US 3867001 A
A spark plug adapter having two terminal ends interconnected by an electrical conductor; one terminal end contained in a socket slidably connectible to a spark plug terminal means and the other terminal end similarly connectible to a conventional ignition-wire socket-type terminal providing an ignition-wire connection laterally displaced from the axis of the spark plug resulting in a reduction in the over-all axial height of the spark plug and its electrical connection (in combination).
Claims available in
Description (OCR text may contain errors)
United States Patent Hedman 1 Feb. 18, 1975 SPARK PLUG ADAPTER AND METHOD OF MAKING Inventor: Robert W. Hedman, 11260 Overland Ave., No. 26C, Culver City, Calif. 90230 Filed: Dec. 26, 1973 Appl. No.: 427,933
US. Cl. 339/26, 339/149 S, 339/218 S Int. Cl H0lr 13/50 Field of Search 339/10, 26, 27, 149, 153, 339/200, 204, 212, 213, 218, 217 SP, 220 A, 223 S, 255 B, 256 C, 258 C, 263 S References Cited UNITED STATES PATENTS Barmore 339/149 S X Strahan 339/213 T Rabezzana 339/26 X Elliott 339/2l8 S UX FOREIGN PATENTS OR APPLICATIONS 167,659 8/1921 Great Britain 339/26 117,541 9/1943 Australia 339/26 Primary Examiner-Roy D. Frazier Assistant Examiner-Lawrence J. Staab Attorney, Agent, or FirmHarris, Kern, Wallen & Tinsley  ABSTRACT A spark plug adapter having two terminal ends interconnected by an electrical conductor; one terminal end contained in a socket slidably connectible to a spark plug terminal means and the other terminal end similarly connectible to a conventional ignition-wire socket-type terminal providing an ignition-wire connection laterally displaced from the axis of the spark plug resulting in a reduction in the over-all axial height of the spark plug and its electrical connection (in combination).
2 Claims, 6 Drawing Figures SPARK PLUG ADAPTER AND METHOD OF MAKING BACKGROUND OF THE INVENTION My invention relates to electrical terminal adapters and, more particularly, to a spark plug ignition-wire adapter for connecting ignition wire to a spark plug terminal of an internal combustion engine.
In general, the electrical connection to a sprak plug of most of todays automobile engines involves the use of an axially slidable terminal attached to an ignition wire which slides and snaps into place over the electrical terminal of the spark plug. The ignition-wire terminal typically takes the form of a tubular member adapted to make electrical connection with the conductor of the ignition wire and sized to receive the spark plug terminal. Often, the tubular member carries a hood of a resilient insulating material having a first opening for receiving therethrough the ignition wire and a second opening sized to fit over the spark plug terminal and at least a portion of a coaxial spark plug electrode insulator. Thus, when such an ignition-wire terminal is in place it not only provides electrical connection between the ignition wire and spark plug terminal but also electrically insulates the connection. The hood extension over the electrical insulator additionally serves to seal the electrical connection from the entry of oily grime and moisture, and further, assists in mechanically maintaining the electrical connection.
Today, in the field of ignition-wire terminals, a prin cipal difference between terminals and requiring careful consideration when making a selection, relates to the angular relationship of the previously mentioned openings in the hood. The hood and its openings determine the angularity of the approach of the ignition wire to the longitudinal axis of the spark plug. In general, some ignition-wire terminals provide for an ignition wire approach in axial alignment with the spark plug; others provide an approach of about 45 from axial alignment; and, still others provide for a wire approach intersecting the spark plug axis at 90.
While the variation in wire terminals and their approach angles olt'er selectivity to best accommodate a particular engine, all of the wire terminals add significantly to the overall height ofthat portion of the spark plug extending outwardly from the engine.
In many engine configurations the exhaust manifolding is located in near proximity of the spark plug terminal. The addition of the wire terminal to the spark plug places the aforementioned hood and approaching ignition wire in even nearer proximity of the manifolding. The inherently high termperature of an engine exhaust manifold serves to heat the surrounding air, the ignition wire, and ignition-wire terminal. The intensity of the heat transferred to the ignition wire and its terminal is, of course, proportional to their clearance distances from the hot manifold and directly affects the serviceable life ofthe ignition wire and its terminal. Typically, the intense maniford heat leads to a hardening, cracking, and breaking away of the insulation which in turn allows the high-voltage electrical ignition pulse to be short circuitctl through the broken insulation to the electrically conductive nearby engine parts including the exhaust maniford itself. The short circuit, of course, renders the spark ignit on circuit and spark plug inoperative. The susceptibility to shorting out becomes even more pronounced as oily grime and moisture fill the voids in the insulation. In order to maintain efficient engine operation periodic and costly replacement of the spark ignition wire is required.
Breakdown and failure of ignition wire and wire terminals is especially rapid in many overhead valve automotive engines. Overhead valve engines necessarily require close spacing between the valves, valve ports. passageways, and between associated exhaust manifolding and spark plugs. The routing of ignition wire to the spark plugs of such an engine usually includes brackets and wire clips to prevent the ignition wire from contacting the exhaust manifold. The maintenance of wire clearance is of a particular problem on overhead valve V-type engines where the exhaust manifolding attaches to a near uppermost area of the cylinder head and extends therefrom outwardly and downwardly along the side of the engine. In many such designs the spark plug is located at a lower point along the side of the cylinder head which means the exhaust manifolding must curve outwardly to give clearance to the spark plugs. Since the opposite terminal end of the ignition wire is typically on the top side of the engine, the ignition wire must necessarily pass over or around the various exhaust conduits connecting and merging the individual exhaust port openings in the cylinder head into a single manifold exit opening. In engins having this configuration the connection of the ignitionwire terminal to the spark plug further reduces the wire clearance relative to the exhaust manifold to a magnitude where the terminal hood is in near contact with the manifold since it adds appreciably to the over-all height of the spark plug. In such a configuration, of course, the straight-on or axially coincident ignition wire, ignition-wire terminal and spark plug type of connection is impossible. The 45 and wire terminals must be used but because of their close proximity to a source of intense heat they may rapidly deteriorate as in the aforementioned manner.
I have also found that the extended spark plug height often adds to the ungainliness of routing ignition wires to spark plugs and in making the connection because of the plethora of equipments mounted on a modern day automotive passenger car engine or in close proximity within the engine compartment of the vehicle. This crowded condition reduces accessibility to the spark plugs and in many cases makes removal and replacement of even the spark plug ignition-wire terminal, for engine test and diagnostic purposes, cumbersome and in some instances virtually impossible without the temporary removal and replacement of some unrelated component. This ungainliness is related with having to axially displace the ignition wire along the axis of the spark plug and to gain sufficient leverage on the terminal where clearance is minimal. This condition is further aggravated because many engine tests must be made on an engine heated to operating temperature; in which case, the exhaust maniford is extremely hot and can cause severe burns to the automotive technician performing the test.
THE INVENTION GENERALLY In view of the foregoing problems, it is an object of my invention to provide a spark plug adapter which may be attached to a spark plug in the same manner as a typical ignition-wire terminal without adding appreciably to the over-all height ofthe spark plug and terminal connection (in combination).
Another object of my invention is to provide an adapter of the foregoing character which will accommodate the connection of the typical ignition-wire hooded terminal without alteration; and further, provide that the connection be laterally displaced from the longitudinal axis of the spark plug.
A further object of my present invention is to provide an adapter of the foregoing character which is durable, inexpensively produced, and which provides a simple and reliable interconnection between a spark plug and its associated ignition wire.
The foregoing objects and features of the present invention may be more clearly understood by reference to the following detailed description when considered with the drawing which, by way of example only, illustrates one form of a spark plug adapter embodying the features of my invention.
THE DRAWING In the drawing:
FIG. 1 is a pictorial view of a portion of a V-type overhead-valve engine illustrating my spark plug adapter attached to a spark plug;
FIG. 2 is a cross-sectional side view of my spark plug adapter illustrating in detail its attachment to a spark plug and an ignition-wire terminal;
FIG. 3 is a cross-sectional view taken along the line 3-3 of FIG. 2;
FIG. 4 is a cross-sectional view taken along the line 4-4 of FIG. 2;
FIG. 5 is a cross-sectional view taken along the line 5-5 of FIG. 2; and
FIG. 6 is a perspective view of the electrical conductor of my spark plug adapter.
DISCLOSURE OF THE INVENTION Referring to the drawing, the spark plug adapter 10 of my present invention is designed for slidable engagement over a terminal means 12 of a typical spark plug 14 and for snapping into place thereon; and further, for slidable engagement with an ignition-wire terminal 16 and retention thereof with a generally similar snap-type of connection. Electrical continuity through the adapter 10 is provided by an elongated electrical conductor 18, best shown in FIG. 6. One end of conductor 18 terminates in a generally tubular end 20 for making electrical contact with the cylindrical terminal means 12 of the spark plug. The other end of conductor 18 terminates in a generally tubular end 22 for making electrical contact with the cylindrical ignition-wire terminal 16. The conductor 18 and its end 20 are encased in insulation 24 formed as a unitary structure contributing to the over-all shape and dimension of the adapter.
A socket 26 formed in the insulation 24 contains the conductor end 20 and comprises two axially aligned chambers 28 and 30 which are generally cylindrical. Chamber 30 is sized to receive a portion of the spark plug electrode insulator 32. Chamber 28 includes the end 20 and is sized to receive the spark plug terminal means 12.
A generally cylindrical portion 34 of the unitary insulation 24 covers the conductor 18 and extends into a generally cylindrical cavity 36 within the end 22 of the conductor thereby giving the conductor 18 and the end 22 unitary structural rigidity. The outer surface of the end 22 is exposed for making slidable electrical contact with a suitably sized socket within an ignition-wire terminal l6.
It is to be noted that the insulation 24 be of only sufficient thickness over an extremity ofthe end 20 to maintain its integrity and resistance to fracture. A minimum thickness of insulation over the end 20 forms an end wall of chamber 28, and minimizes the combined height of the spark plug 14 and adapter 10 thereby minimizing the intrusion into the axial clearance space around the spark plug with the adapter 10 installed. It is to be further noted that an axis of the generally cylindrical portion 34 intersects the axis of the socket 26 at a point, between the base 38 and the end 20 and the socket opening. Accordingly, with the adapter installed it effectively minimizes the intrusion into the clearance space around the terminal means of a spark plug normally occupied by an ignition-wire terminal such as terminal 16.
The conductor 18 including the end terminals 20 and 22, forms a continuous structure which is clearly shown in FIG. 6. FIG. 4 shows a typical cross section of the conductor 18 at a point between its terminal ends which is generally rectangular and has a thickness corresponding to a standardized sheet metal thickness or gauge. Terminal end 20 is tubular having an over-all height generally corresponding to the height of the terminal means 12, as shown in FIG. 2, and an inside diameter for producing a snug fit with the terminal means 12. The wall of the terminal end 20 does not form a continuous periphery but may be broken by a longitudinal gap 40.
The outer wall surface of the terminal end 20 includes an annular groove 42 of semicircular cross section and a mutually conforming annular ridge of the inner wall surface for engaging a corresponding groove formed in the spark plug terminal means 12 as shown in FIG. 2. A slidable engagement of the terminal end 20 over the spark plug terminal means 12 is thus provided with a snap-in-place means for retaining the connection.
Terminal end 22 is also tubular having an over-all height and outside diameter generally of the same dimensions as the spark plug terminal means 12. The wall of terminal end 22 has an annular groove 44 which receives a mating spring-like protrusion 46, formed in the end of the conductor of the ignition-wire terminal 16 to provide a snap-in-place, sliding engagement with the wire terminal. The bent wire protrusion 46 is only typical of many ignition-wire terminals in widespread use today. Many variations thereof are know for similarly making and maintaining the connection.
The conductor 18 and terminal ends 20 and 22 may be fored from a continuous sheet of conductive material. Preferably, the material may be a steel alloy inherently responsive to die shearing and forming and having a spring-like resilience and surface hardness to accommodate repeated installations and removals while retaining the snap action of slidable engagement.
Turning now to the socket means 26 as shown in FIG. 2 and to the chamber 28 including first end 20, it will be noted that a lower edge of the tubular end 20 bears against a shoulder 48 of the spark plug terminal 12 thereby providing a positive means for limiting the axial engagement of the end 20 and the terminal means 12. An end 50 of the chamber 28 is simply formed by the insulation 24.
Chamber 30, defined by the larger diameter portion of the socket means 26, is adjacent to chamber 28 and in axial alignment with the tubular end 20. While generally cylindrical, chamber 30 includes four uniformly spaced apart ridges 52 extending laterally inwardly from and along the chamber side walls, as shown in FIGS. 2 and 5. The diametrical spacing between opposing ridges is the same for each pair and may be only slightly greater than the diameter of the enclosed region of the electrode insulator 32. The exact diameter is dependent upon the elasticity of the insulation 24. When using rigid insulation material, of course, some minimum clearance spacing must be provided. A closely fitting rigid insulation material may be used for effective sealing against the entry of dirt and oily grime and is desirable for adding structural rigidity to the adapter.
The cylindrical portion 34 of the insulation 24 formed around conductor 18 is of an over-all size and shape typical of a spark plug electrode insulator 32 as shown. Portion 34 of my adapter includes a plurality of spaced apart annular ridges 54 simulating the insulator design typical of many spark plugs available today. Other spark plugs, such as 14, are also readily available and are formed without a series of ridges as shown on my adapter. Each ridge 54 includes a sloping portion 56 and a portion 58 as shown in FIG. 2 forming an annular edge 60 having a directional quality to engage and resist removal of a somewhat resilient hood 62 shown as a part of the ignition-wire terminal 16. Such gripping action, of course, inherently serves to seal the electrical connection within the ignition-wire terminal 16 from the entry and accumulation of dirt and grime.
The unitary structure of the insulation 24 fills the tubular end 22 thereby adding to its strength to resist bending and misalignment with the larger cylindrical portion 34. This is best shown in FIG. 3.
From the foregoing detailed description, it is to be understood that the spark plug adapter of my present invention is a simple, effective, and dependable structure for attaching ignition-wire terminals to spark plugs without adding appreciably to the over-all axial height of the spark plug and its electrical connection. My adapter additionally provides electrical connection to a spark plug without appreciably reducing the lateral clearance space immediately surrounding the spark plug terminal means. The adapter of my present invention can be easily installed on a spark plug and connected to an ignition-wire terminal without requiring modification of change over to a unique type of ignition-wire terminal. It is to be further understood that the adapter of my present invention provides flexibility in the routing of ignition wires to engine spark plugs for insuring greater clearance of the ignition wire and ignition-wire terminal relative to the proximity of hot exhaust manifolds.
While a particular form of spark plug adapter is descripbed in some detail herein, it is appreciated that changes and modifications may be made in the illustrated form without departing from the principal spirit of the invention. Accordingly, it is intended I be afforded the full scope of the following claims.
1. In a spark plug ignition-wire adapter, the combination of:
an integral body member formed of a nonconductive, elastomeric material, having a socket portion having an axis and having a socket adapted to fit over an exposed terminal of a spark plug, and having a connector portion having an axis and extending at an angle from said socket portion;
a conductor formed of electrically conductive material, embedded in said body member, and having a first end extending into said socket for electrical engagement with such a terminal, and having a second end extending out of said body member for electrical engagement with an ignition wire connector;
the axis of said connector portion being substantially perpendicular to the axis of said socket portion and said axes intersecting about midway between the ends of said socket portion; and
said first end of said conductor being generally tubular in form to receive in frictional engagement the exposed terminal of a spark plug, and said connector portion having an outer end provided with an integral concentric boss extending therefrom around which said second end of said conductor substantially extends for frictional engagement with an ignition wire connector, said second end of said conductor also being generally tubular in form.
2. An adapter as defined in claim 1 in which said connector portion and said socket portion are generally cylindrical in form, except at the area of their intersection.