US3854465A

US3854465A - Electronic ignition system

Info

Publication number: US3854465A
Application number: US00255396A
Authority: US
Inventors: G Adams
Original assignee: Solitron Devices Inc
Current assignee: Solitron Devices Inc
Priority date: 1972-05-22
Filing date: 1972-05-22
Publication date: 1974-12-17
Anticipated expiration: 1991-12-17

Abstract

A solid state control unit for a high potential generating system which is connected in series with an impulse signal and coil to maximize coil charging time between discharges thereof by means which eliminates eratic impulses from affecting the system and includes means to adjust the timing of the impulses for maximum efficiency and performance.

Description

nited States Patent 1191 Adams [451 Dec. 17,1974

Guy Adams, Monroe, NY.

[52] U.S. Cl.... 123/148 E, 123/146.5 A, 123/117 R [51] Int. Cl. F02p 3/02, F02p 5/08 [58] Field of Search 123/148 E, 146.5 A, 117 R 3,605,713 9/1971 LeMasters 123/148 E 3,651,341 3/1972 Shana 3,660,689 5/1972 ()ishi 1, 123/148 E Primary Examiner-Laurence M. Goodridge Assistant Examiner-Cort Flint Attorney, Agent, or Firm-Richard G. Geib 57 7 ABSTRACT A solid state control unit for a high potential generating system which is connected in series with an impulse signal and coil to maximize coil charging time [56] References Clted between discharges thereof by means which eliminates UNITED STATES PATENTS eratic impulses from affecting the system and includes 3,202,146 8/1965 Short et a1 1. 123/148 E means to adjust the timing of the impulses for maxi- 3,3l4,407 4/1967 Schneider 123/148 E mum efficiency and performance 3,521,611 7/1970 Finch 123/148 E 3,587,551 6/1971 Harrow 123/148 E 10 Claims, 8 Drawing Figures /4 32 34 m) f 30 X6) 2 e 2 2g /2 i" ELECTRONIC IGNITION SYSTEM BACKGROUND OF INVENTION Ignition systems for internal combustion engines operate, as is well known, on the principle of stored inductive energy transfer. In such systems presently employed and proposed an impulse signal is generated by mechanical contacts, magnetic means and photosensitive devices to provide and interrupt current flow to a circuit connected to an ignition coils primary winding. The providing of the current is known as the charging of the coil and the interruption of same permits the coil to discharge whereby a spark plug is energized to initiate combustion in an engine cylinder. Various types of transistorized circuits have been proposed whereby the charging and discharging aforesaid is controlled by the transistor circuit in series connection with the signal generating means and the coil. his to the improvement of these and other similar prior art systems that the present invention is directed whereby the time required to charge a coil is maximized to provide a higher output potential which man engine ignition system, for example. provides easier-engine starts and stable operation at higher speeds than is now possible by any prior art systems known.

It is a more particular object of this invention to provide a new and improved semiconductor control system that if employed with an ignition system has the capability of eliminating all but a triggering electrical impulse, the capability of varying the lead-lag of the triggering electrical impulse and the capability of fixed pulse width ignition coil discharge where'by longer coil charging time is possible at every conceivable engine speed.

A still more particular object of this invention is to delay the output signal'of a signal generator, amplify it, convert it into a square wave signal, differentiate it thereafter, direct it through a one-shot monostable network, amplify it and gate it in the control of an electrical device such as an engine ignition coil.

DRAWING DESCRIPTION FIG. 1 is a block diagram of an electronic ignition system employing the principals of this invention.

FIGS. 2 through 7 are illustrations of the electrical wave forms that will result at various points in the electronic ignition system according to this invention.

FIG. 8 is schematic diagram of the electronic control system according to a preferred form of this invention in series connection with the impulse generating means and the coil.

DETAILED DESCRIPTION In reference to FIG. I there is shown a set of conventional ignition points 10 operable by a cam means 12 as is well known in the prior art. An electrical impulse generated by the points 10 is applied to an RC cornering network 14 whereby the effect of point dither or bounce is smoothed. Next the impulse is directed to a variable resistance network whereby one can advance or retard the impulse applied to an amplifier 18. The amplified impulse is then supplied to a Schmidt trigger to drive same to produce an output delivered to differentiation network 22 which then generates a sharp pulse driving a one-shot monostable network 24. The output of network 24 is then delivered to an amplification and electronic switching network 26 which then drives coil switching network 28 that is in control of the charging of primary winding 30 or the curtailment of same. This will, as is readily appreciated by those skilled in the art, in the first instance create a magnetic field in coil 32 when the coil is charging and a collapse of same when curtailed to induce a high ignition potential in secondary winding 34 that is supplied to spark plugs 36, for example, causing them to spark.

It is thus realized'that an electrical square wave form 38 provided by the points 10, as seen by FIG. 2, is changed to a sloping waveform 40 illustrated in FIG. 3 which is generated by the RC corneringnetwork 14. Electrical wave form 40 has a triggering position 42 which is variable by means of network 1 6 for operation of Schmidt trigger network 20 to restore a square wave form 44 displaced in time. The differentiation network 22 then provides a sharp narrow triggering pulse wave form of positive and

negative spikes

46 and 48 which are provided to the one-shot monostable network 24. This generates a gate waveform 50, as seen by FIG. 6 whose sign is corrected by the'network 26 to provide the wave form 52 of FIG; 7. As is obvious from a comparison of FIGS. 2 through 7 the duration of the pulse shown by wave form 52 no longer has the broad pulse width or position as the initiating square wave form 38. In that the pulse provided by wave form 52 controls the time the primary coil 32 current is interrupted it is possible to increase the charging time for the primary coil 32.

In order to effectuate this advantageous operation .a semiconductor circuit is now to be described in re-ference to FIG. 8. Ignition points 10 are shown connected via an ignition switch 54 to a battery 56 and ground .58 by means of resistor 60 in lead 62 and lead 64, respectively. Zener diode 66 in lead 68 connects the ground potential to lead 62 to maintain constant voltage at junction 70. Opening and closing of points 10 produces an electrical impulse for the RC cornering network comprised of resistor 72 and capacitor 74. This network in a preferred embodiment, creates a 400 psec delay so that the electrical impulse is smoothed and zener diode 66 maintains the constant voltage. This is fed to variable resistor 76 whose sliding contact 78 is connected by lead 80 to a capacitor 82 which is tapped at 84 by lead 86. A discharge diode 88 is connected at juncture 90 to lead 68 between the zener diode 66 and juncture 70. Therefore, an impulse from the points 10 of a square wave form is converted to a slopping or ramp wave form by the RC cornering network of resistor 72 and capacitor 74 having a predetermined delay with a constant voltage as maintained by the zener diode 66 which by means of resistor slider 78 provides an output voltage no more than and normally less than the aforementioned constant voltage. This output is then connected by conductor 90 to the base of an emitter-follower amplifier shown schematically as at 92 having a collector 94 connected by

conductors

96 and 98 to resistor 100 connected to the positive conductor 102 from ignition switch 54. Resistor 100 is connected to negative conductor 104 by conductor 106 and zener diode 108. The amplifier circuit is completed by connecting

conductors

102 and 104 by a conductor 110 having a reverse transient protection diode 112 whereby the amplifier 92 is triggered to amplify the pulse from variable resistor 66 whereby an output is provided at emitter 114 and fed by conductor I16 to base 118 of transistor 120 of the Schmidt trigger circuit 20. As is familiar to those skilled in the art,

transistors

120 and 136 are interposed between

conductors

98 and 104. Transistor 120 has its collector 128 connected to such circuit and its emitter 130 connected by a conductor 132 to emitter 134 of a transistor 136 whose collector 138 is connected to resistor 140 and thence conductor 98. A conductor 140 connects resistor 124 to base 142 of transistor 136. The Schmidt trigger circuit is completed then by providing resistor 146 between

conductors

132 and 104. It may therefore be realized that a positive input pulse provided to base118 of transistor 120 must be of a sufficient level to overcome the reverse bias provided by resistor 146, and when of a sufficient level it applies a forward bias making transistor 120 conductive developing a voltage drop across resistor 122 decreasing the positive potential across base 142 of transitor 136 until transistor 136 stops conducting at which point there is no voltage drop across resistor 140 and the potential in collector 138 equals that in conductor 98, and an output signal is formed for the duration of the input pulse. Therefore, a square wave 44 is created displaced in time in relation to the point 42 on the ramp wave 40. This drives capacitor .148 providing a spike 46, controlled by resistor 150 to a predetermined time duration, which is found at juncture 152. A steering diode 155 is connected to juncture 152 and a conductor 154 connects it to emitter 156 of transistor 158 whose base is connected to conductor 160 between capacitor 162 and resistor 164 respectively connected to

conductors

104 and 98. Conductor 166 taps into conductor 154 at juncture 168 and leads to emitter 170 of transistor 172. Collector 174 of transistor 158 is connected via resistors 176 conductor 98 and resistor 178 to collector 180 of transistor 172. A capacitor 182 in conductor 184 connects collector 174 to base 186 of transistor 170, and a shunt diode 188 is connected between conductor 166 and base 186 between same and capacitor 182. In such circuitry, as this one-shot monostable network 24, the triggering signal, i.e.. spike wave form 46, induces a transition from a stable state to a quasi stable state for a time on the order of 400 usec which automatically returns to the stable state thereafter while at the same time generating the rectangular wave form 50 whose beginning and end are marked by abrupt discontinuity in voltage waveform. The triggering spike 46 drives capacitor 162 and is introduced to base 190 where it affects only transistor 158 of this network 24, so as to not load the circuit. The time of the quasi stable state is controlled through resistor 176 when transistor 158 is conducting. At the same time the resistance on emitter 156 is substantial enough to stabilize resistor 176 whereby the time that transistor 158 is conducting is a linear function of the input to the base. This output is provided to the diode coupler 192 and resistor 194, connected to conductor 104, at juncture 196. Emitter follower amplifier 198 is connected to juncture 196 and via resistor 200 to switching transistor 202 to provide an output to terminal 204 equal but opposite in sign to that at juncture 196, as illustrated by rectangular wave form of FIG. 7. Such a pulse, as is possible at terminal 204, is used to drive ignition coil switching network comprised of resistance 206 between conductor 102 and lead 208 intermediate of the connection of this lead with base 210 of transistor 212. Emitter 214 is connected by

leads

216 and 217 to conductor 104 via terminal 204 and collector 218 is connected by resistor 220 to conductor 221 connected to conductor 102 via terminal 204. Collector 218 is also connected to blocking diode 222 connected by conductor 224 to base 226 of switching transistor 228 whose emitter 229. is connected to conductor 230 leading to conductor 217 and via terminal 204 to ground 58. Collector 232 of transistor 228 is connected to one end of primary winding 30 connected at its other end to conductor 221. Zener

diodes

234 and 236 shunt emitter 229 to the output of collector 232. Therefore. it should be readily appreciated that if no pulse is available at terminal 204 then transistor 212 is off and current is being driven through diode 222 to base 226 of transistor 228 causing it to conduct. This will produce current in primary winding 30 charging the coil 32. However, when a pulse such as rectangular wave form 52 provided by network 26 is provided to network 28 and particularly base 210 of transistor 212 whereby it becomes conductive (saturated), transistor 228 is cutoff and current ceases to be directed to primary winding 30 and a high ignition potential is created in the secondary winding 34 which in the case of an engine ignition system is used to cause arcing across contacts of spark plug 36.

lt will be apparent that the system described and illustrated in the accompanying drawings should be considered as illustrative of how such an electronic ignition system can be applied to present day engine ignition systems employing contact points, and that it is equally applicable and beneficial to other impulse generating systems for controlling engine ignition as are known. In addition, it will be apparent that the utility of this invention is of broader application than just in engine ignition system as it is readily adaptable to any system needing lead-lag pulse shaping. Further, the scope of this invention is considered to embrace structure equivalent to that disclosed now and hereafter either from a mechanical point of view or from an electronic one without departing from the spirit of the intent of disclosure in return for these Letters Patent.

What is claimed is: I 1. An engine ignition system comprising: an electrical source; first means connected to said source and operable in response to engine operation for generating an impulse signal of predetermined time duration; second means connected to said first means for receipt of said impulse signal and operable to change a square waveform of said impulse signal to a nonlinear sloping waveform for said time duration of said impulse signal. said non-linear sloping waveform of said second means terminating upon termination of said square waveform of said impulse signal; third means operatively connected to said second means to vary the gradient of said non-linear sloping waveform within the time duration of said square waveform of said impulse signal to provide a faster or delayed rise of the non-linear sloping waveform from said second means whereby control of the position of a triggering potential therefrom is possible for proper timing of the engine ignition system; fourth means connected to said third means and energized by the triggering potential to generate a signal within the time duration of said impulse signal and displaced in time from the inception of said impulse signal in accordance with the triggering potential on the non-linear sloping waveform to be of a duration of time within said predetermined time duration of said impulse signal of said first means;

fifth means connected to said fourth means providing a switching signal within said time duration of said impulse signal of said first means;

an ignition coil connected to said electrical source and switching means whereby charging of a primary winding of said coil is controlled by said switching means to control transmission of a high energy potential from a secondary winding of said I coil within said time durationof said impulse signal; and

spark plug means connected to said coil to be activated by said high energy potential to provide engine ignition.

2. The structure of claim 1 wherein said second means is characterized as a RC cornering network including means to clamp a constant voltage of a square wave form.

3. The structure of claim 2 and further characterized by said third means including a variable resistor connected to said RC cornering network.

4. The structure of claim 3 wherein said variable resistors sliding contact is connected across said first means by a capacitor and discharge diode.

5. The structure of claim 4 wherein said fourth means is characterized as a means to re-shape said signal from said third means displaced in time and of a lesser predetermined duration whereby charging of said primary winding is permitted to take place for a substantial constant period of time regardless of fluctuations of said impulse signal.

6. The structure of claim 1 wherein said second means is further charactirized as an RC cornering network including means to maintain constant voltage.

7. The structure of claim 1 wherein said third means to vary the gradient of said slope to control the position of a triggering potential includes a variable resistor connected by a capacitor and discharge diode to said second means that changes a squarewave form signal from said first means to said non-linear sloping waveform along which said triggering potential is located.

8. The structure of claim 6 wherein said means to vary a triggering potential includes a resistor connected to said RC network; and

a sliding contact for varying the output of said resistor, said sliding contact being connected by a discharge diode to the constant voltage output of said RC cornering network and by a capacitor to said network in advance of the means therein to maintain constant voltage.

9. The structure of claim 1 wherein said fourth means connected to said third means tovary the gradient of said slope of said sloping character waveform to advance or retard the time to reach said triggering potential includes:

A Schmidt trigger;

A differentiation network 'operably connected to said Schmidt trigger; A one-shot monostable network connected to said diferentiation network; and An amplification and electronic switching means connected to said one-shot monostable network. 10. The structure of claim 9 wherein said fourth means generates an impulse signal of square wave form similar to but displaced in time and of lesser duration than a square waveform from said first means before decay; said fifth means connected to said fourth means comprises an electronic switching means including normally conducting and non-conducting transistors for controlling said ignition coil; and shunt means connected between said electronic switching means and said ignition coil protecting said electronic switching

Claims

1. An engine ignition system comprising: an electrical source; first means connected to said source and operable in response to engine operation for generating an impulse signal of predetermined time duration; second means connected to said first means for receipt of said impulse signal and operable to change a square waveform of said impulse signal to a non-linear sloping waveform for said time duration of said impulse signal, said non-linear sloping waveform of said second means terminating upon termination of said square waveform of said impulse signal; third means operatively connected to said second means to vary the gradient of said non-linear sloping waveform within the time duration of said square waveform of said impulse signal to provide a faster or delayed rise of the non-linear sloping waveform from said second means whereby control of the position of a triggering potential therefrom is possible for proper timing of the engine ignition system; fourth means connected to said third means and energized by the triggering potential to generate a signal within the time duration of said impulse signal and displaced in time from the inception of said impulse signal in accordance with the triggering potential on the non-linear sloping waveform to be of a duration of time within said predetermined time duration of said impulse signal of said first means; fifth means connected to said fourth means providing a switching signal within said time duration of said impulse signal of said first means; an ignition coil connected to said electrical source and switching means whereby charging of a primary winding of said coil is controlled by said switching means to control transmission of a high energy potential from a secondary winding of said coil within said time duration of said impulse signal; and spark plug means connected to said coil to be activated by said high energy potential to provide engine ignition.

4. The structure of claim 3 wherein said variable resistor''s sliding contact is connected across said first means by a capacitor and discharge diode.

8. The structure of claim 6 wherein said means to vary a triggering potential includes a resistor connected to said RC network; and a sliding contact for varying the output of said resistor, said sliding contact being connected by a discharge diode to the constant voltage output of said RC cornering network and by a capacitor to said network in advance of the means therein to maintain constant voltage.

9. The structure of claim 1 wherein said fourth means connected to said third means to vary the gradient of said slope of said sloping character waveform to advance or retard the time to reach said triggering potential includes: A Schmidt trigger; A differentiation network operably connected to said Schmidt trigger; A one-shot monostable network connected to said diferentiation network; and An amplification and electronic switching means connected to said one-shot monostable network.

10. The structure of claim 9 wherein said fourth means generates an impulse signal of square wave form similar to but displaced in time and of lesser duration than a square waveform from said first means before decay; said fifth means connected to said fourth means comprises an electronic switching means including normally conducting and non-conducting transistors for controlling said ignition coil; and shunt means connected between said electronic switching means and said ignition coil protecting said electronic switching means.