Catheter pump outlet structure and auxiliary blood circulation device

Abstract

The application provides a conduit pump outlet structure and an auxiliary blood circulation device. The conduit pump outlet structure comprises a diffuser arranged in an outlet frame, the outlet frame comprising a fixing ring and at least two struts, the diffuser comprising a hub and at least two guide vanes connected to the hub, the number of the guide vanes being consistent with the number of the struts, the profile edge of the guide vanes comprising a root surface and a tip surface, the root surface being the connecting surface of the guide vanes and the hub, and the tip surface being the outer surface away from the hub; the struts have the same outer profile as the tip surface of the guide vanes; when the diffuser is arranged in the outlet frame, the guide vanes and the struts are arranged one by one, so that the tip surface and the inner wall of the struts are arranged in close contact. By using the application, the resistance of blood output is reduced, and the blood pumping efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a catheter pump outlet structure. Background Technology

[0002] Heart failure patients die globally each year because their hearts cannot pump enough blood to maintain the normal metabolic needs of their body tissues. Common treatments for heart failure include medication, heart transplantation, and ventricular assist devices (VADs). For severe heart failure, medication has limited effectiveness, often requiring heart transplantation or VADs. However, heart transplant availability is limited, making VADs the primary option for patients and doctors. Percutaneously implantable artificial ventricular assist devices (VADs) are miniaturized pumping devices that can be inserted into the heart and configured to assist or replace natural heart function through circulatory or continuous pumping, providing hemodynamic support for cardiogenic shock and acute heart failure. In catheter-pumped systems, blood flows out through the outlet structure. Reducing resistance and improving pumping efficiency through outlet structure design, within the constraints of the impeller speed, remains a challenging problem. Summary of the Invention

[0003] The main technical problem solved by the embodiments of the present invention is how to reduce the resistance of blood output and improve the blood pumping efficiency through the design of the catheter pump outlet structure.

[0004] To address the aforementioned technical problems, embodiments of the present invention provide an improved outlet structure for a conduit pump. The duct pump outlet structure includes a pump casing and an impeller. The pump casing comprises a main body and an outlet frame arranged sequentially. The outlet structure includes a diffuser disposed within the outlet frame. The outlet frame includes a retaining ring and at least two support pillars. One end of each support pillar is connected to the main body of the pump casing, and the other end is connected to the retaining ring. A blood outlet is formed between adjacent support pillars. The diffuser is disposed within the outlet frame via the retaining ring. The diffuser is used to disperse and pressurize the blood driven by the impeller's rotation and output it from the blood outlet. The diffuser includes a hub and at least two guide vanes connected to the hub. The number of guide vanes is the same as the number of support pillars. The outline edge of each guide vane includes a root surface and a tip surface. The root surface is the connection surface between the guide vane and the hub, and the tip surface is the outer surface away from the hub. The support pillars have the same outer contour as the tip surface of the guide vanes. When the diffuser is disposed within the outlet frame, the guide vanes and support pillars are arranged in a one-to-one correspondence, such that the tip surface of the guide vane fits against the inner wall of the support pillar.

[0005] Preferably, the diffuser has a first end and a second end, and the second end has an external mounting groove that matches the fixing ring. When the diffuser is installed in the outlet frame, the fixing ring is disposed in the mounting groove. The hub extends from the first end to the mounting groove, and the outer diameter of the hub gradually increases from the first end to the second end.

[0006] Preferably, the tangents of the cross section of the hub along the central axis, the first end connection point, and the mounting groove connection point are all parallel to the central axis.

[0007] Preferably, both the leaf root surface and the leaf tip surface extend smoothly from the first end to the second end, and the thickness of the leaf root surface ranges from 0.5 mm to 0.6 mm; the thickness of the leaf tip surface ranges from 0.5 mm to 0.6 mm.

[0008] Preferably, the guide blade's outline edge further includes a leading edge and a trailing edge; the leading edge extends from the endpoint near the first end of the blade root surface to the endpoint near the first end of the blade tip surface; the trailing edge extends from the endpoint near the second end of the blade root surface to the endpoint near the second end of the blade tip surface; the thickness of the leading edge ranges from 0.5 mm to 0.7 mm; the thickness of the trailing edge ranges from 0.4 mm to 0.6 mm.

[0009] Preferably, the angle between the perpendicular line from the endpoint of the blade tip surface near the first end and the parallel line to the central axis of the hub is the blade tip surface inlet angle; the angle between the perpendicular line from the endpoint of the blade tip surface near the second end and the parallel line to the central axis of the hub is the blade tip surface outlet angle; the blade tip surface inlet angle is determined by the absolute outlet angle of the impeller blade tip surface.

[0010] Preferably, the central angle subtended by the arc length of the axial section of the blade tip surface spaced circumferentially along the hub is the blade tip envelope angle; the blade tip envelope angle is obtained by fitting a cubic polynomial curve.

[0011] θ2=g2x 3 -b2x 2 +c2x

[0012] Where θ2 is the blade tip envelope angle; x represents the relative position along the axial direction (z%), with the leading edge position x = 0 and the trailing edge position x = 100; a2, b2, and c2 are fitting coefficients, where 0 < 0 < 10 ... <a2<0.00002,0.001<b2<0.005,0.3<c2<0.8。

[0013] Preferably, the angle between the perpendicular line from the end point of the blade root surface near the first end and the parallel line of the central axis of the hub is the blade root surface inlet blade angle; the angle between the perpendicular line from the end point of the blade root surface near the second end and the parallel line of the central axis of the hub is the blade root surface outlet blade angle; the blade root surface inlet blade angle is determined by the absolute outflow angle of the blade root surface of the impeller.

[0014] Preferably, the central angle subtended by the arc length of the axial section of the blade root surface spaced circumferentially along the hub is the blade root envelope angle; the blade root envelope angle is obtained by fitting a cubic polynomial curve.

[0015] θ1=a1x 3 -b1x 2 +c1x

[0016] Where θ1 is the leaf root envelope angle; x represents the relative position along the axial direction (z%), with the leading edge position x = 0 and the trailing edge position x = 100; a1, b1, and c1 are fitting coefficients, where 0 < 0 < 10 ... <a1<0.00002,0.002<b1<0.006,0.1<c1<0.9。

[0017] Preferably, the axial length of the wheel hub is 3mm-5mm.

[0018] Preferably, the number of guide vanes is 2 to 5, and the guide vanes are evenly distributed along the circumference of the hub.

[0019] Preferably, each point on the blade tip surface is equidistant from the central axis of the hub.

[0020] Based on the same inventive concept, this application also provides an auxiliary blood circulation device, characterized in that it includes the catheter pump outlet structure as described above.

[0021] Compared with the prior art, the technical solutions of the embodiments of the present invention have beneficial effects.

[0022] For example, the blade structure of the catheter pump outlet structure of the present invention can reduce the resistance of blood output, improve pumping efficiency, enhance hemolysis performance, and improve the performance of the catheter pump while ensuring that blood flows smoothly at a limited impeller speed and that hemolysis performance meets medical requirements.

[0023] For example, both the leaf root surface and the leaf tip surface are smoothly extended from the first end to the second end, so that the blood flows smoothly when it flows through the leaf; the cross section of the hub along the central axis and the tangent of the connection point between the first end and the mounting groove are both set parallel to the central axis; reducing the resistance to the axial flow of blood.

[0024] For example, by selecting the leaf tip and leaf root envelope angles, the hemolysis index can be further reduced, the inlet and outlet static pressure rise can be increased, the hemolysis performance can be improved, and the performance of the duct pump can be enhanced. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the outlet structure of the duct pump in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the pump casing structure in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the diffuser structure in an embodiment of the present invention;

[0028] Figure 4 This is a cross-sectional view of the diffuser in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the diffuser hub and guide vanes in an embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of the inlet blade angle and outlet blade angle of the leaf root surface in an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of the leaf root envelope angle in an embodiment of the present invention;

[0032] Figure 8 In this embodiment of the invention, the diffuser of the straight guide vane of structure 3 and the straight support are correspondingly fitted together to form the outlet structure of the duct pump.

[0033] Figure 9 The diffuser of the inclined guide vane in structure 4 of this invention is fitted with the inclined support column to form the outlet structure of the duct pump. Detailed Implementation

[0034] To make the objectives, features, and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described below are merely for explaining the present invention and are not intended to limit the present invention. Furthermore, the same or similar reference numerals may be used in the drawings to refer to the same or similar elements in different embodiments, and descriptions of the same or similar elements in different embodiments, as well as descriptions of prior art elements, features, effects, etc., may be omitted.

[0035] As shown in this specification and claims, unless specifically indicated or obvious from the context, all numerical values ​​provided herein are modified with the term "about," which should be understood as being within the normal tolerance range in the art. "About" can be understood as allowing tolerances of percentages such as 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the numerical value.

[0036] Reference Figures 1 to 7 This invention provides a conduit pump outlet structure.

[0037] Specifically, the duct pump includes a pump casing and an impeller. The pump casing includes a pump casing body 3 and an outlet frame 2 arranged sequentially. The outlet structure of the duct pump includes a diffuser 1 disposed in the outlet frame 2. The outlet frame 2 includes a fixing ring 22 and at least two support pillars 21. One end of the support pillar 21 is connected to the pump casing body 3, and the other end is connected to the fixing ring 22. A blood pump outlet is formed between adjacent support pillars 21. The diffuser 1 is disposed in the outlet frame 2 via the fixing ring 22. The diffuser 1 is used to disperse and pressurize the blood driven by the impeller rotation and output it from the blood pump outlet. The diffuser 1 includes a hub 11 and at least two guide vanes 12 connected to the hub 11. The number of blades 12 is the same as the number of support pillars 21. The outline edge of the guide blade 12 includes a root surface 121 and a tip surface 122. The root surface 121 is the connection surface between the guide blade 12 and the hub 11, and the tip surface 122 is the outer surface away from the hub 11. The support pillar 21 has the same outer contour as the tip surface 122 of the guide blade 12. When the diffuser 1 is installed in the outlet frame 2, the guide blades 12 and the support pillars 21 are arranged in a one-to-one correspondence, so that the tip surface 122 is fitted to the inner wall of the support pillar 21. When blood flows out from the pump outlet, the support pillar 21 will not block the flow of blood, reduce the resistance of blood output, and improve the pumping efficiency.

[0038] In a specific embodiment, the pump housing body 3, the support column 21, and the fixing ring 22 are integrally cut from a metal round tube.

[0039] In some embodiments, the number of guide vanes 12 is 2 to 5, and the guide vanes 12 are evenly distributed along the circumference of the hub 11.

[0040] In a specific embodiment, there are 3 guide vanes 12, which are arranged in a centrally symmetrical manner around the hub 11.

[0041] In some embodiments, every point on the blade tip surface 122 is equidistant from the central axis of the hub 11.

[0042] In some embodiments, the axial length of the wheel hub is 3mm-5mm.

[0043] In a specific embodiment, the blade tip surface 122 is located on a cylindrical surface coaxial with the hub, and the support is formed by dividing the blade tip surface 122 of the guide blade 12 of the diffuser 1 on a cylindrical surface with the same inner diameter as the pump casing, so that the support 21 has the same outer contour as the blade tip surface 122 of the guide blade 12.

[0044] In some embodiments, the diffuser 1 has a first end 14 and a second end 15. The second end 15 is provided with an external mounting groove 13 that matches the retaining ring 22. When the diffuser 1 is installed in the outlet frame 2, the retaining ring 22 is disposed in the mounting groove 13. The hub 11 extends from the first end 14 to the mounting groove 13, and the outer diameter of the hub 11 gradually increases from the first end to the second end.

[0045] In some embodiments, the cross section of the hub 11 along the central axis and the tangent of the connection point between the first end and the mounting groove are both set parallel to the central axis; reducing the resistance to axial flow of blood.

[0046] In some embodiments, both the root surface 121 and the tip surface 122 extend smoothly from the first end 14 to the second end 15, allowing blood to flow smoothly when passing through the guide vane 12. The thickness of the root surface 121 ranges from 0.5 mm to 0.6 mm. The blade profile of the root surface can be designed with a uniform thickness from the leading edge to the trailing edge, or it can be designed with a non-uniform thickness. The thickness of the trailing edge can be appropriately reduced, which can reduce trailing edge loss and improve hydraulic performance. The thickness of the tip surface 122 ranges from 0.5 mm to 0.6 mm. To ensure that the blade profile of the tip surface fits snugly with the outer frame during installation, the blade profile of the tip surface is designed with a uniform thickness from the leading edge to the trailing edge.

[0047] In some embodiments, the outline edge of the guide blade 12 further includes a leading edge 123 and a trailing edge 124; the leading edge 123 extends from the end point near the first end 14 of the root surface 121 to the end point near the first end 14 of the top surface 122; the trailing edge 124 extends from the end point near the second end 15 of the root surface 121 to the end point near the second end 15 of the top surface 122; the thickness of the leading edge 123 is in the range of 0.5 mm to 0.7 mm; the thickness of the trailing edge 124 is in the range of 0.4 mm to 0.6 mm.

[0048] In some embodiments, the angle between the perpendicular line from the end point of the blade tip near the first end and the parallel line to the central axis of the hub is the blade tip inlet angle β3; the angle between the perpendicular line from the end point of the blade tip near the second end and the parallel line to the central axis of the hub is the blade tip outlet angle β4; the blade tip inlet angle β3 is determined by considering a certain range of variation of the absolute outflow angle of the impeller blade tip; the blade tip outlet angle β4 should guide the blood flow axially as much as possible and is selected based on the actual simulation effect.

[0049] The central angle subtended by the arc length of the axial section of the blade tip surface along the circumferential interval of the hub is the blade tip envelope angle θ2. The blade tip envelope angle θ2 is a non-independent variable. The blade tip inlet angle β3, the blade tip outlet angle β4, and the distribution of the blade angle along the flow direction are determined, and the blade tip envelope angle θ2 is also determined accordingly.

[0050] In some embodiments, the leaf tip envelope angle θ2 is obtained by fitting a cubic polynomial curve:

[0051] θ2=a2x 3 -b2x 2 +c2x

[0052] Where θ2 is the blade tip envelope angle; x represents the relative position along the axial direction (z%), with the leading edge position x = 0 and the trailing edge position x = 100; a2, b2, and c2 are fitting coefficients, where 0 < 0 < 10 ... <a2<0.00002,0.001<b2<0.005,0.3<c2<0.8。

[0053] In some embodiments, the angle between the perpendicular line from the end point near the first end of the blade root surface and the parallel line to the central axis of the hub is the blade root inlet blade angle β1; the angle between the tangent line from the end point near the second end of the blade root surface and the parallel line to the central axis of the hub is the blade root outlet blade angle β2; the blade root inlet blade angle β1 is determined by considering a certain range of variation of the absolute outflow angle of the blade root surface of the impeller; the blade root outlet blade angle β2 should guide the blood flow axially as much as possible and is selected based on the actual simulation effect.

[0054] The central angle subtended by the arc length of the axial section of the blade root surface along the circumferential interval of the hub is the blade root envelope angle θ1. The blade root envelope angle θ1 is a non-independent variable. If the blade root inlet blade angle β1, the blade root outlet blade angle β2, and the blade angle along the flow direction are determined, then the blade root envelope angle θ1 is also determined accordingly.

[0055] In some embodiments, the leaf root envelope angle is obtained by fitting a cubic polynomial curve:

[0056] θ1=a1x 3 -b1x 2 +c1x

[0057] Where θ1 is the leaf root envelope angle; x represents the relative position along the axial direction (z%), with the leading edge position x = 0 and the trailing edge position x = 100; a1, b1, and c1 are fitting coefficients, where 0 < 0 < 10 ... <a1<0.00002,0.002<b1<0.006,0.1<c1<0.9。

[0058] When the inlet blade angle β3 and outlet blade angle β4 on the top surface of the blade, as well as the inlet blade angle β1 and outlet blade angle β2 on the root surface of the blade, are all 0°, the guide blade 12 is in a straight line, the support column 21 is in a straight line, and the thickness of the guide blade 12 is 0.4mm-0.7mm.

[0059] Figure 8 In this embodiment of the invention, the diffuser of the straight guide vane and the straight support are correspondingly fitted together in the duct pump outlet structure; Figure 9 The diffuser of the inclined guide vane in structure 2 of this invention is a duct pump outlet structure in which the inclined support column is correspondingly fitted to the diffuser.

[0060] Blood is considered as a single-phase, incompressible Newtonian fluid with a density of 1059 kg / m³. 3 The viscosity was 0.0036 Pa·s. The fluid around the impeller rotated with the impeller, defined as the rotating domain, while the remaining part was the stationary domain. Different fluid domains were connected by interfaces. Flow field calculations were performed under steady-state conditions, using a Multiple Reference Frame (MRF) to handle the rotating region, and a frozen rotor model was used for the dynamic-static interface. Boundary conditions were set using inlet mass flow rate (equivalent to volumetric flow rate 4.5 L / min), outlet average static pressure (100 mmHg), and no-slip wall boundary conditions. The SST model was used for the turbulence model. Numerical solutions were obtained using commercial CFD software. In the solver control, high-precision solution schemes were used for both the convection term and the turbulence equations, and the time step was set to automatic. During the calculation, the outlet hemolysis index was extracted every 1000 time steps. When the outlet hemolysis index became essentially constant, the calculation results were considered to have converged.

[0061] Under the boundary conditions in Table 1 below, calculate Figure 8 and Figure 9 The hemolysis index of the two catheter pump outlet structures was determined, and the results are shown in Table 2 below; furthermore, the pump performance parameters of the two catheter pump outlet structures are shown in Table 3 below.

[0062] Table 1: Calculation of Boundary Conditions

[0063] rotational speed rpm 30000 Import mass flow rate kg / s 0.07943 Average static pressure at the outlet mmHg 100.00

[0064] Table 2. Hemolysis index at the outlet of different catheter pump structures.

[0065] hemolysis markers Structure 1 Structure 2 Export hemolytic index (%) 0.004631 0.004508

[0066] Table 3 Performance parameters of pumps with different duct pump outlet structures

[0067] Pump performance parameters unit Structure 1 Structure 2 Outlet volumetric flow rate L / min 4.501 4.501 Inlet and outlet static pressure rise mmHg 58.18 60.52

[0068] Based on the outlet hemolysis index, the outlet hemolysis index of structure 2 is less than that of structure 1 for the two catheter pump outlet structures.

[0069] Based on the pump performance parameters, under the same outlet volumetric flow rate, for the two types of duct pumps, the inlet and outlet static pressure rise of structure 2 is greater than that of structure 3; under the same outlet volumetric flow rate, the higher the inlet and outlet static pressure rise, the better the performance.

[0070] From the perspective of hemolysis and pump performance, the outlet structure of the catheter pump in structure 2 is superior.

[0071] Based on the determination that the outlet structure of the duct pump with structure 2 is superior, we will continue to study the outlet structure of the duct pump with structure 2 and explore the distribution of the leaf tip envelope angle and the leaf root envelope angle.

[0072] Table 4 below shows the values ​​of the inlet blade angle, outlet blade angle, and envelope angle for four examples. Simulation experiments were conducted, and the experimental results are shown in Tables 5 and 6 below:

[0073] Table 4 Sample Parameter Table

[0074]

[0075] Table 5. Sample Simulation Results: Export Hemolysis Index

[0076] hemolysis markers Example 1 Sample 2 Sample 3 Sample 4 Export hemolytic index (%) 0.005580 0.005492 0.005390 0.005285

[0077] Table 6 shows the pump performance parameters in the sample simulation results.

[0078] Pump performance parameters unit Example 1 Sample 2 Sample 3 Sample 4 Outlet volumetric flow rate L / min 4.5041 4.5044 4.5041 4.5039 Inlet and outlet static pressure rise mmHg 102.55 106.00 106.76 107.15

[0079] It can be seen that, under the same flow rate, the static pressure rise at the pump inlet and outlet increases sequentially from Examples 1 to 4, reaching its maximum in Example 4. Simultaneously, the hemolysis index at the outlet decreases sequentially, reaching its minimum in Example 4. In other words, Example 4 exhibits optimal outlet hemolysis performance and pump performance. Therefore, the inlet blade angle, outlet blade angle, and envelope angle corresponding to Example 4 can be considered optimally designed. In practice, to ensure good hemolysis and pump performance, the design values ​​corresponding to Examples 3 and 4, and their surrounding range, can be selected as the design parameters for the outlet guide vanes.

[0080] Based on the same inventive concept, this application also provides an auxiliary blood circulation device, characterized by including the catheter pump outlet structure described above. The auxiliary blood circulation device is a pumping device used to insert into the aorta (or other vascular site) of a heart failure patient and provide circulatory support to their heart. It can assist the heart in increasing the perfusion pressure of the aorta, thereby achieving the purpose of treating heart failure. The blood vessel can include arteries or veins. Arteries can include, but are not limited to, the ascending aorta, descending aorta, abdominal aorta, pulmonary aorta, etc. Veins can include, but are not limited to, the superior vena cava or inferior vena cava, etc.

[0081] Finally, it should be noted that the axial, radial, and circumferential directions mentioned in the embodiments of the present invention refer to the axial, radial, and circumferential directions of the hub 11, respectively.

[0082] Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the invention, even when only a single embodiment is described with respect to a particular feature. The feature examples provided in this disclosure are intended to be illustrative and not limiting, unless otherwise stated. In practice, one or more technical features of the dependent claims may be combined with the technical features of the independent claims as needed and where technically feasible, and the technical features from the respective independent claims may be combined in any suitable manner rather than solely by the specific combinations listed in the claims.

[0083] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A catheter pump outlet structure, the catheter pump comprising a pump casing and an impeller, the pump casing comprising a pump casing body and an outlet frame arranged sequentially, the catheter pump outlet structure comprising a diffuser disposed in the outlet frame, the outlet frame comprising a retaining ring and at least two support pillars, one end of each support pillar being connected to the pump casing body and the other end to the retaining ring, a blood pump outlet being formed between adjacent support pillars, the diffuser being disposed in the outlet frame via the retaining ring, the diffuser being adapted to disperse and pressurize blood driven by the rotation of the impeller and output it from the blood pump outlet; characterized in that, The diffuser includes a hub and at least two guide vanes connected to the hub. The number of guide vanes is the same as the number of support columns. The outline edge of each guide vane includes a root surface and a tip surface. The root surface is the connection surface between the guide vane and the hub, and the tip surface is the outer surface away from the hub. The support column has the same outer contour as the tip surface of the guide vane. When the diffuser is installed in the outlet frame, the guide vanes and support columns are arranged in a one-to-one correspondence, such that the tip surface of the vane fits against the inner wall of the support column. The pump casing body, support column, and fixing ring are integrally cut from a metal round tube. The central angle subtended by the arc length of the axial section of the tip surface along the circumferential interval of the hub is the tip envelope angle. The tip envelope angle is obtained by fitting a cubic polynomial curve. θ2=a2x 3 -b2x 2 +c2x Where θ2 is the blade tip envelope angle; x represents the relative position along the axial direction (z%), with the leading edge position x = 0 and the trailing edge position x = 100; a2, b2, and c2 are fitting coefficients, where 0 < 0 < 10 ... <a2<0.00002,0.001<b2<0.005,0.3<c2<0.8; The central angle subtended by the arc length of the axial section of the blade root surface spaced circumferentially along the hub is the blade root envelope angle; the blade root envelope angle is obtained by fitting a cubic polynomial curve. θ1=a1x 3 -b1x 2 +c1x Where θ1 is the leaf root envelope angle; x represents the relative position along the axial direction (z%), with the leading edge position x = 0 and the trailing edge position x = 100; a1, b1, and c1 are fitting coefficients, where 0 < 0 < 10 ... <a1<0.00002,0.002<b1<0.006,0.1<c1<0.9。 2. The outlet structure of the duct pump as described in claim 1, characterized in that, The diffuser has a first end and a second end. The second end has an external mounting groove that matches the fixing ring. When the diffuser is installed in the outlet frame, the fixing ring is located in the mounting groove. The hub extends from the first end to the mounting groove, and the outer diameter of the hub gradually increases from the first end to the second end.

3. The outlet structure of the duct pump as described in claim 2, characterized in that, The tangents of the cross section of the hub along the central axis, the first end connection point, and the mounting groove connection point are all parallel to the central axis.

4. The outlet structure of the duct pump as described in claim 2, characterized in that, Both the leaf root surface and the leaf tip surface extend smoothly from the first end to the second end. The thickness of the leaf root surface ranges from 0.5 mm to 0.6 mm, and the thickness of the leaf tip surface ranges from 0.5 mm to 0.6 mm.

5. The outlet structure of the duct pump as described in claim 2, characterized in that, The guide blade's outline edge also includes a leading edge and a trailing edge; the leading edge extends from the endpoint near the first end of the root surface to the endpoint near the first end of the top surface; the trailing edge extends from the endpoint near the second end of the root surface to the endpoint near the second end of the top surface; the thickness of the leading edge ranges from 0.5mm to 0.7mm; the thickness of the trailing edge ranges from 0.4mm to 0.6mm.

6. The outlet structure of the duct pump as described in claim 2, characterized in that, The angle between the perpendicular line from the end point of the blade tip surface near the first end and the parallel line of the central axis of the hub is the blade tip surface inlet angle; the angle between the perpendicular line from the end point of the blade tip surface near the second end and the parallel line of the central axis of the hub is the blade tip surface outlet angle; the blade tip surface inlet angle is determined by the absolute outlet angle of the impeller blade tip surface.

7. The outlet structure of the duct pump as described in claim 2, characterized in that, The angle between the perpendicular line from the end point of the blade root surface near the first end and the parallel line of the central axis of the hub is the blade root surface inlet blade angle; the angle between the perpendicular line from the end point of the blade root surface near the second end and the parallel line of the central axis of the hub is the blade root surface outlet blade angle. The inlet blade angle at the blade root surface is determined by the absolute outflow angle at the blade root surface of the impeller.

8. The outlet structure of the duct pump as described in claim 1, characterized in that, The axial length of the wheel hub is 3mm-5mm.

9. The outlet structure of the duct pump as described in claim 1, characterized in that, The number of guide vanes is 2 to 5, and the guide vanes are evenly distributed along the circumference of the hub.

10. The outlet structure of the duct pump as described in claim 1, characterized in that, Every point on the blade tip surface is equidistant from the central axis of the hub.

11. A device for assisting blood circulation, characterized in that, include: The duct pump outlet structure as described in any one of claims 1-10 above.

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