Electricity: transmission to vehicles – Systems of distribution – Sectional
Reexamination Certificate
1999-08-16
2001-06-26
Sotelo, Jesus D. (Department: 3617)
Electricity: transmission to vehicles
Systems of distribution
Sectional
C191S00100A, C191S014000, C191S02200C, C191S02300R, C191S025000, C191S048000
Reexamination Certificate
active
06250442
ABSTRACT:
The invention concerns ground power supply devices for electric vehicles. It concerns rail vehicles and vehicles that are not guided by rails, for example electric private cars steered by a user or buses steered by a driver.
It is more particularly concerned with devices of the above kind in which a power supply track is made up of a sequence of segments electrically insulated from each other, and in which only the segments protected by the vehicle are live.
Electrified urban and intercity transport systems usually employ power supply devices including an overhead contact line. Overhead contact lines of the above kind are increasingly unacceptable in urban areas, in particular in historic towns, for aesthetic reasons.
Additionally, devices with overhead contact lines are not free of the risk of electrocuting pedestrians, in particular because of the risk of the contact line breaking.
German Patent DE 3 048 730 proposes a device in which a continuous live line forming a power supply busbar is disposed under a sectionalized rail laid on the ground on which pick-up shoes on the vehicle slide.
A terminal between each segment of the sectionalized rail and the continuous line is electrically connected to the continuous line which is offset downwards relative to the power supply rail when there is no vehicle in the segment concerned.
A magnetized bar under the vehicle attracts the terminal against the segment when the vehicle is above a given segment. The segment is then live by virtue of the electrical connection between the terminal and the live continuous line.
When the vehicle has passed, the terminal resumes its place set back from the power supply rail which is no longer live.
For safety reasons and to prevent short-circuits, the length of the power supply segments is such that only the segments covered by the vehicle are live.
The above device has a major drawback: although they are no longer live when the vehicle is not present, the segments can retain a high electrical charge.
Accordingly, when used in an urban environment, for example to supply power to a tram, there is a real risk of a device of the above kind electrocuting pedestrians.
Also, the device is designed for use with battery-powered vehicles and is ill-suited to use with high currents. Mechanical switches of the above kind require greater forces to separate them from the power supply segments if they carry high current, in which case this gives rise to highly undesirable electrical arcing. A device for biasing the terminals downwards able to exert forces of such magnitude would be costly and difficult to install in the relatively restricted space between the segments and the live continuous line.
Patent DE 4 329 935 proposes an electrical power supply device for electric vehicles of the battery powered car type.
In the above document the segments of a power supply track are longer than the vehicle. The segment over which the rear axle of the vehicle is located is live and the segment over which the front axle of the vehicle is located is earthed. The power supply current then passes between the rear axle and the front axle via the electric motor of the vehicle.
The above device has the major drawback that the live segment extends a great distance beyond the boundary of the vehicle.
The device therefore involves the risk of electrocuting pedestrians which makes it difficult to use anywhere that pedestrians may need to pass behind the vehicle.
Note that the earthing arrangements described in the above document could not applied to the system described in document DE 3 048 730 because the rail segment adjacent the live segment must be “floating”, i.e. not earthed.
Also, the system described in DE 4 329 935 inevitably causes discontinuities in the supply of power, which is highly undesirable, especially in the case of vehicles energized with a high current.
An aim of the present invention is to alleviate the above drawbacks by proposing a sectionalized ground power supply device in which the power supply segments are entirely located under the vehicle and all segments that are not within the footprint of the vehicle are earthed.
Another aim of the invention is to propose a ground power supply device in which failure of any component never leads to a segment that is not covered by the vehicle becoming live.
The device is particularly suitable for supplying power to an urban rail vehicle on a public road, such as a tram, but also for a power supply network for private vehicles steered by their users.
In accordance with the invention the above aims are achieved by a ground power supply device for electrical vehicles including a power supply track made up of segments separated from each other by insulative joints and each having a length less than half the length of the footprint of the vehicle and a switching device adapted to apply a supply voltage to a segment only when said segment is within the footprint of the vehicle characterized in that the vehicle has power supply rubbing member means the extent of which is greater than the length of the insulative joints and in that the switching device is adapted to apply the supply voltage to two adjacent segments when the rubbing member means are in simultaneous contact with the two segments and to earth one of the two segments a short time after said rubbing member means have left that segment.
The device of the invention can optionally include one or more of the following advantageous features:
the vehicle carries a control device adapted to energize any segment at least a part of which is in an activation area whose ends are on respective opposite sides of and beyond front and rear edges of the rubbing member means of the vehicle;
the distance between the front end of said activation area and the front edge of the power supply rubbing member means is greater than the product of the maximum speed of the vehicle and a maximum segment switching time;
the control device comprises two presence signal generators which define said ends of said activation area;
the device includes a control receiving track made up of insulated segments having the same lengths and the same locations as the segments of the power supply track and the signal generators comprise two rubbing members connected to a voltage generator on board the vehicle in contact over a limited distance with said control track;
the control receiving track and the power supply track are combined and the voltage generator generates an AC voltage superimposed on a supply voltage;
the control device has at least one current loop on board the vehicle and the device includes a set of current loops disposed successively along the power supply track and each adapted to transmit an electrical control signal when a magnetic field passes through it, the onboard loop and the loops disposed along the track being adapted to produce local magnetic coupling when the onboard loop is in line with one of the loops disposed along the track;
the loops have the same lengths and the same locations as the segments of the power supply track and the vehicle carries two onboard current loops disposed on respective opposite sides of and beyond front and rear edges of the rubbing member means which define said ends of said activation area;
the device includes a current return track and the vehicle carries a safety rubbing member in contact with the power supply track and connected directly to the current return track disposed to the rear of the rear end of said activation area at a distance from that end greater than the length of a power supply segment plus the product of the maximum speed of the vehicle and a maximum segment switching time;
the vehicle carries a return rubbing member for the power supply current from the motor of the vehicle in is contact with the power supply track and disposed ahead of the front end of the activation area at a distance from that end greater than the length of a power supply segment;
the vehicle carries a return rubbing member for the power supply current from the motor of the vehicle in contact with the pow
Brunet Stephane
Morin Bruno
Perraud Olivier
Jules Frantz F.
McCormick Paulding & Huber LLP
Societe Generale de Techniques et d'Etudes
Sotelo Jesus D.
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