Fuse

Abstract

This fuse (100) comprises a housing with a metal cooling wall (120) which bounds an internal space of the housing. The fuse also comprises a fusible link (130) which is accommodated in the internal space and comprises a main portion, which portion is made in one piece and comprises two ends (132A, 132B) between which a first, reduced section (136) is made. The main portion comprises at least one support (142) via which the main portion is attached to the wall (120), so as to hold the reduced section (136) away from the wall (120). The fuse also comprises a spacer (140) which is inserted between each support and the wall, each spacer (140) comprising a central layer (144) which comprises two opposite faces (146A, 146B) which are electrically insulated from one another, and two connecting layers (152) which are applied to a respective face of the central layer. One of the connecting layers is attached to the wall, while the other connecting layer is attached to each support.

Description

[0001] The present invention relates to a fuse.

[0002] A fuse, sometimes also called a "fuse cartridge," is an electrical component with two terminals that, in the event of an overcurrent exceeding a limit known as the fuse rating, interrupts the flow of electric current between the two terminals. The two terminals are fixed to an insulating body with a cavity and are electrically connected to each other via at least one fusible element, located within the cavity of the insulating body. One or more fusible elements may be connected in parallel to the two terminals, depending on the fuse's rating. The information described for one fusible element is applicable to the other fusible elements when there are several.

[0003] A fusible blade is made of a conductive material with a given electrical resistance and melting point. When an electric current flows through the fusible blade, it heats up due to the Joule effect. Under normal operating conditions, the temperature of the fusible blade remains below its melting point. In the event of an overcurrent, the temperature of the fusible blade rises and exceeds its melting point at one or more points, causing it to melt at least partially, and the current flow is irreversibly interrupted. The fusible blade includes, between the connections to the two poles, at least one intermediate section with a reduced cross-sectional area. This intermediate section is called a "reduced section." Each reduced section offers greater resistance to the flow of current 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 melts preferentially at a reduced section.

[0004] When a small section melts, an electric arc is created, and a 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 fusible element. Along with the thermal and electrical conditions, this change in the material's state in the fusible element, in turn, promotes the maintenance and extension of the electric arc. The cavity is generally filled with a material that facilitates arc extinction, usually sand, in order to reduce the fuse's breaking time.

[0005] For certain high-power applications, particularly for electric vehicle charging, fuses must have a high rating to reduce charging time while minimizing short-circuit leakage current when the fuse blows. This is also referred to as PLTC current – ​​for “ Peak Let Through Current » In English, the PLTC current is related, among other things, to the fuse's breaking time. In the case of vehicle charging, if the charging system malfunctions, the lower the PLTC current, the lower the risk of a vehicle fire. Therefore, it is necessary to use a fuse that offers the highest possible current rating to reduce charging time while maintaining the lowest possible PLTC current.

[0006] The PLTC current is limited by certain standards, such as ISO 17409:2020, which relates to electric vehicle charging. For example, according to this standard, for vehicle charging at 1000 V with a nominal current of 1000 A, the permissible PLTC current limit is 30 kA. However, such performance is not achievable with conventionally designed fuses.

[0007] One known approach to improving fuse performance is to cool the fuse blade, in order to dissipate the heat generated by the Joule effect when current passes through the fuse blade.

[0008] WO-2012 025853-A1 describes, for example, a fuse with a housing comprising a cooled wall made of electrically insulating ceramic. The fuse element is formed from multiple components bonded directly to the cooled wall. Such a fuse is, however, difficult to manufacture, as each component of the fuse element is individually attached to the wall. The ceramic wall, which remains relatively thin to avoid hindering heat transfer, is also relatively fragile and prone to breakage, particularly in the event of an impact or due to temperature differences between its two faces.

[0009] EP0292225A2 describes a fuse with a metallic wall onto which a ceramic plate is laminated. A metallic circuit is formed directly on one inner face of the plate to create the fuse element. However, this structure is not suitable for fuse elements with multiple small cross-sections. Furthermore, when the fuse is filled with sand, the sand is only present on one side of the fuse element. Such a fuse cannot effectively interrupt, with a short breaking time, overcurrents involving high energy levels, such as those encountered during vehicle charging.

[0010] It is these problems that the invention aims to address in particular, by offering a fuse that is robust and efficient.

[0011] To this end, the invention relates to a fuse, comprising: a casing, the casing comprising a wall which is made of metal and which delimits an internal volume of the casing, the wall being configured to be cooled from the outside of the casing, and a fusible blade, which comprises: a main portion, which is made of a single piece, which is received in the internal volume and which includes two opposite ends, and a reduced section, which is provided in the main portion between the two end areas.

[0012] According to the invention: The main portion includes at least one support, by which the main portion is fixed to the wall; the fuse includes a spacer, which is interposed between each support and the wall; each spacer includes: a central layer, which includes two opposite faces electrically insulated from each other, and two bonding layers, which are each made of a bonding material and which are applied to a respective face of the central layer; one of the bonding layers being fixed to the wall, while the other bonding layer is fixed to each support; each support is arranged so as to keep the reduced section away from the wall.

[0013] Thanks to the invention, the casing wall, which cools the fuse during use, is made of metal and is therefore resistant to shocks and thermal cycling. The fusible element is bonded to the metal wall while remaining electrically insulated from it, whereas the reduced cross-section is kept away from the metal wall. When the reduced cross-section melts, the electric arc extends on both sides of the fusible element. Advantageously, when the fuse is assembled, the casing is filled with a material that promotes arc extinction, such as sand. This sand is located on both sides of the reduced cross-section, contributing to effective arc extinction should the reduced cross-section melt.

[0014] 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 permissible combination: The main portion comprises two reduced sections, while the main portion provides an intermediate support, which is arranged between the two reduced sections and fixed to the wall by means of a spacer. The fusible blade is formed so as to keep the reduced sections associated with the intermediate support at a distance from the wall. The fusible blade includes at least one support arranged so that this support is located outside the conduction path of the fusible blade when a current flows through the fusible blade. At least one of the supports among the end supports and the intermediate support includes at least one bearing tab, each bearing tab being formed by cutting the fusible blade and having an elongated shape with a first end, which is connected to the fusible blade, and a second end, which is opposite the first end and fixed to the wall by the corresponding spacer.For at least one support bracket, this bracket is cut near a reduced section, the cut forming a perforation for this reduced section. The support is formed by folding a folding zone of the main portion, the folding zone extending along a length of the main portion and comprising two end zones and an intermediate zone located between the two end zones, while the intermediate zone is folded to form the support, and the two end zones are in electrical contact with each other. For at least one of the reduced sections of the main portion, the main portion comprises two supports associated with this reduced section, while an insulating element is interposed between this reduced section and the wall, and the insulating element closes, at least partially, a gap between the two intermediate supports associated with this reduced section.For at least one of the reduced sections of the main portion, the main portion comprises two adjacent supports associated with that reduced section, while for the two spacers associated with these two supports, the central layer of the two spacers is made in one piece, so as to close a gap between these two supports. The central layer is made of an electrically insulating polymer material. The central layer is made of ceramic. Pads are interposed between each spacer and the fusible blade to increase the distance between each reduced section and the wall. The wall includes projections, which are formed on the surface of the wall and arranged opposite each spacer, so as to increase the distance between each reduced section and the wall.The enclosure comprises, in addition to the wall, a complementary portion of the wall: the complementary portion is made of an insulating material and, together with the wall, delimits the internal volume of the enclosure; for at least one of the reduced sections, the complementary portion of the enclosure comprises at least two projections, which extend within the internal volume and which are arranged on either side of this reduced section, so as to limit the propagation of electric arcs in the internal volume when this reduced section melts.

[0015] The invention will be better understood, and other advantages thereof will become more apparent, in light of the following description of several embodiments of a fuse, conforming to its principle, given solely by way of example and with reference to the accompanying drawings, in which: [ Fig 1 ] there figure 1 is viewed in perspective of a longitudinal section of a fuse conforming to a first embodiment of the invention; [ Fig 2 ] there figure 2 represents respectively, on two inserts a) and b), a perspective view of a section, along a longitudinal plane II to the figure 1 , of a subset of the fuse of the figure 1 , and a detail of this subset; Fig 3 ] there figure 3 schematically represents, on four inserts a) to d), a front view of the subset of the figure 2 and a front view of three sub-assemblies, each belonging to a fuse according to other embodiments of the invention; [ Fig 4 ] there figure 4 schematically represents, on four inserts a) to d), a front view of four sub-assemblies, each belonging to a fuse conforming to other embodiments of the invention; Fig 5 ] there figure 5 represents, on two inserts a) and b), two manufacturing steps of a fusible blade belonging to a fuse according to another embodiment of the invention; [ Fig 6 ] there figure 6 represents, on two inserts a) and b), details of two fusible blades each belonging to a fuse according to other embodiments of the invention; [ Fig 7 ] there figure 7 represents respectively, on two inserts a) and b), a detail of a fusible blade and a subassembly, each belonging to a fuse conforming to other embodiments of the invention; [ Fig 8 ] there figure 8 represents respectively, on two inserts a) and b), two fuses conforming to other embodiments of the invention, and [ Fig 9 ] there figure 9 is a cut of a fuse according to another embodiment of the invention.

[0016] A fuse 100, conforming to a first embodiment of the invention, is shown in the figure 1 Fuse 100 comprises a housing 110 and two connection terminals 112.

[0017] The housing 110 generally has an elongated cylindrical shape defining a longitudinal axis X100 of the fuse 100. By extension, the reference X100 also designates a longitudinal direction, which is oriented from left to right in the figures.

[0018] In the illustrated example, the housing 110 has a generally parallelepiped shape, meaning that it is cylindrical with a rectangular cross-section. The housing 110 is hollow, meaning that it encloses an internal volume V110. In the following description, the terms "top," "bottom," etc., refer to the orientation of the various components of fuse 100 in the drawings, bearing in mind that fuse 100 may be oriented differently in reality.

[0019] The housing 110 includes a wall 120, which is configured to be cooled externally. In normal operation of the fuse 100, the wall 120 is fixed against a cooling device, for example, a metal support with channels for cooled fluid. The cooling device is not shown.

[0020] Wall 120 is here a lower wall of the housing 110. Wall 120 is made of a material with good thermal conductivity, while also being resistant to the stresses of use of the fuse 100, particularly impacts. Wall 120 is made of metal, preferably copper or one of its alloys. Wall 120 is formed from a plate and extends parallel to the longitudinal axis X100 and orthogonally to a height axis Z100 of the fuse.

[0021] By extension, the reference Z100 also designates a height direction, which is oriented from the bottom to the top of the figures. A transverse axis Y100 is also defined as an axis orthogonal to both the longitudinal axis X100 and the height axis Z100, the three axes X100, Y100 and Z100 being arranged to form a direct coordinate system.

[0022] In addition to the wall 120, the housing 110 also includes a complementary portion 122, which cooperates with the wall 120, notably through complementary shapes, to delimit the internal volume V110. The complementary portion 122 is made of an electrically insulating material, for example a synthetic polymer such as polyamide, and is manufactured, for example, by hot injection molding. The two connection terminals 112 are accessible from outside the housing 120, in this case, from outside the complementary portion 122.

[0023] In the illustrated example, the complementary portion 122 is made in two parts: a peripheral portion 122A, which forms a rectangular frame, and a cover 122B, which closes the peripheral portion 122A. The shape of the complementary portion 122 is not limited. In some examples, the complementary portion 122 is concave, while the wall 120, formed from a plate to simplify production, closes the complementary portion 122, delimiting the internal volume V110 of the housing 110.

[0024] In the illustrated example, terminals 112 protrude from the housing 110 through the cover 122B. This arrangement of the connection terminals 112 is not exhaustive. The cover 122B includes openings 124, here in the form of slots arranged parallel to the transverse axis Y100, through which the terminals 112 pass. During normal operation of the fuse 100, the internal volume V110 is generally filled with sand. The sand is not shown. The openings 124 are then sealed to prevent sand leakage, for example, with a sealant, particularly a polysiloxane sealant, also known as silicone.

[0025] Fuse 100 also includes a fusible blade 130, which is received in the internal volume V110. The fusible blade 130 is fixed to the wall 120 to be cooled during the use of fuse 100.

[0026] The fusible blade 130 is made of a conductive material with a given electrical resistance and melting point. The material of the fusible blade 130 is preferably metallic and typically has a thickness between 0.03 mm and 1.0 mm, preferably between 0.06 mm and 0.3 mm. The fusible blade 130 is, for example, made of silver, copper, aluminum, tin, or one of their respective alloys. The fusible blade 130 is formed by perforating, cutting, and / or bending a strip of metal with a constant width, measured parallel to the transverse axis Y100. Alternatively, the fusible blade 130 may have a variable width. The long sides of the metal strip are oriented parallel to the longitudinal axis X100 and form the longitudinal edges of the fusible blade 130.

[0027] The fusible link 130 thus has an elongated shape, extending substantially along the longitudinal axis X100 and comprising two opposing ends 132A and 132B. Each end 132A and 132B is fixed to the wall 120 and forms an end support 132A and 132B for the fusible link 130. By extension, the designations 132A and 132B also refer to the end supports 132A and 132B. Each end support 132A and 132B is electrically connected to a respective connection terminal 112. In the illustrated example, each end support 132A and 132B is fixed to the wall 120 by means of a respective spacer 140. The spacers 140 are described in detail later.

[0028] The fusible blade 130 also includes a main portion 134, which is interposed between the two end supports 132A and 132B. The main portion 134 is here made of a single piece. The main portion 134 here comprises three reduced sections 136, this number not being limiting. In an alternative not shown, the main portion 134 comprises a single reduced section, or two reduced sections, or even four or more reduced sections.

[0029] Each reduced section 136 is formed by a row of holes, this row being oriented along the transverse axis Y100. Thus, the fusible blade 130 exhibits, at each reduced section 136, a higher electrical resistance than the electrical resistance elsewhere. When an electric current flows between the terminals 112, the fusible blade 130 experiences localized heating at the reduced sections 136. In the event of an overcurrent, the melting of the material of the fusible blade 130 occurs preferentially at the reduced sections 136.

[0030] In the illustrated example, the fusible link 130 comprises three identical reduced sections 136. Consequently, the fusible link 130 exhibits a "breaking time / breaking current" response curve with a given shape. In an alternative (not shown), the fusible link 130 has several types of reduced sections, the holes forming each reduced section having, for example, different diameters depending on the section considered. Thus, when an overcurrent occurs, some reduced sections 136 are likely to melt more quickly than others. By combining different types of reduced sections 46, a response curve is obtained that is the superposition of each of the response curves corresponding to each of the reduced sections. This aspect is not detailed further in this description.

[0031] In the illustrated example, the fusible blade 130 also includes perforations 138, each oblong in shape, arranged in rows 139 on either side of each reduced section 136. Each row 139 here comprises three perforations 138. The fusible blade 130 here comprises six rows 139 of perforations, which are paired with each of the reduced sections 136. The perforations 138, or « blowholes » In English, these perforations reduce the amount of material that needs to be melted during the arc's progression when the fuse melts. This results in a faster arc progression than without perforations 138, ultimately reducing the arc extinction time. The operation of perforations 138 is not described in further detail.

[0032] Between two consecutive reduced sections 136, the fusible blade 130 advantageously provides an intermediate support 142. The fusible blade 130 here comprises two intermediate supports 142. In the first embodiment, each intermediate support 142 is formed by folding the fusible blade 130. Each intermediate support 142 is fixed to the wall 120 by means of a spacer 140.

[0033] The end supports 132A and 132B, as well as the intermediate supports 142, are thus fixed to the wall 120, the fusible blade 130 being formed so as to keep the reduced sections 136 away from the wall 120. The fusible blade 130 on the one hand, and the wall 120 and the spacers 140 on the other hand, delimit between themselves cavities 143, which are arranged between each reduced section 136 and the wall 120. The cavities 143 are therefore portions of the internal volume V110.

[0034] During the use of the fuse 100, when one of the reduced sections 136 melts, the electric arc extends on both sides of the fusible blade 130, which promotes its propagation and thus its extinction. When the fuse 100 is assembled, the internal volume V110 of the housing 110 is filled with sand. Each of the cavities 143 is also filled with sand. This sand is located on both sides of the fusible blade 130 at each reduced section 136, contributing to the effective extinction of the arc in the event of a melting of one of the reduced sections 136.

[0035] In an alternative design not shown, arc arresters are advantageously attached to the fusible strip 130 so as to completely or partially obstruct the perforations 138, thereby reducing the arc extinction time. The arc arresters are, for example, silicone strips that are glued to the fusible strip 130. The operation of the perforations 138 and the arc arresters is not described in further detail.

[0036] We will now detail the structure of the 140 spacers using the figure 2 and of the insert a) of the figure 3 On the figure 3 , fuse 100 is represented schematically, the dimensional scales are not respected.

[0037] In the first embodiment, each of the intermediate supports 142 and the end supports 132A and 132B is fixed to the wall 120 by a respective spacer 140. The spacers 140 are separate from one another and are electrically insulated from each other. What is true for one of the spacers 140 is applicable to the other spacers 140.

[0038] Each spacer 140 has a flattened rectangular shape, extending lengthwise parallel to the transverse axis Y100. Each spacer 140 thus has a length, measured parallel to the transverse axis Y100, greater than or equal to the width of the fusible blade 130. Each spacer 140 also has a width, measured parallel to the longitudinal axis X100, greater than or equal to the width of the corresponding intermediate support 142 or the corresponding end supports 132A and 132B, the width being measured parallel to the longitudinal axis X100. This ensures mechanical strength and heat transfer across all surfaces of each of the intermediate supports 142 or the end supports 132A and 132B.

[0039] Each spacer 140 comprises a central layer 144, which has a flattened shape with two opposing faces. The two opposing faces include an upper face 146A, which is oriented towards the internal volume V110, and a lower face 146B, which is oriented towards the wall 120. The upper face 146A and the lower face 146B are electrically insulated from each other. In the first embodiment, the central layer 144 comprises a plate 148, which is made of ceramic and which is coated, on each of its faces, with a layer of metal 150, here copper.

[0040] The 148 wafer typically has a thickness between 0.2 mm and 1.0 mm. The 148 wafer is made here of alumina (Al₂O₃). As non-limiting alternatives, the 148 wafer is made of aluminum nitride (Ain) or silicon nitride (Si₃N₄), these materials offering a good compromise between electrical insulation, thermal conductivity, and cost.

[0041] The wafer 148 and the metal layers 150 are bonded together, so as to metallize the faces of the wafer 148. This is referred to as a "Metallic Ceramic Substrate". The two metal layers 150, separated by the ceramic wafer 148, are electrically insulated from each other.

[0042] Among the preferred methods for metallizing ceramic substrates, direct bonding – or Direct Bonding In English, this is a high-temperature, high-pressure welding process that does not require the addition of any other interface material between the ceramic substrate and the metal layers. When the metal layers are made of copper, it is called the DBC process, an acronym for the English expression Direct Bonded Copper. When the metal layers are made of aluminum, it is called the DBA process, an acronym for the English expression Direct Bonded Aluminum.

[0043] We also know of bonding by adding a thin layer of brazing material between the ceramic substrate and the metal layers. Such a process is known, for example, as AMB, an acronym for the expression Active Metal Brazing.

[0044] The central layer 144 is here manufactured by hot pressing the different elements that compose it, according to the DBC direct bonding process.

[0045] Once the wafer 148 is metallized using the metal layers 150, the exposed faces of the metal layers 150 are advantageously coated with a topcoat, which is a few microns thick and made of a metal different from that of the metal layers 150. The topcoats are not shown. The metal of the topcoats is chosen according to the application, particularly for reasons of oxidation protection, intermetallics, etc. By way of non-limiting example, the topcoats are made of gold (Au), nickel (Ni), or silver (Ag).

[0046] In practice, the thicknesses of the wafer 148 and the metal layers 150 are chosen according to the thermal, mechanical, and electrical stresses encountered by the fuse 100 during its use. A wafer 148 that is too thin may not be sufficiently electrically insulating or mechanically resistant, while a wafer that is too thick may be too thermally insulating. Typically, the wafer 148 has a thickness between 0.1 mm and 1.0 mm.

[0047] Similarly, a layer of metal 150 that is too thin does not allow good adhesion to the insert 148 following the metallization process, in this case the DBC process. Typically, each layer of metal 150 has a thickness between 0.2 mm and 0.4 mm.

[0048] In the illustrated example, the plate 148 has a thickness of 0.6 mm, while each of the metal layers 150 has a thickness of 0.3 mm. In other words, the central layer 144 has a thickness of 1.2 mm.

[0049] Each spacer 140 also includes two bonding layers 152. The central layer 144 is interposed between the two bonding layers 152. In the first embodiment, each of the bonding layers 152 is made by means of a brazing flux.

[0050] Schematically, during the assembly of the fuse 100, each spacer 140 is positioned on the wall 120, while the fusible blade 130 is positioned on the spacers 140. The assembly is then heated, for example in a furnace, to melt the solder flux. When the solder flux cools, it solidifies and forms each of the bonding layers 152, ensuring the mechanical attachment of the fusible blade 130 to the wall 120, while also providing electrical insulation between the fusible blade 130 and the wall 120. One of the bonding layers 152 is fixed to the wall 120, while the other bonding layer is fixed to the main portion 134. Typically, the bonding layer 152 has a thickness between 20 µm and 200 µm. In the illustrated example, each bonding layer 152 has a thickness of approximately 100 µm. The order of the steps described above is not limiting.

[0051] Once assembled together, the wall 120, the fusible blade 130 and the spacers 140 together form a mounting sub-assembly 153 of the fuse 100.

[0052] Preferably, the metal layer 150 located on the upper side 146A has the smallest possible surface area, for example, an area substantially equal to the area of ​​the end support 132A or 132B or the opposite intermediate support 142, so as to ensure good mechanical retention while reducing the risk of flashover. Conversely, the metal layer 150 located on the lower side 146B has the largest possible surface area, so as to ensure good heat transfer between the plate 148 and the wall 120.

[0053] Preferably, for each spacer 140, the metal layers 150 only partially cover the corresponding plate 140, so as to reduce the risk of sparks between two adjacent spacers 140. In the illustration of the figure 3 a) There remains a gap 154 ​​between the two spacers 140 shown. This gap 154 ​​is therefore located between the plate 120 and the opposite reduced section 136. The internal volume V110 is normally filled with sand.

[0054] Other embodiments of the invention are now described. In these other embodiments, elements analogous to those of the first embodiment bear the same reference numerals and function in the same way. The following primarily describes the differences between each embodiment and the preceding one(s).

[0055] A 200 fuse according to another embodiment of the invention is shown in inset b) of the figure 3 One of the main differences between this embodiment and the previous one is that the gap 154 ​​is closed by an insulating element 202. The insulating element 202 is made of an electrically insulating material, for example, silicone. In other words, the insulating element 202 is inserted between the reduced section 136 and the wall 120 and closes the gap 154 ​​between the two intermediate supports 142 associated with this reduced section. Thus, when the opposite reduced section 136 melts, the insulating element 202 prevents the formation of an electric arc between the fusible blade 130 and the wall 120. The insulating element 202 is here bonded directly to the wall 120 using an adhesive. The adhesive is not shown.

[0056] A 300 fuse according to another embodiment of the invention is shown in inset c) of the figure 3 One of the main differences between this embodiment and previous embodiments is that the fuse 300 includes an insulating element 302 which forms a continuous layer on the surface of the wall 120. The insulating element 302 is represented by a hatched area on the figure 3 c) The insulating coating 302 is made of an electrically insulating material, for example, an epoxy resin, a silicone gel, or equivalent, which is applied after the assembly of the fusible blade 130, the spacers 140, and the wall 120. On the side of the internal volume V110, the insulating coating 302 covers all the intermediate supports 142, the associated spacers 140, and the gaps 154 between two successive spacers 140. In other words, for each reduced section 136, the insulating element 302 is inserted between this reduced section 136 and the wall 120 and seals the gap 154 ​​between the two intermediate supports 142 associated with this reduced section. Advantageously, the insulating coating 302 also covers the end supports 132A and 132B.

[0057] A 400 fuse according to another embodiment of the invention is shown in inset d) of the figure 3 One of the main differences between this embodiment and previous embodiments is that each spacer 140 comprises a ceramic plate 448 which extends continuously between two successive spacers 140, so as to close the gap 154 ​​between the two corresponding intermediate supports 142. On the figure 3 d) , the central layer 144 of the two adjacent spacers 140 is made of a single piece, so as to close the gap 154 ​​between the two intermediate supports 142 associated with these spacers 140. Advantageously, the plate 448 is common to all the spacers 140 fixed to the wall 120, so as to electrically isolate the whole of the fusible blade 130 from the wall 120.

[0058] A 500 fuse according to another embodiment of the invention is shown in inset a) of the figure 4 One of the main differences between this embodiment and previous embodiments is that the wall 120 of the fuse 500 includes, on the side of the internal volume V110, projections 502, which are formed on the surface of the wall 120 and which are arranged opposite each spacer 140. The projections 502 are formed for example by machining the wall 120.

[0059] Each spacer 140 is thus raised relative to the rest of the wall 120. This increases a height H136, measured parallel to the height axis Z100, between each reduced section 136 and the wall 120, compared to previous embodiments, which reduces the risk of an electric arc passing between one of the reduced sections 136 and the wall 120.

[0060] Preferably, insulating elements 504 are arranged between two successive projections 502 so as to prevent the transmission of an electric arc between the fusible blade and the wall 120 at the level of these insulating elements 504. In the illustrated example, the insulating elements 504 are made of an electrically insulating elastomeric material, for example, silicone. The insulating elements 504 are assembled, for example, by clipping or gluing to the mounting sub-assembly 153.

[0061] A 600 fuse according to another embodiment of the invention is shown in inset b) of the figure 4 One of the main differences between this embodiment and the previous ones is that pads 602 are inserted, during the manufacture of the mounting sub-assembly 153, between each spacer 140 and the fusible link 130, in order to increase the height H136. The pads 602 are made of a thermally conductive material compatible with brazing. The pads 602 are preferably made of metal, preferably copper or one of its alloys.

[0062] A 700 fuse according to another embodiment of the invention is shown in inset c) of the figure 4 One of the main differences between this embodiment and the previous one is that each spacer 140 comprises a central layer 744 made of an electrically insulating polymer material. Examples of such a material include polyethylene terephthalate (also known as PET), polyethylene terephthalate (also known as PBT), polyimide (also known as PI), for example, distributed as a film under the trade name "Kapton", meta-aramid, for example, distributed as a film under the trade name "Nomex", and polyetheretherketone (also known as PEEK).

[0063] In general, the surface thermal resistance "R" of a material, expressed in m²·K / W - square meter Kelvin per Watt - is equal to the thickness "e" of the material, expressed in meters and measured in the direction of heat transfer, divided by the thermal conductivity λ of this material, expressed in W / m·K - Watt per meter Kelvin -. In other words, R = e / λ.

[0064] Although the thermal conductivity λ of the central layer 744, made of polymer material, is lower than the thermal conductivity λ of the ceramic wafer 148 of the previous modes, the thickness e of the central layer 744 made of polymer material is much less than that of the ceramic wafer 148. As a result, the surface thermal resistance R the central layer 744 maintains an acceptable level, comparable to the surface thermal resistance R of layer 148.

[0065] For illustrative purposes, the thickness of the central polymer layer 744 is generally between 25 µm and 250 µm, while the wafer 148 shown here has a thickness of 0.6 mm. When the central layer 744 is made of polyimide, the thermal conductivity λ is typically between 0.46 W / m·K and 0.75 W / m·K, which should be considered in relation to the dielectric strength of 200 kV / mm. In other words, a 50 µm thick polyimide film has a surface thermal resistance R ranging from 66 mm²·K / W to 110 mm²·K / W, for a breakdown voltage of 10 kV, which is sufficient for an application using voltages on the order of 1 kV. In comparison, when the 148 wafer is made of alumina, the thermal conductivity λ is typically between 14 and 28 W / m·K, to be related to a dielectric strength of 35 kV / mm.Thus, an alumina 148 plate with a thickness of 1 mm has a surface thermal resistance R ranging from 35 mm² K / W to 71 mm² K / W for a breakdown voltage of 35 kV.

[0066] The central layer 744 is thus in the form of a polymer film, which is less likely to break than the plate 148 of previous modes. Optionally, the central layer 744 incorporates a fibrous reinforcement so that it forms a layer of composite material. The fibers are preferably made of an electrically insulating material, for example, glass fibers.

[0067] The central layer 744 is interposed between two bonding layers 752. In the embodiment of the figure 4 c) Each of the 752 bonding layers is made using a layer of adhesive material. Each of the 752 bonding layers typically has a thickness between 25 µm and 100 µm.

[0068] The material for the 752 bonding layers is chosen based on temperature resistance, durability, application time, etc. Non-limiting examples of adhesives used to form the bonding layers are silicone adhesives, acrylic adhesives, polyurethane adhesives, epoxy adhesives, cyanoacrylate adhesives, etc.

[0069] A fuse 800 according to another embodiment of the invention is shown in inset d) of the figure 4 One of the main differences between this embodiment and the previous one is that the spacer 140 includes a central layer 844, here made of a polymer film, which extends continuously between two successive intermediate supports 142, so as to electrically isolate the fusible blade 130 from the wall 120. In other words, the central layer 844 covers at least a gap 154 ​​between two consecutive intermediate supports 142. Advantageously, the central layer covers the wall 120 at least over an area corresponding to a projection of the fusible blade 130 onto the wall 120 along the height axis Z100.

[0070] The central layer 844 is interposed between two bonding layers 852. Preferably, the bonding layer 852 located between the central layer 844 and the wall 120 covers the central layer 844 over the entire surface of the central layer 844, so as to maximize the mechanical strength and the thermal transfer between the spacer 140 and the wall 120.

[0071] Preferably, the bonding layer 852 located between the central layer 844 and the fusible blade 130 wall 120 covers the central layer 844 over the entire surface of the central layer 844, so as to facilitate the fixing of the fusible blade 130 to the spacer 140.

[0072] In all the embodiments described so far, when an electric current flows through the fusible link 130, this current also passes through the intermediate supports 142. In the embodiments illustrated on the figures 5 à 8 The fusible link 130 is arranged to prevent current from passing through intermediate supports. These embodiments are described below.

[0073] A 900 fuse according to another embodiment of the invention is shown in the figure 5 One of the main differences between this embodiment and previous embodiments is that the fusible blade 130 includes an intermediate support 942 formed by folding a folding area of ​​the fusible blade 130 onto itself.

[0074] On insert a) of the figure 5 The fusible blade 130 is shown during an intermediate step in the manufacturing of the fusible blade 130.

[0075] The fusible blade has, between two successive reduced sections 136, a bending zone 943. The bending zone 943 is here a continuous area, delimited by two boundaries, or end zones 943A and 943B. The two end zones 943A and 943B are represented here by dashed lines, which are parallel to the transverse axis Y100. When the bending zone 943 is folded, the two end zones 943A and 943B are brought together, the bending zone 943 being folded back on itself, forming the intermediate support 942. In the illustrated example, one end 942A of the intermediate support 942 is folded so that the intermediate support 942 has an "L" shape, one foot of the L being configured to be fixed to the wall 120 by means of a spacer, as defined previously. The spacer is not shown on the figure 5 .

[0076] The intermediate support 942, obtained by folding the folded area 943 back on itself, thus comprises two walls 944. These two walls 944 are preferably joined together so as to ensure electrical contact between them. In some examples, the two walls 944 are joined together by welding, in particular by laser welding, or by brazing, using a brazing flux.

[0077] As a result, the two end zones 943A and 943B are in electrical contact with each other at the same electrical potential. When a current flows through the fusible strip 130, the current does not flow through the intermediate support 942. In other words, this intermediate support 942 is located outside the conduction path of the fusible strip 130. In the event of melting of one of the reduced sections 136, the risk of an electric arc traveling to the end 942A of the intermediate support 942 is reduced.

[0078] On the other hand, the intermediate support 942, formed of two walls 944 joined together, is advantageous; it is both mechanically resistant and promotes the transfer of heat generated at the reduced sections 136 towards its end 942A.

[0079] A fuse 10 according to another embodiment of the invention is shown in inset a) of the figure 6 One of the main differences between this embodiment and previous embodiments is that the fusible blade 130 includes intermediate supports 1042 which are formed by cutting the fusible blade 130. The intermediate supports 1042 are here provided along the longitudinal edges of the fusible blade 130, i.e. that a cutting profile of the intermediate supports 1042 is intersecting one of the longitudinal edges of the fusible blade 130.

[0080] In the illustrated example, the intermediate supports 1042 are bearing tabs, which are formed on either side of a reduced section along the transverse direction Y100. Each bearing tab has an elongated shape with a first end, which is connected to the fusible blade 130, and a second end 1042A, which is opposite the first end. Each bearing tab thus remains attached, by a material bridge, to the rest of the fusible blade 130. Once cut, each bearing tab is bent into the desired shape to form the corresponding intermediate support 1042, the second end 1042A being configured to be fixed to the wall 120 by means of a respective spacer 140, so as to keep the reduced sections 136 at a distance from the wall 120. The shape and arrangement of the intermediate supports 1042 are not limiting.

[0081] Placing intermediate supports 1042 on either side of a reduced section 136 reduces the amount of material to be melted during the melting of this reduced section 136. Furthermore, being located in the immediate vicinity of the reduced section 136, the intermediate supports 1042 contribute to efficient heat transfer to the wall 120. Finally, each of the intermediate supports 1042 is located outside the conduction path of the fusible strip 130, meaning that no current flows through the intermediate supports 1042 when a current flows through the fusible strip 130.

[0082] A fuse 11 according to another embodiment of the invention is shown in inset b) of the figure 6 As in the previous embodiment, the fusible blade 130 provides intermediate supports 1142 which are formed by cutting and folding the fusible blade 130. One of the main differences between this embodiment and the previous one is that the fusible blade 130 includes intermediate supports 1142 which are provided in pairs within the fusible blade 130. The two intermediate supports 1142 of each pair are thus provided opposite each other along the longitudinal direction X100. Advantageously, the intermediate supports 1142 of each pair are provided on either side, along the longitudinal axis X100, of a reduced section 136, so as to increase the heat transfer between this reduced section and the wall 120.

[0083] A fuse 12 according to another embodiment of the invention is shown in inset a) of the figure 7 The fusible blade 130 includes intermediate supports 1242 which are formed by cutting and bending the fusible blade 130. One of the main differences between this embodiment and the two previous embodiments is that the intermediate supports 1242 are provided at a distance from the longitudinal edges of the fusible blade 130. In other words, the cutting profile of each intermediate support 1242 does not intersect with any of the longitudinal edges of the fusible blade 130.

[0084] In the illustrated example, each intermediate support 1242 is obtained by cutting and then folding the fusible blade 130 near one of the reduced sections 136. Once the intermediate support 1242 is formed, cutting it leaves an opening in the fusible blade 130, which forms one of the perforations 138 associated with that reduced section 136. The material cut to create the perforations 138 is advantageously used to form the intermediate supports 1242. In other words, a perforation 138 is formed simultaneously with each intermediate support 1242 by folding and cutting the fusible blade 130. Of course, if necessary, other perforations are made in the fusible blade 130.

[0085] Each of the intermediate supports 1242 is located outside the conduction path of the fusible blade 130, i.e. no current flows through the intermediate supports 1242 when a current flows through the fusible blade 130.

[0086] A fuse 13 according to another embodiment of the invention is shown in inset b) of the figure 7 The fusible blade 130 includes intermediate supports 1342 obtained in the same way as the intermediate supports 1242 of the previous embodiment, i.e. by cutting and folding the fusible blade 130, so as to jointly form the intermediate supports 1342 and the associated perforations 138.

[0087] The intermediate supports 1342 and the end supports 132A and 132B are here fixed to the wall 120 by means of the spacers 140 similar to those of the first embodiment, i.e. comprising the central layer 144 integrating the plate 148 in ceramic metallized by the DBC process.

[0088] A fuse 14 according to another embodiment of the invention is shown in inset a) of the figure 8 One of the main differences between this embodiment and the previous embodiment is that the spacer 140 includes a central layer of the same type as the central layer 844 of the embodiment shown in the figure 4 d) that is to say that the central layer 844 is a film made of an electrically insulating polymer material, which extends continuously between the intermediate supports 1342. Preferably, the central layer 844 extends over the surface of the wall 120 at least over the whole projection, along the height axis Z100, of the fusible blade 130 on the wall 120.

[0089] The end supports 132A and 132B of the fuse blade 130 are here connected directly to the connection terminals 112, without being fixed to the wall 120, while intermediate supports 142 are provided between each of the ends 132A or 132B and the adjacent reduced portions 136 of these ends.

[0090] The bonding layer 852 between the central layer 844 and the wall 120 is also continuous, to ensure good mechanical support and good thermal transfer between the central layer 844 and the wall 120. For each of the intermediate supports 1342, the bonding layer 752 between the central layer 844 and the corresponding intermediate support 1342 is limited here to the surface sufficient to ensure good fixation between this intermediate support 1342 and the central layer 844.

[0091] A fuse 15 according to another embodiment of the invention is shown in inset b) of the figure 8 One of the main differences between this embodiment and previous embodiments is that the wall 120 provides, on the side of the internal volume V110, projections similar to the projections 502 of the embodiment illustrated by the figure 4 a) , that is to say projections arranged opposite each spacer 140, so as to raise the fusible blade 130 relative to the rest of the wall 120.

[0092] As in the previous embodiment, the spacer 140 here includes the central layer 844 formed of a polymer film, which is fixed to the wall 120 by conforming to the contour of the wall 120. In particular, the central layer 844, bonded to the wall 120 using the bonding layer 852, conforms to the profile of each of the projections 502. The fusible blade 130 is thus electrically separated from the wall 120 in a simple and economical manner.

[0093] A fuse 16 according to another embodiment of the invention is shown in the figure 9 One of the main differences between this embodiment and the previous embodiments is that the terminals 112 are connected to the ends 132A and 132B of the fusible blade by flexible conductors 160. On the other hand, the complementary portion 122 is here made in one part, and includes, on the side of the internal volume V110, protrusions 162. Each of the protrusions 162, which are seen here in cross-section, has a flattened shape and extends along a transverse plane, that is to say a plane orthogonal to the longitudinal axis X100, from the rest of the complementary portion 122 towards the fusible blade 130 located opposite. The protrusions 162 are thus arranged opposite the fusible blade 130, on the same side of the fusible blade 130. The protrusions 162 are arranged on either side of each reduced section 136, so as to limit the propagation of electric arcs in the internal volume when one of the reduced portions melts.In the illustrated example, an outgrowth 162 is provided opposite each of the intermediate supports 142 and opposite each of the end supports 132A and 132B.

[0094] Alternatively, when the fusible blade 130 comprises several reduced sections 136, two protrusions 162 are arranged on either side of at least one of the reduced sections.

[0095] In the described embodiments, the wall 120 is made of a thermally conductive material to dissipate the heat generated when an electric current flows through the fusible strip. In the examples, the wall 120 is made of a metal plate, particularly copper, which offers a good compromise between thermal conductivity and cost, while also being impact-resistant. Since the wall 120 is electrically conductive, the central layer 144 of the spacers 140 consequently comprises two opposing faces that are electrically insulated from each other. In the described examples, the spacer 140 comprises either a ceramic plate 148 or 448, or a polymer film 744 or 844.

[0096] In an alternative not shown, the wall is made of a thermally conductive but electrically insulating material. By way of non-limiting examples, the wall is made of thermally conductive resin, for example epoxy resin (with a thermal conductivity λ of the order of 1.5 W / m·K), or of hot injectable resin, in particular based on polyamide 6 - denoted PA6 -, or polyphenylene sulfide - denoted PPS -, or polycarbonate - denoted PC -.

[0097] In the illustrated example, the fusible blade 130 is made of a single piece, the end supports 132A, 132B, and the intermediate supports 142, 942,...,1342, each being fixed to the wall 120 by means of a respective spacer 140.

[0098] In an alternative configuration not shown, the fusible blade is made in several pieces. For example, each piece comprises a single reduced section interposed between two end supports, each end support being fixed to the wall 120 by means of a spacer 140, so as to keep the corresponding reduced section at a distance from the wall. Although this configuration allows the advantages of the invention to be realized, it is not preferred because assembling each piece of fusible blade to the wall 120 is delicate and time-consuming.

[0099] In the embodiments shown, the fusible blade 130 comprises several reduced sections 136, an intermediate support 142 being provided between each reduced section 136. This arrangement is not limiting.

[0100] In an alternative not shown, the fusible blade 130 comprises two consecutive reduced sections 136 without intermediate support arranged between these two reduced sections. According to another alternative, the fusible blade 130 comprises two or more intermediate supports interposed between two consecutive reduced sections, like the fusible blade of the figure 6 b) .

[0101] More generally, whether the fusible blade 130 comprises one or more main portions 134, each with at least one reduced section 136, at least one of the main portions 134 includes at least one support, whether an end support 132A, 132B, or an intermediate support 142, 1342, ..., 1342, by which this main portion 134 is fixed to the wall 120, this support being arranged so as to keep one or more of the reduced sections 136 away from the wall 120. Preferably, the support(s) are arranged to keep each reduced section 136 of the main portion 134 considered away from the wall 120. The fusible link includes at least one spacer 140, each spacer being interposed between each support and the wall 120. Depending on the case, each support is associated with a respective spacer 140. In other words, each 140 spacer is associated with a single support.Alternatively, the same spacer 140 is inserted between the wall 120 and several neighboring supports.

[0102] When the or one of the main portions 134 comprises two reduced sections 136, an intermediate support 142; 942;...; 1342 is advantageously provided between these two reduced sections, so as to keep the two reduced sections 136 associated with this intermediate support at a distance from the wall 120.

[0103] Multiple configurations are possible, and the person skilled in the art will be able to find the best compromise between rigidity of the fusible blade and size according to the development constraints.

[0104] The embodiments and variants mentioned above can be combined to generate new embodiments of the invention.

Claims

1. A fuse (100; ...; 900; 10;...; 16) comprising: - a housing (110), the housing (110) comprising a wall (120) which is made of metal and which defines an internal volume (V110) of the housing (110), the wall (120) being configured to be cooled from the outside of the housing (110), and - a fuse link (130), which comprises: • a main portion (134), which is made of one piece, which is received in the internal volume (V110) and which comprises two opposite ends, and • a reduced section (136), which is provided in the main portion between the two ends, characterized in that: - the main portion (134) comprises at least one support (132A, 132B, 142; 942;...; 1342) by which the main portion is attached to the wall (120), - the fuse comprises a spacer (140), which is inserted between each support and the wall, each spacer (140) comprising: • a central layer (144; 744; 844), which comprises two opposite faces (146A, 146B) electrically insulated from each other, and • Two connecting layers (152), each of which is made of a connecting material and which are applied to a respective side of the central layer, one of the connecting layers being attached to the wall (120), while the other connecting layer is attached to each support, - each support is arranged so to maintain the reduced section (136) at a distance from the wall (120).

2. The fuse (100; ... ; 900 ; 10 ;... ;16) according to claim 1, wherein: - the main portion (134) comprises two reduced sections (136). - the main portion (134) provides an intermediate support (142; 942; 1042; 1142; 1242; 1342), which is arranged between the two reduced sections (136) and which is attached to the wall (120) by means of a spacer (140), - the fuse link (130) is formed so as to maintain the reduced sections associated with the intermediate support at a distance from the wall (120).

3. The fuse (900 ; 10 ;... ;15) according to any one of claims 1 or 2, wherein: - the fuse link (130) comprises at least one support (942; 1042; 1142; 1242; 1342) which is provided such that the support is located outside the conduction path of the fuse link (130) when a current flows through the fuse link.

4. The fuse (10;...; 15) according to claim 3, wherein: - at least one of the supports (1042; 1142; 1242; 1342) comprises at least one support lug, each support lug being formed by cutting out the fuse link (130) and having an elongate shape with a first end, which is connected to the fuse link (130), and a second end, which is opposite the first end and which is attached to the wall (120) by the corresponding spacer (140).

5. The fuse (12;...; 15) according to claim 4, wherein, for at least one bearing lug (1242; 1342), that bearing lug is cut in the vicinity of a reduced section (136), the cut in said bearing lug forming a perforation (138) associated with said reduced section (136).

6. The fuse (900) according to claim 3, wherein: - the support (942) is formed by folding a folding zone (943) of the main portion (134), the folding zone extending along a length of the main portion and comprising two end zones (943A, 943B) and an intermediate zone located between the two end zones, - the intermediate region is folded to form the support (942), while the two end regions (943A, 943B) are in electrical contact with each other.

7. The fuse (200; 300; 500) according to any one of claims 1 to 6, wherein, for at least one of the reduced sections (136) of the main portion (134): - the main portion (134) comprises two supports (132A, 132B, 142; 942;...; 1342), associated with the reduced cross-section, - an insulating element (202; 302; 504) is inserted between the reduced section (136) and the wall (120). - the insulating element at least partially closes a gap (154) between the two supports associated with the reduced section (136).

8. The fuse (400; 800; 14; 15) according to any one of claims 1 to 6, wherein, for at least one of the reduced sections (136) of the main portion (134): - the main portion (134) comprises two neighboring supports (132A, 132B, 142; 942;...; 1342) associated with the reduced section, - for the two spacers associated with the two supports, the central layer of the two spacers being made in one piece, so as to close off a gap between the two supports.

9. The fuse (700; 800; 14; 15) according to any one of claims 1 to 8, wherein the central layer (744; 844) are made of an electrically insulating polymer material.

10. The fuse (100;...; 600; 900; 10;...; 13) according to any one of claims 1 to 8, wherein the central layer (144) comprises a wafer (148; 448) made of ceramic.

11. The fuse (600; 700; 800) according to any one of claims 1 to 10, wherein studs (602) are inserted between each spacer (140) and the fuse link (130) so as to increase a distance between each reduced section (136) and the wall (120).

12. The fuse (500; 15) according to any one of claims 1 to 11, wherein the wall (120) comprises protrusions (502) formed on the surface of the wall (120) and provided opposite each spacer (140) so as to increase a distance between each reduced section (136) and the wall (120).

13. The fuse (16) according to any one of claims 1 to 12, wherein: - the housing (110) comprises, in addition to the wall (120), a supplementary portion (122) of the wall (120). - the supplementary portion (122) is made of an insulating material and delimits, with the wall (120), the internal volume (V110) of the housing (110), - for at least one of the reduced sections (136), the supplementary portion of the housing (110) comprises at least two protuberances (162), which extend within the internal volume and which are arranged on both sides of the reduced section (136), so as to limit the propagation of electric arcs in the internal volume when the reduced section (136) melts.

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