EP0014128A1 - A device to make an electrical and thermal contact between several metallic surfaces, and utilisation thereof - Google Patents

Abstract

The method according to the invention consists in winding a metal wire (1), substantially helically, both around a frame (2), constituted by a flexible strip, and around two rods (3), arranged parallel to the axis of the frame OO 'and on either side of the frame. The strips (3) are removed when the metal wire is wound. The frame (2) comprises means limiting the displacement of the wire along the axis of the frame (OO ') which coincides with the axis of the propeller along which the wire is wound. These means consist of two series of notches (4 and 5), made lengthwise, on two opposite edges of the strip constituting the frame. The devices obtained by the process according to the invention find their application in the field of microwave frequencies.

Description

The present invention relates to a method of manufacturing a device ensuring electrical and thermal contact between several metal surfaces. It also relates to the device obtained by this method and the application of this device to the microwave domain in particular.

It is known in the prior art to make electrical and thermal contact between two metal surfaces, which may for example be the surfaces of two coaxial cylinders constituting two connections of a microwave electronic tube of coaxial geometry, such as triodes and power tetrodes, using flexible blades. These blades are cut from strips of metal having a good coefficient of elasticity, then bent, and possibly heat treated; this is the case, for example, if beryllium bronze blades are used, the elasticity of which is increased by the heat treatment. These blades are then welded on one of the surfaces, generally in a groove dug on this surface and intended to retain the weld. The other surface is then placed in contact with the blades; an electrical and thermal contact is thus made between the two metal surfaces.

• - la grande surface de contact entre chaque lame et la surface en vis-à-vis, et le déplacement des points de contact d'une lame à l'autre, ce qui peut provoquer la création d'arcs électriques entre lames ;
• - la fragilité des lames qui sont détériorées si elles sont soumises à un glissement orthogonal à leur sens de flexion et qui ne permettent donc pas de réaliser un contact entre deux surfaces soumises à la fois à des mouvements de rotation et de translation ;
• - la difficulté de sa fabrication, il faut en effet prendre beaucoup de précautions lorsqu'on soude les lames pour ne pas leur faire perdre leur élasticité et leur revêtement protecteur ;
• - sa structure trop compacte (les lames ont généralement deux à trois millimètres de large et ne sont séparées que par un intervalle d'un millimètre environ) ; la ventilation du contact est donc diffile et nécessite l'utilisation de turbines très puissantes.

- Contact by flexible blades has many disadvantages, among which we can cite:

• - the large contact surface between each blade and the facing surface, and the displacement of the contact points from one blade to another, which can cause the creation of electric arcs between blades;
• - The fragility of the blades which are deteriorated if they are subjected to a slip orthogonal to their direction of flexion and which therefore do not allow contact to be made between two surfaces subjected to both rotational and translational movements;
• - the difficulty of its manufacture, it is indeed necessary to take a lot of precautions when welding the blades so as not to make them lose their elasticity and their protective coating;
• - its too compact structure (the blades are generally two to three millimeters wide and are only separated by an interval of about one millimeter); contact ventilation is therefore difficult and requires the use of very powerful turbines.

It is also known, in the prior art, to make electrical and thermal contact between two metal surfaces using a spring, housed in a groove hollowed out on one of the surfaces and held at the bottom of the groove by an elastic link. The other surface is then placed in contact with the spring, an electrical contact and .thermiαue is thus produced between the two metal surfaces.

Contact by spring has, compared to contact with flexible blades, the advantage of being punctual and of not requiring welding, moreover, its ventilation is easy because it consists of wire and not of metal plate. On the other hand, the spring contact has a great disadvantage which is its brittleness. Indeed, it deteriorates easily, especially during its installation, and in particular the turns do not remain uniformly apart. Contact by spring therefore does not allow, like contact by flexible blades, to make contact between two surfaces subjected to both rotational and translational movements.

The present invention relates to a method of manufacturing a device ensuring electrical and thermal contact between several metal surfaces which consists in winding, at least one metal wire, substantially helically, around a frame which comprises means limiting the movement of the wire along the axis of the armature, which coincides with the axis of the propeller along which the wire is wound; the various metal surfaces are in contact with the metal wire.

The device ensuring electrical and thermal contact between several metal surfaces, obtained by the method according to the invention, has, like the spring contact known in the prior art, the advantage of being punctual, of not requiring welding and be easy to ventilate. The device according to the invention also has, compared to the spring contact, the essential advantage of not being easily deformable because the means which limit the movement of the wire along the axis of the armature maintain a substantially uniform spacing between turns. The device according to the invention can therefore be easily used to make contact between several metal surfaces subjected to both rotational and translational movements.

• - la figure 1, une vue en perspective, illustrant le procédé de fabrication selon l'invention, d'un dispositif assurant un contact électrique et thermique entre plusieurs surfaces métalliques ;
• - les figures 2a, b, c, d, e, f, des vues de face de dispositifs assurant un contact électrique et thermique entre plusieurs surfaces métalliques illustrant différents modes d'application du procédé de fabrication selon l'invention ;
• - les figures 3, 4, 5, et 6, des vues de face et en perspective de différents modes de réalisation de dispositifs assurant un contact électrique et thermique entre plusieurs surfaces métalliques obtenus par le procédé de fabrication selon l'invention ;
• - les figures 7 à 14, des exemples d'application d'un dispositif assurant un contact électrique et thermique entre plusieurs surfaces métalliques obtenu par le procédé de fabrication selon l'invention.

Other objects, characteristics and results of the invention will emerge from the following description, given by way of nonlimiting example, and illustrated by the appended figures which represent:

• - Figure 1, a perspective view, illustrating the manufacturing method according to the invention, of a device ensuring electrical and thermal contact between several metal surfaces;
• - Figures 2a, b, c, d, e, f, front views of devices ensuring electrical and thermal contact between several metal surfaces illustrating different modes of application of the manufacturing method according to the invention;
• - Figures 3, 4, 5, and 6, front and perspective views of different embodiments of devices ensuring electrical and thermal contact between several metal surfaces obtained by the manufacturing process according to the invention;
• - Figures 7 to 14, examples of application of a device ensuring electrical and thermal contact between several metal surfaces obtained by the manufacturing process according to the invention.

In the different figures, the same references designate the same elements, but, for reasons of clarity, the dimensions and proportions of the different elements have not been respected.

Figure 1 shows a perspective view illustrating the manufacturing method according to the invention; a device ensuring electrical and thermal contact between several metal surfaces. A metal wire 1 is wound, substantially helically, both around a frame 2, which comprises means limiting the movement of the wire along the axis of the frame 00 ', which coincides with the axis of the propeller according to which the wire is wound, and around two rods 3 arranged parallel to the axis of the armature 00 '.

In FIG. 1, the armature is constituted by a flexible strip and the means limiting the movement of the wire along the axis of the armature are constituted by two series of notches 4 and 5, produced lengthwise, on two opposite edges of the flexible strip constituting the reinforcement. The metal wire 1 is introduced into the notches. The notches of the two series 4 and 5 can face each other, as shown in Figure 1, or not.

The various metallic surfaces, between which the device according to the invention provides electrical and thermal contact, are not shown in FIGS. 1 to 6. These surfaces are of course in contact with the metallic wire 1.

Figures 2a, b, c, d, e, f, show front views of devices ensuring electrical and thermal contact between several metal surfaces and illustrating different modes of application of the manufacturing method according to the invention. In these figures, the rods 3 are, as in Figure 1, arranged parallel to the axis of the frame 00 ', but their number, their size and their respective position vary.

In FIG. 2a, two rods 3, of different sizes, are arranged symmetrically on either side of the frame, the device obtained is therefore asymmetrical.

In FIG. 2b, two identical rods are arranged symmetrically on either side of the frame and at one of the ends of the frame, the device obtained is therefore substantially triangular.

In Figure 2c, two identical rods are arranged on either side of the frame but at different levels, the device obtained is inclined.

In FIG. 2d, four identical rods are arranged on either side of the frame. The rods occupy two by two symmetrical positions relative to the armature and the device is hexagonal.

In Figure 2e, only one rod is used.

In FIG. 2f, as in FIG. 2d, four identical rods are used and are distributed on either side of the frame. The rods have two by two a symmetrical position relative to the frame and each group of two rods is located at one end of the frame. The device obtained is therefore substantially rectangular. It can also be subjected to a heat or mechanical treatment which gives it a substantially coil shape, as shown in FIG. 2f.

The method according to the invention applies regardless of the number of rods 3, it also applies when the wire is wound only around the frame 2, that is to say when no rod is used.

FIG. 3 represents a front view of an embodiment of a device ensuring electrical and thermal contact between several metal surfaces which is obtained by the process according to the invention.

In FIG. 3, as in FIG. 1, the reinforcement 2 is constituted by a flexible strip, but the reinforcement shown in FIG. 3 comprises, in the direction of the length, on two opposite edges, two series of slots 8 and 9, perpendicular to the axis of the reinforcement 00 '. The slots of the two series 8 and 9 alternate on the frame.

The device shown in Figure 3 can be used flat disc-shaped, the slots of one of the series, the series 8 in Figure 3, overlap, while the slots of the other series, the series 9 in Figure 3, deviate, while the device shown in Figure 1 can only be used wrapped around a cylinder or in the form of a rectangular strip.

In FIG. 3, the means limiting the movement of the wire along the axis of the armature consist of two series of orifices, 6 and 7, drilled on the plate constituting the armature 2, lengthwise. The metal wire 1 is introduced into these orifices.

FIG. 4 represents a perspective view of an embodiment of a device ensuring electrical and thermal contact between several metal surfaces which is obtained by the method according to the invention.

In FIG. 4, the frame 2 is constituted by a sheet cut out in the form of a ring. Two rods 3 are arranged on either side of the frame, these rods are also in the form of a ring, they are made of plastic or in any other material which can be dissolved after winding.

In FIG. 4, the means limiting the movement of the wire along the axis of the armature 00 'consist of undulations 12, produced on two opposite edges of the plate constituting the armature and along the axis of the armature 00 '. The metal wire is introduced into the concavities 13 of the corrugations. In FIG. 4, two metallic wires 10 and 11 are wound in a helix, in an identical manner, and alternate on the armature. The number of metallic wires can be any.

FIG. 5 represents a perspective view of another embodiment of a device ensuring electrical and thermal contact between several metal surfaces which is obtained by the method according to the invention. The frame 2 is constituted by a wound wire, substantially helical, with contiguous turns. The means limiting the movement of the wire along the axis of the armature 00 'consist of a wire wound substantially in a helix 14, with non-contiguous turns, on the armature. The propellers of the frame and means limiting the movement of the wire can be flattened to limit the overall width of the device. The metal wire 1 ensuring the electrical contact between several metal surfaces is inserted into the space between two consecutive and non-contiguous turns of the propeller 14 constituting the means limiting the movement of the wire.

FIG. 6 represents another embodiment of a device ensuring electrical and thermal contact between several metal surfaces which is obtained by the process according to the invention.

A metal wire 23 is wound substantially in a helix both around the frame 2, which is constituted in this example by a flexible strip, and around at least a first rod arranged parallel to the axis of the frame 00 ', this wand is not shown in the figure. Another metallic wire 24 is then wound, substantially in a helix, both around the frame 2 and at least one second rod arranged parallel to the axis of the frame and on the other side of the frame. compared to the first wand. The device obtained has more solidity and makes it possible to prevent the deformations received by the metal wire located on one side of the frame from being transmitted to the metal wire located on the other side of the frame.

The device ensuring electrical and thermal contact obtained by the method according to the invention is used in numerous applications, in particular in the field of microwave frequencies. This device is thus used in microwave electronic tubes of coaxial geometry, such as power triodes and tetrodes used by radio and television transmitters, radars and industrial high frequency generators, to ensure electrical contact. and thermal between the surfaces of two coaxial cylinders constituting two connections of a tube. The device can then be housed in a groove hollowed out on the surface of one of the two cylinders. It can also be "fixed to the surface of one of the two cylinders, either as shown in FIG. 7, which is an exploded perspective view, by means of tabs 27 provided on the surface 28 which penetrate into oblong orifices 29, drilled on the frame 2, orthogonal to the axis 00 ′ of the frame, or by tabs 30 cut out on the frame 2, as shown in Figure 8, which is a perspective view of the frame, these tabs 30 then enter holes provided on the surface of one of the two cylinders.

This device can also be used, as shown in FIG. 9, to make an electrical contact between two walls 15 and 16 of a microwave coaxial cavity. The device 20 then serves as a piston. It is driven in translation, as shown by a double arrow in Figure 9, by a control rod.

• - soit mettre en place le dispositif 20 en forçant les spires de l'hélice, selon laquelle le fil 1 est enroulé, à se mettre en épi, par rapport à l'armature 2, comme représenté sur la figure 10, qui est une vue de dessus du dispositif 20 assurant un contact électrique entre les parois 15 et 16 d'une cavité coaxiale hyperfréquence, et qui est représenté vu en perspective sur la figure 9 ;
• - soit utiliser un dispositif tel que celui représenté sur la figure 6 qui est réalisé en deux étapes et qui présente une grande souplesse d'utilisation.

So that the device 20 ensures contact between the walls 15 and 16, whatever the variations in the diameter of these walls and their eccentricity, it is necessary:

• - Either set up the device 20 by forcing the turns of the propeller, according to which the wire 1 is wound, to stand on the cob, relative to the frame 2, as shown in Figure 10, which is a view from above the device 20 ensuring electrical contact between the walls 15 and 16 of a microwave coaxial cavity, and which is shown seen in perspective in FIG. 9;
• - Either use a device such as that shown in Figure 6 which is carried out in two stages and which has great flexibility of use.

To make electrical contact between two walls 15 and 16 of a microwave coaxial cavity, one can also use, as shown in FIG. 11 which is a perspective view, two devices 20, obtained by the method according to the invention, and mounted in two grooves 31 located on either side of a piston 32 The devices 20 are connected to the piston by their armature 2. It is possible to use to accommodate the devices 20 grooves 31 of rectangular shape, or of triangular shape, as shown in FIG. 11. The grooves of triangular shape have the 'Advantage when the devices 20 are substantially diamond-shaped, as shown in Figure 11, to allow very good ventilation of the contacts thanks to the space between each device 20 and the piston 32. In addition, with the triangular grooves, the devices 20 are in contact with two sides of the grooves and therefore follow the slightest displacements of the piston 32, which is not the case for the rectangular grooves with which it is difficult to make a fine adjustment of the position of the piston, because the devices 20 do not ensure good contact with the piston, especially since it is necessary to provide a clearance between the armature and the piston to leave the armature free to change dimensions. The piston is of course movable in translation as shown by a double arrow in FIG. 11.

The device obtained by the method according to the invention can be used to make electrical and thermal contact between several metallic surfaces, four metallic surfaces, for example, for the substantially hexagonal device, shown seen from the front in Figure 12.

The four surfaces A, B, C, D, are based on the sides a, b, c, d, of the hexagon, these surfaces A, B, C, D, may or may not be animated with rotational movements.

The device obtained by the method according to the invention can be housed, as shown in FIG. 13, in a helical groove 21 provided on the surface of one of the two parts between which the device 20 provides electrical and thermal contact. This groove 21 makes it possible to increase the surface of the contact produced by the device 20 between the two parts 18 and 19. In FIG. 13, the part 19 comprises cooling fins 22. The device 20 shown in FIG. 13 ensures contact between parts 18 and 19 which can be subjected to both rotational and translational movements.

It is also possible to make a thread of the part 18. The two parts 18 and 19 can then be screwed into one another by means of the device 20 and the contact thus produced is fixed.

It is also possible to superimpose several devices 20 in order to increase the surface of the contact made between several metal parts.

• Le dispositif 20 comporte une armature 2 constituée d'une bande flexible en bronze au béryllium de 0,2 mm d'épaisseur. L'armature des dispositifs selon l'invention est généralement métallique, ce qui permet de diminuer la self de contact entre le fil métallique et l'armature, mais on doit signaler que l'armature peut être aussi réalisée en matériaux isolants, tels que du polytétrafluoroéthylène. Sur l'armature 2, on a donc bobiné, sensiblement en hélice, un fil métallique 1 en tungstène, de 0,33 mm de diamètre. Deux baguettes de mise en forme, cylindriques, de 2,5 mm de diamètre ont été utilisées pour bobiner le fil et ensuite supprimées. Le dispositif 20 est logé, comme représenté sur la figure 14, dans une gorge de hauteur h égale à 9 mm, creusée dans une pièce métallique 25. Un piston 26 de diamètre D égal à 77 mm est en contact avec le dispositif 20. Ce piston peut se déplacer en rotation et en translation, comme indiqué sur la figure 14, par des flèches.

A nonlimiting exemplary embodiment of the object of the invention, illustrated by FIG. 14, gave the following results:

• The device 20 comprises an armature 2 consisting of a flexible strip of beryllium bronze 0.2 mm thick. The framework of the devices according to the invention is generally metallic, which reduces the contact inductance between the metal wire and the frame, but it should be noted that the frame can also be made of insulating materials, such as polytetrafluoroethylene. On the frame 2, a metallic wire 1 made of tungsten, 0.33 mm in diameter, was therefore wound, substantially helically. Two forming rods, cylindrical, 2.5 mm in diameter were used to wind the wire and then removed. The device 20 is housed, as shown in FIG. 14, in a groove of height h equal to 9 mm, hollowed out in a metal part 25. A piston 26 of diameter D equal to 77 mm is in contact with the device 20. This piston can move in rotation and in translation, as indicated on figure 14, by arrows.

A current of 200 amperes is established between parts 25 and 26, which are made of brass. The recorded voltage drop is only 28 millivolts, whereas it would be at least 50 millivolts if the contact between the metal surfaces of parts 25 and 26 was established by devices according to the prior art. Finally, after an hour and a half of operation, the temperature of the rooms 25 and 26 does not exceed 40 degrees Celcius, because the device according to the invention allows good ventilation to be easily achieved.

Claims (18)

1. A method of manufacturing a device ensuring electrical and thermal contact between several metal surfaces, characterized in that it consists in winding, at least one metal wire (1), substantially helically, around a frame (2 ) which includes means limiting the movement of the wire along its axis (00 '). 2. Method according to claim 1, characterized in that, during this winding, each metal wire (1) is kept apart from the frame (2), at some of its points, by at least one rod (3) , arranged parallel to the axis of the armature (00 '), this strip being removed after the winding of the wire. 3. Method according to claim 2, characterized in that it comprises two stages, during which at least one metal wire (23, 24) is wound around the frame (2) and around at least one rod ( 3), the rods used during the two stages being arranged on either side of the frame. 4. Device ensuring electrical and thermal contact between several metal surfaces, characterized in that it is obtained by the method according to one of claims 1 to 3. 5. Device according to claim 4, characterized in that the frame (2) is constituted by a flexible strip. 6. Device according to claim 4, characterized in that the frame (2) is constituted by a leaf cut in the shape of a ring. 7. Device according to one of claims 5 or 6, characterized in that the means limiting the movement of the wire along the axis of the armature consist of two series of notches (4, 5), produced on two opposite edges of the frame, and in that the metal wire (1) passes through the notches. 8. Device according to one of claims 5 or 6, characterized in that the means limiting the movement of the wire along the axis of the frame, are constituted by two series of orifices (6, 7), drilled on the armature, and in that the metal wire (1) passes through the holes. 9. Device according to one of claims 5 or 6, characterized in that the means limiting the movement of the wire along the axis of the armature consist of undulations (12), produced on two opposite edges of the 'armature and in that the metal wire (1) passes through the concavities (13)' corrugations. 10. Device according to claim 5, characterized in that the flexible strip constituting the frame comprises, on two opposite edges, two series of alternating slots (8, 9). 11. Device according to claim 4, characterized in that the armature consists of a wire wound substantially in a helix, with contiguous turns. 12. Device according to one of claims 5, 6 or 11, characterized in that the means limiting the movement of the wire along the axis of the armature consist of a wire, wound substantially helically (14) with non-contiguous turns, on the armature, the metal wire (1) ensuring contact between several metal surfaces being inserted in the space between two of the turns consecutive non-contiguous. 13. Device according to one of claims 4 to 12, characterized in that the frame (2) has fixing holes (29). 14. Device according to one of claims 4 to 12, characterized in that the frame (2) has fixing lugs (30). 15. Microwave coaxial cavity, characterized in that it comprises a device (20) according to one of claims 4 to 14 ensuring electrical and thermal contact between two walls (15, 16) of the cavity. 16. Cavity according to claim 15, characterized in that the device (20) is mounted between two walls (15, 16) so that the turns of the propeller, according to which the metal wire (1) is wound, are arranged in spikes relative to the frame (2). 17. Microwave coaxial cavity, characterized in that it comprises two devices (20) according to one of claims 4 to 14 ensuring electrical and thermal contact between a piston (32) and one of the walls (15, 16) of the cavity, the devices (20) being housed in grooves (31) of triangular shape. 18. Microwave electronic tube of coaxial geometry, characterized in that it comprises a Device (20) according to one of claims 4 to 14 ensuring electrical and thermal contact between two coaxial cylinders constituting connections of the tube.

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