Title:
IGNITION ADAPTER CIRCUIT
United States Patent 3704397
Abstract:
An electrical ignition system for adapting a conventional magneto spark ignition system to a capacitor discharge ignition system.
US Patent References:
Regulated capacitor discharge ignition system
Minks - May 1968 - 3383555
CAPACITOR DISCHARGE IGNITION SYSTEM
Hufton et al. - January 1970 - 3487822
CAPACITIVE-DISCHARGE IGNITION SYSTEM
Ilinski - March 1970 - 3500808
IGNITION SYSTEM UTILIZING TRANSISTOR FOR INTERNAL COMBUSTION ENGINES
Longauer - October 1971 - 3611025
IGNITION SYSTEMS
Maycock et al. - December 1971 - 3629652
Regulated capacitor discharge ignition system
Minks - May 1968 - 3383555
CAPACITOR DISCHARGE IGNITION SYSTEM
Hufton et al. - January 1970 - 3487822
CAPACITIVE-DISCHARGE IGNITION SYSTEM
Ilinski - March 1970 - 3500808
IGNITION SYSTEM UTILIZING TRANSISTOR FOR INTERNAL COMBUSTION ENGINES
Longauer - October 1971 - 3611025
IGNITION SYSTEMS
Maycock et al. - December 1971 - 3629652
Inventors:
Crouch, Thomas J. (Leonard, MI)
Gynn, George E. (Fort Wayne, IN)
Gynn, George E. (Fort Wayne, IN)
Application Number:
05/207261
Publication Date:
11/28/1972
Filing Date:
12/13/1971
View Patent Images:
Export Citation:
Assignee:
Syncro Corporation (Oxford, MI)
Primary Class:
Other Classes:
315/209CD, 123/149R
International Classes:
F02P7/03; F02P7/00; H01T15/02; F02P3/06
Field of Search:
317/157.6 315/29CD
Primary Examiner:
Hix L. T.
Claims:
What is claimed is
1. An adapter assembly for converting an existing magneto ignition system to a capacitor discharge ignition system with the magneto having a rotor and a stator and having a first magneto coil for providing an alternating output potential and connected to and across a first set of breaker points and having a second magneto coil for providing an alternating output potential and connected to and across a second set of breaker points with the first and second magneto coils and first and second sets of points being supported on the stator, a first conductor normally connecting the first magneto coil and first set of points to a first ignition coil, a second conductor normally connecting the second magneto coil and second set of points to a second ignition coil, said adapter assembly comprising: a first capacitor, first charge circuit means connecting the first conductor and hence the first magneto coil to said first capacitor for charging said first capacitor with the electrical energy of the output potential from the first magneto coil, first discharge circuit means connecting said first capacitor to the second ignition coil for transmitting the stored electrical energy in said first capacitor in response to the occurrence of a first preselected positional relationship between the rotor and the stator, a second capacitor, second charge circuit means connecting the second conductor and hence the second magneto coil to said second capacitor for charging said second capacitor with electrical energy of the output potential from the second magneto coil, second discharge circuit means connecting said second capacitor to the first ignition coil for transmitting the stored electrical energy in said second capacitor in response to the occurrence of a second preselected positional relationship between the rotor and the stator.
2. The adapter assembly of claim 1 in which said first discharge circuit means includes first solid state switch means for transmitting the stored electrical energy from said first capacitor in response to a first trigger pulse and includes first trigger means operable in response to actuation of the second breaker points for providing said first trigger pulse, said second discharge circuit means includes second solid state switch means for transmitting the stored electrical energy from said second capacitor in response to a second trigger pulse and includes second trigger means operable in response to actuation of the first breaker points for providing said second trigger pulse.
3. The adapter assembly of claim 2 with said first charge circuit means including the first breaker points with said first capacitor being charged from the first magneto coil when the first breaker points are in open circuit condition, said second charge circuit means including the second breaker points with said second capacitor being charged from the second magneto coil with the second breaker points are in open circuit condition, said first trigger means providing said first trigger pulse with the second breaker points in open circuit condition, said second trigger means providing said second trigger pulse with the first breaker points in open circuit condition.
4. An adapter assembly for converting an existing magneto spark ignition system to a capacitor discharge ignition system with the magneto having a rotor and a stator and having at least one magneto coil connected to the stator for providing an alternating output potential and at least one set of breaker points in combination with a spark ignition coil, said adapter assembly comprising: a capacitor, first circuit means connecting the magneto coil to said capacitor for charging said capacitor directly with the electrical energy of the output potential from the magneto coil for only one polarity of the output potential, second circuit means connecting said capacitor to the ignition coil, said second circuit means comprising: solid state switch means having a pair of principal electrodes and a gate electrode for transmitting the stored energy on said capacitor to the ignition coil via said principal electrodes upon the occurrence of a trigger pulse at said gate electrode, and trigger means operatively connected with the rotor for providing said trigger pulse in response to the occurrence of a preselected positional relationship between the rotor and the stator.
5. The adapter assembly of claim 4 for use with the existing magneto spark ignition system further including a second set of breaker points, said trigger means including the second set of breaker points and providing said trigger pulse in response to actuation of the second set of breaker points.
6. The adapter assembly of claim 5 with said first circuit means including the first set of breaker points for charging said capacitor with the first set of breaker points in an open circuit condition, said trigger means providing said trigger pulse in response to the second set of breaker points being in an open circuit condition.
1. An adapter assembly for converting an existing magneto ignition system to a capacitor discharge ignition system with the magneto having a rotor and a stator and having a first magneto coil for providing an alternating output potential and connected to and across a first set of breaker points and having a second magneto coil for providing an alternating output potential and connected to and across a second set of breaker points with the first and second magneto coils and first and second sets of points being supported on the stator, a first conductor normally connecting the first magneto coil and first set of points to a first ignition coil, a second conductor normally connecting the second magneto coil and second set of points to a second ignition coil, said adapter assembly comprising: a first capacitor, first charge circuit means connecting the first conductor and hence the first magneto coil to said first capacitor for charging said first capacitor with the electrical energy of the output potential from the first magneto coil, first discharge circuit means connecting said first capacitor to the second ignition coil for transmitting the stored electrical energy in said first capacitor in response to the occurrence of a first preselected positional relationship between the rotor and the stator, a second capacitor, second charge circuit means connecting the second conductor and hence the second magneto coil to said second capacitor for charging said second capacitor with electrical energy of the output potential from the second magneto coil, second discharge circuit means connecting said second capacitor to the first ignition coil for transmitting the stored electrical energy in said second capacitor in response to the occurrence of a second preselected positional relationship between the rotor and the stator.
2. The adapter assembly of claim 1 in which said first discharge circuit means includes first solid state switch means for transmitting the stored electrical energy from said first capacitor in response to a first trigger pulse and includes first trigger means operable in response to actuation of the second breaker points for providing said first trigger pulse, said second discharge circuit means includes second solid state switch means for transmitting the stored electrical energy from said second capacitor in response to a second trigger pulse and includes second trigger means operable in response to actuation of the first breaker points for providing said second trigger pulse.
3. The adapter assembly of claim 2 with said first charge circuit means including the first breaker points with said first capacitor being charged from the first magneto coil when the first breaker points are in open circuit condition, said second charge circuit means including the second breaker points with said second capacitor being charged from the second magneto coil with the second breaker points are in open circuit condition, said first trigger means providing said first trigger pulse with the second breaker points in open circuit condition, said second trigger means providing said second trigger pulse with the first breaker points in open circuit condition.
4. An adapter assembly for converting an existing magneto spark ignition system to a capacitor discharge ignition system with the magneto having a rotor and a stator and having at least one magneto coil connected to the stator for providing an alternating output potential and at least one set of breaker points in combination with a spark ignition coil, said adapter assembly comprising: a capacitor, first circuit means connecting the magneto coil to said capacitor for charging said capacitor directly with the electrical energy of the output potential from the magneto coil for only one polarity of the output potential, second circuit means connecting said capacitor to the ignition coil, said second circuit means comprising: solid state switch means having a pair of principal electrodes and a gate electrode for transmitting the stored energy on said capacitor to the ignition coil via said principal electrodes upon the occurrence of a trigger pulse at said gate electrode, and trigger means operatively connected with the rotor for providing said trigger pulse in response to the occurrence of a preselected positional relationship between the rotor and the stator.
5. The adapter assembly of claim 4 for use with the existing magneto spark ignition system further including a second set of breaker points, said trigger means including the second set of breaker points and providing said trigger pulse in response to actuation of the second set of breaker points.
6. The adapter assembly of claim 5 with said first circuit means including the first set of breaker points for charging said capacitor with the first set of breaker points in an open circuit condition, said trigger means providing said trigger pulse in response to the second set of breaker points being in an open circuit condition.
Description:
SUMMARY - BACKGROUND OF THE INVENTION
The present invention relates to capacitor discharge ignition systems and more particularly to an electrical ignition system for adapting a conventional magneto spark ignition system to a capacitor discharge ignition system.
CDI systems have many advantages over the conventional spark ignition system and in many existing engine installations, such as snowmobiles having engines with flywheel magnetos, in which spark ignition systems are already installed it would be desirable to convert those systems to CDI systems. The present invention is directed to such a conversion system in which a conventional spark ignition system can be easily and inexpensively converted to a CDI system.
In the present invention the conversion to a CDI system can be made without the need for disassembling the engine flywheel. Also the present invention is directed to conversion of a two cylinder two cycle engine having a magneto with an ignition winding and a set of points for each cylinder; in this system the points are used to fire or trigger the occurrence of ignition. Therefore it is an object of the present invention to provide a conversion system by which a conventional spark ignition system can be economically and simply converted to a CDI system. It is another object to provide a conversion system of the above described type in which the points are used to provide the trigger to initiate ignition. It is another general object of the present invention to provide a novel conversion system for converting a conventional spark ignition system to a CDI system .
Other objects, features, and advantages of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawing, in which a circuit diagram depicting the ignition adapter system of the present invention is shown.
In the drawing a portion of a conventional magneto ignition system is generally indicated by the numeral 10 and an Ignition Coil and Plug Section for use with the Magneto Portion 10 is generally indicated by the numeral 12. For a conventional magneto spark ignition system the Magneto Ignition Portion 10 would be connected directly with the Ignition Coil and Plug Section 12. In the present invention that system is converted into a CDI system by the use of the CDI Adapter Portion 14.
The Magneto Ignition Portion 10 includes a pair of circumferentially displaced magneto coils La and Lb which are secured to a stator 14 which is fixed under a flywheel 16. The flywheel is provided with a pair of permanent magnets 18 which are circumferentially spaced and which are of opposite polarities, radially. Capacitors Ca and Cb are connected across windings La and Lb, respectively, with one end of the capacitors and windings being connected to ground. The capacitors Ca and Cb are conventionally provided to minimize arcing across points Pa and Pb, respectively. Points Pa and Pb each have one contact connected to the associated capacitor Ca, Cb and another contact connected to ground. In the conventional existing system (to which Adapter Portion 14 applies) the Magneto Ignition Portion just described was connected directly to the Ignition Coil and Plug Section 12.
The Section 12 includes ignition coils ICa and ICb each having secondary windings connected across the electrodes of spark plugs Sa and Sb, respectively. In the existing circuit, then, the primary winding of coil ICa was connected directly to the ungrounded contact of points Pb (via a conductor indicated in dotted lines as 20a) and the primary winding of coil ICb was connected directly to the ungrounded contact of points Pa (via a conductor indicated in dotted lines as 20b). Thus in the pre-existing circuit the electrical energy of magneto winding La was transmitted to and used by coil ICb to fire plug Sb and the electrical energy of winding Lb was transmitted to and used by coil ICa to fire plug Sa. This arrangement is reversed in the adapter of the present invention for reasons to be seen.
The CDI Adapter Portion 14 includes a capacitor CDa which is electrically connected to the primary of coil ICa via conductor 22a and to the ungrounded contact of points Pa via conductor 24a, a charging diode D1a and conductor 26a. A diode D2a is reverse connected from conductor 26a to ground to provide a path for high voltage transients and also for negative potentials. A silicon controlled rectifier, SCRa, is connected to control the discharge of capacitor CDa into the primary of coil ICa. SCRa has its anode connected to conductor 24a and its cathode grounded. The gate of SCRa is connected to be triggered in a manner to be described. Thus capacitor CDa will be charged, when points Pa are opened from magneto winding La via conductor 26a, diode D1a and conductor 24a. At this time SCRa is not in conduction. Subsequently, SCRa is triggered to conduct and the charge on CDa can then flow to the primary of ICa to fire the plug Sa. One difficulty with CDI adapter systems is to find a direct, economical way to time the firing, i.e. via the discharge of the capacitor CDa. In the present invention this is done in a simple manner by providing the timing via the other set of points (Pb) and voltage generated by the other magneto winding (Lb).
Thus in the Adapter Portion 14 the gate of SCRa is connected to the points Pb and winding Lb via a blocking diode D3a and resistor Ra connected to conductor 26b. A diode D2b is reverse connected from conductor 26b to ground. Conductor 26b is also connected to capacitor CDb via charge diode D1b and conductor 24b. Capacitor CDb is connected to the primary of ignition coil ICb via conductor 22b. A silicon controlled rectifier, SCRb, has its anode connected to conductor 24b and its cathode grounded. The gate of SCRb is connected to the points Pa and magneto winding La via resistor Rb, blocking diode D3b, and conductor 26a. Capacitor CDb will be charged, when points Pb are opened, from magneto winding Lb via conductor 26b, diode D1b and conductor 24b. At this time SCRb is not in conduction. Subsequently SCRb is triggered to conduct and the charge in CDb will fire ICb. Note that points Pa and Pb are located approximately 180° apart and are normally closed and will be opened approximately 180° apart via a cam (generally indicated as 28) rotatable with the flywheel 16. When points Pa are opened (points Pb being closed) by cam 28 the voltage generated by winding La will quickly charge capacitor CDa; at the same time the voltage at La will trigger SCRb to discharge CDb and fire Sb. Subsequently when points Pb are opened (points Pa now being closed) by cam 28 the voltage generated by winding Lb will quickly charge capacitor CDb; at the same time the voltage at Lb will trigger SCRa (which was previously charged as noted) and to discharge CDa and fire Sa.
Note that, with the system as described, the plugs Sa and Sb are still fired in the same order relative to the same positional relationship of the flywheel 16 as occurred when the Magneto Ignition Portion 10 was conventionally connected directly to the Ignition Coil and Plug Section 12. The timing is still provided by the flywheel 16 as it actuates the points Pa and Pb. Since the flywheel 16 is connected directly to the engine crankshaft 17, the proper timing, relative to the position of the pistons, is provided. Since the non-rotatable components of Magneto Ignition Portion 10 are conventionally located under the flywheel 16 this means that the system of the present invention can be utilized without disturbing the flywheel by merely disposing the Adapter Portion between conductors 26a, 26b, 22a and 22b. Preferably the ignition coils ICa and ICb are high rise time coils, i.e. having a rise time of around two microseconds.
While it will be apparent that the preferred embodiment of the invention disclosed is well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the invention.
The present invention relates to capacitor discharge ignition systems and more particularly to an electrical ignition system for adapting a conventional magneto spark ignition system to a capacitor discharge ignition system.
CDI systems have many advantages over the conventional spark ignition system and in many existing engine installations, such as snowmobiles having engines with flywheel magnetos, in which spark ignition systems are already installed it would be desirable to convert those systems to CDI systems. The present invention is directed to such a conversion system in which a conventional spark ignition system can be easily and inexpensively converted to a CDI system.
In the present invention the conversion to a CDI system can be made without the need for disassembling the engine flywheel. Also the present invention is directed to conversion of a two cylinder two cycle engine having a magneto with an ignition winding and a set of points for each cylinder; in this system the points are used to fire or trigger the occurrence of ignition. Therefore it is an object of the present invention to provide a conversion system by which a conventional spark ignition system can be economically and simply converted to a CDI system. It is another object to provide a conversion system of the above described type in which the points are used to provide the trigger to initiate ignition. It is another general object of the present invention to provide a novel conversion system for converting a conventional spark ignition system to a CDI system .
Other objects, features, and advantages of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawing, in which a circuit diagram depicting the ignition adapter system of the present invention is shown.
In the drawing a portion of a conventional magneto ignition system is generally indicated by the numeral 10 and an Ignition Coil and Plug Section for use with the Magneto Portion 10 is generally indicated by the numeral 12. For a conventional magneto spark ignition system the Magneto Ignition Portion 10 would be connected directly with the Ignition Coil and Plug Section 12. In the present invention that system is converted into a CDI system by the use of the CDI Adapter Portion 14.
The Magneto Ignition Portion 10 includes a pair of circumferentially displaced magneto coils La and Lb which are secured to a stator 14 which is fixed under a flywheel 16. The flywheel is provided with a pair of permanent magnets 18 which are circumferentially spaced and which are of opposite polarities, radially. Capacitors Ca and Cb are connected across windings La and Lb, respectively, with one end of the capacitors and windings being connected to ground. The capacitors Ca and Cb are conventionally provided to minimize arcing across points Pa and Pb, respectively. Points Pa and Pb each have one contact connected to the associated capacitor Ca, Cb and another contact connected to ground. In the conventional existing system (to which Adapter Portion 14 applies) the Magneto Ignition Portion just described was connected directly to the Ignition Coil and Plug Section 12.
The Section 12 includes ignition coils ICa and ICb each having secondary windings connected across the electrodes of spark plugs Sa and Sb, respectively. In the existing circuit, then, the primary winding of coil ICa was connected directly to the ungrounded contact of points Pb (via a conductor indicated in dotted lines as 20a) and the primary winding of coil ICb was connected directly to the ungrounded contact of points Pa (via a conductor indicated in dotted lines as 20b). Thus in the pre-existing circuit the electrical energy of magneto winding La was transmitted to and used by coil ICb to fire plug Sb and the electrical energy of winding Lb was transmitted to and used by coil ICa to fire plug Sa. This arrangement is reversed in the adapter of the present invention for reasons to be seen.
The CDI Adapter Portion 14 includes a capacitor CDa which is electrically connected to the primary of coil ICa via conductor 22a and to the ungrounded contact of points Pa via conductor 24a, a charging diode D1a and conductor 26a. A diode D2a is reverse connected from conductor 26a to ground to provide a path for high voltage transients and also for negative potentials. A silicon controlled rectifier, SCRa, is connected to control the discharge of capacitor CDa into the primary of coil ICa. SCRa has its anode connected to conductor 24a and its cathode grounded. The gate of SCRa is connected to be triggered in a manner to be described. Thus capacitor CDa will be charged, when points Pa are opened from magneto winding La via conductor 26a, diode D1a and conductor 24a. At this time SCRa is not in conduction. Subsequently, SCRa is triggered to conduct and the charge on CDa can then flow to the primary of ICa to fire the plug Sa. One difficulty with CDI adapter systems is to find a direct, economical way to time the firing, i.e. via the discharge of the capacitor CDa. In the present invention this is done in a simple manner by providing the timing via the other set of points (Pb) and voltage generated by the other magneto winding (Lb).
Thus in the Adapter Portion 14 the gate of SCRa is connected to the points Pb and winding Lb via a blocking diode D3a and resistor Ra connected to conductor 26b. A diode D2b is reverse connected from conductor 26b to ground. Conductor 26b is also connected to capacitor CDb via charge diode D1b and conductor 24b. Capacitor CDb is connected to the primary of ignition coil ICb via conductor 22b. A silicon controlled rectifier, SCRb, has its anode connected to conductor 24b and its cathode grounded. The gate of SCRb is connected to the points Pa and magneto winding La via resistor Rb, blocking diode D3b, and conductor 26a. Capacitor CDb will be charged, when points Pb are opened, from magneto winding Lb via conductor 26b, diode D1b and conductor 24b. At this time SCRb is not in conduction. Subsequently SCRb is triggered to conduct and the charge in CDb will fire ICb. Note that points Pa and Pb are located approximately 180° apart and are normally closed and will be opened approximately 180° apart via a cam (generally indicated as 28) rotatable with the flywheel 16. When points Pa are opened (points Pb being closed) by cam 28 the voltage generated by winding La will quickly charge capacitor CDa; at the same time the voltage at La will trigger SCRb to discharge CDb and fire Sb. Subsequently when points Pb are opened (points Pa now being closed) by cam 28 the voltage generated by winding Lb will quickly charge capacitor CDb; at the same time the voltage at Lb will trigger SCRa (which was previously charged as noted) and to discharge CDa and fire Sa.
Note that, with the system as described, the plugs Sa and Sb are still fired in the same order relative to the same positional relationship of the flywheel 16 as occurred when the Magneto Ignition Portion 10 was conventionally connected directly to the Ignition Coil and Plug Section 12. The timing is still provided by the flywheel 16 as it actuates the points Pa and Pb. Since the flywheel 16 is connected directly to the engine crankshaft 17, the proper timing, relative to the position of the pistons, is provided. Since the non-rotatable components of Magneto Ignition Portion 10 are conventionally located under the flywheel 16 this means that the system of the present invention can be utilized without disturbing the flywheel by merely disposing the Adapter Portion between conductors 26a, 26b, 22a and 22b. Preferably the ignition coils ICa and ICb are high rise time coils, i.e. having a rise time of around two microseconds.
While it will be apparent that the preferred embodiment of the invention disclosed is well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the invention.