EP0211446B1 - Electromagnetic relay with two armatures - Google Patents

Abstract

A relay includes two armatures each having a contact spring and a contact piece secured thereto which interacts with the respective cooperating contact element. The two movable contact pieces are electrically connected by a stranded copper conductor so that a series connection of the two contacts is formed. The series connection can be interrupted twice by the two armatures which switch independently of one another so that a reliable opening of the circuit is assured even if one of the contacts fuses. The relay is particularly useful for safety circuits such as in motor vehicles.

Description

The invention relates to an electromagnetic relay with a coil with a bobbin, winding and axially continuous core, the axis of which is parallel to the mounting plane, further with a yoke arranged next to the coil and parallel to the axis thereof and with two flat armatures, one of which is attached to one The coil end is arranged perpendicular to the coil axis and is supported at each yoke end and forms a working air gap with one end of the core, each armature carrying a contact piece via a contact spring and each having an extension, which extends beyond the bearing point, for attacking return spring means.

Such a relay is known from FR-A 783 822. There, however, the contact springs of the two anchors are angled at an angle such that they work together with a common center contact element. The contact springs themselves also each have a connection to an associated connection element via a flexible conductor element. The armature is reset separately for each armature using its own return spring device, which can be individually adjusted with a special device.

A similarly constructed relay with two armatures is also known from FR-A-204 870. There, the advantage of the double working air gap is used to independently operate a separate changeover contact with each armature. The center contact piece is attached directly to the rigid armature, while the counter-contact elements are anchored in a base. The two armatures or their contact pieces are insulated from one another by an insulating intermediate layer, so that the two circuits of the changeover contacts are independent of one another. Since the direct connection of the contact piece and armature leads to an overdetermination of the armature stroke, there is also provision in one embodiment for pretensioning two core parts with an intermediate spring against the two armatures, but in this case an additional insulating film must be provided, which also covers the fallen ones Anchors against the core parts and electrically isolated from each other.

In addition, there is the general problem of welding contacts with relays. This problem occurs particularly frequently when high powers are to be output with relatively low battery voltages, so that very high currents flow through the contacts, as is the case in motor vehicles. In this area of application in particular, there is a high safety risk if a relay contact is welded in a safety device, for example an anti-lock braking system, and can no longer be opened, so that a high current, which should only flow for a short time, flows continuously, the winding and other parts warmed inadmissibly and also causes further damage.

The object of the invention is to develop a relay with two armatures of the type mentioned in such a way that it can be used in safety circuits, the tendency to weld being considerably reduced and, moreover, ensuring that the circuit is still reliably opened when a contact is welded.

According to the invention, this object is achieved in that each armature interacts via its associated contact piece with a mating contact element having a connection, that the contact pieces of the two armatures are connected to one another via a flexible electrical conductor element, that the two armatures are each mounted on a bearing edge of the yoke and that the extensions of the two anchors are connected to each other behind the cutting edges via a common tension return spring.

In the relay according to the invention, in particular the risk of welding of two contacts which can be connected in series is significantly reduced. The common spring gives both anchors the same restoring force. Should one of the two anchors no longer fall off due to the welding of its contact, the other anchor receives an even greater restoring force due to the tensioned return spring and therefore falls off all the more safely.

What is also important in the invention, however, is the electrical connection of the two movable contact pieces, which can be actuated independently of one another by the two armatures. In this way, the two contacts can be connected in series in the load circuit, which increases safety considerably, since usually only two of the series contacts are welded.

However, the use of two electrically connected contacts in a two-arm relay is also particularly advantageous because the magnetic properties of the two-arm relay are additionally exploited here. Since the two working air gaps are simultaneously reduced when the two anchors are pulled out of the idle state, the attraction increases disproportionately compared to the attraction of a single anchor, as a result of which the switching speed is particularly high at the moment the two contacts are closed, so that the tendency to weld is additionally reduced. This is particularly important for applications in motor vehicles or similar battery-powered systems. With the contacts connected in series, the load current only flows when both armatures are already close to the pole face, i.e. the two air gaps have already become very small and become almost zero. If this state is reached, the two anchors are fully tightened to the core pole surface even if the battery voltage should collapse due to the closing of the contacts and the flow of a large load current. This also helps to avoid a floating state when the contacts are closed, which in most cases would lead to the welding of a contact. Since the relay winding is designed in such a way that the required attraction or the required force for two dropped armatures Flux are generated, the relay according to the invention results in a very favorable ratio of response voltage and pull-through voltage, so that in the last part of the tightening movement a very fast tightening of the armature is made possible with the application of high contact forces.

The described advantages of the relay according to the invention are particularly effective when both contacts of the relay are designed as make contacts. In this case, the closing of the contacts goes hand in hand with the tightening of the two anchors, whereby the largest magnetic forces are also converted into correspondingly large contact forces when the anchors are tightened.

For certain applications, however, the two contacts of the relay can also be designed as openers, which open independently of one another when welded. In this case, however, the associated armature is also retained when a contact is welded, so that the magnetic circuit can no longer be closed completely. If the relay is designed accordingly, the second armature can still pull in and interrupt the series circuit via the second break contact.

In a further modification it can also be provided that a copper wire connecting the two make or break contacts is provided with an additional connection element of its own. In this case it would be possible to make a parallel connection instead of the series connection of the two contacts, so that a double closer or a double opener is produced. In this case, it is no longer guaranteed that the parallel circuit will still be interrupted when one contact is welded, but such an application can be very useful for certain purposes. It is thus possible to set the two contact distances differently in the configuration as a double closer or double opener, so that the two contacts close or open one after the other. At the earlier closing or later opening contact, where welding could occur, it is then expedient to use a contact material which has only a slight tendency to sweat.

In contrast to the known relay mentioned at the outset, the relay according to the invention cannot usefully be operated with changeover contacts, since when one contact is welded, a bridging between the two switched circuits would occur via the electrical connection of the two movable contact elements. However, it is conceivable to attach a mating contact element in the manner of changeover contacts to the respectively unused switching position of the armature or the movable contact piece. These additional mating contact elements are then expediently not used for switching a second circuit, but only for monitoring. In this case, a logical link could be used to determine, for example, if one of the contacts is welded. Although the function is not yet disturbed due to the relay design, since the second armature still safely interrupts the circuit, the display of such a monitoring circuit could prompt an exchange of the relay before the second contact should also weld.

In the case of the relay according to the invention, it is expediently provided in terms of construction that the electrical conductor element is a strand of copper or a similarly highly conductive material which is welded directly onto the two contact pieces. This means that a high load current can be conducted between the two contacts without the risk of excessive heating. The contact spring generating the contact pressure on the respective armature can then be made from an optimal spring material, for example spring steel, which does not have to have very good electrical conductivity.

The coil former expediently serves as a carrier for the functional elements of the relay. For example, the two coil former flanges can each have recesses for the plug-in fastening of the yoke, and further recesses for holding the copper strand. On the side opposite the yoke, the coil flanges expediently each have recesses for the plug-in fastening of the mating contact elements.

• Fig. 1 und 2 in zwei verschiedenen, teilweise geschnittenen Ansichten ein erfindungsgemäß gestaltetes Relais mit unabhängig voneinander öffnenden Schließerkontakten,
• Fig. 3 und 4 ein entsprechendes Relais mit unabhängig voneinander schaltenden Öffnerkontakten,
• Fig. 5 und 6 ein entsprechend aufgebautes Relais, dessen Kontakte als Doppelöffner geschaltet sind und
• Fig. 7 und 8 ein entsprechend aufgebautes Relais mit als Doppelschließer ausgebildeten Kontakten.

The invention is explained in more detail below using exemplary embodiments with reference to the drawing. Show it

• 1 and 2 in two different, partially sectional views, a relay designed according to the invention with independently opening normally open contacts,
• 3 and 4 a corresponding relay with independently switching NC contacts,
• 5 and 6 a correspondingly constructed relay, the contacts of which are switched as double openers and
• 7 and 8 a correspondingly constructed relay with contacts designed as double closers.

The relay shown in FIGS. 1 and 2 has a coil former 1 with a core 2 pressed into an axial through-bore and having two pole faces 3 and 4 at its ends. The coil former has two flanges 5 and 6, between which a winding 7 is applied.

The coil formed by coil former 1, core 2 and winding 7 is arranged with its axis parallel to an installation plane on a flat base 8, which forms a housing with a cap 9. In the overlap area 10, the two housing parts can be welded, for example, with ultrasound.

The magnetic circuit of the relay has a flat flux plate or yoke 11, which is arranged essentially perpendicular to the installation plane next to the coil and is fixed in recesses 12 of the coil body flanges 5 and 6 by insertion. Extensions 13 of the yoke 11 are also anchored in the base 8. At both ends, the flux plate has bearing edges 14 and 15, on which an anchor 16 and 17 is mounted. To the anchor against lateral displacement on the bearing To secure cutting, the yoke is provided in the usual way with incisions 18 or projections 19. Each anchor has an extension 16a or 17a in the area behind the bearing cutting edge, and on these two extensions a common return spring 20, which is under tension, engages and the two anchors with the same restoring force in their rest position, ie in the dropped position , pulls.

A contact spring 21 or 22 is attached to each of the two anchors, which carries a contact piece 23 or 24. Both contact pieces are connected to one another via a copper braid 25 which is guided around the outside of the two armatures and is connected at its ends directly to the relevant contact piece 23 or 24 through a recess in the contact spring 21 or 22. As a result, a possibly high switching current is not conducted via the contact springs made of spring steel or via the armatures.

Opposing the two movable contact pieces 23 and 24, two fixed mating contact elements 26 and 27 are anchored in recesses 5a and 6a of the bobbin flanges 5 and 6, respectively, by insertion. They each have molded pins or plugs, e.g. B. 26a, which are guided through the base 8. Below the winding 7 there is still space for additional components 28, such as diodes or resistors, on the base.

The function of the relay has already been explained at the beginning. When the coil is excited via the winding 7, both armatures 16 and 17 are attracted to the core 2; the two contacts 23 - 26 and 24 - 27 close. A series circuit between the two mating contact elements 26 and 27 is thus closed via the strand 25. When the excitation is switched off, both anchors drop out, so that the circuit is interrupted twice. Should one of the two contacts 23-26 or 24-27 weld, the other contact will still open via the associated second anchor.

3 and 4 show a slightly modified form of the relay. The same parts as in FIGS. 1 and 2 are also provided with the same reference numerals. The only difference from the first example is the design and arrangement of the contacts. The two contact springs 21 and 22 now carry outwardly directed contact pieces 33 and 34, which interact with counter-contact elements 36 and 37. The relay thus contains two break contacts, which form a series connection via the two armatures 16 and 17 in the idle state and which interrupt the circuit twice independently of one another when the relay is excited. Even when one NC contact is welded, the second armature can still pull in (although not with an optimally closed magnetic circuit) and interrupt the circuit.

A further modification is shown in FIGS. 5 and 6. There, the two contact springs 21 and 22 are connected via a strand 35, which is also brought up to an additional plug connection 38. The two break contact pieces 33 and 34 thus have an additional common connection and can therefore also be connected in parallel as a double break contact. The operation of the relay is the same as in the previous examples. In order to switch welding off as far as possible, the two contacts can be set with different contact spacing and equipped with different contact materials, so that one contact with weld-resistant material opens or closes last and thus draws the arc that may occur, while the other contact with a material with high conductivity carries most of the load current during operation, but is not exposed to an arc.

7 and 8 show a corresponding modification for the relay with make contacts. In this case, the strand 35 is guided from the contact pieces 23 and 24 to the additional connection 38. This relay can therefore be used as a double closer relay, whereby the two normally open contacts are connected in parallel, but are actuated via the two armatures which are magnetically connected in series. In this case too, a high degree of security can be achieved with different contact spacings and the use of weld-resistant contact material for the first closing or last opening contact.

To understand the drawings, it should also be mentioned that various symmetrical parts have been omitted, such as armature 17 and contact elements 22, 24, 27 and 37 in FIGS. 1 and 3.

Claims (8)

1. Electromagnetic relay comprising a coil with a coil former (1), a winding (7) and a core (2), which passes through axially and whose axis runs parallel to further comprising a yoke (11) arranged alongside of the coil (1, 7) and parallel to the axis thereof, and comprising tow flat armatures (16, 17) of which in each case one is arranged at a coil end perpendicular to the coil axis, and is mounted at a yoke end in each case, and forms a working air gap with an end of the core (2) in each case, each armature (16, 17) carrying a contact member (23, 24) via a contact spring (21, 22) in each case, and having in each case an extension (16a, 17a) which is prolonged beyond the bearing point in order to engage with restoring spring means, characterized in that each armature (16, 17) cooperates via its associated contact member (23, 24) with a counter-contact element (26, 27) having a connector (eg. 26a), in that the contact members (23, 24) of the two armatures (16, 17) are connected among another via a flexible electric conductor element (25; 35), in that the two armatures (16, 17) are mounted in each case on a bearing knife-edge (14, 15) of the yoke (11), and in that the extensions (16a, 17a) of the two armatures (16, 17) are connected to one another behind the bearing knife-edges (14, 15) via a common tension restoring spring (20).

2. Relay according to Claim 1, characterized in that the electric conductor element (25; 35) is a litz wire of copper or a material conducting similarly well, which is welded directly onto the two contact members (23, 24; 33, 34).

3. Relay according to Claim 1 or 2, characterized in that the two coil former flanges (5, 6) have cutouts (12) for securing the yoke (11) by plugging in.

4. Relay according to one of Claims 1 to 3, characterized in that opposite the yoke (11) the two coil flanges (5, 6) in each case have cutouts (5a, 6a) for securing a counter-contact element (26, 27; 36, 37) by plugging in, in each case.

5. Relay according to one of Claims 1 to 4, characterized in that the two contacts (23; 26; 24; 27) are constructed in each case as make contacts.

6. Relay according to one of Claims 1 to 4, characterized in that the two contacts (33; 36; 34, 37) are constructed as break contacts.

7. Relay according to one of Claims 1 to 6, characterized in that the conductor element (36) connecting the two movable contact members (23, 24; 33, 34) is provided with its own connection element (38).

8. Relay according to Claim 7, characterized in that the two contacts open or close one after another, the earlier closing or later opening contact being formed by contact members of low tendency to weld.

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