Intravascular Blood Pump Drive Posts for Higher Torque Density
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Solution Overview
Problem
Existing blood pumps face issues with parasitic magnetic flux loss and increased energy consumption due to the radial extension of posts in the drive unit, leading to reduced torque and larger pump size, which is unsuitable for intravascular applications.
Innovation Solution
The blood pump design features posts with impeller-side ends that do not extend radially over the coil windings, utilizing a spacer to maintain distance and a discontinuous soft magnetic material to reduce eddy currents, thereby enhancing torque and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the posts extend radially over the coil windings to provide strong magnetic coupling, then the magnetic forces are sufficiently high, but the parasitic magnetic flux increases and torque decreases
Solution Approach 1:
The patent extracts the radially extending head portions from the posts, removing the source of parasitic magnetic flux. The posts are redesigned to have constant cross-section without radial extensions, eliminating the magnetic short-circuit paths between adjacent posts while maintaining the essential magnetic coupling function through the coil windings.
Solution Approach 2:
The patent introduces spacers that segment the magnetic circuit by creating controlled gaps between adjacent posts. This segmentation prevents parasitic magnetic flux from traveling directly between posts while maintaining the necessary magnetic coupling through the coil windings, thereby improving torque efficiency.
2Force
If large magnets are provided to achieve sufficiently strong magnetic forces, then the magnetic coupling is adequate, but the overall diameter of the blood pump increases
Solution Approach 1:
The patent changes the geometric parameters of the posts by eliminating radial extensions and maintaining constant cross-section. This parameter change optimizes the magnetic field distribution, allowing strong magnetic coupling with smaller magnet sizes, thereby reducing the overall pump diameter for intravascular applications.
Solution Approach 2:
The patent applies local quality optimization by concentrating the magnetic field strength where it is most effective—between the coil windings and impeller—rather than distributing it through radial extensions. This localized magnetic field optimization achieves sufficient coupling force with compact dimensions.
3Force
If continuous soft magnetic material is used in posts, then the magnetic coupling is strong, but eddy currents increase and heat generation rises
Solution Approach 1:
The patent segments the continuous soft magnetic material in the posts into discrete magnetic particles or granules. This segmentation interrupts the paths for eddy currents while maintaining the magnetic coupling function, thereby reducing heat generation from eddy currents while preserving the necessary magnetic forces.
4Volume of moving object
If the posts are positioned close together to reduce pump size, then the compactness is improved, but parasitic magnetic flux between posts increases
Solution Approach 1:
The patent introduces spacers as intermediary elements between adjacent posts. These spacers create controlled gaps that act as magnetic insulators, preventing parasitic magnetic flux between posts while allowing the posts to be positioned closely together for compact pump design. The spacers mediate between the competing requirements of compactness and magnetic efficiency.
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
This design improves the torque-to-axial force ratio and reduces heat generation and energy consumption, allowing for a compact, efficient, and mobile blood pump suitable for intravascular use.
Implementation Method 1
the drive unit having a plurality of static posts arranged about the axis of rotation, and each post carrying a wire coil winding and acting as a magnetic core. A control unit sequentially supplies a voltage to the coil windings to create the rotating magnetic field.
Implementation Method 2
The impeller comprises magnets which are disposed adjacent to magnets in the electric motor. Due to attracting forces between the magnets in the impeller and in the motor, rotation of the motor is transmitted to the impeller.
Implementation Method 3
utilizing a spacer to maintain distance and a discontinuous soft magnetic material to reduce eddy currents, thereby enhancing torque and reducing energy consumption.
Data Source
AI summary
This invention concerns an intravascular blood pump for percutaneous insertion into a patient's blood vessel comprising a pump casing having a blood flow inlet and a blood flow outlet and an impeller arranged in said pump casing so as to be rotatable about an axis of rotation. The impeller has blades designed for conveying blood from the inlet and outlet. The blood pump comprises a drive unit with a plurality of posts about an axis for rotating the impeller. Each of the posts has a longitudinal axis and an impeller-side end pointing towards the impeller. A coil winding is disposed around each of the posts and has an impeller-side end pointing towards the impeller. The coil windings are controllable to create a rotating magnetic field, wherein the impeller comprises a magnetic structure arranged to interact with the rotating magnetic field to cause rotation of the impeller.