US3828246A

US3828246A - Spark tester

Info

Publication number: US3828246A
Application number: US00386989A
Authority: US
Inventors: C Maynard
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-08-09
Filing date: 1973-08-09
Publication date: 1974-08-06
Anticipated expiration: 1991-08-06

Abstract

A spark tester having a base plate of insulating material. A central post carries a sharp edged disc electrode. Clamps surround the post and carry needle-pointed radially extending electrodes. Fasteners for the post and clamps extend into upright sockets in the base plate. Transverse bores intersect the upright sockets. Fasteners for the clamps engage cable conductors in associated transverse bores with cable insulation extending into the transverse bores. A ground wire extends into the transverse bore associated with the post to ground the disc electrode.

Description

[4 Aug. 6, 1974 United States Patent [191 Maynard Primary Examiner-Michael J. Lynch Agent, or Firm-James W. Pearce; Roy F.

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UNITED STATES PATENTS ductors in associated transverse bores with cable insu- 324/l8 lation extending into the transverse bores. A ground 324/18 wire extends into the transverse bore associated with 324/18 the post .to ground the disc electrode. 324/18- 6 Claims, 5 Drawing Figures 1,316,560 9/1919 1,526,897 2/1925 Boselli 1,605 863 11/1926 Stem 2,005,992 6/1935 Heaton PATENIEDAUE 61914 3.828.24

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SHEET 2 OF 2 SPARK TESTER This invention relates to spark testers employed in determining the quality of the spark delivered by a high voltage ignition system such as that used on late model outboard engines or other reciprocating engine and ignition system combinations.

An object of this invention is to provide a spark tester capable of testing the electrical discharge power to all cylinders of a reciprocating engine simultaneously.

Another object of this invention is to provide such a spark tester in which there are insulated current paths, insulated joints, and insulated connectors that shield the high voltage of the ignition system from arcing or discharging at random places along the spark tester.

Briefly, this invention provides a spark tester having a plate-like insulative base at the center of which is mounted a post which carries a disc-shaped sharp edged electrode. The post is hollow and is held in place by a fastener which extends into the base and into an elongated bore which extends from one side of the base parallel to and spaced between faces thereof. An insulated ground lead extends into the elongated bore and is provided with an enlarged head which is engaged by the fastener to connect the ground lead to the discshaped sharp edged electrode. A plurality of spaced electrode holders are mounted on the base surrounding the disc-shaped electrode. Each of the electrode holders carries a needle type electrode extending radially of the disc-shaped electrode with the point of each needle electrode spaced an adjustable distance from the sharp edge of the disc electrode. Each of the electrode holders is supported by a fastener which extends into the base and into a bore which extends from a side of the base parallel to and spaced between the faces of the base. Test cables extend into the last mentioned bores and are connected to the electrode holders by the fasteners associated therewith. Opposite ends of the test cables are attached to spark plug cables of a motor to be tested.

The above and other objects and features of the invention will be apparent to those skilled in the art to which this invention pertains from the following detailed description and the drawings in which:

FIG. 1 is a plan view of a spark tester constructed'in accordance with an embodiment of this invention in association with a fragmentary portion of an internal combustion engine of marine type; I

FIG. 2 is a sectional view taken on the line 2-2 in FIG. 1;

FIG. 3 is a sectional view taken on the line 3-3 of FIG. 1;

FIG. 4 is a sectional view taken on the line 4-4 in FIG. 1; and

FIG. 5 is a view partly in side elevation and partly in section of the connection between a spark plug lead cable and a test cable.

In the following detailed description and the drawings, like reference characters indicate like parts.

FIG. 1 shows a spark tester which is constructed in accordance with an embodiment of this invention. The tester 10 includes a plastic insulating plate-like base 11 containing an upright threaded hole or socket 12 (FIG. 2) which intersects an elongated hole or bore 13. The hole 13 is parallel to and spaced between an upper face 131 and to a lower face 132 of the base 11 and extends inwardly from a side face 133 of the base 11. An end portion of a ground cable 14 extends into the elongated hole 13. External insulation'141 of the ground cable 14 is of approximately the same diameter as the hole 13 and extends into the hole 13 to adjacent the upright hole 12. A conductor 142 of the cable 14 extends inwardly of the inner end of the insulation 141. A soft metal plug 15 of solder metal or the like is mounted on the inner end'portion of the conductor 142. The plug 15 isengaged by an upright screw 16 that is threaded into hole 12 to provide a good electrical contact between the screw 16 and the conductor 142. The hole or bore 13 is large enough in diameter to accept the plug 15 and the cable 14 with its insulation intact. This method of attachment provides a well insulated junction between the screw 16 and the conductor 142 of the cable 14. The other end of the conductor 142 of the cable 14 is fitted with an alligator clamp 40 (FIG. 1) for attachment to some appropriate zero potential reference, such as an engine block 17 of an engine 171, as shown in FIG. 1. The screw 16 (FIG. 2) holds in place a tubular spacer or thimble 18, which forms a post on which a sharp edged annular electrode disc 19 is mounted. The disc 19 is disposed parallel to and spaced from the upper face 131 of the base 11.

In FIGS. 1-3 are shown needle-point electrode rods 20. The electrode rods are held adjustably and slidably by electrically conducting spring clamps 21. The electrode rods are disposed around the disc 19 in a radial orientation to form adjustable spark gaps 22 between the rods 20 and the sharp edge disc 19.

The spring clamps 21, which hold the electrodes 20, are held in place on the base 11 by screws 23,'as shown in FIG. 3. The screws 23 are threaded into upright holes or sockets 24. Each of the holes 24 communicates with one of a plurality of holesor bores 25 in the base 11 which receive end portions of spark plug connector test cables 26. Details of construction of one of the holes 25 and associated members are shown in FIG. 4. The hole 25 extends inwardly from a side face 261 of the base 11 and is intersected by the hole 24. A soft metal plug 27of solder metal is mounted on an inner end portion of a conductor 262 of the cable 26. Insulation 28 of the cable 26 continues uninterrupted up to the plug 27. The insulation 28 continues into the associated hole 25 to form a well insulated connection for the cable 26 and the screw 23. As shown, the diameters of the insulation 28 and of the plug 27 are substantially equal to the diameter of the hole 25. The screw fastener 23 engages and firmly grips the plug 27 to provide a good electrical connection between the conductor 262 and the clamp 21 and through the clamp 21 to the associated electrode rod 20 (FIGS. 1 and 3). Referring to FIG. 1, the free end of each of the test cables 26 plugs into one of a plurality of spark plug caps 29 that have been removed from their respective spark plugs 291. FIG. 5 shows the internal arrangement of one of the spark plug caps 29 and associated members. The spark plug cap 29 includes a spring coil 30 and an arm 31 that pierces insulation 32 of a spark plug cable 33 to provide an insulated current path between a cable wire 34 and the coil 30. An insulator cap 35 is formed around the coil 30 and the cable 33. The free end of the conductor 262 of the cable 26 is fitted with a soft metal plug 36 of solder metal or the like, of a diameter to be received and resiliently gripped by the spring coil 30. Insulation 28 of the cable 26 continues uninterrupted up to said plug 36. The intersection of the plug 36 and the insulation 28 is covered and insulated by a sleeve 37 of insulating material which is resiliently elastic such as rubber or other rubber-like material. When the plug 36 is snugly pushed into the coil 30, the sleeve 37 continues into the plug cover 35 to form a well insulated current path.

The spark plugs 291 can be left in the engine block 17 so that a test of all cylinders can be made simultaneously as a starter (not shown) turns the engine 171 to provide starting RPM and cylinder pressure. The spacing between the needle-points of the electrode rods and the sharp edge of the electrode disc 19 can be set at the distance to define a spark of the strength required for proper operation of the engine 171, and as the engine is turned on, the spark available at all spark plugs can be viewed during a single test.

The spark tester constructionillustrated in the drawings and described above is subject to structural modification without departing from the spirit and scope of the appended claims.

Having described my invention, what I claim as new and desire to secure by letters patent is:

1. A spark tester for an engine which comprises a base plate of insulating material, a post mounted on one face of the base plate spaced from sides thereof, a sharp edged disc electrode mounted on the post, a plurality of clamps mounted on said face spaced from the post, a fastener of conductive material holding the disc electrode and the post on the base plate and extending into an upright central socket in the base plate, a fastener of conductive material holding each of the clamps on the base plate and extending into an upright outer socket in the base plate, a transverse bore intersecting each of the upright sockets, the transverse bores beng spaced, each of the transverse bores extending from a side of the base plate and being spaced between upper and lower faces of the base plate, a cable having a central conductor and external insulation extending into each of the transverse bores associated with one of the clamps, the insulation terminating inside the associated transverse bore, means on the cen-v tral conductor engaged by the associated fastener to provide an electrical connection between each clamp and the associated central conductor, a ground wire extending into the transverse bore associated with the post, means on the ground wire engaged by the post fastener for connecting a free end of the ground wire to the engine, means for connecting free ends of the conductors of the other cables to spark plug connectors of the engine, and a needle-pointed electrode mounted on each of the clamps, the needle-pointed electrodes extending radially of the disc electrode, pointed ends of the needle-pointed electrodes being spaced from the disc electrode to define spark gaps for testing the spark of the engine.

2. A spark tester as in claim 1 wherein the means on the conductor engaged by the associated fastener is a plug of metal on the conductor inside the associated transverse bore of substantially the same diameter as the associated transverse bore, the plug being engaged by the associated fastener.

3. A spark tester which comprises an insulative base, a conductive ground screw mounted centrally thereon, said screw holding in vertical spaced relation thereto a disc-shaped sharp edge electrode, said electrode electrically communicating through the conductive ground screw with a soft metal plug forming a terminus of a ground cable and securely held by the conductive screw in a socket inside the insulative base, means for connecting an opposite terminus of the ground cable to an engine, a plurality of needle-point electrode rods arranged around and extending radially of the discshaped sharp edge electrode, a plurality of spaced spring clamps mounted on the base surrounding and spaced from the conductive ground screw, each of the spring clamps supporting one of the electrode rods, each of said clamps being fastened to the insulative base by a conductive test cable screw whcih communicates with a soft metal plug formed on an end of a spark plug test connector cable and securely held by the conductive test cable screw in a cable bore inside the insulative base, and means for connecting opposite ends of the test connector cables to spark plug cables of the engine providing a multiple gap spark tester for testing the voltage applied to a plurality of the spark plug cables simultaneously.

4. A spark tester as in claim 3 in which the ground cable is slidably installed through a bore in the insulative base, .the ground cable carries insulation in adjacent relationship to the soft metal plug at the first mentioned end thereof, and the metal plug and the cable insulation extend deeply into the bore for full insulation of the connection between the soft metal plug and the conductor ground screw inside the insulative base.

5. A spark tester as in claim 3 wherein each of the connector cables is slidably installed through a bore in the insulative base, each connector cable is provided with insulation in adjacent relationship to the soft metal plug at an end thereof, the metal plug and the cable insulation extending deeply into the associated bore for full insulation of the connection between the soft metal plug and the conductive test cable screw associated therewith inside the insulative base.

6. A spark tester as in claim 3 wherein the means for connecting opposite ends of the test connector cables to the spark plug cables includes a soft metal plug on the opposite end of each connector cable, the cable insulation terminating adjacent thereto; an insulating sleeve covering portions of the insulation of the cable and of the associated plug, the insulating sleeve extending into the spark plug cap to provide an insulated junction between the spark plug cap and the associated spark plug connector cable.

Claims

1. A spark tester for an engine which comprises a base plate of insulating material, a post mounted on one face of the base plate spaced from sides thereof, a sharp edged disc electrode mounted on the post, a plurality of clamps mounted on said face spaced from the post, a fastener of conductive material holding the disc electrode and the post on the base plate and extending into an upright central socket in the base plate, a fastener of conductive material holding each of the clamps on the base plate and extending into an upright outer socket in the base plate, a transverse bore intersecting each of the upright sockets, the transverse bores beng spaced, each of the transverse bores extending from a side of the base plate and being spaced between upper and lower faces of the base plate, a cable having a central conductor and external insulation extending into each of the transverse bores associated with one of the clamps, the insulation terminating inside the associated transverse bore, means on the central conductor engaged by the associated fastener to provide an electrical connection between each clamp and the associated central conductor, a ground wire extending into the transverse bore associated with the post, means on the ground wire engaged by the post fastener for connecting a free end of the ground wire to the engine, means for connecting free ends of the conductors of the other cables to spark plug connectors of the engine, and a needle-pointed electrode mounted on each of the clamps, the needle-pointed electrodes extending radially of the disc electrode, pointed ends of the needle-pointed electrodes being spaced from the disc electrode to define spark gaps for testing the spark of the engine.

3. A spark tester which comprises an insulative base, a conductive ground screw mounted centrally thereon, said screw holding in vertical spaced relation thereto a disc-shaped sharp edge electrode, said electrode electrically communicating through the conductive ground screw with a soft metal plug forming a terminus of a ground cable and securely held by the conductive screw in a socket inside the insulative base, means for connecting an opposite terminus of the ground cable to an engine, a plurality of needle-point electrode rods arranged around and extending radially of the disc-shaped sharp edge electrode, a plurality of spaced spring clamps mounted on the base surrounding and spaced from the conductive ground screw, each of the spring clamps supporting one of the electrode rods, each of said clamps being fastened to the insulative base by a conductive test cable screw whcih communicates with a soft metal pLug formed on an end of a spark plug test connector cable and securely held by the conductive test cable screw in a cable bore inside the insulative base, and means for connecting opposite ends of the test connector cables to spark plug cables of the engine providing a multiple gap spark tester for testing the voltage applied to a plurality of the spark plug cables simultaneously.

4. A spark tester as in claim 3 in which the ground cable is slidably installed through a bore in the insulative base, the ground cable carries insulation in adjacent relationship to the soft metal plug at the first mentioned end thereof, and the metal plug and the cable insulation extend deeply into the bore for full insulation of the connection between the soft metal plug and the conductor ground screw inside the insulative base.

6. A spark tester as in claim 3 wherein the means for connecting opposite ends of the test connector cables to the spark plug cables includes a soft metal plug on the opposite end of each connector cable, the cable insulation terminating adjacent thereto, an insulating sleeve covering portions of the insulation of the cable and of the associated plug, the insulating sleeve extending into the spark plug cap to provide an insulated junction between the spark plug cap and the associated spark plug connector cable.