Centrifugal Blood Pump Shaft Oscillation Prevention
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Solution Overview
Problem
Centrifugal blood pumps experience misalignment and oscillation due to housing expansion, leading to excessive vibration and potential hemolysis when the impeller rotates, as the separation distance between bearings increases, causing the shaft member to deviate and oscillate.
Innovation Solution
A method of manufacturing a centrifugal pump where the housing is compressed and joined using a laser welding process, with easily deformable portions to maintain a consistent separation distance between bearings, preventing oscillation and hemolysis by preloading the shaft member, thus stabilizing the shaft member's position during housing expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the housing is made expandable to accommodate blood pressure changes, then the housing can adapt to operational conditions, but the separation distance between bearings increases causing shaft misalignment and oscillation
Solution Approach 1:
The patent applies preliminary anti-action by pre-compressing the housing in the axial direction during assembly to create a pre-compression force that counteracts the expansion force generated by blood pressure. This pre-applied compressive force prevents the housing from expanding during operation, thereby maintaining constant bearing separation distance and preventing shaft misalignment and oscillation.
2Reliability
If the housing is compressed and joined in assembly state, then the separation distance between bearings is maintained constant, but the housing cannot expand to accommodate internal pressure changes
Solution Approach 1:
The housing is pre-compressed during assembly to establish a pre-compression force that maintains constant bearing separation. This pre-applied compressive force counteracts the expansion tendency, allowing the housing to maintain dimensional stability for bearing positioning while still being capable of accommodating pressure changes through the pre-established compression state.
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 method effectively prevents shaft member oscillation and hemolysis by maintaining a consistent separation distance between bearings, ensuring the centrifugal pump operates stably and reduces the risk of hemolysis, even under increased internal pressure.
Implementation Method 1
the lid member and bottom member are joined to each other by a laser welding process
Implementation Method 2
A centrifugal force applying member (i.e., impeller) is rotatably accommodated in the hollow body cavity and rotates so as to apply centrifugal force to the blood
Data Source
AI summary
A centrifugal blood pump prevents a shaft member from oscillating due to expansion of a pump housing resulting from pressurization of the blood. The centrifugal blood pump is manufactured by assembling a bottom member 21 and a lid member 22, and compressing them in a direction in which the bottom member 21 and the lid member 22 approach each other by a deformation amount along their outer circumferential walls. The lid member and the bottom member are joined while in the compressed state in order to create a preloading force between the shaft member and bearings to resist the expansion due to pressurization of the blood during use.