JP2009106690A - Magnetic levitation blood pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic levitation blood pump which can be used for a medium period and a long period of time and eliminates blood damage.
A cone type impeller incorporated in a pump housing is supported by a magnetic bearing in a non-contact manner, and a washout hole is provided in the lowest cone of the cone type impeller so that a secondary flow of blood is generated in the pump head. Formed.
[Selection] Figure 1

Description

  The present invention relates to a centrifugal blood pump having a pump head (blood contact portion) as a disposable part, and more particularly, a magnetically levitated blood that can be used for a medium period and a long period of time and eliminates blood damage. Regarding pumps.

  Today, as a centrifugal blood pump used during and after heart and blood vessel surgery, a disposable centrifugal blood pump that replaces a pump head composed of an impeller that contacts a patient's blood and a pump housing that houses the impeller is widely used. Yes.

  Thus, conventionally, in this type of disposable centrifugal blood pump, the impeller is supported on the pump housing by a contact-type bearing protected by a pivot bearing or a mechanical seal. As shown, the three cones 1a to 1c having a conical section are combined in three layers with a gap between them to form a cone-type impeller 1, which is made up of a contact bearing 3 and a support shaft 5. A centrifugal blood pump 9 is disclosed which is rotatably supported by a pump housing 7. And the pump head (blood contact part) 11 which consists of the cone-type impeller 1 and the pump housing 7 which accommodates this is made into the disposable part.

The pump head 11 is detachably mounted on a reuse unit 17 having a motor 13, a torque transmission disk 15 and the like, and includes a magnet 19 mounted on the cone 1c at the lowest step and a torque transmission disk. A magnetic coupling 23 is generated between the magnet 21 and the magnet 21 attached to the magnet 15. Then, as shown in FIG. 14, when the torque transmission disk 15 is rotated by driving the motor 13, the cone-type impeller 1 rotates in the same direction in conjunction with this, so that the pump housing 7 is rotated as shown in FIGS. The operating energy is given to the blood B flowing in from the blood inlet 25 at the top of the head by rotation of the cone type impeller 1 (the rotation of the cone type impeller 1 is transmitted to the blood B by viscous friction), and the blood B is pump housing The blood flows out from a blood outlet 27 provided on the side surface of 7.
Cardiopulmonary Handbook (2004) pages 55-61 Editor Hideo Adachi, Naoki Momose Chugai Medical Co., Ltd.

  However, since the contact type bearing 3 is used without lubrication in order to avoid contamination of blood B, there is a problem of durability due to severe wear and friction. For this reason, the expiry date of the pump head 11 which is a disposable part Is limited to a maximum of about two days, but the fact that replacement every two days is a heavy burden for medical institutions and patients.

  Further, blood damage such as thrombus around the bearing 3 and hemolysis due to the bearing 3 has been pointed out by using the contact type bearing 3.

  The present invention has been devised in view of such circumstances, and an object of the present invention is to provide a magnetic levitation blood pump that can be used for a medium period and a long period of time and eliminates blood damage.

  In order to achieve such an object, a magnetically levitated blood pump according to claim 1 includes a pump housing having a blood inlet and a blood outlet formed at the top and sides, and is rotatably accommodated in the pump housing. A disposable pump head composed of an impeller and a reusable unit to which the pump head is detachably attached.The impeller is formed by laminating a plurality of cones formed in a conical section with a gap, A washout hole that creates a secondary blood flow is formed in the center of the lowermost cone, and a ring-shaped magnetic pole surface is formed on the upper and lower ends of the outer peripheral surface of the lowermost cone. A cone type impeller mounted on a cylindrical magnetic bearing rotor made of a magnetic material formed in a circumferential direction and having a plurality of magnetic pole faces projecting inwardly on the upper end side and the lower end side of the inner peripheral surface. Units are arranged at equal intervals around the pump housing, and the magnetic pole surfaces are arranged opposite to each other along the magnetic pole surface formed on the outer peripheral surface of the magnetic bearing rotor to generate a magnetic coupling with the magnetic bearing rotor. Three or more electromagnets for magnetic bearings and a ring-shaped permanent magnet magnetized in the thickness direction are sandwiched between two upper and lower ring members made of magnetic material. A plurality of magnetic pole faces corresponding to the magnetic pole faces protruding from the inner peripheral surface of the magnetic bearing rotor, and generating a magnetic coupling with the magnetic bearing rotor; and the pump head And a motor for rotationally driving the torque transmission disk, and a displacement meter for measuring the displacement of the magnetic bearing rotor in the radial direction. And bottom along the outer shape of the motor is formed in a cylindrical shape, said bottom is characterized removably attach it between the magnetic bearing electromagnet and the torque transmission disk.

  According to the first aspect of the present invention, the cone type impeller incorporated in the pump housing is supported in a non-contact manner by the magnetic bearing, and the durability is higher than that of the conventional example in which the impeller is supported by the contact type bearing. As a result, the pump head can be used for a long period of time.

  In addition, as a result of supporting the cone type impeller in a non-contact manner with a magnetic bearing, conventional blood damage such as thrombus around the bearing and hemolysis due to the bearing can be eliminated, and a washout hole is provided in the lowermost cone. By forming the secondary flow of blood, the dynamic pressure action in the thrust direction acts on the cone type impeller, so that the cone type impeller rotates smoothly, and the formation of a thrombus due to the retention of blood can be prevented more reliably. Has the advantage of being able to.

  Further, since the motor is separated from the pump head so that the heat of the motor is difficult to be transmitted to the blood flowing down in the pump head, blood coagulation due to heat can be reliably prevented.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIGS. 1 to 13 show an embodiment of a magnetic levitation blood pump according to claim 1. As shown in FIG. 1, a magnetic levitation blood pump 31 according to this embodiment includes a reuse unit 33 and a reusable unit 33. A pump head (blood contact portion) 35 detachably attached to the upper portion of the utilization unit 33. As described below, a pump housing 37 and a magnetic bearing rotor 39, a cone-type impeller 41 and the like mounted therein are used. The pump head 35 is a disposable part, and the rotation of the cone-type impeller 41 is transmitted to the blood B flowing in from the blood inlet 43 at the top of the pump housing 37 as shown in FIG. It flows out from the blood outlet 45 provided in the side part.

  A brushless DC motor (hereinafter referred to as a “DC motor”) 47 disposed away from the pump head 35, a torque transmission disk 49 that rotates in synchronization therewith, and as shown in FIGS. As shown in FIG. 2, a reuse unit 33 including four magnetic bearing electromagnets 51x, 51y, 53x, 53y and the like installed around the pump housing 37 is a reusable part of the magnetic levitation blood pump 31. The pump housing 37 (pump head 35) has an outer diameter of φ124, a height of 65 mm, and a blood inlet 43 of φ9. As shown in FIG. 1, the reuse unit 33 is set to a height and width of 160 mm. Has been.

  First, the cone-type impeller 41 of the pump head 35 will be described. As shown in FIGS. 2 to 4, the cone-type impeller 41 uses polycarbonate cones 41a and 41b formed in a conical section and polycarbonate. The cones 41c formed in a conical section are stacked with gaps 55 and 57, respectively. The three cones 41a, 41b, and 41c are provided with alignment projections and grooves (not shown). It has a structure in which these are fixed by adhesion. As shown in FIGS. 3 and 4, the diameters of the three cones 41a, 41b, and 41c are all set to φ79, and the entire cone-type impeller 41 is set to a height dimension of 55 mm and a width dimension of φ79. . Further, as shown in FIG. 4, the intervals between the downstream ends of the gaps 55 and 57 are set to 2.6 mm and 1.4 mm, respectively.

  As shown in FIGS. 2 and 4, the uppermost cone 41a and the second cone 41b are formed thin like the cones 1a and 1b in FIG. The blood flow ports 59 and 61 are provided coaxially with the blood flow port 43, and the diameter of the blood flow port 59 is set to φ14, and the diameter of the blood flow port 61 is set to φ9.4.

  On the other hand, as shown in FIG. 2 and FIG. 4, in the center of the lowermost cone 41c, a washout having a circular shape in a plan view that creates a secondary flow of blood B coaxially with the blood inlet 43 as will be described later. The hole 63 is provided with a diameter of φ8 across the vertical direction. The bottom surface of the cone 41c is shaped along the pump housing 37, and the magnetic bearing rotor 39 is integrally incorporated in an annular protrusion 65 formed along the peripheral edge of the bottom portion.

  FIG. 6 shows the details of the magnetic bearing rotor 39, in which 67 is a ring-shaped neodymium permanent magnet magnetized in the thickness direction, and 69 and 71 are teeth in the axial direction at equal intervals on the inner peripheral surface. A magnetic bearing rotor 39 is formed by sandwiching a neodymium permanent magnet 67 between the electromagnetic soft iron rings 69 and 71 by two electromagnetic soft iron rings (ring members) that are grooved.

  The outer peripheral surface of the electromagnetic soft iron ring 69 that is the upper end of the magnetic bearing rotor 39 and the outer peripheral surface of the electromagnetic soft iron ring 71 that is the lower end of the magnetic bearing rotor 39 are ring-shaped magnetic pole surfaces 73 and 75, respectively. A stationary magnetic field is generated between the two magnetic pole surfaces 73 and 75 by the neodymium permanent magnet 67.

  Further, as described above, the inner peripheral surfaces of the electromagnetic soft iron rings 69 and 71 are each subjected to tooth groove processing at equal intervals in the axial direction, and thereby the upper end side of the inner peripheral surface of the magnetic bearing rotor 39 and At the same position on the lower end side, a plurality of tooth-shaped magnetic pole surfaces 77 and 79 are projected inward at equal intervals. As shown in FIG. 2 or 4, the magnetic bearing rotor 39 is integrally incorporated in the annular protrusion 65 of the cone 41c, and the magnetic bearing rotor 39 and the cone type impeller 41 are disposed in the pump housing 37. It is stored in.

  As shown in FIG. 2, the pump housing 37 is made of the same material as the cone-type impeller 41. As described above, the blood inlet 43 and the blood outlet 45 are provided on the top and side surfaces of the pump housing 37, and the bottom 81 is provided. Is formed in a cylindrical shape along the outer shape of the protrusion 65.

  As described above, in the present embodiment, a plurality of tooth-shaped magnetic pole surfaces 77 and 79 are provided at equal intervals on the inner peripheral surface of the electromagnetic soft iron rings 69 and 71, but these magnetic pole surfaces 77 and 79 are not necessarily provided. For example, the four magnetic pole surfaces 77 and 79 may be provided symmetrically with an interval of 100 ° and 80 °, respectively.

  As shown in FIGS. 1, 5, and 7, 4 on the base 83 through the electromagnet mounting base 95 so as to surround the bottom 81 of the pump housing 37 mounted on the base 83 of the reuse unit 33. Two electromagnets 51x, 51y, 53x, 53y are arranged at intervals of 90 °, and these electromagnets 51x, 51y, 53x, 53y and the magnetic bearing rotor 39 do not contact the load of the cone-type impeller 41 by magnetic force. The magnetic bearing 85 to support is comprised.

  As shown in FIGS. 1 and 7, the magnetic bearing 85 is a bearing having a positive rigidity in five degrees of freedom excluding the rotation direction (Ψ direction) centered on the thrust direction (Z direction) of the cone-type impeller 41. .

  As shown in FIG. 1, five degrees of freedom are one degree of freedom in the thrust direction (Z direction), two degrees of freedom in the radial direction (X direction and Y direction), and two degrees of freedom in the tilt direction (Θ direction and Φ direction). In the degree of freedom, the thrust direction corresponds to the rotation axis direction of the cone-type impeller 41, the radial direction corresponds to the direction perpendicular to the rotation axis direction, and the tilt direction corresponds to the direction of minute rotation around the radial direction.

  Further, the magnetic bearing 85 is a two-degree-of-freedom control type magnetic bearing, and of the five degrees of freedom described above, only two degrees of freedom in the radial direction (X direction, Y direction) are controlled. That is, only the radial direction (X direction, Y direction) is an active type, and the three degrees of freedom of the other thrust direction (Z direction) and the tilt direction (Θ direction, Φ direction) are passive types.

  Hereinafter, the configuration of the magnetic bearing 85 will be described. As shown in FIGS. 1, 5, and 7, the electromagnets 51x, 51y, 53x, 53y are composed of two electromagnets 51x, 53x for x-direction control and y-direction control. The electromagnets 51x and 53x for x-direction control are arranged opposite to each other in the x-direction across the magnetic bearing rotor 39 (the bottom 81 of the pump housing 37), and are used for y-direction control. Similarly, the electromagnets 51y and 53y are arranged opposite to each other in the y direction with the magnetic bearing rotor 39 interposed therebetween.

  Since the configurations of the electromagnets 51x, 51y, 53x, and 53y are all the same, the configuration of the electromagnet 51y as an example will be described with reference to FIG. 7. The electromagnet 51y has a coil 89 at the center of the U-shaped electromagnetic soft iron core 87. When the electromagnetic soft iron core 87 is formed of annealed pure iron, the hysteresis loss of the magnetic bearing 85 is reduced, contributing to lower heat generation of the electromagnet 51y, and in the pump head 35 (pump housing 37). Coagulation of blood B flowing down can be prevented.

  In addition, when the electromagnetic soft iron core 87 is formed of a powder core (compressed pure iron fine particles and hardened with an adhesive), eddy current loss is reduced, contributing to lower heat generation of the electromagnet 51y, and magnetic bearings. Since the band width of the electromagnetic force for starting control can be increased from 85, the vibration of the magnetic bearing rotor 39 is reduced, which has the advantage of further preventing hemolysis and preventing blood B from coagulating.

  The electromagnetic soft iron core 87 is provided with two magnetic pole surfaces 91 and 93 that are arranged to face each of the partial areas of the magnetic pole surfaces 73 and 75 of the magnetic bearing rotor 39. As shown in FIG. The shape of 93 is an arc shape along partial regions of the magnetic pole surfaces 73 and 75 of the magnetic bearing rotor 39. The gap between the magnetic pole surfaces 73 and 75 and the magnetic pole surfaces 91 and 93 facing each other across the bottom 81 is set to a narrow size.

  Thus, the magnetic bearing rotor 39 and the electromagnet 51y are arranged so that the magnetic pole surfaces 73 and 91 face each other and the magnetic pole surfaces 75 and 93 face each other. For this reason, the stationary magnetic field generated between the magnetic pole surfaces 73 and 75 by the neodymium permanent magnet 67 of the magnetic bearing rotor 39 passes through the magnetic pole surfaces 91 and 93 of the electromagnet 51y.

  That is, as shown in FIG. 7, the magnetic soft iron ring 69 → the magnetic pole surface 73 → the gap → the magnetic pole surface 91 → the electromagnetic soft iron core 87 → the magnetic pole surface 93 → the gap → the magnetic pole surface 75 → After passing through the electromagnetic soft iron ring 71 in sequence, a magnetic coupling that forms a closed loop of the magnetic flux φ returning to the south pole of the neodymium permanent magnet 67 occurs.

  Here, the sign of the rigidity of the virtual magnetic coupling is “positive” with respect to three degrees of freedom in which the thrust direction (Z direction) and the tilt direction (Θ direction, Φ direction) are combined. In other words, when the magnetic bearing rotor 39 is displaced from the ideal position in the direction of arrow A as shown in FIG. 8 in one degree of freedom in the thrust direction (Z direction), the magnetic bearing rotor 39 has a restoring force due to the loop of the magnetic flux φ. F1 works.

  As shown in FIG. 9, when the magnetic bearing rotor 39 is tilted in the direction of arrow B from the ideal position in two degrees of freedom in the tilt direction (Θ direction, Φ direction), the magnetic bearing rotor 39 has a magnetic flux φ. The restoring torque F2 due to the loop is activated.

  In any case, the magnetic bearing rotor 39 has one magnetic pole surface 73 facing the magnetic pole surface 91 of the electromagnet 51y and the other magnetic pole surface 75 of the electromagnet 51y as shown in FIG. 7 by the restoring force F1 or the restoring torque F2. It moves toward the state facing the magnetic pole surface 93 (that is, the state aligned in an ideal position).

  These restoring force F1 and restoring torque F2 similarly act on the magnetic bearing rotor 39 in the other electromagnets 51x, 53x, 53y.

  As a result, the magnetic bearing rotor 39 is stably held in an aligned state in which the magnetic pole surfaces 73 and 75 are opposed to the magnetic pole surfaces 91 and 93, respectively. That is, regarding the three degrees of freedom in the non-control direction that combines the thrust direction (Z direction) and the tilt direction (Θ direction, Φ direction), the rigidity of the magnetic bearing rotor 39 is determined by the loop of the magnetic flux φ from the neodymium permanent magnet 67. Can be secured sufficiently.

  On the other hand, regarding the two degrees of freedom in the radial direction (X direction, Y direction), the rigidity of the virtual spring due to the loop of the magnetic flux φ from the neodymium permanent magnet 67 becomes “negative”.

  For this reason, in this embodiment, for the purpose of correcting the rigidity of the magnetic coupling 85 in the radial direction (X direction, Y direction) to “positive”, the x direction control electromagnets 51x and 53x and the y direction control The exciting current is supplied to the coils 89 of the two electromagnets 51y and 53y. The direction and strength of the excitation current for each coil 89 is feedback controlled based on the output signal from the displacement sensor 93.

  As shown in FIG. 1, an electromagnet mounting base 95 is disposed on a base 83 of the reuse unit 33, but two displacement sensors are disposed at 90 ° intervals on the electromagnet mounting base 95 with the electromagnet 51y interposed therebetween. 97 is installed toward the center of the magnetic bearing rotor 39, and these displacement sensors 97 measure the displacement of the magnetic bearing rotor 39 in the radial direction (X direction, Y direction).

  A control device (not shown) for the magnetic bearing 85 compares the output signal from the displacement sensor 97 with the target position signal in the radial direction of the magnetic bearing rotor 39 and feeds back the magnetic bearing rotor 39 to the target position. Control.

  For example, when the magnetic bearing rotor 39 is displaced from the ideal position in the direction of the arrow in one degree of freedom in the X direction as shown in FIG. 10, the control device has a direction opposite to the displacement direction as shown in FIG. In order to generate the control force F3, the direction and strength of the excitation current supplied to the coil 89 of the electromagnets 51y and 53y for y direction control are feedback controlled.

  Therefore, when the magnetic bearing rotor 39 is displaced toward the electromagnet 51y as shown in FIG. 10, the control device generates a magnetic flux φ1 opposite to the magnetic flux φ by the electromagnet 51y as shown in FIG. 11, and the other electromagnet 53y. Generates a magnetic flux φ2 in the same direction as the magnetic flux φ. At this time, the magnetic flux φ is weakened in the magnetic circuit including the electromagnetic soft iron core 87 of the electromagnet 51y, and the magnetic flux φ is increased in the magnetic circuit including the electromagnetic soft iron core 43 of the electromagnet 53y. As a result, a control force F3 that pulls the magnetic bearing rotor 39 back toward the electromagnet 53y is generated, and the gap at the magnetic bearing rotor 39 and the electromagnet 53y side becomes equal to the gap at the electromagnet 51y side. It is held stably.

  The same feedback control is performed for the x-direction control electromagnets 51x and 53x, and the magnetic bearing rotor 39 is stabilized at a target position where the gap on the electromagnet 51x side and the gap on the electromagnet 53x side are equal. Held.

  That is, regarding the two degrees of freedom in the radial direction (X direction, Y direction), by combining the loop of the magnetic flux φ from the neodymium permanent magnet 67 and the loop of the magnetic fluxes φ1, φ2 from the electromagnets 51x, 51y, 53x, 53y, The rigidity of the virtual spring becomes “positive”, and the rigidity of the magnetic bearing rotor 39 can be sufficiently secured.

  As described above, the magnetic bearing 85 of the present embodiment relates to the three degrees of freedom in the non-control direction in which the thrust direction (Z direction) and the tilt direction (Θ direction, Φ direction) of the magnetic bearing rotor 39 are combined. Sufficient rigidity can be ensured by the loop of the magnetic flux φ from the magnetic field, and further, with respect to two degrees of freedom in the radial direction (X direction, Y direction), by combining with the loop of the magnetic flux φ1, φ2 from the electromagnets 51x, 51y, 53x, 53y Sufficient rigidity can be secured. That is, high rigidity with 5 degrees of freedom is realized.

  On the other hand, as shown in FIG. 1, a DC motor 47 is installed at a lower portion of the reuse unit 33 with a motor mounting frame 99 fixed to the base 83 spaced apart from the pump head 35. Has the same central axis as the pump housing 37 attached to the upper portion of the base 83.

  A power transmission shaft 105 made of a material having low thermal conductivity is connected to the motor shaft 101 via a coupling 103, and the power transmission shaft 105 is rotatably supported on a base 83 via a bearing 107. Has been. A ring-shaped torque transmission disk 49 for transmitting torque to the magnetic bearing rotor 39 is connected to the tip of the power transmission shaft 105 protruding from the upper surface of the base 83 via a connecting member 109 having a circular shape in plan view. When the pump head 35 is mounted on the upper portion of the base 83, the torque transmission disk 49 is disposed inside the pump housing 37 with the same center axis as the bottom 81 as shown in FIGS. It is like that.

  As shown in FIG. 12, the torque transmission disk 49 is composed of one ring-shaped neodymium permanent magnet 111 magnetized in the opposite direction to the neodymium permanent magnet 67 of the magnetic bearing rotor 39, and the outer peripheral surface is equally spaced in the axial direction. In this structure, the upper and lower electromagnetic soft iron rings (ring members) 113 and 115 are processed so as to be integrated with each other.

  The tooth groove machining of the electromagnetic soft iron rings 113 and 115 is performed in accordance with the tooth groove machining of the inner circumferential surfaces of the electromagnetic soft iron rings 69 and 71, and thereby the upper end of the outer circumferential surface of the torque transmission disk 49. A plurality of tooth-shaped magnetic pole surfaces 117 and 119 facing the magnetic pole surfaces 77 and 79 of the magnetic bearing rotor 39 are formed on the side and the lower end side.

  For this reason, as shown in FIG. 12, even in the torque transmission disk 49, the stationary magnetic field generated between the magnetic pole surfaces 117 and 119 by the neodymium permanent magnet 111 and the magnetic pole surface by the neodymium permanent magnet 67 of the magnetic bearing rotor 39. A magnetic coupling that forms a closed loop of the magnetic flux φ3 indicated by an arrow is generated between the magnetic bearing rotor 39 and the torque transmission disk 49 by the steady magnetic field generated between 77 and 79.

  Thus, this magnetic coupling transmits torque from the DC motor 47 to the magnetic bearing rotor 39 between the torque transmission disk 49 and the magnetic bearing rotor 39 and rotates it in the direction of the arrow as shown in FIG. In addition to the magnetic bearing rotor 39 and the magnetic bearing 85 by the magnetic coupling between the electromagnets 51x, 51y, 53x, 53y, the displacement of the magnetic bearing rotor 39 in the thrust direction (Z direction) and the tilt direction (Θ direction, Φ direction) It will function as a magnetic bearing 121 that restores the inclination.

  As shown in FIG. 2, a gap 123 through which blood B flows is also formed between the upper surface of the uppermost cone 41 a of the cone-type impeller 41 and the inner periphery of the pump housing 37. 85, 121 forms a fluid gap 125 of 0.5 mm between the projection 65 of the lowermost cone 41c and the pump housing 37, and between the concave bottom surface 127 at the center of the bottom of the cone 41c and the housing 37. A 1.0 mm-fluid gap 129 is formed on the corn-type impeller 41 so that the cone-type impeller 41 and the housing 37 are not in contact with each other. As shown in FIG. 1, the pump head 35 is placed on the electromagnet mount 95, and the bottom 81 of the pump housing 37 is inserted between the torque transmission disk 49 and the electromagnets 51x, 51y, 53x, 53y. However, a suction hole (not shown) of a conventionally well-known vacuum chuck (fixing means) is opened on the upper surface of the base 83, and the vacuum pump is drawn from the suction hole when the magnetic levitation blood pump 31 is used. Thus, the bottom 81 is sucked to prevent the pump head 35 from falling off the reuse unit 33.

  Since the magnetic levitation blood pump 31 according to the present embodiment is configured as described above, when the magnetic levitation blood pump 31 is used, the bottom 81 of the pump housing 37 is connected to the torque transmission disk 49 and the electromagnets 51x, 51y, 53x, When the vacuum pump is operated after the pump head 35 is placed on the electromagnet mount 95 after being inserted between the pump head 35 and the electromagnet mounting base 95, the pump head 35 is fixed on the reuse unit 33 by the vacuum chuck.

  Thus, when the pump head 35 is mounted on the reuse unit 33 in this way, the magnetic coupling generated between the magnetic bearing rotor 39 and the torque transmission disk 49, the electromagnets 51x, 51y, 53x, 53y and the magnetic Due to the magnetic coupling generated between the bearing rotor 39 and the cone-type impeller 41 in which the magnetic bearing rotor 39 is integrally incorporated as shown in FIG. And supported in a non-contact state. As described above, in this non-contact state, a gap 123 through which the blood B flows is formed between the upper surface of the uppermost cone 41a of the cone-type impeller 41 and the inner periphery of the pump housing 37. A fluid gap 125 of 0.5 mm is formed between the projection 65 of the lowermost cone 41 c and the pump housing 37, and a fluid of 1.0 mm is formed between the concave bottom surface 127 at the center of the bottom of the cone 41 c and the housing 37. A gap 129 is formed.

  In this state, when the DC motor 47 is driven to rotate and the torque transmission disk 49 is rotated in the direction of the arrow as shown in FIG. 12, it is generated between the torque transmission disk 49 and the magnetic bearing rotor 39 as shown in FIG. Torque is transmitted to the magnetic bearing rotor 39 by the magnetic coupling, the magnetic bearing rotor 39 rotates in the same direction, and the cone-type impeller 41 rotates in the same direction.

  For this reason, as shown in FIG. 2, when the blood B flowing in from the blood inlet 43 at the top of the pump housing 37 enters the gaps 123, 55, 57, the rotation of the cone-type impeller 41 is caused by the viscous friction. The blood B flows out from the blood outlet 45 provided on the side of the pump housing 37.

  In addition, a secondary flow of blood B is formed in which blood B to which kinetic energy is given by the rotation of the cone-type impeller 41 returns to the gap 57 from the fluid gap 125 and the bottom surface 127 of the recess through the washout hole 63. The

  As a result, the secondary flow causes a dynamic pressure action in the thrust direction to act on the cone type impeller 41 so that the cone type impeller 41 rotates smoothly, and the blood B between the bottom of the cone type impeller 41 and the pump housing 37 is obtained. The formation of thrombus due to the staying of water is prevented.

  As described above, the magnetic bearings 85 and 121 are ideal for the displacement and inclination of the magnetic bearing rotor 39 in the thrust direction (Z direction) and the inclination direction (Θ direction and Φ direction) when the cone type impeller 41 rotates. In order to restore the magnetic bearing rotor 39 to the ideal position by the feedback control of the displacement in the radial direction (X direction, Y direction) by the control device via the magnetic bearing 85, the magnetic bearing rotor 39 is restored to the ideal position. The impeller 41 will rotate stably.

  Further, as the DC motor 47 is driven, the DC motor 47 generates heat due to copper loss and iron loss due to magnetic field fluctuations. However, as described above, in the present embodiment, the DC motor 47 is separated from the pump head 35 and reused. Due to the structure in which the power transmission shaft 105 is formed of a material having low thermal conductivity, the heat of the DC motor 47 is not transmitted to the blood B flowing down in the pump head 35 due to the structure disposed at the lower part of the unit 33 and the power transmission shaft 105 made of a material having low thermal conductivity. However, since the torque transmission disk 49 rotates in synchronism with the magnetic bearing rotor 39, no magnetic field fluctuation occurs near the pump head 35.

  When the pump head 35 is replaced, the pump head 35 may be removed from the reuse unit 33 and a new pump head 35 may be attached to the reuse unit 33.

  As described above, the magnetically levitated blood pump 31 according to the present embodiment has a structure in which the cone-type impeller 41 incorporated in the pump housing 37 is supported by the magnetic bearings 85 and 121 in a non-contact manner. The durability is improved as compared with the conventional example that has been supported, and the pump head 35 can be used for a medium period and a long period.

  Further, as a result of supporting the cone-type impeller 41 in a non-contact manner by the magnetic bearings 85 and 121 as described above, according to this embodiment, conventional blood damage such as thrombus around the bearing and hemolysis due to the bearing can be eliminated. Since the washout hole 63 is provided in the lowermost cone 41c to form the secondary flow of blood B, the dynamic pressure action in the thrust direction acts on the cone-type impeller 41, and the cone-type impeller 41 rotates smoothly. In addition, there is an advantage that the formation of a thrombus due to the retention of blood B can be more reliably prevented.

  Furthermore, as described above, in the present embodiment, the DC motor 47 is spaced from the pump head 35 and disposed below the reuse unit 33, and the power transmission shaft 105 is formed of a material having low thermal conductivity. Since the structure is such that the heat of the DC motor 47 is difficult to transmit to the blood B flowing down in the pump head 35, the coagulation of the blood B due to heat can be reliably prevented.

  Furthermore, if the electromagnetic soft iron core 87 of the electromagnets 51x, 51y, 53x, 53y is formed of annealed pure iron as described above, the hysteresis loss of the magnetic bearing 85 is reduced and the electromagnets 51x, 51y, 53x, Since this contributes to a reduction in heat generation of 53y, the coagulation of blood B flowing down in the pump head 35 can be prevented.

  On the other hand, if the electromagnetic soft iron core 87 is formed of a powder core, the eddy current loss is reduced, contributing to lower heat generation of the electromagnets 51x, 51y, 53x, 53y, and an electromagnetic force band for starting control from the magnetic bearing 85. Since the width can be extended, the vibration of the magnetic bearing rotor 39 is reduced, which has the advantage of preventing hemolysis and coagulation of blood B.

  In addition, according to this embodiment, since the pump head 35 of the disposable part is fixed to the reuse unit 33 with a vacuum chuck, the pump head 35 is used during and after cardiac surgery. There is no risk that it will fall off and an unexpected situation will occur.

  In the above-described embodiment, a vacuum chuck is used as a means for fixing the pump head 35 to the reuse unit 33. However, the pump head 35 is detached by using friction between the outer peripheral surface of the pump head 35 and the electromagnet mounting base 95. It may be prevented.

1 is an overall perspective sectional view of a magnetic levitation blood pump according to one embodiment of the present invention. It is sectional drawing of a pump head, and the principal part expanded sectional view. It is a top view of a pump head. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3 and an enlarged cross-sectional view thereof. It is a top view of a magnetic bearing rotor and an electromagnet. It is a perspective sectional view of a magnetic bearing rotor. It is a perspective sectional view of a magnetic bearing rotor and an electromagnet. It is a longitudinal cross-sectional view of a magnetic bearing rotor, an electromagnet, and a torque transmission disk. It is a longitudinal cross-sectional view of a magnetic bearing rotor, an electromagnet, and a torque transmission disk. It is a perspective sectional view of a magnetic bearing rotor, an electromagnet, and a torque transmission disk. It is a perspective sectional view of a magnetic bearing rotor, an electromagnet, and a torque transmission disk. It is a perspective sectional view of a magnetic bearing rotor, an electromagnet, and a torque transmission disk. It is a perspective sectional view of a magnetic bearing rotor, an electromagnet, and a torque transmission disk. It is a schematic block diagram of the conventional disposable centrifugal blood pump. It is explanatory drawing which shows the flow of the blood by the conventional cone type impeller.

Explanation of symbols

31 Magnetic levitation blood pump 33 Reuse unit 35 Pump head 37 Pump housing 39 Magnetic bearing rotor 41 Cone type impeller 41a, 41b, 41c Cone 43 Blood inlet 45 Blood outlet 47 Motor 49 Torque transmission disks 51x, 51y, 53x, 53y Electromagnets 55, 57, 123 Clearance 59, 61 Blood outlet 63 Washout hole 67, 111 Neodymium permanent magnets 69, 71, 113, 115 Electromagnetic soft iron rings 73, 75, 77, 79, 91, 93, 117, 119 Magnetic poles Surface 83 Base 85, 121 Magnetic bearing 87 Electromagnetic soft iron core 89 Coil 97 Displacement sensor 101 Motor shaft 125, 129 Fluid gap φ, φ1, φ2, φ3 Magnetic flux

Claims (1)

A disposable pump head comprising a pump housing having a blood inlet and a blood outlet formed at the top and sides, and an impeller rotatably accommodated in the pump housing;
It consists of a reuse unit to which the pump head is detachably attached,
The impeller is formed by laminating a plurality of cones having a conical cross section, and a washout hole that creates a secondary blood flow is formed in the vertical direction in the center of the lowest cone, Ring-shaped magnetic pole surfaces are formed in the circumferential direction on the upper end side and the lower end side of the outer peripheral surface, and a plurality of magnetic pole surfaces project inwardly on the upper end side and the lower end side of the inner peripheral surface of the cone at the lowermost step. Cone type impeller to which a cylindrical rotor made of magnetic material is attached.
The reusable units are arranged at equal intervals around the pump housing, and the magnetic pole surfaces are arranged opposite to each other along the magnetic pole surfaces formed on the outer peripheral surface of the rotor to generate a magnetic coupling with the rotor. Three or more electromagnets for magnetic bearings and a ring-shaped permanent magnet magnetized in the thickness direction are sandwiched between ring members made of two upper and lower magnetic materials. A plurality of magnetic pole faces corresponding to the magnetic pole faces projecting from the inner peripheral surface of the rotor, and a torque transmission disk for generating magnetic coupling with the rotor; and a position separated from the pump head A motor that rotationally drives the torque transmission disk, and a displacement meter that measures displacement in the radial direction of the rotor,
The pump housing has a bottom formed in a cylindrical shape along the outer shape of the rotor, and the bottom is detachably mounted between the electromagnet for magnetic bearing and the torque transmission disk. Blood pump.

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