EP1494323B1 - Process for manufacturing insulated conductive elements of a rotating electrical collector and rotating electrical collector with the electric conductive elements - Google Patents

Abstract

Method involves covering electrically conductive element (14) with one or more layers of electrically-insulating enamel (42), baking the element so as to cure the layer(s) of enamel, and mounting the element on a carrier structure of the collector. Electric continuity zone (43) of electrically conductive element is then treated so as to remove the layer(s) of enamel. Independent claims are also included for the following : (1) an electrically conductive element; (2) a collector.

Description

The invention relates to a method of manufacturing electrically conductive elements isolated from rotating collector and a rotating collector for the spatial domain comprising these electrically conductive elements.

Rotary manifolds are used to transfer electrical power or signals between moving parts relative to each other. They generally comprise a fixed carrier structure, called a stator, supporting conductive wires called eyelashes, and a rotating part, the rotor, carrying a plurality of cylindrical conductive tracks on which the ends of the eyelashes are in electrical contact. The eyelashes on the one hand, the tracks on the other hand, are connected to electrical conductors through which the power or the signals pass. The conductive yarns or eyelashes are generally made of copper, gold, platinum, copper alloy, gold alloy or platinum alloy.

In other types of collectors, the power or the electrical signals are transferred from the fixed part to the mobile part by brushes which rub with a cylindrical or flat conductive track. These brushes are mounted on flexible brush holders.

The eyelashes and the brush supports constitute electrically conductive elements within the meaning of the present invention. Since they are drivers, they must be isolated from each other. This isolation is currently performed by spacing the eyelashes or brush holders between them. This solution has the disadvantage of being sensitive to pollution by particles or a conductive plasma which can cause short circuits between eyelashes or adjacent brush holders. In the space domain to which the invention applies, such risks are not permissible in view of the required reliability.

The document US Patent 2681564 discloses a method of manufacturing an element according to the preamble of claim 1.

The document DE-1,613,183 describes elastic arms. At their end is brazed pad in rubbing contact on a conductive track. The elastic element is constituted by the conductor itself which is surrounded by an insulating sheath of flexible synthetic material.
However, the presence around the conductor of an insulating sheath of a certain thickness (usually of the order of 100 .mu.m), disrupts the force of application of the arms on the conductive track. In addition, in the case of use in the spatial field, the insulating material must maintain a good mechanical strength at high temperature.

The present invention relates to a method of manufacturing insulated electrically conductive elements, particularly eyelashes and collector brush supports and a rotating collector comprising these eyelashes and / or these brush holders which overcome this disadvantage.

These objects are achieved, according to the invention, by an electrically conductive element for the transfer of an electric current between two moving parts relative to each other. This electrically conductive element is covered with at least one layer of insulating enamel electrically, with the exception of a zone of electrical continuity.

In the case of an eyelash, the electrical continuity zone is a friction zone in contact with a conductive track that moves relative thereto. In the case of a brush holder, the electrical continuity zone is a mounting zone for the brushes, which are in contact with a conductive track that moves relative to them.

1. (a) on recouvre l'élément électriquement conducteur d'une couche ou de plusieurs couches d'un matériau isolant électriquement,
2. (b) on cuit ledit élément recouvert afin de réticuler ledit matériau pour former une ou plusieurs couches d'émail,
3. (c) on traite la zone de continuité électrique des éléments électriquement conducteurs afin d'en retirer la ou les couches d'émail.

According to the invention, the manufacturing method comprises the following steps:

1. (a) covering the electrically conductive element with a layer or layers of an electrically insulating material,
2. (b) baking said coated member to crosslink said material to form one or more enamel layers,
3. (c) treating the electrical continuity zone of the electrically conductive elements in order to remove the enamel layer (s).

According to a first embodiment of the method, the electrically conductive elements are mounted on a carrier structure of the collector after the step (c) of treatment of the electrical continuity zone.
According to a second variant, the electrically conductive elements are mounted on a carrier structure of the collector before the step (c) of treatment of the electrical continuity zone.

In a particular embodiment, the enamel layer is removed by etching, thermal or mechanical etching. Advantageously, the enamel layer or layers are chosen from the group comprising polyvinyls, polyurethanes, polyesters, polyester imides, polyamide imides, polyimides.

The electrically conductive element may comprise several layers of enamel of the same chemical nature or of different natures.

The invention also relates to a collector comprising a first part and a second part moving relative to each other, one of these parts supporting a plurality of electrically conductive elements made according to the method of the invention. The electrically conductive elements are covered with at least one layer of electrically insulating enamel with the exception of a zone of electrical continuity zone.

In a particular embodiment, the collector comprises a fixed carrier structure and a rotor comprising conductive tracks and rotatably mounted in the carrier structure, the carrier structure supporting a plurality of electrically conductive cilia each having a contact zone applied to a rotor track.

In another particular embodiment, the collector comprises a fixed carrier structure and a rotor comprising cylindrical or flat conductive tracks and rotatably mounted in the carrier structure, the carrier structure supporting a plurality of electrically conductive brush supports each having a mounting zone of brushes in contact on a rotor track.

• la figure 1 est une vue en coupe axiale qui illustre la structure générale d'un collecteur tournant,
• la figure 2 est une vue en coupe selon la ligne II-II de la figure 1,
• la figure 3 est une vue en coupe partielle à échelle agrandie des pistes du collecteur des figures 1 et 2,
• la figure 4 est une vue de détail à échelle agrandie de la zone de contact entre un cil conforme à l'invention et une piste du collecteur tournant des figures 1 à 3,
• la figure 5 est une vue schématique en coupe qui illustre la structure générale d'un autre exemple de collecteur tournant.

Other characteristics and advantages of the present invention will become apparent on reading the following description of exemplary embodiments given as illustrative but not limiting, with reference to the accompanying drawing in which:

• the figure 1 is an axial sectional view that illustrates the general structure of a rotating collector,
• the figure 2 is a sectional view along line II-II of the figure 1 ,
• the figure 3 is a partial sectional view on an enlarged scale of the tracks of the collector of Figures 1 and 2 ,
• the figure 4 is an enlarged detail view of the contact zone between an eyelash according to the invention and a track of the rotating collector of Figures 1 to 3 ,
• the figure 5 is a schematic sectional view that illustrates the general structure of another example of a rotating manifold.

The collector shown on Figures 1 and 2 comprises a fixed support structure 2 which supports two eyelash supports 8. The eyelashes 14 comprise a flat part 15 held in an eyelash holder 8 by a cover or by a resin filling and two free ends 20 arranged on either side The eyelashes are made of copper or copper alloy, or other good conducting metals such as gold, silver, platinum or one of their alloys. In the present example, the eyelashes 14 are made of gold alloy and have a circular section. However, it is understood that in the context of the invention, they may have another section, for example square, rectangular or other. Each eyelash support 8 is fixed, for example by screws (not shown), on two flats of the supporting structure 2.

A rotor 24 is rotatably mounted inside the supporting structure 2. The rotor 24 is guided in rotation at its ends in bearings (not shown). It comprises a bearing 28 on which are threaded a series of rings. Some of these rings, such as rings 32 and 34 (see figure 3 ), are simple spacers. Other rings 37 have an L-shaped section in which conductive rings 33 are housed. Between the rings 34 and 37 made of an electrically insulating material is formed a set 36. A conductive ring 33, made for example of a copper alloy, gold or golden brass, is mounted on each ring 37. The rings 33 have a semi-circular groove or other shape which receives an eyelash 14. In addition, as can be seen (see figure 2 ), the ends 20 of the eyelashes comprise a curved portion 38 intended to facilitate their insertion into the grooves 35. The eyelashes 14 are preloaded: this means that their free end 20 is applied to the tracks with a certain support force, called preload , so as to ensure good contact between the eyelashes and the track on which they are applied. The pre-charge is adjustable.

We have shown on the figure 4 an enlarged view of the end of an eyelash 14 in contact with a ring 33 of the rotor 24. In accordance with the invention, the surface of the threads that make up the eyelashes 14 is covered with one or more layers of enamel 42 with the exception of a zone 43 in frictional contact with the ring 33.

The eyelashes are glazed prior to their use in the collector. This avoids the pollution of the collector. In addition, this allows their control before use. The enameling operation can be carried out according to a known method, in particular by soaking the eyelashes in a solution of an electrically insulating material, then by cooking in an enameling furnace, such as that described in the document EP-0 875 299 . The enameled conductor runs continuously along an enameling line. The enameling line generally comprises an applicator for depositing on the wire a solution of oligomers or prepolymers, constituting the insulating material, in a solvent. Additives are usually added to the solution (catalyst, adhesion promoter, etc.). This applicator is followed by an enameling furnace comprising a solvent evaporation zone (150 ° C.-350 ° C.) and a polymerization and crosslinking zone of the electrically insulating material (350 ° C.-550 ° C.). Once enamelled, the conductive wire is then cut into sections to form the eyelashes 14. The electrical continuity zone is treated to remove enamel for example by dipping. The enamel removal operation is preferably carried out after mounting the eyelashes 14 in the carrier structure 2.

We have shown on the figure 5 a second embodiment of a collector according to the invention. It comprises a fixed part 50 and a mobile part 52. The fixed part comprises a support 54, for example made of aluminum, consisting of two parts 56 and 58 clamped by a screw 60 and between which is disposed a brush holder 62 which constitutes a electrically conductive element within the meaning of the invention. The brush holder 62 is constituted by an electrically conductive flexible blade of flattened rectangular section made, for example, of copper or a copper alloy. At its free end, it carries one or more brushes 64 of carbon or other conductive material. At the other end, it is connected to a wire electrical conductor 66 which terminates in a lug 68 fixed to the blade 62, for example by means of a rivet 70. An insulation (not shown) is provided between the support 54 and the brush holder 62.

The movable portion 52 is constituted by a disc 72 movable in rotation about an axis 74. The disc 72 comprises circular conductive tracks 76, made for example of silver. For the sake of simplicity, there is only one track and a single broom in the figure, but it goes without saying that in practice the manifold has several, for example a dozen. The broom 64 rubs on the track 76. The broom support 62 is pre-loaded to apply the broom 64 with a given force on the track 76.

According to the invention, the flexible blade 62 is electrically insulated by one or more layers of enamel (not shown). These enamel layers can be of the same chemical nature or of different chemical natures. They are advantageously deposited in several successive layers of a few microns thick. The enamel layer is locally removed in the contact zone 65 between the brush 64 and the flexible blade 62 to ensure the continuity of the electrical transmission. The enamel layer is also removed at the contact between the flexible blade 62 and the lug 68 of the electrical conductor 66.

The enamel used may be polyvinyl type, polyurethane, polyester, polyester imide, polyamide imide, polyimide or other.

• ne pas perturber la précharge des cils ou des supports de balais, c'est-à-dire la force d'application des cils ou des supports de balais sur la piste du conducteur.
• être compatible avec les opérations de mise en forme des cils ou des supports de balais sans générer de craquelures de l'émail.

Enamel is able to withstand high temperatures and strong differences in electrical potential. he has a strong adhesion to the eyelashes and / or the brush holders. It is flexible and its thickness is sufficiently small (10 to 15μm) for:

• not to disturb the preloading of the eyelashes or the brush supports, ie the force of application of the eyelashes or the brush holders on the conductor's track.
• be compatible with the operations of shaping eyelashes or brush holders without generating enamel cracks.

The preload adjustment is done after the eyelashes or brush holders have been enamelled, so that the stiffness of the enamel is taken into account when adjusting the preload.

Due to the presence of the enamel layer 42, a double insulation of the eyelashes or brush holders in the power or signal collector is achieved. On the one hand, as in the prior art, the eyelashes or brush holders are isolated by spacing them, but furthermore they are isolated by the presence of an enamel layer on each of them. Unlike other solutions, such as the use of insulating sheaths or a layer of glue, the preload is not disturbed by the presence of the enamel layer. In addition, the temperature resistance is better than that of an adhesive or a sheath.

Finally, it is understood that the invention does not apply exclusively to the rotary manifolds which have just been described, but to all types of collectors in which conductive elements transmit signals or electrical power by friction between a part fixed and a moving part, for example by friction on a track made on a record or on a turntable. The invention also applies to a collector in which the tracks are fixed and the conductive elements are mounted on a rotating part relative to the tracks.

Claims (15)

1. Method of manufacturing an electrically conductive element (14, 62) covered in at least one electrically insulating layer (42) with the exception of an electrical continuity zone (43, 65) for transferring an electrical current between two parts (2, 24, 50, 52) that are movable relative to each other, the method being characterized in that it comprises the following steps:

   a) said electrically conductive element (14, 62) is covered in one or more layers of an electrically insulating material;

   b) said covered element is baked so as to crosslink said material in order to form one or more layers of enamel (42); and

   c) the electrical continuity zone (43, 65) of the electrically conductive elements (14, 62) is treated so as to remove the enamel layer(s) therefrom.
2. Method according to Claim 1, in which said electrically conductive elements (14, 62) are mounted on a carrier structure (2, 50) of the collector after step c) of treating the electrical continuity zone.
3. Method according to Claim 1, in which said electrically conductive elements (14, 62) are mounted on a carrier structure (2, 50) of the collector prior to step c) of treating the electrical continuity zone.
4. Method according to one of Claims 1 to 3, in which the electrically conductive elements are wipers (14), the electrical continuity zone being constituted by a zone (43) for rubbing against a conductive track (33, 35) which is movable relative thereto.
5. Method according to one of Claims 1 to 3, in which the electrically conductive elements are brush supports (62), the electrical continuity zone being constituted by a zone (65) for mounting brushes (64) on the brush support.
6. Method according to one of Claims 1 to 5, in which the layer(s) of enamel is/are removed from the electrically conductive element (42, 62) by chemical, thermal, or mechanical attack.
7. Method according to one of Claims 1 to 6, in which the enamel layer(s) (42) is/are selected from the group comprising polyvinyls, polyurethanes, polyesters, polyesterimides, polyamideimides, and polyimides.
8. Method according to one of Claims 1 to 7, in which the electrically conductive element carries a plurality of layers of enamel (42) of identical chemical nature.
9. Method according to one of Claims 1 to 7, in which the electrically conductive element carries a plurality of layers of enamel (42) of different chemical natures.
10. Electrically conductive element for transferring an electrical current between two parts (2, 24, 50, 52) that are movable relative to each other, the element being made by the method according to one of Claims 1 to 9, and being covered in at least one layer of electrically insulating enamel (42) with the exception of an electrical continuity zone (43, 65).
11. Element according to Claim 10, in which said electrical continuity zone is a rubbing zone in contact with a conductive track which is movable relative to said element.
12. Element according to Claim 10, in which said electrical continuity zone is a brush mounting zone on the brush support, said brushes being in contact with a conductive track which is movable relative to said element.
13. Collector comprising a first part (2, 50) and a second part (24, 52) that are movable relative to each other, one of said parts supporting a plurality of electrically conductive elements (14, 62) made by the method according to one of Claims 1 to 9.
14. Collector according to Claim 13, comprising a fixed carrier structure (2) and a rotor (24) having cylindrical or plane conductive tracks and mounted to rotate in the carrier structure, the carrier structure (2) supporting a plurality of electrically conductive wipers (14) each having a contact zone pressed against a track (33) of the rotor (24).
15. Collector according to Claim 13, comprising a fixed carrier structure (50) and a rotor (52) having cylindrical or plane conductive tracks (76) and mounted to rotate in the carrier structure, the carrier structure (50) supporting a plurality of electrically conductive brush supports (62) each having a mounting zone (65) for the brushes (64) in contact with a track (76) of the rotor (52).

Images