Monitoring of the contact area in plug-in devices

Abstract

The invention relates to a plug device and a method for determining an electrical transfer characteristic, such as a transfer resistance (Ru) in a contact region between a first contact element (such as a socket BU) of a first plug device and a second contact element (such as a plug pin ST) complementary thereto of a second plug device. According to the method, the characteristic of a current path is evaluated, which includes the first contact element, the contact region and only the second contact element in the second plug device. It is thus possible to determine the transfer resistance (Ru) between two contact elements, such as a plug pin and a socket, by means of components which are only arranged in the plug device (such as a coupling or a plug).

Description

Technical Field

[0001] The invention relates to a method for determining an electrical transfer property, such as a transfer resistance in a contact region between two contact elements (plug pins, sockets) of a plug device and a plug device which is provided for carrying out such a method. Background Art

[0002] Electrical plug devices, such as plugs or sockets or couplings for high currents according to DIN VDE 0623, EN 60309-2 ("CEE plug devices") or IEC 62196 ("electric vehicle charging plug devices"), include metallic contact elements (plug pins in the plug and sockets in the socket), through which electrical contact is made when plugged together. Due to contamination, oxidation, weakening of the contact force, etc., non-negligible resistance may occur in the contact area between these contact elements. Especially for power plug devices with higher currents flowing during operation, such transfer resistance may lead to intolerable power losses. Because the lost power is converted into heat, there is also the risk of dangerous overheating. Therefore, in the prior art, different measures have been proposed for monitoring the temperature in the plug device. However, such a system can only react when heating has already occurred and thus a potentially problematic situation has occurred. Summary of the invention

[0003] Against this background, the object of the present invention is to provide alternative measures for determining or monitoring the function of a plug device. Preferably, these measures enable early identification of problematic situations.

[0004] This object is achieved by a method having the features of claim 1 and by a plug device having the features of claim 9. Advantageous embodiments are contained in the dependent claims.

[0005] The method according to the invention is used to determine the electrical transfer characteristics in the contact area between a contact element of a first plug device (hereinafter also referred to as "first contact element") and a contact element of a complementary second plug device which is complementary to the first contact element (hereinafter also referred to as "second contact element"). The first plug device can be a coupling with a socket as the first contact element and the second plug device can be a plug with plug pins as the second contact element or vice versa, wherein the plug devices generally include further components (housing, inserts, etc.) in addition to the contact elements. The method is characterized in that the characteristics of at least one current path are evaluated, the current path comprising:

[0006] - a first contact element,

[0007] - contact area, and

[0008] - Only the complementary second contact elements in the second plug device and any further contact elements of the second plug device.

[0009] The current path by definition forms an electrically conductive connection between two terminals, through which a direct current or at least an alternating current can flow or flows. If the terminals are identical, then an electrical circuit exists. Otherwise, a closed electrical circuit is typically established by connecting the terminals to the evaluation circuit.

[0010] The ends or connections of the current path are typically located in or are a component of the first plug device, so that the current path is completely accessible from the first plug device.

[0011] The conductivity of the current path can be conductive, that is to say allow the flow of direct current (wherein the level of the ohmic resistance is typically less than approximately 100 kΩ). In addition or as an alternative, there can be a capacitive conductivity of the current path, for example if the current path comprises a capacitor in a series connection (wherein the size of such a capacitor is typically greater than approximately 10 pF, preferably greater than approximately 100 pF, greater than 1 nF or greater than 3 nF).

[0012] The determination of the electrical transfer characteristic can be performed both qualitatively and quantitatively. A qualitative determination can consist, for example, in determining whether the transfer characteristic is suitable or unsuitable for safe operation. A quantitative determination relates in particular to the determination of the value of the transfer resistance between the first and second contact elements.

[0013] The method has the advantage that the electrical transfer characteristic can be determined solely from the perspective of the first plug device by using the described current path. In the second plug device, only the complementary second contact element (and possibly or in exceptional cases also one or more further contact elements of the second plug device) is used to complete the current path, but the complementary second contact element is anyway joined to the first contact element during the plugging process. As a result, therefore, no structural changes to the second plug device are necessary, so that the method is independent of the type, age, manufacturer, etc. of the second plug device used.

[0014] The specific composition of the current path used and the measurement principle used can be constructed differently. According to a first embodiment, the current path used has at least one detector, which is arranged in the first plug device and contacts the complementary second contact element in another (other) contact area when the two plug devices are plugged together. Such a detector usually does not exist in traditional plug devices, but is only or especially provided for this method. Through the detector, two contact areas are provided between the first plug device and the complementary second contact element in the plugged together state. Therefore, the current path basically realized in the first plug device can include the part of the second contact element (and only the second contact element of the second plug device) between the two contact areas. The transfer resistance in the contact area of ​​interest between the contact elements of the plug device is in this current path and is therefore available for measurement.

[0015] In the first improvement of the embodiment with the detector described above, the voltage drop that occurs when the operating current flows through the contact area of ​​interest is measured by the formed current path. "Operating current" is defined as flowing through the observed (and typically through at least two other) contact elements during the operation of the original setting of the plug device, for example, to drive a load, such as an electric motor or to charge a battery. For a force plug device, this operating current is in the range of one to three digit ampere values, so that a small transfer resistance will lead to a considerable and demonstrable voltage drop. This voltage drop also appears in the formed evaluation current path and forms an indicator for the transfer characteristics in the contact area of ​​interest. If the size of the operating current as the basis of the measurement is additionally known, the transfer resistance existing in the contact area can also be calculated in addition to the known voltage drop.

[0016] When using the probe, it should be noted that there is usually an unknown transfer characteristic in the contact area between the probe and the second contact element of the second plug device, which may make it difficult to determine the transfer characteristic in the contact area of ​​interest. Therefore, it is optional to establish a defined transfer characteristic between the probe and the second contact element of the second plug device before the evaluation or the measurement that causes the evaluation. There are different feasible solutions for this. For example, a contact pressure that is as well defined as possible and can be reproduced can be provided by design measures. The higher the contact pressure, the higher the possibility that oxides, outer layers, etc. are broken. However, a limit is set for the increase of the contact pressure: the operating force of the plug should only be slightly increased by the probe. As a supplement or alternative, a process that works by means of an electrical method can be used, in which a possible isolation layer (composed of oxides, outer layers, etc.) is broken through by applying a suitable voltage (hereinafter referred to as "breakdown voltage"). In this process, which is also called "sintering", the voltage in the transition area between the contact elements is usually at most in the order of magnitude of the fuse voltage of the material of the contact surface. This ensures a defined value or at least a defined maximum value.

[0017] According to another embodiment, the first plug device comprises two (or more) detectors, each of which has its own and separate contact area with respect to the second contact element. Thus, three or more current paths can be evaluated, which include different combinations of the at least three contact areas formed between (a) the second contact element and (b) the first contact element and / or different detectors. This allows multiple independent measurements to be performed, from which unknown variables such as, for example, transfer resistances can be determined.

[0018] In another embodiment of the invention, an induced voltage is generated in the current path used. This has the advantage that measurements can be made in the current path without mechanical / electrical contact, which measurements allow inferences about the transfer behavior of interest.

[0019] In a special embodiment of the above-mentioned embodiment, the current path in question forms a secondary coil (usually with a single winding) on ​​a magnetic core which is arranged in the first plug device and on which a primary coil is also arranged. The system can then be excited in a controlled manner via the primary coil, which causes the generation of an induced voltage in the secondary coil, that is, in the current path in question, via the magnetic core. The electrical properties of the current path depend on the transfer properties of interest in the contact region and can be manifested, for example, as a reaction in the primary coil. For example, the input impedance of the system can be determined on the primary coil, which depends in a defined manner on the transfer resistance in the contact region of interest.

[0020] Additionally or alternatively, the electrical properties of the current path can also be determined in the aforementioned case by means of a separate measuring coil which is laid around the current path.

[0021] The socket of the plug device is often designed in such a way that it includes two or more contact fingers arranged in parallel around a cylindrical cavity, which extend in parallel from a common base of the socket. Each of these contact fingers has its own transition region with respect to the inserted plug pin and can therefore be regarded as an independent "first contact element" within the scope of the method described here. However, for the operation of the plug device, usually only the transfer resistance formed by all contact fingers together with the associated plug pin (in a parallel connection) is of interest, so that the contact fingers of the same socket can also be treated as a single "first contact element" within the scope of the method described here. The transfer resistance with respect to this "first contact element" is then formed by the parallel connection of the transfer resistance with the individual contact fingers.

[0022] For a socket with multiple contact fingers, these can be electrically connected to one another at their free ("distal") ends, for example, by means of a spring coil that surrounds the outside and presses the contact fingers inward. If, on the other hand, two or more contact fingers of a socket are electrically separated from one another outside a common base, the current path under consideration can be formed in such a way that the contact fingers are arranged in series therein. A portion of the contact fingers then forms a first section of the current path and another portion of the contact fingers forms a second section, wherein the two sections are electrically connected on the one hand via the inserted plug pin and on the other hand via the common base of the contact fingers. In such a configuration, a portion of the contact fingers can be arranged, for example, on one side of a ring-shaped magnetic core and another portion of the contact fingers can be arranged on the other side of the magnetic core, so that a total of one turn of the secondary coil is formed as described above.

[0023] The above considerations also apply analogously to the case of plug pins which are separated in the longitudinal direction, in which part of this plug pin assumes the function of a contact finger.

[0024] For the more general structural form of the contact element, the magnetic core can also be arranged in a manner surrounding the contact area between the first and second contact elements. In this case, for example, the induction of a voltage can be achieved in the observed current path without depending on the vacancy of the contact fingers.

[0025] According to the design, the described method interacts differently with the common operation of the plug device. When determining the voltage drop in the contact area of ​​interest as discussed above, the operation of the plug device is necessary for the implementation of the method. When the evaluation is performed under the condition of generating an induced voltage, the high current flowing during operation can have a disruptive effect. Therefore, it can usually be preferred to synchronize the evaluation with the course of the working current according to the method according to the invention. This can mean, for example, in the sense of on / off synchronization, that the evaluation is only performed when there is no working current flowing, or conversely, the evaluation is only performed when there is a working current flowing. However, in addition, the synchronization can also be related to the modulation of the working current, for example if the measurement is preferably performed within the range of the zero crossing of the working alternating current.

[0026] According to a second aspect, the present invention relates to a plug device (also referred to as “first plug device” below), which has at least one first contact element, which, in the plugged-in state of the plug device, contacts in a contact area with a (complementary) second contact element of a complementary second plug device, wherein the plug device is configured to evaluate a property of at least one current path, which includes the first contact element, the contact area and only the second contact element in the second plug device and optionally further contact elements in the second plug device.

[0027] The device is thus configured to carry out a method according to one of the above-described embodiments. Therefore, explanations and modifications relating to the method also apply to the plug device in the same manner and vice versa.

[0028] According to a further development, the plug device preferably comprises at least one detector which is arranged in the first plug device and, in the plugged-in state with the second plug device, contacts a complementary second contact element in another contact region. The detector is typically electrically isolated from the first contact element so that it provides a separate electrical access to the second contact element.

[0029] In another embodiment, the plug device comprises a magnetic core which surrounds the first contact element and / or a detector and / or a contact area of ​​the type described above. With such a magnetic core, a voltage can be induced in the first contact element or the detector and thus in the current path under consideration. Preferably, a primary coil is also present on the magnetic core for this purpose. In addition, the magnetic core can optionally be closed all around or have local or distributed interruptions ("air gaps").

[0030] Furthermore, the plug device can have an evaluation circuit for evaluating the property of the mentioned current path in a method according to one of the above-described specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be explained in detail below based on an embodiment with the aid of the accompanying drawings.

[0032] Figure 1 A socket of a first plug device (coupler) and a plug as a second plug device having plug pins complementary to the socket are shown;

[0033] Figure 2 A current path is schematically shown, the current path comprising a socket, a plug pin and a detector on the socket side, the detector being in contact with the plug pin inside the socket;

[0034] Figure 3 Two embodiments of a current path are schematically shown, the current path comprising a plug pin, a socket and a detector on the plug side;

[0035] Figure 4 The current path is schematically shown, which includes the socket, the plug pins and the two socket-side detectors.

[0036] Figure 5 A current path is schematically shown, the current path comprising a socket, plug pins and a detector on the socket side, the detector being in contact with the plug pins outside the socket;

[0037] Figure 6 Shows Figure 2 The current path together with the superimposed equivalent circuit diagram;

[0038] Figure 7 An equivalent circuit diagram for direct resistance measurement is shown;

[0039] Figure 8 Shows Figure 7 An equivalent circuit diagram of , supplemented here with a circuit for operation, which is provided for measuring a voltage drop in the contact region under operating conditions;

[0040] Fig. 9 Shows Figure 8 Equivalent circuit diagram of , supplemented here with a voltage source for producing a breakdown (sintering) in the contact region of the detector;

[0041] Fig.10 A top view showing the arrangement of two contact fingers inside a magnetic core for generating an induced voltage and the arrangement of two contact fingers outside the magnetic core;

[0042] Fig.11 Shown in side view Fig.10 Arrangement;

[0043] Fig.12 Shows about Fig.10 and 11 Equivalent circuit diagram of the arrangement;

[0044] Fig.13 Shows Fig.10 and 11 An exemplary variation curve of the real part and the imaginary part of the input impedance of the system as a function of the transfer resistance in the contact region;

[0045] Fig.14 An alternative arrangement of the magnetic core around the plug pin and between two contact areas is shown;

[0046] Fig.15 The arrangement of a magnetic core relative to a plug pin is shown in a perspective view, wherein the magnetic core is intended to surround the contact region between the plug pin and a contact finger (not shown) of a socket;

[0047] Fig.16 The socket is shown while Fig.15 A longitudinal section view of the arrangement;

[0048] Fig.17 Shown along Fig.16 The section of line A;

[0049] Fig.18 Shown along Fig.16 The section of line B;

[0050] Fig.19 A current path is schematically shown, which comprises a plug pin, a socket and a probe pressed on the socket side for measuring the conductive and / or capacitive conductivity of the current path;

[0051] Fig. 20 A current path is schematically shown, which includes a plug pin, a socket, a detector on the socket side, and a detection line for the plug state which is mechanically coupled to the detector;

[0052] Fig.21 Shows Fig.11 A modification of the arrangement of the measuring coils surrounding the current path. DETAILED DESCRIPTION

[0053] Figure 1 For the sake of simplicity, only the sockets BU are shown in the three-dimensional view of the coupling as the first plug device SV1. In the embodiment shown, each of the five sockets BU is formed by a cylindrical base, from which four parallel contact fingers KF are led and surround a cylindrical cavity. In addition, the figure shows a plug as the second plug device SV2, which has plug pins ST complementary to the sockets. When the plug SV2 is plugged together with the coupler SV1, the plug pins ST make conductive contact with the sockets BU in the contact area.

[0054] Due to aging processes, corrosion, contamination, etc., higher transfer resistances may occur in the contact region, which lead to an unacceptably high occurrence of heat loss. It is therefore desirable to determine and monitor the electrical transfer properties in the contact region, in particular the transfer resistance in the contact region between the plug pin ST and the associated socket BU.

[0055] The components necessary for such a determination should hereby be arranged as far as possible only in one of the two plug devices SV1, SV2, so that the monitoring is not dependent on the type and origin of the complementary plug device used. In most of the embodiments described below, the necessary components are arranged in the coupling as the first plug device SV1, while the plug as the second plug device SV2 can in principle be any desired one. However, the corresponding explanations (with corresponding adjustments) also apply to the interchangeable effects of the coupling and the plug.

[0056] Figure 2 A schematic partial cross section of a first contact element in the form of a socket BU is shown, into which a plug pin ST is inserted as a complementary second contact element. The socket BU can be a sleeve closed all around or can be composed of a plurality of contact fingers extending in parallel from a base. The contact fingers can be separated at their free distal ends (see Figure 1 ) are electrically connected to each other. Between the plug pin ST and the socket BU or its contact fingers there is (at least) a contact region through which the operating current flows during operation. The transfer characteristics of this contact region, in particular the transfer resistance present there, should be determined according to the invention by means of the components arranged in the coupler.

[0057] The above-described construction corresponds to the situation in conventional plug devices and is also described in the following appendix. Figure 3 , 4 , 5 and 19 and 20 form the basis.

[0058] In accordance with Figure 2 In the embodiment of the present invention, it is provided on this basis that an electrically conductive detector F is arranged on the bottom of the socket BU, the tip of which contacts the plug pin ST when the plug pin is fully inserted into the socket. The contact is made with a small contact normal force, and the insertion force and the pulling force remain almost unaffected. The detector F can be realized, for example, with a spring wire made of zinc white copper or bronze (both materials have very good spring properties, good or even very good corrosion resistance and do not necessarily require coating). In addition, the detector is guided outwards to the connection b while being electrically isolated from the socket BU.

[0059] The second connection a is formed to the material of the socket BU. Thus, a current path is formed between the connections a and b, and the current path includes the following components:

[0060] - Socket BU;

[0061] - a plug pin ST which contacts the socket in the contact area concerned;

[0062] A sensor F which makes contact with the plug pin ST in a separate second contact region.

[0063] Suitably designed evaluation circuits (not shown) can be connected to the connections a, b in order to determine the properties of the current path and in particular the properties of the contact region of interest.

[0064] exist Figure 3 , an embodiment is shown in which the transfer characteristic is measured on the plug side. For this purpose, two connections a, b are provided, of which one connection b is connected to the plug pin ST and the other connection a is connected, when separated from the previous connection, to a probe F which, in the inserted state, contacts the socket BU from the outside.

[0065] The illustration in the drawing (bottom right) shows an alternative embodiment in which the plug pin ST' has a recess or groove extending in the axial direction. A probe F' is arranged in this groove, isolated from the plug pin ST', which can contact the socket BU from the inside.

[0066] Figure 4 Shows a Figure 2, but in which a second detector F2 is provided as an addition to the first detector F1, which second detector contacts the plug pin ST in a separate third contact area and is guided to the connection c while being electrically separated from the socket and the first detector F1. A suitable evaluation circuit can use all three connections a, b and c in this case.

[0067] Figure 5 Shows a Figure 2 An alternative design is provided in which the sensor F is not located on the bottom of the socket BU but is in contact with the plug pins ST outside the socket.

[0068] Figure 6 Shown for Figure 2 The current path between the terminals a and b extends via the base and contact fingers of the socket, from there via the transfer resistor R Ü Extends into the plug pin, from which it passes through another transfer resistor R F In the second contact region between the plug pin and the probe, the resistor extends into the probe and finally ends in the terminal b. Within the solid material of the socket or the plug pin, the resistance is proportional to the transfer resistance R in the contact region. Ü , R F Can usually be ignored.

[0069] Figure 7 Again, it shows Figure 6 Equivalent circuit diagram of a current path, wherein a measuring device is additionally connected between terminals a and b. As depicted in the drawing, this is an ohmmeter, which measures the resistance in the current path, which is essentially additively composed of two transfer resistors R connected in series. Ü and R F However, since these two resistors are unknown in advance, for the total (R Ü +R F ) does not allow to infer the transfer resistance R Ü .

[0070] Figure 4 The arrangement provides a remedy for this situation, in Figure 4 In the arrangement of , there are two detectors F1 and F2 and thus three (unknown) transfer resistors R Ü , R F1 and R F2 However, by the total resistance between a and b R1 = (R Ü +R F1 ), the total resistance between a and c is R2 = (RÜ +R F2 ) and the total resistance between b and c R3 = (R F1 +R F2 ) and can then be used as R Ü = (R1+R2-R3) / 2 to determine the transfer resistance of interest R Ü This presupposes that the three transfer resistors R1 , R2 and R3 can be measured with sufficient accuracy.

[0071] Figure 8 Another measuring principle is shown, which uses a single detector (see Figure 2 , 3 , 5) can be used and the measuring principle is implemented in the operating state of the plug device. In this regard, the working current circuit is outlined in the right part of the figure, which includes an AC voltage source Q, a transfer resistor R Ü and load R X The working current I flowing in this circuit B The transfer resistor R Ü The voltage drop U B The voltage drop can be measured with a voltmeter at connections a, b.

[0072] The unknown transfer resistance R between the detector and the plug pin F There is no interference in such a voltage measurement if it is sufficiently small compared to the internal resistance of the voltmeter. Ü The voltage drop U generated in the working current circuit at B The current flows through connector a, the voltmeter, connector b, and the transfer resistor R F The measuring current is small due to the high internal resistance of the voltmeter. In addition, relative to the transfer resistance R F The high internal resistance of the voltmeter causes substantially the total voltage to be dropped at the voltmeter.

[0073] Fig. 9 Shows Figure 8 An extension of the circuit of , with which the aforementioned condition can be achieved: the transfer resistance R at the detector is greater than the internal resistance of the voltmeter F To this end, a sufficiently high breakdown voltage U is connected to the D Loading onto connectors a and b. In detail, there can be the following exemplary process.

[0074] First, the switch S is closed for a duration of approximately 1 second (“phase 1”). The voltage U of approximately 50 V DThe result is that the isolating oxide, outer layer, etc., which is also present on the aged contact, breaks through or is sintered, so that then the current flows through the contact and through the lead resistor R of approximately 500Ω. V A current of approximately 100 mA flows (=50 V / 500 Ω). After breakdown / sintering, the voltage at the transition between the probe and the plug pin is at most in the order of magnitude of the melting voltage of the material of the contact surface. For example, for nickel, the melting temperature is 1453° C. and the associated melting voltage is 0.65 V. The transfer resistance R thus provided by sintering is F,fritt (detector - plug pin) is thus in the order of magnitude of 1 V / 100 mA=10 Ω.

[0075] For control purposes, a voltage measurement can be performed when the switch S is closed. In addition, phase 1 is only used to establish the transfer resistance R between the detector and the plug pin. F,fritt , which is at least an order of magnitude lower than the high internal resistance used to make voltage measurements.

[0076] At the beginning of the subsequent "phase 2", the switch S is opened. The voltage measurement now provides the desired voltage drop U between the plug pin and the socket during operation of the plug device. B .

[0077] If the operating current I is known from elsewhere B , then the evaluation circuit can be B and current I B Calculate the transfer resistance R Ü However, even without knowing the operating current, the voltage drop represents valuable information: for a plug-in device, for example, a voltage drop of up to 25 mV (plug pin - socket) can still be considered stable operation, but permanent operation may be problematic from approximately 50 mV at the latest (for a 125 A plug-in device, this corresponds to a transfer resistance (plug pin - socket) of 0.4 mΩ; other limit values ​​for the voltage are possible).

[0078] Since the decisive feature is the measurement of the voltage drop in phase 2 , phase 1 may be completely dispensed with if the detector is designed accordingly robustly.

[0079] Phase 2 can again be followed by phase 1. However, a rest phase (“phase 3”) can also be inserted between these two phases.

[0080] For an arrangement with two detectors, an alternative sequence of measurements (see Figure 4 ) could look like the following arrangement:

[0081] Phase 1: A short current flows through a and b to "prepare" the transfer between the first detector F1 and the plug pin ST;

[0082] Phase 2: A current is briefly fed in via the connections a (socket BU) and c (second detector F2), which current is in the order of magnitude of the subsequent operating current (flowing through the socket BU and plug pin ST). The voltage drop between a and b (first detector F1) is measured;

[0083] Phase 3: If phase 2 indicates "normal", the operating voltage / current is switched on, for example, via a contactor. Otherwise, an alarm signal is issued.

[0084] The method can thus be used to check the properties of the plug pin-sleeve transfer before the operating current is switched on.

[0085] The advantage of the described method is that it can function independently of the type of plug pin-socket contact ("X contact" according to WO 2016 / 184673 A1, torsion spring, etc.). In addition, the method can be carried out during continuous operation and the operating current does not distort the measured values.

[0086] exist Figure 10-18 Another method is shown in FIG. 1 , in which the voltage induced in the current path is used. Such a method can be used in particular in Figure 1 , in which two (or more) contact fingers KF are parallel to one another on a common base without contacting one another at the distal ends.

[0087] Fig.10 A schematic top view of a socket BU with four individual contact fingers KF1, KF2, KF3 and KF4 is shown, which extend within the range of a circular ring segment of approximately 90°. Exemplary dimensions (diameter, gap spacing) are indicated in mm. Two of these contact fingers KF1 and KF3 are wound around a soft magnetic core MK (e.g., made of nanocrystalline or amorphous material, ferrite or similar magnetic material), wherein the encircling closed magnetic core MK itself is wound around a multilayer primary coil PSP, e.g., made of varnished copper wire, on a section outside the socket. The primary coil PSP is connected to an evaluation circuit AS, through which a suitable current and / or voltage curve can be applied.

[0088] According to the transformer principle, the current fluctuation in the primary coil PSP generates a changing magnetic field, which is focused and transmitted by the magnetic core MK. Fig.11As can be seen in the side view of the magnetic core MK, the contact fingers KF1 and KF3 surrounded by the magnetic core MK and the external contact fingers KF2 and KF4 form a closed current path around the magnetic core MK due to the inserted plug pins ST, which can also be understood as a secondary coil with turns. Therefore, the alternating magnetic field in the magnetic core MK causes an induced voltage U in the interior of this current path. ind This causes a corresponding induced current (see the contact fingers KF1 and KF3 in Fig.10 ) and the tails of the arrows in the contact fingers KF2 and KF4). These induction currents must flow through the contact region between the contact finger and the plug pin ST and thus represent the desired sensor for the transfer characteristic or transfer resistance in the contact region.

[0089] The construction described is based on Fig.12 The equivalent circuit diagram of the "secondary coil" is ultimately two parallel circuits of two contact fingers connected in series, wherein the material resistance is neglected for simplicity. The total resistance in this induction circuit of the "secondary coil" is denoted by

[0090]

[0091] As

[0092] to calculate.

[0093] and Fig.12 In contrast to the circuit of the plug device, in the remaining operation of the plug device there is a parallel circuit of the contact fingers. The total resistance is then

[0094] ;

[0095] If all four transfer resistors are the same size, that is,

[0096] ,

[0097] Then it applies and , that is to say .

[0098] If the four transfer resistors have different values ​​(in practice they are statistically distributed), then the measured value R ges,ind May exceed R ges,B , but is therefore on the "safe side".

[0099] In a modified embodiment, the evaluation circuit AS on the primary winding PSP can be designed in such a way that it is used to determine not only the complex input impedance Z and thus R ges,ind, and in addition use I B13 To measure the operating current I B The following share, which flows through Fig.10 The contact fingers KF1 and KF3 in the magnetic core MK are enclosed by the magnetic core MK (refer to the transformer / converter principle). If the evaluation circuit also knows the current I flowing through the other contact fingers KF2 and KF4 B24 Or the working current I B itself (e.g. by measurement), then the following relationship can be used:

[0100] ,

[0101] The last two relations have been used above. If we solve this system of equations for R ges,B , then this will cause

[0102] ,

[0103] With the aid of this formula, the evaluation circuit AS can not only provide information about R ges,B information and can provide R ges,B itself.

[0104] In order to know R ges,ind ,Depend on Fig.10 , 11 The evaluation circuit AS measures the (complex) input impedance Z of the primary coil PSP, which depends in particular on R ges,ind .

[0105] Fig.13 In this context, the results of a simulation with typical parameters for the components used are shown. The complex input impedance Z is shown here as a function of the transfer resistance R Ü The real part Re (Z (R Ü )) and the imaginary part Im(Z(R Ü )) (under the above assumption that all transfer resistors are of the same size). The graph shows that the input impedance Z of the measurement circuit is Ü The evaluation circuit AS connected to the measuring circuit can thus be known from the input impedance of the sought transfer resistance.

[0106] In the simulation, it is assumed that the core MK is arranged in such a way that a magnetic flux density of 1 Tesla is achieved when excited with 127 A. In the case of stronger excitation, saturation of the magnetic circuit can be gradually expected. This saturation can occur, for example, if a current significantly higher than the rated current flows within a few seconds during heavy load startup, of which approximately half is distributed to the two contact fingers surrounded by the core. The downstream electronics will therefore measure distorted Z values ​​in the range of the peak value of the operating current, but detect meaningful values ​​in the vicinity of the zero crossing of the operating current. Therefore, the evaluation circuit AS can optionally be designed in such a way that it performs measurements synchronously with the operating current (50 Hz), in particular only in the vicinity of the zero crossing of the operating current.

[0107] The described method with induction of the measuring current can also be carried out optionally using a detector. Figure 2 The detector F can take over the role of the contact fingers outside (or inside) the magnetic core. In addition, a separate plug pin can also replace multiple contact fingers.

[0108] The principle underlying the above-described concept is that the contact point between the socket and the plug pin can be checked by induction with the aid of a magnetic core, if a closed path (curve, line) guided through an electrically conductive material can only be formed with the simultaneous involvement of contact elements of the first plug device and the second plug device, wherein the path passes through the surface spanned by the magnetic core.

[0109] In addition to what has already been shown, these conditions can also be achieved in alternative cases (Note: For the sake of simplicity, the turns of the primary winding, which are wound around the magnetic core as in a transformer, are Figures 14 to 18 not shown).

[0110] therefore, Fig.14 The arrangement of a magnetic core MK extending around the plug pin ST inside the socket BU is shown, wherein contact areas between the plug pin ST and the socket BU are located on both sides next to the magnetic core MK in the axial direction. A current path of the desired type then extends from the plug pin ST via a first contact area in the contact area (plug pin / socket) into the socket BU (or its contact fingers) and from there back into the plug pin ST via a second contact area in the contact area (plug pin / socket).

[0111] Another solution is in the attached Figures 15 to 18 In this case, only the contact area between the plug pin ST and the socket BU effectively extends through the surface of the magnetic core MK.

[0112] If you can Fig.15As can be seen in the three-dimensional view of FIG. 8 , the shape of the magnetic core MK, which is rectangular in the top view, abuts against the plug pin ST in a semi-cylindrical manner.

[0113] exist Fig.16 In the axial cross-sectional view, the three-dimensional shape of the magnetic core MK appears to be a rectangle. Fig.16 FIG. 4 shows the socket BU, which has two parallel contact fingers KF1 and KF2. In the region of the outer sleeve spring HF, which surrounds 360°, the contact fingers KF1, KF2 make contact with the plug pin ST in the first or second contact region, respectively. The first contact region (in the region between the first contact finger KF1 and the plug pin ST) of the two contacts is connected to the plug pin ST. Fig.18 In the cross section along line “B” on the left) is surrounded by the magnetic core MK.

[0114] The desired induced voltage is generated in the current path, which extends from the plug pin ST via the first contact area KF1 / ST, through the first contact finger KF1, via the bottom of the socket BU and / or the sleeve spring HF to the second contact finger KF2, and from there back via the second contact area KF2 / ST to the plug pin ST.

[0115] The advantage of this embodiment is that it can be used both in sockets with free contact fingers and (as shown) in sockets with contact fingers connected at the distal end.

[0116] In the embodiments described so far, it is not discussed further whether the current path under consideration conducts continuously electrically or (only) capacitively. All embodiments function in any case with an electrically conductive conductivity through which a permanent direct current can be conducted.

[0117] However, it is also possible that the current path under consideration conducts only capacitively at at least one point, that is, contains a capacitor in the series connection. Such a current path cannot conduct permanent direct current, but only alternating current. However, otherwise the described exemplary embodiment functions unchanged.

[0118] The use of current paths that can only be conducted capacitively is Fig.19 Shown in. Fig.19 The current path is schematically shown, which includes the plug pin ST, the socket BU and the detector F on the socket side. Figure 2In contrast to the arrangement of the present invention, an electrically insulating pressure washer DK is provided inside the socket BU, which presses the detector F against the plug pin ST. In this way, a sufficiently close contact between the detector F and the plug pin ST should be ensured. Even if an oxide layer or similar phenomena would prevent the electrical conduction of the conductor from the detector F to the plug pin ST, a sufficiently high capacitance would be formed between the detector F and the plug pin ST, which capacitance allows a usable high (alternating) current in the current path. Measures such as the described sintering of the contacts are therefore not necessary.

[0119] The equivalent circuit diagram of such an arrangement is Fig.19 In the figure, C F is the capacitance and R F is the ohmic resistance between the detector F and the plug pin ST. Iso φ represents the isolation resistance between the probe F and the socket BU and is typically in the order of magnitude of at least 5 MΩ.

[0120] In such an embodiment, it is possible to determine, in a separate measurement, for example, by measuring without an operating current and / or without plug pin ST inserted, only the situation at the transition region between the probe F and the plug pin ST, that is, C F and R F These learned results can then be fed into the subsequent implementation and / or evaluation of the actual measurement in order to improve its reliability.

[0121] Another expansion of the present invention is Fig. 20 This approach involves independent detection of the state in which, in particular, the plug pin ST is inserted into the socket BU. This makes it possible to distinguish between "no plug pin is inserted" and "infinitely high transfer resistance".

[0122] The detection of the plug state is preferably performed mechanically so as to be independent of the conduction state. Fig. 20 As outlined in , the detector F can be mechanically coupled to a switch of the detection line DS, for example. The detector F is moved by contact with the inserted plug pin ST and this movement is mechanically converted into the opening (or closing) of the switch of the detection line DS. The switch state can then be queried from the outside.

[0123] Fig.21 Shows Fig.11 A modification of the arrangement of , in which only the differences are described below and otherwise reference is made to the above description.

[0124] In the modified arrangement, an alternating magnetic field is induced in the magnetic core MK again via the primary coil PSP by connecting an alternating voltage source U P Connected to the primary coil PSP (this alternating voltage source is Fig.11 , which is not shown in detail).

[0125] However, in this arrangement, the (reaction) of the current induced by the alternating magnetic field of the magnetic core in the current path of interest is no longer detected by the primary coil PSP. In other words, a further coil is arranged around the current path, which is connected to the evaluation circuit AS as a measuring coil MS. In the measuring coil MS, a measurable electrical variable (e.g. voltage) is induced directly by the current in the current path it surrounds.

[0126] In this case, as depicted in the figures, the entire current path can be extended through the measuring coil MS when the measuring coil MS surrounds all contact fingers of a current direction (here KF2 and KF4 or KF1 and KF3). However, as an alternative, only a portion of the current path can also be detected, for example when the measuring coil MS extends only around a single contact finger.

[0127] Finally, the most important aspects of the invention which can be implemented individually or in combination are listed again, wherein the reference numerals provided in brackets refer to the exemplary embodiments of the drawings:

[0128] A) A method for determining an electrical transfer characteristic (RÜ) in a contact region between a first contact element (BU) of a first plug device (SV1) and a second contact element (ST) complementary thereto of a second plug device (SV2), wherein the characteristic of a current path is evaluated, the current path comprising the first contact element (BU), the contact region and only the following components in the second contact device (SV2): the second contact element (ST) and any further contact elements in the second contact device (SV2),

[0129] in

[0130] a) an induced voltage (Uind) is generated in the current path, so that a measurement can be performed in the current path, which measurement allows inferences to be drawn about the transfer characteristic of interest; and / or

[0131] b) the current path comprises at least one detector (F, F1, F2), which is arranged in the first plug device (SV1) and, in the plugged-in state, is in contact with the second contact element (ST); and / or

[0132] c) the current path comprises at least two detectors (F, F1, F2), which are arranged in the first plug device (SV1) and are in contact with the second contact element (ST) in the plugged-in state; and / or

[0133] d) the current path comprises at least one detector (F, F1, F2), which is arranged in the first plug device (SV1) and, in the plugged-in state, is in contact with the second contact element (ST), and a breakdown voltage (UD) is applied between the detector (F, F1, F2) and the second contact element (ST); and / or

[0134] e) synchronizing the evaluation with the course of the operating current (IB) within the contact region; and / or

[0135] f) the current path comprises at least one detector (F, F1, F2), which is arranged in the first plug device (SV1) and, in the plugged-in state, is in contact with the second contact element (ST), and wherein a capacitance greater than approximately 10 pF is formed in the current path, which capacitance allows an alternating current in the current path; and / or

[0136] g) The operating current (I B ) occurs when the voltage drop (U B ); and / or

[0137] h) the current path forms the secondary coil on a magnetic core (MK), and a primary coil (PSP) is also arranged on the magnetic core;

[0138] B) a plug device (SV1) having at least one first contact element (BU), which, in the plugged-in state, contacts in a contact region with a complementary second contact element (ST) of a second plug device (SV2), wherein the plug device (SV1) has a current path which includes the first contact element (BU), the contact region and only the following components in the second contact device (SV2): the complementary second contact element (ST) and any further contact elements in the second contact device (SV2),

[0139] in

[0140] a) The plug device comprises a device for generating an induced voltage (U) for the method according to point A) ind ) devices; and / or

[0141] b) the plug device comprises at least one sensor (F, F1, F2) which, in the plugged-in state, comes into contact with a complementary second contact element (ST) of the second plug device (SV2); and / or

[0142] c) the plug device comprises at least two probes (F, F1, F2) which, in the plugged-in state, come into contact with complementary second contact elements (ST) of the second plug device (SV2); and / or

[0143] d) the plug device comprises at least one detector (F, F1, F2) which, in the plugged-in state, contacts a complementary second contact element (ST) of the second plug device (SV2) and comprises means for generating a breakdown voltage (UD); and / or

[0144] e) the plug device comprises a magnetic core (MK) which surrounds the first contact element (BU) and / or the probe (F) and / or the contact area; and / or

[0145] f) The plug device comprises an evaluation circuit (AS) for evaluating a property of the current path according to the method described according to point A).

Claims

1. Used to determine the electrical transfer characteristics in the contact area ( ), the contact region being between a first contact element (BU) of a first plug device (SV1) and a second contact element (ST) complementary thereto of a second plug device (SV2), in, evaluating a property of a current path which includes the first contact element (BU), the contact region and only the second contact element (ST) in the second plug device (SV2), It is characterized in that an induced voltage (U ind ), so that measurements can be performed in the current path, which measurements can lead to inferences about the transfer properties of interest.

2. Used to determine the electrical transfer characteristics in the contact area ( ), the contact region being between a first contact element (BU) of a first plug device (SV1) and a second contact element (ST) complementary thereto of a second plug device (SV2), in, evaluating a property of a current path which includes the first contact element (BU), the contact region and only the second contact element (ST) in the second plug device (SV2), Characterized in that the current path includes at least two touchers (F, F1, F2), which are arranged in the first plug device (SV1) and are in contact with the second contact element (ST) in the plugged-in state, and three or more current paths are evaluated, the current paths including at least three different combinations of contact areas formed between (a) the second contact element and (b) the first contact element and / or different touchers (F, F1, F2).

3. The method according to claim 1, wherein the contact region is between a first contact element (BU) of a first plug device (SV1) and a second contact element (ST) complementary thereto of a second plug device (SV2), in, evaluating a property of a current path which includes the first contact element (BU), the contact region and only the second contact element (ST) in the second plug device (SV2), It is characterized in that the evaluation and the working current (I B ) are synchronized in their movement through the contact area.

4. The method according to claim 1, wherein the contact region is between a first contact element (BU) of a first plug device (SV1) and a second contact element (ST) complementary thereto of a second plug device (SV2), in, evaluating a property of a current path which includes the first contact element (BU), the contact region and only the second contact element (ST) in the second plug device (SV2), The current path comprises a toucher (F), which is arranged in the first plug device (SV1) and contacts the second contact element (ST) in the plugged-in state, and is characterized in that a capacitance greater than 10 pF is constructed in the current path, which allows an alternating current in the current path.

5. The method according to claim 2 or 4, It is characterized in that The operating current (I B ) occurs when the voltage drop (U B ).

6. The method according to claim 2 or 4, It is characterized in that In determining the electrotransfer characteristics ( ) before the defined transfer characteristic is established between the touch device (F, F1, F2) and the second contact element (ST).

7. The method according to claim 1 or 2, It is characterized in that The current path forms a secondary coil on a magnetic core (MK) which is arranged in the first plug device and on which a primary coil (PSP) is also arranged.

8. The method according to claim 1 or 3, It is characterized in that The second contact element (ST) comprises a contact foot, and the first contact element (BU) comprises at least two contact fingers (KF1, KF2, KF3, KF4), both of which are in contact with the same contact foot.

9. The method according to claim 6, It is characterized in that A breakdown voltage (U D ) loading to establish the defined transfer characteristics.

10. A plug device (SV1) having at least one first contact element (BU), which, in the plugged-in state, contacts in a contact region with a complementary second contact element (ST) of a second plug device (SV2), in, The plug device (SV1) has a current path which includes the first contact element (BU), the contact region and a second contact element (ST) which is exclusively complementary to the second plug device (SV2). Characterized in that the plug device comprises a device for generating an induced voltage (U ind ) of a device, wherein - the device comprises a magnetic core (MK) which surrounds the first contact element (BU) and / or the contact region, - the current path forms a secondary coil on the magnetic core, and Furthermore, a primary coil is arranged on the magnetic core.

11. The plug device according to claim 10, It is characterized in that The plug device comprises at least two contacts (F, F1, F2) which, in the plugged-in state, come into contact with complementary second contact elements (ST) of the second plug device (SV2).

12. The plug device according to claim 11, It is characterized in that The plug device comprises a magnetic core (MK) which surrounds a first contact element (BU) and / or a contactor (F) and / or a contact region.

13. The plug device according to claim 10 or 11, It is characterized in that The plug device comprises an evaluation circuit (AS) for evaluating a property of a current path according to a method according to any one of claims 1 to 9 .

Images