CA1103752A - Ac type ignition system - Google Patents
Ac type ignition systemInfo
- Publication number
- CA1103752A CA1103752A CA297,798A CA297798A CA1103752A CA 1103752 A CA1103752 A CA 1103752A CA 297798 A CA297798 A CA 297798A CA 1103752 A CA1103752 A CA 1103752A
- Authority
- CA
- Canada
- Prior art keywords
- npn transistor
- transistor
- duration
- spark
- engine
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
- F02P3/00—Other installations
- F02P3/01—Electric spark ignition installations without subsequent energy storage, i.e. energy supplied by an electrical oscillator
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Ignition Installations For Internal Combustion Engines (AREA)
Abstract
AN AC TYPE IGNITION SYSTEM
(D#74,581-F) Abstract of the Disclosure An electronic control circuit for use in connection with an AC type ignition system which employs a relatively high frequency oscillator.
The oscillator generates an AC spark signal that has a controlled duration. The starting of each spark signal is controlled by an engine-timed signal, and the time duration of the spark signal is made inversely proportional to the engine speed.
The result is an AC spark with a duration that coincides with a constant degree of crank angle rotation of the engine.
I
(D#74,581-F) Abstract of the Disclosure An electronic control circuit for use in connection with an AC type ignition system which employs a relatively high frequency oscillator.
The oscillator generates an AC spark signal that has a controlled duration. The starting of each spark signal is controlled by an engine-timed signal, and the time duration of the spark signal is made inversely proportional to the engine speed.
The result is an AC spark with a duration that coincides with a constant degree of crank angle rotation of the engine.
I
Description
1~3~
BACXGROUND OF ~HE_INVENTION
Field of the Invention This invention concerns an ignition system or internal combustion engines, in general. More specifically, it deals with a par-ticular control cir-cuit for controlling the spark signals o an AC
type ignition system. Such an AC type ignition system is illustrated by the following patents issued to the assignee of this application; i.e. Patent ~r Number 3,820,520 issued June 28, 1974 and Patent Number 3,961,613 issued June 8, 1976.
Square-wave AC type ignition systems have been found exceedingly beneficial in providing excellent spark discharges which are repetitive during the interva~ from the commencement of each spark signal to the termination thereof. However, it has been found that where such an ignition system is applied to an internal combustion engine that employs conventional breaker point control of the ignition signals, the duration of the AC
spark signals is practically impossib]e to ad-just so that they can be controlled so as to maintain a ixed relationship to the crank-shaft anyle of the engine. The difficulty which has been discovered is that while the leading edge or commencement of the spark signal may be accurately timed, the relationship of the duration of the signal thereafter until it terminates is extremely difficult to adjust or control with any .1. ' ,3r,~æ
accuracy. The reason is that the point dwell is the determining factor when they are controlling an AC
spark signal. And, such dwell time, or duration, is (as just indicated) extremely difficult (if not impossible) to set with any accuracy.
Consequently, it is an object of this invention to provide an eIectronic circuit that is in comhination with a breaker point ignition signal. It can maintain a spark duration control that has a duration which is in accordance with a ; desired degree of crank shaft rotation. This is -accomplished by having the spark signal duration made inversely proportional to the speed of the englne.
` SUMMAR~ OF THE INVENTION
,, ,~ ,:
, Briefly, the invention concerns the improvement that is in combination with an internal combustion engine having an electronic ignition circuit. The said ignition circuit has a continuous high voltage AC type spark signal of variable duration~ and the said circuit includes an electronic switch means for starting and stop-ping said spark signal. The ignition circuit also has a control means for said electronic switch means. Such control means comprises means for producing an engine timed signal for initiating said spark signal, and electrical time duration control means for actuating said electronic switch . .
~33~
means for an interval having a duration that is inversely proportional to the speed of said engine. The arrangement is in total such that said spark signal duration coincides with a substantially constant degree of crank angle rotation of said engine.
According to a broad aspect o* the invention, there is provided in combination with a controlled spark-duration ignit:ion system for an internal combustion engine having a crank shaft~ sald system comprising in combination a high-frequency continuous-wave oscilla~or including first circuit means for connecting a source of DC power thereto and a transformer having a high-voltage output winding for producing a continuous high-voltage AC type spark signal of variable duration, second circuit means *or connecting said trans- :
former output winding to a sparking circuit, an oscillator control winding ~; located on said transformer for starting and stopping oscillation of said oscillator, third circuit means for applying a DC bias current to said oscillator control winding when said oscillator is not oscillating, and electronic switch means in series with said control winding for starting and stopping said spark signal, the improvement comprising control means for said electronic switch means, comprising means for producing an engine timed signal for initiating said spark signal~ and electronic circuit means includ-ing a plurality of NPN transistors for actuating said electronic switch means for an interval having a duration inversely proportional to the speed of said engine, whereby said spark signal duration coincides with a substantially constant degree of crank angle rotation of said engine.
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BRIEF DESCRIPTION O~ Tl-IE DRAWINGS
_, The oregoing and other objects and benefits of the invention will be more fully set forth below in connection with the best mode con-templated by the inventor of carrying out the inve.ntion, and in connection with which there are illustrations provided in the drawing wherein:
: The FIG. of drawings illustrates a schematic circuit diagram of an ignition system according to the invention, which includes the electronic con*rols of an AC type ignition system.
DESCRIPTION OF THE PREFERRED EMBODIMENT
` 10 Referring to the drawing~ it will be observed that there is shown in dashed lines an ignition ' :
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signal generating system. For example, see the U.S. Patents mentioned above number 3"820,520 issued June 28, 1974 and 3,961,613 issued June 8, 1976. The details of operation of such an ignition system are clearly described in those patents. Consequently, it is sufficient to note here that there is a square-wave type AC
oscillator 12 that is connected to a center tapped winding 15 on a transformer 13. The L0 transformer 13 has a~ output winding 14 for delivering the high voltage spark signals. Also, as is clearly described in the foregoing patents, this type of AC ignition system includes a con-trol winding 17 on the transformer 13. The start-ing and stopping of the oscillator 12 is determined by conditions in the control winding 17, which has an electronic switch 18 (transistor~ connected in series therewith. The control of the transistor, i.e. electronic switch 18 is what determines the spark signal duration. This, in turn, is the time during which oscillator 12 is oscillating.
Other elements of the ignition system, as it is applied to an internal combustion engine, include a battery 21 that supplies power to the oscillator 12. It also suppliers power to the control winding 17, and to the electronic timing control system to be described. Also, it will be understood that there is a conventional ignition switch 22 that has the usual "start" and "run"
positions, which are well known and need not be described further.
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Another element that is not directly part of the invention, is a relay 23 that is shown en-closed in a dashed line. It includes a winding 24 that controls a pair of contacts 25. It will be observed that this relay 23 is energized when the ignition switch 22 is turned on, and consequently the contacts 25 will then be'opened. The pur~ose of this,relay has been described in a U.S~ Patent 3,861,369 issued January 21, 1975 and assigned to Texaco Inc., and consequently it is unnecessary to make any fur~her reference thereto at this time~
It will be observed briefly that the contacts 25, when in the position illustrated in the drawing, provide a short-circuit across the control winding 17. This short circuit insures the stopping of the oscillator 12, so that there will not be any high voltage generated when the ignition switch 22 is turned off.
There is breaker point switch 28 that is controlled by a cam 29 which is directly connected to the crank shaft (not shown) of the engine to which the ignition system is applied.
An important aspeck of this invention concerns the control means for determining the actuation of the transistor (switch) 18. Transistor 18, in turn, controls the time duration o~ oscilation of the oscillator 12 which produces the AC type ignition signals that are delivered from the output winding 14 of the transformer 13. Such control means includes 3~5~ `:
the breaker point switch 28 which is connected into an input circuit of a ~irst transistor 32. That input circuit includes a circuit connection 33 that leads to one end of a resistor 34, as well as to one side of a capacitor 35. -Also a circuit connection 38 goes rom the other side of capacitor 35 to one side of a diode 3~3. The circuit continues through a resis~or 40 to the base electrode of the transistor 32.
It will be noted th~t when the breaker point switch 28 is closed, the networ~ on the foregoing input circuit to transistor 32 provides a grounded condition at the base electrode and consequently keeps transistor 32 non-conducting.
There is a capacitor 43 that has one side thereof connected to the output of the transistor 32 via a circuit connection 44. The other side of capacitor 43 is connected to the input of a second transistor 47 via a circuit connection 48.
There is a third transistor 51 that has its output connected in parallel with the first txansistor 32. The input of transistor 51 is connected to the output of the second transistor 47. The latter is by means of a circuit connection 52, and resistors 53 and 54, as well as a circuit connection 55. The arrangement is such that the third transistor 51 will be conducting when, and so long as, the second transistor 47 is non~conduct-- ing, i.e. turned off.
. 7 .
... . .
. .
~.6337S2 There is a pair o resistors 58 and 59 that are connected to the input of the second transistor 47 so as to control the time duration of the non- ;
conducting state thereof.
A fourth transistor 62 is a PNP type and is connected as a constant current generator. It supplies current to one side of the capacitor 43.
Such constant current generator includes resistors 63, 64 and 65 that are connected to the electrodes of the transistor 62 in a manner that is known to anyone skilled in the art.
There is a fifth transistor 68 that has its input connected to the output of the second transistor 47. Such connection is via the in-dicated circuit connection which goes through a resistor 69. It will be observed that the tran-sistor 68 has its collector connected to the power source from battery 21 via a resistor 70, and its output is connected over a circuit connection 71 to the input, i.e. the base electrode of elec-tronic switch transistor 18. It will be under-stood that the input circuit of transistor 18 includes another resistor 74.
Before the operation of the above des-cribed circuit is indicated, it should be emphasized, or pointed out that the ignition system being con-trolled is the particular type employing an AC
relatively high frequency spark signal. Each spark signal is generated with timing control from the crank shat of the engine. And, each . 8 .
3~
r signal has a variable time duration from the be-ginning to the end of the AC spark signal. As has been clearly explained in the above noted patents, the AC spark signals are controlled by the co~trol winding 17 on the transformer 13 which lakter is part of the oscillator 12 which generates the spark signal~
Th~ winding 17 is the start~stop control winding, and when there is no spark signal being generated it carries a DC bias current and additionally has an AC short circuit connected across it so that the oscillator 12 may not oscillate. The DC current flowing through the winding 17 goes across the electronic switch 18, and consequently it is the instant when conduction of transistor 18 is cut off that commences each spark signal time duration. The end of each such time duration is controlled by the conduction of the transistor 18 once more. It is such conduction that allows the AC short circuit to be applied to the control winding 17, at the same time as the re-commencement of the AC bias current flow.
While in the past, circuits have been arranged for this type of ignition system that would have the conduction of the electronic switch 18 directly controlled by the breaker point swikch 28 as to both the beginning and the ending of each spark signal duration, such arrangement would have involved the problems mentioned above in 3~ regard to the difficulty of physically adjusting 33~
the dwell time of the breaker point switch contacts.
Consequently, as will appear below from the des-cription of the operation of the electronic cir-cuits noted above, those difficulties are overcome by only making use of the initial opening of breaker point 28. The time duration following ;` that initial opening is controlled by an electronic timing circuit the elements of which were described above. This circuit will act inversely as the speed of the engine and consequently may be set to produce a spark signal duration that is sub stantially constant in terms of crank angle degrees.
It may be noted that the timing circuit per se is known, but its co~bination with an AC type ignition system according to this invention is new and unobvious. It overcomes a problem -that would make this type of ignition system inapplicable to an engine using conventional breaker points.
Operation The operation of the timing system for this invention may be described as follows, in regard the elements indicated above, and par-ticularly with reference to the control of conduction and non-conduction of the electronic switch, i.e.
transistor 18.
Thus, beginning with condition when the oscillator 12 is not oscillating and consequently no AC spark signal is being generated, the various . 10 .
~3~
transistors will have the following states. The first transistor 32 is off (i.e. non-conducting) since the breaker point switch 28 is closed. The second transistor 47 is on (i.e. conduc~ing) and its base voltage is clamped at 0.7 volts. The third transistor 51 is of (i.e. non-conducting), and the fourth transistor 68 is also off (i.e.
non-conducting). Finally, the electronic switchr i.e. transistor 18 is on (i.e. conducting) and this means that there is no spark signal being generated because the oscillator 12 is not oscillating.
When the breaker point switch 28 opens (as set by the timing adjustment to start a spark signal at a desired instant relative to the crank shaft of the engine), the following conditions take place in the control circuit. The first transistor 32 is turned on for an instant and then returned off again, under the conditions determined by the input network between the breaker point switch 28 and the base electrode of transistor 32.
When transistor 32 is turned on, it turns off transistor 47 which in turn turns on transistor 51, and these two transistors remain off and on respectively, together. In other words, so long as transistor 47 is non-conducting, the transistor 68 is turned on, and this in turn acts to turn off the transistor (electronic switch) 18. As indicated above these conditions exist at the commencement of a spark signal duration.
. 11 .
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r The timing control for determining how long the transistor (switch) 18 will be non-conducting, involves the capacitor 43 and the fifth transistor 6~, which is a PNP type transistor connected as a constant current generator. The ~: action o the timing circuit may be cLescribed as follows. At the instant when the second transistor : 47 is turned off, the right hand side of capacitor 43 charges toward the battery voltage through the resistors 58 and 59 until a voltage of Q.7 volts ::
- is reached. As soon as that voltage level is reached, the transistor 47 is turned on again, and its collector voltage goes down due to current flow through resistors 77 and 78. Consequently, the subsequent transistor 68.is turned off, as previously described.
The turning back on of transistor 47 turns transistor 51 off and this permits the left hand side of capacitor 43 to charge via the
BACXGROUND OF ~HE_INVENTION
Field of the Invention This invention concerns an ignition system or internal combustion engines, in general. More specifically, it deals with a par-ticular control cir-cuit for controlling the spark signals o an AC
type ignition system. Such an AC type ignition system is illustrated by the following patents issued to the assignee of this application; i.e. Patent ~r Number 3,820,520 issued June 28, 1974 and Patent Number 3,961,613 issued June 8, 1976.
Square-wave AC type ignition systems have been found exceedingly beneficial in providing excellent spark discharges which are repetitive during the interva~ from the commencement of each spark signal to the termination thereof. However, it has been found that where such an ignition system is applied to an internal combustion engine that employs conventional breaker point control of the ignition signals, the duration of the AC
spark signals is practically impossib]e to ad-just so that they can be controlled so as to maintain a ixed relationship to the crank-shaft anyle of the engine. The difficulty which has been discovered is that while the leading edge or commencement of the spark signal may be accurately timed, the relationship of the duration of the signal thereafter until it terminates is extremely difficult to adjust or control with any .1. ' ,3r,~æ
accuracy. The reason is that the point dwell is the determining factor when they are controlling an AC
spark signal. And, such dwell time, or duration, is (as just indicated) extremely difficult (if not impossible) to set with any accuracy.
Consequently, it is an object of this invention to provide an eIectronic circuit that is in comhination with a breaker point ignition signal. It can maintain a spark duration control that has a duration which is in accordance with a ; desired degree of crank shaft rotation. This is -accomplished by having the spark signal duration made inversely proportional to the speed of the englne.
` SUMMAR~ OF THE INVENTION
,, ,~ ,:
, Briefly, the invention concerns the improvement that is in combination with an internal combustion engine having an electronic ignition circuit. The said ignition circuit has a continuous high voltage AC type spark signal of variable duration~ and the said circuit includes an electronic switch means for starting and stop-ping said spark signal. The ignition circuit also has a control means for said electronic switch means. Such control means comprises means for producing an engine timed signal for initiating said spark signal, and electrical time duration control means for actuating said electronic switch . .
~33~
means for an interval having a duration that is inversely proportional to the speed of said engine. The arrangement is in total such that said spark signal duration coincides with a substantially constant degree of crank angle rotation of said engine.
According to a broad aspect o* the invention, there is provided in combination with a controlled spark-duration ignit:ion system for an internal combustion engine having a crank shaft~ sald system comprising in combination a high-frequency continuous-wave oscilla~or including first circuit means for connecting a source of DC power thereto and a transformer having a high-voltage output winding for producing a continuous high-voltage AC type spark signal of variable duration, second circuit means *or connecting said trans- :
former output winding to a sparking circuit, an oscillator control winding ~; located on said transformer for starting and stopping oscillation of said oscillator, third circuit means for applying a DC bias current to said oscillator control winding when said oscillator is not oscillating, and electronic switch means in series with said control winding for starting and stopping said spark signal, the improvement comprising control means for said electronic switch means, comprising means for producing an engine timed signal for initiating said spark signal~ and electronic circuit means includ-ing a plurality of NPN transistors for actuating said electronic switch means for an interval having a duration inversely proportional to the speed of said engine, whereby said spark signal duration coincides with a substantially constant degree of crank angle rotation of said engine.
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``` ~L~.~3~
BRIEF DESCRIPTION O~ Tl-IE DRAWINGS
_, The oregoing and other objects and benefits of the invention will be more fully set forth below in connection with the best mode con-templated by the inventor of carrying out the inve.ntion, and in connection with which there are illustrations provided in the drawing wherein:
: The FIG. of drawings illustrates a schematic circuit diagram of an ignition system according to the invention, which includes the electronic con*rols of an AC type ignition system.
DESCRIPTION OF THE PREFERRED EMBODIMENT
` 10 Referring to the drawing~ it will be observed that there is shown in dashed lines an ignition ' :
_~ _ ,~;4 . , .,, :: - .
~3'7Si~
signal generating system. For example, see the U.S. Patents mentioned above number 3"820,520 issued June 28, 1974 and 3,961,613 issued June 8, 1976. The details of operation of such an ignition system are clearly described in those patents. Consequently, it is sufficient to note here that there is a square-wave type AC
oscillator 12 that is connected to a center tapped winding 15 on a transformer 13. The L0 transformer 13 has a~ output winding 14 for delivering the high voltage spark signals. Also, as is clearly described in the foregoing patents, this type of AC ignition system includes a con-trol winding 17 on the transformer 13. The start-ing and stopping of the oscillator 12 is determined by conditions in the control winding 17, which has an electronic switch 18 (transistor~ connected in series therewith. The control of the transistor, i.e. electronic switch 18 is what determines the spark signal duration. This, in turn, is the time during which oscillator 12 is oscillating.
Other elements of the ignition system, as it is applied to an internal combustion engine, include a battery 21 that supplies power to the oscillator 12. It also suppliers power to the control winding 17, and to the electronic timing control system to be described. Also, it will be understood that there is a conventional ignition switch 22 that has the usual "start" and "run"
positions, which are well known and need not be described further.
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Another element that is not directly part of the invention, is a relay 23 that is shown en-closed in a dashed line. It includes a winding 24 that controls a pair of contacts 25. It will be observed that this relay 23 is energized when the ignition switch 22 is turned on, and consequently the contacts 25 will then be'opened. The pur~ose of this,relay has been described in a U.S~ Patent 3,861,369 issued January 21, 1975 and assigned to Texaco Inc., and consequently it is unnecessary to make any fur~her reference thereto at this time~
It will be observed briefly that the contacts 25, when in the position illustrated in the drawing, provide a short-circuit across the control winding 17. This short circuit insures the stopping of the oscillator 12, so that there will not be any high voltage generated when the ignition switch 22 is turned off.
There is breaker point switch 28 that is controlled by a cam 29 which is directly connected to the crank shaft (not shown) of the engine to which the ignition system is applied.
An important aspeck of this invention concerns the control means for determining the actuation of the transistor (switch) 18. Transistor 18, in turn, controls the time duration o~ oscilation of the oscillator 12 which produces the AC type ignition signals that are delivered from the output winding 14 of the transformer 13. Such control means includes 3~5~ `:
the breaker point switch 28 which is connected into an input circuit of a ~irst transistor 32. That input circuit includes a circuit connection 33 that leads to one end of a resistor 34, as well as to one side of a capacitor 35. -Also a circuit connection 38 goes rom the other side of capacitor 35 to one side of a diode 3~3. The circuit continues through a resis~or 40 to the base electrode of the transistor 32.
It will be noted th~t when the breaker point switch 28 is closed, the networ~ on the foregoing input circuit to transistor 32 provides a grounded condition at the base electrode and consequently keeps transistor 32 non-conducting.
There is a capacitor 43 that has one side thereof connected to the output of the transistor 32 via a circuit connection 44. The other side of capacitor 43 is connected to the input of a second transistor 47 via a circuit connection 48.
There is a third transistor 51 that has its output connected in parallel with the first txansistor 32. The input of transistor 51 is connected to the output of the second transistor 47. The latter is by means of a circuit connection 52, and resistors 53 and 54, as well as a circuit connection 55. The arrangement is such that the third transistor 51 will be conducting when, and so long as, the second transistor 47 is non~conduct-- ing, i.e. turned off.
. 7 .
... . .
. .
~.6337S2 There is a pair o resistors 58 and 59 that are connected to the input of the second transistor 47 so as to control the time duration of the non- ;
conducting state thereof.
A fourth transistor 62 is a PNP type and is connected as a constant current generator. It supplies current to one side of the capacitor 43.
Such constant current generator includes resistors 63, 64 and 65 that are connected to the electrodes of the transistor 62 in a manner that is known to anyone skilled in the art.
There is a fifth transistor 68 that has its input connected to the output of the second transistor 47. Such connection is via the in-dicated circuit connection which goes through a resistor 69. It will be observed that the tran-sistor 68 has its collector connected to the power source from battery 21 via a resistor 70, and its output is connected over a circuit connection 71 to the input, i.e. the base electrode of elec-tronic switch transistor 18. It will be under-stood that the input circuit of transistor 18 includes another resistor 74.
Before the operation of the above des-cribed circuit is indicated, it should be emphasized, or pointed out that the ignition system being con-trolled is the particular type employing an AC
relatively high frequency spark signal. Each spark signal is generated with timing control from the crank shat of the engine. And, each . 8 .
3~
r signal has a variable time duration from the be-ginning to the end of the AC spark signal. As has been clearly explained in the above noted patents, the AC spark signals are controlled by the co~trol winding 17 on the transformer 13 which lakter is part of the oscillator 12 which generates the spark signal~
Th~ winding 17 is the start~stop control winding, and when there is no spark signal being generated it carries a DC bias current and additionally has an AC short circuit connected across it so that the oscillator 12 may not oscillate. The DC current flowing through the winding 17 goes across the electronic switch 18, and consequently it is the instant when conduction of transistor 18 is cut off that commences each spark signal time duration. The end of each such time duration is controlled by the conduction of the transistor 18 once more. It is such conduction that allows the AC short circuit to be applied to the control winding 17, at the same time as the re-commencement of the AC bias current flow.
While in the past, circuits have been arranged for this type of ignition system that would have the conduction of the electronic switch 18 directly controlled by the breaker point swikch 28 as to both the beginning and the ending of each spark signal duration, such arrangement would have involved the problems mentioned above in 3~ regard to the difficulty of physically adjusting 33~
the dwell time of the breaker point switch contacts.
Consequently, as will appear below from the des-cription of the operation of the electronic cir-cuits noted above, those difficulties are overcome by only making use of the initial opening of breaker point 28. The time duration following ;` that initial opening is controlled by an electronic timing circuit the elements of which were described above. This circuit will act inversely as the speed of the engine and consequently may be set to produce a spark signal duration that is sub stantially constant in terms of crank angle degrees.
It may be noted that the timing circuit per se is known, but its co~bination with an AC type ignition system according to this invention is new and unobvious. It overcomes a problem -that would make this type of ignition system inapplicable to an engine using conventional breaker points.
Operation The operation of the timing system for this invention may be described as follows, in regard the elements indicated above, and par-ticularly with reference to the control of conduction and non-conduction of the electronic switch, i.e.
transistor 18.
Thus, beginning with condition when the oscillator 12 is not oscillating and consequently no AC spark signal is being generated, the various . 10 .
~3~
transistors will have the following states. The first transistor 32 is off (i.e. non-conducting) since the breaker point switch 28 is closed. The second transistor 47 is on (i.e. conduc~ing) and its base voltage is clamped at 0.7 volts. The third transistor 51 is of (i.e. non-conducting), and the fourth transistor 68 is also off (i.e.
non-conducting). Finally, the electronic switchr i.e. transistor 18 is on (i.e. conducting) and this means that there is no spark signal being generated because the oscillator 12 is not oscillating.
When the breaker point switch 28 opens (as set by the timing adjustment to start a spark signal at a desired instant relative to the crank shaft of the engine), the following conditions take place in the control circuit. The first transistor 32 is turned on for an instant and then returned off again, under the conditions determined by the input network between the breaker point switch 28 and the base electrode of transistor 32.
When transistor 32 is turned on, it turns off transistor 47 which in turn turns on transistor 51, and these two transistors remain off and on respectively, together. In other words, so long as transistor 47 is non-conducting, the transistor 68 is turned on, and this in turn acts to turn off the transistor (electronic switch) 18. As indicated above these conditions exist at the commencement of a spark signal duration.
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r The timing control for determining how long the transistor (switch) 18 will be non-conducting, involves the capacitor 43 and the fifth transistor 6~, which is a PNP type transistor connected as a constant current generator. The ~: action o the timing circuit may be cLescribed as follows. At the instant when the second transistor : 47 is turned off, the right hand side of capacitor 43 charges toward the battery voltage through the resistors 58 and 59 until a voltage of Q.7 volts ::
- is reached. As soon as that voltage level is reached, the transistor 47 is turned on again, and its collector voltage goes down due to current flow through resistors 77 and 78. Consequently, the subsequent transistor 68.is turned off, as previously described.
The turning back on of transistor 47 turns transistor 51 off and this permits the left hand side of capacitor 43 to charge via the
2~ constant current genexator which includes tran-sistor 62. Since this is a constant current generator the charge on this left hand side of capac-itor 43 will increase linearly with time, and the maximum voltage is set by the ratio of the resistors 63 and 65. The rate of charge is determined by the resistance of the combined re-sistors 58 and the variable resistor 59.
The amplitude of a negative pulse that is created on the right hand side of capacitor 43 when the capacitor discharges through the . 1~ .
37~;~
transistor 32, is determined by the magnitude of the voltage that is impressed on the left hand side of the capacitor 43. Consequently, if the eft hand side voltage is large, the negative voltage on the right hand side will also be large. Then, the time required for the transistor 47 to be turned back on (as indicated above) will be longer than if the pulse were lower in amplitude. Also, the charge on the left hand side of capacitor 43 will be large if there is a long time interval between openings of the breaker point switch 28. Thus, when the engine is turning over rapidly (at a high rate of revolutions) the intervals between openings of breaker points 28 will be short, and the charge on the left side of the capacitor 43 will be small. Therefore, it will be understood that by proper determination of the circuit constants involved, the timing may be set so as to be directly in inverse proportion as the speed of the engine, i.e. the rotations of the crank shaft. Consequently, the AC spark time durations may be determined so as to main-tain a predetermine degree of crank angle shaft rotation, during which desired AC type spark signal will exist.
While a particular embodiment of the inven~ion has been described above in consider-able detail, in accordance with the ap~licable . .
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. ~ . .
The amplitude of a negative pulse that is created on the right hand side of capacitor 43 when the capacitor discharges through the . 1~ .
37~;~
transistor 32, is determined by the magnitude of the voltage that is impressed on the left hand side of the capacitor 43. Consequently, if the eft hand side voltage is large, the negative voltage on the right hand side will also be large. Then, the time required for the transistor 47 to be turned back on (as indicated above) will be longer than if the pulse were lower in amplitude. Also, the charge on the left hand side of capacitor 43 will be large if there is a long time interval between openings of the breaker point switch 28. Thus, when the engine is turning over rapidly (at a high rate of revolutions) the intervals between openings of breaker points 28 will be short, and the charge on the left side of the capacitor 43 will be small. Therefore, it will be understood that by proper determination of the circuit constants involved, the timing may be set so as to be directly in inverse proportion as the speed of the engine, i.e. the rotations of the crank shaft. Consequently, the AC spark time durations may be determined so as to main-tain a predetermine degree of crank angle shaft rotation, during which desired AC type spark signal will exist.
While a particular embodiment of the inven~ion has been described above in consider-able detail, in accordance with the ap~licable . .
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. ~ . .
3~2 statutes, this is not to be taken as in any way limiting the invention but merely as being des-~; criptive thereof.
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:
. ~
. 14 .
Claims (2)
1. In combination with a controlled spark-duration ignition system for an internal combustion engine having a crank shaft, said system comprising in combination a high-frequency continuous-wave oscillator including first circuit means for connecting a source of DC power thereto and a transformer having a high-voltage output winding for producing a continuous high-voltage AC type spark signal of variable duration, second circuit means for connecting said trans-former output winding to a sparking circuit, an oscillator control winding located on said transformer for starting and stopping oscillation of said oscillator, third circuit means for applying a DC bias current to said oscillator control winding when said oscillator is not oscillating, and electronic switch means in series with said control winding for starting and stopping said spark signal, the improvement comprising control means for said electronic switch means, comprising means for producing an engine timed signal for initiating said spark signal, and electronic circuit means including a plurality of NPN tran-sistors for actuating said electronic switch means for an interval having a duration inversely pro-. 15 .
portional to the speed of said engine, whereby said spark signal duration coincides with a substantially constant degree of crank angle rotation of said engine.
portional to the speed of said engine, whereby said spark signal duration coincides with a substantially constant degree of crank angle rotation of said engine.
2. The invention according to Claim 1, wherein said plurality of NPN transistors and electronic circuit means comprise a first NPN transistor having an input connected to said breaker points for producing an initiating pulse to said time duration control means, a capacitor having one side connected to said first NPN transistor output for transmitting said initiating pulse to a second NPN transistor input, a third NPN transistor having its output connected in parallel with said first NPN transistor output and its input connected to the output of said second NPN transistor for making said third NPN
transistor conduct so long as said second NPN
transistor is non-conducting, a PNP transistor connected as a constant current generator feeding said one side of said capacitor, and a variable resistor connected to said second NPN
transistor input for controlling the time duration of said second NPN transistor's non-conducting state.
. 16 .
transistor conduct so long as said second NPN
transistor is non-conducting, a PNP transistor connected as a constant current generator feeding said one side of said capacitor, and a variable resistor connected to said second NPN
transistor input for controlling the time duration of said second NPN transistor's non-conducting state.
. 16 .
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US77911877A | 1977-03-18 | 1977-03-18 | |
| US779,118 | 1977-03-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1103752A true CA1103752A (en) | 1981-06-23 |
Family
ID=25115388
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA297,798A Expired CA1103752A (en) | 1977-03-18 | 1978-02-27 | Ac type ignition system |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS53117136A (en) |
| BR (1) | BR7800212A (en) |
| CA (1) | CA1103752A (en) |
| DE (1) | DE2752639A1 (en) |
| FR (1) | FR2384127A1 (en) |
| IT (1) | IT1092865B (en) |
| ZA (1) | ZA78118B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52147155U (en) * | 1976-04-30 | 1977-11-08 | ||
| US4382430A (en) * | 1981-06-01 | 1983-05-10 | Shinichiro Iwasaki | Ignition system |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4003354A (en) * | 1974-12-19 | 1977-01-18 | Texaco Inc. | Means and method for controlling the occurrence and the duration of time intervals during which sparks are provided in a multicylinder internal combustion engine |
-
1977
- 1977-11-25 DE DE19772752639 patent/DE2752639A1/en active Pending
-
1978
- 1978-01-09 ZA ZA00780118A patent/ZA78118B/en unknown
- 1978-01-13 BR BR7800212A patent/BR7800212A/en unknown
- 1978-02-07 JP JP1201878A patent/JPS53117136A/en active Pending
- 1978-02-13 IT IT20239/78A patent/IT1092865B/en active
- 1978-02-16 FR FR7804387A patent/FR2384127A1/en active Granted
- 1978-02-27 CA CA297,798A patent/CA1103752A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| IT7820239A0 (en) | 1978-02-13 |
| DE2752639A1 (en) | 1978-09-21 |
| FR2384127B3 (en) | 1980-10-03 |
| JPS53117136A (en) | 1978-10-13 |
| FR2384127A1 (en) | 1978-10-13 |
| IT1092865B (en) | 1985-07-12 |
| BR7800212A (en) | 1978-10-10 |
| ZA78118B (en) | 1979-05-30 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |