CN110559496A - External magnetic suspension centrifugal blood pump with central magnetic pole structure - Google Patents

Abstract

The invention provides an in vitro magnetic suspension centrifugal blood pump with a central magnetic pole structure, wherein a pump head comprises an impeller and a pump shell, a lower bottom plate of a cylindrical cavity at the lower part of the pump shell is recessed into a central cylindrical shell, and a central tube cavity is formed by the lower bottom plate corresponding to the outside of the pump shell; the blades in the impeller are fixedly arranged on a base, the base is a cylindrical shell, a pipe section is arranged in the cylindrical shell, and the permanent magnet is fixedly arranged in an annular cavity between the pipe section and the shell; the impeller is sleeved on the central column shell; a section of W-shaped secondary flow channel is arranged between the impeller base and the cylindrical cavity of the pump shell and between the pipe section and the central cylindrical shell; the magnetic suspension device is arranged below the pump shell, the stator soft iron in the magnetic suspension element comprises a central cylindrical soft iron, and a central tube cavity of the pump shell is inserted into the central cylindrical soft iron to form a central magnetic pole. The centrifugal blood pump can reduce thrombus and hemolysis and improve the stability and the operating efficiency of the pump.

Description

An extracorporeal magnetic levitation centrifugal blood pump with a central magnetic pole structure

technical field

The invention relates to the technical field of medical devices, in particular to a magnetic levitation centrifugal blood pump for short-to-medium-term use outside the body of a patient, and in particular to a pump used for cardiac surgery that cannot be separated from extracorporeal circulation (postoperative cardiogenic shock, congenital heart disease correction) Postoperative pulmonary hypertensive crisis, support after heart transplantation), difficult to correct low cardiac output, transition before heart transplantation, failure to achieve spontaneous circulation after cardiopulmonary resuscitation, etc. need short-term and medium-term ventricular assist pump intervention to maintain effective circulation 1. A non-implantable magnetic levitation centrifugal blood pump for extracorporeal use with a central magnetic pole structure that reduces the work of the heart.

Background technique

Generally speaking, short-to-medium-term cardiac assist pumps are mainly used for extracorporeal assisted circulation. Diseases and conditions such as acute heart failure, severe fulminant myocarditis, post-cardiac surgery, and acute myocardial infarction will not only reduce the blood supply of tissues and organs, but will also occur at any time. The possibility of cardiac arrest, the role of assisted circulation in the treatment of such diseases has received more and more attention. At present, the main means of assisted circulation is imported artificial cardiopulmonary support (ECMO). ECMO can not only improve the health of other organs and the heart. Own oxygenated blood supply, and control the risk of cardiac arrest, but also used in cardiopulmonary resuscitation after cardiac arrest, is a standard short-term cardiac life support resuscitation tool, is a cardiogenic shock This is a short-term treatment method, and its auxiliary time is generally about two weeks. Its disadvantage is that it increases the afterload of the left heart, which is not conducive to tissue perfusion, affects coronary perfusion, and greatly damages the blood. Thrombosis in the pump of the ventricular assist pump in the ECMO component Blood clots and hemolysis are also important factors restricting the clinical application of ECMO. Thrombosis leads to complications in patients 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 of hemolysis and high incidence of thrombosis of ventricular assist devices in vitro in the short and medium term, and to design and invent a ventricular assist pump that can be used in the short and medium term in vitro and can reduce the complications and mortality of patients.

At present, there are mainly two types of extracorporeal auxiliary blood pumps commonly used by patients during surgery: centrifugal blood pumps and rolling blood pumps. Centrifugal blood pumps have been used more and more in recent years. However, compared with blood pumps that can be implanted for long-term use, blood compatibility problems such as hemolysis and high incidence of thrombosis are more serious for blood pumps used in vitro at present, and the problems of using blood pumps for long-term implantable use in vitro It is difficult to manufacture and the cost is high. Therefore, according to the characteristics of in vitro use, 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 can reduce patients' complications and mortality.

The short-to-medium-term use of ventricular assist pumps in the prior art also has the problem of magnetic suspension control and blood damage caused by the vibration of the rotor impeller: the magnetic suspension rotor impeller in the pump head is unstable under the dynamic load formed by the impact of blood And there is vibration, the vibration will disturb the flow field in the pump, and then aggravate the occurrence of blood damage such as hemolysis in the pump. The unstable and unreliable suspension of the magnetic levitation rotor impeller is also prone to failures that the impeller hits the pump casing and causes the pump to stop. .

Contents of the invention

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

The purpose of the present invention is achieved like this:

An extracorporeal magnetic levitation centrifugal blood pump with a central magnetic pole structure, including a pump head and a magnetic levitation device,

The pump head includes a magnetic levitation rotor impeller and a pump casing, the magnetic levitation rotor impeller is located in the pump casing, and there is a gap between the magnetic levitation rotor impeller and the pump casing to play the role of scouring the secondary flow channel,

The structure of the pump head is as follows:

The pump casing includes a volute, a central hole is provided along the central axis on the upper top surface of the volute, a central inlet pipe is fixedly connected to the central hole, and a tangential outlet pipe is provided on the outer edge of the volute. The lower part of the shell is provided with a cylindrical chamber communicated with the volute, the lower bottom plate of the cylindrical chamber is recessed inwardly on the central axis, and a central cylindrical shell is formed in the cylindrical chamber. Correspondingly, the pump casing The outer lower base plate forms a central lumen;

The maglev rotor impeller includes blades, permanent magnets and a base, the blades are fixed on the upper surface of the base, the base is a cylindrical shell, the upper bottom surface is closed, and a central perforation is provided on the upper surface, and the center A pipe section is extended toward the interior of the cylindrical shell on the perforation, and the cylindrical shell of the base forms an annular chamber by the pipe section, and the permanent magnet is fixed in the annular chamber;

On the upper surface of the base, a plurality of blades are uniformly fixed around the central hole;

The impeller is sleeved on the central cylindrical casing in the pump casing, 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; the base of the magnetic levitation rotor impeller and the pump casing There is a gap between the cylindrical chambers and between the pipe section and the central cylindrical casing, so that a W-shaped secondary flow channel is formed in the pump casing;

The magnetic levitation device is arranged under the pump casing, and includes a body, which is a bottom-closed cylinder, in which a magnetic levitation element is arranged, and the magnetic levitation element includes a stator soft iron and an electromagnetic coil, and a stator soft iron is arranged in the cylinder. Iron, the stator soft iron is arranged on the inner wall of the body, and a central columnar soft iron is arranged on the lower bottom plate of the cylinder, which is integrated with the stator soft iron arranged on the inner wall of the body. The cylindrical cavity of the pump casing The chamber is inserted in the middle of the stator soft iron in the cylinder on the body. The central columnar soft iron is inserted into the central tube cavity on the lower bottom plate of the pump casing. An electromagnetic coil is set on the stator on the inner wall of the body. The central columnar soft iron constitutes the central magnetic pole, and the magnetic levitation element corresponds to the permanent magnet in the magnetic levitation rotor impeller to form a motor, and also constitutes a magnetic element for adjusting the position of the magnetic levitation rotor impeller in the pump casing; the structure of the central magnetic pole makes each stator The magnetic circuit of the magnetic pole is closed;

The magnetic levitation device also includes a control device, the control device 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 magnetic levitation The position of the rotor impeller in the pump casing; the impeller rotation control device interacts with the permanent magnet in the impeller by controlling the current change of the electromagnet or electromagnetic coil as the stator to adjust the rotation and speed of the impeller.

The magnetic levitation rotor impeller is arranged in the pump casing, and the impeller is sleeved on the central magnetic pole, and a stable bearing connection structure is formed between the magnetic levitation rotor impeller and the pump casing, that is, the magnetic suspension bearing, and the impeller is positioned The control device controls the position of the magnetic levitation rotor impeller rotating in the pump casing through the magnetic levitation bearing.

Preferably, the permanent magnet inside the maglev rotor impeller has a magnetic pole arrangement that is in pairs with the stator soft iron.

The magnetic levitation rotor impeller is suspended in the blood in the volute-shaped pump casing of the pump head under the magnetic field of the magnetic levitation element composed of stator soft iron and electromagnetic coil. The motor, that is, the impeller rotation control device, is driven by the permanent magnet in the magnetic levitation rotor impeller. The impeller of the magnetic levitation rotor rotates to pressurize the blood flowing in from the inlet in the center of the pump casing, and the blood finally flows out from the tangential outlet of the pump casing.

Preferably, the maglev rotor impeller includes four pairs of eight streamlined blades in total, and the blade structure can have the following two designs:

One is: the eight blades are identical, and are evenly fixed on the upper surface of the base in the circumferential direction.

The second is: among the eight blades, two pairs of blades are larger in length, and the other two pairs of blades are shorter in length, 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 track.

The curve of the blade has the following characteristics: it is fitted by 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.

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

When the magnetic levitation rotor impeller is working normally, the magnetic levitation rotor impeller is at the 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 pipe section and center column of the magnetic levitation rotor impeller The gap between shells is 1.0mm-1.5mm.

If the gap is too small, the flushing in the flow channel will be insufficient, and at the same time, the requirements for control accuracy will be higher, and the rotor impeller will easily rub against the inner wall of the pump casing during the rotation; but if the gap is too large, the flow will leak too much, and the pump will The flow rate and pressure rise cannot meet the requirements.

If the gap between the magnetic levitation rotor impeller and the pump casing adopts the above numerical range, a good flushing effect as the secondary flow channel can be obtained, so that the blood pump is not easy to generate thrombus during use.

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

Preferably, the impeller positioning control device includes a position sensor, a controller and a power amplifier, and the position sensor is arranged in the outer circumferential direction of the impeller to monitor the radial displacement, radial rotation and axial displacement of the maglev rotor impeller. The position sensor can use Hall type, eddy current type, inductive type and other displacement sensors.

The position sensor is connected with the controller to feed back the position of the maglev rotor impeller in real time, and the impeller positioning control device makes: when the maglev rotor, that is, the maglev rotor impeller deviates from the set position or the center position in the pump casing, the control The device performs calculations based on the position of the maglev rotor impeller and a specific algorithm, and the result of the calculation drives the power amplifier to generate current in the electromagnetic coil of the maglev control of the impeller positioning control device, providing the force for the maglev rotor impeller to return to the center position, and finally makes the maglev rotor impeller in the center position. Stable suspension under the disturbance of external force.

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

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 the five-degree-of-freedom suspension control of the magnetic suspension rotor impeller in the blood:

The first degree of freedom: the translational degree of freedom along the axial direction, which is passive magnetic levitation control;

The second and third degrees of freedom: the two translation degrees of freedom along the radial direction are actively controlled by the active magnetic levitation control system;

The fourth and fifth degrees of freedom: the two rotational degrees of freedom along the radial direction, that is, when the magnetic levitation rotor impeller is tilted, it is actively controlled by the active magnetic levitation control system;

In addition, the axial rotation is actively controlled by the impeller rotation control device or the motor, that is, the permanent magnet in the magnetic levitation rotor impeller and the corresponding electromagnetic device.

The control device, that is, the controller and power amplifier in the magnetic levitation control device are connected with 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 When the impeller 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. Operation, the result of the operation drives the power amplifier, generates current in the magnetic levitation control coil, that is, the electromagnetic coil, thereby generating a change in electromagnetic force, providing the force for the magnetic levitation rotor impeller to return to the center position, and finally making the magnetic levitation rotor impeller under the disturbance of the external force Suspended stably in a specified position

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

Preferably, the controller uses an ARM processor to process high-speed digital signal processing required for magnetic levitation control and motor rotation.

The design of the blades and flow channels in the pump head can effectively flush the low-speed blood flow area in the pump. The magnetic levitation rotor impeller in the pump head is suspended in the pump casing through the principle of magnetic levitation bearings, without any blood damage caused by mechanical contact, which can effectively solve the problem. For thrombosis problems, it can be used as an auxiliary circulation in extracorporeal circulation membrane lung (ECMO) therapy, and can also be used independently for short and medium-term circulation assistance.

The short-to-medium-term magnetic levitation centrifugal blood pump for extracorporeal use provided by the present invention adopts the magnetic levitation technology with the central magnetic pole, and replaces the mechanical bearing support of the traditional centrifugal blood pump with the magnetic levitation bearing structure of the central magnetic pole, and the magnetic levitation rotor impeller is suspended in the blood Without any mechanical contact with the pump casing, the position and speed of the rotor impeller can be precisely adjusted through the digital signal processor system. The central magnetic pole structure can increase the support stiffness of the magnetic levitation rotor impeller, effectively suppress the vibration of the rotor impeller, and reduce the speed of the magnetic levitation rotor impeller during operation. The risk of bumping into the pump casing and reducing the hemolysis caused by the vibration of the maglev rotor impeller; the center pole structure can close the magnetic circuit of each stator pole, and the change of the magnetic flux of each pole can be controlled independently through the change of the current in the electromagnetic coil, so that Active control force is provided for each magnetic pole, which can realize stable control of the axial direction and tilt direction of the permanent magnet of the rotor, and ensure the stability under dynamic load conditions. Inside the magnetic levitation rotor impeller, there is a magnetic pole arrangement structure that is dual to the stator structure, which makes the structure simple, high in efficiency, low in processing difficulty and high in reliability. The secondary flow channel in the pump casing 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, make more blood flow through the blades, so that the blood flow of the blades will be more, improving Pump operation efficiency, the large gap design of 1-1.5mm in the secondary flow channel allows enough blood to be effectively flushed in the secondary flow channel, reducing the thrombus formation in the pump caused by slow blood flow or stagnant flow in the flow channel , to reduce or eliminate the potential thrombus formation zone caused by low velocity flow between the maglev 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 thrombus formation, and reduce the damage to the blood caused by low flow rate and flow stagnation in the pump.

The present invention will be further described below by means of the accompanying drawings and examples.

Description of drawings

Fig. 1 is a schematic structural diagram of an extracorporeal magnetic levitation centrifugal blood pump provided by the present invention with a central magnetic pole structure.

Fig. 2 is a schematic structural view of a pump head in an extracorporeal magnetic levitation centrifugal blood pump provided by the present invention with a central magnetic pole structure.

Fig. 2a is a schematic diagram of the detailed structure of the pump head shown in Fig. 2, in which a W-shaped secondary flow channel A is shown.

Fig. 3 is a cut-away three-dimensional structural schematic diagram of the pump casing in the pump head shown in Fig. 2 .

Fig. 4 is a schematic diagram of the appearance and three-dimensional structure of the pump head.

Fig. 5 is a three-dimensional schematic diagram of a magnetic levitation rotor impeller in an extracorporeal magnetic levitation centrifugal blood pump with a central magnetic pole structure provided by the present invention.

FIG. 6 is a schematic cross-sectional structure diagram of the magnetic levitation rotor impeller shown in FIG. 5 .

Fig. 7 is a three-dimensional structural schematic diagram of another magnetic levitation rotor impeller.

Fig. 8 is a schematic cross-sectional structure diagram of the magnetic levitation device in the extracorporeal magnetic levitation centrifugal blood pump provided by the present invention with a central magnetic pole structure.

Fig. 9 is an exploded three-dimensional structural diagram of the pump head and the magnetic levitation device of the extracorporeal magnetically levitated centrifugal blood pump with a central magnetic pole structure provided by the present invention.

Among them: 1. pump head; 11. pump casing; 111. central inlet pipe; 112. outlet; 113. tangential outlet pipe 113; 114. cylindrical chamber; 115. central cylindrical shell; .maglev rotor impeller; 121. blade; 122. base; 123. permanent magnet; 124. pipe section; 125. annular chamber; 2. magnetic levitation device; 21. stator soft iron; ; 24. Cylinder.

Detailed ways

As shown in Fig. 1, the extracorporeal magnetic levitation centrifugal blood pump with 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, and the magnetic levitation rotor impeller 12 is located in the pump casing 11, the magnetic levitation rotor impeller 12 includes blades 121, base 122 and permanent magnets 123, and there is a gap between the magnetic levitation rotor impeller 12 and the pump casing 11 to play the role of flushing the secondary flow channel.

As shown in Fig. 2, Fig. 3 and Fig. 4, the pump casing 11 includes a volute 111, a central hole is provided along the central axis on the upper top surface of the volute 111, and 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 communicating with the volute 111 . The lower bottom plate of the cylindrical chamber 114 is recessed inward on the central axis, and a central cylindrical shell 115 is formed by protruding inside the cylindrical chamber, and correspondingly, the lower bottom plate outside the pump casing forms a central tube cavity 116;

As shown in FIGS. 5 and 6 , the maglev rotor impeller 12 includes blades 121 , bases 122 and permanent magnets 123 . The base 122 is a cylindrical shell with a closed upper bottom and a central perforation on the upper bottom. Around the central perforation on the upper bottom of the base 122, eight streamlined shapes with the same shape and the same arc orientation are evenly fixed. For the blade 121, a pipe section 124 is extended toward the interior of the cylindrical shell on the central perforation. The pipe section 124 forms an annular chamber 125 with the cylindrical shell of the base 122, and the permanent magnet 123 is fixed in the annular chamber 125. .

As shown in Figure 7, it is another embodiment of the impeller. In this impeller 12', there are still eight blades. However, among the eight blades, two pairs of blades 121a are relatively long, and the other two pairs of blades 121b are relatively long. Short, 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 track, and the inner edge is the diameter of the central perforation. In different directions, the difference between the distance R1 of the longer blade 121 a and the distance R2 of the shorter blade 121 b is 2.0-5.0 mm; for example, 3.5 mm.

The curve of the blade has the following characteristics: it is fitted by a spline curve with a smooth transition on the basis of the involute, so that the flow range of the pump is 1L/min-10L/min when the impeller speed is 1500_6000 rpm, Pressure rise 60mmHg-600mmHg.

The hemolysis problem of the blood pump in the prior art is solved in the present invention through the design of the vane and the flow channel, and the flow field in the pump is optimized through 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 turbulent flow 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 calculate and simulate the flow field in the pump, try to eliminate the high shear force areas such as turbulence and flow separation in the flow field, and optimize the flow field in the pump to obtain better hemolysis performance of the pump. The design of the vane and the design of the vane curve can achieve the above flow range and pressure rise range, which can well improve the hemolysis problem.

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

As shown in Fig. 1, Fig. 8 and Fig. 9, a magnetic levitation device 2 is arranged below the pump casing 11. The magnetic levitation device 2 includes a body, which is a cylinder 24 closed at the bottom, in which a magnetic levitation element is set, and the magnetic levitation element includes Stator soft iron and electromagnetic coil, the stator soft iron 21 is set in this cylinder 23, the stator soft iron 21 is arranged on the inner wall of the body 23, a central columnar soft iron 23 is set on the lower bottom plate of the cylinder 24, and is arranged on The stator soft iron 21 on the inner wall of the body 24 is connected as a whole, the cylindrical cavity 114 of the pump casing 11 is inserted in the stator soft iron 21, and the central columnar soft iron 23 is inserted into the central tube cavity 116 on the bottom plate of the pump casing 11, An 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 the central magnetic pole. The magnetic element at the position; the central magnetic pole structure closes the magnetic circuit of each stator pole (as shown in Figure 1).

The magnetic levitation device also includes a control device, the electromagnetic coil 22 is connected to the control device, and the control device includes an impeller positioning control device and an impeller rotation control device, the impeller positioning control device makes the magnetic levitation rotor impeller 12 suspend in the pump casing, and the impeller rotation control device makes The impeller 12 works, that is, rotates, and is also called a motor.

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 levitation rotor impeller in the pump casing; the impeller rotation control device interacts with the permanent magnet in the impeller 12 through the current change of the electromagnetic coil to make the impeller rotate and the speed adjust.

The permanent magnet inside the magnetic levitation rotor impeller has a magnetic pole arrangement that is in pairs with the stator soft iron.

The impeller positioning control device, that is, the magnetic levitation control device, includes an actuator, that is, an electromagnet or an electromagnetic coil, a position sensor, a controller, and a power amplifier. The position sensor is arranged in the outer circumferential direction of the magnetic levitation rotor impeller 12 to detect the rotor radial displacement and axial displacement. The position sensor can use a Hall type, eddy current type, inductive type and other displacement sensors, and the position sensor is connected with the controller to feed back the position of the impeller in real time.

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 When it 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, and the magnetic suspension control device is based on the position of the magnetic suspension rotor impeller 12 and the PID algorithm Carry out calculations, the response speed is set by the designer according to the needs, the calculation results drive the power amplifier, and generate current in the magnetic levitation control coil, that is, the electromagnetic coil, thereby generating a change in electromagnetic force and providing the magnetic levitation rotor impeller 12 to return to the center position The force finally makes the maglev rotor impeller stably suspended in the specified position under the disturbance of external force.

The specific principles are as follows:

Assuming that the currents on the two electromagnet windings in the electromagnetic coil are i1 and i2 respectively, the resultant force F of their attraction force on the magnetic levitation rotor impeller 12 and the gravity mg of the magnetic levitation rotor impeller 12 (which can be referred to as the rotor for short) are in balance, and the rotor is in Suspended equilibrium position. Assuming that in the equilibrium position, the rotor is subjected to a downward disturbance, 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. Compared with the initial balance 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 becomes larger, and the lower electromagnet The suction force of the electromagnet becomes smaller, so the resultant force of the upward magnetic force becomes larger, so that the rotor moves back to the original equilibrium position. If the rotor receives an upward disturbance and moves upward, the controller will reduce the output current of the power amplifier above, increase the current below, increase the resultant downward force of the electromagnet, and return the rotor to its original balance position. Therefore, no matter the rotor is disturbed upward or downward, the rotor can always be in a stable equilibrium state under the control of the controller.

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, and 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 provided in the magnetic levitation device 2 , corresponding to the permanent magnet 123 on the magnetic levitation rotor impeller 12 to drive the magnetic levitation rotor impeller 12 to rotate.

Commonly used magnetic suspension bearings can be divided into active suspension control and passive suspension control according to the magnetic force control method.

Passive levitation is generally realized by the permanent magnetic force between permanent magnets, which 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 levitation bearings cannot achieve stable levitation in all degrees of freedom, so At least one degree of freedom requires other suspension methods to form a five-degree-of-freedom full suspension system.

The active magnetic levitation system is to control the rotor displacement in real time through electromagnetic force to realize the active levitation of the rotor. It has the characteristics of adjustable stiffness, damping and other coefficients, and high control accuracy, but it needs to cooperate with the displacement detection system, controller and power of each degree of freedom. amplifier.

The control of the magnetic suspension bearing includes an active magnetic suspension system and a passive magnetic suspension system to realize the five-degree-of-freedom suspension of the impeller in the blood:

The first degree of freedom: the translational degree of freedom along the axis, which is passive suspension control;

The second and third degrees of freedom: the two translational degrees of freedom along the radial direction are active magnetic levitation control;

The fourth and fifth degrees of freedom: the two rotational degrees of freedom along the radial direction, that is, when the impeller is tilted, are passively controlled by the magnetic levitation system;

In addition, the rotation along the axial direction is actively controlled by the motor, that is, the permanent magnet in the impeller and the corresponding electromagnetic device. The function of the magnetic levitation control device is to control the magnetic levitation rotor impeller to realize the five-degree-of-freedom levitation in the blood, and the axial rotational degree of 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 realized by using the impeller positioning control device, which saves space and power consumption.

Another feature of this control device is that it improves the defect of insufficient stiffness of the magnetic levitation rotor impeller 12, that is, through the active adjustment of stiffness and bearing capacity, that is, the active magnetic levitation system can be changed by changing the current in the electromagnet or electromagnetic coil, that is, the magnetic bearing coil. , so as to realize the real-time adjustment of the support stiffness of the maglev rotor impeller 12, which is the advantage of this system. The rigidity of the mechanically supported rotor is determined by the design, and the rigidity cannot be adjusted after the machining is completed. Five degrees of freedom do not necessarily require five groups of electromagnetic coils, and a certain group can control multiple degrees of freedom.

The extracorporeal magnetic levitation centrifugal blood pump provided by the invention adopts the combination of active levitation and passive levitation, which is more compact and efficient. Among the three translational degrees of freedom of the magnetic levitation rotor impeller of the blood pump, one axial translational degree of freedom is passive. The two radial degrees of freedom are active, and 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.

When the magnetic levitation rotor impeller works normally, the magnetic levitation rotor impeller 12 is suspended in the set position in the pump casing 11, that is, it is placed in the center of the pump casing, that is, the rotation axis of the magnetic levitation rotor impeller 12 coincides with the axis of the pump casing 11, and the magnetic levitation rotor The gap between the upper edge of the blade 111 in the impeller 12 and the inner wall of the pump casing 11 is equal to the gap between the lower edge of the blade 111 and the inner wall of the pump casing 12, and the gap between the outer edge of each blade 111 and the pump casing is also equal; The center position of the shell. At this time, the gap between the base 122 of the magnetic levitation rotor impeller 12 and the cylindrical chamber 114 of the pump casing 11, and the gap between the pipe section 124 of the magnetic levitation rotor impeller 12 and the center column shell 115 are large gaps, that is, the gap is 1.0mm -1.5mm. Wherein, the gap between the outer edge of the blade 111 and the pump casing is preferably 1.0-2.0mm, and the gap between the upper and lower edges of the blade 111 and the pump casing is 1.0-1.5mm. Of course, the gap between the impeller and the pump casing can also be equal.

The thrombus problem of the blood pump in the prior art is solved by two methods of no mechanical contact and large gap in the present invention. If there is no mechanical contact, there will be no problem of long thrombus at the contact position. If the gap is large, it means that the blood flow in the gap of the runner is sufficient to form effective flushing and eliminate the formation of thrombus in the gap of the runner. The large gap is also a measure to improve the flow field in the pump. The large gap is to have sufficient blood flow in the gap of the flow channel, which can form effective flushing and eliminate thrombus formation in the gap of the flow channel. Scouring effect, easy to grow thrombus.

The invention adopts the magnetic levitation bearing structure with the central magnetic pole to replace the mechanical bearing support of the traditional centrifugal blood pump. The magnetic levitation rotor impeller is suspended in the blood without any mechanical contact with the pump casing, and the position and speed of the rotor impeller are precisely adjusted through the digital signal processor system. , the central magnetic pole structure can increase the support stiffness of the maglev rotor impeller, effectively suppress the vibration of the rotor impeller, reduce the risk of the maglev rotor impeller touching the pump casing during operation, and reduce the hemolysis caused by the vibration of the maglev rotor impeller. The secondary flow channel A in the pump head 1 is designed as a W-shaped flow channel with a large gap. The groove structure of the pump casing 11, that is, the central column casing 115, extends into the through hole of the magnetic levitation rotor impeller 12, that is, the pipe section 124. Excessive blood flow in the flow channel increases the blood flow passing through the blades in the main channel, which in turn makes the blade work more blood flow and improves the pump operation efficiency. At the same time, the large gap design of the secondary flow channel can keep the corresponding The blood flow is used to flush the secondary channel of the pump head, reducing the risk of thrombus formation. The extracorporeal magnetic levitation centrifugal blood pump of the present invention is composed of a pump head and a magnetic levitation device. The pump head includes a pump casing and a magnetic levitation rotor impeller. The impeller includes a permanent magnet. It consists of three structures. There is a through-hole structure in the middle of the magnetic levitation rotor impeller, and correspondingly, the pump casing has a groove structure extending into the through hole in the middle of the magnetic levitation rotor impeller, and correspondingly, the central magnetic pole of the magnetic levitation device extends into the groove structure of the pump casing. There is a large gap between the shell and the magnetic levitation rotor impeller, which can form effective scour through large flow. The permanent magnet is interference fit and sealed in the magnetic levitation rotor impeller, and the current passes through the stator coil to generate magnetic force, driving the impeller to rotate, and at the same time, the rotor is suspended in the blood in the pump casing. The central magnetic pole structure of the magnetic levitation device can close the magnetic circuit of each stator pole, independently control the change of magnetic flux of each magnetic pole, provide active control force through the electromagnetic coil, and realize stable control of the axial direction and tilt direction of the permanent magnet of the rotor , to ensure stability under dynamic load conditions.

Claims (10)

1. The utility model provides an external magnetic suspension centrifugal blood pump with central magnetic pole structure which characterized in that: comprises a pump head and a magnetic suspension device,

The pump head comprises a magnetic suspension rotor impeller and a pump shell, the magnetic suspension rotor impeller is positioned in the pump shell, a gap is formed between the magnetic suspension rotor impeller and the pump shell,

The pump shell comprises a volute, a central hole is formed in 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 arranged at the outer edge of the volute, a cylindrical chamber communicated with the volute is arranged at the lower part of the volute, the lower bottom plate of the cylindrical chamber is recessed inwards on the central axis, a central cylindrical shell is formed by protruding in the cylindrical chamber, and correspondingly, a central pipe cavity is formed by the lower bottom plate outside the pump shell;

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, the base is a cylindrical shell, the upper bottom surface of the base is closed, a central through hole is formed in the upper surface of the base, a pipe section is arranged on the central through hole in an extending mode towards the interior of the cylindrical shell, the cylindrical shell of the base is formed into an annular chamber through the pipe section, and the permanent magnets are fixedly arranged in the annular chamber; a plurality of blades are uniformly and 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 the magnetic suspension rotor impeller is suspended under the action of magnetic suspension force and is matched with the magnetic suspension device to form a magnetic bearing; gaps are arranged between the base of the magnetic suspension rotor impeller and the cylindrical cavity of the pump shell and between the pipe section and the central cylindrical shell, so that a section of W-shaped secondary flow channel is formed in the pump shell;

The magnetic suspension device is arranged below the pump shell and comprises a body which is a cylinder with a closed lower bottom, wherein a magnetic suspension element is arranged, the magnetic suspension element comprises stator soft iron and an electromagnetic coil, the stator soft iron is arranged in the cylinder, the stator soft iron is arranged on the inner wall of the body, the lower bottom plate of the cylinder is provided with a central column-shaped soft iron, is connected with stator soft iron arranged on the inner wall of the body into a whole, the cylindrical cavity of the pump shell is inserted in the middle of the stator soft iron in the cylinder on the body, the central columnar soft iron is inserted into the central tube cavity on the lower bottom plate of the pump shell, an electromagnetic coil is arranged on a stator arranged on the inner wall in the body, the central columnar soft iron forms a central magnetic pole, the magnetic suspension element and the permanent magnet in the magnetic suspension rotor impeller correspondingly form a motor and also form a magnetic element for adjusting the position of the magnetic suspension rotor impeller in the pump shell; the central magnetic pole structure enables the magnetic circuit of each stator magnetic pole to be closed;

The magnetic suspension device also comprises a control device, the control device comprises an impeller positioning control device and an impeller rotation control device,

In the impeller positioning control device, corresponding electromagnetic coils are connected with the impeller positioning control device so as to adjust the current of the electromagnetic coils and adjust the position of the magnetic suspension rotor impeller in the pump shell;

The impeller rotation control device enables the impeller to rotate and the rotating speed to be adjusted through the action of the current change of the corresponding electromagnetic coil and the permanent magnet in the impeller.

2. The extracorporeal magnetic levitation centrifugal blood pump with a central magnetic pole structure as claimed in claim 1, wherein: the magnetic suspension rotor impeller comprises four pairs of eight streamline blades, and the blade structure is alternatively designed as follows:

One is as follows: the eight blades are the same and are uniformly fixed on the upper surface of the base in the circumferential direction;

The second is that: two pairs of the eight blades are longer, the other two pairs of the eight blades are shorter, four longer blades and four shorter blades are uniformly fixed on the upper surface of the base at intervals, and the outer end edges of the eight blades are on a circumferential track; and/or the presence of a gas in the gas,

when the magnetic suspension rotor impeller works normally, the magnetic suspension rotor impeller is positioned at a set position, and at the moment, the gap between the base of the magnetic suspension rotor impeller and the cylindrical chamber of the pump shell and the gap between the pipe section of the magnetic suspension rotor impeller and the central cylindrical shell are 1.0mm-1.5 mm.

3. the extracorporeal magnetic levitation centrifugal blood pump with a central magnetic pole structure as claimed in claim 2, wherein: the curve of the blade has the following characteristics: fitting with smooth transition spline curve to obtain pump with impeller rotation speed of 1500-6000 rpm, flow rate of 1-10L/min, and pressure rise of 60-600 mmHg; and/or the presence of a gas in the gas,

The difference between the distance R1 from the inner end edge of the longer vane to the center of rotation of the magnetically levitated rotor wheel and the distance R2 from the inner end edge of the shorter vane to the center of rotation of the magnetically levitated rotor wheel is within a range of values: 2.0mm-5.0 mm.

4. the extracorporeal magnetic levitation centrifugal blood pump with a central magnetic pole structure as claimed in claim 1, wherein: the impeller positioning control device comprises a position sensor, a controller and a power amplifier, wherein the position sensor is arranged on the outer circumferential direction of the magnetic suspension rotor impeller and used for monitoring the radial displacement, the radial rotation and the axial displacement of the magnetic suspension rotor impeller.

5. The in vitro magnetic levitation centrifugal blood pump with a central magnetic pole structure as claimed in claim 4, wherein: the position sensor is connected with the controller to feed back the position of the magnetic suspension rotor impeller in real time, and the impeller positioning control device enables: when the magnetic suspension rotor impeller deviates from a set position or a central position in the pump shell, the control device performs operation according to the position of the magnetic suspension rotor impeller and a set algorithm, an operation result drives the power amplifier, current is generated in the magnetic suspension control electromagnetic coil of the impeller positioning control device, force for returning the magnetic suspension rotor impeller to the central position is provided, and finally the magnetic suspension rotor impeller is stably suspended under the disturbance of external force.

6. The extracorporeal magnetic levitation centrifugal blood pump with a central magnetic pole structure as claimed in claim 5, wherein: the algorithm is a PID.

7. the extracorporeal magnetic levitation centrifugal blood pump with a central magnetic pole structure as claimed in claim 1 or 4, wherein: the impeller positioning control device controls the magnetic suspension bearing to comprise an active magnetic suspension control system and a passive magnetic suspension control system, and realizes five-degree-of-freedom suspension control of the magnetic suspension rotor impeller in blood:

a first degree of freedom: the translational degree of freedom along the axial direction is controlled by passive magnetic suspension;

Second and third degrees of freedom: two translational degrees of freedom along the radial direction are actively controlled by an active magnetic suspension control system;

Fourth and fifth degrees of freedom: when two rotation degrees of freedom along the radial direction, namely the impeller of the magnetic suspension rotor, are inclined, the active magnetic suspension control system actively controls the two rotation degrees of freedom; and/or the presence of a gas in the gas,

The rotation along the axial direction is actively controlled by an impeller rotation control device or a motor, namely a permanent magnet in a magnetic suspension rotor impeller and a corresponding electromagnetic device.

8. the in vitro magnetic levitation centrifugal blood pump with a central magnetic pole structure as claimed in claim 4, wherein: the controller completes high-speed digital signal processing required by impeller positioning control and impeller rotation control through the processing of the ARM processor.

9. the extracorporeal magnetic levitation centrifugal blood pump with a central magnetic pole structure as claimed in claim 1 or 4, wherein: the permanent magnets in the magnetic suspension rotor impeller are provided with magnetic poles which are in dual connection with the stator soft iron.

10. The in vitro magnetic levitation centrifugal blood pump with a central magnetic pole structure as claimed in claim 4, wherein: the controller and the power amplifier in the control device, namely the magnetic suspension control device, are connected with the electromagnetic coil in the magnetic suspension device, so that: when the magnetic suspension rotor impeller deviates from a set position or the central position in a pump shell, the sensor sends a signal to the controller, the controller controls the current in the electromagnet through the power amplifier after processing, the magnetic suspension control device carries out operation according to the position of the magnetic suspension rotor impeller and an algorithm, an operation result drives the power amplifier, the current is generated in a magnetic suspension control coil, namely the electromagnetic coil, so that the change of the electromagnetic force is generated, the force for returning the magnetic suspension rotor impeller to the central position is provided, and finally the magnetic suspension rotor impeller is stably suspended at the specified position under the disturbance of an external force.