WO2000062841A1

WO2000062841A1 - Device for axially delivering fluidic media

Info

Publication number: WO2000062841A1
Application number: PCT/EP2000/003560
Authority: WO
Inventors: Peter NÜSSER; Johannes Müller; Hans-Erhard Peters; Norbert Buske; Werner Neumann; Kurt Graichen
Original assignee: Berlin Heart Ag
Priority date: 1999-04-20
Filing date: 2000-04-19
Publication date: 2000-10-26
Also published as: AU4553200A; DE20007582U1

Abstract

The aim of the invention is to provide a device for axially delivering fluidic media such that said device exhibits a low-friction sealing, which does not generate any turbulences, between the stationary tubular hollow body and the rotating tubular delivering part, and with which sealants cannot be absorbed by the fluidic medium to be delivered. To these ends, the annular gaps between the tubular stationary hollow bodies and the rotating delivering part are provided with a magnetic fluid seal.

Description

Device for the axial delivery of fluids

media

description

The invention relates to a device for the axial conveyance of fluid media according to the preamble of claim 1.

Devices for the axial conveyance of fluid media are known. These devices, which are also referred to as axial pumps, are used in particular for the gentle delivery of fluids in medical fields. For example, the publication "Heart Replacement Artificial Heart 5", pages 245 to 252, Springer Verlag, Tokyo 1996, describes an axial blood pump to support a diseased heart, which can be implanted in a patient's chest.

A similar device is also described in U.S. Patent No. 4,957,504.

DE 196 54 834 AI describes a heart pump in which a rotating tubular conveying part is fitted in a blood-carrying tubular fixed hollow body, which has suitable blading and rotates the blur in the axial direction. transported the tubular hollow body. On the two edges between the stationary hollow body and the rotating front part create annular gaps. Sealing these annular gaps is extremely difficult because the previously known axial seals have a high energy consumption, which generally severely limits their use as cardiac support pumps.

Furthermore, turbulence often occurs in the flowing medium in the annular gap area, which can be disadvantageous in particular when biological fluids are required. This turbulence can be traced back to the previously known and known seals of the annular gaps in axial pumps of this type.

The invention has for its object to provide a device for the axial requirement of fluid media, which has a low-friction and no turbulence-generating seal between the fixed tubular hollow body and the rotating tubular conveying part and in the sealant can not be absorbed by the fluid medium to be requested.

The problem is solved in that the annular gaps between the tubular fixed hollow bodies and the rotating front part have a magnetic fluid seal.

Here, a so-called magnetic fluid is used as a sealant. Magnetic fluids are stable dispersions with superparamagnetic properties. The dispersions generally consist of the magnetic component, amphiphilic additives and a carrier liquid. As magnetic Component are used remote or ferromagnetic particles, the particle size is between 3 and 50nm. The so-called amphiphilic additives give the particles either hydrophilic or hydrophobic properties and can thus be homogeneously finely distributed in either aqueous or organic carrier liquids. The composition of the magnetic fluid depends on its application, which determines the desired saturation magnetization and the chemical composition. Saturation magnetization determines the interaction of the magnetic flux in the magnetic field. The stronger the magnetization, the greater the pressure differences the gasket can withstand. The carrier liquid in these applications consists of high-boiling liquids to prevent the carrier liquid from evaporating. The type of amphiphilic additives (surfactants) depends both on the magnetic component used and on the carrier liquid. The nature of the surfactants determines their fixation on the particle surface of the magnetic component or the solubility of the particles in the respective carrier liquid.

The carrier liquids e can advantageously be oil-like or aqueous liquids, depending on the nature of the fluid medium.

In the axial delivery of oil-like fluids z. B. the use of a magnetic fluid based on water, since the interactions between the two media can be minimized in this way.

D e interactions between the medium to be demanded and αer magnetic fluid are, however, primarily almost completely avoided by the fact that the 00/62841

Magnetic liquid is completely fixed in the annular gap by the application of a magnetic field according to the invention.

This seal has proven to be extremely low-friction, so that the energy expenditure for generating the rotation can be greatly minimized and heating of the medium to be conveyed does not occur or only occurs to a small extent.

The invention is explained in more detail below using an exemplary embodiment and FIGS. 1 to 8.

Show it:

1 is an axial half section of a conveyor,

2 shows a detailed representation of the magnetic fluid seal,

3 shows a detailed representation of the magnetic fluid seal with attached magnet arrangement,

4a is an axial view of the magnetic fluid seal with a ring magnet,

4b is an axial view of the magnetic fluid seal with two individual magnets,

5 is a detailed view of the magnetic fluid seal with a barrier to prevent attraction, 00/62841

6a exemplary representations of the training up to the end faces,

Fig. 6b

7 is a detailed representation of the magnetic fluid seal with asymmetrically placed magnets,

Fig. 8 is a detailed representation of the magnetic fluid seal with asymmetrically attached magnets.

1 shows a half section of an exemplary embodiment of a conveyor device according to the invention. The direction of delivery of the fluid medium is marked with an arrow. The fluid medium is introduced into the pump area through an inlet connector 7. The input connector 7 is fixed. An impeller 2 is fastened in an adjoining rotor tube 1. This is followed by an output connector 10, which contains a so-called stator 11 rigidly attached. An input ring gap 16 and an output ring gap 17 are formed between the rotor tube 1 and the input connector 7 on one side and the output connector 10 and the rotor tube 1 on the other side. An input seal 8 and an output seal 12 are arranged around the input ring gap 16 and the output ring gap 17. On the outside of the impeller 2, a motor rotor 3 is attached, which with a motor stator 4 ensures a rotational movement of the rotor tube 1 and thus the impeller 2. The energy supply for this drive is not shown here. The entire pump area is fixed Ξmgangsgehause 9, exit housing 13 and Laufergehause 5 covered. The motor stator 4 is rigidly attached directly to the rotor housing 5. The rotor housing 5 is separated from the input housing 9 and output housing 13 by an input holder 14 and an output holder 15. The input bracket 14 and the output bracket 15 each hold a bearing 6, which ensure the stabilization of the rotational movement of the impeller 2.

In Fig. 2, a magnetic fluid seal of the device according to the invention, which is provided as an inlet seal 8 and / or as an outlet seal 12, is shown in detail in a sectional view, here and also in the further FIGS the conveyor is shown. The exemplary embodiments of the magnetic fluid seal are shown on the tube walls 104a and 105a of the tubes 104 and 105 in the region of tube ends 109 and 110. The tube ends 9 and 10 are so close to one another that an annular gap 101 defined by end faces 114 and 115 is formed.

2 consists of a magnet arrangement 108 and a magnetic fluid 111, not shown here, which is fixed in the annular gap 101. The magnet arrangement 108 contains a magnet 106, which is positioned discretely distributed around the annular gap 101 in an annular or annular manner, and so-called pole shoes 102 and 103, which serve to transmit the magnetic flux and the optimal orientation of the magnetic field in the annular gap 101. The pole piece 103 is with the Pipe wall 105a connected. The pole piece 102 forms a secondary gap 107 with the tube wall 104a. The magnet 106 is held by the pole piece 103 above the annular gap 101. The tube ends 109 and 110 are connected to the magnet 106 in a magnetically conductive manner via the pole shoes 102 and 103. The size of the secondary gap 107 formed between the pole piece 102 of the magnet arrangement 108 and the tube wall 104a is such that the magnetic field can be transmitted from the magnet 106 to the tube end 109 via the pole piece 102. The secondary gap 107 enables flexible coupling of the two tubes 104 and 105. The transmission of the magnetic flux via the pole shoes 102 and 103 leads to the formation of a magnetic north and south pole at the tube ends 109 and 110, between which the magnetic fluid 111 is held.

3 shows a development of the device according to the invention, the pipes 104 and 105 of which are to be connected and are made of non-magnetizable material. Here it is necessary that the pole shoes 102 and 103 are attached to the end of the pipe ends 109 and 110 of the non-magnetizable pipes 104 and 105. The pole shoe 102 is divided into two to maintain the secondary gap 107. A magnetic part 102a of the pole piece 102 is in direct contact with the magnet 106 and a tube part 102b of the pole piece 102 is attached to the end of the tube end 109. The tubular part 102b and the magnetic part 102a form the secondary gap 107. The annular gap 101 is formed between the pole shoe 103 attached on the end face and the tubular part 102b of the pole shoe 102 and has the required different magnetic polarity for fixing the magnetic fluid 111. 4a and 4b show axial views of the device according to the invention viewed from tube 104. The two views are partially cut away in order to recognize the formation of the magnet 106. In this representation of the device according to the invention, a circular cross section of the pipes 104 and 105 to be connected is assumed. 4a, a ring-shaped magnet 106 is provided, which is fixed between the pole shoes 102 and 103. 4b, on the other hand, two opposing individual magnets 106 are arranged, which are also fixed between the pole shoes 102 and 103. The pole shoes 102 and 103 have a different shape here. This shape is necessary in order to optimize the magnetic field formation in the direction of the annular gap 101. The tube 104 forms the secondary gap 107 with the pole shoe 102. In FIG. 4b two magnets 106 are shown in an individual arrangement by way of example, but depending on the sealing problems to be solved between two tubes 104 and 105, the further arrangement of magnets 106 is advantageously possible. To do this, it would then be necessary to adapt the shape of the pole shoes 102 and 103.

The formation of the magnetic fields between the end faces 114 and 115 of the pipe ends 109 and 110 can lead to a narrowing of the annular gap 101 due to the magnetic attraction if the pipes 104 and 105 are not adequately fixed. Disadvantageously, magnetic fluid 111 can thereby escape from the annular gap 101 or the flexibility of this pipe connection is restricted by the reduction in the size of the annular gap 101. The exemplary embodiment of FIG. 5 allows for the arrangement of a circumferential barrier 112 which has an axial gap with the pole shoe 102 113 forms to build up a magnetic counterforce that counteracts the attraction between the end faces 114 and 115. This is achieved in that the barrier 112 is also magnetically polarized with respect to the pole shoe 102.

6a to 6g show different embodiments of the annular gap 101 or the end faces 114 and 115 which delimit the annular gap 101 in the axial direction. The magnetic fluid 111 is arranged in the annular gap 101.

In a further exemplary embodiment of the invention according to FIG. 7, the magnet 106 of the magnet arrangement 108 is fastened directly on the tube wall 105a. The pole piece 102 transmits the magnetic field across the secondary gap 107 to the tube end 109 of the soft magnetic tube 104.

In the exemplary embodiment according to FIG. 8, the magnet 106 is arranged on the tube end 110, the magnet 106 being designed as a ring magnet. A pole ring 116 is attached directly to the magnet 106 and forms the annular gap 101 with its end face 114 and the end face 115 of the tube end 109. The pole piece 103 is guided across the magnet 106 and the annular gap 101 to the tube end 109. Here it forms the secondary gap 107 with the tube wall 104a of the soft magnetic tube 104. 1

10

Reference list

Rotor tube 101 annular gap

102 pole shoe impeller 102a magnetic part motor rotor 102b tube part motor stator 103 pole shoe rotor housing 104 tube bearing 104a tube wall input connector 105 tube 105a tube wall input seal input housing 106 magnet

Output connector 107 secondary gap

108 Stator magnet arrangement

109 Pipe end exit seal

110 Pipe end exit housing

111 Magnetic fluid inlet bracket outlet bracket 112 barrier

Input ring gap 113 magnetic conductor

114 End face exit ring gap

115 end face

116 pole ring

Claims

claims

1. Device for the axial conveyance of fluid media, consisting of two tubular, the fluid medium guiding fixed hollow body (7, 10), one in the hollow body (7, 10) axially fitted, tubular rotatable conveyor part (1), characterized that annular gaps (16, 17) have magnetic fluid seals (8, 12) between the tubular fixed hollow bodies (7, 10) and the rotating conveying part (1).

2. Device according to claim 1, characterized in that the magnetic fluid seals (8, 12) from a fixed around the annular gap magnet assembly (108) with the ends of the fixed hollow bodies and the ends (109, 110) of the rotating conveyor part (1 ) are connected in a magnetically conductive manner and consist of a magnetic fluid (11) arranged in the annular gaps (16, 17).

Device according to claim 1 or 2, characterized in that the magnet arrangement (108) is connected in a magnetically conductive manner to the ends (109, 110) via two pole shoes (102, 103), ^" with one pole shoe (103) attached one end (110) and a second pole piece (102) is arranged at the end (109).

Device according to one of claims 1 to 3, characterized in that a pole piece (102) is formed in two parts, a tube part (102b) of the pole piece (102) on the tube (104) and a magnetic part (102a) of the pole piece (102) the magnet (106) of the magnet arrangement (108) is attached in a magnetically conductive manner.

5. Device according to one of claims 1 to 4, characterized in that the magnetic part (102a) and the tubular part (102b) are separated by an annular auxiliary gap (107) without contact.

Device according to one of claims 1 to 5, characterized in that the pole piece (102) and the pole piece (103) have a different magnetic polarity.

7. Device according to one of claims 1 to 6, characterized in that the tube end (109) has a circumferential barrier (112) which forms an axial gap (113) with the pole piece (102).

8. Device according to one of claims 1 to 6, characterized in that the tubular part (102b) has a circumferential barrier (112) which forms an axial gap (113) with the magnetic part (102a).

9. Device according to one of claims 1 to 8, characterized in that the magnet arrangement (108) has at least two individual magnets (106), the north or

South pole are each connected to a pole piece (102, 103).

10. Device according to one of claims 1 to 8, characterized in that the magnet arrangement (108) has at least one ring-shaped magnet (106).

11. Device according to one of claims 1 to 10, characterized in that the pole piece (103) and the tubular part (102a) of the pole piece (102) at the ends (109, 110) of the tubes

(104, 105) are attached and / or molded directly.

12. The device according to one of claims 1 to 11, characterized in that that the annular gap (101) in the axial direction delimiting end faces (114, 115) between which the magnetic fluid (111) is arranged are mirror-symmetrical to one another.

13. The device according to one of claims 1 to 11, characterized in that the annular gap (101) in the axial direction delimiting end faces (114, 115), between which the magnetic fluid (111) is arranged, are not symmetrical to each other.

14. Device according to one of claims 1 to 13, characterized in that the end faces (114, 115) in the direction of the annular gap axis have circumferential and / or non-circumferential depressions and / or elevations.

15. The device according to one of claims 1 to 13, characterized in that the end faces (114, 115) have a flat design in the direction of the annular gap axis.

16. The device according to one of claims 1 to 15, characterized in that the end faces (114, 115) are arranged parallel to each other.

17. The device according to one of claims 1 to 15, characterized in that the end faces (114, 115) are not arranged in parallel.

18. Device according to one of claims 1 to 17, characterized in that the end faces (114, 115) are arranged at right angles to the annular gap axis.

19. Device according to one of claims 1 to 17, characterized in that the end faces (114, 115) are arranged at an acute and / or obtuse angle with respect to the annular gap axis.

20. Device according to one of claims 1 to 19, characterized in that the magnets (106) of the magnet arrangement (108) are designed as permanent or electromagnets.

21. Device according to one of claims 1 to 20, characterized in that the pole shoes (102, 103) consist of soft magnetic material.

2. Device according to one of claims 1 to 21, characterized in that the magnets (106) of the magnet arrangement (108) are attached to the tube ends (109 or 110).