Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
  • A61M60/10—Location thereof with respect to the patient's body
  • A61M60/104—Extracorporeal pumps, i.e. the blood being pumped outside the patient's body
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
  • A61M60/20—Type thereof
  • A61M60/205—Non-positive displacement blood pumps
  • A61M60/216—Non-positive displacement blood pumps including a rotating member acting on the blood, e.g. impeller
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
  • A61M60/40—Details relating to driving
  • A61M60/403—Details relating to driving for non-positive displacement blood pumps
  • A61M60/408—Details relating to driving for non-positive displacement blood pumps the force acting on the blood contacting member being mechanical, e.g. transmitted by a shaft or cable
  • A61M60/411—Details relating to driving for non-positive displacement blood pumps the force acting on the blood contacting member being mechanical, e.g. transmitted by a shaft or cable generated by an electromotor
  • A61M60/416—Details relating to driving for non-positive displacement blood pumps the force acting on the blood contacting member being mechanical, e.g. transmitted by a shaft or cable generated by an electromotor transmitted directly by the motor rotor drive shaft
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
  • A61M60/40—Details relating to driving
  • A61M60/403—Details relating to driving for non-positive displacement blood pumps
  • A61M60/422—Details relating to driving for non-positive displacement blood pumps the force acting on the blood contacting member being electromagnetic, e.g. using canned motor pumps

Definitions

• the invention relates to a pump for a delicate fluid, according to the preamble of claim 1.
• a pump of this type is also known as a Tesla pump or a disc pump, although a rotor of such a pump does not have to be in the shape of a disc, or at least not exclusively.
• pumps of this type it is important to avoid large shear stresses in the fluid as much as possible in order to prevent damage to the fluid.
• An example of a delicate fluid of this type is blood. During the transfer by pumping, the blood cells in the blood should be subject to as little damage as possible, while thrombosis formation should also be prevented as much as possible.
• Fig. 7 of DE-2.200.599 shows a blood pump having four trumpet- shaped rotors. These rotors are concentrically connected to one another by means of struts. One rotor is connected to a drive shaft, likewise by means of struts, which drive shaft is in turn driven by an electric motor.
• the four rotors are accommodated in one pump chamber which is delimited by a housing. Each of the rotors is provided with an opening around its centre axis to allow the passage of blood.
• the pump chamber is provided with an inlet opening and an outlet opening.
• the inlet opening is situated on one side of the housing, in line with the openings in the rotors.
• the outlet opening is provided close to the radially outer side of the pump chamber.
• the side of the rotors facing the inlet is below referred to as the front, the side remote from the inlet as the rear.
• blood will enter the pump chamber via the inlet and spread throughout the pump chamber, in which case it will be both at the front and at the rear of the rotors due to the openings in the rotors. Due to adhesion, the rotating rotors will entrain blood during a rotational movement, as a result of which the remaining blood in the pump chamber will also rotate. As a consequence of the centrifugal forces, the pressure of the blood in the pump chamber will be greater at the radially outer side thereof than at the inlet, which will lead to blood emerging from the outlet.
• a disadvantage of the known blood pump is the fact that turbulences may arise near the openings in the rotors. This risk is greatest for the rotor which is furthest at the back, viewed in the direction of flow, i.e. the rotor that is connected to the drive shaft. The rear of this rotor faces the pump housing. Blood flowing through the passage of this rotor will flow onto this non-rotating housing. There is therefore a risk that the blood between this rotor and the housing is rotated to a lesser degree than the blood between the rotors .
• the pump according to the invention comprises a pump chamber, a first inlet for feeding fluid into the pump chamber, and an outlet, for discharging the fluid from the pump chamber.
• the pump furthermore comprises a pump rotor which is provided in the pump chamber so as to be able to rotate about a centre axis.
• a second inlet is provided for feeding the fluid into the same pump chamber.
• the second inlet Due to the second inlet, fluid can be fed to both sides of the pump rotor without holes having to be made in the pump rotor for this purpose. Thus, the risk of the fluid being damaged near the holes in the pump rotor is prevented. Furthermore, it is advantageous for the second inlet to be able to direct the fluid in such a manner that it flows as much as possible to the pump rotor, whereas in the prior art, the fluid which emerges from the hole in the pump rotor initially flows away from the pump rotor.
• Fig. 3 of DE-2.200.599 shows an embodiment of a blood pump, whose last pump rotor does not have a hole.
• this pump rotor has a large so-called dead surface, where blood is present, but is not actually being transferred by pumping.
• This dead surface extends on the radially outer side of the rotor, as well as on the rear of the rotor.
• the surface in the pump chamber which is delimited by the dead surface and the pump housing can be considered to be dead space. Blood which is present in this dead space and therefore in contact with a moving rotor without actually being transferred by pumping is at an increased risk of being damaged and forming thromboses. Due to the second inlet according to the invention, it is possible to prevent such dead spaces and to use preferably substantially the entire surface of the pump rotor as pumping surface without a hole having to be provided in the pump rotor for this purpose.
• US-6.132.193 shows an air pump having a. first and a second inlet.
• this is a positive- displacement pump.
• An impeller with coiled rods and walls of a housing together delimit sickle-shaped working spaces which displace the air towards an outlet by means of a circular movement and thereby increase the pressure.
• a pump of this type is not suitable for transferring a delicate fluid by pumping, as the fluid will be damaged at the points of contact between the • coiled rods and the housing.
• the first and second inlet have no impact whatsoever on reducing shear stresses in general, or turbulence in particular.
• positive-displacement pumps are not suitable for transferring a delicate fluid by pumping as the fluid becomes damaged at the point of contact between an impeller, such as for example a piston, and a housing, for example a cylinder, inside which the impeller moves.
• Regular centrifugal pumps where the pumping action is essentially effected by means of blades placed on a rotor, are not suitable either. The blades cause- such turbulences and shear stresses that a delicate fluid to be transferred by pumping will " be damaged and/or any emulsion will separate as a result.
• the second inlet is provided substantially diametrically opposite the first inlet in the pump chamber.
• the pressure chamber comprises a pressure region which extends around the pump rotor and is in communication with the outlet.
• the pressure region extends at the location of the largest diameter of the pump rotor.
• the pump rotor comprises a spinning top- shaped body. Such a spinning top-shaped body can be produced in a simple and inexpensive manner and fluid can flow onto it effectively from two opposite locations.
• the spinning top-shaped body has a substantially progressively increasing radius, viewed from one end of the spinning top-shaped body towards the largest diameter of the spinning top- shaped body.
• a progressively increasing radius results in a concave curve, as a result of which sudden changes in the direction of flow of the fluid are avoided and a gradually increasing centrifugal force can be exerted on the fluid.
• the spinning top-shaped body is symmetrical relative to an imaginary plane, which extends at right angles to the centre axis of the pump rotor. This kind of symmetry makes it easier to control the supply of fluid from two sides such that the pump rotor maintains a balanced position in the axial direction through the two fluid flows .
• the pump rotor is provided with an annular disc, whose internal radius corresponds with the external radius of the spinning top-shaped body.
• the annular disc increases the effective diameter of the pump rotor. Such an increase results in a disproportionate increase in the efficiency of the pump.
• the surface of the pump rotor adjoining the pump chamber is substantially hydrophilic.
• a hydrophilic surface increases the adhesion between the fluid and the pump rotor, thus increasing the efficiency of the pump.
• the pump chamber is advantageously delimited by a housing which is substantially hydrophobic.
• a hydrophobic limitation of the pump chamber ensures that the fluid adheres to a relatively smaller extent to the non-rotating housing. This increases the efficiency of the pump .
• the invention furthermore relates to the use of a pump for pumping blood.
• the invention relates to the use of a pump for pumping blood, in particular blood which is not inside the body of a human or animal, according to claims 10 and 11.
• the pump is particularly suitable for pumping blood.
• the use of the pump for transferring blood by pumping reduces the risk of damage to the blood and of thrombosis formation in comparison with pumps according to the prior art.
• fig. 1 shows a sectional side view of a first embodiment of a pump according to the invention
• fig. 2 shows a sectional view on line II-II in fig. 1
• fig. 3 shows a sectional side view of a second embodiment of the pump
• fig. 4 shows a sectional side view of a third embodiment of a pump according to the invention.
• Fig. 1 shows an embodiment of a pump 100 for pumping a delicate fluid, such as blood.
• the pump 100 comprises a housing 102, which consists of an outer wall 104 and an inner wall 106.
• the pump housing 102 is rotationally symmetrical about a centre axis 108.
• the inner wall 106 of the housing 102 delimits a pump chamber 110.
• the pump furthermore comprises a first 112 and a second 114 inlet, in the form of respective openings in the housing 102, as a result of which the pump chamber 110 can be provided with fluid from outside the housing 102.
• the pump chamber 110 is furthermore provided with two outlets 116, 118, cf. also fig. 2, for discharging transferred fluid.
• the pump 100 furthermore comprises a pump rotor 120, around which the fluid can flow on two sides.
• the pump rotor 120 has a pumping surface 121 and, in this case the entire outer surface of the pump rotor 120 may be regarded as pumping surface 121.
• the pump rotor 120 is formed rotationally symmetrically about its centre axis 122, which, in use, substantially coincides with the centre axis 108 of the housing 102.
• the pump rotor 120 is rotatable about its centre axis 122, to which end it is rotationally supported in this embodiment by a shaft 124 and a first 126 and a second 128 bearing.
• the shaft 124 is connected to the pump rotor 120 concentrically with the centre axis 122.
• the first 126 and the second 128 bearing are provided in the housing 102 near the relevant inlet openings 112 and 114.
• the pump chamber 110 extends around the entire pump rotor 120 and comprises a pressure region 130 which extends around at least part, in particular the central part, of the pump rotor 120.
• the pressure region 130 is that part of the pressure chamber 110 which is at the radially largest distance relative to the centre axis 108.
• the pressure region 130 is in open communication with the outlets 116 and 118. 1
• the pressure region 130 viewed in the axial direction, is halfway between the inlets 112 and 114 and - in use - at the location of the largest diameter of the pump rotor 120.
• the outlets 116 and 118 are substantially diametrically opposite one another relative to the centre axis 108 of the pump housing 102.
• the outlets 116 and 118 extend in the tangential direction relative to the pump rotor 120.
• the first 112 and second 114 inlets are diametrically opposite one another.
• the inlets 112 and 114 have a circular cross section, the centre of which coincides essentially with the centre axis 108 of the pump housing 102.
• the first inlet 112 is at the location of a first axial end 132 of the pump rotor 120, while the second inlet 114 is near a second axial end 134 of the pump rotor 120.
• the pump rotor 120 comprises a spinning top-shaped body 140 and an annular disc 142.
• the spinning top-shaped body 140 is symmetrical relative to an imaginary plane 144 which extends at right angles to the centre axis 108.
• the spinning top-shaped body 140 comprises two conical bodies, which are connected to one another by their respective base surfaces.
• the respective base surfaces coincide with the imaginary plane 144.
• the conical bodies are substantially identical to one another.
• the cones of the spinning top-shaped body 140 have a substantially progressively increasing diameter, viewed both from the first 132 and the second 134 axial end towards the plane of symmetry 144, which results in a doubly curved concave surface in the shape of the flared bell of a trumpet .
• the annular disc 142 is provided along the edge of the spinning top-shaped body 140 and essentially coincides with the imaginary plane 144.
• the internal radius of the annular disc 142 in this case corresponds with the external radius of the spinning top-shaped body • 140.
• the pump rotor 120 in particular the spinning top-shaped body 140, is provided with four permanent magnets 150, 152, 154, 156.
• the permanent magnets 150-156 cooperate with four electromagnets 160,
• the permanent 150-156 and electromagnets 160-166 form a magnetic drive or electric motor.
• the outer surface of the pump rotor 120 that is to say the surface of the spinning top-shaped body 140 and the annular disc 142 facing the pump chamber 110, comprises a hydrophilic material.
• the surface of the inner wall 106 of the pump housing 102 facing the pump chamber 110 comprises a hydrophobic material.
• the pump rotor 120 is made from a plastic by means of injection-moulding and is hollow in the example shown. It may, however, also be solid.
• the pump housing 102 is likewise made from a plastic.
• Fig. 2 shows a top view of the first embodiment from fig. 1, on line II-II from fig. 1.
• the outer wall 104 of the pump housing 102 has been omitted in this case.
• the electromagnets 160-166 will generate an alternating magnetic field.
• This alternating magnetic field results in a torque being exerted on the pump rotor 120 via the permanent magnets 150- 156.
• This torque leads to a rotating movement, diagrammatically indicated by means of arrow 170.
• a delicate fluid, such as blood is supplied via the first 112 and second 114 inlet. This flows towards the two sides of the pump rotor 120. Due to adhesion, in this case intensified by the hydrophilic surface of the pump rotor 120, the blood will be entrained in a rotating movement, diagrammatically indicated by means of arrows 172.
• the rotating fluid is seemingly subjected to a centrifugal force, although in physical terms there is in fact a lack of a centripetal force, resulting in the blood flowing towards the radially outer side of the pump chamber 110 and there collecting in the pressure region 130.
• the blood flows from the pressure region 130 out of the pressure chamber 110 via the first 116 and second 118 outlet, diagrammatically indicated by means of arrows 174.
• a smoothly configured pump chamber 110 is created. This also prevents great differences in speed of the blood.
• the blood which flows from the first and second side of the pump rotor 120 towards the pressure region 130 will be at a substantially uniform speed, thus avoiding pressure differences and vortices near the edge of the pump rotor.
• the concave shape of the pump rotor 120, the symmetry of the pump rotor 120 and the absence of dead spaces due to the double-sided nature of the pump rotor 120 contribute to a uniform action of the accelerating forces on the blood.
• a further effect of the symmetry of the pump rotor 120 is that the axial forces which the blood entering the pump chamber 110 via the inlet 112 exerts on the pump rotor 120 is substantially cancelled out by the corresponding axial forces of the blood entering via the inlet 114.
• the bearings 126 and 128 only have to absorb a much reduced residual force, if any, in the axial direction.
• Fig. 3 shows a side view of a second embodiment of a pump for a delicate fluid, in particular a blood pump 200.
• the embodiment according to fig. 3 comprises various components which are similar to those of the first embodiment. These components are not explained in detail and have been given a reference numeral increased by 100 compared to the corresponding components of the first embodiment.
• the blood spinning top 220 of the blood pump 200 does not have any bearings, which means that a rotation shaft can be dispensed with. Instead, the first 232 and second 234 ends of the pump rotor 220 are pointed, the tip of the respective pointed end 'being rounded. Due to the symmetry of the pump rotor 220 and of the inlet 212 and 214, the pump rotor 220 will be centred in the axial direction when in use. In the radial direction, the pump rotor 220 is centred relative to the centre axis 208 of the pump housing 202 due to the in particular conical shape, in this case concave conical shape, of the pump rotor 220.
• the relevant axial ends 232 and 234 may be provided with a permanent magnet, which cooperates with magnets provided at a suitable position near the inner wall of the housing 202.
• the pump chamber 210 is provided with only one outlet 216, this may be at the expense of centring the pump rotor 220 about the centre axis 208 of the pump chamber 210. This adverse effect may be avoided by providing an additional pressure duct (not shown) in the pump housing, concentrical to the pressure region 230.
• Fig. 4 shows a sectional side view of a third embodiment of a blood pump 300.
• Components of this blood pump 300 which correspond to components of the first embodiment are denoted by reference numerals which are increased by 200 compared to the corresponding components of the first embodiment.
• the pump rotor 320 is provided on a shaft 324 so as to be rotatable. In contrast with the first embodiment, the shaft 324 only protrudes from the pump rotor 320 at one axial end. In a similar way to the second embodiment, the first axial end 332 is provided with a rounded pointed end.
• the shaft 324 is rotatably mounted in a bearing 328 which is in turn provided in the housing 302 and also acts as a liquid-tight passage.
• the blood spinning top 320 is driven via the shaft 324 by means of a diagrammatically illustrated electric motor 380.
• the pump according to the invention can be used for transferring blood by pumping.
• it can assume the function of the heart of a patient during an operation. It can also be used separated from the body, for example when transferring blood by pumping into a blood bank or when examining blood which has already been removed from a body.
• the pump for a delicate fluid is not limited to the embodiments shown. Thus, various variants and additional elements are possible. Components of the pump housing and the pump rotor may also be made from metals, ceramic materials, glass and natural materials, such as rubber, rather than from plastic.
• the pump rotor may be provided with ribs .
• ribs increase the load on the fluid and will therefore not be suitable for the most delicate fluids, such ribs offer the advantage of increasing the efficiency of the pump.
• the pump rotor operates substantially entirely on the basis of adhesion.
• the pump rotor may also be provided with two additional trumpet-shaped surfaces which extend substantially parallel to the surface of the pump rotor in the pump chamber. They may be connected to the pump rotor by means of supports, preferably supports which exert a small load on the liquid and are provided near the respective inlet.
• the additional trumpet-shaped surfaces are open towards the inlet, while the trumpet-shaped surfaces near the pressure region define a passage.
• fluid can flow between the respective trumpet-shaped surfaces and the corresponding surface of the pump rotor. As this fluid flow encounters a rotating wall on both sides, the pump delivery is increased.
• any additional trumpet-shaped surfaces may extend halfway between the pump rotor and the innex wall of the housing. In this case, both sides of the trumpet-shaped surfaces are active, which results in a relatively high pump delivery.
• the fluid which emerges from the space between the pump rotor and the trumpet-shaped surface will have a higher speed than the fluid which emerges from between the trumpet-shaped surface and the housing. This may lead to vortices behind the edge of the trumpet-shaped surface, as a result of which this embodiment is less suitable for most delicate fluids, such as blood.
• the trumpet-shaped surfaces may lie closely against the inner wall of the housing and, if desired, be provided with suitable seals, so that there is no fluid between the trumpet- shaped surfaces and the inner wall.
• This has the advantage that the fluid is surrounded only by rotating walls. This results in a more uniform distribution in the speed of the fluid.
• no seals are known which are sufficiently reliable to be used in a blood pump .
• the central pump rotor is closed, even in a variant of this type.
• Central pump rotor is understood to mean the pump rotor which is essentially halfway between the inlets.
• this is also the driven pump rotor, in which the trumpet-shaped surfaces are driven via the central pump rotor.
• the illustrated magnetic drive and magnetic bearing may also be designed in various ways. Thus, more or less than four permanent and four electromagnetic magnets may be used, as well as annular magnets.
• a first blood pump may run stationary and thus provide a base flow rate.
• the second pump may have a. variable speed of rotation in order to control the pressure and/or delivery of the pumps.
• the spinning top-shaped body may be flatter than illustrated, with the axial height being smaller than the largest radial diameter.
• the pump rotor may also comprise a substantially flat disc onto which fluid flows from both sides according to the invention. In order to improve the circulation and prevent vortices, the centre of such a surface may be provided with a cone.
• the spinning top-shaped body and the possible cone on a flat disc may be curved concavely, as described above.
• these surfaces may also be straight cone sections or a surface defined by an S curve .
• the pump rotor it is possible for the pump rotor not to be completely symmetrical with respect to a plane at right angles to the centre axis.
• both inlets may differ from one another and the amount of liquid flowing in through the inlets can be controlled in a different way, it being advisable to match the asymmetry of the pump rotor and the inlet beforehand in such a manner that no large differences in speed occur when the two fluid flows come together in the pressure region.
• the invention provides a pump for a delicate fluid which is particularly suitable to be used as a blood pump. On account of the two-sided flow, both vortices and dead spaces are avoided, thus reducing the risk of damage to the blood and thrombosis formation.
• the pump chamber has a smooth surface with few or no obstacles, which again reduces the risk of damage.
• the pump is simple, can be made from few components and is relatively inexpensive to produce.

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• Health & Medical Sciences (AREA)
• Heart & Thoracic Surgery (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Mechanical Engineering (AREA)
• Anesthesiology (AREA)
• Cardiology (AREA)
• Hematology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• External Artificial Organs (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (2)

Citations (6)

• 2005
  • 2005-03-07 NL NL1028471A patent/NL1028471C2/nl not_active IP Right Cessation
• 2006
  • 2006-03-03 WO PCT/NL2006/000110 patent/WO2006096049A1/en active Application Filing

Patent Citations (6)

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