EP0022953B2 - Electromagnetic relay - Google Patents

Abstract

In an electromagnetic relay, an armature block serving to actuate contact springs includes a pair of armatures and a permanent magnet disposed therebetween to magnetize the armatures to opposite polarities. Pole ends of a yoke carrying the excitation flux created by the relay coil extend between free ends of the armatures. The armature block is suspended by means of a resilient arm integrally formed with the block at one side thereof and having its outer end fixed to a bearing portion, so that a rocking motion of the armature block is achieved by a flexing motion of the resilient arm.

Description

An electromagnetic relay with the features specified in the first part of patent claim 1 is from "The Bell System Technical Journal" January 1964, pages 15 to 44, in particular FIG. 16 (b) on page 36, and from "Bell Laboratories Record" June 1963, Pages 241 to 243, known. A separate, apparently metallic, two-armed bearing spring is riveted to an armature block made up of two webs and an intermediate permanent magnet, the two ends of which are removed from the armature block so that they rest on surfaces of certain structural parts of the relay and extend with their tips to the housing cap . The cited documents do not disclose whether the two ends of the bearing spring are fixed to the structural parts of the relay or are resilient. A resilient, thus movable system would cause friction when the anchor block rotates. A fixation would mean that bends occur in the spring arms when the armature block rotates. Depending on whether only one or both bearing springs bend, there are different switching movements and a correspondingly inaccurate switching characteristic. In any case, the spring arms must be soft because of the three-point bearing in order to allow the armature block to move at all. Such soft bearing springs do not allow stable switching behavior.

An electromagnetic relay is also known from DE-B2 2454967 and the corresponding FR-A 2 271 654, the magnet system of which is shown in FIG. 17 of the accompanying drawings. This relay has an armature block h with a pair of armature webs e, d which are arranged parallel to one another, in front of and behind projecting ends c of a yoke b which carries a coil winding a. A permanent magnet f is arranged between the anchor webs e, d. The anchor block is mounted essentially in the middle of the anchor webs e, d by means of a round pin i in a bore j.

• 1. Die Achse des Zapfens i muss exakt am Schnittpunkt der Mittellinie X-X der Ankerstege e, d und der Mittellinie Y-Y des besagten Joches b positioniert sein.

The construction of a relay, in which the reciprocating or rotating movement of the armature block is effected with such a journal bearing, has the following disadvantages:

• 1. The axis of the pin i must be positioned exactly at the intersection of the center line XX of the anchor bars e, d and the center line YY of the yoke b.

• (2) Selbstverständlich muss ausserdem zwischen Zapfen i und Bohrung j ein gewisses Lagerspiel vorgesehen sein, das der Spanne der Fertigungstoleranzen gerecht wird. Aber wegen dieses Lagerspiels kann es passieren, dass eines der vorspringenden Enden des Joches von den Ankerstegen nicht berührt wird, während am anderen Ende zufriedenstellender Kontakt erfolgt. Dies wiederum führt zu instabiler Kontaktgabe. Ferner sind die dynamischen Verhältnisse dieses Magnetsystems derart, dass sich die Anlagekräfte (Anzugskräfte) an beiden Enden der Ankerstege auf eine Seite des Zapfens konzentrieren, wobei die resultierende Kraft als Kontaktkraft nutzbar ist. Eine unzureichende Anlagekraft an einem Ende führt zu einer Verringerung der Kontaktkraft unter den Sollwert und verursacht letztlich eine für das elektromagnetische Relais unzureichende Schaltleistung.
• (3) In Verbindung mit Vorstehendem wird, wenn das Lagerspiel zwischen dem Zapfen und der Bohrung zu sehr verringert wird, der Reibungswiderstand so sehr erhöht, dass er von der die Drehung bewirkenden Kraft abgezogen werden muss.

The need for this constructive measure is that the anchor webs e, d are to be supported on the projecting ends of the yoke b. If the pin i is crazy from the intersection of both axes, the ends deviate from the intended setting and each form an air gap at one end, while sufficient attachment is only guaranteed at the other end. This causes bruises and poor electrical contact. Overall, it requires a high degree of manufacturing accuracy to place the pin at the intersection of the two axes.

• (2) Of course, there must also be a certain clearance between the pin i and the hole j, which meets the range of the manufacturing tolerances. But because of this bearing play, it can happen that one of the projecting ends of the yoke is not touched by the anchor bars, while at the other end there is satisfactory contact. This in turn leads to unstable contact. Furthermore, the dynamic conditions of this magnet system are such that the contact forces (tightening forces) at both ends of the anchor webs concentrate on one side of the pin, the resulting force being usable as a contact force. An insufficient contact force at one end leads to a reduction in the contact force below the setpoint and ultimately causes an insufficient switching capacity for the electromagnetic relay.
• (3) In connection with the above, if the bearing clearance between the pin and the bore is reduced too much, the frictional resistance is increased so much that it has to be subtracted from the force causing the rotation.

Furthermore, the construction of such an anchor block is generally carried out in such a way that the permanent magnet is arranged in a one-piece pressed part in the middle between parts which serve as anchor webs e, d. After the spraying or pressing process, however, the influence of the heat causes a change in the distance between the anchor bars, which changes the path of the anchor bars relative to the yoke.

In addition, in this known relay, the actuating part for the contact spring is molded onto the armature block. This design measure is chosen for this relay because large contact forces and a high degree of self-cleaning effect are required to achieve high switching loads and high resistance to contact welding. For this reason, when the contact is selected, contact is made by bending the contact springs. However, in the case of such contact actuation parts, the armature block can move without additional precautions even if one of the contacts is welded and, regardless of the defect, can also close the other contact, which can create further problems in the circuit.

From GB-A 1 025969 it is also known to mount the armature in an electromechanical relay relative to a stationary part by means of a plastic hinge, in which two rigid parts are pivotally connected to one another via a predetermined bending point formed by a wedge-shaped groove. A predetermined bending point generated in this way in a plastic component, which is also bent at right angles in the known relay in the rest position, does not have the durability as that of modern relays for a reasonable service life correspondingly high number of switching operations is required. Rather, there is a risk that the predetermined bending point breaks relatively quickly due to material fatigue and the relay thus becomes inoperable. Apart from this, the known plastic hinge is connected to the relevant relay parts by means of rivets or screws and thus forms a separate component which is subject to tolerances.

Similarly, in the electromagnetic relay according to DE-A 1 094366, the armature is mounted in the form of a thin film via a separate plastic part which is subject to tolerances and which is connected to the relevant components of the relay by mechanical fastening means. Again, there is a risk that the thin plastic film used for storage will break prematurely during operation and render the relay inoperable.

The invention has for its object to provide a relay that is simple in construction and easy to manufacture, which is still free of fluctuations in the armature air gap and the air gap between the yoke and both armature webs, which allows safe opening and closing of the switching contacts, thus has stable switching behavior, and in which there is also a relatively large opening of the switching contacts with respect to the armature opening.

According to the invention, this object is achieved in the relay characterized in claim 1. The fact that the resilient arm is then molded onto the plastic frame that summarizes the armature block means, on the one hand, that mechanical means and additional work steps for fastening the bearing arm to the armature block are eliminated, which simplifies the manufacture and construction of the relay. At the same time, there are no tolerances such as are unavoidable when connecting separately manufactured parts (anchor block - bearing spring). Static problems are also avoided, so that fluctuations in the various air gaps and thus the switching behavior are significantly reduced. Furthermore, since the resilient arm forms two separate compartments for accommodating the switch contacts, it extends, viewed from the anchor, in the direction in which the contact space of the relay is located. The possibility achieved thereby to make the resilient arm relatively long means that it is nevertheless sufficiently flexible with a cross-section of the plastic material that is sufficient for strength reasons, in order not to restrict the mobility of the anchor block. The bending of the resilient arm required for the pivoting movement of the armature is therefore distributed over a relatively large length, so that the risk taken in the invention of using a plastic spring for alternating bending stresses is limited.

An advantageous embodiment of the invention consists in fixing one of the anchor bars, the actuating pieces and the flexible arm, which ensures the rotatable mounting of the anchor, in the shape as a unit, in order to ensure an exact anchor air gap.

According to a further development of the invention, cranks are provided on the surfaces of the two actuating pieces, through which the contact springs are guided such that the inside of each crank encompasses the contact spring in a gap, so that both resilient contact and forced contact opening are ensured.

Furthermore, according to a further embodiment of the invention, one of the two contacts is attached to a contact spring which is forcibly opened and which is provided with an auxiliary spring. In order to increase the contact spring force and thereby bring about symmetry in the force of the mentioned and the opposite contact spring as well as to achieve corresponding tightening forces in both switching directions, the auxiliary spring is designed so that it is supported on a fixed part immediately before lifting.

• Fig. 1 eine Vorderansicht im Schnitt,
• Fig. und 3 Längsschnitte gemäss den Linien A-A bzw. B-B in Fig. 1,
• Fig.4 bis 6 Querschnitte gemäss den Linien C-C, D-D bzw. E-E in Fig. 1,
• Fig. 7 eine perspektivische Darstellung des zerlegten Relais,
• Fig.8 eine perspektivische Darstellung von wichtigen Einzelteilen des Relais,
• Fig.9 und 10 perspektivische Darstellungen verschiedener Ausführungsbeispiele,
• Fig. 11 ein Schnittbild eines anderen Ausführungsbeispiels,
• Fig. 12 eine vergrösserte Darstellung, an der die Arbeitsweise des Relais erläutert wird,
• Fig. 13 und 14 Ansichten, die den Schaltvorgang erläutern,
• Fig. 15 eine schematische Darstellung eines weiteren Ausführungsbeispiels der Erfindung,
• Fig. 16 ein Ausführungsbeispiel eines Relais mit zwangsweiser Kontaktöffnung, und
• Fig. 17 ein dem Stand der Technik zuzuordnendes Relais.

The invention is described below with reference to the embodiments shown in the drawings. In detail shows

• 1 is a front view in section,
• 3 and 3 longitudinal sections along lines AA and BB in Fig. 1,
• 4 to 6 cross sections along lines CC, DD and EE in Fig. 1,
• 7 is a perspective view of the disassembled relay,
• 8 is a perspective view of important individual parts of the relay,
• 9 and 10 are perspective representations of various exemplary embodiments,
• 11 is a sectional view of another embodiment,
• 12 is an enlarged view on which the operation of the relay is explained,
• 13 and 14 views explaining the switching process,
• 15 shows a schematic illustration of a further exemplary embodiment of the invention,
• Fig. 16 shows an embodiment of a relay with a forced contact opening, and
• 17 shows a relay to be assigned to the prior art.

In the relay shown in the figures, 1 denotes a housing which consists of a base plate 2 made of insulating material or plastic and a housing cap 3. 4 with a bobbin is designated, which has a winding area 5 and two flanges 6. The winding area 5 of the bobbin 4 is provided with a continuous opening 7, in which a yoke 8 is arranged such that ends 8a protrude upward on the opposite flanges 6. The coil winding C, the coil body 4 and the yoke 8 together form the electromagnetic circuit M.

A pair of anchor bars 9 that protrude opposite ends 8a are opposite each other on both sides, have pole faces 9a, 9b, which are adapted to the projecting ends 8a of the yoke for making contact. One pole face is wider than the other. A plate-shaped or cuboid permanent magnet 10 is arranged between the anchor webs 9.

An insulating frame 11 holds the anchor bars 9 and the permanent magnet 10 together. It has on the upper side a wall 12 along which one of the anchor webs extends, a pair of posts 13 through which one anchor web is passed, and a horizontal wall 14 which, together with the post 13, has a cavity for receiving the permanent magnet 10 forms. A projection 14a on the horizontal wall 14 serves to position the permanent magnet, takes up the other armature web and encloses it with the exception of the pole faces 9a, 9b. All walls are integrally connected to the insulating frame 11. One anchor web 9, which penetrates the posts 13, is designed as a thin plate in order to facilitate insertion into the mold and, at the same time, embedding.

The insulating frame 11 also has a resilient arm 15 projecting in the middle, which can bend in the direction T perpendicular to the direction of rotation R of the anchor bars 9 (FIG. 12). 1, 6, 7 and 10, the insulating frame 11, including the flexible arm 15, is formed from a plastic which is highly resistant to arcing. In the exemplary embodiment shown in FIG. 11, the arm 15 is formed from a metallic leaf spring embedded in the insulating frame 11. For this reason, the term "structural unit" is used because, in contrast to the known rotating anchor system with pin bearing, it works as a whole without play. The arm 15 can also be provided on both sides, as shown in FIGS. 10 and 11. Relatively stiff synthetic resin can also be used, as long as sufficient flexibility can be ensured by the thickness or shape of the arm 15. The two anchor bars 9, the permanent magnet 10, the insulating frame 11 and the flexible arm 15 together form the anchor block G.

The base plate 2 is provided with a bearing block 16. In order to increase the flexibility, the arm 15 is tapered in cross section in the area of its connection 15b in the vicinity of the insulating frame 11 and widened at its front end 15a in such a way that an air gap 16a arises in the area of the connection 15b and that its front, widened end 15a against a pair of firmly anchored side walls 17.

With 18 movable contact springs are designated, which are arranged on both sides of the flexible arm 15. Each of these springs lies opposite the upper wall 12 of the insulating frame 11 of the anchor block and is provided with a contact 19 at its front end. Each contact spring 18 is also fastened to an L-shaped base part 20a of a contact connection 20 with an L-shaped foot part 18a. The movable contact spring 18 engages the inner surface 22 of a bend of an operating part 21 for the purpose of a forced contact opening. 23 is a further contact connection which carries a fixed contact 24. The two contacts 19 and 24 form a contact arrangement S.

The base plate 2 has an upright partition 25 which is arranged as an arc protection between this contact arrangement S on the one hand and the part M of the electromagnetic circuit and the armature block G on the other. The partition 25 is integrally formed on the side walls 17 of the bearing block 16. A connecting pin 26 for the coil winding C is L-shaped, its horizontal section 26a being passed through the flange 6 of the coil body 4. The contact connections 20, 23 and the connection pin 26 penetrate the base plate 2.

15 is a schematic illustration of a further preferred embodiment of the invention, which ensures better coordination of spring force and actuating force. The one of two contacts, which is denoted by 27, is closed by bending the contact spring and stands out from the fixed contact 28 serving as an abutment when there is no force from the armature 30. The other contact with the contact spring 29 is forcibly opened and then closed when no force is exerted by the armature. The contact spring 29 of the contact which is forcibly opened carries the movable contact 31 on the side facing the armature 30 and on the other side an auxiliary spring 32 which is supported on it and which is also fastened to the same contact connection 33. The free end of the auxiliary spring 32 is not always supported on the contact spring 29, but only when the contact spring 29 is lifted off the fixed contact 28. The spring force of the contact spring 29 is increased by the force of the auxiliary spring 32 at this time. The resulting spring force from the deflection upon contact, the forced contact opening and the auxiliary spring at the end of the armature movement on the side on which the contact is opened takes on an increased value until the spring force on the side at the contact opening is equal is the value of the spring force on the side where the contact is closed. In this way, the resulting spring force is adjusted to the actuating force of the armature.

The mode of operation of the relay according to the invention is described below. FIG. 13 (FIG. 13A shows the rest position of the relay) shows an arrangement with a work contact and a break contact, in which the armature block G is moved over the flexible arm 15 when the coil is excited, as a result of which the contact arrangements S on both sides can be opened and closed alternately (Figs. 13A, 13B).

In Fig. 14, which shows another arrangement with two working contacts (with Fig. 14A showing the rest position of the relay), the rotation of the armature block G causes a simultaneous opening or Close the two contact arrangements on both sides. The arrangement of Fig. 13 corresponds to the construction shown in Fig. And the arrangement of Fig. 14 corresponds to that shown in Fig. 9.

The relationship between the anchor block G and the elastic arm 15 is that the arm 15 is bent in a direction T perpendicular to the axis of rotation of the anchor block G in response to its rotation, as shown in FIG. 12. If the axis of rotation is displaced from the normal position, a subsequent movement to the right or left or forwards or backwards occurs within the area of the deflection to compensate for the offset, thereby compensating for the problem of chattering or excessive play on the axis of rotation.

Since the electromagnetic relay according to the invention is designed such that the insulating frame 11, which carries the anchor bars 9 and the permanent magnet 10, is formed in one piece with the elastic arm 15, which can bend perpendicularly to the direction of the axis of rotation of the anchor bars 9 and from the bearing block 16 of the base plate 2 is held securely, any offset due to a deflection of the elastic arm 15 is made ineffective by said subsequent movement. This arrangement makes it unnecessary to devote great care to the centering that was required with conventional journal bearings. Since the armature block G is also a unit which comprises the armature webs 9, the permanent magnet 10 and an insulating frame 11, the final assembly compared to the known relays according to the prior art, in which only one part at a time can be installed in the housing , made much more efficient.

In addition to the features described above, the electromagnetic relay according to the invention is further characterized in that the upright partition 25 is provided in its base plate 2 in order to provide protection against arcing between the contacts. Furthermore, the common contact spring 18 is designed such that it comes into engagement with the inner surface of the offset of the actuating part 21. The insulating frame 11, which carries the anchor bars 9 and the permanent magnet 10, is on its top with the wall 12, along which one of the anchor bars is arranged, the pair of posts 13, which an anchor bar passes, and the horizontal wall 14, which together with said posts 13 forms a cavity for receiving and fastening the permanent magnet. Added to this is the wall projection 14a, which extends from the horizontal wall and together with this forms a positioning segment for the permanent magnet, which is adapted to and covers the other armature web 9, the pole faces 9a and 9b of which remain uncovered alone. All the walls mentioned are integrally connected to the frame part. In addition, one of the contact springs is provided with a contact that springs through when contact is made, while the other contact spring carries a contact that is forced to open. The first-mentioned contact spring is provided with an auxiliary spring which is supported on the surface of the contact spring facing away from the moving contact, as a result of which the advantages mentioned are achieved.

16 also shows a rotary armature, in which an armature provided with permanent magnets is mounted on one side on a flexible arm 15 in a bearing block 16. The flexible arm 15 is molded like the actuating pieces 21 a, 21 b, 21 a ', 21 b _' from the insulating material jacket or the insulating frame 11 of the armature. The insulating material sheath also fixes in the armature at least one permanent magnet (not shown) and armature webs 9 which cooperate with the yoke ends 8a of the coil core. The actuating pieces 21a, 21b and 21a ', 21b' shown in section are connected to one another on their upper side, that is to say they grip around the contact springs 18 and 18 '.

In the illustration, the right contact point 19, 24 is closed, the left contact point 19 ', 24' is open. To make contact, the crowned actuating piece 21 b presses against the contact spring 18, while the opposite actuating piece 21 a is lifted off the latter. According to the relatively long spring travel L ₂ , the contact spring 18 experiences considerable deflection. On the other hand, the contact opening at the left contact point 19 ', 24' takes place through the action of the actuating piece 21 a 'on the contact spring 18', the actuating piece 21 b 'being lifted off the contact spring. At the beginning of the opening process, the contact-near section 21c, 21c 'of the actuating piece 21a, 21a' engages with the contact spring 18, 18 ', so that only the short resilient length L ₃ , L _{3 is} effective up to the contact point . The contact point on the contact spring moves with increasing opening of the contact point 19 ', 24', since the surface of the actuating piece 21 a 'facing the contact spring 18' runs parallel to the longitudinal axis of the armature 8, from the contact-less to the non-contact section 21 d 'of the actuating piece 21 a '.

In this exemplary embodiment of the invention, it is thus ensured that the contact is made over long spring travel L ₂ , L ₂ ', but the opening is forced over short and thus rigid sections L ₃ , L ₃ '. In addition to the advantages described in connection with the previously described exemplary embodiments of the invention, an enlargement of the contact opening is achieved in the present case by moving the point of application of the actuating piece 21a 'from the portion 21c' closer to the contact to the portion 21d 'further from the contact.

As a result of the strong deflection when contact is made, the permanent magnetic attraction force can also be stored well in the contact springs 18, 18 '. Due to the slight deflection of the contact springs 18, 18 'on contact opening, on the other hand, in the event of a contact welding, the welded contact is either torn open and the other is operated properly - or, if the welding point cannot be broken, the other contact is also no longer operated.

Claims (6)

1. Electromagnetic relay comprising an armature block (G) including a pair of armature webs (9) and a permanent magnet (10) supported therebetween and oppositely magnetizing the armature webs (9), a substantially U-shaped yoke (8) having projecting ends (8a) respectively disposed in an air gap between the opposite ends of the armature webs (9) in contact with the permanent magnet (10); a coil (C) adapted for connection to a control source for exciting the relay, and a bearing means (15, 16) for the armature block (G) such that one or the other of the two pairs of diametrically opposite ends of the armature block (G)is selectively movable towards the projecting ends (8a) of the yoke (8), the bearing means having a resilient arm (15) which extends away from the armature block (G) perpendicularly with respect to the pivot axis thereof and is fixed at its remote end (15a) facing away from the armature, characterised in that the resilient arm (15) is formed as an integral part of a frame (11) of synthetic material which comprises the armature block (G), and that two compartments for separately housing two switching contacts (19, 24) are formed by a stationary portion at the end (15a) of the resilient arm (15) remote from the armature block (G) and a base plate (2) of synthetic material in which the switching contacts (19, 24) are embedded.

2. Electromagnetic relay according to claim 1, characterised in that one of the armature webs (9) is embedded in a plate (14) of synthetic material, that the plate (14) further includes integrally formed actuating pieces (21) for actuating a pair of contact springs (18) and a cavity adapted for receiving the permanent magnet (10), and that the other armature web (9) is positioned and fixed in the cavity by bearing against the permanent magnet (10).

3. Electromagnetic relay according to claim 2, characterised in that each of the actuating pieces (21) has a pressure surface for actuating the contact spring (18) and a bent part which is so formed that it forcibly opens the respective switching contact (19, 24) by engaging that surface of the contact spring (18) which is on the side opposite to the pressure surface.

4. Electromagnetic relay according to any of claims 1 to 3, characterised in that one of the contacts (28, 31) has a contact spring (29) to be force- ably opened and is provided with an auxiliary spring (32) which is formed such that it bears against a stationary part immediately before the contact opening to increase the spring force of the contact spring (29).

5. Electromagnetic relay according to any of claims 1 to 3, characterised in that the armature block (G) has one actuating piece (21) engaging around each contact spring (18) for actuating the respective contact spring (18), that the actuating pieces (21) have respective pressure surfaces (21 b) at one side of the contact spring (18) facing away from the contact to be closed, for making contact, and respective bent parts (21a) at the other side of the contact spring (18) facing the contact to be opened, for forcible contact opening, and that the pressure surfaces (21b) at the contact springs (18) are further remote from the contact position than the engaging positions of the portions (21 c) of the bent parts (21 a) causing the contact opening.

6. Electromagnetic relay according to claim 5, characterised in that the bent parts (21 a) effecting the contact opening have a portion (21 c) closer to the contact and portion (21 d) more remote from the contact, that the contact opening is initiated by actuation of the respective portion (21 c) closer to the contact, and that in the course of the opening action the engaging position travels along the contact spring (18) from the portion (21 c) of the bent part (21 a) closer to the contact to the portion (21d) more remote from the contact.

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