A micro-magnetic fluid suspension centrifugal blood pump

Abstract

The present invention relates to a micro-magnetic liquid suspension centrifugal blood pump, which is a device integrating a pump and a motor. The blood pump includes: a pump housing, a rotor, an impeller, a servo motor, an inner magnetic core group, an outer magnetic ring group, a limiting device and a suture retaining ring device; the rotor and the impeller are seamlessly connected into one body, the rotor is arranged in the inner tube of the blood pump, and the rotor is driven by the servo motor to drive the impeller to do work; the inner magnetic core group is arranged at the lower end inside the rotor, the outer magnetic ring group and the wrapping sleeve stand inside the lower shell of the pump chamber, and the combination of the inner and outer magnets can generate a radial magnetic suspension effect on the impeller; the ceramic piece and the ceramic cone form a limiting temporary bearing; the top of the impeller blade has an inclined surface, which can generate liquid suspension when the pump is working. According to the technical solution of the present invention, the rotor and the impeller can work stably in suspension, overcoming the friction effect of mechanical bearings; the internal structure of the pump is simple and smooth, which can greatly reduce hemolysis and thrombus complications; the blood pump is small in size and light in weight, with less surgical invasiveness, and can improve safety and practicability.

Description

Technical Field

[0001] The embodiments of this specification relate to the technical field of medical devices, and particularly to a micro magnetic liquid suspension centrifugal blood pump. Background Art

[0002] An artificial heart uses mechanical power to replace or assist the pumping work of a failing human heart, so it is also simply called a "blood pump", which provides a new treatment method for the treatment of patients with advanced heart failure. Currently, the blood pumps applied in the international market are mainly divided into two categories: centrifugal blood pumps and axial flow blood pumps. These two types of blood pumps can be further divided into bearing structures and suspension structures according to their internal structures. The blood pumps with bearing structures are usually called second-generation blood pumps, and their main disadvantages are: the bearings are easily worn, which severely restricts the service life of the blood pumps; the suspension structures are usually called third-generation blood pumps, including magnetic suspension or liquid suspension. Although this structure without bearings has a long service life, no frictional heat generation and local blood flow stagnation areas, and can better prevent thrombus formation, there are also new problems: one is that the magnetic suspension structure is complex, which requires adding detection, feedback and control systems, and will increase the volume of the blood pump, increasing the invasiveness of the operation. For example, the volume and weight of the third-generation magnetic suspension blood pump HeartMate III are more than three times that of the second-generation blood pump Jarvik2000; the other is that the internal fluid mechanical structure is complex, it is difficult to overcome the blood flow dead angle, and thrombus is easily formed in the dead angle.

[0003] Therefore, it can be seen that reducing the volume and weight of the suspension blood pump, simplifying the internal structure of the pump, and reducing complications such as hemolysis and thrombus are difficult problems that need to be solved by the blood pump. Summary of the Invention

[0004] The technical problem to be solved by the embodiments of this specification is to overcome the deficiencies of the prior art and provide a micro magnetic liquid suspension centrifugal blood pump with a small volume, light weight and simple structure.

[0005] To achieve the above objectives, the embodiments of this specification adopt the following technical solutions:

[0006] A micro magnetic liquid suspension centrifugal blood pump includes: a pump housing, a rotor, an impeller, a servo motor, an inner magnetic core group, an outer magnetic ring group, a limiting device and a suture ring device; the rotor and the impeller are seamlessly connected, the rotor is arranged in the inner tube of the blood pump, and the rotor is driven by the servo motor to drive the impeller to do work.

[0007] The inner magnetic core group is composed of multiple circular magnetic sheets and is built in the lower end of the rotor. The outer magnetic ring group includes multiple magnetic rings, which are arranged inside the lower end of the pump housing and surround the inner magnetic core group.

[0008] The limiting device includes a ceramic piece and a ceramic cone. The ceramic piece is embedded in the lower end of the rotor impeller, and the ceramic cone is arranged inside the lower end of the pump housing and is centered and directly opposite to the ceramic piece.

[0009] Optionally, the blood pump further includes a suture retaining ring device, which is outside the pump housing and is used to fix the blood pump and the cardiac apex.

[0010] Optionally, the inner magnetic core group is composed of three circular magnetic pieces, and the outer magnetic ring group is composed of three magnetic rings; or

[0011] the inner magnetic core group is composed of four circular magnetic pieces, and the outer magnetic ring group is composed of four magnetic rings; or

[0012] the inner magnetic core group is composed of five circular magnetic pieces, and the outer magnetic ring group is composed of five magnetic rings; or

[0013] the inner magnetic core group is composed of six circular magnetic pieces, and the outer magnetic ring group is composed of six magnetic rings.

[0014] Optionally, the inner magnetic core group and the outer magnetic ring group are both bonded together by the repulsive force of the same polarity of the strong magnetic neodymium iron boron material.

[0015] Optionally, the inclined surface at the middle part of the top of the impeller is a liquid suspension structure.

[0016] Optionally, the impeller is sheet-shaped and includes a plurality of blades, and the roots of the blades are connected to the rotor.

[0017] Optionally, the impeller includes 3 - 5 blades.

[0018] Optionally, the pump housing includes an inlet pipe, a pump chamber cover, and a lower pump chamber housing;

[0019] The inlet pipe includes an outer sleeve and an inner pipe;

[0020] The outer sleeve and the inner pipe are coaxial structures, and the inlet ends of the two are directly connected, and the other end is connected to the pump chamber cover;

[0021] The outer surface of the outer sleeve has a circle of sandblasted titanium powder coating;

[0022] The pump chamber cover is circular and is concentrically connected to the inner pipe, and the outer circle is connected to the lower pump chamber housing;

[0023] The inner bottom of the lower pump chamber housing has a circular convex platform, and there is a pump outlet on the side.

[0024] Optionally, the servo motor includes a rotor magnet, a stator iron core, and a stator winding;

[0025] The rotor permanent magnet is disposed inside the rotor, and the stator core and the stator winding are disposed on the inner wall of the inlet pipe, that is, built-in between the inner pipe and the outer sleeve;

[0026] The rotor permanent magnet is integrated with the rotor, and the stator core and the stator winding are integrated with the inlet pipe.

[0027] Optionally, the servo motor further includes a telecommunication transmission line. One end of the telecommunication transmission line is connected to the stator winding, and the other end extends outside the body and is connected to a control system.

[0028] Optionally, the suture retaining ring device includes a suture ring and a retaining ring mechanism. The retaining ring mechanism includes a hook ring and a base ring.

[0029] The above at least one technical solution adopted in the embodiments of the present specification can achieve the following beneficial effects:

[0030] The suspension in the embodiments of the present specification is passive permanent magnet suspension, which does not require complex detection, feedback, and control systems, has a relatively simple structure and stable performance, and can greatly improve the technical reliability and use safety of the blood pump; the blood pump has a smaller volume and weight, can reduce the surgical invasiveness of the blood pump, and improve the practicability; the internal structure of this fully suspended blood pump is simple and smooth, avoiding dead cavities or blind corners, and can also effectively prevent thrombus formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present specification or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present specification. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 It is a schematic cross-sectional view of the structure of the micro magnetic liquid suspension centrifugal blood pump provided by the embodiments of the present specification;

[0033] Figure 2 It is a cross-sectional view of the combination of the outer magnetic ring group and the inner magnetic core group provided by the embodiments of the present specification;

[0034] Figure 3 It is a three-dimensional structure schematic diagram of the magnetic ring sleeve provided by the embodiments of the present specification;

[0035] Figure 4 It is a three-dimensional schematic diagram of the force analysis of the rotor and the impeller provided by the embodiments of the present specification.

[0036] Description of the attached reference numerals: Rotor magnet - 1, Stator iron core - 2, Stator winding - 3, Outer magnetic ring group - 4, Spacer - 4.1, Inner magnetic core group - 5, Telecommunication transmission line - 6, Inner tube - 7, Outer sleeve - 8, Titanium powder coating - 9, Magnetic ring sleeve - 10, Sleeve foot - 10.1, Rotor - 11, Impeller - 12, Inclined surface - 13, Ceramic piece - 14, Ceramic cone - 15, Circular boss - 16, Wedge groove - 17, Lower pump housing - 18, Pump chamber cover - 19, Pump outlet - 20, Pump inlet - 21, Suture ring - 22, Soft magnetic sheet - 23, Washer - 24, Snap ring mechanism - 25, Hook ring - 25.1, Base ring 25.2, First backward axial force - F1, Second backward axial force - F2, Third backward axial force - F3, Forward axial force - F4. Detailed implementation manners

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this specification clearer, the technical solutions of the embodiments of this specification will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this specification, rather than all the embodiments. Based on the embodiments in this specification, all other implementation manners obtained by those of ordinary skill in the art without creative efforts fall within the scope protected by the embodiments of this specification.

[0038] The following further illustrates the specific implementation of the embodiments in conjunction with the drawings of the embodiments of this specification.

[0039] See Figures 1 to 4 , the embodiments of this specification provide a micro magnetic liquid suspension centrifugal blood pump, including: a pump device, a servo motor, a suspension limiting system, and a suture snap ring device.

[0040] The pump device includes a pump housing, a rotor 11, and an impeller 12.

[0041] The pump housing includes an inlet pipe, a pump chamber cover 19, and a lower pump housing 18.

[0042] The inlet pipe includes an inner tube 7 and an outer sleeve 8.

[0043] The inner tube 7 and the outer sleeve 8 are coaxially structured, with their inlet ends directly connected, and the other ends connected to the pump chamber cover 19. Seamless welding is performed at the connection points to prevent leakage.

[0044] The outer circumference of the outer sleeve 8 is roughened and has a circle of sandblasted titanium powder coating - 9, which can prompt the timely formation of a closed-loop inner membrane at the apex socket.

[0045] There is a cavity between the outer sleeve 8 and the stator iron core 2, which can play a role in heat resistance and temperature reduction, improving the safety of the blood pump and the motor.

[0046] The pump chamber cover 19 is in the shape of a ring, the central opening is connected concentrically with the inner tube 7, and the outer circle is connected with the pump chamber lower shell 18, and the connection needs to be welded to prevent leakage.

[0047] The inner bottom of the pump chamber lower shell 18 is provided with a round boss 16 and a pump outlet 20 on the side. After the internal parts are installed, the pump chamber cover 19 is buckled onto the pump chamber lower shell 18 and sealed and welded.

[0048] The rotor 11 and the impeller 12 are seamlessly connected to form a whole.

[0049] The rotor 11 is driven by a servo motor, driving the impeller 12 to do work, so as to cause blood to continuously flow in from the pump inlet 21 and flow out from the pump outlet 20 after centrifugation.

[0050] The impeller 12 is composed of four hollow blades, which are evenly distributed at the root of the rotor 11 and seamlessly connected thereto as a whole.

[0051] The servo motor mainly includes a rotor magnet 1 , a stator core 2 , a stator winding 3 and a telecommunication transmission line 6 .

[0052] The rotor magnet 1 is placed in the rotor 11; the stator core 2 and the stator winding 3 are sleeved on the outer wall of the inner tube 7, and the rotor magnet 1 is radially located at the center of the stator core 2 and the stator winding 3, while in the axial position, the rotor magnet 1 is offset forward.

[0053] The telecommunication transmission line 6 is used to transmit electric energy and electric signals, one end of which is connected to the stator winding 3, and the other end extends outside the body and is connected to the control system.

[0054] Since the servo motor and the pump device are integrated, a "pump-motor integration" is formed.

[0055] The suspension and limiting system comprises a magnetic suspension combination, a liquid suspension structure and a limiting device.

[0056] The magnetic suspension assembly comprises an inner magnetic core group 5 and an outer magnetic ring group 4, and the cooperation of the inner magnetic core group 5 and the outer magnetic ring group 4 can realize radial magnetic suspension of the rotor and the impeller.

[0057] The inner magnetic core group 5 is composed of three circular magnetic sheets stacked together coaxially and built into the lower end of the rotor; the outer magnetic ring group 4 is composed of three magnetic rings stacked together coaxially. The magnetic rings are not in direct contact with each other, and thin spacers 4.1 of the same size are adhered between them. The magnetic ring group 4 is wrapped in a magnetic ring sleeve 10. The magnetic ring sleeve 10 has a plurality of sleeve feet 10.1, and the sleeve feet 10.1 are embedded in the lower shell 18 of the pump chamber.

[0058] The magnetic directions of the circular magnetic sheets or magnetic rings of the inner magnetic core group 5 and the outer magnetic ring group 4 are axial, and they are forcibly glued together with the same poles facing each other.

[0059] Optionally, the inner magnetic core group 5 can be composed of four circular magnetic sheets, and the outer magnetic ring group 4 can be composed of four magnetic rings; or the inner magnetic core group 5 can be composed of five circular magnetic sheets, and the outer magnetic ring group 4 can be composed of five magnetic rings; or the inner magnetic core group 5 can be composed of six circular magnetic sheets, and the outer magnetic ring group 4 can be composed of six magnetic rings. When the inner magnetic core group 5 and the outer magnetic ring group 4 are installed, their positions are basically aligned in the center.

[0060] Preferably, the magnetic material of the inner magnetic core group 5 and the outer magnetic ring group 4 is strong magnetic neodymium iron boron.

[0061] A soft magnetic sheet 23 and a washer 24 are arranged between the rotor magnetic steel 1 and the inner magnetic core group 5, which can play a role in magnetic shielding and anti-interference, and can improve the magnetic suspension effect and the working efficiency of the blood pump. Among them, the soft magnetic sheet 23 is a magnetic conductive material such as silicon steel and iron, and the washer 24 is a non-magnetic conductive material.

[0062] The limiting device includes a ceramic sheet 14 and a ceramic cone 15. The ceramic sheet 14 is embedded in the lower end of the rotor impeller 12, and the ceramic cone 15 is embedded in the circular boss 16 of the lower shell of the pump chamber and is centered opposite to the ceramic sheet 14. When the blood pump is in a stationary or low-speed state, under the pressure of the rotor impeller, the ceramic cone 15 presses against the ceramic sheet 14, and can act as a group of temporary sliding bearings, which can well limit the impeller and support the start-up of the blood pump.

[0063] The liquid suspension structure is that the middle part of the top of the impeller 12 is inclined, that is, the middle of the top of the blade is inclined from the upstream side of the inlet to the downstream side. The inclined surface 13 forms a wedge-shaped space with the inner surface of the pump chamber cover 19, and the two sides of the inclined surface have edges flush with the top surface to prevent liquid from overflowing. When the blood pump is working, under the action of centrifugal force, liquid flows into the wedge-shaped groove 17, and hydraulic pressure is generated due to the extrusion, and the axial force pushes the impeller 12 away, so that it can never contact the pump chamber cover 19.

[0064] Optionally, the inclination angle of the inclined surface 13 is 1-10°.

[0065] The suture clamping ring device is located at the root of the outer sleeve 8 near the pump chamber cover 19, and includes a suture ring 22 and a clamping ring mechanism 25. It is used to connect the apex of the heart and the blood pump and fix the blood pump. During the operation, the base ring 25.2 is first sutured on the apex of the heart, and after drilling a hole, the pump inlet is inserted into the ventricle through the hole. When the hook ring 25.1 clicks and hooks the base ring 25.2, the blood pump is fixed.

[0066] The embodiment of the present specification provides a micro magnetic fluid suspension centrifugal blood pump. After starting smoothly, how the rotor impeller can achieve suspension operation needs to be analyzed. The suspension can be decomposed into radial suspension and axial suspension.

[0067] Radial suspension is mainly achieved by a combination of magnetic levitation. The inner magnetic core group 5 and the outer magnetic ring group 4 repel each other radially due to magnetic force, and the repulsive force is sufficient to overcome and balance various radial forces, so that the rotor impeller is always limited to the center of the inner tube 7 and the pump chamber. Coupled with the gyroscopic effect when the rotor impeller rotates, a good radial magnetic levitation effect can be obtained.

[0068] Axial suspension is liquid suspension. To understand how it is achieved, it is necessary to analyze the axial forces. When the blood pump is operating at high speed, it is affected by multiple axial forces, which can be divided into weak axial forces and strong axial forces. The weak axial forces mainly include the axial component of the gravity of the rotor impeller and the axial forces of other factors, which are weak influencing factors; the strong axial forces mainly include four axial forces, which can be analyzed as follows Figure 4 As shown. F4 is the forward axial force (pointing to the pump inlet), and F1, F2, and F3 are the three backward axial forces (away from the pump inlet). The generation of F1 is due to the fact that the motor iron core always has an automatic binding force on the motor magnet, keeping it axially centered. When the magnet moves axially forward relative to the iron core axis, it is subjected to a backward pulling force. When the magnet moves axially backward relative to the iron core axis, it is subjected to a forward pulling force. In this illustrative example, since the rotor magnet 1 moves forward, F1 is an axially backward force, which is relatively small and has no relation with the pump speed; F2 is the axial component of the impulse force generated by the liquid momentum on the impeller, and the magnitude of this force is positively correlated with the speed; F3 is the axial component of the pressure exerted by the liquid dynamic pressure on the inclined surface 13 of the impeller 12, and the magnitude of this force is positively correlated with the speed in a geometric progression but negatively correlated with the size of the wedge-shaped space; F4 is generated due to the pressure difference between the low hydraulic pressure on the inner surface of the pump chamber cover 19 and the suction inlet and the high hydraulic pressure on the lower cover surface during the operation of the pump. After the pump starts, this force increases rapidly as the pump speed increases. When the speed reaches a certain level and F4 is greater than the sum of F1, F2, and F3, F4 drives the rotor impeller and the ceramic piece 14 to separate from the ceramic cone 15 and move axially forward. As the wheel approaches the pump chamber cover 19, the wedge-shaped space becomes smaller, and the axial component of the liquid dynamic pressure F3 generated increases in a geometric progression. F3 will automatically counteract F4. When the resultant axial force is balanced, it forces the rotor impeller to stop axially moving, and F3 no longer increases. That is to say, within a certain speed range, the axial force on the rotor impeller can be automatically balanced, achieving automatic axial suspension.

[0069] As described above, by combining the radial magnetic levitation and axial liquid suspension of the rotor impeller, stable suspended operation can be achieved.

[0070] The technical effects that can be achieved by the embodiments of this specification are as follows:

[0071] Compared with the existing mechanical bearing blood pump, in the suspended state during normal operation of the blood pump in the embodiments of this specification, there is no friction in the bearing, which can reduce hemolysis, extend the life of the blood pump, and also reduce thrombus complications triggered by friction heating.

[0072] Compared with existing magnetic levitation blood pumps, the levitation in the embodiments of this specification is passive permanent magnet levitation, which does not require complex detection, feedback, and control systems. It has a relatively simple structure and stable performance, which can greatly improve the technical reliability and usage safety of the blood pump; the volume and weight of the blood pump are smaller, which can reduce the surgical invasiveness of the blood pump and improve its practicability; the internal structure of this fully levitated blood pump is simple and smooth, avoiding dead spaces or blind corners, and can also effectively prevent thrombus formation.

[0073] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0074] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A micro-magnetic liquid suspension centrifugal blood pump, characterized in that, it includes: a pump housing, a rotor, an impeller, a servo motor, an inner magnetic core group, an outer magnetic ring group, a limiting device and a suture retaining ring device; the rotor and the impeller are seamlessly connected, the rotor is arranged in the inner tube of the blood pump, and the rotor is driven by the servo motor to drive the impeller to do work; the inner magnetic core group is composed of multiple circular magnetic sheets and is built-in at the lower end inside the rotor, and the outer magnetic ring group includes multiple magnetic rings, which are arranged inside the lower end of the pump housing and surround the inner magnetic core group; the limiting device includes a ceramic sheet and a ceramic cone, the ceramic sheet is embedded inside the lower end of the rotor impeller, and the ceramic cone is arranged inside the lower end of the pump housing and is centered and facing the ceramic sheet; the magnetic suspension combination includes an inner magnetic core group and an outer magnetic ring group; the outer magnetic ring group is fixedly installed at the bottom of the lower shell of the pump chamber and coincides with the axis of the lower shell of the pump chamber; the impeller is sheet-shaped and includes multiple blades, the roots of the blades are connected to the rotor, and the blades are arranged on the outer side of the outer magnetic ring group in the radial direction.

2. The blood pump according to claim 1, characterized in that, the blood pump further includes: a suture retaining ring device, which is outside the pump housing and is used to fix the blood pump and the cardiac apex.

3. The blood pump according to claim 1, characterized in that, the inner magnetic core group is composed of three circular magnetic sheets, and the outer magnetic ring group is composed of three magnetic rings; or the inner magnetic core group is composed of four circular magnetic sheets, and the outer magnetic ring group is composed of four magnetic rings; or the inner magnetic core group is composed of five circular magnetic sheets, and the outer magnetic ring group is composed of five magnetic rings; or the inner magnetic core group is composed of six circular magnetic sheets, and the outer magnetic ring group is composed of six magnetic rings.

4. The blood pump according to claim 1, characterized in that, both the inner magnetic core group and the outer magnetic ring group are bonded together by the mutual repulsion of the same-sex strong magnetic neodymium iron boron materials.

5. The blood pump according to claim 1, characterized in that, the inclined surface at the middle part of the top of the impeller is a liquid suspension structure.

6. The blood pump according to claim 1, characterized in that, the impeller includes 3 - 5 blades.

7. The blood pump according to claim 1, characterized in that, the pump housing includes: an inlet pipe, a pump chamber cover and a lower pump chamber housing; the inlet pipe includes an outer sleeve and an inner pipe; the outer sleeve and the inner pipe are coaxial structures, the inlet ends of the two are directly connected, and the other end is connected to the pump chamber cover; the outer surface of the outer sleeve has a circle of sandblasted titanium powder coating; the pump chamber cover is circular and is concentrically connected to the inner pipe, and the outer circle is connected to the lower pump chamber housing; the inner bottom of the lower pump chamber housing has a circular convex platform, and there is a pump outlet on the side.

8. The blood pump according to claim 7, characterized in that, the servo motor includes a rotor magnet, a stator iron core and a stator winding; the rotor magnet is placed inside the rotor, and the stator iron core and the stator winding are placed on the inner wall of the inlet pipe, that is, built-in between the inner pipe and the outer sleeve; the rotor magnet is integrated with the rotor, and the stator iron core and the stator winding are integrated with the inlet pipe.

9. The blood pump according to claim 8, characterized in that, the servo motor further includes a telecommunication transmission line, one end of the telecommunication transmission line is connected to the stator winding, and the other end extends outside the body and is connected to a control system.

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