Load Suspension and Weighing System for a Dialysis Machine Reservoir

• US 20140174835A1
• Filed: 12/24/2012
• Published: 06/26/2014
• Est. Priority Date: 12/24/2012
• Status: Active Grant

• Current Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius Medical Care AG)
• Original Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius Medical Care AG)
• Inventors: Fulkerson, Barry Neil, Huang, Alec, Kelly, Brian Thomas, Nolan, Tam, Fazio, Joe, Smith, Mark
• Granted Patent: US 9,157,786 B2
• Time in Patent Office: Days
• US Class Current: 177/1
• CPC Class Codes: A61M 1/3621 Extra-corporeal blood circuits single-needle circuits A61M1/30
• CPC Class Codes: A61M 2205/3393 by weighing the reservoir
• CPC Class Codes: B01D 61/30 Accessories; Auxiliary operation
• CPC Class Codes: G01G 17/04 for weighing fluids, e.g. gases, pastes
• CPC Class Codes: G01G 19/14 for weighing suspended loads G01G3/00 takes precedence; incorporation of weighing devices in cranes B66C1/40, B66C13/16
• CPC Class Codes: G01G 3/15 measuring variations of magnetic properties
• CPC Class Codes: G01L 1/04 by measuring elastic deformation of gauges, e.g. of springs
• CPC Class Codes: G01L 1/044 of leaf springs
• CPC Class Codes: G01L 1/046 of spiral springs

Abstract

A load suspension and weighing system for a removable reservoir unit of a portable dialysis machine includes a centrally located flexure assembly. The flexure assembly includes magnets and a number of flexure rings which allow for movement of the magnets about a fixed circuit board. Sensors in the circuit board sense changes in the magnetic field as the magnets move in relation to the circuit board. The magnetic field changes produce a voltage output which is used by a processor to generate weight calculations. The top of the flexure assembly is attached to the interior of the dialysis machine. The entirety of the reservoir unit is suspended by a first internal frame that is attached to the bottom of the flexure assembly. Having a single flexure assembly positioned above the reservoir unit provides more accurate weight measurements while also preventing damage to the assembly from water spillage.

Claims

1. A flexure assembly for weighing and suspending loads, said flexure assembly comprising:

a. a top component comprising a first plurality of magnets;

b. a bottom component comprising a second plurality of magnets, wherein said first plurality of magnets and said second plurality of magnets generate a magnetic field within said flexure assembly;

c. a circuit board positioned between said top assembly and said bottom assembly and comprising a plurality of magnetic field sensors and a processor;

d. at least one flexing structure attached to said top assembly and positioned between said top assembly and said circuit board, wherein said at least one flexing structure comprises at least one flexing member for allowing movement of said top assembly in relation to said circuit board and in tandem with said bottom assembly; and

e. at least one flexing structure attached to said bottom assembly and positioned between said bottom assembly and said circuit board, said at least one flexing structure comprising at least one flexing member for allowing movement of said bottom assembly in relation to said circuit board and in tandem with said top assembly.

2. The flexure assembly of claim 1 wherein the at least one flexing structure attached to said top assembly is a flexure ring and wherein said at least one flexing member is a curved arm.

3. The flexure assembly of claim 2 wherein the at least one flexing structure attached to said bottom assembly is a flexure ring and wherein said at least one flexing member is a curved arm.

4. The flexure assembly of claim 3, comprising an additional flexure ring positioned between said top assembly and said circuit board and an additional flexure ring positioned between said bottom assembly and said circuit board.

5. The flexure assembly of claim 1, wherein said top assembly is adapted to attach to an attachment point of a dialysis machine and wherein said attachment point is positioned along a vertical axis extending through a center of said dialysis machine.

6. The flexure assembly of claim 1, wherein said bottom assembly is adapted to attach to an attachment point of a first internal frame of a dialysis machine and wherein said attachment point of the first internal frame is positioned along a vertical axis extending through a center of said dialysis machine.

7. The flexure assembly of claim 3, wherein said flexure assembly includes at least one spacer element between each of said at least one flexure rings and said circuit board.

8. The flexure assembly of claim 1 further comprising copper wherein said copper is adapted to magnetically dampen mechanical oscillations of structures suspended from the flexure assembly and attached to the bottom assembly.

9. The flexure assembly of claim 3, wherein said flexure rings are comprised of aluminum.

10. A method for weighing and suspending loads of a reservoir unit of a dialysis machine, comprising the steps of:

a. providing a flexure assembly, said flexure assembly attached to a point along a vertical axis of said dialysis machine, said flexure assembly comprising;

i. a top component comprising a first plurality of magnets;

ii. a bottom component comprising a second plurality of magnets, wherein said first plurality of magnets and said second plurality of magnets generate a magnetic field within said flexure assembly;

iii. a circuit board positioned between said top assembly and said bottom assembly and comprising at least one magnetic field sensor and a processor;

iv. at least one flexing structure attached to said top assembly and positioned between said top assembly and said circuit board, said at least one flexing structure comprising at least one flexing member for allowing movement of said top assembly in relation to said circuit board; and

v. at least one flexing structure attached to said bottom assembly and positioned between said bottom assembly and said circuit board, said at least one flexing structure comprising at least one flexing member for allowing movement of said bottom assembly in relation to said circuit board; and

,

b. applying a load to the bottom assembly of said flexure assembly, wherein the application of said load pulls on said flexure assembly, resulting in a displacement of said magnetic field about said circuit board, wherein said at least one magnetic field sensor senses the displacement of the magnetic field and generates a voltage output and wherein said processor receives the voltage output and generates a weight measurement based on the voltage output.

11. The method for weighing and suspending loads of claim 10 wherein the at least one flexing structure attached to said top assembly is a flexure ring and wherein said at least one flexing member is a curved arm.

12. The method for weighing and suspending loads of claim 11 wherein the at least one flexing structure attached to said bottom assembly is a flexure ring and wherein said at least one flexing member is a curved arm.

13. The method for weighing and suspending loads of claim 12 wherein at least one of the flexure ring attached to said bottom assembly or the flexure ring attached to the top assembly comprises aluminum.

14. The method for weighing and suspending loads of claim 12, comprising an additional flexure ring positioned between said top assembly and said circuit board and an additional flexure ring positioned between said bottom assembly and said circuit board.

15. The method for weighing and suspending loads of claim 11, wherein the first plurality of magnets lie in a same plane and are spaced 120 degrees apart.

16. The method for weighing and suspending loads of claim 12, wherein the second plurality of magnets lie in a same plane and are spaced 120 degrees apart.

17. A dialysis system having an assembly for weighing and suspending loads, said assembly comprising:

a first component comprising a first plurality of magnets;

a second component comprising a second plurality of magnets, wherein said first plurality of magnets and said second plurality of magnets generate a magnetic field within said assembly; and

a circuit board positioned between said first component and said second component and comprising a plurality of magnetic field sensors for outputting a voltage based on changes to said magnetic field and a processor, wherein said processor is configured to output a weight measurement based on said voltage output.

18. The dialysis system of claim 17 further comprising at least one flexing structure attached to said first component and positioned between said first component and said circuit board, said at least one flexing structure comprising at least one curved member for allowing movement of said first component in relation to said circuit board.

19. The dialysis system of claim 18 further comprising at least one flexing structure attached to said second component and positioned between said second component and said circuit board, said at least one flexing structure comprising at least one curved member for allowing movement of said second component in relation to said circuit board.

20. The dialysis system of claim 17 further comprising a first internal frame attached to said second component, said first internal frame having a top plate attached to said second component, at least two tracks configured to slidably receive a reservoir unit, and a plate having a plurality of electrical contact elements configured to be in physical and electrical contact with a contact plate on said reservoir unit.