Method for actuating electromechanical switching element

Abstract

The invention relates to a method for actuating an electromechanical switching element having at least a plurality of contacts, a coil with an iron core, and an armature, in which, in the event that a given condition is satisfied, the switching-on and switching-off pulses of the switching element are carried out a plurality of times during the switching-off process at a given point in time within the overtravel region, or the switching-on pulse is carried out during the switching-on process. The closing and opening pulses of the switching element are executed a plurality of times such that the coil current flowing into the coil swings between a given maximum value and a minimum value, which is defined as the current value at the time when the armature begins to be detached from the iron core, thereby causing the armature to move within the over-travel region and thus causing the contacts to rub against each other without being detached from each other.

Description

Technical Field

[0001] The invention relates to a method for actuating an electromechanical switching element, and to a generic component. Background Art

[0002] When switching electromechanical switching elements such as relays, two fault conditions may occur. In one case, the relay cannot make contact by the switching-on process, in the other case, the current flow through the contacts cannot be interrupted by the switching-off process. The causes of these fault conditions are various, among which, for example, mechanical jamming of the contacts, oxide layers and welding, etc. can be envisaged. However, many of these causes are reversible, i.e., when the contacts are mechanically jammed, for example, they can still be released again and the relay can continue to be used for thousands of switching cycles. Therefore, a faulty switching state of the relay can be corrected by re-operation.

[0003] In DE 10 2014 211 400 A1, the contactor is opened and closed at least once, for example, when the contacts of the contactor are in contact with a contact resistance not lower than a defined value.

[0004] In EP3185269B1, the operating current is superimposed on the electrical waveform. This method can only be used for the disconnection process.

[0005] Known measures include, for example, repeating the switching process and applying vibrations to the contacts. The measurement techniques required for detecting the contact state are also known, for example, from DE 10 2018 114 425 A1 or WO 202 194 418 A1.

[0006] However, the known methods still need to be improved in order to prevent the failure of the switching element, or to delay the failure. Summary of the invention

[0007] The object of the present invention is therefore to provide a method for actuating an electromechanical switching element, by which the adhesion of the contact element can be avoided or it can be detached again. According to the invention, this object is achieved by the features of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.

[0008] Proposed is a method for controlling an electromechanical switching element, which has at least a plurality of contacts, a coil with an iron core, and an armature, wherein, under given conditions, at a given moment in an overtravel region, multiple opening and closing pulses of the switching element are performed during a disconnection process, or multiple closing and opening pulses of the switching element are performed during a connection process, so that the coil current flowing into the coil swings between a given maximum value and a minimum value, so that the armature moves in the overtravel region, thereby causing the contacts to rub against each other without the contacts detaching from each other, wherein the minimum value is defined as the current value at the moment when the armature begins to detach from the iron core.

[0009] In a further embodiment, it is provided that the given condition is the recognition of a fault state in which the contacts do not make contact when switched on or do not separate when switched off, or wherein the given condition is the detection of a deterioration in the contact quality of the contacts.

[0010] In a further embodiment, it is provided that the switch-on period or the switch-off period is selected to be long enough until the coil current reaches the value which it had at a given time after switching off or switching on.

[0011] In a further embodiment, it is provided that the overtravel range is continuously determined for each electromechanical switching element during use and that the specified time of the opening or closing pulse is adjusted within the overtravel range if the overtravel range changes during the service life.

[0012] In a further embodiment, provision is made for a continuous monitoring to be carried out to determine whether a given condition is met.

[0013] In another embodiment, a universal component is provided, which comprises: an electromechanical switching element having a plurality of contacts and an armature, wherein the armature is configured to move the contacts in such a way that the contacts come into contact with or out of contact with each other; an integrated measuring technology for determining at least one overtravel region during operation of the electromechanical switching element; and a microcontroller connected to the electromechanical switching element signal, in which the method is implemented as a software program.

[0014] In a further embodiment, it is provided that the universal component is designed as a relay socket.

[0015] Further features and advantages of the invention are apparent from the following description of exemplary embodiments of the invention, with reference to the accompanying drawings which show details according to the invention, and from the claims. In variants of the invention, the individual features can be realized individually or in any combination. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The preferred embodiments of the present invention are described in detail below with the aid of the accompanying drawings.

[0017] Figure 1-Figure 3 The figures show an electromechanical switching element according to the prior art in different switching states.

[0018] Figure 4 A diagram depicting a normal breaking process and contact rubbing according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0019] In the following description of the figures, identical elements or functions are provided with the same reference symbols.

[0020] The proposed method is applied in a product having an electromechanical switching element 10, which has a plurality of contacts 7a, 7b, 7c and an armature 5. In particular, the proposed electromechanical switching element 10 of the present invention is equipped in a universal component such as a universal socket, which is used, for example, in industrial automation (DC industrial power grid), or also in charging piles for electric vehicles, etc. The electromechanical switching element 10 used here cannot usually be configured directly after production, or based on one or more reference components, because different influencing factors play a role depending on the usage scenario, i.e. the type of switching element, control voltage, installation position, installation location, etc., which may cause the switching characteristics of the switching element to be changed.

[0021] Therefore, according to the invention, the electromechanical switching element 10 is controlled directly at the installation site to reduce faults. That is, the control method is carried out in the universal component. For this purpose, both measurement technology and a microcontroller are required, and the measurement technology and the microcontroller are equipped in the universal component. The universal component can be implemented as a relay socket.

[0022] The following only concerns the relay 10 as the electromechanical switching element 10. However, the method can also be used for other electromechanical switching elements, such as contactors. However, in addition to the embodiment shown here, in which the changeover contact is a component of the electromechanical switching element 10, such a changeover contact can also be integrated in other devices, such as a changeover switch.

[0023] exist Figure 1, a schematic diagram of a three-pole changeover contact according to a general embodiment is shown. At present, the changeover contact is only exemplarily a part of an electromechanical switching element 10 or a changeover relay. The electromechanical switching element 10 includes three interfaces assigned to the changeover contacts, and these interfaces are referred to as COM interface ("common") 2a, NC interface (normally closed) 2b and NO interface (normally open) 2c according to convention below. In addition, the electromechanical switching element 10 includes two relay coil interfaces 3a and 3b, through which the relay coil 3 (also referred to as coil 3) of the electromechanical switching element 10 can be supplied with a coil current I3. Through the flow of current, the relay coil 3 establishes a magnetic field, which is guided in the magnetic core 4 and exerts a force on the movable relay armature 5 (also referred to as armature 5), which in turn causes the movement of one or more contacts 7a, 7b, 7c (also referred to as contact elements or contact sheets) assigned to the corresponding interfaces 2a, 2b, 2c through the slider 6.

[0024] exist Figure 1 1 shows a state in which the relay 10 is open, that is, the contacts 7a and 7b abut against each other. Figure 2 The state of the relay being closed is shown in FIG. , that is, the contacts 7a and 7c are in contact with each other. Figure 3 . Here, contact 7a is against contact 7c (relay 10 is closed), and contact 7a is pressed toward contact 7c by slider 6 operated by armature 5, which is shown by the bending of the upper end of contact 7a. When relay 10 is turned on and off, there is a region where contacts 7a and 7c are in contact but armature 5 does not contact coil 3 (more specifically, core 8). That is, the connection between contacts 7a and 7c is already conductive, but the bending state of the contact element is still changing, and this region is hereinafter referred to as the overtravel region.

[0025] exist Figure 4 , the time curve for the opening process of an electromechanical switching element 10, which is designed as a relay, for example, according to the prior art is shown. A standardized measurement variable x / X is given on the ordinate. max Here, region B0 represents a state where the relay 10 is closed, i.e., the armature 5 is attracted to the coil 3, more precisely, the armature is not in contact with the coil 3 but with the yoke or core 8, and in regions B1 and B2, the armature is detached from the yoke or core 8, and the contacts 7a and 7c are in contact with each other (e.g., Figure 2 As shown in FIG. 1 , the conductivity exists (indicated by the dashed line L1). Area B1 indicates the overtravel state (as shown in FIG. 1 ). Figure 3Region B2 shows a state where the relay 10 is open, i.e., the contacts 7a, 7c are separated from each other, so that there is no conductivity between the contacts 7a, 7c (as shown in FIG. Figure 1 As shown in the figure). The solid line represents the coil current I3. It can be seen here that during the circuit breaking process, the coil current I3 decreases until at time t 01 A current minimum is reached (minimum current). This current minimum is defined by the armature 5 being detached from the core 8 of the coil 3 (and can be detected immediately after the detachment). At the moment t when the armature 5 begins to detach 01 , the coil current I3 rises again, which can be determined, for example, by calculation via the derivative (from a negative value to a positive value). 01 , area B0 transitions to area B1 (overtravel). At the moment t when contacts 7a and 7c open 12 At d, it leaves the overtravel region B1 (enters the region B2, in which the contacts 7a and 7c are in the open state). 02 Indicates t 01 and t 12 During the time period between , although the armature 5 is separated from the iron core 8 of the coil 3, the contacts 7a, 7c are still in contact with each other.

[0026] The object of the present invention is to identify a faulty switching state, which prevents the contacts 7a / 7b or 7a / 7c from being separated from each other, or in which the contacts 7a / 7b or 7a / 7c are in contact with each other but not conducting. This is achieved by re-energizing the armature 5 in the overtravel area B1, thereby moving the contacts 7a, 7c and rubbing them against each other, as described below. Here, the disconnection process, i.e. the disconnection process of the contacts 7a, 7c, is particularly considered. However, the proposed method can also be applied during connection. Depending on the installation situation, there are two disconnection faults (NO 2c-COM 2a; COM 2a-NC 2b) in the converter, but there are also connection faults for these contact pairs, so that a total of four faults are corrected in the switching relay: the contacts NO 2c-COM 2a do not disconnect, NO 2c-COM 2a do not conduct, COM 2a-NC 2b do not disconnect, and COM 2a-NC 2b do not conduct. Since the focus below is on the disconnection process, the method will only be described with reference to contacts 7a and 7c. ein , d ein , L2 additionally writes to Figure 4 to illustrate how the method works.

[0027] The excitation, in this embodiment a re-engagement or start pulse (since no complete switch-on process is performed), is in the overtravel region B1, i.e. in the time period d 02 The time t ein Advantageously, the time t is chosen so that ein , so that it is consistent with t 01 and t 12 There is a time interval. ein The selection can be arbitrarily realized by the microcontroller. ein At the beginning, the coil current (hereinafter referred to as I1) rises again (at Figure 4 From t ein ), thereby preventing the contacts 7a, 7c from disengaging. However, these contacts are still energized in the overtravel region and move relative to each other on different trajectories by the spring force, so that the contacts rub against each other or a force is applied to the connection position of the contacts. During the period when the coil current I1 rises again, the contacts 7a, 7c are pressed against each other again. If the coil current I1 reaches a given value, at time t during the disconnection process aus At the current value selected at the place, it is disconnected again, whereby the contacts 7a, 7c are excited again and move on different tracks with each other by the spring force, so that the contacts rub against each other, or force is applied to the connection position of the contacts. This can be repeated many times. Therefore, the contacts 7a, 7c produce friction, but the contacts 7a, 7c will not be separated from each other, that is, they will not go through a complete switching cycle. The switching element 10 is therefore also fully conductive during the contact friction. The coil current I3 (I1) therefore swings between a (given, freely selected) maximum current and a (limited by the disengagement of the armature 5) minimum current, thereby always causing the armature 5 to move in the overtravel area B1.

[0028] Here, in Figure 4 The maximum current (maximum coil current I3) and the minimum current (which is at time t 01 The disconnection time t is selected at any position between aus In this embodiment, the time t is selected at about 2 / 3 of the full coil current I3. aus However, another disconnection time t can also be selected according to the control aus , and thereby select another disconnection coil current I3. For example, the excitation can be carried out in a band of 90% to 40% of the coil current I3.

[0029] From the selected time t aus and the switch-on time t ein The disconnection duration d is obtained from aus . Switch-on duration d einBy the switch-on time t ein With time t aus2 The time period between the two is obtained, at this time t aus2 The coil current I1 reaches the same level as at time t aus The disconnected coil current I3 at the same height. aus and d ein The sum of the (pulse width) signals used for control is obtained, and is given by d aus and d ein The ratio of 1 / 2 results in the duty cycle of the signal. Preferably, a high frequency of 50 Hz or more is achieved, in the present embodiment, a high frequency of 200 Hz.

[0030] Advantageously, the method is terminated as soon as possible when it is detected that the contacts 7a, 7b are in contact (when connected) or when it is detected that the contacts 7a, 7c are separated (when disconnected). Advantageously, the monitoring is performed continuously or at a given time. If the corresponding detection cannot be performed after a given period of time, the relay 10 is disconnected and a fault signal is issued.

[0031] Therefore, as a result of the proposed re-energization, the contacts 7a, 7c rub against each other several times, but at the same time do not open (do not separate from each other), so that a conductive connection remains between the contacts, such as by Figure 4 The term "multiple times" can be understood as multiple repetitions of the opening and closing pulses (during the disconnection process) or multiple repetitions of the closing and opening pulses (during the connection process), preferably until the fault state is no longer obtained, wherein a limit can be set on the duration or frequency of the friction.

[0032] Furthermore, no complete switching cycle is experienced during excitation. Instead, in the overtravel region B1, that is, in the time period d between the disengagement of the armature 5 and the disengagement of the contacts 7a, 7c, 02 Inside, at time t ein A new excitation occurs at , ie before the contacts 7a, 7c disengage from each other.

[0033] The method is event-based and is advantageously carried out when a fault state is detected, i.e. when the contacts 7a, 7c do not disengage or when a conductive connection can no longer be established due to deposits. Through the friction caused by multiple opening and closing pulses (during the disconnection process) or multiple closing and opening pulses (during the connection process), dirt is removed between the contacts or the coating material is worn away.

[0034] However, the method can also be performed under conditions different from the current recognition of a fault state, for example, preventively. The method can be performed based on the recognition of a predictive fault state, i.e., preventively. Here, in the case of, for example, the recognition of a vibration in the coil current I3 at the end of the switching process, it can be inferred that the switching element 10 is in a degraded state (the contact quality of the contacts 7a, 7b, 7c deteriorates). Here, although a fault state has not yet been acquired, in which the contacts 7a, 7c (when the relay 10 is disconnected) are no longer separated from each other, or (when the relay 10 is connected) no conductive connection is formed, the fault state is already predictive and is therefore expected. Then, the method can be performed preventively.

[0035] In a less preferred embodiment, the method can also be carried out preventively after a fixed, predetermined number of switching operations of the relay 10 .

[0036] As already mentioned, the method can be carried out both during a switch-on process and during a switch-off process, since in both processes a fault state can occur, ie the contacts 7 a / 7 c , 7 a / 7 b are not disconnected from one another or are not conducting.

[0037] In order to be able to carry out the method, at the beginning of the use of the electromechanical switching element 10, i.e. after it has been installed in the application, data (coil current I3, time t) are collected during each switching process in order to be able to determine the overtravel region B1. As described above, this can be determined from the time difference between the first sign change of the time derivative of the coil current and the first change in the conductivity of the contacts 7a / 7c, 7a / 7b. By acquiring data as far as possible in each switching process, the overtravel region B1 can be adjusted thereby, which may shift, for example, due to aging of the relay 10 during its service life. Therefore, the method is adaptive.

[0038] In order to acquire data and carry out regulation, a universal component is provided which has not only the required measurement technology, for example for measuring current, but also a microcontroller which can carry out the corresponding calculations and take over the control of the relay 10. The method is implemented as a software program in the microcontroller. The method also serves to control the relay 10, for example, by means of a PWM signal.

[0039] The advantage of this method is that a large number of plant failures caused by a faulty relay 10 can be prevented. In addition, the system has a low response time, so that the plant can continue to operate without interruption. Another advantage of this method is that if reconnection is not carried out, the friction can be ended immediately because there is no vibration behavior. In addition, the technical realization as a self-sufficient universal switching component ensures a minimum application effort for the user. Reference numerals

[0041] 2a COM interface

[0042] 2b NC interface

[0043] 2c NO interface

[0044] 3 Relay coil

[0045] 3a, 3b relay coil interface

[0046] 4 cores

[0047] 5 Relay armature

[0048] 6 Sliders

[0049] 7a-7c Contact elements

[0050] 8 core

[0051] 10 Electromechanical switching elements, such as relays

[0052] Armature position with B0 contact closed

[0053] B1 Overtravel armature position (overtravel area)

[0054] Armature position at which the B2 contact opens

[0055] I3 coil current

[0056] I 1 Coil current during friction

[0057] I3_max, I 1_max maximum coil current

[0058] I3_min minimum coil current

[0059] L1, L2 conductivity

[0060] t time

[0061] t aus Disconnection time

[0062] t aus2 Friction-breaking moment

[0063] t ein Connection time

[0064] t 12 Contact opening moment

[0065] t 01 Armature disengagement moment

[0066] d 02 Time period / overtravel duration

[0067] d aus Disconnection duration

[0068] d ein On time

Claims

1. A method for controlling an electromechanical switching element (10), the electromechanical switching element having at least a plurality of contacts (7a, 7b, 7c), a coil (3) with an iron core (8), and an armature (5), wherein -When the given conditions are met, - At a given time (t ein ), during the disconnection process, the switching element (10) is repeatedly pulsed on and off, or during the connection process, the switching element (10) is repeatedly pulsed off and on, so that the coil current (I3, I1) flowing into the coil (3) swings between a given maximum value (I3_max; I1_max) and a minimum value (I3_min), thereby causing the armature (5) to move within the overtravel area (B1), and thereby causing the contacts (7a, 7b, 7c) to rub against each other without being separated from each other, in, The minimum value (I3_min) is defined as the moment (t 01 ) at the current value.

2. The method according to claim 1, wherein: The given condition is the recognition of a fault state in which the contacts do not make contact when switched on or do not separate when switched off, or wherein the given condition is the detection of a deterioration in the contact quality of the contacts (7a, 7b, 7c).

3. The method according to claim 1 or 2, wherein: On time (d ein ) or the disconnection duration is selected to be long enough until the coil current (I 1) reaches the value which the coil current reaches at a given time (t 1 ) after disconnection or connection. aus ) has a value.

4. A method according to any one of the preceding claims, wherein: For each electromechanical switching element (10), an overtravel region (B1) is continuously determined during use and, if the overtravel region changes during its service life, a given time (t) of an on pulse or a off pulse is adjusted within the overtravel region (B1). ein ).

5. A method according to any one of the preceding claims, wherein: Whether the given conditions are met is continuously monitored.

6. A universal assembly (100), comprising: - an electromechanical switching element (10) having a plurality of contacts (7a, 7b, 7c) and an armature (5), wherein the armature is provided for moving the contacts (7a, 7b, 7c) in such a way that the contacts come into contact with one another or come out of contact with one another, and - an integrated measuring technique for determining at least one overtravel region (B1) during operation of an electromechanical switching element (10), and A microcontroller which is in signal connection with the electromechanical switching element (10), in which microcontroller the method according to one of the preceding claims is implemented as a software program.

7. The universal component (100) according to claim 6, which is designed as a relay socket.

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