US2081979A

US2081979A - Ignition coil system

Info

Publication number: US2081979A
Application number: US741763A
Authority: US
Inventors: Ferdon D Bentley
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1934-08-28
Filing date: 1934-08-28
Publication date: 1937-06-01
Anticipated expiration: 1954-06-01

Description

June 1, 1937- F. D. BENTLEY IGNITION COIL SYSTEM Filed Aug. 28, 1954 IN VEN T016 PLUGS m w 1 V 3 W E a m n em D m a J a z 6 5 n, 0 ml 1W WM, 5 A M F m g y i v N 0 5 M n 1 o 1 1 r 6 m 5 i M 6 1 1 l: 5 M 5 7 5 III: J F 1 n n /8 m 1 M 3 9 4 a f a F l 1 1 5 v T 6/ M Patented June 1, 1 937 I UNITED STATES PATENT OFFICE IGNITION COIL SYSTEM Delaware Application August 28, 1934, Serial No. 741,763

12 Claims. (Cl. 175-361) This invention relates to ignition coils for gasoline motors and the like, and has particular reference to a device for the elimination of static interference when radio apparatus is employed in the immediate vicinity of an internal combustion engine.

Various devices have been resorted to in the past for suppression of the interference above referred to. Among these are the so-called supm pressors" which are applied to the spark plugs. Various forms of electrostatic shielding have. also been provided for isolating a radio receiver from static effects of an ignition system. Since the radio apparatus is usually operated from the 15 some battery as that which serves the ignition system, shielding does not provide the complete isolation of the radio receiver which is desired. l have discovered, however, that the structure of the ignition coil may be so designed as to very 2Q considerably reduce the interference both as transmitted through space between the ignition system and the radio receiver, and also as transmitted through the conductors to the common battery.

25 it is an object of my invention to provide an ignition system the electrical characteristics of which are such as to substantially eliminate sparking interference with the ordinary operation oi a radio receiver.

3@ Other objects of my invention are: to provide an ignition coil structure suitable ffor u'se in an ignition system whose battery is common to that oi a radio receiver; to provide adequate shielding in an ignition coil such that static interference, 35 at above referred to, is substantially suppressed; and to provide means for substantially eliminating a so-called corona-effect which, if it takes place between the primary and secondary windings of an ignitioncoil, is a contributing cause of 40 static interference.

The foregoing and other objects of my inven tion will beapparent upon reading a complete description thereof, details of which are given in the ensuing part of the specification wherein ref- 45 erencfe is made to the accompanying drawing in core 3 about which is wrapped a sheet of insulating material 4. The secondary winding 5 is preferably disposed next to the insulation 4 and internally of primary winding 6. Between the primary and secondary windings, Iprovide an elec- 5 trostatic shield l, faced on both sides thereof by insulating members 8 and 9. The shield I may be composed of sheet copper. The usual precautionsare taken that the abutting edges of the shield 5 do not make contact with one another, 10 since, it they did, an undesirable sho-rt-circuited loop would be provided for induced currents therein.

The arrangement of the coil leads contributes most effectively to the efficiency of operation of my invention. Preferably, the starting lead of the secondary winding is connected to a sheet metal member iii which. is disposed about one end of the laminated core 3. A molded insulation end piece it is so constituted as to provide on the inner side a cup into which the laminated core 3 may fit. The sheet metal member ill intervenes between the Aamlnations oi the core and the inner wall of this cup. The molded member l l is also provided with an outer cup which may, if desired, be lined by a metallic receptacle it. After the ignition coil unit has been assembled, a mall 83, or the like, may be driven through a central hole in the insulation member I l thereby electrically interconnecting the cup lining it, the

sheet metal lead Hi, which connects with the starting lead ofthe secondary winding 5 and the laminations of the core 3.

The finish lead of the secondary winding and the start lead of the primary winding are connected by a conductor l4 (common to both) to a terminal post l5 so that connection may be made with the breaker-points l6 (see Fig. 2) of' the ignition system.

The outer lead of the primary winding may be 40 connected as by means of a conductor I!- to a terminal post It fol-connection with an ignition switch l9. Another end piece 20 of molded insulation is provided with an internal cup for holding the core in position.- The molded end pieces II and 20 may; therefore, be seen to be similar in construction except that the member ll only is provided with areceptacle for an ignition wire to the distributor 29.

The assembly of my ignition coil unit may be I 1 completed by encasing the unit within the outer cylindrical member 2|, the ends of which may be permanently locked into engagement with metal flanges 22. The letter, if desired, may be molded illtothe peripheries or the members II and 20 respectively. The edges of the members 22 may be spun over the flanged portions of the casing member 2i. The'entire ignition coil unit may, if desired, be supported by a 'clamp 23, or in any other desired manner.

In order to prevent induced currents in the members 2i and 22, these parts are split and the intervening space is preferably filled with insulating compound. The clamp 23, if it is in two pieces, may be provided with insulation members ll about the bolt 32 so as to avoid a short circuit for induced currents.

The electrostatic shield I may be electrically connected to the outer shell II as by means of a conductor 33. These elements may then be grounded in any suitable manner; for example, through the clamp members 23 which, presumably are supported by a metallic portion oi the chassis.

It will be noted that the cylindrical walls of the insulation member il extend considerably beyond the ends of the coils. The purpose of this arrangement is to avoid a corona effect which has been known to take place between the primary and secondary coils. This effect is very objectionable.

. The very marked improvement in the operating characteristics in my ignition coil unit, as compared with units heretofore known, may be attributed in part to the arrangement of the coil leads I adiacent the electrostatic shield i. These particular coil leads are at the low potential ends of the primary and secondary respectively.

Referring to Fig. 2, I show the relation between the connections to my ignition coil unit and the other elements of my ignition system such as contribute further to the improved performance characteristics of the system as a whole. In this diagram will be seen the common battery ll grounded at one end and having a lead at the other end to the ignition switch i 9. The ignition switch is preferably shunted by a capacitor 25 having a value of the order of say .5 mi. The ignition switch is, as before stated, connects with the terminal post l8 of the ignition coil unit. A conductor 20 is shown interconnecting the breaker points it with one lead each of the primary and secondary windings, the leads being connected to the terminal post I! (Fig. 1). The

-breaker points may, if desired, be shunted by a capacitor 21 having preferably a value of about .25 mt.

A conductor 20 interconnects the-terminal ll ing a core member, primary and secondary windings, an electrostatic shield separating the primary from the secondary, insulating means disposed internally and externally 01' said shield. a

terminal post common to the outer lead of the inner winding and to the inner lead of the outer winding, a grounded metallic outer casing, and means including an electrical connection between said shield and said casing for substantially suppressing the eifects of ignition-circuit interference upon a nearby radio apparatus.

2. An ignition circuit transformer comprising a core, an insulating member surrounding said core, a secondary winding about said insulating member, an inner and an outer insulating sleeve surrounding said secondary winding, a grounded electrostatic shield disposed between said inner and outer sleeves, a primary winding exterior. to said outer sleeve, a grounded metallic casing for said transformer, a binding post for the outer lead of said primary winding, a distributor lead reoeptacle connected both to said core and to the inner lead of said secondary winding, and means including a conductor common to the inner lead of said primary winding and the outer lead of said secondary winding for substantially preventing the radiation of ignition-circuit interference to a zone occupied by radio apparatus.

3. An ignition circuit transformer comprising shieldingly encased primary and secondary coils. a grounded electrostatic shield of thin metal interposed between said primary and said secondary, a breaker-point connection'to the outer terminal of said secondary and the inner terminal of said primary, an ignition switch connection to the outer terminal of said primary, a laminated iron core, and means including a distributor connection to the inner terminal of said secondary and to said core for substantially suppressing the eifects oi ignition-circuit interference upon a nearby radio apparatus.

4. An ignition circuit transformer in accordance with claim 3 and having means including laminations of insulating material between which said electrostatic shield is disposed, at least one of said laminations extending substantially beyond the lengthwise limits of the coil convolutions.

5. In a transformer, a secondary coil, a primary coil wound over said secondary, ignitioninterference shielding means insulatingly interposed between said primary and said secondary, a conductor interconnecting the flnish-lead of said secondary and the "-lead of said primary, separate conductors to the start"-lead 'of said secondary and to thefflnish lead of said primary, respectively, an outer metallic casing and a grounded connection both to said casing and to said shielding means.

6. In a device for suppressing the interference effect upon radio apparatus caused by an ignition system, an ignition transformer having primary and secondary coils, a split tubular casing therefor of magnetic material which is grounded, a grounded electrostatic shield separating said primary from said secondary, and means including a tubular member of insulating material' over-reaching the coil ends and the shield ends sumciently to substantially eliminate corona leakage between said coils and from either of said coils to said shield.

7. An ignition-circuit transformer for internal combustion engines comprising in combination .core member, primary and secondary windings,

an electrostatic shield separating nil from said secondary, a container for said windings having a split cylindrical wall of magnetic material and end pieces of non-metallic material, and means includingra groimded conductor connecting with said shield and with the cylindrical wall of said container for substantially suppressing the effects of ignition-dreuit interference upon a nearby radio apparatus.

8. A transformer for use with a bat- 2 7 system for a radio apparatus and'for the ignition circuit of an internal combustion engine, comprising primary and secondary windings, a core member electrically connected tothe' 7s start"-lead of the inner one of the two said windings, a metallic ignition-interference shield separating said windings, a metallic container surrounding said windings, a ground terminal for said shield and said container, and a breaker; point common to the finish"-lead of the inner winding and to the start-lead of the outer winding.

9. The invention as set forth in claim 8 wherein means including an insulation member are provided adjacent said ignition -interference shield for substantially suppressing a corona discharge loetween said windings and from either of said windings to said shield.

10. in a transformer, primary and secondary coils wound one over the other, ignition-interierence shielding means insulatingly interposed between said coils, a laminated core and a cylindrical container both of magnetic material, means including a conductor common to said shielding means and to said cylindrical container 101' maintaining the same at substantially ground potential. means i'or equalizing potentials applied to the finish-lead ofthe inner coil and to the start"-lead of the outer coil, and means for equalizing potentials applied to the "start"- lead of the inner coil and to the laminated core.

11. A device in accordance with claim 10 characterized in that said ignition-interference shielding means and said cylindrical container are so constructed as to offer substantially an infinite impedance to induced currents circulating therein,

12. In a device for suppressing the interference efiect upon radio apparatus caused by the ignition system of an internal combustion engine, a transformer having primary and secondary windings, an electrostatic shield separating said windings, and means including members of insulating material at least one of which over-reaches the edges of said shield sufficiently to substantial lyeliminate corona leakage between said windings and said shield.

FERDON' D. BENTLEY.