WO2009138283A1

WO2009138283A1 - Solenoid having a cooling device

Info

Publication number: WO2009138283A1
Application number: PCT/EP2009/053383
Authority: WO
Inventors: Johannes Reinschke
Original assignee: Siemens Aktiengesellschaft
Priority date: 2008-05-15
Filing date: 2009-03-23
Publication date: 2009-11-19
Also published as: DE102008023610A1

Abstract

The invention relates to an actively cooled solenoid (10), having at least one current-conducting winding (310) for generating a magnetic field, and at least one copper pipe (211, 221) experiencing flow in the form of a winding (210, 220) as the cooling system. The current-conducting winding (310) and the copper pipe winding (210, 220) are disposed parallel to each other and behind each other as viewed in the direction of the longitudinal axis N of the solenoid. Both windings (210, 220, 310) have approximately the same winding eye and/or the same inner and/or outer dimensions. A helical flat aluminum strip (311) serves as the current-conducting winding (310). The current-conducting aluminum strip (311) and the copper pipe (211, 221) are in mechanical and thermal contact which each other, but are electrically isolated from each other.

Description

description

Magnetic coil with cooling device

The invention relates to a magnetic coil for generating a magnetic field, which is equipped with a cooling device for cooling the magnetic coil.

Minimally invasive diagnostic and therapeutic procedures have become increasingly important in modern medicine in recent years. The procedures required in the procedures are typically performed using catheters or endoscopes. In this case, there is usually a direct mechanical connection between a diagnostic agent, such as a camera, and the hand of the doctor.

Diagnostic examinations, in particular those on internal hollow organs of the human body, e.g. the gastrointestinal tract can be performed by such methods. Typical diagnostic procedures are gastroscopy and colonoscopy. Within the scope of such examinations, photo and / or video sequences of the relevant hollow organ are typically recorded, tissue and / or fluid samples are taken or drugs are administered locally.

In particular, an endoscopy capsule that can be navigated in a magnetic field can be used for such diagnostic or therapeutic procedures or examinations.

Typical magnetic coil systems for navigating an endoscopy capsule are disclosed, for example, in DE 103 40 925 B3 or also in DE 10 2005 010 489 A1. Such magnet coil systems typically comprise a system of 8 to 14 individually controllable navigation or magnetic coils.

The successful use of an endoscopy capsule requires a magnetic field to control the endoscopy capsule. In addition, depending on the application, if necessary, a position determination of the endoscopy capsule by means of a location system needed. Especially in the event that the endoscopy capsule is to be navigated in water, the position measurement can possibly be dispensed with, since there are no appreciable disturbance forces in the water, ie location-dependent frictional or blocking forces. A determination of position in this context means the determination of the spatial position of the endoscopy capsule, for example in a Cartesian coordinate system, as well as the determination of the orientation of the endoscopy capsule in the corresponding working volume. The orientation determination can be made for all three or fewer axes of the endoscopy capsule.

A magnet coil system, which is used for wireless or non-contact movement of a magnetic body in one

Working space should be able to produce high magnetic field strengths. The magnetic control of an endoscopy capsule typically requires magnetic field strengths of up to 100 mT and magnetic field gradients of up to 400 I / t / m. The field gradient values are approximately a factor of 10 above the typical values for magnetic resonance imaging (MRI) systems. In comparison between a magnet coil system for navigating an endoscopy capsule and a magnet coil system of an MRI system, the navigation magnet coil system has an increased need for cooling the magnet coils. While capsule navigation in water requires fewer fields, nonetheless effective cooling can not be dispensed with here as well.

For cooling coils, for example, cooling plates made of metal, preferably of copper, can be attached to the outer surfaces of the coils or between individual winding layers of the coils. However, this is at least disadvantageous if the endoscopy capsule system is to carry out a position determination in addition to the generation of high field strengths for the navigation: The position determination of the endoscopy capsule in the space enclosed by the navigation coils typically takes place by means arranged in this space transmitting coils, which are operated with alternating current. The locating system, ie the transmitting coil is typically operated in a frequency range between 500 Hz and 100 kHz. If, for a cooling system, as mentioned above, large-area metal or copper plates are used on the outer surfaces of the navigation coils, eddy currents are induced in these metal plates by the transmitting coil. The hurricanes induced in the metal plates by the transmitting coil lead to a distortion of the field emitted by the transmitting coil, and thus to transmission errors in the locating system of the endoscopy capsule system.

The cooling of magnetic coils by means of large-scale attached to these metal plates is therefore unsuitable for equipped with a navigation coil system and a tracking system endoscopy capsule system.

Another possibility for cooling a magnetic coil is to form the turns of the coil as a hollow body and to let flow through by a cooling medium, thus to cool the coil directly.

For cooling a navigation coil of a Endoskopiekapsel- system, which is completely wound from hollow bodies, a special cooling medium is necessary. Typically, deionized water can be used for this purpose. The cooling of such a navigation coil also has the following technical problems: viewed in cross section, the cooling channel, which is located in the interior of the hollow body, occupies a considerable part of the cross-sectional area. For this reason, the filling level of the entire navigation coil deteriorates. Under the degree of filling is to be understood in this context, the quotient of the cross section of the current-carrying conductor and the total cross section of the navigation coil. In order to increase the degree of filling of the navigation coil, the diameter of the cooling channel can be chosen small. To a desired Amperewindungszahl To achieve the navigation coil must have a large number of turns. For a large number of turns turn a correspondingly long hollow body is necessary. Over the length of the hollow body again takes place a considerable pressure drop of the cooling medium. If the cooling channel is increased accordingly, this leads to a navigation coil with a large volume and poor filling level. If the solenoid is realized with a small number of turns, a correspondingly high current is necessary to achieve a desired ampere-turn number. This in turn leads to a high technical effort to generate these high currents.

Another way to cool a coil is to place from a non-conductive material, in particular made of a plastic cooling water pipes or tubes between the conductors or windings of a coil. However, this solution has the disadvantage that on the one hand, the heat transfer through the plastic tube is significantly worse than, for example, by a copper pipe and that on the other hand, the plastic hoses only up to max. about 70-75 ⁰ C are temperature resistant.

Typically, the cooling medium in such a cooling system is pressed through the cooling lines at a pressure of several bars. Inside a navigation coil temperatures of over 100 ⁰ C can be easily reached. In addition, occur in the generation of high magnetic fields between the individual conductors of the navigation coil windings not negligible Lorenzkräfte. These can result in individual conductors or winding layers being mechanically displaced against one another even if the navigation coil has a sufficiently mechanically stable construction. If such a mechanical displacement occurs at a location at which a cooling channel made of plastic is drawn into the winding, then the mechanical displacement typically takes place via the plastic component, which is thus subjected to enormous shearing forces. Obviously for reasons of reliability, both for mechanical reasons as well as with respect to the operating temperature occurring, the use of such a cooling system using commercially available, commercially available plastics in a navigation coil system for a capsule endoscopy installation is not advisable.

It is therefore the object of the invention to provide a equipped with an effective cooling system and comparatively easy to manufacture magnetic coil and a method for producing such a magnetic coil.

This object is achieved by the inventions specified in the independent claims. Advantageous embodiments emerge from the dependent claims.

The magnetic coil according to the invention has a current-carrying winding made of electrically conductive material for generating the magnetic field. In addition, at least one hollow body through which a cooling medium flows is provided for cooling the magnetic coil. The current-carrying winding and the hollow body winding are arranged one behind the other as viewed parallel to one another and in the direction of the coil longitudinal axis N of the magnet coil.

The current-carrying winding is in the radial direction, i. in a direction perpendicular to the coil longitudinal axis seen flat band of electrically conductive material which is wound spirally. This is preferably an aluminum strip. The surface of the strip is electrically insulated, wherein the insulation is achieved, for example, by an anodized layer or by means of an interposed insulation film.

The current-carrying winding and the hollow body winding are wound in such a way that they have essentially the same winding eye and / or the same inner and / or outer dimensions seen in the radial direction. Under the Winding eye of a winding is understood in the direction of the coil longitudinal axis seen open cross-section of the winding.

The hollow body winding may be a spirally curved, tubular hollow body, for example a copper pipe. The hollow body is flowed through by a cooling medium and is preferably made of an electrically insulating material, bpsw. by a glass fiber tape, wrapped to avoid for the reasons mentioned above, that an extended electrically conductive surface is formed. In addition, the current-carrying winding and the hollow body winding are electrically isolated from each other, for example. By an additional, placed between the current-carrying winding and the hollow body winding foil or by sheathing the entire hollow body winding with a glass fiber tape.

The current-carrying winding and the hollow body winding are connected to one another in such a way that they are in mechanical and thermal contact.

Advantageously, a current-carrying winding is located between two hollow body windings, so that a more effective cooling is achieved. In principle, a plurality of current-carrying windings and / or a plurality of hollow body windings may be provided, which are arranged alternately one behind the other and are in thermal and mechanical contact with each other. For example. For example, the magnet coil may have two hollow body windings and one current-carrying winding, wherein the current-carrying winding is arranged between the hollow body windings.

For winding up the current-carrying winding and the hollow body winding of the magnet coil, advantageously one and the same winding tool can be used. The current-carrying winding and the hollow body winding are wound up independently of one another. To produce the magnetic coil, the current-carrying winding is first wound and removed from the winding mandrel. Subsequently, on the same winding thorn wound the hollow body winding. By gluing, Umbandelung and / or similar measures, the two windings are then mechanically interconnected. The final mechanical and thermal contact is made by potting the entire coil.

The following advantages arise with the magnet coil according to the invention:

- There are no electrochemical reactions with the

Cooling water instead, because the hollow body winding is made on the one hand of copper and on the other hand is de-energized. As cooling water can therefore be used tap water.

- The insulation of the hollow body winding causes no large area, electrically conductive area is present in which, for example, by external electromagnetic alternating fields eddy currents can be excited, which in turn can lead to EMC problems or additional heat coupling.

- In the event that the current-carrying winding and the hollow body winding are produced independently on the same winding tool, a simple and inexpensive production of the solenoid, especially in small quantities, is possible.

Further advantages, features and details of the invention will become apparent from the embodiment described below and with reference to the drawings.

Showing:

FIG. 1 shows a system for the capsule endoscopic examination or treatment of a patient,

Figure 2 is a perspective view of a magnetic coil of

Magnet coil arrangement, Figure 3 shows a cross section of the magnetic coil and 4 shows a cross section of a further embodiment of the magnetic coil.

FIG. 1 shows in parts a system for capsule-endoscopic examination or treatment of a patient. The system 1 comprises a magnet coil system 2 for wireless navigation of an endoscopy capsule (not shown), as described, for example, in DE 10 2005 010 489 A1. The magnet coil system 2 includes a plurality of magnetic coils 10 (only one of the magnetic coils is explicitly marked in FIG. 1), which may optionally be dimensioned differently, but essentially have a shape, as illustrated by way of example in FIG. FIG. 1 also shows a guide 3 for a patient couch on which the patient is examined or examined

Treatment is located. Also only indicated is a housing 4, which surrounds the magnet coil system 2 and possibly other equipment such as, for example, a location system.

FIG. 2 shows a magnetic coil 10 in perspective

View. The magnetic coil 10 has a rectangular shape in the illustrated embodiment and has a so-called. Winding eye 11 on. In this case, the winding eye of a winding or a coil is understood as meaning the open cross-section of the winding as seen in the direction of the coil longitudinal axis N, which is oriented in the direction of the z-axis of the coordinate system indicated in FIG. 2, i. the opening of the coil surrounded by the actual winding. However, the magnetic coil 10 may also have a circular, an elliptical or a square shape.

FIG. 3 shows the cross section, indicated in FIG. 2, of a section of the magnetic coil 10, which results in the direction of the arrows 12, 13. In the direction of the coil longitudinal axis N, a first hollow body winding 210, a current-carrying winding 310 and a second hollow body winding 220 are arranged in succession. The hollow body Windings 210, 220 and the current-carrying winding 310 are each spirally wound and oriented parallel to each other, ie, the cross-sectional areas of the hollow body windings 210, 220 and the current-carrying winding 310 are parallel to each other.

The current-carrying winding 310 and the hollow body windings

210, 220 are wound in such a way that they have substantially the same winding eye 11 and substantially the same inner and / or outer dimensions d _x , d _a in the radial direction (see FIG. 2).

The current-carrying winding 310 is an electrically conductive, flat aluminum strip 311 whose surface is electrically insulated, wherein the insulation 312 is achieved, for example, by an anodized layer or by means of an interposed insulation film.

The hollow body windings 210, 220 are ideally each made of a spirally curved, a coolant channel having hollow body 211, 221 or from a spirally curved, tubular hollow body 211, 221. Preferably, the hollow body 211, 221 as a copper waveguide or copper pipe with square or rectangular outside - formed cross-section. Such a copper waveguide 211, 221 is usually uninsulated by the manufacturer, in particular without Lackioslierung delivered. The copper waveguide 211, 221 can, before it is finally wound into the spiral shape, be coated with an electrically insulating material 212, 222, for example with a fiberglass tape, in order to avoid that an extended, electrically conductive surface is formed.

The hollow body windings 210, 220 and the copper waveguide

211, 221 flows through a cooling medium, for example. Of tap water for cooling the solenoid coil 10 and the current-carrying winding 310. In this case, the hollow body windings 210, 220 can in principle be connected both in parallel and in series to the source of the cooling medium. For However, in the case that the hollow body windings 210, 220 are connected in series to the source, the temperature of the cooling medium is already increased, when it flows through the behind in the flow direction hollow body winding. The cooling effect is therefore reduced. In addition, the line resistance of serially connected lines is increased. Preferably, the hollow body windings 210, 220 are therefore connected in parallel to the source, since then on the one hand a better cooling effect is achieved and on the other hand, the line resistance is lower.

In addition to the above-mentioned isolation of the copper waveguides 211, 221 with an electrically insulating strip 212, 222, the two hollow body windings 210, 220 are also electrically insulated from the current-carrying winding 310 by means of an insulation 213, 223. This is done, for example, by additional, between the current-carrying winding 310 and the hollow body windings 210, 220 laid films over a sheathing of the entire hollow body windings 210, 220 with glass fiber tape or, as shown in Figure 3, with the aid of a

Vakuumvergusses with an epoxy 213, 223. At the same time are the hollow body windings 210, 220 via a connection 313 with the current-carrying winding 310 in both mechanical and in thermal contact, wherein the thermal contact in the current-carrying winding 310 resulting heat to the hollow body windings 210th , 220 is discharged.

The connection 313 can be realized in different ways:

- Mechanical wrapping of the 3-coil system consisting of the hollow body windings 210, 220 and the current-carrying winding 310 with glass fiber tape and subsequent Vakuumverguss.

Inserting prepreg mats between the hollow body windings 210, 220 and the current-carrying winding 310, Coating of the 3-coil system with prepreg mats followed by thermal compression and curing. - Cold gluing with an epoxy glue.

4 shows an embodiment with two independent current-carrying windings 310, 320. Accordingly, three hollow body windings 210, 220, 230 are provided, wherein the current-carrying windings 310, 320 and the hollow body windings 210, 220, 230 arranged alternately in the direction of the coil longitudinal axis N. , The windings are in thermal and mechanical contact, but are electrically isolated from each other. Incidentally, the structure of the magnetic coil 10 of FIG. 4 corresponds to the copper waveguides 211, 221, 231, the electrically insulating material 212, 222, 232, the insulation 213, 223, 233, the aluminum strip 311, 321, the insulation 312, 322 and the connection 313 to the structure described in connection with FIG.

Advantageously, one and the same winding tool can be used for producing the magnetic coil 10 or for winding the current-carrying winding (s) 310, 320 and the hollow body winding (s) 210, 220, 230.

The magnet coil 10 according to FIG. 3 is produced in the following way: First, the current-carrying winding 310 is wound up and taken from the winding mandrel of the winding machine.

Subsequently, successively on the same mandrel the

Hollow body windings 210, 220 wound. By gluing,

Umbandelung and / or similar measures, the windings 210, 220, 310 are then mechanically interconnected. The final mechanical and thermal contact is made by

Potting the entire coil.

Basically, the order can of course be reversed.

Before winding the hollow body winding 210, 220, the corresponding copper waveguide 211, 221, 231 to be wound should be however, if desired, sheathed with the electrically insulating tape 212, 222, 232.

Claims

claims

1. magnetic coil having at least one current-carrying winding (310, 320) of electrically conductive material and at least one of a cooling medium flow through the hollow body winding (210, 220, 230), characterized in that the current-carrying winding (310, 320) and the hollow body winding (210 , 220, 230) parallel to each other and in the direction of the coil longitudinal axis N of the magnetic coil (10) are arranged one behind the other.

2. Magnetic coil according to claim 1, characterized in that the current-carrying winding (310, 320) is a flat band (311) of electrically conductive material, in particular an aluminum strip, wherein the band (311) is wound spirally.

3. Magnetic coil according to claim 1 or 2, characterized in that the current-carrying winding (310, 320) and the hollow body winding (210, 220, 230) substantially the same winding eye (11) and / or in a direction perpendicular to the coil longitudinal axis substantially the same Inner and / or outer dimensions (d _x , d _a ) have.

4. Magnetic coil according to one of the preceding claims, characterized in that the hollow body winding (210, 220, 230) has a hollow body (211, 221, 231) which is encased by an electrically insulating material (212, 222, 232).

5. Magnetic coil according to one of the preceding claims, characterized in that the current-carrying winding (310, 320) and the hollow body winding (210, 220, 230) by means of an insulation (213, 223, 233) are electrically isolated from each other.

6. Magnetic coil according to one of the preceding claims, characterized in that the current-carrying winding (310, 320) and the hollow body winding (210, 220, 230) via a connection (313) in mechanical and in thermal contact with each other.

7. Magnetic coil according to one of the preceding claims, characterized in that the current-carrying winding (310, 320) and / or the hollow body winding (210, 220, 230) are spirally wound.

8. Magnetic coil according to one of the preceding claims, consisting of a plurality of current-carrying windings (310, 320) and a plurality of hollow body windings (210, 220, 230), wherein the current-carrying windings (310, 320) and the hollow body windings (210, 220, 230) in Direction of the coil longitudinal axis N are alternately set to each other and via a connection (313) in mechanical and thermal contact.

9. A method for producing a magnetic coil according to one of the preceding claims, characterized in that the current-carrying winding (310, 320) and the hollow body winding (210, 220, 230) are produced with one and the same winding tool.

10. The method according to claim 9, characterized in that the winding tool has a winding mandrel, wherein

- on the mandrel first the current-carrying winding is wound,

the finished current-carrying winding is taken from the mandrel,

- Then on the winding mandrel, the hollow body winding is wound,

- The finished hollow conductor winding is taken from the winding mandrel and - the current-carrying winding and the hollow body winding are mechanically connected to each other.

11. The method according to claim 9, characterized in that the winding tool has a winding mandrel, wherein

- The hollow body winding is first wound on the mandrel, - The finished hollow body winding is taken from the winding mandrel,

- Then on the winding mandrel, the current-carrying winding is wound,

- The finished current-carrying winding is taken from the winding mandrel and

- The current-carrying winding and the hollow body winding are mechanically connected to each other.