Abstract:
A coil housing for a relay and a method of making the same, the coil housing comprises a first housing member and a second housing member. The first housing member includes a first flange with a first tubular half extending therefrom. The second housing includes a second flange with a second tubular half extending therefrom. The second tubular half engages with the first tubular half to form a coil receiving tube connecting the first and second housing members. Connectors formed of a punched sheet metal are molded in at least one of the first and second housing members.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to a relay and, more particularly, to a coil housing for a relay comprising first and second housing members with connectors injection-molded therein and a method for embedding the connectors in the first and second housing members.  
       BACKGROUND OF THE INVENTION  
       [0002]     Relays, such as miniaturized relays that weigh only a few grams, are used in automotive applications and are suitable for high switching currents of up to approximately 30 A. Although there are many types of relays, a distinction is often drawn between soldered relays and plug-in relays. The soldered relays can either have connectors in the form of soldering lugs located substantially parallel to a lower side of the housing or connection pins extending substantially perpendicularly from a lower side of the relay. The soldering lugs are suitable for use in surface mount technology (SMT), and the connection pins are suitable for use in conventional through-mount technology where the connection pins are inserted into apertures in a printed circuit board and soldered on an opposing side thereof. Plug-in relays, on the other hand, have flat, optionally relatively wide, connectors, which are commonly known as FASTON connectors. These connectors extend substantially perpendicular from a base side of the relay and can be rapidly inserted into sockets with little installation effort.  
         [0003]     Additionally, a distinction is drawn between relays that have the connectors injection molded therein and relays that have the connectors installed by plug installation. In the plug installation process, the connectors are fitted into a coil housing after is has been injection-molded. Because the connectors are often oversized, the connectors tightly fit into the coil housing when inserted therein. During insertion, particles may therefore abrade as a result of the parts overlapping, which may lead to contact errors during operation of the relay. In the injection installation process, the connectors, which may be formed from punched sheet metal, are embedded in the coil housing. The connectors are either individually inserted into an open injection mold, which is laborious, or are inserted into an injection mold connected in a strip, which requires high sheet metal consumption. The connectors are conventionally inserted into the injection mold parallel to a parting plane thereof. The desired arrangement of the connectors in the coil housing is therefore complex because it involves a plurality of parting planes and/or alternating parting planes in order to provide “rear” mold planes.  
         [0004]     To alleviate these problems, DE 197 47 166 C1 proposes a modified, efficient injection-molding process. In this process, connection pins are embedded in a coil housing. The connection pins are arranged in two or more parallel offset planes in a region of flanges of the coil housing. This process requires only one parting plane, which extends transversely through flanges and a coil receiving tube of the relay. When the mold is closed, the connection pins are fed in the form of drawn wires through channels extending perpendicularly to the parting plane in the mold half into the mold. The connecting pins are then embedded in position in a region of the flanges, so that only one parting plane is required as a result of the feed process.  
         [0005]     This injection-molding process, however, may not be used with relatively wide connectors, such as FASTON connectors. These wide connectors are usually too rigid to be drawn as a wire from a supply roll. Additionally, these connectors can not be connected in a strip or easily introduced as individual parts into the closed mold through a mold half in the feed process. A wire-feed process is also problematic, because unlike the connection pins, these connectors require a chamfer in two planes at a plug-in side for facilitating insertion into a socket, which would have to be laboriously applied to the finished part after injection molding. Further, if profiled wire is used for the connectors, contacts will have to be welded to the connectors after injection-molding. Heating of the plastic material in a region of the embedding of the connectors cannot be avoided during this procedure. As a result, glass fibers may become detached from the plastic material, which may lead to contact disturbances.  
       SUMMARY OF THE INVENTION  
       [0006]     It is therefore an object of the invention to provide a relay comprising connectors, such as FASTON connectors, and a simple, cost-effective injection-molding process for embedding the connectors in the relay.  
         [0007]     This and other objects are achieved by a coil housing for a relay comprising a first housing member and a second housing member. The first housing member includes a first flange with a first tubular half extending therefrom. The second housing includes a second flange with a second tubular half extending therefrom. The second tubular half engages with the first tubular half to form a coil receiving tube connecting the first and second housing members. Connectors formed of a punched sheet metal are molded in at least one of the first and second housing members.  
         [0008]     This and other objects are further achieved by a method of making a coil housing for a relay. The method comprises the steps of providing at least two leadframes with punched connectors. The leadframes are arranged so that the connectors of one of the lead frames are positioned in-between the connectors of the other lead frame. First housing members and second housing members are then injection-molded with the leadframes so that the connectors are partially embedded therein. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a perspective view of a relay according to the invention;  
         [0010]      FIG. 2  is a schematic illustration of an installation sequence in the production of the relay shown in  FIG. 1 ;  
         [0011]      FIG. 3  is an exploded view of a coil housing;  
         [0012]      FIG. 4  is a lateral view of the coil housing shown in  FIG. 3 ;  
         [0013]      FIG. 4A  a lateral view of another embodiment of the coil housing;  
         [0014]      FIG. 5  is a perspective view of another embodiment of the relay;  
         [0015]      FIG. 6  is a perspective view of still another embodiment of the relay;  
         [0016]      FIG. 7  is a lateral view of an arrangement of first and second housing members and connectors during injection-molding; and  
         [0017]      FIG. 8  is a perspective oblique view of the arrangement shown in  FIG. 7 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]      FIG. 1  shows by way of example a relay (some housing elements have been omitted). The relay has as a support member a coil housing comprising a first housing member  1  joined with a second housing member  2 . The first housing member  1  has a first flange  17 , and the second housing member  2  has a second flange  18 . As shown in  FIG. 3 , a first tube half  21  extends from the first flange  17 , and a second tube half  22  extends from the second flange  18 . The first and second tube halves  21 ,  22  are permanently joined to form a coil receiving tube  3 , as shown in  FIG. 2 . In order to join the first and second tube halves  21 ,  22 , a free end of the first tube half  21  may be formed with a projection that is at least partially received in the second tube half  22 , as shown in  FIG. 4 . Alternatively, an outside surface or an inside surface of either the first tube half  21  or the second tube half  22  may be geometrically configured to positionally secure and/or prevent twisting of the first and second housing members  1 ,  2 , as shown in  FIG. 4A . The first and second tube halves  21 ,  22  do not have to be symmetrically formed. A winding  8  is attached to the coil receiving tube  3 , as shown in  FIG. 2 .  
         [0019]     As shown in  FIG. 3 , the first and second housing members  1 ,  2  each have extensions  19 ,  20 , respectively. The configuration of the extensions  19 ,  20  is not limited to the embodiment shown herein. Connectors,  13 ,  14 ,  15 ,  16  such as FASTON connectors, are injection-molded, into a lower region of the first and second flanges  17 ,  18 . The connectors  13 ,  14   15 ,  16  extend substantially parallel to the first and second flanges  17 ,  18 . The connectors  13 ,  14   15 ,  16  may be, for example, embedded into the extensions  19 ,  20 . The connectors  13 ,  14 ,  15 ,  16  may be made, for example, from punched sheet metal. In the illustrated embodiment, the connector  13  is provided with a fixed contact  7 , and the connector  15  is provided with a lug  23 . Chamfers  24 , which may be formed in two planes to facilitate insertion of the connectors  13 ,  14 ,  15 ,  16  into corresponding sockets (not shown), may be formed at plug-in-side ends of the connectors  13 ,  14 ,  15 ,  16 .  
         [0020]      FIG. 5  shows a slightly modified embodiment of the relay. In  FIG. 5 , connectors  27 ,  28  are load connectors and are configured with wider connectors than the connectors  15 ,  16 , which are coil connectors. The typical FASTON widths of the connectors  15 ,  16 ,  27 ,  28  are 2.8 millimeters, 4.8 millimeters, and 6.3 millimeters, however these widths may be varied. The connectors  27 ,  28  may be embedded or inserted into the coil housing.  FIG. 6  shows an additional modification of the relay. In  FIG. 6 , connectors  29 ,  30 ,  31  are constructed as connection pins that are suitable for soldering to a printed circuit board (not shown). The connectors,  29 ,  30 ,  31  may be embedded or inserted into the first and second housing members  1 ,  2 .  
         [0021]     As shown in  FIG. 2 , the coil housing holds a magnet system and a contact system. The first housing member  1  includes a core receiving through-hole  25  corresponding with the first tube half  21 , which receives a core  4 , as shown in  FIGS. 2 and 3 . A yoke  9 , which is typically L-shaped, is fixed to the core  4 . A spring module comprising an armature  10 , a spring contact  11 , and a movable contact  12 , is joined and electrically connected to the yoke  9 .  
         [0022]     The assembly of the relay will now be described in greater detail. As shown in  FIGS. 7 and 8 , partially punched connectors  13 ,  14 ,  15 ,  16  are arranged on a strip or leadframe  5 ,  6 , respectively, in pairs. The connectors  13 ,  14 ,  15 ,  16  of the first and second housing members  1 ,  2  are arranged next to each other in parallel on the strip so that the connectors  13 ,  14 ,  15 ,  16  opposing each other engage with one another in a finger-like manner. Each of the leadframes  5 ,  6  is then injection-molded with either the first housing member  1  or the second housing member  2  so that the connectors  13 ,  14 ,  15 ,  16  are partially embedded therein. The leadframes  5 ,  6  may be bent for this purpose, if necessary, and may be provided with the fixed contact  7 . Alternatively, the connectors  13 ,  14 ,  15 ,  16  may be provided as individual inserts that are injection-molded with the first and second housing members  1 ,  2 .  FIG. 3  shows the first and second housing members  1 ,  2 , illustrated with the leadframes  5 ,  6 , respectively.  
         [0023]     In the illustrated configuration, the first and second housing members  1 ,  2  are injection-molded in a common die, so the illustrated arrangement comprising parallel opposing first and second housing members  1 ,  2  or connectors  13 ,  14 ,  15 ,  16  reflects the installation sequence shown schematically in  FIG. 2  up to the moment of joining of the first and second housing members  1 ,  2 . Alternatively, the first and second housing members  1 ,  2  may be injection-molded in separate dies.  
         [0024]     As shown in the installation sequence in  FIG. 2 , after removal of the leadframes  5 ,  6 , the core  4  is inserted into the core receiving aperture  25  in the first housing member  1 . The core  4  helps to fix and join the first housing member  1  to the second housing member  2 . The first tube half  21  and the second tube half  22  are then joined to form the coil receiving tube  3  and connect the first housing member  1  to the second housing member  2 . Alternatively, the core  4  may be inserted into the core receiving aperture  25  after the first and second housing members  1 ,  2  have been joined.  
         [0025]     The winding  8  is then wound onto the coil receiving tube  3 . The lug  23  facilitates the winding-on of the winding  8 . The yoke  9 , which is typically L-shaped, is then inserted or welded onto the core  4 . A spring module that comprises the armature  10 , the spring contact  11 , and the movable contact  12 , is then electrically connected to the yoke  9  and fastened thereto by, for example, riveting or laser welding.  
         [0026]     The relay according to the invention is produced in two halves that each have a parting plane. Each half includes, for example, two of the connectors  13 ,  14 ,  15 ,  16 , which may be load connectors or coil connectors. However, it is also possible, for example, to produce an additional fixed contact for the load connectors substantially in the plane of the first flange  17  or even to produce a slightly offset contact plane, for example using an alternating parting plane for the first housing member  1 . With a slightly higher outlay in the unravelling inside the relay, the allocation of the connectors  13 ,  14 ,  15 ,  16  may also be altered. It is also possible, for example, to embed only some of the connectors  13 ,  14 ,  15 ,  16 , which may easily be injected in almost any configuration as a result of having only one parting plane, and to insert the remaining connectors  13 ,  14 ,  15 ,  16  during the installation process. In this embodiment, it is advantageous if the embedded connectors are provided as coil connectors and the connectors inserted in the installation process are provided as load connectors of the relay.  
         [0027]     An advantage of the relay according to the invention is that during production, an additional transverse slide in the injection mold is not required for a core receiving through-hole  25  located in the parting direction of the two-part injection mold. Additionally, because the first and second housing members  1 ,  2  may be injection-molded using separate injection-molding dies or a common die, material consumption of the punched metal sheet is reduced. For example, in the arrangement shown in  FIGS. 7 and 8 , the connectors  13 ,  14 ,  15 ,  16  are placed in common strips in the injection mold for optimal utilization of the punched sheet metal material. As a result of the mutual engagement of the connectors  13 ,  14 ,  15 ,  16 , part of the material, which is otherwise consumed as waste in the gaps, is utilized for the respectively opposing connector. The plane formed by the common strips and the first and second flanges  17 ,  18  corresponds approximately to the parting plane of the common injection-molding die so that the amount of punched material wasted to be kept low, thereby substantially assisting cost-effective production.  
         [0028]     The invention is accordingly based on the idea of addressing the injection-molding process problems caused by the shape of the coil housing and the connectors arranged therein, not by the provision of elaborate, varying or complex individual parting planes in the injection mold, but rather by the division (“intersection” approximately in the center between the parting planes, which otherwise extend in the first and second flange planes) of the actual coil housing to be injected into two separate halves. The individual first and second housing members  1 ,  2 , which are initially unconnected, may thus in each case easily be produced in injection molds having only one parting plane and then be joined in the region of a core receiving through-hole  25  to form a complete coil housing.  
         [0029]     In an advantageous embodiment, the injected connectors  13 ,  14 ,  15 ,  16  are constructed as FASTON connectors, which are made of a punched flat material and are suitable for plug installation. The connectors  27 ,  28  may also exhibit a varying material thickness, in particular a varying width. The use of the punched flat material also allows the fastening of contact rivets or weld contacts prior to injection molding or insertion, thus eliminating the risk of glass fibers becoming detached from the plastic material.