US 3680029 A
A wire resistor including a ceramic core and a resistor wire wrapped on the core constructed of approximately 4.5 percent aluminum, 22 percent chromium, 0.5 percent cobalt and the balance iron, which is coated with an insulating material, is positioned between an internal combustion engine ignition circuit spark plug lead and the associated spark plug for suppressing electromagnetic radiation on firing of the spark plug in the frequency range of 20-1,000 megahertz to prevent pollution of the air by extraneous radiation.
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Description (OCR text may contain errors)
United States Patent Berry Field of Search IGNITION CIRCUIT RADIATION SUPPRESSION RESISTOR lnventor: Norman H. Berry, 49 Cambridge, Pleasant Ridge, Mich. 48069 Filed: Dec. 16, 1970 Appl. No.: 98,604
US. Cl. ..338/334, 123/148 A, 174/355 M, 252/513, 338/66, 338/270 Int. Cl .1101: 1/06 ..338/66, 267-270, 338/264, 301, 302, 334; 174/355 M, 36; 123/148 A, 148 P; 252/513; 330/177 References Cited UNITED STATES PATENTS 7 58,439 10/ 1 866 l y o n 23 6017 lGNITlON CIRCUIT lllllll [4 1 July 25,1972
Houchin ..l36/l77 3,191,132 6/1965 Mayer 174/36 3,212,044 10/1965 Cloud 3,529,273 9/1970 Morris ..338/66 Primary Examiner-E. A. Goldberg AnorneyWhittemore, l-lulbert & Belknap  ABSTRACT 9 Claims, 1 Drawing Figure APPROXIMATE WIRE COMPOSITION 4.5% ALUMINUM 22 CHROMIUM 5% COBALT BALANCE IRON PAIENIEHIIII2 Am 3.680.029
IGNITION CIRCUIT /I6 I I I I I I I APPROXIMATE wIRE COMPOSITION 4.5% ALUMINUM 22 CHROMIUM 5% COBALT 24 BALANCE IRoN INVENTOR NORMAN H. BERRY BY ;LZ TE,-E-
BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to ignition circuits of the type used on automobiles and refers more specifically to a wire wound resistor including a substantial amount of iron in the resistor wire for suppressing extraneous electromagnetic radiation produced on firing of the spark plugs, which suppression is enhanced due to the hysteresis effect of the iron in the resistor wire.
2. Description of the Prior Art Relatively recently, ecologists have discovered pollution of the airwaves in certain areas by electromagnetic waves which are not dissipated or confined in the area of use thereof. Thus, for example, garage doors may open and close for no apparent reason in areas where a large number of automobiles are operated, communication may be interrupted with satellites and navigational gear may mysteriously indicate incorrect directions. Such malfunctioning due to electromagnetic interference of our airwaves may be particularly expensive and sometimes dangerous.
Thus, for example, in a newly built lnternal Revenue Service complex in Louisiana, part of the computers memory suddenly went blank, and it was subsequently discovered that signals from the New Orleans airport erased the tax records that had been freshly stored on the computers electronic tape. Also, certain pacemakers for the heart designed to steady the beat of a faltering heart can be knocked temporarily out of rhythm if they happen to come close to microwave ovens.
The Federal Communications Commission has therefore attempted to regulate the use of the airwaves and has provided standards for electronic radiation control. The Society of Automotive Engineers (S.A.E.) have recommended one such regulation in S.A.E. Standard J55la, stating maximum permissible radiation from automobile ignition circuits on firing of the spark plugs therein.
Standard original equipment automobile ignition circuits maintain their emission below the maximum recommended by the S.A.E. at the testing required by the S.A.E. Standard J55la. Such original equipment generally includes a nonmetallic carbon impregnated nylon core spark plug lead. Replacement spark plug leads, however, have generally been of the insulated wire type. For example, copper wire has been used. The solid wire spark plug leads radiate substantial energy on firing of the spark plugs if the energy is not suppressed.
In the past resistors have been placed between the spark plugs and spark plug leads to suppress passage of energy from the spark plugs to the leads on firing of the spark plugs. Also, the spark plug leads have sometimes in the past been wrapped with monel coils to suppress the radiation from the spark plug leads on firing of the spark plugs. Such radiation suppression means have been effective in after-market spark plug leads to reduce radiation from the spark plug leads to within the prescribed S.A.E. limits at lower frequencies. However, at higher frequency in the band indicated above the radiation permitted by these devices has in the past been at or slightly over the maximum recommended by S.A.E. Standard J55la. It is desirable to reduce the radiation from the after-market spark plug leads to a radiation no greater than that provided by the original equipment manufacturers in the frequency range from 20MH to l,000MH,
SUMMARY OF THE INVENTION To further reduce the emission from solid wire spark plug leads, there is therefore provided in accordance with the invention a resistor between the spark plug and spark plug lead which is a wire wound resistor on an insulating core. The wire wound resistor has a substantial iron content so that the electromagnetic energy produced on firing of the park plugs will be dissipated in the resistor partly due to the hysteresis efiect of the iron in the resistor along with the usual attenuation of the radiation due to the alternating and direct current resistance provided by the resistor.
BRIEF DESCRIPTION OF THE DRAWINGS spark plug lead and a spark plug in an automobile ignition circuit.
DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the FIGURE, a wire wound resistor 10 is connected between a spark plug lead 12 and a spark plug 14 in a usual internal combustion engine ignition circuit 16.
In accordance with the usual operation of the ignition circuit 16, the spark plug 14 is periodically caused to discharge, whereby alternating signals over the entire frequency range of, for example, from 20-l ,OOOMH, may be created which if pased back to the spark plug lead wire 12 will be radiated a substantial distance from the ignition circuit to cause radiation pollution of the airwaves.
The wire wound resistor 10 includes a core 18 of high temperature resistant material such as a ceramic and a resistor wire coil 20 wound on the core 18. Metal connectors 22 and 24 are provided, as shown, to connect the wire of the wire wound resistor 10 to the spark plug lead 12 at one end and to the spark plug 14 at the other end.
The electrical energy created on firing of the spark plug 14 is dissipated in the resistor 10 due to the impedance of the wire 20 to the frequency of the signals produced on firing of the spark plug 14 and the direct current resistance of the material of which the wire 20 is constructed.
In addition and in accordance with the invention, the alternating energy produced on firing of the spark plug 14 is further attenuated before arriving at the spark plug lead 12 by the hysteresis effect of the particular resistor wire 20. Resistor wire 20 contains a substantial amount of iron to provide the hysteresis eifect which further attenuates the alternating energy created by the spark plug 14.
The wire 20 is relatively thin and may be between 0.001 and 0.0015 inches in diameter and approximately 18 feet long and include amounts of chromium, aluminum and cobalt to provide required direct current resistance which a pure iron wire would provide very littleof.
In one example, the wire 20 wound on a ceramic core one eighth inch in diameter and three fourth inch inch long was 0.0015 inches in diameter and had a composition of approximately 4.5 percent aluminum, 22 percent chromium, 0.5 percent cobalt and the balance was iron by weight.
The energy absorption due to the hysteresis of the iron in the coil, which hysteresis is defined as the magnetization of a sample of iron due to a magnetic field which is made to vary through a cycle of values and lags behind the magnetic field. Standard textbooks provide an equation developed by Steinmetz for hysteresis and give the law of energy in ergs per cycle per centimeter cubed which may be dissipated by the hysteresis effect as:
where B is the maximum induction in maxwells per cm and n is the coefficient of hysteresis.
While as noted above a pure iron resistor wire will provide a -minimum of direct current-resistance of approximately 3000 While one embodiment of the invention has been considered in detail, it will be understood that other modifications and embodiments are contemplated by the inventor. It is intended to include all modifications and embodiments as are defined by the appended claims within the scope of the invention.
What I Claim as my invention is:
l. A resistor for use in automobile ignition spark plug circuits or the like comprising a ceramic insulating core, a wire coil wound on the insulating core having a substantial iron content whereby energy is dissipated in the resistor due to the hysteresis effect of the iron content thereof and insulating material applied to the wire coil and ceramic core.
2. Structure as set forth in claim 1 wherein the wire is approximately 4.5 percent aluminum, 22 percent chromium, 0.5 percent cobalt and the balance iron.
3. Structure as set forth in claim 1 wherein the resistor wire is approximately 70 percent iron.
4. Structure as set forth in claim 1 wherein the wire is approximately 0.0015 inches in diameter.
5. Structure as set forth in claim 1 wherein the resistor wire is approximately 18 feet long.
6. A resistor for use in automobile ignition spark plug circuits or the like comprising an insulating core and a wire coil wound on the insulating core, the wire of which is approximately 4.5 percent aluminum, 22 percent chromium, 0.5 percent cobalt and the balance iron, whereby energy is dissipated in the resistor due to the hysteresis effect of the iron content thereof.
7. Structure as set forth in claim 6 wherein the resistor wire is approximately 0.0015 inches in diameter.
8. Structure as set forth in claim 6 wherein the resistor wire is approximately 18 feet long.
9. In combination in an ignition system, a spark plug lead, a spark plug and a wire wound resistor in series between the spark plug and the spark plug lead immediately adjacent the spark plug for suppressing radiation on firing of the spark plug which resistor includes a ceramic core and a wire coil wound on the ceramic core including a substantial amount of iron whereby alternating energy created by the spark plugs in the range of 20-l,000 megahertz, in addition to that dissipated due to the resistance value of the resistor, is dissipated due to the hysteresis effect of the iron in the resistor coil.
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