Safety element

Abstract

Safety element, in particular for a motor vehicle power line, comprising - a control circuit and - a pyrotechnic fuse (2), wherein - the control circuit comprising a printed circuit board (24) - at least one measuring sensor, - at least one temperature sensor and - at least one processor (26) evaluating the measuring sensor and the temperature sensor, - the pyrotechnic safety device (2) - a first connecting tab (8a), - a second connecting tab (8b), - a separation point (16) arranged between the connecting tabs (8a, b), and - has a pyrotechnic drive acting on the separation point (16), wherein - the drive (12) has ignition contacts (14) on its side facing away from its explosive surface (22), and characterized in that, - the pyrotechnic fuse (2) is attached directly to the circuit board (24) at least in a form-fitting manner, - that the drive (12) is designed in such a way that it can be triggered both intrinsically and extrinsically, in which - in the event of an intrinsic triggering, the processor (26) applies an ignition voltage to the drive (12) via a connection between the processor (26) and the ignition contacts (14) and - the ignition contacts (14) are set up for connection to an external ignition signal and the external ignition signal is applied to the ignition contacts (14) during external triggering.

Description

[0001] The subject matter concerns a safety element, in particular for a motor vehicle power line.

[0002] Electrical circuits, especially in motor vehicles, must always be protected against short circuits. This minimizes damage to property and personal injury. This applies to both electrical and electronic applications, the latter often including printed circuit boards. A wide variety of fuses are available on the market, suitable for almost any application. Common types include fuses, relays, and semiconductor switches, each with its own specific advantages and disadvantages. Fuses are compact and can be integrated onto a circuit board, but they have high power dissipation and manufacturing-related variations in their tripping characteristics. Furthermore, they are slow to react, as the conductor takes time to melt. Fuses may not provide sufficient protection, especially in the case of slow-developing short circuits.External tripping of fuse links, i.e., by an external disconnection pulse, is not possible. This is because fuse links exhibit age-related drift, which affects their tripping characteristic.

[0003] Relays are complex in design and therefore more expensive than fuses. They are also larger and have power losses. The advantage of relays is that they can be switched reversibly and can switch multiple current paths simultaneously.

[0004] Semiconductor-based switches, especially electronic relays or MOSFETs, are more expensive than relays, but they switch faster, have lower power dissipation, are reversible, and are smaller. However, heat dissipation becomes problematic at high currents, which can cause semiconductor-based switches to fail and become unusable. Switching with semiconductor-based switches does not provide galvanic isolation at the junction.

[0005] Publication DE 10 2016 107 706 A1 concerns a control device for a pyrotechnic safety device for a high-voltage power supply of a motor vehicle.

[0006] Publication US 2019 / 0244778A1 concerns a circuit breaker that interrupts the electrical circuit in case of overload or short circuit. This can be achieved by a fuse, which melts when the current increases and must be replaced.

[0007] Publication DE 10 2012 013 491 B3 describes an electrical disconnecting device designed to disconnect an electrical current path between two terminal parts. The device comprises a disconnecting point, a movable disconnecting element, and a drive that accelerates the disconnecting element.

[0008] Publication DE 10 2016 216 829 A1 relates to a disconnecting device for disconnecting an electrical connection between at least two components of a motor vehicle.

[0009] The project was based on the task of providing a safety concept that combines the advantages of different switching concepts.

[0010] This problem is solved by a safety element according to claim 1. The safety element in question enables PCB-mountable, monitorable isolation of a current path by means of a isolating element. The safety element in question comprises a control circuit as well as a pyrotechnic fuse as the isolating element. The control circuit serves to monitor the fuse and to trigger the fuse depending on the monitoring status. The pyrotechnic fuse can provide galvanic isolation and is monitorable and triggerable by the control circuit. Furthermore, the pyrotechnic fuse can be triggered externally, so that the safety element in question can provide galvanic isolation both intrinsically and extrinsically.

[0011] The control circuit comprises a printed circuit board. Active, passive, and / or electronic components are arranged on the circuit board in a known manner. The control circuit includes at least one measuring sensor and one temperature sensor on the circuit board. The measuring sensor serves to detect an electrical quantity, and the temperature sensor serves to detect a temperature. Both the electrical quantity and the temperature can be detected at the pyrotechnic fuse, allowing it to be monitored by the control circuit.

[0012] Both the measuring sensor and the temperature sensor provide measured values ​​that can be evaluated by a processor, which is also located on the circuit board. The processor is specifically a microcontroller, for example an EPROM or EEPROM or similar, which is programmed to monitor and control the pyrotechnic safety device.

[0013] The pyrotechnic fuse has a first and a second connection tab. The connection tabs have significantly larger conductor cross-sections than the conductor tracks on the circuit board. In particular, the connection tabs have conductor cross-sections of more than 2.5 mm². 2 , especially 16mm 2 or more. A current of several tens or even several hundred amps can flow through the connection lugs. The connection lugs are configured on the input side so that they can be connected to an electrical conductor by a material-fit and / or form-fit connection, for example by welding, soldering, crimping, or similar methods. The connection lugs are connected to each other at a break point along the pyrotechnic fuse.

[0014] The fuse is electrically conductive in its unexploded state, and the connecting tabs are directly connected to each other mechanically and / or electrically at the break point. This break point serves to galvanically isolate the connecting tabs from each other in the event of the pyrotechnic fuse being triggered. For this purpose, the pyrotechnic fuse has a pyrotechnic actuator.

[0015] The pyrotechnic drive is characterized by reliable and long-term stable separation behavior. The pyrotechnic drive can be electrically ignited, for example, by an electrical ignition pulse. Such an electrical ignition pulse can be applied to the drive either by the control circuitry or extrinsically.

[0016] For monitoring and controlling the pyrotechnic fuse, it is now proposed that the fuse be attached directly to the circuit board, at least by positive locking, but preferably also by a material bond, in particular by welding or soldering. The control circuit and the fuse form a single structural unit and are interconnected. This direct connection places the control circuit in close proximity to the fuse, enabling it to perform its monitoring function. By arranging the pyrotechnic fuse directly on the circuit board, both the temperature sensor and the measuring sensor can directly access measured values ​​at the fuse. This is particularly relevant for the temperature sensor, as it is designed to monitor the fuse's temperature.

[0017] The temperature sensor allows monitoring of the fuse's temperature, particularly the temperature at the terminals and / or the break point. In the event of a slow short circuit, a continuous current flows through the break point. The break point is typically a reduction in the conductor cross-section and therefore presents an increased resistance. A continuous current through this resistance generates Joule heating, which causes the fuse to heat up. This heating can be detected directly by the temperature sensor. The fuse can then trip if a predefined temperature threshold is exceeded. Thus, this fuse element provides protection against slow short circuits.

[0018] In the event of a brief overcurrent, the measuring sensor can detect an increased voltage drop along the connection lugs, particularly across the ohmic resistance of the break point. Knowing the conductance of the connection lugs and the resistance of the break point, the current flowing through the lugs can be determined from the voltage measured between them. Alternatively, a current sensor can be used to measure the corresponding current. The measuring sensor makes it possible to determine whether an overcurrent is flowing through the break point, and if the measured electrical value exceeds a threshold, the control circuit can also trip the fuse.

[0019] Finally, an external ignition impulse can trigger the pyrotechnic safety device.

[0020] When the pyrotechnic safety device is triggered, the actuator acts on the disconnect point in such a way that it is severed, creating a galvanic isolation between the connecting lugs. The pyrotechnic actuator is ignited, whereupon an ignition pellet explodes. The gas pressure built up by the explosion is directed towards the disconnect point. The actuator is therefore positioned accordingly, pointing towards the disconnect point. The resulting gas pressure is sufficient to permanently destroy the disconnect point and, in particular, to mechanically force the connecting lugs apart, especially by plastically deforming them. Thus, the actuator, triggered by an electrical ignition pulse, creates a galvanic isolation between the connecting lugs.

[0021] According to one embodiment, it is proposed that the measuring sensor measures an electrical parameter across the junction. The measuring sensor is, in particular, a voltage sensor, but can also be a current sensor. In the case of a voltage sensor, the measuring sensor can measure a voltage drop across the junction. Knowing the ohmic resistance between the connection points of the measuring sensor, a current can be determined from the voltage drop. It is proposed that the measuring sensor determine a current flow across the junction from the voltage drop.

[0022] According to one embodiment, it is proposed that the connecting tabs are formed as flat parts. In particular, the connecting tabs are bent sheets or strips made of a metallic material, for example, a copper alloy or an aluminum alloy. The connecting tabs are mechanically and / or electrically connected to each other at the separation point, which has a predetermined breaking point. The predetermined breaking point can be formed, in particular, by a reduction in the material thickness. It is also possible, and particularly preferred, if the separation point is formed by perforating the connecting tabs. Perforation can be introduced, for example, particularly easily into a flat part. In particular, it is possible that the connecting tabs are first formed in one piece, bent in a processing step, and then perforated along the separation point in a further processing step.The perforation can also be performed before bending. By creating the separation point, the flat part is divided into a first and a second connecting tab. The connecting tabs can then be inserted into the locking element and mechanically fastened to it, so that the connecting tabs are mechanically fixed relative to the drive when the drive is triggered. The force exerted on the separation point by the drive separates it.

[0023] To create a firing channel in which the actuator can build up gas pressure, it is specifically proposed that the connecting tabs encircle the actuator in a U-shape. The separation point can be located at the bottom of the U and positioned on the actuator. When the actuator is triggered, the built-up gas pressure can act directly on the separation point. The actuator has a firing direction defined by a longitudinal axis of the firing channel. The connecting tabs are arranged around the actuator such that the firing direction points towards the separation point. This ensures that the gas pressure is applied directly to the separation point when the actuator is triggered.

[0024] To secure the connection tabs to the drive, both the connection tabs and the drive are housed in a single enclosure. The drive, for example, is located in a through-opening of the enclosure. The connection tabs, with their separation point, can be positioned over the through-opening of the enclosure. Both the drive and the connection tabs can be mechanically fixed to the enclosure. A gap can be provided on the side of the separation point facing away from the drive, allowing the connection tabs to be bent away from the drive to create galvanic isolation.

[0025] The drive exerts a force on the separation point. To prevent the connecting tabs from being detached from the housing by this force, it is proposed that the connecting tabs at least partially engage the housing on the side facing away from the separation point. The connecting tabs could be arranged on the housing in the manner of a clamp, with the ends of the connecting tabs spaced apart from each other and resting against a first side of the housing, and the separation point located on the opposite side of the housing.

[0026] The connecting tabs are preferably arranged in recesses in the housing. The recesses protect the connecting tabs from electrical contact. The recesses extend parallel to the weaving direction, and the connecting tabs can be inserted through them.

[0027] According to one embodiment, it is proposed that the housing is attached to the printed circuit board (PCB) by means of fasteners. For this purpose, the PCB has, for example, recesses into which projections of the housing can be inserted. It is also possible that the PCB has projections and the housing has recesses. In particular, the projections and recesses can be formed in a transition or press fit to each other, so that a mechanical locking action between the housing and the PCB can be achieved.

[0028] The housing is securely attached to the circuit board. This attachment is achieved through a frictional and / or positive locking mechanism. Fixing the housing to the circuit board also ensures a defined distance between the housing with its connection tabs and the components mounted on the circuit board, particularly the temperature sensor, thus guaranteeing accurate temperature sensing at all times.

[0029] According to one embodiment, it is proposed that the actuator be oriented with a blast surface in the direction of the separation point. The actuator, as a pyrotechnic device, has a pyrotechnic detonator. This detonator contains an ignition charge that can be activated by a detonating wire. The ignition charge is enclosed within the detonator, which is formed as a housing. The detonator has a defined blast direction. This means that the ignition charge is enclosed within the housing in such a way that, upon activation, the gas pressure escapes from a defined surface of the detonator housing. This surface can be referred to as the blast surface. The detonator is generally at least partially cylindrical. A blast surface is then, in particular, a top or bottom surface of the detonator. The gas pressure escapes from this surface upon activation of the ignition charge.To ensure the separation is safe, the detonator is now aligned with the explosive surface at the separation point so that the escaping gas pressure acts directly on the separation point.

[0030] On the side facing away from the blast surface, the actuator has ignition contacts. These ignition contacts are typically wires extending from the detonator. An ignition pulse, in particular an electrical voltage, can be applied via these contacts. This ignition pulse activates the detonator.

[0031] According to one embodiment, it is proposed that the pyrotechnic fuse is attached to the printed circuit board (PCB) such that the temperature sensor is in contact with the fuse. The pyrotechnic fuse is positioned relative to the PCB such that the area of ​​the PCB on which the temperature sensor is located faces directly towards the fuse. In particular, the fuse is positioned above the PCB components such that the temperature sensor on the PCB faces directly towards the fuse. A contact, especially a direct contact, can be formed. Specifically, the temperature sensor is in contact with at least one of the terminal tabs. The terminal tabs, being electrical conductors, are also good thermal conductors. Thus, the temperature across the connection point can be measured with high accuracy at the terminal tabs.

[0032] If direct contact is not possible, the temperature sensor can be positioned in close proximity, particularly directly facing the fuse, on the circuit board. To enable improved temperature sensing, the temperature sensor can be connected to the terminals via temperature probes. For example, metallic wires can be attached to the terminals and routed towards the temperature sensor. This allows the temperature sensor to directly detect the temperature of the terminals via these probes.

[0033] In one embodiment, it is proposed that the temperature sensor be an NTC resistor. This resistor has a temperature-dependent resistance characteristic. A temperature can be inferred from a change in the ohmic resistance. An NTC resistor can be easily arranged on a printed circuit board as a passive component.

[0034] According to one embodiment, it is proposed that the printed circuit board (PCB) includes at least one comparator. The comparator can, in particular, comprise an operational amplifier and / or a differential amplifier. The comparator is configured to compare at least one measured value from the sensor with a reference value. This reference value can be a value programmed into the processor. Alternatively, contacts can be arranged on the PCB through which a potentiometer can be switched. The reference value can be adjusted via the potentiometer, which can optionally be connected between the contacts. The comparator can be a conventional comparator circuit with an adjustable threshold. Hysteresis can also be set on the comparator.

[0035] A comparator can also compare a temperature sensor reading with a reference value. Here too, the reference value can either be programmed into the processor or set via an external resistor, which can be connected to the circuit board via contacts.

[0036] Depending on the comparison, the comparator can output a comparison value. Specifically, a comparator can be provided for both the measuring sensor and the temperature sensor. Based on this comparison value, the processor can then trigger the actuator or not. Thus, the processor can trigger the actuator based on the comparison value, which is determined by monitoring the measured value of the measuring sensor and / or the measured value of the temperature sensor. The processor can therefore ensure that the safety element is activated not only based on an external ignition signal, but also based on temperature and / or current flow across the disconnect point.

[0037] According to one embodiment, it is proposed that the processor is operatively connected to at least one comparator and controls the drive depending on the comparison value. Both the comparator and the processor can be arranged on the circuit board. The drive can be activated via the control signal.

[0038] According to one embodiment, it is proposed that the actuator is connected to the processor via ignition contacts, the ignition contacts being designed for connection to an external control system. The fuse or actuator is designed such that it can be triggered both intrinsically and extrinsically.

[0039] Intrinsic triggering occurs via the processor, depending in particular on the comparison result, via the functional connection, specifically the connection between the processor and the ignition contacts. The processor can apply a trigger voltage to the ignition contacts, whereupon the drive is triggered.

[0040] In addition, the fuse can be triggered externally, as the ignition contacts are also designed for connection to an external ignition signal. Specifically, the ignition contacts are designed as conventional plug-in contacts. These plug-in contacts can be inserted into a standard pyrotechnic fuse holder and thus be configured to receive an external ignition signal.

[0041] The subject matter is explained in more detail below with reference to a drawing showing an exemplary embodiment. The drawing shows: Fig.1a, b Views of a pyrotechnic fuse according to an exemplary embodiment; Fig. 2 a sectional view of a pyrotechnic fuse according to an exemplary embodiment; Fig. 3a, b a view and a top view of a control circuit; Fig. 4. Assembly of a safety element according to an exemplary embodiment.

[0042] Fig. Figure 1a shows a pyrotechnic fuse 2. The pyrotechnic fuse 2 has a housing 4. The housing 4 is made of an impact-resistant plastic. For this reason, it is also proposed that the plastic has, for example, the following properties, either individually or in any combination: Characteristic Value Unit Test standard Fracture stress 100-400 preferred, 200-300 preferred, especially around 250 MPa ISO 527-1 / -2 Elongation at break 1-3 preferably approx. 2 % ISO 527-1 / -2 Charpy impact strength, +23°C 50 - 100, preferably 70 - 90, especially about 80 kJ / m 2 ISO 179 / 1eU Charpy impact strength, -30°C 50 - 100, preferably 70 - 90, especially about 80 kJ / m 2 ISO 179 / 1eU Charpy impact strength, +23°C 1 - 20, preferably 8 - 13, especially about 11 kJ / m 2 ISO 179 / 1eA Charpy impact strength, -30°C 1 - 20, preferably 8 - 12, especially about 10 kJ / m 2 ISO 179 / 1eA

[0043] During the final manufacturing stage, particularly for the production of the printed circuit board, the housing is placed in a soldering oven together with the circuit board. The housing 4 must also be dimensionally stable during this manufacturing step. For this reason, it is also proposed that the plastic, for example, has the following properties, either individually or in any combination: Characteristic Value Unit Test standard Melting point, 10°C / min 300-400 preferred, 310-350 preferred, especially around 325 °C ISO 11357-1 / -3 Dimensional stability temperature, 240 - 320 °C ISO 75-1 / -2 1.80 MPa preferably 260-300, especially around 285 Dimensional stability temperature: 8.00 MPa 150-300 preferred, 190-230 preferred, especially around 210 °C ISO 75-1 / -2 Coefficient of linear expansion, parallel 10-20, preferably 12-17, especially around 15 E-6 / K ISO 11359-1 / -2 Coefficient of linear expansion, perpendicular 20-60 preferred, 30-40 preferred, especially around 40 E-6 / K ISO 11359-1 / -2 Flammability at thickness h HB class IEC 60695-11-10 tested specimen thickness 0.4 - 1.2 preferred, 0.6 - 1.0, especially approx. 0.8 mm IEC 60695-11-10

[0044] The housing 4 is shaped to include receptacles 6, which are, for example, slot-shaped. Connecting tabs 8a, b can be inserted into the receptacles 6. Furthermore, the housing 4 has a firing channel 10 in which a pyrotechnic drive 12, in particular a primer, is installed. The firing channel 10 extends longitudinally through the housing 4. Ignition contacts 14 are led out of the housing in a sealed manner from the bottom of the firing channel 10 (not shown). The receptacles 6 generally extend parallel to the firing channel 10.

[0045] The connecting tabs 8a, b are made of metallic material, in particular copper or a copper alloy, as well as aluminium or an aluminium alloy.

[0046] The connecting tabs 8a, b run within the housing 4 in the receptacles 6 parallel to the firing channel 10. Immediately at the point where they exit the receptacles 6, the connecting tabs 8a, b are bent towards the firing channel 10, specifically at right angles. The connecting tabs 8a, b are connected to each other above the firing channel 10 at a separation point 16. In the example shown, the separation point 16 has a perforation in the connecting tabs 8a, b. The separation point 16 lies directly above the firing channel 10 and the pyrotechnic drive 12.

[0047] The separation point 16 extends along a first surface of the housing 4.

[0048] On an adjacent side wall of the housing 4, this housing has fastening lugs 18. The fastening lugs 18 extend from the surface of the housing 4 in the surface normal of this surface.

[0049] The mounting pins 18 are used to attach the housing 4 to a printed circuit board. A printed circuit board has corresponding receptacles 6 for this purpose, as will be shown below.

[0050] The mounting pins 18 are connected to the printed circuit board (PCB) such that the surface on which the mounting pins 18 are arranged is the surface of the housing 4 facing the PCB. To enable the closest possible contact between the housing 4 and the PCB, recesses 20 are provided in this surface, which are formed to receive components of the PCB. Components are arranged on the PCB that protrude from its surface. To reduce the distance between the PCB and the housing 4, the recesses 20 are shaped to receive components of the PCB. Thus, the housing 4 can be attached close to, in particular directly to, or with a small gap against the PCB.

[0051] Fig.Figure 1b shows the housing 4 in another view, on the side of the housing 4 facing away from the separation point 16. It can be seen that the connecting tabs 8a, b on the side of the housing 4 facing away from the separation point 16 are bent towards the ignition contacts 14 and thus clamp around the housing 4. This clamping action ensures that the connecting tabs 8a, b are securely attached to the housing 4 and, in particular, remain attached to the housing 4 when the separation point 16 is disconnected.

[0052] Fig.Figure 2 shows a cross-sectional view along the firing channel 10. It can be seen that the pyrotechnic actuator 12 is located in the firing channel 10. The ignition contacts 14 extend from the housing 4. The pyrotechnic actuator 12 is sealed against the ignition contacts 14 in the firing channel 10 by a seal 12a. The pyrotechnic actuator 12 has a rupture surface 22. In the event of ignition, the actuator 12 bursts at the rupture surface 22, so that the gas pressure acts directly on the separation point 16.

[0053] Since the connecting tabs 8a, 8b grip the housing 4 on the side opposite the separation point 16, the separation point 16 can tear open at the perforation and a separation is effected.

[0054] A circuit board 24 is used to monitor fuse 2, according to the Fig.3a is provided. For example, a processor 26 and two operational amplifiers 28 are provided on the circuit board 24. Each of the operational amplifiers 28 receives a measurement signal. These measurement signals can be acquired using passive components 30. The circuit board 24 has receptacles 32 for receiving the mounting pins 18. When the mounting pins 18 are positioned in the receptacles 32, the operational amplifiers 28 engage with the receptacles 20. Thus, the housing 4 is in direct contact with the circuit board 24. A voltage sensor located on the circuit board 24 is connected to the terminals 8a, b via sensing lines (not shown). A voltage can be measured across the junction 16 via these sensing lines, which are, for example, located at terminal contacts 34. The measured voltage is compared to a reference value by the operational amplifier 28, and a comparison result is output.

[0055] On the side of the circuit board 24 facing the housing 4, a temperature sensor, for example in the form of an NTC resistor 36, can be arranged. The NTC resistor 36 is positioned on the circuit board 24 such that it is in close proximity to the housing 4 and, in particular, in close proximity to at least one of the terminals 8a, b, preferably in contact with at least one of the terminals 8a, b. The ohmic resistance across the NTC resistor 36 can be measured by an operational amplifier 28, and a temperature at the terminals 8a, b can be determined from this measurement. The operational amplifier 28 can also compare the measured temperature with a reference value and output a comparison result. The processor 26 can evaluate the comparison results and, if necessary, output an ignition pulse via contacts 38, which are connected to the ignition contacts 14.

[0056] Finally, it shows Fig.Figure 4 shows the assembly of a housing 4 with a printed circuit board 24. It can be seen that the printed circuit board 24, with its mountings 32, accommodates the mounting pins 18. Furthermore, it can be seen that the operational amplifiers 28 are mounted in the mountings 32, so that the housing 4 rests directly against the printed circuit board 24. This allows for particularly good temperature sensing at the connection tabs 8a, b. It also enables the locking element 2 to be particularly compact. Reference symbol list 2 pyrotechnic safety devices 4 cases 6 recording 8a, b Connection tab 10 shot channel 12 pyrotechnic propulsion 12a Seal 14 Ignition contact 16 Separation point 18 fastening pins 20 recordings 22 blast area 24 circuit boards 26 processor 28 Comparator 30 passive components 32 recording 34 Connection contact, contact 36 NTC resistor

Claims

[1] Safety element, in particular comprising for a motor vehicle power line, - a control circuit and - a pyrotechnic fuse (2), wherein - the control circuit comprising a printed circuit board (24) - at least one measuring sensor, - at least one temperature sensor and - at least one processor (26) evaluating the measuring sensor and the temperature sensor, - the pyrotechnic safety device (2) - a first connecting tab (8a), - a second connecting tab (8b), - a separation point (16) arranged between the connecting tabs (8a, b), and - has a pyrotechnic drive acting on the separation point (16), wherein - the drive (12) has ignition contacts (14) on its side facing away from its explosive surface (22), and wherein characterized by , - the pyrotechnic fuse (2) is attached directly to the circuit board (24) at least in a form-fitting manner, - that the drive (12) is designed in such a way that it can be triggered both intrinsically and extrinsically, in which - in the event of an intrinsic triggering, the processor (26) applies an ignition voltage to the drive (12) via a connection between the processor (26) and the ignition contacts (14) and - the ignition contacts (14) are set up for connection to an external ignition signal and the external ignition signal is applied to the ignition contacts (14) during external triggering. [2] Locking element according to claim 1, characterized by , - that the measuring sensor measures an electrical parameter across the separation point (16). [3] Locking element according to claim 1 or 2, characterized by , - that the connecting tabs (8a, b) are formed as flat parts which are connected to each other at the separation point (16), wherein the separation point (16) has a predetermined breaking point. [4] Locking element according to any of the preceding claims, characterized by , - that the connecting tabs (8a, b) surround the drive (12) in a U-shape. [5] Locking element according to any of the preceding claims, characterized by , - that the connecting tabs (8a, b) grip the housing (4) on the side facing away from the separation point (16). [6] Locking element according to any of the preceding claims, characterized by , - that the drive (12) is arranged in a housing (4), that the housing (4) has receptacles (6, 20, 32) for the connecting tabs (8a, b) and that the housing (4) is attached to the circuit board (24) with fastening means. [7] Locking element according to any of the preceding claims, characterized by , - that the housing (4) has at least a recess on its outer surface for receiving (6) at least one component of the printed circuit board (24). [8] Locking element according to any of the preceding claims, characterized by , - that the drive (12) is aligned with a blast surface (22) in the direction of the separation point (16) and / or that ignition contacts (14) of the drive (12) are arranged on a side facing away from the blast surface (22). [9] Locking element according to any of the preceding claims, characterized by , - that the pyrotechnic fuse (2) is attached to the circuit board (24) in such a way that the temperature sensor is in contact (34) with the fuse. [10] Locking element according to any of the preceding claims, characterized by , - that the temperature sensor is connected to the connection tabs (8a, b) via temperature probes. [11] Locking element according to any of the preceding claims, characterized by , - that the temperature sensor is an NTC resistor. [12] Locking element according to any of the preceding claims, characterized by , - that the circuit board (24) has at least one comparator (28) which a) compares a measured value from the measuring sensor with a reference value and outputs a reference value depending on the comparison and / or b) compares a measured value from the temperature sensor with a reference value and outputs a reference value depending on the comparison. [13] Locking element according to any of the preceding claims, characterized by , - that the processor (26) is in operative connection with at least one comparator (28) and controls the drive (12) depending on the comparison value.

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