Method for manufacturing a magnetic yoke

Abstract

Method for producing a magnetic yoke (4) having two magnetic legs (2, 3) of a magnetic release (18) which can preferably be used in a residual current circuit breaker, - in which the two magnetic legs (2; 3) are spaced apart from one another by a non-magnetic separating layer (5) arranged between the two magnetic legs (2; 3) and are arranged parallel to one another in order to be fixed relative to one another by means of at least one thermal joining connection (13), - in which a measurement of the capacitance of a capacitor formed by the magnetic legs (2; 3) with the separating layer (5) arranged therebetween is carried out, - in which, on the basis of the measured capacitance value, the process parameters for producing the at least one thermal joint (13) are determined in such a way that the magnetic resistance of the manufactured magnetic yoke (4) is set to a predefined value, and - in which the thermal joining connection (13) is produced on the basis of the determined process parameters, characterized in that the type of the at least one thermal joining connection (13) and the intensity of the energy input are determined as process parameters.

Description

The invention relates to a method for producing a magnetic yoke having two magnetic legs of a magnetic release which can preferably be used in a residual current circuit breaker.Electromechanical protective switching devices-for example circuit breakers, line circuit breakers or residual current circuit breakers-serve for monitoring and also for safeguarding an electrical circuit and are used in particular as switching and safety elements in electrical energy supply and distribution networks. To monitor and protect the electrical circuit, the circuit breaker is electrically conductively connected via two or more connection terminals to an electrical line of the circuit to be monitored, in order to interrupt the electrical current in the respective monitored line if required. For this purpose, the protective switching device has at least one switching contact which can be opened when a predefined state occurs-for example when a short circuit or a fault current is detected-in order to disconnect the monitored circuit from the electrical line network. Such protective switching devices are also known in the field of low-voltage technology as series-built-in devices.In electrical installation technology, circuit breakers suitable for this purpose, for example fault current circuit breakers or differential current circuit breakers, are used to detect what is known as a differential or fault current, in order to protect persons from risks which may occur when parts of electrical installations under voltage are touched. Differential currents can arise if, for example, a residual current flows through the human body via a defective insulation or-in the case of a contact-to ground.To detect such a fault or differential current, the magnitude of the current in a line leading to an electrical load, for example a phase line, is compared with the magnitude of the current in a line leading back from the electrical load, for example a neutral conductor, with the aid of a so-called sum current converter. This has an annular magnetic core through which the primary conductors (positive and negative-going electrical lines) are passed. The magnetic core itself is wound with a secondary conductor or a secondary winding. In the fault current-free state, the sum of the electrical currents flowing to the load is equal to the sum of the electrical currents flowing back from the load. If the currents are added vectorially, i.e. in a direction-related or signed manner, it follows from this that the signed sum of the electrical currents in the forward and return lines in the fault current-free state is equal to zero: no induction current is induced in the secondary conductor.In contrast to this, in the case of a fault current or differential current flowing away from earth, the sum of the electrical currents flowing back and forth in the sum current converter is not zero. The current difference occurring in this case leads to a voltage proportional to the current difference being induced at the secondary winding, as a result of which a secondary current flows in the secondary winding. This secondary current serves as a fault current signal and, after exceeding a predetermined value, leads to the tripping of the circuit breaker device and, as a result, by opening the at least one switching contact of the circuit breaker device, to the disconnection of the correspondingly secured circuit.In general usage, instead of the term "residual current circuit breaker", the terms FI circuit breaker (FI switch for short), differential current circuit breaker (DI switch for short) or RCD (for residual current protective device) are also used equally.In the case of residual current circuit breakers, a distinction is furthermore made between device types which are dependent on the mains voltage and are independent of the mains voltage: whereas residual current circuit breakers have control electronics with a trip which, in order to fulfil their function, is dependent on an auxiliary voltage or mains voltage, residual current circuit breakers which are independent of the mains voltage do not require an auxiliary voltage or mains voltage in order to achieve the trip function which is independent of the mains voltage, but generally have a somewhat larger sum current converter with which a larger induction current can be generated in the secondary winding. Since the differential currents determined in this way are generally comparatively small, they also have only a low energy density. Therefore, the fault current cannot be used directly and directly, as in the case of a circuit breaker, for example, for triggering a latching mechanism-for example with the aid of a magnetic coil and a striker in the event of a short circuit being triggered. Instead, an electromechanical trip relay, which is also referred to as a magnetic trip, is generally used to implement the fault current trip independent of the mains voltage.The magnetic trip device is electrically conductively connected to the sum current converter via the secondary winding. Because of the usually low differential current, however, the magnetic trip device has only a comparatively low trip force, which requires an additional energy store on the latch lock in order to open the switching contact directly when a fault current occurs. In general, such an electromagnetic triggering device is known from, for example, German patent specification DE 197 35 413 B4.Due to the low forces, a magnetic release suitable for use in a residual current circuit breaker is designed as a fine mechanism assembly and has a magnet system with two fixed magnet legs, which are arranged with respect to one another by an exact spacer. By means of a suitable manufacturing method, the two magnet legs are mechanically connected to one another. The spacer constitutes a non-magnetic separating layer which separates, i.e. keeps the two magnet legs at a distance from one another, forming a magnetic resistance corresponding to the geometry of the parts. In this way, the permanent magnetic flux fed into the magnetic circuit by a permanent magnet or permanent magnet is prevented from being short-circuited. The magnet system fed by the permanent magnet thus serves to guide a constant magnetic flux to a movable armature of the magnetic release. The armature is mounted in such a way that in the idle state it is held in its idle position by the permanent magnet against the force of a release spring. If the permanent magnetic flux of the magnet system is weakened by an oppositely oriented magnetic flux which is generated by a trigger or excitation coil when a fault current occurs, the holding force of the permanent magnet is thereby reduced in such a way that it is no longer sufficient to hold the armature in its idle state against the force of the trigger spring. The armature is lifted from the pole surfaces of the magnet system by the spring force of the prestressed tripping spring and subsequently actuates a coupling member of the magnet trip unit, which acts on a latch mechanism of the residual current circuit breaker, in order in this way to bring about an opening of a switching contact or of a contact system of the residual current circuit breaker.The magnet system must have a high mechanical strength and must be mountable in large numbers by means of an automated production line. For functional safety and economic production of the magnetic release or of the holding magnetic release, it is necessary for the release performance to be in a predefined, relatively narrow range with a small range of variation due to production. In order to achieve this, the magnetic properties of the magnet system-i.e. its magnetic flux-must be very accurately adjustable during the assembly of the individual components. In this case, the magnetic properties of the materials used for the two magnet legs and, if appropriate, the separating layer, but also the distance of the two magnet legs from one another, are decisive in particular.European patent application EP 0 984 477 A2 discloses, for example, a method for producing a yoke of a magnetic trip device, in which the two yoke plates are first held at a predetermined mounting distance from one another, forming an air gap. Subsequently, even before the two yoke laminations are fixed to one another by means of a plurality of connection points, the capacitance of a capacitor formed from the yoke laminations and the air gap lying therebetween is measured. After the measurement, the air gap of the capacitor-and thus the mounting distance of the two yoke plates-is varied as a function of the measured capacitance value in such a way that after the connection points have been provided, the magnet yoke manufactured in this way has the desired magnetic properties, in particular the desired magnetic flux density. However, this method is complicated, since after the capacitance measurement the distance between the two yoke plates has to be varied or corrected in a range of only a few micrometers. The execution of this method therefore makes high demands on the manufacturing technique used and on the quality of the mutually oriented surfaces of the two yoke plates.Furthermore, a method for producing a magnet system according to the preamble of independent claim 1 is known from the publication DE 10 2005 050 636 A1.Furthermore, the publication EP 0 984 477 A2 discloses a method for producing a yoke of a magnetic release, in which two yoke plates are held at a predetermined mounting distance from one another to form an air gap and are fixed to one another after connection points are provided at an average distance from one another which determines the magnetic properties of the release, wherein, before the connection points are provided, the capacitance of a capacitor formed by the yoke plates and the air gap lying therebetween is determined periodically as a function of the yoke plate distance.The invention as set forth in the claims is therefore based on the object of providing an alternative method for producing a magnetic yoke of a magnetic release preferably usable in a residual current circuit breaker as well as an electromechanical circuit breaker device, in particular a residual current circuit breaker, having a magnetic release which has a corresponding magnetic yoke which has been produced according to the method according to the invention, which are characterized by a simplified production suitable for large numbers and by a high production quality.This object is achieved according to the invention by the method for producing a magnetic yoke according to independent claim 1. Advantageous embodiments of the production method according to the invention are the subject of the dependent claims.In the method according to the invention for producing a magnetic yoke of a magnetic release preferably usable in a residual current circuit breaker, which yoke has two magnetic legs, the two magnetic legs are spaced apart from one another by a non-magnetic separating layer arranged between the two magnetic legs and are arranged parallel to one another in order to be fixed relative to one another by means of at least one thermal joining connection. In this case, firstly a measurement of the capacitance of a capacitor formed by the magnet limbs with the separating layer arranged therebetween is carried out. The process parameters for producing the at least one thermal joint connection are then determined on the basis of the measured capacitance value in such a way that the magnetic resistance of the magnet yoke produced is thereby set to a predefined value. The thermal joint connection is then produced on the basis of the determined process parameters, wherein the type of the at least one thermal joint connection and the intensity of the energy input are determined as process parameters.The thermal joining methods include, in particular, soldering and welding. By a suitable selection of the process parameters of the relevant thermal joining process, the magnetic resistance-and thus the magnetic flux-between the magnet legs of the manufactured magnet yoke can be influenced in an advantageous manner. This is effected in particular in that the splitting of the magnetic flux into a main flux which leads via the pole surfaces and the armature and a secondary flux between the magnet legs can be varied by the type and the number of the at least one thermal joint connection. This results in the advantage that manufacturing differences of the magnet legs and / or the separating layer can be compensated by the selection of the suitable process parameters for establishing the thermal joint connection in such a way that the magnetic resistance-and thus the magnetic flux density of the manufactured magnet yoke-can be adjusted to its predefined target value despite existing manufacturing inaccuracies or deviations.In particular, it is possible to dispense with complicated surface processing of the so-called shunt surfaces, i.e. the mutually facing inner surfaces of the magnet legs, in order to achieve a high surface quality with a small roughness depth, as can be achieved, for example, by honing or lapping: the triggering performance of the magnet system depends in particular on the distance of the two magnet legs from one another and the ratio of the inner surface of the magnet leg to the distance volume. It is therefore absolutely necessary to maintain a tolerance to the spacing of the two magnet legs within a certain range of variation. The distance between the two magnet legs typical of a magnetic release is about 40 μm. Accordingly, an absolute distance tolerance of approximately ±4 μm corresponds to a relative distance tolerance of usually ±10%. However, since the flatness tolerance of the magnet legs, which are usually stamped, is significantly higher than the flatness of approximately 4 μm required on one side, the shunt surfaces of the magnet legs must be subjected to a lapping process in a complicated manner in order to achieve the desired flatness requirement. This complicated surface processing can be dispensed with in the production method according to the invention, which is why the magnet yoke can be produced significantly more efficiently and more cost-effectively.The type of the at least one thermal joint is to be understood as meaning not only the respective joining method-for example suitable soldering or welding methods-but also the shape and / or the size of the respective thermal joint. The intensity of the energy input is understood here to mean the energy power introduced into the joint, i.e. the amount of energy introduced per unit of time. Therefore, in addition to the type of joint connection, both the magnitude of the energy and its duration of action are considered as variable process parameters.In an advantageous development of the production method according to the invention, the process parameters for producing the at least one thermal joint connection are determined by calculation and / or by use of a characteristic diagram.The determination of the process parameters for establishing the at least one thermal joint connection, which can be realized, for example, on an outer side or on an end side of the magnet legs, can be based on a suitable calculation of the physical properties of the magnet yoke-for example, material properties or the geometry. Alternatively, it is also possible to first create at least one process characteristic map suitable for this purpose and then derive the process parameters respectively suitable for joining the specific magnet yoke from the characteristic map on this basis.In a further advantageous development of the method, the at least one thermal joint connection is designed as a welded connection, which is produced by a suitable welding method, preferably by means of laser welding.The various welding methods represent a possibility for producing the at least one thermal joining connection. For producing the magnet yoke, the laser welding method is advantageous in this respect in that here, on the one hand, both the power and the duration of action of the laser on the joining partners to be welded can be set very precisely. On the other hand, the laser welding method is particularly suitable for use in automated production plants.In a further advantageous development of the method, the at least one welded connection is designed as a welding point and / or as a weld seam.Instead of one or more welding points, the at least one thermal joint designed as a welded connection can also have one or more welded seams. As a result of this variance of the embodiment, the magnetic flux in a magnet yoke produced in this way can be influenced in a targeted manner-in addition to the possibility of varying the intensity of the energy input-in order to achieve the predefined target value for the magnetic flux density of the magnet yoke in a simple manner.In a further advantageous development of the method, magnet legs with unground shunt surfaces are used for producing the magnet yoke.This results in the advantage that the shunt surfaces, i.e. the mutually facing inner side surfaces of the two magnet legs, do not have to be processed or pretreated in a complicated manner before the creation of the thermal joint connection, since possible deviations of the surface quality, i.e. the roughness of the inner surfaces, can be compensated for after the measurement of the capacitance by a variation of the process parameters of the thermal joint process. In this way, the manufacturing cost of the magnetic yoke can be significantly reduced.In a further advantageous development of the method, the two magnet legs have a predefined distance from one another, which is predefined by the thickness of the separating layer.Since the distance between the two magnet legs is predetermined by the thickness of the separating layer lying therebetween, it no longer has to be corrected during the execution of the method. Since a distance correction would be in the range of only a few micrometers, complex measuring and manufacturing means would be required for this purpose, which can be dispensed with when carrying out the method according to the invention on account of the compensation possibility by means of variance of the process parameters of the thermal joining method. The manufacturing cost of the magnetic yoke is thereby further reduced.In a further advantageous development of the method, the separating layer consists of an electrically non-conductive material. As electrically non-conductive, non-magnetic material for the separating layer, for example, a thin, flat plastic film is suitable.In a further advantageous development of the method, the separating layer is designed as a planar adhesive connection.A further possibility for realizing the separating layer is to form it as an adhesive connection which is applied flat to the mutually facing inner side surfaces of the two magnet legs. This results in the additional advantage that the two magnet legs already adhere to one another, so that the thermal joint connection is less given the function of fixing the two magnet legs, but predominantly the function of influencing the magnetic flux by a corresponding setting of the process parameters of the thermal joint process. The production process is thereby further simplified.In a further advantageous development, the method is carried out as an automated method in an automated manufacturing process with the aid of suitable manufacturing means.The partially or completely automated execution of the method according to the invention allows the incorporation thereof into a predominantly automated production process, which brings with it a clear cost advantage, in particular when producing large numbers.An exemplary embodiment of the method for producing a magnetic yoke and a magnetic release having a magnetic yoke produced in this way will be explained in more detail below with reference to the appended figures. In the figures,FIGS. 1 and 2 show schematic representations of a magnetic yoke of a magnetic release having two magnetic legs in different views; FIG. 3 shows a schematic representation of a magnetic release preferably usable in a residual current circuit breaker; FIG. 4 shows a schematic representation of a magnetic equivalent circuit diagram of the magnetic release.In the various figures of the drawing, identical parts are always provided with the same reference numerals. The description applies to all drawing figures in which the corresponding part can likewise be seen.FIGS. 1 and 2 schematically show a magnet system 1 in various perspective views. The magnet system 1 has a first magnet leg 2 and a second magnet leg 3, which form a magnetic yoke 4 of a magnetic release 18 which can preferably be used in a residual current circuit breaker. A first pole face 2.1 is formed on the first magnet leg 2, and a second pole face 3.1 of the magnet yoke 4 is formed on the second magnet leg 3. The two magnet legs 2 and 3 each consist of soft magnetic material and together with a separating layer 5 arranged therebetween form the magnet yoke 4.The first magnet leg 2 has a shape in which its free end 2.2 according to FIG. 2 is arranged horizontally and is tapered in its height. At right angles to this, a first pole face arm 2.3 is provided, at the end of which the first pole face 2.1 is located. The other end of the first magnet leg 2 then extends. The second magnet leg 3 has, in contrast thereto, at its free end a vertically extending second pole face arm 3.3, at the end of which the second pole face 3.1 is located. The second pole face arm 3.3 is offset from the remaining magnet leg 3 by a U-shaped cutout 6 and serves to receive an excitation coil 7 (see FIG. 3 ) which can be mounted thereon.On an end face 4.1 of the magnet yoke 4, a rectangular permanent magnet 8 is arranged in its longitudinal axis, which is surrounded by structurally separate pole plates 9 and 10 which are situated opposite one another and bear against the two magnet legs 2 and 3 for forwarding the magnetic flux. A bearing element 11 (see FIG. 3 ) can be fastened to the upper end sides 9.1 and 10.1 of the two spaced pole plates 9 and 10, i.e. to the upper end side 9.1 of the first pole plate 9 and to the upper end side 10.1 of the second pole plate 10, in such a way that a planar support is provided for a release anchor 12 which can be arranged thereon. The two magnet legs 2 and 3 are mechanically connected at their respective outer edges to the pole plate 9 or 10 respectively arranged thereon via at least one thermal joint 13.1. At least the one pole plate 9 is additionally mechanically connected to the permanent magnet 8 via a further thermal joint 13.2. Furthermore, a further thermal joint 13.3 is shown, via which the two magnet legs 2 and 3 are mechanically connected to one another. The thermal joining connections 13.1, 13.2 and 13.3 can be formed, for example, as soldered connections or also as welded connections. A combination of the two joining methods (for different joining connections) is also possible.FIGS. 1 and 2 each show the magnet system 1 with the magnet yoke 4 formed by the two magnet legs 2 and 3, the permanent magnet 8 and the two pole plates 9 and 10 in different views. The positions of the thermal joining connections 13.1, 13.2 and 13.3 are indicated by punctiform markings, without this involving any restriction with regard to the type and number of joints or the joining method used. In addition, it is possible to arrange further joints for connecting the two magnet legs 2 and 3, for example on the underside of the magnet system 1.FIG. 3 shows a schematic illustration of a magnetic release 18-also referred to as a release relay-which can preferably be used in a residual current circuit breaker-with the magnetic system 1 already known from FIGS. 1 and 2. the magnetic system 1 has a release armature 12 which is mounted movably relative to the bearing element 11 and which for its part has a retaining element 19 for mounting a spring element 20. The spring element 20 suspended on the holding element 19 in the prestressed state is mounted at its other end on a holding leg 17 of the bearing element 11. The magnet system 1 together with the release armature 12 forms a magnetic circuit which is fed by the permanent magnet 8 in its predefined, magnetically set state.An excitation coil 7 is plugged onto the second pole face arm 3.3 (see FIGS. 1 and 2 ), by means of which excitation coil the magnetic circuit can be influenced: if the excitation coil 7 is energized, the resulting magnetic flux counteracts the magnetic flux generated by the permanent magnet 8, so that the holding force of the magnetic circuit acting on the release armature 12 is weakened in such a way that the lifting force acting on the release armature 12 by the prestressed spring element 20 predominates in relation to the holding force of the magnetic circuit, as a result of which an abrupt pivoting movement of the release armature 12 into an open position is brought about. By this pivoting movement, a triggering element 22, in particular a plunger, guided in a housing 21 of the magnetic release 18 is moved in a triggering direction 23, as a result of which, for example, a triggering lever of a latching mechanism (not shown) of the circuit breaker device, for example of a residual current circuit breaker, is then acted upon. The energy released in this case finally serves to open the electrical contacts of the circuit breaker device. The excitation coil 7 is fed by a residual current, which is detected, for example, with the aid of a sum current converter of the residual current circuit breaker.Due to the magnet system 1, the magnetic trip 18 is capable of forming a magnetic circuit with a predefined magnetic flux characterized by a predefined trip characteristic. This triggering characteristic is influenced by the design and the structure of the magnet system 1, in particular by the permanent magnet 8, the coupling of the magnetic flux via the two pole plates 9 and 10, and the soft magnetic material properties of the magnet legs 2 and 3.FIG. 4 shows a schematic illustration of a magnetic equivalent circuit diagram of the magnetic release device 18, on the basis of which the various influencing variables on the magnetic flux of the magnetic system 1 are illustrated below.The magnetic circuit is fed by the permanent magnet 8, i.e. the permanent magnet 8 acts as a source for a total magnetic flux Φ 0, which flows through the individual components of the magnet system 1. These components represent, on the one hand, installation-dependent and, on the other hand, different resistances for the total magnetic flux φ 0 due to their different magnetic properties. Here, first of all, mention should be made of the magnetic resistance of the first pole plate R M, P1 and the magnetic resistance of the second pole plate R M, P2. R L3 denotes the magnetic resistance of the "air gap 3", R L4 accordingly the magnetic resistance of the "air gap 4". The two last-mentioned variables are to be understood as meaning in each case the air gap between the permanent magnet 8 and the respectively adjoining pole plate 9 or 10, and the further air gap between this pole plate 9 or 10 and the respectively adjoining magnet limb 2 or 3. Since these two air gaps are each connected in series with one another, the individual resistance values are combined to form a common variable. R is M, M1 or. R M, M2 denotes the magnetic resistance of the first magnet leg 2 and of the second magnet leg 3.In the further course, the total magnetic flux φ 0 of the magnet system 1 is divided into a first partial magnetic flux φ 1 and a second partial magnetic flux φ 2The second partial magnetic flux φ 2 flows via the two pole face arms 2.3 and 3.3 and the release armature 12.The first partial magnetic flux φ 1 on the other hand, is guided over the shunt surfaces of the two magnet legs 2 and 3. Here, the magnetic resistances are the magnetic resistance of the "second air gap" R L2, which takes into account the "distance" of the two magnetic legs 2 and 3 due to the unevenness of the two mutually facing shunt surfaces, and the magnetic resistance of the separating layer 8 arranged therebetween. Furthermore, the magnetic resistance of the shunt is opposed to the first partial magnetic flux φ 1 via the at least one thermal joint connection 13, denoted by R SP in the illustration of FIG. 4. Due to the geometric design of the magnetic system 1, the two magnetic resistances R L2 and R SP are to be regarded as a magnetic parallel circuit.In order to achieve the desired, predefined value for the magnetic flux density of the magnet system 1 despite manufacturing deviations, it is absolutely necessary during the production of the magnet yoke 4-i.e. during the joining of the two magnet legs 2 and 3 with the separating layer 8 arranged therebetween-that the magnetic resistance resulting from the parallel connection of the two magnetic resistors R L2 and R SP is kept essentially constant. This can be achieved, for example, by varying the distance between the two magnet legs 2 and 3 before joining in a corresponding manner in order to compensate for manufacturing deviations. However, this is extremely complicated on account of the required accuracy and presupposes highly precise production means for the adjustment of the two magnet limbs 2 and 3 in the micrometer range. According to the invention, the object is therefore achieved in that the magnetic resistance R SP of the shunt can be varied via the at least one thermal joint connection 13 by a suitable variation of the process parameters of the thermal joint process in such a way that the magnetic resistance resulting from the parallel connection of the two magnetic resistances R L2 and R SP can be adjusted to the desired, predefined value.In the following, the method according to the invention for producing a magnetic yoke, having two magnetic legs, of a magnetic release preferably usable in a residual current circuit breaker is explained in more detail with reference to the above-described figures:First, the two magnet legs 2 and 3 are spaced apart from one another and arranged parallel to one another by a non-magnetic separating layer 5 arranged between the two magnet legs 2 and 3, in order to be fixed relative to one another by means of at least one thermal joining connection 13.3. Subsequently, a measurement of the capacitance of a capacitor formed by the magnet legs 2 and 3 with the separating layer 5 arranged therebetween takes place. Based on the measured capacitance value, the process parameters for producing the at least one thermal joint 13.3 are subsequently determined. The process parameters are selected such that the magnetic resistance of the manufactured magnet yoke 4 after carrying out the joining method corresponds to a predefined value. Subsequently, the at least one thermal joint 13.3 is produced on the basis of the determined process parameters.An essential parameter for specifically influencing the triggering performance of the magnet system 1 is thus the connecting technology used, with which the two magnet legs 2 and 3 are mechanically held together. As connecting elements for realizing the thermal joining connection, one or more welding points, for example, are considered, which are arranged on the outer or end sides of the magnet legs. Advantageously, these are laser welds. However, small welded seams can also be realized. Depending on the size of the welding spots or intensity of the welding power (current and time), the magnetic resistance between the magnet legs changes and thus the splitting of the magnetic flux of main flux and secondary flux changes. Thus, by means of the targeted control of the welding parameters, it can be achieved that the triggering power lies in a defined narrow range with a small fluctuation range. In this case, the complicated and expensive machining of the shunt surfaces of the magnet legs 2 and 3 can be dispensed with. The basis for this is a relatively simple capacitive measurement in front, in which a non-conductive separating layer 5 is used as spacer.The invention is thus based on the design of the magnet system 1, wherein preferably ungrounded magnet legs 2 and 3, i.e. magnet legs 2 and 3 each with ungrounded shunt surface, as well as a non-magnetic, non-conductive separating layer 5 arranged between the magnet legs 2 and 3, which advantageously consists of plastic or a plastic-like film. The separating layer 5 has commercially available thickness tolerances, typically in the range of ±10% of the thickness of the separating layer. The two magnet legs 2 and 3 can then be used without additional adjustment of the shunt gap. The relatively cost-effective separating layer 5 serves as a spacer, which is advantageously adapted to the outer contour of the magnet legs.After the two magnet legs 2 and 3 have been fixed with the separating layer 5 arranged therebetween, a receiving device specifically developed for this purpose, capacitance measurement takes place during the ongoing production process with the aim of keeping the magnetic resistance of the uneven, because unground magnet legs 2 and 3, the separating layer 5 and the thermal joint 13.3 as constant as possible in total. The fixing of the two magnet legs 2 and 3 is advantageously carried out in a recording device specifically developed for this purpose, as well as the capacitance measurement in the context of an at least partially automated manufacturing method, for example using round tact tables.Depending on the measured capacitance value, the process parameters for the thermal joining process that are suitable for the respective magnetic yoke are determined by means of software suitable for this purpose. The aim of obtaining magnet systems of almost the same magnetic quality is thus achieved in that the magnetic resistance of the shunt is determined on the basis of the measured capacitance values and the process parameters of the joining process are adapted accordingly. In this case, both the type of joints, the joining power (with respect to the amount of energy introduced and the duration of time), and the number or the position of the joints can be varied. In this way, magnet systems with high mechanical strength can be manufactured in a large number of fully automated ways, wherein the complicated adjustment of the shunt gap using complicated positioning means can be dispensed with.The process parameters of the thermal joining process thus serve as controlled variable of the production method according to the invention for achieving the predefined value of the magnetic resistance of the magnet yoke for connecting the two magnet legs, and not the air gap formed by the distance between the two magnet legs.List of reference characters1 Magnet system 2 First magnet leg 2.1 First pole face 2.2 Free end 2.3 First pole face arm 3 Second magnet leg 3.1 Second pole face 3.3 Second pole face arm 4 Magnet yoke 4.1 End face 5 Separating layer 6 Cutout 7 Excitation coil 8 Permanent magnet 9 First pole plate 9.1 Upper end face 10 Second pole plate 10.1 Upper end face 11 Bearing element 12 Release armature 13 Thermal joint 13.2 Thermal joint 13.3 Thermal joint 17 Holding leg 18 Magnetic release / release relay 19 Holding element 20 Spring element 21 Housing 22 Release element 23 Release direction Φ 0 Total magnetic flux Φ 1 First partial magnetic flux Φ 2 Second partial magnetic flux r L1 magnetic resistance air gap 1 R L2 magnetic resistance air gap 2 R L3 magnetic resistance air gap 3 R L4 magnetic resistance air gap 4 R M, A magnetic resistance of the armature R M, M1 magnetic resistance of the first magnetic leg R M, M2 magnetic resistance of the second magnetic leg R M, P1 magnetic resistance of the first pole plate R M, P2 magnetic resistance of the second pole plate R SP magnetic resistance of the shunt

Claims

Method for producing a magnetic yoke (4) having two magnetic limbs (2, 3) of a magnetic release (18) which can preferably be used in a residual current circuit breaker, - in which the two magnetic limbs (2; 3) are spaced apart from one another by a non-magnetic separating layer (5) arranged between the two magnetic limbs (2; 3) and are arranged parallel to one another in order to be fixed relative to one another by means of at least one thermal joining connection (13), - in which a measurement of the capacitance of a capacitor formed by the magnetic limbs (2; 3) with the separating layer (5) arranged therebetween is carried out, - in which, on the basis of the measured capacitance value, the process parameters for producing the at least one thermal joining connection (13) are determined in such a way that the magnetic resistance of the produced magnetic yoke (4) is thereby set to a predefined value, and - in which the thermal joint connection (13) is produced on the basis of the process parameters determined, characterized in that the type of the at least one thermal joint connection (13) and the intensity of the energy input are determined as process parameters.Method according to Claim 1, wherein the process parameters for producing the at least one thermal joint connection (13) are ascertained by calculation and / or by use of a characteristic diagram.Method according to one of the preceding claims, in which the at least one thermal joint connection (13) is designed as a welded connection which is produced by a suitable welding method - preferably by means of laser welding.Method according to Claim 3, in which the at least one welded connection is designed as a welding point and / or as a weld seam.Method according to one of the preceding claims, in which magnet legs (2; 3) with unground shunt surfaces are used for producing the magnet yoke (4).Method according to one of the preceding claims, in which the two magnet legs (2; 3) have a predefined distance from one another, which is predetermined by the thickness of the separating layer (5).Method according to one of the preceding claims, in which the separating layer (5) consists of an electrically non-conductive material.Method according to one of the preceding claims, in which the separating layer (5) is designed as a planar adhesive connection.Method according to one of the preceding claims, wherein the method is carried out as an automated method in an automated production process by means of suitable production means.

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