Traction transformer

1. A traction transformer for railbound vehicles comprising:

an insulating liquid filled enclosure with a first and a second cover arranged at axial ends of the enclosure,

at least two windings contained in the enclosure,

a transformer core arranged outside the enclosure,

mounting means for mounting the transformer to the railbound vehicle,

wherein the mounting means are attached to the transformer core, and wherein the enclosure is clamped between at least two support elements pressing at the axial ends onto the first and the second cover; and

wherein the insulating liquid is a transformer oil.

2. The traction transformer according to claim 1 , wherein the mounting means are only fixed to the transformer core of the traction transformer.

3. The traction transformer according to claim 1 , wherein the enclosure is formed by two cylindrical inner housings and by a cylindrical outer housing partially surrounding the two cylindrical inner housings, wherein an enclosed volume of the enclosure between the two cylindrical inner housings and the cylindrical outer housing is filled with the insulating liquid, and wherein portions of the transformer core extend through the two cylindrical inner housings.

4. The traction transformer according to claim 1 , wherein the at least two support elements are adapted to the shape of the first cover and the second cover for preventing a magnetic stray field in an axial direction of the winding, wherein the shaped support elements act as shielding and prevent a distraction of the unwanted magnetic stray field to the railbound vehicle or to the rails.

5. The traction transformer according to claim 1 , wherein the enclosure has an eight-shaped cross section, and wherein the cross section being perpendicular to the axial direction of the windings.

6. The traction transformer according to claim 1 , wherein the insulating liquid comprises mineral oil, silicon oil, synthetic oil or vegetable oil and serves for electrical isolation of the windings and for cooling of the windings.

7. The traction transformer according to claim 1 , wherein the first and the second cover, the two cylindrical inner housings, and the cylindrical outer housing form an enclosed volume which is filled with the insulating liquid, and the windings which are accommodated in the enclosure are completely immersed in the transformer oil.

8. The traction transformer according to claim 1 , wherein the enclosure is attached to the transformer core by the at least two support elements.

9. The traction transformer according to claim 8 , wherein the enclosure is fixed to the transformer core by four support elements which are angled and in which two of them are arranged on the top of the transformer core at the axial ends of the enclosure and wherein the two other angled support elements are arranged at the bottom side of the transformer core at the axial ends of the enclosure.

10. The traction transformer according to claim 9 , wherein each of the angled support elements is screwed by one of its two legs direction to the transformer core, whereas the enclosure is clamped between the other legs, the atter ones press at the axial ends onto the first and second cover, and wherein the support elements on the top of the transformer core and the support element on the bottom side of the transformer core have adjusting screws to set the contact force for clamping the enclosure, and the adjusting screws are fixed on the leg of the support element which presses against the first cover or the second cover.

11. The traction transformer according to claim 1 , wherein the first cover and the second cover are liquid-tight sealed to the axial ends of the enclosure and wherein the first cover and the second cover each have at least one opening matching to a diameter of the at least one cylindrical inner housing, and wherein the portions of the transformer core partly extend through the at least one opening.

12. The traction transformer according to claim 11 , wherein the liquid-tight sealing is ensured by a glued joint and/or by a gasket and/or by welding.

13. The traction transformer according to claim 11 , wherein the mounting means are a frame with parallel sidebars and wherein the sidebars are fixed to the yokes and run along the yoke direction.

14. The traction transformer according to claim 13 , wherein the traction transformer comprises stiffening elements to absorb forces along the yoke direction, wherein the stiffening elements are attached to the side bars of the frame and to the portion of the transformer core partly extending through the at least one cylindrical inner housing.

15. The traction transformer according to claim 14 , wherein additional stiffening elements are attached to the support elements to absorb acceleration forces and are welded thereto, and the additional stiffening elements are positioned before and after the yokes, in particular are screwed to the transformer core, and prevent an unwanted movement of the transformer core along the X-direction.

16. The traction transformer according to claim 1 , wherein the traction transformer is of core-type and the mounting means are fixed to the yokes of the transformer core.

17. The traction transformer according to claim 16 , wherein the transformer core is of stack-lap type, and the mounting means, and the at least two support elements are screwed together perpendicular to the axial direction of the windings.

18. The traction transformer according to claim 17 , wherein at least four support elements are provided, wherein two of the at least four support elements are screwed together at each axial end of the enclosure, and wherein one of the yokes and one of the sidebars are arranged between the two support elements.

19. The traction transformer according to claim 1 , wherein the enclosure comprises a lightweight material, in particular glass fiber, epoxy based composite, or aluminum.

20. The traction transformer according to claim 19 , further comprising:

an insulation liquid filled enclosure with a first and a second cover arranged at axial ends of the enclosure;

at least two windings contained in the enclosure;

a transformer core arranged outside the enclosure;

mounting means for mounting the transformer to the railbound vehicle;

wherein the mounting means are attached to the transformer core, wherein the enclosure is formed by two cylindrical inner housings and by a cylindrical outer housing partially surrounding the two cylindrical inner housings, wherein an enclosed volume of the enclosure between the two cylindrical inner housings and the cylindrical outer housing is filled with the insulating liquid, and wherein portions of the transformer core extend through the two cylindrical inner housings,

wherein the insulating liquid is a transformer oil;

the enclosure is attached to the transformer core by at least two support elements;

the traction transformer is of core-type and the mounting means are fixed to the yokes of the transformer core; and

the transformer core is of stack-lap type, and the mounting means and the at least two support elements are screwed together perpendicular to the axial direction of the windings.

21. A traction transformer for railbound vehicles comprising:

an insulation liquid filled enclosure with a first and a second cover arranged at axial ends of the enclosure; at least two windings contained in the enclosure; a transformer core arranged outside the enclosure; mounting means for mounting the transformer to the railbound vehicle; wherein the mounting means are attached to the transformer core, wherein the enclosure is formed by two cylindrical inner housings and by a cylindrical outer housing partially surrounding the two cylindrical inner housings, wherein an enclosed volume of the enclosure between the two cylindrical inner housings and the cylindrical outer housing is filled with the insulating liquid, and wherein portions of the transformer core extend through the two cylindrical inner housings,

wherein the insulating liquid is a transformer oil; the enclosure is attached to the transformer core by at least two support elements; the traction transformer is of core-type and the mounting means are fixed to the yokes of the transformer core; and

the transformer core is of stack-lap type, and the mounting means and the at least two support elements are screwed together perpendicular to the axial direction of the windings.