EP0378273B1 - Rotary anode X-ray tube with a gliding bearing, particularly a spirally grooved bearing - Google Patents

Rotary anode X-ray tube with a gliding bearing, particularly a spirally grooved bearing Download PDF

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Publication number
EP0378273B1
EP0378273B1 EP90200048A EP90200048A EP0378273B1 EP 0378273 B1 EP0378273 B1 EP 0378273B1 EP 90200048 A EP90200048 A EP 90200048A EP 90200048 A EP90200048 A EP 90200048A EP 0378273 B1 EP0378273 B1 EP 0378273B1
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EP
European Patent Office
Prior art keywords
bearing
lubricant
ray tube
anode
rotary
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP90200048A
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German (de)
French (fr)
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EP0378273A2 (en
EP0378273A3 (en
Inventor
Axel Vetter
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Philips Intellectual Property and Standards GmbH
Koninklijke Philips NV
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Philips Patentverwaltung GmbH
Koninklijke Philips Electronics NV
Philips Electronics NV
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Publication of EP0378273A3 publication Critical patent/EP0378273A3/en
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00X-ray tubes
    • H01J35/02Details
    • H01J35/04Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/08Anodes; Anti cathodes
    • H01J35/10Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes
    • H01J35/101Arrangements for rotating anodes, e.g. supporting means, means for greasing, means for sealing the axle or means for shielding or protecting the driving
    • H01J35/1017Bearings for rotating anodes
    • H01J35/104Fluid bearings
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00X-ray tubes
    • H01J2235/10Drive means for anode (target) substrate
    • H01J2235/1046Bearings and bearing contact surfaces
    • H01J2235/106Dynamic pressure bearings, e.g. helical groove type
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00X-ray tubes
    • H01J2235/10Drive means for anode (target) substrate
    • H01J2235/1046Bearings and bearing contact surfaces
    • H01J2235/1066Treated contact surfaces, e.g. coatings

Definitions

  • the invention relates to a rotating anode X-ray tube according to the preamble of the main claim.
  • Such an X-ray tube with a spiral groove bearing is known from EP-OS 141 476.
  • the object of the present invention is to design a rotating anode X-ray tube of the type mentioned at the outset in such a way that damage to the bearing in the event of loss of lubricant is largely prevented.
  • the rotary anode X-ray tube shown in FIG. 1 has a metal piston 1 to which the cathode 3 is attached via a first insulator 2 and the rotary anode is attached via a second insulator 4.
  • the rotating anode has an anode disc 5, on the surface of which is opposite the cathode 3, when a high voltage is switched on, X-radiation is generated, which emerges through a radiation exit window 6 in the bulb 1, which preferably consists of beryllium.
  • the anode disk 5 is connected via a bearing to a carrier body 7 which is fastened to the second insulator 4. As can be seen in particular from FIG.
  • the bearing comprises a bearing shaft 8 which is fixedly connected to the carrier body 7 and a bearing shell 9 which concentrically surrounds the bearing shaft 8 and which has at its lower end a rotor 10 for driving the anode disk 5, which at the upper end the bearing shell 9 is attached.
  • the bearing axis 8 and the bearing shell 9 consist of tungsten, molybdenum or a tungsten-molybdenum alloy (TZM).
  • the axis 8 is provided with two herringbone groove patterns 11 which are offset from one another in the axial direction.
  • the grooves are only a few »m deep and the surfaces of the grooves are preferably in a ratio of 1: 1 to the surfaces in between.
  • the space between the groove patterns 11 and the bearing shell 9 is filled with a liquid lubricant, preferably a gallium alloy (GaInSn).
  • GaInSn gallium alloy
  • the bearing axis 12 has a section 12 several millimeters thick, the diameter of which is substantially larger than the diameter of the remaining part of the bearing axis 8; a section follows below, the diameter of which is slightly smaller than the diameter of the bearing axis 8 in the upper region and which is connected to the carrier body 7.
  • the inner contour of the bearing shell 9 is adapted to the outer contour of the axis 8; as a result, the bearing shell cannot be formed in one piece, as shown in the drawing, but must consist of at least two parts which are connected in a suitable manner in the area of section 12 in such a way that the lubricant cannot escape through the connection areas.
  • the lower end face of the section 12 is provided with a herringbone-like pattern 13 of grooves and, together with a parallel surface of the bearing shell 9, forms a pair of bearing surfaces which can absorb axially upward forces on the rotating anode.
  • the upper end face 14 of the section 12 is provided with a similar groove pattern. It forms together with the opposite parallel surface of the bearing shell 9 a pair of bearing surfaces, which absorbs downward axial forces on the rotating anode.
  • the bearing 8, 9 is closed towards the anode disk 5; the lubricant film only adjoins the vacuum space in the lower section. So that the surfaces adjacent to the bearing surfaces are not wetted by the lubricant and thereby remove lubricant from the bearing, the surfaces in the opening area of the bearing are provided with a layer that cannot be wetted by the lubricant, for example titanium oxide, as known from EP-OS 141 476. Nevertheless, it cannot be avoided that lubricant can escape due to sudden mechanical stress on the bearing.
  • a relatively large gap is provided between the outer lateral surface of section 12 and the opposite and concentric surface of the bearing shell 9, which surrounds a lubricant reservoir 15.
  • a gap of only 0.5 mm is sufficient to form a lubricant reservoir of around 500 mm 3, which is large compared to the amount of lubricant in the radial or axial direction Spiral groove bearings (70 mm3 or 50 mm3). Since the lubricant in the lubricant reservoir 15 from the Rotation axis 16 has the greatest distance, the centrifugal forces generated by rotating anode cause the lubricant to remain in the reservoir during normal operation.
  • a channel 17 is drilled in section 12 of the bearing axis 8, which connects the lubricant reservoir 15 to the opening area, so that the end of this channel facing away from the lubricant reservoir is connected to the vacuum space in the X-ray tube.
  • the lubricant initially contained in the channel 17 empties into the lubricant reservoir 15, and then the vacuum can expand into the lubricant region 15 and form a cavity there.
  • the channel 17 has the effect that all bearing points are automatically supplied with the required amount of lubricant.
  • the diameter of the channel should be as large as possible, but only so large - for example 0.6 mm - that the Capillary forces still hold the lubricant and do not let it flow into the vacuum space of the rotating anode X-ray tube. This must also not happen while the rotating anode is rotating. Therefore, a radially outwardly directed channel through the bearing shell 9 is prohibited because the centrifugal forces could push the lubricant outwards through the channel during operation. This danger does not exist with the channel 17 directed inwards from the lubricant reservoir. In order to enable a faster flow from the lubricant reservoir in the event of a loss of lubricant, it can be expedient to provide a plurality of channels 17 - symmetrical to the axis of rotation and evenly distributed over the circumference.
  • the lubricant gap of the spiral groove bearing 14 on the anode side becomes smaller. This leads to a higher pressure build-up there and consequently to a pumping action, as a result of which lubricant is sucked into the outer and inner edge of this bearing.
  • the lubricant comes from the opposite spiral groove bearing 13. This lubricant transport through the narrow bearing gaps would create high negative pressures, which can lead to the tearing of the lubricating film (cavitation).
  • Such a cavitation or strong lubricant flows across the bearing surface can be avoided by a channel 18, which has approximately the same diameter as the channel 17 and which connects the spiral groove bearing 14 facing away from the opening of the bearing to the lubricant reservoir 15 at its inner edge. This is because the lubricant is supplied to the inner edge of the bearing 14 from the reservoir 15 via the bore 18.
  • the channel 17 has a similar function for the opposite axial movement, if it ends in the area of the inner edge of the axial spiral groove bearing 13.
  • the inner part of the bearing - the bearing axis 8 - is fixed, while the outer part - the bearing shell 9 - rotates; the opening of the bearing faces away from the anode disk.
  • the inner part could rotate and the outer part could be fixed; the opening of the bearing would face the anode disk.
  • the channels 17 and 18 could then also run in the inner part and should be directed inwards from the lubricant reservoir.
  • a bearing was assumed whose cross-section part provided with spiral grooves has the shape of an inverted T. Instead, this part can also have a rectangular cross section; i.e., the spiral grooves can be applied to the front and lateral surfaces of a cylindrical bearing axis.
  • the lubricant reservoir is located on the lateral surface between the two radial spiral groove bearings attached there. In order to establish a connection with the axial spiral groove bearings on the end faces - the lubricant can practically not be transported there via the radial bearings - there must be a system of channels which connects the edges of the bearing axis with the lubricant reservoir.
  • the lubricant reservoir must be connected to the vacuum space via a plurality of channels - that is, also a channel system - the inlet opening having to be closer to the axis of rotation than the reservoir.
  • the two channel systems mentioned can share some of their channels.

Landscapes

  • Sliding-Contact Bearings (AREA)

Description

Die Erfindung betrifft eine Drehanoden-Röntgenröhre gemäß dem Oberbegriff des Hauptanspruchs. Eine solche Röntgenröhre mit einem Spiralrillenlager ist aus der EP-OS 141 476 bekannt. In der Praxis läßt sich nicht vermeiden, daß Schmiermitteltropfen aus dem Lager austreten. Da die Schmiermittelmenge solcher Lager begrenzt ist, kann dieser Schmiermittelverlust zu einer Zerstörung des Lagers führen.The invention relates to a rotating anode X-ray tube according to the preamble of the main claim. Such an X-ray tube with a spiral groove bearing is known from EP-OS 141 476. In practice, it cannot be avoided that drops of lubricant come out of the bearing. Since the amount of lubricant in such bearings is limited, this loss of lubricant can destroy the bearing.

Aufgabe der vorliegenden Erfindung ist es, eine Drehanoden-Röntgenröhre der eingangs genannten Art so auszugestalten, daß eine Beschädigung des Lagers im Falle eines Schmiermittelverlustes weitgehend unterbunden wird.The object of the present invention is to design a rotating anode X-ray tube of the type mentioned at the outset in such a way that damage to the bearing in the event of loss of lubricant is largely prevented.

Diese Aufgabe wird erfindungsgemäß durch die im Hauptanspruch angegebenen Maßnahmen gelöst. Im Falle eines Schmiermittelverlustes strömt aus dem Schmiermitttelreservoir Schmiermittel in die Lagerflächenpaare hinein. Ohne das Kanalsystem wäre dies nicht möglich, weil das Hineinströmen die Bildung eines Hohlraums im Schmiermittelreservoir voraussetzt. Diese Hohlraumbildung (Kavitation) wird aber normalerweise durch die Oberflächenspannung des Schmiermittels verhindert. Erst der Kanal ermöglicht diese Hohlraumbildung und gestattet das Nachströmen aus dem Schmiermittelreservoir in den belasteten Bereich der Lagerflächenpaare.This object is achieved by the measures specified in the main claim. In the event of a loss of lubricant, lubricant flows from the lubricant reservoir into the bearing surface pairs. This would not be possible without the channel system because the flow requires the formation of a cavity in the lubricant reservoir. This cavitation is usually prevented by the surface tension of the lubricant. Only the channel enables this formation of cavities and allows the flow from the lubricant reservoir into the loaded area of the bearing surface pairs.

Es sei an dieser Stelle erwähnt, daß aus der EP-OS 117 873 bereits ein Gleitlager bekannt ist, bei dem der Bereich zwischen den Lagerflächen durch ein Kanalsystem mit dem Außenraum des Lagers verbunden ist. Dieses Lager wird bei unterschiedlichem Atmosphärendruck betrieben und das Kanalsystem hat dabei die Aufgabe, bei erhöhtem Außendruck den Zustrom von Frischluft in das Lager und bei verringertem Außendruck das Ausströmen der Luft aus dem Lager zu gestatten.It should be mentioned at this point that a plain bearing is already known from EP-OS 117 873, in which the area between the bearing surfaces is connected to the outside of the bearing by a channel system. This camp is operated at different atmospheric pressure and the duct system has the task of allowing the inflow of fresh air into the camp at increased outside pressure and the air to flow out of the camp at reduced outside pressure.

Die Erfindung wird nachstehend anhand der Zeichnung näher erläutert. Es zeigen

  • Fig. 1 eine Drehanoden-Röntgenröhre nach der Erfindung und
  • Fig. 2 einen Teil einer solchen Röhre.
The invention is explained below with reference to the drawing. Show it
  • Fig. 1 shows a rotating anode X-ray tube according to the invention and
  • Fig. 2 shows a part of such a tube.

Die in Fig. 1 dargestellte Drehanoden-Röntgenröhre besitzt einen Metallkolben 1, an dem über einen ersten Isolator 2 die Kathode 3 und über einen zweiten Isolator 4 die Drehanode befestigt ist. Die Drehanode besitzt eine Anodenscheibe 5, auf deren der Kathode 3 gegenüberliegenden Fläche beim Einschalten einer Hochspannung Röntgenstrahlung erzeugt wird, die durch ein Strahlenaustrittsfenster 6 im Kolben 1, das vorzugsweise aus Beryllium besteht, austritt. Die Anodenscheibe 5 ist über ein Lager mit einem Trägerkörper 7 verbunden, der an dem zweiten Isolator 4 befestigt ist. Wie sich insbesondere aus Fig. 2 ergibt, umfaßt das Lager eine fest mit dem Trägerkörper 7 verbundene Lagerachse 8 und eine die Lagerachse 8 konzentrisch umschließende Lagerschale 9, die an ihrem unteren Ende einen Rotor 10 zum Antrieb der Anodenscheibe 5 aufweist, die am oberen Ende der Lagerschale 9 befestigt ist. Die Lagerachse 8 und die Lagerschale 9 bestehen aus Wolfram, Molybdän oder einer Wolfram-Molybdänlegierung (TZM).The rotary anode X-ray tube shown in FIG. 1 has a metal piston 1 to which the cathode 3 is attached via a first insulator 2 and the rotary anode is attached via a second insulator 4. The rotating anode has an anode disc 5, on the surface of which is opposite the cathode 3, when a high voltage is switched on, X-radiation is generated, which emerges through a radiation exit window 6 in the bulb 1, which preferably consists of beryllium. The anode disk 5 is connected via a bearing to a carrier body 7 which is fastened to the second insulator 4. As can be seen in particular from FIG. 2, the bearing comprises a bearing shaft 8 which is fixedly connected to the carrier body 7 and a bearing shell 9 which concentrically surrounds the bearing shaft 8 and which has at its lower end a rotor 10 for driving the anode disk 5, which at the upper end the bearing shell 9 is attached. The bearing axis 8 and the bearing shell 9 consist of tungsten, molybdenum or a tungsten-molybdenum alloy (TZM).

An ihrem oberen Ende ist die Achse 8 mit zwei in axialer Richtung gegeneinander versetzten, fischgrätartigen Rillenmustern 11 versehen. Die Rillen sind nur wenige »m tief und die Flächen der Rillen stehen zu den dazwischenliegenden Flächen vorzugsweise im Verhältnis 1 : 1. Der Zwischenraum zwischen den Rillenmustern 11 und der Lagerschale 9 ist mit einem flüssigen Schmiermittel gefüllt, vorzugsweise einer Galliumlegierung (GaInSn). Die mit den Rillenmustern 11 versehenen Flächen der Achse 8 und die ihnen gegenüberliegenden Flächen der Lagerschale 9 bilden somit ein Spiralrillenlager, das die radialen Lagerkräfte aufnimmt.At its upper end, the axis 8 is provided with two herringbone groove patterns 11 which are offset from one another in the axial direction. The grooves are only a few »m deep and the surfaces of the grooves are preferably in a ratio of 1: 1 to the surfaces in between. The space between the groove patterns 11 and the bearing shell 9 is filled with a liquid lubricant, preferably a gallium alloy (GaInSn). The surfaces of the axis 8 provided with the groove patterns 11 and the surfaces of the bearing shell 9 lying opposite them thus form a spiral groove bearing which absorbs the radial bearing forces.

Im Anschluß an das untere der beiden Rillenmuster 11 hat die Lagerachse 12 einen mehrere Millimeter dicken Abschnitt 12, dessen Durchmesser wesentlich größer ist als der Durchmesser des übrigen Teiles der Lagerachse 8; darunter folgt ein Abschnitt, dessen Durchmesser geringfügig kleiner ist als der Durchmesser der Lagerachse 8 im oberen Bereich und der mit dem Trägerkörper 7 verbunden ist. Die Innenkontur der Lagerschale 9 ist der Außenkontur der Achse 8 angepaßt; infolgedessen kann die Lagerschale nicht einteilig ausgebildet sein, wie in der Zeichnung dargestellt, sondern sie muß aus mindestens zwei Teilen bestehen, die im Bereich des Abschnitts 12 auf geeignete Weise so miteinander verbunden sind, daß das Schmiermittel durch die Verbindungsbereiche nicht austreten kann.Following the lower of the two groove patterns 11, the bearing axis 12 has a section 12 several millimeters thick, the diameter of which is substantially larger than the diameter of the remaining part of the bearing axis 8; a section follows below, the diameter of which is slightly smaller than the diameter of the bearing axis 8 in the upper region and which is connected to the carrier body 7. The inner contour of the bearing shell 9 is adapted to the outer contour of the axis 8; as a result, the bearing shell cannot be formed in one piece, as shown in the drawing, but must consist of at least two parts which are connected in a suitable manner in the area of section 12 in such a way that the lubricant cannot escape through the connection areas.

Die untere Stirnfläche des Abschnitts 12 ist mit einem fischgrätartigen Muster 13 von Rillen versehen und bildet zusammen mit einer dazu parallelen Fläche der Lagerschale 9 ein Lagerflächenpaar, das axial nach oben gerichtete Kräfte auf die Drehanode aufnehmen kann. Die obere Stirnfläche 14 des Abschnitts 12 ist mit einem gleichartigen Rillenmuster versehen. Es bildet zusammen mit der gegenüberliegenden parallelen Fläche der Lagerschale 9 ein Lagerflächenpaar, das nach unten gerichtete axiale Kräfte auf die Drehanode aufnimmt.The lower end face of the section 12 is provided with a herringbone-like pattern 13 of grooves and, together with a parallel surface of the bearing shell 9, forms a pair of bearing surfaces which can absorb axially upward forces on the rotating anode. The upper end face 14 of the section 12 is provided with a similar groove pattern. It forms together with the opposite parallel surface of the bearing shell 9 a pair of bearing surfaces, which absorbs downward axial forces on the rotating anode.

Das Lager 8, 9 ist zur Anodenscheibe 5 hin geschlossen; nur im unteren Abschnitt grenzt der Schmiermittelfilm an den Vakuumraum an. Damit die an die Lagerflächen angrenzenden Flächen nicht vom Schmiermittel benetzt werden und dem Lager dadurch Schmiermittel entziehen, sind die Oberflächen in dem Öffnungsbereich des Lagers mit einer vom Schmiermittel nicht benetzbaren Schicht versehen, beispielsweise Titanoxid, wie aus der EP-OS 141 476 bekannt. Trotzdem läßt sich nicht vermeiden, daß durch stoßartige mechanische Beanspruchung des Lagers Schmiermittel austreten kann. Vergegenwärtigt man sich, daß der Schmiermittelspalt wesentlich kleiner ist als in der Zeichnung dargestellt und typischerweise in der Größenordnung von 20 »m liegt, dann wird deutlich, daß schon beim Austritt einer kleinen Schmiermittelmenge ein relativ großer Teil des im Lagerbereich enthaltenen Schmiermittels verlorengeht, was zu einer Verringerung der Tragkraft und zu einer Beschädigung des Lagers - insbesondere in den Start- oder den Stopp-Phasen - führen kann.The bearing 8, 9 is closed towards the anode disk 5; the lubricant film only adjoins the vacuum space in the lower section. So that the surfaces adjacent to the bearing surfaces are not wetted by the lubricant and thereby remove lubricant from the bearing, the surfaces in the opening area of the bearing are provided with a layer that cannot be wetted by the lubricant, for example titanium oxide, as known from EP-OS 141 476. Nevertheless, it cannot be avoided that lubricant can escape due to sudden mechanical stress on the bearing. If one realizes that the lubricant gap is considerably smaller than shown in the drawing and is typically of the order of 20 »m, then it becomes clear that when a small amount of lubricant escapes, a relatively large part of the lubricant contained in the bearing area is lost, which is why a reduction in the load capacity and damage to the bearing - especially in the start or stop phases.

Um solche Beschädigungen zu vermeiden, ist zwischen der äußeren Mantelfläche des Abschnitts 12 und der gegenüberliegenden und dazu konzentrischen Fläche der Lagerschale 9 ein relativ großer Spalt vorgesehen, der ein Schmiermittelreservoir 15 umschließt. Bei einer Dicke des Abschnitts 12 von z.B. 6 mm und einem Durchmesser dieses Abschnittes von 50 mm genügt ein Spalt von nur 0,5 mm, um ein Schmiermittelreservoir von rund 500 mm³ zu bilden, das groß ist im Vergleich zur Schmiermittelmenge im radialen bzw. axialen Spiralrillenlager (70 mm³ bzw. 50 mm³). Da das Schmiermittel in dem Schmiermittelreservoir 15 von der Rotationsachse 16 den größten Abstand hat, bewirken die bei rotierender Drehanode erzeugten Zentrifugalkräfte, daß das Schmiermittel im normalen Betrieb in dem Reservoir verbleibt.In order to avoid such damage, a relatively large gap is provided between the outer lateral surface of section 12 and the opposite and concentric surface of the bearing shell 9, which surrounds a lubricant reservoir 15. With a thickness of section 12 of, for example, 6 mm and a diameter of this section of 50 mm, a gap of only 0.5 mm is sufficient to form a lubricant reservoir of around 500 mm 3, which is large compared to the amount of lubricant in the radial or axial direction Spiral groove bearings (70 mm³ or 50 mm³). Since the lubricant in the lubricant reservoir 15 from the Rotation axis 16 has the greatest distance, the centrifugal forces generated by rotating anode cause the lubricant to remain in the reservoir during normal operation.

Wenn Schmiermittel aus dem Lager ausgetreten ist - im allgemeinen aus dem Bereich der unteren Stirnfläche 13 des Abschnitts 12 der Lagerachse - wird bei rotierender Anode zwar ein Sog von dem in diesem Lagerflächenpaar verbliebenen Schmiermittel auf das im Schmiermittelreservoir 15 vorhandene Schmiermittel ausgeübt, doch kann das Schmiermittel aus dem Schmiermittelreservoir nicht ohne weiteres in den entleerten Zwischenraum zwischen dem genannten Lagerflächenpaar einströmen. Dies würde nämlich ein Auseinanderreißen des Schmiermittelfilms oder eine Hohlraumbildung im Bereich des Schmiermittelreservoirs erfordern, die durch die Oberflächenspannung des Schmiermittels verhindert wird.If lubricant has escaped from the bearing - generally from the area of the lower end face 13 of section 12 of the bearing axis - while the anode is rotating, suction is exerted by the lubricant remaining in this pair of bearing surfaces on the lubricant present in the lubricant reservoir 15, but the lubricant can do not readily flow from the lubricant reservoir into the emptied space between said bearing surface pair. This would namely require the lubricant film to tear apart or to form a cavity in the area of the lubricant reservoir, which is prevented by the surface tension of the lubricant.

Um das Nachströmen des Schmiermittels gleichwohl zu ermöglichen, ist in den Abschnitt 12 der Lagerachse 8 ein Kanal 17 gebohrt, der das Schmiermittelreservoir 15 mit dem Öffnungsbereich verbindet, so daß das vom Schmiermittelreservoir abgewandte Ende dieses Kanals mit dem Vakuumraum in der Röntgenröhre in Verbindung steht. Im Falle eines Schmiermittelverlustes entleert sich das zunächst im Kanal 17 enthaltene Schmiermittel in das Schmiermittelreservoir 15 hinein, und danach kann sich das Vakuum bis in den Schmiermittelbereich 15 hinein ausdehnen und dort einen Hohlraum bilden. Der Kanal 17 bewirkt also, daß sich alle Lagerstellen automatisch mit der benötigten Schmiermittelmenge versorgen.In order to enable the lubricant to flow in, a channel 17 is drilled in section 12 of the bearing axis 8, which connects the lubricant reservoir 15 to the opening area, so that the end of this channel facing away from the lubricant reservoir is connected to the vacuum space in the X-ray tube. In the event of a loss of lubricant, the lubricant initially contained in the channel 17 empties into the lubricant reservoir 15, and then the vacuum can expand into the lubricant region 15 and form a cavity there. The channel 17 has the effect that all bearing points are automatically supplied with the required amount of lubricant.

Der Durchmesser des Kanals sollte möglichst groß sein, jedoch nur so groß - beispielsweise 0,6 mm - daß die Kapillarkräfte das Schmiermittel noch festhalten und es nicht in den Vakuumraum der Drehanoden-Röntgenröhre abfließen lassen. Dies darf auch während der Rotation der Drehanode nicht geschehen. Deshalb verbietet sich ein radial nach außen gerichteter Kanal durch die Lagerschale 9 hindurch, weil die Zentrifugalkräfte das Schmiermittel im Betrieb durch den Kanal hindurch nach außen drücken könnten. Bei dem vom Schmiermittelreservoir aus nach innen gerichteten Kanal 17 besteht diese Gefahr nicht. Um bei einem Schmiermittelverlust ein schnelleres Nachströmen aus dem Schmiermittelreservoir zu ermöglichen, kann es zweckmäßig sein, mehrere Kanäle 17 vorzusehen - symmetrisch zur Rotationsachse und gleichmäßig auf den Umfang verteilt.The diameter of the channel should be as large as possible, but only so large - for example 0.6 mm - that the Capillary forces still hold the lubricant and do not let it flow into the vacuum space of the rotating anode X-ray tube. This must also not happen while the rotating anode is rotating. Therefore, a radially outwardly directed channel through the bearing shell 9 is prohibited because the centrifugal forces could push the lubricant outwards through the channel during operation. This danger does not exist with the channel 17 directed inwards from the lubricant reservoir. In order to enable a faster flow from the lubricant reservoir in the event of a loss of lubricant, it can be expedient to provide a plurality of channels 17 - symmetrical to the axis of rotation and evenly distributed over the circumference.

Wenn durch einen Lastwechsel die Anodenscheibe 5 nach unten verschoben wird, verkleinert sich der Schmiermittelspalt des anodenseitigen Spiralrillenlagers 14. Dies führt dort zu einem höheren Druckaufbau und in dessen Folge zu einer Pumpwirkung, wodurch Schmiermittel an den Außen- und Innenrand dieses Lagers angesaugt wird. Das Schmiermittel kommt dabei aus dem gegenüberliegenden Spiralrillenlager 13. Dieser Schmiermitteltransport durch die engen Lagerspalte würde hohe Unterdrücke hervorrufen, die zum Zerreißen des Schmierfilms (Kavitation) führen können. Durch einen Kanal 18, der etwa den gleichen Durchmesser hat wie der Kanal 17 und der das von der Öffnung des Lagers abgewandte Spiralrillenlager 14 an dessen Innenkante mit dem Schmiermittelreservoir 15 verbindet, lassen sich solche Kavitationen bzw. starke Schmiermittelströme über die Lagerfläche hinweg vermeiden. Denn das Schmiermittel wird dabei dem Innenrand des Lagers 14 vom Reservoir 15 über die Bohrung 18 zugeführt. Der Kanal 17 hat eine ähnliche Funktion für die entgegengesetzte axiale Bewegung, wenn er im Bereich des Innenrandes des axialen Spiralrillenlagers 13 endet.If the anode disk 5 is shifted downward due to a load change, the lubricant gap of the spiral groove bearing 14 on the anode side becomes smaller. This leads to a higher pressure build-up there and consequently to a pumping action, as a result of which lubricant is sucked into the outer and inner edge of this bearing. The lubricant comes from the opposite spiral groove bearing 13. This lubricant transport through the narrow bearing gaps would create high negative pressures, which can lead to the tearing of the lubricating film (cavitation). Such a cavitation or strong lubricant flows across the bearing surface can be avoided by a channel 18, which has approximately the same diameter as the channel 17 and which connects the spiral groove bearing 14 facing away from the opening of the bearing to the lubricant reservoir 15 at its inner edge. This is because the lubricant is supplied to the inner edge of the bearing 14 from the reservoir 15 via the bore 18. The channel 17 has a similar function for the opposite axial movement, if it ends in the area of the inner edge of the axial spiral groove bearing 13.

Beim Ausführungsbeispiel steht der innere Teil des Lagers - die Lagerachse 8 - fest, während der äußere Teil - die Lagerschale 9 - rotiert; die Öffnung des Lagers ist von der Anodenscheibe abgewandt. Stattdessen könnte aber auch der innere Teil rotieren und der äußere Teil feststehen; dabei wäre die Öffnung des Lagers der Anodenscheibe zugewandt. Die Kanäle 17 und 18 könnten dann ebenfalls in dem inneren Teil verlaufen und müßten vom Schmiermittelreservoir aus nach innen gerichtet sein.In the embodiment, the inner part of the bearing - the bearing axis 8 - is fixed, while the outer part - the bearing shell 9 - rotates; the opening of the bearing faces away from the anode disk. Instead, the inner part could rotate and the outer part could be fixed; the opening of the bearing would face the anode disk. The channels 17 and 18 could then also run in the inner part and should be directed inwards from the lubricant reservoir.

Bei dem Ausführungsbeispiel wurde von einem Lager ausgegangen, dessen mit Spiralrillen versehener Teil Querschnitt die Form eines umgekehrten T hat. Stattdessen kann dieser Teil aber auch einen rechteckigen Querschnitt haben; d.h., die Spiralrillen können auf den Stirn- und Mantelflächen einer zylinderförmigen Lagerachse aufgebracht sein. Das Schmiermittelreservoir befindet sich dabei auf der Mantelfläche zwischen den beiden dort angebrachten radialen Spiralrillenlagern. Um eine Verbindung mit den axialen Spiralrillenlagern auf den Stirnflächen herzustellen - das Schmiermittel kann dorthin praktisch nicht über die radialen Lager transportiert werden - muß ein System von Kanälen vorhanden sein, das die Kanten der Lagerachse mit dem Schmiermittelreservoir verbindet. Außerdem muß das Schmiermittelreservoir über mehrere Kanäle - also ebenfalls ein Kanalsystem - mit dem Vakuumraum verbunden sein, wobei die Eintrittsöffnung dichter an der Rotationsachse liegen muß als das Reservoir. Die beiden erwähnten Kanalsysteme können einen Teil ihrer Kanäle gemeinsam haben.In the exemplary embodiment, a bearing was assumed whose cross-section part provided with spiral grooves has the shape of an inverted T. Instead, this part can also have a rectangular cross section; i.e., the spiral grooves can be applied to the front and lateral surfaces of a cylindrical bearing axis. The lubricant reservoir is located on the lateral surface between the two radial spiral groove bearings attached there. In order to establish a connection with the axial spiral groove bearings on the end faces - the lubricant can practically not be transported there via the radial bearings - there must be a system of channels which connects the edges of the bearing axis with the lubricant reservoir. In addition, the lubricant reservoir must be connected to the vacuum space via a plurality of channels - that is, also a channel system - the inlet opening having to be closer to the axis of rotation than the reservoir. The two channel systems mentioned can share some of their channels.

Vorstehend wurde davon ausgegangen, daß die axiale und die radiale Lagerung durch getrennte Lager erfolgt. Die Erfindung ist jedoch auch bei Spiralrillenlagern anwendbar, die - wie an sich aus der EP-OS 141 476 bekannt - so geformt sind, daß die Lagerflächenpaare nicht nur axial gerichtete, sondern auch radial gerichtete Kräfte aufnehmen können.It was assumed above that the axial and the radial storage is carried out by separate bearings. However, the invention is also applicable to spiral groove bearings which - as known per se from EP-OS 141 476 - are shaped so that the bearing surface pairs can absorb not only axially directed, but also radially directed forces.

Claims (4)

  1. A rotary-anode X-ray tube comprising a sleeve bearing, notably a helical-groove bearing, for journalling the rotary anode in the axial direction, which bearing comprises at least two pairs of bearing surfaces (13, 14) for taking up axial forces acting in opposite directions, each pair comprising two bearing surfaces which are present on bearing portions which are rotatable with respect to one another, which bearing surfaces cooperate via a lubricant, the sleeve bearing communicating with the vacuum space of the X-ray tube via at least one opening, characterized in that a lubricant reservoir (15) is provided at the area between the pairs of bearing surfaces (13, 14), which reservoir communicates with the lubricant within the pairs of bearing surfaces, in one of the two bearing portions (8) there being provided a system of ducts (17) which connects the lubricant reservoir (15) to the vacuum space of the X-ray tube.
  2. A rotary-anode X-ray tube as claimed in Claim 1, characterized in that the system of ducts comprises a plurality of ducts (17) which are symmetrically arranged with respect to the axis of rotation (16), and uniformly distributed in the one bearing portion (8).
  3. A rotary-anode X-ray tube as claimed in any one of the preceding Claims, characterized in that the lubricant reservoir (15) is situated at a greater distance from the axis of rotation than the pair of bearing surfaces and is formed by a portion which is symmetrical with respect to the axis of rotation (16) and for which the distance between the stationary portion (8) and the rotary portion (9) of the bearing is greater.
  4. A rotary-anode X-ray tube as claimed in any one of the preceding Claims, characterized in that in the one bearing portion (8) there is provided an additional duct (18) which connects the pair of bearing surfaces which is remote from the opening to the lubricant reservoir (15) at its area which is remote therefrom.
EP90200048A 1989-01-12 1990-01-09 Rotary anode X-ray tube with a gliding bearing, particularly a spirally grooved bearing Expired - Lifetime EP0378273B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3900729 1989-01-12
DE3900729A DE3900729A1 (en) 1989-01-12 1989-01-12 TURNING ANODE TUBE WITH A SLIDING BEARING, ESPECIALLY A SPIRAL GROOVE BEARING

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EP0378273A2 EP0378273A2 (en) 1990-07-18
EP0378273A3 EP0378273A3 (en) 1991-02-06
EP0378273B1 true EP0378273B1 (en) 1995-05-31

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EP90200048A Expired - Lifetime EP0378273B1 (en) 1989-01-12 1990-01-09 Rotary anode X-ray tube with a gliding bearing, particularly a spirally grooved bearing

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US (1) US5068885A (en)
EP (1) EP0378273B1 (en)
JP (1) JP2851097B2 (en)
DE (2) DE3900729A1 (en)

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CN1024235C (en) * 1990-10-05 1994-04-13 株式会社东芝 Rotary anode type X-ray tube
KR940009193B1 (en) * 1990-10-05 1994-10-01 가부시키가이샤 도시바 Rotary-anode type x-ray tube
CN1022007C (en) * 1990-10-05 1993-09-01 东芝株式会社 Rotary anode type x-ray tube
CN1024065C (en) * 1990-10-19 1994-03-16 株式会社东芝 Rotary anode type X-ray tube
JP2989050B2 (en) * 1991-09-19 1999-12-13 株式会社東芝 Rotating anode X-ray tube
US5384819A (en) * 1992-04-08 1995-01-24 Kabushiki Kaisha Toshiba X-ray tube of the rotary anode type
DE4339817A1 (en) * 1993-11-23 1995-05-24 Philips Patentverwaltung Rotating anode X-ray tube with a plain bearing
US5483570A (en) * 1994-06-24 1996-01-09 General Electric Company Bearings for x-ray tubes
JP3093581B2 (en) 1994-10-13 2000-10-03 株式会社東芝 Rotating anode X-ray tube and method of manufacturing the same
DE19502207A1 (en) * 1995-01-25 1996-08-01 Philips Patentverwaltung Rotating anode X-ray tube with a plain bearing
JP2760781B2 (en) * 1996-01-31 1998-06-04 株式会社東芝 X-ray tomography equipment
JP2948163B2 (en) * 1996-02-29 1999-09-13 株式会社東芝 X-ray equipment
DE19733274A1 (en) * 1997-08-01 1999-02-04 Philips Patentverwaltung Rotating anode X-ray tube with a plain bearing
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US6891928B2 (en) * 2003-05-07 2005-05-10 Ge Medical Systems Liquid metal gasket in x-ray tubes
EP1807236A1 (en) * 2004-10-26 2007-07-18 Koninklijke Philips Electronics N.V. Molybdenum-molybdenum brazing and rotary-anode x-ray tube comprising such a brazing
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Also Published As

Publication number Publication date
DE3900729A1 (en) 1990-07-19
DE59009164D1 (en) 1995-07-06
US5068885A (en) 1991-11-26
JP2851097B2 (en) 1999-01-27
JPH02227947A (en) 1990-09-11
EP0378273A2 (en) 1990-07-18
EP0378273A3 (en) 1991-02-06

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