US3888225A

US3888225A - Internal combustion engine ignition controller

Info

Publication number: US3888225A
Application number: US401043A
Authority: US
Inventors: James A Boyer; Charles L Dusenberry
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1973-09-26
Filing date: 1973-09-26
Publication date: 1975-06-10
Anticipated expiration: 1992-06-10
Also published as: CA1023793A; GB1462824A

Abstract

A breakerless ignition controller for an internal combustion engine. The ignition controller is a single-unit device comprising the base and cap of ignition distributor. The cap of the distributor carries an ignition coil. The base of the distributor supports a magnetic pick-up and an electronic module for controlling the current through the primary of the ignition coil. The magnetic flux for generating a control voltage in the magnetic pick-up coil is a permanent magnet. The flux produced by the primary of the ignition coil is so oriented with respect to the flux produced by the permanent magnet of the magnetic pick-up that false triggering voltages that might otherwise be produced by stray magnetic fields are overcome by the magnetic field produced by the primary winding when it is energized. The permanent magnet of the magnetic pick-up is oriented in a predetermined relationship to the magnetic field produced by the conductor connecting the battery and cranking motor of the motor vehicle to further prevent false triggering of the ignition controller. The secondary winding of the distributor cap supported ignition coil is also oriented to prevent false triggering of the system.

Description

United States Patent [1 1 Boyer et a1.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Sept. 26, 1973 [21] Appl. No.: 401,043

[52] US. Cl. 1. 123/148 E; 123/1465 A [51] Int. Cl. F02]! H01) [58] Field of Search... 123/148 E, 148 R, 1480 CD,

[56] References Cited UNITED STATES PATENTS 3,437,876 4/1969 Dotto 123/148 E 3,767,935 [0/1973 Truss 3,783,314 H1974 Kostan 123/148 E Primary Examiner-Charles .l. Myhre Assistant ExaminerRonald E. Cox

Attorney, Agent, or FirmC. R. Meland June 10, 1975 57 ABSTRACT A breakerless ignition controller for an internal combustion engine. The ignition controller is a single-unit device comprising the base and cap of ignition distributor. The cap of the distributor carries an ignition coil. The base of the distributor supports a magnetic pickup and an electronic module for controlling the current through the primary of the ignition coil The magnetic flux for generating a control voltage in the magnetic pick-up coil is a permanent magnet. The flux produced by the primary of the ignition coil is so oriented with respect to the flux produced by the permanent magnet of the magnetic pick-up that false triggering voltages that might otherwise be produced by stray magnetic fields are overcome by the magnetic field produced by the primary winding when it is energized. The permanent magnet of the magnetic pick-up is oriented in a predetermined relationship to the magnetic field produced by the conductor connecting the battery and cranking motor of the motor vehicle to further prevent false triggering of the ignition controller. The secondary winding of the distributor cap supported ignition coil is also oriented to prevent false triggering of the system.

10 Claims, 9 Drawing Figures PATENTEDJUN 1 0 ms SHEET TIME INTERNAL COMBUSTION ENGINE IGNITIUN CONTROLLER This invention relates to an ignition controller that is capable of applying properly timed spark firing impulses to the spark plugs of an internal combustion engine. The ignition controller is a single-unit device where the ignition coil is carried by a distributor cap having terminals connected to the spark plugs of the engine. The distributor cap is supported by a distribu' tor base which supports both a magnetic pick-up and an electronic control module which serve to control the current supplied to the primary winding of the capsupported ignition coil.

The magnetic pick-up comprises a permanent magnet. a pick-up coil and a variable reluctance magnetic circuit including a distributor rotor which is operative to cause an alternating voltage to be induced in the pick-up coil that is a function of the position ofthe distributor rotor. The distributor rotor is driven in synchronism with the engine so that the alternating output voltage of the pick-up coil represents engine crankshaft position.

In order to provide proper ignition timing for an engine. with the type of ignition controller that has been described. the alternating output voltage of the pickup coil must be a precise representation of engine crankshaft position. This is particularly true of the part of the alternating output voltage that causes the electronic control module to interrupt primary winding current since it is at this point in the ignition cycle that a spark firing impulse is applied to a spark plug.

Since a motor vehicle contains a number of current carrying wires that produce magnetic fields it is possible for these fields to induce voltages in the pickup coil of the ignition controller. If these voltages are of sufficient magnitude and improper phase they may cause false triggering of the ignition system with resulting improper ignition timing. Examples of such current carrying conductors are those that supply the horn and airconditioner and the conductor connecting the battery and cranking motor of the motor vehicle.

It accordingly is one of the objects of this invention to provide an ignition controller of the type described which is arranged to prevent false triggering of the ignition system by external magnetic fields. In carrying this object forward the magnetic field produced by the primary winding of the ignition coil. when it is energized, is oriented to aid the magnetic field produced by the permanent magnet of the magnetic pick-up. With this arrangement the flux produced by the ignition coil opposes stray magnetic fields that might otherwise cause false triggering of the system. More specifically. the capcarried ignition coil has a magnetic core that has an air-gap. The air-gap is offset from the longitudinal axis of the magnetic pick-up. With this arrangement. and with the primary winding energized with a proper polarity direct current. the leakage flux produced by the primary winding aids the flux linking the pick-up coil produced by the permanent magnet and opposes magnetic fields that would otherwise cause false triggering of the ignition system.

Another object of this invention is to provide an ignition controller of the type described where the permanent magnet ofthe magnetic pickup is so oriented with respect to the magnetic field produced by the conductor connecting the battery and cranking motor of a motor vehicle that false triggering of the ignition sys tem by the current through the cranking motor conductor is eliminated.

Still another object of this invention is to provide an ignition controller of the type described where the sec ondary winding of the ignition coil is offset from the axis of the controller in the same direction as the offset of the air-gap of the magnetic core of the ignition coil so as to prevent false triggering of the ignition system.

In the drawings:

FIG. 1 is a vertical sectional view of an ignition controller made in accordance with this invention;

FIG. 2 is a top plan view partly in section of the ignition distributor illustrated in FIG. 1 with the cap removed and looking in the direction of line 2-2 of FIG. 1;

FIG. 3 is a plan view of an ignition transformer which is utilized with the ignition controller illustrated in FIG. I;

FIG. 4 is a vertical sectional view of the coil assembly which forms a part of the ignition transformer illustrated in FIG. 3;

FIG. 5 is a top plan view of the magnetic core of the ignition transformer illustrated in FIG. 3;

FIG. 6 is a diagrammatic representation of certain of the parts of the ignition controller illustrated in FIG. I and illustrating certain flux paths for the ignition controller of this invention;

FIG. 7 illustrates the output voltage wave form of the pickup coil of the ignition controller illustrated in FIG. 1;

FIG. Sis a schematic circuit diagram of an electronic circuit which controls primary winding current and which is in turn controlled by the magnetic pickup of the distributor illustrated in FIG. I; and

FIG. 9 is a diagrammatic representation of the positions of the distributor and cranking motor energizing wire in a motor vehicle.

Referring now to the drawings and more particularly to FIG. 1, the reference numeral 10 designates the base of an ignition controller or distributor made in accordance with this invention. The base I0 is formed of an aluminum material and has a longitudinally extending section 12 provided with a bore which receives a shaft 14. The top end of the base 10 is provided with a cylindrical bowl section which has been designated by reference numeral I6.

The annular support section 16 supports a magnetic pickup assembly which includes an annular cup-shaped metallic support designated by reference numeral I8. The part 18 is formed of a magnetic material and has a central tubular section 20 which engages the outer periphery of the top end of a bearing 22 that serves to support the shaft I4. The bearing 22 is fitted into the top end of base 10 as shown.

The part 18 serves to support an annular coil winding 24 which is wound on a suitable spool insulator, an annular permanent magnet 26, and a pole piece designated by reference numeral 28. These three parts are held together by screws 30 illustrated in FIG. 2 which pass through the pole piece and magnet and are threaded into a flange portion of the cup-shaped metallic support 18. The pick-up coil 24 is wound such that it extends about the shaft 14 with its longitudinal axis substantially coinciding with the axis of the shaft 14. The permanent magnet 26 is an annular flat magnet having an upper end face 26A of one magnetic polarity and a lower end face 268 of an opposite magnetic polarity. The pole piece 28 is comprised of an annular section 28A and a plurality of radially inwardly extending teeth designated in FIG. 2 by reference numeral 28B. The ignition controller shown in FIG. 2 is for an eightcylinder engine and in this case there are eight equally circumferentially spaced radially inwardly extending teeth 288. The central portion of part 28 is journalled for rotation on the top end of bearing 22.

The pole piece 28 is, of course, formed of a suitable magnetic material and the teeth of this pole piece cooperate with a rotor designated by reference numeral 32. The rotor, as is better illustrated in FIG. 2, has eight ra dially projecting teeth 32A which become aligned with the teeth 28A of the pole piece 28 as the rotor 32 is rotated by the shaft 14. The rotor 32 has a depending portion 32B formed of magnetic material that is disposed between central portion 20 of part 18 and the inner side of pickup coil 24. As will become more readily apparent hereinafter, rotation of the rotor 32 relative to the pole piece 28 causes an alternating voltage to be induced in the pickup coil 24 as is depicted in FIG. 7.

The shaft 14 drives the rotor 32 through a suitable centrifugal advance mechanism 33 illustrated in FIG. 6 which is contained within the rotor 34 which is formed of an insulating material. This advance mechanism is like that Shown in the US. Pat. No. 3,254,247 to Falge. The rotor 34 is secured to the weight base of the cen trifugal advance mechanism and carries a radially ex tending conductor 36 which engages a contact 38 connected with the ignition coil to be described hereinafter. The conductor 36 is connected with a contact 40 which cooperates with the terminals of the cap of the distributor to be described hereinafter.

As previously mentioned, the magnetic pickup ash sembly comprised of the metal support 18, pickup coil 24, permanent magnet 26 and pole piece 28 is journalled for rotation on the outer surface of the upper end of bearing 22 by engagement of part 20 with the outer surface of the hearing. The housing 18 has an integral radially extending portion 18A which receives the end 42 ofa rod operated by a conventional vacuum advance unit 44. The vacuum advance unit as is well known to those skilled in the art, is connected with the intake manifold of the internal combustion engine and serves to rotate the magnetic pickup assembly relative to the base 10 during the operation of the ignition sys tem to provide a vacuum advance for the ignition controller.

The annular portion 16 of the base 12 also supports an electronic control module designated in its entirety by reference numeral 46 and fixed to the annular portion 16 by fasteners 48. The electronic module 46 is preferably an integrated electronic circuit for controlling primary winding current of the ignition controller of this invention in accordance with the signal information produced by the pickup coil and shown in FIG. 7. The schematic circuit diagram for the electronic module 46 is illustrated in FIG. 8 and described in detail hereinafter.

The ignition controller of this invention has a distributor cap that is formed of insulating material which is designated by reference numeral 50. This distributor cap has a plurality of circumferentially spaced terminals designated by reference numeral 52 one of which is illustrated in FIG. 1. For an eight-cylinder engine there are, of course, eight equally spaced terminals 52 which cooperate in a known manner with the conductor 40 carried by the rotor 34.

The distributor cap 50 has a central portion which supports the conductive insert or contact 38. The insert 38 as will be more fully described hereinafter operates to electrically connect the secondary winding of the ignition coil with the contact 36 of the rotor 34. The upper outer surface of the distributor cap 50 is shaped to provide a part of a compartment which is designated by reference numeral 54. The upper part of the compartment is provided by a cap 56 which is formed of insulating material. The cap 56 is removably secured to the cap 50, for example, by suitable fasteners (not illustrated) which engage the cap 56 and are threaded into the cap 50.

The compartment 54 formed by the upper outer wall of cap 50 and the inner wall of cap 56 contains an ignition coil which is generally designated by reference numeral 58. This ignition coil has a laminated magnetic core designated in its entirety by reference numeral 60 and an outer case 62 formed of insulating material. The outer case 62 has an opening exposing an annular metal conductor or insert 64 which is electrically connected to the top end of conductor 38 by a spring 66. The ignition coil 58 is held in place with respect to cap 50 by four screws 57 which pass through openings 61 (see FIG. 3) formed in the laminated core 60 of the ignition coil and which are threaded into suitable threaded openings formed in internal bosses 50A of the cap 50. A rubber washer 67 is interposed between the lower side of the ignition coil 62 and the cap 50 and has a central opening receiving the top end of the insert 38.

The ignition coil 58 is further illustrated in FIGS. 3, 4, and 5. Referring first to FIG. 5 it is seen that the core 60 of the ignition coil is formed of two lamination assemblies designated respectively as 60A and 608. Each lamination assembly 60A and 60B comprise a stack of steel laminations which are E-shaped. The two stacks of steel laminations are assembled to a three-sided bracket or support which embraces the steel laminations and which is designated by reference numeral 70 in FIG. 3. The support 70 has crimped over sections 70A engaging end portions of lamination stack 60B. The support 70 is generally channel-shaped in crosssection to contain the two stacks of E-shaped laminations and has a tight fit with the stacks of laminations. When the two E-shaped stacks 60A and 60B are assembled to the bracket or support 70, the outer legs of the stacks of laminations 60A and 60B are in engagement with each other over areas designated by reference numerals 72 and 74. The center legs of the two stacks of laminations 60A and 608, however. are spaced from each other to form an air-gap 76 having a dimension of approximately 0.030 inches. it is pointed out that the airgap 76 is offset from the center line 77 of the finally assembled magnetic core 60. This offset may be approximately O.43 inches where the outer dimension of the assembled core 60 is approximately 3 inches on each side. It will also be appreciated that once the laminations are assembled to the bracket 70 they provide three legs 78. and 82, the

outer legs

78 and 82 forming a continuous magnetic circuit and the center leg 80 having the air-gap 76. As will be pointed out hereinafter, the offsetting of the air-gap 76 with respect to the center line 77 of the magnetic core provides an arrangement which prevents false triggering of the ignition controller of this invention. The center leg 80 of the magnetic core 60 receives a central opening in the coil assembly of ignition coil 58.

The ignition coil assembly which is fitted to core leg 80 is illustrated in FIG. 4 and comprises a spool 86 formed of insulating material. The spool 86 has a rectangular cross-section and the primary winding 88 of the ignition coil is wound thereon. Disposed about the outer surface of the primary winding 88 is a secondary winding which is designated by reference numeral 90. In the assembly of the ignition coil shown in FIG. 4, the primary winding 88 is wound on the spool 86. The spool with the primary winding 88 and the secondary winding 90 are then positioned within the case 62. The case 62 is then filled with a suitable potting compound formed of insulating material which has been designated by reference numeral 92. When the secondary winding 90 is disposed within the case 62 it is positioned such that it engages a lower internal wall 62A of the case 62. The secondary winding 90 is electrically connected with the conductive insert 64 which is molded into one side of the case 62 and which as previously mentioned engages the spring 66 shown in FIG. l when the ignition coil 58 is assembled to the ignition controller.

In order to fabricate the final ignition coil assembly which is shown in FIG. 3, the E-shaped lamination stack 60A having the longer legs is provided and the ignition coil assembly shown in FIG. 4 is fitted to this stack of E-shaped laminations by passing the center section 80 through the rectangular center opening of the spool or coil form 86. The smaller stack of laminations 60B is then assembled such that its center section passes through the central opening of the ignition coil provided by the coil form 86. In the final assembly the stacks of laminations are in engagement over lines 72 and 74 but an air gap is provided at 76 as shown in FIG. 5. After the ignition coil is assembled to the lamination stack the frame 70 is fixed to the laminations to hold the laminations in place. A quantity of adhesive may be applied to the stacks of laminations adjacent the airgap 76 which engages the coil form 86 to hold the ignition coil assembly relative to the laminations and frame 70.

After the ignition coil has been completely fabricated as illustrated in FIG. 3, it is assembled to the cap 50 by passing fasteners 57 through the holes 61 formed in the laminations and frame 70 of the ignition coil assembly shown in FIG. 3. As previously mentioned, these fasteners are threaded into suitable threaded openings formed in the bosses 50A of the cap 50 of the ignition controller. The frame 70 and lamination stacks rest on the boss portions 50A of the cap 50.

When the ignition coil 58 is assembled to the cap 50 it is positioned such that the longitudinal axis of the primary winding 88 and the secondary winding 90 are perpendicular to the longitudinal axis of shaft I4. The ignition coil 58 is positioned such that the center line 77 of its core 60 is perpendicular to but aligned with the longitudinal axis of shaft 14. This means that air-gap 76 is offset radially from the axis of shaft 14. Since shaft 14 is concentric with rotor 32. pole piece 28, permanent magnet 26 and pick-up coil 24 of the magnetic pick-up, the air-gap 76 is offset radially a predetermined amount with respect to the longitudinal axis of the magnetic pick-up. The effect of this offset is fully described in connection with FIG. 6.

As previously mentioned. the electronic module 46 that connects pick-up coil 24 and ignition coil 58 is shown schematically in FIG. 8. In FIG. 8 the reference numeral designates the motor vehicle battery the negative side of which is grounded. The positive side of battery 100 is connected to power supply conductor 102 through an ignition switch 104.

The primary winding 88 of ignition coil 58 has two end conductors designated as 88A and 888. In FIG. 8 the end conductor 88A is shown connected to positive power supply conductor 102 and end conductor 888 to the collector of an NPN switching transistor I10. As is explained hereinafter conductor 88A could be connected to the collector of transistor and conductor 888 to conductor 102, thus reversing the direction of current flow through primary winding 88 to thereby reverse the direction of the magnetic field produced by primary winding 88 when it is energized.

The emitter of transistor 110 is connected to one side of a resistor 106 the opposite side of which is connected to grounded conductor 108. A pair of variable resistors 112 and 114 are connected in series across resistor I06 and have a common junction 116.

It will be appreciated that transistor 1 10 controls primary winding current. Thus, when transistor 110 is biased conductive current flows from conductor 102, through primary 88, through the collector-emitter circuit of transistor 110 and then through resistor 106 to ground. When transistor 110 is biased non-conductive current is interrupted in primary 88 with the result that a voltage is induced in secondary winding 90 to develop a voltage to fire a spark plug from a distributor cap terminal 52 that is connected to a spark plug.

The timing information for controlling the on-off switching of transistor 110 is the signal voltage developed in pick-up coil 24 which is depicted in FIG. 7. The conduction of transistor 110 is controlled by NPN transistors 120, 130, I40, I50 and 160. The transistor in addition to collector electrode I22 has a quasicollector electrode 124 connected to the base of transistor 110.

The transistor 120 is a silicon planar transistor comprised of an epitaxial layer of N-type conductivity silicon on a foundation wafer of P-type conductivity silicon with an N+ diffused buried layer in the foundation wafer at its interface with the epitaxial layer. The epitaxial layer serves as a transistor collector region. Over the buried layer there is an island-like P-type base region diffused into the surface of the N-type epitaxial layer, an island-like N-type emitter region diffused into the base region island and a diffused N+ surface enhancement island region inset in the surface of the epitaxial layer collector region on each of opposite sides of the base region island. A discrete ohmic contact of evaporated aluminum is laid down upon each the emitter region, the base region and the two N+ collector surface enhancement regions to provide separate electrodes serving as the emitter electrode. the base electrode, the collector electrode I22 and quasi-collector electrode 124. respectively. With the collector emitter electrodes connected across the positive and negative polarity terminals, respectively, of a direct current potential source, a control potential applied across the base-emitter electrodes of a positive polarity upon the base electrode with respect to the emitter electrode will produce base-emitter current flow and. consequently. a current flow between collector electrode 122 and emitter tiectrode. With the quasi-collector electrode 124 connected to an external point of reference or ground potential directly or through an external electri cal circuit. while the device is not conducting through the collector-emitter electrodes. current flows through the collector region between collector electrode 122 and quasi-collector electrode 124. While the device is conducting through the collector-emitter electrodes, substantially no current flows through the quasicollector electrode 124. The reason for the low or substantially zero current flow through the quasi-collector electrode while the device is conducting through the collector-emitter electrodes is that the quasi-collector electrode. which is at a positive polarity potential with respect to the emitter electrode, the base electrode and the emitter electrode comprise a lateral NPN transistor at the surface of the device which conducts to provide a low impedance circuit to ground around the quasi collector electrode.

The collector electrode 122 and emitter electrode of control transistor 120 are connected across the direct current potential source. battery 100, through resistors 126 and 128 when switch 104 is closed. The quasi collector electrode 124 of control transistor 120 is connected to the base of transistor 110 to control the conduction of transistor 110. Forward base drive current is supplied to the base of switching transistor 110 through quasi-collector electrode 124 while control transistor 120 is not conducting through its collectoremitter circuit for producing conduction through the collector-emitter circuit of the switching transistor 110 to complete the ignition coil primary winding energizing circuit for the flow of ignition coil primary winding energizing current through ignition coil primary winding 88 and resistor 106.

The end conductors of pick-up coil 24 are designated 24A and 248 in FIG. 8. Conductor 24A is shown connected to junction 132 and conductor 24B is shown connected to junction 134. As will be explained herein after conductor 24A will be connected to junction 134 and conductor 243 to junction 132 if the polarity of the permanent magnet 26 is reversed.

The voltage generated in pick-up coil 24 is shown in FIG. 7. The coil 24 must be so connected with junctions 132 and 134 that during a positive half cycle 94 junction 132 goes positive with respect to junction 134 and this corresponds to a condition where transistor 110 is turned on. At the beginning of the negative half cycle 96 (FIG. 7) junction 132 must go negative with respect to junction 134 and this corresponds to the time that transistor 110 is turned off to initiate the firing of a spark plug.

When voltage pulse 94 becomes sufficiently positive it biases transistor 160 on through junction 132, current limiting resistor 136, conductor 138, resistor 139, base-emitter of transistor 160, resistor 142, conductor 108, diode 144, resistor 146, conductor 148 and then through resistor 152 to junction 134. The collectoremitter circuit of transistor 160 is connected across battery 100 by a circuit that can be traced from conductor 102, resistor 153, resistor 154, conductor 156. resistor 158, collector-emitter of transistor 160 and re' sistor 142 to conductor 108. The collector-emitter circuit of transistor 160 is connected across the base and emitter of transistor 150. This means that as transistor 160 is biased on transistor 150 is biased off in its collector-emitter circuit.

With transistor 150 non-conductive the potential of its collector increases. This biases transistor 140 conductive through resistor 162, resistor 164 and resistor 166. The collector-emitter circuit for transistor 140 is through resistors 153 and 168.

The collector of transistor 140 is connected to the base of transistor 130. The collector of transistor is connected to resistor 172. The emitter of transistor 130 is connected to conductor 174 which in turn is connected to the base of transistor 120.

When transistor is biased conductive its collector approaches the potential of grounded conductor 108. This biases the transistor 130 non-conductive in its collector-emitter circuit.

The collector-emitter circuit of transistor 130 is connected in series with the base-emitter circuit of transistor 120. With transistor 120 non-conductive the potential of quasi-collector 124 of transistor 120 biases switching transistor 110 conductive so that primary winding 88 is now energized.

When the output voltage of pick-up coil 24 reverses (voltage 96 FIG. 7) transistor 160 is biased nonconductive. This causes transistor to be biased conductive. transistor 140 non-conductive transistor 130 conductive. transistor 120 conductive and transistor 110 non-conductive. As transistor 110 goes non conductive to interrupt primary winding current a volt age is induced in secondary winding 90 to cause the fir ing of a spark plug.

The control system of FIG. 8 includes a differential amplifier circuit designated by reference numeral 174. This circuit provides a direct current control signal which is proportional to the voltage developed across resistor 106 when primary winding 88 is energized.

The differential amplifier includes NPN transistors 176 and 178 resistors 180, 182, 184, 186, 188 and 190, and diodes 192 and 194 connected as shown in H0. 8. The collector of transistor 176 is connected to conductor 196 and the collector of transistor 178 is also connected to conductor 196 through resistor 182. Resistor 184 is connected to conductor 196 through resistor 198.

The input circuit of differential amplifier 174 includes the base of transistor 176. The base of transistor 176 is connected to junction 116 by diode 192, resistor 186 and conductor 200. The voltage at junction 116 is a function of the voltage developed across resistor 106 which in turn is proportional to primary winding current.

The output of the differential amplifier is taken at junction 202 and the potential of this junction varies as a function of the magnitude of current through resistor 106. This output is applied to the base of NPN transistor 204 through conductors 206 and 208 and resistor 210.

Since the collector-emitter circuit of transistor 204 is connected to the base of transistor 120 it can control the amount of conduction of transistor 120 to in turn control the amount of conduction of transistor 110. The arrangement is such that the current sensed by resistor 106 limits the amount of current conducted by transistor 110 due to the feedback through differential amplifier 174 to transistor 204.

Because of the distributed collector to base capacitance of NPN transistor 110. some phase shift between current and voltage may occur at the base of transistor 110. Resistor 212 and capacitor 214 provide feedback 9 to the differential amplifier I74 to correct the phase shift.

The system of FIG. 8 includes an arrangement for varying the time of turn-on of transistor III). This ar rangement includes NPN transistor 216 and capacitor 218. The collector-emitter of transistor 2I6 is connected in series with resistor I46 and diode 218.

Resistors

220 and 222 are connected across picieup coil 24 through a circuit that can be traced from junction 132,

resistors

220 and 222, conductor 224, resistor I06. conductor I08. diode I44, resistor [46. conductor I48 and resistor I52 to junction I34. The voltage at junction 226 is half-wave rectified by diode 228 and charges capacitor 2I8. through resistor 230. diode 228. resistor 232. capacitor 2l8, conductor 224. resistor I06. conductor I08. diode I44. resistor I46, resistor I52. pick-up coil 24 and resistor 220. The base of transistor 216 is connected between resistor 232 and capacitor 218. The voltage accumulated on capacitor 218 is of such a polarity as to tend to bias transistor 216 conductive. When transistor 2I6 conducts a bias voltage is developed across resistor 42 of such a polarity as to aid the positive signal voltage 94 that biases transistor I60 conductive. The net result is that as capacitor 218 accumulates more charge the earlier in the half cycle 94 that transistor I60 turns on resulting in an earlier turn-on of transistor III).

The junction 202 of differential amplifier I74 is connected to one end of series connected resistors 240 and 242 the junction of which is connected to the base of NPN transistor 244. When the voltage ofjunction 202, which responds to primary current through resistor I06, reaches a predetermined value transistor 244 is biased conductive. When transistor 244 is biased conductive it causes a partial discharging of capacitor 218 through resistor 232 and conductor 240. This action further modifies the charge on capacitor 218 as a function of primary winding current to vary the point of turn on of transistor III).

The

diodes

250 and 252 are provided for protection from a reverse battery polarity. Zener diode 254 is utilized to provide overvoltage protection since a high voltage causes it to conduct biasing transistor 120 on and transistor I10 off. A filter capacitor 256 is connected across piclcup coil 24.

The specific electronic control circuit shown in FIG. 8 is disclosed and claimed in copending patent application Ser. No. 390.882. Roy C. Richards et a1. filed on Aug. 23. I973 U.S. Pat. No. 3.838.672 and assigned to the assignee of this invention. This control circuit could take other forms as long as it is capable of switching transistor IIO on and off by a signal like that illustrated in FIG. 7.

It now will be apparent that as the rotor 32 rotates the voltage wa\e form of FIG. 7 is generated and controls the conduction of transistor lIt). Thus. as previously mentioned. when the voltage is positive in FIG. 7 as designated by reference numeral 94, the transistor III) is switched on. On the other hand. when the voltage goes negative as designated by refcrencc numeral 96. the output transistor H is switched off to cause the firing of a spark plug.

In order to better understand the significance of the offset air-gap 76 of the ignition coil primary. reference should now be had to FIG. 6 which diagrammatically illustrates various parts of the ignition controller shown in FIG. I and illustrates various flux paths that are set up during the operation oftbe controller. In FIG. 6 the same reference numerals have been used as were used in FIG. I to identify the same parts in each FIGURE. In the operation of the magnetic pulse generator of the ignition controller. it has been discovered that both the field set up by the ignition coil 58 and other stray magnetic fields produced by wires such as those con nected to horns or to other accessories such as an air conditioner can effect the voltage wave form of FIG. 7 and under certain conditions of operation can effect it such that false triggering of the ignition system occurs. With respect to stray magnetic fields it is possible for these fields to link with the shaft 14 and the centrifugal advance mechanism 33 and rotor 32 to cause voltages to be induced in the pick-up coil 24 tending to produce a false trigger signal voltage in the output of the coil 24. To further explain this. it is assumed in FIG. 6 that the upper annular face 26A of the permanent magnet has been magnetized such that it is a north pole and the lower annular face 26B :1 south pole. With this polarity of the magnet. the magnet causes magnetic flux 26F to flow through a path from the top side 26A of magnet 26, through pole piece 28. through the variable airgap between the pole piece 28 and the rotor 32, through the rotor portion 328 ofthe rotor. through the metallic case I8 of the magnetic pick-up assembly and then from this case to the lower south pole 26B of the magnet 26. This flux path is indicated in FIG. 6 with the flux flowing in a clockwise direction relative to the pick-up coil 24. It will. of course. be appreciated that a similar flux path exists completely about the entire magnetic pick-up assembly such that flux in a clockwise direction embraces the entire annular pick-up coil 24 during operation of the system. This flux. of course, varies as the air-gap between the rotor teeth 32A and the teeth 28A vary to induce the voltage wave form shown in FIG. 7 at the two output terminals 24A and 24B of the pick-up coil 24.

The voltage wave form of FIG. 7 must be applied with the proper polarity and phase to the ignition system of FIG. 8. In other words. the junction I32 must be positive with respect to junction 134 when it is desired to turn on transistor 110 and junction 132 must be neg ative with respect to junction 134 when it is desired to turn this transistor off. As will be explained hereinafter, it is possible to assemble a magnet 26A such that the lower face 268 is a north pole and the upper face 26A a south pole. In such a case the magnetic flux path illustrated in FIG. 6 is reversed in direction from the flux path indicated. If such a reversal of the polarity of the magnet is made, it is necessary to reverse the electrical connections to the end conductors of the pick-up coil 24 so that the proper voltage shown in FIG. 7 is applied with its proper polarity to the control system of FIG. 8. Putting it another way. the voltage wave form of FIG. 7 must always be applied to the control system of FIG. 8 such that the junction 132 is positive when it is desired to turn transistor I on and is negative when it is desired to turn transistor I10 off. This means that after the magnet 26A is magnetized with a predetermined polarity. the conductors 24A and 248 must be properly connected to the junctions I32 and 134 of the control system of FIG. 8 in order to insure proper operation.

Since stray magnetic fields from conductors connected to accessories may disturb or distort the voltage wave form of FIG. 7 to produce false triggering of the system, this invention contemplates providing a flux field which effectively opposes the stray fields and reinforces the flux that provides the proper triggering signal for the system. As seen in FIG. 6, and as has been previously explained, the air-gap 76 in the middle leg 80 of the ignition coil core 60 is offset by approximately 0.43 inches from the longitudinal axis of the shaft 14 and the pick-up coil assembly. With this arrangement as illus trated in FIG. 6. and when the primary winding 88 of the ignition coil is energized. there is a certain amount of leakage flux 88F which passes across the air-gap 76. This leakage flux is shown by dotted lines and arrows in FIG. 6 and as depicted in FIG. 6 the leakage flux passes through the centrifugal advance mechanism 33 and through the rotor 32 in a direction indicated. It can be seen from FIG. 6 that the leakage flux is in the same direction as the flux 26F developed by the permanent magnet 26 over an area linking coil 24. This of course. means that this flux which has been developed when transistor I was turned on to energize the ignition coil 88 is in the proper direction to aid the flux 26F produced by the permanent magnet 26 such that this flux causes the voltage wave form of FIG. 7 to properly trigger the electronic control system of FIG. 8. It is pointed out that any stray magnetic fields linking the magnetic system which are in opposite direction to the flux 88F provided by the ignition coil and 26F by the permanent magnet is opposed by the flux generated in the ignition coil when transistor IIO turns on. This means that when transistor 110 is turned on to energize the primary winding any stray magnetic fields which might tend to distort the wave form 96 to cause a false turn off of transistor 110 are opposed by the magnetic flux developed in the ignition coil when transistor 110 is turned on. It has been found that this flux 88F developed by the ignition coil is sufficient to overcome stray magnetic fields that might otherwise cause a false triggering of the system.

The direction of the flux developed as a result of energizing the primary winding of the ignition coil 58 will be determined by the direction of current flow through the primary winding 88 of the ignition coil. This means. of course, that the terminating conductors or the

end terminals

88A and 88B of the primary winding of the ignition coil must be electrically connected such that the current flows in a proper direction between the end conductors 88A and 883. Thus for a given polarity of magnet 26 the current must pass in a direction through primary winding 88 to provide a flux shown in FIG. 6 which aids the flux produced by the permanent magnet 26. If the permanent magnet 26 has its polarity reversed such that the lower side 26B is a north pole, the electrical connections 88A and 888 shown in FIG. 8 must also be reversed so that current flows in an oppo site direction through the primary winding 88 for this condition of operation. Putting it another way, the direction of current flow through the primary winding 88 is dictated by the polarity of the permanent magnet 26 with the primary winding current flow being in one direction when face 26A is a north pole and the current flow being in an opposite direction in primary winding 88 when the face 26A of the permanent magnet is a south pole.

It will be evident that when the connections for the primary winding 88 are reversed. the leakage flux 88F shown in FIG. 6 would be reversed from the direction indicated and the permanent magnet 26 would be oriented such that the flux developed by the permanent magnet 26 would also flow in a reverse direction from that indicated in FIG. 6 with the net result that the flux linking the pick-up coil 24 developed by the permanent magnet and by energization of the primary winding 88 of the ignition coil is in an aiding relationship as this flux links the coil 24. This means that the flux developed by energization of the primary winding of the ignition coil again will be in a right direction to aid the flux of the permanent magnet with the result that the voltage wave form of FIG. 7 may increase in amplitude but is in proper phase to properly trigger the ignition systern. In each case the flux developed by the primary of the ignition coil tends to overcome stray magnetic fields which would otherwise affect the output voltage shown in FIG. 7 developed in the pick-up coil 24.

To this point, the only factors affecting the operation of the magnetic pickup of the ignition controller that have been mentioned are stray magnetic fields pro vided by conductors connected to accessories on the vehicle such as the horn and air conditioners. It has been discovered, however, that certain stray magnetic fields such as those produced by the wiring connecting the battery and the cranking motor of the motor vehicle may cause a false triggering or distortion of the voltage wave form illustrated in FIG. 7 when the engine is being cranked. To further illustrate this problem. reference should be made to FIG. 9 which illustrates the front end ofa motor vehicle including the engine 260, the distributor or ignition controller 262, the battery I00 and the cranking motor 264. The ignition controller 262 represents the device illustrated in FIG. I. It can be seen from FIG. 9 that whenever the cranking motor is energized a current flows through a conductor 266 connecting the battery and cranking motor which is located on one side of the engine and distributor. It has been discovered that the magnetic field produced by conductor 266 may be of such intensity as to induce a voltage in pickup coil 24 which distorts the output voltage shown in FIG. 7 to such an extent as to provide false triggering of the ignition system.

In order to prevent false triggering or difficulty in starting the internal combustion engine due to the magnetic field of the conductor 266 connecting the battery and the cranking motor, the system of this invention is arranged such that the magnetic pickup 24 of controller 262 is so located relative to the conductor 266 that the magnetic field of this conductor always induces a negative voltage 96 in the pickup coil 24 or in other words a voltage of such a polarity as to maintain the transistor 110 nonconductive at the instant that the cranking motor is being energized to start cranking the engine. This means. of course, that on any particular motor vehicle the direction of the magnetic field of the wire connecting the battery and the cranking motor must be determined. Once this determination is made the conductors 24A and 24B of the pickup coil 24 are connected to junctions 132 and 134 such that the voltage induced in the pickup coil 24 by the field of conductor 266 will be such as to bias the transistor I10 nonconductive. In view of the fact that in motor vehicles the battery and cranking motor 264 are located in many different relative positions with respect to the ignition controller 262, it is necessary that the conductors 24A and 248 be connected with the system of FIG. 8 in such an arrangement that a negative voltage is always developed by the field of the cranking motor conductor 266. Thus in some motor vehicles the wire 266 connecting the battery and the cranking motor may be on the opposite side of the engine with the result that the connection of conductors 24A and 248 would have to be reversed with respect to junctions 132 and 134 in the arrangement shown in FIG. 8, in order that a negative voltage is always applied to junction 132 due to any initial cranking of the engine.

In order to properly set the magnetic parameters of the ignition controller 262 the controller must be designed with a predetermined magnetic system relative to the field set up by conductor 266 as will now be described. Assuming first of all that the direction of the magnetic field produced by the conductor 266 connecting the cranking motor 264 and the battery 100 has been determined and the relative position of the distributor 262 with respect to this magnetic field, the end conductors 24A and 243 can now be properly connected with junctions 132 and 134 shown in FIG. 8 to provide a negative voltage on junction 132 due to the field produced by conductor 266. However. once it has been determined which end conductors 24A and 24B of pickup coil 24 are to be connected with certain junc tions I32 and 134 of the electronic system of FIG. 8, the polarity of the permanent magnet 26 must be oriented to provide the proper polarity output voltage to be developed between the two output conductors 24A and 24B. The magnetic field of the starting motor wire 266 therefore determines the polarity of the permanent magnet 26. In other words. the upper face 26A of the magnet 26 may be a north or south pole depending upon the magnetic field that is encountered within the motor vehicle developed in the starting motor conductor 266. Once it has been determined how the end conductors 24A and 24B of pickup coil 24 are to be connected with the system of FIG. 8, the polarity of the magnet 26 is then determined and the magnet 26 is then magnetized with the proper polarity to provide the voltage of FIG. 7 in proper phase for triggering the sys- After the polarity of the magnet has been determined, that is whether face 26A is a north or south pole, it is now necessary to determine the proper direction of current flow through the primary winding 88 of the ignition coil so that the magnetic flux developed by the ignition coil will aid the flux developed by the permanent magnet. Assuming that the magnetic field of the starting motor conductor is such that the upper face 26A of the permanent magnet is a north pole as assumed in FIG. 6, the direction of current flow through the primary winding 88 will be selected such that its magnetic field 88F aids the magnetic field 26F of the permanent magnet as shown in FIG. 6. This, of course, is accomplished by proper connection of the two end conductors of the primary winding 88 with the electrical system shown in FIG. 8. Thus if it is assumed that

conductors

88A and 88B are connected to provide the flux path shown in FIG. 6 then the proper flux from the ignition coil is in the right direction to aid that of the permanent magnet. On the other hand. had the field of the starting motor conductor affected the pickup coil in an opposite direction, the magnet 26 would have its polarity reversed (face 26A a south pole) and the connections 88A and 888 would be reversed with connection 883 being connected to the battery and connection 88A to the collector of transistor I10.

The reason for arranging pick-up coil 24 so that the field from cranking motor 266 induces a negative voltage 96 therein (FIG. 7] is to insure that this field biases output switching transistor 110 non-conductive. The field produced by conductor 266 only exists for a brief period of time at the instant the cranking motor is encrgized to start the engine. Since this field biases transistor I10 non-conductive its effect is to prevent energization of the primary winding 88 at the beginning of the cranking of the engine to prevent misfiring of a spark plug. Thus, were the field of the cranking motor conductor 266 in a direction to induce a positive voltage to turn transistor 110 on at the beginning of the crank ing operation misfiring might occur since the primary winding 88 would be energized due to the cranking motor conductor field and a subsequent turning off of transistor 110 would cause a spark plug to be fired.

Referring again to FIG. 6, the line A represents the center line of the magnetic pick-up parts which is the longitudinal axis of shaft 14. This line A intersects line 77 (FIG. 5) at point B, which is the center of magnetic core 60, when the ignition coil 58 is assembled to the cap 50. The line C in FIG. 6 represents the axis of core air-gap 76 and as previously mentioned the offset represented by dimension D is approximately ().43 inches where the outer dimension of the core 60 is approxi mately 3 inches. The amount of offset D must be selected such that the leakage flux 88F links with the magnetic pick-up to aid the flux generated by perma nent magnet 26. As seen in Hg. 1, the vertical axis of air-gap 76 is aligned approximately with the inner circumferential edge of pick-up coil 24. This has been found to be a satisfactory arrangement for applying the leakage flux 88F to the magnetic pick-up. The point B of magnetic core 60, which is aligned with the longitudinal axis of shaft 14 is also indicated in FIGS. 3 and 5.

One other factor that has been discovered to effect to some extent the output voltage wave form of FIG. 7 is the magnetic field created by the decay of current in the secondary winding of the ignition coil during operation of the system. In order to prevent this magnetic field from causing any substantial false triggering of the magnetic pick-up the secondary winding 90 of the ignition coil is offset in the same direction as the offsetting of the air-gap 76 of the core of the ignition coil. This offset may be approximately 0.1 inch and can be accomplished by insuring that coil 90 abuts surface 62A (FIG. 4) before the coil is potted and further by proper assembly of the ignition coil 58 to cap 50. The center of the axial dimension of the ignition coil secondary winding 90 is offset from the center line or longitudinal axis of the shaft 14 of the ignition controller shown in Hg. 1 in the same direction as the offset of the air-gap 76 of the ignition coil when the ignition coil 58 is assembled to the cap 50. In other words as imaginary upward extension of the longitudinal axis of shaft 14 would radially intersect the secondary winding 90 of coil 58 at a point that is offset from the center of the axial dimension of coil 90.

Since the ignition coil secondary winding 90 is offset in the same direction as air-gap 76 the decay of secondary winding current creates a flux field of its own that is arranged to aid the flux developed by permanent magnet 26 and therefore aid in preventing false triggering. The secondary winding 90 creates this field independent of the field associated with air-gap 76 because of loose coupling between primary winding 88 and secondary winding 90. This decay in secondary current oc curs subsequent to the shut-off of transistor 110.

Since the controller of FIG. 1 contains all the control elements of an ignition system it is only necessary to connect it to the battery and the cap terminals 52 to respective spark plugs by spark plug wires when installing the controller on a motor vehicle engine.

The physical electrical connection to the positive terminal of the battery is made by a wire and connector (not illustrated). This connector engages a portion 300A of a terminal 300 fitted to part 508 of cap 50. The terminal 300 is electrically connected to one end conductor of primary winding 88 for example conductor 88A. The part 50B receives an insulator block 302 having a terminal connected to conductor 304 that engages terminal part 3008 of terminal 300. The parts 300A and 3008 are located at right angles to each other. The conductor 304 passes through an insulator 306 fitted in an opening formed in the part 16 of base 10 (see FIG. 2) and is connected to one terminal of electronic control module 46 in insulator block 309. This connection corresponds to the conductors connecting resistors I26 and 153 to conductor 102 in FIG. 8.

The other end conductor 88B of primary winding 88 is connected to another terminal 316 which is like terminal 300 and which is located next to terminal 300 in part 508 of cap 50. This terminal connects with conductor 310 fitted to a terminal in block 302. The conductor 310 passes through insulator 306 and is electri cally connected to another terminal of module 46 connected to the collector of transistor 110. The conduc tor 310 corresponds to the conductor of FIG. 8 connecting 888 to the collector of transistor 110. The conductor 324 is a ground conductor connected to core 60 by a terminal engaging core 60 which is not illustrated.

The distributor cap 50 is secured to base 10 by a plu rality conventional spring biased parts 318. The lower end of shaft I4 (not illustrated) is fitted with a gear driven by the engine crankshaft. The secondary winding 90 is formed of fine wire insulated by layers of insulation. It is noted that the ignition parts shown in FIGS. 3, 4 and 5 are on an enlarged scale as compared to the same parts shown in FIG. I. The same is true of the parts shown in FIG. 6. The lamination plan view of FIG. Sis on an enlarged scale compared to both FIGS. 1 and 3.

The voltage pulse wave form of FIG. 7 is generated by the change in flux linking coil 24. As rotor teeth 32A approach pole-piece teeth 268 the flux linking the coil increases and as teeth 32A leave teeth 288 the flux decreases. As engine speed increases the amplitude of the

pulses

94 and 96 increase and their frequency increases with the result that they occur closer together than depicted in FIG. 7.

The false triggering that might otherwise occur due to stray magnetic fields has its greatest effect at cranking or at low speeds of the engine At higher speeds the voltage pulses are strong enough not to be substantially affected by stray magnetic fields.

The point at which transistor 110 is switched depends on the sensitivity of the control circuit 46 to the signal shown in FIG. 7. In the system of this invention the transistor I I0 is switched just after the voltage crosses or departs from the zero line or in other words close to the beginning of a

voltage pulse

94 or 96. This, of

course, depends on bias conditions of control 46 as has been explained.

The critical point in the operation of this system is the point at which transistor is biased nonconductivc because it is at this point that a spark plug is tired. This occurs just after the beginning of pulse 96 providing no magnetic field is permitted to distort the wave form of FIG. 7 of such magnitude as to cause switching.

As has been explained the leakage flux 88F about airgap 76 induces a voltage in coil 24 when ignition coil primary 88 is energized. This voltage is shown in dotted lines and identified as 94A in FIG. 7. This pulse occurs shortly after transistor 110 was biased conductive and exists until primary current reaches a steady-state value. This pulse 94A will not cause false triggering because transistor ll0 is already biased on and pulse 94A is in the same direction as positive voltage 94. The leakage flux, however. tends to oppose any field that might tend to turn transistor 110 off. that is. a field inducing a negative voltage 96.

Any field inducing a voltage in the direction of negative voltage 96 occurring after transistor I10 is biased non-conductive by the beginning of pulse 96 will not affect the system because with transistor I10 previously biased non-conductive a spark plug has already been fired.

By offsetting the air-gap 76 in the proper direction the system will not be false triggered by the field of primary winding 88. Were the offset in the wrong direction this field might cause false triggering of the system.

It has been pointed out that the voltage induced in coil 24 and the direction of the field produced by primary winding 88 can be reversed by reversing their end leads. This has assumed that these coils have remained in the same physical position after reversal of the leads. This reversal can be made by reversing the external leads (24A and 248 or 88A and 888) as explained, or by reversing the end wires of the coils connected to the external leads.

The magnitude and polarity of the voltage induced in pick-up coil 24 by leakage flux 88F (FIG. 6) depends on the position of the airgap 76 relative to axis of the magnetic pick-up. If air-gap 76 were exactly aligned with the longitudinal axis of the magnetic pick-up the effect of the leakage flux 88F in inducing a voltage in coil 24 would be zero because this flux would then link coil 24 in one direction on one side thereof and in an opposite direction on an opposite side thereof. The airgap 76 must therefore be offset by an amount D that is sufficient to cause the net flux 26F and 88F linking coil 24 to increase the voltage generated in pick-up coil 24. This is depicted as voltage 94A in FIG. 6 which is a voltage added to voltage 94 provided by permanent magnet flux 26F.

What is claimed is:

I. An ignition controller for an internal combustion engine comprising. a base member. a magnetic pick-up supported by said base member comprising. a pick-up coil and a permanent magnet. a rotor formed of magnetic material rotatable with respect to said base memher. a magnetic circuit providing a path for flux linking said pick-up coil comprising said rotor and permanent magnet and including at least one air gap which varies as a function of rotor position whereby an alternating control voltage is induced in said pick-up coil when said rotor is rotated, an ignition coil supported from said base member spaced from said magnetic pick-up. said ignition coil having a magnetic core provided with an air gap, said core carrying the primary and secondary windings of said ignition coil. and ignition control means comprising a switching means. means connecting said pick-up coil and said switching means for caus ing said switching means to be biased substantially conductive when said alternating control voltage has a first polarity and substantially non-conductive and said alternating control voltage has a second opposite polarity. means connecting said switching means and said primary winding whereby said primary winding is ener gized when said switching means is conductive and is substantially deencrgized when said switching means is substantially non-conductive when said switching means and primary winding are operatively connected to a voltage source. said air gap of said core of said ignition coil being so positioned with respect to said magnetic circuit that the leakage flux developed during en ergization of said primary winding across the air gap of said ignition coil core is applied to said magnetic circuit in such a direction and magnitude as to aid the flux in said magnetic circuit provided by said permanent magnet in generating a voltage of said first polarity to thereby prevent false triggering of said control means by stray magnetic fields.

2. An ignition controller for an internal combustion engine comprising. a base member. a magnetic pick-up supported by said base member comprising an annular permanent magnet. an annular pick-up coil and a rotor. said permanent magnet and pick-up coil having a common longitudinal axis. a magnetic circuit linking said pick-up coil disposed between opposite poles of said permanent magnet including said rotor for causing an alternating control voltage to be induced in said pickup coil when said rotor is rotated, an ignition coil sup ported from said base member and spaced from said magnetic pick-up. said ignition coil including a magnetic core member having an air gap. primary and secondary windings disposed about said magnetic core member. switching means connected with said pick-up coil for connecting and disconnecting said primary winding with a source of voltage in response to said control voltage. the longitudinal axis of said primary and secondary windings and said core member being substantially normal to said longitudinal axis of said permanent magnet and pick-up coil. said ignition coil being so positioned with respect to said magnetic pickup that said air gap of said ignition coil core member is spaced radially from the longitudinal axis of said magnet and pick-up coil by a predetermined amount. the spacing of said air gap from the longitudinal axis of said magnet and pick-up coil being sufficient to cause flux developed by the energization of said primary winding of said ignition coil to aid the flux provided by said permanent magnet in inducing a control voltage in said pick-up coil biasing said switching means conduclive.

3. An ignition controller for an internal combustion engine comprising. a base member. an annular pick-up coil supported by said base member. an annular permanent magnet. said coil winding and magnet having a common longitudinal axis. a rotor formed of magnetic material rotatable with respect to said base member. means including a pole-piece and said rotor forming a magnetic circuit for flux generated by said permanent magnet. said flux linking said coil winding. said rotor being shaped to provide a varying air gap for said magnetic circuit whereby an alternating control voltage is induced in said pickup coil as said rotor rotates. an ignition coil supported from said base member, said ignition coil having a magnetic core comprised of a pair of substantially E-shaped core parts having a center leg that has an air gap. primary and secondary windings wound on said center leg of said core. said core being so positioned with respect to said permanent magnet and pick-up coil winding that said air gap in said center leg of said core is offset radially a predetermined amount from said longitudinal axis of said permanent magnet and pick-up coil whereby leakage flux adjacent said core air gap aids the flux provided by said permanent magnet in said magnetic circuit linking said pickup coil in generating said control voltage when said primary winding is energized with a voltage of a predetermined magnitude and polarity said leakage flux opposing stray magnetic fields tending to generate a voltage in said pick-up coil opposite to that produced by said leakage flux.

4. An ignition system for an internal combustion engine of a motor vehicle that is equipped with a battery and an electric cranking motor. the combination com prising. an ignition controller on said vehicle having a base. a shaft supported by said base driven in synchronism with said engine. said base supporting a magnetic pick-up. said magnetic pick-up comprising. a permanent magnet. a pick-up coil and a rotor formed of magnetic material driven by said shaft. said magnetic pickup arranged such that an alternating control voltage is induced in said pick-up coil as said rotor is rotated by said shaft. an ignition coil having a magnetic core provided with an air gap having a primary winding and a secondary winding carried thereby. said ignition coil supported from said base and spaced from said magnetic pickup. power supply conductors connected to said battery, an ignition control means connected to said power supply conductors comprising a semiconductor switch means. means connecting said primary winding and said semiconductor switch means in series across said power supply conductors whereby said pri mary winding is energized when said semiconductor switch means is biased conductive and is substantially deenergized when said semiconductor switch means is biased non-conductive to induce a spark firing impulse in said secondary winding. means connected between said pick-up coil and said semiconductor switch means for causing said semiconductor switch means to be biased conductive when said control voltage has a first polarity and biased non-conductive when said control voltage has a second opposite polarity, and cranking motor conductor means connecting said battery and electric cranking motor. said magnetic pick-up being so positioned and arranged relative to said cranking motor conductor means that any voltage induced in said pickup coil by the field produced by initial current flow through said cranking motor conductor means is of such a polarity as to tend to bias said semiconductor switch means non-conductive. said magnetic pick-up and ignition coil being so positioned that leakage flux developed across said ignition coil air gap when said primary winding is energized is of such a direction and magnitude as to aid the flux developed by said permanent magnet in generating a voltage of a polarity tending to bias said semiconductor switch means conductive.

5. An ignition control arrangement for an internal combustion engine comprising. an ignition controller having a base member. a magnetic pick-up supported by said base member. said magnetic pick-up comprising a permanent magnet and a pick-up coil. a rotor driven by said engine cooperating with said permanent magnet and pick-up coil to cause an alternating control voltage to be generated in said picloup coil when said rotor is rotated. a distributor cap supported by said base member. an ignition coil having a primary winding and a secondary winding carried by a magnetic core. said core having an air gap. said ignition coil supported by said distributor cap. control circuit means having an input connected to said pick up coil. said control circuit means including an electronic switching device connected in series with said primary winding whereby said primary winding is energized when said switching device is biased conductive and is deenergized to cause a spark firing pulse to be induced in said secondary winding when said switching device is biased non conductive. said control circuit being so arranged that said switching device is biased conductive when said control voltage has a first polarity and nonconductive when said control voltage has an opposite second po larity. said air gap of the magnetic core of said ignition coil being so positioned and arranged with respect to said permanent magnet and pick-up coil that leakage flux produced across said air gap by the energization of said primary winding when said switching device is bi ased conductive by said first polarity voltage links said pick-up coil and is of such a direction and magnitude as to tend to induce a voltage in said pick-up coil of said first polarity whereby said leakage flux opposes stray magnetic fields tending to induce a voltage in said pickup coil of said opposite second polarity.

6. An ignition controller for an internal combustion engine comprising. a base member, a shaft adapted to be driven in synchronism with said engine rotatably supported by said base member. a distributor cap supported by said base member including terminals adapted to be connected with spark plugs of said engine. a magnetic pick-up supported by said base memher. said magnetic pickup comprising an annular permanent magnet and an annular pick-up coil located substantially concentric with said shaft. a first rotor driven by said shaft formed of magnetic material cooperating with said magnet and picleup coil to cause control voltage pulses to be induced in said pick-up coil as said rotor is rotated. an ignition coil supported by said distributor cap. said ignition coil comprising a magnetic core having an air gap and primary and secondary windings carried thereby. said core extending substantially normal to the longitudinal axis of said permanent magnet and pick-up coil. said air gap being spaced radi ally from the longitudinal axis of said permanent magnet and pick-up coil by a predetermined amount sufficient to cause leakage flux produced by energization of said primary winding to link said pick-up coil. said leakage flux aiding the flux of said permanent magnet over an area linking said pick-up coil in generating a control voltage pulse. and a second rotor formed of insulating material driven by said shaft carrying conductor means operative to electrically connect the secondary winding of said ignition coil and said distributor cap terminals.

7. An ignition controller for an internal combustion engine comprising. a base member. a magnetic pick-up supported by said base member. said magnetic pick-up comprising a pick-up coil. 21 permanent magnet and a rotor formed of magnetic material. a magnetic circuit linking said pick-up coil connected between opposite poles of said permanent magnet comprising said rotor and including an air gap which varies as a function of rotor position. said pick-up coil having an alternating control voltage induced therein as said rotor rotates. an ignition coil supported from said base member and spaced from said magnetic pick-up. said ignition coil comprising a magnetic core having an air gap with primary and secondary windings carried thereby. said ignition coil being positioned such that said core member extends substantially normal to the longitudinal axis of said magnetic pick-up. said air gap in said core member having an axis which is radially offset a predetermined amount from the longitudinal axis of said magnetic pick-up, said secondary winding being located such that it is offset from the center of said magnetic core in the same direction as the offset of said core air gap from the longitudinal axis of said magnetic picleup.

8. An ignition distributor for an internal combustion engine comprising. a base member formed of nonmagnetic material. said base member having a longitudi nally extending section rotatably supporting a distribu tor shaft and an annular support section. a magnetic pick-up supported by said support section. said magnetic pick-up comprising an annular coil winding. an annular permanent magnet and an annular pole-piece all located substantially concentric with the longitudinal axis of said shaft, a rotor member formed of magnetic material driven by said shaft. said rotor member having circumferentially spaced teeth spaced from teeth formed on said pole-piece. a distributor cap formed of insulating material supported by the support section of said base member, an ignition coil supported from an outer wall of said distributor cap. said ignition coil comprising a core member extending generally normal to the longitudinal axis of said magnetic pickup and having an air gap. primary and secondary windings carried by said core, the axis of said air gap being radially spaced from the longitudinal axis of said shaft by a predetermined amount. said secondary winding of said ignition coil being offset axially of the center of said core in the same direction as the offsetting of said air gap from said longitudinal axis of said shaft.

9. An ignition controller for an internal combustion engine comprising. a base member. a distributor shaft rotatably supported by said base member. a magnetic pick-up mounted concentric with said shaft, said magnetic pick-up comprising an annular coil winding. an annular permanent magnet and an annular pole-piece located above said shaft. a rotor formed of magnetic material disposed within said pole-piece. said polepiece and rotor including means providing a variable air gap therebetween as said rotor is rotatably driven by said shaft. a distributor cap supported from said base member and enclosing said magnetic pick-up. and an ignition coil supported from an outer wall of said distributor cap. said ignition coil including a magnetic core having three legs joined by end sections. said igni tion coil being so positioned that the longitudinal axis of said magnetic pick-up is in alignment with the center of the middle leg of said core of said ignition coil. said middle leg of said ignition coil carrying primary and secondary windings and having an air gap. said air gap being offset a predetermined amount from the center of the middle leg of said core member and offset from 21 the longitudinal axis of said magnetic pickup by said predetermined amount. the secondary winding of said ignition coil being offset along said middle leg of said core in the same direction as the offset of said core air gap.

10. An ignition distributor for an internal combustion engine comprising. a base. a shaft adapted to be connected with an engine rotatably supported by said base. a magnetic pick-up assembly supported by said base. said pick-up assembly comprising an annular coil wind ing. an annular permanent magnet and an annular polepiece. said coil, magnet and pole-piece having a common longitudinal axis. a rotor formed of magnetic material driven by said shaft disposed within said polepiece, said rotor and pole-piece having opposed teeth arranged such to provide a variable air gap therebetween as said rotor is rotated. a distributor cap sup- 22 ported by said base. and an ignition coil supported by said distributor cap. said ignition coil having a magnetic core provided with two outer legs and a center leg located therebetween. said legs joined by end sections. said center leg having an air gap and carrying primary and secondary windings. said core being located in a plane that is substantially normal to the longitudinal axis of said magnet. pick-up coil and pole-piece. the axis of said air gap being radially spaced from said longitudinal axis by a predetermined amount. said air gap axis located within said annular permanent magnet whereby leakage flux across said air gap developed by energization of said primary winding induces a voltage in said pick-up coil. said leakage flux aiding the flux provided by said permanent magnet.

Claims

1. An ignition controller for an internal combustion engine comprising, a base member, a magnetic pick-up supported by said base member comprising, a pick-up coil and a permanent magnet, a rotor formed of magnetic material rotatable with respect to said base member, a magnetic circuit providing a path for flux linking said pick-up coil comprising said rotor and permanent magnet and including at least one air gap which varies as a function of rotor position whereby an alternating control voltage is induced in said pick-up coil when said rotor is rotated, an ignition coil supported from said base member spaced from said magnetic pickup, said ignition coil having a magnetic core provided with an air gap, said core carrying the primary and secondary windings of said ignition coil, and ignition control means comprising a switching means, means connecting said pick-up coil and said switching means for causing said switching means to be biased substantially conductive when said alternating control voltage has a first polarity and substantially non-conductive and said alternating control voltage has a second opposite polarity, means connecting said switching means and said primary winding whereby said primary winding is energized when said switching means is conductive and is substantially deenergized when said switching means is substantially non-conductive when said switching means and primary winding are operatively connected to a voltage source, said air gap of said core of said ignition coil being so positioned with respect to said magnetic circuit that the leakage flux developed during energization of said primary winding across the air gap of said ignition coil core is applied to said magnetic circuit in such a direction and magnitude as to aid the flux in said magnetic circuit provided by said permanent magnet in generating a voltage of said first polarity to thereby prevent false triggering of said control means by stray magnetic fields.

2. An ignition controller for an internal combustion engine comprising, a base member, a magnetic pick-up supported by said base member comprising an annular permanent magnet, an annular pick-up coil and a rotor, said permanent magnet and pick-up coil having a common longitudinal axis, a magnetic circuit linking said pick-up coil disposed between opposite poles of said permanent magnet including said rotor for causiNg an alternating control voltage to be induced in said pick-up coil when said rotor is rotated, an ignition coil supported from said base member and spaced from said magnetic pick-up, said ignition coil including a magnetic core member having an air gap, primary and secondary windings disposed about said magnetic core member, switching means connected with said pick-up coil for connecting and disconnecting said primary winding with a source of voltage in response to said control voltage, the longitudinal axis of said primary and secondary windings and said core member being substantially normal to said longitudinal axis of said permanent magnet and pick-up coil, said ignition coil being so positioned with respect to said magnetic pick-up that said air gap of said ignition coil core member is spaced radially from the longitudinal axis of said magnet and pick-up coil by a predetermined amount, the spacing of said air gap from the longitudinal axis of said magnet and pick-up coil being sufficient to cause flux developed by the energization of said primary winding of said ignition coil to aid the flux provided by said permanent magnet in inducing a control voltage in said pick-up coil biasing said switching means conductive.

3. An ignition controller for an internal combustion engine comprising, a base member, an annular pick-up coil supported by said base member, an annular permanent magnet, said coil winding and magnet having a common longitudinal axis, a rotor formed of magnetic material rotatable with respect to said base member, means including a pole-piece and said rotor forming a magnetic circuit for flux generated by said permanent magnet, said flux linking said coil winding, said rotor being shaped to provide a varying air gap for said magnetic circuit whereby an alternating control voltage is induced in said pick-up coil as said rotor rotates, an ignition coil supported from said base member, said ignition coil having a magnetic core comprised of a pair of substantially E-shaped core parts having a center leg that has an air gap, primary and secondary windings wound on said center leg of said core, said core being so positioned with respect to said permanent magnet and pick-up coil winding that said air gap in said center leg of said core is offset radially a predetermined amount from said longitudinal axis of said permanent magnet and pick-up coil whereby leakage flux adjacent said core air gap aids the flux provided by said permanent magnet in said magnetic circuit linking said pick-up coil in generating said control voltage when said primary winding is energized with a voltage of a predetermined magnitude and polarity said leakage flux opposing stray magnetic fields tending to generate a voltage in said pick-up coil opposite to that produced by said leakage flux.

4. An ignition system for an internal combustion engine of a motor vehicle that is equipped with a battery and an electric cranking motor, the combination comprising, an ignition controller on said vehicle having a base, a shaft supported by said base driven in synchronism with said engine, said base supporting a magnetic pick-up, said magnetic pick-up comprising, a permanent magnet, a pick-up coil and a rotor formed of magnetic material driven by said shaft, said magnetic pick-up arranged such that an alternating control voltage is induced in said pick-up coil as said rotor is rotated by said shaft, an ignition coil having a magnetic core provided with an air gap having a primary winding and a secondary winding carried thereby, said ignition coil supported from said base and spaced from said magnetic pick-up, power supply conductors connected to said battery, an ignition control means connected to said power supply conductors comprising a semiconductor switch means, means connecting said primary winding and said semiconductor switch means in series across said power supply conductors whereby said primary winding is energized when said semiconductor switch means is biased conductive aNd is substantially deenergized when said semiconductor switch means is biased non-conductive to induce a spark firing impulse in said secondary winding, means connected between said pick-up coil and said semiconductor switch means for causing said semiconductor switch means to be biased conductive when said control voltage has a first polarity and biased non-conductive when said control voltage has a second opposite polarity, and cranking motor conductor means connecting said battery and electric cranking motor, said magnetic pick-up being so positioned and arranged relative to said cranking motor conductor means that any voltage induced in said pick-up coil by the field produced by initial current flow through said cranking motor conductor means is of such a polarity as to tend to bias said semiconductor switch means non-conductive, said magnetic pick-up and ignition coil being so positioned that leakage flux developed across said ignition coil air gap when said primary winding is energized is of such a direction and magnitude as to aid the flux developed by said permanent magnet in generating a voltage of a polarity tending to bias said semiconductor switch means conductive.

5. An ignition control arrangement for an internal combustion engine comprising, an ignition controller having a base member, a magnetic pick-up supported by said base member, said magnetic pick-up comprising a permanent magnet and a pick-up coil, a rotor driven by said engine cooperating with said permanent magnet and pick-up coil to cause an alternating control voltage to be generated in said pick-up coil when said rotor is rotated, a distributor cap supported by said base member, an ignition coil having a primary winding and a secondary winding carried by a magnetic core, said core having an air gap, said ignition coil supported by said distributor cap, control circuit means having an input connected to said pick-up coil, said control circuit means including an electronic switching device connected in series with said primary winding whereby said primary winding is energized when said switching device is biased conductive and is deenergized to cause a spark firing pulse to be induced in said secondary winding when said switching device is biased non-conductive, said control circuit being so arranged that said switching device is biased conductive when said control voltage has a first polarity and non-conductive when said control voltage has an opposite second polarity, said air gap of the magnetic core of said ignition coil being so positioned and arranged with respect to said permanent magnet and pick-up coil that leakage flux produced across said air gap by the energization of said primary winding when said switching device is biased conductive by said first polarity voltage links said pick-up coil and is of such a direction and magnitude as to tend to induce a voltage in said pick-up coil of said first polarity whereby said leakage flux opposes stray magnetic fields tending to induce a voltage in said pick-up coil of said opposite second polarity.

6. An ignition controller for an internal combustion engine comprising, a base member, a shaft adapted to be driven in synchronism with said engine rotatably supported by said base member, a distributor cap supported by said base member including terminals adapted to be connected with spark plugs of said engine, a magnetic pick-up supported by said base member, said magnetic pick-up comprising an annular permanent magnet and an annular pick-up coil located substantially concentric with said shaft, a first rotor driven by said shaft formed of magnetic material cooperating with said magnet and pick-up coil to cause control voltage pulses to be induced in said pick-up coil as said rotor is rotated, an ignition coil supported by said distributor cap, said ignition coil comprising a magnetic core having an air gap and primary and secondary windings carried thereby, said core extending substantially normal to the longitudinal axis of said permanEnt magnet and pick-up coil, said air gap being spaced radially from the longitudinal axis of said permanent magnet and pick-up coil by a predetermined amount sufficient to cause leakage flux produced by energization of said primary winding to link said pick-up coil, said leakage flux aiding the flux of said permanent magnet over an area linking said pick-up coil in generating a control voltage pulse, and a second rotor formed of insulating material driven by said shaft carrying conductor means operative to electrically connect the secondary winding of said ignition coil and said distributor cap terminals.

7. An ignition controller for an internal combustion engine comprising, a base member, a magnetic pick-up supported by said base member, said magnetic pick-up comprising a pick-up coil, a permanent magnet and a rotor formed of magnetic material, a magnetic circuit linking said pick-up coil connected between opposite poles of said permanent magnet comprising said rotor and including an air gap which varies as a function of rotor position, said pick-up coil having an alternating control voltage induced therein as said rotor rotates, an ignition coil supported from said base member and spaced from said magnetic pick-up, said ignition coil comprising a magnetic core having an air gap with primary and secondary windings carried thereby, said ignition coil being positioned such that said core member extends substantially normal to the longitudinal axis of said magnetic pick-up, said air gap in said core member having an axis which is radially offset a predetermined amount from the longitudinal axis of said magnetic pick-up, said secondary winding being located such that it is offset from the center of said magnetic core in the same direction as the offset of said core air gap from the longitudinal axis of said magnetic pick-up.

8. An ignition distributor for an internal combustion engine comprising, a base member formed of nonmagnetic material, said base member having a longitudinally extending section rotatably supporting a distributor shaft and an annular support section, a magnetic pick-up supported by said support section, said magnetic pick-up comprising an annular coil winding, an annular permanent magnet and an annular pole-piece all located substantially concentric with the longitudinal axis of said shaft, a rotor member formed of magnetic material driven by said shaft, said rotor member having circumferentially spaced teeth spaced from teeth formed on said pole-piece, a distributor cap formed of insulating material supported by the support section of said base member, an ignition coil supported from an outer wall of said distributor cap, said ignition coil comprising a core member extending generally normal to the longitudinal axis of said magnetic pick-up and having an air gap, primary and secondary windings carried by said core, the axis of said air gap being radially spaced from the longitudinal axis of said shaft by a predetermined amount, said secondary winding of said ignition coil being offset axially of the center of said core in the same direction as the offsetting of said air gap from said longitudinal axis of said shaft.

9. An ignition controller for an internal combustion engine comprising, a base member, a distributor shaft rotatably supported by said base member, a magnetic pick-up mounted concentric with said shaft, said magnetic pick-up comprising an annular coil winding, an annular permanent magnet and an annular pole-piece located above said shaft, a rotor formed of magnetic material disposed within said pole-piece, said pole-piece and rotor including means providing a variable air gap therebetween as said rotor is rotatably driven by said shaft, a distributor cap supported from said base member and enclosing said magnetic pick-up, and an ignition coil supported from an outer wall of said distributor cap, said ignition coil including a magnetic core having three legs joined by end sections, said ignition coil being so positioned that the longiTudinal axis of said magnetic pick-up is in alignment with the center of the middle leg of said core of said ignition coil, said middle leg of said ignition coil carrying primary and secondary windings and having an air gap, said air gap being offset a predetermined amount from the center of the middle leg of said core member and offset from the longitudinal axis of said magnetic pick-up by said predetermined amount, the secondary winding of said ignition coil being offset along said middle leg of said core in the same direction as the offset of said core air gap.

10. An ignition distributor for an internal combustion engine comprising, a base, a shaft adapted to be connected with an engine rotatably supported by said base, a magnetic pick-up assembly supported by said base, said pick-up assembly comprising an annular coil winding, an annular permanent magnet and an annular pole-piece, said coil, magnet and pole-piece having a common longitudinal axis, a rotor formed of magnetic material driven by said shaft disposed within said pole-piece, said rotor and pole-piece having opposed teeth arranged such as to provide a variable air gap therebetween as said rotor is rotated, a distributor cap supported by said base, and an ignition coil supported by said distributor cap, said ignition coil having a magnetic core provided with two outer legs and a center leg located therebetween, said legs joined by end sections, said center leg having an air gap and carrying primary and secondary windings, said core being located in a plane that is substantially normal to the longitudinal axis of said magnet, pick-up coil and pole-piece, the axis of said air gap being radially spaced from said longitudinal axis by a predetermined amount, said air gap axis located within said annular permanent magnet whereby leakage flux across said air gap developed by energization of said primary winding induces a voltage in said pick-up coil, said leakage flux aiding the flux provided by said permanent magnet.