EP1540773A1

EP1540773A1 - Connector for a coaxial cable

Info

Publication number: EP1540773A1
Application number: EP03794918A
Authority: EP
Inventors: Gerhard Zuch
Original assignee: Framatome ANP GmbH
Current assignee: Areva GmbH
Priority date: 2002-08-29
Filing date: 2003-08-22
Publication date: 2005-06-15
Anticipated expiration: 2023-08-22
Also published as: JP2005537629A; EP1540773B1; AU2003264090A1; ES2258237T3; BR0313872A; DE50302442D1; CN100352105C; CA2496845C; ZA200500722B; JP4348296B2; CA2496845A1; CZ301400B6; UA79809C2; US20050260878A1; WO2004025786A1; US7131866B2; DE10240563A1; CZ2005117A3; CN1679211A; DE10240563B4

Abstract

The invention relates to a connector (33) for interconnecting two coaxial cables (30, 32), each comprising a central conductor (34, 35) that is surrounded by an outer conductor (36, 37), whereby a respective connector piece (38, 39) is assigned to each coaxial cable (30, 32). The aim of the invention is to ensure the easy and rapid use of the connector, whilst reliably guaranteeing the electrical contact between the interconnected coaxial cables. To achieve this, each connector piece (38, 39) comprises one connection region (40, 41) that is electrically connected to the respective central conductor (34, 35) of the corresponding coaxial cable (30, 32), a connection head (42) of the second connector piece (39) being supported on the connection region of said piece by means of a spring element (43), in order to make electrical contact with the connection region (40) of the first connector piece (38).

Description

description

Coupling for coaxial cables

The invention relates to a coupling for coaxial cables according to the preamble of claim 1.

Such a coupling is known for example from EP 0 314 299 A1. Couplings for coaxial cables with spring-loaded connecting elements are also known from the publications US 3, 416, 125, US 4, 012, 105 or US 6, 053, 777.

Such a coupling can be important in many industrial applications in which coaxial cables have to be quickly and easily disengaged and coupled together, for example during maintenance work. In particular, such a coupling can be used in the case of rigid coaxial conductors, such as those used in a nuclear facility or a nuclear power plant for the transmission of electrical signals or pulses.

In nuclear power plants, it is necessary to monitor the level of an operating or cooling medium in a container that is not directly visible and, if necessary, to readjust it, for example the level of the primary coolant in the reactor pressure vessel. The so-called TDR measuring principle (time-domain reflectometry) can be used for this purpose, as is known, for example, from DE 19958584C1. The effect of the TDR measuring principle is that an electromagnetic pulse carried in an antenna system is partially reflected when the impedance changes abruptly between, for example, a central conductor of the antenna and a sheathed conductor surrounding it in the manner of a coaxial cable.

Such an abrupt change in impedance occurs, for example, where the antenna formed in this way is immersed in a liquid from a gaseous environment, since the impedance depends on the capacitance between the central conductor and the sheathed conductor and thus on the dielectric constant of the medium filling the space between the central conductor and the sheathed conductor depends. One of such, in that too depends on the conductor and sheathed conductor filling medium. An electromagnetic pulse supplied to such an antenna, which is immersed in the medium to be monitored, is thus partially reflected on the surface of the medium. Another reflection occurs at the usually short-circuited antenna end. Since, moreover, the propagation speed of the electromagnetic pulse in the antenna is known, the transit time difference between the pulse reflected at the boundary layer and the pulse reflected at the antenna end can be used as a measure of the position of the boundary layer and thus as a means of determining a characteristic of the position of the boundary layer Position characteristic value can be used, whereby an essentially proportional dependency between the term difference and position characteristic value can be used.

In order to be able to use this method for the diagnosis and monitoring of, for example, a medium in a closed container, the transmission of electromagnetic pulses from the outside into the interior of the container and vice versa is therefore necessary. On the other hand, depending on the type and properties of the medium held in the container, it may be imperative or at least of great importance to ensure a particularly high degree of tightness of the container. Depending on the operating parameters prevailing in the container according to the design, such as, for example, the pressure and temperature of the medium held there, particularly high demands are to be made on the electrical feedthrough used for introducing and discharging electromagnetic pulses. The same applies to the transmission of an electromagnetic pulse from the containment surrounding the reactor pressure vessel to a pulse generator or to an evaluation and control unit and vice versa.

For example, rigid coaxial conductors can be used to transmit the electromagnetic pulses between the containment wall and the reactor pressure vessel, in particular in order to ensure the high signal quality required for reliable measurement value acquisition. However, it may still be necessary to make the reactor pressure vessel accessible, for example during maintenance work. In order to make this possible even with the use of rigid coaxial conductors with little effort, a coupling device which allows segments of the Coupling the coaxial conductor between the two bushings mentioned quickly and easily.

In order to keep the interference and damping of the electromagnetic pulse in such a system as low as possible at the coupling point, the coupling should meet high requirements. In particular, the impedances should be kept constant over the length of the conductor or at least not change discontinuously, so that disturbing reflections on impedance jumps are avoided as best as possible. High-quality electrical contact between conductors connected by the coupling is particularly important for reliable transmission of the electromagnetic pulse.

The invention is therefore based on the object of specifying a coupling of the type mentioned above which is both simple and quick to use and which ensures the electrical contact between the coupled coaxial conductors with high reliability.

This object is achieved in that the end of the connection head facing the connection area of the second coupling piece is provided with contact fingers which fit into recesses provided for this purpose in the connection area of the second coupling piece, the connection area of the second coupling piece being provided with a contact piece which is suitable for the or each contact finger has an associated connection surface.

The invention is based on the consideration that a coupling mechanism for coaxial cables should be easy to operate, that is to say that the cables should be able to be coupled and uncoupled quickly and easily. At the same time, however, the electrical contact between the coaxial conductors connected via the coupling should also be particularly intensive during the operation of the system. In order to meet these two conditions, which in principle contradict one another, the coupling is provided with a device which particularly strengthens the contact between the conductors to be coupled. Here, the targeted use of the restoring force of a spring element is provided, the spring being loaded when the two coaxial conductors are coupled together therefore constantly exerts a force favoring the electrical contact on both conductors.

In order to be able to guarantee a particularly intimate contact between the connection head and the connection area of the first coupling piece, the connection head is slidably mounted on the connection area of the first coupling piece. The connection head is expediently positioned when the coupling is open in such a way that when the coupling is assembled, the connection area of the first coupling piece moves the connection head toward the connection area of the second coupling piece and thereby tensions the spring element. The resulting restoring force of the spring element consequently leads to a permanent pressing of the connecting head against the first coupling piece and thus to a particularly reliable electrical connection. The contact fingers both center the connection head with respect to the longitudinal axis of the coupling and produce the electrical contact between the connection head and the connection area. Due to the interaction of the contact fingers with the associated recesses and in particular with contact surfaces arranged in them, sufficient contact with the connection area carrying it is ensured at all times even when the connecting head is displaced in the longitudinal direction.

The contact fingers of the connection head enclose a contact piece attached to the connection area of the second coupling piece, which serves to ensure the electrical contact between the connection head and the connection area. Depending on the load on the spring element assigned to the connecting head, the contact fingers rest on a larger or smaller surface of the contact piece. The contact piece therefore also has the task of reliably maintaining the electrical contact between the connecting head and the connection area of the second coupling piece, even with a varying length of the spring.

Advantageously, the connecting head fits into a recess made in the connection area of the first coupling piece such that it thereby centers itself with respect to the longitudinal axis of the coupling. The shape of the connecting head can in particular be convex and a corresponding concave Insert the recess in the connection area of the first coupling piece, both the connecting head and the recess being rotationally symmetrical about the longitudinal axis of the coupling. This ensures that the connecting head attaches particularly easily to the second coupling piece and that the central axes of both coupling pieces cannot move against each other when coupling together, which can lead to undesirable disturbances in the electromagnetic pulse and can also make it impossible to connect the sheathed conductors to one another.

For manufacturing reasons, a conical recess in the connection area of the first coupling piece is particularly advantageous, with which a connecting head shaped in the manner of a truncated cone corresponds.

Advantageously, a retaining screw is anchored to the connection area of the second coupling piece, holds the connection head at the connection area and prevents the connection head from being completely loosened when the coupling is open. The jacket conductor of each coupling piece is expediently equipped with a mounting flange which allows the coupling pieces to be connected to one another. Advantageously, a circumferential seal is attached between the mounting flanges, which enables a tight closure of the coupling.

The secure connection of the two coupling pieces is expediently carried out via a closure element, which allows the two coupling pieces to be held firmly together. Such a closure element is adapted in shape and contour to that of the mounting flanges and encloses the mounting flanges in the connected state.

The closure element is advantageously a clamping ring with a spring clip, which enables particularly simple and quick operation of the coupling.

An undesired damping of the electromagnetic pulse can be excluded or at least kept low by the fact that the impedances do not change or change only slightly over the length of the coupling point. To ensure this Most, the corresponding components, in particular the connection areas and the sheathed conductors surrounding them, are advantageously suitably dimensioned.

The advantages achieved by the invention are, in particular, that the use of a spring element in the production of an electrical connection between the central conductors of the coaxial cables provides a particularly simple and quick-to-use coupling, which also ensures that the electrical connection between the coaxial conductors is particularly good is high quality. This enables the coupling to be used even for sensitive measurements that require high signal quality. The coupling is therefore particularly suitable for use on signals for coaxial conductors transmitting TDR measurements in nuclear power plants. An embodiment is explained in more detail with reference to a drawing. In it show:

1 schematically shows a system for monitoring the fill level in a closed reactor pressure vessel,

2 shows in cross section a coupling for coaxial cables,

3 shows in cross section the sheathed conductor of the coaxial cable with a closure element, and

4 shows in cross section the same sheathed conductor of the coaxial cable with a closure element and a seal.

Identical parts are provided with the same reference symbols in all figures.

The system 1 according to FIG. 1 is provided for monitoring a medium M within the connected reactor pressure vessel 2 of a nuclear facility. The reactor pressure vessel 2 is arranged inside a containment 4 which is designed to be closed and is only indicated in FIG. 1. For the suitable exchange of signals S, the reactor pressure vessel 2 is connected via a signal line 6 is led through a containment 8 through the containment 4, connected to a communication interface 10 of the system 1.

In the exemplary embodiment, water W is held as medium M in the exemplary embodiment of the reactor pressure vessel 2, which serves as the primary coolant of the nuclear plant. In a lower area of the room, the water w is unmixed in the so-called supercooled state. In contrast, in a room area above, in which there is a heating effect of the nuclear fuel elements arranged in the reactor pressure vessel 2, there is a phase mixture W, D between water W and vapor bubbles D formed therein. In an even further area, on the other hand, there is exclusively evaporated primary coolant, that is only steam D, before. The medium M held in the container 2 thus has a first boundary layer 12 between water W and the phase mixture W, D and a second boundary layer 14 between the phase mixture W, D and the vapor D.

A large number of operating parameters are provided for monitoring the operation of the nuclear plant. Among other things, it may be desirable or necessary to monitor the position of the boundary layers 12, 14. For example, the position of the boundary layer 14 can take place via a fill level measurement.

The system 1 is provided for the prompt determination and monitoring of positional characteristic values of the boundary layers 12, 14. To this end, system 1 is designed to use the so-called TDR measurement principle (time-domain reflectometry). For such a TDR measurement, a substantially vertical coaxial cable 16 serving as an antenna is provided within the reactor pressure vessel 2. The coaxial cable 16 is led out of the reactor pressure vessel via an electrical feedthrough 18 and connected to the signal line 6. The communication interface 10 connected to the signal line 6 is in turn connected to a pulse generator 20 that generates the electromagnetic pulses and to an evaluation and control unit 22 with an output module 24 and a memory module 26. Of course, the evaluation and control unit 22 is also connected to other components required for proper operation, such as an input device. With its components, System 1 is specifically geared towards the use of the TDR measuring principle. For this purpose, a particularly high-quality signal transport in the lines provided for this purpose, in particular the signal line 6, is desired. In order to particularly favor this, the signal line 6 is in turn designed as a rigid coaxial cable.

However, in order to enable maintenance work on the reactor pressure vessel 2, it may be necessary to disassemble the signal line 6 as required into individual sections and to reassemble them, for example at different points between the bushing 8 and the bushing 18 and apart quickly and easily after maintenance work has been completed to couple. For this purpose, the signal line 6 is composed of a plurality of coaxial cables 30, 32 which are detachably connected to one another via a coupling 33.

In order to meet the overall high demands on the transmission quality, the clutch 33 is also specifically designed for this design goal. In particular, it is provided that the coupling 33 produces a particularly intimate electrical contact between the central conductors 34 and 35 of the coaxial cables 30, 32 to be connected, while being easy to operate overall.

As shown in FIG. 2, the coaxial cable 30 and the coaxial cable 32 have a sheathed conductor 36 or 37 and a central conductor 34 or 35. The coupling 33 provided for connecting the coaxial cables 30, 32 to one another accordingly consists of a first coupling piece 38 and a second coupling piece 39, the coaxial cable 30 being firmly connected to the first coupling piece 38 and the coaxial cable 32 being firmly connected to the second coupling piece 39. The first coupling piece 38 comprises a connection area 40 which is connected to the central conductor 34. The second coupling piece 39 also comprises a connection area 41, which is connected accordingly to the central conductor 35 of the second coupling piece 39. To produce a particularly intimate contact, the connection area 41 is equipped with a connection head 42 which can be brought into contact with the connection area 40 and which is resiliently removed from the actual connection area 41 via a spring element 43. is supported. The spring of the spring element 43 is tensioned when the coupling 33 is closed and, due to its restoring force, constantly presses the connecting head 42 against a corresponding contact surface of the connection area 40 of the first coupling piece 38 and thus ensures a particularly reliable electrical connection. Suitable springs are, for example, spiral springs, disc springs, leaf springs or coil springs as in the exemplary embodiment.

In order to achieve a particularly easy assembly of the connection head 42 and the connection area 40 and a self-centering of the connection head 42, the connection head 42 is equipped with, for example, a convex tip 44, which in the exemplary embodiment is shaped like a truncated cone, and which fits into a provided, for example inserts concave recess 45 in the connection area 40. The recess 45 is conical in the exemplary embodiment and thus its contouring is adapted to the tip 44 of the connecting head 42. A high-quality electrical contact between the connection head 42 and the connection area 41 of the second coupling piece 39 carrying this is made possible by contact fingers 46 attached to the connection head 42. These enclose a contact piece 47 attached to the connection area 41 and, depending on the load on the spring element 43, lie against a larger or smaller area of the contact piece 47. The contact fingers 46 can slide along the contact piece 47, the electrical contact between the connecting head 42 and the connection region 41 of the second coupling piece 39 being ensured in every position of the contact finger 46. This ensures high-quality electrical contact between the connecting head 42 and the connection region 41 even with a varying length of the spring. The connection head 42 is held on the connection area 41 by a retaining screw 50. As a result, a complete loosening of the connecting head 42 is reliably avoided, even when the clutch 33 is open.

The sheathed conductors 36 and 37 surrounding the connection areas 40 and 41 of the coupling pieces 38 and 39 are each provided with a mounting flange 52 which allows the coupling pieces 38 and 39 to be connected to one another. FIG. 3 shows a cross section through the jacket conductors 36 and 37 of the coupling pieces 38 and 39 with a closure element 54 enclosing the flanges 52 and thereby connecting the coupling pieces 38 and 39, for example a clamping ring, which is held together by a spring clip (not shown).

FIG. 4 likewise shows a cross section through the jacket conductors 28 of the coupling pieces 38 and 39 with a closure element 54 which surrounds the mounting flanges 52 and thereby connects the coupling pieces 38 and 39 and which is equipped with a circumferential seal 56. The seal 56 allows a particularly tight and secure closure of the coupling 33 by the closure element 54.

LIST OF REFERENCE NUMBERS

system

RPV

containment

signal line

execution

Communication Interface

interface

antenna

execution

pulse generator

Evaluation and control unit

output module

memory module

coaxial

clutch

Central Head

external conductor

First coupling piece

Second coupling piece

terminal area

connecting head

spring element

top

recess 46 contact fingers

47 contact piece

50 retaining screw

52 mounting flange

54 closure element

56 seal

S signals

W water

D steam

M medium

Claims

Expectations

1. Coupling (33) for connecting two coaxial cables (30, 32), each with a central conductor (34, 35) surrounded by a sheathed conductor (36, 37), with each coaxial cable (30, 32) having a coupling piece (38, 39), each of which has a connection area (40, 41) electrically connected to the central conductor (34, 35) of the coaxial cable (30, 32) assigned to it, one for establishing electrical contact with the connection area (40) of the first coupling piece (38) provided, displaceably mounted on this connecting head (42) of the second coupling piece (39) is supported at the connection area (41) thereof via a spring element (43), characterized in that the connecting head (42) is provided in a number of contact fingers (46) that fit into recesses in the connection area (41) of the second coupling piece (39), the connection area (41) of the second coupling piece back (39) is provided with a contact piece (47) which has an associated connection surface for the or each contact finger (46).

2. Coupling (33) according to claim 1, wherein the connecting head (42) and the connection area (40) of the first coupling piece (38) have such coordinated contact surfaces in such a way that the connecting head (42) self-centering with respect to the coupling Longitudinal axis of the coupling (33) connects to the connection area (40) of the first coupling piece (38).

3. Coupling (33) according to claim 1 or 2, wherein the connecting head (42) carries a truncated cone-shaped tip (44) which has a conical recess (45) made in the connection region (40) of the first coupling piece (38) ) corresponds.

4. Coupling (33) according to one of claims 1 to 3, wherein the connecting head (42) is held by a retaining screw (50) on the connection area (41) of the second coupling piece (39).

5. Coupling (33) according to one of claims 1 to 4, wherein each of the connecting region (40, 41) surrounding sheathed conductor (36, 37) of each coupling piece (38, 39) is provided with a mounting flange (52).

6. Coupling (33) according to claim 5 with a circumferential seal (56) introduced between the mounting flanges (52).

7. Coupling (33) according to claim 5 or 6, in which the mounting flanges (52) are enclosed in the assembled state by a common closure element (54).

8. Coupling (33) according to claim 7, wherein the closure element (54) comprises a clamping ring and a spring clip.

9. Coupling (33) according to claim 8 with a circumferential seal (56) introduced between the mounting flanges (52).

10. Coupling (33) according to claim 8 or 9, in which the mounting flanges (52) are enclosed in the assembled state by a common closure element (54).

11. Coupling according to claim 10, wherein the closure element (54) comprises a clamping ring and a spring clip.