Patent Publication Number: US-10314753-B2

Title: Systems, methods, and devices for fluidizing a fluidizable medium

Description:
BACKGROUND OF THE DISCLOSURE 
     This disclosure relates generally to fluidized person support structures. More particularly, but not exclusively, one illustrative embodiment relates to fluidizing a fluidizable medium of a fluidized person support structure. While various fluidized person support structures have been developed, there is still room for improvement. Thus a need persists for further contributions in this area of technology. 
     SUMMARY OF THE DISCLOSURE 
     In one illustrative embodiment, a fluidized person support structure comprises a fluidizable medium, a fluid supply, a sensor, and a controller. The fluid supply is configured to supply fluid that flows through the fluidizable medium. The controller is electrically coupled to the fluid supply and the sensor and is configured to calculate a desirable flow rate as a function of at least one input from the sensor as the rate at which fluid flows through the fluidizable medium is changed. The controller causes the fluid supply to supply fluid at the desirable flow rate. 
     In another illustrative embodiment, a fluidized person support structure comprises a fluidizable medium, a fluid supply, an input device, and a controller. The fluid supply is configured to supply fluid that flows through the fluidizable medium. The controller is configured to receive an input from the input device and calculate a fluidization threshold as a function of the input. The controller controls the fluid supply as a function of the fluidization threshold. 
     In another illustrative embodiment, a fluidized person support structure comprises a fluidizable medium, a fluid supply, a sensor, and a controller. The fluid supply is configured to supply fluid that flows through the fluidizable medium. The sensor is configured generate a signal indicative of a level of fluidization of the fluidizable medium. A physical property of the sensor changes as the fluidizable medium is fluidized by the fluid. The controller is configured to receive an input from the sensor and control the fluid supply as a function of the input. 
     In another illustrative embodiment, a method of fluidizing a fluidizable medium comprises the steps of: identifying a fluidization threshold of the fluidizable medium; and increasing a rate at which fluid flows through the fluidizable medium as a function of the fluidization threshold. 
     In another illustrative embodiment, a method of fluidizing a fluidizable medium comprising the steps of: changing a rate at which fluid flows through the fluidizable medium; sensing a parameter indicative of a level of fluidization of the fluidizable medium; determining a desirable flow rate as a function of the sensed parameter; and controlling a fluid supply as a function of the desirable flow rate. 
     Additional features alone or in combination with any other feature(s), including those listed above and those listed in the claims and those described in detail below, can comprise patentable subject matter. Others will become apparent to those skilled in the art upon consideration of the following detailed description of illustrative embodiments exemplifying the best mode of carrying out the invention as presently perceived. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the illustrative examples in the drawings, wherein like numerals represent the same or similar elements throughout: 
         FIG. 1  is a perspective side view of a fluidized person support apparatus according to an illustrative embodiment; 
         FIG. 2  is a perspective side view of the fluidized person support apparatus according to another illustrative embodiment; 
         FIG. 3  is a cross-sectional side view of the person support apparatus of  FIG. 2  along the width of the person support apparatus showing a profile of the diffuser; 
         FIG. 4  is a graph of the plenum pressure as a function of fluid flow rate; 
         FIG. 5  is a cross-sectional side view of the person support apparatus of  FIG. 2  along the width of the person support apparatus showing a flexible sensor positioned in the fluidizable medium; 
         FIG. 6  is a cross-sectional side view of the person support apparatus of  FIG. 2  along the width of the person support apparatus showing an accelerometer positioned in the fluidizable medium; 
         FIG. 7  is a cross-sectional side view of the person support apparatus of  FIG. 2  along the width of the person support apparatus showing a plurality of sensors positioned in the fluidizable medium at varying depths; and 
         FIG. 8  is a cross-sectional side view of the person support apparatus of  FIG. 2  along the width of the person support apparatus showing a sensor positioned in the plenum. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     While the present disclosure can take many different forms, for the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. No limitation of the scope of the disclosure is thereby intended. Various alterations, further modifications of the described embodiments, and any further applications of the principles of the disclosure, as described herein, are contemplated. 
     A person support apparatus  10  according to one illustrative embodiment of the current disclosure is shown in  FIGS. 1-8 . The person support apparatus  10  is a fluidized hospital bed and includes a head section H 1 , where the head of a person (not shown) can be positioned, and a foot section F 1 , where the feet of a person (not shown) can be positioned. The person support apparatus  10  includes a lower frame  12 , an upper frame  14 , a plurality of supports  16  supporting the upper frame  14  on the lower frame  12 , and a fluidization system  18 . 
     The supports  16  are coupled to the lower frame  12  and the upper frame  14  and movably support the upper frame  14  above the lower frame  12  as shown in  FIG. 1 . In one illustrative embodiment, the supports  16  are lift mechanisms  16  with a lift driver (not shown) that causes the lift mechanisms  16  to expand and/or contract to raise and/or lower the upper frame  14  with respect to the lower frame  12 . In another illustrative embodiment, the supports  16  fixedly support the upper frame  14  above the lower frame  12  as shown in  FIG. 2 . 
     The upper frame  14  includes an upper frame weldment  24  that supports a tank assembly  26  or container  26  and a head end support assembly  28  as shown in  FIG. 1 . In some contemplated embodiments, the upper frame  14  does not include a head end support assembly  28  and instead, the tank assembly  26  that extends the length of the upper frame  14  as shown in  FIG. 2 . The head end support assembly  28  is configured to support a person&#39;s head and/or torso while the tank assembly  26  is configured to support the pelvic region and lower extremities of a person. The head end support assembly  28  includes a person support surface  30  or mattress  30  composed of fluid bladders  32  and is configured to pivot with respect to the tank assembly  26  to move a person supported on the person support apparatus  10  between a substantially horizontal position and a reclined or elevated position. In some contemplated embodiments, the person support surface  30  includes foam (not shown) and/or a combination of foam and fluid bladders  32 . 
     The tank assembly  26  includes a tank base  34 , a tank liner  36 , a tank bladder  38 , and a filter cover  40  or gas permeable cover  40  as shown in  FIGS. 3-8 . In one illustrative embodiment, the tank base  34  and the tank liner  36  are made of a low or substantially no air-loss material, such as, for example, a polyurethane-backed nylon fabric material, and the tank bladder  38  is composed of a substantially no air loss polymeric material and filled with a fluid, such as, air. The tank base  34  is coupled to the upper frame weldment  24  by tank fasteners (not shown) and includes an inlet  42  that couples with the fluid supply system  18 . The tank liner  36  and the tank bladder  38  are coupled together to form the sides of the tank assembly  26 . The tank base  34  is coupled with the tank liner  36  and the tank bladder  38  to define an opening  39  opposite the tank base  34 . 
     The filter cover  40  or filter sheet  40  is positioned over the opening  39  and is coupled to the tank liner  36  as shown in  FIGS. 3-8 . The cover  40  is coupled to the tank liner  36  by fasteners can be zippers, buttons, snaps, turn-buttons, hook and loop fasteners, or other fasteners. The tank base  34 , the tank liner  36 , the tank bladder  38 , and the filter cover  40  cooperate to define a chamber  44  there between that contains a fluidizable medium  46  and a diffuser  48  or gas permeable support  48 . The filter cover  40  is configured to allow fluid, such as, bodily fluids and air, to pass there through while preventing the fluidizable medium  46  from passing through. The filter cover  40  is also configured to prevent hammocking from occurring when a person is supported thereon and the fluidizable medium  46  is fluidized. 
     The diffuser  48  is configured to support the fluidizable medium  46  in the chamber  44  and provide substantially uniform fluid flow to the fluidizable medium  46  as shown in  FIGS. 3-8 . The diffuser  48  is permeable to the fluid supplied by the fluidization system  18  and is configured to prevent the fluidizable medium  46  from passing there through. The diffuser  48  is positioned proximate the tank base  34  and cooperates with the tank base  34  to define a chamber  50  or plenum  50 . The plenum  50  receives fluid from the fluidization system  18  through the inlet  42  and is configured to substantially equalize the pressure of the fluid within the plenum  50  across the diffuser  48  so that the fluid is communicated substantially uniformly through the diffuser  48 . The fluid in the plenum  50  is pressurized depending on the fluid flow rate from the fluidization system  18  and the porosity of the diffuser  48 . 
     The volume between the diffuser  48  and the filter cover  40  is filled with the fluidizable medium  46  as shown in  FIGS. 3-8 . Generally speaking, fluidization of the fluidizable medium  46  follows a standard pressure drop v. fluid flow rate curve for fluidization of a bed of solid particles as shown in  FIG. 4 . The pressure drop is proportional to the weight of the bed of particles and the rate at which fluid flows through the particles. Fluid flowing through the bed of particles exerts a force on the particles, and when the force exceeds the weight of the bed of particles, the particles become suspended and begin to exhibit liquid-like characteristics. The portion of the graph at which this occurs is the fluidization threshold or knee K 1  of the curve. Increasing the fluid flow rate above the knee K 1  into the fluidized region causes the bed of particles to expand and bubble. The change in pressure drop in this region is relatively small for changes in fluid flow rate. Conversely, decreasing the fluid flow rate below the knee K 1  into the non-fluidized region causes the particles to stop moving and the bed of particles becomes fixed. The change in pressure drop in this region is relatively large for changes in the fluid flow rate when compared to the fluidized region. 
     The fluidizable medium  46  is composed of small particles that can vary in shape in size. In one illustrative embodiment, the fluidizable medium  46  are spherical silica beads of the type commonly employed in air fluidized bead person support systems. In some contemplated embodiments, the fluidizable medium  46  can range in size from about 50 to about 150 microns in diameter. A new batch of the fluidizable medium  46  having a depth of about 9 inches requires about 25-35 cubic feet per minute (“CFM”) to reach the fluidization threshold and about 40-65 CFM to provide a desirable level of fluidization. 
     The fluidization system  18  is configured to communicate fluid, such as, air, through the diffuser  48  to fluidize the fluidizable medium  46 . The fluidization system  18  includes a fluid supply  52 , a hose  54 , a sensor  56 , an input device  57 , and a controller  58  as shown in  FIGS. 1-3 . In one illustrative embodiment, the fluid supply  52  is an air blower coupled to the lower frame  12  and configured to supply air through the hose  54  to the plenum  50 . In some contemplated embodiments, the fluid supply  52  can be removably coupled to or integrated into the upper frame  14  and/or the supports  16 . In other contemplated embodiments, the fluid can be remotely supplied, such as, by a head wall unit (not shown) or fluid outlet (not shown) within a facility, such as, an air outlet. In still other contemplated embodiments, the temperature of the fluid communicated by the fluid supply  52  can be increased/decreased by a heating/cooling device (not shown). 
     The sensor  56  is configured to measure an operational parameter of the person support apparatus  10  indicative of a level of fluidization of the fluidizable medium  46  as shown in  FIGS. 5-8 . The word “indicative” as used herein means indicating an actual level of fluidization or used as a variable in the calculation of the level of fluidization. The sensor  56  can be configured to measure a variety of parameters, including, but not limited to, the fluid flow rate, the amount of current drawn by the fluid supply  52 , an amount of movement of the fluidizable medium  46 , a fluid pressure, pressures within the fluidizable medium, and other operational parameters. In one illustrative embodiment, the sensor  56  includes a flexible sensor coupled to the tank assembly  26  and positioned in the fluidizable medium  46  as shown in  FIG. 5 . In some contemplated embodiments, the flexible sensor  56  could be coupled to the diffuser  48 , the filter cover  40 , and/or the tank liner  36 . The flexible sensor  56  is configured to maintain substantially the same resistance when the fluidizable medium  46  is not fluidized and change its resistance as it is moved by the fluid and/or the fluidizable medium  46  when the fluidizable medium  46  is fluidized. The magnitude of the changes in resistance increase as the fluidization increases. 
     In another illustrative embodiment, the sensor  56  includes an accelerometer coupled to the tank assembly  26  and positioned in the fluidizable medium  46  as shown in  FIG. 6 . The accelerometer  56  is coupled to a post P 1  that is coupled to the tank liner  36  and is configured to be moved by the fluidizable medium  46  and/or the fluid when the fluidizable medium  46  is fluidized. In some contemplated embodiments, the accelerometer  56  could be coupled to the diffuser  48  and/or the filter cover  40 . 
     In another illustrative embodiment, the sensor  56  includes an array of pressure sensors positioned within the fluidizable medium  46  as shown in  FIG. 7 . In one illustrative embodiment, a first sensor SS  1  is coupled to the diffuser  48  and suspended in the fluidizable medium  46  a first distance D 1  from the diffuser  48 , for example, about 1 inch, and a second sensor SS 2  coupled to the diffuser  48  and suspended in the fluidizable medium  46  a second distance D 2  from the diffuser  48 , for example, about 5 inches. The first sensor SS 1  is configured to measure a first pressure within the fluidizable medium  46  and the second sensor SS 2  is configured to measure a second pressure within the fluidizable medium  46 . The first pressure and the second pressure can be compared to determine the difference in pressure between the sensors to signify a level of fluidization. 
     In another illustrative embodiment, the sensor  56  includes a pressure sensor positioned in the plenum  50  and configured to measure the pressure within the plenum  50  as shown in  FIG. 8 . As the fluidizable medium  46  fluidizes, the rate at which the fluid pressure within the plenum  50  changes is reduced. In some contemplated embodiments, a flow sensor (not shown) is used in combination with the pressure sensor  56  (or any one of the other of sensors described herein) to detect the rate at which fluid is flowing through the fluidizable medium  46  or diffuser  48 . 
     The input device  57  is electrically coupled to the controller  58  as shown in  FIG. 3 . In one illustrative embodiment, the input device  57  is user interface configured to receive inputs from a user and/or control at least one function of the person support apparatus  10 . In another illustrative embodiment, the input device  57  is configured to provide an input to the controller  58  from a device or system external to and/or in communication with the person support apparatus  10 , such as, an electronic medical record system (EMR). The information received by the input device  57  can include the depth of the fluidizable medium  46 , the weight of the person supported on the person support apparatus  10 , or other information about the person or person support apparatus  10 . Based on the information from the input device  57 , the controller  58  is be able to better calculate what the fluidization threshold is. 
     The controller  58  is electrically coupled to the fluid supply  52  and the sensor  56  and is configured to control the operation of the fluid supply  52  as a function of one or more input signals from the sensor  56 . The controller  58  can determine how to optimize fluidization of the fluidizable medium  46  a number of ways. One way the controller  58  can optimize fluidization is by identifying the location of the fluidization threshold and increasing the fluid flow rate by a predetermined amount. In one illustrative embodiment, the controller  58  calculates what the fluidization threshold is based on the depth of the fluidizable medium and the weight of the person supported thereon. In another illustrative embodiment, the fluid flow rate from the fluid supply  52  is slowly increased from an initial flow rate, for example, 0 CFM, until the input from the sensor  56  indicates that the fluidizable medium  46  is at about the fluidization threshold. Once the fluidization threshold has been determined, the controller  58  increases the fluid flow rate by a predetermined amount, such as, 10-35 CFM, to reach a predetermined desirable level of fluidization. The fluidization threshold can be established during a calibration mode or while a person is supported on the person support structure  10 . 
     Another way the controller  58  can optimize fluidization is by checking the fluidization level as the fluid flow rate is varied. In one illustrative embodiment, the fluid supply  52  is supplying fluid at a first rate FR 1  and the sensor  56  sense a parameter indicative of a first level of fluidization FL 1 . The controller  58  changes the fluid flow rate from the first rate FR 1  to a second rate SR 1  and the sensors sense a parameter indicative of a second level of fluidization SL 1 . In one illustrative embodiment, the change in fluid flow rate is ±5-10 CFM. The controller  58  compares the first level of fluidization FL 1  to the second level of fluidization SL 1  to determine what the pressure drop between the two values is. If the pressure drop is relatively small then the fluid supply  52  is operating in the fluidized region of the curve in  FIG. 4 , and the controller  58  operates the fluid supply  52  at the lower of the first rate FR 1  and the second rate SR 1 . If the pressure drop is relatively large, then the fluid supply  52  is operating near the fluidization threshold or in the non-fluidized region (shown in  FIG. 4  with the first rate FR 2 , the first level of fluidization FL 2 , the second rate S 2 , and the second level of fluidization SL 2 ) and the controller  58  operates the fluid supply  52  at the higher of the first rate FR 1  and the second rate SR 1 . 
     If neither the first rate FR 2  nor the second rate SR 2  cause the fluidizable medium  46  to fluidize, then the controller  58  can increase the fluid flow rate until the fluidization threshold is established and then increase the fluid flow rate by a predetermined amount to reach a desired level of fluidization, or the controller can repeat the process of comparing first and second flow rates and levels of fluidization until one of the flow rates generates a desirable level of fluidization. In some contemplated embodiments, the controller  58  can operate the fluid supply  52  at the lower of the first rate FR 1  and the second rate SR 1  as long as both rates are at or above the fluidization threshold in the fluidized region. In other contemplated embodiments, once a desirable fluidization threshold has been determined and the fluid supply  52  is operating at the appropriate fluid flow rate, a user is able to increase and/or decrease the flow rate within a predetermined therapeutic range, for example, ±20 CFM, as long as level of fluidization remains above the fluidization threshold or the lower end of a predetermined desirable fluidization threshold. 
     Another way the controller  58  can optimize fluidization is by adjusting the fluid flow rate upon a triggering event occurring. In one illustrative embodiment, the triggering event occurs when the level of fluidization is less than or equal to a predetermined trigger threshold, such as, the fluidization threshold. The level of fluidization can be measured using any of the sensors  56  previously mentioned and the controller  58  can use any method previously mentioned to return the person support apparatus  10  to a desired level of fluidization. In one example, the controller  58  causes the fluid supply  52  to gradually increase the fluid flow rate until the fluidization threshold is established and then increases the fluid flow rate by a predetermined amount to reach a desired level of fluidization. In another example, the controller  58  measures the level of fluidization at the current rate and compares it to a level of fluidization at a higher rate. If the higher rate produces a desired level of fluidization, the controller  58  maintains the fluid flow rate from the fluid supply  52  at that rate. If not, then the process is repeated until a desired fluidization level is reached. 
     Many other embodiments of the present disclosure are also envisioned. For example, a fluidized person support structure comprises a fluidizable medium, a fluid supply, a sensor, and a controller. The fluid supply is configured to supply fluid that flows through the fluidizable medium. The controller is electrically coupled to the fluid supply and the sensor and is configured to change the rate at which fluid flows through the fluidizable medium from a first rate to a second rate and calculate a desirable flow rate as a function of a first input from the sensor at the first rate and a second input from the sensor at the second rate. The controller causes the fluid supply to supply fluid at the desirable flow rate. 
     In another example, a fluidized person support structure comprises a fluidizable medium, a fluid supply, a sensor, and a controller. The fluid supply is configured to supply fluid that flows through the fluidizable medium. The controller is electrically coupled to the fluid supply and the sensor and is configured to calculate a desirable flow rate as a function of at least one input from the sensor as the rate at which fluid flows through the fluidizable medium is changed. The controller causes the fluid supply to supply fluid at the desirable flow rate. 
     In another example, a fluidized person support structure comprises a fluidizable medium, a fluid supply, an input device, and a controller. The fluid supply is configured to supply fluid that flows through the fluidizable medium. The controller is configured to receive an input from the input device and calculate a fluidization threshold as a function of the input. The controller controls the fluid supply as a function of the fluidization threshold. 
     In another example, a fluidized person support structure comprises a fluidizable medium, a fluid supply, a sensor, and a controller. The fluid supply is configured to supply fluid that flows through the fluidizable medium. The sensor is configured generate a signal indicative of a level of fluidization of the fluidizable medium. A physical property of the sensor changes as the fluidizable medium is fluidized by the fluid. The controller is configured to receive an input from the sensor and control the fluid supply as a function of the input. 
     In another example, a method of fluidizing a fluidizable medium comprises the steps of: identifying a fluidization threshold of the fluidizable medium; and increasing a rate at which fluid flows through the fluidizable medium as a function of the fluidization threshold. 
     In another example, a method of fluidizing a fluidizable medium comprising the steps of: changing a rate at which fluid flows through the fluidizable medium; sensing a parameter indicative of a level of fluidization of the fluidizable medium; determining a desirable flow rate as a function of the sensed parameter; and controlling a fluid supply as a function of the desirable flow rate. 
     In another example, a fluidized person support structure comprises a fluidizable medium, a fluid supply, a sensor, and a controller. The fluid supply is configured to supply fluid that flows through the fluidizable medium. The controller is configured to identify a fluidization threshold as a function of an input from the sensor as the rate fluid supplied by the fluid supply is changed, and control the fluid supply as a function of the fluidization threshold. 
     In another example, an apparatus for controlling the fluidization level of a fluidized person support apparatus comprises a fluidizable medium, a fluid supply, an input device, and a controller. The fluid supply is configured to communicate a fluid through the fluidizable medium. The controller is configured to receive an input from the input device and calculate a fluidization threshold as a function of the input. The controller controls the fluid supply as a function of the fluidization threshold. 
     In another example, an apparatus for controlling the fluidization level of a fluidized person support apparatus comprises a fluidizable medium, a fluid supply, a sensor, and a controller. The fluid supply is configured to communicate a fluid through the fluidizable medium. The sensor is configured generate a signal indicative of a level of fluidization of the fluidizable medium. A physical property of the sensor changes as the fluidizable medium is fluidized by the fluid. The controller is configured to receive an input from the sensor and control the fluid supply as a function of the input. 
     In another example, a method of optimizing fluidization of a fluidizable medium in a person support structure comprises the steps of: upon the occurrence of a triggering event, determining a fluidization threshold of the fluidizable medium; and changing a rate at which fluid flows through the fluidizable medium as a function of the fluidization threshold. 
     In another example, a method of optimizing fluidization of a fluidizable medium comprises the steps of: identifying a fluidization threshold of the fluidizable medium; and increasing fluidization of the fluidizable medium by a predetermined amount above the fluidization threshold to reach a desired fluidization level. 
     Any theory, mechanism of operation, proof, or finding stated herein is meant to further enhance understanding of principles of the present disclosure and is not intended to make the present disclosure in any way dependent upon such theory, mechanism of operation, illustrative embodiment, proof, or finding. It should be understood that while the use of the word preferable, preferably or preferred in the description above indicates that the feature so described can be more desirable, it nonetheless can not be necessary and embodiments lacking the same can be contemplated as within the scope of the disclosure, that scope being defined by the claims that follow. 
     In reading the claims it is intended that when words such as “a,” “an,” “at least one,” “at least a portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary. 
     It should be understood that only selected embodiments have been shown and described and that all possible alternatives, modifications, aspects, combinations, principles, variations, and equivalents that come within the spirit of the disclosure as defined herein or by any of the following claims are desired to be protected. While embodiments of the disclosure have been illustrated and described in detail in the drawings and foregoing description, the same are to be considered as illustrative and not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Additional alternatives, modifications and variations can be apparent to those skilled in the art. Also, while multiple inventive aspects and principles can have been presented, they need not be utilized in combination, and various combinations of inventive aspects and principles are possible in light of the various embodiments provided above.