Abstract:
An over-molded harness including a plurality of bundled flexible electric wires, an electrical or electronic element electrically connected between at least two of the wires, and at least a portion of the bundled electrical wires having an over-molded insulative covering, whereby the electrical or electronic element is unsupported by other than primarily by the over-molded insulative covering and secondarily by the flexible electric wires, the electrical or electronic element being both precisely located and completely enclosed within the insulative covering.

Description:
BACKGROUND 
       [0001]    The present invention relates to conductive wire harnesses, and more particularly such harness that include an over-molded element formed of a material such as a polymer. 
         [0002]    In some applications such as powered hand tools, components such as motors, control circuits, external control elements (switches, etc.) and displays are variously distributed in the device and interconnected by various electrical wires that are often bundled as a wiring harness. Over-molding of such harnesses or portions thereof for preventing wire damage, for example is known. See, for example, U.S. Pat. No. 7,204,724 to Holtz, U.S. Pat. No. 7,393,218 to Pavlovic, and U.S. Pat. No. 7,462,780 to Marsh et al. A mold for over-molding a harness is disclosed in U.S. Pat. No. 6,071,446 to O&#39;Brien et al. 
         [0003]    In some situations, such as when a needed component does not fit well within the space of a connected component, or when a new component is needed within an existing product design, and particularly when the physical location of the needed component is critical, the known prior art does not provide a satisfactory solution. 
         [0004]    Thus there is a need for an over-molded harness that includes one or more otherwise unsupported circuit elements such as inductors, varistors, and integrated circuits in the over-molding. 
       SUMMARY 
       [0005]    The present invention meets this need by providing an over-molded wire harness that includes at least one otherwise unsupported circuit element that is precisely located. In one aspect of the invention, an over-molded harness includes a bare harness including a plurality of bundled flexible electric wires and a circuit component having electrical connections between at least two of the wires; and at least a portion of the bare harness having an over-molded body forming an insulative covering, whereby the circuit component is unsupported by other than primarily by the over-molded insulative covering and secondarily by the flexible electric wires, the component being both precisely located and completely enclosed within the insulative covering. As used herein, “circuit component” includes an electrical component such as a resistor, a varistor, and an inductor, or an electronic element such as a diode, a transistor, and an integrated circuit. The circuit component can include a component body and electrical leads, the harness preferably further including a pre-mold body having the component body substantially encapsulated therein to form a pre-mold module with portions of the leads projecting from the pre-mold body, the pre-mold body having one or more registration surfaces for precisely locating the pre-mold module within the over-molded body. The one or more registration surfaces can include a parallel-spaced pair of registration openings. 
         [0006]    The electric wires can have insulation coverings, the over-mold body preferably having locating cavities formed therein for facilitating positioning of the wires away from outside surfaces of the over-mold body, the bare harness further including lengths of insulative tubing located over the electrical connections and over portions of the wires to be adjacent the locating cavities, for providing double insulation layers between conductors of the wires and the outside surfaces of the over-mold body. The over-mold body can have a major cavity formed therein for receiving an external member in registration with the over-mold body, the circuit component preferably being precisely located proximate the major cavity and closely spaced inwardly from the outside surface of the over-mold body for sensing an operating parameter such as speed associated with the external member. The over-molded harness having the major cavity can be provided in an assembly with a motor having a major projection, the major projection engaging and registering the over-mold body. The major projection of the motor can be formed of an insulating material, the over-mold harness in the assembled condition preferably providing double insulation of the electrical wires and the circuit component within the over-mold body. 
         [0007]    In another aspect of the invention, apparatus for making an over-molded harness having a plurality of flexible electrical wires and a circuit component to be precisely located within an over-molded body of the harness, wherein the circuit component has a component body and electrical leads, includes: a pre-mold die set including (a) a first die block formed for receiving a portion of at least one of the leads and having a first component registration surface for contacting the component body, the circuit component being precisely located relative to the first die block when the component body is seated contacting the component registration surface with the portion of the at least one lead received in the first die block; (b) a second die block configured for facing contact with the first die block, the first and second die blocks forming a pre-mold cavity for enclosing the component body and portions of the leads in a pre-mold body to form a pre-mold module having portions of the electrical leads projecting therefrom; and (c) means for defining at least one module registration surface within the cavity, the module registration surface being spaced from the circuit component when the circuit component is seated within the cavity. The apparatus also includes (d) an over-mold die having a main cavity for receiving the pre-mold module and portions of a plurality of bundled flexible electric wires, the projecting lead portions being electrically connected to respective ones of the wires; and (e) means for precisely registering the pre-mold module within the main cavity by contacting the at least one module registration surface, whereby, when the over-molded body is formed in the main cavity, the circuit component is both precisely located and completely enclosed within the over-molded body, the circuit component being unsupported by other than primarily by the over-molded insulative covering and secondarily by the flexible electric wires. The at least one module registration surface of the pre-mold module can include a parallel-spaced pair of registration openings, the means for precisely registering the pre-mold module including a spaced pair of registration pins projecting into the main cavity. 
         [0008]    A further aspect of the invention provides an over-molding process for precisely locating a circuit component in an over-molded body of an electrical wire harness. The process includes the steps of: (a) providing a pre-mold module having a body of the circuit component substantially enclosed therein, with electrical leads of the component projecting from a molded body of the module, the molded body having one or more registration surfaces formed thereon; (b) providing an over-mold die having a main cavity for forming an over-mold body, and having one or more registration elements therein for engaging the one or more registration surfaces of the molded body of the pre-mold module; (c) providing a set of flexible electrical wires for the harness; (d) electrically connecting the leads of the circuit component to corresponding ones of the electrical wires; (e) bundling the wires to form a bare harness; (f) seating the pre-mold module in the over-mold die, in registered engagement with the one or more registration elements, portions of the bare harness extending within the main cavity of the over-mold die; feeding and setting an over-molding material into the over-mold die; and removing the completed over-molded harness from the over-mold die. 
         [0009]    The step of providing the pre-mold module preferably includes the further steps of (a) providing a pre-mold die for receiving the circuit component, the pre-mold die having counterparts of the registration elements for forming the registration surfaces; (b) registering the circuit component in the pre-mold die; (c) feeding and setting a pre-molding material into the pre-mold die; and (d) removing the completed pre-mold module from the pre-mold die. The registration elements of the over-mold die can include a spaced pair of registration pins. Preferably the electrical wires have insulation coverings and the over-mold die has projections extending into the main cavity for positioning the wires away from outside surfaces of the main cavity, the method comprising the further step of locating insulative tubing over the electrical connections and over portions of the wires to be adjacent the projections, for providing double insulation layers between conductors of the wires and the outside surfaces of the over-mold body. 
     
    
     
       DRAWINGS 
         [0010]    These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings, where: 
           [0011]      FIG. 1  is a top plan view of an over-molded wire harness according to the present invention; 
           [0012]      FIG. 2  is a detail plan view within region  2  of  FIG. 1 ; 
           [0013]      FIG. 3  is sectional detail view on line  3 - 3  in  FIG. 2 ; 
           [0014]      FIG. 4  is a sectional detail view on line  4 - 4  in  FIG. 2 ; 
           [0015]      FIG. 5  is a sectional detail view on line  5 - 5  in  FIG. 2 ; 
           [0016]      FIG. 6  is a detail plan view of a pre-mold circuit element module of the harness of  FIG. 1 ; 
           [0017]      FIG. 7  is a front elevational view of the pre-mold circuit element module of  FIG. 6 ; 
           [0018]      FIG. 8  is a side view of the pre-mold circuit element module of  FIG. 6 ; 
           [0019]      FIG. 9  is a fragmentary perspective view showing alignment of the over-molded wire harness of  FIG. 1  with a device motor for assembly therewith; 
           [0020]      FIG. 10  is a plan view of a molding tool portion for the over-molded harness of  FIG. 1 ; 
           [0021]      FIG. 11  is a sectional view on line  11 - 11  of  FIG. 10 ; 
           [0022]      FIG. 12  is a plan view of another molding tool portion for the over-molded harness of  FIG. 1 ; 
           [0023]      FIG. 13  is a perspective view of a die set for producing the pre-molded module of  FIGS. 6 ,  7 , and  8 ; and 
           [0024]      FIG. 14  flow chart of a process for making the over-molded harness of  FIG. 1 . 
       
    
    
     DESCRIPTION 
       [0025]    The present invention is directed to an over-molded wire harness that incorporates a precisely positioned circuit element that is supported only by the over-molding material and secondarily by flexible wires of the harness. With reference to  FIGS. 1-9  of the drawings, an over-molded harness  10  includes a bundled plurality of electrical wires  12  forming a bare harness  14 , and an over-molded body  16  that encloses and secures at least a portion of the bare harness. As further shown in  FIG. 1 , an exemplary configuration of the over-molded harness  10  is branched, with groups of the wires having various singular and ganged terminations; particularly a first connector  18  terminating eight of the wires  12 , a second connector  20  terminating five of the wires, a third connector  22  also terminating five of the wires, and several variously configured singular and/or doubled terminations, designated terminators  24 A,  24 B, and  24 C. Also, the bare harness  14  optionally includes one or more cable ties  26 , and an insulating sleeve  28 . It will be understood that the arrangement of wires and terminations of the bare harness  14  is to suit particular devices incorporating the over-molded harness  10 , and forms no part of the present invention. As shown in  FIG. 9 , the over-molded body  16  is configured to register on the end of a device motor  30  having a major end projection  32  from an end face of the motor, and a minor end projection  34  from the face  33 , the body  16  having correspondingly shaped a major cavity  36  and a minor cavity  37 . A housing (not shown) of the device serves to retain the body  16  seated on the motor  30 , the over-molded body  16  having a raised pad portion  38  that includes a pair of registration cavities  39  for engagement by the housing as also shown in  FIG. 4 . 
         [0026]    According to the present invention, a circuit element in the form of an inductor  40  having an inductor body  41  and axial leads  42  is precisely positioned within the over-molded body  16  as described herein. With particular reference to  FIGS. 6-8 , the inductor  40  is encapsulated in a pre-mold body  44  to form a pre-mold module  45 , the leads  42  having formed bends with portions  46  of the leads projecting in spaced parallel relation from the pre-mold body  44 . The pre-mold body  44  has a narrowed portion  47  that serves to precisely confine the inductor body  41  in a direction parallel to the parallel projecting lead portions  45  of the leads  42 . Further, the inductor body  41  is formed having a parallel-spaced pair of registration openings  48  that are oriented perpendicular to the inductor body and to the projecting lead portions  46 . 
         [0027]    As shown in  FIG. 3 , the over-molded body  16  is formed having a pair of first upper locating cavities  50  and a pair of first lower locating cavities  52  that are formed by respective posts (described below) for positioning particular ones of the electrical wires  12  adjacent the minor cavity  37  during molding of the body  16 . As further shown in  FIG. 3 , each of the lead portions  46  of the inductor  40  are electrically connected to respective ones of the wires  12 , a short length of heat-shrink tubing  54  being installed over groups of the wires and covering the electrical connections. 
         [0028]    As further shown in  FIGS. 2 and 4 , the over-molded body  16  is formed having a plurality of locating openings  56  for confining electrical wires proximate the major cavity  36 , away from outer surfaces of the body. This feature insures that the wires  12  have double insulation, the material of the body providing an additional layer of insulation to the native insulating covering of the wires themselves. It will be understood that the major projection  32  of the motor  30  is formed of an insulating material, so that exposure of wires at the major cavity  36  of the over-molded body  16 , if any, would not compromise the double insulation properties of the body  16 . 
         [0029]    As shown in  FIGS. 2 and 5 , the over-molded body  16  has an additional pair of second upper locating cavities  58  and second lower locating cavities  60  that are spaced toward a distal extremity  62  of the body  16 . The locating cavities  58  and  60  are formed by additional posts (described below) as for the first locating cavities  50  and  52  of  FIG. 3 . The electrical wires  12  exiting the over-molded body  16  at the distal extremity  62  are covered by an insulating sleeve  64  that can be formed by a length of heat-shrink tubing. The sleeve  64  extends within the body beyond the second locating cavities  58  and  60  for maintaining double insulation of the wires  12 . 
         [0030]    Suitable materials for the pre-mold body  44  and the over-molded body  16  include PVC, TPE, and other shock-absorbing thermoplastic polymers, preferably in an electrical insulation grade that provides a secondary insulation layer to the wires. As described herein the over-molded harness  10  is believed to be acceptable as a direct double-insulation device and method for Underwriters Laboratory (UL) certification, thus eliminating a need for an additional insulation layer such as a film or mechanical plastic layer over the harness. 
         [0031]    With further reference to  FIGS. 10-12 , a pair of molding tool portions, designated upper tool portion  66  ( FIGS. 10 and 11 ) and lower tool portion  67  ( FIG. 12 ) for producing the over-molded harness of  FIG. 1  includes an upper die block  68  having an upper main cavity  70  shaped to form an upper portion of the over-molded body  16 , and a lower die block  69  having a main cavity  71  to form a lower portion of the body. (The upper die block  68  is shown inverted from the orientation of the body  16  as depicted in  FIGS. 1-5 .) In use, the lower tool portion  67  (for example) would be inverted and clamped onto the upper tool portion  66 , the main cavities  70  and  71  forming a single cavity for defining the outside shape of the over-molded body  16 . It will be understood that the tool portions  66  and  67  are shown in simplified form, with conventional features such as guides and runners being omitted in the drawings. 
         [0032]    The upper die block  68  is formed with a first projection  72  and a second projection  74  in the main cavity  70  for forming the major cavity  36  and the minor cavity  37  of the body  16 . The die block  68  is also formed with a pair of first channels  76  for receiving groups of the electrical wires of the bare harness  14 , and a second channel  78  for receiving the insulating sleeve  64 . A pair of register pins  80  are fixedly installed in the die block  68 , projecting into the main cavity  70  for precisely locating the pre-mold module  45 , the module  45  to be seated in contact with the bottom of the main cavity  70 . Further, a pair of first upper locating posts  82  and second upper locating posts  84  project into the main cavity  70  for defining the first and second upper locating the cavities  50  and  52  of the body  16  (shown in  FIGS. 3 and 5 ); moreover, a plurality of locating pins  86  also project into the cavity  70  for defining the locating openings  56  of the over-molded body  16  (shown in  FIG. 4 ). 
         [0033]    Similarly, the lower die block  69  is formed with a pair of register posts  73  projecting within a pad cavity  75  for forming the registration cavities  39  in the pad portion  38  of the over-molded body  16 . The die block  69  is also formed with a raised pair of first channels  77  that align with the first channels of the upper die block  68  for receiving the groups of the electrical wires of the bare harness  14 , and a raised second channel  79  for receiving the insulating sleeve  64  in cooperation with the second channel of the die block  68 . The raised form of the first and channels  77  and  79  of the lower die block  69  cooperate with deepened corresponding channels  76  and  78  of the upper die block to effect exit of the electrical wires  12  in offset relation to facing surfaces of the upper and lower die blocks. A pair first lower locating posts  83  and second lower locating posts  85  project into the main cavity  71  for defining the first and second lower locating cavities  52  and  60  of the body  16  (shown in  FIGS. 3 and 5 ). 
         [0034]    With further reference to  FIG. 13  an exemplary die set  90  (shown in simplified form) for producing the pre-mold module  45  includes a first die block  91  having a raised portion  92  for forming the narrowed portion  47  of the pre-mold body  44 , and spaced pair of lead holes  93  for receiving the lead portions  46  of the inductor  40  that are to be exposed. A mating second die block  94  has a pre-mold cavity  95  formed therein for forming the remainder of the pre-mold body  44 , and a pair of registration pins  96  extending in parallel relation through the cavity  95 . The registration pins  96  have tapered portions for forming countersink depressions at one end of each registration opening  48  of the pre-mold body (see  FIGS. 6 and 7 ), and are stepped for receiving respective correspondingly shaped collars  97  that form opposite countersink depressions at opposite ends of the openings  48 . The second die block  94  can also be split as indicated at  98  in  FIG. 13 . It will be understood that with the leads  42  of the inductor formed in predetermined coplanar relation to each other, the location of the inductor body  41  assumes a precise location relative to the first die block  91  when the body  41  rests on the raised portion  92 . The pre-mold cavity  95  is preferably formed in close proximity to the inductor body  41  such that, when the pre-mold module  45  is seated in the upper die block  68 , the inductor body  41  becomes precisely positioned proximate the major projection  32  and to the main portion of the motor  30  when the over-molded harness  10  is assembled therewith for accurate speed sensing of the motor. 
         [0035]    With further reference to  FIG. 14 , an over-molding process  100  for precisely locating a circuit component in an over-molded body includes the steps of: 
         [0036]    (a) providing a pre-mold module having a body of the circuit component substantially enclosed therein, with electrical leads of the component projecting from a molded body of the module, the molded body having one or more registration surfaces formed thereon; 
         [0037]    (b) providing an over-mold die having a main cavity for forming an over-molded body, and having one or more registration elements therein for engaging the one or more registration surfaces of the molded body of the pre-mold module; 
         [0038]    (c) providing a set of flexible electrical wires for the harness; 
         [0039]    (d) electrically connecting the leads of the circuit component to corresponding ones of the electrical wires; 
         [0040]    (e) bundling the wires to form a bare harness; 
         [0041]    (f) seating the pre-mold module in the over-mold die, in registered engagement with the one or more registration elements, portions of the bare harness extending within the main cavity of the over-mold die; 
         [0042]    (g) feeding and setting an over-molding material into the over-mold die; and 
         [0043]    (h) removing the over-molded harness from the over-mold die. 
         [0044]    The registration elements of the over-mold die can include the spaced pair of registration pins. The electrical wires preferably have insulation coverings and the over-mold die preferably has projections extending into the main cavity for positioning the wires away from outside surfaces of the main cavity, the method including the further step of locating insulative tubing over the electrical connections and over portions of the wires to be adjacent the projections, for providing double insulation layers between conductors of the wires and the outside surfaces of the over-molded body. 
         [0045]    Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not necessarily be limited to the description of the preferred versions contained herein.