US2412690A - Ignition apparatus for internal - Google Patents

Description

, therefor.

Patented Dec. 17, 1946 T oFFlcE IGNITION APPARATUS FUR INTERNAL- COMBUSTION ENGINES Walter Ochsenben, Bern, Switzerland, assignor to Hasler A. G. Werke fr Telephonie und Przisionsmechanik, Bern, Switzerland Application June 12, 1943, Serial No. 490,706 In Switzerland February 2, 1942 2 Claims.

The present invention relates to improvements in ignition apparatus for internal combustion engines and more particularly to an ignition system for generating several directly consecutive sparks at the same spark plug within the same ignition period.

It is known that in the case of weak combusti'- ble mixtures an increase of the engine power can be obtained by generating on each spark plug two or more directly consecutive sparks during one and the same ignitionperiod in the cylinder. A number of means have already been proposed For instance, such a number of ignition apparatus can be used as sparks must be generated per ignition order on each spark plug, so that each apparatus generates during an ignition periodV a single spark on one and the same spark plug. However, this proposition is not economical due to the high Weight, the usually existing diiiiculties for driving and the high costs.

There is a further possibility consisting, for example, in connecting several resistances into the primary circuit of an ignition system. By successively short circuiting these resistances the magnetic iiux will be varied, whereon depends the induction of the ignition voltage. An apparatus of this disposition requires, compared with an ordinary ignition device, high electric power and is, therefore, excessively heavy and voluminous.

Already known are also the apparatus for multiple ignition, wherein the ignition points of different circuits on one and the same spark plug can be adjusted independently of one another, so that forthwith, instead of a simultaneous ignition, the ignition points adjusted may occur at intervals. The apparatus for multiple ignition will thereby, however, no more fully accomplish its original purpose, namely to secure a reliable ignition.

It is an objectof the present invention to provide a plurality of contact pieces circularly disposed within contacting range of a rotatable distributor and being spaced from one another, whereby at least two contact pieces at a time are exclusively connected to a spark plug, so that accordingly at each spark plug at least two sparks will be generated per revolution of' said distribby providing an interrupter which opens at times `for controlling the first spark of an ignition period of each group, While the sparks coordinate (Cl. 12S-148) Z to the remaining contactpieces of the group are generated with open interrupter.

The accompanying drawing shows a diagrammatic view of the ignition circuits of one of Various possible embodiments of the ignition apparatus according to this invention. It illustrates one half of a double magneto ignition system of a twelve-cylinder internal combustion engine.

In the figure the reference I designates the primary Winding, 2 the interrupter, 3 the blow-out condenser, 4 the secondary winding, 5 the distributor, 6 the rst contact pieces of groups of two at a time and 8 the remaining contact pieces of each group. All these contact pieces 6 and are circularly disposed within contacting range of the rotatable distributor arm 5 and each group of two contiguous contact pieces 6 and 8 is connected wth a coordinate spark plug 1. When the distributor arm 5 passes over the contact piece 6 of a group the ignition current controlled by the interrupter 2 flows as current impulse to the coordinate spark plug l and while the interrupter is open, that is in the same ignition period, a further current impulse ows through the same spark plug 1, as soon as the distributorV arm 5 passes over the contact piece 8 of the same group. For the other half of the double magneto ignition system a second distributor, 5 is provided with a. rotatable arm which works in the same manner.

This arm, which is not illustrated, and the distributor arm 5 are mounted upon the shaft 9 which carries the interrupter cam l0` and the magneto rotor il.

If, as illustrated, for igniting a twelve-cylinder four-cycle engine an ignition apparatus is used which per revolution of the ca-m shaft generates twenty-four high-voltage impulses, then these impulses follow each other on each one of the two spark plugs of a cylinder at an angle difference of 30 degrees taken on the crankshaft. For instance, if the rst spark in each cylinder jumps over at 40 before the upper dead-center 'position, the second ignition will occur-at 10 before said dead-center position.

In the case of high-speed engines it can be diicult to open the interrupter` or interrupters several times at each ignition period. However, a single opening of the interrupter, namely for the rst spark, is quite suiiicient. The interrupter may remain open during the second high-voltage impulse. The increase and decrease, respectively, of magnetic flux in the cores of the coils occurs in the cited example at an adopted speed of the magneto of 2500 revolutions per minute 60,000 times per minute, that is rapidly enough, that the slope of the ilux curve relative to the induction of the ignition voltage is still sufficient with the interrupter being open. The second ignition occurs in this case at a moment, which is advanced by the so-called breaking-off angle of about 5 to 6, that means inthe chosen numerical example 15-16" before the upper dead-center position.

Correspondingly, if the number of high-voltage impulses per ignition period is three orv more,` the interrupter must only beopened for generating the first spark of the period in each cylinder and may remain open during the rest of said ignition period. In a magneto, wherein the changes of flux occur, for instance, every 20 taken on the crankshaft of a twelve-cylinder four-cycle engine, wherein, therefore, thirty-six changes of ux take place per revolution of the cam shaft, that is three changes of ilux per ignition process, only two changes of flux, for instance, that means the first and the second .change of flux or the rst and third one are used for the ignition, while the generation of a spark upon the third or the second change of flux, respectively, is .prevented in any known manner.

'I'he use ofthe 'ignition apparatus according tov the invention is, ofcourse, not limited upon magnetos for twelve-cylinder four-cycle engines. They are as well adapted for magnetos of twocycle engines and any number of cylinders.

What I claim is:

4 1. In a high tension ignition system for internal combustion engines comprising a source of current,y a. primaryl winding anda secondaryl winding, and an interrupter in circuit with said primary winding, a distributor in circuit with said secondary winding including a rotary distributor lever driven by the engine synchronously with said interrupter and a plurality of contacts distributed circumferentially around the rotary axis of said lever adapted to be successively contacted thereby, said ignition system being adapted to deliver to said distributor lever at least one high voltage impulse for each of said contacts,

l a lplurality of adjacent contacts each being connected to a common spark plug terminal to fire v across the spark gap thereof a plurality of times al; a small phase displacement in the same ignition period.

2. An apparatus as set forth in claim 1 wherein said source of current is a multipole magneto delivering per revolution of said distributor lever a number of high-voltage impulses at'fleastequal to the number of said contacts, the synchronous drive between said distributor lever and interrupter being so arranged that the contacts of the interrupter are opened only at the time of contact of said distributing lever with each first one ofthe adjacent contacts which are connected to a single spark plug.

' WALTER QCHSENBEIN.

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