Electricity: transmission to vehicles – Conductors – Third rail
Reexamination Certificate
1999-10-29
2001-11-20
Morano, S. Joseph (Department: 3617)
Electricity: transmission to vehicles
Conductors
Third rail
Reexamination Certificate
active
06318529
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a conductor rail having a rail-like support section made of metallic material, in particular a support section which is I-shaped in cross-section and has at least one component of another metal attached to it. Furthermore, the scope of the invention includes a use of the conductor rail and a process for its manufacture.
Known from U.S. Pat. No. 5,918,712 is a composite section featuring a support section or body made of light weight metallic material and at least one strip of another material of greater wear resistance which is joined to the support section or body during extrusion. Composite sections that are I-shaped in cross-section and exhibit a rail base, rail neck and rail head are described, the head part being covered by a strip running in the direction of the longitudinal axis; the latter provides a wear-resistant power transfer surface for the sliding contact shoe. This composite section is manufactured out of an aluminium alloy by means of extrusion in one single step during which the strip is fed into the extrusion press.
Known from U.S. Pat. No. 4,215,560 is a process for manufacturing conductor rails from a support section and at least one strip of another metal which forms at least part of the covering surface of the support section. Also here the support section is formed during extrusion by pressing a block of metal through the shape-giving opening of an extrusion die; at the same time the strip runs through the die opening parallel to the longitudinal axis of the die. Also—on making use of strips that have not been plated in advance—at least two composite sections are produced simultaneously, this in order to ensure adequate bonding between the support section and the covering layer; the areas of support section to be provided with a covering layer face each other and are fed a pair of strips that are in contact with each other and pass through the shape-giving opening in the die.
Although new power supply units are fitted with aluminium/steel composite conductor rails—this in view of their significantly better electrical conductivity—the electrification of the larger part of the approximately 11′000 km stretch of railway line, in particular in underground railways, involves soft iron conductor rails and so called light mail vehicles.
Retro-fitting such oonductor systems involves exchanging the conductor rails completely, which means down time and therefore—in addition to the investment and installation costs—also considerable losses due to down time on the stretch of track in question.
In view of this state of the art the object of the present invention is to enable steel conductor rails to be retrofitted; it should be possible to retro-fit the whole power supply facility with a ready-made conductor rail that meets the requirements e.g. during overnight down time and without expensive installation costs. Furthermore, it should be possible to employ ready assembled conductor rails with profile rails for new installations.
SUMMARY OF THE INVENTION
The foregoing object is achieved by way of the invention by providing a conductor rail which comprises a rail-like support section made of ferrous material, the rail-like support section being shaped in cross section to define at least one side channel, a light metal body, in particular an extruded section made of an aluminium alloy, which is mounted in at least one of the side channels of the rail or support section made of a ferrous material in particular soft iron, running parallel to the longitudinal axis of the rail or support section, said light metal body forming a conductor section the outward facing surface of which, as installed, has—at least in places—the component made of higher strength metal covering it.
According to another feature of the invention at least one of the side faces of the light metal body of that conductor section exhibits a saw-tooth profile or is provided with longitudinal ribs that define a channel-like cross-section on this side face.
The trapezium-shaped cross-section of the conductor section should advantageously taper towards its back face—this to match the side channel in the supporting section which tapers in cross-section towards the strut of that support section; the line along the middle of the conductor section is thereby preferably a line of symmetry with respect to the conductor section.
Such a conductor section—for which protection is sought independently in respect of its shape and use—makes it possible to retro-fit the widely common soft iron I-sections which exhibit on both sides of a central strut side channels delimited by flanges, and to do so without expensive boring and bolting operations; the light metal body matching the cross-section of the side channels may be secured by virtue of shape in the side channels and locked in preferably by the application of pressure. It has also been found to be favourable to join the conductor section by thermal means to the supporting section. Furthermore, on creating the mechanical fit a cold weld joint may be formed, and it is possible to secure the conductor in place by means of spot welding; the latter involves joining the component of a heavy metallic material—especially a steel strip—to the supporting section.
As a result of the invention therefore, for steel conductor rails already installed and in use—e.g. conductor rails according to standard DIN 43 156—an exactly fitting section of Al 99.5 or the like alloy with profiled side faces is provided, which can be pressed in situ into the conductor rail using an appropriately designed hydraulic device. In the process the projecting profile rills on the aluminium component are squashed; ideally cold welding takes place between the soft iron of the conductor rail and the retrofitted additional conductor material.
According to the invention the light weight metal of the conductor section can be provided with a blind slit running from its rear surface towards the strut in the support section, this in order to compensate for tolerances; for that purpose a strain relieving groove may be press formed into the light metal body or a longitudinal slit machined there. In both cases the provision of the groove, which can alter the cross-section, achieves an improvement in the mechanical locking—this also as an alternative to profiling the surface.
The steel covering which is integrated in the conductor section and is preferably joined in an intermetallic manner by an extrusion process, should as described enable the conductor section and the support section to be welded together without difficulty. This effect can also be achieved by choosing for the other component a groove shaped steel sheet of superior wear resistance and clamping the two side flanges of the steel sheet onto shoulder-like parts of the light metal body. In both versions it is favourable for the side faces of the support section or its flange to be approximately flush with the free surface of the covering component.
In the system comprising conductor rail and side-mounted conductor sections the transfer of electric power takes place at the side faces in the manner of a conductor section pressed in like a wedge. Initial calculations indicate that the electrical resistance of the conductor rail can be reduced by more than 50%, thereby reaching the range of new aluminium/steel composite conductor rails.
Further advantages, features and details of the invention are revealed in the following description of preferred exemplified embodiments and with the aid of the drawing which shows in.
REFERENCES:
patent: 3836394 (1974-09-01), Kugler et al.
patent: 4215560 (1980-08-01), Ames et al.
patent: 5161667 (1992-11-01), Kilburg
patent: 5263561 (1993-11-01), Plichta
patent: 5310032 (1994-05-01), Plichta
patent: 5918712 (1999-07-01), Wompner et al.
Bock Uwe
Herrmann Stephan
Alusuisse Technology & Management Ltd.
Bachman & LaPointe P.C.
McCarry, Jr. Robert J.
Morano S. Joseph
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