DE3636938A1 - HEATING CONVERTER FOR A X-RAY GENERATOR - Google Patents

Abstract

The heat convertor described is of extremely compact design and can be fed with 125 kV. Its design dispenses with any additional insulation and several converters can be stacked in order to form a module without the need for technical modifications. The connections of the primary and insulating windings (5, 6) are located on the opposite side of the secondary winding (12) which is at a high-voltage potential. The core material used is a ferrite torus of circular cross-section.

Description

For the operation of an X-ray system two different ones are used Transformer types required, a high voltage transformer to accelerate the electrons and a heat converter or heating transformer. The heating converter generates a heating voltage in the Range of approx. 3.5 V-25 V and causes the franking Electrons by electrical heating of the heating coil X-ray tube cathode. To change the x-ray current The tube heating can be regulated in the X-ray tube. More common transformers are used here, which are made of cut tape cores are built up. These transformers have through their mechanical structure of relatively large geometric dimensions Another disadvantage is that they are not against each other can be lined up in the event that several tubes or a multi-focus tube should be connected.

Another disadvantage of the cutting tape cores compared to the ver The ferrite core used is that the cutting tape core has a square or rectangular cross section and thus there is no close connection to the winding. In addition to the cutting tape cores, there are also normal ones Sheet laminated cores are used in heating transducers. The same disadvantages are to be mentioned here as with the cuts tape cores. Another disadvantage is that this Heat converters usually only with a frequency of 50 Hz operate.

Today's modern X-ray generators are no longer with one Frequency operated by 50 Hz. The high frequency inverters technology enables due to the high frequencies that up to 100 kHz can range, and suitable insulating materials Construction of small heat converters.

Because the X-ray tubes operate at different outputs heating converters also vary in their output Performance and thus also in the amount of potential against earth, in contrast to an operating voltage transformer. This has the consequence that special requirements for the insulating material changes must be made. Polypropylene, a high insulating plastic, meets all the requirements are necessary, a heating converter in the smallest possible space build up.

Further advantages and features of the inventive subject matter are based on the more or less schematic in the drawings shown table and execution described below examples explained in more detail.  

The primary winding ( 2 ) is on a polypropylene bobbin ( 1 ), which is rounded at the ends. The primary winding is covered by an insulating layer ( 3 ). The screen winding ( 4 ), which is crimped over the rounded ends of the coil former ( 1 ), forms the safe end. The shield winding ( 4 ) is not short-circuited in itself, but has a finite opening ( 8 ) opposite the connection ( 5 ). On each side of the shield winding ( 4 ) there are notches ( 7 ), which ensure safe derivation of the connections ( 5 ) and no protruding edges at the opening ( 8 ). The electrical connection ( 6 ) of the shield winding ( 4 ) is attached to one end.

The coil former ( 9 ) of the secondary winding ( 10 ) is also made of polypropylene and embeds the secondary winding ( 10 ) securely against rollovers on all sides with the minimum wall thickness. After the secondary winding ( 19 ) has been applied, the cover ring ( 11 ) is pushed over the coil former ( 9 ). From this cover ring ( 11 ) made of polypropylene is formed in the outer Formgestal device so that the outer surface is tapered from the center to the sides. The insulation half-shells ( 13 ) are of opposite conical design on the inner surface ( 14 ).

The assembly takes place in the following steps:

The primary winding and the secondary winding are prefabricated. The secondary winding ( 10 ) provided with the cover ring ( 11 ) is pressed with the aid of a tool into the lower insulation half-shell ( 13 ). Make sure that the connections ( 12 ) are exactly on the bushing ( 15 ). The primary winding with its axially led out connections ( 5, 6 ) is now placed centrally in the secondary winding. The end is formed by the second insulation half-shell ( 13 ), which is also pressed onto the protruding second half of the secondary winding by means of a tool. Characterized in that the outer inner surfaces ( 14 ) run conically in opposite directions as the cover ring ( 11 ), a quasi-homogeneous connection between the cover ring and insulation half shells is formed after assembly.

This type of connection can only be carried out if all used individual parts are manufactured in tight tolerances. This type of installation creates an almost infinitely long creep paths, which represent optimal isolation. When from closing heat process also anneals the material. The unit created from individual parts is guaranteed but an even wall thickness on all sides.  

So that the two insulation half-shells ( 13 ) are not inadvertently separated by mechanical external influences, they are connected with suitable highly insulating means ( 16 ). As can be seen from FIG. 4, no parts protrude in the axial direction after assembly. This con structive design has the advantage that several heating transducers can be connected directly to one another ( 18 ). Such a package of heating transducers can be easily installed in an X-ray generator.

The connections ( 5 ) of the primary winding and the shield winding ( 4 ) are screwed onto the outer surfaces. The final step is the assembly of the ferrite core ( 19 ), which consists of two halves. The ferrite core ( 19 ) is completely enclosed by the two insulation shells ( 13 ). The half insulation shells ( 13 ) have in their central center a hole through which one leg of the U-shaped ferrite core half passes. This leg is enclosed by the coil body ( 1 ) of the primary winding, which in turn is mechanically supported against the stop ( 17 ) and is thus fixed against slipping.

The second leg of the U-shaped ferrite core half ( 19 ) lies in the indentation ( 21 ). This indentation ( 21 ) ensures that the ferrite core ( 19 ) is secured against external mechanical stresses. At the same time, this constructive measure ensures that the heating transducer is significantly smaller in its mechanical dimensions than known heating transducers in the version with a cutting band core. Despite the enormous small mechanical dimensions, the heating converter delivers just as great a power as heating converters with ribbon cores.

By using a ferrite core with a circular Cross section is also a close magnetic coupling to the Given primary and secondary windings.

The two ferrite core halves are on their abutting surfaces glued together with a suitable adhesive. This is necessary agile, so that even the smallest ver shifts of the two ferrite core halves are not inadmissible Can cause induction change.  

Due to the constructive measure that only one leg is wound, the insulation precautions of the secondary winding ( 12 ), which is at high voltage potential, can be solved well. This is shown clearly in FIG. 4. The ferrite core ( 19 ) and the connections of the primary winding ( 5 ) and the shield winding ( 6 ) lying at ground potential are located opposite the connection of the secondary winding ( 12 ), which is at high voltage potential.

An additional insulation measure is not necessary because the constructive construction all required minimum clearances ensures. In contrast, large insulation measures are used conventional cutting core.

The invention thus shows a heating transducer which in its mechanical dimensions is extremely small and still with 125 kV can be operated.

Descriptions of the drawings

The subject of the registration is clearly recognizable by following drawings:

Fig. 1 sectional view of the primary winding with shielding winding,

FIG. 2 primary and shield winding with connections - seen from above,

Fig. 3 secondary winding with insulating half-shells,

Fig. 4 assembly drawing of the heating transducer.

• Reference numeral ( 1 ) coil former of the primary winding
  ( 2 ) primary winding
  ( 3 ) insulation
  ( 4 ) shield winding
  ( 5 ) Primary winding connections
  ( 6 ) Connection of the shield winding
  ( 7 ) Notching
  ( 8 ) Opening the shield winding
  ( 9 ) Bobbin of the secondary winding
  ( 10 ) secondary winding
  ( 11 ) cover
  ( 12 ) Secondary winding connections
  ( 13 ) Insulation half-shell
  ( 14 ) Conical inner surface
  ( 15 ) Execution for secondary connections
  ( 16 ) Lanyards
  ( 17 ) Stop for primary winding
  ( 18 ) Stack connection
  ( 19 ) ferrite core
  ( 20 ) adhesive surface
  ( 21 ) indentation

Claims (6)

1. Heating converter as a flow converter, operated with an inverter, for an X-ray generator for feeding the X-ray tube heating, the magnetic core of which consists of two U-shaped halves of ferrite core, which are insolubly glued to one another and whose bobbin and covers are made of polypropylene, characterized in that the heating converter with a ferrite core ( 19 ) made up of two halves with a circular cross section, one leg of the ferrite core ( 19 ) being arranged on one side in an indentation ( 21 ) in the insulation half-shells ( 13 ) and thus not being exposed to any mechanical stress due to the heating transducer being fastened , with the other leg centrally embedded in two identical insulation half-shells ( 13 ), the connections of the primary winding and the shield winding are on the side where the ferrite core lies in the indentation and the secondary high-voltage connections are on the opposite side and with 125 kV b can be driven. 2. Heating converter for an X-ray generator according to claim 1, characterized in that the insulation half-shells ( 13 ) on the side of the secondary high-voltage connections are connected with means made of highly insulating material ( 16 ). 3. heating converter for an X-ray generator according to claim 1, characterized, that the individual heating transducer is designed so that it themselves without additional constructive means can be connected and is therefore stackable into a package. 4. Heating converter for an X-ray generator according to claim 1, characterized in that the primary winding ( 2 ) is enclosed by a shield winding ( 4 ) which is not short-circuited, has notches ( 7 ) at the connection outlets and is at ground potential. 5. Heating converter for an X-ray generator according to claim 1, characterized in that the cover ring ( 11 ) of the secondary high-voltage winding ( 10 ) is conical in the axial direction outside on both sides and thus a quasi-homogeneous connection after assembly with the insulation half-shells ( 13 ), which are formed in the opposite axial direction in the opposite direction. 6. Heating converter for an X-ray generator according to claims 1, 4 and 5, characterized in that the primary winding is embedded without additional fastenings in the insulation half-shells ( 13 ) which have stops ( 17 ) on the end faces.