US3260891A - Integrated transistorized ignition control system - Google Patents

Description

y 1966 w. H. JUDSON 3,260,891

INTEGRATED TRANSISTORIZED IGNITION CONTROL SYSTEM Filed April 1, 1964 INVENTOR WILLIAM H. JUDSON ATTORNEYS United States Patent INTEGRATED TRXNSISTORIZED IGNITION CONTROL SYSTEM William H. Judson, Wayne, Pa., assignor to Judson and Judson, Conshohoeken, Pa., a partnership of Pennsylvania Filed Apr. 1, 1964, Ser. No. 356,526 8 Claims. (Cl. 315--212) This invention relates to an electronic or transistorized ignition control system for multi-cylinder internal combustion engines subjected to variable operating conditions'of speed, temperature, and load such as those of automotive vehicles, tractors, trucks, buses, boats, aircraft and industrial engines. More particularly, the invention concerns a completely integrated. single package system which is adapted to be incorporated within any presentlyknown ignition system simply by transferring the wires from the already existing ignition coil to the binding posts of the casing of the instant device which contains all of the components for effecting maximum engine performance.

The conventional ignition system as furnished on all present-day standard automotive engines is fundamentally the same make-and-break point system employed on cars built some fifty years ago. It includes a spark induction coil, a rotary distributor, a cam-operated make-andbreak switch (commonly called points) and a condenser in parallel with the points. A battery is connected in series through a ballast resistor with the primary of the coil and the breaker points, the distributor rotor being coupled to the coil secondary while the stator segments of the distributor communicate with the respective spark plugs.

It is well known that the breaker points are an engineering compromise which impose a very serious limitation upon engine operation over the extreme variety of operating conditions even normally encountered. First of all, due to interruption by the points of the large inductive current in the coil primary, a large arc is drawn across the points each time the contacts open. The arcing necessarily results in pitting and burning of the point contacts and is the main cause of wear which consequently necessitates frequent replacement. Secondly, when the points close, current flows in the coil primary but builds up only slowly because the induced primary voltage opposes the battery voltage. The greater the number of turns in the primary, the greater is the induced back which accordingly results in deceleration in current build-up. Thirdly, the points must accept the feed-back voltage from the secondary which also produces some arcing even through a certain portion of this feedback is absorbed by the condenser. At low r.p.m. when the engine is barely turning over, as for example, starting in cold weather, the points remain in contact much longer than during usual driving speeds. This prolonged contacting condition produces overheating and oxidation of the points and causes them to become blue with consequent increased contact resistance, the ultimate effect being loss of engine power, generally poor performance and diflicult starting.

At high engine speeds, because of the increased size of the magnetic core necessary to produce high self-inductance in the spark coil at cranking speeds, there is accordingly a substantial magnetic core loss which is sufiicient to effectively decrease the high voltage at the secondary. The proportionate decrease in high voltage results in the frequently encountered high speed misses, and hence, poor fuel combustion, fouled plugs, with consequent engine residue and wear.

Thus, the conventional ignition system does not provide sufficient voltage and amperage at high speeds so as to produce missing, loss of power, carbon deposits, high fuel consumption, and a rough running engine. Because it provides too much amperage across the points at idle and cranking speeds, the breaker points break down and account for difficult starting and ignition failure.

Although transistorizing the input to the spark coil by incorporating the points in the base circuit of a current limiting transistor switch and utilizing an ignition coil having a very closely coupled primary and secondary Winding with a primary of relatively low inductance (see US. Patents No. 2,955,248 and No. 2,966,615) improves the foregoing deficiencies to some extent, there still remains the inductive load in series with the points themselves. Furthermore, while the amperage across the points is considerably reduced by placing them in the base circuit (0.5 amp as compared to 6 to 7 amps in conventional ignition), the resultant low amperage is not sufiicient to gen erate enough heat to burn off the usual film of oil on the points which has a tendency to become deposited thereon because of its nearnes-s to combustion fumes. Moreover the electronic ignitions of today employ germanium transistors which are not capable of operating at temperatures in excess of 200 F. As a result, the prior art transistor systems had to decentralize the disposition of the various components because of the likelihood that the combination of the ballast resistor, the coil, and the engine itself would generate so much heat energy as to cause the germanium transistor itself to blow.

Finally, the power or amperage (not voltage) produced at the spark by the prior art transistorized ignition systems decreased as the speed of the engine increased. The Voltage output remained the same up to the higher speeds where it fell off drastically. All of this is just contrary to the requirements of the engine.

The conventional magneto which has been in existence for years and now used as standard equipment in aircraft, has an output curve that is opposite to that of the battery ignition. Thus, the magneto starts out very poorly because of its reliance on a rotating magnet for changes of flux through the coil. The weak output at cranking speeds results from the slow rate at which the flux is cut. However, at speeds above 1,000 rpm, the magneto becomes more efiicient, and its output remains fairly level as the speed increases up to and beyond 5,000 rpm. However, in addition to the large size and cost of a conventional magneto ignition, there still exists its poor performance at the low or cranking speeds.

The instant invention is a complete and integrated electronic system which is adapted for immediate installation on any existing ignition system. If the existing system has a ballast of a particular value, the unit of the instant device uses that ballast. If no ballast is utilized in the existing system, none is necessary in the present device. Installation consists simply of transferring the tree wires from the existing ignition coil to the binding posts of the packaged unit of the present invention.

It is therefore an object of this invention to provide an integrated transistorized ignition control system for incorporation within any existing ignition system wherein the output will increase as the speed of the engine increases and yield positive ignition at all speeds under any condition of load and temperature.

Another object of this invention is to provide an electronic ignition control system in which the fire power at the plugs will match the ignition requirements of the engme.

Another object of this invention is to provide an electronic ignition control system in which the inductive load is fully eliminated from the distributor points and replaced by a pure resistive-capacitive load whereby breaker point life is materially extended many times.

Still another object of this invention is to provide an electronic ignition control system which will produce improved engine performance (2 to 6 miles more per gallon of fuel), faster starting, and a higher top speed.

Yet another object of this invention is to provide an electronic ignition system for internal combustion engines in which the engine may develop its maximum potential horsepower.

Still a further object of this invention is to provide an electronic ignition system which will yield superior performance at idle and starting speeds even in sub-zero Weather, and having the same type of output wave form as a mechanical magneto at higher speeds.

Yet a further object of this invention is to provide an electronic ignition control system which will yield maximum voltage in minimum rise time.

A still further object of this invention is to provide an electronic ignition control system which is adapted for either negative or positive ground systems.

Another object of this invention is to provide an electronic ignition-control system in which all parts are incorporated on a single integrated casing and which will continue to function at a temperature up to 450 F. Another object of this invention is to provide an electronic ignition control system which will draw less than half the amperage of conventional systems thereby resulting in longer battery life.

Other objects of this invention are to provide an improved device of the character described that is easily and economically produced which is sturdy in construction, and both highly eificient and effective in operation.

With the above and related objects in view, this invention consists of the details of construction and combination of parts as will be more fully understood from the following detailed description when read in conjunction with the following drawings in which:

FIGURE 1 is a perspective view of an integrated electronic ignition control system embodying this invention.

FIGURE 2 is a sectional view taken along lines 22 of FIGURE 1.

FIGURE 3 is a schematic diagram of the electronic ignition circuit embodied in this invention.

Referring now in greater detail to the drawing in which similar reference characters refer to similar parts, I show an integrated electronic control system comprising a single housing, generally designated as A, which contains as a unitary package all circuitry B for immediate installation and coupling with an existing ignition system, generally designated as C.

The housing A includes a generally cylindrical insulated casing portion 12 having a pair of mounting legs or bosses 14 and 16 for securing by suitable screws or bolts the entire package to the frame of a structure, for example, under the hood of an automobile. The casing portion 12 may be molded from any suitable insulating material having high dielectric properties, such as hard rubber or a styrene and/ or formaldehyde plastic composition. The interior of the casing 12 is hollow, and in the illustration of FIG- URES l and 2, the hollowed interior has a generally rectangular configuration whose inner walls define an outwardly bellied square, although such is not material to the spirit of the invention. The lower end of the casing 12 is closed, but has a tubular element 18 extending therefrom which communicates wtih the hollow interior.

An annular metal ring 20 is secured to the upper portion of the casing 12 and has an interior wall configuration substantially co-extensive with that of the interior of the casing. The ring 20 is preferably cast of a lightweight heat conductive metal such as aluminum. A plurality of integrally formed fins 22 radially extend peripherally of the exterior Walls of the ring 20 and operate to dissipate heat from the ring which itself acts as a heat sink for the transistorized system. A ground binding post 24 laterally projects from one wall of the ring 20 and includes a conductive threaded rod portion 24a which communicates 4 with the interior thereof and a plastic knob 24b which screws upon the external portion of the threaded rod.

An insulated cap 26 is detachably secured over the ring 20 by pins 28 which are mounted in the walls of the casing 12 so as to act as a closure for the entire housing A and its internal electrical components B. Binding posts 30 and 32 project outwardly from the cap 26 and serve as a means for coupling the battery and distributor respectively of the existing ignition system C to the circuitry B of the instant invention.

The heart of the instant ignition control system is in the use of a silicon transistor 35 (either P-N-P of N-P-N) for both negative or positive ground systems, and the coupling of the conventional breaker points 50 in the collectoremitter circuit of the transistor 35. The transistor 35 is mounted upon the outer wall of the heat sink 20 and is of the three electrode junction type cooperatively associated with a silicon semiconductor body, such as a No. 35413 made by R.C.A. This is in contradistinction to the germanium transistors previously employed in prior transistorized ignition systems. As shown in FIGURE 3, the emitter electrode 36 is coupled to binding post 32 which is to be connected to the make-and-break points 50 of the distributor 52. The base 37 of the transistor is connected to the battery binding port 30 through a heatdissipating and current limiting resistor 39. It has been found that a 10 watt 40 ohm resistor is suitable for this purpose. The collector electrode 38 is connected to one end of the primary of an ignition coil 40, the other terminal of the coil primary being coupled to the battery post 30.

The ignition coil 40 is potted within the casing portion "12 of the housing A in an encapsulation of the usual resinous potting material, such as naphthalene. The primary winding of the coil 40 may have turns of #18 wire and the secondary 35,000 turns of #40 copper wire, for example. One end of the ignition coil secondary extends through the tube 18 at the bottom of the housing A and is directly coupled to the rotor 52a of the distributor, the cam 5212 being also operative in its normal function of actuating the opening and closing of the make-and-break points 50. The other end of the secondary of coil 40 is internally connected (not shown in FIGURE 3) to binding post 24 where it is externally secured to the reference ground or frame of the automobile.

A 10 watt, 100 volt zener diode 42, such as a #1Cl375, is connected as shown across the emitter 36 and collector 38 electrodes of the transistor 35. In addition, a 1 watt, 9.1 volt zener diode 44, for example, #1C1710, is connected across the base 37 and the emitter 36, as shown in FIGURE 3. The zener diodes 42 and 44 are secured to the interior wall of the heat sink 20 or may be mounted in back-to-back relationship with the wall of the heat sink 20 therebetween (not shown). Also connected interiorly at the housing A and across the binding posts 24 and 32 is a condenser 46 such as a 3 microfarad, 200 volt paper capacitor.

It is thus to be observed that all of the circuitry B of my ignition control system is self-contained within the housing A. See area defined within the broken lines of FIGURE 3. When installing a prior transistorized ignition system, it was necessary to install and connect three different components, i.e., the coil, the ballast and the transistor plate. Some of the prior art transistorized ignition systems either by-passed the existing ballast or substituted one of their own. Thus, the installation of transistorized controls in the prior art ignition systems required removal of the original ballast, which is difficult to locate on most vehicles, wiring the three components,

and running the Wire from the coil to the ignition switch.

In the present invention, the original coil, which was a part of the existing ignition system is completely removed, and the three lead wires to that coil are transferred to the present housing A and its contained circuitry B. Note that the instant circuitry employs its own coil 40 and its own condenser 46. The source of current is that already existing in the vehicle, and as shown in FIGURE 3, is in the form of a 12 volt electric storage battery 54 incorporated in a negative ground system which is standard in all United States manufactured automobiles. The positive terminal of the battery 54 is connected to a ballast or main current controlling resistor 56 which had been connected to one end of the primary of the existing ignition coil now removed. The lead which had connected the ballast 56 to the primary of the original coil is now couple-d to binding post 30 of housing A so as to be joined to the primary of the new coil 40 and the base circuit of transistor 35. The lead from the points 50 to the other end of the previous coil is now connected to binding post 32, i.e., the emitter electrode 36 of the transistor 35. The end of the secondary of coil 40 which projects through tube 18 is connected to the rotor 52a of the distributor, and the binding post 24 connected to ground. It is not necessary to run wires to the ignition switch 58 nor is it necessary to remove the original ballast. The spark plugs 60 remain coupled to the distributor segments as before.

Accord-ing to the principles of the instant invention, the transistor performs the switching function of establishing and interrupting the flow of current required for the energizing of the primary winding of the ignition coil 40. This function is accomplished by the use of a control circuit for applying the proper polarity voltage bias which is periodically interrupted by the make-andbreak points 50 of the conventional ignition system. It is to be observed that the points 50 are coupled to the coil 40 primary through the collector-emitter circuit of the transistor 35. The current flowing through this circuit is 2.5 amperes as compared to 6 to 7 amperes in a conventional ignition. The zener diodes 44 and 46 are reverse biased into the breakdown region for the purpose of voltage stabilization. Thus, the coil 40 which has stored energy during closing of the points releases this energy upon their opening through the zener diode 42 which becomes conductive for the reverse voltage and thereby chops off the pulses at this value. Therefore, instead of high voltage passing through the transistor, it bypasses the current through the zener diodes. The overall effect is to totally remove any inductive load on the points 50 and provides instead a pure resistivecapaoitive load. This enables extremely rapid rise time (.5 microsecond) delivered at relatively constant voltage (30,000 volts minimum) and constant amperage (10 milliamperes) to the plugs 60 at all engine speeds.

It is to be noted that the ignition control system of the instant invention in all cases adapts to the system in which it is incorporated. If the existing system has a ballast resistor of a part, the present invention uses that ballast. If no ballast is utilized in the previous system, then none is to be incorporated with the instant invention. Similarly, if the previous ignition system utilizes a positive ground in its circuitry, as is the case in some trucks as well as in foreign automobile ignitions, the present invention will adapt to and employ a positive ground system. That is, after disconnecting the xisting coil, the binding post 30 would now be connected to the negative side of the battery while the binding post 32 would be coupled to the points now on the positive side of the battery. However in this modification (not shown) the condenser 46 would be wired to post terminal 24 through binding post 30.

Inasmuch as the silicon transistor 35 will operate satisfactorily up to a temperature of 450 F., the present invention can incorporate this transistor with all of its component circuitry in a single package.

Although this invention has been described in considerable detail, such description is intended as being illustrative rather than limiting since the invention may be variously embodied and the scope of the invention is to be determined as claimed.

What is claimed is:

1. In an ignition system for internal combustion engines having a rotary distributor communicating sequentially with a plurality of spark plugs and a battery coupled to points of said distributor; an integrally packaged electronic control unit comprising a coil having primary and secondary windings, a transistor having a base, a collector, and emitter electrodes, a condenser having one plate coupled to said emitter electrode, a reverse biased diode connected across said collector and emitter electrode, a diode coupled across said base and said emitter electrodes, and a resistor having one end connected to said base, the other end of said resistor being coupled to one end of said coil primary and being further coupled to one battery terminal, the other end of said coil primary being connected to said collector electrode, said emitter electrode being further connected to said points, one end of said coil secondary being connected to the rotary element of said distributor, and the other end of said coil secondary being coupled to the other plate of said condenser through a ground reference.

2. The invention of claim 1 wherein said transistor comprises a silicon semiconductor body for both negative and positive ground systems.

3. An electronic ignition control system for internal combustion engines having a distributor sequentially coupled to a plurality of spark plugs and a source of connected to the points of the distributor, comprising a single casing, a heat sink on said casing, an ignition coil having a primary winding and a secondary winding mounted in said casing, one end of said secondary winding extending through an aperture in the casing for connection to the distributor, a transistor mounted on said heat sink and having a base, collector and emitter electrodes, a condenser having one plate connected to said emitter electrode, means for coupling the collector-emitter of said transistor from one end of said coil primary to the distributor points, means for coupling the base and the other end of said coil primary to one terminal of the source, and means for coupling the other plate of said condenser and the other end of said coil secondary to a ground reference.

4. The invention of claim 3 including a first zener diode is connected across said collector and emitter electrodes, and a second zener diode is connected across said base and emitter electrodes.

5. The invention of claim 4 wherein said transistor has a silicon semiconductor body.

6. An electronic ignition control system for internal combustion engines having a distributor sequentially coupled to a plurality of spark plugs and a battery having one end coupled to points of the distributor, comprising an integral housing and heat sink, a silicon transistor having a base, collector and emitter electrodes and mounted on said heat sink, an ignition coil mounted within said housing and having a primary and a secondary winding, means for coupling the collector-emitter circuit of said transistor in series with the coil primary, the points and the battery, means for biasing the base, a condenser coupling the emitter with one end of the coil secondary, and means for connecting the other end of the coil secondary to the distributor.

7. The invention of claim 6 including reverse bias diode means connected across said collector and emitter electrodes.

8. The invention of claim 7 including a second reverse bias diode means connected across said base and emitter electrodes.

References Cited by the Examiner Brice Ward, Transistor Ignition, Article appearing in Popular Electronics, June 1964, pp. 33-44, -87.

JOHN W. HUCKERT, Primary Examiner.

D. O. KRAFT, Assistant Examiner.

Claims (1)

1. IN AN IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES HAVING A ROTARY DISTRIBUTOR COMMUNICATING SEQUENTIALLY WITH A PLURALITY OF SPARK PLUGS AND A BATTERY COUPLED TO POINTS OF SAID DISTRIBUTOR; AN INTEGRALLY PACKAGED ELECTRONIC CONTROL UNIT COMPRISING A COIL HAVING PRIMARY AND SECONDARY WINDINGS, A TRANSISTOR HAVING A BASE, A COLLECTOR, AND EMITTER ELECTRODES, A CONDENSER HAVING ONE PLATE COUPLED TO SAID EMITTER ELECTRODE, A REVERSE BIASED DIODE CONNECTED ACROSS SAID COLLECTOR AND EMITTER ELECTRODE, A DIODE COUPLED ACROSS SAID BASE AND SAID EMITTER ELECTRODES, AND A RESISTOR HAVING ONE END CONNECTED TO SAID BASE, THE OTHER END OF SAID RESISTOR BEING COUPLED TO ONE END OF SAID COIL PRIMARY AND BEING FURTHER COUPLED TO ONE BATTERY TERMINAL, THE

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