Abstract:
A tool for determining the continuity of an electrical circuit for an internal combustion engine includes a single body member with male connectors projecting from the opposite ends and a lead wire having a 90° connection boot at one end and an inline connection boot at the opposite end is useful for attachment to the heads of spark plugs regardless of their orientation in an engine block.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    In a principal aspect, the present invention relates to an apparatus for determining whether the spark plug of an internal combustion engine is properly generating an ignition spark or electrical discharge so as to ignite vaporized fuel.  
           [0002]    When servicing an internal combustion engine, a mechanic often finds it necessary to determine whether the spark plugs for the engine are providing an appropriate electrical discharge or spark in each of the cylinders of the engine. A determination of ignition spark enables the mechanic to diagnose whether engine operation is defective due to a faulty ignition system or alternatively, due to a faulty fuel delivery system. That is, by determining whether appropriate electrical charge or spark is delivered via the spark plug of the internal combustion engine, the mechanic quickly and easily determines that the ignition system is working properly. Thus, if the spark is generated, then there may be a defect associated with the fuel delivery system. Alternatively, if there is no spark, then the ignition system is not working properly.  
           [0003]    There are at least two devices known which are used to check the viability of the ignition system. These devices are made available by S&amp;G Tool Aid Corporation of Newark, N.J. Their product numbers are No. 23900 and No. 23920 and are depicted in FIGS. 1 and 2, respectively. Product No. 23900 is identified as an inline ignition spark checker and includes a male contact or probe connected in a circuit with a light indicator. The male probe projects from one end of the device. An inline boot or lead wire for connection to the head of a spark plug is provided at the opposite end of the device. Product No. 23920 is an alternative construction wherein the boot or lead wire is a 90° boot designed for use in situations where the inline boot will not be useful or workable. Thus, in order to check the spark at each and every cylinder of a multi-cylinder internal combustion engine, it may be necessary to use both tools, depending upon the orientation and position of the spark plug in the engine block. A mechanic may necessarily need to switch back and forth between tools in order to check the ignition system associated with each of the cylinders of an internal combustion engine. Such switching back and forth, as well as the cost of two tools to perform the same function, has inspired the development of the present invention.  
         SUMMARY OF THE INVENTION  
         [0004]    Briefly, the present invention comprises an apparatus or mechanic&#39;s tool for evaluating the ignition system, and more particularly, the delivery of electrical current via the ignition system to a spark plug of an internal combustion engine. The tool has universal application in that the tool utilizes either an inline boot for connection to the head of the spark plug or an angled, i.e. 90° boot, depending upon the requisite need and accessibility of the spark plug associated with the internal combustion engine that is being serviced.  
           [0005]    Thus, the tool includes a lead wire having an inline female boot at one end and a 90° connection boot at its opposite end. The tool further includes a generally cylindrical body member with male connectors screw-threaded to each end of the body member. Internally, the body member is hollow and includes an indicator light in series with the male connectors projecting from the opposite ends of the body member into the hollow cylindrical body member. A spring inside the body member is interposed between the light and the male connectors to insure electrical continuity for the device. A lead wire boot may be connected to either of the male connectors projecting from the body member and may also be connected at either end to the head of a spark plug. Thus, the single tool disclosed may be utilized for inline or angle connection of the tool to the head of a spark plug and thereby provide a continuity check of the ignition system.  
           [0006]    Thus, it is an object of the invention to provide an improved ignition system diagnostic tool.  
           [0007]    It is a further object of the invention to provide an ignition system diagnostic tool which may be utilized for checking an electrical spark via a spark plug in an ignition system regardless of the orientation or position of the head of the spark plug in the engine block.  
           [0008]    It is a further object of the present invention to provide a diagnostic tool for ignition systems which is inexpensive, rugged, easy to use, has broad application for various types of engines and spark plugs associated with such engines, and which is lightweight and inexpensive.  
           [0009]    These and other objects, advantages and features of the invention will be set forth in the detailed description as follows.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0010]    In the detailed description which follows, reference will be made to the drawing comprised of the following figures:  
         [0011]    [0011]FIG. 1 is an isometric view of a prior art tool having a linear or straight line connection boot;  
         [0012]    [0012]FIG. 2 is an isometric view of a second prior art tool having a  90 ° or right angle connection boot;  
         [0013]    [0013]FIG. 3 is a plan view of the diagnostic tool of the invention;  
         [0014]    [0014]FIG. 4 is an isometric view of the tool of FIG. 3 in a first configuration;  
         [0015]    [0015]FIG. 4A is an isometric view of the tool of FIG. 3 in an alternative configuration;  
         [0016]    [0016]FIG. 5 is an exploded isometric view of the tool of FIG. 3;  
         [0017]    [0017]FIG. 6A is an isometric view illustrating the manner of use of the tool of FIG. 3; and  
         [0018]    [0018]FIG. 6B is an isometric view illustrating the manner of use of the tool of FIG. 3 in an alternative configuration.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0019]    Referring to FIGS.  2 - 6 B, the ignition diagnostic tool includes a generally hollow, translucent or transparent cylindrical body member  10  with a cylindrical passage  12  of uniform diameter therethrough. Passage  12  includes a first threaded connection mechanism or internal threads  14  at one end and a second threaded connection mechanism or internal threads  16  at its opposite end. A first cap member  18  includes a projecting, conductive male rod  20 . The cap  18  is molded from an insulating plastic material and includes a threaded annular ring or rib  22  which engages with the threaded connection or threads  14  of the body member  10  so as to tightly hold the cap  18  in position. The rod  20  is a conductive rod and is sized and shaped so as to cooperate with a spark plug ignition system boot. The rod  20  fits through the cap  18  and includes a contact pad or surface  24  positioned on the inside of the hollow body member  10 .  
         [0020]    A second cap  28  also includes a conductive rod  30  molded in the generally insulating material, second cap  28 . The first rod  20  and second rod  30  are axially aligned one with the other and with a centerline axis  54  of the body member  10 . The cap  28  also includes an annular ring member or rib  32  which is threaded and cooperative with the internal threads  16  of the body member  10 . Rod  30  further includes an internal contact or pad  34  and, in addition, includes a spiral wound, conductive spring  36  either attached to the pad  34  or engaged against the pad  34 .  
         [0021]    A generally cylindrical bulb  40  includes frusto-conical metal end caps  42  and  44  which are also cylindrical and axially aligned to provide contact with the spring  36  and connection pad  24 , respectively. The bulb  40  further includes a neon glow lamp  46  having lead wires  48  and  50  extending into the glow lamp  46 . A resistor  52  is provided in the circuit connected with the glow lamp  46  through the lead  50 .  
         [0022]    The body member  10 , in combination with the cap members or caps  18  and  28 , provides a generally symmetrical device having conductive rods  20  and  30  projecting outwardly from the opposite ends thereof with the entire device being axially and symmetrically arranged along the axis  54 . The body member  10  is cylindrical so that it may be easily, manually grasped and manipulated.  
         [0023]    As a further important part of the combination comprising the apparatus, there is included a spark plug wire  60  which comprises an insulated wire connected with a first inline female boot member  62  and a second 90° angle boot member  64 . The boot members  62 ,  64  are attached to the opposite ends of the wire  60 . Each boot member  62 ,  64  is connectable to either one of the conductive rods  20  and  30 .  
         [0024]    In practice, referring to FIGS. 6A and 6B, the wire  60 , and more particularly, one of the boot members  62  or  64 , may be engaged with the head  70  of a spark plug  72  in an engine block  74 . The choice of the particular boot member  62  or  64  which will be utilized depends upon the orientation and position of the plug  72  and, more particularly, the head  70  thereof. In any event, the head  70  is connected electrically with the boot  62 ,  64  of choice. The opposite or remaining boot  62  or  64  is then connected to the rod  20  or  30  as the case may be. The remaining rod,  20  or  30 , as the case may be, is connected to the boot  80  associated with the lead wire  82  that generally connects with the head  70  of the plug  72 . Turning the ignition of the vehicle engine will then theoretically provide for electric current through the ignition system. If current is, in fact, being delivered, it will register via lighting of the bulb  46 . If there is no ignition detection, then there is a fault with the ignition system, at least for that particular plug to the engine. If the ignition system does properly work, then failure of the particular cylinder to be operable is in all likelihood associated with the fuel delivery system.  
         [0025]    With the tool of the invention, it is thus possible by virtue of utilizing a single tool to check each and every spark plug utilizing either the boot  62  or the boot  64  to connect to the plug depending upon the orientation and location of the plug. A separate tool is not needed. This results because the boots  62  and  64  are universally engageable with the rods  20  or  30 , as well as the spark plug heads. A single tool can, therefore, be utilized in place of what previously would require two separate tools.  
         [0026]    Various modifications and changes may be made to the described tool. For example, the shape and configuration of the body  10  may be altered. The indicator of electrical continuity may be altered and, for example, a light emitting dial or some other indicator device may be used. The particular arrangement of the mechanism for maintaining the elements within the hollow body may also be altered. That is, multiple springs may be utilized, or the springs may be eliminated, provided there is appropriate electrical continuity. Thus, the invention is to be limited only by the following claims and equivalents thereof.