Abstract:
A solenoid including a substantially cylindrical hollow bobbin made of an insulating material is provided, which is mountable on a housing body and is provided with at least two relay connectors anchored in an end area of the bobbin and projecting axially therefrom, and the solenoid is also coupled to a contact element. The solenoid and the contact element are two separate components which are connectable to each other by a connecting part of the contact element attachable to the housing body, by a suitable securing method, e.g., by soldering or welding.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a division of U.S. patent application Ser. No. 10/049,805, which was the National Stage of PCT International Application No. PCT/DE01/02147, filed on Jun. 8, 2001, each of which is expressly incorporated herein in its entirety by reference thereto. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a two-part solenoid and a method for the manufacture thereof.  
       BACKGROUND OF THE INVENTION  
       [0003]     A solenoid described in German Patent 295 14 315 U1 includes a largely cylindrical hollow bobbin made of an insulating material that is provided with two relay connectors anchored in an end area of the bobbin and projecting axially therefrom, with which it is possible to wind the bobbin mechanically. The bottom of the bobbin forming the bottom of the winding space has variable adjacent winding levels in the axial direction which are offset against one another in the radial direction, with the transitions between the winding levels being designed as a bevel having an inclination of approximately 30 degrees. Except in the transition areas, the bottom of the bobbin is provided with grooves for the winding wire.  
         [0004]     The disadvantage of the solenoid described in the above-mentioned German Patent 295 14 315 U1 lies, in particular, in the overall length of the solenoid, which is determined by the length of the relay connector. This makes the solenoid susceptible to damage, for example, when mechanically winding the coil wire. The relay connectors have a tendency to bend.  
         [0005]     Another disadvantage is that different flat connectors for the electrical lines may require different manufacturing methods, which complicates the production process and makes it expensive.  
       SUMMARY OF THE INVENTION  
       [0006]     The solenoid according to the present invention has the advantage over the related art that the short relay connectors enable the solenoid to be easily handled in subsequent processing steps, and, in addition, a contact element of any shape, for example a flat connector, may be attached to the solenoid by a simple snap-on connection and subsequently connected to the relay connectors.  
         [0007]     An advantage of this invention is the easy manufacture of the relay connectors and contact elements, which may be manufactured, for example, by punching them out of a metal sheet.  
         [0008]     The connecting part between the solenoid and the contact element is advantageously made of a flexible plastic which enables the contact element to be mounted on the bobbin or the valve housing.  
         [0009]     The contact tabs of the contact element are still connected during manufacturing, which makes it easier to correctly position the contact tabs relative to each other. After being extrusion-coated with plastic, the contact tabs are separated by punching.  
         [0010]     The angled extensions of the contact tabs give the contact element a shape that allows it to be easily connected to the relay connectors. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1A  shows a schematic top view of a relay connector of a solenoid according to the present invention.  
         [0012]      FIG. 1B  shows a schematic side view of a relay connector of a solenoid according to the present invention.  
         [0013]      FIG. 1C  shows a sectional view of a cross-section taken along the line marked IC-IC in  FIG. 1A .  
         [0014]      FIG. 2A  shows a schematic view of the bobbin of a solenoid according to the present invention.  
         [0015]      FIG. 2B  shows a longitudinal section of the bobbin of a solenoid according to the present invention.  
         [0016]      FIG. 2C  shows an enlarged view of area IIC shown in  FIG. 2B .  
         [0017]      FIG. 3A  shows a cross-section of a solenoid according to the present invention.  
         [0018]      FIG. 3B  shows a schematic side view of the solenoid shown in  FIG. 3A .  
         [0019]      FIG. 4A  shows a schematic view of the contact element of the solenoid according to the present invention in first of three consecutive stages of processing.  
         [0020]      FIG. 4B  shows a schematic view of the contact element of the solenoid according to the present invention in second of three consecutive stages of processing.  
         [0021]      FIG. 4C  shows a schematic view of the contact element of the solenoid according to the present invention in third of three consecutive stages of processing.  
         [0022]      FIG. 5A  shows a schematic representation of the first method step according to the present invention for connecting the solenoid to the contact element.  
         [0023]      FIG. 5B  shows a schematic representation of the second method step according to the present invention for connecting the solenoid to the contact element.  
         [0024]      FIG. 5C  shows a schematic representation of the third method step according to the present invention for connecting the solenoid to the contact element.  
         [0025]      FIG. 5D  shows a schematic representation of the fourth method step according to the present invention for connecting the solenoid to the contact element.  
         [0026]      FIG. 5E  shows a schematic representation of the fifth method step according to the present invention for connecting the solenoid to the contact element. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]     Solenoid  2  according to the present invention, shown in  FIG. 3B , is suitable, in particular, as a component for a fuel-injection valve like those used, for example, to inject fuel into the combustion chamber of a mixture-compressing, internal combustion engine with externally supplied ignition.  
         [0028]      FIGS. 1A-1C  show a schematic representation of a relay connector or terminal support  1  of a solenoid  2  according to the present invention in different views.  
         [0029]      FIG. 1A  shows a top view of relay connector  1 , which is needed to suitably hold in place wire ends  7  of wire  6 , which is shown in  FIG. 3B , and which is wound to form solenoid  2 , so that the ends may be connected to electrical lines leading to a control unit for the fuel injection valve.  
         [0030]     Relay connector  1  has a generally tab-like shape having side or lateral projections  25  and  26 . Shorter projections  25  are used, in particular, to stabilize the position of relay connector  1  in a bobbin  3 .  
         [0031]     Projections  26  are used to widen the surface of relay connector  1  so that, after bobbin  3  has been wound, the ends of winding  5  can be attached to relay connector  1 , for example by soldering.  
         [0032]     Relay connector  1  also has holes  27  and  28 , which, like projections  25  and  26 , are used to fix relay connector  1  in place in bobbin  3  or to fasten wire ends  7 . For example, wire ends  7  may be fed through hole  28  and then pinched. Hole  27  is filled with plastic when relay connector  1  is injected into bobbin  3 , thereby securing relay connector  1  in place in bobbin  3 .  
         [0033]      FIG. 1B  shows a corresponding side view of relay connector  1 . Due to its simple shape, relay connector  1  may be easily produced, for example, by punching it out of a metal sheet.  
         [0034]      FIG. 1C  shows a cross-section along the line marked IC-IC in  FIG. 1A . In an exemplary embodiment, relay connector  1  may have rounded edges, which further simplifies processing.  
         [0035]      FIGS. 2A-2B  show a schematic view and a schematic longitudinal section, respectively, of bobbin  3  of a solenoid  2  according to the present invention, and  FIG. 2C  shows an enlarged view of the area marked IIC in  FIG. 2B .  
         [0036]      FIG. 2A  shows a schematic side view of unwound bobbin  3  having relay connectors  1  already attached to bobbin  3 . Because of their simple shape, relay connectors  1  are easily connectable to bobbin  3 . Bobbin  3  is principally made of plastic by injection molding. Relay connector  1  is injected into bobbin  3  up to lateral projections  25 .  
         [0037]     Bobbin  3  has a largely cylindrical hollow design with a circumferential recess  30  for holding winding  5 .  
         [0038]     An extension  4  of bobbin  3 , which forms an end area and extends the cylindrical hollow cross-section of bobbin  3  in an angular range of approximately 400, is molded onto bobbin  3 . Relay connectors  1  are injected in one end area  31  of extension  4 .  
         [0039]      FIG. 2B  shows a longitudinal section of bobbin  3  of solenoid  2  according to the present invention, illustrated in a schematic sectional representation. Relay connectors  1  are attached in projecting end area  31  of extension  4  of bobbin  3 .  
         [0040]      FIG. 2C  shows an enlarged view of section IIC of  FIG. 2B  for further clarification. Relay connectors  1  are inserted into extension  4  of bobbin  3  up to the point marked E in  FIG. 1A .  
         [0041]      FIG. 3A  shows a view of the relay connector end of a solenoid  2  according to the present invention. Of a winding  5  of solenoid  2 , only wire ends  7 , which are wound around relay connector  1 , are visible.  
         [0042]      FIG. 3B  shows a side view of a solenoid  2  according to the present invention, around which winding  5  of a wire  6  is wound on bobbin  3 . Wire ends  7  are routed from winding  5  of solenoid  2  via extension  4  of bobbin  3  to relay connectors  1 . Wire ends  7  are routed to relay connectors  1  in an indentation  32  provided in extension  4  of bobbin  3 , and they are wound around relay connectors  1  at least once in the area between projections  25  and  26  and may have flattened segments  8  for better attachment to relay connectors  1 . Possible attachment methods include welding or soldering or even fixing wire ends  7  in hole  27 .  
         [0043]      FIGS. 4A-4C  show schematic representations of three consecutive processing steps in the manufacture of a contact element  9  according to the present invention.  
         [0044]      FIG. 4A  shows a schematic view of one exemplary embodiment of contact element  9 , which, like relay connectors  1 , is easily punchable from a metal sheet. Contact element  9  has two contact tabs  10  which have rounded front edges  11 . Both contact tabs  10  are punched out in a single piece, connected by a web  12  which is removed later on. Two extensions  13  projecting outward at a desired angle are provided at the end of contact element  9  opposite rounded edges  11 . Extensions  13  are used for connection to relay connectors  1  in a later processing step. Multiple holes  14   a ,  14   b  are provided in contact tabs  10  of contact element  9 , with the present exemplary embodiment having two holes per contact tab  10 .  
         [0045]     In the next processing step, whereby contact element  9  is extrusion-coated, the plastic enters holes  14   a ,  14   b , securely anchoring contact tabs  10  of contact element  9  in the plastic.  
         [0046]      FIG. 4B  shows a schematic view of contact element  9  after contact tabs  10  have been extrusion-coated with plastic. A first plastic web  15  is formed in the area of holes  14   a . The plastic enters holes  14   a  and holds contact tabs  10  a certain distance apart, determined by the width of web  12 . A connecting part  16  according to the present invention is injection-molded onto plastic web  15 . For stability, a second plastic web  19  is provided in the area of holes  14   b  and used to stabilize the position of contact tabs  10  relative to one another.  
         [0047]     To electrically isolate contact tabs  10 , metallic web  12  is removed by punching.  
         [0048]     First plastic web  15  continues into connecting part  16 , which was injection-molded onto contact element  9 , using a suitable apparatus which is not illustrated in any further detail here. Connecting part  16  is in the shape of a hollow cylinder that is open at one end. Slightly more than half of the cylinder wall is designed as a complete hollow cylinder. Extensions  13 , which will connect contact tabs  10  to relay connectors  1  later on, project laterally from plastic web  15 .  
         [0049]      FIG. 4C  shows a side view of the exemplary embodiment of contact element  9  illustrated in  FIG. 4B  after a further processing step. In this processing step, contact element  9  is bent at an approximately 30-degree angle toward the horizontal at a bending point  17  in the vicinity of plastic web  15 .  
         [0050]      FIGS. 5A-5E  show a schematic representation of the method steps for connecting solenoid  2  according to the present invention to contact element  9 .  
         [0051]      FIG. 5A  shows a view similar to that in  FIG. 3A  of the relay connector end of bobbin  3 . Relay connectors  1  and wire ends  7  are visible in end area  4  of bobbin  3 .  
         [0052]      FIG. 5B  shows the same representation of bobbin  3  after relay connectors  1  have been bent. Relay connectors  1  are preferably bent outward at a 90-degree angle from their previous position.  
         [0053]      FIG. 5C  shows a side view of solenoid  2  that is already mounted on a housing body  18 . Housing body  18  has an external housing  21 , which encapsulates solenoid  2 , and an inner housing part  22  that grips solenoid  2  and has an outer diameter equal to the inner diameter of connecting part  16 . Due to the special shape of connecting part  16  according to the present invention, it may be mounted on inner housing part  22  in a stable snap-on connection. Connecting part  16  surrounds inner housing part  22  in an area which forms an angle greater than 180 degrees, preventing connecting part  16  from sliding off inner housing part  22  in the radial direction.  
         [0054]      FIG. 5D  shows the same view as  FIGS. 5A and 5B , illustrating bobbin  3 , which is mounted on inner housing part  22 , with connecting element  9  positioned over connecting part  16 . Extensions  13  of contact tabs  10  of contact element  9  come to rest on bent relay connectors  1  of bobbin  3 . First plastic web  15  of contact tabs  10  of contact element  9  has an external shape that prevents connecting part  16  from sliding on internal housing part  22 .  
         [0055]     In the final method step, as shown in  FIG. 5E , contact element  9  is connected to relay connectors  1  by a weld  20  or by soldering it onto extensions  13 . The welding or soldering step arrests contact element  9  firmly in its final position so that it cannot move in either axial or radial direction. This also establishes a secure electrical contact between contact element  9  and relay connectors  1 .  
         [0056]     The present invention is not limited to the illustrated exemplary embodiment, but is also suitable for a contact element  9  having a wide variety of other shapes. According to the method of the present invention, coils having multiple windings insulated against one another may be provided with a contact element of any design.