Membrane-Sealed Dialysis Pump Chambers to Prevent Liquid Scattering

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Solution Overview

Problem

Existing pump devices for hemodialysis suffer from liquid leakage during piston motion and require precise control of electromagnetic valves, and detachment of chambers can lead to scattering of residual dialysate or drain liquid.

Innovation Solution

A pump device with flexible dividing membranes that close accommodation parts, allowing detachable chambers to be sealed, using a drive source to displace membranes for suction and discharge, and incorporating incompressible liquid and negative-pressure ports for accurate fitting and detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of repair

If the chamber is made detachable for replacement, then ease of maintenance is improved, but liquid leakage occurs when the chamber is detached

Engineering Contradiction:
Improvechamber replacementVSAvoidliquid scattering
Core Design Contradiction:
Ease of repairVSObject-generated harmful factors

Solution Approach 1:

The dividing membrane automatically closes the accommodation part before the chamber is detached from the pump body. This preliminary closing action prevents liquid from scattering during the detachment process, while still allowing easy removal of the chamber for maintenance or replacement.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If electromagnetic valves are used for liquid delivery, then control precision is improved, but device complexity increases

Engineering Contradiction:
Improveliquid delivery controlVSAvoidnumber of valves and pumps
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the need for electromagnetic valves and additional pumps by using the piston's mechanical motion directly to displace the dividing membrane. This simplifies the device structure while maintaining precise control over liquid delivery through the natural reciprocating motion of the piston.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the electromagnetic valve control system with a direct mechanical piston-driven system. The piston's mechanical displacement directly moves the dividing membrane to control liquid flow, eliminating the need for complex electromagnetic actuation and reducing overall device complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If pistons undergo reciprocating motion in the cylinder, then liquid delivery is enabled, but liquid leakage occurs at sealed parts

Engineering Contradiction:
Improvedialysate deliveryVSAvoidliquid leakage
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The invention uses a flexible dividing membrane instead of rigid sealed parts in the traditional piston-cylinder arrangement. This flexible membrane effectively seals the accommodation part during piston reciprocating motion, preventing liquid leakage while allowing the piston to move back and forth for continuous dialysate delivery.

Inventive Principle:
Principle #30Flexible shells and thin films

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Prevents scattering of residual dialysate or drain liquid during chamber detachment and ensures smooth operation with continuous flow control, reducing the need for additional pumps or valves.

Implementation Method 1

dividing membranes each being a flexible member attached to a corresponding one of the supply chamber and the drain chamber in such a manner as to close a corresponding one of the supply-side accommodation part and the drain-side accommodation part

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a space between each of the moving membranes 5 and the piston P (driven part) is filled with incompressible liquid

Methodology Applied
Scientific EffectHydraulic pressure transmission: Pascal's Law

Implementation Method 3

a negative-pressure port P5 through which a negative pressure is generated between each of the dividing membranes 4 and a corresponding one of the moving membranes 5 in such a manner as to bring the dividing membrane 4 and the moving membrane 5 into close contact with each other

Methodology Applied
Scientific EffectNegative pressure: Vacuum

Data Source

PatentEP4685350A1Pump device
Publication Date: 2026.01.28 NIKKISO CO LTD
  • EP4685350A1 patent drawingFigure 1~2
  • EP4685350A1 patent drawingFigure 3
  • EP4685350A1 patent drawingFigure 4~5

AI summary

Provided is a pump device in which remaining dialysate or drain liquid is prevented from scattering to the outside when a chamber is detached from a pump body. A pump device 1 includes a supply chamber 2 having a supply-side accommodation part S1; a drain chamber 3 having a drain-side accommodation part S2; dividing membranes 4 each being a flexible member that closes a corresponding one of the supply-side accommodation part S1 and the drain-side accommodation part S2, the dividing membranes 4 being displaceable relative to the supply-side accommodation part S1 and the drain-side accommodation part S2 in such a manner as to cause dialysate to be suctioned into and discharged from the supply-side accommodation part S1 through a liquid-supply-side connection port and cause drain liquid to be suctioned into and discharged from the drain-side accommodation part S2 through a liquid-drain-side connection port; and a pump body 7 from and to which the supply chamber 2 or the drain chamber 3 is detachable and attachable with the supply-side accommodation part S1 or the drain-side accommodation part S2 being closed by the corresponding dividing membrane 4, the pump body 7 including a piston P configured to move with activation of a motor M and in such a manner as to displace the dividing membranes 4.