EP0928944A1 - A movable body accelerating electromagnetic device - Google Patents

Abstract

The e.g. cylindrical projectile (1) has a central waist with a conducting lining (3). Multiple radial strands of hard metal, e.g. bronze/cadmium alloy, rooted in the lining, form a resilient brush (2) sliding on the inner faces of longitudinal insulating guides (5) comprising the launch tube (4). Sets of conducting bars (6), connected (7,8) to current sources, e.g. charged capacitors, slide axially in the intervals between guides, driven e.g. by screw-jacks. The propulsive force derives from the transient current loops formed as the projectile brush passes between diametrically opposed pairs of contact bars connected to current source terminals of opposite polarity. By arranging bar pairs in helical sequence spin is imparted to the projectile.

Description

The present invention relates to an electromagnetic device allowing to accelerate a mobile conductor of electricity, intended especially to be used to launch a projectile.

The invention relates more particularly to a device of the type comprising means for supplying electric power to the mobile and accelerate it under the effect of so-called Laplace magnetic forces (again say of Lenz) and means to guide the mobile during its race acceleration.

There are known devices of this type, commonly called rail launchers, which have two parallel conductive rails electricity along which the projectile can slide by establishing a electrical contact between them. The electric current flowing through conductive rails creates a magnetic field which gives rise in the projectile with magnetic forces from Laplace (or Lenz).

This type of device makes it possible to obtain high speeds in output, of the order of 2 to 5 km / s for a projectile whose mass is between one hundred grams and several kilograms.

Taking into account the very high values of the current intensity necessary to obtain the desired acceleration, the two conductor rails are connected for example to a set of capacitors capable of restoring energy in a very short time considerable electrical.

Depending on the acceleration to be given to the projectile, we connect all or part of the capacitors on the conductor rails.

Connecting the capacitors is tricky, however. due to the particularly high values of the intensity of the running in game.

In addition, charging the capacitors may become difficult to manage when all the capacitors are not used.

The subject of the present invention is a new device which allows in particular to overcome the aforementioned drawbacks.

It achieves this by proposing a device to accelerate a mobile, of the type comprising guide means for guiding the mobile during its acceleration stroke and means for supplying the mobile with electric current and accelerate it under the effect of the magnetic forces of Laplace (or Lenz), characterized in that the means power supply have at least two segments conductors of electricity, each connected to an energy source electric and adjustable in position along the guide means so as to pass an electric current through the mobile when its passage in predetermined locations chosen according to the acceleration or speed to give to the mobile.

According to a preferred embodiment of the invention, each segment is connected to a capacitive electrical power source of constant nominal capacity.

Thanks to the invention, it is no longer necessary to modify the acceleration given to the mobile to act on the connections connecting the capacitors and conductor rails as it suffices to position differently the conductive segments to decrease or increase the value of the intensity of the electric current flowing through the mobile in one given location of its trajectory and the intensity of magnetic forces of Laplace (or Lenz) who exercise on it.

In a particular embodiment of the invention, the device comprises at least two segments placed in alignment one of the other with a spacing between them.

In a particular embodiment of the invention, the polarity and the positioning of the segments are chosen so as to cause the mobile to rotate on itself when it leaves the device.

In a particular embodiment of the invention, the device comprises screw jacks for driving in axial displacement the segments along the guide means.

In a particular embodiment of the invention, each segment is in the form of a section of rail guided in sliding by two slides in electrically insulating material.

In a particular embodiment of the invention, each segment participates in guiding the mobile.

In a particular embodiment of the invention, the segments are distributed angularly around a parallel geometric axis to the direction of acceleration of the mobile.

In a particular embodiment of the invention, each segment has an aluminum or copper substrate coated on its side intended to come into contact with the mobile of a silicon carbide deposit.

In a particular embodiment of the invention, the mobile has conductive strands on all or part of its periphery electricity, intended to establish sliding electrical contact with the segments.

The invention also relates to a projectile comprising on its entire periphery of the electrically conductive strands capable of establishing sliding electrical contact with the segments of a device electromagnetic as above.

• la figure 1 est une vue schématique en coupe axiale d'un projectile pouvant être utilisé dans un dispositif électromagnétique selon l'invention,
• la figure 2 est une vue en coupe transversale selon le trait de coupe II-II de la figure 1,
• la figure 3 est une vue schématique en perspective, partielle, représentant un dispositif électromagnétique conforme à un exemple de réalisation de l'invention,
• la figure 4 est une vue schématique et partielle, en coupe transversale, du dispositif représenté sur la figure 3,
• les figures 5 et 6 illustrent l'allure de l'intensité du courant électrique traversant le projectile en fonction de la position axiale de ce dernier pour deux exemples de positionnement relatif des segments.

Other characteristics and advantages of the present invention will emerge on reading the detailed description which follows, of a non-limiting embodiment of the invention and in view of the drawing in which:

• FIG. 1 is a schematic view in axial section of a projectile which can be used in an electromagnetic device according to the invention,
• FIG. 2 is a cross-sectional view along the section line II-II of FIG. 1,
• FIG. 3 is a partial schematic perspective view showing an electromagnetic device according to an exemplary embodiment of the invention,
• FIG. 4 is a schematic and partial view, in cross section, of the device shown in FIG. 3,
• Figures 5 and 6 illustrate the shape of the intensity of the electric current passing through the projectile as a function of the axial position of the latter for two examples of relative positioning of the segments.

FIGS. 1 and 2 show a projectile 1 intended to be used in an electromagnetic device according to the invention.

This projectile 1 comprises in a particular example describes a symmetrical body of revolution around an X axis and present on its periphery an annular groove in which a crown is retained electrically conductive 3, on the radially outer surface of which stand up strands 2 conductors of electricity, constituting a brush adapted to collect the electric current by sliding contact. These strands 2 are known in themselves, are preferably of the type described in the French patent 79 27526, and will be described in more detail below. Of course, the projectile can present, without leaving the frame of the invention, a non-symmetrical section of revolution, square by example.

FIGS. 3 and 4 show schematically a electromagnetic device 4 according to an exemplary embodiment of the invention. This device comprises means for guiding the projectile 1 along a geometrical axis Y confused during the launch with the axis X and means for supplying electric current to the projectile 1.

The guide means comprise a plurality of slides 5 straight lines made of an electrically insulating material. These slides 5 are distributed angularly around the Y axis.

The radially internal surface of the slides 5 is cylindrical of revolution around the Y axis and is used to guide the projectile during its acceleration race.

The slides 5 also constitute a guide structure for a plurality of segments 6 electrical conductors, connected each by a conducting wire 7 to one or more associated capacitors.

Each segment 6 can slide along the space formed between two adjacent slides 5.

The segments 6 comprise in the example described a substrate in aluminum or copper for example and, on the radially internal face intended to come into contact with the conductive strands 2, a deposit of silicon carbide.

This deposition can be carried out by centrifugation in particular.

Of course, it is not going beyond the ambit of the invention to use segments 6 made of other known and suitable materials.

The radially internal surface of the segments 6 is located in the continuity of the radially internal surface of the slides 5.

As an indication, the diameter of the projectile can be by example between 10 and 140 mm.

The length of the slides 5 can be for example 6 m, and the length of a segment 0.5 m.

A wide variety of means can be used to move parallel to the Y axis each of the segments 6.

One can for example use screw jacks.

There is shown in Figure 3 the axes A, B, C parallel to the Y axis of three screw jacks.

The cylinder screws are rotated on themselves by motor means known in themselves and not shown and are engaged in studs 8 integral with respective segments 6. The displacement of each segment can be controlled by a computer programmed to calculate, depending on the desired speed at the output of the device, the relative arrangement of the segments making it possible to reach this speed.

The studs 8 are crossed by threaded holes 9 in which engage the screws, and further serve, in the example described, at the connection of the wires 7.

Several segments 6 can be arranged in the extension one of the other.

By way of example, FIG. 3 shows two segments 6 arranged in alignment with each other with a spacing between them. These two segments 6 are driven in displacement simultaneously by the rotation of the B axis screw.

All segments 6 located on the same side of a diametrical plane containing the Y axis can have for example the same polarity and those located on the other side with the opposite polarity, as illustrated in figure 4, on which the neutral line N has been represented.

The segments 6 are positioned, preferably taking care that two segments of opposite polarities intended to come simultaneously to the projectile contact are substantially diametrically opposed.

In the case where there are several segments in the alignment of each other and where one seeks to rotate on itself the projectile at its exit from the device 4, the aligned segments have advantageously alternating polarities.

Referring again to Figures 1 and 2, the strands 2 are embedded at one end in the crown 3 and have a length in overhang preferably exceeding at least 10% the average spacing between the projectile 1 and the segments 6.

In this way, the bending deformation of the free end of the strands 2, which is flexible, maintains a contact pressure sufficient when sliding along a segment.

Preferably, the diameter of the strands 2 is between 60 μm and 100 µm and their length is less than 15 mm.

Preferably, the strands 2 are made of metal alloy hard, with good elasticity, for example in cadmium bronze or an alloy FeSi or copper and its alloys.

The strands 2 are obtained for example by drawing possibly a work hardening.

Electrically non-conductive strands can also be added for lubrication purposes for example.

The device 4 can be used in the following way.

The segments 6 are arranged for example around the Y axis along a double helix, that is to say that when we turn in a given direction around the Y axis, two successive segments of the same polarity are offset axially towards the exit of the device and the segments of opposite polarities are arranged symmetrically with respect to the Y axis.

By adjusting the position of each segment in relation to the segments adjacent poles, you can increase or decrease the length of overlap of two segments of the same polarity and act on the surface total of the segments coming simultaneously into contact with the projectile, therefore on the intensity of the current which will cross the projectile.

The position of the segments is chosen according to the intensity of current which must pass through the projectile at a given location in its launch course and acceleration resulting from the positioning of segments can be easily calculated by those skilled in the art.

The range of projectile 1 fire can be changed by playing on the speed of the projectile at the exit of the device 4 resulting from the positioning of segments 6.

After positioning the segments 6 according to the acceleration at give the projectile and charge the associated capacitors, we can introduce the projectile into the device.

The projectile then establishes an electrical contact between the two first segments of opposite and diametrically opposite polarities and finds it propelled towards the exit, establishing as it travels a contact between the following segments which accelerate it again.

FIG. 5 illustrates a configuration in which the first five segments of the same polarity overlap two by two by a distance l and the fifth and sixth segments of the same polarity follow one another by overlapping by a greater distance L.

We have also indicated in this figure the evolution of the intensity of the current passing through the projectile according to the axial position x of the latter along the Y axis.

FIG. 6 shows another example of configuration of the segments 6 in which the axial overlap of the first five segments of the same polarity is equal to L and the overlap of the fifth and sixth segments is equal to l .

It has been indicated by dotted lines in FIGS. 5 and 6 the intensity of the electric current resulting from the cumulation of the currents delivered by each of the segments.

Note that the fact that there is an axial overlap of two segments of the same polarity allows to accumulate in the area of recovery of the currents delivered by each of the segments through the projectile: it is possible through this to submit for example the projectile at a substantially constant intensity throughout its course acceleration if desired.

It will also be noted that the current delivered simultaneously by several segments of the same polarity can be greater than the maximum current debited by a segment.

To modify the trajectory of the projectile between two shots successive, there is no need to act on the nominal capacity and the charging of the capacitors producing the electric current flowing through the projectile.

It suffices in the invention to move the segments one by relation to the others so as to place them in a configuration which confers to the projectile the desired acceleration.

It must be understood that the invention offers very great freedom in the choice of the acceleration of the projectile.

The invention is not limited to the embodiment which has just been described and it is possible in particular to replace the screw jacks used to move the segments by equivalent means.

The shape of the projectile and the location of the strands are not limited to the examples which have just been described and moreover the content of the projectile can be arbitrary.

In addition, the electromagnetic device can be used according to the invention not to launch a projectile but to move an organ remaining guided all along its trajectory.

The number of segments 6 of the same polarity is equal to six in the example shown in Figure 4 but we can of course use a different number of segments 6 without departing from the scope of the invention.

We do not go beyond the scope of the invention by connecting the segments not to capacitors but to other current sources such as inductors.

Claims (12)

Electromagnetic device (4) for accelerating a mobile (1) electrically conductive, of the type comprising guide means for guide the mobile during its acceleration stroke and means for supply the mobile with electric current and accelerate it under the effect of Laplace (or Lenz) magnetic forces, characterized in that the electric current supply means comprise at least two electrically conductive segments (6), each connected to a source of electric energy and adjustable in position along the guide means (5) so as to pass an electric current through the mobile (1) during its passage in predetermined locations chosen according to acceleration or speed to give to the mobile. Device according to claim 1, characterized by the fact that each segment (6) is connected to a source of electrical energy capacitive with constant nominal capacity. Device according to claim 1 or 2, characterized by the that it has at least two segments (6) placed in alignment from each other with a spacing between them. Device according to any one of Claims 1 to 3, characterized by the fact that the polarity and the positioning of the segments (6) are chosen so as to cause the rotation on itself of the mobile (1). Device according to any one of Claims 1 to 4, characterized by the fact that it comprises screw jacks for driving in axial movement of said segments (6). Arrangement according to any one of claims 1 to 5, characterized in that each segment is in the form of a section of rail guided in sliding by one or more slides (5) made of insulating material. Device according to any one of Claims 1 to 6, characterized in that each segment (6) participates in guiding the mobile. Device according to any one of Claims 1 to 7, characterized in that the segments (6) are angularly distributed around a geometric axis (Y) parallel to the direction of acceleration of the mobile. Device according to any one of Claims 1 to 8, characterized in that each segment (6) comprises a substrate made of aluminum or copper coated on the side intended to come into contact with the mobile of a silicon carbide deposit. Device according to any one of the claims above, characterized in that said mobile (1) has on all or part of its periphery of the strands (2) intended to establish contact electric sliding with said segments (6). Device according to any one of Claims 1 to 10, characterized by the fact that said mobile is a projectile. Projectile (1) comprising a body and strands (2) for making sliding electrical contact with segments of a device electromagnetic launch, characterized in that said strands extend over the entire periphery of said body.

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