DE112004001809T5 - Axial flow blood pump with magnetically suspended, radially and axially stabilized impeller - Google Patents

Abstract

Blood pump containing:
A stator having a cavity extending therethrough;
An impeller rotatably disposed in the cavity of the stator and magnetically suspended, the impeller defining an axis of rotation and the stator and the impeller defining a fluid passage therebetween;
A plurality of magnetic bearings containing passive permanent magnets and active electromagnetic magnets which cause the impeller to float within the cavity of the stator, including an axial bearing for axially supporting the impeller in the cavity;
Wherein the axial bearing includes an array of adjacent bearing sets axially aligned with respect to the axis of rotation, each bearing set including an impeller magnet on the impeller and a stator magnet on the stator and the impeller and stator magnets radially aligned with each other across the fluid passage ;
- where adjacent impeller magnets and adjacent stator magnets have axially aligned polarities and reversed polarities with respect to adjacent magnets, and

Description

background Field of the invention

The The present invention relates generally to axial flow blood pumps, those for permanent implantation in humans as a support device for one are suitable for chronic chamber.

affected Area of Expertise

A effective and reliable axial-flow Can Provide Mechanical Circulatory Support (MCS) to Thousands of Patients Every Year Offer. estimated 4.8 million Americans suffer from congestive heart failure (CHF), a clinical syndrome characterized by a ventricular dysfunction and finally associated with a reduction in cardiac output. A reduction of the heart output leads low blood flow, fluid accumulation and activation of saltwater retention mechanisms. Statistics from the American Heart Association indicate that about 400,000 new CHF cases be diagnosed every year in the United States, and estimated 40,000 heart failure patients die every year in a row from CHF.

If a short-term medical Intervention, either surgically or by aggressive medication, not successful, many of these heart failure patients become candidates for heart transplants. Because of a limited number of donor hearts every year (2,500) available are, need CHF patients frequently MCS as a Bridging to the Transplantation, and many such patients do not survive while they are wait for a donor organ. Chamber Support Devices (VADs) or mechanical blood pumps have proven to be successful at bridging Heart transplantation of patients who were diagnosed with a heart defect suffer in the final stage, and encourage the belief that a long-term MCS or target therapy possible is. estimated 35,000 to 70,000 heart failure patients could be long-term each year MCS benefit.

• 1) Komponentenhaltbarkeit und Nutzungsdauer;
• 2) Blutgerinnung oder Thrombose infolge von Strömungsstau in der Pumpe in sekundären Strömungsbereichen, Waschöffnungen, Rezirkulationsbereichen und Plättchenaktivierung in Bereichen von hoher Scherspannung;
• 3) Bluttrauma oder Hämolyse, die auftreten können, wenn Blut mechanische Lager oder fremde Flächen berührt, und wenn Blut höheren Scherbedingungen als normal durch die Rotationskomponenten ausgesetzt ist;
• 4) Perkutane Leitungen, die für den Motor und Lagersteuersysteme und andere Unterstützungslinien erforderlich sind;
• 5) die Pumpengeometrie (Größe, Form und Gewicht) zur leichten Implantation, Mobilität des Patienten und zum Verhindern von Rissen im Transplantat;
• 6) hohe Kosten der Pumpe und
• 7) hoher Strombedarf, der eine große Stromquelle erfordert.

Despite the tremendous need for an effective chamber assist pump, prior MCS devices have not been completely successful due to several limiting factors. The particular concerns and design limitations of current blood pump designs include:

• 1) component durability and service life;
• 2) blood clotting or thrombosis due to flow congestion in the pump in secondary flow areas, wash openings, recirculation areas, and platelet activation in high shear stress areas;
• 3) blood trauma or hemolysis that can occur when blood contacts mechanical bearings or foreign surfaces, and when blood is exposed to higher shear conditions than normal by the rotational components;
• 4) percutaneous leads required for the engine and bearing control systems and other support lines;
• 5) the pump geometry (size, shape and weight) for easy implantation, mobility of the patient and to prevent tears in the graft;
• 6) high cost of the pump and
• 7) high power consumption, which requires a large power source.

Many blood pump designs had a pulsating configuration. This requires the explantation (removal) of the diseased native heart and replacement by the pulsatile mechanical blood pump. However, these pulsating pumps have proven to be very complicated mechanically, they are relatively large and have relatively short mechanical life. An alternative design using a rotary pump results in the application of the mechanical heart as a ventricle assist device that does not require explantation of the native heart. The rotary pumps have a smaller size and better mechanical reliability. Such a pump supports the heart of a patient by pumping extra blood in parallel with a diseased heart. The rotary blood pump may be connected to the patient's heart in a left ventricle assist configuration, a right ventricle assist configuration or a bicammer assist configuration. For example, if a left ventricle configuration is used, the rotary pump is connected to receive the flow from the left ventricle of the heart and return it to the aorta. Generally, the rotary pump includes a stator (housing) having an inlet and an outlet opening, an impeller positioned in the stator, and Impeller has a motor for rotating the pump and a suspension system to produce the pumped bloodstream. The blood enters through the inlet of the stator and is pumped by the rotating impeller through the housing to the outlet and back into the circulatory system of the patient.

It are two primary Configurations for Rotary blood pump configurations be used: axial flow and centrifugal flow. In the axial flow configuration the pump configuration is similar a cylinder with an inlet flow opening an end and an outlet flow opening the other end. The centrifugal flow configuration is similar to one circular Disc with an inlet flow opening in the center of one side of the disc aligned perpendicular to the Plane of the disc, and a tangential outlet flow opening the edge of the disc, in the plane of the disc.

studies have many problems with low rotational bloodstream, in both axial and centrifugal flow blood pumps including those which have a magnetic suspension. One of these problems is Stagnation with the result of thrombosis or coagulation. If the flow may have a range lower or zero speed, it may cause Thrombosis or coagulation come where blood attaches to the pump structure staying. Such low or zero speed ranges usually become in secondary Bloodstream found in the pump. When the thrombosis builds up, can be an area or a large one Stop clots and embolize in the bloodstream. If that Clot closes a blood vessel that can lead to the brain or any other sensitive area develop very serious conditions, such as a profound organ dysfunction like an epileptic seizure or a severe brain damage. One another problem is hemolysis, where the blood is higher Shearing stresses in the rotary pump is usually exposed near the impeller wings, moving at a relatively high speed and the at the circulating blood directly or with delay causing damage can. When the impeller forces on the blood, can Areas of turbulence or radiation formation in poorly constructed Devices occur.

Lots Rotary blood pump designs have been created to do this Bearing problems with their use as chamber support devices to solve. It is desirable a storage system with an expected service life of 10 to 20 Years, if possible, to have. Generally, these bearings fall into three categories: mechanical, hydrodynamic or magnetic bearings.

Some Rotary blood pumps have mechanical or hydrodynamic bearings or hydrodynamic suspensions. See, for example, U.S. Patent Nos. 6,609,883 and 6,638,011. Other Rotary blood pumps have a combination of hydrodynamic Bearings and permanent magnet bearings. For example, see US patents No. 5,695,471; 6,234,772; 6,638,083 and 6,688,861.

One Type of rotary blood pumps has mechanical bearings, which is a lubricant flushing or Cleaning with an external grease reservoir for lubrication storage and removal of heat require. See, for example, U.S. Patent Nos. 4,944,722 and 4,846,152. There are many disadvantages to this type of pump. The percutaneous feed and delivery of the lubricant cleaning fluid degrades the quality of life of the patient and forms a high potential for Infections. Seals for the external lubricant is notoriously susceptible to wear and fluid attack, which lead to leakage can and is followed by a subsequent epileptic seizure of the patient. Furthermore is an extra Pump required to deliver the lubricant to the bearing, and if it fails, sticks the lubricated bearing. Finally, have mechanical bearings a limited wear time, usually of a few years, and must be replaced as a result of bearing wear.

It gives axial flow rotary pumps with ceramic bearings that are currently being clinically tested. It is not known how long these bearings will last, but the expected usage times based on other applications are in the range of 2 to 5 years. There are also reported cases of thromboembolism in some patients. This occurred while the patients were anticoagulating were.

Rotary pumps have been developed with magnetic suspension to eliminate the previous requirement for external cleaning of lubricant or ceramic mechanical bearings. The use of a magnetically suspended impeller eliminates the direct contact between rotating and stationary surfaces as they exist in mechanical bearings. See, for example, U.S. Patent Nos. 5,326,344 and 4,688,998. The expected service lives of magnetic suspension systems are in the range of 10 to 20 years. This type of magnetic suspension rotary pump generally includes an impeller within a housing, the impeller being formed by a combination of permanent mag Neten and is stabilized within the housing, which are positioned in the impeller and the stator, and with an electromagnet, which is positioned within the stator. The impeller is rotated by a ferromagnetic motor consisting of a stator ring secured within the housing and electromagnetic windings wound around two diametrically opposed projections. The ferromagnetic impeller and the electromagnetic coils are positioned symmetrically with respect to the rotational axis of the pump impeller.

at magnetically suspended Rotary blood pumps serve the gap between the stator and the impeller the competing purposes of allowing the blood to flow through it as well to support the magnetic levitation and the rotation of the impeller. Regarding the bloodstream, it is desirable that the radial gap for An effective blood pumping is great, but effective magnetic suspension it is desirable that the radial gap is small. Because of the competing split requirements contain other conventional ones Pumps frequently a primary Fluid flow region and a secondary one magnetic gap. The area of the primary fluid flow radial gap is big enough a hydrodynamically effective flow without traumatic or turbulent fluid flow permit. The secondary magnetic radial gap allows Fluid through and is small enough to be an effective magnetic Floating the central hub, which is either the stator or the impeller can be. Examples of pumps with a blood flow path, which is both a primary as well as a secondary bloodstream contains can in U.S. Patent Nos. 6,071,093; 6,015,272; 6,244,835 and 6,447,266 being found.

Some conventional Blood pumps contain a permanent magnet thrust bearing, which is a pressure plate relative huge Diameter with permanent magnets with an alternating polar Configuration both on the stator and the rotor components of the Pump has, but are arranged in a radial configuration. It is believed that the size Pressure disc obstructs the bloodstream and creates a curved bloodstream, which is from a straight line through the pump. The conventional ones Pumps, however, contain configurations of radially polarized Permanent magnets.

Various Scanning techniques have been used to determine the rotor position of a active electromagnetic bearing to locate and control. These techniques close Eddy current or inductive or capacitive and laser sensors, the usual used in industrial applications of electromagnetic bearings become. Laser sensors can can not be used because they can not "see through" the opaque blood and inductive sensors require a magnetic source in the Stator and a magnetic target in the rotor as well as a maglev, which extends between the stator and the rotor to the rotor position to capture. capacitance probes require an electrical path between the stator and the rotor, which is generally not possible with blood pumps.

It There are several problems related to using one Eddy current or inductive sensor types in the gap between the Stator and the rotor in a miniature implantable blood pump. For example, support These types of sensors are on a clear, magnetically non-disabled path between the sensor "surface" and the rotor surface means that the sensor body inside the stator housing with its "surface" perpendicular to the rotor area must be placed. It is desirable too prevent any Part of the body of the sensor is placed within the fluid flow (blood) of the pump, but still near the magnetic rotor target. A problem with these Types of sensors is the possible Contamination of the bloodstream, if the soft iron or another non-biocompatible sensor surface exposed to the blood. Generally this is solved with the use of a Sort of a thin biocompatible Materials that the sensor surface and the goal is covered, to avoid blood contact. Other problems are space constraints, the for the Sensor are required, and the energy budget for such Sensors is required.

Also included such rotary blood pumps a motor to turn the impeller which in turn causes the required blood flow. It is desirable that the Engine has a very long usage time, and faultless during one Period of time to one or more decades of its application is running. Some Pumps use brushless DC motors for this purpose, which is a compact and effective construction without to brush to have. There is no brush wear, So that the expected service life such a pump is very long. A target With such pumps it is necessary to ensure that the engine is in the necessary Direction starts, so that the impeller pumps. The correct starting direction Rotation can be an important feature.

As mentioned above, magnetic suspensions often have at least one active electromagnet cal control bearing axis. in a radial bearing configuration, the electromagnet may consist of a set of soft iron magnetic poles in a configuration in the stator which are circumferentially lined around the rotor with a free gap and exert centering forces acting on a soft iron placed in the rotor. The current in the coils must be precisely controlled to achieve the desired centering purpose, allowing the rotor to operate precisely in free space. The current in the coils is set by an automatic control system. In order to carry out the automatic force centering control method, there must be a sensor which detects the position or displacement of the magnetic rotor target, an electronic means of active control to adjust the control currents in the stator windings, such as electronic monitoring panels and power amplifiers to provide the current ,

The Control method for determining the winding currents in the magnetic bearing of an active warehouse a way of specifying how to obtain the winding currents are. Active magnetic bearings can consist of magnetic soft iron materials that have a significant Have limitation in that they the magnetic saturation at a certain level, typically at about 1 Tesla. The active tax procedure should consider this circumstance pull. Furthermore is the force exerted by an active magnetic bearing a non-linear function of both the magnetic gap as well of the current in the windings.

The most common Method of treatment of magnetic material saturation and non-linearity is that of bias linearization, where a stationary bias current is given to each the winding currents which imposes a magnetic flux in the magnetic soft iron poles generated by about half of the magnetic saturation flux. Then, a perturbation current is applied to cause changes in the winding currents. with the poles on one side of the rotor opposite the other side are connected. When these differences are connected because of higher winding currents higher with the poles on one side magnetic forces at the magnetic rotor target compared to the other side generate where smaller winding currents connected to the poles generate smaller magnetic forces on the other side of the rotor, which act on the magnetic rotor target. The rotor has one Netting force used to close this in the free gap Center. The use of the bias linearization method, The above-described one has a major disadvantage in that it has a relatively high power consumption in the windings and that a great heat generated in the windings, which is the active magnetic bearing component can heat the rotary blood pump. There are also limits in this type of magnetization linearization in that the full Use of the magnetic force capacity of the active magnetic Camp is prevented.

One Another problem regarding an exactly centered operation of the Rotary pump impeller is the imbalance in the rotor. rotating Devices are subject to a mechanical imbalance since it is difficult to make a perfectly balanced rotor. Furthermore can while operation within the patient over a long period of additional changes in the imbalance occur due to a displacement of the rotor, Rubbing of the rotor, adherence of blood or blood products to the impeller surfaces and because of other factors.

There As the patient goes through different levels of activity, non-centering forces work the rotor change. When the patient is active, for example walking or climbing from stairs, need the magnetic bias current levels in the active magnetic Be big, around big ones magnetic centering forces to create. However, if the patient is sitting or sleeping peacefully, it is a much smaller magnetic bearing centering force is required. higher Lead bias level to a higher power consumption and to a greater heat.

Besides, they are Zentrifugalströmungs rotary blood pumps with magnetic suspension been proposed. See, for example, U.S. Patent Nos. 6,074,180; 6,595,762 and 6,394,769. However, it has been found that centrifugal flow pumps not easily implanted in an animal or in humans, since the inflow and outflow channels relative to 90 ° are arranged to each other and in separate planes. Also require such centrifugal pumps meander secondary blood flow paths as part of the design.

Summary the invention

It it has been recognized that it would be beneficial a reliable one The ventricular assist device to develop for permanent implantation in humans. Besides that is it has been recognized that it would be beneficial to develop a blood pump to reduce blood clotting, secondary flow paths too avoid and provide an open, single-lane bloodstream. Besides that is it has been recognized that it would be beneficial a blood pump with a reduced size, a long life and low power consumption. It has also been recognized that it would be beneficial a blood pump with a hybrid permanent magnet and an electromagnetic To develop a set of permanent magnets to manage larger forces (axial or pressure) and an electromagnet to manage smaller forces (radially). Besides that is it has been recognized that it would be beneficial a blood pump with an optimal configuration of permanent and develop electromagnetic bearings to provide the best blood pump flow performance to achieve. Furthermore it has been recognized that it would be beneficial a blood pump with a correct direction of rotation develop. Furthermore It has been recognized that it is beneficial would be, to develop a blood pump with control methods that use less power consume and develop less heat to an active magnetic To facilitate bearing component.

The The invention provides a blood pump with an impeller rotatable arranged and magnetically within a cavity of a stator through a variety of magnetic bearings (passive permanent and active electromagnetic), including one axial bearing to hold the bearing axially in the cavity. The axial bearing contains nearby impeller magnets and nearby stator magnets, respectively with axially aligned polarities and reversed polarities in terms of the neighboring magnets. A motor contains impeller magnets on the impeller and windings / magnetic poles connected to the stator. Radial permanent magnet bearings and electromagnetic bearings can also be included. The magnetic bearings and the engine have Stator magnets or windings / magnetic poles radially across the Fluid channel of the associated Impeller magnets are arranged to form an annular gap, the is positioned radially between the impeller and stator, and radially positioned between each of the plurality of magnetic bearings is to create a straight through passageway without secondary flow paths to accomplish.

Further Features and advantages of the invention are apparent from the following detailed Description, in conjunction with the accompanying drawings taken together by way of examples features of the invention represent.

Short description the drawings

1 Fig. 15 is a longitudinal perspective cross-sectional view of a blood pump according to an embodiment of the present invention;

2 is a perspective view of the blood pump of 1 ;

3 is a longitudinal perspective cross-sectional view of a stator of the blood pump of 1 ;

4 is a partially broken away perspective view of an impeller of the blood pump of 1 ;

5 is a side view of the impeller of 4 , shown with inlet vanes and diffuser vanes of the stator, and showing inlet regions, impeller vanes and diffuser regions.

6 is a schematic cross-sectional view of the blood pump of 1 and shows a magnetic levitation and rotation system;

7 is a partial schematic side view of the blood pump of 1 ;

8th is a schematic end view of the blood pump of 1 and shows an active electromagnet table storage;

9 is a partial end view of a conventional active bearing;

10a is a partial end view of the blood pump 1 and shows a combination of inlet vanes and active electromagnetic bearing poles;

10c -E are partial perspective views of the blood pump 1 and show a method of assembling the active electromagnetic bearing poles with the inducing blades;

10f -H are partial perspective views and end views of the blood pump of the 1 and show another method of assembling the active electromagnetic bearing poles with the inducing blades;

11 FIG. 12 is a partial schematic view of a unidirectional motor of the blood pump of FIG 1 according to one aspect of the present invention;

12a and b are schematic end views and side views of a sensor field of the blood pump of FIG 1 ;

12c is a schematic side view of another sensor field of the blood pump of 1 ;

13 is a schematic side view of the blood pump 1 and shows inducer, impeller, and diffuser areas;

14a and b are end views of the inlet wings of the blood pump 1 ;

15a and b are side views and end views of the diffuser wings of the blood pump 1 ;

16a is a graph of oscillation over time from the blood pump's impeller 1 without using a bumpless transfer algorithm and

17 is a schematic diagram of a bumpless transfer algorithm.

It Reference is now made to the exemplary embodiments which are shown in the drawings, and a special language is used to describe this. Nevertheless, it is understood that this no restriction the scope of the invention is intended.

Detailed description of preferred and alternative exemplary embodiments

As in the 1 to 8th and 10a to 14b 10, an exemplary embodiment of a compact axial flow rotary blood pump, generally designated 10, is shown with a magnetic suspension and rotation system. Such a pump may be used as a ventricular assist device (VAD) for those suffering from congestive heart failure (CHF). The pump 10 advantageously includes a magnetic levitation and rotation system that reduces size, has a long service life, and reduces power consumption requirements. Besides, the pump has 10 advantageously an unhindered one-lane blood design without a secondary bloodstream for any magnetic suspension distances, in contrast to previous magnetic suspension systems which require both primary and secondary bloodstreams. This minimizes the pump 10 advantageously, the occurrence of flow arrest, which can lead to thrombosis as well as hemolysis, by avoiding secondary flow paths.

• 1) ein passives axial zentrierendes, Permanentmagnet-Drucklager;
• 2) ein passives, radial zentrierendes Permanentmagnetlager und
• 3) ein aktives elektromagnetisches Radiallager, das in näheren Einzelheiten unten beschrieben wird.

The magnetic suspension system used

• 1) a passive axially centering, permanent magnet thrust bearing;
• 2) a passive, radially centering permanent magnet bearing and
• 3) an active electromagnetic radial bearing, which will be described in more detail below.

In this way, power consumption is minimized by using only one active electromagnetic bearing that consumes power, and the other bearings are permanent bearings that do not consume power. In addition, permanent magnets do not heat the pump, they do not require wires or any Power supply or electrical controls. In addition, this magnetic suspension contributes to a single bloodstream without the need for any secondary bloodstream, which also minimizes power consumption, the number of wires, power supplies, and electronic control devices.

The pump 10 contains a pump rotor or impeller 14 that is magnetic in an axial flow pump stator or housing 18 is suspended. The stator 18 contains a cavity 22 passing axially between an inlet 26 and an outlet 28 extends. The cavity 22 of the stator 18 can be a continuous and sealed deposit 29 have stator components from the impeller and the fluid channel, as described in more detail below. Similarly, the impeller may have a liner that separates impeller components from the fluid channel. The impeller 14 is rotatable in the cavity 22 or the deposit 29 arranged and hung magnetically in it. The impeller 14 has a rotation axis 30 around which the impeller rotates. There is also a gap or fluid passage 32 between the impeller 14 and the stator 18 formed, through which the blood flows. Thus, the blood enters through the inlet 26 a, flows around the impeller 14 through the fluid channel 32 and from the outlet 28 out, whereby a single-lane bloodstream is formed. The cavity 22 and the stator 18 can also move along the axis of rotation 30 extend. In addition, the inlet 26 and the outlet 28 be aligned longitudinally or axially. The cavity 22 and the impeller 14 can have elongated, substantially cylindrical shapes.

The cavity 22 or the pump 10 contain an introduction area 32a , an impeller wing area 32b and a diffuser area 32 as in the 5 and 12 is shown. The lead-in area 32a reduces a tangential flow component or straightens the flow into the pump. The impeller wing area 32b gives kinetic rotational energy to the fluid. The diffuser area 32c converts the kinetic energy into static pressure.

The lead-in area 32a is near the inlet 32 arranged and contains an introduction device with one or more introduction wings 34 , The introduction wings 34 are on the stator 18 at the inlet 26 of the cavity 22 arranged and extending in a radially inward direction. In addition, the inlet wings 34 essentially axially on the axis of rotation 30 aligned. So that's the inlet wings 34 designed to displace the blood into an axial flow (as opposed to a radial or circumferential flow when entering the pump) and prevent the impeller from causing a circular flow upstream of the pump Einleiteinrichtung have six wings that surround the axis of rotation, as in the 3 . 5 . 10a . 13a and 13b is shown. The wings of the introducer extend into the cavity without tensing the cavity. The deposit 29 Can over and around the wings 34 be formed of the introduction. It goes without saying that more or less wings 34 the introduction device can be provided. It is also emphasized that the wings of the introducer may be curved or helical. The diffuser area 32c is near the outlet 28 arranged and contains a diffuser with one or more diffuser wings 36 , The diffuser wings 36 are at the stator near the outlet 28 of the cavity 22 arranged and extend inwardly, without overstretching the cavity. The diffuser wings 36 are substantially helical with respect to the axis of rotation 30 shaped and / or arranged. Thus, the diffuser wings 36 designed to straighten the flow as it exits the pump. The diffuser can have three diffuser wings 36 included, as in the 3 and 5 shown, or six diffuser wings 36b as in the 14a and b is shown. It is understood that more or less diffuser blades can be provided. The diffuser wings extend from the insert 29 ,

Of the Diffuser area converts fluid velocities or kinetic energy owing to the special shape of the diffuser wings and the diffuser channel in print. In one aspect, the downstream diameter of the diffuser channel be a little bit bigger as the upstream one Diameter at an inlet too the diffuser channel. The diffuser channel can have a divergence angle usually is less than 5 °, around a flow separation to prevent. The expansion area in the channel has a smooth Increase in the cross-sectional area, reducing the axial velocity the bloodstream is reduced when it leaves the pump.

Stationary vanes attached to the diffusion jacket have a configuration that helps to eliminate the tangential component of the absolute velocity of the flow. The reduction in speed also helps to increase the pressure increase of the pump and the hydraulic efficiency. The curvature of the stationary vanes is selected so that the flow enters the diffuser vanes with minimal hydraulic loss and leaves the pump axially. Determination of diffuser performance is given by the recovery factor, which is a function of inlet flow velocities and the outlet of the diffuser, and the pressure loss inside the diffuser due to the resistance. The ideal case of recovering the kinetic energy of the flow entering the diffuser is represented by a unit recovery factor. Maximum values for the recovery factor of 0.7 to 0.8 indicate an optimum combination between the diameter ratio and the length of the channel. The recovery factor decreases rapidly at large divergence angles (> 10 °) due to boundary layer separation.

The current Diffuserflügelgeometrie is designed so that the hydraulic losses are minimized at the design point. Therefore The front edge of the diffuser wing is perfectly aligned with the direction the velocity vector of the incoming bloodstream. In off-design operating conditions, there is a mismatch between the velocity vectors of the incoming fluid and the front edge angle of stationary wings, resulting in additional Losses leads. For the Operating range of the present invention are the hydraulic Losses kept at an acceptable level thereby increasing the diffuser recovery factor is respected.

The impeller wing area 32b is between the inlet area and the diffuser area 32a and c arranged. The impeller 14 can have an elongated body with one or more impellers or blades 38 extending radially therefrom. For example, the impeller may have four impeller blades as shown. It is understood, of course, that the impeller may be provided with more or less impeller blades. The impeller blades 38 may have a helical shape and / or arrangement to move the fluid or blood through the pump as the impeller rotates. The impeller blades 38 and the diffuser wings 36 have opposite orientations so that the impeller blades 38 create a circular flow in one direction and the diffuser wings direct the flow.

The magnetic suspension system includes a plurality of magnetic bearings or sets of bearings. Each bearing includes one or more impeller magnets connected to the impeller and one or more corresponding stator magnets connected to the stator. The impeller magnets and stator magnets are across the fluid channel 32 arranged one another and substantially radially with respect to the axis of rotation 30 aligned. The impeller and stator magnets may be annular magnets or ring magnets, with the stator magnets concentrically surrounding or rewriting the impeller magnets. The fluid channel 32 may be substantially annular and extend between the annular magnets. In addition, the magnetic bearings may have a plurality or series of axially aligned abutting magnets on the impeller and the stator, as described below.

It has been recognized that in normal operation, the largest force to be controlled is the axial force due to the relatively large change in pressure over the length of the pump. For example, the pressure change across the pump may be as great as 150 mm / Hg. The magnetic suspension system includes an axial or thrust bearing 40 to move the impeller axially in the cavity 22 to store. The axial bearing 40 includes a plurality of permanent magnets in an axially oriented, inverted polarity configuration to axially center the pump impeller. The axial bearing 40 can be characterized as a field of adjacent bearing sets that are axial with respect to the axis of rotation 30 lined up with a field of impeller magnets 42 and a field of stator magnets 44 , For example, three axial bearing sets may be adjacent to each other or adjacent. Each bearing set includes an impeller magnet on the impeller and a stator magnet on the stator. The impeller and stator magnets are radially across the fluid channel 32 aligned. Thus, a plurality of adjacent impeller magnets 42a to c axially disposed on the impeller, and a plurality of adjacent stator magnets 44a to c is arranged axially on the stator. Adjacent impeller magnets and adjacent stator magnets have axially aligned polarities and reverse polarities with respect to the adjacent magnets. Thus, the axially aligned polarity of one impeller magnet is reversed to an adjacent impeller magnet. Similarly, the axially oriented polarity of a stator magnet is inversely related to an adjacent stator magnet. In addition, the impeller and stator magnets of each bearing set have a reverse polarity to each other, so that magnets of the axial bearing on opposite sides of the fluid channel have opposite polarity. Thus, the axial polarity of an impeller magnet is inversely related to a corresponding stator magnet across the fluid channel.

The axial bearing 40 can be constructed by multiple axially polarized individual components or rings. One ring is placed on the impeller and another on the stator, forming a fluid (blood) gap. The 3 . 4 . 6 and 7 show the geometry of pairs of magnetic rings that form a thrust bearing. The polarization is different, as in 7 is shown, wherein the polarities are reversed. The north pole on one side of the fluid column is arranged transversely from the south pole on the other side of the fluid gap net. The polarities are reversed at the other end of the rings. This configuration produces positive axial stiffness and negative radial stiffness.

A single pair of permanent magnet rings may not provide sufficient axial rigidity. The axial stiffness is greatly enhanced by the construction of a thrust bearing composed of several rings of opposite polarity, as in FIG 7 shown for three rings. This combination of rings greatly increases the axial stiffness of the axial bearing. A different number of rings can be used. The rings may or may not have the same axial length.

The Permanent magnet configuration fixed on the stator and that on the impeller fixed permanent magnet configuration have a straight through free gap, so they take up the only continuous axial bloodstream, without any axial obstacle. The axial permanent magnet does not need any Energy to center the rotor axially, resulting in a reduction of electricity consumption. The configuration of this pump, this straight through flow path is the axially polarized with changing poles Permanent magnet configuration with magnets that are axially on the stator and the rotor without a big one Pressure plate are aligned.

The magnetic suspension system also includes a radial permanent magnet bearing 50 to move the impeller radially in the cavity 22 to store. The axial bearing 40 may be characterized as at least one pair of adjacent sets of bearings that are axial with respect to the axis of rotation 30 are positioned. For example, two axial bearing sets may be provided adjacent to each other or adjacent to each other. Each bearing set includes an impeller magnet on the impeller and a stator magnet on the stator. The impeller and stator magnets are radially across the fluid channel 32 aligned. Thus, several adjacent impeller magnets 52a and b axially on the impeller, and a plurality of adjacent stator magnets 54a and b are axially disposed on the stator. Adjacent impeller magnets and adjacent stator magnets have axially aligned polarities and reversed polarities with respect to the adjacent magnets, similar to what has been described above with respect to the axial bearing. In addition, the impeller and stator magnets of each bearing set have the same polarity to each other, so that magnets of the radial bearing on opposite sides of the fluid channel have the same polarity, opposite to what is described above with respect to the axial bearing.

The radial bearing 50 can be constructed of axially polarized permanent magnet rings. The rings can be the same length. Alternatively, the rings may have different lengths. A set of rings is placed on the impeller, and a set of rings on the stator, and they form a fluid (blood) gap. (The axial polarities are the same as indicated by the arrows with the north pole at the head of the arrow and the south pole at the end of the arrow). The north poles of the rotor and the stator are disposed on opposite sides of the fluid gap, while the south poles of the rotor and the stator are disposed on opposite sides of the fluid gap. This creates a positive stiffness so that the rotor and stator have equal and opposite forces acting to prevent them from moving closer together. However, this configuration produces a negative axial stiffness of twice the positive radial stiffness that must be compensated for in other bearing components.

One single pair of magnetic rings can not produce enough rigidity to keep the wheel centered. A radial bearing with higher rigidity can be constructed by placing several rings of equal polarity next to each other be combined. This configuration greatly improves the stiffness values over the number, by multiplying the stiffness of a ring by the number of the rings is obtained. Another number of rings can be used become. The rings can the same axial length or not.

The axial and radial bearings 40 and 50 use a new permanent magnet pole configuration with compact magnetic rings of high magnetic strength with alternating axially polarized polarity. This configuration allows the axial suspension of the impeller about the radial suspension of the impeller at one end without any external energy. In addition, the permanent bearings require no feedback control or position sensors for their operation. These bearing configurations can be placed in the impeller and the stator in such a manner that they do not enter the blood flow path, thereby allowing a straight flow through the blood flow path in the rotary blood pump.

The magnetic suspension system also includes a radial electromagnetic bearing 60 to move the impeller radially in the cavity 22 to store. The radial electromagnetic bearing 50 can be a 6-pole, actively controlled solenoid with impeller magnet 62 that is in the wheel 14 are arranged, and windings / magnetic poles (windings 64 and poles 66 ) be with the stator 18 are connected. The wheel magnet 62 and windings / magnetic poles are radially across the fluid channel 32 positioned one another. The stator can have a series of radial stator poles 66 which are formed of a non-permanent magnet material, such as silicon iron, through the windings 64 activated and driven, which are wound around the arms, as in 8th and similar materials form a cylindrical configuration on the impeller. In one aspect, the conduit is formed in such a manner that the currents produce a magnetic flux producing a north pole in one of the electromagnetic poles of a pair, and the other produces a south pole in the other portion of the pair. In the embodiment shown, there are in the six-pole electromagnet of 8th three pairs of poles. A smaller number or greater number of electromagnetic poles may be used to reduce or increase the size of the bearing, as needed, with an associated reduction or increase in the force capacity of the bearing.

In one aspect, the active magnetic bearing may include: position sensors, magnetic actuators, and a source that supplies the currents through each of the magnetic actuators. Regarding 9 is an example of a typical conventional radially active magnetic bearing construction shown with a radial stator 70 with windings 72 from the actuators, and a rotor 74 whose radial position is determined by the magnitude of the flux or composite force generated in each of the actuators. The stator is generally a single monolithic piece of "soft" magnetic material, such as silicon iron (SiFe), which provides a low resistance path for the magnetic fields generated by actuators Generally, this radial stator assembly has a means for attaching this structure to the housing such as four through holes (one in each quadrant) provided for the axial attachment of the stator to the housing The conventional method of assembling a radially active magnetic bearing involves "pushing" each of the radial windings 72 on every "arm" of the stator 70 and then inserting and securing the stator in the respective housing. The purpose of the conventional active magnetic bearing is to generate the force over the magnetic flux generated in this structure around the rotor 74 in its centered position to position and hold.

In one aspect, the pump of the present invention may include the introducer and inducer vanes 34 with the active electromagnetic 60 combine. The poles 66 of the active bearing can be in the inductor wing 34 extend or be combined with them. With reference to the 10a and b is the lead-in area of the stator 18 and part of the active electromagnetic bearing 60 shown by the active electromagnetic bearing 60 and the inlet wings 34 are installed together. The electromagnetic bearing poles 66 may be placed in the pump inducer, where the poles are covered by solid material in the form of a fluid blade, to enhance and enhance the pump inlet flow. Thus, the bearing poles 66 in the inlet wings 34 to be ordered. This dual use of pole / wing configuration results in a compact, multi-use design for these pump components. This dual use also makes efficient use of the associated space and volume. Thus, the active magnetic stator and the initiator are combined as well as their two functions into a composite dual application device.

The introducing means may comprise a non-magnetic material such as titanium, which forms an unobstructed magnetic path for the magnetic flux generated in the stator while also providing a means for sealing the fluid (blood) flowing through the interior of the introducing means and thus is not contaminated by the magnetic stator components. This form of protective confinement is called a lining or "pot" 29 designated. It would be difficult to insert a rigid, monolithic, active magnetic bearing stator structure into the monolithic form of the introducer. Therefore, a combined lead-in and an active magnetic bearing stator are assembled as in FIGS 10c to 10e is shown. Regarding 10c is a sub-arrangement 80 an active magnetic bearing arm and winding with a stator back iron 82 shown. A single stator arm 84 with a T-shape or cross-section contains opposite "dovetail" faces at each end of the horizontal section of the arm. These dovetail faces fit into inverted or mating dovetail slots 85 in the stator back iron 82 , A winding 86 fits around the perimeter of the vertical portion of the "T-shape" and is shown coincident with the bottom of the horizontal portion of the "T". Regarding 10d are six sub-assemblies 80 shown in bags 88 in the introducer or the pot 29 are used. Regarding 10e are the swallow tails of the sub-assemblies 80 axially into the dovetail slots 85 of the iron 82 used.

With reference to the 10f to h, another approach of assembling a combined active magnetic bearing and introducer is shown. An integral or monolithic arm and back iron 90 contains an arm section 92 and a 60 ° arc section 94 of the finished Rückei sens 96 , A winding 86 fits around a circumference of the arm section. A 60 ° arc is used as an example because the inducer can have six wings. A different number of arms or wings may be used, including unequal ground segments. Once again, the arm section becomes 92 in pockets of the pot 29 used.

As shown, multiple magnetic bearings may be connected to the radial electromagnetic bearing 60 near the inlet 26 be positioned to the fluid channel; the radial permanent magnet bearing 50 is near the outlet 28 the fluid channel arranged; and the axial permanent magnet bearing 40 is disposed between the radial electromagnetic bearing and the radial permanent magnet bearing. It is understood that other configurations are possible. For example, the radial electromagnetic bearing could be positioned near the outlet while the radial permanent magnet bearing could be positioned near the inlet.

In addition, the pump contains 10 an engine 150 with impeller magnets 154 on the impeller 14 and windings / magnetic poles (windings 158 and poles 182 ) are with the stator 18 connected. For example, the motor may be a brushless DC motor, without wear-resistant brushes and with a compact energy efficient construction. In addition, the motor may have a staggered stator pole structure so that it can only start in one direction, the correct or desired direction for pumping the impeller.

In addition, the engine may be a unidirectional engine. The motor may have a brushless DC motor configuration with only one start in the required direction of movement with an associated impeller flow design and a self-adjusting control device. Regarding 11 the motor can be staggered stator poles 70 which extend obliquely to a magnetic gap between a leading edge of the pole 172 in a desired direction of rotation, which is smaller than another magnetic gap between a rear pole edge 174 in an opposite direction of rotation. The motor may have a six-pole configuration with oblique poles, three-phase stator winding and a four-segment permanent magnet target in the rotor. In addition, there are no brushes and the motor has a compact, energy-efficient construction. In addition, the motor has a special staggered stator pole structure so that it can only start in one direction - the right direction for pumping the impeller. The correct starting direction of rotation is caused by an oblique pole design. The motor pole construction has a slope so that the magnetic gap distance of the leading motor pole edge in the direction of rotation is smaller than the magnetic gap distance of the rear edge of the motor pole in the opposite direction of rotation. The engine may also have a self-adjusting controller with a microprocessor control inverter. Unlike previous rotary blood pumps that have an angular position sensor, the present motor and controller do not require a sensor to determine the commutation or rotational speed. The self-adjusting controller uses auto-parameter tuning at startup, in overload rotational situations, high temperature protection, and active rotational speed control. This inverter ensures high performance while reducing the generation of radio frequency noise.

The magnetic suspension system described above, together with the rotation system or motor, provides a significant improvement over previous magnetic suspension systems that require primary and secondary bloodstreams. The magnetic suspension system allows for unrestrained, one-lane blood design without a secondary blood path for magnetic suspension distances. Thus, the pump minimizes 10 the occurrence of flow arrest that can lead to thrombosis and hemodialysis by avoiding secondary fluid pathways.

The only, unimpaired bloodstream, and the fluid channel are through an annular Gap limited radially between the magnetic bearings and the engine is positioned. All magnetic bearings have stator magnets, the radially across the fluid channel of the associated Impeller magnets are arranged. The engine has the same way Windings / magnetic poles radially across the fluid channel of the associated Impeller magnets are arranged. This is the annular gap positioned radially between the impeller and the stator, and radially between all of the multiple magnetic bearings. The fluid channel or the only, unimpaired bloodstream extends through the Stator and around the impeller, between the permanent magnet and the electromagnetic bearings. Thus, the impeller is magnetic within suspended from the cavity of the stator, without a structure that spans the cavity of the stator.

The pump may be controlled and energized by a control box inserted into or out of the body and able to direct the coil currents to the motor and the active bearing. The control box may include control electronics or computers as well as a power source. The power source may be a long life battery located on the body and a small internal battery in the control box for a short term backup use. When the control box is implanted, the long-term battery current can be delivered through the intact skin either by a transcutaneous lead or by high-frequency transmission (telemetry). When the control box is externally carried, the long-term battery power can be supplied through a line.

Power amplifiers can be used be based on the electromagnetic bearing windings of input signals from a process panel with winding control signals to press. The winding control panels can programmed with an automatic feedback control algorithm be around the pump impeller at or near the center of the free fluid gap to hold it when there are different fluid gravity or other distraction forces is exposed. The automatic feedback control algorithm can use the radial coordinate position of the rotor, in two coordinate directions, relative to the stator or pump housing, the axial coordinate position the impeller relative to the pump housing as a feedback signal. These Impeller position signals can provided by sensors such as Hall sensors, or stray current sensors become. The feedback signal may include other inputs, such as pump accelerations in one, two or three directions, by an accelerometer be measured.

With reference to the 12a to c can radial and axial positions through Hall sensors 200 are detected, which include very compact, electronically operated with low power sensitive magnetic field sensors. Several of these sensors can be positioned in the pump housing in multiple radial positions and at least in two axial positions. At least some of the Hall effect sensors 200 can be placed where the fluid gap is oblique, so that the magnetic field varies with radial and axial position changes, so that both are calculated by a simple algorithm and thus the position changes in both directions are measured. The Hall effect sensors can be powered by the same long-term (or short-term) battery system as the electromagnetic bearing.

permanent magnets 204 can be placed in the impeller in positions near the locations of the Hall effect sensors in the stator or pump housing. The permanent magnets 204 cause the changes in the magnetic field signal as the rotor moves radially or axially, which the Hall effect sensor calculates. These Hall effect sensors detect the displacement of the impeller relative to the sensor in both the radial and axial directions and provide some or all of the feedback control signal used for the electromagnetic bearing and the physiologic controller. In addition, they generate signals monitored by the control unit to generate an alarm, or other suitable methods to alert the patient or medical personnel to the existence of potential problems, such as wheel rubbing. Signals may be used to monitor the pump control unit or be delivered to an external monitoring alarm unit.

The Using Hall effect sensors avoids the problem of room conditions for the Sensors, for the energy balance for the sensors required, arranging sensor surfaces within the stator housing, the contamination of the bloodstream and thrombosis and blood clotting. The Hall effect sensors use the Hall "effect" to measure the field that is magnetic Device surrounds. Linear versions of these devices can be exact the magnetic field intensity which surrounds a magnetic device. Four Hall Effect Sensors can be arranged in an orthogonal field, two each on the X and Y axis, then by differentiating the pairs of axes get the position of the magnet within these devices can be. An advantage of using a Hall effect sensor in this miniature pump is that the magnetic flux emanating from the magnet, easily through the contamination without contamination Fluid (blood) go through, and that the magnet and the Hall effect sensor can be sealed behind a non-magnetic barrier, the as a lining or "pot" is called.

With reference to the 12a and b is an embodiment of a Hall effect sensor array. As in 11a 4, there are shown four Hall effect sensors (X +, X-, Y +, Y-) orthogonally attached and fixed to a printed circuit board (PCB) as a Hall sensor array, and a cylindrical magnet 74 is centered between these Hall effect sensors. Regarding 12b Stylized magnetic flux lines are shown by the magnet 70 which represents only one plane (Y) of the magnetic flux line distribution around the magnet, these flux lines being shown intersecting the Y + and Y- Hall effect sensor. It should be noted that when the magnet is centered between the Y + and Y- Hall effect sensor, these two devices deliver a voltage of equal amplitude. It will also be appreciated that if the outputs from these two devices are associated with the respective + Y and -Y ratios and these values are different, then the indicated different output will be indicative of the magnet position is above or below the abscissa, and the value of this output is the value of the local displacement from the abscissa. In the same way, the X position of the magnet within the sensor field can be obtained by following this same procedure. The mathematical relationship for the X and Y positions would be: 3X = X-X +, and 3Y = Y-Y +. It should be noted that the magnetic flux lines from the magnet are impermeable to any non-ferrous material, so that a biocompatible pot or protective layer made of, for example, titanium would not interfere with or inhibit positional information obtained from this device.

Regarding 12c Another embodiment of a Hall effect field configuration is shown with two Hall effect fields axially symmetrically placed about the centerline and center plane of a magnet. It should be noted that the differentiated pairs X1, Y1, X2 and Y2 operate as independent sensors to determine the respective X and Y magnet positions at their respective locations. It should also be noted that in addition to the X and Y positions, the relative axial position of the magnet can be derived by separately summing all the X1 and Y1 Hall effect outputs separately, regardless of the signal 31 = (X1 +) + X1-) + (Y1 +) + (Y1-)), while at the same time the same with the X2 and Y2 outputs ( 32 ) happens. The assignment of an arbitrary character + an axial movement to the right (X2 and Y2) fields and - moving to the left (X1 and Y1) fields and adding these two sums together leads to the direction of axial displacement as well as the Z value of the magnet position. The mathematical relation for determining the Z-position of the magnet assuming that a movement to the right would be positive would be Z = 32-31.

The Hall effect sensors or arrays described above require none unobstructed view of the wheel. Thus, the sensors from the impeller and the fluid channel separated by the liner or pot be. Furthermore The sensors do not enter the fluid channel and hinder it not the flow path or fluidic characteristics. Furthermore The sensors do not require special surfaces to adjust the position of a to detect rotating element. For example, laser sensors require highly polished surfaces, and eddy-current (inductive) and capacitive sensors require one conductive (metallic) surface. Furthermore The sensors do not require an additional magnet to match the to add rotating element is. For example, you can two permanent magnetic fields are arranged in the impeller body, such as is shown. Therefore, could the two Hall effect sensor fields described above inside of the stator are arranged around the radial permanent magnets on the impeller and the axial permanent magnets on the impeller to see. Furthermore can the sensors in conjunction with engine characteristics (RPM and power consumption) used to determine the pressure differential across the pump. This feature could Be very important to be on high and low blood pressure in one Close patients.

alternative can Hall effect sensors are positioned to the impellers of the axial and radial bearings to use, in contrast to the additional Magnet. Thus, you can two Hall effect sensors are positioned on the stator, of which a field is arranged to detect a magnetic field that of the Impeller magnet of the axial permanent magnet bearing is generated, and another positioned at a different axial location is to capture a different magnetic field, that of the Impeller magnet of the radial permanent magnet bearing is generated.

One or more accelerometers can be used to accelerations of the stator or pump housing to measure in different directions. In addition, speed measuring devices can be used be to the speed of the pump housing in different directions to determine. The signals from these devices can be used to serve as feedback signals for the electromagnet, also for the physiological controller and / or alarms, for example to display a case.

In addition, can the electromagnetic bearing itself both as an actuator as also be seen as a sensor. Thus, the active bearing in a self-feeling Mode used to get the position information from the winding to win. A treasury can be built to filter the current signal and to get the position from the filtered signal. Such a Technology avoids additional Sensors and electronics. This reduces the number of wires, and the reliability is increasing.

The controller may be operatively coupled to the pump or to the sensors, the motor, and the active electromagnetic bearing. The controller may include several different algorithms for different electromagnetic modes of operation including, for example, sleep, rest and activity. In the sleep state, the fluid and gravity changes in force tend to be much smaller, so that a simple control algorithm that saves power can be used. In an awake hibernation or active state, the fluid and gravity changes in force tend to be greater, and a more advanced control algorithm that consumes more power can be used. The various algorithms may be automatically switched from one to another based on input signals that are displayed by either the hall effect sensors, the accelerometer (s), or other motion detection device. A bumpless transfer algorithm that tracks both control algorithms just before the shift occurs may be used for this shift to prevent a large rotor swing.

Of the bumpless Transfer algorithm allows the controller smooth between different Switch modes of operation: sleep mode with low power consumption, normal mode for daily Activities, and active mode for moderate exercises like climbing stairs. A good one Bias control of the electromagnetic pole currents also contribute to power reduction.

• 1) Rotoranheben von jeder möglichen anfänglichen Ruheposition und dann erfolgreiche Rotation beim Anlaufen;
• 2) Verhindern das Aufsetzen des Rotors mit Änderungen der Rotationsgeschwindigkeiten, ungeachtet der Position des Patienten;
• 3) Widerstehen den Ungenauigkeiten der Pumpe, die bei ihrer Herstellung auftreten;
• 4) Schutz gegen Störungskräfte wie beispielsweise Blutströmungsstörungen und plötzliche Körperbewegungen;
• 5) Verbrauch von so wenig Strom wie möglich, um die Batterienutzungsdauer zu maximieren;
• 6) Minimieren des Steueraufwandes, um die Größe und das Gewicht der magnetischen Lager zu reduzieren.

The functions and requirements of the suspension control may include:

• 1) rotor lifting from any possible initial rest position and then successful startup rotation;
• 2) Prevent rotor seating with changes in rotational speeds regardless of the patient's position;
• 3) Resist the inaccuracies of the pump that occur during their manufacture;
• 4) protection against disturbance forces such as blood flow disturbances and sudden body movements;
• 5) Consuming as little power as possible to maximize battery life;
• 6) Minimize control effort to reduce the size and weight of magnetic bearings.

These Functions and requirements lead over in two Characteristics of the suspension control system: Effectiveness and robustness. Conventional electromagnetic bearing controls usually underuse the capacities the electromagnetic bearing to the closed-loop instability problem to avoid that by saturation the electromagnetic storage capacity is caused. The present electromagnetic pump bearings can be a highly effective and use robust control equipment based on the latest Progress in tax theory is constructed. A feature of this control device is the full use of electromagnetic storage capacity for maximum Performance of the tax system, in terms of effectiveness and Robustness. In other words, an effective suspension control device allows the use of one or more small electromagnetic bearings, which have less weight, less space and less energy.

Of the bumpless Transfer algorithm can be smooth between different control devices turn. For example, when the patient goes to sleep, one becomes less aggressive control device enabled to save energy. However, the transition circuit from one controller to another usually pretty bumpy. The present pump, the new control device a short Start time before switching. A mechanism is provided, the the new controller for synchronization with the on-line controller causes before the switching takes place. This works the same way like runners start in a relay race, before the rod turns to another Runner passes. The transition from one controller to the other controller above is described as a bumpless transition.

Regarding 16a For example, the vibration of the impeller is shown over time as the pump transitions from one control algorithm to another or between modes of operation without the bumpless transfer algorithm being used. As shown, the vibration amplitude was about 0.2 mils before switching, however, the impeller experienced 1.2 mils of vibration during the control switching, and the actuator or active bearing was nearly saturated. Because the controller is robust, the system remained stable. However, it is desirable to obtain a smooth transition or instantaneous switching between controllers while maintaining a smooth vibration output signal. Regarding 16b The vibration of the impeller over time is shown as the pump transitions from one algorithm to another using the bumpless transfer algorithm. As shown, the transition or shifting with a bumpless transfer becomes very smooth and reduces impeller vibration. In addition, winding currents can be minimized to minimize energy losses.

The vibration output signal will be "bumpless" if a smooth control signal can be obtained during switching In order to obtain a smooth control signal, not only the control signal generated by the two controllers should be the same, but also the higher order of derivatives For digital control devices, it is generally difficult to know the deferred control states at the switching pumps, since the deferred control does not control the system before switching.To guarantee the condition of a smooth control signal, the control states can be determined as follows:

unter Verwendung eines Bandpaßfilters, um die Ableitung anzunähern. Da das Outputsignal in magnetischen Lagersystem geräuschempfindlich ist und die robuste Steuerordnung allgemein groß, ist es nicht möglich, alle latenten Steuerzustände durch die obige Formel On-line zu berechnen.For low order systems, the states of the deferred controllers can be obtained by:

using a bandpass filter to approximate the derivative. Since the output signal in the magnetic bearing system is sensitive to noise and the robust control order is generally large, it is not possible to calculate all the latent control states on-line by the above formula.

The latent initial control states can be obtained by a sampling filter K1 and K2, as in FIG 17 is shown. A Kalman filter can be used to estimate the states of the latent controller in the presence of noise. The tax transfer is bi-directional. When the rotor speed approaches the shift speed, for example reaches 90% of the shift speed, the switches for the observer (A, B, C, D and K) are turned on. The observer starts sampling the control output signal u with input y in the presence of a fault. At the switching point, the latent control device is switched to the line and the observation gain K is cut off. The latent control states are the desired values for a smooth transition.

For a duration model, the state-space equation of the controller may be: ξ = Aξ + By + Gw (state equation) u = Cξ + Dy + Hw + v (measurements) with known inputs u, process disturbance b, measurement disturbance v and disturbance covariance: B {ww ¹ } = QN, E {vv ¹ } = RN, E {wv ¹ } = NN,
the estimate K has the input [y; u] and generates the maximum estimates u_e, ξe of u, ξ ξ_e = A ξ_e + By + K (u - C ξ_e - Dy) | U_E | = | C | ξ_e + | D | y

A calmanobserver was constructed to obtain the latent control state. A Kalman filter gives the best estimate of the state in terms of the least square error. Since the amount of rotor acceleration and deceleration is relatively small, and for implementation purposes, a constant asymptotic value of the Kalman filter result is used. This requires solving the algebraic Riccat equation of the steady state in continuous time when H = 0 AP + PA T - (PC T + GN) R -1 (CP + N T G T ) + GQG T = 0

If the magnitude of rotor acceleration and deceleration is high in some applications, the Gainscheduling method can be used, that is, the variation of Kalman gain during observation. Since the magnitude of the change in the Kalman gains is small compared to the sample size, any value of Kalman gain can be used for a portion of the observation time. In either case, the Kalman gain calculation may be performed "off-line" and stored in the computer memory become.

A Kalman filter observer brings the best estimates of the deferred control states in terms of least squares error minimization. The real-time calculation is expensive. There are several methods that can be used to facilitate the computational burden. From the point of view of the setup, the priority of the observation calculation is smaller than that of the calculation of the on-line control. The update of the state of the observer is performed on different sample sizes in real-time application. Second, the complexity of the calculation comes from the real-time computation of the matrix products. The number of flops required to compute the product of a general nxn matrix and nxl vector is n ² . The complexity can be significantly reduced with the special structure of the A matrix. Using a state transformation, an A matrix can be transformed into a canonical Jordan block form. The control devices and the observer are realized with this special form. Third, a set of mini-vector instructions is used. An advanced microprocessor, such as an Intel Pentium III processor, includes a new set of instructions: Streaming SIMD (Single Instruction, Multiple Data) Extensions (SSE). The SSE instructions allow us to use an instruction level parallelism that results in a significant increase in velocity. After application of the SSE, the sample size can reach 8000 Hz (125 μs) for a forty-eighth-order controller on a 700 MHz Intel Pentium III processor while a controller and an observer are running at the time of switching.

The Pump can also be an advanced control method for selecting the correct winding currents in the radial active magnetic bearing, referred to as the inevitable control solution becomes. Thus, the full power capability is made possible by the control method. Furthermore estimates a fault control device effectively the disorders as a result of the physical Movements of the patient or components of the physical movement of the cardiovascular system of the patient, which is due to the centering of the active magnetic Bearing can affect.

The noise control use the estimated ones disorders, around radial forces to develop the magnetic bearing, which counteracts the disturbance forces act and the rotor of the rotary blood pump in the free gap keep centered and keep the operation exactly.

In addition, the active magnetic bearing forces used in a pre-feedback control method, due to the rotational forces of rotor imbalances. Thus, the pump uses advanced Control methods that consume less power, generate less heat and the active magnetic bearing component compared to the state the technology facilitates. The feedback position signal is the electronic Input control system fed to the active magnetic bearing windings. Consequently becomes an inevitable Control method used. Furthermore The pump may have an open loop imbalance control Rotor vibrations using the active control currents in the apply active magnetic bearings. In addition, the pump can be between switch the different bias level using a bum-free Transfer strategy.

The variable biasing operation used in this invention will, contains an adaptive multimode biasing method for the active magnetic Warehouse control currents, as she needed based on the activity level of the patient. The variable bias setting is determined by the disturbance controller, as described above. The bias level is set as it is required to the centering force control on the Rotor for the level of activity suitable to hold, but not more than the required Level, the power consumption of the rotary blood pump and the degree of heating to reduce. To achieve this, a bumpless transfer method is used used.

Another problem with a precisely centered operation of the impeller of the rotary pump is the imbalance in the impeller. All rotating devices are subject to mechanical imbalance since it is difficult or impossible to make a perfectly balanced rotor. In the manufacturing state, the impeller can be adjusted in the normal manner on a leveling machine, removing or adding small masses at the appropriate locations. However, during operation in the patient over a long period of time, additional changes in imbalance may occur due to misalignment of impeller components, wheel drag, adhesion of blood or blood products to the impeller surfaces, and other factors. It is an object of this invention to apply an open loop imbalance control of impeller vibrations using active control currents in the active magnetic bearing. On the basis of this position signal, the suspension control means determines the currents in the active magnetic bearings so that the pum smoothly working in different operating conditions. A robust control device has the ability to withstand the inaccuracies in the manufacture of the various parts of the pumps and overcomes various disturbances. The present pump may have adaptive bias, positive control design and multi-mode control with a bumpless transfer mechanism.

First can be based on the activity level the patient of the bias level can be determined adaptively. A large Bias current allows a big Operating capacity of a active magnetic bearing, but consumes more energy. Under a predetermined bias is a control device designed to be complete the capacities to use, which are made possible by the Vormagnetisierungslevel. The pump will then be between these different control devices switch according to the different bias levels.

The transition from one controller to another can usually be very bumpy. In the present pump, the new control device Start a short time before switching. A mechanism may be formed in the computer, the new control device to synchronize with the on-line controller before the switching takes place. This works the same way as with a relay race, as mentioned above. Such a transition from one controller to another controller as a bum-free Transfer referred.

• 1. Zwangsläufiges Steuerdesign – Die volle Kapazität der AMBs wird von der Steuereinrichtung genutzt; – ein Störungsbeobachter, der wirkungsvoll die Störungen infolge von Bewegungen des Patienten schätzt, macht die Steuereinrichtung dahingehend wirksam, daß diese Störungen zurückgewiesen werden; – die Ansprechzeit der Steuereinrichtung ist maximiert, mit einer vollen Nutzung der AMB Kapazität.
• 2. Ungleichgewichtssteuerung – Ein Vor-Feedback ist geschaffen, das das Ungleichgewicht des Rotors überwindet.
• 3. Adaptive Vormagnetisierung – Der Vormagnetisierungslevel wird gemäß der Betriebsbedingung der Steuereinrichtung eingestellt, was den gesamten Stromverbrauch der Steuereinrichtung reduziert, wann immer dies möglich ist.
• 4. Multimodussteuerung mit stoßfreiem Transfer – Das System schaltet unter verschiedenen Steuereinrichtungen um, die optimal in verschiedenen Betriebsbedingungen sind; – eine stoßfreie Transferstrategie wird verwendet, um das Umschalten auf eine solche Weise durchzuführen, daß der Übergang von einer Steuereinrichtung zu der anderen glatt ist. – Mit erneutem Bezug auf 4 kann das Laufrad eine Ankerschraube 300 und expandierbares Material 304 haben, das verwendet werden kann, um das Gleichgewicht des Rotors herzustellen.

More specifically, the controller may have the following features:

• 1. Forced Control Design - The full capacity of the AMBs is used by the controller; A disturbance observer, who effectively estimates the disturbances due to movements of the patient, makes the controller effective to reject these disturbances; - The response time of the controller is maximized, with full use of the AMB capacity.
• 2. Imbalance Control - A pre-feedback is created that overcomes the imbalance of the rotor.
• 3. Adaptive bias - The bias level is set in accordance with the operating condition of the controller, which reduces the overall power consumption of the controller whenever possible.
• 4. Multi-mode control with bumpless transfer - The system switches among various control devices that are optimal in different operating conditions; A bumpless transfer strategy is used to perform the switching in such a way that the transition from one controller to the other is smooth. - With renewed reference to 4 The impeller may be an anchor bolt 300 and expandable material 304 which can be used to establish the balance of the rotor.

The Impeller and the diffuser can by titanium casting be prepared using a lost wax method, in the case of a precise Wax model or positive in a ceramic cup and negative is formed. liquid Titanium can be poured into the ceramic shell, and the shell will after cooling open. A hydrogen pressure implant can be applied to the cast object act on all surface inaccuracies followed by a chemical etching to remove the surfaces for final processing and to prepare polishing. The bloodstream can become a finish a 10 micro-inch area or better polished. The inlet cannula and the introducer can be prepared with standard techniques of metal forming. The Inlet cannula can a titanium tube, which is shaped into the desired shape (bent and expanded). The inside surface can be on a finish of 10 micro-inches are polished. The introducer can by a Combination of CNC milling, electric wire discharge machining (EDM) and dip techniques EDM are produced. Alternatively, the insertion device could to be poured as mentioned above is. The polishing can be accomplished by applying the Spray-sanding method, which involves the use of a fine-cut medium like diamond chips, those in a mud-like Medium are distributed to surface inaccuracies to polish and remove. The mud can be pumped or along the surfaces guided which are polished until the desired surface finish is reached.

To In one aspect of the present invention, the pump may be configured be that she pumps other fluids or fluids instead of blood.

The foregoing examples illustrate the principles of the present invention in one or more particular applications, and it will be apparent to those skilled in the art that numerous modifications are possible in the form of use and in details of the application, without the inventive faculty, and without departing from the principles and concepts of the invention. It is therefore not intended that the invention be limited except as by the following claims.

Summary

A blood pump ( 10 ) has an impeller ( 14 ) rotatable within a cavity ( 22 ) of a stator ( 18 ) by a plurality of magnetic bearings ( 40 . 50 . 60 ) and magnetically suspended, which is an axial bearing ( 40 ) to axially support the impeller in the cavity. The axial bearing contains adjacent impeller magnets ( 41a , b and c) and adjacent stator magnets ( 42a , b, c) with axially aligned polarities and reversed polarities with respect to adjacent magnets. An engine ( 150 ) contains impeller magnets ( 154 ) on the impeller and windings and poles ( 158 . 168 ), which are connected to the stator. Radial permanent magnet and electromagnetic bearings ( 50 . 60 ) are also included. The magnetic bearings and the motor have stator magnets or windings and poles disposed radially across the fluid passage of associated impeller magnets to define an annular gap positioned radially between the impeller and the stator and positioned radially between all of the magnetic bearings , whereby a straight blood passageway without secondary flow paths is created.

Claims (16)

Blood pump containing: - a stator with a extending cavity therethrough; - An impeller that rotates is arranged in the cavity of the stator and magnetically suspended, wherein the impeller determines an axis of rotation and the stator and the impeller define a fluid passage therebetween; - a plurality of magnetic bearings, the passive permanent magnets and active contain electromagnetic magnets and the impeller within the Float the stator float, including an axial bearing for axial support the impeller in the cavity; - Where the axial bearing a Field of adjacent bearing sets contains the axially relative the axis of rotation are strung, each bearing set one Impeller magnet on the impeller and a stator magnet on the stator contains and the impeller and stator magnets are radially aligned over the fluid passage are; - in which adjacent impeller magnets and adjacent stator magnets axially aligned polarities and reversed polarities in terms of have adjacent magnets, and - where a motor impeller magnets on the impeller and windings / poles that are connected to the stator are connected. The blood pump of claim 1, wherein the impeller and Statormagnete each bearing set mutually reverse polarity. A blood pump according to claim 1, wherein all magnetic Bearings and the motor stator magnets or windings / poles have that radially over the fluid passage of associated Impeller magnets are arranged to limit an annular gap, which is positioned radially between the impeller and the stator, and radially between all the plurality of magnetic bearings is positioned. The blood pump of claim 1, further comprising: a single annular Blood flow path extending axially through the cavity between the impeller and the stator extends and between the impeller magnets on the impeller and the Stator magnets or the windings / poles to the stator. The blood pump of claim 1, wherein the impeller is magnetic is suspended within the cavity of the stator, without the structure spans the cavity of the stator, around a single, essentially unhindered bloodstream through the Cavity of the stator and to form the impeller. A blood pump according to claim 1, wherein all magnetic Bearing impeller magnets, which are arranged in the impeller, and stator magnets included, which are arranged on the stator and around the cavity of the stator, without one Stator magnet is disposed in the cavity of the stator. The blood pump of claim 1, wherein the plurality of magnetic bearings further includes a radial perma magnetic bearing comprising: at least one pair of adjacent bearing sets disposed axially with respect to the rotation of the rotation, each bearing set having an impeller magnet on the impeller and a stator magnet on the stator and radially aligning the impeller and stator magnets radially across the fluid passage are; wherein adjacent impeller magnets and adjacent stator magnets have axially aligned polarities and reversed polarities relative to each other. A blood pump according to claim 7, wherein the impeller and Stator magnet of each bearing set of the radial permanent magnet bearing the same polarity have each other. The blood pump of claim 7, further comprising: at least two Hall effect sensors, which are connected to the stator, wherein One of the Hall effect sensors is positioned to a magnetic field to detect that of the impeller magnets of the axial permanent magnet bearing and another Hall effect sensor on another axial position is positioned to detect a different magnetic field, that is generated by the impeller magnets of the radial permanent magnet bearing becomes. The blood pump of claim 7, wherein the plurality of magnetic bearings also a radial electromagnetic bearing contains which includes: - impeller magnets, which are arranged in the impeller, and - windings / poles with the stator are connected, wherein the impeller magnets and the windings / poles radially over the Fluid channel are positioned from each other. The blood pump of claim 10, further comprising: Insertion wings, the on the stator at an inlet of the Cavity are arranged, wherein the poles of the radial electromagnetic Warehouse arranged in the introduction wings are. A blood pump according to claim 10, wherein - the radial arranged electromagnetic bearing at an inlet to the fluid passage is; - the radial permanent magnet bearing closer an outlet too arranged the fluid passage is and - the axial permanent magnet bearing between the radial electromagnetic Bearing and the radial permanent magnet bearing is arranged. The blood pump of claim 10, further comprising: one Pot radially surrounding the cavity of the stator and the windings / poles of the stator separates from the fluid passage. The blood pump of claim 10, further comprising: at least two control devices with different bias currents, the each operatively coupled to radial electromagnetic bearings and are designed to switch from one to the other, wherein one of the controllers starts before another stops. The blood pump of claim 1, further comprising: - at least a Hall effect sensor connected to the stator and positioned is to detect a magnet disposed in the impeller is and - one Pot, between the at least one Hall effect sensor and the Magnet is arranged, which is arranged in the impeller. The blood pump of claim 1, wherein the engine is further includes: offset Stator poles with slope, around a magnetic gap between one leading Polrand in a desired To make direction of rotation that is smaller than another magnetic gap between a trailing edge of the pole in one converted direction of rotation.