Spherical Blood Pump Rotor Mounting for Tilt Without Wall Contact
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Solution Overview
Problem
Existing blood pumps face challenges with radial tilting of the rotor, leading to increased friction, thrombogenicity, and mechanical wear, which complicates miniaturization and stability, especially due to the need for complex control systems and potential contact between the rotor and channel walls.
Innovation Solution
An axial fluid pump design featuring a rotor mounted within a spherical section of the fluid channel, allowing for tilting without contact, utilizing a combination of mechanical, hydrodynamic, and magnetic bearings to maintain a constant minimal distance and prevent friction, with a passively magnetic rocker bearing for preload and stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a mechanical bearing is used to support the rotor axially, then the rotor can be mechanically mounted with good axial guidance, but blood can penetrate into the bearing and cause thrombogenicity and increased friction
Solution Approach 1:
The patent replaces the traditional mechanical bearing system with a magnetic bearing system that uses magnetic fields to support and guide the rotor axially. This substitution eliminates mechanical contact between the rotor and bearing surfaces, preventing blood penetration into the bearing gap and the associated thrombogenicity while maintaining stable axial guidance through magnetic forces.
Solution Approach 2:
The patent employs a hydrodynamic bearing concept where blood itself is used as the lubricant and suspension element. By creating a fluid film between the rotor and bearing surfaces, the system allows the rotor to float on the blood, eliminating direct mechanical contact and preventing blood activation while maintaining axial guidance through the fluid pressure distribution.
2Adaptability or versatility
If the rotor is radially deflected to follow radially active forces, then the rotor can accommodate bearing stiffness, but the axial support surface is reduced and wear increases
Solution Approach 1:
The patent replaces the mechanical radial bearing system with a magnetic bearing system that provides radial support through magnetic fields. This allows the rotor to be radially centered and stable without mechanical contact, preventing wear on the axial support surface while maintaining adaptability to radial forces through magnetic field adjustment.
3Object-affected harmful factors
If a fully magnetic mounting is used to suspend the rotor contactlessly, then thrombogenicity is reduced, but extensive control electronics are required and the pump base is enlarged
Solution Approach 1:
The patent uses a hydrodynamic bearing system where blood serves as the lubricant and suspension medium. This passive fluid-based support system eliminates the need for active magnetic control electronics while maintaining contactless support and reducing thrombogenicity, thereby simplifying the device complexity.
Solution Approach 2:
The system allows the blood itself to perform the bearing function by creating a self-sustaining hydrodynamic film that automatically supports and centers the rotor without requiring external control systems. The blood flow pattern itself provides the necessary stabilization, making the system self-regulating.
4Adaptability or versatility
If the blade gap is made large to accommodate return properties of magnetic bearings, then radial tilting is allowed, but blade losses are intrinsically increased
Solution Approach 1:
The patent replaces the magnetic bearing system with a hydrodynamic bearing system where the blood flow pattern is optimized to provide both radial centering and tilt accommodation. The fluid dynamic pressure distribution allows the rotor to follow radial forces while maintaining an optimal small blade gap, preventing both excessive blade losses and thrombogenicity.
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 enhances the pump's robustness, miniaturization, and safety by minimizing friction and contact risks, reducing thrombogenicity and maintaining efficient operation across varying flow rates, while simplifying the control system and reducing mechanical stress on components.
Implementation Method 1
a passively magnetic bearing is present, wherein the passively magnetic bearing is formed as a rocker bearing for axially preloading the rotor with respect to the fluid channel
Implementation Method 2
the fluid channel has a spherical section, the rotor has a rotor body and a conveying element that is arranged within the spherical section of the fluid channel and that is suitable to generate an at least regionally substantially spherical rotational area of the rotor
Data Source
AI summary
A fluid pump conveys a fluid, such as blood. A fluid channel that is bounded by a channel wall and a rotor arranged in the fluid channel and that is rotatably mounted about a pivot point of the bearing with a mechanical, hydrodynamic and/or hydrostatic, axial and radial bearing. The fluid channel has a spherical section and the rotor has a rotor body and a conveying element that is arranged within the spherical section of the fluid channel and configured to generate a substantially spherical rotational area of the rotor. The spherical center of the spherical section of the fluid channel and the spherical center of the spherical rotational area substantially coincide with the pivot point so that a minimum distance between the rotor and the channel wall is maintained in the spherical section upon a tilting of the rotor.