US 3858113 A
The disclosure describes sensitivity adjustment apparatus for adjusting a flash tube which generates a flash of light in response to the firing or a spark plug in an internal combustion engine. The apparatus adjusts the trigger level voltage at which the flash tube fires in order to prevent misfiring or double firing during a cycle of engine rotation. A bias circuit supplies a DC bias voltage to the flash tube which is less than the trigger level voltage. An additional voltage surge is supplied to the flash tube through a coupling disk and a pick up conductor attached to the lead wire of one of the spark plugs. By adjusting the position of the coupling disk relative to the flash tube, the voltage coupled to the flash tube can be varied to accommodate the range of spark plug voltages encountered in various internal combustion engines.
Claims available in
Description (OCR text may contain errors)
Pruss 1451 Dec. 31, 1974 IGNITION TIMING LIGHT SENSITIVITY ADJUSTMENT APPARATUS Gerald A. Pruss, Chicago, 111.
Sun Electric Corporation, Chicago, Ill.
Filed: Dec. 13, 1973 Appl. No.: 424,550
US. Cl... 324/17, 313/201, 315/58, 315/241 S Int. Cl. F02p 17/00 Field of Search 315/241 S, 58, 71; 313/201, 234; 324/16 T, 17
References Cited UNITED STATES PATENTS l/l956 Floyd 313/201 10/1969 Fuchs 4. 324/16 T Primary ExaminerMichael .l. Lynch Attorney, Agent, or FirmMolinare, Allegretti, Newitt & Witcoff 5 7 ABSTRACT The disclosure describes sensitivity adjustment apparatus for adjusting a flash tube which generates a flash of light in response to the firing or a spark plug in an internal combustion engine. The apparatus adjusts the trigger level voltage at which the flash tube tires in order to prevent mistiring or double firing during a cycle of engine rotation. A bias circuit supplies a DC bias voltage to the flash tube which is less than the trigger level voltage. An additional voltage surge is supplied to the flash tube through a coupling disk and a pick up conductor attached to the lead wire of one of the spark plugs. By adjusting the position of the coupling disk relative to the flash tube, the voltage coupled to the flash tube can be varied to accommodate the range of spark plug voltages encountered in various internal combustion engines.
6 Claims, 3 Drawing Figures IGNITION TIMING LIGHT SENSITIVITY ADJUSTMENT APPARATUS BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to ignition timing lights and more particularly relates to means for adjusting the sensitivity level of ignition timing lights.
Most internal combustion engines are provided with a crankshaft damper having a mark which rotates into alignment with a similar mark mounted on a fixed position on the engine during each rotation of the engine. In order to adjust the ignition timing, the engine is started and an ignition timing light is connected to the number one spark plug of the engine so that a flash of light is produced as the number one spark plug fires. The light is directed on the damper and the distributor of the engine is then rotated to vary the spark timing until the damper mark appears to be in alignment with the corresponding engine mark.
Most such timing lights employ a flash tube which produces a flash of light in response to a fixed trigger voltage level. If conventional circuitry is used to couple the flash tube to the number one spark plug, experience has shown that the voltage produced by some engines will be too low to reliably trigger the flash tube, whereas the voltage produced by other engines is so high that multiple flashings per engine revolution are triggered.
In order to overcome this deficiency, the applicant has devised an economical and foolproof method of reliably adjusting the trigger level voltage of a flash tube to accommodate the various voltage levels encountered in different internal combustion engines. According to a principal feature of the invention, a bias means supplies a portion of the DC voltage needed to trigger the flash tube and an adjustable coupling means provides the remainder of the requisite triggering voltage. A conductor means transmits the requisite voltage to the coupling means in response to a surge of current in the ignition system, such as the current surge resulting from the firing of a sparkplug. By adjusting the position of the coupling means in relationship to the flash tube, the amount of voltage applied to the flash tube can be varied to accommodate a wide range of voltages encountered in different types of engine ignition systems.
According to another feature of the invention, the coupling means comprises a metal band placed in a fixed position around the flash tube and a metal disk which is movably mounted adjacent the flash tube. By using this unique apparatus, the trigger level voltage of a timing light can be adjusted with a degree of accuracy and reliability previously unattainable.
DESCRIPTION OF THE DRAWINGS These and other advantages and features of the present invention will hereafter appear in connection with the accompanying drawings wherein like numbers refer to like parts throughout and wherein:
FIG. 1 is a schematic, fragmentary drawing of an exemplary internal combustion engine and ignition system which can be used in connection with the present invention;
FIG. 2 is an enlarged, fragmentary isometric view of a preferred form of ignition timing light sensitivity adjustment apparatus made in accordance with the present invention; and
FIG. 3 shows the apparatus illustrated in FIG. 2 with certain elements removed to more clearly show the details of the underlying parts.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, thepresent invention can be used in connection with an exemplary 6 cylinder internal combustion engine 10 having an ignition system 12 including a coil 13, a distributor l4, and a battery 16. Power is supplied to the ignition system by battery 16 through an ignition switch 18. The ignition system sequentially applies a high voltage to spark plug lead wires 21-26 which causes a spark discharge in spark plugs 31-36, respectively. As soon as a spark plug discharges, a surge of current is transmitted through the associated lead wire in a well known manner.
Engine 10 is supplied with a circular crank shaft damper 38 which bears a timing mark 40. Mark 40 can be aligned with a similar mark 42 which is fixed on the block of engine 10.
Referring to FIGS. 2 and 3, a preferred form of timing light system 50 made in accordance with the present invention basically comprises a flash tube 52, a housing assembly 55, a bias circuit 60, a coupling circuit 62, a conductor assembly and an adjustment assembly 84.
More specifically flash tube 52 comprises a conventional gas-filled tube in which the gas ionizes to produce a flash of light when a voltage of about 1,600 volts DC is applied across a positive terminal 53 and a negative terminal 54.
Housing assembly 55 comprises a printed circuit board 56 and a bracket 57 which holds tube 52 above the printed circuit board in the manner shown. Each of the components is held in place inside a case 58 having an open end 59 through which the light from tube 52 is visible.
Bias circuit 60 comprises a conventional DC power supply which provides 600 volts DC across terminals 53 and 54.
Coupling circuit 62 comprises a fixed metal trigger band 64 which surrounds tube 52 in the position illustrated, and a movable metal trigger disk 66, such as a steel washer, having a central orifice 67. The provision of a fixed trigger band and a movable trigger disk is an important feature which enables an appropriate voltage to be coupled to the flash tube by using conventional components of convenient size.
Conductor assembly 70 comprises a capacitive clip 72 which includes an upper plate 74 and a lower plate 75 that are shaped to fit around one of spark plug lead wires 21-26. The upper and lower plates are connected to an upper handle 76 and a lower handle 77, respectively. Both the plates and handles are fabricated from metal which will conduct an electrical current. The handles are pivotally mounted around a pivot rod 78 so that the upper and lower plates are moved apart by squeezing handles 76 and 77 together. An insulated conductor 80 comprises an insulation layer 82 which surrounds a conductive metal wire 81. Wire 81 connects upper handle 76 to band 64 and disk 66.
Adjustment assembly 84 comprises a pivot bearing 86 mounted on circuit board 56 in the location shown in FIGS. 2 and 3. As shown in more detail in FIG. 3. the
assembly also comprises pivot arms 88 and 89 which are displaced from each other by an angle A of 90. Pivot arm 89 ends in a finger 90 which is arranged perpendicular to the longitudinal axis of pivot arm 89. Arms 88 and 89 are joined by a pivoting coil 92 which is positioned around bearing 86 in the manner shown in FIG. 3. Assembly 84 also comprises a thumb slide 94 consisting of a slide arm 96 having a slot 97. Finger 90 extends through slot 97 in the manner shown in FIG. 3, and arm 96 extends through an opening 98 in case 58. Slide arm 96 is attached to a perpendicular control arm 99 having a roughened outer surface 100 to facilitate movement of the assembly by the thumb of the operator.
In order to operate the system, plates 74 and 75 are fitted around the number one spark plug lead wire of the engine, such as spark plug lead wire 21. As previously described, flash tube 52 ionizes to produce a light in response to 1,600 volts DC. 600 volts out of the requisite 1,600 volts is supplied by bias circuit 60. As soon as a high voltage is supplied to lead wire 21 by coil 13 and distributor l4, spark plug 31 fires or discharges so that a current surge is produced in lead wire 21. The current surge produces a voltage in conductor assem bly 70 which is coupled to the flash tube through metal trigger band 64 and metal trigger disk 66. The amount of voltage coupled to the tube depends on the relative position of disk 66 and tube 52. By moving thumb slide 94 forward or backward, disk 66 is moved in an arcuate path beneath tube 52 to couple an amount of voltage to the tube which results in reliable tube firing.
Those skilled in the art will recognize that only a single preferred embodiment of the invention has been disclosed herein which can be modified and altered by those skilled in the art without departing from the true spirit and scope of the invention as defined in the accompanying claims.
What is claimed is:
1. In a system comprising a flash tube for generating a flash of light in response to the firing of a spark dis charge device resulting in a surge of current in the ignition system of an internal combustion engine, improved apparatus for adjusting the trigger level voltage at which the flash tube fires comprising in combination:
bias means for supplying to the flash tube a DC bias voltage less than the trigger level voltage;
a metal band positioned around the flash tube;
a metal disk movably positioned adjacent the flash tube;
conductor means for transmitting a voltage surge to the metal band in response to the surge of current in the ignition system; and
adjustment means for varying the position of the metal band and metal disk relative to each other, whereby the magnitude of the voltage surge coupled to the flash tube can be varied.
2. Apparatus, as claimed in claim 1, wherein the metal band is fixed relative to the flash tube.
3. Apparatus, as claimed in claim 1, wherein the ignition system comprises a lead wire for carrying the surge of current to the spark discharge device and wherein the conductor means comprises:
a capacitive clip adapted to be positioned around the lead wire; and
a conductor connecting the capacitive clip to the coupling means.
4. Apparatus, as claimed in claim 1, wherein the adjustment means comprises:
a case for containing the flash tube;
a pivot bearing;
a first pivot arm fastened to the disk;
a second pivot arm movable from outside the case;
means for pivotally mounting the first and second pivot arms on the pivot bearing.
5. Apparatus, as claimed in claim 4, wherein the adjustment means further comprises a thumb slide including a slot in which the second pivot arm is slidably mounted.
6. Apparatus, as claimed in claim 5, wherein the angle between the first and second pivot arms is UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT ND. 3,858,113
DATED December 31, I 1974 INVENTOR(S) t GILBERT A. PRUSS It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Kindly correct the first name of the inventor from "Gerald" t0 -GILBERT-.
Signed and sealed this 20th day of May 1975.
C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks