Electricity: transmission to vehicles – Conductors – At or below ground surface
Reexamination Certificate
1999-05-24
2001-03-27
Morano, S. Joseph (Department: 3617)
Electricity: transmission to vehicles
Conductors
At or below ground surface
C191S02300R, C191S039000, C191S040000, C191S0330PM
Reexamination Certificate
active
06206156
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention pertains to a contact rail assembly for electrically driven vehicles. Electrically driven vehicles receive power via current collectors from contact lines under electrical voltage. Contact wires used for contact lines are defined in European Standards. To supply electrical power to current collectors, the contact lines are arranged either as hanging wire structures over the tracks or are attached to contact rails. Contact rails are usually employed when power is provided under spatially constricted conditions. Compared to contact rails, suspended wire structures require more space since the contact wire is suspended by means of suspension wires that hang at short intervals from a support cable, and the support points on the support cable are located about 30 to 180 cm higher than the contact wire. The required “construction space” is described by the concept of “system height,” and the system height is equal to the vertical distance to the tracks at the support points. For financial reasons, in tunnels and overpasses, for example, in maintenance or assembly sheds, the system height must necessarily be designed to be very short. Furthermore, the contact wires and support cables are tensioned mechanically to 8-30 kN in order to allow travel speeds of the current collectors of up to 500 km/h. The tensioning devices thus required are complex structures that are difficult to set up, particularly in tunnels, since they require additional space. Another problem is that the current collector mounted on the vehicle is pressing upward with a force of 70-300 N, so that additional space is needed. For these reasons, rigid contact rails are used for travel sections with limited space relationships, such as tunnels or stretches under overpasses, since when using contact rails, no support cables are needed and the contact wire is not deflected upward, since it is attached to the contact rail. Thus, when using the contact rail, the required system height is less than for suspended support structures. Since contact rails can only be produced in limited lengths (usually, 12 m) and since they expand as a result of fluctuations in ambient temperature and as a result of heating due to current flow, they are cut into sections in tunnels, for instance, and are mechanically and electrically separated from each other. Contact rails are also cut into sections in the electrification of maintenance sheds, swing bridges and drawbridges.
The transition between two sections of contact rail causes problems. It is usual to run parallel sections of contact rail in a relatively long transition region of a length of 150 cm and more. A partial parallel run of sequential contact rails is cost intensive since, in general, more contact rails and additional support structures are needed. In addition, the transition of the current collector from one contact rail to another is not technically easy to handle. Due to the construction width of the contact rails, the parallel run of the contact wires attached to the contact rails occurs in a relatively long distance of 10 cm and more from each other, and over a length of 150 cm and more the sliding strip attached to the current collector slides along one or both contact wires alternately in an uncontrolled manner.
The result of one-side sliding of the contact wire means that the contact wires positioned at the contact rails do not exactly run at the same height, which can be attributed, for example, to inaccuracies in the manufacture or the “on-site assembly” of the contact rails. If the contact is along only one sliding contact wire, then an electrical field forms in the small air gap between the sliding contact wire that does not contact but is still under voltage, and the current collector, and the electric field increases as the size of the air gap decreases. As a result of the high field intensity in this region, arcing may occur. Arcing of any kind is undesirable, since it causes a successive burn-up or wear on the contact wire and on the current collector and produces induction-related voltage peaks that can damage the electric motor of the vehicle. If both sliding contact wires make contact, then arcing occurs due to the given inaccuracies with different contact forces, so that different, significantly fluctuating transition resistances occur at the two contact sites between contact wire and current collector, which is undesirable.
In addition to contact wires not exactly located at the same height, and the described electrotechnical problems, the contact point between contact wire and current collector can “skip” from one contact wire to the other under certain circumstances, and this produces an impulse on the current collector every time. This impulse is greater, the greater the speed of travel. Due to the relatively large spacing of the parallel-running contact wires in conventional contact rail assemblies, the impulses are applied relatively far outside the center of the sliding contact of the current collector, so that the occurring impulses cause undesirable, large torque impacts on the current collector and it is deflected accordingly. Another problem in known contact rail assemblies is that the ends of the contact rail must be curved upward in order to ensure that the end of the contact rail will not thread into the linkage of the current collector and destroy it. Bending up the relatively rigid contact rail is only possible if the bend is applied to a relatively long section, so that the mentioned long transition region will result. In addition, bending of the relatively rigid contact rail profile is only possible in a workshop, and as a rule, the 12 m long contact rail bars are connected with great effort.
SUMMARY OF THE INVENTION
The purpose of the present invention is to create a contact rail assembly that eliminates the above-mentioned disadvantages, and in particular, allows a good transition with little effort between two contact rail sections, which can be traversed at high speeds, with a long service life and requires little maintenance expense.
The underlying principle of the invention is that two sequential contact rails in the travel direction are arranged in a line and at a relatively short distance from each other, and at the opposing ends of the contact rails there is one transition horn, whose free ends extend into the transition region and do not contact each other.
Since the transition horns do not touch each other, in a first design example of the invention, the two contact rails or the associated transition horns are electrically and mechanically disconnected from each other. But for many applications it is desirable for there to be an electrical connection between two opposing transition horns. Thus, according to a second design example, the transition horns are electrically connected to each other by at least one separate contact section.
In both variants, the transition horns are configured and designed so that in a top view, they run into the contact rail assembly on one section of the transition region at a slant with respect to the contact rails, i.e., their free ends protrude out to the side, and run essentially parallel at a distance from each other. The two transition horns are essentially straight on this section. Since an electric field forms between the two transition horns, in the first-described variant of the invention, the spacing of the parallel-running transition horns must be large enough so that even at high humidity, no sparking or arcing can take place between the transition horns. For example, the middle spacing of the two transition horns is 55 mm, which represents a sufficient isolation spacing at an operating voltage of 1.5 kV. For the same reason, in the first variant, the free ends of the transition horns have a corresponding distance from the opposing contact rail.
Seen in a side view, the transition horns are positioned against the contact rails such that a contact wire attached to the underside of a transition horn passes smoothly and as a single piece onto the co
Furrer & Frey AG
Jules Frantz
Morano S. Joseph
Senniger Powers Leavitt & Roedel
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