Patent Publication Number: US-4482876-A

Title: Electromagnetic relay

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electromagnetic relay, and is more particularly concerned with a relay having spring contacts which comprise an extension in the area of their mounting, the extensions of the contact springs forming terminal lugs which are secured in a base and serve as a resilient mounting of the armature carrier. 
     2. Description of the Prior Art 
     The German patent application No. P 31 32 239.5, corresponding to U.S. Ser. No. 407,236, fully incorporated herein by this reference, relates to an electromagnetic relay having an excitation coil and an elongate armature seated at one side which extends essentially parallel to the axis of the coil and to which at least one contact spring is secured in an insulated manner. The contact spring extends parallel to the armature and has a free end which cooperates with at least one cooperating contact element. A bar-shaped armature is seated at its one end in the area of a first coil flange over an insulating carrier and extends essentially over the entire coil length up to the second coil flange at the opposite end, whereby it forms a working air gap with at least one pole plate in the area of the second coil flange and whereby the contact springs anchored in the armature also essentially extend over the entire length of the coil and spaced from the armature. 
     The above-mentioned relay has the advantage that the direct fastening of the contact springs in the insulating carrier of the armature directly transmits the armature movement to the contact springs so that no actuation slide is required. However, given the exemplary embodiment described in that application, it is necessary to connect the contact springs, connected to the armature, and movable therewith, to their respective connection elements in a base body by way of stranded conductors. Such stranded conductor connections are relatively expensive and involved to manufacture. Moreover, the insulating carrier of the armature must be seated at the coil body by way of suitable measures, this producing unavoidable friction. When, moreover, the armature is to exhibit a bias or, respectively, restoring force, then such force must be exerted by an additional spring. 
     SUMMARY OF THE INVENTION 
     The object of the present invention, therefore, is to provide a further development of the relay mentioned above in such a manner that the stranded conductor connections for the movable contact spring can be eliminated and the bearing friction of the armature is avoided at the same time. 
     Given a relay of the type set forth above, and according to the present invention, the above object is achieved in that the contact springs respectively exhibit an extension in the area of their anchoring in the carrier, the extension forming a terminal lug and being secured in a base body carrying the cooperting contact elements and serving as a resilient seating of the armature carrier. 
     As a result of the design of a relay in accordance with the present invention, therefore, the contact springs which are movable with the armature comprise, together with their terminal lugs, a one-piece construction which also simultanously assumes the seating of the armature. Therefore, a stranded conductor connector for the electrical connection of the contact springs is superfluous and the bearing friction of the armature is avoided at the same time. In addition, a desired restoring force for the armature can be generated by way of the spring seating without an additional reset element being necessary for this purpose. 
     A respective extension of the contact spring or, respectively, contact springs, advantageously emerges from the carrier in the respective area of the armature&#39;s axis of rotaton and, over one or more crimps, and forms a fastening part having an integrated terminal lug. 
     In accordance with a preferred embodiment of the invention, one contact spring is secured in the carrier at both sides of the armature, whereby the extension of the two contact springs emerge from the carrier offset relative to one another in the direction of the armature&#39;s axis of rotation. Thereby, the extension of the respective contact spring can exhibit a spring section reduced in cross section and stressed during the switch operation of the armature for flexure or torsion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Other objects, features and advantages of the invention, its organization, construction and operation will be best understood from the following detailed description of a preferred embodiment of the invention, taken in conjunction with the accompanying drawing, on which there is a single FIGURE which is a perspective pictorial view of a relay constructed in accordance with the invention. 
     An armature 71 is illustrated on the drawing and comprises an elongate ferromagnetic plate which is movably disposed in a coil body (not illustrated) which has a winding 72 which is only schematically illustrated. The armature 71 has a free end 71a which is movably disposed between two pole plates 73 and 74 and which forms respective working air gaps 75 and 76 relative to the pole plates 73 and 74. Only the ends of the pole plate 73 and 74 are illustrated. As with the entire magnetic system, the pole plates 73 and 74 can be designed, for example, in accordance with that relay of the aforementioned German patent application. The armature 71 is secured at its opposite end 71b in a carrier 77 of insulating material, being secured, for example, by embedding or by insertion therein. 
     Also secured in the carrier 77 are two contact springs 78 and 79 whose two spring legs respectively extend at both sides of the armature 71 parallel thereto and whose free ends 78a and 79a are disposed between respective pairs of contact elements 80, 81 and 82, 83, respectively, such that they selectively produce contact therewith. The cooperating contact elements 80, 81 and 82, 83 are secured in a schematically-illustrated base 84 in a conventional manner, for example, by way of embedding or insertion therein and form respective terminal lugs, for example the terminal lugs 80a, 81a, at the terminal side of the base 84. 
     Proceeding respectively from their anchoring in the carrier 77, the contact springs 78 and 79 form an extension 78b, 79b, respectively, which extends to a fastening section 78c, 79c extending parallel to the contact springs 78, 79 and which forms a respective terminal lug, for example 78d, below its anchoring in the base 84. The corresponding terminal lug of the contact spring 79 cannot be seen on the drawing. At the exit location from the carrier 77, the contact springs 78 and 79 respectively form a spring bar 78e, 79e which lies in the area of the axis of rotation of the armature and, as a result of its spring effect, exerts a restoring force on the armature together with the overall fastening elements 78b, 79b. 
     From its spring leg over its embedding in the carrier 77 and over the multiply-bent and crimped fastening part 78b up to the terminal lug 78d, therefore, the contact spring 78 is a one-piece element so that both the electrical current supply, as well as the seating of the carrier 77 with the armature 77 can be undertaken without additional elements. The bars 78e, 79e thereby serve as pivot bearings. Therefore, any and all bearing friction for the armature 71 is also eliminated. Of course, the contact springs 78, 79 with their connection parts can be modified so that, for example, respective torsion bars can be disposed in the rotational axis of the armature instead of the bars 78e, 79e which are loaded for flexure. The armature can be biased in a center position or in a lateral final position by way of an appropriate design and adjustment of the contact springs or, respectively, their fastening parts. 
     Moreover, the base can be designed for the receipt of the coil body (not illustrated) and further elements. For example, it can also be designed in a suitable manner for receiving a cover cap. 
     Although we have described our invention by reference to a particular illustrative embodiment thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. We therefore intend to include within the patent warranted hereon all such changes and modifications as may reasonably and properly be included within the scope of our contribution to the art.