ELECTRICAL INTERFACE OF A VEHICLE

Description

[0001] The invention relates to an electrical power interface of a vehicle, in particular a commercial vehicle or a rail vehicle.

[0002] With temporary electrical connections, the quality of the electrical contact at the connection point, and therefore the contact resistance, is usually unknown. This can lead to problems, especially with power interfaces that transmit high power. For example, the connection interface can be overloaded if the contact quality between the power contacts forming the interface is poor and the transmission power is not matched to it. This problem can occur particularly with temporary power interfaces where power contacts are exposed to direct environmental influences. Examples of such temporary power interfaces include an external charging port on a plug-in hybrid vehicle or a pantograph, e.g., a power rail.a pantograph, of a rail vehicle or bus, which can be brought into contact with a current-carrying line to form a power path.

[0003] From DE 10 2005 042 087 B3, a method for monitoring the condition of a current collector in contact with a power line is known, wherein the current collector is designed such that strain gauges are provided on it to measure the mechanical strain of the current collector caused by a contact force between the power line and the current collector. Conclusions about the quality of the electrical contact can be drawn from the mechanical strain. A disadvantage of the known method is that it is specifically designed for current collectors of power lines and cannot be readily transferred to other power interfaces, where, as a rule, no easily measurable mechanical strain of a power contact occurs, or at least this strain does not correlate with the quality of the electrical contact.Another disadvantage is that the process requires a comparatively complex design of the current collector due to the necessary installation of strain gauges.

[0004] WO 2005 044 614 A1 discloses the method of determining the temperature at an electrical power interface and drawing conclusions about the quality of the electrical contact from the measured temperature. A disadvantage of the described current collector is that a fiber Bragg grating is required for temperature measurement, as well as a correspondingly complex device for evaluating the sensor signals.

[0005] In DE 10 2010 026 435 A1, it is also proposed to use a temperature sensor to classify the electrical contact between a first terminal element of a battery and a second terminal element, and to classify the electrical contact using a control device based on the temperature sensor's detection signal. As a further variant, it is also proposed to additionally determine a voltage at each of two power contact pairs, which is applied to the contacting power contacts of one power contact pair, and then to draw conclusions about the quality of the electrical contact by comparing the two voltage values. A disadvantage of the described approach is that both a temperature measurement and a voltage measurement at two different measuring points, i.e.,This requires two different power contact pairs and is therefore complex to implement. A further disadvantage is that the proposed approach to voltage measurement does not allow conclusions to be drawn about the quality of an individual electrical contact between two power contacts of a power contact pair, but only provides a statement about the overall contact quality of an arrangement consisting of two power contact pairs and the conductors arranged between them.

[0006] DE 20 2009 012 471 U1 discloses a measuring device for the continuous detection of the contact resistance between a power line and a sliding contact of a pantograph for an electrically powered vehicle. Two sliding contacts are slid against the power line, which can be an overhead line or a conductor rail, at a potential difference from each other. One of the sliding contacts serves to transmit the electric current for the vehicle's power supply, its contact resistance together with the vehicle's internal resistance forming a first voltage divider with a tap. The second sliding contact, with its contact resistance together with a high-impedance resistor, forms a second voltage divider with a tap at which a reference voltage is applied.The voltage dividers are connected to a data acquisition device via the taps, which measures the contact resistance of the sliding contact by measuring the voltage difference across the sliding contacts and the current supplying the vehicle.

[0007] EP 2 670 622 A1 discloses a method for protecting a charging cable in a charging device for charging the traction battery of an electrically powered vehicle. In this method, a resistance value is determined that corresponds to the magnitude of the electrical resistance between two contacts of the charging cable, where the magnitude of the electrical resistance indicates the current-carrying capacity of the charging cable. Depending on the determined resistance value, one of several line protection devices arranged in the charging device is switched into the charging current path.

[0008] US Patent 2009 / 286427 A1 discloses a connector arrangement comprising an elongated element, wherein the elongated element includes at least two electrically conductive areas on its outer surface. The at least two electrically conductive areas are insulated from each other and form a first connector. A second connector is arranged inside the elongated element and is accessible from an end face of the elongated element, wherein the second connector is configured to be used independently of the first connector.

[0009] It is therefore an object of the invention to provide an electrical power interface that avoids the disadvantages of conventional electrical power interfaces. In particular, the invention aims to provide a temporary electrical power interface that allows for the detection of the state of an electrical contact between the power contacts of a power contact pair.

[0010] These problems are solved by an electrical power interface of a vehicle, in particular a commercial vehicle or a rail vehicle, according to the features of the main claim. Advantageous embodiments and applications of the invention are the subject of the dependent claims and are explained in more detail in the following description with partial reference to the figures.

[0011] The electrical power interface comprises a first power contact that can be brought into contact with a second power contact to establish an electrical power path. The first power contact thus represents a first electrical connection element of a power contact pair, which can be brought into contact with a second electrical connection element to form an electrical connection. For the purposes of this invention, an electrical power interface of a vehicle is understood to be an electrical interface designed for energy transmission, for example, for the transmission of energy used to propel the vehicle, in contrast to an electrical signal interface, which is designed for signal transmission. Examples of such power interfaces of vehicles are an external charging interface of a plug-in hybrid vehicle or a current collector, e.g.,a pantograph, of a rail vehicle or bus, which can be brought into contact with a current-carrying line to form a power path.

[0012] The electrical power interface further comprises an auxiliary contact, which is electrically isolated from the first power contact. The auxiliary contact is further arranged relative to the first power contact such that, when the first and second power contacts are brought into contact to form the electrical power path, the auxiliary contact also makes electrical contact with the second power contact, the auxiliary contact being electrically connected in parallel to the first power contact via a measuring path.

[0013] Furthermore, a measuring device for monitoring the condition of an electrical contact between the first power contact and the second power contact may be provided. This device is designed to determine a voltage drop across the electrical power interface and / or a quantity correlated with the voltage drop. For example, the measuring device may be a voltage measuring device that measures the voltage difference between the auxiliary contact and the first power contact, which depends on the quality of the electrical contact between the first and second power contacts. In other words, the contact resistance at the power interface is determined.

[0014] A particular advantage of the present invention is therefore that, by means of a simple constructive extension of a conventional power interface by providing the auxiliary contact and the measuring path, the contact resistance of the electrical contacting can be measured, and it is thus possible to detect and evaluate the quality of the electrical contacting of a single power contact pair.

[0015] It is emphasized that the terms "first" service contact and "second" service contact are chosen arbitrarily and are only intended to express that the auxiliary contact is located at one of the two service contacts of a service contact pair.

[0016] According to a particularly preferred embodiment, the electrical power interface is a temporary power interface. A temporary power interface within the meaning of this invention is a mechanically separable electrical power interface, for example, a plug connector. The term "temporary" is intended to express that the two contacts forming the power interface can be detachably connected to one another. The temporary power interface is thus an electrical interface in which a temporary electrical connection can be established via the first power contact and the second power contact. For example, the first power contact and the second power contact can be in contact or out of contact depending on an operating state of the vehicle.Such a temporary electrical connection can also last for several hours or days, for example when charging a plug-in hybrid vehicle via its external charging interface.

[0017] In one advantageous variant of this design, the temporary power interface can be a charging interface of a plug-in hybrid vehicle for connecting an external electrical power source. According to another variant, the first power contact can be a pantograph for the overhead line of a rail vehicle or bus.

[0018] The auxiliary contact and measuring path can be designed for negligibly small currents compared to the primary power contact. Furthermore, the measuring device can be designed such that the current through it is negligibly small, which is approximately achieved, for example, by the very large and ideally infinitely high internal resistance of the measuring device, which is, for instance, a voltmeter. Additionally, the measuring path can be designed such that the voltage drop in the measuring path is negligibly small.

[0019] In other words, the auxiliary contact, the measuring path, and / or the measuring device can be designed such that no current, or a negligible current, flows when the voltage drop or contact resistance under load is determined at the power interface via the auxiliary contact and the measuring path. The auxiliary contact is therefore preferably not designed as a power contact. This allows the magnitude of the contact resistance or the voltage drop under load, and thus the quality of the electrical contact, to be precisely determined.

[0020] One possible implementation according to the invention provides that the measuring path has a first line that is contacted at the first power contact and a second line that is contacted at the auxiliary contact.

[0021] According to a further embodiment, the external power interface can include a control device configured to reduce the power to be transmitted via the electrical power path or to terminate the transmission of electrical power via the electrical power path if the voltage drop measured by the measuring device under load or the quantity correlated with the voltage drop exceeds a predetermined threshold.

[0022] Therefore, if the contact resistance or voltage drop under load becomes too high, the power to be transmitted can be reduced, even to the point of shutdown, to prevent overload and damage to the power interface.

[0023] The invention is not limited to a specific design and type with regard to the constructive design of the first and second power contacts or the type of electrical power interface.

[0024] According to one embodiment, the electrical power interface can comprise a plug that can be brought into contact with a second power contact designed as part of a plug socket. In this embodiment, both the first power contact and the auxiliary contact can be designed as a section of a plug element of the connector, connected to each other by an electrically insulating section of the plug element. The plug element is understood to be the part of the plug that is inserted into a correspondingly designed socket opening of the plug socket for electrical contact.

[0025] According to one variant of this embodiment, the auxiliary contact can be arranged at an end section of the connector. This variant allows for the modification of conventional power interfaces with minimal design effort.

[0026] It is possible for the auxiliary contact to be located on the end section of the plug element that, when the plug is inserted into the socket, faces the socket's insertion opening. This arrangement offers the particular advantage that the auxiliary contact is at the rear end of the plug element with respect to the insertion direction and therefore tends to "see" a slightly higher contact resistance than if it were located at the opposite end. This arrangement of the auxiliary contact thus enables particularly sensitive detection of insufficient connection quality, which can be caused, for example, by incomplete insertion of the plug element into the socket opening.

[0027] However, according to an alternative variant, the auxiliary contact can also be located on the end section of the plug that, when the plug is inserted into the socket, faces away from the socket's insertion opening and thus towards the socket's base or end. Furthermore, according to another variant, the auxiliary contact can be located on a middle section of the plug or even on any section of the plug.

[0028] Another aspect of the invention relates to a vehicle, in particular a commercial vehicle or a rail vehicle, with an electrical power interface according to one of the preceding aspects. For example, the vehicle can be configured as a bus and the first power contact as a current collector, preferably as a pole or pantograph, for a current-carrying overhead line. Another possible implementation according to the invention provides that the vehicle is configured as a commercial vehicle and the first power contact as a charging interface for connecting an external electrical power source.

[0029] Further details and advantages of the invention are described below with reference to the accompanying drawings. These show: Figure 1 is a schematic representation of a power interface according to a first embodiment; Figure 2 is a schematic representation of a power interface according to a second embodiment; and Figure 3 is a schematic representation of the measurement principle.

[0030] Figure 1Figure 1 schematically illustrates a cross-sectional view of a plug 10 of a temporary power interface with a cylindrical plug element 10a, which can be inserted into a corresponding plug socket 20 to establish an electrical power path. The components shown by lines 1, 11, 21, and 2 in bold form the power path. To establish the power path, the power contact 11 of the plug element 10a is inserted into the socket-shaped second power contact 21 of the plug socket 20, which forms a cylindrical cavity 24, such that the outer cylindrical surface of the power contact 11 touches the inner cylindrical surface of the second power contact 21 to form an electrical contact. Reference numerals 1 and 2 denote the connecting leads for the power path.

[0031] If the power contact 11 is tilted or not fully inserted into the socket of the power contact 21, or if the electrical contact between the power contact 11 and the power contact 21 is otherwise impaired, e.g. due to contamination on the contact surfaces, overloads may occur at the electrical power interface.

[0032] In order to be able to detect the state of the electrical contact, in contrast to a conventional power contact, an auxiliary contact 14 is also provided at the first power contact 11, which is electrically insulated via an insulation section 13 and is fixedly arranged on the first power contact 11.

[0033] Here, the auxiliary contact 14 is arranged on the first power contact 11 in such a way that, when the first power contact 11 is inserted into the socket-shaped second power contact 21, the auxiliary contact 14 is also electrically in contact with the second power contact 21 (in Figure 1 (not shown).

[0034] Furthermore, a measuring path is provided, formed from a first measuring line 3, which is contacted at the first power contact 11, and a second measuring line 4, which is contacted at the auxiliary contact 14, so that the auxiliary contact 14 is electrically connected in parallel to the first power contact 11 via the measuring path 3, 4.

[0035] In the present example, the electrically conductive contact surface of the cylindrical first power contact 11 is arranged on an insulating material 17 that runs inside the cylindrical first power contact 11. The measuring lead 4 of the measuring path runs through the insulating material 17 to electrically isolate it from the electrically conductive contact surfaces of the first power contact.

[0036] The two measuring leads 3, 4 of the measuring path lead to a measuring device (not shown) that measures the voltage difference between the auxiliary contact 14 and the first power contact 11, which depends on the contact quality between the first power contact 11 and the second power contact 21.

[0037] Thus, the contact resistance of the electrical contact of the power contact pair 11, 21 can be measured. If, for example, the voltage measured by the measuring device via the measuring path is greater than a predetermined threshold value, this can be considered an indication of excessively high contact resistance at the power contact pair 11, 21.

[0038] A control device (not shown) is provided and configured to reduce the power to be transmitted via the electrical power path or to terminate the transmission of electrical power via the electrical power path if the voltage drop measured by the measuring device under load or the quantity correlated with the voltage drop exceeds a predetermined threshold.

[0039] Unlike the power contacts 11 and 21, the auxiliary contact 14, which serves only as a measuring contact, can be designed for small currents compared to the currents flowing through the power contact pair 11, 21. In other words, the auxiliary contact 14, the measuring path 3, 4, and the measuring device are designed such that when measuring the voltage drop and / or the quantity correlated with the voltage drop in the form of the contact resistance, no current or a negligible current flows through the auxiliary contact 14 and the measuring path 3, 4.

[0040] In this context, reference is made to Figure 3Reference is made to the schematic diagram, which again illustrates the measurement principle. The power path is again shown using the connecting leads 1 and 2. Depending on the quality of the electrical contact between the first and second power contacts, a different contact resistance 5 (transmission resistance) is formed at the power interface, through which a power current I flows. Based on the principle of four- and three-wire measurement, a negligibly small measuring current is injected via the auxiliary contact and the measuring path 3, 4, and the voltage U, which occurs across the contact resistance, is tapped off in parallel. From this, a measure of the state of the electrical contact between the two power contacts of the contact pair can be directly derived.

[0041] The in Figure 1The illustrated embodiment can be used, for example, to implement a charging interface for a hybrid vehicle to connect an external electrical energy source.

[0042] Figure 2 schematically illustrates another embodiment for the realization of a temporary power interface between a vehicle contact 30, e.g. of a bus or rail vehicle, and a rail 40. Figure 2 schematically shows a cross-sectional view in the longitudinal direction of rail 40.

[0043] In this case, the vehicle contact 30 is equipped with a stamp-shaped current collector 31, which can be brought into contact with a current-carrying running rail 41 ( Figure 2 This again only shows the state in which the pantograph 31 is not in contact with the conductor rail 41).

[0044] Reference numbers 1 and 2 denote the power connections of the power path. Such pantographs 31 on buses are known from the prior art and do not need to be described in more detail here.

[0045] In contrast to conventional pantographs, according to the exemplary embodiment an auxiliary contact 34 is attached to the pantograph 31 via an electrical insulation 33, such that when the pantograph is brought into contact with the running rail 41, the auxiliary contact 34 also rests on the surface of the running rail 41 and makes electrical contact with it.

[0046] The auxiliary contact 34 is electrically connected in parallel to the pantograph 31 via a measuring path 3, 4. The measuring path comprises a first measuring line 3, which is electrically contacted at the pantograph 31, and a second measuring line 4, which is contacted at the auxiliary contact 34. Not shown is the measuring device for monitoring the condition of the electrical contact between the pantograph 31 and the running rail 41. This device is connected to the two measuring lines 3, 4 of the measuring path and measures the voltage drop between the auxiliary contact 34 and the pantograph 31. The measurable voltage drop depends on the contact quality and thus on the resulting contact resistance between the pantograph 31 and the running rail 41.

[0047] Furthermore, it should be noted that a power interface can be implemented in an analogous manner for an overhead line current collector, also called a pantograph. According to this modification, the representation would be in Figure 2 rotated by 180°, and in this variant the contact line 41 would be designed as an overhead line and the current collector 31 as a pantograph. Reference symbol list

[0048] 1, 2 Power path connection leads 3, 4 Measuring path measuring leads 5 Contact resistance 10 Plug 10a Plug element 11 First power contact 13, 33 Electrical insulation between auxiliary contact and first power contact 14, 34 Auxiliary contact 17 Electrical insulation 20 Socket 21 Second power contact 23 Insertion opening 24 Receiving cavity 30 Vehicle contact 31 Pantograph 40 Rail 41 Running rail

Claims

1. An electrical power interface of a vehicle, preferably a utility vehicle or a rail vehicle, comprising a first power contact (31) that can be brought into contact with a second power contact 41) to produce an electrical power path, wherein the first power contact (31) is a current collector for a catenary wire of a rail vehicle or a bus, and the second power contact (41) is a current-carrying conductor rail; an auxiliary contact (34) that is arranged so as to be electrically insulated from the first power contact (31) and that is arranged with respect to the first power contact (31) in such a way that, when the first power contact (31) and the second power contact (41) are brought into contact with one another to form the electrical power path, the auxiliary contact (34) likewise makes contact with the second power contact (41), wherein the auxiliary contact (34) is connected electrically in parallel with the first power contact (31) via a measurement path (3, 4); and a measurement device for capturing the state of an electrical contact-connection between the first power contact (31) and the second power contact (41) that is configured to determine a voltage drop across the electrical power interface and / or a variable correlating with the voltage drop via the measurement path (3, 4), characterized in that the auxiliary contact (34) is attached to the first power contact (31) via an electrical insulation (33) such that, when the first power contact (31) is brought into contact with the second power contact (41), the auxiliary contact (34) likewise rests on the surface of the second power contact (41) and electrically contacts the second power contact (41).

2. The electrical power interface according to Claim 1, characterized in that the electrical power interface is a temporary power interface.

3. The electrical power interface according to one of the preceding claims, characterized (a) in that the auxiliary contact (34) and the measurement path (3, 4) are configured for currents that are negligibly small in comparison to the first power contact; and / or (b) in that the auxiliary contact (34), the measurement path (3, 4) and / or the measurement device is / are configured in such a way that no current or a negligibly small current flows via the auxiliary contact (34) and the measurement path (3, 4) during measurement of the voltage drop or the variable correlating with the voltage drop by means of the measurement device; and / or (c) in that the measurement path (3, 4) has a first line (3) that is in contact with the first power contact (31), and a second line (4) that is in contact with the auxiliary contact (34).

4. The electrical power interface according to one of the preceding claims, characterized by a control device that is designed to reduce the power to be transmitted via the electrical power path or to end the transmission of electrical power via the electrical power path if the voltage drop measured by means of the measurement device under load or the variable correlating with the voltage drop exceeds a predetermined threshold value.

5. A vehicle, in particular utility vehicle or rail vehicle, comprising an electrical power interface according to one of the preceding claims.

6. The vehicle according to Claim 5, characterized in that the vehicle is configured as a bus, and the first power contact is configured as a current collector, preferably as a plunger, for a catenary wire .