EP4141905A1 - X-ray tube with an insulating body comprising a cast body - Google Patents

Abstract

An X-ray tube (1), which has a cathode housing (2) with a radiation exit window (13), a cooled anode (4), a cathode, in particular a hot cathode (6), an insulating body (11) for electrically insulating a high-voltage potential of the anode (4) , an inflow line (9) for coolant to the anode (4) and an outflow line (10) for coolant from the anode (4), and wherein in the insulating body (11) the inflow line (9) and the outflow line (10) each have several turns (16) is characterized in that the cast body (12) comprises an inner mold (20) and at least temporarily during the manufacture of the X-ray tube (1) an outer mold (21), the anode (4) and the cathode housing ( 2) are attached to the ceramic body (3), and the cast body (12) is attached to the ceramic body (3), that the cast body (12) comprises an outer mold (21) and an inner mold (20) that in a casting space (22) between the outer mold (21) u nd the inner mold (20), the inlet line (9) and the outlet line (10) are each formed with a hose (9a, 10a), which forms the multiple windings (16), so that in the casting space (22) at least one straightening body (23 ) is arranged made of plastic, with which the hoses (9a, 10a) are aligned in the casting space (22), so that the turns (16) of the hoses (9a, 10a) respectively from the outer mold (21) and the inner mold ( 20) are spaced apart, and that the casting space (22) is filled with a casting material (32) made of plastic in a hardened state, so that the spaces between the windings (16) on the one hand and the outer mold (21) and the inner mold ( 20) on the other hand are occupied by the plastic of the at least one directional body (23) and/or the plastic of the casting material (32). With the easy-to-manufacture X-ray tube, a high dielectric strength and a compact structure can be achieved.

Description

• welche ein Kathodengehäuse mit einem Strahlungsaustrittsfenster, eine gekühlte Anode, eine Kathode, insbesondere Glühkathode, einen Isolationskörper zur elektrischen Isolation eines Hochspannungspotentials der Anode, eine Zulaufleitung für Kühlmittel zur Anode und eine Ablaufleitung für Kühlmittel von der Anode umfasst,
• und wobei im Isolationskörper die Zulaufleitung und die Ablaufleitung jeweils mehrere Windungen umfassen.

The invention relates to an X-ray tube

• which comprises a cathode housing with a radiation exit window, a cooled anode, a cathode, in particular a thermionic cathode, an insulating body for electrical insulation of a high-voltage potential of the anode, a feed line for coolant to the anode and a discharge line for coolant from the anode,
• and wherein the inflow line and the outflow line each comprise a plurality of turns in the insulating body.

Such an X-ray tube is from the WO 2008/148426 A1 (= reference [1]) became known.

X-rays are used in a variety of ways in instrumental analysis or to produce images of human and animal patients in medicine. X-rays are typically generated in an X-ray tube by emitting electrons at an electrically heated hot cathode, and accelerating the electrons in a vacuum through an electric field onto an anode, at which bremsstrahlung and characteristic X-rays corresponding to the anode target material used (e.g. B. tungsten, molybdenum or rhodium) is released.

When generating X-ray radiation, only a small part, usually around 1%, of the energy used is converted into X-ray power. The remaining part of the energy used generates heat. In order to prevent the anode from melting, it is therefore customary to cool the anode. The anode is usually cooled with a coolant that flows through the anode. The coolant is conducted through cooling channels within the anode.

During operation, the anode is typically at high-voltage potential. As a result, electrical insulation of the anode is necessary. The anode can be arranged on an electrically insulating insulating body. Coolant lines, with which the anode is supplied with the coolant, also typically run through the insulating body. Since the coolant in the anode is also at high voltage, it must be ensured that there are no voltage breakdowns via the coolant column, for which the length of the coolant column, the conductivity or dielectric strength of the coolant and the applied voltage must be selected appropriately. Only coolants with low electrical conductivity, such as deionized water (VE water), are regularly used as coolants.

Reference [1] cited at the outset shows a high-voltage X-ray tube comprising a cathode and an anode and an anode insulating element. The anode insulation element is designed as a ceramic cone and includes an opening for a high-voltage plug. An intermediate element is between the Anode insulating element and inserted into the opening for the high-voltage connector high-voltage connector. An inflow channel and an outflow channel run in the intermediate element, through which a cooling liquid, in particular a cooling oil, is conducted to the anode. The inflow and outflow channel can be guided in a spiral shape. Drilling and casting are proposed for the manufacture of line structures.

If the inflow and outflow channels are designed in a spiral shape, a longer insulation distance can be made available in the cooling liquid. However, spiral line structures within the intermediate body are difficult to implement in production. Reference [1] does not provide any further details as to how spiral-shaped inlet and outlet lines are to be manufactured, particularly in the intermediate body.

Imprecise placement of the inlet line and the outlet line in an insulating body, in particular too small a distance between turns or to an inner wall or outer wall of the insulating body, can lead to voltage flashovers and damage to the x-ray tube.

From the DE 10 2017 217 181 B3 (= reference [2]) and from the US 10,714,300 B2 (= reference [3]) a standing anode for an X-ray radiator has become known. The standing anode includes an anode base body. In the anode base body there are spiral cooling sections through which a cooling fluid flows to cool the anode.

The anode base body can be better cooled by the spiral cooling sections. However, no further details are given as to how an insulating body for electrical insulation of the anode base body could look like and how an inflow channel and an outflow channel for the cooling fluid could be designed.

Another x-ray tube is the OEG 9X series x-ray tubes from Varex Imaging Corporation, Salt Lake City, UT 84104, USA (formerly Varian Medical Systems), cf. the company publication "OEG-92J Industrial X-Ray tube", version 2021 (=reference [4]). An X-ray tube of this series essentially comprises an anode at high voltage potential which is attached to an annular glass element which is double U-shaped in cross-section. An oil-filled hollow body connects to the underside of the glass element facing away from the anode. A coolant line leads in the oil-filled hollow body from a rear part of the x-ray tube through the glass element to the anode and back again into the rear part of the x-ray tube. The coolant line runs in the rear part of the X-ray tube with coils around a high-voltage connection. The coils abut axially against one another and radially outward against a plastic wall.

The coils retain a certain mobility in the oil, which can promote voltage breakdowns. The filaments lying against one another also have a rather low dielectric strength. A comparatively large length of the coolant line is required in order to avoid voltage breakdowns, and accordingly this design has a relatively large length. Furthermore, even a small leak in the hollow body of the X-ray tube can result in oil escaping and the rest of the X-ray tube and the environment being contaminated. This contamination with oil is often difficult to remove.

From the DE 10 2008 017 153 A1 (=Reference [5]) a cooled radiation generator has become known. The radiation generator includes a protective tube housing which is filled with a coolant. A radiation generating tube with a cathode and an anode is arranged inside the protective tube housing filled with the cooling liquid. A flow channel, which is filled with a cooling medium, is formed on the protective tube housing. The inside of the tube protection housing can be cooled with the flow channel. The cooling medium is fed into and out of the flow channel via an inlet and outlet line.

From the U.S. 2012/0 076 278 A1 (=Reference [6]) a cooled X-ray tube has become known. The x-ray tube includes a housing, a cathode assembly having a cathode attached to the housing, a stator assembly having a rotating anode attached to the housing, and an x-ray window attached to a window frame on the housing. Liquid cooling channels are formed in the housing and in the stator assembly. Coolant can be fed into and discharged from the liquid-cooling channels via connections on the housing and the stator assembly. The housing and the stator assembly can be cooled by means of the coolant.

From the JP 2015-232 944 A (=Reference [7]) an X-ray tube device has become known with which damage to a vacuum envelope of the X-ray tube device can be prevented. The X-ray tube device includes an X-ray tube, a stress relaxation film, and a molding. The x-ray tube includes a cathode, an anode, and the vacuum envelope. The film is adhered to the outer surface of the vacuum envelope. The molding fully covers and is bonded to the vacuum envelope and film. With the stress relaxation film, the stress applied from the outside of the vacuum envelope can be reduced.

object of the invention

It is the object of the present invention to present an x-ray tube that is easy to manufacture and with which a high dielectric strength and a compact structure can be achieved.

Description of the invention

• dass der Isolationskörper einen Keramikkörper und einen Gusskörper umfasst, wobei die Anode und das Kathodengehäuse auf dem Keramikkörper befestigt sind, und der Gusskörper am Keramikkörper befestigt ist,
• dass der Gusskörper eine innere Gussform und zumindest zeitweise während der Herstellung der Röntgenröhre eine äußere Gussform umfasst,
• dass in einem Gussraum zwischen der äußeren Gussform und der inneren Gussform die Zulaufleitung und die Ablaufleitung jeweils mit einem Schlauch ausgebildet sind, der die mehreren Windungen ausbildet,
• dass im Gussraum wenigstens ein Richtkörper aus Kunststoff angeordnet ist, mit dem die Schläuche im Gussraum ausgerichtet sind, so dass die Windungen der Schläuche jeweils von der äußeren Gussform und der inneren Gussform beabstandet sind,
• und dass der Gussraum mit einem Gussmaterial aus Kunststoff in einem ausgehärteten Zustand aufgefüllt ist, so dass die Zwischenräume zwischen den Windungen einerseits und der äußeren Gussform und der inneren Gussform andererseits von dem Kunststoff des wenigstens einen Richtkörpers und/oder dem Kunststoff des Gussmaterials eingenommen sind.

This object is achieved according to the invention by an X-ray tube of the type mentioned at the outset, which is characterized in that

• that the insulating body comprises a ceramic body and a cast body, the anode and the cathode housing being fixed on the ceramic body, and the cast body being fixed on the ceramic body,
• that the cast body comprises an inner mold and at least temporarily during manufacture of the X-ray tube an outer mold,
• that in a casting space between the outer mold and the inner mold, the inlet pipe and the outlet pipe are each formed with a hose that forms the plurality of turns,
• that at least one straightening body made of plastic is arranged in the casting space, with which the hoses are aligned in the casting space, so that the windings of the hoses are spaced apart from the outer mold and the inner mold,
• and that the casting space is filled with a plastic casting material in a hardened state, so that the spaces between the windings on the one hand and the outer mold and the inner mold on the other hand are occupied by the plastic of the at least one directional body and/or the plastic of the casting material.

The present invention proposes using at least one straightening body made of plastic in order to arrange the hoses with the multiple turns in the casting space. The at least one straightening body enables a defined and precise arrangement of the hoses in the casting space, in particular during the casting of the casting material and until the casting material has hardened; thereafter, the defined and exact arrangement will continue to be maintained.

The straightening body (auxiliary body) guides and stabilizes the hoses in the casting space. With the at least one straightening body, the hoses can be positioned safely and easily in such a way that the hoses do not directly touch either the inner mold or the outer mold. This can prevent flashovers from the hoses or the coolant contained therein to the inner and outer mold (or the outside of the filled casting space) during operation of the x-ray tube, thus avoiding damage to the x-ray tube.

The straightening bodies also enable a defined, for example uniform, arrangement of the hoses, in particular in the radial direction and/or axial direction.

Because the hoses can be positioned exactly in the cast body, i.e. the positioning tolerances are small, only these small positioning tolerances need to be taken into account when designing the X-ray tube with regard to the high voltage (and associated dielectric strength) desired during operation. In particular, a minimum spacing of hose sections can be ensured via the straightening bodies. In other words, less safety margin is required when the hoses are spaced apart from the inner and outer mold, or preferably between the turns of the hoses themselves. As a result, the space requirement of the hoses, which are wound several times, can be reduced and the x-ray tube can be made even more compact, in particular more compact in the radial and/or axial direction, depending on the design.

The inlet line and the outlet line generally run essentially helically (helically) around a tube axis of the X-ray tube and thereby form a double helix structure (i.e. the individual turns can be assigned to the inlet line and the outlet line alternately); the double helix can be cylindrical (straight) or conical (tapering). The feed line and the discharge line preferably run in a similar (symmetrical) manner around the tube axis, in particular with the same (local) pitch and the same (local) radius, with the feed line and the discharge line being arranged rotated by 180° about the tube axis with respect to one another.

The plastic casting material is poured into the casting chamber in a liquid state. For this purpose, the X-ray tube can be set up in such a way that the anode points to the support surface; an opening leading into the casting space faces up in the opposite direction. The liquid casting material can accumulate in the casting space (between the inner mold and the outer mold). Distribute evenly without creating gaps or cavities. In particular, the casting material can also be distributed between the hoses, which are held in position by the at least one directional body.

The casting material is then hardened, which can be done, for example, by waiting and/or heat treatment, depending on the material system, and retains its shape in the hardened state. If desired, the outer mold can be removed from the rest of the cast body (in particular from the hardened cast material of the filled cast space) in the hardened state of the cast material. In the hardened state, the plastic casting material - possibly together with the plastic material of the at least one straightening body - separates the hoses permanently from the walls of the inner mold and the outer mold (or the outside of the filled casting space) and preferably also separates the hoses from one another, so that it is no longer possible for the hoses to come into contact with the walls, and preferably also with each other. As a result, the risk of a flashover between the hoses and the walls during operation of the X-ray tube can be minimized; With cast material between the hoses, the cast material can also help to minimize the risk of voltage flashovers between the hoses or the adjacent windings, which means that the thickness of the hose walls can be reduced or the dielectric strength of the hose material becomes less relevant. Furthermore, the ceramic body can be connected to the cast body tightly and without gaps or cavities; Typically, the cast body is already mechanically fastened well to the ceramic body by casting the cast body onto the ceramic body.

As a plastic, the cast material has good dielectric strength, which means that flashovers and thus damage to the components of the X-ray tube can be avoided with a compact design. The use of the cast material eliminates the need for an oil-filled hollow body with electrically insulating oil through which the hoses are routed. The hardened casting material can still be flexible ("soft") to a certain extent, but is no longer flowable and, in particular, no longer liquid.

The anode can be attached to the ceramic body in a simple manner and in a vacuum-tight manner, for example by soldering it onto a metallized surface of the ceramic body, or by gluing it to the ceramic body in a temperature- and vacuum-resistant manner. The design of the ceramic body also allows the creepage distance to be adjusted both on the side of the ceramic body that faces the anode and on the side of the ceramic body that faces the cast body, thereby improving the dielectric strength. The ceramic body can be made of Al ₂ O ₃ or ZrO ₂ , for example.

The hoses have a certain pliability or flexibility, in particular for laying in the casting space, with the hoses being aligned in the casting space via the at least one straightening body. The hoses preferably have a minimum degree of inherent rigidity, as a result of which the respective hose has a basic geometry that is adapted to the desired hose geometry in the X-ray tube. Furthermore, the inner walls of the hoses can be designed in such a way that they have a low degree of roughness and thus oppose a low flow resistance to the coolant flowing through the hoses. In this way, an efficient inflow and outflow of coolant to the anode can be set up. The inner walls of the hose can also be additionally coated for this purpose, in particular in order to adjust the surface tension between the coolant and the hose.

As a rule, it is possible without any problems to design the hoses to be liquid-tight. As a result, liquid leaks in the insulating body can be avoided, which could lead, for example, to unwanted flashovers in the insulating body and thus damage the components of the x-ray tube.

For example, fully desalinated ("deionized") water (VE water), single-distilled water or water that has been distilled several times can be used as a coolant. Water-based coolants are due to their high specific heat capacity preferred; In addition to water-based coolants, however, other coolants can also be used, for example an oil, in particular silicone oil. The coolant preferably has a low electrical conductivity of less than 1 μS/cm. Since the length of the required coolant column and thus the length of the hoses filled with coolant depends, among other things, on the conductance of the coolant, the length of the hoses can be reduced by suitably selecting a coolant with a low conductance, thereby reducing the space required for the X-ray tube.

The x-ray tube of the present invention is typically grounded with the cathode (notwithstanding the cathode filament current) and the anode at a high voltage (positive) potential. It is also possible within the scope of the invention to connect the cathode to a (negative) high-voltage potential, if desired.

Preferred embodiments of the invention

In a preferred embodiment of the X-ray tube according to the invention, it is provided that the hoses are also aligned in the casting space with the at least one aligning body, so that the windings of the hoses are also spaced apart,
and that the casting space is further filled with the casting material, so that the intermediate spaces between the turns are also occupied by the plastic of the at least one directional body and/or the plastic of the casting material. The turns of the hoses can be reliably and precisely spaced apart from one another in the casting space by the at least one straightening body, in particular with regard to the axial direction. The distance between the windings of the hoses can be set so precisely that, when the x-ray tube is in operation at a given high voltage, there are no flashovers between the windings of the hoses or the coolant contained therein, which would damage the x-ray tube. Due to the precise alignment, the space in the X-ray tube or in its insulating body can be used efficiently and the space required for the hoses can thus be kept low become. The X-ray tube can therefore be made even more compact. The hoses can be held securely in their position and spaced apart from one another while the casting mold is being filled with the casting material with the straightening bodies. When the casting mold is filled with the casting material in the liquid state, the casting material can be distributed evenly in the interstices of the turns without the formation of gaps or cavities.

A further preferred embodiment is characterized in that the ceramic body has a circumferential recess between the cathode housing and the anode on a front side facing the anode, and that the ceramic body has a central recess on a back side of the ceramic body facing the cast body. The circumferential groove lengthens the path between the anode and the cathode case (which is grounded) at the front of the ceramic body, establishing a long creepage distance. The central relief lengthens the path between structures connected to the anode that pass through the ceramic body (typically a high voltage feedthrough and usually also tubes for the cooling liquid) and the outside of the insulating body (which is usually grounded) at the back of the ceramic body, thereby a long creepage distance is set up between the ceramic body and the cast body. In longitudinal section, the ceramic body can then be approximately W-shaped; the ceramic body is then also referred to as crown-shaped due to the multiple indentations. The circumferential groove is typically V-shaped or U-shaped (on each side in longitudinal section) and the central recess is also typically (inverted) V-shaped or U-shaped in longitudinal section along the tube axis. It should be noted that in some embodiments only the center relief is provided, and in other embodiments both the circumferential indentation and the center relief are provided.

In a preferred development of this embodiment, the hoses are partially arranged in a region of the central recess of the ceramic body, in particular with at least half a turn of the Hoses and / or at least 10% of the length of the hoses is arranged in the central recess of the ceramic body. This allows the recovery space to be used efficiently and the hoses to be connected closer to the anode (e.g. to tubes/pipe sockets protruding through the ceramic body), thus increasing the length of the hoses and thus the path for the high voltage to drop from the anode . The recess typically extends into the ceramic body in the direction of the tube axis over at least 50% of the axial extent of the ceramic body. The recess can be conically shaped, preferably with the widest radius of the recess on the rear side of the ceramic body extending over at least 2/3 of the outer radius of the ceramic body on its rear side.

Also preferred is an embodiment in which the inner mold is designed as a socket for a high-voltage plug for connection to the anode. The anode can be connected to the high voltage in a simple, particularly reversible manner by means of the socket and the high-voltage plug. The socket, which is made of electrically insulating material (usually a plastic), can provide the necessary creepage distance to prevent flashovers from the applied high voltage from a connection pole (usually at the socket base) to the grounded parts of the X-ray tube (e.g. the coolant connections ) or to prevent the cable shield. In addition, the socket can protect the high-voltage connection of the high-voltage plug (which protrudes into the socket and contacts the connection pole when connected) from accidental contact. The socket is typically located radially centrally in the cast body on the side of the insulating body facing away from the anode, and the inlet line and the outlet line preferably also run around the socket, as a result of which a particularly compact and electrostatically stable coaxial structure of the high-voltage potentials can be achieved.

Also preferred is an alternative embodiment, which is characterized in that the inner mold is designed as a cable, which has a includes an insulating jacket and a core running in the jacket, to which the anode is connected. This embodiment is particularly inexpensive and can achieve an even more compact structure, particularly in the radial direction. The cable can be cast directly with the casting material.

An embodiment in which the at least one directional body and the casting material consist of the same plastic is particularly preferred. By using the same plastic for the aligning body or bodies and the casting material, a particularly good connection between the aligning body and the casting material is achieved. The result is a largely monolithic cast body with hoses for the coolant running in a defined manner on the inside. Distortions of field lines at the interface between the directional body and the cast material are minimized, and leakage currents at these interfaces are also minimized. The structure of the cast body is therefore far less susceptible to voltage breakdowns. By using the same plastics for the or the directional body and the cast material, the structure of the x-ray tube can become even more compact due to the improved dielectric strength.

In a preferred development of this embodiment, the plastic of the casting material includes a silicone or an epoxy resin or a polyurethane. These plastics have proven particularly useful in practice. The plastics are inexpensive to purchase, can be easily cast in the liquid state, can be hardened and have good electrical insulation properties. In addition, these materials are only subject to minor aging effects (especially in comparison to insulating oil).

• zwischen der inneren Gussform und der äußeren Gussform
• und/oder zwischen den Schläuchen einerseits und der inneren Gussform oder der äußeren Gussform andererseits
  eingeklemmt angeordnet sind. Durch die Nutzung mehrerer Richtkörper lassen sich die Schläuche noch besser im Gussraum ausrichten und können besonders leicht in Position gehalten werden. Durch Verklemmung der Richtkörper an den Schläuchen und den Gussformen ist auf einfache Weise ein sicherer Halt der Richtkörper, insbesondere für den Gussvorgang, möglich. Es ist alternativ auch möglich, dass sich die Richtkörper aneinander und zumindest an der äußeren Gussform klemmend abstützen. Allgemein liegen die Richtkörper an den Schläuchen an, um diese (während des Gussprozesses) ausgerichtet zu halten.

In a particularly preferred embodiment, it is provided that several straightening bodies are arranged in the casting space,
in particular, the directional body respectively

• between the inner mold and the outer mold
• and/or between the hoses on the one hand and the inner mold or the outer mold on the other hand
  are clamped. By using several straightening bodies, the hoses can be aligned even better in the casting space and can be held in position particularly easily. By jamming the straightening bodies on the hoses and the casting molds, the straightening bodies can be held securely, in particular for the casting process, in a simple manner. Alternatively, it is also possible for the straightening bodies to be supported on one another and at least on the outer mold in a clamped manner. Generally, the straighteners abut the hoses to keep them aligned (during the casting process).

A further development of this embodiment is advantageous, in which the aligning bodies are arranged at angular positions in a respective cutting plane perpendicular to a tube axis of the x-ray tube, the angular positions forming a rotationally symmetrical arrangement with respect to the tube axis. Due to the rotationally symmetrical arrangement of the straightening bodies, they can act uniformly on the hoses from several directions, so that the hoses are subjected to an approximately uniform radial force (clamping force) over the circumference of their windings and/or are radially aligned. As a result, irregularities in the windings can be minimized and the hoses can be supported particularly stably by the straightening bodies.

A further development of this further development is also advantageous, which is characterized in that N straightening bodies support the hoses towards the inner cast body, and N straightening bodies support the hoses towards the outer cast body, and the rotationally symmetrical arrangement of the angular positions has an N-fold number, with N is a natural number with N≥2. This distribution of the straightening bodies has proven particularly useful in practice. This allows the hoses to be positioned particularly precisely in the casting space and held in position.

• an identischen Winkelpositionen, oder
• an um 360°/(2^∗N) zueinander versetzten Winkelpositionen. Die Positionierung der Richtkörper an identischen Winkelpositionen ermöglicht ein besonders einfaches Einklemmen eines jeweiligen Schlauchabschnitts zwischen den sich gegenüberliegenden Richtkörpern; hierdurch kann auch eine sehr genaue Ausrichtung der Schläuche erfolgen, insbesondere mit minimierten Stauchungen der Windungen. In manchen Ausführungsformen kann bei identischen Winkelpositionen von Richtkörpern auch vorgesehen sein, dass die Richtkörper sich gegenseitig abstützen. Durch die Positionierung der Richtkörper an unterschiedlichen Winkelpositionen kann die Ausrichtung der Schläuche in Umfangsrichtung an besonders vielen Stellen erfolgen, wodurch die Ausrichtung der Schläuche insbesondere in axialer Richtung besonders präzise gestaltet werden kann. Man beachte, dass die N Richtkörper, die die Schläuche zum inneren Gusskörper hin abstützen, und die N Richtkörper, die die Schläuche zum äußeren Gusskörper hin abstützen, bei Anordnung an identischer Winkelposition einstückig (etwa als Lochplatte) oder auch mehrstückig (etwa als gegenüberliegende Nutenriegel) ausgebildet sein können.

It is just as advantageous if the N straightening bodies, which support the hoses toward the inner cast body, and the N straightening bodies, which support the hoses toward the outer cast body, are arranged in a respective sectional plane with respect to the tube axis

• at identical angular positions, or
• at angular positions offset by 360°/(2 ^∗ N) from one another. The positioning of the straightening bodies at identical angular positions enables a particular hose section to be clamped in particularly easily between the straightening bodies lying opposite one another; This also allows the hoses to be aligned very precisely, in particular with minimized compression of the windings. In some embodiments, if the angular positions of the directional bodies are identical, it can also be provided that the directional bodies support one another. By positioning the straightening bodies at different angular positions, the hoses can be aligned in the circumferential direction at a particularly large number of points, as a result of which the hoses can be aligned particularly precisely, particularly in the axial direction. It should be noted that the N straightening bodies, which support the hoses towards the inner cast body, and the N straightening bodies, which support the hoses towards the outer cast body, can be in one piece (e.g. as a perforated plate) or in several pieces (e.g. as opposite slot bars) when arranged at an identical angular position ) can be trained.

Also preferred is an embodiment in which one or more straightening bodies of the at least one straightening body are designed as a perforated plate, comprising a plate and a number of holes in the plate, through which the hoses are routed,
in particular wherein a respective perforated plate is arranged clamped between the inner mold and the outer mold. Such perforated plates are easy to manufacture and easy to position in the mold. The hoses are fed through the holes of the die plate (typically before the die plate and hoses are placed between the outer mold and the inner mold). An even arrangement of the hoses is easily possible due to the given structure of the perforated plate. The distance between the hoses can be adjusted via the distances between the individual holes. Likewise, the distance between the hoses and the inner and outer mold can be adjusted via the distance between the holes and the side edges of the perforated plate when the side edges rest against the inner and outer mold in the clamped state.

A further embodiment is advantageous, which is characterized in that one or more straightening bodies of the at least one straightening body are designed as a slot bar, comprising a bar and a number of grooves, in particular semicircular grooves, into which the hoses are inserted,
in particular, a respective slot bar being clamped between the hoses on the one hand and the inner mold or the outer mold on the other hand. Such slot bolts are particularly easy to manufacture. The slot bars can be arranged easily and flexibly on the inner mold and/or the outer mold. The hoses are placed in the grooves of the slotted bar and thereby aligned. By clamping the slot bars between the hoses and one of the molds, the slot bars can be easily fixed for the casting process.

In an advantageous further development of this embodiment, slot bars, which support hoses toward the inner cast body, and slot bars, which support hoses toward the outer cast body, are arranged in pairs opposite one another. As a result, the hoses can be held exactly in position in a simple manner, in particular with the hoses being clamped between the opposite grooved bars. With a corresponding size of the slot bolts, the slot bolts can also support each other.

Equally advantageous is an embodiment in which the windings of the hoses are wound around a tube axis and lined up along a tube axis. In this way, the hoses can be easily arranged. The windings of the hoses can be arranged to save space.

A further development of this embodiment is also advantageous, in which the windings have a constant radius with respect to the tube axis, in particular with the outer mold and the inner mold being designed essentially in the shape of a cylinder jacket and coaxial to the tube axis, so that the windings have a constant radial distance from the outer mold and furthermore the windings have a constant radial distance to the inner mould. This can be set up particularly easily and precisely in practice.

A further development of this development is particularly advantageous, in which the windings have a constant spacing from one another in the axial direction. This can also be set up easily and precisely in practice. The constant (equal) spacing of the turns of the hoses, with a constant radius of the turns at the same time, distributes the voltage drop over the length of the coolant column evenly over all turns; the potential difference between adjacent turns (at the same angular positions in each case) is the same for all turns. As a result, optimal use of space in the cast body can be achieved with a desired dielectric strength between the turns of the hoses.

Also advantageous is an alternative development of the above embodiment, in which the windings have a radius with respect to the tube axis that increases away from the anode.
in particular wherein the outer mold and the inner mold are essentially cylindrical and coaxial with the tube axis, so that the windings have a radial distance from the outer mold that decreases away from the anode, and the windings have a radial distance from the inner mold that increases away from the anode exhibit. A comparatively high potential still prevails in the hose sections that are close to the anode with respect to the coolant path. Due to the still small radius of the windings near the anode, a larger radial distance to the outer mold (which typically has contact with the ground) is maintained here, so that better dielectric strength is achieved in this area. Conversely, only a low potential (closer to ground) is present in the hose sections that are far from the anode with respect to the coolant path. Due to the large radius of the windings far from the anode, there is a larger radial distance to the inner mold (inside a conductor carrying the high-voltage potential is arranged during operation), so that better dielectric strength is also achieved in this area. As a result, the installation space in the X-ray tube can be used optimally.

• einen konstanten axialen Abstand zueinander
• oder einen von der Anode weg zunehmenden axialen Abstand zueinander aufweisen. Ein konstanter axiale Abstand der Windungen zueinander kann besonders einfach eingerichtet werden. Durch einen von der Anode weg zunehmenden axialen Abstand der Windungen zueinander, bei gleichzeitig zunehmendem Radius der Windungen, kann die Durchschlagsfestigkeit noch weiter verbessert werden. Durch den von der Anode weg zunehmenden Radius der Windungen erhöht sich der Spannungsabfall über das Kühlmittel pro Windung von der Anode weg. Dadurch erhöht sich die Potentialdifferenz zwischen benachbarten Windungen (an jeweils gleichen Winkelpositionen) von der Anode weg, was die Gefahr von Spannungsüberschlägen erhöht. Durch den von der Anode weg zunehmenden axialen Abstand kann dies bezüglich der Durchschlagfestigkeit (zumindest teilweise) kompensiert werden. Bevorzugt verhalten sich die axialen Abstände der Windungen proportional zu den Radien der Windungen; hierdurch wird ein überall ungefähr gleicher Spannungsabfall pro axialer Entfernung (bzw. eine überall gleiche Feldstärke) im Gusskörper zwischen den Windungen erreicht, soweit er durch das lineare Abfallen der Hochspannung der Anode über die Länge der Schläuche im Kühlmittel bedingt ist. Der Bauraum in der Röntgenröhre wird optimal genutzt.

A further development of this development is also advantageous, which is characterized in that the windings

• a constant axial distance from each other
• or have an increasing axial spacing away from the anode. A constant axial distance between the turns can be set up particularly easily. The dielectric strength can be further improved by increasing the axial distance between the windings away from the anode and at the same time increasing the radius of the windings. As the radius of the turns increases away from the anode, the voltage drop across the coolant per turn away from the anode increases. This increases the potential difference between adjacent turns (at the same angular positions in each case) away from the anode, which increases the risk of voltage flashovers. This can be (at least partially) compensated for with regard to the dielectric strength by the increasing axial distance away from the anode. The axial distances between the windings are preferably proportional to the radii of the windings; This results in a voltage drop that is approximately the same everywhere per axial distance (or a field strength that is the same everywhere) in the cast body between the windings, insofar as it is caused by the linear drop in the high voltage of the anode over the length of the hoses in the coolant. The installation space in the X-ray tube is used optimally.

An embodiment of the X-ray tube according to the invention is preferred, in which the outer mold remains on the rest of the cast body after the production of the X-ray tube. In other words, the outer mold required during casting is not removed after casting, but remains part of the x-ray tube during its operation. This is particularly easy. The outer mold can also mechanically stabilize the X-ray tube during operation. If necessary, can the outer mold can be wrapped with a material that conducts electricity well and/or is highly absorbent of X-ray radiation, for example a lead foil, in order to ensure grounding and protection against radiation.

In an alternative embodiment it is provided that after the manufacture of the x-ray tube the outer mold is removed from the rest of the cast body. In other words, the casting mold required during casting is only arranged on the ceramic body during the casting process and is no longer part of the X-ray tube in its operation. This makes it possible to use one outer mold for the manufacture of a large number of X-ray tubes. If necessary, the rest of the cast body can be wrapped in a material that conducts electricity well and/or is highly absorbent of X-rays, e.g. lead foil, to ensure grounding and radiation protection.

1. a) zur Einrichtung des Gussraums wird die äußere Gussform an einer der Anode abgewandten Rückseite des Keramikkörper abdichtend angeordnet und die innere Gussform wird vor der Rückseite des Keramikkörpers angeordnet, und im Gussraum zwischen der inneren Gussform und der äußeren Gussform werden der wenigstens eine Richtkörper aus Kunststoff und die Schläuche angeordnet, wobei mit dem wenigstens einen Richtkörper die Schläuche im Gussraum so ausgerichtet werden, dass die Windungen der Schläuche jeweils von der äußeren Gussform und der inneren Gussform beabstandet sind, und bevorzugt auch die Windungen voneinander beabstandet sind,
2. b) der Gussraum wird mit dem Gussmaterial aus Kunststoff in einem flüssigen Zustand aufgefüllt, so dass die Zwischenräume zwischen den Windungen einerseits und der äußeren Gussform und der inneren Gussform andererseits, und bevorzugt auch die Zwischenräume zwischen den Windungen untereinander, von dem Kunststoff des wenigstens einen Richtkörpers und/oder dem Kunststoff des Gussmaterials eingenommen werden,
3. c) das Gussmaterial aus Kunststoff wird ausgehärtet. Mit diesem Herstellungsverfahren kann auf einfache Weise eine Röntgenröhre gefertigt werden, mit der eine hohe elektrische Durchschlagfestigkeit und ein kompakter Aufbau erreichbar ist. In den abgedichteten Gussraum kann das Gussmaterial im flüssigen Zustand problemlos und sauber gefüllt werden, und das Gussmaterial erfüllt den zur Verfügung gestellten Gussraum selbsttätig und vollständig, insbesondere ohne Lücken und Hohlräume. Die Richtkörper und Schläuche werden vom Gussmaterial eingeschlossen, und es ergibt sich ein Gusskörper aus Vollmaterial, das eine gute Durchschlagfestigkeit zur Verfügung stellen kann. Durch den wenigstens einen Richtkörper können die Schläuche besonders einfach und exakt im Gussraum angeordnet werden, wobei gewünschte Abstände zur inneren Gussform und äußeren Gussform eingestellt werden können, insbesondere mit geringen Toleranzen. Weiterhin können die Schläuche durch den wenigstens einen Richtkörper mit gewünschten Abständen der Windungen zueinander angeordnet werden, insbesondere mit geringen Toleranzen. Der wenigstens eine Richtkörper hält die Schläuche während des Auffüllens des Gussraums mit dem Gussmaterial im flüssigen Zustand stabil und in Position. Nach dem Aushärten des Gussmaterials bleiben die Schläuche weiterhin in den gewünschten, exakt eingerichteten Positionen, wobei sie weiterhin durch die Richtkörper und nun auch durch das ausgehärtete Gussmaterial gehalten werden.

Also falling within the scope of the present invention is a method of manufacturing an x-ray tube as described above,
with the steps:

1. a) To set up the casting space, the outer casting mold is arranged in a sealing manner on a rear side of the ceramic body facing away from the anode and the inner casting mold is arranged in front of the rear side of the ceramic body, and the at least one plastic straightening body is placed in the casting chamber between the inner casting mold and the outer casting mold and the hoses are arranged, the hoses being aligned in the casting space with the at least one straightening body in such a way that the coils of the hoses are spaced apart from the outer mold and the inner mold, and preferably the coils are also spaced apart from one another,
2. b) the casting space is filled with the casting material made of plastic in a liquid state, so that the spaces between the turns on the one hand and the outer mold and the inner mold on the other hand, and preferably also the spaces between the turns among themselves, from the plastic of the at least one directional body and/or the plastic of the casting material,
3. c) the plastic casting material is cured. With this manufacturing method, an x-ray tube can be manufactured in a simple manner, with which a high electrical breakdown strength and a compact structure can be achieved. The casting material in the liquid state can be filled easily and cleanly into the sealed casting space, and the casting material automatically and completely fills the casting space provided, in particular without gaps and cavities. The dies and hoses are encapsulated by the cast material, resulting in a solid cast body that can provide good dielectric strength. The at least one straightening body allows the hoses to be arranged particularly easily and precisely in the casting space, with the desired distances to the inner mold and outer mold being able to be set, in particular with low tolerances. Furthermore, the hoses can be arranged by the at least one straightening body with the desired distances between the turns, in particular with small tolerances. The at least one straightening body keeps the hoses stable and in position during the filling of the casting space with the casting material in the liquid state. After the casting material has hardened, the hoses continue to remain in the desired, precisely set positions, while still being held by the straightening bodies and now also by the hardened casting material.

The individual steps of step a) can in principle take place in any order. Typically, the at least one straightening body is mechanically clamped as part of step a) with hoses resting on the straightening body, typically between the inner and outer mold (especially in the case of a perforated plate), or between the hoses on the one hand and the inner or outer mold on the other (especially in the case of slot bolts).

In order to achieve a better connection between the aligning body and the cast material, the plastic of the aligning body and the plastic of the cast material can be the same plastic. If the plastic of the (at least one) directional body and the plastic of the casting material are the same plastic, the (at least one) directional body is typically manufactured and cured in advance before it is inserted into the casting space.

Note that at the beginning of step a) typically the tube head (particularly the cathode housing and the anode) has already been placed on the ceramic body. An x-ray tube according to the invention, as described above, including the embodiments described above, can be produced with the method according to the invention.

In a preferred variant of the method according to the invention it is provided that after step c) the outer mold remains on the rest of the cast body; accordingly, in this variant, an x-ray tube is produced in which, after the production of the x-ray tube, the outer mold remains on the rest of the cast body. This is particularly easy to implement; in particular, no demolding step for the outer mold is required after casting.

In another variant of the method according to the invention, the method also includes one step
d) the outer mold is removed from the remainder of the casting; according to this variant, an X-ray tube is produced in which, after the production of the X-ray tube, the outer mold is removed from the rest of the cast body. The outer mold can then be used in the manufacture of a variety of X-ray tubes; alternatively, however, the outer mold can be used only once if desired, particularly if the molding requires the outer mold to be destroyed.

Further advantages of the invention result from the description and the drawing. Likewise, the features mentioned above and those detailed below can be used according to the invention individually or collectively in any combination. The embodiments shown and described are not to be understood as an exhaustive list, but rather have an exemplary character for the description of the invention.

Detailed description of the invention and drawings

1

shows a first embodiment of an X-ray tube according to the invention in a schematic longitudinal section, with slot bars and windings of the hoses with a uniform radius;

2

shows in a schematic longitudinal section a second embodiment of an X-ray tube according to the invention, with perforated plates and windings of the hoses with a uniform radius;

3

shows in a schematic longitudinal section a third embodiment of an X-ray tube according to the invention, with slot bars and windings of the hoses with variable radius and crown-shaped ceramic body;

4

shows a fourth embodiment of an X-ray tube according to the invention in a schematic longitudinal section, with perforated plates and windings of the hoses with a variable radius and variable axial spacing;

figure 5

shows a schematic cross section through an X-ray tube according to the invention, with aligning bodies on angular positions with a rotationally symmetrical arrangement of the angular positions, with two inner slot bars and two outer slot bars lying opposite one another;

6

shows a schematic cross section through an X-ray tube according to the invention, with aligning bodies on angular positions with a rotationally symmetrical arrangement of the angular positions, with four inner slot bars and four outer slot bars lying opposite one another;

7

shows a schematic cross section through an X-ray tube according to the invention, with aligning bodies at angular positions with a rotationally symmetrical arrangement of the angular positions, two inner slot bars being offset by 90° to two outer slot bars;

8

shows a schematic cross section through an X-ray tube according to the invention, with aligning bodies at angular positions with a rotationally symmetrical arrangement of the angular positions, with three perforated plates being arranged offset from one another by 120°;

9

shows a partially manufactured x-ray tube in a schematic longitudinal section, with cathode housing and ceramic body, which is manufactured according to the invention to form a complete x-ray tube;

10

shows the partially manufactured X-ray tube from 9 , with the inner and outer molds positioned, forming a casting space, with the straightening bodies and with the hoses positioned;

11

shows the X-ray tube from 10 , now fully manufactured, the casting space being filled with a casting compound;

12

shows the X-ray tube of FIG. 1 in a variant for the invention 11 , after removing the outer mold.

The 1 shows a first embodiment of an X-ray tube 1 according to the invention in a schematic longitudinal section. The x-ray tube 1 extends along a tube axis RA.

The x-ray tube 1 comprises a cathode housing 2 which is attached to a ceramic body 3 in a vacuum-tight manner, for example by soldering. In addition, an anode 4 (here with an approximately cylindrical anode body) is arranged inside the cathode housing 2, which is also mounted on the ceramic body 3 is attached in a vacuum-tight manner, typically also by soldering. The cathode housing 2, the ceramic body 3 and the anode 4 delimit an evacuated space 5.

In the evacuated space 5 is a cathode, here a thermionic cathode 6, arranged, typically formed with incandescent filaments. In the embodiment shown, the hot cathode 6 can be supplied with an electric current via a ground connection 7a and a current connection 7b, which are led through the cathode housing 2 in a vacuum-tight manner. The electric current is typically an alternating current, preferably of low voltage, mostly with a maximum voltage amplitude of 24 V or less. The hot cathode 6 can be made to glow by means of this electrical current (also called heating current), as a result of which electrons emerge from the hot cathode 6 .

During operation, the anode 4 is at a positive high-voltage potential (typically 20 kV to 60 kV, possibly more in other applications) compared to the hot cathode 6. During operation, the hot cathode 6 is grounded in the embodiment shown here, regardless of the heating current already explained . Electrons emerging from the hot cathode 6 are accelerated from the hot cathode 6 to the anode 4, here to an upper side 4a of the anode 4, by the high voltage, under the influence of a shielding 8 that is connected to ground. When they hit the anode 4, the electrons are decelerated, as a result of which X-rays are generated in the form of bremsstrahlung. In addition, electrons are knocked out of the inner shells of the atoms of the material (“target”) of the anode 4 arranged on the upper side 4a. When electrons from the outer shells fill up the inner shells of these atoms, X-rays are emitted in the form of characteristic X-rays. As a rule, a desired material is attached to the upper side 4a of the anode 4 in order to generate the X-ray radiation characteristic of this material. The x-ray radiation generated exits the x-ray tube 1 through a radiation exit window 13, here a beryllium window, and can be used for measurements, for example an x-ray fluorescence measurement on a sample, or for recording an x-ray image.

The electrons accelerated onto the anode 4 heat the anode 4, which is made of metal. In order to prevent the anode 4 from melting, the anode 4 is cooled with a coolant. In the X-ray tube 1, an inflow line 9 is formed, which conducts the coolant to the anode 4, and also an outflow line 10, which conducts the coolant away from the anode 4 again. It should be noted that the supply line 9 and the return line 10 can also be connected in reverse to the coolant flow if desired.

The anode 4, which is at high voltage potential, must be electrically isolated. In particular, voltage breakdowns on the outside of the X-ray tube 1 and other grounded structures should be prevented.

The anode 4 is electrically insulated on the X-ray tube 1 essentially by an insulating body 11 and the evacuated space 5 set up in the cathode housing 2. According to the invention, this insulating body 11 comprises the ceramic body 3 made of ceramic material, on which the anode 4 and the cathode housing 2 seated, and a cast body 12, which is attached to the back of the ceramic body 3. The ceramic body 3 consists of a vacuum-tight ceramic material, for example Al ₂ O ₃ . The cast body 12 essentially consists of a cast material 32 made of plastic. The plastic of the casting material 32 can be a silicone, for example. The inlet line 9 and the outlet line 10 are routed through the insulating body 11 to the anode 4 . The insulating body 11 (and correspondingly also the respectively associated section of the ceramic body 3 and the cast body 12) is approximately circular-cylindrical on the outside and aligned along the tube axis RA.

It should be noted that the coolant in the anode 4 is in contact with the high-voltage potential and is grounded in the area of coolant connections 9b, 10b. Accordingly, the high voltage drops over the length of the inlet line 9 and over the length of the outlet line 10 in the coolant. In order to prevent the high voltage from breaking through, a coolant is used on the one hand low electrical conductivity or high dielectric strength used, such as deionized water or a silicone oil. On the other hand, the x-ray tube 1 is designed in such a way that it allows for a large length (path length) of the inlet line 9 and the outlet line 10 in a compact space, and furthermore ensures a sufficient spacing of structures at different electrical potentials.

In the design shown, two tubes 14a, 14b, typically made of metal, lead through the ceramic body 3, to the upper end of which are connected anode channels 4b for the coolant, which run inside the anode 4, and to the lower end of which hoses 9a, 10a are connected. It should be noted that in other designs the coolant passage through the ceramic body 3 can also be designed differently, for example with coaxial tubes or tubes made of ceramic or simple holes into which plug-in connections protrude (not shown). The hoses 9a, 10a form the inlet line 9 and the outlet line 10, insofar as these run within the cast body 12. The hoses 9a, 10a are made of a plastic material. In the cast body 12, the hoses 9a, 9b each form a plurality of windings 16 in a central part, which are arranged one behind the other in the axial direction and form a double helix in this area (more on this below).

On its rear side facing away from the anode 4, the ceramic body 3 forms a central recess 15, which is cone-shaped here. In the axial direction (along the tube axis RA), the recess 15 extends over a depth TR into the ceramic body 3, which overall has an axial extent AEK. In the embodiment shown, approximately TR=0.8 ^∗ AEK; TR≥0.5 ^* AEK or also TR≥0.75 ^* AEK is generally preferred. In the radial direction (perpendicular to the tube axis RA), the recess 15 extends at its widest point on the rear side of the ceramic body 3 with a largest radius GRR, and at its end near the anode at its narrowest point with a smallest radius KRR. The ceramic body 3 has an outer radius RK in the area of its rear side; it should be noted that the ceramic body 3 has a uniform outer radius in the embodiment shown. In the shown embodiment applies approximately GRR=0.75 ^∗ RK; generally preferred is GRR≥0.5 ^∗ RK or also GRR≥0.67 ^∗ RK. Furthermore, in the embodiment shown, approximately KRR=0.53 ^∗ RK; generally preferred is KRR≥0.33 ^∗ RK or also KRR≥0.40 ^∗ RK.

The recess 15 in the ceramic body 3 allows the hoses 9a, 10a to move axially close to the anode 4, and the depth TR of the recess 15 can be used at least in part to allow the high voltage to drop via the coolant in the hoses 9a, 10a . The tubes 14a, 14b, with which the anode channels 4b are connected to the hoses 9a, 10a, can be made comparatively short. A considerable hose length, usually at least 10% of the respective total hose length or also a hose length corresponding to at least half a turn 16 (i.e. at least R ^* Pi, with R: radius of the turns 16), can be accommodated in the area of the recess 15. The recess 15 also causes a comparatively long creepage distance from the tubes 14a, 14b to the radial outside of the ceramic body 3 along the boundary surface to the cast body 12, in particular much longer than the radius RK of the ceramic body 3.

A contacting element 17 made of metal is also guided through the ceramic body 3 and connects the anode 4 to a connection pole 18 . The contacting element 17 continues to run centrally in the X-ray tube 1 through the cast body 12 and, in the embodiment shown, leads into a socket 19 for a high-voltage plug (the latter not shown), with which the high voltage for the anode 4 is connected to the connection pole 18 in the socket 19 can. The socket is made of an electrically insulating material, such as a plastic.

At the same time, the bushing 19 forms an inner mold 20 for the cast body 12 . The bushing 19 is approximately cylindrical and is aligned with the tube axis RA.

The cast body 12 also includes an outer mold 21, which is designed here as a cylinder tube, which can be made of metal or plastic, for example. The inner mold 20, the outer mold 21 and the ceramic body 3 delimit a casting space 22. In particular, the hoses 9a, 10a run in this casting space 22.

The hoses 9a, 10a are aligned in the casting space 22 with the aid of straightening bodies 23. The directional body 23 are made of plastic. The straightening bodies 23 are typically arranged in a clamped manner in the casting space 22 . In the embodiment shown, the straightening bodies 23 are designed as slot bars 24 . The slotted bolts 24 each include a bolt 24a on which a plurality of grooves 24b, here semicircular grooves, are formed. A winding 16 of a hose 9a, 10a is inserted into each groove 24b. In the embodiment shown, radially inner slot bars 25a, 25b and radially outer slot bars 26a, 26b are located opposite one another, between which the windings 16 of the hoses 9a, 10a are clamped. The slot bars 24 are respectively clamped between one of the molds 20, 21 and the hoses 9a, 10a.

The windings 16 of the hoses 9a, 10a are aligned with high accuracy by the straightening bodies 23. The distance between the individual windings 16 is set radially inwards towards the bushing 19/inner mold 20 (RAI), radially outwards towards the outer mold 21 (RAA), and in the axial direction among one another (AA). In the embodiment shown, it is ensured in the area of the turns 16 that the adjacent turns 16 of the various hoses 9a, 10a, and furthermore the hoses 9a, 10a and the inner mold 20, and finally the hoses 9a, 10a and the outer Mold 21, do not touch (i.e. AA>0, RAI>0, RAI>0). In the embodiment shown, the radial distance RAI inwards to the inner mold 20 is the same for all turns 16, the radial distance RAA outwards to the outer mold 21 is the same in each case, and the radius R of the turns 16 with respect to the X-ray axis RA is the same. In addition, for all windings 16, the axial distance AA is the same among one another.

The casting space 22 was filled with a liquid casting material 32 made of plastic, so that the entire casting space 22 that was not occupied by other structures (hoses 9a, 10a, directional body 23, contacting element 17) was filled with the casting material 32. The straightening bodies 23 ensured that the hoses 9a, 10a could not shift during the casting and during the subsequent hardening of the cast material 32, and in particular that the distances provided (e.g. RAI, RAA, AA for the respective windings 16 ) were met with a high level of accuracy. The plastic of the casting material 32 and the plastic of the directional body 23 were chosen to be the same, in particular as a silicone material. This minimizes leakage currents at the interfaces between the directional bodies 23 and the casting material 32; this interface (as far as the electrical properties are concerned) essentially disappears after the casting material 32 has hardened.

The cast body 12 engages with a conical front end 29 in the recess 15 of the ceramic body 3 and is attached to it. The X-ray tube 1 can set up good vacuum tightness and high-voltage strength with the ceramic body 3, and good water-tightness and also good high-voltage strength with the cast body 12 in a compact space. The casting material 32 is easy to handle and easy to maintain (in particular, the hardened casting material 32 can no longer leak out of the casting space 22 and shows little thermal expansion and aging, unlike an insulating oil). A long coolant column (path length of the inlet line and outlet line) can be set up, in particular using installation space axially and radially within the ceramic body 3. The hoses 9a, 10a can have a certain flexibility for this, which is nevertheless defined due to the directional body 23 and with the required distances can be placed in the cast body 12. Creepage distances can easily be set up to be long (e.g. between the cast body 12 and the ceramic body 3) or avoided entirely (by using the same plastic for the directional body 23 and the cast material 32). Overall is a simple and compact design of the X-ray tube 1 is possible, with voltage breakdowns being able to be reliably prevented and the coolant flow being defined and reliably ensured.

It should be noted that the outer mold 21 can also be removed from the X-ray tube 1 (after the casting material has been poured and hardened) (not shown in more detail in FIG 1 , cf. but 12 rear).

In the Figures 2 to 4 further embodiments of an X-ray tube 1 according to the invention are explained, which largely correspond to the embodiment of FIG 1 are equivalent to. There are only the main differences to the embodiment of 1 explained.

The 2 shows a second embodiment of an X-ray tube 1 according to the invention.

In this X-ray tube 1, the directional bodies 23 for the hoses 9a, 10a are designed as perforated plates 27. The hole plates 27 are each formed by a plate 27a in which a plurality of holes 27b are included. The windings 16 of the hoses 9a, 10a are guided through the holes 27b. The die plates 27 are typically clamped between the inner mold 20 and the outer mold 21, particularly during the pouring and curing of the molding material. Alternatively, the perforated plates 27 can also be aligned with an external holder relative to the rest of the x-ray tube 1 during the casting and curing process.

The 3 shows a third embodiment of an X-ray tube 1 according to the invention.

In this embodiment, the ceramic body 3 is formed with a peripheral recess 30 on its front side facing the anode 4 . This depression 30 lies radially between the anode 4 and the cathode housing 2.

This lengthens a creepage distance from the anode 4 to the outside of the ceramic body 3 at the interface between the ceramic body 3 and the evacuated space 5, in particular significantly longer than the distance AAG between the anode 4 and the cathode housing 2. The circumferential depression 30 appears in the longitudinal section on each side of the Tube axis RA approximately V-shaped (in other embodiments also U-shaped, not shown). In a longitudinal section, the ceramic body 3 appears approximately W-shaped overall, or also approximately crown-shaped in three dimensions.

In the embodiment shown, a cable 31 is used as the inner mold 20, which is designed with an insulating sheath 31a made of plastic and a core 31b made of metal. Core 31b is connected to contacting element 17, so that high voltage can be applied to anode 4 via core 31b. The insulating jacket 31a projects here in the axial direction (along the tube axis RA) beyond the turns 16 and into the cast body 12 . The sheath 31a is formed with a constant diameter and the cable 31 is aligned along the tube axis RA. When casting the casting space 22, the cable 31 is cast into the x-ray tube 1 permanently.

Furthermore, it is provided in this embodiment by means of appropriate directional bodies 23 that the radial distance RAA outwards of the windings 16 of the hoses 9a, 10a to the outer casting mold 21 away from the anode 4 decreases. Conversely, the radial distance RAI increases inwards between the windings 16 of the hoses 9a, 10a and the inner casting mold 20, away from the anode 4. The (local) potential in the inflow line 9 and in the outflow line 10 is higher, the closer a respective line section (along the line path of the inflow line 9 or the outflow line 10) is to the anode 4. Therefore, what is achieved with this configuration is that the radial spacing of line sections with a high potential from the outer mold 21 (which is in contact with the mass) is greater than in the case of line sections with a low potential. Conversely, what is also achieved is that the radial spacing of line sections with a low potential from the core 31b (which is at high voltage) is greater than in the case of line sections with a high potential. This prevents voltage breakdowns, and allows a particularly compact construction of the X-ray tube 1 at a given high voltage.

In this design, the straightening bodies 23 are designed as wedge-shaped slot bars 24, and the windings 16 have the same axial spacing AA from one another.

The 4 shows a fourth embodiment of an X-ray tube 1 according to the invention.

In this embodiment, the directional bodies 23 are in turn designed in such a way that the radial distance RAA outwards between the turns 16 of the hoses 9a, 10a and the outer casting mold 21 away from the anode 4 decreases. Conversely, the radial distance RAI increases inwards between the windings 16 of the hoses 9a, 10a and the inner casting mold 20, away from the anode 4. In addition, it is provided here that the axial distance AA from adjacent windings 16 away from the anode 4 increases. Due to the increase in the radii R of the respective windings 16 in the direction axially away from the anode 4, a higher voltage per winding 16 drops in windings 16 that are further away from the anode 4 than in windings 16 that are closer to the anode 4 . Due to the larger axial distances AA in the windings 16, which are further away from the anode 4, voltage breakdowns between axially adjacent windings 16 can be prevented and a more compact construction of the x-ray tube 1 can be achieved.

The Figures 5 to 8 show schematic cross sections through X-ray tubes according to the invention perpendicular to the respective X-ray axis RA in various embodiments, each in the area of the windings 16 and the directional body 23. The arrangement of angular positions at which the respective directional bodies 23 in the casting space 22 between the outer mold 21 and the inner mold 20 can be advantageously arranged, illustrated by way of example. The location or projection of the hoses 9a, 10a is shown in dashed lines.

In the embodiment of figure 5 the aligning bodies 23 are designed as slot bars 24, with two (N=2) inner slot bars 25a, 25b and two (N=2) outer slot bars 26a, 26b being provided. An inner slotted bar 25a, 25b and an outer slotted bar 26a, 26b lie opposite one another and clamp the hoses 9a, 10a between them. The inner slot bars 25a, 25b are supported on the inner mold 20. The outer slot bars 26a, 26b are supported on the outer mold 21. The angular positions of the two inner slot bars 25a, 25b are offset from one another by 180°, and the angular positions of the outer slot bars 26a, 26b are offset from one another by 180°. The arrangement of the angular positions of the directional body 23 has a 2-fold rotational symmetry here.

In the embodiment of 6 the aligning bodies 23 are also designed as slot bars 24, with four (N=4) inner slot bars 25a, 25b, 25c, 25d and four (N=4) outer slot bars 26a, 26b, 26c, 26d being provided. An inner slotted bar 25a, 25b, 25c, 25d and an outer slotted bar 26a, 26b, 26c, 26d lie opposite each other and clamp the hoses 9a, 10a between them. The inner slot bars 25a, 25b, 25c, 25d are supported on the inner mold 20. The outer slot bars 26a, 26b, 26c, 26d are supported on the outer mold 21. The angular positions of the four inner slot bars 25a, 25b, 25c, 25d are offset from each other by 90°, and the angular positions of the outer slot bars 26a, 26b, 26c, 26d are offset from each other by 90°. The arrangement of the angular positions of the directional body 23 has a 4-fold rotational symmetry here.

In the embodiment of 7 the aligning bodies 23 are in turn designed as slot bars 24, with two (N=2) inner slot bars 25a, 25b and two (N=2) outer slot bars 26a, 26b being provided. The inner slot bars 25a, 25b are supported on the inner mold 20. The outer slot bars 26a, 26b are supported on the outer mold 21. The angular positions of the two inner slot bars 25a, 25b are offset from one another by 180°, and the angular positions of the outer slot bars 26a, 26b are 180° from one another shifted. The angular positions of the inner slot bars 25a, 25b are offset from the angular positions of the outer slot bars 26a, 26b by 90° to one another. The hoses 9a, 10a are also held clamped here by the straightening bodies 23, with the hoses 9a, 10a in this embodiment having to have a certain minimum rigidity against radial compression and stretching (against "oval deformation") so that the straightening bodies can have a good clamping effect 23 occurs. The arrangement of the angular positions of the directional body 23 has a 2-fold rotational symmetry here.

It should be noted that the grooved bars 24 can run parallel to the tube axis RA, in which case the grooves must be introduced into the respective bar with an inclination corresponding to the pitch of the double helix of the hoses 9a, 10a. Alternatively, the slotted bars 24 can also run with grooves introduced perpendicularly to their direction of extension, and then be arranged in the casting space 12 with an inclination to the tube axis RA, which corresponds to the pitch of the tubes 9a, 10a. It should also be noted that the inner slot bars 25a-25d can be supported not only on the inner mold 20, but alternatively or additionally also on each other, in particular with the inner slot bars 25a-25d forming partial shells (in particular half shells or quarter shells) that form the inner mold embrace (not shown).

In the embodiment of 8 the straightening bodies 23 are designed as perforated plates 27, with three (N=3) perforated plates 28a, 28b, 28c being provided, the angular positions of which are offset by 120° with respect to one another. The perforated plates 27 are each supported with their plates 27a (or their side edges) both on the inner mold 20 and on the outer mold 21 . The hoses 9a, 10a are guided in the holes 27b of the plates 27a. The arrangement of the angular positions of the directional body 23 has a 3-fold rotational symmetry here.

The Figures 9 to 11 schematically illustrate the sequence in the manufacture of an X-ray tube 1 according to the invention. An x-ray tube 1 as in 1 described manufactured. Schematic longitudinal sections along the tube axis RA are shown in each case.

Manufacture begins with the provision of a partially manufactured X-ray tube 100, essentially comprising the ceramic body 3, to which the anode 4 and the cathode housing 2 are already attached, cf. 9 . The cathode housing 2 is directed downwards.

• die äußere Gussform 21 auf dem Keramikkörper 3 aufgesetzt wird,
• die innere Gussform 20 (hier eine Buchse 19 einschließlich Anschlusspol 18) innerhalb der äußeren Gussform 21 platziert wird, und
• die Richtkörper 23 und die Schläuche 9a, 10a im Bereich zwischen der inneren Gussform 20 und der äußeren Gussform 21 angeordnet werden. Der danach erreichte Zustand ist in Fig. 10 gezeigt. Durch die Richtkörper 23, hier die Nuten 24b, werden die Schläuche 9a, 10a in Position gehalten. Der Gussraum 22 ist nach oben hin offen.

Then the casting space 22 is prepared by (in principle any order)

• the outer mold 21 is placed on the ceramic body 3,
• the inner mold 20 (here a socket 19 including terminal 18) is placed inside the outer mold 21, and
• the straightening bodies 23 and the hoses 9a, 10a are arranged in the area between the inner mold 20 and the outer mold 21. The state reached afterwards is in 10 shown. The hoses 9a, 10a are held in position by the straightening bodies 23, here the grooves 24b. The casting space 22 is open at the top.

A liquid, hardenable plastic casting material 32 is then filled into the casting space 22, which is selected, for example, as a silicone. The casting material 32 is most simply poured into the casting space 22 from above. The liquid casting material 32 is distributed throughout the available casting space 22 up to a surface 32a of the casting material 32. The casting material 32 reaches in particular between the coils 16 and the inner mold 20, between the coils 16 and the outer mold 21, and axially between adjacent turns 16. The casting material 32 thus encloses the hoses 9a, 10a and also the straightening body 23. The filled state of the casting space 22 is in 11 shown. Then the liquid casting material 32 is hardened; typically, some time is allowed and/or heat is applied for curing. After the casting material 32 has hardened, the casting body 12 and the x-ray tube 1 are completed overall. In this variant, the outer mold 21 remains on the X-ray tube 1; the outer mold 21 can be covered with lead foil (not shown) for grounding and radiation protection. With a coolant, such as deionized water in the Hoses 9a, 10a cooled anode 4 and high voltage applied between the anode 4 and the heated hot cathode 6, X-rays can then be generated by means of the X-ray tube 1 during operation.

In another variant, starting from the in 11 X-ray tube shown, after the casting material 32 has hardened, the outer mold of the cast body is removed; a corresponding X-ray tube 1 with the outer mold removed is in 12 shown. The cast body then remains in the X-ray tube 1 as a remaining cast body 12a, which is essentially formed by the cast space 22 filled with hardened cast material 32 (including the cast-in directional body or bodies and the cast-in hose sections) and the inner mold 20. A (radially outer) side surface 32b of the hardened casting material 32 or of the filled casting space 22 is exposed accordingly; this side surface 32b can be covered with a lead foil (not shown) for grounding and radiation protection. In this variant, the outer mold can be used several times (and is then usually designed in several parts for radial shaping and permanently arranged at a casting station, not shown). In the 12 X-ray tube 1 shown can, like the one shown in 11 X-ray tube shown are used in operation for generating X-rays.

reference list

1

x-ray tube

2

cathode housing

3

ceramic body

4

anode

4a

top of the anode ("target")

4b

Anode channels for coolant (in the anode body)

5

evacuated space

6

thermionic cathode

7a

ground connection

7b

Power connection (for heating current)

8th

shielding

9

inlet line

9a

Inlet line hose

9b

Coolant connection (supply line)

10

drain line

10a

Drain line hose

10b

Coolant connection (drain line)

11

insulating body

12

cast body

12a

rest of the casting

13

Radiation exit window, here beryllium window

14a

inlet pipe tube

14b

tubing of the drain line

15

return

16

coil

17

contacting element

18

connection pole

19

Rifle

20

inner mold

21

outer mold

22

casting room

23

straight body

24

slot bolt

24a

bars

24b

groove

25a-25d

inner slot bolts

26a-26d

outer slot bar

27

perforated plate

27a

plate

27b

Hole

28a-28d

perforated plates

29

conical front end of the cast body

30

circumferential indentation

31

Cable

31a

Coat

31b

Soul

32

casting material

32a

surface (casting material)

32b

side surface (casting material)

100

partially manufactured X-ray tube

aa

axial distance

AAG

radial distance of anode and cathode case

AEK

axial extension of the ceramic body

GRR

largest radius of return

KRR

smallest radius of the return

R

radius of the turn

RA

tube axis

RK

outer radius of the ceramic body at the back

RAA

radial distance to the outside

RAI

radial distance inwards

TR

axial depth of recess

reference list

1. [1] WO 2008/148426 A1
2. [2] DE 10 2017 217 181 B3
3. [3] US 10,714,300 B2
4. [4] Company publication "OEG-92J Industrial X-Ray tube", version 2021, Varex Imaging Corporation, Salt Lake City, UT 84104, USA .
5. [5] DE 10 2008 017 153 A1
6. [6] U.S. 2012/0 076 278 A1
7. [7] JP 2015-232 944 A

Claims (25)

X-ray tube (1), which has a cathode housing (2) with a radiation exit window (13), a cooled anode (4), a cathode, in particular a hot cathode (6), an insulating body (11) for electrical insulation of a high-voltage potential of the anode (4), a feed line (9) for coolant to the anode (4) and a drain line (10) for coolant from the anode (4), and wherein in the insulating body (11) the inlet line (9) and the outlet line (10) each comprise a plurality of windings (16); characterized, that the insulating body (11) comprises a ceramic body (3) and a cast body (12), the anode (4) and the cathode housing (2) being fixed to the ceramic body (3), and the cast body (12) to the ceramic body (3 ) is fixed, that the cast body (12) comprises an inner mold (20) and at least temporarily during the manufacture of the X-ray tube (1) an outer mold (21), that in a casting space (22) between the outer mold (21) and the inner mold (20), the inlet line (9) and the outlet line (10) are each formed with a hose (9a, 10a) which has the plurality of turns (16 ) trains that at least one straightening body (23) made of plastic is arranged in the casting space (22), with which the hoses (9a, 10a) are aligned in the casting space (22), so that the turns (16) of the hoses (9a, 10a) each from the outer mold (21) and the inner mold (20) are spaced apart, and that the casting space (22) is filled with a casting material (32) made of plastic in a hardened state, so that the spaces between the windings (16) on the one hand and the outer mold (21) and the inner mold (20) on the other hand from the Plastic of the at least one directional body (23) and / or the plastic of the casting material (32) are taken. X-ray tube (1) according to Claim 1, characterized in that the hoses (9a, 10a) are also aligned in the casting space (22) with the at least one aligning body (23), so that the windings (16) of the hoses (9a, 10a ) are spaced apart,
and that the casting space (22) is still filled with the casting material (32), so that the spaces between the windings (16) are also occupied by the plastic of the at least one straightening body (23) and/or the plastic of the casting material (32). are. X-ray tube (1) according to Claim 1 or 2, characterized in that the ceramic body (3) has a peripheral depression (30) between the cathode housing (2) and the anode (4) on a front side facing the anode (4), and that the ceramic body (3) has a central recess (15) on a rear side of the ceramic body (3) facing the cast body (12). X-ray tube (1) according to Claim 3, characterized in that the hoses (9a, 10a) are partially arranged in a region of the central recess (15) of the ceramic body (3), in particular with at least half a turn (16) of the hoses ( 9a, 10a) and/or at least 10% of the length of the hoses (9a, 10a) is arranged in the central recess (15) of the ceramic body (3). X-ray tube (1) according to any one of claims 1 to 4, characterized in that the inner mold (20) as a socket (19) for a High-voltage plug for connection to the anode (4) is designed. X-ray tube (1) according to one of Claims 1 to 4, characterized in that the inner mold (20) is designed as a cable (31) which has an insulating jacket (31a) and a core (31b) running in the jacket (31a). includes, to which the anode (4) is connected. X-ray tube (1) according to one of the preceding claims, characterized in that the at least one directional body (23) and the cast material (32) consist of the same plastic. X-ray tube (1) according to Claim 7, characterized in that the plastic of the casting material (32) comprises a silicone or an epoxy resin or a polyurethane. X-ray tube (1) according to one of the preceding claims, characterized in that several straightening bodies (23) are arranged in the casting space (22),
in particular wherein the directional body (23) respectively - between the inner mold (20) and the outer mold (21) - and/or are clamped between the hoses (9a, 10a) on the one hand and the inner mold (20) or the outer mold (21) on the other hand. X-ray tube (1) according to claim 9, characterized in that in a respective cutting plane perpendicular to a tube axis (RA) of the X-ray tube (1), the aligning bodies (23) are arranged at angular positions, the angular positions having a rotationally symmetrical arrangement with respect to the tube axis (RA) form. X-ray tube (1) according to Claim 10, characterized in that N aligning bodies (23) support the hoses (9a, 10a) towards the inner cast body (20), and N aligning bodies (23) support the hoses (9a, 10a) towards the outer cast body ( 21) towards, and the rotationally symmetrical arrangement of the angular positions has an N-fold number, where N is a natural number with N≥2. X-ray tube (1) according to Claim 11, characterized in that the N straightening bodies (23) supporting the hoses (9a, 10a) towards the inner cast body (20) and the N straightening bodies (23) supporting the hoses (9a, 10a) towards the outer cast body (21), are arranged in a respective sectional plane with respect to the tube axis (RA). - at identical angular positions, or - at angular positions offset by 360°/(2 ^∗ N) from one another. X-ray tube (1) according to one of the preceding claims, characterized in that one or more directional bodies (23) of the at least one directional body (23) are designed as a perforated plate (27, 28a-28c) comprising a plate (27a) and a plurality of holes (27b) in the plate (27a) through which the hoses (9a, 10a) are routed,
in particular wherein a respective perforated plate (27, 28a-28c) is arranged clamped between the inner mold (20) and the outer mold (21). X-ray tube (1) according to one of the preceding claims, characterized in that one or more directional bodies (23) of the at least one directional body (23) are designed as a slot bar (24), comprising a bar (24a) and a plurality of slots (24b), in particular semicircular grooves (24b) into which the hoses (9a, 10a) are inserted,
In particular, a respective slot bar (24) between the hoses (9a, 10a) on the one hand and the inner mold (20) or the outer Mold (21) is arranged clamped on the other hand. X-ray tube (1) according to Claim 14, characterized in that slot bars (25a-25d) support the hoses (9a, 10a) towards the inner cast body (20) and slot bars (26a-26d) support the hoses (9a, 10a ) to the outer cast body (21) support out, are arranged in pairs opposite each other. X-ray tube (1) according to one of the preceding claims, characterized in that the windings (16) of the hoses (9a, 10a) are wound around a tube axis (RA) and lined up along a tube axis (RA). X-ray tube (1) according to Claim 16, characterized in that the windings (16) have a constant radius (R) with respect to the tube axis (RA),
In particular, the outer mold (21) and the inner mold (20) are designed essentially in the shape of a cylinder jacket and coaxial to the tube axis (RA), so that the windings (16) have a constant radial distance (RAA) to the outer mold (21) and furthermore the windings (16) have a constant radial distance (RAI) to the inner mold (20). X-ray tube (1) according to Claim 17, characterized in that the windings (16) have a constant spacing (AA) from one another in the axial direction. X-ray tube (1) according to Claim 16, characterized in that the windings (16) have a radius (R) with respect to the tube axis (RA) which increases away from the anode (4),
in particular, the outer mold (21) and the inner mold (20) being essentially cylindrical and coaxial with the axis of the tube (RA) are formed so that the turns (16) have a decreasing radial distance (RAA) away from the anode (4) to the outer mold (21) and further the turns (16) increase away from the anode (4). Have radial distance (RAI) to the inner mold (20). X-ray tube (1) according to Claim 19, characterized in that the turns (16) - a constant axial distance (AA) to each other - Or from the anode (4) away increasing axial distance (AA) to each other exhibit. X-ray tube (1) according to one of Claims 1 to 20, characterized in that after the production of the X-ray tube (1), the outer mold (21) remains on the rest of the cast body (12a). X-ray tube (1) according to one of Claims 1 to 20, characterized in that after the production of the X-ray tube (1), the outer mold (21) is removed from the rest of the cast body (12a). Method for producing an X-ray tube (1) according to one of the preceding claims,
with the steps: a) to set up the casting space (22), the outer mold (21) is arranged in a sealing manner on a rear side of the ceramic body (3) facing away from the anode (4) and the inner mold (20) is arranged in front of the rear side of the ceramic body (3), and the at least one directional body (23) made of plastic and the hoses (9a, 10a) are arranged in the casting space (22) between the inner mold (20) and the outer mold (21), with the at least one directional body (23) hoses (9a, 10a) are aligned in the casting space (22) so that the turns (16) of the hoses (9a, 10a) are spaced from the outer mold (21) and the inner mold (20), and preferably also the turns (16) are spaced apart, b) the casting space (22) is filled with the plastic casting material (32) in a liquid state, so that the spaces between the turns (16) on the one hand and the outer mold (21) and the inner mold (20) on the other hand, and preferably also the spaces between the windings (16) are occupied by the plastic of the at least one directional body (23) and/or the plastic of the casting material (32), c) the plastic casting material (32) is hardened. Method according to claim 23, characterized in that
that with the method an X-ray tube (1) according to claim 21 is produced, wherein after step c) the outer mold (21) remains on the rest of the cast body (12a). Method according to claim 23, characterized in that
that with the method an X-ray tube (1) according to claim 22 is produced, wherein the method further comprises a step d) the outer mold (21) is removed from the rest of the cast body (12a).

Images