An extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure

Abstract

The present invention provides an extracorporeal magnetic suspension centrifugal blood pump with a central magnetic pole structure, wherein the pump head includes an impeller and a pump casing, the lower bottom plate of the cylindrical chamber at the lower part of the pump casing is concave to form a central cylindrical shell, and the lower bottom plate outside the corresponding pump casing forms a central tube cavity; the blades in the impeller are fixed on the base, the base is a cylindrical shell, a pipe section is arranged inside it, and the permanent magnet is fixed in the annular chamber between the pipe section and the shell; the impeller is sleeved on the central cylindrical shell; there is a W-shaped secondary flow channel between the impeller base and the cylindrical chamber of the pump casing and between the pipe section and the central cylindrical shell; the magnetic suspension device is below the pump casing, and the stator soft iron in the magnetic suspension element includes a central columnar soft iron, and the central tube cavity of the pump casing is inserted on the central columnar soft iron to form a central magnetic pole. The centrifugal blood pump can reduce thrombosis and hemolysis, and improve the stability and operation efficiency of the pump.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a magnetically suspended centrifugal blood pump for short- to medium-term extracorporeal use in patients, and in particular to a non-implantable extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure for use in situations where extracorporeal circulation cannot be separated after cardiac surgery (postoperative cardiogenic shock, pulmonary hypertension crisis after correction of congenital heart disease, support after heart transplantation), difficult-to-correct low cardiac output, transition before heart transplantation, inability to achieve spontaneous circulation after cardiopulmonary resuscitation, and other situations requiring short- to medium-term ventricular assist pump intervention treatment, so as to maintain effective circulation and reduce cardiac work. Background Art

[0002] Generally speaking, short- and medium-term heart assist pumps are mainly used for extracorporeal circulation. Acute heart failure, severe fulminant myocarditis, post-cardiac surgery, acute myocardial infarction and other diseases and conditions will not only reduce the blood supply to tissues and organs, but also may cause cardiac arrest at any time. In the treatment of such diseases, the role of auxiliary circulation has received more and more attention. At present, the main auxiliary circulation method used is imported artificial cardiopulmonary support (ECMO). ECMO can not only improve the oxygenation and blood supply of other organs and the heart itself, but also control the risk of cardiac arrest. It is also used in cardiopulmonary resuscitation after cardiac arrest. It is a standard short-term cardiac life support resuscitation tool and a short-term treatment method for cardiogenic shock. Its auxiliary time is generally about two weeks. Its disadvantage is that it increases the afterload of the left heart, is not conducive to tissue perfusion, affects coronary perfusion, and causes great damage to the blood. Thrombosis and hemolysis in the ventricular assist pump in the ECMO component are also important factors restricting the clinical application of ECMO. Thrombosis causes complications and increases the risk of death in patients, which cannot meet the needs of critical heart failure treatment. Therefore, it is of great significance to solve the blood compatibility problems such as hemolysis and high incidence of thrombosis of extracorporeal short- and medium-term ventricular assist devices, and to design and invent a ventricular assist pump that can be used extracorporeally in the short and medium term and can reduce patient complications and mortality.

[0003] At present, there are two main types of extracorporeal auxiliary blood pumps commonly used by patients during surgery: centrifugal blood pumps and roller blood pumps. Centrifugal blood pumps have been used more and more in recent years. However, compared with implantable blood pumps for long-term use, the blood compatibility problems of blood pumps used in vitro, such as high incidence of hemolysis and thrombosis, are more serious. The problem with using implantable blood pumps for long-term use in vitro in the short and medium term is that the manufacturing is difficult and the cost is high. Therefore, it is necessary to design a low-cost blood pump with stable performance, simple structure, low incidence of hemolysis and thrombosis, short-term and medium-term use, and the ability to reduce patient complications and mortality based on the characteristics of extracorporeal use.

[0004] The existing extracorporeal short- to medium-term ventricular assist pumps have problems with magnetic levitation control and blood damage caused by the vibration of the rotor impeller: the magnetic levitation rotor impeller in the pump head is unstable and vibrates under the dynamic load formed by the impact of blood. The vibration will disrupt the flow field in the pump, thereby aggravating the occurrence of blood damage such as hemolysis in the pump. The unstable and unreliable suspension of the magnetic levitation rotor impeller also makes it easy for the impeller to hit the pump casing, causing the pump to stop. Summary of the invention

[0005] The purpose of the present invention is to improve the deficiencies of the prior art and provide an extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure, which can be used in the short and medium term in vitro and can reduce complications and mortality of patients.

[0006] The object of the present invention is achieved in that:

[0007] An extracorporeal magnetic suspension centrifugal blood pump with a central magnetic pole structure comprises a pump head and a magnetic suspension device.

[0008] The pump head comprises a magnetic suspension rotor impeller and a pump casing, wherein the magnetic suspension rotor impeller is located in the pump casing, and a gap is provided between the magnetic suspension rotor impeller and the pump casing to flush the secondary flow channel.

[0009] The structure of the pump head is as follows:

[0010] The pump casing comprises a volute, a central hole is provided on the upper top surface of the volute along the central axis, a central inlet pipe is fixedly connected to the central hole, a tangential outlet pipe is provided on the outer edge of the volute, a cylindrical chamber connected to the volute is provided at the lower part of the volute, a lower bottom plate of the cylindrical chamber is recessed inwardly on the central axis, and protrudes in the cylindrical chamber to form a central cylindrical shell, and correspondingly, a central tube cavity is formed on the lower bottom plate outside the pump casing;

[0011] The magnetic suspension rotor impeller comprises blades, permanent magnets and a base, wherein the blades are fixedly arranged on the upper surface of the base, and the base is a cylindrical shell with a closed upper bottom surface and a central through hole arranged on the upper surface, wherein a pipe section is extended from the central through hole toward the inside of the cylindrical shell, and the pipe section forms an annular chamber with the cylindrical shell of the base, and the permanent magnet is fixedly arranged in the annular chamber;

[0012] A plurality of blades are evenly fixedly arranged on the upper surface of the base around the central through hole;

[0013] The impeller is sleeved on the central column shell in the pump housing, so that under the action of the magnetic suspension force, the magnetic suspension rotor impeller is suspended and cooperates with the magnetic suspension device to form a magnetic bearing; a gap is provided between the base of the magnetic suspension rotor impeller and the cylindrical chamber of the pump housing and between the pipe section and the central column shell, so that a W-shaped secondary flow channel is formed in the pump housing;

[0014] The magnetic suspension device is arranged below the pump housing, and includes a body, which is a cylinder with a closed bottom, in which a magnetic suspension element is arranged, and the magnetic suspension element includes a stator soft iron and an electromagnetic coil. The stator soft iron is arranged in the cylinder, and the stator soft iron is arranged on the inner wall of the body. A central columnar soft iron is arranged on the lower bottom plate of the cylinder, and is connected with the stator soft iron arranged on the inner wall of the body. The cylindrical chamber of the pump housing is inserted in the middle of the stator soft iron in the cylinder on the body, and the central columnar soft iron is inserted into the central tube cavity on the lower bottom plate of the pump housing. The electromagnetic coil is arranged on the stator arranged on the inner wall in the body, and the central columnar soft iron constitutes a central magnetic pole. The magnetic suspension element and the permanent magnet in the magnetic suspension rotor impeller correspond to form a motor, and also constitute a magnetic element for adjusting the position of the magnetic suspension rotor impeller in the pump housing; the central magnetic pole structure enables the magnetic circuit of each stator magnetic pole to be closed;

[0015] The magnetic suspension device also includes a control device, which includes an impeller positioning control device and an impeller rotation control device. In the impeller positioning control device, the corresponding electromagnetic coil is connected to the impeller positioning control device to adjust the current of the electromagnetic coil to adjust the position of the magnetic suspension rotor impeller in the pump casing; the impeller rotation control device adjusts the impeller rotation and speed by controlling the current change of the electromagnet or electromagnetic coil serving as the stator to interact with the permanent magnet in the impeller.

[0016] The magnetically suspended rotor impeller is arranged in the pump casing, and the impeller is sleeved on the central magnetic pole, so that a stable bearing connection structure, i.e., a magnetically suspended bearing, is formed between the magnetically suspended rotor impeller and the pump casing. The impeller positioning control device controls the position of the magnetically suspended rotor impeller rotating in the pump casing through the magnetically suspended bearing.

[0017] Preferably, the permanent magnet inside the magnetically suspended rotor impeller has a magnetic pole arrangement that is dual to the stator soft iron.

[0018] The magnetic levitation rotor impeller is suspended in the blood in the volute-shaped pump casing of the pump head under the action of the magnetic field of the magnetic levitation element composed of stator soft iron and electromagnetic coil. The motor, i.e., the impeller rotation control device, drives the magnetic levitation rotor impeller to rotate through the permanent magnet in the magnetic levitation rotor impeller, pressurizing the blood flowing into the inlet at the center of the pump casing, and the blood is finally driven to flow out from the tangential outlet of the pump casing.

[0019] Preferably, the magnetically suspended rotor impeller comprises four pairs of eight streamlined blades, and the blade structure may have the following two designs:

[0020] One is that the eight blades are identical and are evenly fixed on the upper surface of the base in the circumferential direction.

[0021] Second, among the eight blades, two pairs of blades are longer, and the other two pairs of blades are shorter. The four longer blades and the four shorter blades are evenly fixed on the upper surface of the base at intervals, and the outer end edges of the eight blades are on a circular trajectory.

[0022] The curve of the blade has the following characteristics: it is fitted with a smooth transition spline curve to obtain the pressure rise flow performance and hemolysis performance of the pump, that is, the appropriate flow and pressure: when the impeller speed is 1500_6000 rpm, the flow range is 1L / min-10L / min, and the pressure rise is 60mmHg-600mmHg.

[0023] Preferably, the difference between the distance R1 between the inner edge of the longer blade and the rotation center of the magnetic levitation rotor impeller and the distance R2 between the inner edge of the shorter blade and the rotation center of the magnetic levitation rotor impeller is within the following numerical range: 2.0 mm-5.0 mm.

[0024] When the magnetic levitation rotor impeller is working normally, the magnetic levitation rotor impeller is located at a set position. At this time, the gap between the base of the magnetic levitation rotor impeller and the cylindrical chamber of the pump casing, and the gap between the pipe section of the magnetic levitation rotor impeller and the central cylindrical shell are 1.0mm-1.5mm.

[0025] If the gap is too small, the flow channel will not be fully flushed. At the same time, the control accuracy requirement will be higher, and the rotor impeller will easily rub against the inner wall of the pump casing during rotation; but if the gap is too large, the flow leakage will be too much, and the flow and pressure rise of the pump will not meet the requirements.

[0026] The gap between the magnetic suspension rotor impeller and the pump housing adopts the above-mentioned numerical range, which can obtain a good flushing effect as a secondary flow channel, so that the blood pump is not prone to thrombosis during use.

[0027] The blades on the magnetic levitation rotor impeller are placed in the pump casing, and the base is inserted into the central column shell in the cylindrical chamber of the pump casing. A gap is provided between the base, the cylindrical chamber and the central column shell, so that under the action of the magnetic levitation force, the magnetic levitation rotor impeller is suspended and cooperates with the magnetic levitation device to form a magnetic bearing.

[0028] Preferably, the impeller positioning control device includes a position sensor, a controller and a power amplifier, wherein the position sensor is arranged on the outer circumference of the impeller to monitor the radial displacement, radial rotation and axial displacement of the magnetic suspension rotor impeller. The position sensor can use a Hall type, eddy current type, inductive type or other displacement sensor.

[0029] The position sensor is connected to the controller to provide real-time feedback on the position of the magnetic levitation rotor impeller. The impeller positioning control device enables: when the magnetic levitation rotor, i.e., the magnetic levitation rotor impeller, deviates from the set position or the center position in the pump casing, the control device performs calculations based on the magnetic levitation rotor impeller position and a specific algorithm. The calculation results drive the power amplifier to generate current in the electromagnetic coil of the magnetic levitation control of the impeller positioning control device, providing force for the magnetic levitation rotor impeller to return to the center position, thereby ultimately allowing the magnetic levitation rotor impeller to stably suspend under the disturbance of external forces.

[0030] The specific algorithm may be, for example, PID or the like.

[0031] Preferably, the control of the magnetic suspension bearing by the impeller positioning control device includes an active magnetic suspension control system and a passive magnetic suspension control system, so as to realize five-degree-of-freedom suspension control of the magnetic suspension rotor impeller in the blood:

[0032] The first degree of freedom: the translational freedom along the axial direction, which is passive magnetic suspension control;

[0033] The second and third degrees of freedom: The two translational degrees of freedom along the radial direction are actively controlled by the active magnetic suspension control system;

[0034] The fourth and fifth degrees of freedom: The two rotational degrees of freedom along the radial direction, i.e. when the impeller of the magnetic suspension rotor is tilted, are actively controlled by the active magnetic suspension control system;

[0035] In addition, the rotation along the axial direction is actively controlled by the impeller rotation control device or the motor, that is, the permanent magnets in the magnetically suspended rotor impeller and the corresponding electromagnetic device.

[0036] The controller and power amplifier in the control device, i.e. the magnetic levitation control device, are connected to the electromagnetic coil in the magnetic levitation device, so that: during the operation of the magnetic levitation rotor impeller, the position sensor is used to detect the position of the magnetic levitation rotor impeller in real time. When the magnetic levitation rotor impeller deviates from the set position, i.e. the center position in the pump casing, the sensor sends the signal to the controller, which controls the current in the electromagnet through the power amplifier after processing. The magnetic levitation control device performs calculations based on the position and algorithm of the magnetic levitation rotor impeller, and the calculation results drive the power amplifier to generate current in the magnetic levitation control coil, i.e. the electromagnetic coil, thereby generating a change in electromagnetic force, providing a force for the magnetic levitation rotor impeller to return to the center position, and finally making the magnetic levitation rotor impeller stably suspended at a specified position under the disturbance of external force.

[0037] The function of the impeller positioning control device or magnetic suspension system is to control the magnetic suspension rotor impeller to achieve five-degree-of-freedom suspension in the blood, and the axial rotational freedom is controlled by the impeller rotation control device or motor. The advantage of this system is that the axial magnetic bearing is omitted, and the axial passive suspension is achieved by the impeller positioning control device, which saves space and power consumption.

[0038] Preferably, the controller completes the high-speed digital signal processing required for magnetic suspension control and motor rotation through an ARM processor.

[0039] The blades and flow channel design in the pump head can effectively flush the low-speed blood flow area in the pump. The magnetically levitated rotor impeller in the pump head is suspended in the pump casing through the principle of magnetic levitation bearings. There is no blood damage caused by any mechanical contact, which can effectively solve the problem of thrombosis. It can be used as an auxiliary circulation in extracorporeal membrane oxygenation (ECMO) treatment, and can also perform independent short- and medium-term circulation assistance.

[0040] The short- and medium-term magnetic suspension centrifugal blood pump for in vitro use with a central magnetic pole structure provided by the present invention adopts a magnetic suspension technology with a central magnetic pole, and replaces the mechanical bearing support of a traditional centrifugal blood pump with a magnetic suspension bearing structure of a central magnetic pole. The magnetic suspension rotor impeller is suspended in the blood without any mechanical contact with the pump housing. The position and speed of the rotor impeller are accurately adjusted by a digital signal processor system. The central magnetic pole structure can increase the support stiffness of the magnetic suspension rotor impeller, effectively suppress the vibration of the rotor impeller, reduce the risk of the magnetic suspension rotor impeller hitting the pump housing during operation, and reduce the hemolysis caused by the vibration of the magnetic suspension rotor impeller; the central magnetic pole structure can close the magnetic circuit of each stator magnetic pole, and the magnetic flux change of each magnetic pole can be independently controlled by the current change in the electromagnetic coil, thereby providing active control force for each magnetic pole, and realizing stable control of the axial and tilt directions of the rotor permanent magnet, and ensuring stability under dynamic load conditions. The magnetic suspension rotor impeller has the characteristics of a structure with a magnetic pole arrangement that is dual to the stator structure, so that the structure is simple, efficient, low in processing difficulty, and high in reliability. The secondary flow channel in the pump housing is a W-shaped flow channel, which can prevent the blood flow in the secondary flow channel from becoming the main blood flow, that is, more blood flows through the blades, so that the blood flow for the blades to do work is more, improving the pump operation efficiency. The large gap design of 1-1.5mm in the secondary flow channel allows sufficient blood to be retained in the secondary flow channel to effectively flush the flow channel, reducing the thrombosis in the pump caused by slow blood flow or flow stagnation in the flow channel, and reducing or eliminating the potential thrombosis area caused by low-speed flow between the magnetic suspension rotor impeller and the pump housing. It can not only improve the efficiency of the pump, but also effectively flush the secondary flow channel to reduce the probability of thrombosis, reducing the damage to the blood in the pump due to low flow rate and flow stagnation.

[0041] The present invention will be further described below by means of the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic structural diagram of an extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure provided by the present invention.

[0043] Figure 2 This is a schematic structural diagram of a pump head in an extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure provided by the present invention.

[0044] Figure 2a for Figure 2 A detailed schematic diagram of the pump head is shown, showing the W-shaped secondary flow channel A.

[0045] Figure 3 for Figure 2 A schematic diagram of the cutaway three-dimensional structure of the pump housing in the pump head is shown.

[0046] Figure 4 This is a schematic diagram of the three-dimensional structure of the pump head.

[0047] Figure 5 A schematic diagram of the three-dimensional structure of a magnetically suspended rotor impeller in an extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure provided by the present invention.

[0048] Figure 6 for Figure 5 The cross-sectional structural schematic diagram of the magnetic levitation rotor impeller is shown.

[0049] Figure 7 It is a schematic diagram of the three-dimensional structure of another magnetically suspended rotor impeller.

[0050] Figure 8 This is a schematic cross-sectional structural diagram of a magnetic suspension device in an extracorporeal magnetic suspension centrifugal blood pump with a central magnetic pole structure provided by the present invention.

[0051] Fig. 9 A schematic diagram of the exploded three-dimensional structure of a pump head and a magnetic suspension device of an extracorporeal magnetic suspension centrifugal blood pump with a central magnetic pole structure provided by the present invention.

[0052] Wherein: 1. pump head; 11. pump casing; 111. central inlet pipe; 112. outlet; 113. tangential outlet pipe 113; 114. cylindrical chamber; 115. central cylindrical casing; 116. central tube cavity; 12. magnetic levitation rotor impeller; 121. blades; 122. base; 123. permanent magnet; 124. pipe section; 125. annular chamber; 2. magnetic levitation device; 21. stator soft iron; 22. electromagnetic coil; 23. central cylindrical soft iron; 24. cylinder. DETAILED DESCRIPTION

[0053] like Figure 1As shown, the extracorporeal magnetic levitation centrifugal blood pump with a central magnetic pole structure provided by the present invention includes a pump head 1 and a magnetic levitation device 2. The pump head 1 includes a magnetic levitation rotor impeller 12 and a pump casing 11. The magnetic levitation rotor impeller 12 is located in the pump casing 11. The magnetic levitation rotor impeller 12 includes blades 121, a base 122 and a permanent magnet 123. There is a gap between the magnetic levitation rotor impeller 12 and the pump casing 11 to play a flushing role in the secondary flow channel.

[0054] like Figure 2 , Figure 3 and Figure 4 As shown, the pump housing 11 includes a volute 111, a central hole is provided on the upper top surface of the volute 111 along the central axis, a central inlet pipe 112 is fixedly connected to the central hole, a tangential outlet pipe 113 is provided on the outer edge of the volute 111, and the lower bottom surface of the volute 111 is closed to form a cylindrical chamber 114 connected to the volute 111. The lower bottom plate of the cylindrical chamber 114 is recessed inwardly on the central axis, and protrudes in the cylindrical chamber to form a central cylindrical shell 115, and accordingly, the lower bottom plate outside the pump housing forms a central tube cavity 116;

[0055] like Figure 5 and Figure 6 As shown, the magnetic suspension rotor impeller 12 includes blades 121, a base 122 and a permanent magnet 123. The base 122 is a cylindrical shell with a closed upper bottom surface. A central through hole is provided on the upper bottom surface. Eight streamlined blades 121 with the same shape and the same arc surface orientation are evenly fixed around the central through hole on the upper bottom surface of the base 122. A pipe section 124 is extended from the central through hole toward the inside of the cylindrical shell. The pipe section 124 forms an annular chamber 125 with the cylindrical shell of the base 122. The permanent magnet 123 is fixed in the annular chamber 125.

[0056] like Figure 7 Another embodiment of an impeller is shown. In the impeller 12', there are still eight blades. However, among the eight blades, two pairs of blades 121a are longer, and the other two pairs of blades 121b are shorter. Four longer blades and four shorter blades are evenly fixed on the upper surface of the base 122 at intervals. The outer edges of the eight blades are aligned on a circular trajectory, while the radial distances of the inner edges from the central through hole are different. The difference between the distance R1 of the longer blade 121a and the distance R2 of the shorter blade 121b is 2.0-5.0 mm; for example, it is 3.5 mm.

[0057] The curve of the blade has the following characteristics: it is fitted by a spline curve with a smooth transition based on the involute, so as to obtain a flow range of 1L / min-10L / min and a pressure rise of 60mmHg-600mmHg when the impeller speed of the pump is 1500_6000 rpm.

[0058] The hemolysis problem of the blood pump in the prior art is solved in the present invention by designing the blades and flow channels, and optimizing the flow field in the pump by numerical calculation to obtain better hemolysis performance of the pump. The flow field in the pump is closely related to hemolysis. High shear forces such as turbulence and flow separation will increase hemolysis in the pump, and improving these bad flows will reduce hemolysis. Improving the flow field in the pump is to simulate the flow field in the pump by calculation, eliminate high shear force areas such as turbulence and flow separation in the flow field as much as possible, and optimize the flow field in the pump to obtain better hemolysis performance of the pump. The above-mentioned design of the blades and the design of the blade curves can achieve the flow range and pressure rise range, which can well improve the hemolysis problem.

[0059] like Figure 2 and Figure 2a As shown, the magnetic suspension rotor impeller 12 is arranged in the pump housing 11 in this way: the blades on the magnetic suspension rotor impeller 12 are placed in the volute 111, the base 122 is inserted in the cylindrical chamber 114 of the pump housing 11, and the pipe section 124 extending from the central through hole in the base 122 toward the inside of the cylindrical chamber 114 of the cylindrical shell is inserted into the central column shell 115 in the pump housing 11, and a gap is provided between the base (122) and the cylindrical chamber (114), and a gap is also provided between the pipe section 124 and the central column shell 115, thereby forming a W-shaped secondary flow channel A. Under the action of the magnetic suspension force, the magnetic suspension rotor impeller 12 is separated from the central tube and suspended, and cooperates with the magnetic suspension device to form a magnetic bearing. At the same time, blood flows through the W-shaped secondary flow channel A.

[0060] like Figure 1 , Figure 8 and Fig. 9 As shown, a magnetic suspension device 2 is arranged below the pump housing 11. The magnetic suspension device 2 includes a body, which is a cylinder 24 with a closed bottom, in which a magnetic suspension element is arranged. The magnetic suspension element includes a stator soft iron and an electromagnetic coil. A stator soft iron 21 is arranged in the cylinder 23. The stator soft iron 21 is arranged on the inner wall of the body 23. A central columnar soft iron 23 is arranged on the lower bottom plate of the cylinder 24, which is connected to the stator soft iron 21 arranged on the inner wall of the body 24. The column of the pump housing 11 The shaped chamber 114 is inserted in the stator soft iron 21, the central columnar soft iron 23 is inserted into the central tube cavity 116 on the lower bottom plate of the pump housing 11, and the electromagnetic coil 22 is arranged on the stator 23 arranged on the inner wall in the body 24, and the central columnar soft iron 23 constitutes a central magnetic pole. The magnetic suspension element and the magnetic suspension rotor impeller correspond to form a motor and also constitute a magnetic element for adjusting the position of the magnetic suspension rotor impeller in the pump housing; the central magnetic pole structure enables the magnetic circuit of each stator magnetic pole to be closed (such as Figure 1 as shown).

[0061] The magnetic levitation device also includes a control device, to which the electromagnetic coil 22 is connected. The control device includes an impeller positioning control device and an impeller rotation control device. The impeller positioning control device enables the magnetic levitation rotor impeller 12 to suspend in the pump casing, and the impeller rotation control device enables the impeller 12 to work, i.e. rotate, and is also called a motor.

[0062] The electromagnetic coil 22 is connected to the impeller positioning control device to adjust the current of the electromagnetic coil to adjust the position of the magnetic suspension rotor impeller in the pump housing; the impeller rotation control device interacts with the permanent magnet in the impeller 12 through the current change of the electromagnetic coil to adjust the impeller rotation and speed.

[0063] The permanent magnet inside the magnetic suspension rotor impeller has a magnetic pole arrangement that is dual to the stator soft iron.

[0064] The impeller positioning control device, i.e., the magnetic suspension control device, includes an actuator, i.e., an electromagnet or an electromagnetic coil, a position sensor, a controller, and a power amplifier. The position sensor is arranged on the outer circumference of the magnetic suspension rotor impeller 12 to detect the radial displacement and axial displacement of the rotor. The position sensor can use a Hall type, eddy current type, inductive type, or other displacement sensor, which is connected to the controller to provide real-time feedback on the position of the impeller.

[0065] The controller and power amplifier in the magnetic levitation control device are connected to the electromagnetic coil 22 in the body 23, so that: during the operation of the magnetic levitation rotor impeller, the position sensor is used to detect the position of the magnetic levitation rotor impeller in real time. When the magnetic levitation rotor impeller 12 deviates from the set position, that is, the center position in the pump casing, the sensor sends the signal to the controller, and the controller controls the current in the electromagnet through the power amplifier after processing. The magnetic levitation control device performs calculations based on the position of the magnetic levitation rotor impeller 12 and the PID algorithm. The response speed is set by the designer according to needs. The calculation result drives the power amplifier to generate current in the magnetic levitation control coil, that is, the electromagnetic coil, thereby generating a change in electromagnetic force, providing a force for the magnetic levitation rotor impeller 12 to return to the center position, and finally making the magnetic levitation rotor impeller stably suspended at a specified position under the disturbance of external force.

[0066] The specific principles are as follows:

[0067] Assuming that the currents on the two electromagnet windings in the electromagnetic coil are i1 and i2 respectively, the suction force F generated by them on the magnetic suspension rotor impeller 12 and the gravity mg of the magnetic suspension rotor impeller 12 (which can be referred to as the rotor) are balanced, and the rotor is in a suspended equilibrium position. Assuming that the rotor is subjected to a downward disturbance at the equilibrium position, the rotor will deviate from its equilibrium position and move downward. At this time, the sensor detects the displacement of the rotor from its equilibrium position, and the controller converts this displacement signal into a control signal. The power amplifier converts the control signal into a control current. Relative to the initial equilibrium position, the control current of the upper electromagnet increases and the control current of the lower electromagnet decreases. Therefore, the suction force of the upper electromagnet increases and the suction force of the lower electromagnet decreases. Therefore, the upward magnetic force increases, so that the rotor moves back to the original equilibrium position. If the rotor is subjected to an upward disturbance and moves upward, the controller reduces the output current of the upper power amplifier and increases the current below. The downward force of the electromagnet increases, and the rotor can also return to the original equilibrium position. Therefore, no matter whether the rotor is disturbed upward or downward, the rotor can always be in a stable equilibrium state under the control of the controller.

[0068] The base of the magnetic levitation rotor impeller 12 is arranged on the magnetic bearing seat of the stator soft iron 21 to form a magnetic levitation bearing. The electromagnetic coil is connected to the magnetic levitation control device to adjust the current of the electromagnetic coil to adjust the position of the magnetic levitation rotor impeller 12 in the pump housing 11. An electromagnet is also arranged in the magnetic levitation device 2, which corresponds to the permanent magnet 123 on the magnetic levitation rotor impeller 12 to drive the magnetic levitation rotor impeller 12 to rotate.

[0069] Commonly used magnetic levitation bearings can be divided into active suspension control and passive suspension control according to the control method of magnetic force.

[0070] Passive suspension is generally achieved by utilizing the permanent magnetic force between permanent magnets. It has the advantages of small size and no power consumption, and does not require additional control systems and mechanisms. However, according to Earnshaw's law, permanent magnetic suspension bearings cannot achieve stable suspension in all degrees of freedom. Therefore, other suspension methods are required in at least one degree of freedom to form a five-degree-of-freedom full suspension system.

[0071] The active magnetic levitation system controls the rotor displacement in real time through electromagnetic force to achieve active suspension of the rotor. It has the characteristics of adjustable coefficients such as stiffness and damping and high control accuracy, but it requires the coordination of displacement detection systems, controllers and power amplifiers in each degree of freedom.

[0072] The control of the magnetic suspension bearing includes an active magnetic suspension system and a passive magnetic suspension system, which realizes the five-degree-of-freedom suspension of the impeller in the blood:

[0073] The first degree of freedom: the translational freedom along the axial direction, which is passive suspension control;

[0074] The second and third degrees of freedom: The two translational degrees of freedom along the radial direction are actively controlled by magnetic suspension;

[0075] The fourth and fifth degrees of freedom: the two rotational degrees of freedom along the radial direction, i.e. when the impeller is tilted, are passively controlled by the magnetic suspension system;

[0076] In addition, the rotation along the axial direction is actively controlled by the permanent magnet in the motor, i.e., the impeller, and the corresponding electromagnetic device. The function of the magnetic suspension control device is to control the magnetic suspension rotor impeller to achieve five-degree-of-freedom suspension in the blood, and the axial rotational freedom is controlled by the motor. The advantage of the device is that the axial magnetic bearing is omitted, and the axial passive suspension is achieved by using the impeller positioning control device, saving space and power consumption.

[0077] Another feature of the control device is that it improves the defect of insufficient stiffness of the magnetic suspension rotor impeller 12, that is, through active adjustment of stiffness and bearing capacity, that is, active magnetic suspension system, the current in the electromagnet or electromagnetic coil, that is, the magnetic bearing coil, can be changed to achieve real-time adjustment of the support stiffness of the magnetic suspension rotor impeller 12, which is the advantage of the system. The stiffness of the mechanically supported rotor is determined by the design, and after the processing is completed, the stiffness can no longer be adjusted. Five degrees of freedom do not necessarily have to be five groups of electromagnetic coils, and one group can control multiple degrees of freedom.

[0078] The extracorporeal magnetically suspended centrifugal blood pump provided by the invention adopts a combination of active suspension and passive suspension, which is more compact and efficient. Among the three translational degrees of freedom of the magnetically suspended rotor impeller of the blood pump, one axial translational degree of freedom is passive and two radial degrees of freedom are active. Among the three rotational degrees of freedom of the blood pump, one axial rotational degree of freedom is controlled by a motor and the other two radial rotational degrees of freedom are passively controlled.

[0079] When the magnetic suspension rotor impeller works normally, the magnetic suspension rotor impeller 12 is suspended at a set position in the pump housing 11, that is, it is placed in the center of the pump housing, that is, the rotation axis of the magnetic suspension rotor impeller 12 coincides with the axis of the pump housing 11, and the gap between the upper edge of the blade 111 in the magnetic suspension rotor impeller 12 and the inner wall of the pump housing 11 is equal to the gap between the lower edge of the blade 111 and the inner wall of the pump housing 12, and the gap between the outer edge of each blade 111 and the pump housing is also equal; in other words, the magnetic suspension rotor impeller is located at the center of the pump housing. At this time, the gap between the base 122 of the magnetic suspension rotor impeller 12 and the cylindrical chamber 114 of the pump housing 11, and the gap between the pipe section 124 of the magnetic suspension rotor impeller 12 and the central column housing 115 are large gaps, that is, the gap is 1.0mm-1.5mm. Among them, the gap between the outer edge of the blade 111 and the pump housing is preferably 1.0-2.0mm, and the gap between the upper edge and the lower edge of the blade 111 and the pump housing is 1.0-1.5mm. Of course, the gap between the impeller and the pump casing can also be equal.

[0080] The thrombosis problem of the blood pump in the prior art is solved in the present invention by two methods: no mechanical contact and large gap. If there is no mechanical contact, there will be no problem of thrombosis at the contact position. If there is a large gap, it means that the blood flow in the flow channel gap is sufficient to form an effective flushing and eliminate the thrombosis in the flow channel gap. The large gap is also a measure to improve the flow field in the pump. The large gap allows the flow channel gap to have sufficient blood flow, which can form an effective flushing and eliminate the thrombosis in the flow channel gap. If the gap is small, the blood flow rate is slow, and the flushing effect cannot be achieved, which is easy to grow thrombosis.

[0081] The present invention adopts a magnetic suspension bearing structure with a central magnetic pole to replace the mechanical bearing support of a traditional centrifugal blood pump. The magnetic suspension rotor impeller is suspended in the blood without any mechanical contact with the pump housing. The position and speed of the rotor impeller are accurately adjusted by a digital signal processor system. The central magnetic pole structure can increase the support stiffness of the magnetic suspension rotor impeller, effectively suppress the vibration of the rotor impeller, reduce the risk of the magnetic suspension rotor impeller hitting the pump housing during operation, and reduce the hemolysis caused by the vibration of the magnetic suspension rotor impeller. The secondary flow channel A in the pump head 1 is designed as a large-gap W-shaped flow channel. The groove structure of the pump housing 11, i.e., the central column housing 115, extends into the through hole of the magnetic suspension rotor impeller 12, i.e., the pipe section 124. By reducing the excessive blood flow in the secondary flow channel, the blood flow passing through the blades in the main channel is increased, thereby increasing the blood flow for the blades to do work, thereby improving the pump operation efficiency. At the same time, the large gap design of the secondary flow channel can keep the corresponding blood flow in the secondary flow channel to flush the secondary flow channel of the pump head, thereby reducing the risk of thrombosis. The extracorporeal magnetic suspension centrifugal blood pump of the present invention is composed of two separate bodies, a pump head and a magnetic suspension device. The pump head includes a pump housing and a magnetic suspension rotor impeller. The impeller includes a permanent magnet. The magnetic suspension device is composed of three structures, namely, a stator core, a motor coil and a central magnetic pole. There is a through hole structure in the middle of the magnetic suspension rotor impeller. Correspondingly, the pump housing has a groove structure extending into the through hole in the middle of the magnetic suspension rotor impeller. Correspondingly, the central magnetic pole of the magnetic suspension device extends into the groove structure of the pump housing. A large gap between the pump housing and the magnetic suspension rotor impeller can form an effective flushing through a large flow rate. The permanent magnet is interference-fitted and sealed in the magnetic suspension rotor impeller. The current generates magnetic force through the stator coil to drive the impeller to rotate, and at the same time, the rotor is suspended in the blood in the pump housing. The central magnetic pole structure of the magnetic suspension device can close the magnetic circuit of each stator magnetic pole, independently control the magnetic flux change of each magnetic pole, and provide active control force through the electromagnetic coil, so as to realize stable control of the axial and tilt directions of the rotor permanent magnet and ensure stability under dynamic load conditions.

Claims

1. An extracorporeal magnetically suspended centrifugal blood pump having a central magnetic pole structure, characterized in that: Including pump head and magnetic suspension device, The pump head comprises a magnetic suspension rotor impeller and a pump casing, wherein the magnetic suspension rotor impeller is located in the pump casing, and a gap is provided between the magnetic suspension rotor impeller and the pump casing. The pump casing comprises a volute, a central hole is provided on the upper top surface of the volute along the central axis, a central inlet pipe is fixedly connected to the central hole, a tangential outlet pipe is provided on the outer edge of the volute, a cylindrical chamber connected to the volute is provided at the lower part of the volute, a lower bottom plate of the cylindrical chamber is recessed inwardly on the central axis, and protrudes in the cylindrical chamber to form a central cylindrical shell, and correspondingly, a central tube cavity is formed on the lower bottom plate outside the pump casing; The magnetic suspension rotor impeller comprises blades, permanent magnets and a base, wherein the blades are fixedly arranged on the upper surface of the base, and the base is a cylindrical shell with a closed upper bottom surface and a central through hole on the upper surface. A pipe section is extended from the central through hole toward the inside of the cylindrical shell, and the pipe section forms an annular chamber with the cylindrical shell of the base, and the permanent magnet is fixedly arranged in the annular chamber; a plurality of blades are evenly fixedly arranged on the upper surface of the base around the central through hole, The impeller is sleeved on the central column shell in the pump shell, so that under the action of the magnetic suspension force, the magnetic suspension rotor impeller is suspended and cooperates with the magnetic suspension device to form a magnetic bearing; a gap is provided between the base of the magnetic suspension rotor impeller and the cylindrical chamber of the pump shell and between the pipe section and the central column shell, so that a W-shaped secondary flow channel is formed in the pump shell; When the magnetic suspension rotor impeller is working normally, the magnetic suspension rotor impeller is at a set position, at which time the gap between the base of the magnetic suspension rotor impeller and the cylindrical chamber of the pump housing, and the gap between the pipe section of the magnetic suspension rotor impeller and the central cylindrical housing are 1.0mm-1.5mm; The magnetic suspension device is arranged below the pump housing, and includes a body, which is a cylinder with a closed bottom, in which a magnetic suspension element is arranged, and the magnetic suspension element includes a stator soft iron and an electromagnetic coil. The stator soft iron is arranged in the cylinder, and the stator soft iron is arranged on the inner wall of the body. A central columnar soft iron is arranged on the lower bottom plate of the cylinder, and is connected with the stator soft iron arranged on the inner wall of the body. The cylindrical chamber of the pump housing is inserted in the middle of the stator soft iron in the cylinder on the body, and the central columnar soft iron is inserted into the central tube cavity on the lower bottom plate of the pump housing. The electromagnetic coil is arranged on the stator arranged on the inner wall in the body, and the central columnar soft iron constitutes a central magnetic pole. The magnetic suspension element and the permanent magnet in the magnetic suspension rotor impeller correspond to form a motor, and also constitute a magnetic element for adjusting the position of the magnetic suspension rotor impeller in the pump housing; the central magnetic pole structure enables the magnetic circuit of each stator magnetic pole to be closed; The magnetic suspension device also includes a control device, which includes an impeller positioning control device and an impeller rotation control device. In the impeller positioning control device, a corresponding electromagnetic coil is connected to the impeller positioning control device to adjust the current of the electromagnetic coil to adjust the position of the magnetic suspension rotor impeller in the pump housing; The impeller rotation control device adjusts the rotation and speed of the impeller by interacting with the permanent magnet in the impeller through the current change of the corresponding electromagnetic coil; The magnetically suspended rotor impeller includes four pairs of eight streamlined blades, and the blade structure can be designed in one of the following two ways: One is that the eight blades are identical and are evenly fixed on the upper surface of the base in the circumferential direction; Second, among the eight blades, two pairs of blades are longer, and the other two pairs of blades are shorter, and the four longer blades and the four shorter blades are evenly fixed on the upper surface of the base at intervals, and the outer end edges of the eight blades are on a circular trajectory; The impeller positioning control device comprises a position sensor, a controller and a power amplifier. The position sensor is arranged on the outer circumference of the magnetic suspension rotor impeller to monitor the radial displacement, radial rotation and axial displacement of the magnetic suspension rotor impeller.

2. The extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure according to claim 1, characterized in that: The blade curve has the following characteristics: it is fitted by a smooth transition spline curve to obtain a pump flow range of 1L / min-10L / min and a pressure rise of 60mmHg-600mmHg when the impeller speed is 1500-6000 rpm; and / or, The difference between the distance R1 between the inner edge of the longer blade and the rotation center of the magnetic levitation rotor impeller and the distance R2 between the inner edge of the shorter blade and the rotation center of the magnetic levitation rotor impeller is within the following numerical range: 2.0 mm-5.0 mm.

3. The extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure according to claim 1, characterized in that: The position sensor is connected to the controller to provide real-time feedback on the position of the magnetically suspended rotor impeller. The impeller positioning control device enables: when the magnetically suspended rotor impeller deviates from the set position or the center position in the pump casing, the control device performs calculations based on the magnetically suspended rotor impeller position and the set algorithm. The calculation results drive the power amplifier to generate current in the electromagnetic coil of the magnetically suspended control of the impeller positioning control device, providing force for the magnetically suspended rotor impeller to return to the center position, thereby ultimately allowing the magnetically suspended rotor impeller to be stably suspended under the disturbance of external forces.

4. The extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure according to claim 3, characterized in that: The algorithm is PID.

5. The extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure according to claim 1, characterized in that: The control of the magnetic bearing by the impeller positioning control device includes an active magnetic suspension control system and a passive magnetic suspension control system, so as to realize the five-degree-of-freedom suspension control of the magnetic suspension rotor impeller in the blood: The first degree of freedom: the translational freedom along the axial direction, which is passive magnetic suspension control; The second and third degrees of freedom: The two translational degrees of freedom along the radial direction are actively controlled by the active magnetic suspension control system; Fourth and fifth degrees of freedom: two rotational degrees of freedom along the radial direction, i.e. when the magnetic suspension rotor impeller is tilted, it is actively controlled by the active magnetic suspension control system; and / or, The rotation along the axial direction is actively controlled by the impeller rotation control device or the motor, that is, the permanent magnets in the magnetically suspended rotor impeller and the corresponding electromagnetic device.

6. The extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure according to claim 1, characterized in that: The controller completes the high-speed digital signal processing required for impeller positioning control and impeller rotation control through the ARM processor.

7. The extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure according to claim 1, characterized in that: The permanent magnet inside the magnetic suspension rotor impeller has a magnetic pole arrangement that is dual to the stator soft iron.

8. The extracorporeal magnetically suspended centrifugal blood pump with a central magnetic pole structure according to claim 1, characterized in that: The control device, i.e., the controller and the power amplifier in the magnetic levitation control device, are connected to the electromagnetic coil in the magnetic levitation device, so that: during the operation of the magnetic levitation rotor impeller, the position sensor is used to detect the position of the magnetic levitation rotor impeller in real time. When the magnetic levitation rotor impeller deviates from the set position or the center position in the pump housing, the sensor sends the detection signal to the controller, and the controller controls the current in the electromagnet through the power amplifier after processing. The magnetic levitation control device performs calculations based on the position of the magnetic levitation rotor impeller and the algorithm. The calculation results drive the power amplifier to generate current in the magnetic levitation control coil, i.e., the electromagnetic coil, thereby generating a change in electromagnetic force, providing a force for the magnetic levitation rotor impeller to return to the center position, and finally making the magnetic levitation rotor impeller stably suspended at a specified position under the disturbance of external force.

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