Disclosure of Invention
The invention aims to provide an implantable self-suspension axial flow blood pump which is smaller in volume and lighter in weight, does not stop rotating due to mechanical failure of a bearing, is higher in reliability and avoids thrombus from being formed at the position of the bearing.
In order to solve the technical problem, the embodiment of the invention discloses an implantable self-suspending axial blood pump, which comprises: a stator and a rotor, wherein the stator comprises: the stator comprises a stator iron core (2), a stator coil (3) and a motor support (4); the rotor includes: magnetic steel (5) containing magnetic material and a built-in paddle (8);
in the cross section of the blood pump, the blood pump sequentially comprises the following components from inside to outside along the radial direction: the built-in paddle (8), the magnetic steel (5), the motor support (4), the stator coil (3) and the stator iron core (2);
the stator and the rotor are not connected by a bearing.
Compared with the prior art, the implementation mode of the invention has the main differences and the effects that:
the rotor comprises hollow annular magnetic steel and a built-in paddle fixed in the hollow annular magnetic steel, the rotor is directly arranged in the middle of the stator, the stator and the rotor are not directly or indirectly connected through a bearing, and the rotor automatically breaks away from contact with the inner wall of the stator when rotating and is in a self-suspension state. Because no bearing or magnetic suspension control system is used, the blood pump is smaller in size and lighter in weight.
Furthermore, the invention can not stop rotating due to mechanical failure of the bearing, has higher reliability and avoids forming thrombus at the position of the bearing. Because a complex magnetic suspension control system is not needed, the blood pump has lower cost and better reliability.
Furthermore, the stator coil (3) adopts a hollow cup winding, so that the problem of difficult coil inserting of a small-sized stator is solved, a stator core does not have a tooth slot any more, and the essential rotation fluctuation caused by a tooth harmonic magnetic field is completely eliminated.
Furthermore, the structure that the internal paddle (8) is arranged in front of the main runner and the external paddle (9) is arranged behind the main runner is adopted, so that the blood is enabled to be acted by the rotating blades of the internal paddle (8) firstly when entering the runner, most of the blood is enabled to pass through the main runner, and trace blood passes through the main runner under the action of the blade tip part of the external paddle (9) arranged behind the main runner, and therefore the blood can be enabled to be smoothly branched and smoothly pass through the main runner and the branch runner without generating a congestion thrombus phenomenon.
Furthermore, the blade section of the built-in blade (8) and the blade section of the external blade (9) adopt the section form of an airfoil-shaped blade of a marine ducted propeller, when blood flows through the airfoil-shaped blade section, positive pressure appears on the blade surface of the blade section, negative pressure appears on the blade back of the blade section, and the pressure difference between the blade surface and the blade back can improve the blood pump efficiency and increase the pressure head.
Furthermore, a two-phase conduction and three-phase six-state conduction mode is adopted, so that the utilization rate of the winding is improved, the volume and the weight are reduced, the magnetic state angle is reduced, and the rotation fluctuation is reduced.
Furthermore, the outlet right-handed stator (7) is fixed with the motor support (4) together to play a role in adjusting the outflow direction of blood flow.
Furthermore, the functions of identifying the position of the rotor and self-starting are realized by adopting a circuit, the function of a position sensor is realized, and the conventional position sensor can be cancelled, so that the sealing difficulty is reduced, the reliability is improved, the structure is simplified, and the volume is reduced.
Furthermore, the clearance range of the cylindrical hollow inner wall is between 0.003D and 0.019D, preferably between 0.0042D and 0.0048D, and D is the inner diameter of the cross section of the magnetic steel (5), so that the optimal effect on reducing vibration is achieved, wherein the effective value of vibration acceleration is reduced by 1-2 m/s2, the effective value of vibration speed is reduced by 3-5 mm/s, and the effective value of vibration displacement is reduced by 13-33 microns.
Furthermore, the thickness range of the magnetic steel (5) is between 1.5mm and 3.5mm, preferably between 2.0mm and 3.0mm, more preferably between 2.3mm and 2.8mm, the rotating speed can be improved by about 2000 r/min, and the current can be reduced.
Detailed Description
In the following description, numerous technical details are set forth in order to provide a better understanding of the present application. However, it will be understood by those skilled in the art that the technical solutions claimed in the present application can be implemented without these technical details and with various changes and modifications based on the following embodiments.
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
A first embodiment of the invention relates to an implantable self-suspending axial blood pump. The implanted self-suspending axial flow blood pump comprises: a stator and a rotor, wherein the stator comprises: the stator comprises a stator iron core (2), a stator coil (3) and a motor support (4); the rotor includes: magnetic steel (5) containing magnetic material and a built-in paddle (8);
in the cross section of the blood pump, the blood pump sequentially comprises the following components from inside to outside along the radial direction: the motor comprises a built-in paddle (8), magnetic steel (5), a motor support (4), a stator coil (3) and a stator core (2).
The stator and the rotor are not connected by a bearing.
The inner envelope curve of the cross section of the motor bracket (4) is circular; an axial central hole is formed in the magnetic steel (5), and an outer envelope line of the cross section of the magnetic steel (5) is circular;
the stator and the rotor are not directly or indirectly connected through a bearing; wherein the indirect connection comprises magnetic levitation or the like.
When the blood pump runs normally, the range of the gap between the motor bracket (4) and the magnetic steel (5) is between 0.003D and 0.019D, and D is the inner diameter of the cross section of the magnetic steel (5).
Furthermore, preferably, when the blood pump runs normally, the clearance between the motor bracket (4) and the magnetic steel (5) ranges from 0.0042D to 0.0048D, and D is the inner diameter of the cross section of the magnetic steel (5).
The outer diameter, inner diameter and length range (mm) of the stator core can be properly adjusted according to the design scheme of the invention. Preferably, the outer diameter, inner diameter, and length range (mm) (phi14.5-37.7) × (phi11.4-29.6) × (11.5-30.0) of the stator core; outer diameter, inner diameter, and length range (mm) of stator coil: (phi11.4-29.6) × (phi10.3-26.6) × (12.5-32.5) more preferably can be the outer diameter, inner diameter and length range (mm) of the stator core: (. phi.20.3-37.7) × (. phi.15.9-29.6) × (16.1-30.0), and the outer diameter, inner diameter and length ranges (mm) of the stator coil may be (. phi.9-29.6) × (. phi.14.3-26.6) × (17.5-32.5).
Fig. 1 is a schematic diagram (in cross-section) of a preferred implantable self-suspending axial flow blood pump.
Specifically, as shown in fig. 1, the implantable self-suspending axial blood pump comprises: a stator and a rotor, wherein the stator comprises: stator core (2), stator coil (3) and motor support (4). The rotor includes: the inner side wall containing magnetic materials is cylindrical magnetic ring magnetic steel (5) and a built-in blade (8).
In addition, specifically, the magnetic steel (5) containing a magnetic material may contain other materials as long as a permanent magnet is contained therein.
In the present embodiment, preferably, the stator and the rotor are not directly or indirectly connected by a bearing. Wherein the indirect connection comprises magnetic levitation and the like.
The bearing in the embodiments of the present invention includes a directly connected bearing, and also includes a bearing which is not directly connected, such as a magnetic suspension bearing.
The stator coil (3) is located inside the stator core (2). The stator coil (3) is used for generating an alternating magnetic field for driving the magnetic steel (5) to rotate after being electrified.
The stator is a hollow cylindrical structure, and due to the existence of the stator, the magnetic steel (5) made of the permanent magnetic material can be firmly attracted to the middle part of the stator under the action of magnetic force, so that the rotor cannot be separated from the middle part of the stator due to the reaction force generated during rotation.
The stator coil (3) adopts a hollow cup winding.
The motor support (4) is fixed on the inner wall of the stator, the motor support (4) is provided with a hollow inner wall, and the rotor is arranged in the hollow inner wall.
The inner envelope curve of the cross section of the motor bracket (4) is circular; an axial central hole is arranged in the magnetic steel (5), and the outer envelope line of the cross section of the magnetic steel (5) is circular.
Specifically, the hollow inner wall of the motor support (4) can be regular cylindrical, irregular cylindrical or conical and the like, as long as the inner envelope of the cross section of the motor support (4) is circular.
Similarly, the outer wall of the magnetic steel (5) can be in a regular cylindrical shape, an irregular cylindrical shape or a conical shape, and the like, as long as the outer envelope line of the cross section of the magnetic steel (5) is circular.
When the blood pump runs normally, the range of the gap between the motor bracket (4) and the magnetic steel (5) is between 0.003D and 0.019D, and D is the inner diameter of the cross section of the magnetic steel (5).
Furthermore, preferably, the gap between the motor bracket (4) and the magnetic steel (5) ranges from 0.0042D to 0.0048D, D is the inner diameter of the cross section of the magnetic steel (5), wherein the effective value of the vibration acceleration is reduced by 1-2 m/s2, the effective value of the vibration speed is reduced by 3-5 mm/s, and the effective value of the vibration displacement is reduced by 13-33 micrometers.
The thickness range of the magnetic steel (5) is between 1.5mm and 3.5mm, preferably between 2.0mm and 3.0mm, more preferably between 2.3mm and 2.8mm, more preferably the thickness is 2.8mm, the rotating speed can be improved by about 2000 r/min, and the current can be reduced by 0.1A.
The stator coil (3) adopts the hollow cup winding, so that the problem of difficult coil inserting of the small-sized stator is solved, a stator core does not have a tooth socket any more, and the essential rotation fluctuation caused by a tooth harmonic magnetic field is thoroughly eliminated.
Furthermore, it is understood that in certain other embodiments of the present invention, the stator coil (3) may be in other coil forms instead of a coreless winding.
The stator adopts a two-phase conduction and three-phase six-state conduction mode.
The adoption of two-phase conduction and three-phase six-state conduction mode not only improves the utilization rate of the winding, reduces the volume and weight, but also reduces the magnetic state angle and reduces the rotation fluctuation.
Furthermore, it is to be understood that in certain other embodiments of the present invention, the stator may also adopt other conduction modes, not limited to only two-phase conduction and three-phase six-state conduction modes.
And a motor shell (1) is fixed outside the stator.
In addition, the method further comprises the following steps: the outlet right-handed stator (7) is arranged at the blood flow outlet end of the implanted self-suspension axial flow blood pump, and the outlet right-handed stator (7) is fixed with the motor bracket (4) together to play a role in adjusting the blood outflow direction and further reduce the rotation fluctuation.
The central axis of the magnetic steel (5) is parallel to the central axis of the stator coil (3).
Preferably, the magnetic steel (5) is a cylindrical magnetic ring which is made of rubidium, iron and boron permanent magnetic materials, is magnetized in the radial direction and has a pair of poles.
The magnet steel (5) adopts a rubidium iron boron permanent magnet material with high remanence induction strength, radial magnetization and a pair of polar cylindrical magnet ring column steel are adopted, a stronger air gap magnetic field can be still generated under the large electromagnetic air gap of the hollow cup winding, so that the volume and the weight of the motor are reduced, the uniformity of the quality is guaranteed due to the fact that the pair of polar whole cylindrical magnet steel is easier, the dynamic unbalance under high-speed motion is reduced, and the operation is stable because single-side magnetic tension does not exist, and the use comfort is improved.
Furthermore, no position sensor is included in the blood pump to determine the relative position between the stator and the rotor.
An axial central hole is formed in the magnetic steel (5), the built-in paddle (8) is arranged in the central hole, and the blade tip of the built-in paddle (8) is tightly contacted with the inner wall of the central hole or fixed into a whole.
A main flow channel for blood flow is formed between the inner holes of the magnetic steel (5).
The main runner in the inner hole of the magnetic steel (5) is free of any other obstacles, so that the runner is smooth and large blood flow is allowed to pass smoothly.
In addition, the method further comprises the following steps: a propeller shaft (10), and/or an outboard propeller blade (9).
The external paddle (9) is larger than the internal paddle (8), the external paddle (9) is close to one end of a blood flow outlet of the implantable self-suspension axial-flow blood pump, is arranged outside a central hole of the magnetic steel (5), and forms a paddle-shaft integrated tandem paddle (6) with the internal paddle (8), and preferably, the external paddle (9) and the internal paddle (8) are integrally connected in series on a paddle shaft (10). Alternatively, the two may be directly connected without using a paddle shaft, as shown in fig. 7.
In the embodiment, the rotor is preferably designed into a tandem paddle form, and a tandem structure with an internal paddle (8) at the front and an external paddle (9) at the rear is adopted.
In view of the fact that a flow channel in the blood pump is long and narrow, the diameter of blades of a rotor is limited, and the flow channel is divided into a main flow channel and a branch flow channel, the embodiment adopts a tandem propeller concept in a special propeller of a marine propeller, and the rotor of the blood pump is designed into a tandem paddle form. The tandem blades are characterized in that blades with different sizes are arranged on the same shaft and rotate at the same rotating speed, and the tandem blade form is particularly suitable for the situations that an implantable blood pump flow passage is long and narrow and the diameter of a rotor is limited.
Of course, this is only one preferred embodiment of the invention, and in some other embodiments of the invention, the rotor may not be a tandem blade, but may be other types of blades, such as a continuous blade, an inboard blade and an outboard blade may be connected to each other, without a shaft, and so on.
The blade section of the internal blade (8) and the external blade (9) adopts the section form of an airfoil-shaped blade of a marine ducted propeller.
The blade section of the internal blade (8) and the external blade (9) adopts the section form of an airfoil-shaped blade of a marine ducted propeller, when blood flows through the airfoil-shaped blade section, positive pressure appears on the blade surface of the blade section, negative pressure appears on the blade back of the blade section, and the pressure difference between the blade surface and the blade back can improve the efficiency of the blood pump and increase the pressure head.
Furthermore, it is understood that in certain other embodiments of the invention, the blade sections of the inboard blades (8) and the outboard blades (9) may also take other forms than the airfoil-shaped blade section of a marine ducted propeller, for example, the flat blade section of a typical pump.
In the present embodiment, the pump body rotor adopts a wing type blade section and large and small tandem rotors, especially large and small tandem rotor blades. The data shows that under the conditions of rotating speed of 7500-8000 rpm and pressure of 90-100 mmHg, the pumping flow of the large and small rotor blades is about 2 liters/minute larger than that of a single small rotor blade. Fig. 2 is a schematic structural view of the propeller-shaft integrated tandem blade.
Fig. 3 is a schematic view of the blade section and the force applied to the blade.
A main flow passage (11) and a main flow passage (12) for blood to flow are formed between the paddle shaft integrated tandem paddle (6) and the inner wall of the motor bracket (4) and the inner hole of the magnetic steel (5); branch flow channels (13) and (14) for blood flow are formed between the outer wall of the magnetic steel (5) and the inner wall of the motor bracket (4).
In the main flow channel, no other obstacles exist, so that the flow channel is unobstructed, and large-flow blood is allowed to smoothly pass through.
No obstacles are arranged in the branch flow channels (13) and (14) to prevent blood from flowing through, and because the gaps of the branch flow channels are small, the air gaps of the stator coils (3) and the magnetic steel (5) are also small, thereby obviously reducing the volume and the weight of the blood pump.
Adopt built-in paddle (8) in the front, structure behind external paddle (9), can guarantee that blood gets into the runner from blood flow import (15), receive built-in tandem paddle (8) rotating vane's effect earlier, guarantee that most blood passes through from the mainstream canal, and trace blood is then through with the help of the leaf tip part effect that sets up external paddle (9) at the back, can guarantee like this that blood is in main, branch runner branching smoothly, smooth passing through, do not produce the thrombus phenomenon of congestion.
Considering that the implantable self-suspension axial flow blood pump is used for an implantable ventricular assist device and has high requirements on the sealing performance of the structure, if a conventional brushless direct current motor position sensor is adopted, the functions of identifying the position of a rotor and self-starting are realized by adopting a circuit, the function of the position sensor is realized, and the position sensor which is necessary for the conventional brushless direct current motor can be cancelled, so that the sealing difficulty is reduced, the reliability is improved, the structure is simplified, and the volume is reduced.
The rotor comprises hollow cylindrical magnetic steel and a built-in paddle fixed in the hollow cylindrical magnetic steel, the rotor is directly arranged in the middle of the stator, the stator and the rotor are not directly or indirectly connected through a bearing, and the rotor automatically breaks away from contact with the inner wall of the stator when rotating and is in a self-suspension state. Because no bearing or magnetic suspension control is used, the blood pump has smaller volume and lighter weight, does not stop rotating due to mechanical failure of the bearing, has higher reliability and avoids forming thrombus at the position of the bearing.
Fig. 4 is a schematic radial cross-sectional view of the stator and rotor structure.
After stator coil (3) circular telegram, the air gap production rotating magnetic field that produces between the inner wall of stator coil (3) and the outer wall of magnet steel (5) drives magnet steel (5) rotatory, because the effect of magnet steel rotation centrifugal force, the magnet steel breaks away from the initial condition with the stator coil contact in the twinkling of an eye to the inner wall of motor support (4) is confined, and the medium is incompressible fluid, the magnet steel reaches the suspension rotation state coaxial with the stator coil very fast, and drive and rotate together with magnet steel even oar axle integration tandem paddle (6) of an organic whole, blood just inhales from blood flow import (15) of the pump body, flow from the export.
FIG. 5 is a schematic structural diagram (sectional view) of an initial state of the implantable self-suspending axial blood pump; fig. 6 is a schematic structural diagram (cross-sectional view) of the implanted self-suspending axial blood pump in a suspended state, wherein 20 denotes the outer diameter of the magnetic steel, and 21 denotes the inner diameter of the motor support.
The implanted self-suspension axial flow blood pump has the advantages of simple structure, small volume, light weight, smooth flow, no congestion thrombus phenomenon, no bearing friction, balanced operation, comfortable use, high blood pump efficiency and good hemolysis and thrombus prevention performance, and is completely suitable for being used as an implanted ventricle auxiliary device. Based on the above principle, the inventor has developed a prototype of a bearingless implantable self-suspended axial blood pump in 11/17/2011. The prototype has been successfully rotated for four months and is still operating normally and stably at present. The sample machine can be started and stopped in all directions, and can normally run under the impact of certain external force (impact, shaking and the like). Meanwhile, from 11/17/2011 to the present, the inventor carries out fatigue tests on the implanted self-suspended axial blood pump, and carries out real-time recording by a computer, wherein a prototype can also normally run under the conditions of intermittent starting and stopping.
The following table is a table of experimental test data for this prototype operating to date from 11/17/2011.
Date
|
Rotational speed RPM
|
Pressure MMHG
|
Current A
|
Flow rate L/MIN
|
2011.12.07
|
7610
|
99.10
|
0.55
|
4.85
|
2011.12.12
|
7599
|
98.70
|
0.55
|
4.90
|
2011.12.17
|
7623
|
99.80
|
0.55
|
4.81
|
2011.12.22
|
7630
|
99.81
|
0.55
|
4.50
|
2012.01.09
|
7684
|
99.15
|
0.55
|
4.80
|
2012.01.14
|
7600
|
98.70
|
0.55
|
4.80
|
2012.01.19
|
7557
|
94.29
|
0.51
|
4.40
|
2012.01.24
|
7704
|
97.62
|
0.55
|
4.85
|
2012.01.29
|
7550
|
94.02
|
0.51
|
4.40
|
2012.02.05
|
7488
|
94.01
|
0.51
|
4.80
|
2012.02.10
|
7408
|
93.80
|
0.51
|
4.80
|
2012.02.15
|
7501
|
95.00
|
0.52
|
4.81 |
The self-suspension axial flow blood pump body is optimized, the structure is compact, the number of main channel nodes is small, and the axial sealing performance is good. The pump body can be significantly shortened. The outer diameter, the inner diameter and the length range (mm) of the motor iron core can be properly adjusted according to the design scheme of the invention. Preferably, the outer diameter, inner diameter and length ranges of the stator core may be (mm): (. phi.20.3-37.7) × (. phi.15.9-29.6) × (16.1-30.0), and the outer diameter, inner diameter, and length of the motor coil may be (. phi.15.9-29.6) × (. phi.14.3-26.6) × (17.5-32.5).
Moreover, the inventor tests the implanted self-suspended axial blood pump under different pressures to obtain the following data:
as can be seen from the test data:
1) the power consumption of the blood pump is changed from 14-20 w under the normal working condition, and the corresponding pump temperature is kept below 38 ℃.
2) The rotating speed range is 4000 rpm-8000 rpm, and the corresponding flow rate is 2-6L/min under the same pressure (100 mmHg). The rotating speed is 8000rpm, and the corresponding flow is about 6L/min. The rotation speed can be further increased, and the relevant indexes such as corresponding flow rate and the like are also increased.
3) Working durability: in a fatigue test, the axial flow self-suspension pump can continuously rotate for more than zero four months in a year.
While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.