A pump head structure for a magnetic levitation blood pump

Abstract

The application discloses a pump head structure of a magnetic suspension blood pump capable of providing mixed flow blood flow, which comprises an upper shell, a lower shell, a rotor impeller and a rotor permanent magnet; the upper shell and the lower shell are assembled to form a blood pump cavity, the rotor impeller is located in the blood pump cavity and comprises a plurality of cantilever blades and a sealed permanent magnet cavity; the plurality of cantilever blades are located on the outer wall upper surface of the permanent magnet cavity, the permanent magnet cavity is accommodated in the lower shell, and the rotor permanent magnet is installed in the permanent magnet cavity; the lower shell comprises a hub, and the hub has a gap between the plurality of cantilever blades; the plurality of cantilever blades respectively extend in the axial direction of the hub and the radial direction of the upper shell and the lower shell, and are combined by an axial flow part and a centrifugal part in the direction from the upper shell to the lower shell; the end of the plurality of cantilever blades has a gap with the inner wall of the blood pump cavity; an inlet flow channel is arranged in the axial direction of the upper shell, and an outlet flow channel is arranged in the radial direction of the lower shell, and the liquid flow direction of the outlet flow channel is perpendicular to the liquid flow direction of the inlet flow channel.

Description

Technical Field

[0001] This invention relates to a pump head structure for a magnetically levitated blood pump, belonging to the field of medical device technology. Background Technology

[0002] In the treatment of critically ill patients with advanced heart failure, the use of circulatory support is increasing, especially with the gradual clinical application of new-generation magnetically levitated blood pumps. Currently, the main type of magnetically levitated blood pump used is the centrifugal type. The advantages of magnetically levitated centrifugal blood pumps are that the magnetic levitation function is relatively easy to implement and the impeller can provide sufficient blood flow at a relatively low speed. The disadvantage of centrifugal blood pumps is that their pressure boosting capacity is not as good as that of axial flow blood pumps, while the structural characteristics of axial flow blood pumps limit the application of magnetic levitation technology in axial flow blood pumps.

[0003] The application of magnetic levitation technology effectively reduces blood damage within the blood pump. However, if the internal structural design of the blood pump is poor, optimal blood compatibility cannot be achieved. The level of blood damage in magnetic levitation blood pumps may still be higher than that of blood pumps using mechanical bearings. Therefore, the blood compatibility of magnetic levitation blood pumps currently still relies on impeller, flow channel, and blood compatibility design to generate good blood flow. The main reason for blood damage caused by poor structure and poor flow is the complex geometry and high-speed rotation within the pump, which generates strong non-physiological shear stress, causing damage to red blood cells, mainly manifested as hemolysis and coagulation. Hemolysis refers to the process of red blood cell rupture and the release of hemoglobin into the plasma. Flow-induced coagulation is mostly caused by dead zones in the flow field. Therefore, designing blood pumps that can generate excellent blood compatibility requires structural design and flow field optimization.

[0004] Current magnetic levitation centrifugal blood pumps have several problems, such as defects in blade and flow channel design, which cause hemolysis and coagulation problems during the ventricular assist pump's operation. Applying magnetic levitation technology to axial flow blood pumps is difficult to implement, and even if it is implemented, it is impossible to solve the problem of flow dead zone or low-speed flow between the rotor and the housing.

[0005] To improve the hydraulic performance of current magnetic levitation centrifugal blood pumps and reduce the incidence of intrapump hemolysis and thrombosis, this invention combines the advantages of centrifugal and axial flow pumps, reduces the incidence of adverse events in the clinical application of ventricular assist pumps, and designs and invents a pump head structure that can provide mixed-flow blood flow for use with magnetic levitation ventricular assist pumps, with the rotor impeller hub and blades separated. This is of great significance for reducing patient complications and mortality with ventricular assist pumps. Summary of the Invention

[0006] In view of the shortcomings of existing magnetic levitation centrifugal blood pumps, such as weak pressurization capacity, large blood damage caused by flow, and insufficient flushing, the purpose of this invention is to provide a pump head structure for a magnetic levitation blood pump that can provide mixed-flow blood flow, combining the advantages of axial flow and centrifugal hydraulics to improve blood flow within the pump and reduce hemolysis and coagulation within the pump.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A pump head structure for a magnetically levitated blood pump includes an upper shell, a lower shell, a rotor impeller, and a rotor permanent magnet. The upper and lower shells are assembled to form a blood pump cavity. The rotor impeller is located within the blood pump cavity and includes multiple cantilever blades and a sealed permanent magnet cavity. The multiple cantilever blades are located on the upper surface of the outer wall of the permanent magnet cavity, which is housed within the lower shell. The rotor permanent magnet is installed within the permanent magnet cavity. The lower shell includes a hub with a gap between the hub and the multiple cantilever blades.

[0009] The multiple cantilever blades extend axially in the hub and radially in the upper and lower shells, respectively, and are composed of axial flow and centrifugal flow portions along the direction from the upper shell to the lower shell.

[0010] There is a gap between the ends of the plurality of cantilever blades and the inner wall of the blood pump cavity;

[0011] An inlet channel is provided in the axial direction of the upper shell, and an outlet channel is provided in the radial direction of the lower shell. The liquid flow direction of the outlet channel is perpendicular to the liquid flow direction of the inlet channel.

[0012] In one embodiment of the present invention, the plurality of cantilever blades are identical in shape and size, uniformly distributed on the upper surface of the outer wall of the permanent magnet cavity, and integrally formed with the upper surface of the outer wall of the permanent magnet cavity. The number of cantilever blades can be 4, 6, or 8.

[0013] In one embodiment of the present invention, the upper shell and the lower shell are assembled by welding to form a blood pump cavity.

[0014] In one embodiment of the present invention, the rotor permanent magnet is annular and is installed in the permanent magnet cavity by an interference fit.

[0015] In one embodiment of the invention, the permanent magnet cavity has a channel at its central axis for the hub to pass through.

[0016] In one embodiment of the present invention, the gap between the plurality of cantilever blades and the inner wall of the blood pump cavity is larger than the gap between the hub and the plurality of cantilever blades.

[0017] In one embodiment of the present invention, the plurality of cantilever blades are fitted by spline curves, and the connection between the axial flow portion and the centrifugal portion is tangent and has a smooth transition.

[0018] The beneficial effects of this invention are:

[0019] The pump head structure of the magnetic levitation blood pump of this invention features both axial and centrifugal flow characteristics in its blade and hub design, exhibiting excellent hydraulic properties. This effectively flushes the low-speed blood flow zone within the pump. The magnetic levitation rotor impeller in the pump head is suspended within the blood pump cavity (pump casing) via the principle of magnetic levitation bearings, eliminating any mechanical contact that could cause blood damage. This effectively solves the problem of thrombosis and can be used as an auxiliary circulation in extracorporeal membrane oxygenation (ECMO) therapy, or as an independent circulatory support. Attached Figure Description

[0020] Figure 1 This is a perspective view of the pump head structure of the present invention.

[0021] Figure 2 This is a cross-sectional view of the pump head structure of the present invention along the axial direction of the inlet flow channel.

[0022] Figure 3 This is a perspective view of the rotor impeller in the pump head structure of the present invention.

[0023] Figure 4 This is a perspective view of the lower shell in the pump head structure of the present invention.

[0024] Figure label:

[0025] 1. Upper shell; 2. Lower shell; 3. Rotor impeller; 4. Rotor permanent magnet; 5. Cantilever blade; 6. Permanent magnet cavity; 7. Hub; 8. Inlet flow channel; 9. Outlet flow channel. Detailed Implementation

[0026] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0027] like Figures 1-4As shown, the pump head structure for a magnetically levitated mixed-flow blood pump of the present invention includes an upper shell 1, a lower shell 2, a rotor impeller 3, and a rotor permanent magnet 4; the upper shell 1 and the lower shell 2 are assembled by welding to form a blood pump cavity, the rotor impeller 3 is located in the blood pump cavity, including multiple cantilever blades 5 and a sealed permanent magnet cavity 6; the multiple cantilever blades 5 are located on the upper surface of the outer wall of the permanent magnet cavity 6, the permanent magnet cavity 6 is housed in the lower shell 2, and the rotor permanent magnet 4 is installed in the permanent magnet cavity 6 with an interference fit; the lower shell 2 has a hub 7, which... Hub 7 extends along the central axis of lower shell 2 and has gaps between it and multiple cantilever blades 5; multiple cantilever blades 5 extend in the axial direction of hub 7 and in the radial direction of upper shell 1 and lower shell 2, respectively, and are composed of axial flow part and centrifugal part in the direction from upper shell 1 to lower shell 2; there are gaps between the ends of multiple cantilever blades 5 and the inner wall of blood pump cavity; an inlet flow channel 8 is provided in the axial direction of upper shell 1, and an outlet flow channel 9 is provided in the radial direction of lower shell 2, with the liquid flow direction of outlet flow channel 9 perpendicular to the liquid flow direction of inlet flow channel 8.

[0028] like Figure 2 , 3 As shown, the rotor impeller 3 has an annular groove structure (forming an annular groove between adjacent cantilever blades) and a hollow permanent magnet cavity structure for mounting the rotor permanent magnet. Multiple cantilever blades 5 are identical in shape and size, evenly distributed on the outer surface of the permanent magnet cavity 6, and integrally formed with the outer surface of the permanent magnet cavity. The number of cantilever blades 5 can be 4, 6, or 8; the figure shows 4. The permanent magnet cavity has a channel 10 at its central axis for the hub to pass through. Figure 2 , 4 As shown, the hub 7 extends upwards through the channel towards the upper shell, and a gap is also formed between the hub and the cantilever blades, meaning the hub and blades are separate. A gap structure is used between the rotor impeller 3 and the lower shell 2. Preferably, the gap size between the aforementioned multiple cantilever blades and the inner wall of the blood pump cavity is larger than the gap size between the hub and the multiple cantilever blades.

[0029] As shown in Figure 3, multiple cantilever blades are composed of an axial flow section near the upper shell and a centrifugal section near the lower shell. The axial flow section and the centrifugal section are tangent at the connection point and have a smooth transition. The multiple cantilever blades are fitted by spline curve fitting, and a specific fitting method, such as fitting with a sixth-order polynomial function, can be used. The position of the connection point between the axial flow section and the centrifugal section, as well as the overall size of the cantilever blade, can be adjusted according to actual needs.

[0030] For example, in a specific embodiment of the present invention, the impeller inlet diameter (also called impeller inner diameter) formed by multiple cantilever blades around the hub is 10 mm, and the impeller outlet diameter (also called impeller outer diameter) formed by multiple cantilever blades near the inner wall of the blood pump cavity is 45 mm; the width of each cantilever blade along the hub axis, i.e., the inlet width, is 16 mm, and the outlet width near the inner wall of the blood pump cavity is 6.6 mm; the blade inlet angle is 17°, the blade outlet angle is 32°, and the outer diameter L of the axial flow in the front half is 28 mm. The blade profile fitting curve is fitted using a 6th-order polynomial function, and the polynomial formula is: y = 4E-06x^6 - 0.0008x^5 + 0.0666x^4 - 3.0135x^3 + 75.337x^2 - 983.64x + 5229.5; R = 0.9995; where x and y are the coordinates of the points on the blade profile, and R is the confidence level. The closer R is to 1, the more accurate it is.

[0031] The installation process of the pump head structure of the present invention is as follows:

[0032] The permanent magnet of the rotor is installed in the permanent magnet cavity and sealed. For example, the permanent magnet can be installed in the permanent magnet cavity of the rotor impeller by interference fit and sealed with a bottom cover. Then the permanent magnet cavity is placed in the lower shell, and multiple cantilever blades are placed on the upper surface of the outer wall of the permanent magnet cavity. The gap between the cantilever blades and the hub and the inner wall of the lower shell is adjusted. Finally, the upper cover and the lower cover are welded together to complete the assembly of the pump head structure.

[0033] The working principle of the pump head structure of this invention is as follows:

[0034] In operation, the pump head structure of this invention allows blood to enter the pump chamber through the inlet channel located axially on the upper shell. An external electromagnetic coil acts on the rotor permanent magnet of the magnetically levitated rotor impeller, causing the cantilever blades to levitate and rotate within the blood under magnetic force. The cantilever blades are streamlined blades with both axial and centrifugal sections. The blood is simultaneously subjected to the thrust of the axial section and the centrifugal force of the centrifugal section, forming a mixed-flow blood flow. Furthermore, the hub is separated from the cantilever blades, and the gap between them allows this mixed-flow blood flow to more effectively flush the low-speed blood flow zone within the pump. Specifically, centrifugal blood pumps have low flow rates and high pressure rises, while axial blood pumps have high flow rates and low pressure rises. The rotor impeller used in this invention is a mixed-flow pump impeller. The high-speed rotation of the cantilever blades generates both the centrifugal force of a centrifugal pump and the thrust of an axial pump. The mixed-flow pump performs work through the combined effect of these two forces. Compared to a centrifugal pump, it has a lower pressure rise and a higher flow rate; compared to an axial pump, it has a higher pressure rise but a lower flow rate. In addition, the blades of the axial flow section are generally grown on the hub. Without the hub structure, the axial flow section cannot function. However, if they are grown on the hub, the blades cannot rotate. Therefore, a structure with gaps between the blades and the hub can solve this problem. The secondary flow in the gaps can also serve to flush the blood.

[0035] In the pump head structure of this invention, a two-stage blade design (axial and centrifugal) and a hub-and-blade separation structure replace the traditional internal structure of a centrifugal blood pump, improving the pump's hydraulic performance. The rotor impeller is suspended within the pump casing without any mechanical contact, and there is a gap between the hub and the blades. The blood flow within this gap effectively flushes the internal flow channels, reducing the probability of clotting and minimizing the damage to the blood caused by poor flow within the pump. Furthermore, the magnetically levitated rotor impeller is suspended within the blood pump cavity using magnetic levitation, eliminating any mechanical contact with the pump cavity that could lead to blood damage and effectively addressing the problem of thrombosis.

Claims

1. A pump head structure for a magnetically levitated blood pump, characterized in that, The pump head structure includes an upper shell, a lower shell, a rotor impeller, and a rotor permanent magnet; the upper shell and the lower shell are assembled to form a blood pump cavity, the rotor impeller is located in the blood pump cavity, and includes multiple cantilever blades and a sealed permanent magnet cavity; the multiple cantilever blades are located on the upper surface of the outer wall of the permanent magnet cavity, the permanent magnet cavity is housed in the lower shell, and the rotor permanent magnet is installed in the permanent magnet cavity; The lower housing includes a hub with a gap between the hub and multiple cantilever blades; The multiple cantilever blades extend axially in the hub and radially in the upper and lower shells, respectively. They are composed of axial flow and centrifugal sections along the direction from the upper shell to the lower shell. The connection between the axial flow and centrifugal sections is tangential and has a smooth transition. There is a gap between the ends of the plurality of cantilever blades and the inner wall of the blood pump cavity; The gap between the plurality of cantilever blades and the inner wall of the blood pump cavity is larger than the gap between the hub and the plurality of cantilever blades; An inlet channel is provided in the axial direction of the upper shell, and an outlet channel is provided in the radial direction of the lower shell. The liquid flow direction of the outlet channel is perpendicular to the liquid flow direction of the inlet channel.

2. The pump head structure for a magnetically levitated blood pump according to claim 1, characterized in that, The multiple cantilever blades are identical in shape and size, uniformly distributed on the upper surface of the outer wall of the permanent magnet cavity, and integrally formed with the upper surface of the outer wall of the permanent magnet cavity.

3. The pump head structure for a magnetically levitated blood pump according to claim 1 or 2, characterized in that, The number of cantilever blades is 4, 6, or 8.

4. The pump head structure for a magnetically levitated blood pump according to claim 1 or 2, characterized in that, The upper shell and the lower shell are assembled by welding to form the blood pump cavity.

5. The pump head structure for a magnetically levitated blood pump according to claim 1 or 2, characterized in that, The rotor permanent magnet is ring-shaped and is installed inside the permanent magnet cavity by an interference fit.

6. The pump head structure for a magnetically levitated blood pump according to claim 1 or 2, characterized in that, The permanent magnet cavity has a channel at its central axis for the hub to pass through.

7. The pump head structure for a magnetically levitated blood pump according to claim 1 or 2, characterized in that, The multiple cantilever blades are fitted by spline curves.

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