US2139475A

US2139475A - High tension ignition system

Info

Publication number: US2139475A
Authority: US
Publication date: 1938-12-06
Anticipated expiration: 1955-12-06

Description

Dec. 6, 1938. T, TOGNOLA 2,139,475

HIGH TENSION IGNITION SYSTEM Filed June 10, 1937 2 Sheets-Sheet l u nml w "ml I. a I W Dec. 6, 1938. T. TOGNOLA HIGH TENSION IGNITION SYSTEM Filed June 10, 1937 2 Sheets-Sheet 2 Patented Dec. 6, 1938 HIGH TENSION IGNITION SYSTEM Tullio Tognola, Sidney, N. Y., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application June 10, 1937, Serial No. 147,537

7 Claims.

The present invention relates to a high tension ignition system and more particularly to an arrangement for adapting ignition generating devices for satisfactory use in situations other than that for which they were designed.

It sometimes happens that it is desired to use an ignition generator such as a magneto for the ignition of an engine having a less number of cylinders than that for which the generator is designed. Thus it may be desired to use a magneto designed to ignite a four-cylinder engine, for operating a two-cylinder engine, or a threecylinder engine with degree and degree spacing of its firing points. It is desirable in such cases that the superfluous discharges of the magneto be dissipated in order to prevent unnecessary electrical stresses on the magneto coil, but this dissipation of the charges should be without fire hazard and without causing undue arcing at the distributor points.

Thus it has been proposed to use an external gap to lead off the discharge from one of the distributor terminals of the magneto, but such external gap constitutes a fire hazard. It has also been proposed to merely ground the superfluous distributor terminal, but in that case the discharge across the points of the distributor is very heavy so that the points are burned and caused to deteriorate.

It is an object of the present invention to providein a high tension ignition system an arrangement for effectively dissipating superfluous discharges of the ignition generator.

It is another object to provide such a device in whichlthere are no external air gaps such as might create a fire hazard.

It is a further object to provide such a device in which arcing at the distributor points is de-U creased rather-than increased.

It is another object to provide such a device in which the energy of the superfluous discharges is dissipated. as heat in a resistor element.

Further objects and advantages will be ap-' parent from the following description taken in connection with the accompanying drawings in which:

Fig. 1 is an end elevation partly broken away and in vertical section of a magneto incorporating a preferred embodiment of the invention;

Fig. 2 is a top view of a second embodiment of the invention; v

Fig. 3 is a longitudinal sectional view of a. distributor terminal and cable connection; and

Fig. 4 is a similar view of such'terminal incurporating a discharge dissipating device in accordance with the present invention.

Referring first to Fig. 1 of the drawings, there is illustrated a conventional type of four-cylinder magneto indicated generally by numeral I incorporating a distributor mechanism 2 including a terminal block 3 from which emerge the

output cables

4, 5,6 and I.

In this embodiment of the invention, it is proposed to use this four-cylinder magneto to ignite a two-cylinder engine, and the output cables 6 and I are accordingly arranged to conduct high tension discharges from the magneto to the engine, not illustrated, for that purpose. The two superfluous output cables 4 and 5 are, as here illustrated, connected to a grounding device 8 comprising a metallic thimble 9 attached and grounded in any suitable way as indicated at II to the frame of the magneto I and closed at its lower end by a metallic plug I2. An insulating bushing I3 is mounted in the upper end of the grounding device 8 and carries a binding post I4 to which cables 4 and 5 are attached.

Within the thimble 9 a resistor element I5 in theiorm of a cylindrical cartridge with terminal conductor caps is mounted with one cap I6 in engagement with the grounded plug I2, and the other cap I! in engagement with the inner end of the binding post I4, either directly or by means of suitable conductive spacing means I 8 so that the binding post is grounded to the frame of the magneto through the resistor I5.-

Resistor I5 may be of any suitable commercial form of suflicient current-carrying capacity to lead of! the discharge of the magneto, and sumcient resistance, to cause the major part of the energy oi. the discharge to be dissipated as heat in the resistor rather than in the air gap of the distributor. 0n the other hand, the resistance is suiliciently low to prevent excessive electrostatic stresses on the magneto coil.

It has been found that suitable values for the resistor I5- are an energy capacity of about one watt and a resistatnce of about one-fourth megohm. It will be understood that these values can be varied within rather wide limits so long as the conditions above set forth are fulfilled, the optimum arrangement being a matter of adaptation to the particular installation.

It will be understood that the discharge dissipating device may be connected in' other ways than as illustrated in Fig. 1. Thus a device of this character may be incorporated directly in the output terminal of the magneto as shown in Figs. 2 and 4. i

Fig. 2 shows the top 2| of a magneto having four output terminals, two of which 22 and 23 are arranged to be connected by

cables

24 and 25 to the spark plugs of the engine to be ignited, while the

other terminals

26 and 21 are provided with energy-dissipating devices in accordance with the present invention.

The output terminal isillustrated in section in Fig. 3 and comprises an insulating shell 28 retained in the cover 2i of the magneto by a metallic thimble 29. A sliding contact 3| is mounted in the lower end of the shell 28 as by means of a socket member 36, and a nipple 32 for receiving the end of the output cable is clamped to the upper end of the shell 28 by means of a nut 33.

In the exercise of the invention, a grounding resistance is inserted in the terminal as shown in Fig. 4. As there illustrated, the nipple 32 is removed and a resistor 34 is inserted with its lower conductive cap 35 in engagement with the socket member 36 for the contact member 3 I, and the upper terminal 31 of resistor 34 is received in a cap 38 of conductive material threaded on the thimble 29.

It will be understood that the resistor 34 in this case is analogous to the resistor l5 shown in Fig, 1 and performs its function similarly.

Although but two locations and arrangements of charge-dissipating devices have been shown and described in detail, it will be understood that other arrangements are possible and that various changes may be made in the design and proportions of the parts without departing from the spirit ofthe invention as defined in the claims appended hereto.

What is claimed is:

1. In an ignition system, a high tension gener-' ator, means for conducting discharges therefrom to ignite an internal combustion engine, and means including a resistor for dissipating superfluous discharges of the generator.

2. In an ignition system, a high tension generator, means including a distributor for conducting discharges therefrom to the cylinders of an engine to be ignited, and means including a resistor for connecting certain of the terminals of the distributor to the ground.

3. In an ignition system, a high tension gener ator, means including a distributor having a plurality of terminals for conducting discharges therefrom to the spark plugs of an internal combustion engine, and means including a resistor having a value lower than the initial resistance of such spark plugs for grounding the superfluous terminals of the distributor.

4. In an ignition system for internal'combustion engines, a high tension generator, a distributor for the output thereof having a plurality of terminals, and means including a resistor having a value of approximately one-fourth megohm forming a ground connection for certain of the terminals of said distributor.

5. In an ignition system for internal combustion engines, a high tension generator, and means adapting said generator for use with engines having a smaller number of cylinders than that for which the generator is designed, including a resistor for grounding the superfluous discharges of the magneto, said resistor having a value during such discharges greater than the resistance of the remainder of the path of such discharges.

6. In combination with a magneto having a distributor with a plurality of output terminals, a resistor grounding certain 9f said terminals having a value low enough to relieve the magneto from undue electrical stress, but high enough to prevent burning the distributor points.

7. In an ignition system, a high tension generator, means including a distributor having a rotary conductor finger and a plurality of output conductors terminating adjacent the path of said finger for conducting discharges therefrom to the spark plugs of an internal combustion engine, and means including a resistor having a value greater than the resistance of the air gap between the finger and its adjacent output conductor of the distributor while a discharge is occurring for connecting certain of the output conductors to the ground.

TULLIO 'I'OGNOLA.