Patent Application
20240234060
The invention relates to a contact monitoring means for monitoring an electrical, three-pole changeover contact (e.g. of a relay), in particular for monitoring a switching process of the changeover contact.
Changeover contacts with three ports are generally known in the prior art, wherein the ports are, for the most part, referred to as COM port (“common”), NC port (“normally closed”) and NO port (“normally open”). A changeover contact typically has the task of establishing an electrical contact between a common port, the COM port, and one of the two further ports, the NC or NO port. During normal operation, the changeover contact thus has two operating states, that is to say, the COM port is either connected to the NC port or the COM port is connected to the NO port.
In addition to the two above-mentioned states, which can also occur in the event of a disrupted operation of the changeover contact (e.g. when the COM port and the NC or NO port, respectively, are welded together), further switching states can also occur in the event of an error. As a result of worn contact beads, e.g., there can thus be no connection whatsoever between the three ports. Alternatively, all three ports can also be connected to one another, for example by means of an arc or by means of a welding of the contacts as a result of thermal and/or electrical overload. The NC port can furthermore also be connected only to the NO port, but both in each case not to the COM port, wherein this state typically plays a rather subordinate role due to the setup of a relay. As a whole, a number of (error) states can thus occur in the case of changeover contacts, which is why in practice there is a need for a simple and reliable option for detecting or monitoring respectively, the switching state of a changeover contact.
The principle of evaluating the switching state of a contact by imprinting a test signal thereon, is thereby known from DE 28 06 294 A1. However, the contact therein is only a contact with two switching states.
A method for monitoring a switch position of mechanical switching contacts is further known from EP 1 202 313 A1, wherein the method requires two coupling transformers. Only two switching states can furthermore be differentiated by means of the above-mentioned method.
Similar solutions for the changeover contact monitoring are also known from the documents EP 3 396 692 A1, DE 27 29 480 A1, DE 42 21 916 A1, and DE 10 2018 217 135 A1. It is a disadvantage of all of these approaches, however, that only two switch positions can be differentiated with them. In particular in the case of the approach of the DE 10 2018 217 135 A1, the state that all three ports, i.e. the COM, NC and NO port, are connected to one another (e.g. by means of a welding of the contacts) would thereby be interpreted erroneously as a correct function of the switch, even though an error case can be present.
In an embodiment, the present invention provides a contact monitoring means for monitoring an electrical, three-pole changeover contact, comprising: a signal generator, which is configured to generate a monitoring signal; a coupling means, which is connected downstream from the signal generator; a sensing circuit, which is connected downstream from the coupling means and which is coupled or can be coupled to the changeover contact; wherein the monitoring signal generation of the signal generator and thus the monitoring signal and/or a signal derived from the monitoring signal can be changed as a function of a switching position of the changeover contact by means of the sensing circuit, which is coupled to the signal generator via the coupling means; an evaluation means, which is configured to detect the monitoring signal and/or the signal derived from the monitoring signal and/or a change of the monitoring signal and/or a change of the signal derived from the monitoring signal, in order to thus monitor the changeover contact, wherein the sensing circuit is configured to change the monitoring signal and/or the signal derived from the monitoring signal in a different way for at least three different switch positions of the changeover contact.
The present invention will be described in even greater detail below based on the exemplary figures. The invention is not limited to the exemplary embodiments. Other features and advantages of various embodiments of the present invention will become apparent by reading the following detailed description with reference to the attached drawings which illustrate the following:
In an embodiment, the present invention provides an option, which is as cost-efficient as possible, for monitoring a three-pole changeover switch, by means of which the disadvantages of the current solutions are avoided. In an embodiment, the invention provides a solution, by means of which as many error or switching states, respectively, as possible of a changeover switch can be detected, preferably independently of an external circuit of the changeover contact.
According to a first aspect, the disclosure relates to a contact monitoring means for monitoring an electrical, three-pole changeover contact (e.g. of a relay changeover contact). The changeover contact can thereby comprise three ports, which will be referred to below as COM port, NC port, and NO port.
The contact monitoring means comprises a signal generator, which is configured to generate a monitoring signal. The signal generator can thereby be, for example, an oscillator circuit, e.g. a Colpitts oscillator circuit. The monitoring signal is preferably a high-frequency monitoring signal, i.e. a signal in the high frequency range. For example, the monitoring signal can have a frequency of at least 10 kHz, preferably of at least 100 kHz, or more preferably of at least 1 MHz. The monitoring signal is preferably a voltage signal, but the monitoring signal can additionally or alternatively also be a current signal and/or a power signal.
The contact monitoring means further comprises a, preferably exclusively one, coupling means (e.g. a transformer), which is connected downstream from the signal generator, and a sensing circuit, which is connected downstream from the coupling means. I.e., in other words, the sensing circuit is coupled to the signal generator via the coupling means. The coupling means is thereby preferably an inductive coupling means and/or is configured to galvanically separate the sensing circuit from the signal generator. The sensing circuit, in turn, is coupled to the changeover contact or can be coupled thereto. The sensing circuit is thereby preferably coupled to each port of the changeover contact or can be coupled thereto.
It is provided thereby that the monitoring signal generation of the signal generator and thus the monitoring signal and/or a signal derived from the monitoring signal can be changed as a function of a switching position of the changeover contact by means of the sensing circuit, which is coupled to the signal generator via the coupling means. In other words, the sensing circuit can be configured to change the monitoring signal generation of the signal generator and thus the monitoring signal and/or a signal derived from the monitoring signal as a function of a switching position of the changeover contact via the coupling of said sensing circuit to the signal generator via the coupling means. The sensing circuit can be configured, e.g., only in an exemplary manner, to change the amplitude and/or frequency of the generated monitoring signal and/or of the signal derived from the monitoring signal as a function of the switching position of the changeover contact by influencing the vibration behavior of the signal generator. A signal derived from the monitoring signal is to thereby be understood to be a signal, which is functionally associated with the monitoring signal (e.g. is proportional thereto) and/or can be generated from it or converted, respectively. For example, the monitoring signal can be a voltage signal, and the signal derived from the monitoring signal can be a current signal. The sensing circuit is further configured to change the monitoring signal and/or the signal derived from the monitoring signal in a different way for at least three, preferably four, particularly preferably five, different switch positions of the changeover contact “Changing” can thereby generally also be understood to be an “influencing” or “varying”.
In other words, a change or influencing of the monitoring signal, respectively, which is characteristic for the respective switch position, can take place for each of the switch positions, which then results, e.g., in an amplitude of the monitoring signal, which is different for each of the switch positions.
The contact monitoring means furthermore comprises an evaluation means, which is configured to detect the monitoring signal and/or the signal derived from the monitoring signal and/or a change of the monitoring signal and/or a change of the signal derived from the monitoring signal, in order to thus monitor the changeover contact. For example, the evaluation means can detect the current amplitude of the monitoring signal and/or an amplitude change of the monitoring signal, and, on the basis thereof, determine, e.g., the current actual switching state of the changeover contact, which can then, in turn, be compared, e.g., to a specified target switching state. In the event that the monitoring signal is a pulse-like monitoring signal, the detection of a change of the monitoring signal can be, e.g., a detection of a pulse response. As a whole, a plurality of different switch positions of the changeover contact can thus be detected or monitored, respectively, in an advantageous manner, whereby a reliable diagnosis of the current state of the changeover contact is made possible. An unambiguous detection of the contact state of the changeover contact can thus be realized in particular under the aspect of the functional safety (e.g. according to the standard IEC 61508), and a high degree of diagnostic coverage can be attained accordingly.
According to a first aspect of the invention, the sensing circuit can be configured to change an amplitude, a frequency, a phase position, a decay behavior, a runtime and/or a signal form of the monitoring signal as a function of the switch position of the changeover contact. Additionally or alternatively, the sensing circuit can also be configured to change an amplitude, a frequency, a phase position, a decay behavior, a runtime and/or a signal form of the signal derived from the monitoring signal as a function of the switch position of the changeover contact. For example, the sensing circuit can be configured to increase the amplitude of the monitoring signal, based on a first switch position (initial position), if the changeover contact is transferred into a second switch position, and to lower it compared to the amplitude in the first switch position, if the changeover contact is transferred into a third switch position. The monitoring signal can thereby be a continuous monitoring signal or a pulse-like monitoring signal. The sensing circuit can thereby generally be dimensioned to change the same respective parameter(s) of the monitoring signal and/or of the signal derived from the monitoring signal as a function of the switch position (e.g. always the frequency). Alternatively, the sensing circuit can also be configured (e.g. dimensioned) to at least partially change different respective parameters of the monitoring signal and/or to at least partially change the signal derived from the monitoring signal as a function of the switch position (e.g. the frequency in a first switch position and the amplitude in a second switch position). The changing or influencing, respectively, of the above-mentioned parameters of the monitoring signal and/or of the signal derived from the monitoring signal can thereby take place, e.g., by coupling variables, which influence the vibration behavior of the signal generator (such as, e.g., an impedance) into the signal generator as a function of the switch position.
According to a further aspect of the invention, the changeover contact can comprise a, preferably common, COM port, an NC port and an NO port. The sensing circuit can further be configured to change the monitoring signal and/or the signal derived from the monitoring signal in a different way in each case for at least three, preferably four, particularly preferably all of the following switch positions. In other words, the contact monitoring means as a whole can be configured to provide a different monitoring signal for at least three, preferably four, particularly preferably all of the following switch positions in each case. The corresponding switch positions, which can also be referred to as switching states, are thereby:
The advantage of the fact that different monitoring signals, i.e. which are characteristic for the respective switch position, can be generated by the signal generator in each case for as many of the corresponding switch positions as possible, is that an unambiguous assignment of the individual switching states can take place in this way, whereby a diagnosis, which is as accurate as possible, of the changeover contact is made possible in an advantageous manner.
According to a further aspect of the invention, the sensing circuit can comprise one or several impedances.
The sensing circuit can further be configured to provide, with the changeover contact, a total impedance, which varies with the switch positions of the changeover contact, at the coupling means. In other words, the sensing circuit can be configured to change the total impedance applied at the coupling means as a function of the switch positions of the changeover contact. This changed total impedance can then result in the signal generator or in the oscillator circuit, respectively, in a change of the monitoring signal generated there. For example, an increase of the total impedance can effect a decrease of the amplitude of the monitoring signal.
Additionally or alternatively, the sensing circuit can also be configured to provide a respective different total impedance at the coupling means for at least three, preferably four, particularly preferably five switch positions of the changeover contact. For example, a first total impedance can be provided for a first switch position, a second total impedance can be provided for a second switch position, etc. In other words, the sensing circuit can be configured to set, with the changeover contact, a respective characteristic total impedance at the coupling means for at least three, preferably four, particularly preferably five switch positions, which total impedance is then coupled via the coupling means into the signal generator in order to change the monitoring signal generated there. A simple option for the variation of the vibration signal can thus be provided as a whole in an advantageous manner as a function of the switch position, which then provides for a reliable monitoring of the changeover contact.
According to a further aspect of the invention, the sensing circuit can comprise a first impedance, which can be coupled or is coupled to a port of the changeover contact, preferably the COM port. The first impedance is thereby preferably formed in the form of a series connection of a resistor and a capacitor, wherein, to make differentiation easier, the resistor or the capacitor, respectively, will be identified below as “first” resistor and “first” capacitor.
Additionally or alternatively, the sensing circuit can also comprise a second impedance, which can be coupled or is coupled to a further port of the changeover contact, preferably the NC port. This second impedance is thereby preferably also configured in the form of a series connection of a “second” resistor and a “second” capacitor. Additionally or alternatively, the sensing circuit can also comprise a third impedance, which can be coupled or is coupled to a further port of the changeover contact, preferably the NO port. Said third impedance is preferably also configured in the form of a series connection of a “third” resistor and a “third” capacitor. A corresponding interconnection of impedances can thus be provided in an advantageous manner, which makes it possible to vary the total impedance applied at the coupling means and thus the monitoring signal generation as a function of the switch positions of the changeover contact, whereby a monitoring or determination, respectively, of the changeover contact state is made possible in a simple way.
According to a further aspect of the invention, the sensing circuit can comprise one to three further impedances, which, for the purpose of better differentiation, will be identified below as fourth, fifth, and sixth impedance. The respective impedance can thereby in each case be connected downstream from a port of the changeover contact. For example, the fourth impedance can be connected downstream from the COM port, the fifth impedance can be connected downstream from the NC port and/or the sixth impedance can be connected downstream from the NO port. The corresponding impedances, which can comprise, e.g., an inductor or a ferrite, can thereby serve the purpose of attenuating high-frequency signals, which are applied by means of the coupling means at the changeover contact and/or at an electrical load and/or voltage source coupled to the changeover contact. In other words, the fourth, fifth and/or sixth impedance can act as filter elements, whereby other options for filtering, which are known to the person of skill in the art, can also be used instead of impedances. The impedances or the filter elements, respectively, are thereby preferably highly resistive in a frequency range from 100 kHz to 100 MHz, so that the monitoring signal is not applied or only with reduced signal amplitude, respectively, at the loads, which are optionally connected to the changeover contact. A reliable monitoring of the changeover contact can thus be attained in an advantageous manner, which quasi does not represent a negative impact for corresponding useful signals. In other words, the contact monitoring means for typical DC or low-frequency useful signals is not or hardly noticeable, respectively, “viewed from the outside”.
According to a further aspect of the invention, the sensing circuit can comprise at least one further impedance, wherein the at least one further impedance is in each case connected between two ports of the changeover contact. The sensing circuit thereby preferably comprises one, two, or three further impedances, which, for the purpose of better differentiation, will be identified below as seventh, eighth, and ninth impedance. The seventh impedance can be connected, for example, between the COM port and the NO port, the eighth impedance can be connected between the COM port and the NC port and/or the ninth impedance can be connected between the NO port and the NC port. The seventh impedance is thereby preferably configured in the form of a series connection of an inductor and a capacitor, whereby, for the purpose of better differentiation, these will be identified below as seventh inductor and seventh capacitor. The eighth impedance can likewise also preferably be configured in the form of a series connection of an eighth inductor and an eighth capacitor. Lastly, the ninth impedance can preferably also be configured in the form of a series connection of a ninth inductor and a ninth capacitor. The corresponding impedances can thereby serve the purpose of attenuating high-frequency signals between the ports of the changeover contact. The above-mentioned LC series resonant circuits thereby preferably comprise a series resonance frequency, which lies in the range of the frequency of the monitoring signal. In the case of the series resonance frequency, the impedance of the series resonant circuit is thus given only due to resistive portions of the inductor and of the capacitor and is thus very low. It can be attained thereby in an advantageous manner that, on the one hand, voltage signals between the ports and thus electromagnetic interference emissions are reduced and, on the other hand, the influence of the sensing circuit is minimized due to optionally connected loads at the operating frequency of the signal generator because they are connected in parallel to the low seventh or eighth impedance, respectively.
According to a further aspect of the invention, the changeover contact can be a changeover contact of a relay. In this context, the changeover contact can also be identified as relay changeover contact. The relay can thereby be, e.g., an electromechanical relay, in the case of which the changeover contact can be switched by means of a relay coil and a movable relay armature. Alternatively, however, the relay can also be a semiconductor relay. Additionally or alternatively, the contact monitoring means can also be part of a relay socket. In other words, the contact monitoring means can be integrated in a relay socket. The contact monitoring means is thereby preferably encased by a relay socket housing.
According to a further aspect of the invention, the coupling means can be an inductive transmitter. The coupling means can, for example, comprise a transformer, which can comprise a first inductor (e.g. a first air coil) and a second inductor (e.g. a second air coil), wherein the first inductor can be inductively coupled to the second inductor (e.g. via a ferrite or magnetic core). The advantage of a corresponding embodiment with air coils is thereby that the coils can be capable of being produced by means of printed circuit board technique and a number of discrete electronic components can accordingly be reduced during a production of the contact monitoring device. Additionally or alternatively, the coupling means can be configured to galvanically separate the signal generator and the sensing circuit. Alternatively, however, the coupling means can also be formed as a direct galvanic connection of the sensing circuit to the signal generator (e.g. in the form of a cable or conductor connection, respectively). Additionally or alternatively, the coupling means can also be configured of at least two electromagnetically coupled antennas. Additionally or alternatively, the coupling means can also be configured of at least two capacitors. The two capacitors are thereby preferably embodied as printed circuit board capacitors.
According to a further aspect of the invention, the signal generator can be a high-frequency generator, which is configured to generate a high-frequency monitoring signal. For example, the monitoring signal can comprise a frequency of at least 10 kHz, preferably of at least 100 kHz, or more preferably of at least 1 MHz. The advantage that a frequency separation of the monitoring signal and of the useful signal switched by the changeover contact can be realized by means of cost-efficient frequency filter elements, can in particular be attained thereby. Additionally or alternatively, the signal generator can also comprise a Colpitts oscillator circuit. Additionally or alternatively, the signal generator can be connected to the changeover contact via the coupling means and the sensing circuit, for example in parallel.
According to a further aspect of the invention, the signal generator can comprise a tap (e.g. a voltage tap). The signal generator can further be configured to provide the monitoring signal and/or a signal derived from the monitoring signal, via the tap of the evaluation means. In other words, the evaluation means can be connected to the signal generator via the tap. A simple connection of the evaluation means to the signal generator can thus be realized in a simple way.
According to a further aspect of the invention, the monitoring signal can comprise at least a first monitoring subsignal and a second monitoring subsignal. For example, the first monitoring subsignal can comprise a frequency, which differs from the second monitoring subsignal and/or a different signal form and/or can be generated at a different point in time. In other words, the first monitoring subsignal and the second monitoring subsignal can be different or distinguishable, respectively, whereby more than two different or distinguishable monitoring subsignals, respectively (e.g. three monitoring subsignals) can generally also be used. In this context, the signal composed of all monitoring subsignals or consisting of these components, respectively, is to be understood as “monitoring signal”. It can thereby furthermore be provided that the first monitoring subsignal and/or a signal derived from the first monitoring subsignal can be changed by means of the sensing circuit as a function of a switching position of a first port subset of the changeover contact, and the second monitoring subsignal and/or a signal derived from the second monitoring subsignal can be changed as a function of a switching position of a second port subset of the changeover contact. The first port subset is thereby preferably at least partially different from the second port subset. For example, the first monitoring subsignal and/or the signal derived from the first monitoring subsignal can be capable of being changed as a function of the switching state of the COM and NO port, while the second monitoring subsignal and/or the signal derived from the second monitoring subsignal can be capable of being changed as a function of the switching state of the COM and NC port. I.e., in other words, the respective monitoring subsignals and/or the signals derived from the monitoring subsignals can in each case only be assigned to a portion of the ports of the changeover contact or can react only to a change of a portion of the ports of the changeover contact, respectively.
According to a further aspect of the invention, the signal generator can comprise a first signal generator means for generating the first monitoring subsignal and a second signal generator means for generating the second monitoring subsignal. The first signal generator means can be, for example, a first high-frequency generator, which is configured to generate a high-frequency first monitoring signal, and the second signal generator means can be a second high-frequency generator, which is configured to generate a high-frequency second monitoring signal. Additionally or alternatively, the coupling means can also comprise a first coupling element (e.g. a first transformer) for coupling the first signal generator means to the sensing circuit, and a second coupling element (e.g. a second transformer) for coupling the second signal generator means to the sensing circuit. The first coupling element can be, for example, a first transformer and the second coupling element can be a second transformer, wherein other above-described types of the coupling (e.g. capacitive or in the form of a conductor connection) can generally also be used. Additionally or alternatively, the sensing circuit can also be configured to couple the first monitoring subsignal to a first port subset of the changeover contact, and to couple the second monitoring subsignal to a second port subset. In other words, the sensing circuit can be configured to couple the corresponding monitoring subsignals only to certain ports of the changeover contact in each case.
According to a further aspect of the invention, the evaluation means can be configured to output a state signal, which indicates the switch positions of the changeover contact, as a function of the monitoring signal and/or the change of the monitoring signal. Additionally or alternatively, the evaluation means can also be configured to output a state signal, which indicates the switch positions of the changeover contact, as a function of a signal derived from the monitoring signal and/or the change of the signal derived from the monitoring signal. The evaluation means can be configured, for example, to provide a state signal, which is proportional to the current amplitude, frequency, phase position and/or signal form of the monitoring signal and/or of the signal derived from the monitoring signal. The state signal thereby preferably comprises at least three, preferably four, particularly preferably five, different signal states. I.e., in other words, the state signal can characterize the actual switching state of the changeover contact. The evaluation means can further be configured to then compare the above-mentioned state signal with a target switching state signal, which is derived, e.g., from a switching signal generated by the control of the changeover contact, in order to thus monitor a proper switching process or the state of the changeover contact, respectively.
According to a further aspect of the invention, the evaluation means can be configured to detect a switching signal (e.g. generated by a control of the changeover contact) for switching the changeover contact. For this purpose, the evaluation means can be connected to the corresponding control, e.g. via a switching control port. The evaluation means can further be configured to output a control signal as a function of the switching signal as well as of the monitoring signal and/or the change of the monitoring signal, which control signal indicates whether the changeover contact is switched according to the switching signal. Additionally or alternatively, the evaluation means can also be configured to output a control signal as a function of the switching signal as well as of a signal, which is dependent on the monitoring signal, and/or the change of the signal, which is dependent on the monitoring signal, which control signal indicates whether the changeover contact is switched according to the switching signal. Only in an exemplary manner, the control signal can be a binary signal with a first signal value and a second signal value, whereby the first signal value indicates a correct switching process and the second signal value indicates a faulty switching process.
According to a further aspect of the invention, the evaluation means can further be configured to detect the monitoring signal and/or the change of the monitoring signal within a predetermined time interval, with the receipt of the switching signal, in order to determine whether the changeover contact is switched according to the switching signal within the predetermined time interval. Additionally or alternatively, the evaluation means can also be configured to detect the signal derived from the monitoring signal and/or the change of the monitoring signal and/or the change of the signal derived from the monitoring signal within a predetermined time interval, with the receipt of the switching signal, in order to determine whether the changeover contact is switched according to the switching signal within the predetermined time interval. The predetermined, i.e. previously defined, time interval can be, e.g., 50 ms. As a whole, a needs-based monitoring of the changeover contact can thus be realized in an advantageous manner. In one embodiment, the contact monitoring device can thereby comprise an optical display element, which is configured to display the detection of the switching signal and a corresponding detected switching of the changeover contact or a deviation from the expected switching signal, respectively.
According to a further aspect of the invention, the contact monitoring means can comprise a control for controlling the switching state of the changeover contact. In other words, the switching state of the changeover contact can be specified via the control. For this purpose, the control can be configured to output a corresponding switching signal to the changeover contact (e.g. for the energization of a relay coil assigned to the changeover contact). The control is preferably additionally also connected to the evaluation means in terms of signaling, in order to provide the switching signal and/or a target switching state signal derived therefrom to said evaluation means.
According to a further aspect of the invention, the contact monitoring means and the changeover contact can be encased by a common housing. In other words, the contact monitoring means and the changeover contact can form a structural unit. The housing thereby preferably comprises a plurality of ports, which can be configured, e.g., in the form of socket plugs. The housing can comprise, for example, a supply port 11d for the energy supply of the contact monitoring means, two control ports for controlling the switching state of the changeover contact, three load ports for connection to a load to be switched and/or an output port for outputting a state and/or control signal. As a whole, a structurally compact integration solution for monitoring a changeover contact can thus be provided in an advantageous manner. Alternatively, however, the contact monitoring means can also be a device, which is separate from the changeover contact. The contact monitoring means can, for example, be part of a module socket, into which a corresponding switching module can be plugged with a changeover contact. In this case, the contact monitoring means or the module socket, respectively, can further comprise three contact ports, which can be configured, e.g. as socket plugs and which are configured for receiving corresponding contacts on the changeover contact or switching module, respectively. The contact monitoring means or the module socket, respectively, can furthermore comprise one or several switching signal outputs for providing a switching signal for the changeover contact, wherein switching signal outputs, in turn, can be configured for receiving corresponding switching contacts on the changeover contact or switching module, respectively.
Identical or functionally equivalent elements are described with the same reference numerals in all figures and are partly not described separately.
the COM contact pellet 7a is connected, for example, to the NO contact pellet 7, if current flows through the coil 3. When the current flow through the coil 3 is interrupted, the contact pellets 7a, 7b, 7c will be moved into their original position again, e.g. due to a corresponding resilient tensioning of the COM contact element 7a, i.e. the COM contact pellet 7a is contacted with the NC contact pellet 7b in the present case. In addition to the embodiment illustrated here, in the case of which a changeover contact 2 is part of an electromechanical relay 10, the generic changeover contact 2, however, can also be integrated in another device, such as, e.g. a changeover switch.
The contact monitoring means 100 furthermore comprises a coupling means 120, which is connected downstream from the oscillator circuit or the signal generator 110, respectively. In the present case, the coupling means 120 is, for example, an inductive transmitter in the form of a transformer, which is configured to inductively couple the signal generator 110 to a sensing circuit 130, which will be described below in detail. For this purpose, the transformer has a first inductor 121 (e.g. a first planar coil) and a second inductor 122 (e.g. a second planar coil), wherein the first inductor 121 is inductively coupled to the second inductor 122, e.g. via a (non-illustrated) magnetic core. As mentioned above, the first inductor 121 in the present embodiment thereby fulfills a double function, in that it represents an element of the resonant circuit of the oscillator, on the one hand, and forms the connection of the coupling means 120 to the signal generator 110, on the other hand. For a formally unambiguous assignment of the corresponding components, the first inductor 121, however, can be assigned to the signal generator 110, and the second inductor 122 or the magnetic core, respectively, to the coupling means 120. A galvanic separation between the signal generator 110 and the sensing circuit 130 preferably takes place by means of the coupling means 120.
The contact monitoring means 100 further comprises a sensing circuit 130, which is connected downstream from the coupling means 120 and which is connected to the changeover contact 2. The vibration behavior of the signal generator 110 and thus the monitoring signal SM and/or a signal derived from the monitoring signal (e.g. a current signal, if the monitoring signal is a voltage signal), can be changed as a function of a switching position of the changeover contact 2 by means of the above-mentioned sensing circuit 130, which is coupled to the signal generator 110 via the coupling means 120. The sensing circuit 130 is thereby in particular configured to change the monitoring signal SM generated by the signal generator 110 and/or the signal derived from the monitoring signal for at least three, preferably four, different switch positions of the changeover contact 2 in a different way, which will be described in more detail in connection with
The sensing circuit 130 can additionally also comprise further, but generally optional, impedances, in particular if the contact monitoring means 100 is part of a relay socket only in an exemplary manner as in the present embodiment, in the case of which the COM, NC, and NO port 2a, 2b, 2c is electrically connected to corresponding load ports 9a, 9b, 9c for connection to corresponding loads (here, e.g., load 12 or load 13, respectively). The COM port 2a, e.g., can thus be electrically connected to the load port 9a via a fourth impedance 134. The NC port 2b can be electrically connected to the load port 9b via a fifth impedance, and the NO port 2c can be electrically connected to the load port 9c via a sixth impedance. Depending on the dimensioning, individual ones of these optional impedances can also be omitted again, in turn, i.e. can be zero or direct electrical connections can be realized, respectively, e.g. via conductor tracks. In the present case, the fourth, fifth, and sixth impedance 134, 135, 136 are embodied in an exemplary manner in the form of ferrites, which are preferably of low impedance for low-frequency AC voltage signals and of high impedance for high-frequency AC voltage signals. The advantage of these further impedances, i.e. of the fourth, fifth, and sixth impedance 134, 135, 136 is thereby that attenuation can take place due to these high-frequency signals at the load ports 9a, 9b, 9c due to the coupling to the signal generator 110. It can thus be attained in an advantageous manner to functionally separate the contact monitoring means 100 from an external circuit at the load ports 9a, 9b, 9c, while low-frequency signals with high currents can simultaneously be efficiently conducted on ports 2a, 2b, 2c. In other words, the ports 9a, 9b, and 9c, viewed from the outside, are quasi identical to the respective ports 2a, 2b, and 2c due to the low impedances 134, 135, 136 for a useful signal, so that a relay socket with a contact monitoring means 100 according to the shown embodiment does not or hardly differ, respectively, from a common standard relay socket.
Additionally or alternatively, the optional impedances 137 and 138, which will be identified below as seventh impedance 137 and eighth impedance 138, can also be provided in the sensing or impedance circuit 130, respectively. These impedances 137 and 138 can serve different purposes, e.g., for the fault-free operation and independence of an external circuit. They can consist, only in an exemplary manner, of series resonant circuits with a seventh or eighth inductor 137a, 138a, respectively, and a seventh or eighth capacitor 137b, 138b, respectively, wherein the series resonance circuit preferably in each case comprises a series resonance frequency at an operating frequency of the signal generator 110. At the series resonance frequency, the impedance of the series resonance circuits is thus given only by means of resistive portions of the inductance and of the capacitance and are thus very low. On the one hand, a fed-in high-frequency voltage signal between the ports 9a and 9b or 9a and 9c, respectively, can be reduced thereby in an advantageous manner, and emitted electromagnetic interferences at the terminals can thus be minimized. On the other hand, the influencing of the sensing circuit 130 by means of possible connected loads can be minimized at the operating frequency of the signal generator 110 because they are connected parallel to the low impedances 137 and 138.
As a whole, all of the impedances, which are present in the sensing or impedance circuit 130, respectively, are dimensioned, if possible, so that they quasi do not represent an impairment for the useful signal. For example the capacitors 132b, 133b, 137b, and 138b of the impedances 132, 133, 137, and 138 can be very small, so that they are of extremely high impedance and are thus hardly or not noticeable, respectively, for the useful signal. In this respect, the sensing circuit 130 or the contact monitoring means 100, respectively, viewed from the outside, for a (DC or AC or low-frequency, respectively) useful signal acts so as not to be noticeable compared to a conventional circuit or simple connection, respectively. In other words, the components of the sensing circuit 130 are preferably dimensioned so that they do not influence the impedance between the ports 9a, 9b, and 9c at the operating frequency of the loads to be switched (typically direct current voltage or 50 Hz or 60 Hz, respectively). It is furthermore important to mention that the components, which are embodied in an exemplary manner in the present case as load ports 9a, 9b, 9c, do not necessarily actually have to be accessible ports. The corresponding components can thus also only be taps for internal signals of a complex product, e.g. of a product with several functional units, so that the ports 9a, 9b, 9c are only present indirectly or as internal signals/potentials, respectively.
Lastly, the contact monitoring means 100 also comprises an evaluation means 140, which is configured to detect the monitoring signal SM and/or the signal derived from the monitoring signal and/or a change of the monitoring signal SM and/or a change of the signal derived from the monitoring signal, in order to thus monitor the changeover contact 2. For this purpose, the evaluation means 140 can be connected, e.g. via a tap 118 to the signal generator 110, wherein the monitoring signal SM generated by the signal generator 110 is applied at the tap 118 a signal derived from the monitoring signal. In the present case, the evaluation means 140 is configured—only in an exemplary manner—in the form of a Greinacher circuit with two capacitors 141 and 142, two diodes 143 and 144, as well as resistor 145, wherein the circuit is configured to provide a rectified state signal SZ, which is proportional to the oscillation amplitude of SM. The state signal SM can thereby characterize the actual switching state of the changeover contact 2 and can subsequently be compared to, e.g., a target switching state signal, which is derived from a switching signal SS, which is generated by the control 8, for the changeover contact 2, in order to thus monitor a proper switching process or the state of the changeover contact 2, respectively.
The monitoring of the actual switching state of the changeover contact 2 takes place in the evaluation means 140, for the purpose of which the monitoring signal SM, which varies as a function of the switch position of the changeover contact 2 and/or signal derived from the monitoring signal is detected. In the present embodiment, the changing or influencing, respectively, of the monitoring signal SM or of the signal derived from the monitoring signal, respectively, takes place by means of the different interconnection of the impedances 131-138 of the sensing circuit 130 as a function of the switch position of the changeover contact 2, so that, depending on the switch position of the changeover contact 2, a, preferably different, total impedance is coupled into the signal generator 110 via the coupling means 120, which total impedance, in turn, results in different amplitudes of the monitoring signal SM. In other words, four signal amplitudes of SM, which can be differentiated, can be generated by means of suitable dimensioning of the impedances for the typically four states of the changeover contact 2, which are to be differentiated, at the frequency of the signal generator 110, which signal amplitudes allow for an unambiguous assignment between signal amplitude and actual switch position—as will be described below in connection with
Above, the focus was mainly on influencing or changing, respectively, the amplitude of the monitoring signal as a function of a varying total impedance for monitoring the changeover contact. It is immediately clear for the person of skill in the art, however, that other parameters of the monitoring signal, e.g. the frequency, phase position, decay behavior, runtime and/or signal form thereof, can also be used for the changeover contact monitoring via a corresponding adaptation of the units of the contact monitoring means. As can already be seen in
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below. Additionally, statements made herein characterizing the invention refer to an embodiment of the invention and not necessarily all embodiments.
The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.
| Number | Date | Country | Kind |
|---|---|---|---|
| BE2021/5383 | May 2021 | BE | national |
This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2022/062552, filed on May 10, 2022, and claims benefit to Belgian Patent Application No. BE 2021/5383, filed on May 12, 2021. The International Application was published in German on Nov. 17, 2022 as WO/2022/238361 under PCT Article 21(2).
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/062552 | 5/10/2022 | WO |
