Fuse device

Abstract

The invention proceeds from a fuse device (10a-c), in particular a domestic appliance fuse device, having a printed circuit board (12a-c) and at least one fuse unit (14a-c) located on the printed circuit board (12a-c), which has a plurality of fuses (16a-c) that are designed as individual conductor paths on the printed circuit board (12a-c) and are electrically parallel to one another. In order to improve efficiency, according to the invention at least one of the fuses (16a-c) has a cross-sectional surface perpendicular to its main extension (18a-c) that varies along the main extension (18a-c).

Description

[0001] Safety device

[0002] The invention relates to a safety device according to the preamble of claim 1 and a method for producing a safety device according to the preamble of claim 12.

[0003] Fuse devices are already known from the prior art, comprising a fuse unit arranged on a circuit board with a plurality of fuses configured as conductor tracks and arranged electrically parallel to one another. For example, DE 10 2013 205 272 A1 discloses an electronic assembly comprising a circuit board, a high-current component, and a high-current conductor track fuse with a plurality of individual fuses configured as conductor tracks on the circuit board. All fuses are connected in parallel and contact the high-current component with a common electrical potential.

[0004] The object of the invention is, in particular but not limited to, to provide a generic device with improved properties in terms of efficiency. This object is achieved according to the invention by the features of claims 1 and 12, while advantageous embodiments and further developments of the invention can be found in the subclaims.

[0005] The invention relates to a safety device, in particular a household appliance safety device, comprising a printed circuit board and at least one fuse unit arranged on the printed circuit board, which fuse unit has a plurality of fuses which are designed as individual conductor tracks on the printed circuit board and are arranged electrically parallel to one another.

[0006] It is proposed that at least one of the fuses has a cross-sectional area perpendicular to its main extension which varies along the main extension.

[0007] Such a design advantageously provides a safety device with improved efficiency properties. In particular, material efficiency and cost efficiency can be improved. At the same time, the safety device exhibits consistent or improved safety and reliability properties compared to generic safety devices. Compared to conventional fuses with a constant cross-sectional area along the main extension, varying the cross-sectional area of ​​at least one fuse results in only a slight temperature increase, so that the risk of false triggering during normal operation is negligible.At the same time, however, the fuse unit responds more quickly in the event of a fault, for example in the event of a short circuit, since the variation in the cross-sectional area allows a higher temperature rise rate to be achieved and less metal has to be evaporated in the area of ​​the smallest cross-sectional area of ​​the fuse.

[0008] The safety device is designed as a structural and / or functional component of an appliance, preferably a household appliance, and is intended to protect at least one element and / or one unit of the appliance from damage caused by overcurrents, in particular by short circuits. For example, a household appliance having the safety device could be a freezer or a refrigerator and / or freezer. Alternatively or additionally, a household appliance having the safety device could be, for example, a dishwasher and / or a washing machine and / or a dryer. Advantageously, a household appliance having the safety device is a cooking appliance. A household appliance designed as a cooking appliance could be, for example, an oven and / or a microwave and / or a grill and / or a steamer.Advantageously, a household appliance designed as a cooking appliance is a hob, preferably an induction hob. Furthermore, the safety device could be used in household appliances other than those mentioned above without departing from the scope of the present invention.

[0009] The securing device comprises the printed circuit board, wherein the printed circuit board is not limited to a specific type, but can be designed, for example, as a rigid printed circuit board or as a flexible printed circuit board or as a rigid-flexible printed circuit board.

[0010] The fuse unit has a plurality of at least two fuses, which are formed as individual conductor tracks on the circuit board and arranged electrically parallel to one another. The fuse unit can have a total of more than two fuses, for example at least three, in particular at least five, advantageously at least seven, particularly advantageously at least nine, preferably at least eleven, preferably at least thirteen, and particularly preferably at least fifteen. The fuses formed as conductor tracks are made of an electrically conductive material, for example copper or aluminum, or of another electrically conductive material deemed appropriate by a person skilled in the art.

[0011] At least one of the fuses of the fuse unit has a cross-sectional area perpendicular to its main extension, which varies along the main extension. A main extension is understood to be a longest straight extension of the fuse parallel to its main extension direction. A “main extension direction” of an object is understood to be a direction that runs parallel to a longest edge of a smallest geometric cuboid that just completely encloses the object. Due to the variation of the cross-sectional area along the main extension, the at least one fuse has at least one region with a smallest cross-sectional area and at least one region with a largest cross-sectional area. Preferably, the fuse has a width perpendicular to the main extension in the region of the largest cross-sectional area that corresponds to an initial width of the fuse.The cross-sectional area of ​​the at least one fuse preferably varies between the region of the largest cross-sectional area and the region of the smallest cross-sectional area by at least 10%, preferably by at least 20%, and particularly preferably by at least 30%. The cross-sectional area of ​​the at least one fuse preferably varies continuously, in particular steadily, between the region of the largest cross-sectional area and the region of the smallest cross-sectional area. In an operating state of the fuse unit, the region of the smallest cross-sectional area of ​​the at least one fuse determines a tripping characteristic of the fuse unit, since in the region of the smallest cross-sectional area a current density is locally increased when current flows through the fuse. The fuses of the fuse unit preferably form an avalanche protection device together.If the fuses of the fuse unit form an avalanche protection device, the at least one fuse whose cross-sectional area varies along its main extension is the first to trip in the event of an overcurrent, whereby due to the parallel connection a current density in the remaining fuses increases and the remaining fuses also melt and a current flow via the fuse unit is interrupted.

[0012] In this document, numerals such as "first" and "second," which precede certain terms, serve only to distinguish between objects and / or to correlate objects with each other and do not imply a total number and / or ranking of the objects. In particular, a "second object" does not necessarily imply the presence of a "first object."

[0013] "Intended" should be understood as specifically programmed, designed, and / or equipped. The fact that an object is intended for a specific function should be understood as meaning that the object fulfills and / or performs this specific function in at least one application and / or operating state.

[0014] It is further proposed that the fuses of the fuse unit be designed as fusible links. This advantageously further increases efficiency. A reliable fuse unit can be provided using particularly simple technical means.

[0015] It is also proposed that all fuses of the fuse unit have a cross-sectional area perpendicular to their respective main extension, which varies along the respective main extension. This can advantageously further improve efficiency. In particular, material savings can be improved if all fuses of the fuse unit have a cross-sectional area perpendicular to their respective main extension, which varies along the respective main extension. All fuses of the fuse unit could have a geometry that is essentially identical to one another. However, it is also conceivable for some or all fuses of the fuse unit to have different geometries and, in particular, different variations of the cross-sectional area along their respective main extension.In this case, exactly one of the fuses can have a smallest cross-sectional area in at least one region, which is also the smallest cross-sectional area of ​​all fuses and thus determines a triggering characteristic of the fuse unit. Furthermore, it is proposed that the at least one fuse, in a region of its smallest cross-sectional area perpendicular to its main extension, has a width that is reduced by at least 40% and at most 60% compared to an initial width running perpendicular to its main extension direction. Such a configuration can advantageously achieve a low temperature rise.Preferably, the at least one fuse has, compared to a conventional fuse with a constant width along the main extent, which corresponds to the initial width, a maximum absolute temperature rise of at most 5 Kelvin, preferably of at most 4 Kelvin and particularly preferably of at most 3 Kelvin, at the same current load.Investigations by the applicant have shown that this maximum absolute temperature rise can be achieved if the at least one fuse has a width in the region of its smallest cross-sectional area perpendicular to its main extension which is reduced by a maximum of 60% compared to the initial width running perpendicular to its main extension direction, wherein this relationship, within the scope of the orders of magnitude customary for conductor tracks on printed circuit boards, is independent of the absolute dimensions of the reduced width and the initial width and is dependent only on a degree of reduction in the width relative to the initial width.On the other hand, if the at least one fuse has a width in the region of its smallest cross-sectional area perpendicular to its main extension which is reduced by at least 40% compared to the initial width running perpendicular to its main extension direction, a higher temperature rise rate and thus a faster triggering of the fuse unit in the event of a fault can be enabled.

[0016] In an advantageous embodiment, it is additionally proposed that a region of a smallest cross-sectional area of ​​the at least one fuse is aligned centrally with respect to its main extent. This can advantageously further improve efficiency. In particular, manufacturing costs can be reduced. This embodiment proves to be particularly advantageous when an input region and an output region of the fuse unit and / or the circuit board to which the at least one fuse is connected have similar, preferably identical, properties with regard to heat dissipation capacity. In an alternative advantageous embodiment, it is proposed that a region of a smallest cross-sectional area of ​​the fuse is aligned off-center with respect to its main extent. This can advantageously improve flexibility.Furthermore, it is proposed that the off-center region of the smallest cross-sectional area of ​​the at least one fuse faces a region of the fuse unit and / or the circuit board which has a high heat dissipation capacity. This allows flexibility to be further increased while maintaining the reliability of the fuse device. This embodiment proves to be particularly advantageous when the region of high heat dissipation capacity, which can be either the input region or the output region of the fuse unit and / or the circuit board to which the at least one fuse is connected, has a higher heat dissipation capacity than another region of low heat dissipation capacity to which the at least one fuse is connected.Therefore, even in the case of asymmetrical geometries of the fuse unit and / or circuit board, which may be necessary, for example, due to limited space or other technical reasons, the risk of false triggering during normal operation due to locally increased temperature in the area of ​​the smallest cross-sectional area of ​​the fuse can be reduced using simple technical means.

[0017] It is further proposed that the fuses have main extensions that are geometrically aligned parallel to one another. This can advantageously further improve efficiency. In particular, manufacturing costs can be reduced. Furthermore, it is proposed that the fuses be arranged at regular intervals from one another. This can advantageously improve reliability. In particular, the risk of false triggering of the fuse unit during normal operation without overcurrents can be reduced if the fuses are arranged at regular intervals from one another. Each of the fuses is preferably arranged at a specific distance from an immediately adjacent fuse, which distance is the same for all fuses. This can advantageously reduce the risk of false triggering during normal operation due to heat input from one fuse to the immediately adjacent fuse.In an alternative advantageous embodiment, it is proposed that a main extension of at least one of the fuses be aligned at an angle to at least one further main extension of another of the fuses. This can advantageously further increase flexibility. In particular, particularly compact designs of the fuse unit are advantageously enabled. The main extension of the at least one fuse can, for example, be aligned perpendicular to the further main extension of the further fuse. However, any other angles greater than 0° and less than 180° between the main extension of the at least one fuse and the further main extension of the further fuse are also conceivable without departing from the scope of the present invention.

[0018] The invention also relates to a household appliance with at least one safety device according to one of the previously described embodiments. Such a household appliance is characterized in particular by the advantageous properties that can be achieved by the previously described features of the household appliance device.

[0019] The invention further relates to a method for producing a fuse device, in particular according to one of the previously described embodiments, with a printed circuit board and with at least one fuse unit which has a plurality of fuses and which is arranged on the printed circuit board, wherein the fuses are applied as individual conductor tracks on the printed circuit board and are arranged electrically parallel to one another.

[0020] It is proposed that at least one of the fuses be applied to the circuit board with a cross-sectional area that varies perpendicular to its main extension. Such a method can advantageously enable particularly efficient production of the fuse device.

[0021] The safety device is not intended to be limited to the application and embodiment described above. In particular, the safety device may have a number of individual elements, components, and units that differs from the number stated herein to fulfill a function described herein. Further advantages will become apparent from the following description of the drawings. The drawings illustrate three exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will expediently consider the features individually and combine them into further meaningful combinations.

[0022] They show:

[0023] Fig. 1 shows a household appliance with a safety device in a schematic representation,

[0024] Fig. 2 is a schematic representation of the fuse device with a circuit board and a fuse unit having a plurality of fuses,

[0025] Fig. 3 is a schematic representation of one of the fuses with a cross-sectional area varying along its main extension,

[0026] Fig. 4 is a schematic diagram showing a relationship between a temperature rise and a degree of reduction of a width of the fuse in a region of its smallest cross-sectional area compared to its initial width,

[0027] Fig. 5 is a schematic diagram showing simulation results for a temperature rise of the fuse unit with different total numbers of fuses,

[0028] Fig. 6 is a schematic process flow diagram of a process for producing the safety device,

[0029] Fig. 7 shows a further embodiment of a safety device with a circuit board and a safety unit in a schematic representation and

[0030] Fig. 8 shows a further embodiment of a security device with a circuit board and a security unit in a schematic representation.

[0031] Figure 1 shows a schematic representation of a household appliance 34a. In the present exemplary embodiment, the household appliance 34a is embodied, for example, as a cooktop, specifically as an induction cooktop. The household appliance 34a embodied as an induction cooktop has a cooktop plate 36a and four inductors 38a arranged beneath the cooktop plate 36a.

[0032] Of multiple objects, only one is provided with a reference symbol in the figures.

[0033] The household appliance designed as an induction hob has a control unit 40a which includes an inverter unit (not shown) for supplying energy to the inductors 38a.

[0034] The household appliance 34a has a safety device 10a. In the present case, the safety device 10a is designed as a household appliance safety device. In the present exemplary embodiment, the safety device 10a is provided, for example, for short-circuit protection of the control unit 40a. The control unit 40a is connected to a power supply (not shown) via the safety unit 10a.However, the safety device 10a is not limited to use for short-circuit protection of the control unit 40a of the household appliance 34a designed as an induction hob, but can alternatively or additionally also be used to protect other units (not shown) of the household appliance 34a and / or in other household appliances (not shown), for example ovens and / or refrigerators and / or freezers and / or washing machines and / or dishwashers and / or dryers and / or the like, without departing from the scope of the present invention.

[0035] Figure 2 shows the fuse device 10a in a schematic representation. The fuse device 10a has a printed circuit board 12a. The fuse device 10a has at least one fuse unit 14a, in this case exactly one. The fuse unit 14a comprises a plurality of fuses 16a. The fuses 16a are formed as individual conductor tracks on the printed circuit board 12a. The fuses 16a are arranged electrically parallel to one another. In this case, the fuse unit 14a comprises a total of nine fuses 16a, although a higher or lower number of fuses 16a would also be conceivable.

[0036] The fuses 16a each have a main extension 18a. In this case, the main extensions 18a each have essentially the same length. The main extension 18a can be, for example, 3.2 mm, although shorter or longer main extensions 18a are also conceivable.

[0037] In the present case, the fuses 16a have mutually parallel main extensions 18a. The fuses 16a are spaced apart from one another at regular intervals 28a. Each of the fuses 16a is arranged at the same distance 28a from an immediately adjacent fuse 16a.

[0038] At least one of the fuses 16a has a cross-sectional area perpendicular to its main extension 18a, which varies along the main extension 18a. In the present case, all fuses 18a of the fuse unit 14a have a cross-sectional area perpendicular to their respective main extension 18a, which varies along the respective main extension 18a.

[0039] In this case, the fuses 16a of the fuse unit 14a are each designed as fusible links.

[0040] In the present embodiment, the fuses 16a of the fuse unit 16a together form an avalanche protection device. As soon as an overcurrent event occurs, at least one of the fuses 16a blows. This results in an increase in the current density in the remaining fuses 16a due to the parallel connection, causing the remaining fuses 16a to also blow and interrupting the current flow through the fuse unit 14a.

[0041] The fuse unit 14a has a total width 76a. Each of the fuses 76a has an initial width 24a (see Figure 3) perpendicular to its main extension direction 18a, which in this case is the same for each of the fuses 16a. The sum of the initial widths 24a of all fuses 16a results in the total width 76a of the fuse.

[0042] The fuse unit 14a has a region 26a and a further region 84a. Each of the fuses 16a extends from the region 26a and opens into the further region 84a. The region 26a and the further region 84a each have a total width of 76a and essentially identical volumes. The fuses 16a, the region 26a, and the further region 84a are formed in one piece and consist of the same electrically conductive material, for example, copper. The region 26a can be provided for connecting the fuse unit 14a to the power supply for the household appliance 34a (see Figure 1). The further region 84a can be provided for connecting to the control unit 40a of the household appliance 34a.

[0043] Figure 3 shows one of the fuses 16a of the fuse unit 14a in a schematic representation.

[0044] The at least one fuse 16a has a width 22a in a region 20a of its smallest cross-sectional area perpendicular to its main extension 18a. The width 22a in the region 20a of the smallest cross-sectional area of ​​the fuse 16a is reduced by at least 40% and at most 60% compared to the initial width 24a extending perpendicular to its main extension 18a.

[0045] The fuse 16a has a first end region 42a and a second end region 44a. In the first end region 42a and in the second end region 44a, the fuse 16a has an initial width of 24a perpendicular to its main extension 18a.

[0046] In the present embodiment, the region 20a of the smallest cross-sectional area of ​​the at least one fuse 16a is centrally aligned with respect to its main extension 18a. The region 20a of the smallest cross-sectional area is equally spaced from the first end region 42a and the second end region 44a.

[0047] The fuse 16a has a first recess 68a and a second recess 70a. The recesses 68a, 70a each have an arcuate geometry, are formed on opposite sides of the fuse 16a, and each extend from the first end region 42a to the second end region 44a. Due to the recesses 68a, 70a, the cross-sectional area of ​​the fuse 16a continuously decreases from the first end region 42a along the main extension 18a to the region 20a and continuously increases from the region 20a to the second end region 44a. The first recess 68a and the second recess 70a are mirror-symmetrical with respect to a longitudinal center axis (not shown) of the fuse 16a running parallel to the main extension 18a. In the region 20a, the first recess 68a has a maximum width 72a, and the second recess 70a has a maximum width 74a. The maximum widths 72a and 74a are equal in this case.The width 20a of the fuse 16a in the region of its smallest cross-sectional area perpendicular to its main extension 18a is thus obtained by subtracting the maximum width 72a and the maximum width 74a from the initial width 24a.

[0048] Figure 4 shows a schematic diagram illustrating a relationship between a temperature increase and a degree of reduction in the width 22a of the fuse 16a in the region 20a of its smallest cross-sectional area compared to its initial width 24a. A reduction in the width 22a of the fuse 16a in the region of its smallest cross-sectional area compared to the initial width 24a is plotted as a dimensionless parameter on an abscissa 46a of the diagram. A temperature increase in Kelvin is plotted on an ordinate 48a of the diagram. A curve 50a in the diagram shows the relationship between the degree of reduction in the width 22a compared to the initial width 24a and the temperature increase. As can be seen from the diagram, for example, if the width 22a of the fuse 16a in the region 20a of the smallest cross-sectional area is reduced by 40% compared to the initial width 24a, a temperature increase of 2 Kelvin results.The heating of the fuse 16a due to the reduced width 22a in the region 20a when subjected to an electric current of an electrical current intensity in a range for which the fuse 16a is designed for normal operation, i.e., without tripping, is 2 Kelvin higher compared to a conventional fuse (not shown), which has a constant width perpendicular to its main extension, for the same current intensity. If the width 22a of the fuse 16a is reduced by 60% in the region 20a of the smallest cross-sectional area compared to the initial width 24a, a temperature increase of 3 Kelvin results.

[0049] Investigations by the applicant have shown that the relationship represented by curve 50a in the diagram in Figure 4 is scale-invariant within a range of magnitudes relevant for fuses formed as conductor tracks on printed circuit boards. This means that the relationship shown between temperature rise and the degree of reduction in width 22a compared to the initial width 24a is generally valid within this range of magnitude and depends only on the relative reduction in width 22a compared to the initial width 24a and not on the absolute sizes of width 22a and initial width 24a. The diagram in Figure 4 can therefore be used to design the fuses 16a of the fuse unit 14a of the fuse device 10a.

[0050] Figure 5 shows a schematic diagram illustrating simulation results for a temperature rise of the fuse unit 14a, with different total numbers N of fuses 16a when a fault current of 150 A / ms occurs. A time in milliseconds is plotted on an abscissa 52a of the diagram. A temperature in Celsius is plotted on an ordinate 54a of the diagram. A first curve 56a shows a profile of a temperature rise rate for the case in which the fuse unit 14a has a total of five fuses 16a connected electrically in parallel. A second curve 58a shows a profile of a temperature rise rate for the case in which the fuse unit 14a has a total of seven fuses 16a connected electrically in parallel.A third curve 60a shows a profile of a temperature rise rate for the case where the fuse unit 14a has a total of nine fuses 16a connected electrically in parallel. A fourth curve 62a shows a profile of a temperature rise rate for the case where the fuse unit 14a has a total of eleven fuses 16a connected electrically in parallel. A fifth curve 64a shows a profile of a temperature rise rate for the case where the fuse unit 14a has a total of thirteen fuses 16a connected electrically in parallel. A sixth curve 66a shows a profile of a temperature rise rate for the case where the fuse unit 14a has a total of fifteen fuses 16a connected electrically in parallel.For each of the cases represented by curves 56a, 58a, 60a, 62a, 64a, 66a, the fuse unit 14a trips in a temperature range 78a between 1050°C and 1100°C. For each of the cases represented by curves 56a, 58a, 60a, 62a, 64a, 66a, the fuse unit 14a has the same total width 76a (see Figure 2), which is, however, divided among different total numbers N of fuses 16a. For the case represented by the first curve 56a, for example, each of the five fuses 16a has an initial width 24a (see Figure 3), which corresponds to one-fifth of the total width 76a. For the test series shown in the diagram in Figure 5, the maximum widths 72a, 74a of the recesses 68a, 70a were kept constant, whereby the initial width 24a and thus also the width 20a (cf.Figure 3) the smallest cross-sectional area of ​​each of the fuses 16a is reduced with increasing total number N of fuses 16a of the fuse unit 14a. For an increase in the total number N of fuses 16a from five (first curve 56a) to fifteen (sixth curve 66a), with the present simulation results with a total width 76a of 4 mm and maximum widths 72a, 74a of the recesses 68a, 70a of 100 μm each, a reduction of 50% of the width 22a in the region 20a of their smallest cross-sectional area perpendicular to their main extension results for each of the fuses 16a. As a result, the time until the fuse unit 14a is triggered can be reduced from 6.5 ms with a total of five fuses 16a to approximately 5 ms with a total of fifteen fuses 16a.

[0051] Figure 6 shows a schematic process flow diagram illustrating a process for producing the fuse device 10a. In the process, the fuse unit 14a is applied to the printed circuit board 12a. The process comprises two process steps 80a, 82a. In a first process step 80a of the process, the printed circuit board 12a is provided. In a second process step 82a of the process, the fuse unit 14a is applied to the printed circuit board 12a. In this case, the fuses 16a are applied as individual conductor tracks to the printed circuit board 12a and arranged electrically parallel to one another, wherein at least one of the fuses 16a is applied to the printed circuit board 12a with a cross-sectional area varying perpendicular to its main extension 18a.The application of the fuses 16a of the fuse unit 14a as conductor tracks can be carried out by means of methods known from the prior art, for example photolithographically and / or by insulation milling and / or by means of punching technology and / or wire laying technology and / or by means of screen printing and / or by any other technique that appears appropriate to the person skilled in the art.

[0052] Two further exemplary embodiments of the invention are shown in Figures 7 and 8. The following descriptions are essentially limited to the differences between the exemplary embodiments, whereby reference can be made to the description of the exemplary embodiment in Figures 1 to 6 with regard to identical components, features and functions. To distinguish the exemplary embodiments, the letter a in the reference numerals of the exemplary embodiment in Figures 1 to 6 has been replaced by the letter b in the reference numerals of the exemplary embodiment in Figure 7 and by the letter c in the reference numerals of the exemplary embodiment in Figure 8. With regard to components with the same designation, in particular with regard to components with the same reference numerals, reference can in principle also be made to the drawings and / or the description of the exemplary embodiment in Figures 1 to 6.

[0053] Figure 7 shows a further exemplary embodiment of a fuse device 10b in a schematic representation. Analogous to the first exemplary embodiment, the fuse device 10b has a printed circuit board 12b and a fuse unit 14b. The fuse unit 14b comprises a plurality of fuses 16b, which are formed as individual conductor tracks on the printed circuit board 12b and arranged electrically parallel to one another. At least one of the fuses 16b has a cross-sectional area perpendicular to its main extension 18b, which varies along the main extension 18b. In the present case, all fuses 16b of the fuse unit 14b have a cross-sectional area perpendicular to their respective main extension 18b, which varies along the respective main extension 18b.

[0054] Analogous to the previous exemplary embodiment, the at least one fuse 16b has a width (not shown) in a region 20b of its smallest cross-sectional area perpendicular to its main extension 18b that is reduced by at least 40% and at most 60% compared to an initial width (not shown) running perpendicular to its main extension 18b. In Figure 7, the region 20b is symbolized only by a dashed circle, and the cross-sectional taper of the fuse 16b in this region is not shown. With regard to the geometry of the fuse 16b, reference can be made to the geometry of the fuse 16a from the first exemplary embodiment shown in Figure 3.

[0055] In contrast to the first exemplary embodiment, the region 20b of the smallest cross-sectional area of ​​the fuse 16b is oriented off-center with respect to its main extension 18b. The off-center region 20b of the smallest cross-sectional area of ​​the at least one fuse 16b faces a region 26b of the fuse unit 14b, which has a high heat dissipation capacity. In the present case, the region 26b, in contrast to the previous exemplary embodiment, has a larger volume and thus a higher heat dissipation capacity than a further region 84b of the fuse unit 14b. The region 20b is spaced closer to the region 26b than to the further region 84b. This allows heat to be better dissipated from the region 20b during normal operation, and false triggering of the fuse device 10b can be prevented.

[0056] The securing unit 14b has a further securing element 32b, which is designed essentially identically to the securing element 16b. A further difference between the securing device 10b and the securing device 10a from the previous exemplary embodiment is that the main extension 18b of at least one of the securing elements 16b is aligned at an angle to at least one further main extension 30b of the further securing element 32b of the securing unit 14b. In the present case, the main extension 18b is aligned perpendicular to the further main extension 30b. In the present case, the securing unit 14b has two securing elements 16b and two further securing elements 32b. The securing elements 16b are aligned parallel to one another. The further securing elements 32b are also aligned parallel to one another.

[0057] Figure 8 shows a further embodiment of a fuse device 10c in a schematic representation. Analogous to the previous embodiments, the fuse device 10c has a printed circuit board 12c and a fuse unit 14c. The fuse unit 14c comprises a plurality of fuses 16c, which are formed as individual conductor tracks on the printed circuit board 12c and arranged electrically parallel to one another. At least one of the fuses 16c has a cross-sectional area perpendicular to its main extension 18c, which varies along the main extension 18c. In the present case, all fuses 16c of the fuse unit 14c have a cross-sectional area perpendicular to their respective main extension 18c, which varies along the respective main extension 18c.

[0058] Analogous to the previous exemplary embodiments, the at least one fuse 16c has a width (not shown) in a region 20c of its smallest cross-sectional area perpendicular to its main extension 18c, which is reduced by at least 40% and at most 60% compared to an initial width (not shown) running perpendicular to its main extension 18c. In Figure 8, the region 20c is symbolized only by a dashed line, and the cross-sectional taper of the fuse 16c in this region is not shown. With regard to the geometry of the fuse 16c, reference can again be made to the geometry of the fuse 16a from the first exemplary embodiment shown in Figure 3. Analogous to the second exemplary embodiment shown in Figure 7, the region 20c of the smallest cross-sectional area of ​​the fuse 16c is aligned off-center with respect to its main extension 18c.The off-center region 20c of the smallest cross-sectional area of ​​the at least one fuse 16c faces a region 26c of the fuse unit 14c, which has a high heat dissipation capacity. In the present case, the region 26c and a further region 84c of the fuse unit 14c, in contrast to the previous exemplary embodiment, have essentially identical volumes. However, the region 20c is arranged closer to a long edge of the region 26c than to a short edge of the further region 84c. The region 26c has a larger partial volume in a partial region extending from the long edge than the further region 84c in a partial region extending from the short edge.Thus, heat from the region 20c can be better dissipated via the region 26c during normal operation if the region 26c is arranged off-center with respect to the main extension 18c and faces the region 26c, thus preventing false triggering of the safety device 10c.

[0059] In the present case, the securing unit 14c has two fuses 16c. The securing unit 14c also has a further fuse 32c, which is designed essentially identically to the fuses 16c. Analogous to the securing device 10b from the previous exemplary embodiment, the main extension 18c of at least one of the fuses 16c is oriented at an angle to at least one further main extension 30c of the further fuse 32c of the securing unit 14c. In contrast to the previous exemplary embodiment, however, the main extension 18c is not perpendicular, but rather at an angle of approximately 45° to the further main extension 30c. Reference numeral

[0060] 10 Safety device

[0061] 12 circuit board

[0062] 14 Fuse unit

[0063] 16 Security

[0064] 18 Main extension

[0065] 20 area

[0066] 22 width

[0067] 24 Exit width

[0068] 26 Area

[0069] 28 distance

[0070] 30 further main extensions

[0071] 32 additional backups

[0072] 34 household appliances

[0073] 36 hob plate

[0074] 38 Inductor

[0075] 40 Control unit

[0076] 42 first end area

[0077] 44 second end area

[0078] 46 Abscissa

[0079] 48 ordinates

[0080] 50 curve

[0081] 52 Abscissa

[0082] 54 ordinates

[0083] 56 first curve

[0084] 58 second curve

[0085] 60 third curve

[0086] 62 fourth curve

[0087] 64 fifth curve sixth curve first recess second recess maximum width maximum width total width temperature range first process step second process step further range

Claims

Claims 1. A safety device (10a-c), in particular a household appliance safety device, comprising a printed circuit board (12a-c) and at least one safety unit (14a-c) arranged on the printed circuit board (12a-c), which has a plurality of fuses (16a-c) which are designed as individual conductor tracks on the printed circuit board (12a-c) and are arranged electrically parallel to one another, characterized in that at least one of the fuses (16a-c) has a cross-sectional area perpendicular to its main extension (18a-c) which varies along the main extension (18a-c).

2. Safety device (10a-c) according to claim 1, characterized in that the fuses (16a-c) of the fuse unit (14a-c) are designed as fusible links.

3. Safety device (10a-c) according to claim 1 or 2, characterized in that all the fuses (16a-c) of the fuse unit (14a-c) have a cross-sectional area perpendicular to their respective main extension (18a-c) which varies along the respective main extension (18a-c).

4. Safety device (10a-c) according to one of the preceding claims, characterized in that the at least one safety device (16a-c) has a width (22a) in a region (20a-c) of its smallest cross-sectional area perpendicular to its main extension (18a-c) which is reduced by at least 40% and at most 60% compared to an initial width (24a) running perpendicular to its main extension direction (18a-c).

5. Safety device (10a) according to one of the preceding claims, characterized in that a region (20a) of a smallest cross-sectional area of ​​the at least one safety device (16a) is aligned centrally with respect to its main extension (18a).

6. Safety device (10b; 10c) according to one of claims 1 to 5, characterized in that a region (20b; 20c) of a smallest cross-sectional area of ​​the safety device (16b; 16c) is oriented off-center with respect to its main extension (18b; 30c).

7. Fuse device (10b; 10c) according to claim 6, characterized in that the off-center region (20b; 20c) of the smallest cross-sectional area of ​​the at least one fuse (16b; 16c) faces a region (26b; 26c) of the fuse unit (14b; 14c) and / or the printed circuit board (12b; 12c) which has a high heat dissipation capacity.

8. Safety device (10a) according to one of the preceding claims, characterized in that the safety devices (16a) have main extensions (18a) which are aligned geometrically parallel to one another.

9. Safety device (10a) according to claim 8, characterized in that the fuses (16a) are arranged spaced from one another at regular intervals (28a).

10. Safety device (10b; 10c) according to one of claims 1 to 7, characterized in that a main extension (18b; 18c) of at least one of the safety devices (16b; 16c) is aligned at an angle to at least one further main extension (30b; 30c) of a further safety device (32b; 32c) of the safety unit (14b; 14c).

11. Household appliance (34a) with at least one safety device (10a-c) according to one of the preceding claims.

12. Method for producing a safety device (10a-c), in particular according to one of claims 1 to 10, with a printed circuit board (12a-c) and with at least one fuse unit (14a-c) which has a plurality of fuses (16a-c) and which is arranged on the printed circuit board (12a-c), wherein the fuses (16a-c) are arranged as individual conductor tracks on the Printed circuit board (12a-c) are applied and arranged electrically parallel to one another, characterized in that at least one of the fuses (16a-c) is applied to the printed circuit board (12a-c) with a cross-sectional area varying perpendicular to its main extension (18a-c).

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