FR2879031A1 - INSULATING INTERFACE FOR ELECTRICAL CONNECTION DEVICE AND ELECTRICAL CONNECTION DEVICE COMPRISING SUCH AN INTERFACE - Google Patents

Abstract

The present invention relates to an electrical connection device (1) for high-voltage apparatus comprising two separable insulating elements (2, 3). Each insulating element has at least one electrical contact (4, 5). These insulating elements are intended to fit into each other. A gap formed between these two insulating elements (2, 3) comprises an insulating interface (20). This insulating interface (20) comprises a succession of air chambers (22) and segments (21). The segments are formed from elastic insulating materials. And the air chambers (22) are formed by grooves.

Description

Insulating interface for electrical connection device and device

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  The subject of the present invention is an insulating interface for an electrical connection device for a high voltage apparatus comprising two separable insulating elements. The field of the invention is that of the connectors used to make electrical connections between a high voltage power source and for example an X-ray tube apparatus. The invention can nevertheless be applied to high voltage connection devices. of all kinds.

  In the field of electrical connection devices for high voltage apparatus, the connection devices generally consist of two parts. A first portion or receptacle that is permanently attached to the housing enclosing the high voltage power source. A second part or plug intended to fit into the receptacle to achieve electrical continuity. This plug is an end of the high voltage cable. In order to withstand the high voltages of the source and the X-ray tube, which can reach more than 200 kilovolts, the receptacle and the plug of the connection device are made of electrically insulating and rigid materials. The receptacle and the plug have shapes and dimensions generally imposed by international standards.

  The electrical connection device in which the high voltage flows must be perfectly isolated from the ground over its entire length. Indeed, an imperfection of the insulation such as the presence of air bubbles or polluting conductive particles, between the receptacle and the plug, may cause the formation of an electric arc between the receptacle and the plug and the metallic shells forming the electrical mass. These air bubbles or polluting conductive particles have the disadvantage of interrupting the continuity of the electrical insulation due to a sudden change in the dielectric constant.

  In the state of the art, the electrical insulation between the plug and the receptacle is provided by a liquid insulator. This liquid insulator can be oil or mineral grease, it can also be silicone grease. This liquid insulator removes air bubbles or polluting conductive particles that may be between the receptacle and the plug.

  This liquid insulator, however, has disadvantages. Because, the procedure of introduction of the liquid insulator is very delicate because, it imposes the complete absence of air bubble or polluting conductive particles between the receptacle and the plug. In addition, there is always a risk that the operator forget to return oil or grease or that it does imperfectly when mounting the connection device. In the hospital services, the operators of its services are obliged to have syringes and bottles containing liquid insulation to fill and check the tightness of the connection devices.

  In addition, the presence of a liquid insulator constitutes a constraint that imposes a substantially vertical orientation of the electrical connection device during assembly and disassembly.

  In operating mode, the liquid insulator is at a relatively high temperature. And the differences in thermal expansion, the various components of the separable elements as well as the liquid insulator, lead to a potential risk of loss of tightness of the assembly resulting in oil or grease leakage and consequently to a lowering the level of electrical insulation of the high voltage connection device.

  This sealing problem is particularly important when the high-voltage connection device is in a rotating system, for example the sheaths of some x-ray radiography apparatus. Currently, most high-voltage medical devices are mobile, for example example on scanners. Scanners turn faster and faster to make images in real time, they can follow the rhythms of the heart. During the rotation of the scanner, if there is any air bubble or polluting conductive particles between the receptacle and the plug, an air channel or a channel of the polluting particle is formed at the bottom of the device, by the centrifugal force. And the liquid insulator is pushed from the bottom of the device to the outside. This air channel causes a dielectric failure of the electrical connection device.

  Today medical devices have smaller and smaller dimensions. Standardized connection devices have disproportionate sizes compared to new medical devices. In addition, in view of the progress made in insulating materials and high voltage medical devices a new type of high voltage connection device is described in FR-A-2817667.

  This new type of small size connection device will differ from the standard size connection device in particular by reducing the lengths and diameters of the receptacle and the plug With this connection device the problem of using the oil or fat, is solved. The plug of this connection device is formed of elastically deformable plastic material. The plug is flexible with a certain taper. The plug is deformable when you put some pressure on it. This taper as well as this deformability of the plug allows, during the nesting of the plug in the receptacle, to remove air bubbles or polluting conductive particles present between the receptacle and the plug. As a result, it is no longer necessary to use grease or oil to suppress air bubbles. This system has by cons a lot of disadvantage.

  To be able to remove the air bubbles between the receptacle and the plug a considerable pressure is exerted on the connection device. This pressure is ensured in a continuous and uniform way. The connection device is then dependent on the pressure. In addition, the deformation of the plug of the connection device may cause a variation in the length of this plug. In this case, the receptacle and the plug does not come into contact, in operating mode, causing in the same way an interruption of the electrical continuity.

  In addition, for more than half a century men have used to put liquid insulation between the receptacle and the plug of the connection device. It is very difficult to change habits. The men then continue to put liquid insulation between the elements of this new connection device. By cons, the elements of this device are elastomers, which causes swelling and destruction of said elements when the liquid insulator is expanded by heat. In this case, the connection device is destroyed.

  The chemical components of the plug material swell in operating mode. This swelling is caused by the rise in temperature generated by the heating of the receptacle in the tube sheath or in the high voltage source. This swelling causes the destruction of the connection device. This destruction can cause the breakdown of the X-ray system and the destruction of the X-ray generator. The object of the present invention is to provide a high-voltage assembly comprising separable elements in which it is not necessary to use the oil or grease to ensure the continuity of electrical insulation between the separable elements of the high voltage connection device.

  The object of the invention is also to provide a connection device in which it is not necessary to maintain the connection device at considerable pressures in a continuous and uniform manner.

  The invention also aims to provide a connection device in which it is not necessary to maintain said sealed connection device.

  The invention also aims to provide a connection device in which it is not necessary to provide said connection device with a volume expansion compensator of the interface.

  For this, the invention provides an insulator between the receptacle and the plug as a flexible insulating interface. This insulating interface is intended to encircle the receptacle or the plug of the connection device. This insulating interface is preferably removable. The insulating interface is formed of elastic insulating materials. The insulating interface has segments provided with elongate rings separated by air chambers. This alternation of insulating materials and air chambers forms a high-voltage divider. The leakage currents pass the number of rings and air chambers present in the insulating interface and divide the high voltage.

  More specifically, the subject of the invention is an electrical connection device for a high-voltage device comprising two separable insulating elements, each insulating element comprising at least one electrical contact, these insulating elements being intended to fit one into the other. another, a gap being formed between these two insulating elements characterized in that this gap comprises an insulating interface, this insulating interface comprising a succession of air chambers and segments, the segments being formed of elastic insulating material.

  The invention also relates to a connection device comprising an insulating interface according to the invention.

  The invention will be better understood on reading the description which follows and the examination of the figures which accompany it. These are presented only as an indication and in no way limitative of the invention. The figures show: FIG. 1: a sectional view of an electrical connection device according to the invention.

  FIG. 2 is a sectional view of a first embodiment of the insulating interface according to the invention.

  - Figure 3: a sectional view of a second embodiment of the insulating interface according to the invention Figure 1 shows a schematic view of a device 1 of high voltage electrical connections. This device 1 comprises two insulating elements 2 and 3 separable and connected. The insulating element 2 is a receptacle of the device 1. The receptacle 2 comprises at least one female contact 4. The insulating element 3 is a plug of the device 1. The plug 3 comprises at least one male contact 5.

  The receptacle 2 is intended to be attached to an apparatus operating at high voltage, for example a high-voltage generator or the sheath of an X-ray tube, for the purpose of supplying it at high voltage. The receptacle 2 comprises a frustoconical envelope 6. This envelope 6 is hollow and rigid. This envelope 6 is for example formed of a rigid plastic material. The envelope 6 has a bottom wall 7 and a side wall 8. This side wall 8 is open at the end 9 of the receptacle 2.

  This end 9 is opposite to the bottom wall 6 delimiting an internal volume 10. The side wall 8 flares from the bottom wall 7 to its end 9.

  This envelope 6 is provided on the periphery of its end 9 with an annular flange 11. This flange 11 allows the connection of the receptacle 2 to a metal casing 12 of a high-voltage device. This metal casing 12 comprises a thread 13. This thread 13 is intended to cooperate with an attachment nut 14 of the plug 3 in order to ensure a secure connection of the separable elements of the connection device 1.

  The female contact 4 is disposed in the bottom wall 7 of the casing 6. This female contact 4 is connected by a conductor 15 to an electrode of the high-voltage apparatus.

  The plug 3 comprises a frustoconical block 16. This block 16 is made of electrically insulating material. This block 16 can be deformable elastic or rigid. This block 16 coats the conductor 17 connected to a high-voltage power supply cable 18. This conductor 17 ends at the front face of the block 16 by at least the male contact 5. This male contact 5 is intended to connect with the female contact 4. The block 16 flares from its front face to a flange 19 annular support. This support flange 19 provides the connection between the block 21 and the high voltage cable 18.

  In the example of Figure 1, the fastening nut 14 of the plug 3 comprises a thread for cooperating with the thread 13 of the metal casing 12. It can also be used any other known arrangement for fixing the connection devices .

  To avoid the occurrence of electrical discharges due to air bubbles, between the interior volume 10 of the receptacle 2 and the block 16 of the plug 3, in particular in the direction of the metal casing 12 of the sheath, an interface is provided. insulation 20 in a gap present between the receptacle 2 and the plug 3. This insulating interface 20 is intended to ensure the continuity of the electrical insulation between the plug 3 and the receptacle 2. This insulating interface 20 is flexible. This interface has a shape, preferably pseudo-cylindrical slightly conical, suitable for all existing connection devices.

  This insulating interface is in the form of a sleeve. This sleeve 20 may be made of any flexible insulating material. Preferably, the sleeve 20 is made with a silicone elastomer.

  The sleeve 20 is intended to be compressed between the interior volume 10 of the receptacle 2 and the block 16 of the plug 3 in order to be sufficiently deformed to perfectly fill the gap between the receptacle 2 and the plug 3.

  According to the invention, the sleeve 20 is formed by revolution about an axis X of revolution common to the two separable elements. The sleeve 20 is, in general, pressed against the plug 3. The sleeve 20 is retained by the support flange 19. The sleeve 20 can also be glued against the receptacle 2. The sleeve 20 is preferably removable.

  The sleeve 20 has a succession of segments such as 21. The segments 21 are seen here in section. These segments 21 comprise elongated rings and made around the sleeve 20. The rings 21 are separated by air chambers such as 22. The shape of the air chambers 22 causes the shape of the rings 21.

  In the example of FIG. 1, the chambers 22 of air are formed by cavities each having a bottom such as 23. Likewise, the rings 21 form protruding parts of the sleeve 20 each having a ridge such as 24. rings 21 are delimited by two successive air chambers 22.

  The air chambers 22 form a pathway where the air circulates. The rings 21 10 fit into each other. The rings 21 and the air chambers 22 are preferably concentric in shape.

  The air chambers 22 can be made by holes or crenellations. The air chambers 22 can also be made by grooves. The air chambers 22 have such constant depths. These depths may be specific to each air chamber. The depth 25 is a height of an air chamber. This depth 25 also corresponds to a height of the rings 21. A length 26 of an air chamber 22 may be specific to each of the air chambers 22. In the example of Figure 1, the length 26 is almost constant.

  This alternation of rings 21 and air chambers 22 is intended to alternately pass the leakage current between elastic insulating materials and air. This alternation of rings 21 and 22 air chambers form a high voltage divider between the contacts 4 and 5 forming the high voltage level and the metal shell 7 of the sheath forming the mass. This high-voltage divider, formed by alternating air chambers 22 and rings 21, is preferably linear. In the case where the length 26 is almost constant, the high voltage divider is also almost linear.

  This alternation of rings 21 and chambers 22 of air makes it possible to eliminate the pressure as well as the chemical or thermal swelling of the components constituting the sleeve 20.

  The number of rings 21 and air chambers 22 is determined as a function of the intensity of the leakage current to be removed and the length of the separable elements of the device 1 connections. It suffices then to put enough rings 21 so that a single ring never has enough voltage at its terminals to snap.

  The rings 21 and the air chambers 21 can have all the geometric shapes that make it possible to subdivide the high voltage.

  When the receptacle 2 and the plug 3 are joined together by engagement, the rings 21 and the air chambers 22 are deformed by compression. The ridges 24 of the rings 21 have rounded shapes for cutting. In this example, the air chambers 22 are deformed by compression. This compression of the air chambers 22 makes it possible to standardize the variation of the volume of the sleeve 20.

  In view of cutting, the air chambers 22 have a trapezoidal shape.

  The air chambers 22 comprise a small base formed by the bottom 23 of the air chambers 22 and a large base 27. This large base 27 is formed by the length of two successive ridges 24.

  In dynamic mode, the alternation of rings 21 and air chambers 22 forms a capacitive divider. And in continuous mode, the alternation of rings 21 and air chambers 22 forms a leakage current divider.

  To allow the circulation of air between the air chambers 22, the rings 21 each comprise at least one slot (not shown). Each slot is intended for the passage of air.

  The circulation of the air, between the slots of the rings 21, allows the inner volume 10 to always remain at atmospheric pressure. This maintenance of the internal volume at atmospheric pressure makes it possible to divide the leakage currents precisely.

  If inadvertently a liquid insulator is put in the gap formed by the receptacle and the plug 3, the elastomer swells. Maintaining the pressure of the inner volume at atmospheric pressure makes it possible to compensate for the chemical swelling of the components of the sleeve material caused by the expansion of the liquid insulator. This circulation of air then makes it possible to preserve the constant sleeve volume regardless of the liquid insulation coated between the receptacle 2 and the plug 3. As a result, there are no longer any problems with oil leakage, filling and pressure exerted on the device 1 connections.

  The invention makes it possible to have a high-voltage device 1 comprising the receptacle 2 and the plug 3 that can be easily assembled during manufacture or installation. The receptacle 2 and the plug 3 can be easily disassembled after use or during an intervention. The manipulation of the device 1 is thus facilitated. This ease of manipulation makes it possible to change elements of the device 1 directly at its location and not in a factory. This ease of handling also makes it possible to reduce the possibilities of human errors.

  Figure 2 shows a first embodiment of the sleeve 20 according to the invention. In this example, the sleeve 20 is formed of rings 21 and air chambers 22 in the form of parallel rings. The rings 21 and the air chambers 22 then have a circular shape surrounding the envelope 28 of the sleeve 20. This envelope 28 is, in this example, in the form of a hollow cylinder. This envelope 28 has an opening 29. The rings 21 and the air chambers 22 preferably have the same center of circle as the center 30 of this opening 29. The center 30 of the opening 29 is located in example of Figure 2, on the axis of revolution X. This sleeve 20 is adapted to envelop the receptacle 2 or the plug 3 of the device 1 connections. In a preferred example, the sleeve 20 encircles the plug 3.

  The rings 21 have elongate ridges. Each of the rings 21 comprise at least one slot such as 31. In the example of FIG. 2, the rings 21 each comprise a single slot 31. These slots 31 can be made transversely to the elongation of the rings 21.

  These slots 31 allow the circulation of air between two successive air chambers 22. A length of an opening 32 of these slots 31 may vary from one slot to another. In the example of Figure 3, the slots 31 are made perpendicular to the elongation of the rings 21. And the length of the opening 32 is constant.

  In one example, the slots can be made in a rotation of 90 degrees relative to the axis X of revolution common to the two separable elements. The slots 31 can be chosen according to the most suitable position for the air circulation.

  The length 26 of the air chambers 22 and the length 33 of the rings 21 are defined to form a quasi-linear high voltage divider between the contacts forming the high voltage level and the metal casing of the cladding forming the mass. The lengths 26 and 22 are preferably equal.

  Figure 3 shows a second embodiment of the sleeve of the invention. In this embodiment, the rings 21 and the air chambers 22 are made in the form of rings wound spirally around the casing 20 of the sleeve 30. The sleeve 20 has a pseudocylindrical shape. This sleeve 20 adapts to all existing connection devices. These rings 21 each comprise at least one slot 31. This slot 31 is made, in one example, by a rotation of 90 relative to the axis X of revolution common to the two separable elements.

  The slots 31 may be chosen according to the most appropriate position for the flow of air between the air chambers 22.

  The orientation of all these possible models must be geometrically oriented in space so that the high-voltage leakage current alternately passes through air chambers 22 and rings 21 comprising elastic insulating materials.

Claims (1)

11 CLAIMS   1 - Device (1) for electrical connections for high-voltage devices comprising: - two separable insulating elements (2, 3), - each insulating element comprising at least one electrical contact (4, 5), - these insulating elements being intended for to fit one into the other, a gap being formed between these two insulating elements, characterized in that this gap comprises an insulating interface (20), said insulating interface comprises a succession of air chambers (22). ) and segments (21), said segments being formed of elastic insulating materials.   2 - Device (1) according to claim 1, characterized in that the air chambers and the segments are formed by a sleeve (20), forming a flexible support interface, provided with an elongate ring (21) at the location of segments.   3 - Device (1) according to one of claims 1 to 2, characterized in that the sleeve (20) is formed by revolution about an axis (X) of revolution common to the two separable elements.   4 - Device (1) according to one of claims 1 to 3, characterized in that each segment (21) comprises. a slot (31) transverse to their elongation.   5 - Device (1) according to one of claims 1 to 4, characterized in that the slots on the segments are made in a rotation of 90 degrees relative to the axis of revolution common to the two separable elements.   6 - Device (1) according to one of claims 1 to 5, characterized in that the sleeve is made with an elastomer.   7 - Device (1) according to one of claims 1 to 6, characterized in that the air chambers and the segments form parallel rings having the same center of circle 30 on the axis of revolution.   8 - Device (1) according to one of claims 1 to 7, characterized in that the air chambers and the segments form spirally wound rings around the sleeve.   9 - Device according to one of claims 1 to 8, characterized in that the segments are compressed slightly during the nesting of the insulating elements.   - Device (1) according to one of claims 1 to 9, characterized in that the air chambers are formed by grooves.   11 - high voltage device, characterized in that it comprises a device (1) of electrical connections according to any one of claims 1 to 10.