Pump rotor

Abstract

The present invention discloses a pump rotor, comprising: a rotating shaft and blades; the blade roots of the blades are fixed to the periphery of the rotating shaft in a cylindrical spiral manner; the blades are divided into two or more layers along the blade height direction, and blade parameters are designed for each of the two or more layers; the inlet installation angles of the blades at the blade leading edges are different from the blade roots to the blade tips; a swept portion is provided at the blade leading edges, and the sweep angle of the blade is defined as the angle between the curve of the blade leading edge along the blade height direction and the radial direction. The sweep angle of each of the two or more layers takes a value within the sweep angle range and is connected to form the leading edge curve of the blade; the outer diameter D2 of the impeller housing of the pump rotor is set to be less than 10 mm, the hub ratio range is set to 0.15 to 0.75, the root diameter D1 is obtained, the ratio range of the axial length L of the blade to the outer diameter of the impeller housing is 1 to 2, and the ratio of the radial outlet height b of the blade to the outer diameter of the impeller housing is 0 to 1.5. The pump rotor of the embodiment of the present application can achieve the same head at a lower rotational speed, reduce the risk of high-speed rotors in the human body, and prevent hemolysis from occurring.

Description

Technical Field

[0001] The embodiments of the present application relate to pump technology in the medical field, and particularly to a blood pump rotor. Background Art

[0002] Currently, during some major surgeries, especially heart surgeries, while ensuring surgical operations on the heart, it is also necessary to keep the blood of the medical subject flowing normally, ensure the normal circulation of the medical subject's blood, and enable the medical subject to maintain normal vital signs.

[0003] Currently, a blood pump device is commonly used to promote the normal circulation of the blood of the medical subject during the surgery, that is, one end of the blood pump device with a blood pump is inserted into the ventricle of the medical subject, and the other end of the blood pump device is inserted into the artery of the heart. Through the operation of the blood pump, the blood in the ventricle of the heart is pumped into the artery of the medical subject, thereby ensuring the normal blood circulation of the medical subject and enabling the blood of the medical subject to still flow normally when performing heart-related surgeries on the medical subject.

[0004] However, for the blood pump in the current blood pump device, since it is required to pump blood, the requirements for the pump, especially the rotor of the pump, are extremely high. Considering that the blood pump needs to be inserted into the body of the medical subject, therefore, the overall size of the pump rotor is designed to be as small as possible. One of the major indicators for designing a relatively small size of the pump rotor is to improve the pumping efficiency of the pump rotor. If the pumping efficiency of the pump rotor can be increased high enough, then when the blood pumping volume can be satisfied, the sizes of the blades of the pump rotor can be designed relatively smaller, and in this way, it is convenient to insert the pump rotor into the body of the medical subject more easily.

[0005] Regrettably, in the design of the pump rotor, there have been many studies on the pumping efficiency, but the efficiency improvement is not obvious. Summary of the Invention

[0006] In view of this, one aspect of the embodiments of the present application provides a pump rotor that can pump sufficient blood for the medical subject. Due to the relatively high pumping efficiency, even if the blade size of the pump rotor is designed to be smaller and the rotational speed is lower, the blood supply pumping efficiency for the medical subject can still be achieved.

[0007] The embodiments of the present application provide a pump rotor, including: a rotating shaft and blades; the blade roots of the blades are fixed on the periphery of the rotating shaft in a cylindrical helical line manner;

[0008] The blades are divided into two or more layers along the blade height direction, and blade parameters are designed for each of the two or more layers;

[0009] The inlet installation angles of the blades at the blade leading edge are different from the blade root to the blade tip;

[0010] The leading edge of the blade is provided with a swept portion. The sweep angle of the blade is defined as the angle between the curve of the leading edge of the blade along the blade height direction and the radial direction. The sweep angle range is ±50°. The sweep angle of each layer of the two or more layers takes a value within the sweep angle range and is connected to form the leading edge curve of the blade;

[0011] Set the impeller housing diameter D2 of the pump rotor to be less than 10 mm, the hub ratio range is set to 0.15 - 0.75 to obtain the root diameter D1 of the blade. The ratio range of the axial length L of the blade to the impeller housing diameter is 1 - 2, and the ratio of the radial outlet height b of the blade to the impeller housing is 0 - 1.5; the tip clearance range is 0.15 - 1 mm. Then the blade height h = (D2 - D1 - 2δ) / 2, where δ is the tip clearance.

[0012] As an implementation, the blade radius of the m-th layer of the two or more layers n is the total number of the two or more layers;

[0013] The circumferential rotational speed of the m-th layer is obtained from the designed rotational speed N of the pump rotor From the designed inlet flow rate The inlet axial velocity of this layer is obtained The blade inlet installation angle is calculated at the m-th layer as

[0014] As an implementation, the calculated blade inlet installation angle of the m-th layer takes the theoretical calculated value α m ±15°.

[0015] As an implementation, the outlet angle β of each layer of the two or more layers takes the included angle range with the circumferential direction as 30° - 90°.

[0016] As an implementation, the blade inlet installation angle of each layer of the two or more layers gradually changes from α m to β along the axial direction, constructs the distribution of the blade angle φ along the way, obtains the blade center line of each layer of the two or more layers. The wrap angle of the blade around the axis is the same or different for each layer, the wrap angle is greater than or equal to 90°, and the absolute value of the difference in the wrap angle of each layer of the two or more layers does not exceed 20° at most.

[0017] As an implementation, the blade center lines of each layer of the two or more layers are superimposed with the thickness distribution to form the blade curve on each layer, and the superimposed thickness of the blade center lines does not exceed 1.5 mm.

[0018] As an implementation, the blade has a flexible part and a rigid part along the radial direction, and the flexible part and the rigid part are integrally and smoothly connected;

[0019] The flexible part of the blade is located radially at the lower part, and a part of the flexible part of the blade is fixed to the periphery of the rotating shaft in a cylindrical spiral manner as the blade root; or, the rigid part of the blade is located radially at the lower part, and a part of the rigid part of the blade is fixed to the periphery of the rotating shaft in a cylindrical spiral manner as the blade root.

[0020] As an implementation manner, the elastic modulus of the material of the flexible part is 8 Mpa to 80 Mpa; the elastic modulus of the material of the rigid part is 35 Mpa to 195 Mpa, and the elastic modulus of the material of the flexible part is less than the elastic modulus of the material of the rigid part.

[0021] As an implementation manner, the length ratio of the flexible part and the rigid part of the blade in the radial direction of the rotating shaft is 1:8 to 5:1.

[0022] As an implementation manner, the length ratio of the flexible part and the rigid part of the blade in the radial direction of the rotating shaft is 10:37, 9:26, 11:24, 4:7 or 11:14.

[0023] In the pump rotor structure of the embodiment of the present application, the blade is divided into two or more layers along the blade height direction. The leading edge of the blade is provided with a swept part, and the inlet installation angle of the blade at the leading edge is different from the root to the tip. Such a design of the pump rotor structure is more in line with the different changes in the radial velocity direction of blood in a rotary machine, enhancing the pressurization ability. It can use a smaller rotational speed to reach the same head, reducing the risk brought by the high rotational speed of the pump rotor and reducing the risk of hemolysis. In addition, the embodiment of the present application adopts a twisted and swept pump rotor design. When the flow rate is small, the working mode of the blade has no obvious difference. However, when the blood pump works to pump blood to relieve the burden on the heart, the performance of the blade in the embodiment of the present application is the best. For example, at a flow rate of 4 L / min of the rotor pump blood, the head of the blade in the embodiment of the present application is 3% higher than that of the non-twisted and swept blade in terms of pumping efficiency, 9.2% higher than that of the twisted and non-swept blade, and 27.5% higher than that of the non-twisted and non-swept blade. In this way, when the blood pump helps the heart pump blood to the same head, the pump rotor in the embodiment of the present application can use a lower rotational speed to reach the same head, reducing the risk of the high-speed rotor in the human body. At the same time, the reduction of the rotational speed can also reduce the hemolysis value of the blood. Taking the rotational speed of the twisted and non-swept rotor as 28500 (rpm: revolutions per minute) as a benchmark, the pump rotor in the embodiment of the present application only needs a rotational speed of 27800 rpm to reach the same head, and the rotational speed drops by 700 rpm. At the same time, after the hemolysis value is simulated and calculated using computational fluid dynamics (CFD), the hemolysis value of the twisted and non-swept pump rotor drops by 1.2%. Description of the Drawings

[0024] Figure 1Schematic diagram of the composition structure of the pump rotor according to an embodiment of the present application;

[0025] Figure 2 Schematic diagram of the composition structure of the swept blades of the pump rotor according to an embodiment of the present application;

[0026] Figure 3 Schematic diagram of the distribution of the blade angles of the pump rotor along the course according to an embodiment of the present application;

[0027] Figure 4 Schematic diagram of the blade layer thickness of the pump rotor according to an embodiment of the present application;

[0028] Figure 5 Schematic diagram of the profile stacking of the blades of the pump rotor according to an embodiment of the present application;

[0029] Figure 6 Schematic diagram of the shaft design curve of the pump rotor according to an embodiment of the present application;

[0030] Figure 7 Schematic diagram of the composition structure of the pump rotor in the pure axial - flow form according to an embodiment of the present application;

[0031] Figure 8 Schematic diagram of the structure of the blades of the pump rotor according to an embodiment of the present application;

[0032] Figure 9 Schematic diagram of the structure of the blades of the pump rotor according to an embodiment of the present application;

[0033] Figure 10 Schematic diagram for comparing the head - flow relationship of the pump rotor according to an embodiment of the present application;

[0034] Figure 11 Schematic diagram of the hemolysis value effect of the pump rotor according to an embodiment of the present application. Detailed implementation manners

[0035] The essence of the technical solution of the embodiment of the present application will be elaborated in detail below with reference to the accompanying drawings.

[0036] For a blood pump, the diameters of the blade roots and blade tips in the pump rotor are different. Thus, the rotational angular velocities at the blade roots and blade tips are different, and therefore the relative blood flow velocities are also different. Using straight blades with the same installation angle from the blade root to the blade tip at the blade inlet position cannot fit well with the blood flow, easily causing flow separation, reducing the work - doing ability of the blood pump, and increasing the risk of hemolysis. The diameters of human blood vessels are very thin, and the rotor pressurization ability of the blood pump is very low in the limited space of the blood vessels. This requires increasing the pressurization ability by increasing the rotational speed. However, this method of increasing pressurization by increasing the rotational speed will increase the hemolysis risk of the pump rotor. At the same time, when the pump rotor rotates at a high speed, it also has a certain degree of danger in the human body.

[0037] For the pump rotor of the embodiment of the present application, a twisted blade with a changing inlet installation angle from the blade root to the blade tip is used at the leading edge of the blade, which helps the blood flow to conform to the blade rotor, increases the work capacity of the blood pump, and reduces the generation of special flow structures. Moreover, the leading edge of the blade in the embodiment of the present application adopts a swept blade design, which can greatly improve the pressure boosting ability of the blade. This means that under the same head, the swept pump rotor of the embodiment of the present application can reach the same head at a lower rotational speed, which greatly reduces the risk of the high-speed rotor in the human body during blood pumping by the pump rotor and reduces the risk of hemolysis.

[0038] The following further clarifies the essence of the technical solution of the embodiment of the present application through specific examples.

[0039] Figure 1 It is a schematic structural diagram of the composition of the pump rotor of the embodiment of the present application. As Figure 1 shown, the pump rotor of the embodiment of the present application includes: a rotating shaft 10 and blades 20; the blade roots of the blades 20 are fixed on the periphery of the rotating shaft 10 in a cylindrical helix manner;

[0040] The blades 20 are divided into more than two layers along the blade height direction, and blade parameters are designed for each of the more than two layers;

[0041] The inlet installation angles of the blades 20 are different from the blade root to the blade tip at the leading edge of the blade;

[0042] A swept portion 30 is provided at the leading edge of the blade 20.

[0043] As Figure 1 shown, since the pump rotor of the embodiment of the present application is applied inside a medical object, therefore, it is determined that the range of the impeller housing diameter D2 of the pump rotor is less than 10 mm, and the range of the hub ratio can be roughly determined to be 0.15 - 0.75. In this way, the root diameter D1 can be determined, and the range of the ratio of the axial length L of the blade 20 to the housing diameter is roughly 1 - 2, and the range of the ratio of the radial outlet height b of the blade 20 to the housing diameter of the pump rotor is roughly 0 - 1.5. When b is 0, the impeller outlet becomes an axial outlet. In the embodiment of the present application, when the pump rotor is placed inside a medical object, the entire pump rotor needs to be placed in a pump rotor housing. Here, the housing diameter refers to the diameter of the introduction housing that accommodates the pump rotor of the embodiment of the present application. And this pump rotor housing is generally temporarily left inside the medical object, and the pump rotor works inside the pump rotor housing.

[0044] The blade design of the embodiment of the present application is as follows:

[0045] The size of the tip clearance δ should be as small as possible, but it should not affect the velocity distribution at the inner surface of the pump rotor housing and exacerbate hemolysis. Therefore, in the embodiments of the present application, the size range of the tip clearance δ is approximately 0.15 - 1 mm, and the blade height h = (D2 - D1 - 2δ) / 2.

[0046] In the embodiments of the present application, the blade 20 is divided into n layers (n >= 2) along the blade height direction, and blade parameters are designed for each layer m (1 <= m <= n).

[0047] Figure 2 It is a schematic diagram of the composition structure of the swept blade of the pump rotor in the embodiments of the present application. As Figure 2 shown, in the embodiments of the present application, the sweep angle of the blade 20 of the pump rotor is defined as the angle formed by the curve of the leading edge of the blade along the blade height direction and the radial direction. A positive angle is forward sweep, and a negative angle is backward sweep. The sweep angle range is within ±50°. The sweep angle of each layer of the blade takes a value within this range, and then the leading edge curve of the blade is connected.

[0048] In the embodiments of the present application, the radius of the blade 20 of the m-th layer is The circumferential rotational speed of this layer is obtained from the designed rotational speed N (rpm) The axial velocity at the inlet of this layer is obtained from the designed inlet flow rate The calculated blade inlet installation angle (angle with the circumferential direction) on this layer is Considering that the pumping object, i.e., blood, is viscous, which has a greater impact on the inlet velocity distribution of the pump rotor. Therefore, the blade inlet installation angle can be considered within α m ±15°. The specific blade inlet installation angle can be set based on actual requirements according to the above determination method.

[0049] In the embodiments of the present application, the outlet angle β of the blade 20 is the same for each layer. The outlet angle β of the blade 20 takes the range of the angle with the circumferential direction to be approximately within 30° - 90°. For example, the angle between the outlet angle β of the blade 20 and the circumferential direction is taken as 60°, 45°, 75°, etc.

[0050] Figure 3 It is a schematic diagram of the distribution of the blade angle along the path of the pump rotor in the embodiments of the present application. As Figure 3 shown, in the embodiments of the present application, among the blades of the pump rotor in the embodiments of the present application, with the inlet installation angle α m and β of each layer, the distribution of the blade angle φ along the path is constructed. The blade angle varies axially from α m ​Gradually changing from α to β, the center line of the blade 20 of each layer is obtained. The wrap angle of the obtained blade 20 around the rotating shaft 10 can be different for each layer, but the wrap angle is not less than 90°. The absolute value of the difference in wrap angles of all layers in the blade is at most 20°. The result of different wrap angles is that the blade profile is a bendable structure.

[0051] Figure 4 It is a schematic diagram of the blade layer thickness of the pump rotor according to the embodiment of the present application. As Figure 4 shown, in the embodiment of the present application, the blade curves on each layer are formed by superimposing the thickness distribution on the center line. The thickness range of each layer does not exceed 1.5 mm, but the thickness of each layer is different.

[0052] Figure 5 It is a schematic diagram of the blade profile stacking of the pump rotor according to the embodiment of the present application. As Figure 5 shown, in the embodiment of the present application, the three-dimensional blade profile is obtained by radially stacking the blade curves of n layers to complete the blade design. The number of blades is 2 to 6. The blade 20 moves from the equally divided position at the periphery of one end of the rotating shaft 10 in a manner of moving towards the other end of the rotating shaft. Each blade 20 is wound around the corresponding equally divided position at the periphery of the other end of the rotating shaft 10 in a parallel manner; the number of turns of the blade 20 around the periphery of the rotating shaft is 0.1 to 5 turns.

[0053] To make the structure of the pump rotor according to the embodiment of the present application more suitable for use inside a medical object, the rotating shaft 10 of the embodiment of the present application is designed as follows:

[0054] At the leading edge position of the blade 20, a straight line L1 with a length of l1 is formed by taking a section before and after it. The value range of l1 is 0 to 4 mm, and the distance D1 / 2 from the rotation center remains unchanged. When l1 is 0, the starting and ending points of the curve coincide at the leading edge position of the blade.

[0055] Figure 6 It is a schematic diagram of the rotating shaft design curve of the pump rotor according to the embodiment of the present application. As Figure 6 shown, in the embodiment of the present application, a streamline curve L2 is constructed at the starting point of L1. Along the axial direction, the distance from the rotation center gradually decreases from D1 / 2 to 0 upstream, with an axial length of l2.

[0056] As Figure 6 shown, starting from the downstream termination point of L1, a curve L3 is constructed. Along the axial direction downstream, the distance from the rotation center gradually expands and reaches the maximum distance D3 / 2 at the blade root, where D1 ≤ D3 ≤ D2. The oblique angle θ (the angle with the axial direction) of the rotating shaft at the downstream termination point of L1 is 0°, and the oblique angle θ of the rotating shaft at the blade root takes a range of 0° to 90°. These two angles are the tangent angles of the starting and ending points of the L3 curve, with an axial length of l3.

[0057] In the embodiments of the present application, a rotating shaft entity is obtained by connecting three curves and rotating them for one week. Considering the influence of machining accuracy, the largest diameter circle can be made into a boss with a thickness of τ, and the thickness of the boss does not exceed 0.5 mm. The axial length of the rotating shaft is l1 + l2 + l3 + τ, and the length is 1.1 to 2 times the axial length of the blade. Thus, the design of the rotating shaft 10 in the embodiments of the present application is completed. In the embodiments of the present application, the rotating shaft 10 designed in the foregoing manner has a more stable structure, is more suitable for the blade distribution in the pump rotor of the embodiments of the present application, and can make the pumping efficiency of the pump rotor in the embodiments of the present application higher.

[0058] 4. The blade 20 and the rotating shaft 10 are concentrically positioned so that their center lines are the same. The root of the blade 20 and the root of the rotating shaft 10 (ignoring the boss) are positionally positioned so that their axial positions are the same, and the two are superimposed to obtain the final blood pump rotor.

[0059] Example 1:

[0060] The diameter of the blade is taken as 6 mm, and the hub ratio is taken as 0.367. Therefore, the root diameter of the blade is 2.2 mm. The blade length L is defined as the ratio of the blade length at the root to the outer diameter of the casing, and the value is taken as 1.333. Therefore, the blade length is 8 mm. The ratio of the blade outlet height b to the outer diameter of the casing is taken as 0.4167. Therefore, the outlet length is 2.5 mm. The tip clearance is taken as 0.2 mm, and the blade height is 1.7 mm. The blade is divided into 3 layers along the blade height direction. The sweep angle of each layer is taken as +20°. The designed rotational speed is 28500 rpm, and the designed flow rate is 4 L / min. It is calculated that the inlet installation angle of the first layer is 18.05°, the inlet installation angle of the second layer is 25.08°, and the inlet installation angle of the third layer is: 39.68°. Considering the influence of viscosity, the inlet installation angle of the first layer is taken as 12.5°, the inlet installation angle of the second layer is taken as 27.4°, and the inlet installation angle of the third layer is taken as 41.5°. The outlet angle of all three layers is selected as 60°. The blade angle distribution along the path is constructed to obtain the center line of the blade for each layer. The blade wrap angle around the axis obtained thereby is 120° for all three layers, and the blade profile is a straight blade without camber. The thickness distribution is superimposed on the center line. The root of the blade takes an equal thickness distribution with a thickness of 0.8 mm; the tip takes an equal thickness distribution with a thickness of 0.5 mm, and the three-dimensional blade profile is obtained by stacking to form the blade. The number of blades is taken as 2. For the L1 curve in the rotating shaft, l1 is taken as 0.95 mm, D3 is taken as 5.6 mm, the bottom boss is 0.2 mm, and the total blade length is 12 mm, obtaining the design structure of the rotating shaft. The structure of this pump rotor is as Figure 1 shown.

[0061] Example 2:

[0062] Figure 7 It is a schematic diagram of the composition structure of the pure axial-flow type pump rotor in the embodiments of the present application, as Figure 7As shown in the figure, in the embodiment of the present application, the blade diameter is taken as 8 mm, the hub ratio range is taken as 0.3125, so the root diameter of the blade is 2.5 mm. The blade length L is defined as the ratio of the blade length at the root to the housing diameter, and the value is taken as 1.125, so the blade length is 9 mm. The tip clearance is taken as 0.25 mm, then the blade height is 2.625 mm. The blade is divided into 3 layers along the blade height direction. The first layer has a sweep angle of -20°, the second layer has a sweep angle of +50°, and the third layer has a sweep angle of +30°. The designed rotational speed is 20000 rpm, and the designed flow rate is 5 L / min. It is calculated that the inlet installation angle of the first layer is 13.2°, the inlet installation angle of the second layer is 19.3°, and the inlet installation angle of the third layer is 35.1°. Considering the influence of viscosity, the inlet installation angle of the first layer is taken as 10°, the inlet installation angle of the second layer is taken as 24°, and the inlet installation angle of the third layer is taken as 35°. The outlet angle of all three layers is selected as 60°. The blade angle distribution along the path is constructed to obtain the center line of each layer of the blade. From this, the blade wrap angle around the axis of all three layers is 210°. The thickness distribution is superimposed on the center line. The root and the tip of the blade both take an equal thickness distribution, with a thickness of 1 mm. By stacking, a three-dimensional blade profile is obtained to form the blade, and the number of blades is taken as 3. For the L1 curve in the rotating shaft, l1 is taken as 1 mm, D3 is taken as 3 mm, the oblique angle is taken as 10°, and the total length of the blade is 1.5 times the blade length, which is 13.5 mm, thus obtaining the designed structure of the rotating shaft.

[0063] In the embodiment of the present application, on the premise of ensuring the pumping efficiency of the pump rotor, other designs can also be made for the structure of the blade 20. Figure 8 It is a schematic structural diagram of the blade of the pump rotor in the embodiment of the present application, as Figure 8 shown, the blade 20 of the embodiment of the present application can be provided with a flexible part 201 and a rigid part 202 along the radial direction, and the flexible part 201 and the rigid part 202 are integrally and smoothly connected;

[0064] As Figure 8 shown, the flexible part 201 of the blade is located in the lower part along the radial direction, and a part of the flexible part 201 of the blade 20 is fixed to the periphery of the rotating shaft in a cylindrical helix manner as the blade root;

[0065] Or, Figure 9 It is a schematic structural diagram of the blade of the pump rotor in the embodiment of the present application, as Figure 9 shown, the rigid part 202 of the blade 20 is located in the lower part along the radial direction, and a part of the rigid part 202 of the blade 20 is fixed to the periphery of the rotating shaft in a cylindrical helix manner as the blade root.

[0066] In the embodiments of the present application, to ensure the pumping efficiency of the pump rotor, the elastic modulus of the material of the flexible part 201 is 8 Mpa to 80 Mpa; the elastic modulus of the material of the rigid part 202 is 35 Mpa to 195 Mpa, and the elastic modulus of the material of the flexible part 201 is less than that of the rigid part 202.

[0067] When adopting Figure 8 , Figure 9 For the structural design of the blade shown, the length ratio of the flexible part 201 and the rigid part 202 of the blade 20 in the radial direction of the rotating shaft 10 is 1:8 to 5:1.

[0068] As a preferred manner, the length ratio of the flexible part 201 and the rigid part 202 of the blade 20 in the radial direction of the rotating shaft 10 is 10:37, 9:26, 11:24, 4:7 or 11:14.

[0069] In the embodiments of the present application, the connection part between the blade 20 and the rotating shaft 10 is set to be flexible. In this way, when the pump rotor rotates to drive the blade 20 to rotate, when the blade 20 contacts a pumping object such as blood, under the acting force applied by the pumping object, the flexible part 201 deforms, thereby forming a pump blade structure for pumping blood, and thus pumping blood and the like to the target direction. Moreover, since part of the blade 20 is made of a flexible material, the pump rotor will have a certain protective effect on the pumping object during the rotation process, that is, the blade 20 of the pump rotor will not damage the physiological indexes of the pumping object such as blood, and ensure that the physiological indexes of the pumped blood will not be damaged.

[0070] When pumping blood for a medical object, it is very important to prevent hemolysis of the pumped blood, because if hemolysis occurs during pumping, it will endanger the life safety of the medical object.

[0071] Hemolysis refers to the phenomenon that red blood cells in the blood rupture, causing the hemoglobin inside the red blood cells to overflow and dissolve in the blood. Hemolysis will cause changes in the morphology and biochemical characteristics of red blood cells, shorten their lifespan or even completely rupture, thus reducing the ability of red blood cells to transport oxygen to tissues and organs. In addition, after hemolysis, the concentration of plasma free hemoglobin increases, and the excess free hemoglobin needs to be excreted through the kidneys, so it may cause kidney function damage and multiple organ failure. In the embodiments of the present application, the blood volume estimation is based on the quantitative relationship between the flow parameters in a simple flow field measured by experiments and the amount of hemolysis damage, and through reasonable assumptions and deformations, a hemolysis model applicable to a complex flow field is established. Currently, most of the research on quantitative hemolysis estimation is based on the power-law equation. The power-law equation describes the relationship between the hemolysis index (HI) and the shear force (τ), exposure time (t exp ) in a simple flow field:

[0072]

[0073] Among them, the hemolysis index HI is defined as the ratio of the increment of plasma free hemoglobin concentration (ΔHb) to the whole blood hemoglobin concentration (Hb). C, α, and β are constants obtained through regression analysis of experimental data.

[0074] To sum up, the size of hemolysis is related to the shear force and exposure time. When the structure design proposed in the embodiment of the present application is adopted in the blade 20 and the root part of the blade 20 is made of a flexible material, the rotor blade 20 will bend in the direction opposite to the rotation direction, so that the velocity distribution at the tip is improved, thereby reducing the magnitude of the shear force at the tip position and reducing the possibility of blood hemolysis at the tip position.

[0075] In addition, the design of the pump rotor structure in the embodiment of the present application can also avoid the formation of thrombus. The formation, movement of thrombus and its relationship with hemodynamics have always been research hotspots. Its formation and development are affected by various factors, such as hemodynamic factors such as blood wall shear force and wall pressure, and body fluid factors such as vasoactive growth mediators and inflammatory mediators in blood vessels. Blood flow velocity, viscosity, blood vessel shape and blood vessel stenosis in blood vessels will all have an important impact on the formation, distribution and movement of thrombus. For example, the mural thrombus on blood vessels will gradually calcify and even cause blood vessel obstruction; while relatively small thrombus will also flow in the human body with the blood and block small blood vessels at the stenosis to cause lesions. Therefore, deeply understanding the mutual relationship between blood fluid dynamics and thrombus, and analyzing the changes of wall shear force and pressure on the blood vessel wall have certain significance for preventing and treating thrombus.

[0076] The interaction between blood cells, mainly the interaction between platelets and coagulation proteins, leads to the formation of thrombus at the arterial lesion site. This process usually causes changes in the surface characteristics of the blood vessel wall, such as atherosclerotic lesions. Blood flow disorders, procoagulant factors, and the increase in the number of platelets and hematocrit may accelerate the formation of thrombus. Considering the interaction between blood and thrombus, a mathematical model of blood (red blood cells and plasma) is introduced, and the incompressible flow equation is as follows:

[0077]

[0078]

[0079] Where v f represents the blood velocity, T f is the stress tensor of the fluid, ρ f is the density of blood, b f is the body force, v T is the velocity of the thrombus, C2 = 1e9 is the resistance coefficient, and φ is the volume fraction of deposited platelets.

[0080] In the above-mentioned thrombus (platelet) mathematical model, the chemical and biological material reaction process of platelet deposition is described by the convection-diffusion-reaction equation as follows:

[0081]

[0082] Among them, D i refers to the diffusion coefficient of material i in the blood, [C i is the concentration of material i, and S i is the chemical reaction source term of material i.

[0083] To sum up, the interaction between blood cells in a narrow space is the main cause of thrombus formation. In the structure of the blade 20 in the embodiment of the present application, by setting a flexible part at the root of the blade, when the blade 20 of the pump rotor pumps blood, due to the deformation of the root of the blade 20 of the pump rotor, there will be no blood deposition or adhesion in the narrow area of the corner area where the blade of the pump rotor intersects with the rotating shaft. After using a flexible material at the root of the blade 20, when the pump rotor rotates, the blade bends at the root, changing the size of the angle area between the blade and the rotating shaft, reducing the possibility of blood adhesion in the angle area, and reducing the generation of thrombus at the angle area where the root of the blade intersects with the rotating shaft.

[0084] In the embodiment of the present application, the flexible material for making the flexible part 201 has certain elasticity requirements. This material has a certain elasticity and flexibility. Among them, the elastic modulus of the material of the flexible part 201 is 8 Mpa to 80 Mpa; the elastic modulus of the material of the rigid part 202 is 35 Mpa to 195 Mpa, and the elastic modulus of the material of the flexible part 201 is less than the elastic modulus of the material of the rigid part 202.

[0085] In the embodiments of the present application, although in the selection of materials for the flexible part 201, the smaller the elastic modulus of the selected material, the better, the pumping efficiency of the pump rotor also needs to be considered. Therefore, on the premise of not damaging the physiological indexes of the pumping object, such as blood, it is also necessary to ensure that the pumping efficiency is as high as possible. During the experiment on the flexible material, the elastic modulus of the material of the flexible part 201 is preferably 45.7 Mpa to 51.6 Mpa. When the flexible material is within this elastic modulus range, the damage to the physiological indexes of the pumping object, such as blood, is relatively small, and the pumping efficiency of the pump rotor can be ensured. For example, when the flexible material with an elastic modulus of 45.7 Mpa to 51.6 Mpa is used, the pumping efficiency of the pump rotor in the embodiments of the present application can reach 90.3% of the pumping efficiency of the pump rotor with fully rigid pump blades. The decrease in the pumping efficiency of the pump rotor is not obvious. For the pumping object such as blood, almost no damage to red blood cells is seen in the sampling at the target direction end, and hemolysis is basically eliminated. In addition, for the white blood cell index, hemoglobin index, serum haptoglobin index, platelet index, etc. in the blood on the target side, no damage is seen at all.

[0086] In addition, as an implementation manner, the elastic modulus of the material of the flexible part 201 in the embodiments of the present application is further preferably between 47.93 Mpa and 48.67 Mpa.

[0087] In the embodiments of the present application, there is no strict requirement for the material of the flexible part 201. It can be an alloy material that meets the above elastic modulus requirements, or a resin, synthetic resin, mixed resin, etc. material that meets the above elastic modulus requirements. In the embodiments of the present application, the flexible material of the above flexible part is preferably a resin material.

[0088] In the embodiments of the present application, there is also no corresponding requirement for the material of the rigid part 202, as long as the elastic modulus of the material of the rigid part 202 is greater than the elastic modulus of the material of the flexible part 201. Under the condition of ensuring integral processing of the rigid part 202 and the flexible part 201, the difference between the elastic modulus of the material of the rigid part 202 and the elastic modulus of the material of the flexible part 201 is preferably between 40 Mpa and 60 Mpa. In the embodiments of the present application, when the material of the flexible part 201 is a resin, the material of the rigid part 202 is preferably also a resin or other similar material with higher hardness. When the material of the flexible part 201 is an alloy, the material of the rigid part 202 is preferably also a harder alloy or metal, etc.

[0089] The pump rotor structure in the embodiments of the present application is more in line with the different changes of blood in the radial velocity direction in the rotary machinery, with enhanced pressurization ability. It can use a smaller rotational speed to reach the same head, reduce the risks brought by high rotational speed, and reduce the risk of hemolysis.

[0090] Figure 10Schematic diagram for comparing the relationship between the head and flow rate of the pump rotor according to the embodiments of the present application, as shown in Figure 10 As shown, the pump rotor of the embodiment of the present application designed by using the above method is a twisted and swept impeller structure. Under the condition that other conditions remain unchanged, schematic diagrams for comparing the head flow of pump rotors with several structural designs of having twist but no sweep, having sweep but no twist, and having neither twist nor sweep are shown. It can be seen that at low flow rates, there is no obvious difference in the pumping efficiency of the impeller structures of the four pump rotors. However, when the blood pump works to pump blood to relieve the burden on the heart, the impeller performance of the embodiment of the present application is the best. At a flow rate of 4 L / min of the rotor pumping blood, the head of the impeller of the embodiment of the present application is 3% higher than that of the impeller with sweep but no twist, 9.2% higher than that of the impeller with twist but no sweep, and 27.5% higher than that of the impeller with neither twist nor sweep.

[0091] In this way, when the blood pump helps the heart pump blood with the same head, the impeller of the embodiment of the present application can reach the same head at a lower rotational speed, reducing the risk of high-speed rotors in the human body.

[0092] Meanwhile, Figure 11 Schematic diagram of the hemolysis value effect of the pump rotor according to the embodiments of the present application, as shown in Figure 11 As shown, the reduction in the rotational speed of the pump rotor of the embodiment of the present application can also reduce the hemolysis value when pumping blood. Taking the impeller with twist but no sweep at 28500 rpm as a reference, the impeller of the embodiment of the present application only needs to rotate at 27800 rpm to reach the same head, with a rotational speed reduction of 700 rpm. At the same time, after calculating the hemolysis value using CFD, it is reduced by 1.2% compared with the impeller with twist but no sweep.

[0093] In addition, through the structural design of providing flexible parts on the blades of the pump rotor, the blades of the pump rotor always have a certain degree of flexibility during rotation, that is, there is corresponding bending deformation as the blood is pumped. This has a strong protective effect on the physiological indicators of the blood and hardly damages red blood cells. Therefore, it can ensure the physiological indicators of the pumped blood and is applicable to any medical object, especially medical objects with complications.

[0094] In addition, the features and benefits of the present invention are illustrated by referring to exemplary embodiments. Accordingly, the present invention is clearly not limited to these exemplary embodiments that illustrate some possible non-limiting combinations of these features, which may exist alone or in other combinations of features.

[0095] Those skilled in the art will readily think of other embodiments of the present disclosure after considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include the common general knowledge or conventional technical means in the technical field not disclosed in the present invention. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present invention are defined by the claims.

Claims

1. A pump rotor, characterized in that, The pump rotor includes: a rotating shaft and blades; the blade roots of the blades are fixed on the periphery of the rotating shaft in a cylindrical helix manner; The blades are divided into more than two layers along the blade height direction, and blade parameters are designed for each of the more than two layers; The inlet installation angles of the blades are different from the blade roots to the blade tips at the blade leading edges; A swept portion is provided at the blade leading edge, the sweep angle of the blade is defined as the angle between the curve of the blade leading edge along the blade height direction and the radial direction, the sweep angle range is ±50°, and the sweep angle of each of the more than two layers takes a value within the sweep angle range and is connected to form the leading edge curve of the blade; The outer diameter D2 of the impeller housing of the pump rotor is set to be less than 10 mm, the hub ratio range is set to 0.15 - 0.75, the root diameter D1 is obtained, the ratio range of the axial length L of the blade to the outer diameter of the impeller housing is 1 - 2, the ratio of the radial outlet height b of the blade to the outer diameter of the impeller housing is 0 - 1.5; the tip clearance range is 0.15 - 1 mm, then the blade height h = (D2 - D1 - 2δ) / 2, where δ is the tip clearance.

2. The pump rotor according to claim 1, wherein The blade radius of the m-th layer among the two or more layers n is the total number of the two or more layers; Obtain the circumferential rotational speed of the m-th layer from the designed rotational speed N of the pump rotor From the designed inlet flow rate Obtain the inlet axial velocity of this layer Calculate the blade inlet installation angle at the m-th layer as 3. The pump rotor according to claim 2, characterized in that, The inlet installation angle of the m-th layer of computational blades takes the theoretical calculated value α m ±15°.

4. The pump rotor according to claim 2, characterized in that, The outlet angle β of each of the more than two layers takes the included angle range with the circumferential direction as 30° - 90°.

5. The pump rotor according to claim 4, characterized in that, The blade inlet installation angle of each layer among the above two or more layers gradually changes from α m to β axially to construct the distribution of the blade angle φ along the way, and obtain the blade center line of each layer among the above two or more layers. The blade wrap angle around the axis is the same or different for each layer, the wrap angle is greater than or equal to 90°, and the absolute value of the difference in the wrap angle of each layer among the above two or more layers does not exceed 20° at most.

6. The pump rotor according to claim 5, characterized in that, The superposition thickness distribution of the blade centerlines of each of the more than two layers forms the blade curve on each layer, and the superposition thickness of the blade centerlines does not exceed 1.5 mm.

7. The pump rotor according to any one of claims 1 to 6, characterized in that, The blades have a flexible part and a rigid part along the radial direction, and the flexible part and the rigid part are integrally and smoothly connected; The flexible part of the blade is located in the lower part along the radial direction, and a part of the flexible part of the blade is fixed on the periphery of the rotating shaft in a cylindrical helix manner as the blade root; or, the rigid part of the blade is located in the lower part along the radial direction, and a part of the rigid part of the blade is fixed on the periphery of the rotating shaft in a cylindrical helix manner as the blade root.

8. The pump rotor according to claim 7, characterized in that, The elastic modulus of the material of the flexible part is 8 Mpa to 80 Mpa; the elastic modulus of the material of the rigid part is 35 Mpa to 195 Mpa, and the elastic modulus of the material of the flexible part is less than the elastic modulus of the material of the rigid part.

9. The pump rotor according to claim 8, characterized in that, The length ratio of the flexible part and the rigid part of the blade in the radial direction of the rotating shaft is 1:8 to 5:

1.

10. The pump rotor according to claim 9, characterized in that, The length ratio of the flexible part and the rigid part of the blade in the radial direction of the rotating shaft is 10:37, 9:26, 11:24, 4:7 or 11:14.

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