Fluidizable bed with occupancy status detection and method of occupancy status detection for a fluidizable bed

Patent metadata

Field	Value
Publication number	US-9700239-B2
Application number	US-201213651639-A
Country	US
Kind code	B2
Filing date	Oct 15, 2012
Priority date	Jul 6, 2012
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

A method of detecting a change in occupancy status of a fluidizable bed ( 10 ) includes determining ( 102 ) an unloaded plenum pressure value corresponding to the absence of a load on the bed, determining ( 104 ) a loaded plenum pressure value corresponding to the presence of an occupant on the bed, and establishing a reference (P REF ) as a function of at least one of the unloaded plenum pressure value and the loaded plenum pressure value. A signal ( 116, 120 ) is issued in response to a relationship between the reference and a value (P MON ) representative of actual pressure in the plenum. The bed also includes a pressure sensor ( 60 ) for monitoring a pressure value representative of pressure in the plenum and a controller ( 50 ) for issuing a signal ( 116, 120 ) responsive to a relationship between the monitored value and a reference value.

First claim

We claim:

1. A method of detecting a change in occupancy status of a fluidizable bed extending longitudinally between a head end and a foot end and having a distribution plenum and a fluidizable medium, the method comprising:
determining an unloaded plenum pressure value corresponding to an absence of a load on the bed;
determining a loaded plenum pressure value corresponding to a presence of an occupant on the bed, wherein the unloaded plenum pressure and the loaded plenum pressure are determined using a pressure sensor that is installed either inside the plenum or a conduit that connects a blower with the plenum such that the entirety of the sensor is situated inside the plenum or conduit, wherein the plenum is continuously open to atmosphere through the fluidizable medium when the unloaded plenum pressure and the loaded plenum pressure are measured by the pressure sensor;
calculating a reference value as a sum of the unloaded plenum pressure value and a predetermined fraction of a difference between the loaded and unloaded plenum pressure values, wherein the unloaded plenum pressure value corresponds to pressure in the plenum when the fluidizable medium is in a fluidized state and a load is not being supported by the fluidized medium, and the loaded plenum pressure value corresponds to fluid pressure in the plenum when the fluidizable medium is in the fluidized state and a portion of the occupant is supported by the fluidized medium with another portion of the occupant being supported by a nonfluidizable section of the bed that is pivotable upwardly and downwardly relative to a fluidizable medium container that contains the fluidizable medium, the nonfluidizable section being situated adjacent the head end of the fluidizable bed and the fluidizable medium container being configured so that the fluidizable medium occupies a space extending from the nonfluidizable section to the foot end of the fluidizable bed;
detecting a current pressure value in the plenum; and
issuing a signal in response to the current pressure value being equal to or less than the reference value.

2. The method of claim 1 wherein the predetermined fraction is one third.

3. The method of claim 1 wherein the unloaded plenum pressure value and the loaded plenum pressure value are offset.

4. A fluidizable bed extending longitudinally between a head end and a foot end, the fluidizable bed comprising:
a blower;
a receptacle;
a diffuser board dividing the receptacle into a fluidizable medium container and a distribution plenum beneath the fluidizable medium container, the fluidizable medium container adapted to receive a quantity of a fluidizable medium and the plenum adapted to receive a stream of a fluidizing medium from the blower via a conduit that extends between the blower and the plenum such that the fluidizable medium is fluidized as a result of admission of the fluidizing medium to the plenum;
a pressure sensor for monitoring a value representative of pressure in the plenum;
and a controller configured to calculate a reference pressure value as a sum of an unloaded plenum pressure value and a fraction of a difference between a loaded plenum pressure value and the unloaded plenum pressure value, and for issuing a signal indicating that a current plenum pressure is less than or equal to the reference pressure value, wherein the unloaded plenum pressure value corresponds to pressure in the plenum when the fluidizable medium is in a fluidized state and a load is not being supported by the fluidized medium, and the loaded plenum pressure value corresponds to pressure in the plenum when the fluidizable medium is in the fluidized state and a portion of an occupant is supported by the fluidized medium with another portion of the occupant being supported by a nonfluidizable section of the bed that is pivotable upwardly and downwardly relative to the fluidizable medium container, the nonfluidizable section being situated adjacent the head end of the fluidizable bed and the fluidizable medium container being configured so that the fluidizable medium occupies a space extending from the nonfluidizable section to the foot end of the fluidizable bed, wherein the pressure sensor is installed either inside the plenum or the conduit such that the entirety of the sensor is situated inside the plenum or conduit, wherein the plenum is continuously open to atmosphere through the fluidizable medium when the unloaded plenum pressure and the loaded plenum pressure are measured by the pressure sensor.

5. The fluidizable bed of claim 4 wherein the fraction is one third.

6. The fluidizable bed of claim 4 wherein the unloaded plenum pressure value and the loaded plenum pressure value are offset values.

7. A fluidizable bed extending longitudinally between a head end and a foot end, the fluidizable bed comprising:
a blower;
a receptacle;
a diffuser board dividing the receptacle into a fluidizable medium container and a distribution plenum beneath the fluidizable medium container, the fluidizable medium container adapted to receive a quantity of a fluidizable medium, and the plenum arranged continuously open to atmosphere through the fluidizable medium and adapted to receive a stream of a fluid from the blower connected with the plenum such that the fluidizable medium is fluidized as a result of admission of fluid to the plenum;
a pressure sensor arranged for monitoring pressure in the plenum; and
a controller configured to calculate a threshold pressure value as a sum of an unloaded plenum pressure value and a predetermined fraction of a difference between a loaded plenum pressure value and the unloaded plenum pressure value,
wherein the unloaded plenum pressure value corresponds to pressure in the plenum having the fluidizable medium in the fluidized state and an occupant load is not supported by the fluidized medium, and the loaded plenum pressure value corresponds to pressure in the plenum having the fluidizable medium in the fluidized state and at least a portion of an occupant is supported by the fluidizable medium.

8. The fluidizable bed of claim 7 , wherein the predetermined fraction is one third.

9. The fluidizable bed of claim 7 , wherein the predetermined fraction is calculated by the controller as a function of the unloaded and loaded plenum pressure values.

10. The fluidizable bed of claim 7 , wherein the unloaded plenum pressure value and the loaded plenum pressure value are offset.

11. The fluidizable bed of claim 7 , wherein the controller is configured to issue a signal indicating an alarm to activate when a current pressure value is less than the threshold pressure value.

Assignees

• Sauser Frank
• Klink Kristopher
• Hill Rom Services Inc

Inventors

• Sauser Frank
• Klink Kristopher

Classifications

• A61G7/05746

  fluidised by air flow · CPC title

• A61B5/6891

  Furniture · CPC title

• A61G7/07

  for the head or torso, e.g. special back-rests {(pillows in general A47G9/10)} · CPC title

• A61B5/1115 Primary

  Monitoring leaving of a patient support, e.g. a bed or a wheelchair · CPC title

• A61B2562/168

  Fluid filled sensor housings · CPC title