Patent Abstract:
This invention relates to a transformer and more particularly, to a system and method for making a transformer utilizing dynamic magnetic compaction. A coil is placed in a conductive container, and a conductive powder material, such as ferrite, is placed in the container and surrounds the coil and the turns of the coil. A power supply energizes a capacitor which subsequently provides a high energizing current to a second, energizing coil within which the container, material and inner coil are situated, thereby causing the container, powder materials and coil to be compacted to provide an electrical component, such as a transformer, motor, commutator, rotor or choke.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of U.S. patent application Ser. No. 09/504,678 filed Feb. 15, 2000, which is based on provisional patent Application Serial No. 60/120,244 filed Feb. 16, 1999 and a continuation-in-part of Ser. No. 08/681,898 filed Jul. 29, 1996. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to electrical components, such as transformers, chokes and, more particularly, to a method and system for forming particulate or powder-like materials into a unitary, firmly-compacted body of material to provide transformers, chokes, commutators, rotors and/or stators for motors.  
           [0004]    2. Description of Related Art  
           [0005]    Powder metal bodies have been formed by means of pressure and heat. Such a method has also been used for forming unitary bodies from other particulate materials. U.S. Pat. Nos. 5,405,574; 5,611,139; 5,611,230 and 5,689,797 all disclose systems and methods for compacting powder-like materials. For example, U.S. Pat. No. 5,689,797 discloses a method for producing an annular body wherein a container is filled with a particulate material and an electrically conductive drive member is used to induce a current in the container to cause a compaction pressure to be applied to the particulate material. This causes the material to compress and compact within the container into an annular body of magnetic compacted particulate material.  
           [0006]    Similarly, U.S. Pat. No. 5,611,139 discloses a structure for increasing the density of a powder comprising a support for receiving the powder and an electrically conductive driver positioned adjacent the support and a connector for connecting the driver to a source of electrical energy for energizing the driver to create a magnetic field to pressure the powder, thereby producing an integral part from the powder. These patents are owned by the same Assignee as the present invention, and are incorporated herein by reference and made a part hereof.  
           [0007]    [0007]FIG. 11 shows a prior art magnetic compaction system having a direct current power supply A to which is connected electrical conductors B and C. Connected to the conductor B is a switch D which is also connected to a conductor E. The conductor E and the conductor C have joined there between a capacitor. The conductor E is also connected to a switch G which is also connected a connector H. The conductor C and the conductor H are connected to a solenoid I which encompasses an electrically conductive container I.  
           [0008]    In operation, the switch is closed, and the capacitor F is charged from the power supply A. After the capacitor F is completely charged, the switch D is opened and the switch G is closed. When the switch G is closed, a large quantity of electrical current flows from the capacitor F through the solenoid or energizing coil I. When the electrical current flows through the solenoid or energizing coil I, magnetic pressure is applied upon the electrical conductive container J. This pressure acts inwardly upon the electrically conductive container J, and the transverse dimensions of the electrically conductive J are reduced. Thus, compaction occurs within the electrically conductive container  38  and the powder-like material K is compressed and compacted to form a dense body. Thus, the powderous material K within the electrically conductive container J becomes a dense body.  
           [0009]    Due to the fact that the solenoid or energizing coil I tends to expand radially as current flows there through, suitable means have been employed to restrain the coil I against lateral expansion as current flows there through. For example, as shown in FIG. 11, a wall L may closely encompass the energizing solenoid or coil I and restrain the solenoid or coil I against expansion as current flows there through.  
           [0010]    One problem with the current designs and configurations of ferrite-based transformers is that they tend to be relatively large. Consequently, the costs associated with manufacturing and producing such transformers tends to be relatively high, and reliability is not as good as desired.  
           [0011]    What is needed, therefore, is a transformer design and manufacturing process capable of utilizing dynamic magnetic compaction technology which facilitates reducing the size of the parts, such as the transformers, and which reduces or eliminates the number of manufacturing and assembly steps required by prior art techniques.  
         SUMMARY OF THE INVENTION  
         [0012]    This invention provides a system and method wherein powder-like and/or particulate materials are received in a container along with a insulated coil and subject to dynamic magnetic compaction to produce a transformer, choke, rotor or stator for an electric motor and the like.  
           [0013]    The method and related structure of this invention applies pressures generated by non-contact electromagnetic forces. These electromagnetic pressures are generated by employing suitably shaped energizing coils, such as solenoids or the like, which have the necessary capacity. An electrically conductive container is provided wherein a powder-like material and an inner coil is situated therein. An electrical current is passed through a solenoid or energizing coil surrounding the container, and the electrically conductive container is reduced in transversed dimensions, thereby encasing both the particulate material and inner coil to provide a high density body which may be used as a transformer or choke. The compaction of the particulate material is preferably performed by electromagnetic compaction as electrical energy is applied in short time pulses.  
           [0014]    An object of this invention is to provide a compacted electrical component having improved manufacturing characteristics, reduced cost and improved reliability.  
           [0015]    Another object of this invention is to provide an electrical component manufactured using dynamic magnetic compaction.  
           [0016]    In one aspect, this invention comprises a component part comprising a conductive container for receiving a powderous material, an internal coil having an insulating coating situated in the conductive container, the conductive container compacting the powderous material about the internal coil to form the component part when the conductive container is subject to an electromagnetic field.  
           [0017]    In another aspect, this invention comprises a method of making a component part comprising the steps of providing a conductive container for receiving a powderous material, situating an internal coil having an insulating coating situated in the conductive container, situating a powderous material in the conductive container, energizing the conductive container to magnetically compact the conductive container and the powderous material to provide the component part.  
           [0018]    In still another aspect, this invention comprises a compaction system comprising a power supply, a plurality of conductors coupled to the power supply, an energizing coil for providing an electromagnetic field, at least one capacitor connected across the energizing coil, at least one switch coupled to the plurality of conductors and selectively coupling the power supply to at least one capacitor and at least one switch, the energizing coil be situated relative to a conductive container in order to generate an electromagnetic field to energize a conductive container to magnetically compact a powderous material about an internal coil to form a component part, wherein the internal coil comprises an insulating coating.  
           [0019]    Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a perspective view of a part prior to compaction in accordance with one embodiment of the invention;  
         [0021]    [0021]FIG. 2 is a sectional view of the part shown in FIG. 1;  
         [0022]    [0022]FIG. 3 is a perspective view of the part shown in FIG. 1 after compaction;  
         [0023]    [0023]FIG. 4 is a sectional view of the part shown in FIG. 3;  
         [0024]    [0024]FIG. 5 is a perspective view of another part of another embodiment of the invention;  
         [0025]    [0025]FIG. 6 is a perspective view of another part of another embodiment of the invention;  
         [0026]    [0026]FIG. 7 is a schematic view of a magnetic compaction system in accordance with one embodiment of the invention;  
         [0027]    [0027]FIG. 8 is a section view of a bobbin in accordance with one embodiment of the invention;  
         [0028]    [0028]FIG. 9 is a sectional view, taken along the line  9 - 9  in FIG. 2, of a plurality of wires having an insulative coating which comprise the coil;  
         [0029]    [0029]FIGS. 10A and 10B are views of wound stators for an electrical motor manufactured in accordance with this invention; and  
         [0030]    [0030]FIG. 11 is an illustration of a prior art device. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]    FIGS.  1 - 10  illustrate various embodiments of the invention. As illustrated in FIG. 1, a component, such as a transformer  10 , is shown having an electrically conductive container  12  for receiving a powderous material  14  and an internal coil  16 . The internal coil  16  has an insulated coating of varnish or other suitable coating.  
         [0032]    Although the coil  16  is described as having the insulation mentioned, it should be appreciated that other types of insulation may be utilized. For example, a suitable pliable varnish or other insulation product, such as FORMVAR, may be utilized as well. Another example of an alternate coating could be polyimide. The important point is that the coil  16  and each of the wires  16   c - 16   e  (FIG. 9) have an insulation  17  to insulate them from the material  14  both during and after compaction.  
         [0033]    In the embodiment being described, the powder  14  is preferably either a ferrite or iron powder or any other suitable magnetic powder material. The powder  14  is situated in the container  12  and around the coil  16 . The container  12 , powder  14  and coil  16  are then placed inside another solenoid or energizing coil  18  as shown in FIG. 7.  
         [0034]    As best illustrated in FIG. 7, the invention comprises a power supply  20  coupled to the conductors  22  and  24 . Connected to the conductor  22  is a switch  26  which is also connected to a conductor  28 . The conductor  28  and the conductor  24  have joined there between a capacitor  30 . The conductor  28  is also connected to a switch  32  which is also connected to a conductor  34 . The conductor  24  and the conductor  34  are connected to the solenoid or energizing coil  18  which encompasses the electrically conductive container  12 . The electrically conductive container  12  is shown as being cylindrical in transverse dimension; however, the electrically conductive container  12  may be of any suitable or desired shape and size. The electrically conductive container may be of any suitable, electrically conductive material, such as, for example, silver, aluminum, copper or other conductive material.  
         [0035]    During operation, the switch  26  is closed, and the capacitor  30  is charged from the power supply  20 . After the capacitor  30  is completely charged, the switch  26  is opened and the switch  32  is closed. When the switch  32  is closed, a large quantity of electrical current flows from the capacitor  30  through the solenoid or coil  36 . When the electrical current flows through the coil or solenoid  36 , magnetic pressure is applied upon the electrically conductive container  38 . The pressure acts similarly upon the electrically conductive container  38 , and the transverse dimension of the electrically conductive container  38  are reduced. Thus, compression occurs within the electrically conductive container, and the powder-like material  14  is compacted and compressed around coil  16 . The powderous material  14  becomes a dense body and the container  12 , powder  14  and inner coil  16  provide a unitary finished part useful in providing a transformer or choke. In order to facilitate the compacting process, the container  12 , powder  14  and soil  16  may be placed in a retaining die (not shown) having a top and bottom in support of end  12   a  and  12   b  of container  12 .  
         [0036]    As best illustrated in FIGS.  1 - 5 , the coil  16  has a plurality of leads  16   a  and  16   b  which extend outside of end  12   a  and end  12   b , respectively, of container  12 .  
         [0037]    It should be appreciated that the position of the leads may vary depending on the application. For example, FIG. 5 shows leads  16   a  and  16   b  both extending from end  12   a  of container  12 . In addition, it is envisioned that the invention may comprise more than one inner coil  16 , such as the use of multiple coils  40  and  42  which are stacked as shown in FIG. 6 or they could be interlaced or woven so that the turns of each coil are adjacent to each other.  
         [0038]    It should be appreciated that the performance of the finished part will depend on the magnetic properties of the consolidated powder  14  and the compaction between the turns of the coil  16 .  
         [0039]    The magnetic performance of the powder  14  can be enhanced by using powders which have high inherent bonding characteristics and permeability, such as pure iron powder. Iron powders are preferable because of their inherent binding ability during magnetic compaction. It has been found that the performance of the component  10  can be enhanced by utilizing plastic coated powders, such as EM-1 products available from Quebec Metal Products, Inc. Performance is also enhanced by improving the compacted density of the powder  14 . In this regard, features of the invention described in U.S. patent application Ser. No. 08/681,898, now U.S. Pat. No. 6,273,963, which is assigned to the same Assignee as the present invention and which is incorporated herein by reference and made apart hereof may be utilized.  
         [0040]    Also, it has been found that providing wire  16  in an octagonal or hexagonal or other cross-sectional shaped facilitates improving the compacted density of part  10  which, in turn, improves performance.  
         [0041]    Moreover, it has been found that powder  14  between the turns of coil  16  may tend “short circuit” the magnetic periphery of the component  10 . One way to reduce or eliminate this effect is by utilizing a non-magnetic or insulating bobbin  44  (FIG. 8) formed, for example, of plastic. It has also been found that using a non-magnetic filler material  46  between the wires  16   c - 16   e  further facilitate preventing any short circuit between or among any of the wires  16   c - 16   e.    
         [0042]    Another advantage of this compacted powder component design is that it facilitates dissipating heat because the compacted powder  14  conducts the heat away from coil  16 .  
         [0043]    In the embodiment being described, the container  12  (FIGS.  1 - 5 ) comprises an exemplary dimension of 16 mm diameter, but it should be appreciated that smaller or larger components  10  may be made without departing from the features of the invention. Further, the wires  16   c - 16   e  which make up coil  16  each have a diameter of about 1 mm and are made of copper, and these dimensions may be varied as desired. After applying the techniques of the invention to compact the container  12  and powder  14  about coil  16 , the dimensions of the finished compacted part  10  are on the order of about 42 mm. It should be appreciated, however, that the dimensions and characteristics of the part  10  may be selectively varied depending upon the application.  
         [0044]    It should be appreciated that this invention may be utilized to make transformers, chokes, commutators, rotors and stators for electrical motors and any other components which can benefit from the application of dynamic magnetic compaction technology described herein. For example, FIG. 10 shows a cross-sectional view of a wound stator  50  having the wires  16  compacted therein to provide a finished stator which, when used with a rotor (not shown) and power supply (not shown) provide an electric motor capable of performing work.  
         [0045]    While the methods herein described, and the forms of apparatus for carrying these methods into effect, constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to these precise methods and forms of apparatus, and that changes may be made in either without departing from the scope of the invention disclosed herein.

Technology Classification (CPC): 1