JP4251732B2 - Blood pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a blood pump that pumps blood in place of or in addition to a living heart, and more particularly to a pump that delivers blood in a steady flow.
[0002]
[Prior art]
A blood pump that pumps blood is used for the purpose of compensating for the deterioration of the function of the heart of a living body. Compared with pumps that handle other fluids, there are problems of hemolysis and thrombus, which are particularly problematic in blood pumps. Hemolysis is a phenomenon in which the cell membrane of erythrocytes is destroyed and internal hemoglobin flows out. A thrombus is a mass of blood components aggregated (coagulated) in the bloodstream. When a thrombus is formed and grows and peels off, it flows into the blood vessel, and there is a problem that the blood flow may be hindered by a capillary blood vessel or the like.
[0003]
There are two types of blood pumps, one that forms a pulsatile flow and the other that forms a steady flow. As a pump that forms a pulsating flow, a sac type or tube type pump is used because there are few places where blood stays.
[0004]
Pumps that form a steady flow include positive displacement pumps such as gear pumps and vane pumps, and turbo pumps such as centrifugal pumps, diagonal flow pumps, and axial flow pumps. The former has a problem that blood tends to stay in many parts and has a problem that blood clots are likely to occur, and is not usually used as a blood pump. On the other hand, the latter turbo pump does not require a valve, has a low possibility of thrombus generation, and has a relatively large discharge amount, and thus can be miniaturized. Because of these characteristics, turbo pumps, particularly centrifugal pumps, are attracting attention as blood pumps that can be implanted in a living body for a long period of time.
[0005]
[Problems to be solved by the invention]
However, when a centrifugal pump is used continuously for a longer period, problems such as blood clots and blood clots have not necessarily been solved. On the rear surface of the impeller, particularly the central portion thereof, a slow blood flow portion is formed, which may cause thrombus.
[0006]
The present invention has been made in consideration of the above-described problems, and an object thereof is to provide a blood pump that can suppress the occurrence of thrombus.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, a blood pump according to the present invention has an impeller that discharges blood sucked from both suction portions provided on both front and back surfaces from an outer peripheral portion, and a casing that houses the impeller. The casing has a magnetic pole and a coil for generating a rotating magnetic field, a permanent magnet is disposed on the impeller, the casing functions as a stator of the electric motor, the impeller functions as a rotor of the electric motor, The center of rotation is supported by point contact by a support point provided on the casing.
[0008]
Further, the permanent magnet may be disposed near the outer periphery of the impeller, and the magnetic pole may be disposed at a position facing the permanent magnet in the radial direction of the impeller.
[0009]
Further, at least one of the magnetic poles may be provided with a liquid introduction path through which blood discharged from the impeller flows.
[0010]
In addition, a liquid guide path through which blood discharged from the impeller flows may be disposed at a position shifted in the pump axis direction with respect to the magnetic pole.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings. 1 to 4 show an example of a blood pump to which the present invention is applied. FIG. 1 is a sectional view mainly broken along a plane orthogonal to the pump axis, FIG. 2 is a developed sectional view mainly broken along a plane including the pump axis, FIG. 3 is a front view, and FIG. 4 is a side view. More specifically, FIG. 1 shows the impeller 12 of the blood flow pump 10 with a portion of the shroud 14 omitted, and the casing 16 shows the axial center point of the impeller 12. The cross section in the axis orthogonal plane which passes is shown. Further, in FIG. 2, the fracture surface changes for each part. The impeller has a fractured surface passing through the center of the blade. The casing has a fracture surface in which the left half of the center line passes through the center of the magnetic pole, and the right half has a fracture surface in the plane along the flow line of blood flow. Specifically, the left side of the center line is a cross-sectional development view substantially along the OCBA plane shown in FIG. 1, and the right side is a cross-sectional development view substantially along the OH plane or ODEF plane. Accordingly, the scale is changed depending on the portion.
[0012]
The impeller 12 is a double suction type as shown in the figure, and a suction port 18 is provided at substantially the center of each of the front side surface (hereinafter referred to as the front surface) and the back side surface (hereinafter referred to as the back surface). Have. In the following description, when particularly distinguishing these, the upper suction port in FIG. 2 is referred to as a front surface suction port 18a, and the lower side is referred to as a back surface suction port 18b. Similarly, the same member exists on both the front and back sides, and when these are distinguished, they are distinguished by subscripts a and b. The boss 20 of the impeller 12 has a disk shape with a thick central portion, and blades 22 are provided on both the front and back sides. The front and back surfaces of the blades 22 are reduced in dimension in the axial direction toward the outer side in the radial direction, and are integrated in the vicinity of the outer peripheral portion. Upward in FIG surface vanes 22a, the downward in FIG backside blade 22b, respectively substantially annular plate-like surface shroud 14a, back surface shroud 14b is disposed. The openings of the inner portions of the circular rings of these shrouds 14a and 14b serve as the suction ports 18a and 18b. Four permanent magnets 24 are arranged on the shroud 14 at equal intervals in the circumferential direction. Moreover, the polarities on the outer peripheral side of the adjacent magnets 24 are different polarities. On both front and back surfaces of the center of the impeller 12, support holes 26 that are slightly recessed from the periphery are provided.
[0013]
A support pivot 28 protrudes from the casing 16 at a position facing the support hole 26 of the impeller, and the tip of the support pivots substantially contacts the support hole 26 to support the impeller 12. The casing 16 has a suction pipe 30, and the suction pipe 30 branches in the middle, one extending toward the front surface suction port 18 a of the impeller and the other toward the back surface suction port 18 b. Six liquid guide paths 32 are provided outside the casing 16 in the radial direction of the impeller. The liquid guide path 32 is disposed obliquely with respect to the radial direction along the direction of blood flow discharged from the impeller 12, and is further bent in the axial direction to be disposed at a position slightly offset in the axial direction. It extends toward the part discharge pipe 34. The end of the peripheral discharge pipe 34 is connected to the discharge pipe 36. The discharge pipe 36 is arranged in the vicinity of the suction pipe 30 so as to face substantially the same direction.
[0014]
Six magnetic poles 38 are arranged outside the casing 16 in the radial direction of the impeller, and constitute a stator of the electric motor. The stator core has an annular portion and teeth 40 projecting inward from the annular portion, and is formed by laminating electromagnetic steel plates having the same shape as the cross-sectional shape in the direction perpendicular to the axis. The teeth 40 are arranged with a slight inclination with respect to the radial direction, and the inclination prevents the interference with the liquid introduction path 32 described above. The tip of the tooth 40 slightly protrudes at a position facing the permanent magnets 24 arranged on the front and back of the impeller 12, and the portion between them is a flow path that guides the blood discharged from the impeller 12 to the liquid guide path 32. ing.
[0015]
A coil 42 is formed by winding a conductive wire around the tooth 40. The teeth 40 and the coil 42 are embedded in the casing so as not to come into direct contact with blood.
[0016]
When three-phase AC power is supplied to the coil 42, a rotating magnetic field is formed and the impeller 12 rotates. Thus, blood pump 10 operates like an electric motor having casing 16 as a stator and impeller 12 as a rotor. Therefore, unlike a normal pump, there is no shaft for driving the impeller 12 from the outside, and no shaft seal is necessary. The seal portion of the shaft is a portion where blood tends to stay and blood clots are easily generated, but the blood pump 10 does not have such a portion.
[0017]
When the impeller 12 rotates, blood flows from the suction pipe 30 to the suction port 18, and is sent out radially outward along the blades 22. The blood discharged from the impeller 12 is sent to the peripheral discharge pipe 34 through the liquid introduction path 32 and further to the discharge pipe 36.
[0018]
As described above, since the blood pump 10 is of the double suction type, there is no impeller rear surface in which blood tends to stay, and clotting on the rear surface of the impeller, which has been a problem in the past, can be suppressed. Further, the impeller 12, since the front and back symmetrical shape, the thrust force is not generated, less load bearing part consists of supporting holes 26 and the support pivot 28, improved durability of the bearing Yes. Furthermore, since the tip of the suction pipe 30 and the tip of the discharge pipe 36 are arranged in substantially the same direction, the arrangement in the living body is easy.
[0019]
Further, by arranging a stator on the outer peripheral side of the impeller as in the blood pump 10, when the impeller 12 is about to be displaced in the axial direction, a restoring force can be applied to return the impeller 12 to its original position. . This can also reduce the load on the bearing portion and improve the durability of the bearing.
[0020]
Furthermore, a means for detecting the radial displacement of the impeller 12 and a means for applying a restoring force to the impeller 12 based on the detected displacement can be provided. The means for detecting the displacement includes a metal ring provided in the vicinity of the outer periphery of the impeller 12 and a displacement sensor disposed in the casing so as to face the metal ring in the radial direction of the impeller. As the displacement sensor, an eddy current type or electrostatic capacity type gap sensor can be used, and the distance between the impeller 12 and the metal ring that changes in accordance with the radial movement of the impeller 12 is detected. The means for applying the restoring force includes a control coil that is arranged at the same position as the drive coil. Electric power corresponding to the displacement in the radial direction of the impeller 12 is supplied to the control coil, and a restoring force by magnetic force is applied. According to this, the load of the bearing part of an impeller can be reduced. Furthermore, the impeller 12 can be lifted during the pump operation. The phase relationship between the permanent magnet and the magnetic pole built in the impeller can be calculated based on the counter electromotive force generated in the coil. It is also possible to use a resolver. Furthermore, a Hall element can be provided at a position facing the permanent magnet to obtain the phase.
[0021]
As described above the support, by magnetic force control, in the case of generating a force to restore to the impeller neutral position, the front surface side, an increasing spacing support pivot 28 of the back surface side, the impeller 12 slightly loose It is also possible to do so. It is possible to further suppress the retention of blood between the support pivot 28 and the support hole 26.
[0022]
5 and 6 show a blood pump 110 according to another embodiment. The same components as those of the blood pump 10 shown in FIG. 1 and the like are denoted by the same reference numerals, the description thereof is omitted, and the corresponding components are denoted by reference numerals added with 100. FIG. 5 shows a state in which the shroud 14a is partially removed with respect to the impeller 12, and with respect to the casing 116, the upper half is an axial orthogonal section passing through the plane of symmetry of the impeller 12, and the lower half is a flow line of blood flow. It is a sectional view along.
[0023]
The impeller 12 is exactly the same as that shown in FIG. One of the features of the blood pump 110 is that the number of the liquid introduction paths 132 is three and the angle with respect to the radial direction is larger than that of the blood pump 10. Since the tooth 140 passes the liquid guide path 132, the center part of the tip is greatly dented. The liquid guide path 132 is formed so that the passage cross-sectional area gradually increases toward the outside so that the flow velocity energy of the internal blood flow can be efficiently converted into pressure energy. Moreover, it is formed so as to draw a large arc, and the internal blood flow smoothly joins the blood flow of the peripheral discharge pipe 34. A discharge pipe 136 is formed on the extension of the liquid guide path 132 at the end of the peripheral discharge pipe 34, and the end of the peripheral discharge pipe 34 is coupled to the liquid guide path 132. The suction pipe 130 is disposed on the opposite side of the discharge pipe 136, that is, on the lower side of the impeller 12 in FIG. However, with respect to this arrangement, both can be arranged on one side as in the blood pump 10.
[0024]
FIG. 7 shows a blood pump 210 according to still another embodiment. The same components as those of the blood pump 10 shown in FIG. 1 and the like are denoted by the same reference numerals, the description thereof will be omitted, and the corresponding components will be denoted by reference numerals added with 200. 7 is a cross-sectional view of the surface of the impeller 212 along the blade 222, as in FIG. 2, and the casing 216 is a cross-sectional view of the center line on the left side through the center of the tooth 240, and the right side is a flow diagram. It is sectional drawing along a line.
[0025]
One of the features of blood pump 210 is that permanent magnet 224 is directly embedded in boss 220 of both suction type impellers 212 to form an open type impeller. The impeller 212 is a double suction type as in the above-described embodiment, but is thicker in the axial direction as compared with this, and four permanent magnets are arranged on the outer peripheral portion. Vertical direction in the drawing ends of the vanes 2 22 which is erected on the boss portion 22, the blood in the vicinity of the inner surface of the casing faces the inner surface of the direct casing 216, substantially the same flow rate as the blood flow in the impeller 212 Have. In the casing 216, two liquid introduction paths 232 are arranged so as to face the two blade outlets on the front and back sides of the outer peripheral portion of the impeller 212. The liquid guide path 232 is disposed slightly obliquely with respect to the radial direction and extends toward the peripheral discharge pipe 234. This angle of inclination is determined based on the direction of the stream line of blood discharged from the impeller. The peripheral portion discharge pipe 234 circulates around the outer periphery of the casing 216 over substantially one round, and the end protrudes further outward to form a discharge pipe 236. The magnetic pole 238 includes teeth 240 and a coil 242. The teeth 240 are disposed so as to be inclined with respect to the radial direction and prevent the liquid guide path 232 and the coil 242 from interfering with each other.
[0026]
Six teeth 240 are arranged corresponding to the permanent magnets, and in FIG. 7, liquid guide paths 232 are arranged above and below. Thus, since the liquid guide path 232 and the teeth 240 do not exist on the same plane orthogonal to the axis, the arrangement of the liquid guide path 232 only needs to consider interference with the coil 242. Therefore, the cross-sectional area of the flow path can be made sufficiently large.
[0027]
In the blood pump 210, two peripheral discharge pipes 234 are disposed in a stepped portion formed by the coil 242 and the stator core, but one can be disposed outside the stator core.
[0028]
FIG. 8 shows a blood pump 310 according to still another embodiment. The same components as those of the blood pump 10 shown in FIG. 1 and the like are denoted by the same reference numerals, the description thereof will be omitted, and the corresponding components will be denoted by reference numerals added with 300. 8 is a cross-sectional view of the impeller 312 in the plane along the blade 22 as in FIG. 2, and the casing 316 is a cross-sectional view of the center line on the left side through the center of the teeth 340, and the right side is a flow chart. It is sectional drawing along a line.
[0029]
One of the features of the blood pump 310 is the arrangement of constituent members of an electric motor, that is, a magnetic pole 338 embedded in the casing 316 and a permanent magnet 324 fixed to the impeller 312. Six permanent magnets 324 are arranged in the circumferential direction in the front and rear shrouds 314 of both suction type impellers 312, and the polarities of adjacent magnets are reversed. A magnetic pole 338 is embedded in a portion of the casing 316 facing the permanent magnet 324 on the front side and the back side of the impeller 312. The magnetic pole 338 includes teeth 340 and a coil 342. By supplying three-phase AC power to the coil 342, a rotating magnetic field is formed. The impeller 312 is rotated by this rotating magnetic field.
[0030]
By the rotation of the impeller 312, blood is sucked from the suction pipe 30, further sucked from the central portion of the impeller 312, and discharged toward the outer peripheral direction. The discharged blood passes through the peripheral discharge tube 334 and is sent to the discharge tube 336.
[0031]
FIG. 9 shows a blood pump 410 according to still another embodiment. The main configuration is the same as that of blood pump 110 shown in FIGS. 5 and 6, and description of the common configuration is omitted. For the corresponding configuration, a sign obtained by adding 400 to the last two digits of the sign in FIG. Blood pump 410, the permanent magnet 424 only on the back surface shroud 414b is disposed, the magnetic pole 438 are also arranged so as to face the permanent magnet 424. Further, a control coil is provided so as to overlap the coil constituting the magnetic pole 438. The control coil can apply force to the impeller 312 in the direction perpendicular to the axis by interaction with the permanent magnet 424 by magnetic force. The outer peripheral portion of the front surface shroud 414a, are arranged ring-shaped metal ring 444. On the casing 416 side, there are at least two gaps at a position facing the outer periphery of the metal ring 444, that is, at a position perpendicular to the impeller rotation axis and equidistant from the rotation axis on a plane including the metal ring 444. A sensor 446 is disposed. The outer peripheral surface of the metal ring 444 is a cylindrical surface centered on the rotation axis of the impeller 12. The direction to be detected by the gap sensor 446 needs to be two directions passing through the center of the impeller and intersecting each other, but is preferably two directions orthogonal to each other. As the gap sensor 446, an eddy current type or a capacitance type sensor can be used. Based on the output of the gap sensor 446, the position of the impeller 412 in the radial direction can be detected, and if it is shifted, the power supplied to the coil is controlled so as to eliminate this shift and generate a force to restore the center position. To do. Further, in order to detect the positional relationship between the magnetic pole 438 and the permanent magnet 424 in the circumferential direction, three Hall elements 448 are arranged at equal intervals with respect to the magnetic pole in the circumferential direction. In the position control in the radial direction, electric power is supplied to the control coil in consideration of the positional relationship (phase) in the circumferential direction.
[0032]
The support hole 26 and the support pivot 28 are arranged with a slight gap. By performing the above-described radial position control, the rotation is maintained with little contact while the blood pump 410 is rotated. The Note that, when this axial displacement occurs, a force (restoring force) that attracts the permanent magnet 424 to the magnetic pole 438 is generated. Therefore, the neutral position is naturally controlled without performing any aggressive control.
[0033]
In the present embodiment, since the magnetic poles are arranged offset to the back face shroud 414b side of the impeller, Shirubeekiro is the pole may be disposed at a position shifted to the pump axial direction . Therefore, restrictions on the shape and arrangement of the liquid introduction path are relaxed, and the degree of design freedom is increased.
[0034]
Since the blood flow pump 410 has a small number of permanent magnets 424 and small magnetic poles, the entire weight can be suppressed.
[0035]
As described above, since the blood pump of each embodiment is a double suction type, there is no impeller rear surface in which blood is likely to stay, and clotting on the impeller rear surface, which has been a problem in the past, does not occur. Further, the impeller, since the front and back symmetrical shape, the thrust force is not generated, load bearing part consists of the support hole and the supporting pivot is small, has improved durability of the bearing. Further, unlike the normal pump, the suction pipe is not provided in the impeller rotational axis direction, and the discharge pipe is not provided in the radial direction of the impeller, both of which extend substantially in the impeller radial direction. Easy to place.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of a blood pump according to an embodiment.
FIG. 2 is a cross-sectional view of another blood fracture surface of FIG.
FIG. 3 is a front view of the blood pump of FIG. 1;
4 is a side view of the blood pump of FIG. 1. FIG.
FIG. 5 is a cross-sectional view showing a configuration of a blood pump according to another embodiment.
6 is a cross-sectional view of another blood fracture surface of the blood pump of FIG.
FIG. 7 is a cross-sectional view showing a configuration of a blood pump according to still another embodiment.
FIG. 8 is a cross-sectional view showing a configuration of a blood pump according to still another embodiment.
FIG. 9 is a cross-sectional view showing a configuration of a blood pump according to still another embodiment.
[Explanation of symbols]
12 impellers, 16 casings, 20 bosses, 22 blades, 24 permanent magnets, 26 support holes, 28 support pivots, 30 suction pipes, 32 liquid conduits, 36 discharge pipes, 38 magnetic poles, 40 teeth, 42 coils.

Claims (4)

An impeller that discharges blood sucked from a suction portion provided in the center portion of the front and back surfaces from the outer peripheral portion, and a casing that houses the impeller,
Magnetic poles and coils that generate a rotating magnetic field are arranged in the casing, permanent magnets are arranged in the impeller, the casing functions as a stator of the electric motor, and the impeller functions as a rotor of the electric motor,
The impeller is provided with support holes that are dented in a slit shape on both front and back surfaces of the impeller rotation center in the suction portion,
The casing is provided with a support pivot projecting along the rotation axis of the impeller toward the support holes on both the front and back surfaces,
The support hole and the tip of the support pivot are in point contact, and the impeller is supported by point contact with the support pivot at the center of rotation thereof,
The casing extends from the lateral direction of the rotation axis of the impeller, branches in the middle, and one extends from the lateral direction of the axis of the support pivot to the suction portion on the front surface, and the other extends to the suction portion on the back surface. A suction pipe extending from the lateral direction of the axis of the support pivot is provided,
Double suction type blood pump.   2. The blood pump according to claim 1, wherein the permanent magnet is disposed near an outer periphery of the impeller, and the magnetic pole is disposed at a position facing the permanent magnet in a radial direction of the impeller.   The blood pump according to claim 2, wherein the impeller is loosely supported by the support pivot.   The blood pump according to claim 2 or 3, wherein a liquid guide path through which the blood discharged from the impeller flows is arranged at least between the adjacent magnetic poles.

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