Abstract:
A safety relay comprising a separating wall, an electromagnetic drive located on a first side of the separating wall comprising a coil with core and yoke, the coil being connectable to a control current, the core being oriented parallel to the separating wall, and a movable armature, a comb located on a second side of the separating wall capable of moving parallel to the separating wall by means of the armature, and a row of several contacts located on the second side of the separating wall actuated by the drive comb, each of the contacts comprising at least two contact elements arranged on an electrically insulating carrier part each of the contacts being connected with a current connection element, at least one of the contact elements being formed by an elongated contact spring arranged between the comb and the separating wall, the contact spring being arranged with a spring longitudinal axis crosswise to the direction of the movement of the comb, forcibly guided by the comb and by a spring foot at one end of the contact spring sitting rigidly in the carrier part, and being provided with a contact head at an end lying opposite the spring foot, the end being movable.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention concerns a safety relay with at least one electromagnetic drive, which comprises a coil with a core/yoke that can be connected to a control current and a movable armature. The relay also comprises a comb that can be moved by means of the armature and several contacts arranged on an electrically insulating carrier part. The drive is arranged on one side of a separating wall; comb and contacts are on the other side of the separating wall. The invention particularly concerns a twin relay of the aforementioned type. The twin relay is a safety relay with two electromagnetic drives. These drives are arranged on one side of a separating wall. Two combs and two rows of contacts are arranged correspondingly on the other side of the separating wall. 
     2. Brief Description of Art 
     A twin relay, which is approximately 15 mm high, 65 mm wide, and 76 mm long, and the structural height of which is formed by two planes, is described in WO 99/54,905. In one of the planes, for example on the side of the connections, two drive systems (opposite-poled sliding armatures) are accommodated. The contact sets are arranged in the other plane. The contact sets each are formed by two contacts individually driven by one of the drives that are independent of one another, and these contacts are connected internally in series. The contacts are formed by one or two contact springs. If a contact is formed by two contact springs, then the active or the passive contact spring extending over the entire width or length of the relay is clamped in the center in a chamber separating wall, and possesses a contact head on both ends. This contact head cooperates with a contact spring, which has a terminal connection on the outside of the relay. If the individual contact is formed of a single contact spring only, then the latter is forcibly-commutated together with the comb and its contact head cooperates directly with the contact head of the contact spring of the other contact of the contact set. This contact spring of the second contact is in turn forcibly-commutated together with a second comb. The two combs each move in opposite directions. The contact springs extend parallel to a separating wall between the two planes. The prior art document is silent with respect to the position and configuration of the drive with armature and comb. 
     Nowadays a relay must meet two partially contradictory requirements. These requirements must be considered in the development of new relays in order to be competitive in the marketplace. The first requirement is that relays must be made smaller. On the other hand it is required of the relays that they be durable and reliable. In a safety relay which meets EN (European Standard) 50205, the air paths and leakage paths between control contact and load contact comply with the requirements of standard IEC 61810-5 and IEC 664-1. The contents of these standards are known to the person skilled in the art and are included by reference. Depending on the voltage, the degree of contamination and the field of application, the known distances between conductive components of the different load contacts must be maintained. In addition, the forced commutation of the contacts further serves for purposes of safety. 
     In accordance with the present invention, a forcibly-commutated relay is a relay in which the contacts are forcibly-commutated with a common movable comb that is connected with the drive and in which at least one working contact and one resting contact are provided. Forcibly commutated here means that each time a contact element abuts a fixed stop, a movable contact spring cooperating with this contact element engages in the comb in such a way that it is forcibly moved together with the movements of the comb. With this constructive measure, it is ascertained that in case a contact is welded, either the welded contact breaks or the comb cannot be moved and thus the other contacts, including the resting contact, also remain in the position given by the welded contact. 
     BRIEF SUMMARY OF THE INVENTION 
     Thus, the object of the invention is to provide a safety relay of compact and simple construction, with which reliable, durable operation is assured. Preferably the relay is miniaturized. In addition the relay shall be easy to assemble and optimally adjustable. 
     The adjustment of the contacts forms an important aspect for assuring safety and durability of a relay. A sufficient adjustment of the contacts is more difficult to obtain the smaller the relay is and the smaller the clearances relative to the force equilibrium of the drive/spring and the 3-dimensional distances are selected. Thus high requirements are to be placed on adjustability in the case of a miniaturized relay. 
     The adjustability of the safety relay or the twin relay of the present invention is achieved in that the contact springs are arranged between the comb and the separating wall separating the drive side from the contact side. 
     The safety relay has at least one electromagnetic drive, which comprises at least one coil with a core/yoke that can be connected to a control current and a movable armature. This drive is arranged on one side of a separating wall which extends parallel to the core. A comb that can be moved parallel to the separating wall by means of the armature and a row of several contacts which are arranged on an electrically insulating carrier part are located on the other side of the separating wall. The contacts are comprised of at least two contact elements and can be actuated by the drive. At least one of the contact elements is connected with a current connection element, for example a pin on the outer side of the relay. Likewise, at least one of the contact elements is formed by an elongated contact spring. The longitudinal axis of this contact spring is arranged transverse to the direction of motion of the comb and extends advantageously parallel to the plane of the separating wall. The contact spring is forcibly-commutated by the comb. The contact spring with its spring foot on one end is accomodated firmly in the carrier part. On its opposite movable end it is provided with a contact head. For an optimal construction of the relay, the contact springs are arranged between the comb and the separating wall. With this construction, the length of the armature can take up the entire height of the relay, and a relatively large comb path is achieved with relatively small structural height. 
     Advantageously, a removable outer wall of the contact chamber on the comb side of the contact spring that lies opposite the separating wall for closure of the relay. This allows one to insert the comb into the carrier part after introducing the contact elements, and holding it in its catching position by means of the outer wall of the chamber. If the contacts can be arranged in a functional manner in the opened relay, it is assured by this arrangement that the contacts can be optimally adjusted. When adjusting the contacts, the contacts are firmly secured in the carrier part, are not in engagement with the comb, and are freely accessible from the open outer wall of the chamber. In order to control the adjustment, the comb can be temporarily inserted with the relay still open. Only after the correct adjustment has been controlled, the comb is definitively inserted and the outer wall of the chamber is put in place, and thus the relay is sealed. 
     Preferably, the individual contacts are separated from one another by chamber walls. Advantageously, the comb is formed by a longitudinal bar extending through cutouts in the chamber walls. This longitudinal bar can be arranged in the vicinity of the contact springs and is engaged with the contact springs by means of suitable formations on the bar. Due to the drive arrangement, the longitudinal bar is advantageously arranged in the center between the outer edges of the relay or relay part. Shields are provided on at least three sides of the longitudinal bar, which are arranged approximately parallel to the chamber walls and extend beyond the sides of the longitudinal bar, in order to elongate the air and leakage paths between contact elements of adjacent contacts in the region of the through-passages of the bar. A labyrinthine extension of the air and leakage paths is achieved by overlapping the chamber walls with the shields. 
     Preferably, the engagement portion of the contact spring on the comb has a distance to the bar axis of the comb, parallel to the longitudinal axis of the spring. As a result of such distance, the longitudinal bar of the comb can be arranged centrally, while the contact spring engages the comb at a selectable distance to the spring foot and the contact head. 
     Preferably, the dimensions of the drive and the contacts are selected to correspond with one another, by providing that the totality of the chambers housing the contacts actuated with a drive leave approximately the same dimensions in two directions as the coil assigned to the contacts. Thus the chambers and the coil having practically the same extensions, the available space is optimally utilized. Resulting from its considerable length the coil may be selected as a relatively high-ohm coil, despite its reduced height. 
     The chamber walls for separating adjacent chambers may be formed on the carrier part or protruding from the outer wall of the chamber. Advantageously, they are formed on both parts. Thus, air and leakage paths are lengthened by an overlapping of the chamber walls. 
     Preferably, at least one portion of the contacts is provided with two independent terminal elements. Contacts having only one terminal element extending to the outside are appropriate for twin relays. These contacts are connected in series with a second contact, which is actuated by a second coil. In the ordinary single relay, all of the contacts have two terminal elements, or three in the case of double-throw contacts, which extend to the outside of the relay. Such contacts are particularly suitable as control contacts, even in twin relays. 
     In a further advantageous embodiment of the invention, the contact springs between their contact head and the spring foot each have a projection with a comb attachment protruding away from the separating wall towards the comb side. The contact spring is forcibly engaged with the comb by the comb attachment. A lateral protrusion on the contact spring allows to insert the comb between the head end and the foot end of the contact spring next to the projection. The contact spring may be notched in the region adjoining the protrusion for guiding the comb therethrough. Thus, the comb may be shaped mirror symmetrically with respect to a plane through the bar axis extending perpendicularly to the separating wall. The projection then engages in one of the two formations provided for engagement. This permits the use of a uniform comb even in the case of a twin relay of the type described below. 
     Advantageously, the contact spring is engaged with the comb at a comb attachment, which is located at a distance from the mechanical longitudinal axis of the spring. The distance to the mechanical longitudinal axis causes a twisting of the contact spring when the contact is connected, which acts favorably on the life-span of the contact head and thus on the durability of the relay. 
     Preferably, the contact head is attached to the spring by its center at a preselected distance beneath the mechanical longitudinal axis of the contact spring. This also causes a twisting of the spring and a favorable effect on the contact head when the contact is connected. The preselected distance is preferably smaller than the distance between the comb attachment and the longitudinal axis of the spring. 
     In the direction of the longitudinal axis of the spring, the distance of the comb attachment from the spring foot is preferably about double its distance from the center of the contact head, in order to achieve good guidance and sufficient length of movement of the contact head. 
     Such a relay with six contacts can be made very small while fulfilling the requirements of the standards indicated initially. The terminal ports are located on the side of the contacts and the drive is arranged above the contacts and extends over practically the entire length of the relay. The relatively large space available for the winding allows an efficient drive with small coil losses. On the side of the armature, on the relay end, terminal ports are provided for the coils. 
     The advantages stated above also apply to a safety relay with two electromagnetic drives, for example a twin relay. Twin relays have a coil with a core that can be connected to a control current and a movable armature for each drive. The coils are preferably aligned the same way, so that the armatures are located on the same side. The drives are arranged on one side of a separating wall which extends parallel to the cores, while each armature extends across the separating wall. Two combs movable parallel to the separating wall, and two rows of several contacts which are arranged on an electrically insulating carrier part, are arranged next to one another on the other side of the separating wall. The contact springs are arranged with their longitudinal axis parallel to the separating wall. The combs are driven independently of one another, each by one of the armatures. At least two of the contacts actuated thereby independently of one another are joined via a common contact element. 
     According to the invention, the contact springs are arranged between the comb and the separating wall. The contacts, which have only one terminal element and are connected with a second such contact by means of a common contact element, are preferably arranged on the end of the comb opposite the armature. In this way, preferably a center region arranged underneath the relay and adjacent to at least one edge of the relay, is free of terminal elements. This permits to arrange contact lines to the terminal elements of the contacts having two terminal elements, the contact lines extending in the direction of motion of the comb underneath the relay. 
     Advantageously, in the case of the contact springs of the contacts which are joined with one another by a common contact element and forcibly commuted by the combs, the spring feet are arranged at ends turned away from one another. Appropriately, the contact heads are arranged between the contact feet of the two contact springs driven independently and connected to a switching unit at ends of the contact springs which are turned toward one another. This arrangement has the advantage that the movable contact springs have the largest possible length and the stationery common contact element can be formed as small as possible. A twin relay of the above-described construction has twice the area of the single relay. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic, perspective view of a relay constructed according to the invention. 
     FIG. 2 is a section through coil and contacts of a relay with six contacts. 
     FIG. 3 is a view of the relay from underneath. 
     FIG. 4 is a detail of the view according to FIG. 3, but having a symmetrical comb. 
     FIG. 5 is a detail of a sectional drawing through the relay according to FIG.  4 . 
     FIG. 6 is a view from underneath of a twin relay according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As used herein, “contact elements” refers to the contact spring, the fixed contact element in the single or twin relay, and the common contact element in the twin relay of the present invention. 
     In FIG. 1 only those elements which are necessary for the understanding of the relay according to the invention are depicted. Relay  11  has a drive  15  in a drive region  13  shown bounded by the dotted line. The drive  15  is located on a first side of an essentially planar separating wall  17 . Drive  15 , as usual, has a coil connected to a control current by means of two control terminal connection pins  19  and can move a comb  23  by an armature  21 . Working contacts and control contacts are arranged on the second side of the separating wall  17 . In FIG. 1 a single pair  25  of contact elements with a contact spring  27  engaged in comb  23  and an immovably arranged second contact element  29  represents a multiple number of contacts. Both contact elements  27 ,  29  each have a current connection element, for example a terminal pin  31 . 
     The core and yoke of the coil of drive  15  is arranged parallel to separating wall  17 . The armature  21  is arranged on a short side of relay  11  and extends upwardly to the other side of separating wall  17  and is engaging comb  23 . Contact elements  27 ,  29  are arranged directly adjacent to separating wall  17  and attached to a carrier part  33  forming the separating wall  17 . Comb  23  is arranged on the side of the contact elements  27 ,  29 , facing away from the drive. Thus with the relay  11  turned upside down and having the terminal pins extend into the air the comb is located on top. When the relay is assembled this arrangement allows the insertion of the contacts  25  into the carrier part  33  already provided with the drive and their adjustment and inspection prior to engaging the comb  23  with the contact springs  27 . In the comb  23  slot  35  is provided, in which a projection protruding from contact spring  27  in the direction of comb  23  engages. In FIG. 1, for illustration purposes six slots  35  are depicted, so that the contact springs  27  can be moved with the comb  23 . 
     In FIG. 2, there is illustrated a coil  37  with a core  39  and a yoke  41 , an armature  21 , a carrier part  33  with a separating wall  17 , as well as contact springs  27  and stationery contact elements  29 . Further, comb  23  is shown engaged with the armature  21  and the contact springs  27 . All of this is enclosed in a housing which is comprised of a cover  43  and a bottom part  45 . These are hooked inside one another. Carrier part  33  forms an uptake for receiving drive  15  on one side of the separating wall  17 . Chambers  49  for the contacts  25  which are separated from one another by chamber walls  47  are formed on the other side of separating wall  17 . The chamber walls  47  and a peripheral wall  51  surrounding all of chambers  49  define all dimensions of the chambers. The bottom part  45  abuts with its inner side the front sides of the chamber walls  47  and the peripheral wall  51 . The bottom part  45 , however, is provided in turn with chamber ribs  53 , which come to lie directly next to chamber walls  47  when relay  11  is sealed. A bottom edge rib  55  comprises the peripheral wall  51  and is engaged in cover  43  by nose pieces  57 . Cover  43  in turn encloses all five sides of relay  11 , which are not covered by bottom part  45 , as well as bottom edge rib  55 . 
     The chamber ribs  53  and the chamber walls  47  together form a labyrinthine extension of air and leakage paths between the contact elements  27 ,  29  in adjacent chambers  49 . In places where the comb  23  extends through the chamber walls  47  and the chamber ribs  53 , only a shortened air and leakage path would be formed, if this path were not extended by a shield  59  at the comb. Shield  59  protrudes over a longitudinal bar  60  of the comb  23  along three sides. The bar extends through the openings in the chamber walls and the chamber ribs. On the fourth side, i.e., the side facing toward the bottom part  45 , for space reasons it is not desired that the shield  59  extend beyond the longitudinal bar  60 . Thus, the shield  59  is formed in an L-shape where necessary and covers the contact spring  27  together with a shield part  61  arranged to extend parallel to the bottom part  45 , so that a path elongation is achieved there also. 
     Positive catches  65  are formed on the shield parts  61  or like tabs  63  formed on the comb  23 . The positive catches  65  engage catch projections  67  (see FIG. 5) formed at the contact spring  27  from two sides, so that the contact spring  27  must follow each movement of the comb  23 . The shield parts  61  are arranged symmetrically with respect to the longitudinal bar  60  of comb  23  in order to uniformly extend the air and leakage paths on both sides of the longitudinal bar. The symmetrical arrangement permits the use of a uniform comb for both relays of a twin relay as illustrated in FIG.  6 . 
     Returning to FIG. 2, armature  21  extends through an opening in the separating wall  17  up to the direct vicinity of bottom part  45 . Its free end rests in a recess in comb  23 . Coil  37  is wound on a coil carrier  69 , which is penetrated by core  39 . The yoke  41  and the core  39  are manufactured together from one piece. Terminal pins onto which is connected the coil winding wire are provided on the coil carrier  69 . The terminal pins project from the housing through openings in the bottom part  45 . 
     As depicted in FIG. 3, contact elements  27 ,  29  are seated at clamping regions  71  provided in carrier part  33 . The contact springs  27  are folded once at the spring foot  73  and bent by 90° in the doubled region. They are inserted into the pocket-like clamping region  71  in carrier part  33  with this angular part  75  from the comb side, that is from the open bottom. Likewise, the rigid contact element  49  is inserted into a receptacle in the shape of a pocket  79 . The terminal pins project counter to the direction of insertion of the contact elements  27 ,  29 , towards the bottom part  45  which can be placed on carrier part  33 . In the bottom part, corresponding holes for the pin are provided. 
     An advantageous configuration of the contact springs  27 , the fixed contact elements  29  and the comb  23  is illustrated in FIGS. 4 and 5. The comb  23  is shaped symmetrically, so that the same comb  23  can be used both in the relay constructed as shown as well as in a relay designed in a symmetrical configuration. Contact spring  27  is also formed symmetrical relative to contact head  77 . The preformed head part of a contact head rivet is arranged on one side of contact spring  27  and the hammered head part is arranged on the other side of contact spring  27 . The body of the contact spring  27  is made of a sheet metal that is preferably cut into an E-shape. The E-shape is formed by the spring part  80  (along axis  81 ) and the three projections extending transversely to the longitudinal axis of the spring part  80 , namely the contact head  83  (which is widened relative to spring part  80 ), the catch projection  67 , and the spring foot  73 . The distance between the spring part  80  and the separating wall  17  is specified by the spring foot  73 . The projection  67  is arranged in close vicinity to the head. Longitudinal bar  60  of the comb  23  extends between the spring foot  73  and the projection  67 . The comb  23  is engaged with the positive catches  65  by projection  67 . When the contact is opened, a twisting of the spring part  80  is effected by the actuation of the contact spring  27  via the catch projection  67  which is arranged asymmetrically with respect to the longitudinal axis  81 . The twisting of the spring part is a result of the center of contact head  77  and the attachment point of the positive catch  65  at projection  67  having different distances to the mechanical longitudinal axis  81 . 
     The fixed contact element  29  is formed by an almost square-shaped sheet-metal part  85  having a rivet head  87 . Simultaneously, the sheet-metal part  85  forms a terminal pin  31  or, in a twin relay as illustrated in FIG. 6, a common contact element  86  to the rivet head  87  in the second relay. The fixed contact element  29  or a common contact element  86  forming a bridge to the rivet head  87  is inserted into a pocket  79 ,  79 ′ encompassing the edges of sheet-metal part  85 ,  85 ′. 
     The twin relay  89  illustrated in FIG. 6 is equipped with two combs  23  of mirror-image design and two different types of contact springs  27 . The spring parts  80  with spring foot  73 , catch projection  67  (compare FIG. 5) and head part  83  are in fact identical, but the contact head  77  is arranged in one of the springs on the side on which the spring foot  73  is bent outwardly, and in the second spring it is located on the opposite side. Due to the correspondingly shaped clamping regions  71  in the carrier part  33 , the same contact spring  23 , but with head rivets arranged differently or shaped symmetrically, can be inserted in both relays, functioning as both working contacts as well as resting contacts. 
     The problem of air and leakage paths between the contact elements  27 ,  29  of adjacent contacts is resolved in the same manner within each individual relay of the twin relay, as in the case of a single relay. A leakage path between the contact springs  27  or the fixed contact elements  29  of the load contacts  91  of at least 8 mm inside the relay results from the path extensions by means of overlapping chamber walls  47  and chamber ribs  53  and by shields  59 . The distance of the pins and the air path on the inside under load contacts  91  amount to at least 6.5 mm and fulfill the requirements of the standards. Between the load contacts  91  and the control contacts  93 , the air path is extended to 8 mm. This ascertains a reliable separation between the different voltage potentials of the load contacts  91  and the control contacts  93  operated with safety low voltage. 
     In addition, in the case of a twin relay  89 , both relays must be arranged at a distance from one another, which fulfills the requirements of the standards. For this purpose, between the two relays a labyrinthine gearing of cover  43  and carrier part  33  is provided, on the one hand, and of bottom part  45  and carrier part  33 , on the other hand, the labyrinth gearing being attached to a carrier part  33  designed for two drives  15  (compare FIG. 2) and two rows of contacts  25 . The walls provided in the carrier part  33  for this gearing are penetrated only by the common contact elements, so called bridges  86  common to two contacts  25  forming bridges, and the chamber ribs  53  adjacent to these. 
     For a relay  11 , whether an individual relay or a twin relay, a carrier part  33  preferably cast of plastic, encloses a drive on one side of a separating wall and forms chambers  49  for contacts  25  on the other side of the separating wall. The chambers  49  are open on the side lying opposite the separating wall and are closed by a bottom part  45 . A comb  23  which is movable parallel to the separation wall by an armature is arranged between the bottom part  45  and the contacts  25 . Movable contact springs  27  of the contacts  25  cross the comb  23  and are forcibly commutated by means of the comb. The contact springs  27  are all designed uniformly, and will be moved by comb  23  equally on either side. The combs  23  are also designed uniformly, and the movable heads of contact springs  27  are arranged equally on either side of comb  23 . The components of the relay are particularly advantageous for the production of a twin relay. Due to the arrangement of the comb  23  near the bottom, the contact springs  27  can be aligned before the comb  23  is inserted. Thus, relay  11  may be produced with contact springs of very small dimensions and can be adjusted in a reliable operating manner. Sufficiently long leakage and air paths are achieved between the contact elements  27 ,  29  in adjacent chambers  49  even though only small spaces are available. This advantage is a result of the constructive engagement of the bottom part  45  with chamber ribs  53  and carrier part  33  with the chamber walls  47 . The distances of the terminal pins from one another and the number of contacts  25  are decisive factors for the overallexternal dimensions of relay  11 . The length of the contact springs  27  with respect to the minimal distances between the contact heads of an open contact  25  is a limiting factor, since the material nature of the contact spring  27  can be varied only within certain limits. Due to the extension of the coil  37  (compare FIG. 2) over the entire length of all chambers  49 , it can be operated with the lowest possible power losses. 
     While the invention has been described above with reference to specific embodiments thereof, it is apparent that many changes, modifications, and variations can be made without departing from the inventive concept disclosed herein. Accordingly, it is intended to embrace all such changes, modifications and variations that fall within the spirit and broad scope of the appended claims. All patent applications, patents and other publications cited herein are incorporated by reference in their entirety.