US2811672A - Electronic ignition system or the like - Google Patents

Description

Oct. 29, 1957 E. M. GILBERT ELECTRONIC IGNITION SYSTEM OR THE LIKE Filed Sept. 21, 1955 mOhqmm;

VEOBFMZ vEOkCMZ EDWIN MAJOR GILBERT INVENTOR.

HIS ATTORNEY United States Patent Ofifice ELECTRONIC IGNITION SYSTEM OR THE LIKE Edwin Major Gilbert, Burbank, Calif., assignor to Holiman Electronics Corporation, a corporation of California Application September 21, 1955, Serial No. 535,568

4 Claims. (Cl. 315-163) This invention is related to ignition systems and more particularly to a new and improved electronic ignition system which will exhibit optimum reliability.

in the past, many types of ignition systems have been devised for employment in internal combustion engines. in accordance with conventional practice, a single high tension coil is used for each engine. In multi-cylinder engines this coil is frequently over-taxed because at high engine speeds the reluctance will not permit the coil to collapse completely before the next impulse is imposed on it. Also, the efliciency of current ignition systems is considerably below that desired, owing to leakage from the high-tension wires connected to the spark plugs. Other disadvantages are to be found in the current employment of distributors in which high tension current is supplied successively to the successive distribution points from the rotating distributor arm, by virtue of which there results a reduced efficiency and a production of unwanted radio interference signals during intervals of contact between the distributor arm and the several distributor points. Recently there have been devised several ignition systems employing a plurality of circularly disposed pick-off coils and an inwardly disposed, rotatable, magnetic field producing means which is caused to rotate and thereby produce in the several successive pick-off coils successive energy pulses which are translated and stepped up, voltage-wise, to the spark plugs. The transformers employed, however, have necessarily had to be of a type exhibiting an extremely high turns ratio, owing to the decreased energy level of the initial energy pulses. In addition, the timing of such a system is difiicult to adjust and regulate while the voltage levels at these spark plugs themselves exhibit a considerable degree of variation.

Therefore, it is an object of the present invention to provide a new and useful ignition system which may be conveniently adjusted for timing.

It is a further object of the present invention to provide a new and useful electronic ignition system in which the output voltage pulses as applied to the ignition system spark plugs will be uniform energy level.

According to the present invention, a permanent magnet or electromagnet with a suitable switching circuit is centrally and rotatably disposed with reference to a plurality of circularly pick-off coils which correspond in number to the number of cylinders in the associated engine. Pulse energy is fed from each pick-off coil through a pulse shaping network, if desired, to the input circuit of an associated thyratron tube which is normally biased off for non-conduction. Pulse occurrence at the input side of the several thyratron tubes causes discharge of the successive tubes and produces a current surge in the several output inductances or transformers coupled to the output side of the several thyratron tubes. This current surge produces a high output voltage in each of the thyratron output transformer circuits, which voltage is impressed across its respective spark plug. Variable bias Patented Oct. 29, 1957 means is supplied the several thyratron tubes for controlling the level at which the tubes will fire.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, in which:

Figure l is a schematic diagram partially in block form of an electronic ignition system according to the present invention.

Figure 2 is a schematic diagram of a circuit which may be alternately employed at several points in the circuit of Figure 1, if desired.

In Figure 1, magnet 10 may be either a highly concentrated, magnetic field type of permanent magnet or an electro-magnet provided with energy supplying means and a suitable switching circuit, and is mechanically coupled to shaft 11 to rotate in accordance therewith. Shaft 11 itself may be coupled and appropriately geared to the engine crankshaft, camshaft, or other convenient point. Thus, for each engine cycle magnet 14) will accomplish one complete revolution. Induction coils 12 are circularly disposed about shaft 11 and are coupled at one end to ground, the remaining ends thereof being coupled through a [respective pulse shaping network 13, if employment of such pulse shaping network is to be desired (such desirability being hereinafter explained), to the input side of a respective thyratron tube 14. Each control electrode 15 is coupled through an input resistor 16 to a common variable bias voltage source 17. Cathodes 18 of the several thyratron tubes 14 are coupled to ground through a respective cathode charging capacitor 1?, and, in addition, are coupled to a charging voltage source, such as the combination of battery 2%) and vibrator and filter 21 (shown in block diagrams). Anodes 22 of thyratrons 1-2 are coupled as shown through transformers 23 to spark plugs 24, respectively.

The circuit shown in Figure l operates as follows. In rotating through the region of proximity associated with each of the several induction coils 12, magnet 10 will by virtue of its field induce a voltage in the induction coils 12 which will be routed through a respective pulse shaping network 13 to a respective control electrode 15 of thyratron tube 14. The various pulse shaping networks 13 may be designed to sharpen the input pulse or may be designed to generate a sawtooth voltage, or similar voltage from which, with the cooperation of variable bias source 17, will regulate the time of firing of the several thyratron tubes 14. In lieu of an eiectronically controlled timing arrangement accomplished by variable bias source 17, manual timing might be effected by varying the angular disposition of the several induction pickup coils 12 with reference to a particular disposition of shaft 11, as is indicated by arrows 26. This may be accomplished by the employment of mechanical flyweights, a manual cable, or by other means.

There must necessarily be employed in the system a relatively high D. C. voltage source, such as is indicated by the cooperation of battery 2% and vibrator and filter 21, to charge negatively the several cathode capacitors 19 to a predetermined value for awaiting sudden discharge through each respective thyratron tube 14 upon the occurrence of a positive pulse on the input side thereof from a respective one of the several pickup coils 12. Discharge of the cathode capacitors 19 through their respective thyratron tubes will produce a sharp voltage rise at the several output transformers 23, which voltage rise is subsequently translated to the several respective spark plugs 24. Itis accordingly seen that the firing of the several spark plugs 24 will correspond to the angulat disposition of shaft 1 1 and magnet 10 relative to the several induction pickup coils 1-2. Hence, by the present design the applicant avoids the employment of high tension induction coils, interrupter means, and the conventional distributor arrangement. Timing. is accomplished either by manually adjusting the disposition of the circularly disposed induction pickup coils 12, or by employing a pulse shaping network having a sawtooth output signal in conjunction with a variable bias voltage source, for adjusting the discharge of the several thy-ratron tubes 14.

In lieu of circuit portions 25, signified by the dotted line shown, circuit portion 200- in Figure 2, consisting of the shunting of an. output inductor 201 by the associated spark plug 202, may be employed. Owing to the high voltage which must be developed across reactor 201 to cause the firing of spark plug 202', a coil having arel'atively high magnetizing cur-rent must necessarily be employed.

It is to he understood the equivalents of thyratrons 14', e; g., semi-conductors exhibiting thyratron characteristics, may be substituted in the circuit of Figure 1.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and, therefore, the aim inthe appended claims i to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. An electronic ignition system'including, in combination, a plurality of spaced induction coils; rotatable, magnetic field producing means movable with reference to saidfinduction coils; a plurality of pulse shaping means each coupled to one of said induction coils and responsive to'electricalimpulsestherefirom for producingoutput volt ages of substantially sawtooth character; a plurality of thyratron tubes each having an input circuit coupled to a respective one of said pulse shaping means and an output circuit including a charging capacitor; adjustable bia means coupled to each of said input circuits of said thyratron tubes for ranging the time at which said sawtooth voltage will cause said thyratron tubesto conduct; a plurality of sparkplugs; and separate means intercouplingeachof said spark plugs with a. respective one of said output circuits for simultaneously translating and transforming current surges therein to each of said spark plugs as high voltage impulses.

2. Apparatus according; to claim. 1; in: which each of said thyratron tubes is produced with an anode coupled to said translating and transforming means, a control electrode coupled to said input circuit, and a cathode; a negative voltage source coupled to said cathode; said changing capacitor having a first terminal coupled to said cathode and a second terminal maintained at a common reference potential which is positive with respect to said negative voltage source.

3'. Apparatus according to claim 2 in which said transletting and transformingameanscomprises a transformer.

4. Apparatus according toclaim 2' in which said translating and transforming means eomprises an inductor.

References. Gitedin the fil'e of this patent UNITED STATES PATENTS 2,353,527 Touceda et al: July ll, 1944 2,474,550 Short et al. June 28, 1949 2,490,960 Hanchett Dec. 13, 1949

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