Method and device for testing whether a current collector is in contact

Abstract

A method and a device test whether there is contact between a current collector and a contact wire of an overhead line. The current collector is located on a motor vehicle driven by an electric motor, and the contact wire extends in a direction of travel. The current collector has two contact regions oriented transversely to the direction of travel which are arranged one behind the other in the direction of travel and on each of which an end contact element is located. A pair of end contact elements located on the same side is connected to a measuring device and an electrical state variable is detected by the measuring device. Subsequently, it is determined in accordance with the detected state variable whether the pair of end contact elements is in contact with the overhead line.

Claims

1. A method for testing whether there is contact between a current collector and a contact wire of an overhead line, the current collector being disposed on a motor vehicle driven by an electric motor and the contact wire extending in a direction of travel, the current collector having two contact regions oriented transversely to the direction of travel and are disposed one behind another in the direction of travel and on each of the contact regions an end contact is disposed, a pair of end contacts disposed on a same end side is connected to a measuring device, wherein the measuring device having at least one measuring resistance and one reference resistance, which comprises the steps of: detecting an electrical state variable by means of the measuring device by determining a voltage drop via the at least one reference resistance via the measuring device, wherein the voltage drop varies depending on the contact between the end contacts and the overhead line, wherein when the at least one measuring resistance is bridged, the voltage drop only takes place via the reference resistance when the end contacts are in contact with the overhead line; and determining in accordance with a detected electrical state variable whether the pair of end contacts is in contact with the overhead line.

2. The method according to claim 1, wherein the measuring device has a voltage source and is supplied with a power supply voltage by the voltage source.

3. The method according to claim 1, wherein the voltage drop takes place via the measuring resistance and the reference resistance when the contact regions are in contact with the overhead line.

4. The method according to claim 1, which further comprises outputting a warning signal when the pair of end contacts is in contact with the overhead line.

5. A device for testing whether there is contact between a current collector disposed on a motor vehicle driven by an electric motor and a contact wire of an overhead line extending in a direction of travel, the device comprising: the current collector having two contact regions oriented transversely to the direction of travel and disposed one behind another in the direction of travel and on each of said contact regions an end contact is disposed at both ends of said contact regions; and a measuring device having a measuring resistance and a reference resistance, a pair of end contacts disposed on a same end side is connected to said measuring device and an electrical state variable being detected by means of said measuring device by determining a voltage drop via said reference resistance via said measuring device, wherein the voltage drop varies depending on the contact between the end contacts and the overhead line, wherein when said measuring resistance is bridged, the voltage drop only takes place via said reference resistance when the end contacts are in contact with the overhead line, said measuring device configured such that depending on a detected electrical state variable, it is determined whether said pair of end contacts is in contact with the overhead line.

6. The device according to claim 5, wherein said end contact is electroconductive and is isolated from said contact regions.

7. The device according to claim 5, wherein said measuring resistance and said reference resistance are ohmic resistors.

8. The device according to claim 5, further comprising a number of resistances for current limitation.

9. The device according to claim 5, wherein: said current collector has a controller; and said measuring device is integrated within said controller of said current collector.

10. The device according to claim 5, wherein the motor vehicle driven by the electric motor is configured as a truck driven by the electric motor.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 A roughly sketched representation of a motor vehicle driven by an electric motor,

(2) FIG. 2 A perspective partial view of a current collector,

(3) FIG. 3 A roughly sketched circuit diagram of a measuring device according to a first embodiment variant,

(4) FIG. 4 A roughly sketched circuit diagram of the measuring device according to a second embodiment variant and

(5) FIG. 5 A roughly sketched circuit diagram of the measuring device according to a third embodiment variant.

DETAILED DESCRIPTION OF THE INVENTION

(6) In the figures, parts having the same effect are represented by the same reference characters.

(7) FIG. 1 shows a roughly sketched illustration of a motor vehicle 1 driven by an electric motor. In the exemplary embodiment, the motor vehicle 1 is designed as a truck driven by an electric motor.

(8) For the electrical supply of the motor vehicle, an overhead line 8 extending in a direction of travel F is arranged above a carriageway 3. The overhead line 8 usually comprises a contact wire 10 and a plurality of support cables 11 on which the contact wire is located. The contact wire 10 is supplied with an electrical voltage.

(9) In order to be able to tap this voltage, the motor vehicle 1 has a current collector 2. The current collector 2 can be moved in and counter to a vertical direction V and has a current collector arm 12. A holding element 14 having two contact regions 16 is arranged on the current collector arm 12. The contact regions 16 are usually designed as wearing strips 18 (shown in FIG. 2).

(10) In order to keep the distance of the current collector 2 from the contact wire 10 as short as possible, the current collector 2 in the exemplary embodiment is arranged on the roof 19 of the motor vehicle 1.

(11) The current collector 2, which is at least partially illustrated in FIG. 2, is designed in the exemplary embodiment specifically as a double structure. I.e. so that both an electrical phase line 4 which is supplied with an electrical power supply voltage and an electrical ground line 6 which corresponds to an electrical zero potential are designed as an overhead line 8 and, in particular, as a contact wire 10, each of which can be contacted by means of a current collector 2. The contact wire 10 extends in a direction of travel. The background to this embodiment is a missing earth connection in the form of a rail, as is customary in rail vehicles.

(12) On account of the redundant and identical construction, with regard to the current collector 2, only the current collector 2 in contact with the phase line 4 will be discussed below. However, all the listed components, elements and/or properties apply analogously to the current collector 2 which is in contact with the ground line 6.

(13) As already shown in FIG. 1, the current collector 2 has a current collector arm 12. A holding element 14, also referred to as a rocker, is arranged on the current collector arm 12. In the exemplary embodiment, the holding element 14 has two contact regions 16, each with a wearing strip 18. The wearing strips 18 serve to make direct contact with the contact wire 10 so that in driving mode, for example, the wearing strips 18 grind along the contact wire 10 and thus ensure the electrical supply of the motor vehicle.

(14) End contact elements 20 are arranged at both ends of the wearing strips 18. In the exemplary embodiment, the end contact elements 20 have a bent shape counter to the vertical direction V (i.e. downwards) and are therefore also referred to as horns. The end contact elements 20 prevent the contact wire 10 from “slipping” under the contact region 16.

(15) Furthermore, the end contact elements 20 limit a maximum permissible lateral offset L. In the present case, the maximum permissible lateral offset L is understood to mean a deflection of the current collector 2 and in particular, the wearing strips 18, parallel to the contact wire 10 so that a functional contact with the contact wire 10 is ensured. At the same time, a maximum permissible lateral offset of the motor vehicle is predefined hereby.

(16) In order to prevent the maximum permissible lateral offset L being exceeded, the current collector 2 has a measuring device.

(17) FIG. 3 shows such a measuring device 22 according to a first embodiment variant. In this case, in the exemplary embodiment two end contact elements 20 form a pair of end contact elements which is electrically connected to the measuring device 22, for example in a wired manner by means of an electrical line. For this purpose, the electrical line is arranged on, for example, screwed to the end contact elements. In other words, in particular end contact elements 20 on the same end side are connected to the measuring device 22. That is to say, for example (viewed in the direction of travel F and the contact wire 10 arranged centrally on the wearing strips 18), either the two left-hand end contact elements 20 or the two right-hand end contact elements 20 are connected to the measuring device 22. Preferably, both the left-hand end contact elements 20 and the right-hand end contact elements 20 are connected to the measuring device 22 or, in each case, to a measuring device 22. In the exemplary embodiment, the connection of the two left-hand end contact elements 20 to the measuring device 22 is shown diagrammatically by way of example.

(18) In order to form an electrical conductivity, the end contact elements 20 have at least one electrically conductive, for example, metallized surface. Alternatively, the end contact elements 20 are made from a metal.

(19) Within the measuring device 22, the end contact elements 20 are connected to a voltage source 24 which generates a measurement voltage U.sub.M. If the motor vehicle and/or the current collector 2 now moves to the right (viewed in the direction of travel F), the contact wire 10 “approaches” the left-hand end contact elements 20. If the motor vehicle and/or the current collector 2 now moves so far to the right that the left-hand end contact elements 20 grind on the contact wire 10, the contact wire 10 short-circuits the two end contact elements 20 and thus closes a circuit which is formed by the voltage source 24 within the measuring device 22. Consequently, a current flows through the measuring device 22 which is detected in the measuring device 22. Alternatively, resistance is detected. In addition, the measuring device 22 has a current limiting element R.sub.1, for example, an ohmic resistor for current limitation.

(20) The method described is carried out analogously for a deflection of the motor vehicle and/or the current collector to the left, viewed in the direction of travel.

(21) An event in which the end contact elements 20 are in contact with the contact wire 10 is subsequently generated as a function of the flowing current, for example, by an evaluation unit 26 connected to the measuring device 22 and, for example, transmitted in the form of a warning signal to a driver of the motor vehicle and/or in the form of an actuating signal to a motor control unit of a current collector actuating unit. The current collector actuating unit then, for example, corrects the position using a method of the current collector 2. Alternatively, the warning signal is transmitted to a drive control unit of the motor vehicle 1 which, for example, performs a steering movement for “repositioning” of the motor vehicle into the maximum permissible lateral offset.

(22) FIG. 4 shows a roughly sketched circuit diagram of the measuring device 22 according to a second embodiment variant.

(23) In addition to the circuit according to FIG. 3, besides the voltage source 24 and the evaluation unit 26, the measuring device 22 has a resistance element 28, for example, an ohmic resistor. In the exemplary embodiment, the resistance element 28 is connected in parallel to the end contact elements 20. According to the second embodiment variant, a current I.sub.M flows within the circuit of the measuring device 22, the value of which is determined, for example, by the value of the resistance element 28. When the end contact elements 20 are in contact with the contact wire 10, the resistance element 28 is electrically bridged in the circuit. This bridging is based on the fact that the end contact elements 20 short-circuited by means of the contact wire 10 form a current path running parallel to the resistance element 28. However, this parallel current path has a resistance with a lower value than the current path in which the resistance element is arranged. Thus, the current of the circuit preferably flows across the end contact elements 20 and the total current of the circuit increases. This increase is detected by the measuring device 22 and the evaluation unit 26 then determines the output of the warning signal and/or the actuating signal according to the first embodiment.

(24) In addition, the measuring device 22 according to the second embodiment variant has a current limiting element R.sub.1, for example, an ohmic resistor for current limitation.

(25) FIG. 5 shows a roughly sketched circuit diagram of the measuring device 22 according to a third and particularly preferred embodiment variant.

(26) The measuring device 22 according to FIG. 4 has a measuring resistance element R.sub.M and a reference resistance element R.sub.R. The two resistance elements R.sub.M, R.sub.R are, for example, designed as ohmic resistors. The measuring resistance element R.sub.M has, for example, a value in the range between 50 kΩ and 70 kΩ. The reference resistance element R.sub.R has, for example, a value of 10 kΩ to 20 kΩ.

(27) The resistance elements are connected to a supply voltage U and are connected to the measuring device 22 in the manner of a voltage divider circuit. I.e. the measuring resistance element R.sub.M is connected in parallel to the end contact elements 20 in a manner analogous to the resistance element 28 according to FIG. 3. The reference resistance element R.sub.R is connected in series to the measuring resistance element R.sub.M. A measurement voltage U.sub.M used to determine whether the end contact elements 20 are in contact with the contact wire 10 is tapped in parallel with the reference resistance element R.sub.R. The power supply voltage U has, for example, a value in the range between 6V and 30V.

(28) If the end contact elements 20 are not in contact with the contact wire 10, the supply voltage U drops at the two resistance elements R.sub.M, R.sub.R connected in series. The measurement voltage U.sub.M is obtained according to the voltage divider rule from the difference between the supply voltage U and the value of the voltage drop across the measuring resistance element R.sub.M.

(29) If, for example, as already described above, the motor vehicle is displaced laterally with respect to the contact wire 10 in such a way that the end contact elements 20 grind on the contact wire 10, then the contact wire short-circuits the measuring resistance element R.sub.M and the voltage drop of the supply voltage U takes place solely on the reference resistance element R.sub.R. In other words, the measurement voltage U.sub.M corresponds to the supply voltage U. Any additional voltage drops due to, for example, production-related tolerances and/or additional components have been deliberately ignored.

(30) The measuring device 22 according to FIG. 4 also has three current limiting elements R.sub.1, R.sub.2, R.sub.3. For example, the current limiting elements R.sub.1, R.sub.2, R.sub.3 are designed as ohmic resistors. Furthermore, the measuring device 22 according to the third embodiment variant has a filter element 29, for example, for smoothing voltage peaks. For this purpose, the filter element 29 has a filter resistance element 30, for example, an ohmic resistor and a smoothing capacitor 32. The filter elements 30, 32 are arranged, in particular connected, in the manner of a low-pass filter in the measuring device 22.