FUSE AND ASSOCIATED MANUFACTURING PROCESS
Patent Information
- Application Number
- MX2023001114
- Authority / Receiving Office
- MX · MX
- Patent Type
- Patents
- Current Assignee / Owner
- Priority Date
- 2020-07-29
- Filing Date
- 2023-01-26
- Publication Date
- 2026-02-25
- Estimated Expiration
- 2041-07-28
Smart Images
Figure MX431504B0
Abstract
Description
FUSE AND ASSOCIATED MANUFACTURING PROCESS Field of Invention The present invention relates to a fuse and an associated manufacturing method. Background of the Invention A fuse is an electrical component consisting of two terminals that, in the event of an overcurrent exceeding a limit called the fuse rating, interrupts the flow of electrical current between the two terminals. The two terminals are attached to an insulating body and are electrically connected to each other by means of at least one fuse blade, located within a cavity formed in the insulating body. One or more fuse blades can be connected in parallel to the two terminals, depending on the size of the fuse. The description for one fuse blade can be applied to other fuse blades when there are multiple blades. The blade of a fuse is made of a conductive material that has a given electrical resistance and melting point. In normal operation, current passes through the fuse blade, and its temperature remains below the melting point. In the event of an overcurrent, the temperature of the fuse blade rises and exceeds the melting point. Ref. 342676 Melting temperature at one or more points on the fuse blade, which melts at least partially, and the current flow is irreversibly interrupted. The fuse blade comprises, between the connections to the two poles, at least an intermediate portion having a reduced surface area. This intermediate portion is called the reduced section. Each reduced section offers greater resistance to current flow than the rest of the blade. As the current flowing through the blade increases, the temperature of each reduced section rises more than the temperature of the rest of the blade. In the event of an overcurrent, the blade preferentially melts at the reduced section. When a small section melts, an electric arc is created, and the current continues to flow until the arc is extinguished. The electric arc, defined as a plasma state of matter, causes intense localized heating that promotes the melting of the fuse blade. Under the given thermal and electrical conditions, this change in the material of the fuse blade contributes to the maintenance and elongation of the electric arc. It is common practice to place arc protectors made of elastic material on the fuse blade to limit arc propagation. For example, silicone can be applied to the fuse blade in a paste-like state, requiring several hours of waiting for it to fully cure and harden. With this method, the geometry of the arc protectors produced is approximate. The waiting times slow down production, and harmful solvents often evaporate. US-2015 294 828-A1 describes how to rivet hardened silicone strips onto the fuse blade. The rivet assembly is an industrially delicate process and carries the risk of damaging the fuse blade. It is these problems that the invention aims to remedy more specifically by proposing a fuse that offers better performance and is easier to assemble. Summary of the Invention For this purpose, the invention relates to a fuse, comprising: - at least one fuse blade, formed in a sheet having two opposing principal faces extending along a longitudinal axis of the fuse blade, each fuse blade comprising a part in which a reduced section is formed defining a plane transverse to the fuse blade, - two connection terminals, each terminal being connected to each fuse blade, - arc protectors, made of a preformed elastic material, which are associated in pairs, the arc protectors of the same pair being located each opposite each other on a respective principal side of the same fuse blade. According to the invention, for at least a first pair of arc protectors, an adhesive layer is interposed between the fuse blade and an inner face of each arc protector of this pair, the inner face being oriented towards one of the main faces of the fuse blade, to fix each arc protector to the fuse blade. Thanks to this invention, arc protectors are easy to mount on the fuse blade, saving time during manufacturing. The risk of damage during assembly is also reduced. According to advantageous, but not mandatory, aspects of the invention, such a fuse may incorporate one or more of the following features taken individually or in any technically feasible combination: The fuse comprises, in addition to the first pair of arc protectors, a second pair of arc protectors, the first and second pairs of arc protectors being separated from each other by at least a reduced section; Each arch protector comprises a front face, oriented towards a reduced section, and a rear face opposite the front face, while the front and rear faces of each arch protector are separated by a length of between 5 mm and 30 mm; - a distance between the front face and an opposite reduced section boundary line is between 0.5 mm and 00 mm, preferably between 1 mm and 15 mm, more preferably between 2 mm and 12 mm; - each arc protector comprises an outer face, opposite the inner face, each arc protector having a thickness, defined as a distance separating the inner face from the outer face, between 0.2 mm and 20 mm; - the arc protectors are made of an elastomeric material, which has a hardness, measured on a ShoreA scale, between 20 and 90, preferably between 40 and 70; - the arch protectors are made of silicone; - at least one perforation is made in the fuse blade on one side of the reduced section, each of such perforations being at least partially closed by the inner faces of two arc protectors of the same pair; The perforations extend parallel to the longitudinal direction of the fuse blade beyond the rear face of the arc projectors, to form rear ventilation grilles; - the rear ventilation grilles have a length between 0.1 mm and 10 mm, preferably between 0.5 and 8 mm, more preferably between 1 mm and 5 mm; The perforations extend parallel to the longitudinal direction of the fuse blade beyond the front face of the arc guards to form front ventilation grilles, wherein the front ventilation grilles have a length of between 0.1 mm and 5 mm, preferably between 1 and 3 mm; - the fuse comprises a frame, which is received in a cavity of the fuse body and which limits the movements of the fuse blades with respect to the body by means of spacers and / or shims, and - When the fuse is assembled, the arc protectors are compressed in a direction orthogonal to the main faces of the fuse blade, each arc protector having a thickness less than 99% of the thickness of this same arc protector when this arc protector is not subjected to any external stress, preferably less than 98%, more preferably less than 95%. The invention also relates to a method for manufacturing a fuse as described above, the fuse comprising at least one fuse blade with a reduced section defining a plane transverse to the fuse blade. The method comprises the steps of: - manufacture two arch protectors of a first pair, the arch protectors being made of a reticulated elastic material and with a flat inner face, - glue or glue each arch protector of the first MA / a / ZUZJ / UUl 114 pair on a respective main face of the fuse blade in the vicinity of the reduced section, interposing a layer of adhesive between the inner face of each arc protector and a respective main face of the fuse blade so that a distance between a front face of each arc protector and a line of the edge of the opposite reduced section is between 1 mm and 15 mm. Advantageously, the method comprises a stage, prior to the gluing stage, consisting of providing at least one perforation on each side of the transverse plane in the fuse blade, while during the gluing stage, the arc protectors of the first pair are glued to the fuse blade so that each perforation is at least partially blocked by the arc protectors. Brief Description of the Figures The invention will be better understood, and other advantages thereof will appear more clearly, in view of the following description of various embodiments of a fuse according to its principle, given only by way of example and made with reference to the accompanying figures, in which: Figure 1 is a perspective view of a fuse comprising several fuse blades and arc protectors according to a first embodiment of the invention, some parts being shown schematically to facilitate reading; - Figure 2 is a view of the fuse in Figure 1, along arrow II in Figure 1, omitting some parts to make it easier to read; - Figure 3 is a larger-scale schematic perspective view of a fuse blade and arc guards from Figure 1, along arrow III in Figure 1; - Figures 4A and 4B schematically show two views of the same fuse blade and arcs according to another embodiment of the invention; - Figures 5A and 5B are figures similar to Figures 4A and 4B, showing the same fuse blade and arcs according to another embodiment of the invention; - Figures 6A and 6B are figures similar to Figures 4A and 4B, showing the same fuse blade and arcs according to another embodiment of the invention; - Figure 7 is a graph illustrating the evolution of an electric current passing through the blade of a fuse according to the state of the art or the embodiments of the invention; - Figure 8 is a diagram showing the steps of a method for manufacturing a fuse blade and arc arresters according to embodiments of the invention; - Figure Si is a figure similar to Figure 3, 1114 showing a fuse and arc blade according to another embodiment of the invention, and - Figures 10A and 10B schematically represent two views of the same fuse blade and arcs in Figure 9. Detailed Description of the Invention Figure 1 shows a fuse 2. The fuse 2 comprises a body 20, shown schematically with dotted lines, and two connection terminals 22. Body 20 is made of an insulating material, for example, ceramic. Body 20 is generally shaped like an elongated cylinder that defines a longitudinal axis A2 of fuse 2. In the illustrated example, body 20 is shaped like a parallelepiped, that is, body 20 is a cylinder with a rectangular cross-section. In a non-limiting variant, body 20 has an elliptical or even circular cross-section. A transverse direction is defined as a direction orthogonal to axis A2. A transverse plane of fuse 2 is thus a plane orthogonal to axis A2. In the illustrated example, the terminals 22 are arranged on two respective faces of the body 20, opposite and orthogonal to axis A2. Each terminal 22 has the form of a cylinder with an oval cross-section and a generator parallel to axis A2. An oblong hole 24 is made through each terminal 22. Each terminal 22 comprises a plate 26, intended for mounting 1114 Fuse 2 in a fuse holder, not shown. The body 20 of fuse 2 comprises a cavity V20, in which the fuse blades 4 are housed. Each fuse blade 4 comprises two opposing fixing ends 40, each end 40 being connected to one of the terminals 22. The fuse blades 4 are thus electrically connected in parallel to the terminals 22. In other words, each terminal 22 is connected to one of the respective fixing ends 40 of each fuse blade 4. The fuse blades (4) are shown here in a number of four; this number may vary depending on the size of the fuse (2), particularly the voltage and amperage for which the fuse (2) is designed. When a fuse (2) comprises several fuse blades (4), the fuse blades (4) advantageously have the same structure and function in the same way. The fuse blades (4) of the fuse (2) are preferably identical. What is explained for one fuse blade (4) can be applied to the other fuse blades (4). The fuse blades (4) are manufactured from a conductive material with a specific electrical resistance and melting point. The material of the fuse blades (4) is preferably metallic, for example, silver, designated as Ag. Each fuse blade (4) is rectangular in shape. MA / a / ZUZJ / UUl 114 elongated, whose long sides are arranged parallel to axis A2. Each fuse blade 4 has a constant width, measured transversely to axis A2. Each fuse blade 4 here has a symmetrical shape with respect to a transverse plane P4 and is formed into a blade, which has two opposite principal faces, extending along the longitudinal axis A2 and comprising flat portions separated by transverse folds 42. In the illustrated example, the flat portions of the same fuse blade 4 are located in the same median plane; the median planes of each of the fuse blades 4 are mutually parallel and define a principal axis denoted as A4. The axis A4 is transverse to the axis A2. As a variant, the flat portions of the same fuse blade 4 are not all located in the same median plane. In some of the flat parts of each fuse blade 4, rows of holes 44 are made, each row of holes 44 being oriented transversely to axis A2 and defining a reduced section 46. In other words, each fuse blade 4 comprises an intermediate portion between the two fixing ends 40 in which a reduced section 46 is provided. Each blade 4 of the fuse has, at the level of each reduced section 46, a higher electrical resistance than the electrical resistance at any other location. Thus, when an electric current flows between terminals 22, the blade 4 of the fuse experiences localized heating at the reduced sections 46. In the event of an overcurrent, melting of the fuse blade 4 material occurs preferentially at the reduced sections 46. In the illustrated example, each fuse blade 4 has several types of reduced sections 46, the holes 44 having, for example, different diameters depending on the reduced section 46 considered. Therefore, when an overcurrent occurs, some reduced sections 46 are likely to melt faster than others. When the fuse blade 4 comprises only one type of reduced section 46, its breaking time / breaking current response curve has a given appearance. Combining different types of reduced sections 46 results in a response curve that is the superposition of each of the response curves corresponding to each of the sections. This aspect is not detailed further in the present description. In the illustrated example, the fuse 2 also comprises a frame 48, which is received in cavity V20 of the body 20. The frame 48 is not essential to the implementation of the invention described herein, but it contributes to its implementation. The frame 48 serves, among other things, to assemble the body 20 to the rest of the fuse 2 and to hold the fuse blade 4, for example, to protect them during the manufacture of the fuse 2. The fuse blades 4 are indeed very thin and flexible; the fuse blades 4 can have thicknesses on the order of 0.1 mm or even less. Frame 48 is made of an insulating material, preferably rigid, for example, a synthetic material, optionally reinforced with inorganic fibers such as glass fibers. By way of non-limiting examples, the reinforcement 48 can be polyimide (also called PI), polyetheretherketone (also called PEEK), polytetrafluoroethylene (also called PTFE), polyamide (also called PA), silicone, or polyphenylsulfone (also called PPSU). In the illustrated example, the frame 48 comprises two side panels 50, positioned opposite each other and connected by spacers 52. The structure of the frame 48 is not limiting. Each panel 50 comprises, on one face facing the other panel 50, notches 54 for retaining the fuse blades 4. In the example illustrated in Figure 2, the spacers 52 are shown in section, while the side panels 50 are not. The spacers 52 are grouped here into two stacks 56 of five spacers 52 each, each stack 56 being arranged in close proximity to the fixing ends 40 of the fuse blade 4. A fuse blade 4 is thus held, by compression, between two adjacent spacers 52, while the two spacers 52 located at the ends of each stack 56 are supported on the body 20, inside the cavity V20. When the body 20 is assembled to the rest of the fuse 2, the spacers 52 limit the range of movement of the fuse blades 4 relative to the rest of the fuse 2. In addition to the fuse blade 4 and the frame 4 8 received in cavity V20 of body 20, cavity 20 is generally filled with a powder that absorbs some of the energy of the electric arc that appears in case of overcurrent, contributing to faster arc extinction and quicker interruption of the electric current. This powder, which is not shown in the figures, is preferably in the form of micrometric particles and is, for example, silica sand. In the illustrated example, one of the reduced sections 46 of each fuse blade 4, referred to as 46A, is straddled on a transverse plane coinciding with the transverse plane P4. The reduced section 46A is considered primarily below, knowing that what is valid for the reduced section 46A can be generally transposed to the other reduced sections 46. The arc protectors 6, visible in section in Figure 2 and at a larger scale in perspective in Figure 3, are arranged in the vicinity of each reduced section 46A. In particular, for each reduced section 46A, four arc protectors 6 are arranged symmetrically with respect to the transverse plane P4 and symmetrically with respect to the fuse blades 4. Two arc protectors 6 located on the same side of the transverse plane P4 thus form a pair 60 of arc protectors 6, each of the arc protectors 6 of the same pair 60 being located opposite each other on a respective main face of the same fuse blade 4. In the illustrated example, the two pairs 60 of arc protectors 6 are separated from each other by a single reduced section 46A. In an unrepresented variant, two pairs 60 of arc protectors 6 are separated by several reduced sections 46 or 46A. Arc protectors 6 have similar shapes and function in the same way. In particular, arc protectors 6 of the same pair 60 are preferably identical. In the remainder of the description, the four arc protectors 6 located in the vicinity of the reduced section 46A are considered identical. Arc guards 6, also known as arc suppressors, are made of a preformed polymeric material, meaning a pre-crosslinked material. The material of arc guards 6 is elastic, meaning it can deform under mechanical stress and return to its original shape when the stress is removed. In the example shown, the arc guards 6 are made of an astrometic material. The elastomeric material of arches 6 is, for example, polysiloxane, also called silicone. A cross-linked silicone material is a solid material that has a defined shape and can be easily handled; in particular, it can be cut and / or machined with tight dimensional tolerances, whereas a non-cross-linked silicone material is generally in the form of a paste, which has no defined shape. The fuse 2 also comprises shims 58, which are connected to the fuse blades 4 or to the arc guards 6 to be immobilized with respect to the fuse blades 4, in particular during the assembly or handling of the fuse 2. Thus, during the assembly of the fuse 2, the forces due to handling are distributed among all the fuse blades 4, reducing the risk of damaging the fuse blades 4. The shims 58 also allow the fuse blades 4 to be immobilized with respect to the frame 48 when it is MA / a / ZUZJ / UUl 114 present and / or with respect to body 20 when fuse 2 is fully assembled. Optionally, when frame 48 is present, some of the shims 58 cooperate with the notches 54, or with other machined shapes or materials, not shown, formed in frame 48, to limit the movements of the fuse blades 4 with respect to frame 48. More generally, frame 48 limits the movements of the fuse blade 4 by means of the spacers 52 and / or the shims 58. Thus, during the assembly of fuse 2, the fuse blades 4 are protected by frame 48. The assembly operation can be carried out more quickly, with a reduced probability of failure, which is economically advantageous. In the example shown in Figure 2, each shoe 58 is shaped like a parallelepiped. Advantageously, the shoe 58 is made of the same material as the arch protector 6, for example, a pre-crosslinked elastomeric material such as silicone. The shoe 58 and arch protector 6 are shown schematically in Figure 2. Notably, the proportions between the dimensions of the arch protector 6 and the shoe 58 are not restrictive. In the illustrated example, the reduced sections 46A of the rifle blade 4 are aligned in the transverse plane P4, and the bow guards 6 are arranged to 1114 both sides of the transverse plane P4. Some of the shims 58, located in the vicinity of the reduced section 4 6A, are interposed between two arc protectors 6 located on the same side of the transverse plane P4 and belonging respectively to two neighboring fuse blades 4. Advantageously, the shims 58 are attached to the fuse blades 4 or the arc protectors 6 by gluing, i.e., in a manner analogous to that described later in this description, in which the arc protectors 6 are attached to the fuse blades 4. As a variant, when an arc protector 6 is in contact with a shim 58, this shim 58 is integral with this arc protector 6. Such an arc protector 6 contributes, on the one hand, to extinguishing the arc and, on the other hand, to supporting the fuse blades 4. When fuse 2 is fully assembled, the shims 58 are slightly compressed in the direction of axis A4. In particular, the arc protectors 6 are slightly compressed in the direction of axis A4 by means of the shims 1 — 58. When frame 48 is present, some of the shims 58 cooperate with frame 4 8 so that the arch protectors 6 are compressed in the direction of axis A4. A subassembly comprising a reduced section fuse blade 46A and two pairs 60 of arc protectors 6 located in the vicinity of this reduced section 46A is now described, in particular with the help of Figure 3. Each arc protector 6 has an elongated parallelepiped shape and is arranged along its length parallel to the reduced section 46A, the length of each arc protector 6 being equal to the width of the fuse blade 4. In an unshown variant, each arc protector 6 is longer than the width of the fuse blade 4. Each arc protector 6 has a front face 62, which is oriented towards the reduced section 46A in the vicinity of which the arc protector 6 is located, and a rear face 64, opposite the front face 62, i.e., facing the reduced section 46A. A length L6 is defined as the length separating the front face 62 from the rear face 64. Each arc protector 6 has an inner face 66 that is oriented towards a main face of the fuse blade 4, and an outer face 68 that is oriented opposite to the inner face 66. A thickness L7 of an arc protector 6 is defined as one that is at a distance separating the inner face 66 from the outer face 68. Two edge lines 70 of the reduced section 46A are defined as two lines parallel to the transverse plane P4, located on either side of plane E'4 and containing the reduced section 46A. These two edge lines 70 are each tangent to at least one hole 44 of the reduced section 46A. Each edge line 70 is therefore located between the reduced section 46A and the front face 62 of the adjacent arc protectors 6. In the example illustrated in Figure 3, the holes 44 of the reduced section 46A are all aligned and have the same diameter, so the edge lines 70 are tangent to all the holes 44 of the reduced section 46A. For each arc protector 6, a distance L8 is defined between this arc protector 6 and the reduced section 46A located opposite, which is at a distance, measured parallel to axis A2, between the front face 62 of this arc protector 6 and the nearest to the edge lines 70 of the opposite reduced section 46A. For each arc protector 6, a layer of adhesive 72 is interposed between the inner face 66 and the opposite face of the fuse blade 4, to fix this arc protector 6 onto the fuse blade 4. In other words, each arc protector 6 is glued to the fuse blade 4. To ensure that each arc protector 6 is properly secured to the fuse blade 4, each inner face 66 is preferably flat. When the two arc protectors 6 of the same pair 60 are attached onto the fuse blade 4, the inner faces MA / a / ZUZJ / UUl 114 of the 6 arc protectors of the same pair 60 overlap each other. Each layer of adhesive 72 is preferably a thin layer, i.e., a thickness between 10 mm and 0.5 mm, preferably less than 0.1 mm. Each layer of adhesive 72 is preferably uniform, i.e., the adhesive layer 72 has a constant thickness over the entire inner face 66. According to the examples, the adhesive layer 7 2 is applied directly to the fuse blade 4, then the arc shield 6 is placed on the fuse blade 4 and then left to rest while being held motionless to allow the adhesive to harden. Preferably, the inner face 66 of an arc protector 6 is pre-bonded; that is, the adhesive layer 72 is applied directly to the inner face 66 of an arc protector 6. The pre-bonded arc protector 6 is then placed onto the fuse blade 4 and left to rest while being held immobile, for example, by a device such as a clamp, to allow time for the adhesive to harden. The clamp is not shown. Depending on the composition of the adhesive layer 72, the bonding of the arc protector 6 to the surface of the fuse blade 4 can be instantaneous. By instantaneous, it is understood that the hardening of the adhesive layer 72 takes only a few seconds, for example, less than 10 seconds, which is very short compared to the curing time of an uncured silicone material. The adhesive layer 72 is applied, for example, by spraying. Alternatively, the adhesive layer 72 can be a double-sided adhesive, meaning that the adhesive layer comprises a substrate such as a blade, made of paper or an insulating polymer, which has both sides coated with a respective adhesive film. The use of the double-sided adhesive allows for easy mounting of fuse 2. During use, a fuse 2 heats up due to the electric current flowing through it, and this fuse 2 can reach a temperature exceeding 100 °C, for example, between 150 °C and 200 °C, for several months or even several years. The adhesive used to attach the arc protectors 6 to the fuse blades 4 is selected to withstand these operating conditions. Furthermore, when the fuse 2 blows and an electric arc occurs, the adhesive may be exposed to an electric arc. The adhesive is selected so that it does not cause an exothermic reaction when subjected to an electric arc. By way of non-limiting examples, the adhesive is an inorganic adhesive, such as a silicone adhesive, or an organic adhesive, such as a cyanoacrylate adhesive, an epoxy adhesive, or even a vinyl or acrylic adhesive, or aphiphatic, or polyurethane, or neoprene adhesive, etc. Depending on the type of adhesive used, surface activation may be necessary, for example, on the inner face 66 of the arch protectors 6. The following schematically describes the operating principle of a fuse blade 4 comprising arc protectors 6 arranged in the vicinity of the reduced section 46A. When this fuse blade 4, connected to a circuit, is traversed by excessive electric current, the reduced section 46A melts and an electric arc appears in the reduced section 46A. As long as this arc exists, electric current continues to flow through the fuse blade 4, the material of the fuse blade 4 continues to melt, and the arc continues to propagate away from the reduced section 46A. As the arc length increases, the arc voltage increases. Finally, when the arc voltage reaches a value higher than the circuit voltage, the arc is extinguished, and no more electric current flows through the fuse blade 4.The time between the moment the electric arc appears and the moment the arc is extinguished defines a fuse cutting time. In the context of the present invention, the two arc protectors 6 of a pair 60 create a confinement zone between them, which channels the ionic products generated by the arc as the arc propagates. The progression of the electric arc is thus channeled in a preferred direction, which is parallel to the axis A2, moving away from the reduced section 46Ά. The progression of the arc thus channeled is faster than in the absence of an arc protector 6, as is the case in the prior art. As the arc grows faster, the arc voltage also increases faster, and the instant of arc extinction is reached more quickly. Thanks to the arc protectors 6, the cutting time of the fuse blades 4 is shorter. In other words, the cutting time of a fuse 2 comprising arc protectors 6 on both sides of the reduced sections 4 6A is faster. Provided the arc has not reached the arc guards 6, the arc progression speed is not appreciably influenced by the arc guards 6; that is, the arc progression speed is similar to what occurs in the absence of an arc guard. If the arc guards 6 are too far from the reduced section 46A, the effect of the arc guards 6 is unnecessarily delayed. Conversely, if the arc guards 6 are too close to the reduced section 46A, when an arc occurs, the heat released by the arc is excessive and risks damaging the arc guard material 6, for example, through carbonization. Similarly, during normal operation, the reduced section 46A heats up more than the other parts of the fuse blades 4. If the arc guards 6 are too close to the reduced section 46A, they may age more rapidly, particularly hardening, which is undesirable for the reasons explained later in this description. Therefore, the distance L8 between the arc guards 6 and the edge line 70 of the reduced section is between 1 mm and 15 mm, preferably between 3 mm and 10 mm, and more preferably between 4 mm and 8 mm. A distance L8 of 6 mm yields good results. For the confinement effect of the arc protectors 6 to be significant and to prevent the arc from bypassing the arc protector 6, the arc protector 6 must have a sufficient thickness L7. Therefore, each arc protector 6 has a thickness L7 greater than 0.2 mm, preferably greater than 0.5 mm, and more preferably greater than 1 mm. A thickness L7 of 2 mm yields good results. The thickness L7 is not limited, except, for example, for practical space reasons, particularly during the mounting of fuse 2. Thus, the thickness L7 is less than 20 mm, preferably less than 10 mm, and more preferably less than 5 mm. So that the elected confinement of the MA / a / ZUZJ / UUl 114 arc protectors 6 is significant, it is also necessary that the electric arc can be channeled for a sufficient length so that the arc voltage reaches the circuit voltage before the arc emerges from the back side 64 of the arc protectors 6. If the length L6 of the arc protectors 6 is too short, the electric arc will emerge from the back side 64 of the arc protectors 6 and then continue to progress at a rate similar to what happens in the absence of an arc protector. Thus, each arc protector 6 has a length L6 greater than 5 mm, preferably greater than 7 mm. The length L6 is not limited, except, for example, for practical space reasons. Thus, the length L6 is less than 30 mm, preferably less than 25 mm, and more preferably less than 20 mm. The hardness of the elastic material of the arc protectors 6 has a significant influence on reducing the breaking time of the fuses 2. The elastic material of the arc protectors 6 has a hardness evaluated on a scale called Shore A, which ranges from 0 for a very soft material to 100 for a very hard material. The confinement effect of a material that is too soft, with a Shore A hardness of less than 20, is insufficient. A hardness greater than 40 is preferred. Conversely, a 6-inch arch protector made of a MA / a / ZUZJ / UUl 114 Excessively hard material also does not offer good performance. The material for arc protectors 6 is therefore chosen with a Shore A hardness of less than 90. On the other hand, under the operating conditions of a fuse 2, arcs 6 are subjected to temperatures that can exceed 100 °C or 150 °C, and elastomers tend to harden over time. The material for arc protectors 6 is therefore chosen so that its Shore A hardness remains below 90 even after aging. Thus, the Shore A hardness of the new material for arc protectors 6 is preferably chosen to be less than 70. Thus, the 6 arch protectors are made of a material that has a hardness, measured on a Shore-A scale, between 20 and 90, preferably between 40 and 70. Surprisingly, the mechanical compression state of the arc protectors 6 positively influences the reduction of the cutting time of the fuses 2. Advantageously, when the fuse 2 is mounted, the arc protectors 6 are slightly compressed in a direction parallel to the axis A4, i.e., orthogonal to the main faces of the blades 4 of the fuse at the location of these arc protectors 6. When the fuse 2 is assembled, each arc protector 6 is compressed and has a thickness L7 less than 99% of the thickness L7 of this same arc protector 6 when this arc protector 6 is not subjected to any external stress, preferably less than 98%, more preferably less than 95%. The compression of the arch protectors 6 of the same pair is carried out by means of specific devices, such as compression clamps, and / or by means of the frame 48 when present, for example through the shims 5 8. The compression clamps are not shown. When clamping clamps are used during assembly to immobilize the arc protectors 6 and allow time for the adhesive to harden, these clamping clamps also advantageously serve as compression clamps and are left in place on the arc protectors 6 once the adhesive layer 72 has hardened. Figures 4A-4B, 5A-5B, and 6A-6B, respectively, show the fuse blade 4 and arc protectors 6 according to the second, third, and fourth embodiments of the invention, while Figures 9 to 10B show a fuse blade 4 and arc protectors 6 according to a fifth embodiment of the invention. Elements similar to those of the first embodiment bear the same part numbers and function in the same manner. The main differences between each embodiment and the preceding one(s) are described below. One of the main differences between the second embodiment, shown in Figures 4A and 4B, and the first embodiment is that at least one perforation 80 is made in the fuse blade 4 on each side of the reduced section 46A, i.e., on each side of the transverse plane P4. In the first embodiment, the perforations 80 are covered by the arc shields 6; that is, as long as the fuse 2 has not blown, the perforations 80 are completely sealed in the direction of axis A4 by the inner faces 66 of the arc shields 6. The same fuse blade 4 is shown in Figures 4A and 4B. Figure 4B represents a section of the fuse blade 4 of Figure 4A along a section plane 4b on Figure 4A. The perforations 80 reduce the amount of material to be melted during the progression of the electric arc, once the arc reaches the front face 62 of the arc protectors 6. The arc progression is thus faster than in the first embodiment of the invention, as illustrated in Figure 7. The perforations 80 are not obstructed, in the direction parallel to the axis A2 of the fuse 2, by the adhesive layers 7 2 or by the arc protectors 6, so as not to impede the progression of the electric arc. Advantageously, the perforations 80 are each elongated and arranged along their length parallel to the axis A2 of the fuse 2, that is, parallel to the longitudinal direction of the fuse blade 4. Schematically, the elongated perforations 80 provide channels, parallel to the longitudinal axis A2, that facilitate the progression of the electric arc. In the second embodiment of the invention, each perforation 80 has a length, measured parallel to the longitudinal axis A2 of the fuse 2, substantially equal to the length L6 of the arc protectors 6 that close this perforation 80. The perforations 80 made on one side of the transverse plane P4 are preferably symmetrical to the perforations 80 made on the other side of the transverse plane P4. The perforations 80 located on the same side of the transverse plane P4 form a group of perforations 80. In the first embodiment, the perforations 80 of the same group are thus completely enclosed by the inner faces 66 of the two arch protectors 6 of the same pair 60. In the illustrated example, each group of 80 perforations comprises three 80 perforations; this number is not limiting. Alternatively, each group of 80 perforations may comprise a single 80 perforation, or two, or even four or more. The perforations 80 of the same group are preferably arranged in rows, i.e., aligned with each other in a direction transverse to the fuse blade 4, i.e., in a direction orthogonal to axis A2. In the example illustrated in Figure 4A, the perforations 80 have a rectangular cross-section. In non-limiting variations, the perforations 80 are oval, elliptical, rhomboid, or, more generally, oblong. The shape of the perforations 80 depends in particular on the manufacturing method, which may include, but is not limited to, stamping, laser cutting, or electro-erosion. Perforations 80 within the same group preferably each have the same shape. For each group of perforations 80, the more numerous the perforations 80 are and the more significant their width (measured parallel to the transverse direction of the fuse blades 4), and the greater the electrical resistance (measured parallel to the axis A2 of the fuse 2), the greater the passage through this group of perforations 80. However, unlike the reduced sections 46 or 46A, the perforations 80 are not intended to promote the initiation of an electric arc in the event of an overcurrent, but rather to provide passages that favor the progression of the arc until it reaches the arc protectors 6. For each fuse blade 4, the surface section of a group of perforations 80, measured along the longitudinal axis of this fuse blade 4, is five times larger, preferably ten times larger, than the smallest surface section among the reduced surface sections 46 or 46a provided in this fuse blade 4. The perforations 80 of the same group are preferably regularly spaced in the transverse direction of the fuse blade 4, to avoid locally weakening the fuse blade 4 material or to avoid creating a hot spot when current flows in the fuse blade 4. One of the main differences between the third mode, shown in Figures 5A and 5B, and the second mode is that the perforations 80 protrude from the arc protectors 6 on the side opposite the reduced section 46A. The same fuse blade 4 is shown in Figures 5A; Figure 5B represents a section of the fuse blade 4 of Figure 5A along a plane of the section 5b in figure 5A. Each perforation 80 extends parallel to the longitudinal axis A2 of fuse 2, beyond the rear face 64 of the neighboring arc protectors 6. Each perforation 80 thus comprises a rear portion, located on the side opposite the reduced section 46A, which protrudes from the rear face 64 and forms a rear ventilation grille 82, through which the perforation 80 opens. When an arc advances between arc protectors of the same pair 60, the rear ventilation grilles 82 allow for faster evacuation of arc-generated products, particularly molten metal or other baked-on products. This rapid removal of these products destabilizes the arc, leading to a reduction in the time required to achieve complete current interruption. For each perforation 80, a length L82 is defined as a length, measured parallel to the longitudinal axis A2 of the fuse 2, between an end of this perforation 80 furthest from the reduced section 4 6A and the rear face 64 of the adjacent arc protector 6. The length L82 thus represents a length of a rear ventilation grille 82. The length L82 is between 0.1 mm and 10 mm, preferably between 0.5 and 8 mm, more preferably between 1 mm and 5 mm. Thus, in the third modality, the perforations 80 of the same group are partially obturated by the internal faces 66 of the two arch protectors 6 of the same pair 60. One of the main differences between the fourth mode, shown in Figures 6A and 6B, and the third mode is that the perforations 80 protrude from the arc guards 6 on the side that is turned toward the reduced section 46A. The same fuse blade 4 is shown in Figures 6A and 6B, Figure 6B showing a section of the fuse blade 4 from Figure 6A along a cut plane 6b in Figure 6A. Each perforation 80 extends parallel to the longitudinal axis A2 of the fuse 2, beyond the front face 62 of the arc protectors 6. Each perforation 80 thus comprises a front portion, located on the side of the reduced section 4 6A, which protrudes from the front face 62 and forms a front ventilation grille 84, through which the perforation 80 opens. Thus, in the fourth embodiment, the perforations 80 of the same row are partially closed by the inner faces 66 of the two arc protectors 6 of the same pair 6 0. When an arc advances towards the arc protectors 6 of the same pair 60, the front ventilation grilles 84 allow some of the molten metal or other ionized products generated by the arc in the vicinity of the reduced section 4 6A to be evacuated, filling the cavity V20 with sand. These ionized products no longer contribute to maintaining the arc. For each perforation 80, a length L84 is defined as a length, measured parallel to the longitudinal axis A2 of fuse 2, between one end of this perforation 80 closest to the reduced section 4 6A and the front face 62 of the adjacent arc protector 6. The length L84 thus represents a length of one of the front ventilation grilles. 84. The length L84 is between 0.1 mm and 5 mm, preferably between 1 and 3 mm. Figure 7 represents a graph 700 illustrating the evolution of an electric current passing through a fuse blade 4 comprising a reduced section 4 6A for different fuse blades 4 with different characteristics. The performance of a fuse 2 is evaluated in particular by its breaking time, which is the time required for the electric current to be canceled once the melting of the reduced section 46A begins. Curve 99 illustrates the evolution of the current in the case where the fuse blade 4 does not include an arc protector in the vicinity of the reduced section 46A. An electric arc appears at time t0. The current is zero at time t. The breaking time is equal to t V-t0. Curve 100 illustrates the evolution of the current in a case where the fuse blade 4 comprises arc protectors 6 according to the first embodiment of the invention described below, i.e., two pairs 60 of the arc protectors 6 are arranged on each side of the reduced section 4 6A. The current is zero in a time t00. The cutting time of a fuse blade 4 that includes an arc protector 6, equal to t00, is approximately 40% less than the cutting time of a fuse blade 4 without an arc protector. Curve 200 illustrates the evolution of the current in a case where the fuse blade 4 comprises arc protectors 6 according to the second embodiment of the invention described above, i.e., the perforations 80 are made in the fuse blade 4 between the arc protectors 6 of the same pair 60. The current is zero at an instant t2oo- The breaking time of a fuse blade 4 comprising arc protectors 6 with perforations, equal to t2oo - t2, is approximately 4 5% less than the breaking time of a fuse blade 4 without an arc protector. Curve 300 illustrates the evolution of the current in a case where the fuse blade 4 comprises arc protectors 6 according to the third embodiment of the invention described above, i.e., the perforations 80 protrude from the arc protectors 6 on the side opposite the reduced section 4 6A. The current is zero at a taco- instant. The cutting time of a fuse blade 4 comprising arc protectors 6 with perforations and rear ventilation grilles 82, equal to tgoo - to, is approximately 50% less than the cutting time of a fuse blade 4 without an arc protector. Curve 400 illustrates the evolution of the current in a case where the fuse blade 4 comprises MA / a / ZUZJ / UUl 114 arc protectors 6 according to the fourth embodiment of the invention described above, i.e., the perforations 80 protrude from the arc protectors 6 both on the side of the reduced section 4 6Ά and on the side opposite the reduced section 4 6A. The current is zero at an instant t4oo- The cutting time of a blade 4 of the fuse comprising arc protectors 6 with perforations 80 and front 84 and rear 82 ventilation holes, equal to t4oo-to, is approximately 60% less than the cutting time of a blade 4 of the fuse without an arc protector. Figure 7 illustrates an aspect of the improved performance, measured by the reduction in breaking time, of the fuses 2 according to the invention, compared to the fuses according to the prior art. The fuses 2 according to the second, third, and fourth embodiments of the invention, in which the perforations 80 located on the same side of the reduced section 46A are at least partially blocked by the arc protectors 6 of the same pair 60, make it possible to further improve the performance of the fuse 2 compared to the first embodiment of the invention. In the illustrated example, the perforations 80 are made on each side of the reduced section 46A. In an unillustrated variant, one or more perforations 80 are made on one side of the reduced section 46A, in the vicinity of this reduced section 46A, at least one perforation 80 also contributing to the extinguishing of the electric arc. In the illustrated example, the arc protectors 6 are arranged only on either side of the reduced section 4 6A located in the middle of a fuse blade 4 to explain the invention. Of course, when the fuse blade 4 comprises reduced sections 46 other than the reduced section 46A, other arc protectors, of the arc protector type 6, may be placed, if necessary, near these reduced sections 46. According to an unrepresented variant, the two pairs of arcs 6 are separated from each other by two, or even more, reduced sections of the type of reduced sections 46 and / or 46A. As described above, the perforations 80 and arc protectors 6 have shapes with precise dimensions; these dimensions can change in particular depending on the sizing and rating of the fuse 2, and the size of the holes 44 of the reduced section 46A. In the illustrated example, the pair of arc protectors 6 is mounted on a flat part of the fuse blade 4. In a variant not shown, where the fuse blade 4 has folds, such as the transverse folds 42, the folds form pleats with various profiles, such as a flat surface, a groove, etc. The arc protectors 6 can be placed directly into a fold, for example a crease or a groove, thus allowing the net length of the fuse blades 4 to be shortened. The manufacturing method for fuse 2, described in particular with the aid of Figure 8, thus comprises a step 800 consisting of manufacturing two arc protectors 6 from a first pair 60, the arc protectors 6 being made of a preformed elastic material, in particular a cross-linked elastomer, and each having a flat inner face 66. By way of non-limitation, the arc protectors 6 are manufactured, for example, by molding, the inner face 66 being optionally ground by machining. By another example, they are manufactured, for example, by calendering, from a calibrated strip of elastic material having a width equal to the width of the fuse blades 4 onto which the arc protectors 6 are to be bonded, the strip having a thickness equal to the thickness L7 of the arc protectors 6. The arc protectors 6 are then cut from this calibrated strip.One or more of the faces of the arc protectors 6 can be machined to correct their geometry, in particular the inner face 66, which is preferably flat to promote the adhesion of the adhesive layer 72, and the front face 62, oriented towards the reduced section 46A. The method then comprises a step 802 which consists of gluing each arch protector 6 of the same pair 60 MA / a / ZUZJ / UUl 114 on a respective main face of the fuse blade 4 in the vicinity of the reduced section 4 6A, by interposing a layer of adhesive 7 2 between the inner face 66 of each arc protector 6 and a respective main face of the fuse blade 4. The arc protectors 6 are located on the same side of the transverse plane P4, the front faces 62 of the arc protectors 6 being oriented towards the reduced section 4 6A, so that the distance L8 between the front face 62 of each arc protector 6 and the nearest edge line 70 is between 1 mm and 15 mm. When perforations 80 are made in the fuse blades 4, the manufacturing method comprises a step 804, prior to the bonding step 802, consisting of providing at least one perforation 80 in the fuse blade 4 in the vicinity of the reduced section 46A. During the bonding step 804, arc protectors 6 are placed on the fuse blade 4 so that the perforations 80 are essentially closed by the arc protectors 6. When the perforations 80 are longer than the length L6 of the arc protectors 6, front vents 84 and / or rear 82 are provided. The fifth mode of the fuse blade 4 and arc protectors 6, shown in Figures 9 and 10, resembles the fourth mode in that the perforations 80, formed in the vicinity of the reduced section 46A, 1114 protrude from the front 62 and rear 64 faces of the arc protectors 6, to form the front 84 and rear 82 ventilation grilles respectively. Each of the perforations 80 is at least partially closed by the inner faces 66 of the two arc protectors 6 of the same pair 60, leaving each perforation 80 a gap between the two arcs 6 of the same pair 60. As in other embodiments, the arc protectors 6 of the fourth embodiment are made of an elastic material, here silicone, which are associated in pairs 60 and are fixed onto the fuse blade 4 by means of an adhesive layer 72, which is interposed between the fuse blade 4 and an inner face 66 of each arc protector 6 of the corresponding pair 60. Among the main differences between the fuse blade 4 and the arc guards 6 of the fifth modality compared to the previous modalities, the perforations 80 are elongated ellipses, extending along their length parallel to the longitudinal axis Ά2 of the fuse 2. Furthermore, the fuse blade 4 here has folds 86 on the front 62 and rear 64 faces of the arc guards 6. In the illustrated example, the folds 86 are located in a plane parallel to the transverse plane P4. The front vents 84 and rear 82 extend over these folds 86. Thus, the front vents 84 are oriented towards the reduced section 46Ά. In the illustrated example, the rear vents 82 of each pair 60 of the arc guards 6 are oriented towards their respective reduced sections 46.According to the naming conventions used in this description, the rear ventilation grilles 82, with respect to the reduced section 46A, are therefore front ventilation grilles with respect to one of the reduced sections 46. Such a fuse blade 4 structure, comprising 86 folds, allows for a more compact structure compared to a fuse blade 4 without folds. In all the illustrated embodiments, the arch protectors 6 are made of a preformed elastic material, particularly an elastomeric material such as silicone. Optionally, the arch protectors 6 may comprise mineral and / or organic particles, which are added to the elastic material in the form of powder and / or fibers. These particles serve to adjust the material properties of the arch protectors 6, for example, to adjust the Shore hardness of the material, and / or to provide mechanical reinforcement. The material of the arch protectors 6 is therefore a reinforced material, also called a composite material, comprising a matrix manufactured from an elastic material, particularly an elastomeric material such as silicone. Unlike a reinforced material, a material without added particles is called raw material. According to an unshown variant, the arch protectors are made of an elastic foam material, i.e., a material containing gas bubbles and having an average porosity greater than 50%, preferably greater than 60%, and more preferably greater than 70%. The average porosity of a part is defined as the fraction of the volume of gas bubbles contained in that part relative to the total volume of that part. According to another variant not shown, arch protectors 6 are composed of several layers of materials stacked on top of each other. At least one of the layers is made of an elastic material as described above, specifically an elastomeric material such as silicone. Based on the examples, these layers have distinct characteristics, particularly different hardness characteristics, and these material layers are advantageously bonded together. Many other options are possible. In particular, the features of the fuse blade 4 and the arc guards 6 according to the invention, and in particular the structural features of the arc guards and their method of manufacture, can be implemented independently of the body 20 comprising a frame 48 described above and could be implemented in MA / a / ZUZJ / UUl 114 a conventional fuse body. In particular, the perforations 80 can be used independently of the frame 48. Any feature described for one modality or variant thereof may be implemented for the other modalities and variants described above, to the extent that it is technically feasible. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.
Claims
1. A fuse comprising: - at least one fuse blade, formed in a sheet having two opposite principal faces extending along a longitudinal axis of the fuse blade, each fuse blade comprising a portion in which a reduced section is formed defining a plane transverse to the fuse blade, - two connection terminals, each terminal being connected to each fuse blade, - arc protectors, made of a preformed elastic material, associated in pairs, the arc protectors of the same pair being located opposite each other on a respective principal side of the same fuse blade, characterized in that for at least a first pair of arc protectors, an adhesive layer is interposed between the fuse blade and an inner face of each arc protector of this pair, the inner face being oriented towards one of the principal faces of the fuse blade,so that each arc protector is secured over the fuse blade.
2. The fuse according to claim MA / a / ZUZJ / UUl 114 1, characterized in that the fuse comprises, in addition to the first pair of arc protectors, a second pair of arc protectors, the first and second pairs of arc protectors being separated from each other by at least a reduced section.
3. The fuse according to any of claims 1 or 2, characterized in that each arc protector comprises a front face, oriented towards a reduced section, and a rear face opposite the front face, and wherein the front and rear faces of each arc protector are separated by a length of between 5 mm and 30 mm.
4. The fuse according to claim 3, characterized in that a distance between the front face and an edge line of the opposite reduced section is between 0.5 mm and 20 mm.
5. The fuse according to claim 4, characterized in that the distance between the front face and the edge line of the opposite reduced section is between 1 mm and 15 mm.
6. The fuse according to claim 4, characterized in that the distance between the front face and the edge line of the opposite reduced section is between 2 mm and 12 mm.
7. The fuse according to any of claims 1 or 2, characterized in that each arc protector comprises an outer face, opposite the inner face, and each arc protector has a thickness, defined as a distance separating the inner face from the outer face, between 0.2 mm and 20 mm.
8. The fuse according to any of claims 1 or 2, characterized in that the arc protectors are manufactured from an elastomeric material, which has a hardness, measured on a Shore-A scale, of between 20 and 90.
9. The fuse according to claim 8, characterized in that the arc protectors are manufactured from an elastomeric material, which has a hardness, measured on a Shore-A scale, of between 40 and 70.
10. The fuse according to any of claims 1 or 2, characterized in that the arc protectors are made of silicone.
11. The fuse according to any of claims 1 or 2, characterized in that on one side of the reduced section of the fuse blade there is at least one perforation made, each of such perforations being enclosed at least partially by the internal faces of the two arc protectors of the same pair.
12. The fuse according to claim 11, characterized in that the perforations extend parallel to the longitudinal direction of the fuse blade beyond the rear face of the arc guards, so as to form rear ventilation grilles.
13. The fuse according to claim 12, characterized in that the rear ventilation grilles have a length between 0.1 mm and 10 mm.
14. The fuse according to claim 13, characterized in that the rear ventilation grilles have a length between 0.5 and 8 mm.
15. The fuse according to claim 14, characterized in that the rear ventilation grilles have a length between 1 mm and 5 mm.
16. The fuse according to claim 11, characterized in that the perforations extend parallel to the longitudinal direction of the fuse blade beyond the front face of the arc guards to form front ventilation grilles, and in that the front ventilation grilles have a length of between 0.1 mm and 5 mm.
17. The fuse according to claim 16, characterized in that the front ventilation holes fill a length of between 1 and 3 mm.
18. The fuse according to any of claims 1 or 2, characterized in that it comprises a frame housed in a cavity of a fuse body and which limits the movements of the fuse blades relative to the body by means of spacers and / or shims.
19. The fuse according to any of claim 1 or 2, characterized in that when the fuse is mounted, the arc protectors are compressed orthogonally to the main faces of the fuse blade, each arc protector having a thickness less than 99% of the thickness of the same arc protector when this arc protector is not subjected to any external stress.
20. The fuse according to claim 19, characterized in that when the fuse is assembled, the arc protectors are compressed in the direction orthogonal to the main faces of the fuse blade, each arc protector having a thickness less than 98% of the thickness of the same arc protector when this arc protector is not subjected to any external stress.
21. The fuse according to claim 20, characterized in that when the fuse is assembled, the arc protectors are compressed in a direction orthogonal to the main faces of the fuse blade, each arc protector having a thickness less than 95% of the thickness of the same arc protector when the arc protector is not subjected to any external stress.
22. A method of manufacturing a fuse according to any of claim 1 or 2, the fuse comprising at least one fuse blade of reduced section defining a plane transverse to the fuse blade; characterized in that it comprises the steps of: - manufacturing two arc protectors of a first pair, the arc protectors being manufactured from an elastic reticulated material and having a flat inner face, - gluing each arc protector of the first pair to a respective main face of the fuse blade in the vicinity of the reduced section, interposing a layer of adhesive between the inner face of each arc protector and a respective main face of the fuse blade, such that a distance between a front face of each arc protector and a line of the edge of the opposite reduced section is between 1 mm and 15 mm. 2 3. The manufacturing method according to claim 14, characterized in that it comprises a step, prior to the gluing step, consisting of providing in the fuse blade at least one perforation on each side of the transverse plane, and wherein, during the gluing step, the arc protectors of the first pair are glued to the fuse blade in such a way that each perforation is at least partially blocked by the arc protectors.