Piston Pump Rotatable Valve Plate Occlusion Detection
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Solution Overview
Problem
Current piston pumps for medical infusion and dialysis technologies face challenges in achieving a compact construction and simple handling, particularly due to the movement of inlet and outlet ports which complicates assembly and requires significant space, and the detection of occlusions and air bubbles is hindered by creep behavior in tube deformation and the difficulty in distinguishing air bubbles using ultrasonic sensors.
Innovation Solution
A piston pump design featuring a rotatable valve plate with immobile inlet and outlet ports, integrated occlusion sensors within the ports using pressure-sensitive materials, and ultrasound sensors integrated into the ports to prevent air bubble misidentification, allowing for a compact and simplified assembly and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inlet and outlet ports are attached to the reciprocating valve plate to enable continuous pumping, then pumping functionality is improved, but device complexity and space requirements increase significantly
Solution Approach 1:
The pump is divided into two functional modules: a reciprocating valve plate module that handles fluid direction and a rotating distributor module that handles continuous fluid supply. This segmentation allows each module to be optimized independently, reducing overall complexity while maintaining pumping functionality.
Solution Approach 2:
A rotating distributor acts as an intermediary between the reciprocating valve plate and the stationary inlet/outlet ports. It receives fluid from the valve plate and distributes it to the ports, enabling continuous pumping without requiring the ports themselves to move.
2Difficulty of detecting and measuring
If tube deformation is used for occlusion detection, then occlusion detection capability is improved, but creep behavior causes measurement inaccuracy
Solution Approach 1:
The mechanical tube deformation method is replaced with an optical measurement system. A light source and detector measure the inner diameter of the tube optically, eliminating the creep behavior inherent in mechanical deformation methods and providing accurate, stable measurements.
3Difficulty of detecting and measuring
If ultrasonic sensors are used for air bubble detection, then air bubble detection capability is improved, but difficulty in distinguishing air bubbles from fluid remains
Solution Approach 1:
The system uses optical absorption characteristics (analogous to color changes) to distinguish air bubbles from fluid. The light source emits light at a wavelength absorbed by the infusion fluid but transmitted by air bubbles, creating a detectable signal difference that enables accurate identification.
4Difficulty of detecting and measuring
If separate sensor components are used for occlusion and air bubble detection, then detection functionality is improved, but device complexity and space requirements increase
Solution Approach 1:
The occlusion sensor and air bubble detector are merged into a single integrated sensor unit. Both detection functions share common components such as the tube holder, light source, and detector, eliminating the need for separate sensor assemblies and reducing overall device complexity.
Solution Approach 2:
The integrated sensor unit performs multiple functions: it detects occlusions through inner diameter measurements, identifies air bubbles through absorption characteristics, and can potentially measure fluid properties. This multi-functionality eliminates the need for separate dedicated sensors for each detection type.
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
The design achieves a compact and accurate fluid pumping system with improved occlusion and air bubble detection, reducing the need for separate sensor components and simplifying handling, while minimizing space requirements and avoiding the issues of creep behavior and manual tube deformation.
Implementation Method 1
an elastomer which behaves physically analogously to a pressure membrane. The port forms a hard component insensitive to pressure which does not deform under the occurring pressure changes. Due to the occurring deformations of the sensor component as soft component, the internal pressure in the port can on the other hand be determined.
Implementation Method 2
air bubble detection in medical infusion sets as well as in dialysis applications is prescribed as a necessity. Usually the recognition occurs via ultrasonic transmitters and receivers which are coupled sonically on both sides to the tube piece to be observed.
Data Source
AI summary
A piston pump is described for pumping a fluid. The pump includes at least one cylinder having a piston movable inside the cylinder along the longitudinal axis of the cylinder by a drive, each cylinder having at an end face a mounting flange having at least one cylinder opening, and a chamber having a volume that changes when the associated piston is moved in the cylinder. The piston pump has an inlet port for supplying and an outlet port for draining the fluid. A rotatable valve plate is arranged on the other side of the mounting flange. The mounting flange has at least one passage in the region of the inlet port and the outlet port, respectively, through which the fluid can flow between the inlet port and/or the outlet port and the other side of the mounting flange. The valve plate has fluid-transporting means by which, upon rotation of the valve plate at least one cylinder opening can be connected to a passage of the inlet and/or the outlet port.