EP1363304A1 - Opening switch with explosive wire and method of manufacture - Google Patents

Abstract

The switch includes a body (6) occupying a volume delimited by a cylinder, with lines of conductors (5) placed in the body, these conductors extending in the radial direction towards the exterior casing (6C) of the body. The lines are connected to a central conductor (1) which is located at the axis of the cylinder on one part, and to a mass (2) at the level of the envelope exterior to the body on the other part, these conductor lines destined to be ruptured during the passage of an electric current between the central conductor and the mass.

Description

The present invention relates to a switch with opening of type with exploded wires and a manufacturing process. It applies in particular switches used in high pulsed power systems.

Such a switch is typically used in a circuit electric comprising a high impedance load and a power supply low impedance. The switch is initially conductive. In others terms, its resistance before switching is almost zero. The switch short-circuits the load. The power supplies a current crescent flowing through the switch. At a given time, the switch opens. In other words, when switching its resistance tends to infinity. At this moment all the current flows in the charge.

The switch thus makes it possible to format a pulse of current. More precisely, it makes it possible to reduce the duration of the rising edge and increase the voltage across its terminals. A switch ideally has a resistance before switching as low as possible, resistance after highest possible switching time, and the longest switching time weak possible.

There are several families of opening switches: pyrotechnic switches, plasma switches ("plasma opening switch "in Anglo-Saxon literature), wire switches exploded. Pyrotechnic switches use a system dihedral hollow charge type pyrotechnics to cut a driver. In plasma switches, the conductive phase is due to a plasma that is interrupted to open the switch. The exploded wire switches initially include metallic wires conductors in which the flow of current causes an increase in temperature that melts and then vaporizes the conductor. The resistivity of son increases considerably which ensures the function of switching.

One problem with these switches is that they occupy a volume important. The present invention aims to optimize the volume occupied by the Explosive wire type opening switches, the volume allocated to these switches being a substantially cylindrical volume.

The invention consists in distributing the active volume of the switch (conductive lines) homogeneously in the allocated volume. Through elsewhere one of the proposed solutions has advantages in terms industrialization.

• un corps occupant sensiblement un volume délimité par un cylindre ;
• des lignes conductrices placées dans le corps, les lignes conductrices s'étendant dans une direction radiale vers l'enveloppe extérieure du corps, les lignes conductrices étant destinées à être reliées à un conducteur central sensiblement sur l'axe du cylindre d'une part, et à une masse au niveau de l'enveloppe extérieure du corps d'autre part, les lignes conductrices étant destinées à être rompues lors du passage d'un courant électrique entre le conducteur central et la masse.

To this end, the opening switch comprises at least:

• a body occupying substantially a volume delimited by a cylinder;
• conductive lines placed in the body, the conductive lines extending in a radial direction towards the external envelope of the body, the conductive lines being intended to be connected to a central conductor substantially on the axis of the cylinder on the one hand, and to a ground at the level of the external envelope of the body on the other hand, the conducting lines being intended to be broken during the passage of an electric current between the central conductor and the ground.

According to a first advantageous embodiment, the lines conductive form axial undulations. According to a second mode of advantageous embodiment, the conductive lines describe turns around of the cylinder axis. These first and second embodiments can be implemented independently or together.

• on réalise des pistes conductrices par gravure sur un film souple dont la surface est le développement d'un cône, ce film étant à plat lors de la réalisation de ces pistes ;
• on génère une forme conique à partir de cette surface ;
• on réalise des repliements du cône dans une direction axiale.

The invention also relates to a method for manufacturing a switch in which:

• conductive tracks are produced by etching on a flexible film whose surface is the development of a cone, this film being flat during the production of these tracks;
• a conical shape is generated from this surface;
• the cone is folded in an axial direction.

• la figure 1, une vue de dessus, représente un commutateur à ouverture de type à fils explosés classique ;
• la figure 2, une vue de dessus, représente un exemple de commutateur selon l'invention ;
• la figure 3, une section, représente le commutateur de la figure 2 ;
• la figure 4, une perspective éclatée, représente des éléments formant le commutateur de la figure 2 ;
• la figure 5, une vue en perspective, représente un film souple isolant formant un cône ;
• les figures 6 à 9, des vues en perspectives, représentent des étapes de pliage du film souple isolant de la figure 5 pour obtenir un élément de la figure 4 ;
• la figure 10, une vue de dessus, représente un mode de réalisation avantageux dans lequel les lignes conductrices forment des spires ;
• la figure 11, une vue en perspective, représente un support isolant souple formant un cône, sur lequel sont déposées des pistes conductrices formant des spires ;
• la figure 12, une vue de dessus dans un plan muni d'un quadrillage régulier, représente un support isolant souple plan destiné à former le cône représenté sur la figure 11.

Other characteristics and advantages of the invention will become apparent from the following description given with reference to the appended drawings:

• Figure 1, a top view, shows an opening switch type of conventional exploded son;
• Figure 2, a top view, shows an example of a switch according to the invention;
• Figure 3, a section, shows the switch of Figure 2;
• Figure 4, an exploded perspective, shows elements forming the switch of Figure 2;
• Figure 5, a perspective view, shows a flexible insulating film forming a cone;
• Figures 6 to 9, perspective views, show steps of folding the flexible insulating film of Figure 5 to obtain an element of Figure 4;
• Figure 10, a top view, shows an advantageous embodiment in which the conductive lines form turns;
• Figure 11, a perspective view, shows a flexible insulating support forming a cone, on which are deposited conductive tracks forming turns;
• FIG. 12, a top view in a plane provided with a regular grid, represents a flat flexible insulating support intended to form the cone shown in FIG. 11.

We now refer to Figure 1. A wire switch exploded generally includes at least one wire 4 stretched over a frame insulating plane 3. One end of this wire is intended to be connected to a ground. The other end is intended to be connected to a hot spot, i.e. to a point of high potential. Several wires of the same length can be mounted in parallel in planes parallel to the insulating frame. Such a switch is not optimized to occupy a substantially cylindrical volume.

Referring now to Figures 2 and 3. According to the invention, the switch has a body 6 which occupies substantially a volume delimited by a cylinder with an axis 10. According to one embodiment (not shown), the body includes an insulator on which conductive lines are deposited. These conductive lines can be formed by filaments of a few tens of micrometers in section for example.

In switches used in high systems pulsed power, a large number of lines are preferably used conductors (of the order of a hundred) of small cross section (of the order of one ten micrometers). Indeed, the switching time is all the more weak as the section is weak. And, the amount of energy that can be the greater the sum of the sections of the conductive lines is important.

According to an advantageous embodiment which is particularly suitable switches used in high pulsed power systems, the conductive lines are formed by tracks engraved on a support insulating. They can be engraved on an intermediate insulating support as described in connection with Figure 4 or directly on the insulator. They can be made for example by photoengraving.

According to an advantageous embodiment (not shown), the body includes several insulators between which the lines are located conductive. Each insulator separates two layers of conductive lines. The conductive lines can be parallel between the layers successive. According to another embodiment (shown in Figures 2 and 3) the body consists of a single layer of conductive lines and two insulators 6A, 6B between which the conductive lines are located.

The conductive lines are placed in the body 6. They extend in a radial direction with respect to the axis 10 of the cylinder towards the outer casing 6C of the body. The conductive lines are intended for be connected to a central conductor 1 substantially on the axis 10 of the cylinder on the one hand, and to a mass 2 at the level of the outer casing 6C of the body on the other hand.

The invention leads to a coaxial structure at the potential with high potential on axis 10 and mass on the outside. This switch is thus suitable for a supply or a load of coaxial geometry.

The central conductor can be a rigid connector such as a metal rod. The body 6 may include a recess 11 substantially on axis 10 to accommodate the central conductor 1. Obviously 11 may have the shape of a cylinder with an axis 10. According to a variant of realization, the body does not understand obviously but includes a point of contact on its external surface, this point of contact being substantially positioned at axis 10. The central conductor is then shaped adapted to this point of contact. So the end of the conductive lines connected to the central conductor 1 is either substantially on the axis 10 (body without obviously), or close to this axis (body with obviously).

According to an advantageous embodiment, illustrated in FIG. 3, the conductive lines 5 form axial undulations. These ripples may for example be formed by a substantially sinusoidal curve. According to another embodiment, they can be formed by straight segments arranged in W and connected by rounds. In others terms, the conductive lines are folded in a direction parallel to axis 10. This makes it possible to generate longer conducting lines while retaining a switch which occupies a substantially delimited volume by a cylinder of the same radius. This geometry has two advantages.

First, knowing that the potential is distributed linearly along the conductive lines, the arrangement described above allows to optimize the electric field levels in the dielectric volumes and thus minimizing the risk of breakdown.

Second, we form undulations and not folds. We avoid peak effects and therefore to have intense electric fields. In other words, thanks to this advantageous geometry of the lines conductive, we limit the electric field levels while keeping a compact switch.

Advantageously, the body comprises at least two insulators recessed between which the conductive lines are located. We are growing thus the dielectric strength of the switch. Isolators 6A, 6B separate as illustrated in Figure 3 the successive undulations. Thanks to their corrugated forms, the insulators have the effect of limiting breakdown by rampage. The rampage breakdown, specific to solid dielectrics, is a breakdown in which the current takes a geometric path to the surface of a solid dielectric.

We now refer to Figure 4. The switch can include a flexible insulating film 7 on which tracks are engraved forming the conductive lines. For example the film can be a sheet in plastic such as a polyimide sheet (known as Kapton commercial), the conductive lines being produced by a depot of copper. This insulating film can thus be easily folded, which allows generate the axial undulations of the conductive lines without risking them to break up. This embodiment is particularly suitable for lines conductors of small cross-section.

Advantageously, the insulating film substantially forms a cone folded. This allows to generate ripples in W as described more high. There is also an advantageous structure in terms industrialization.

• on réalise les pistes conductrices 5 par gravure sur un film souple dont la surface est le développement d'un cône, ce film étant à plat lors de la réalisation de ces pistes ;
• on découpe et on colle deux bords de ce film de manière à générer une forme conique comme illustré sur la figure 5 ;
• on réalise des repliements du cône dans une direction axiale comme illustré sur les figures 6 à 9, en veillant à conserver un arrondi au niveau des repliements ;
• on insère ce film gravé et replié entre deux isolateurs 6A et 6B.

Advantageously, one can proceed as follows:

• the conductive tracks 5 are produced by etching on a flexible film whose surface is the development of a cone, this film being flat during the production of these tracks;
• two edges of this film are cut and glued so as to generate a conical shape as illustrated in FIG. 5;
• folding of the cone is carried out in an axial direction as illustrated in FIGS. 6 to 9, taking care to maintain a roundness at the level of the folding;
• this engraved and folded film is inserted between two insulators 6A and 6B.

According to an implementation variant, the isolators 6A and 6B being rigid insulators, we can generate the folds of the film (and by consequent conductive lines) by embedding the insulators one in the other, the flexible film located between said insulators.

We now refer to FIG. 10 which presents a mode of advantageous realization. Conductive lines 5 describe turns around of axis 10 of the cylinder. The conductive lines 5 can also form axial undulations as indicated above. Of course, the lines conductors can simply describe turns in a plane without form axial ripples. This increases the length of the lines without increasing the volume occupied by them. It is possible to adjust their length by changing the number of turns.

We now refer to Figure 11 in which is represented a flexible insulating support forming a cone. It is possible to combine the advantageous embodiments so as to obtain undulations axial and turns using a folded cone on which are engraved turns. We can thus reach a typical line length of 4 meters in a small footprint.

We now refer to Figure 12 on which is represented between edges 20,21,22,23 shown in dotted lines a surface developed from a cone. The edges 21 and 23 of this surface are intended to be glued to generate a conical surface. The edge 20 is intended for form the base of the cone (circle), and the edge 21 the top of the cone (circle). The conductive lines 51, 52, 53, 54 in this example form a half turn.

The grid in Figure 12 is a unit grid: each box has a vertical side of length 1 and a horizontal side of width 1. We use a Cartesian coordinate system in X (horizontal) and Y (vertical) to locate in this grid. The solid and dotted curves have the equation: x 0 = (r 2 -r 1 ) T + r 1 sin (γ) cos ((2πNt - ϕ 0 ) Sin (γ)) there 0 = (r 2 -r 1 ) T + r 1 sin (γ) sin ((2πNt - ϕ 0 ) Sin (γ)) x 1 = (r 2 -r 1 ) T + r 1 sin (γ) cos ((2πNt - ϕ 1 ) Sin (γ)) there 1 = (r 2 -r 1 ) T + r 1 sin (γ) sin ((2πNt - ϕ 1 ) Sin (γ)) x 2 = (r 2 -r 1 ) T + r 1 sin (γ) cos ((2πNt - ϕ 2 ) Sin (γ)) there 2 = (r 2 -r 1 ) T + r 1 sin (γ) sin ((2πNt - ϕ 2 ) Sin (γ)) x 5 = (r 2 -r 1 ) T + r 1 sin (γ) cos ((2πNt - ϕ 5 ) Sin (γ)) there 5 = (r 2 -r 1 ) T + r 1 sin (γ) sin ((2πNt - ϕ 5 ) Sin (γ)) x 6 = r 1 sin (γ) cos (((φ 0 - ϕ 5 ) t - ϕ 0 ) Sin (γ)) there 6 = r 1 sin (γ) sin (((φ 0 - ϕ 5 ) t - ϕ 0 ) Sin (γ)) x 7 = r 2 sin (γ) cos (((φ 0 - ϕ 5 ) t - ϕ 0 + 2πN) sin (γ)) there 7 = r 2 sin (γ) sin (((φ 0 - ϕ 5 ) t - ϕ 0 + 2πN) sin (γ))

h : la hauteur du cône (3) ;

r₁ : le rayon du cercle formant la partie supérieure du cône (0,5) ;

r₂ : le rayon du cercle formant la base (2) ;

N : le nombre de spires (0,5) ;

ϕ₀ : la position angulaire du bord 23 (-π/4) ;

ϕ₁ : la position angulaire de la ligne conductrice 51(0) ;

ϕ₂ : la position angulaire de la ligne conductrice 52 (π/2) ;

ϕ₃ : la position angulaire de la ligne conductrice 53 (π) ;

ϕ₄ : la position angulaire de la ligne conductrice 54 (3π/2) ;

ϕ₅: la position angulaire du bord 20 (2π-π/4).

In which we use parameters, whose values taken in figure 12 are indicated in brackets, which represent:

h: the height of the cone (3);

r ₁ : the radius of the circle forming the upper part of the cone (0.5);

r ₂ : the radius of the circle forming the base (2);

N: the number of turns (0.5);

ϕ ₀ : the angular position of the edge 23 (-π / 4);

ϕ ₁ : the angular position of the conductive line 51 (0);

ϕ ₂ : the angular position of the conductive line 52 (π / 2);

ϕ ₃ : the angular position of the conductive line 53 (π);

ϕ ₄ : the angular position of the conductive line 54 (3π / 2);

ϕ ₅ : the angular position of the edge 20 (2π-π / 4).

t : une grandeur variant de 0 à 1 pour décrire les courbes 20, 21, 22, 23, 51, 52, 53, 54 ;

x₀ et y₀ : les coordonnées des points décrivant la courbe 23 ;

x₁ et y₁ : les coordonnées des points décrivant la courbe 51 ;

x₂ et y₂: les coordonnées des points décrivant la courbe 52 ;

x₃ et y₃ : les coordonnées des points décrivant la courbe 53 ;

x₄ et y₄ : les coordonnées des points décrivant la courbe 54 ;

x₅ et y₅ : les coordonnées des points décrivant la courbe 21 ;

x₆ et y₆ : les coordonnées des points décrivant la courbe 22 ;

x₇ et y₇ : les coordonnées des points décrivant la courbe 20.

In which we use variables which represent: sin (γ): the quantity 1 1+ h 2 (r 2 -r 1 ) 2 ;

t: a quantity varying from 0 to 1 to describe the curves 20, 21, 22, 23, 51, 52, 53, 54;

x ₀ and y ₀ : the coordinates of the points describing the curve 23;

x ₁ and y ₁ : the coordinates of the points describing the curve 51;

x ₂ and y ₂ : the coordinates of the points describing the curve 52;

x ₃ and y ₃ : the coordinates of the points describing the curve 53;

x ₄ and y ₄ : the coordinates of the points describing the curve 54;

x ₅ and y ₅ : the coordinates of the points describing the curve 21;

x ₆ and y ₆ : the coordinates of the points describing the curve 22;

x ₇ and y ₇ : the coordinates of the points describing the curve 20.

It is possible to increase or decrease the length of the lines conductive by increasing or decreasing the value of the parameter h, it is to say the height of the cone. By doing so, you don't change the radial size of the switch. We can keep the thickness of the constant switch by increasing the number of cone folds (which increases the density of the switch) when the value is increased of the parameter h.

When the parameter N is zero, the conductive lines do not describe more turns but straight lines. This corresponds to the mode of realization shown in Figures 2 to 5. The number N can take any value positive (turns in the direction illustrated in Figure 12) or negative (turns in the other direction).

It is possible to increase or decrease the length of the lines conductive by increasing or decreasing the absolute value of the parameter N, i.e. the number of turns. By doing so, you don't change not the size of the switch.

If the number of turns becomes large, the self induced by the Current flow in the conductive lines can become troublesome. Advantageously, one can compensate for this self by carrying out turns in the opposite direction with another layer of conductive lines. In in other words, part of the conductive lines describe turns in one direction and the other part of the conductive lines describe lines in the other direction. Preferably, as many conductive lines are used to describe turns in one direction than in the other direction.

The guidelines that describe turns in one direction can be placed on one side of an insulating support, the conductive lines describing turns in the other direction being deposited on the other side. This insulating support can be a flexible film or a rigid insulator or any other support.

If the cone is generated from a flexible film on which the tracks are engraved flat, we will have to make junctions either for the turns that cross edges 21 and 23. To avoid having to make junctions, one can start directly from a flexible film cone on which are engraved tracks. The tracks are then no longer engraved flat, which is more difficult to achieve, but there is no need to join.

According to an advantageous embodiment, the conductive lines describing turns in one direction are deposited on a first support insulating, the conductive lines describing turns in the other direction are deposited on a second insulating support. This embodiment allows avoid having to make junctions of conductive lines while keeping the possibility of engraving the tracks flat. Advantageously, the first and the second insulating support are nested one inside the other.

Claims (13)

Opening switch characterized in that it comprises at least: a body (6) occupying substantially a volume delimited by a cylinder; conductive lines (5) placed in the body, the conductive lines extending in a radial direction towards the outer envelope (6C) of the body, the conductive lines being intended to be connected to a central conductor (1) substantially on the axis (10) of the cylinder on the one hand, and a mass (2) at the level of the external envelope of the body on the other hand, the conducting lines being intended to be broken during the passage of an electric current between the central conductor and the ground. Switch according to the preceding claim, characterized in that the conductive lines form axial undulations. Switch according to the preceding claim, characterized in that the body comprises at least two insulators (6A, 6B) embedded between which the conductive lines are located, the insulators separating the successive undulations of the conductive lines. Switch according to any one of the preceding claims, characterized in that the conductive lines are formed by filaments. Switch according to any one of claims 1 to 3, characterized in that the conductive lines are formed by tracks deposited on an insulating support. Switch according to the preceding claim, characterized in that the insulating support is a flexible film (7). Switch according to the preceding claim, characterized in that the flexible film substantially forms a folded cone. Switch according to any one of the preceding claims, characterized in that the conductive lines describe turns (51, 52, 53, 54) around the axis of the cylinder. Switch according to the preceding claim, characterized in that part of the conductive lines describe turns in one direction and the other part of the conductive lines describe turns in the other direction. Switch according to claim 9, characterized in that the conductive lines describing turns in one direction are deposited on one side of an insulating support, the conductive lines describing turns in the other direction are deposited on the other side of the insulating support. Switch according to claim 9, characterized in that the conductive lines describing turns in one direction are deposited on a first insulating support, the conductive lines describing turns in the other direction are deposited on a second insulating support. Switch according to the preceding claim, characterized in that the first and the second insulating support are fitted one inside the other. Method of manufacturing a switch characterized in that : conducting tracks (5) are produced by etching on a flexible film (7) the surface of which is the development of a cone, this film being flat when these tracks are produced; a conical shape is generated from this surface; the cone is folded back in an axial direction (10).

Images