the second version of the battery retention system  180 ′ without limitation. 
     Similar to above, the battery retention system  180 ′ shown in  FIG.  11    prevents the battery  160 ′ from unintentionally becoming disconnected from the patient support apparatus  100 , which may have undesirable effects on the operation of the patient support apparatus  100 . The battery retention system  180 ′ may comprise a mount base  184 ′ and a battery receiver  186 ′ pivotably coupled to the mount base  184 ′ for movement between a locked state SL and an unlocked state SU. The mount base  184 ′ is configured to be coupled to the support frame  106 . 
     The battery receiver  186 ′ is movable relative to the mount base  184 ′ between the locked state SL and the unlocked state SU. The pivoting movement of the battery receiver  186 ′ relative to the mount base  184 ′ may occur about a pivot axis  190 ′. In  FIG.  12   , the battery receiver  186 ′ is shown in the locked state SL, in which the battery  160 ′ is secured to the battery retention system  180 ′. Conversely, in  FIGS.  13  and  14   , the battery receiver  186 ′ is shown pivoted relative to the mount base  184 ′ about the pivot axis  190 ′ in the unlocked state SU, in which the battery  160 ′ is able to be removed from the battery retention system  180 ′ by a caregiver. In this version, the pivot axis  190 ′ is arranged horizontally such that the pivoting movement of the battery receiver  186 ′ moves in a vertical direction. 
     Referring to  FIGS.  12 - 15   , the mount base  184 ′ comprises first side  194 ′, a second side  196 ′, and a pair of pivot ears  280 ′, which define a pivot hole  192 ′. The pivot ears  280 ′ protrude from the second side  196 ′ of the mount base  184 ′ toward the battery receiver  186 ′. Each of the pivot holes  192 ′ extends though the respective pivot ears  280 ′ along a pivot axis  190 ′. The mount base  184 ′ may further comprise a biasing surface  202 ′ arranged on the second side  196 ′ and oriented toward the battery receiver  186 ′ for engaging the latch pawl  182 ′. The mount base  184 ′ may further comprise a pivot limiter  282 ′ protruding from the second side  196 ′. The pivot limiter  282 ′ is arranged for contact with the battery receiver  186 ′ to define the locked state SL. As will be discussed below, the biasing surface  202 ′ may interact with the latch pawl  182 ′ in order to move the latch pawl  182 ′ between the extended and retracted position PRs in coordination with the pivoting movement of the battery receiver  186 ′. 
     The battery receiver  186 ′ is pivotably coupled to the mount base  184 ′ for movement between a locked state SL and an unlocked state SU. The battery receiver  186 ′ has a first side  208 ′ oriented toward the mount base  184 ′ and a second side  210 ′. On the second side  210 ′ the battery receiver  186 ′ defines a channel  212 ′ configured for engaging the battery  160 ′ and an aperture  214 ′ extending between the first side  208 ′ and the channel  212 ′. The channel  212 ′ extends between a first end  216 ′ and a second end  218 ′ in a longitudinal direction along a channel axis  220 ′. The first end  216 ′ has an opening  222 ′ shaped to receive the battery  160 ′ from the first end  220 ′ in a direction along the channel axis  220 ′. 
     Here too, the battery receiver  186 ′ comprises two rails  224 ′ extending between the first end  216 ′ and the second end  218 ′ and on opposing lateral sides of the channel  212 ′. The rails  224  engage corresponding slots defined in the battery housing  162 ′. The rails  224 ′ are generally parallel to the channel axis  220 ′ and support sliding engagement of the battery  160 ′ with the battery receiver  186 ′ along the channel axis  220 ′. As mentioned above, the battery  160 ′ includes a terminal  166 ′ that engages a corresponding receiver terminal  226 ′ as the battery  160 ′ slides along the rails  224 ′ for enabling power transfer to the patient support apparatus  100 . The receiver terminal  226 ′ is coupled to the battery receiver  186 ′ and arranged at the second end  218 ′ of the channel  212 ′. The receiver terminal  226 ′ may supported on an inner wall  228 ′ of the battery receiver  186 ′ at the second end of the channel  212 ′. 
     As best shown in  FIG.  15   , the second side  210 ′ of the battery receiver  186 ′ is depicted spaced from the mount base  184 ′ and the latch pawl  182 ′. The battery receiver  186 ′ defines a pivot bore  284 ′ extending therethrough in a lateral direction perpendicular to the channel axis  220 ′. When assembled, the pivot bore  284 ′ is aligned with the pivot axis  190 ′ and facilitates the pivoting movement of the battery receiver  186 ′. To this end, the battery retention system  180 ′ further comprises a pivot rod  286 ′. The pivot rod  286 ′ is shown spaced from the pivot holes  192 ′ and aligned with the pivot axis  190 ′. When assembled, the pivot rod  286 ′ is received in the pivot holes  192 ′ and the pivot bores  286 ′ to facilitate the pivoting movement of the battery receiver  186 ′. 
     With continued reference to  FIGS.  12 - 15   , the battery receiver  186 ′ further defines a latch recess  240 ′ in the first side  208 ′. The latch pawl  182 ′ is disposed in the latch recess  240 ′ between the battery receiver  186 ′ and the mount base  184 ′. The latch recess  240 ′ is in communication with the aperture  214 ′ to facilitate movement of the latch pawl  182 ′ into the channel  212 ′. The battery receiver  186 ′ defines two pawl sockets  242 ′ on opposing sides of the latch recess  240 ′ and extending through the battery receiver  186 ′. The pawl sockets  242 ′ are configured to receive a trunnion rod  288 ′, which pivotably supports the latch pawl  182 ′. 
     The battery retention system  180 ′ may further comprise a return spring  238 ′ disposed between the mount base  184 ′ and the battery receiver  186 ′. The return spring  238 ′ exerts a force on the mount base  184 ′ and the battery receiver  186 ′ to bias the battery receiver  186 ′ toward the locked state SL. 
     The battery retention system  180 ′ comprises the latch pawl  182 ′ interposed between the battery receiver  186 ′ and the mount base  184 ′. The latch pawl  182 ′ is arranged for movement between a retracted position PR ( FIG.  13   ) and an extended position PE ( FIG.  12   ). In the retracted position PR the latch pawl  182 ′ is substantially outside the channel  212 ′. In the extended position PE the latch pawl  182 ′ is at least partially disposed in the channel  212 ′. More specifically, the latch pawl  182 ′ is disposed in the latch recess  240 ′ and movable into and out of the channel  212 ′ for selectively permitting removal of the battery  160 ′ from the battery retention system  180 ′. To this end, the latch pawl  182 ′ may comprise a latch body  244 ′ having a finger portion  246 ′ arranged for engagement with the mount base  184 ′ and a clasp portion  248 ′ for engaging the battery  160 ′. The latch body  244 ′ may define a trunnion bore  290 ′ extending therethrough along a latch axis  252 ′. The trunnion bore  290 ′ receives the trunnion rod  288 ′ to facilitate the pivoting movement of the latch pawl  182 ′. 
     The latch pawl  182 ′ is disposed in the latch recess  240 ′ such that the trunnion rod  288 ′ is arranged in the pawl sockets  242 ′ and the trunnion bore  290 ′ for supporting pivoting movement of the latch pawl  182 ′ about the latch axis  252 ′. In use, as the latch pawl  182 ′ moves from the extended position PE to the retracted position PR, the finger portion  246 ′ engages the mount base  184 ′ and the clasp portion  248 ′ gets closer to the second side  196 ′ of the mount base  184 ′. Conversely, as the latch pawl  182 ′ moves from the retracted position PR to the extended position PE, the clasp portion  248 ′ gets further away from the second side  196 ′ of the mount base  184 ′. 
     Control of the latch pawl  182 ′ movement is facilitated by a latch spring  256 ′ disposed between the latch pawl  182 ′ and the battery receiver  186 ′. The battery retention system  180 ′ may utilize the latch spring  256 ′ to urge the latch pawl  182 ′ into engagement with the mount base  184 ′. Said differently, the latch spring  256 ′ may be arranged to bias the latch pawl  182 ′ toward the extended position PE. As shown here, the latch spring  256 ′ is disposed between the finger portion  246 ′ of the latch body  244 ′ and the battery receiver  186 ′. Pivoting the battery receiver  186 ′ toward the unlocked state SU causes the finger portion  246 ′ to contact the biasing surface  202 ′, which pivots the latch pawl  182 ′ relative to the battery receiver  186 ′. As the latch pawl  182 ′ pivots toward the retracted position PR the latch spring  256 ′ is compressed. From the unlocked state SU, pivoting the battery receiver  186 ′ toward the locked state SL allows the latch spring  256 ′ to pivot the latch pawl  182 ′ back toward the extended position PE. 
     With renewed reference to  FIGS.  12 - 14   , the battery retention system  180 ′ is shown in operation to remove the battery  160 ′. In  FIG.  12   , the battery receiver  186 ′ is shown in the locked state SL in which the battery  160 ′ is secured in the channel  212 ′ preventing unintended removal. In  FIG.  13   , the battery receiver  186 ′ is pivoted (by a user, not shown) into the unlocked state SU in which the battery  160 ′ is able to be removed from the channel  212 ′. When the battery receiver  186 ′ is in the unlocked state SU the return spring  238 ′ is compressed, which biases the battery receiver  186 ′ back toward the locked state SL when a user releases the battery receiver  186 ′. 
     Similar to above, the battery  160 ′ may be reinstalled by first aligning the battery  160 ′ with the rails  224 ′ of the channel  212 ′ and sliding the battery  160 ′ through the opening  222 ′. As the battery  160 ′ approaches the aperture  214 ′, the battery housing  162 ′ engages the clasp portion  248 ′ of the latch pawl  182 ′. Sliding the battery  160 ′ further along the channel axis  220 ′ urges the clasp portion  248 ′ out of the channel  212 ′. When the battery  160 ′ is fully inserted in the channel  212 ′ such that the battery terminal  166 ′ and the receiver terminal  226 ′ are electrically engaged, the latch pawl  182 ′ is able to pivot into the extended position PE with the clasp portion  248 ′ in the notch  170 ′ of the battery  160 ′. Interaction between the clasp portion  248 ′ and the notch  170 ′ prevents the battery  160 ′ from being removed from the battery retention system  180 . 
     Several examples have been discussed in the foregoing description. However, the examples discussed herein are not intended to be exhaustive or limit the disclosure to any particular form. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the disclosure. The terminology that 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 disclosure may be practiced otherwise than as specifically described.