EP0207365B1 - Method of making a reed relay for switching high frequency currents, and reed relay made in this way - Google Patents

Abstract

In a method for producing a reed relay, and a reed relay produced in accordance therewith, for switching r.f. currents at high voltages, it is proposed to arrange the coil, which is wound upon a normal bobbin with flanges on both sides, within a low-ohmic coil shielding by mounting the bobbin with the coil in an outer tube of brass, fitting an inner tube, likewise of brass, in the bobbin and connecting the two tubes by annular end disks placed on the two ends and joined with the tubes by pressing. The whole assembly comprising the bobbin, the coil and the shielding is then mounted on a two-piece bobbin carrier, and the vacuum glass tube of the r.f. reed switch is inserted into the bearing tube of the bobbin carrier and preferable fixed therein by means of a silicone hose.

Description

The invention is based on a method according to the preamble of claim 1 and a reed relay according to the preamble of claim 7.

In a known reed relay (US-A-3 560 898), which is also suitable for switching high-frequency currents, as coax relays, a larger and a smaller reed switch are arranged side by side in a trough-shaped, metallic main bearing part, which can be screwed to a cover whose connections are combined on one side, thereby isolating the inner conductor, leading to the outside, while on the other hand, the reed switch connections penetrate the housing end wall separately. The reed switches are surrounded by a non-magnetic material, but an electrically conductive shield in the form of an inner tube, which at both ends is firmly connected, for example soldered, to inner projections of the trough-shaped metallic housing, so that even in the area of the reed Switch maintains an approximately geometrical coaxial configuration with correspondingly reduced leakage losses and minimized disturbance of the wave resistance of the coax lines led into the switch area.

This known coaxial reed relay therefore only pays attention to a flawless and as far as possible coaxial shielding of the inner conductor, which is formed in the area of the reed relay by the resilient contact tongues of the reed switch. A shielding of the coil against interference from the reed switch is not mentioned and is therefore not attainable, because with the underlying design of this known coaxial reed relay, the reed switches located in the coil carrier cavity together with the coil must be inserted into the housing from the open tub side and by applying a cover, the reed relay is then properly shielded from the surroundings by the closed shape, but not the coil with respect to interference, which originate from the reed switches or the inner conductors continued inside the housing. Radiation emanating from these can reach the cover side Escape freely from the inner tube shield and act on the coil from both sides.

Another known magnetic relay (US-A-4 225 836) has an inner tube located between the coil carrier and the reed switch, furthermore lateral end plates and an outer tube, but is not suitable for shielding any parts to the outside or to one another directed, but should ensure a low sensitivity for the excitation coil with a total miniaturized construction, a high sensitivity in the switching range, for which purpose the material surrounding the coil is of particularly high magnetic conductivity in order to collect the flux emanating from the coil and concentrated through an opening in the inner tube directly to the movable switch contacts of the reed switch. From this point of view of a coil shield, this, of all places, central opening in the inner tube results in barely door-sized openings for the passage of high-frequency energy into the coil area, which runs counter to the basic idea of the present invention. In fact, the materials which can preferably be used for the implementation of the invention, such as copper or brass, which have a high electrical conductivity and are therefore particularly low-resistance, in order to achieve the desired low-resistance coil shielding, in the magnetic relay of this publication (US Pat. No. 4,225,836 ) cannot be used because these materials are non-magnetic.
Such magnetic relays (another can be found, for example, in DE-B-27 19 230 (= ̂ FR-A-2350678)) all have a magnetic yoke structure, which is not intended to counter the coil against the reed contacts shielding a high-frequency influence, for reasons that will be discussed further below, but rather the magnetic field emanating from the coil should be bundled and strengthened in a direction of action extending from the outside inwards. Because of the air gap in the inner tube, which is then necessary, the coil is completely free and unprotected against the effects of the reed switch.

In general, reed relays are manufactured in such a way that the glass tube of the vacuum reed switch with the associated switching coil is inserted into a rectangular housing with an open side wall, and then the housing is preferably hermetically sealed with a suitable synthetic resin, with the respective connection contacts including the coil connections being led outside are.

Known reed relays therefore usually include a coil carrier, which forms the coil and at the same time supports the glass tube of the reed switch so that when the excitation is energized, the contact tongues move - the coil body can therefore, in one piece, simultaneously be a carrier for the coil and housing for the reed switch and thus forms the reed relay overall.

Problems can arise with the usual embodiments of reed relays and in their manufacture if they are intended to carry particularly high-frequency currents or signals (for example 30 MHz for currents up to for example 5 A) and operating voltages which can be, for example, kV _SS . In such operating conditions, which are unusual for conventional reed relays and therefore extreme, there may be disadvantages due to the strong, high-frequency electromagnetic fields, which at least lead to increased temperatures in the entire coil and relay area, so that in addition to a possible change in the electrical data, the stability of the reed relay can suffer itself.

The invention is, moreover, expressly not a so-called coax relay (see DE-C-814 915 or essay "protective gas contacts ..." by Jung / Welz in frequency 1960, pp. 392-394), in which a constant wave resistance is maintained (Coding of coax relay) an outer tube (outer conductor) to the (inner conductor) switch is arranged over the entire length and at a constant distance. On the contrary, everything that couples should be avoided in the invention. It should therefore be prevented that energies from the HF range reach the coil, for example in order to avoid heating of the excitation coil.

Accordingly, the invention is based on the object of designing a manufacturing method for a reed relay and creating a reed relay in such a way that, by means of particularly good low-resistance shielding in the coil area, the disadvantageous effects (i.e. high-frequency influence / high-voltage influence / influence) higher currents) can be avoided.

Advantages of the invention

The manufacturing method according to the invention and the reed relay manufactured by this method each achieve this object with the characterizing features of claim 1 and claim 7 and have the advantage that there is a particularly good resistance to the strong influence of the high-frequency electromagnetic fields emanating from the reed switch itself , at the same time inexpensive and simple construction of the relay.

The invention is based on the knowledge that, contrary to the usual reed relay form, a division in the area of the bearing of the coil or the relay is necessary, firstly to implement the low-resistance coil shielding and secondly to ensure the vacuum glass tube of the reed switch and the entire reed relay to store.

It is also advantageous that the use of the present invention makes it possible to use (plastic) materials for the coil former and / or coil former carriers which have dielectric properties which are particularly suitable for the field of RF applications, but on the other hand because of an existing, only low temperature stability otherwise, namely in the absence of the guaranteed by the invention, low-resistance coil shielding could not be used, since the heat loss generated by a poorly shielded coil would severely impair the stability of such materials, and possibly even melt them at the limit.

The arrangement of a properly terminated, low-resistance shield around the coil is not known in the field of reed relays; insofar as shields are present, more often in the form of closed magnetic yoke structures, they concentrate on bundling and influencing magnetic field lines without paying more attention to the ratio of coil to contact springs than is the case, or metallic shields are proposed for high-voltage relays, but Pack the coil and contact springs together in an envelope. In contrast to this, the invention acts selectively only on a low-resistance shield, which surrounds the coil, and protects it against effects from the contact springs of the reed switch, it being understood that this low-resistance shield has no magnetically disadvantageous effects, for example made of a material such as brass or other non-magnetic metal.

These measures represent advantageous developments and improvements of the invention and are set out in the subclaims, the formation of the shield advantageously consisting of brass tubes and brass end-face punching rings consisting of additional hot-dip tinning result in a particularly intimate connection of the shielding parts and secure low-resistance inclusion exclusively of the coil in its coil body.

The connection of the shielding parts can be brought about by means of a suitable pressing pressure using a tool, the end ring disks being pressed into the outer tube in a form-fitting manner and the closed inner tube then being pressed into the central bore of the end disks. This results in a complete and all-round metallic shielding. But it is also possible to solder the end disks with the inner and outer tube.

Fig. 1

in einer Schnittdarstellung den Spulenkörper mit darauf angedeuteter Spulenwicklung, beide hermetisch eingeschlossen in eine metallische Umhüllung und

Fig. 1a

die Darstellung der Fig. 1 in einer Stirnansicht - lediglich Spulenkörper

Fig. 2a bis 2d

einen zur Vervollständigung des Reedrelais nachträglich aufzubringenden Teil eines Spulenkörperträgers in Seitenansicht, Draufsicht, Ansicht von vorn und von unten jeweils;

Fig. 3a und 3b

einen die Darstellung der Fig. 2a bis 2d vervollständigendes Teil des Spulenkörperträgers und

Fig. 4

in Draufsicht einen Stanzring, der ergänzend zu einem inneren und einem äußeren Messingrohr die metallische Abschirmung des Spulenkörpers mit Wicklung bildet.

An embodiment of the invention is shown in the drawing and is explained in more detail in the following description. Show it:

Fig. 1

in a sectional view the bobbin with indicated coil winding, both hermetically enclosed in a metallic casing and

Fig. 1a

the representation of Fig. 1 in a front view - only bobbin

2a to 2d

a part of a bobbin carrier to be subsequently applied to complete the reed relay in side view, top view, front and bottom view;

3a and 3b

a part of the bobbin support and the representation of FIGS. 2a to 2d

Fig. 4

in plan view a punching ring which, in addition to an inner and an outer brass tube, forms the metallic shield of the coil body with winding.

Description of the embodiments

The basic idea of the present invention is to manufacture a high-frequency reed relay by winding a separate coil former with the electrical coil, so to speak, to wrap this coil former in a metallic sheathing that forms a low-resistance shield, and then to connect the whole thing to a divided coil former carrier, which then at the same time stores and receives the vacuum reed switch in an inner tube, with which the high-frequency currents (for example 30 MHz at for example 5 A and operating voltages of for example 5 kV _ss ) are switched.

The basic manufacturing process therefore takes place in such a way that on the bobbin designated by 10 in FIG Pipe part 10a is constructed with flanges 10b, 10b 'on both sides, the coil is wound, the coil catch and coil end, as indicated at 11a and 11b, being led out through tubular holes 12 into the coil flange 10b, 10b'. In the illustration in FIG. 1, the coil wound on the bobbin 10 is only indicated and provided with the reference number 13.

This finished "coil" is then completely shielded with a low resistance, namely by introducing a first metallic tube 15 into the inner ring passage 14 of the coil body 10, which, like the other shielding parts, preferably consists of brass and, together with the others , parts to be mentioned causes the required high-frequency shielding.

In an advantageous addition, a magnetic shield made of mu-metal is then provided for the coil, preferably in a foil-like configuration, which can be placed overlapping around the coil winding and which collects the magnetic field formed by the control of the coil and also ensures that there is no mutual interference from neighboring relays. The mu-metal foil consists of a particularly magnetically permeable material.

Furthermore, an outer tube 16 is pushed onto the wound bobbin, which therefore accommodates the entire bobbin with coil, and the length of these two tubes 15 and 16 is determined in such a way that - as a preferred embodiment - these end-to-end around extend a predetermined distance beyond the longitudinal dimension of the coil body, so that the completion of the coil shielding can be accomplished by placing so-called face washers 17a, 17b on both sides. The face washers are preferably formed as punched rings and, in a top view, raise the shape shown in FIG. 5, that is to say adjacent to the periphery and diametrically opposite one another, two through holes 18 through which the annular projections forming the tubular holes and extending from the coil flanges can be inserted.

In the embodiment shown in Fig. 1, the inner bore dimensions and the outer ring dimensions of the double-sided face washers, which can preferably be punched rings, are held so that there is preferably a slight oversize, so that the inner bore of each punched washer is slightly smaller than that Diameter of the inner tube 15, while the outer diameter of each end washer is preferably slightly larger than the inner diameter of the outer tube 16.

In this way it is namely possible to assemble and connect all four brass parts 15, 16, 17a, 17b into an intimate, very low-resistance connection which hermetically encloses the coil body with coil.

Preferably, the procedure is such that the four brass parts used here are hot-tinned and the assembly is carried out by a pressing process in a suitable tool, in which the double-sided face washers are pressed into the outer tube and, at the same time, the inner tube is pressed into the central opening of the face washers, sometimes with a corresponding one , slight material deformation, which results in a firm positive and non-positive cohesion of all screen parts with each other.

It goes without saying that the described form of the shield can also be made differently; for example, the end ring disks can also be cap-shaped, in which case they are then slipped over the outer tube 16 with inwardly directed ring flanges, and at the same time inner ones can be drawn from the inner bore ring flanges emanating from the end ring washers are pressed into the interior of the inner tube 15 - here, that is to say in the area of the connection of the individual shielding brass parts, design options are therefore open.

Subsequently, the coil with the coil former packed into the low-resistance metallic shield is connected to the coil former carrier shown in FIGS. 2a to 2d and 3a and 3b, which is constructed as follows.

The first part of a bobbin carrier 18a shown in FIGS. 2a and 2d - the second part corresponding to FIGS. 3a and 3b is designated by 18b - comprises a longitudinal tube 19 which is hollow on the inside and serves to enter the inner tube 15 to be inserted in the combination unit of the coil former with the coil and the shield, as flush as possible, up to one of a bearing flange 20, which is preferably integrally connected to the tube 19. The first part of a coil former carrier 18a preferably consists of a suitable plastic material such as polypropylene, for example with the Description Vestolen and is formed in one piece with the support tube 19 and end bearing flange 20, the support tube 19 passing through a vertical wall 20a of the bearing flange 20 and with this and a base plate 20b vertically attached to the wall 20a to form an L-shape of the support flange 20 via medium Reinforcing ribs 21 is connected, the two legs of the L-shape can also be connected by lateral triangular ribs 22 for reinforcement.

As can best be seen from the illustration in FIG. 2c, the one partial wall 20a of the bearing flange 20 has lateral incisions 23a, 23b which accommodate the projecting tubular projections 12 of the coil body on both sides, which also after the "packing" by the Shielding material extend beyond its outer dimensions. This simultaneously results in the torsion-proof, secure mounting and anchoring of the coil former unit with coil and shield on the coil former carrier 18, it being understood that after this unit has been pushed onto the carrier tube 19, the structure of the coil former carrier and thus also the entire structure of the high-frequency reed relay is different Completed by the fact that the second bearing flange 20 'shown in FIGS. 3a and 3b is pushed onto the bearing tube 19 protruding to the right in the drawing plane of FIGS. 2a to 2d. This therefore has, in addition to the base plate 20b 'and the vertical wall 20a', a tubular extension 24 which is pushed out over the bearing tube 19, so that there is a secure and non-rotatable connection overall with the first part 18a of the bobbin carrier 18 and , again here, guaranteed by lateral receiving slots 23a ', 23b', which results in the form-fitting anchoring of the coil former with its tubular projections 12.

In the assembled state, the bearing tube 19 then extends approximately on both sides as far beyond the bearing flanges 20a, 20b of the coil former carrier 18, as shown in FIGS. 2a, 2b, which also represent the dimensions of the reed relay in natural size if the unit comprising the coil former is included The coil and shield as well as the second flange part are pushed on.

The final structure of the reed relay is then completed by inserting and fixing a special high-voltage switch, which is manufactured separately in a form not to be discussed further here as a vacuum glass tube with contact paddles fused in on both sides, into the interior of the bearing tube 19. The attachment can be done, for example, by double-sided (silicone) tube pieces, which firmly press the glass tube of the reed switch, not shown in the drawings, into the inner opening of the bearing tube 19 under pressure; however, it is also possible to completely surround the vacuum glass tube with a silicone tube and then to push the whole thing into the bearing tube 19.

Before the glass tube of the reed switch is inserted, the coil ends can also be soldered to coil connecting pins arranged on the two bearing flanges 20, 20 '(not shown in the drawing).

While maintaining the same basic concept, the invention also makes it possible to design such a high-frequency / high-voltage reed relay as a rest relay by arranging a magnet, preferably designed as a ring magnet, in the coil former with coil and shielding unit. For this purpose, the procedure can be such that the inside diameter of the coil former 10 shown in FIG. 1 is increased somewhat so that the ring magnet has space. It goes without saying that the insertion of the inner brass tube 15 then takes place in such a way that the ring magnet required to complete the relaxation relay is shielded from the high-frequency field, that is to say it is located within the shield.

A high-frequency reed relay with such a structure has the technical data which is also given below, it being understood that this information does not restrict the invention, but merely specifies one exemplary embodiment in more detail.

Measurements on such a reed relay have shown that the coil heats up to a maximum of 30 Kelvin when the relay is operated at 30 MHz 5 A _rms .

Claims (18)

1. A method for producing a reed relay for switching high frequency currents, for example in the frequency range of 1.5 ... 30 mHz, and where appropriate high voltages, e.g. 5 kV_ss, wherein the coil (13) is wound on a coil body (10) in the interior of which is located a contact pair (reed switch) vacuum sealed in a glass tube and a metallic inner tube (15) is disposed between the coil body (10) and the contact pair (reed switch), characterised in that a metallic outer tube (16) and metallic annular end discs (17a, 17b) at the two ends are further attached to form a low-resistance coil screen, and then the inner tube and outer tube are connected to the annular end discs by means of a further procedure and the unit consisting of coil body (10), coil (13) and the metallic screen (15, 16, 17a, 17b) is attached to a separate coil body support (18) and the vacuum switch is inserted into the bearing tube (19) of the coil body support (18).
2. A method according to claim 1, characterised in that the dimensions, relative to one another, of the metallic screen parts are such that they are joined to one another with a friction fit by means of a pressing procedure conducted under pressure or are even soldered together, during which procedure the inner tube is first inserted into the coil body, the metallic outer tube (16) is then slipped over and the metallic annular end discs (17a, 17b) at the two ends are then placed in position.
3. A method according to claim 2, characterised in that the annular end discs are manufactured in the form of punched rings and are pressed into the outer tube (16) and the inner tube (15) is pressed into a central recess of the annular end discs, and in that all the screen parts (15, 16, 17a, 17b) are made of brass and are hot tin plated before being pressed together.
4. A method according to one of claims 1 to 3, characterised in that the unit consisting of the coil body with the coil and the screen is attached to the coil body support by first slipping it on to the bearing tube (19) of a first part (18a) of the coil body support (18) and by then slipping a second part of the coil body support as an end piece also on to the bearing tube (19).
5. A method according to one of claims 1 to 4, characterised in that when the unit consisting of the coil body with the coil and screen is slipped on to the first part of the coil body support, holes which are located on the coil body support and form tubular extensions and which penetrate the annular end discs at the two ends are inserted into receiving recesses (23a, 23b; 23a', 23b') of walls (20a, 20a') - adjoining on either side - of end flanges on both sides, these being designed as bearing flanges (20, 20') and supporting the bearing tube (19), thereby producing a rotationally rigid and positively locking anchorage of the coil body and coil screen unit on the coil body support.
6. A method according to one of claims 1 to 5, characterised in that the vacuum tube of the reed switch is inserted and secured in position inside the bearing tube (19) of the coil body support (18) with the at least partial interposition of a silicone tube.
7. A reed relay for switching high frequency currents, for example in the frequency range of 1.5 ... 30 mHz, and where appropriate high voltages, e.g. 5 kV_ss, wherein the coil (13) is wound on a coil body (10) and in the interior thereof is disposed a contact pair (reed switch) vacuum sealed in a glass tube and disposed between the two is a metallic inner tube (15), characterised in that a low-resistance coil screen is formed by slipping over a metallic outer tube (16) and by disposing annular end discs (17a, 17b) at the two ends, each butt-joined to one another, and in that the unit composed of the coil body (10) with the winding (13) and the metallic screen (15, 16, 17a, 17b) is attached to the bearing tube (19) of a coil body support (18).
8. A reed relay according to claim 7, characterised in that the individual parts comprising the inner tube (15), the outer tube (16) and the annular end discs (17a, 17b) at the two ends which form the screen are joined or soldered together by a pressing procedure, ensured by the relative oversize in each case, by means of expansion and the friction fit thereby produced.
9. A reed relay according to claim 7 or 8, characterised in that the coil body (10) consists of a central tube (10a) supporting the coil winding (13) with end flanges (10b, 10b') on each side, wherein feed-through openings for the beginning and end of the coil are created in the end flanges by tubular extensions (12) which project laterally.
10. A reed relay according to one of claims 7 to 9, characterised in that the tubular extensions (12) in the coil body flanges (10b, 10b') pass through feed-through openings (18), correspondingly assigned to them, in the annular end discs (17, 17b) which contribute to the formation of the screen, and when joined to the coil body support (18) engage into corresponding recesses (23a, 23b; 23a', 23b') of wall regions (20a, 20a') of the bearing flanges (20, 20') on both sides of the coil body support (18) for the rotationally secure mounting and anchoring thereon.
11. A reed relay according to one of claims 7 to 10, characterised in that the coil body support (18) is divided and consists of a first part with a bearing flange (20) and the bearing tube (19) emerging from it in one piece, on to which is slipped the unit consisting of the coil body with the winding and the screen with the inner metallic screen tube (15), and a second part forming an opposite bearing flange (20') which is similarly slipped on to the bearing tube (19).
12. A reed relay according to claim 11, characterised in that the bearing flanges (20, 20') on the two sides of the coil body support (18) are each L-shaped, with a wall (20a, 20a') extending adjacently to the coil flanges and a bearing plate (20b, 20b') [extending] transversely thereto and connected to the wall (20a, 20a') by way of reinforcing ribs (21, 22).
13. A reed relay according to claim 11 or 12, characterised in that the second part (18b) of the coil body support (18) has a tubular extension (24) which enables the other coil body support part (18a) to be slipped on to the bearing tube (19).
14. A reed relay according to one of claims 7 to 13, characterised in that the parts (15, 16, 17a, 17b) of the screen are made of hot tin plated brass and the coil body (10) and the coil body support (18, 18a, 18b) are made of synthetic material (nylon or polypropylene).
15. A reed relay according to one of claims 7 to 14 with a rest contact, characterised in that there is an annular magnet disposed between the coil and the inner tube (15).
16. A reed relay according to claim 15, characterised in that the annular magnet is an alloy magnet.
17. A reed relay according to one of claims 7 to 16, characterised in that in order to form a supplementary magnetic screen, the coil winding is further disposed in a casing made of magnetically highly conductive material.
18. A reed relay according to claim 17, characterised in that the coil winding is inserted into an overlapping metal foil.

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