WO2024052527A1

WO2024052527A1 - Fuse

Info

Publication number: WO2024052527A1
Application number: PCT/EP2023/074721
Authority: WO
Inventors: Gianfranco De Palma; Jean-Francois Oeuvrard; Laurent MILLIERE
Original assignee: Mersen France Sb Sas
Priority date: 2022-09-09
Filing date: 2023-09-08
Publication date: 2024-03-14
Also published as: FR3139662A1

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

DESCRIPTION

TITLE: Fuse

The present invention relates to a fuse.

A fuse, sometimes also called a “fuse cartridge”, is an electrical component comprising two terminals and allowing, in the event of an overcurrent beyond a limit called fuse rating, to interrupt the circulation of electric current between the two terminals. The two terminals are fixed to an insulating body providing a cavity and are electrically connected to each other via at least one fuse blade, arranged within the cavity of the insulating body. One or more fuse blades can be connected in parallel to the two terminals depending on the size of the fuse. What is described for a fuse blade can be transposed to other fuse blades when there are several.

A fuse blade is made of a conductive material having a given electrical resistance and a given melting temperature. When an electric current flows through the fuse blade, it heats up by the Joule effect. In normal operation, the temperature of the fuse blade remains below the melting temperature. In the event of an overcurrent, the temperature of the fuse blade increases and exceeds the melting temperature at one or more points of the fuse blade, which melts at least partially, and the flow of current is irreversibly cut off. The fuse blade includes, between the connections with the two poles, at least one intermediate portion having a reduced surface section. Such an intermediate portion is called a “reduced section”. Each reduced section offers greater resistance to the passage of current than the rest of the blade. As the intensity of the current flowing through the blade increases, the temperature of each reduced section increases more than the temperature of the rest of the blade. In the event of overcurrent, the blade melts preferably at a reduced section.

When a reduced section melts, an electric arc is created, and a current continues to flow until the electric arc is extinguished. The electric arc, defined as a plasma state of the material, causes strong localized heating which promotes the melting of the fuse blade. With the thermal and electrical conditions, this change in state of the material of the fuse blade in turn promotes the maintenance and lengthening of the electric arc. The cavity is generally filled with a material that helps extinguish the arc, generally sand, so as to reduce the fuse breaking time. For certain high-power applications, in particular for charging electric vehicles, the fuses must both have a high rating, to reduce the charging time, while limiting as much as possible a short-circuit leakage current when the fuse bottom. We also speak of PLTC current - for “Peak Let Through Current” in English. The PLTC current is linked, among other things, to the fuse cut-off time. In the case of vehicle charging, in the event of a charging malfunction, the lower the PLTC current, the lower the risk of vehicle fire. It is therefore necessary to have a fuse which offers the highest possible nominal current, to reduce the recharge time, while maintaining the lowest possible PLTC current.

The PLTC current is for example limited by certain standards, for example the ISO17409:2020 standard relating to the charging of electric vehicles. As an illustration, according to this standard, for vehicle charging at a voltage of 1000 V, with a nominal current of 1000 A, the admissible limit of the PLTC current is 30 kA. However, such performances are not accessible to fuses of classic architecture.

A known approach to improving the performance of fuses consists of cooling the fuse blade, so as to evacuate the heat generated by the Joule effect when the current passes through the fuse blade.

WO-2012 025853-A1 describes, for example, a fuse with a housing comprising a cooled wall made of electrically insulating ceramic. The fuse blade is made up of multiple elements which are glued directly to the cooled wall. Such a fuse is, however, difficult to manufacture, each element of the fuse blade being attached individually to the wall. The ceramic wall, which remains relatively thin so as not to hinder heat transfer, is also relatively fragile and risks breaking, particularly in the event of an impact or under the effect of temperature differentials between its two faces.

EP0292225A2 describes, for its part, a fuse with a metal wall, on which a ceramic plate is laminated. A metallic circuit is formed directly on an internal face of the plate, so as to form the fuse element. However, such a structure is not suitable for fuse elements comprising several reduced sections. On the other hand, when the fuse is filled with sand, the latter is only present on one side of the fuse element. Such a fuse cannot effectively interrupt, with a reduced breaking time, overcurrents involving high energy levels, for example in the case of vehicle charging.

It is these problems that the invention aims to remedy in particular, by proposing a fuse which is robust and efficient. To this end, the invention relates to a fuse, comprising:

- a housing, the housing comprising a wall which is made of metal and which delimits an internal volume of the housing, the wall being configured to be cooled by the exterior of the housing, and

- a fuse blade, which includes:

• a main portion, which is made in one 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 zones.

According to the invention:

- the main portion comprises at least one support, by which the main portion is fixed to the wall,

- the fuse comprises a spacer, which is inserted between each support and the wall, each spacer comprising:

• a central layer, which comprises 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.

Thanks to the invention, the wall of the case which serves to cool the fuse during its use is made of metal and is therefore resistant to shocks and thermal cycles. The fuse blade is stuck to the metal wall while remaining electrically isolated from the metal wall, while the reduced section is kept at a distance from the metal wall. When the reduced section melts, the electric arc extends on both sides of the fuse blade. Advantageously, when the fuse is assembled, the case is filled with a material promoting the extinction of electric arcs, for example sand. This sand is found on both sides of the reduced section, contributing to the good extinction of the arc in the event of melting of the reduced section.

According to advantageous but not obligatory aspects of the invention, such a fuse can incorporate one or more of the following characteristics taken in isolation or in any technically admissible 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 which is fixed to the wall by means of a spacer, and that the fuse blade is formed so as to keep the reduced sections associated with the intermediate support at a distance from the wall.

The fuse blade comprises at least one support which is provided so that this support is located outside the conduction path of the fuse blade when a current flows in the fuse blade.

At least one of the supports among the end supports and the intermediate support comprises at least one support tab, each support tab being formed by cutting the fuse blade and having an elongated shape with a first end, which is connected to the fuse blade, and a second end, which is opposite the first end and which is fixed to the wall by the corresponding spacer.

For at least one support tab, this support tab is cut in the vicinity of a reduced section, the cutting of this support tab forming a perforation for this reduced section.

The support is formed by folding a folding zone of the main portion, the folding zone extending over 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 so as 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 in part, an interval 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 neighboring supports associated with this 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.

Studs are inserted between each spacer and the fuse blade, so as to increase a distance between each reduced section and the wall. The wall comprises projections, which are provided on the surface of the wall and which are arranged opposite each spacer, so as to increase a distance between each reduced section and the wall.

The housing includes, in addition to the wall, a complementary portion of the wall:

• the complementary portion is made of an insulating material and delimits, with the wall, the internal volume of the box,

• for at least one of the reduced sections, the complementary portion of the housing 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 propagation electric arcs in the internal volume when this reduced section melts.

The invention will be better understood, and other advantages thereof will appear more clearly in the light of the description which follows, of several embodiments of a fuse, conforming to its principle, given solely as a guide. example and made with reference to the appended drawings, in which:

- [Fig 1] Figure 1 is a perspective view of a longitudinal section of a fuse conforming to a first embodiment of the invention;

- [Fig 2] Figure 2 represents respectively, on two inserts a) and b), a perspective view of a section, along a longitudinal plane II in Figure 1, of a sub-assembly of the fuse of the figure 1, and a detail of this subset;

- [Fig 3] Figure 3 schematically represents, on four inserts a) to d), a front view of the sub-assembly of Figure 2 and a front view of three sub-assemblies each belonging to a fuse conforming to d other embodiments of the invention;

- [Fig 4] 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] Figure 5 represents, on two inserts a) and b), two stages of manufacturing a fuse blade belonging to a fuse conforming to another embodiment of the invention;

- [Fig 6] Figure 6 represents, on two inserts a) and b), details of two fuse blades each belonging to a fuse conforming to other embodiments of the invention;

- [Fig 7] Figure 7 represents respectively, on two inserts a) and b), a detail of a fuse blade and a sub-assembly, each belonging to a fuse conforming to other embodiments of the invention ; - [Fig 8] Figure 8 represents respectively, on two inserts a) and b), two fuses conforming to other embodiments of the invention, and

- [Fig 9] Figure 9 is a section of a fuse conforming to another embodiment of the invention.

A fuse 100, conforming to a first embodiment of the invention, is shown in Figure 1. The fuse 100 comprises a housing 110 and two connection terminals 112.

The housing 110 generally has the shape of an elongated cylinder 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.

In the example illustrated, the housing 110 has a generally parallelepiped shape, that is to say that the housing 110 has the shape of a cylinder of rectangular section. The housing 1 10 is hollow, that is to say that the housing 1 10 delimits an internal volume V1 10. In the description which follows, the notions of “top”, “bottom”, etc., are given in reference to the orientation of the various elements of the fuse 100 in the drawings, knowing that the fuse 100 can be oriented differently in reality.

The housing 1 10 includes a wall 120, which is configured to be cooled from the outside of the housing. In normal use of the fuse 100, the wall 120 is fixed against a cooling device, for example a metal support comprising refrigerated fluid channels. The cooling device is not shown.

The wall 120 is here a lower wall of the housing 110. The wall 120 is made of a material having good thermal conductivity, while being resistant to the constraints of use of the fuse 100, in particular shocks. The wall 120 is here made of metal, preferably copper or one of its alloys. The wall 120 is here made in a plate and extends parallel to the longitudinal axis X100 and orthogonal to an axis of height Z100 of the fuse.

By extension, the reference Z100 also designates a direction of height, which is oriented from the bottom to the top of the figures. We also define a transverse axis Y100 as being an axis orthogonal to both the longitudinal axis X100 and the height axis Z100, the three axes X100, Y100 and Z100 being arranged so as to form a direct reference.

In addition to the wall 120, the housing 1 10 also comprises a complementary portion 122, which cooperates with the wall 120, in particular by complementarity of shapes, to delimit the internal volume V1 10. The complementary portion 122 is made of an electrically insulating material, for example made of a synthetic polymer such as polyamide, and is manufactured for example by hot injection. The two connection terminals 1 12 are accessible from outside the housing 120, here outside the complementary portion 122.

In the example illustrated, the complementary portion 122 is made in two parts, with 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 restrictive. According to examples, the complementary portion 122 is concave, while the wall 120, formed in a plate to simplify production, closes the complementary 122, delimiting the internal volume V110 of the housing 110.

In the example illustrated, the terminals 112 protrude out of the housing 110 by passing through the cover 122B. This arrangement of connection terminals 112 is not restrictive. 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. In normal operation of the fuse 100, the internal volume V1 10 is generally filled with sand. Sand is not shown. The openings 124 are then closed to prevent sand leaks, for example by means of a sealant, in particular a polysiloxane sealant, also called silicone.

The fuse 100 also includes a fuse blade 130, which is received in the internal volume V1 10. The fuse blade 130 is fixed to the wall 120 to be cooled during use of the fuse 100.

The fuse blade 130 is made of a conductive material, which has a given electrical resistance and melting temperature. The material of the fuse blade 130 is preferably metallic, and has a thickness generally between 0.03 mm and 1.0 mm, preferably between 0.06 mm and 0.3 mm. The fuse blade 130 is for example made of silver, or copper, or aluminum, or tin, or one of their respective alloys. The fuse blade 130 is here formed by perforating and/or cutting and/or folding a strip of metal, which has a constant width, measured parallel to the transverse axis Y100. Alternatively, the fuse blade 130 has a variable width. The long sides of the metal strip are arranged parallel to the longitudinal axis X100 and form longitudinal edges of the fuse blade 130.

The fuse blade 130 thus has an elongated shape, which extends substantially along the longitudinal axis and 132B of the fuse blade 130. By extension, the references 132A and 132B also designate the end supports 132A and 132B. Each of the end supports 132A and 132B is here electrically connected to a respective connection terminal 112. In the example illustrated, each end support 132A and 132B is fixed to the wall 120, by means of a respective spacer 140. The spacers 140 are detailed below.

The fuse 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 in one piece. The main portion 134 here comprises three reduced sections 136, this number not being limiting. As a variant not shown, the main portion 134 comprises a single reduced section, or two reduced sections, or even four or more reduced sections.

Each reduced section 136 is formed by a row of holes, this row being oriented along the transverse axis Y100. Thus the fuse blade 130 presents, at the level of each reduced section 136, an electrical resistance greater than the electrical resistance elsewhere than at the level of the reduced sections 136. When an electric current flows between the terminals 1 12, the fuse blade 130 presents , at the level of the reduced sections 136, localized heating. In the event of an overcurrent, the melting of the material of the fuse blade 130 occurs preferentially at the level of the reduced sections 136.

In the example illustrated, the fuse blade 130 comprises three identical reduced sections 136. The fuse blade 130 therefore presents a “breaking time/breaking intensity” response curve with a given appearance. As a variant not shown, the fuse blade 130 has several types of reduced sections, the holes forming each reduced section having for example different diameters depending on the reduced section considered. Thus, when an overcurrent occurs, certain reduced sections 136 are likely to melt more quickly than others. By combining different types of reduced sections 46, we obtain a response curve which 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.

In the example illustrated, the fuse strip 130 also comprises perforations 138, which here are each of oblong shape and which are arranged in rows 139, on either side of each reduced section 136. Each row 139 here comprises three perforations 138. The fuse blade 130 here comprises six rows 139 of perforations, which are associated in pairs with each of the reduced sections 136. The perforations 138, or "blowholes" in English, reduce the quantity of material to be melted during the progression of the electric arc, when the fuse blows. The progression of the arc is thus faster than in the absence of perforations 138, which ultimately reduces the arc extinction time. The operation of the perforations 138 is not detailed further.

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

The end supports 132A and 132B, as well as the intermediate supports 142, are thus fixed to the wall 120, the fuse blade 130 being formed so as to maintain the reduced sections 136 at a distance from the wall 120. The fuse blade 130 d on the one hand, and the wall 120 and the spacers 140 on the other hand, delimit between them 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.

During the use of the fuse 100, when one of the reduced sections 136 melts, the electric arc extends on both sides of the fuse blade 130, which promotes its progression, and therefore its extinction. When the fuse 100 is assembled, the internal volume V1 10 of the box 1 10 is filled with sand. Each of the cavities 143 is also filled with sand. This sand is found on both sides of the fuse blade 130 at the level of each reduced section 136, contributing to the successful extinction of the arc in the event of melting of one of the reduced sections 136.

In a variant not shown, arc guards are advantageously fixed on the fuse blade 130, so as to obstruct, totally or partially, the perforations 138, and thus reduce the time for extinction of the electric arc. The arc guards are for example silicone tabs, which are glued to the fuse strip 130. The operation of the perforations 138 and the arc guards is not detailed further.

We now detail the structure of the spacers 140 using Figure 2 and insert a) of Figure 3. In Figure 3, the fuse 100 is represented schematically, the dimensional scales not being respected.

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 here distinct from each other and are electrically isolated from each other. What is valid for one of the spacers 140 can be transposed to the other spacers 140.

Each spacer 140 here has the shape of a flattened rectangle, which extends in its length 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 a width of the fuse blade 130. Each spacer 140 also has a width, length, measured parallel to the longitudinal axis X100, greater than or equal to a width of the corresponding intermediate support 142 or of the corresponding end supports 132A and 132B, the width being measured parallel to the longitudinal axis X100. This ensures mechanical strength and thermal transfer on all the surfaces of each of the intermediate supports 142 or the end supports 132A and 132B.

Each spacer 140 includes a central layer 144, which has a flattened shape with two opposing faces. The two opposite faces include a high face 146A, which is oriented towards the internal volume V110, and a low face 146B, which is oriented towards the wall 120. The high 146A and low 146B faces are electrically isolated from each other . In the first embodiment, the central layer 144 comprises a plate 148, which is made of ceramic, and which is covered, on each of its faces, with a layer of metal 150, here copper.

The plate 148 typically has a thickness of between 0.2 mm and 1.0 mm. The plate 148 is here made of alumina - AI2O3 -. According to non-limiting alternatives, the plate 148 is made of aluminum nitride - AIN - or of silicon nitride - Si3N ₄ -, these materials offering a good compromise between electrical insulation, thermal conductivity and cost.

The plate 148 and the metal layers 150 are joined together, so as to metallize the faces of the plate 148. We speak of a “Metallized Ceramic Substrate”. The two layers of metal 150, separated by the ceramic plate 148, are electrically isolated from each other.

Among the preferred methods of metallizing a ceramic substrate, we know in particular direct bonding - or Direct Bonding in English -, which is a welding process at temperature under pressure, without adding another interface material between the ceramic substrate and the layers of metal. When the layers of metal are made of copper, we speak of the DBC process, an acronym for the English expression Direct Bonded Copper. When the metal layers are made of aluminum, we speak of the DBA process, an acronym for the English expression Direct Bonded Aluminum.

Bonding is also known by adding a thin layer of solder material between the ceramic substrate and the metal layers. Such a process is for example known under the name AMB, an acronym for the expression Active Metal Brazing.

The central layer 144 is here manufactured by hot pressing of the different elements which compose it, according to the DBC direct bonding process.

Once the plate 148 is metallized using the layers of metal 150, the exposed faces of the layers of metal 150 are advantageously covered with a finishing layer, which has a thickness of a few microns and which is made up of a metal of a nature different from that of the metal layers 150. The finishing layers are not shown. The metal of the finishing layers is chosen according to the application, in particular for protection against oxidation, intermetallics... According to non-limiting examples, the finishing layers are in gold - Au -, or in nickel - Ni -, or in silver - Ag -.

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

Likewise, a layer of metal 150 that is too thin does not allow good adhesion to the wafer 148 following the metallization process, here the DBC process. Typically, each layer of metal 150 has a thickness of between 0.2 mm and 0.4 mm.

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

Each spacer 140 also comprises 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 produced by means of a soldering flux.

Schematically, when assembling the fuse 100, each spacer 140 is positioned on the wall 120, while the fuse blade 130 is positioned on the spacers 140. The assembly is then heated, for example in an oven, from so as to melt the soldering flux. When the brazing flux cools, it solidifies and forms each of the bonding layers 152, ensuring the mechanical strength of the fuse blade 130 to the wall 120, while ensuring electrical insulation between the fuse blade 130 and the wall 120. One of the bonding layers 152 is attached to the wall 120, while the other bonding layer is attached to the main portion 134. Typically, the bonding layer 152 has a thickness of between 20 μm and 200 μm. In the Example illustrated, each bonding layer 152 has a thickness substantially equal to 100 μm. The order of the steps described above is not restrictive.

Once assembled together, the wall 120, the fuse blade 130 and the spacers 140 together form a mounting subassembly 153 of the fuse 100.

Preferably, the metal layer 150 located on the high side 146A has the smallest possible surface, for example a surface substantially equal to a surface of the end support 132A or 132B or of the intermediate support 142 facing, so as to ensure good mechanical support while reducing the risk of lightning. Conversely, the metal layer 150 located on the low side 146B has a surface that is the most as wide as possible, so as to ensure good thermal transfer between the plate 148 and the wall 120.

Preferably, for each spacer 140, the layers of metal 150 only partially cover the corresponding plate 140, so as to reduce the risk of lightning between two neighboring spacers 140. In the illustration of Figure 3 a), there remains a gap 154 between the two spacers 140 shown. The interval 154 is therefore located between the plate 120 and the reduced section 136 facing it. The internal volume V1 10 is normally filled with sand.

We now describe the other embodiments of the invention. In the other embodiments, the elements similar to those of the first embodiment bear the same references and operate in the same way. In what follows, we mainly describe the differences between each embodiment and the previous one(s).

A fuse 200 according to another embodiment of the invention is shown in insert b) of Figure 3. One of the main differences between this embodiment and the previous embodiment is that the interval 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 reduced section 136 located opposite melts, the insulating element 202 prevents the formation of an electric arc between the fuse blade 130 and the wall 120. The insulating element 202 is here glued directly to the wall 120, at using an adhesive. Adhesive is not shown.

A fuse 300 according to another embodiment of the invention is shown in insert c) of Figure 3. One of the main differences between this embodiment and the previous embodiments is that the fuse 300 comprises an element 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 in Figure 3 c). The insulating coating 302 is made of an electrically insulating material, for example an epoxy resin, or a silicone gel, or equivalent, which is applied after the assembly of the fuse strip 130, the spacers 140 and the wall 120. The insulating coating 302 covers here, on the side of the internal volume V110, all of the intermediate supports 142, associated spacers 140, and intervals 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 closes 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. A fuse 400 according to another embodiment of the invention is shown in insert d) of Figure 3. One of the main differences between this embodiment and the previous embodiments is that each spacer 140 comprises a plate ceramic 448 which extends, continuously, between two successive spacers 140, so as to close the gap 154 between the two corresponding intermediate supports 142. In Figure 3 d), the central layer 144 of the two neighboring spacers 140 is made in one 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 entire fuse strip 130 from the wall 120.

A fuse 500 according to another embodiment of the invention is shown in insert a) of Figure 4. One of the main differences between this embodiment and the previous embodiments is that the wall 120 of the fuse 500 comprises, on the side of the internal volume V110, projections 502, which are provided 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.

Each spacer 140 is thus raised relative to the rest of the wall 120. A height H 136 is thus increased, measured parallel to the height axis Z100, between each reduced section 136 and the wall 120, compared to the previous embodiments. , which reduces the risk of an electric arc passing between one of the reduced sections 136 and the wall 120.

Preferably, insulating elements 504 are arranged between two successive projections 502, so as to prevent the transmission of an electric arc between the fuse blade and the wall 120 at the level of these insulating elements 504. In the example illustrated, 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 by gluing to the mounting subassembly 153.

A fuse 600 according to another embodiment of the invention is shown in insert b) of Figure 4. One of the main differences between this embodiment and the previous embodiments is that pads 602 are interposed, during the manufacture of the mounting subassembly 153, between each spacer 140 and the fuse strip 130, so as to increase the height H136. The pads 602 are here made of a thermally conductive material compatible with assembly by brazing. The pads 602 are preferably made of metal, more preferably made of copper or one of its alloys. A fuse 700 according to another embodiment of the invention is shown in insert c) of Figure 4. One of the main differences between this embodiment and the previous embodiment is that each spacer 140 comprises a layer central 744 made of an electrically insulating polymer material. In a non-limiting manner, examples of such a material are polyethylene terephthalate - also known as PET -, polybutylene terephthalate - also known as PBT -, polyimide - also known as PI -, for example distributed in the form of a film under the trade name of “Kapton”, meta-aramid, for example distributed in film form under the trade name of “Nomex”, polyetheretherketone - also known as PEEK -.

Generally speaking, the surface thermal resistance "R" of a material, expressed in m ² -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 À of this material, expressed in W/mK - Watt per meter Kelvin -. In other words, R = e / À.

Although the thermal conductivity À of the material of the central layer 744, made of polymer material, is lower than the thermal conductivity À of the material of the plate 148 of the previous modes, made of ceramic, the thickness e of the central layer 744 in polymer material is much lower than that of the ceramic plate 148. This results in the surface thermal resistance R of the central layer 744 maintaining an acceptable level, comparable to the surface thermal resistance R of the layer 148.

For illustration purposes, the thickness of the central layer 744 of polymer material is generally between 25 pm and 250 pm, while the plate 148 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/mK and 0.75 W/mK, to be related to the dielectric rigidity of 200 kV/mm. In other words, a polyimide film 50 μm thick has a surface thermal resistance R ranging from 66 mm ² K/W to 1 10 mm ² K/W, for a breakdown voltage of 10 kV, which is sufficient for a application using voltages of the order of 1 kV. In comparison, when the plate 148 is made of alumina, the thermal conductivity À is typically between 14 and 28 W/mK, to be compared with a dielectric rigidity of 35 kV/mm. Thus an alumina plate 148 with a thickness of 1 mm has a surface thermal resistance R ranging from 35 mm ² K/W to 71 mm ² K/W for a breakdown voltage of 35 kV.

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

The central layer 744 is interposed between two connecting layers 752. In the embodiment of Figure 4 c), each of the connecting layers 752 is produced by means of a layer of adhesive material. Each of the bonding layers 752 typically has a thickness of between 25 pm and 100 pm.

The material of the bonding layers 752 is chosen based on temperature resistance performance, durability, processing 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.

A fuse 800 according to another embodiment of the invention is shown in insert d) of Figure 4. One of the main differences between this embodiment and the previous embodiment is that the spacer 140 comprises a central layer 844, here made of a polymer film, which extends continuously between two successive intermediate supports 142, so as to electrically separate the fuse strip 130 from the wall 120. In other words, the central layer 844 covers at least one interval 154 between two consecutive intermediate supports 142. Advantageously, the central layer covers the wall 120 at least on a surface corresponding to a projection of the fuse blade 130 on the wall 120 along the height axis Z100.

The central layer 844 is interposed between two connecting layers 852. Preferably, the connecting 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 heat transfer between the spacer 140 and the wall 120.

Preferably, the connecting layer 852 located between the central layer 844 and the fuse strip 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 fuse strip 130 at spacer 140.

In all the embodiments described so far, when an electric current flows in the fuse blade 130, this current also passes through the intermediate supports 142. In the embodiments illustrated in Figures 5 to 8, the fuse blade 130 is arranged so as to avoid the passage of current through the intermediate supports. These embodiments are described below. A fuse 900 according to another embodiment of the invention is shown in Figure 5. One of the main differences between this embodiment and the previous embodiments is that the fuse blade 130 comprises an intermediate support 942 formed by folding of a folding zone of the fuse blade 130 on itself.

On insert a) of Figure 5, the fuse blade 130 is shown during an intermediate step, during the manufacture of the fuse blade 130.

The fuse blade has, between two successive reduced sections 136, a folding zone 943. The folding zone 943 is here a continuous zone, which is delimited by two borders, or end zones 943A and 943B. The two end zones 943A and 943B are represented here by mixed lines, which are parallel to the transverse axis Y100. When folding the folding zone 943, the two end zones 943A and 943B are brought closer to each other, the folding zone 943 being folded back on itself, forming the intermediate support 942. In the example illustrated, one end 942A of the intermediate support 942 is folded so that the intermediate support 942 has an "L" shape, one leg of the L being configured to be fixed to the wall 120 via a spacer, as previously defined. The spacer is not shown in Figure 5.

The intermediate support 942, obtained by folding the folding zone 943 on itself, thus comprises two walls 944. These two walls 944 are preferably secured to each other so as to ensure electrical contact between these two walls. According to examples, the two walls 944 are joined to each other by welding, in particular by laser welding, or by brazing, using a brazing flux.

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 in the fuse blade 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 fuse blade 130. In the event of fusion of a reduced sections 136, the risks of an electric arc moving towards the end 942A of the intermediate support 942 are reduced.

On the other hand, the intermediate support 942, formed of two walls 944 secured to each other, is advantageous it is both mechanically resistant and promotes the transfer of the heat generated at the level of the reduced sections 136 towards its end 942A.

A fuse 10 according to another embodiment of the invention is shown in insert a) of Figure 6. One of the main differences between this embodiment and the previous embodiments is that the fuse blade 130 comprises intermediate supports 1042 which are formed by cutting the fuse blade 130. The intermediate supports 1042 are here provided along the longitudinal edges of the fuse blade 130, that is to say that a cutting profile of the intermediate supports 1042 intersects one of the longitudinal edges of the fuse blade 130.

In the example illustrated, the intermediate supports 1042 are support legs, which are provided on either side of a reduced section in the transverse direction Y100. Each support tab has an elongated shape with a first end, which is connected to the fuse blade 130, and a second end 1042A, which is opposite the first end. Each support tab thus remains attached, by a bridge of material, to the rest of the fuse blade 130. Once cut, each support tab is folded according to the desired shape, so as 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 maintain the reduced sections 136 at a distance from the wall 120. The shape and arrangement of the intermediate supports 1042 are not limiting .

Providing the intermediate supports 1042 on either side of a reduced section 136 accordingly reduces the quantity of material to be melted during the fusion of this reduced section 136. On the other hand, being located in the immediate vicinity of the section reduced 136, the intermediate supports 1042 contribute to the good transfer of heat towards the wall 120. Finally, each of the intermediate supports 1042 is located outside the conduction path of the fuse blade 130, that is to say that no current circulates through the intermediate supports 1042 when a current flows through the fuse blade 130.

A fuse 11 according to another embodiment of the invention is shown in insert b) of Figure 6. As in the previous embodiment, the fuse blade 130 provides intermediate supports 1142 which are formed by cutting and folding of the fuse blade 130. One of the main differences between this embodiment and the previous embodiment is that the fuse blade 130 comprises intermediate supports 1142 which are provided in pairs in the fuse blade 130. The two intermediate supports 1142 of the same pair are thus arranged facing each other in the longitudinal direction X100. Advantageously, the intermediate supports 1142 of the same 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 .

A fuse 12 according to another embodiment of the invention is shown in insert a) of Figure 7. The fuse blade 130 comprises intermediate supports 1242 which are formed by cutting and folding the fuse blade 130. 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 fuse blade 130. In other words, the cutting profile of each intermediate support 1242 does not intersect with one of the longitudinal edges of the fuse blade 130.

In the example illustrated, each intermediate support 1242 is obtained by cutting then folding the fuse blade 130, in the vicinity of one of the reduced sections 136. Once the intermediate support 1242 is formed, the cutting of this intermediate support 1242 leaves in the fuse blade 130 an opening, which forms one of the perforations 138 associated with this reduced section 136. The material cut to provide the perforations 138 is advantageously used to form the intermediate supports 1242. In other words, a perforation 138 is formed jointly with each support intermediate 1242, by folding and cutting the fuse blade 130. Of course, if necessary other perforations are made in the fuse blade 130.

Each of the intermediate supports 1242 is located outside the conduction path of the fuse blade 130, that is to say that no current flows through the intermediate supports 1242 when a current flows through the fuse blade 130.

A fuse 13 according to another embodiment of the invention is shown in insert b) of Figure 7. The fuse blade 130 comprises intermediate supports 1342 obtained in the same way as the intermediate supports 1242 of the embodiment previous, that is to say by cutting and folding the fuse blade 130, so as to jointly form the intermediate supports 1342 and the associated perforations 138.

The intermediate supports 1342 and the end supports 132A and 132B are here fixed to the wall 120 via spacers 140 similar to those of the first embodiment, that is to say comprising the central layer 144 integrating the plate 148 in ceramic metallized by DBC process.

A fuse 14 according to another embodiment of the invention is shown in insert a) of Figure 8. One of the main differences between this embodiment and the previous embodiment is that the spacer 140 comprises a central layer of the same type as the central layer 844 of the embodiment shown in 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 on the surface of the wall 120 at least over the entire projection, along the height axis Z100, of the fuse blade 130 on the wall 120.

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 reduced portions 136 adjacent to these ends. The connecting 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 connecting layer 752 between the central layer 844 and the corresponding intermediate support 1342 is here limited to the surface sufficient to ensure good attachment between this intermediate support 1342 and the central layer 844.

A fuse 15 according to another embodiment of the invention is shown in insert b) of Figure 8. One of the main differences between this embodiment and the previous embodiments is that the wall 120 saves, from the side of the internal volume V1 10, projections similar to the projections 502 of the embodiment illustrated in Figure 4 a), that is to say projections arranged opposite each spacer 140, so as to raise the fuse blade 130 relative to the rest of the wall 120.

As in the previous embodiment, the spacer 140 here comprises the central layer 844 formed of a polymer film, which is fixed on the wall 120 by following the contour of the wall 120. In particular, the central layer 844, glued using the connecting layer 852 to the wall 120, matches the profile of each of the projections 502. The fuse strip 130 is thus electrically separated from the wall 120 in a simple and economical manner.

A fuse 16 according to another embodiment of the invention is shown in 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 fuse blade by flexible conductors 160. On the other hand, the complementary portion 122 is here made in one part, and comprises, on the side of the internal volume V1 10, protrusions 162. Each of the protrusions 162, which are here seen in sections , 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 fuse blade 130 located opposite. The protrusions 162 are thus arranged facing the fuse blade 130, on the same side of the fuse blade 130. The protrusions 162 are arranged on either side of each reduced section 136, so as to limit the propagation of the arcs electrical in the internal volume when one of the reduced portions melts. In the example illustrated, a projection 162 is provided opposite each of the intermediate supports 142 and opposite each of the end supports 132A and 132B.

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

In the embodiments described, the wall 120 is made of a thermally conductive material, so as to evacuate the heat generated when a current Electricity circulates in the fuse blade. In the examples, the wall 120 is made of a metal plate, in particular copper, which presents a good compromise between thermal conductivity and cost, while being resistant to shocks. The wall 120 here being electrically conductive, the central layer 144 of the spacers 140 therefore comprises two opposite faces electrically insulated from one another. In the examples described, the spacer 140 comprises either a ceramic plate 148 or 448, or a polymer film 744 or 844.

In a variant not illustrated, 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 around 1.5 W/m-K), or even of hot injectable resin, in particular based on polyamide 6 - denoted PA6 -, or polyphenylene sulphide - denoted PPS -, or even polycarbonate - denoted PC -.

In the example illustrated, the fuse blade 130 is made in one 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.

In a variant not shown, the fuse blade is made in several pieces. For example, each piece comprises a single reduced section, interposed between two end supports, each of the end supports being fixed to the wall 120 by means of a spacer 140, so as to maintain the corresponding reduced section at a distance of Wall. Although it makes it possible to implement the advantages of the invention, this configuration is however not preferred because the assembly of each piece of fuse blade to the wall 120 is delicate and takes time.

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

As a variant not shown, the fuse blade 130 comprises two consecutive reduced sections 136 without intermediate support arranged between these two reduced sections. According to another variant, the fuse blade 130 comprises two intermediate supports, or even more, interposed between two consecutive reduced sections, like the fuse blade in Figure 6 b).

More generally, whether the fuse 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 comprises at least one support, whether it is an end support 132A, 132B, or an intermediate support 142, 942; 1342, by which this main portion

134 is fixed to the wall 120, this support being arranged so as to maintain the or one of the reduced sections 136 at a distance from the wall 120. Preferably, the support(s) are arranged to maintain each reduced section 136 of the main portion 134 considered at a distance from the wall 120. The fuse comprises 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 spacer 140 is associated with a single support. Alternatively, the same spacer 140 is inserted between the wall 120 and several neighboring supports.

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 maintain the two reduced sections 136 associated with this intermediate support at a distance from the wall 120.

Multiple configurations are possible, and those skilled in the art will be able to find the best compromise between rigidity of the fuse blade and size depending on development constraints. The embodiments and variants mentioned above can be combined with each other to generate new embodiments of the invention.

Claims

1. Fuse (100; ...; 900; 10;...; 16) comprising: a housing (110), the housing (110) comprising a wall (120) which is made of metal and which delimits an internal volume (V110) of the housing (110), the wall (120) being configured to be cooled by the outside of the housing (110), and a fuse blade (130), which comprises:

• a main portion (134), which is made in 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 fixed to the wall (120), the fuse comprises a spacer (140), which is interposed 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 one another, and

• two bonding layers (152), 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 (120), while the other connecting layer is fixed to each support, each support is arranged so as to maintain the reduced section (136) at a distance from the wall (120).

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

3. Fuse (900; 10; 15) according to any one of claims 1 or 2, in which: the fuse blade (130) comprises at least one support (942; 1042; 1142; 1242; 1342) which is provided so that this support is located outside the conduction path of the fuse blade (130) when a current flows in the fuse blade.

4. Fuse (10; 15) according to claim 3, in which: at least one of the supports (1042; 1142; 1242; 1342) comprises at least one support tab, each support tab being formed by cutting from the fuse blade (130) and having an elongated shape with a first end, which is connected to the fuse blade (130), and a second end, which is opposite the first end and which is fixed to the wall (120) by the corresponding spacer (140).

5. Fuse (12; 15) according to claim 4, in which, for at least one support tab (1242; 1342), this support tab is cut out in the vicinity of a reduced section (136), the cutout of this support tab forming a perforation (138) associated with this reduced section (136).

6. Fuse (900) according to claim 3, in which: the support (942) is formed by folding a folding zone (943) of the main portion (134), the folding zone extending over 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 zone is folded so as to form the support (942), while the two zones d The end (943A, 943B) are in electrical contact with each other.

7. Fuse (200; 300; 500) according to any one of claims 1 to 6, in which, 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 this reduced section, an insulating element (202; 302; 504) is interposed between this reduced section (136) and the wall (120), the insulating element closes , at least in part, an interval (154) between the two supports associated with this reduced section (136).

8. Fuse (400; 800; 14; 15) according to any one of claims 1 to 6, in which, 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 these two supports, the central layer of the two spacers is made in one piece, so as to close an interval between these two supports.

9. Fuse (700; 800; 14; 15) according to any one of claims 1 to 8, in which the central layer (744; 844) is made of an electrically insulating polymer material.

10. Fuse (100; 600; 900; 10; 13) according to any one of claims 1 to 8, in which the central layer (144) comprises a plate (148; 448) made of ceramic.

11. Fuse (600; 700; 800) according to any one of claims 1 to 10, in which pads (602) are interposed, between each spacer (140) and the fuse blade (130), so as to increase a distance between each reduced section (136) and the wall (120).

12. Fuse (500; 15) according to any one of claims 1 to 11, in which the wall (120) comprises projections (502), which are provided on the surface of the wall (120) and which are arranged in view of each spacer (140), so as to increase a distance between each reduced section (136) and the wall (120).

13. Fuse (16) according to any one of claims 1 to 12, in which: the housing (110) comprises, in addition to the wall (120), a complementary portion (122) of the wall (120), the complementary portion (122) is made of an insulating material and delimits, with the wall (120), the internal volume (V110) of the housing (1 10), for at least one of the reduced sections (136), the complementary portion of the housing (1 10) comprises at least two protrusions (162), which extend within the internal volume (V1 10) and which are arranged on either side of this reduced section (136), so as to limit the propagation of the arcs electrical in the internal volume (V110) when this reduced section (136) melts.