Abstract:
An improved method and apparatus for winding electrical coils and testing them, including heat bonding of resinous coating of the windings. Both the heat bonding and testing occur in the same apparatus and the testing takes place before the heat bonding so that if the winding is not satisfactory, it can be repaired rather than scraped.

Description:
BACKGROUND OF INVENTION  
         [0001]    This invention relates to a method and device for testing and heat bonding an electrical coil for a rotating electrical machine.  
           [0002]    Many types of rotating electrical machines employ one or more coil windings. A typical machine of this type is shown in FIG. 1 wherein a magneto generator that is adapted to be associated with the crankshaft of an internal combustion engine is indicated generally by the reference numeral  11 . The magneto generator  11  is, in the illustrated construction, designed so as to provide a source of electrical power for the associated engine, for example for firing its spark plugs.  
           [0003]    The magneto generator  11  is comprised of a stator assembly, indicated generally by the reference numeral  12  which is associated with a flywheel assembly, indicated generally by the reference numeral  13  and shown in phantom. The flywheel assembly  13  is affixed for rotation with an engine crankshaft  14  and has a generally cup-shaped flywheel portion  15  upon which a plurality of permanent magnet segments  16  are affixed.  
           [0004]    The stator assembly  12  has a core  17  which has an opening that passes the crankshaft  14  and which is fixed against rotation to the body of the associated engine in a suitable manner. This core  17  has a plurality of armature poles  18 , which, like the remainder of the core  17 , is formed from a plurality of laminated metal plates  19 . The core plates  19  are comprised of thin plates of silicone or carbon steel laminated with insulating layers.  
           [0005]    Contained around each pole  18  is a winding  21 , which is wound around a bobbin  22 . The bobbin  22  is comprised of a pair of halves which encircle the laminated poles  18  and which is made by an insulating plastic by injection molding.  
           [0006]    The afore-described construction describes the stator of a rotating magneto generator of the AC type. However, it should be understood that the invention herein may be utilized in conjunction with the manufacture and testing of a plurality of types of electric coils, which may be either fixed against rotation or rotatable in the associated machine. Also, these coils may either form portions of a generator or portions of an electric motor.  
           [0007]    Referring now to FIG. 2, which shows the prior art type of apparatus normally utilized for winding, heat-bonding and testing the stator  12  and specifically the coils  21  thereof and to the left-hand or conventional side view of FIG. 3 which shows the procedure in performing the winding, the disadvantages of the prior art type of method and apparatus will be described.  
           [0008]    The core assembly  17  is first placed in a winding machine, indicated by the reference numeral  23 , which is designed so as to specifically wind the wire around the core  18  to form the coil  21 . This is performed at the step S 1  in the Prior Art method shown in FIG. 3.  
           [0009]    After the windings  21  have been completed, the wound core assembly  12  is removed from the winding machine  23  and is placed into an energization-heating machine  24 . Then at the step S 2  the terminals of the energization-heating machine are connected to the coil terminals  21  a. It should be noted that FIG. 2 only shows one pair of the coil windings, but there are three such pairs in the illustrated embodiment.  
           [0010]    Then after the connections are completed at the step S 2 , there is an energization heating performed by passing a large current through the coil windings for a short time, this also occurring in the machine  24 . This is done so as to fuse and solidify epoxy resin, which applied to the wire of winding of the stator core so as to stabilize the contact between the windings and the connection between the windings and the bobbin  22  onto which the windings are wound.  
           [0011]    Then the procedure moves to the step S 4  where the windings are cooled so that the apparatus can then be moved to an assembly line  25  wherein lead wires  26  are connected. This occurs at the step S 5 .  
           [0012]    Then, at the step S 6  the apparatus is moved to a testing machine  27  wherein a connection to the lead wires  26  is made with a device that performs a waveform test to see if the winding has been properly made. This applies a charge over a time period to determine the damping characteristics of the voltage and current by application of a rectangular wave of constant voltage for a plurality of times.  
           [0013]    If, at the step S 6  it is determine that the completed assembly is satisfactory, it is then removed from the testing machine  27  and shipped at the step S 7 .  
           [0014]    Thus, in connection with conventional apparatus and method the wound coil  21  must be moved from one station to another a number of times and the testing is not done until after the stator assembly  12  has been completed. Thus, if there is an error in the winding of the coils  21 , then the entire stator  12  must be scraped because it cannot be fixed.  
           [0015]    In addition, the cooling time is lengthened because there must be a cooling step S 4  to cool the device to a temperature low enough for the wave-form testing at the step  56  and the connections being made at the step S 5 .  
           [0016]    It is, therefore, a principal object to this invention to provide an improved and simplified method and apparatus for assembling, heat bonding and testing of an electrical coil that minimizes the number of transfers that must be made.  
           [0017]    It is a further object to this invention to provide a method and apparatus for performing this bonding and testing wherein the testing occurs before the bonding so that if the coil has not been properly wound, it can be repaired and need not be scraped.  
           [0018]    It is a further object to this invention to provide an improved arrangement, which minimizes the cooling time and thus, permits quicker assembly and lower assembly and testing costs.  
         SUMMARY OF INVENTION  
         [0019]    A first feature of the invention is adapted to be embodied in a method of winding, heat-bonding and testing an electrical coil. The method comprises the winding of the electrical coil around a pole tooth of a core using a winding machine. After the wound electrical coil is formed, it is connected to a testing device for testing the winding. The connection of the wound electric coil to the testing device is then switched to an energization-heating device for energization heating to bond the coil by fusion of a resin applied to the coil. Thereafter, the lead wires are assembled to the wound and bonded electrical coil.  
           [0020]    Another feature of the invention is adapted to be embodied in an apparatus for winding, heat-bonding and testing an electrical coil. The apparatus comprises a winding machine for winding the electrical coil and a combined testing device for testing the winding and energization-heating device for energization heating the winding to bond the electrical coil by fusion of a resin applied to the coil in a single station. A switching mechanism switches the connection of the wound electrical coil from the testing device to the energization-heating device. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0021]    [0021]FIG. 1 is a cross sectional view taken through a magneto generator which may be formed from either the prior art method or the method embodying the invention to show the construction of the components.  
         [0022]    [0022]FIG. 2 is a block diagram showing the conventional method of winding the coils, energization heating them, assembling them and testing them.  
         [0023]    [0023]FIG. 3 is a block diagram showing, on the left side, the steps of the prior art method and, on the right hand side, the steps in the method embodying the invention.  
         [0024]    [0024]FIG. 4 is a partially schematic view, in part similar to FIG. 2, but shows the apparatus in accordance with the invention.  
         [0025]    [0025]FIG. 5 is a more detailed view showing the combined testing and bonding apparatus of the invention.  
         [0026]    [0026]FIG. 6 is timing diagram showing the timing chart in accordance with the method by which the apparatus in FIG. 5 works. 
     
    
     DETAILED DESCRIPTION  
       [0027]    Referring now primarily to the right hand side of FIG. 3 and to FIG. 4, the apparatus and method for performing the invention will be described in detail. The apparatus is shown in FIG. 4, and the method, 1s shown at the right hand side of FIG. 3. The initial step and apparatus of the invention is the same as the prior art. It begins at the step S 101  where the coil core  17  is placed into a conventional type of winding machine  23  so that the coils  21  may be wound and the terminals  21  a attached.  
         [0028]    This attachment step is indicated at the step S 102  and is basically the same as the step S 2  of the prior art method. However, the wound stator  12  is then removed from the winding machine  23  and placed into a machine, indicated generally by the reference numeral  51 , which has a combined testing device and energization heating device. This machine  51  has, as shown also in FIG. 5, a testing machine portion  52  and an energization heating machine portion  53 .  
         [0029]    The testing machine portion  52  has a connection to an AC power source  54  with a power transformer  55  that steps up the voltage from the AC source  54  and then delivers it to a rectifying section  56 . The output of the rectifying section  56  is passed through a smoothing section  57  to a current control section  58 . An oscilloscope  59  is connected across the outputs of the current control section and is connected to a two pole, two-way switch  61 . This switch  61  selectively couples the terminal ends  21  a that are connected to terminals  62  of the machine  51  to either the testing machine portion  52  or the heat energizing portion  53 .  
         [0030]    Unlike the prior art, before the energization heating the testing of the winding  21  is accomplished. This is done for example by applying a pulse of 1 K volts for 19 μ second time widths to the coil winding  21  fives times at given time intervals (FIG. 6).  
         [0031]    Changes in voltage and current on the winding  21  are determined by the oscilloscope  59 . This testing is done at the first phase of the step S 1103 .  
         [0032]    Assuming the winding is properly made, and then the switch  61  is switched over to connect to the energization-heating machine portion  53 . As seen in FIG. 3, this also includes a suitable electric power source, which may be the same source  54  and a step up transformer  62  that steps up the voltage which is, in turn, delivered to a rectifying section  63 . The output of the rectifying section  63  is delivered to a smoothing section  64 . The output from the smoothing section  64  is applied to a current control section  65  so as to energize the coil winding  21  with a large current such as 30 or 40 amps for a given time period, such as 15 to 20 seconds, so as to heat the winding of the stator  12  and achieve the bonding of the resinous material (FIG. 6).  
         [0033]    Thus, these operations all take place at the step S, 103 . As has been previously noted, this is done in such a way that if the winding  21  is not satisfactory, the stator  12  can be removed from the testing and heating machine  51  and repaired.  
         [0034]    After this combined testing and heating is successfully completed, the program moves to the step S 104  so as to provide a cooling time period. Also since the energization heating takes place after the testing, the cooling time period can be significantly shortened as shown in FIG. 3 by the time ranges t 1  and t 2 .  
         [0035]    This is because the only step following is the lead wire connection which is done at the step S 105  and is the same as that in the conventional step S 5 . Then there is merely made a continuity test at the step S 106  which again takes place over a shorter time period T 3  than the longer time period T 4  applied with the conventional waveform testing of the prior art step.  
         [0036]    Then, the device can be shipped at the step S 107  and this is done with a much simpler structure and in a shorter time period so as to reduce costs. Also, as noted, the testing is done at a time when it would still be possible to repair the device and not scrap it.  
         [0037]    Thus, from the foregoing description it should be readily apparent that the described embodiment of the invention provides a very rapid and low cost yet highly efficient way for completing the construction and testing of a coil winding. Of course, the foregoing description is that of a preferred embodiment of the invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.