US2477775A - Self-compensating means for make and break circuits - Google Patents

Description

Aug. 2, 1949. H, R. STUART 2,477,775

SELF-COMPENSATING MEANS FOR MAKE AND`BREAK CIRCUITS y Filed Jan. 19, 1946 HARv R STU/m7.

nventor (Ittorneu Patented Aug. 2, 1949 AUNITED STATE S PATENT OFFICE SELF-COMPENSATING MEANS FOR MAKE AND BREAK CIRCUITS Claims.

Y The present invention broadly relates to selfregulating means for inherently improving the performance of current interrupter contacts, and is more particularly directed to correcting certain deficiencies in conventional circuits being used for electric ignition in internal combustion engines.

' The primary object of this invention is to provide electro-magnetic compensating control means for variable speed automotive engines or the 'like that are frequently run under widely varying speed conditions, said means at slow breaker frequency being adapted to automatically decrease the initial current ow and'protracted intensive arcing at the interrupter contact points to reduce the Wear rate thereof, and if desired to automatically boost current flow to progressively and automatically augment the intensity of an ignition jump spark as the breaker frequency rate is increased.

A further object is to accomplish the cited purpose by inherent means inbuilt or compactly installed as an accessory to existing types of ignition distributors Without need of any mechanical manipulation to attain a more advantageous control of current flow at said contact points over conventional practice.

Embodied herein are illustrative circuit ari rangements that will hereinafter be more explicitly set forth. Reference is had to the accompanying sheetv of drawings that discloses a preierred embodiment of my invention, and in which drawings:

Fig. 1 is an elevational view taken in part section along line I-l of Fig. 2, that shows my compensating means applied to a well known automotive distributor or ignition timer, a portion of the preferred wiring system being incorporated alongside such sectional view.

Fig. 2 represents a detail taken along 2-2 of Fig. 1 with half of the distributor cap removed.

Fig. 3 schematically presents a wiring diagram Afor the Fig. 1 type of distributor.

skirt I2. Above such disc, the shaft I4 may carry a multi-lobed circuit breaker cam I1, the one shown being of octagonal contour adapted to handle an eight cylinder engine. Mounted upon said disc is an insulated, laterally resilient circuit breaker lever I8 which is cam actuated about the insulated fulcrum I9 by the intermediate cam follower 20. A swinging end of such lever is provided with an interrupter contact point 22. Cooperating therewith is a mated anvil or opposed contact point 23 that is usually grounded to the framework. An insulated terminal lug 24 may be flexibly connected to the contact 22 through a spring 9 and said lever I8 which is also wired at 8 to connect with a conventional shock condenser 25 whose casing may be grounded. The use of such condenser is deemed essential for a commercially acceptable performance vas applied to jump spark ignition in automotive engines.

The crown of the shaft I4 may have demountably aiiixed thereto, an insulated distributor arm 26 which may be maintained in. contactwith the high tension electrode 21 that is retractively mounted in a bell-shaped plastic cap 28. Also carried by such cap, are one or more wiped brushes such as 29, their number being dependent upon the proiile given to the cam II. These brushes are successively contacted by the varm 26. EachA such brush may be separately wired at 30 to a distinctive jump spark plug 3| in a conventional manner. l

' Another timer circuit (see Fig. 1, diagram) is comprised in the lead wire 32r extending from the electrode 21 to the ignition or the like induction coil 33 having the primary winding 34, a core 35 and ya secondary'high tension winding 36. Corresponding terminals of such superimposed windings may be interconnected by the lead wire 31 and carried to an electrical energizing source such as the storage battery 38 that in automotive practice is commonlygrounded at G. A dash controlled ignition switch 39 usually commands current flow to the primary winding 3 4, the opposite terminal of said primary winding being carried by the lead wire 2| to the lug 24.

The foregoing description relates to a conventional electrical hook-up for a combined current interrupter and distributor commonly employed in variable speed automotive engines. An in herent defect thereof lies at slow distributor speed in rapid wear by destructive arcing at the primary contact points 22 vand 23. In` order to remedy these deficiencies, I preferably resort tothe supplementary electrical compensating means shown in Fig. 1.'

Such preferred corrective may be introduced in the defined conventional distributor lead wire 2| by the use of a compensating primary Winding 40 in conjunction with a secondary Winding 4l which is wound in opposition to its primary Winding to co-operate with a soft iron core 42 common to both such windings in transformer fashion. Said primary winding 40 is connected in series with a primary Winding 34 of the induction coil. The secondary winding 4I is preferably shunt connected across the lead wires 2l and 31, there being an additional compensating condenser 43 interposed in series with such shunt, as shown.

Upon closing the circuit breaker points 22 and 23, current will flow from the battery 38 through the coils 4D and 34. This in turn magnetizes the cores 42 and 35 and induces a potential in such direction as to assist the battery potential. in charging the condenser 3. When the latter becomes fully charged. current ceases to ow through the coil 4l. the work done by the initialcurrent inrusb tbrougli'tlie coil 4.0 momentarly increases the impedance of sold coll 40 and effects a reduction in the initial current flow through the circuit including the circuit breaker points 22 and 23- The iron cores 42 and 35. remain masnetized so lone as these points remain closed. Upon opening the timed. breaker points, the battery current through the coils 4B and 34. is stopped, whereby the magnetism of both iron cores 35 and 42 collapses end. thus inducing a potential .in coils 34- 3e. 40. and 4l,

The potential induced in coil 34 is in .a direction to pass current through the battery 38 from negative to positive to assist the battery boten tial in. charging the shock condenser. 25, while at the same timev tending to raise the potential of the condenser 43..

The potential induced in coil dl is in a direc.- tion to .further add to the potential of the con denser A3 and therefore tends to remain the potential of the interruptor contact 22 as it breaks the circuit at the points 22 and 23.. Because of such transient action, the condenser H3 does not maintain its charge after the points 2.2 and 23 are completely seperated but said charge may oscillatively equalize. through the coils All, 4| and 34, As will be understood, the condenser 25, coil 34 and the battery 38 function in conventional fashion in causing a spark to lump the can ofthe spark plus 3l.

These. various components of my distributor System muy have. different time constants. When suilicent time elaoses between the closing and opening of suoli circuit, certain transient elects such as the current ilow to the condenser 43 may have ceased and ell other conditions may have. become stable before another cycle is begun.

As. the cyclic frequency is increased; the. time consumed in charging and discharging the :maile iary condenser 43 may dually coincide with its natural period and almost exactly counteract the instantaneous imljliddince of coil Ml. Upon a still urther increase ci frcouencylthe charging current to the condenser 43 may assist the battery current theo flowing through coil 34 and thus in.- oreose the useful high tension. spark voltage, above that. which. would obtain. by the use of couventicnel means` .It might be observed that the constants of my electrosmagnetio system may remain fixed and that therefore the electrical performance may be materially affected by changes in periodic frequency. Accordingly different phase relations of current and potential may result when the breaker points operate at Widely diiferent frequencyA By proper proportioning, said system may be designed to buck current ow at one frequency and to boost the same at some other frequency, preferably in an inherently self-regulatine or automatic manner without need of extraneous impedance adjustment.

Furthermore, assuming the use of an inserted choking transformer and combined condenser of proper capacity, the relative current ow through the closed interruptor contacts may Without jeopardy be increased as the rate of cam revolutions is raised to provide a self-regulating, gradually augmented engine ignition spark that affords a minimum of Contact Wear under adverse slow speed running conditions.

Accordingly, my auxiliary transformer elements to, 4l and 42 together with the condenser t3, may at high speeds serve as a spark booster. VAll such compensating components may be compaetly assembled as an accessory unit and as such readily be incorporated into existing conventional distributor circuits. It will be obvious that for single or multicylinder engine purposes, the same principle underlying my self-regulating circuit may likewise be applied to different needs such as any pulsating or intermittent current generated by means of a circuit interrupting device.

Itis thought the foregoing disclosures will make evident to those skilled ln this art, the more outstanding advantages aforded over the prior art by my improved automatic compensating means, also that various equivalent modiflcations in my illustrative exemplication may be applied in obtaining a similar result, all Without departing from the spirit and scope of my invention as more particularly characterized in the appended claims.

I claim:

1. 1n a circuit breaker device, the combination of a pair of current interruptor contacts, means for making and breaking said contacts in sequence. a choke condenser shunted across the broken contacts, an induction coil comprising an electrically energized primary winding and a Secondary winding, said contacts being respectively wired to the opposed terminals of said primary winding to complete a circuit therethrough when the contacts are closed, and supplementary electrical compensation means comprising a primary winding, a cooperating secondary winding and an additional condenser, the primary winding of the compensating means being connected in series with the primary winding of the induction coil and the secondary winding of the compensating means being shunted across the aforesaid series connected primary windings and having the last named condenser incorporated into such shouted cross connection.

2. n a circuit breaker for jump spark ignition of a multicylindor internal combustion engine, the combination of a pair of current interrupter contacts, rotatable cam means operatively disposed to repeatedly make and break said contacts, e shock condenser shunted across the broken contacts, a distributor device provided with a distributor arm arranged to shift in synchronism with the cam moans and further provided with a plurality of high tension brushes that are contacted in sequence by said arm, a separate spark plug independently Wired to each such brush, an induction coil comprising an electrically energized primary winding and a secondary winding, the latter having a terminal connected to said arm and the interrupter contacts being respectively wired to opposed terminals of said primary winding to complete a circuit therethrough when said contacts are closed, and self-regulating electrical compensating means comprising a, primary Winding, a cooperative secondary winding and an additional condenser, the primary winding of the compensating means being connected in series with the primary winding of the induction coil and the secondary winding of the compensating means being shunted across the aforesaid series connected primary windings and having the last named condenser incorporated in such shunted cross connection, said compensating means serving to effect a relatively intense choking action to current ow through said completed circuit while the engine is run at comparatively slow speed and to progressively reduce such choking action with increased engine speed without need of impedance adjustment.

3. A circuit breaker comprising a pair of current interrupter contacts timed by a distributor for successively igniting explosive charges in a variable speed multicylinder internal combustion engine, a shock condenser shunted across said contacts, an induction coil having a primary winding and a secondary winding both cooperatively coiled about acommon magnetic core, and

compensating electrical means comprising a supplementary primary Winding that encircles another magnetic core and is connected in series with the primary of said coil and which compensating means further include separate secondary winding means subject to the inductive influence of the last named core and which winding means is shunt wired across the respective outer terminals of the aforesaid series of primary windings with an additional condenser incorporated in said shunt wiring.

4. A circuit breaker comprisingna pair of current interrupter contacts timed by a distributor for successively igniting explosive charges in a variable speed multicylinder internal combustion engine, a shock condenser shunted across said contacts, an induction coil having a primary winding and a secondary winding both cooperatively coiled about a common magnetic core, and compensating electrical means comprising an auxiliary condenser together with a supplementary primary winding that encircles another magnetic core and is connected in series with the primary of said coil and which compensating means further include separate secondary winding means subject to the inductive influence of the last named core and which Winding means is shunt connected across the respective outer terminals of the aforesaid series of primary windings whereby to modify the output of the secondary winding of the induction coil at different breaker frequencies.

5. In a circuit breaker de-vice, the combination of mated current interrupter contacts, means for successively making and breaking said contacts, a shock condenser shunted across the breaker contacts, an induction coil comprising an electrically energized primary winding and a secondary winding, said contacts being respectively Wired to the opposed terminals of said primary Winding to complete a circuit therethrough when the contacts are closed, and supplementary electrical compensating means comprising an auxiliary condenser together with a primary winding and a cooperating secondary winding of which both windings surround a common magnetic core, the primary winding of said compensating means being connected in series with the primary windings of the induction coil and the secondary winding of the compensating means being shunted across the outer terminals of the aforesaid series connected primary windings.

HARVE R. STUART.

REFERENCES CITED The following referemces are of record in the file of this patent:

UNITED STATES PATENTS

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