Abstract:
A method of constructing a spark plug that has positive and ground electrodes configured such a spark plug defined between the positive and ground electrode extenders comprises an elongate channel which opens axially and away from the body and is substantially unobstructed in the axial direction to provide better ignition resulting in improved fuel economy. The method involves taking a body part of a conventional spark plug and welding an adapter part to the body part to produce a spark plug with the elongate channel.

Description:
[0001]    This application is a utility application that claims priority to and is a continuation-in-part of co-pending U.S. Utility Application entitled “Sparkplug Construction, having Ser. No. 12/359,702, filed on Jan. 26, 2009, and which is hereby incorporated in it&#39;s entirely. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to spark-ignited internal combustion engines. 
       BACKGROUND OF THE INVENTION 
       [0003]    In internal combustion engines, it is conventional to initiate combustion with the use of spark plugs. In conventional spark plugs, a body which defines a longitudinal axis is provided. The body has, adjacent one end thereof, a metal ring which is orientated coaxially with the longitudinal axis. The body further includes a metal tube which: is orientated coaxially with the longitudinal axis; extends from the ring towards the other end of the body; and is externally-threaded for engagement in a corresponding threaded bore in an engine block in use. A porcelain insulator also forms part of the body. The insulator has a portion disposed inside the tube. This portion extends axially, from inside the tube, beyond the ring, and has an elongate void extending axially therethrough. An elongate positive electrode occupies the void and extends axially beyond the insulator to a terminus which defines the one end of the body. Conventional spark plugs also include an electrode leg. The electrode leg has two arms transversely connected to one another, with one arm extending axially from the ring and beyond the electrode and the other arm extending radially inwardly from the one arm so as to terminate in an end portion that is axially-spaced from the terminus. The spark gap in this conventional plug is the space defined between the positive electrode and the electrode leg, this gap being substantially entirely obstructed in the axial direction by the electrode leg. 
       SUMMARY OF THE INVENTION 
       [0004]    An adapter for use with a spark plug body and an engine block forms one aspect of the invention. The plug body defines a longitudinal axis and has: adjacent one end, a metal ring which is orientated coaxially with the longitudinal axis; a metal tube which is orientated coaxially with the longitudinal axis, extends from the ring towards the other end of said body and is externally-threaded for engagement in a corresponding threaded bore in said engine block in use; an insulator having a portion disposed inside the tube, which portion extends axially, from inside the tube, beyond the ring, and has an elongate void extending axially therethrough; and an elongate positive electrode which occupies the void and extends axially beyond the insulator to a terminus which defines the one end of said body. The adapter:
       is secured, in use, to said body;   comprises: a positive electrode extender which, in use, is in electrically-conducting contacting relation to the positive electrode; and a ground electrode extender which, in use, is in electrically-conducting contacting relation to the metal ring; and   is configured such that a spark gap defined between the positive and ground electrode extenders comprises an elongate channel which opens axially and away from said body and is substantially unobstructed in the axial direction.       
 
         [0008]    According to another aspect of the invention, in the adapter for use with a spark plug body and an engine block, the ground electrode extender can comprise a fixed portion that is welded to the ring, thereby to secure the adapter to said body and hold the positive electrode extender in said electrically-conducting contacting relation to the positive electrode. 
         [0009]    According to another aspect of the invention, in the adapter for use with a spark plug body and an engine block, the ground electrode extender can: further comprise a remote portion that is spaced apart from the fixed portion and from the ring; and be configured such that a spark gap defined between the positive electrode extender and the ground electrode extender comprises an elongate channel defined between the positive electrode extender and the remote portion of the ground electrode extender, which elongate channel opens axially and away from the body and is substantially unobstructed in the axial direction. 
         [0010]    According to another aspect of the invention, in the adapter for use with a spark plug body and an engine block, the positive electrode extender can comprise a radially extending bar and the ground electrode extender can comprise four elongate electrode portions, each orientated parallel to the positive electrode extender, with two of the elongate portions disposed on each radial side of the bar and spaced with respect to the bar and one another such that the spark gap comprises four parallel channels, the innermost pair of flanking electrode portions defining the remote portion of the ground electrode extender and the outermost pair of flanking electrode portions forming part of the fixed portion. 
         [0011]    According to another aspect of the invention, in the adapter for use with a spark plug body and an engine block, the adapter can further comprise an insulator disposed between and secured to each of: the fixed portion of the ground electrode extender; and the radially extending bar and the remote portion of the ground electrode extender. 
         [0012]    According to another aspect of the invention, in the adapter for use with a spark plug body and an engine block, the radially extending bar can project axially beyond the remote portion of the ground electrode extender. 
         [0013]    According to another aspect of the invention, in the adapter for use with a spark plug body and an engine block, in the ground electrode extender, the remote portion can project axially beyond the fixed portion. 
         [0014]    According to another aspect of the invention, in the adapter for use with a spark plug body and an engine block:
       the fixed portion can be a tube-like extension of the ring;   the remote portion can comprise: an inner ring, disposed about and in spaced relation to the positive electrode extender and orientated coaxially with the longitudinal axis; and an outer ring, disposed about and in spaced relation to the inner ring, orientated coaxially with the longitudinal axis and disposed in spaced relation to the fixed portion; and   the spark gap defined between the positive and ground electrode extenders can comprise (i) an annular channel between the positive electrode extender and the inner ring, which opens axially and away from the body and is substantially unobstructed in the axial direction; (ii) an annular channel between the inner ring and the outer ring, which opens axially and away from the body and is substantially unobstructed in the axial direction; and; (iii) an annular channel between the outer ring and the fixed portion.       
 
         [0018]    According to another aspect of the invention, in the adapter for use with a spark plug body and an engine block, the spark plug body can further comprise an annular insulator disposed between and secured to each of (i) the fixed portion; and (ii) the inner and outer rings, the outer diameter of the insulator being smaller than the outer diameter of the outer ring, to provide said annular channel between the outer ring and the fixed portion. 
         [0019]    According to another aspect of the invention, in the adapter for use with a spark plug body and an engine block, the positive electrode extender can project axially beyond the inner ring. 
         [0020]    According to another aspect of the invention, in the adapter for use with a spark plug body and an engine block, the inner ring can project axially beyond the outer ring. 
         [0021]    An adapter for use with a spark plug and an engine block forms another aspect of the invention. The spark plug is of the type having a spark plug body and an electrode leg. The spark plug body defines a longitudinal axis and has: adjacent one end, a metal ring which is orientated coaxially with the longitudinal axis; a metal tube which is orientated coaxially with the longitudinal axis, extends from the ring towards the other end of the body and is externally-threaded for engagement in a corresponding threaded bore in said engine block in use; an insulator having a portion disposed inside the tube which portion extends axially, from inside the tube, beyond the ring, and has an elongate void extending axially therethrough; and an elongate positive electrode which occupies the void and extends axially beyond the insulator to a terminus which defines the one end of the body. The electrode leg has two arms transversely connected to one another, with one arm extending axially from the ring and beyond the electrode and the other arm extending radially inwardly from the one arm so as to terminate in an end portion that is axially-spaced from the terminus. The adapter is secured, in use, to said body and comprises: a positive electrode extender which, in use, is in electrically-conducting contacting relation to the positive electrode; and a ground electrode extender which, in use, is in electrically-conducting contacting relation to the electrode leg. The adapter is configured such that a spark gap defined between the positive and ground electrode extenders comprises an elongate channel which opens axially away from the body and is substantially unobstructed in the axial direction. 
         [0022]    According to another aspect of the invention, the adapter for use with a spark plug and an engine block can be adapted for snap-fit engagement with said spark plug for use. 
         [0023]    According to another aspect of the invention, in the adapter for use with a spark plug and an engine block, the positive electrode extender can comprise a resilient clip portion, said clip portion being defined by an open loop which has an opening smaller than the diameter of the positive electrode, which loop, for use, is orientated such that its opening presents towards the positive electrode and urged radially between the electrode leg and the positive electrode, to allow the positive electrode to enter the loop and provide for said snap-fit engagement. 
         [0024]    According to another aspect of the invention, in the adapter for use with a spark plug and an engine block, for use, the loop can be urged towards the one arm of the electrode leg. 
         [0025]    According to another aspect of the invention, the adapter for use with a spark plug and an engine block can further comprise a socket portion of the positive electrode extender, said socket portion being defined by a closed loop adapted to receive in tight-fitting electrically-conducting contacting relation, the positive electrode, which loop, for use, is orientated such that its opening presents towards the positive electrode, and urged between the electrode leg and the positive electrode, to widen the space between the positive electrode and the electrode leg and allow the positive electrode to enter the loop, whereupon the electrode leg springs back to provide for said snap-fit engagement. 
         [0026]    According to another aspect of the invention, in the adapter for use with a spark plug and an engine block, for use, the loop can be urged towards the one arm of the electrode leg. 
         [0027]    According to another aspect of the invention, the adapter for use with a spark plug and an engine block can further comprise an insulator disposed between and secured to each of the positive and ground electrode extenders. 
         [0028]    According to another aspect of the invention, in the adapter for use with a spark plug and an engine block, the ground electrode extender can project axially beyond the positive electrode extender. 
         [0029]    According to another aspect of the invention, the insulator can be porcelain. 
         [0030]    A spark plug for use with an engine block forms another aspect of the invention. The spark plug comprises a plug body defining a longitudinal axis. The plug body has: adjacent one end, a metal ring which is orientated coaxially with the longitudinal axis; a metal tube which is orientated coaxially with the longitudinal axis, extends from the ring towards the other end of said body and is externally-threaded for engagement in a corresponding threaded bore in said engine block in use; an insulator having a portion disposed inside the tube, which portion extends axially, from inside the tube, beyond the ring, and has an elongate void extending axially therethrough; a positive electrode having an elongated portion which occupies the void and extends axially beyond the insulator; and a ground electrode coupled to the metal tube. The positive and ground electrodes are configured such that a spark gap defined between the positive and ground electrode extenders comprises an elongate channel which opens axially and away from said body and is substantially unobstructed in the axial direction. 
         [0031]    The invention relates to the production of spark plugs having spark gap geometries characterized by the presence of at least one elongate channel which opens axially and away from the spark plug body and is substantially unobstructed in the axial direction. Other advantages, features and characteristics of the present invention, as well as methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims with reference to the accompanying drawings, the latter being briefly described hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1  is a side elevational view of a spark plug according to the prior art; 
           [0033]      FIG. 2  is a cross-sectional view of the spark plug of  FIG. 1 ; 
           [0034]      FIG. 3  is an enlarged view of encircled area  3  in  FIG. 1 ; 
           [0035]      FIG. 4  is a view, showing an adapter according to one embodiment of the invention disposed above an exemplary spark plug body with which it is deployed in use; 
           [0036]      FIG. 5  is a view of the adapter of  FIG. 4  in use; 
           [0037]      FIG. 6  is a perspective view of the adapter of  FIG. 4 ; 
           [0038]      FIG. 7  is a perspective view of an adapter according to another exemplary embodiment of the invention; 
           [0039]      FIG. 8  is a side elevational view of the adapter of  FIG. 7 ; 
           [0040]      FIG. 9  is a perspective view of an adapter according to another exemplary embodiment of the invention; 
           [0041]      FIG. 10  is a perspective view of an adapter according to another exemplary embodiment of the invention; 
           [0042]      FIG. 11  is a perspective view of an adapter according to another exemplary embodiment of the invention; 
           [0043]      FIG. 12  is a perspective view of an adapter according to another exemplary embodiment of the invention; 
           [0044]      FIG. 13  is a perspective view of an adapter according to another exemplary embodiment of the invention; 
           [0045]      FIG. 14  is a perspective view of an adapter according to another exemplary embodiment of the invention; 
           [0046]      FIG. 15  is a perspective view of an adapter according to another exemplary embodiment of the invention; 
           [0047]      FIG. 16  is a perspective view of an adapter according to another exemplary embodiment of the invention; 
           [0048]      FIG. 17  is a perspective view of a portion of the structure of  FIG. 16 ; 
           [0049]      FIG. 18  is a side elevational view of the structure of  FIG. 17 ; 
           [0050]      FIG. 19  is a plan view of the structure of  FIG. 17 ; 
           [0051]      FIG. 20  is a perspective view of another portion of the structure of  FIG. 16 ; 
           [0052]      FIG. 21  is a plan view of the structure of  FIG. 20 ; 
           [0053]      FIG. 22  is a side elevational view of the structure of  FIG. 20 ; 
           [0054]      FIG. 23  is a perspective view of a yet further portion of the structure of  FIG. 16 ; 
           [0055]      FIG. 24  is a side elevational view of the structure of  FIG. 23 ; 
           [0056]      FIG. 25  is a plan view of the structure of  FIG. 23 ; 
           [0057]      FIG. 26  is a schematic side elevational view of an adapter according to a further embodiment of the invention disposed adjacent an exemplary spark plug with which it is deployed in use; 
           [0058]      FIG. 27  is a view of the structure of  FIG. 26  with the adapter translated radially towards the electrode leg; 
           [0059]      FIG. 28  is a view of the structure of  FIG. 26 , with the adapter disposed in snap-fit engagement with the positive electrode; 
           [0060]      FIG. 29  is a perspective view of a further embodiment of the adapter of the snap-fit type illustrated schematically in  FIG. 26-28 ; 
           [0061]      FIG. 30  is a perspective view of a further embodiment of the adapter of the snap-fit type; 
           [0062]      FIG. 31  is a perspective view of a further embodiment of the adapter of the snap-fit type; 
           [0063]      FIG. 32  is a perspective view of a further embodiment of the adapter of the snap-fit type; 
           [0064]      FIG. 33  is a perspective view of a further embodiment of the adapter of the snap-fit type; 
           [0065]      FIG. 34  is a perspective view of a further embodiment of the adapter of the snap-fit type; 
           [0066]      FIG. 35  is a perspective view of a further embodiment of the adapter of the snap-fit type; 
           [0067]      FIG. 36  is a schematic side elevational view of an adapter according to a further embodiment of the invention disposed adjacent an exemplary spark plug with which it is deployed in use; 
           [0068]      FIG. 37  is a view of the structure of  FIG. 36  with the adapter translated radially towards the electrode leg; 
           [0069]      FIG. 38  is a view of the structure of  FIG. 37  with the adapter translated further radially towards the electrode leg; 
           [0070]      FIG. 39  is a view similar to  FIG. 38  with the adapter tilted slightly to permit the positive electrode to partially enter the closed loop; 
           [0071]      FIG. 40  is a view similar to  FIG. 39 , with the adapter urged radially further towards the electrode leg, and the electrode leg displaced axially; 
           [0072]      FIG. 41  is a view of the structure of  FIG. 40 , with the adapter disposed in socketed engagement with the positive electrode; 
           [0073]      FIG. 42  is a top perspective view of an exemplary adapter of the ring-lock type illustrated schematically in the sequence of  FIGS. 36-41 ; 
           [0074]      FIG. 43  is a top plan view of the adapter of  FIG. 42 ; 
           [0075]      FIG. 44  is a bottom perspective view of the adapter of  FIG. 42 ; 
           [0076]      FIG. 45  is a bottom plan view of the adapter of  FIG. 42 ; 
           [0077]      FIG. 46  is a top perspective view of another exemplary adapter of the ring-lock type; 
           [0078]      FIG. 47  is a top plan view of the adapter of  FIG. 46 ; 
           [0079]      FIG. 48  is a bottom perspective view of the adapter of  FIG. 46 ; 
           [0080]      FIG. 49  is a bottom plan view of the adapter of  FIG. 46 ; 
           [0081]      FIG. 50  is a top perspective view of a further exemplary adapter of the ring-lock type; 
           [0082]      FIG. 51  is a top plan view of the adapter of  FIG. 50 ; 
           [0083]      FIG. 52  is a bottom perspective view of the adapter of  FIG. 50 ; and 
           [0084]      FIG. 53  is a bottom plan view of the adapter of  FIG. 50 . 
       
    
    
     DETAILED DESCRIPTION 
       [0085]    By way of background, a spark plug  100  according to the prior art is illustrated in side elevation in  FIG. 1  and in cut-away in  FIG. 2  and will be seen to include a plug body  102  and an electrode leg  124 . 
         [0086]    The plug body  102  defines a longitudinal axis X-X and has a metal ring  104 , a metal tube  106 , an insulator  108  and an elongate positive electrode  110 . Metal ring  104  is adjacent one end  114  of the plug body  102  and is orientated coaxially with the longitudinal axis X-X. The metal tube  106  is orientated coaxially with the longitudinal axis X-X, extends from the ring  104  towards the other end  112  of said body  102  and is externally-threaded for engagement in a corresponding threaded bore in said engine block in use (not shown). The insulator  108  has a portion  116  disposed inside the tube  106 , which portion  116  extends axially, from inside the tube  106 , beyond the ring  104 , and has an elongate void  118  extending axially therethrough. The positive electrode  110  occupies the void and extends, from a terminal  120  at the other end  112  of the body  102 , axially beyond the insulator  108  to a terminus  122  which defines the one end  114  of said body  102 . The electrode leg  124  has two arms  126 , 128  transversely connected to one another, with one arm  126  extending axially from the ring  104  and beyond the electrode  110  and the other arm  128  extending radially inwardly from the one arm  126  so as to terminate in an end portion  130  that is axially-spaced from the terminus  122 . 
         [0087]    Against this backdrop, a method of producing a spark plug according to an exemplary embodiment of the present invention is hereinafter described. 
         [0088]    In the method, a conventional spark plug body is utilized, as will be evident upon comparison of  FIG. 4 , which shows an initial step in the method, against  FIG. 3 , which shows a view of encircled area  3  in  FIG. 1 . 
         [0089]    The spark plug body  102  utilized in this exemplary embodiment may be obtained by removing the electrode leg from a conventional spark plug, procured, for example, through automotive supply retailers. Alternatively, the spark plug body  102  may, for example, be obtained via a custom order from a spark plug manufacturer. 
         [0090]    Simply put, the electrode in  FIG. 3  is removed from a conventional spark plug. The adapter  20  as shown in  FIG. 4  is then welded to the spark plug body  102 . 
         [0091]    This method simply reduces the cost of constructing the spark plug of this invention. The adapter  20  has a positive electrode extender as shown in  FIGS. 4 and 5 . 
         [0092]    In addition to the spark plug body, the method involves the use of an adapter  20 , such as that shown in  FIGS. 4-6  by way of example. The adapter  20  comprises a positive electrode extender  22  (shown partially in phantom in  FIGS. 4 and 5 ) and a ground electrode extender  36 . 
         [0093]    Once a suitable spark plug body and an adapter have been obtained, the exemplary method comprises the step of securing the adapter  20  to the spark plug body  102 . In the adapter  20  shown in  FIGS. 3-6 , the ground electrode extender  36  comprises a fixed portion  30  that is welded to the ring  104 , to provide for said securement, as shown in  FIG. 5 . 
         [0094]    Once secured, positive electrode extender  22  is in electrically-conducting contacting relation to positive electrode  110  and ground electrode extender  36  is in electrically-conducting contacting relation to the metal ring  104 . 
         [0095]    In the adapter illustrated in  FIGS. 4-6 , the fixed portion  30  is a tube-like extension of the ring  104 , the positive electrode extender  22  is a rod-like extension of the terminus  122  and a remote portion  28  and an insulator  40  are provided as part of the adapter  20 . 
         [0096]    The remote portion  28  is spaced apart from the fixed portion  30  and from ring  104  and takes the form of an inner ring  24  and an outer ring  26 . The inner ring  24  is disposed about and in spaced relation to the positive electrode extender  22  and orientated coaxially with the longitudinal axis X-X. The outer ring  26  is disposed about and in spaced relation to the inner ring  24 , orientated coaxially with the longitudinal axis X-X and disposed in spaced relation to the fixed portion  30 . 
         [0097]    As shown in  FIGS. 4 and 5 , the positive electrode extender  22  projects axially beyond the inner ring  24  and the inner ring  24  projects axially beyond the outer ring  26 . 
         [0098]    The insulator  40  comprises an annular disc portion  34 , through which the positive electrode extender  22  passes and which is disposed between: the fixed portion  30 ; and the inner  24  and outer  26  rings. The outer diameter of annular disc portion  34  is smaller than the outer diameter of the outer ring  26 , to define an annular channel  32  between the outer ring  26  and the fixed portion  30 . As best seen in  FIG. 4 , the insulator  40  further includes a tubular boss portion  38 , which is engaged in snug-fitting relation inside the fixed portion  30 , to secure the annular disc portion  34  to the fixed portion  30 . The inner  24  and outer  26  rings are secured to the insulator  40  in any conventional manner. 
         [0099]    In this arrangement, a spark gap  50  defined between the positive  22  and ground  36  electrode extenders comprises:
       an annular channel  42  between the positive electrode extender  22  and the inner ring  24 , which opens axially and away from the body  102  and is substantially unobstructed in the axial direction;   an annular channel  44  between the inner ring  24  and the outer ring  26 , which opens axially and away from the body  102  and is substantially unobstructed in the axial direction; and   the annular channel  46  defined between the outer ring  26  and the fixed portion  30 .       
 
         [0103]    Another adapter is shown in  FIGS. 7-8 . This adapter is generally similar to the adapter shown in  FIGS. 3-6 , but herein:
       the positive electrode extender  22  comprises a radially-extending bar   the ground electrode extender  36  comprises four elongate electrode portions, each orientated parallel to the positive electrode extender, with two of the elongate portions disposed on each radial side of the bar and spaced with respect to the bar and one another such that the spark gap  50  comprises four parallel channels, the innermost pair of flanking electrode portions defining the remote portion  28  of the ground electrode extender and the outermost pair of flanking electrode portions forming part of fixed portion  30  of the negative electrode extender  36     the insulator  40  is disposed between and secured to each of: the fixed portion of the ground electrode extender; and the radially extending bar and the remote portion of the ground electrode extender   the radially extending bar  22  projects axially beyond the remote portion  28  of the ground electrode extender  36     the remote portion  28  projects axially beyond the fixed portion  30         
 
         [0109]    Seven further embodiments of this adapter are shown in  FIGS. 9-15 , the parts thereof being identified in analogous fashion to the adapters illustrated in  FIGS. 4-8 , but as these adapters are similar in structure and function, further description herein is neither necessary nor provided. 
         [0110]    In another exemplary embodiment, the invention can be carried out with a conventional spark plug, i.e. which includes the electrode leg. An example of an adapter  206  used in this embodiment is illustrated in snap-fit engagement with a conventional spark plug  212  in  FIG. 16  and comprises: a positive electrode extender  200  which, in use, is in electrically-conducting contacting relation to the positive electrode  110 / 122 ; and a ground electrode extender  204  which, in use, is in electrically-conducting contacting relation to the electrode leg  124 . Adapter  206  is again configured, as per the previous embodiments, such that a spark gap  500  defined between the positive  200  and ground  204  electrode extenders comprises an elongate channel which opens axially away from the body and is substantially unobstructed in the axial direction, and in fact, three elongate channels  214 , 216 , 216  are shown in  FIG. 16 , two  216  flanking the other arm  128  of the electrode leg  124  and one  214  disposed opposite the one arm  126 . 
         [0111]      FIGS. 17-25  show the components of the adapter  206  in more detail, and with reference to  FIGS. 23-25 , it will be seen that the positive electrode extender  200  comprises a resilient clip portion  208 , said clip portion being defined by an open loop which has an opening  210  smaller than the diameter of the positive electrode  110 / 122 , which loop  208 , for use, is orientated such that its opening  110  presents towards the positive electrode  110 / 122  and urged radially between the electrode leg  124  and the positive electrode  122 , as shown schematically by the sequence of  FIGS. 26-28 , to allow the positive electrode  110 / 122  to enter the loop  208  and provide for said snap-fit engagement. With further reference to  FIGS. 23-25 , it is notable that the clip portion  208  defines a generally D-shaped opening.  FIGS. 17-19  show the ground electrode extender  204  of this adapter  206 , which is notable for its general “A” shape, and for a square central opening  220 .  FIGS. 20-22  show the insulator disc  202 , which is notable for a circular central spacer portion  202 A, a square plug portion  202 B adapted for insertion, in frictionally-engaged relation, into the square central opening  220  of the ground electrode extender  204  and a D-shaped plug portion  202 C adapted for insertion, in frictionally-engaged relation, into the D-shaped opening defined by clip portion  208 . 
         [0112]    Seven further embodiments of this adapter are shown in  FIGS. 29-35 , the parts thereof being identified in analogous fashion to the adapter illustrated in  FIGS. 16-25 , but as these adapters are similar in structure and function, further description herein is neither necessary nor provided. 
         [0113]    As another alternative utilizing conventional spark plugs, ring-lock type adapters, as hereinafter described, can be provided. In this alternative, the adapter can further comprise a socket portion of the positive electrode extender, said socket portion being defined by a closed loop adapted to receive in tight-fitting electrically-conducting contacting relation, the positive electrode. As shown by the sequence of  FIGS. 36-41 , which schematically show a ring-lock type adapter  300  being positioned for use, the loop  312 , for use, is orientated such that its opening  310  presents towards the positive electrode  122 , and urged between the electrode leg  124  and the positive electrode  122 , to widen the space between the positive electrode  122  and the electrode leg  124  and allow the positive electrode  122  to enter the loop  312 , whereupon the electrode leg  124  springs back to provide for said snap-fit engagement. 
         [0114]      FIGS. 42-53  show three exemplary versions of the ring-lock type adapter  300 , constructed using printed circuit board technologies, with an insulative substrate  310  plated on both sides with conductive material, electrical contact being provided across the substrate via plated through-holes  350 . Each of these versions includes:
       a positive electrode extender  302  of the contemplated type, i.e. including a socket loop  312 , which, in use, is in electrically-conducting contacting relation to the positive electrode  122 ; and   a ground electrode extender  304  which, in use, is in electrically-conducting contacting relation to the electrode leg  124 .       
 
         [0117]    Each of the illustrated positive  302  and ground  304  electrode extenders has portions on both sides of the substrate  310 , connected via plated through-holes  350  as previously mentioned, which portions are configured that a spark gap  500  defined between the positive  302  and ground  304  electrode extenders comprises an elongate channel which opens axially away from the body and is substantially unobstructed in the axial direction. 
         [0118]    In each of the embodiments illustrated herein, the insulator, i.e.  40 / 202 / 310  may comprise porcelain, or other suitable materials, and the positive  22 / 200 / 302  and ground  36 / 204 / 304  electrode extenders may comprise copper, or other conductive materials. 
         [0119]    Testing has been carried out of spark plugs according to the invention. The testing involved the use of a pair of 2007 Chevrolet Silverado Extended Cabs with 4800 Vortec® Engines. Modifications were made to the vehicle fuel tanks, to permit to permit the tanks to be easily drained; otherwise, the vehicles were utilized in “stock” condition (but for the spark plugs of the present invention, as indicated in the table.) In each test, the vehicles were filled with fuel and driven along a controlled access highway along a common route, with cruise-control locked at 100 km/hr. At the completion of the run, the tanks were refilled; the amount of fuel that was required to be added to refill the tank equates to the amount of fuel consumed during the test. 
         [0120]    The test results are reproduced below: 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                   
                   
                 Spark Plug 
                 Fuel starting 
                 Fuel ending 
                 Distance 
               
               
                 Run 
                 Vehicle 
                 Utilized 
                 Volume (l) 
                 volume (l) 
                 driven (km) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 Test 
                 FIG. 4-6 
                 Full 
                 13.5 
                 98 
               
               
                 2 
                 Control 
                 Stock 
                 Full 
                 15.1 
                 98 
               
               
                 3 
                 Test 
                 FIGS. 50-53 
                 Full 
                 13.4 
                 103 
               
               
                 4 
                 Control 
                 Stock 
                 Full 
                 15.2 
                 103 
               
               
                 5 
                 Test 
                 FIGS. 42-45 
                 Full 
                 13.5 
                 98 
               
               
                 6 
                 Control 
                 Stock 
                 Full 
                 14.97 
                 98 
               
               
                 7 
                 Test 
                 FIGS. 7-8 
                 Full 
                 12.3 
                 99.5 
               
               
                 8 
                 Control 
                 Stock 
                 Full 
                 14.5 
                 99.5 
               
               
                 9 
                 Test 
                 FIGS. 16-23 
                 Full 
                 11.7 
                 99 
               
               
                 10 
                 Control 
                 Stock 
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         [0121]    As evident from the test results, spark plugs according to the invention can have advantageous impacts on fuel mileage. Without intending to be bound by theory, it is believed that this advantage may flow from the presence of spark gap geometries characterized by the presence of at least one elongate channel which opens axially and away from the spark plug body and is substantially unobstructed in the axial direction, in contradistinction, for example, to conventional spark plugs as illustrated in  FIGS. 1-2 , wherein the spark gap opens radially, and in the axial direction, is substantially entirely obstructed by the electrode leg. Again, without intending to be bound by theory, it is believed that the spark gap geometries of the plugs according to the invention control the potential distribution between the anode and the cathode, and hence the spatial distribution of the field, leading to: a more uniform and radial energy distribution in the discharge; relatively low quenching, and thus a higher local field gradient in the discharge region; and an engineered field profile that provides for a more distributed discharge profile, suitable for coupling to a larger volume of combustion gas, all in comparison to the prior art spark plugs. 
         [0122]    Whereas twenty-one exemplary embodiments of the invention are herein illustrated and described, of three general types, it will be evident that modifications can be made, both in terms of shape/geometry, size and manner of connection. Accordingly, it should be understood that the invention is to be limited only by the accompanying claims, purposively construed.