US3853106A

US3853106A - High frequency continuous-wave ignition energy for an internal combustion engine

Info

Publication number: US3853106A
Application number: US00067450A
Authority: US
Inventors: R Canup
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1970-08-27
Filing date: 1970-08-27
Publication date: 1974-12-10
Anticipated expiration: 1991-12-10
Also published as: ZA714724B; BR7105202D0; HK28076A; FR2102032A5; AU457965B2; DE2141778A1; NL7110971A; GB1308750A; ES394367A1; CA938996A; CH529294A; SE375131B; DE2141778B2; AU3159371A

Abstract

An ignition system useful with a high frequency continuous-wave source of spark energy, where a saturation winding controls the turning on and off of an oscillator which feeds the high frequency output. The system controls current flow to the saturation winding during a timed interval for each spark. The interval is under control of a timing shaft that has magnetic flux density change for inducing a signal in a control coil. The control coil acts to switch a flip-flop circuit which, in turn, controls the gating of current flow to the oscillator control winding.

Description

United States Patent 1191' Canup HIGH FREQUENCY CONTINUOUS-WAVE IGNITION ENERGY FOR AN INTERNAL COMBUSTION ENGINE [75] Inventor: Robert E. Canup, Richmond, Va.

[73] Assignee: Texaco Inc., New York, NY.

[22] Filed: Aug. 27, 1970 [21] Appl. No.: 67,450

[52] US. Cl. 123/148 E, 315/209 [51] Int. Cl. F02p I/00 [58] Field of Search 123/148 E, 149 A, 149 D; 315/209 [56] References Cited UNITED STATES PATENTS 3,356,896 12/1967 Shano 123/148 E 3,407,795 10/1968 Aiken et al 123/148 E 3,575,153 4/1971 Hardin 123/148 E 14 1 Dec. 10, 1974 3,593,696 7/1971 Guido 123/148 E Primary Examiner-Charles J. Myhre Assistant ExaminerRonald B. Cox Attorney, Agent, or Firm-T. H, Whaley; C. G. Reis [57] ABSTRACT An ignition system useful with a high frequency con tinuous-wave source of spark energy, where a saturation winding controls the turning on and off of an oscillator which feeds the high frequency output. The system controls current flow to the saturation winding during a timed interval for each spark. The interval is under control of a timing shaft that has magnetic flux density change for inducing a signal in a control coil. The control coil acts to switch a flip-flop circuit which, in turn, controls the gating of current flow to the oscillator control winding.

9 Claims, 4 Drawing Figures HIGH FREQUENCY CONTINUOUS-WAVE IGNITIONENERGY FOR AN INTERNAL COMBUSTION ENGINE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to internal combustion engine ignition systems in general, and particularly concerns such an ignition system that is applicable to the type of ignition spark that is created by continuous-wave energy during the entire sparking interval.

2. Description of the Prior Art While there are various known arrangements for providing high frequency sparking energy to be used with internal combustion engine systems, there is in particular, an ignition system that employs an oscillator to generate high frequency signals and which includes a saturation winding for controlling the oscillator. Such an ignition system is shown and described in a prior US. Pat. No. 3,407,795, issued Oct. 29, 1968, inventors R. W. Aiken, et al. However, that system employed conventional breaker points to control current flow in the control winding. Such conventional breaker point contacts are subject to point bounce, erosion and wearoff of the cam rubbing block. While such difficulties per se are, of course, not unique in regard to the particular type of ignition system mentioned above; the conventional ignition systems are not such that the present invention may be employed. And furthermore, while there have been different arrangements proposed for eliminating the use of conventional breaker points,

none of them are applicableto the type of ignition system that employs a saturation winding for timing the spark and its duration.

SUMMARY OF THE INVENTION It comprises in combination electromagnetic means associated with said shaft for providing an initial pulse of one polarity and a terminal pulse of the opposite polarity, separated by a pre-determined degree of shaft angle rotation, both pulses for each cylinder of said engine. It also comprises electronic means actuated by both said pulses for cutting off said current flow when said initial pulse appears and for restoring said current flow when said terminal pulse appears.

Again briefly, the invention relates to a system for use in a high frequency continuous-wave ignition system for an internal combustion engine. The said system employs: (a) a control winding for starting and stopping said high frequency continuous-wave energy; and it has (b) a shaft for timing said energy relative to said engine. The invention comprises improved means for controlling current flow through said winding (a) in accordance with a predetermined amount of shaft (b) angle rotation, and it comprises in combination (c) a rotor of magnetically permeable material carried by said shaft. The rotor has a plurality of radial projections with concentric arcuate extremities extending concentrically over an arc equal to said predetermined rotation angle. It also comprises (d) a stator of magnetically permeable material including a permanent magnet and a closed path for the magnetic flux which includes said rotor (c), and (e) a plurality of pointed projections on said stator (d) matching in number the projections on said rotor (c) and forming a minimum air gap when in radial registration with said rotor projections throughout said are. It also comprises (f) a coil located in inductive relation'with said magnetic flux, and (g) a flipflop circuit comprising a pair of transistors and having said coil (f) connected therein for switching same. In addition, it comprises (h) a diode and (i) transistor connected in series with said control winding (a) for controlling current flow therethrough, and (j) a PNP transistor connected to the base of said transistor (i).

Finally, it also comprises (k) a circuit for connecting BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects and benefits of'the invention will be more fully set forth below in connection with the best mode contemplated by the inventor of carryingout the invention and in connection with which there are illustrations provided in the drawings,

wherein: I

FIG. 1 illustrates a high frequency continuouswave ignition system according to the prior art, e.g. the

above mentioned US. Pat. No. 3,407,795;

FIG. 2 is a circuit diagram illustrating an electronic control system according to the inventions;

FIG. 3 is a top plan view illustrating schematically a timing shaft and related rotor and stator elements, according to the invention; and

FIG. 4 is a longitudinal cross-sectional view of the shaft and related elements that are illustrated in FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENT It is to be noted that this invention is particularly applicable to the controlling of an ignition system like that shown in the above mentioned US. Pat. No. 3,407,795, although it could equally well be employed with any ignition system that makes use of a corresponding type of control winding for starting and stopping the generation of spark energy during a spark interval. It will be observed that the FIG. [system is substantially the same as the system of the foregoing US. patent, insofar as the elements illustrated there are concerned. Consequently, no detailed explanation is necessary here and it is sufiicient to observe that the system employs a Jensen type oscillator 11. This oscillator has a control winding 12 which acts to saturate a magnetic core 15 of the oscillator 11 when the winding has current flowing therein.

When spark energy is desired, the current flow through winding 12 is cut 05 and this creates instantaneous starting of the oscillator 11 in the manner that is explained in the aforementioned U.S. Pat. No. 3,407,795. The oscillator 11 provides high frequency continuouswave energy in the output circuit shown that leads to a distributor 16 and a spark plug 17, all as illustrated.

Referring to FIG. 2, it is to be noted that the winding 12 and the magnetic core 15 are shown here in an electronic control circuit that is in accordance with the in-- vention. This circuit determines the timing of intervals during which current flow through the control winding 12 is cut off, sothat the oscillator 1 1 (FIG. 1) will oscillate and supply spark energy.

Control of the foregoing intervals is timed to be in proper synchronization with the internal combustion engine, by having the control circuit (illustrated in FIG.

:2) acted upon by a spark timing element. Such timing element includes a shaft (FIGS. 3 and 4) that is mechanically rotated by direct connection with the engine (not shown) in a conventional manner. This shaft is illustrated in FIGS. 3 and 4 along with a rotor 21 that-is constructed of magnetically permeable material. It is attached to the shaft 20 for rotation therewith at all times, and it is in alignment with a top annular portion 24 of a stator 25. The stator includes a lower disc-like portion 26 for completing a magnetic flux path through I the stator and rotor of the combined elements.

Stator includes a cylindrical magnet section 29 that provides a source of magnetic flux for the aforementioned flux path. It will be appreciated by one skilled in the art that, while it may not be as mechanically feasible, the magnetic flux might be provided by other means, e.g. by having an electromagnetic coil (not shown) with current flow therein. However, in any event, there is an induction coil 32 that is situated in inductive relation to the magnetic field created by the flux through the foregoing flux path. Consequently, changes in flux density will generate an EMF in the coil 32.

It will be observed that on the inner periphery of the annular portion 24 of the stator 25, there are a plurality of pointed projections 33. These are equal in number to the number of cylinders of the internal combustion engine for a four cycle engine, in order to provide the proper timing. The projections 33 extend radially inward into close clearance from the radially outermost surfaces of a corresponding plurality of projections 36 I that are located on the periphery of the rotor 21. With the foregoing structure, when the rotor projections 36 are in correspondence radially with the stator projections 33, there will be a minimum size air gap that is distributed around among all of the pairs of projections.

It will be noted that the structure of rotor 21 includes a corresponding number of recessed portions 37 between the projections 36. These are provided so that during the rotation of shaft 20, when projections 36 are out of correspondence radially with the projections 33 (on the stator), there will be a very substantial air gap created in the flux path.

It is to be noted also, that while the circumferential widths of the rotor projections 36 are illustrated as being a relatively large angle, this is an exaggeration merely for the purposes of illustration of the principles involved. Actually, the angle will be smaller in accordance with conventional practice.

Referring to FIG. 2 again, it will be noted that induction coil 32 is located in a flip-flop circuit 40 which includes a pair of

transistors

41 and 42 that are connected in a known manner for creating a bi-stable oscillator that can be switched from one state to the other and will remain in either state until switched to the other. Each stable state has one of the

transistors

41 or 42 conducting while the other is cut off. The foregoing flip-flop circuit 40 includes one branch circuit with a resistor-"45 that is connected between a source of 8+ voltage 44, i.e. the battery indicated in FIG. 1 and the collector electrode of the transistor 41. Also, the emitter of transistor 41 is part of the circuit. It is connected to one end of another resistor 46 that has the other end thereof connected to ground, as illustrated.

The other transistor 42 is connected in another branch circuit that leads from the B+ voltage source 44 through a pair of

resistors

49 and 50 that are connected in series. This circuit leads to the collector electrode of the transistor 42. The circuit continues from the emitter element of transistor 42 and then it is con nected over via a circuit connection 53 to the same end of the resistor 46 as was the emitter of the other transistor 41. a

The base electrode of transistor 42 is connected to one end of a resistor 56 that has the other end thereof connected to ground, as illustrated. The base of transistor 42 is also connected via a circuit wire 57 to one end of a resistor 60 that has a shunting capacitor 61 connected there across. The other end of resistor 60 is connected over to the collector electrode of transistor 41 in the other branch. Similarly, with respect to transistor 41, there is a connection from the base electrode thereof to one end of a resistor 64 that has a shunting capacitor 65 connected there across. The other end of resistor 64 is connected via a wire 66 back over to the collector electrode of the transistor 42.

It will be noted that the elements of the flip-flop circuit 40 which have been described, provide for a cross action from one transistor to the other such that the bistable state mentioned above, is created. This type of circuit is now well known to those skilled in this art.

Continuing to refer to FIG. 2, it will be observed that current flow through the winding 12 (control of oscillator 11 FIG. 1) is under control of a transistor 70. This transistor is connected in series with a diode 71 so that both together are in series with the winding 12, while the transistor controls current flow therethrough. The state of conduction or non-conduction of transistor is controlled by a PNP transistor 74 that has the collector electrode thereof .connected directly to the base of transistor 70 by a circuit wire 75. The PNP transistor 74 is in turn controlled for determining current flow therethrough by having a circuit connection 78 that goes from the base electrode of transistor 74 to a connection point 76 that is between

resistors

49 and 50 of the flip-flop circuit 40. Consequently, when the transistor 42 is conducting, there will be sufficient voltage drop across resistor 49 to apply enough potential between the emitter and the base of PNP transistor 74 to cause it to conduct. The resulting current flow through a resistor 79 will provide a voltage drop that causes a potential to be applied over the wire to the base of the transistor 70 such that it will conduct.

On the other hand, when the flip-flop circuit 40 has been switched to the opposite state from that just described above, the transistor 42 will be no longer conducting. Them, the transistor 41 will conduct and transistor 42 will be cut off. Therefore, the current flow through PNP transistor 74 will cease and in turn, the transistor 70 will no longer conduct. Consequently, the current flow through control winding 12 will be cut off.

It may be noted that as an additional feature, there is included an arrangement for making sure that the high frequency spark voltage is not continuously supplied in case the engine should stop with the shaft 20 so positioned that the rotor and stator elements are in correspondence with the matching

projections

33 and 36 in radial alignment. Such conditions would leave the flip-flop circuit 40 switched over so as to cut off the current flow in control winding 12 and thus cause the oscillator 11 to continue to produce spark voltage output to the engine. Since these conditions would be dangerous to personnel handling the engine, provision is made for switching the flip-flop circuit 40 back to the other state so as to cause current to flow in control winding 12 and therefore cut off oscillator 11 and the generation of spark energy. I

In order to accomplish the foregoing, there is a timing circuit that includes a unijunction transistor oscillator 82 (see FIG. 2). This oscillator is made up of a unijunction transistor 83 that has itscontrol electrode connected between a resistor 86 and a capacitor 87 which are connected in series. These provide a time constant effect so that a pulse will be obtained after a predetermined time delay in case the engine has stopped as indicated above. Such pulse will cause the flip-flop circuit to be switched back so as to cut off the oscillator 11.

The other two electrodes of the unijunction transistor 83 are connected respectively to one end of each of two

resistors

90 and 91. Resistor 90 has the other end thereof connected via a circuit wire 94 to the B+ voltage source. The other end of resistor 91 is connected to ground, as illustrated. In addition, there is a capacitor 95 that is connected between one end of the resistor 56 of the transistor 42 branch of the flip-flop circuit, and one end of resistor 91 in the unijunction transistor 83 circuit.

OPERATION As indicated above, the oscillator 11 (FIG. 1) is controlled, turned on and off, by the flow of direct current through winding 12 of the timing transformer (core As long as no current flows, the oscillator will run and a spark is available. When current flows, the timing transformer is saturated and insufficient feedback is present for the oscillatorto oscillate. However, for the oscillator to start, the flow of current through the startstop winding 12 of the timing transformer (core 15) must be interrupted abruptly. Such interruption was accomplished with mechanical switching at the breaker points, in prior arrangements.

With this invention, the foregoing interruption is accomplished using the electronic circuit and related elements that are illustrated in FIG. 2. Its operation may be described as follows:

The

transistors

41 and 42 and allied components compose a conventional flip-flop circuit with the exception of winding 32 which has replaced the conventional base to ground resistor of transistor 41. The coil 32 is the pickup coil on the stator 25 that is associated with the timing shaft 20.

Assuming that transistor 42 is on, the current flow through resistor 49 will cause a sufficient voltage differential between the base and emitter of the PNP transistor 74 so that it will be conducting. This will cause a sufficient voltage to be developed across resistor 79 so that transistor will be conducting. The timing, or control, winding 12 of the oscillator 11 is connected through the diode 71 to the collector of transistor 70. Sufficient current flows so that no oscillation of the basic oscillator 11 of the internal combustion engine ignition system can occur.

When the leading edges of the projections 36 on the rotor 21, pass the stationary points of the stator projections 33, a positive voltage pulse is developed across the coil 32. This voltage pulse applied to the base of the off transistor 41 will cause this transistor to start to conduct. The positive pulse applied to the base coil will appear as a negative pulse at the collector. This negative pulse is coupled through capacitor 61 and resistor 60 to the base of the 'on transistor 42. This negative pulse on the base appears as a positive pulse on the collector (amplified by the gain of the transistor) of transistor 42. This positive pulse is coupled to the base of transistor 41 by resistor 64 and capacitor 65. This cascading action causes the system to flip and transistor 41 now becomes conducting and transistor 42 nonconducting. When transistor 42 becomes nonconducting, PNP transistor 74 no longer conducts, hence there will be no forward bias on the transistor 70 and it will cease to conduct. When the flow of current through the timing transformer (core 15) ceases, the oscillation starts and a spark occurs. As long as transistor 42 is off, the oscillation will continue and a spark will be available for ignition.

When the trailing edges of the projections 36 on the rotor 21 pass the points of projections 33 on the stator 25, a change of flux will occur and a negative voltage pulse will be induced in the coil 32. This negative pulse will be applied to the base of transistor 41 which is now the on transistor. This pulse will cause the flip-flop 40 to. flip so that transistor 42 will be conducting and transistor 41 off. This, in turn, will cause transistor 70 to conduct which will stop the oscillation of the ignition system. I

ADDITIONAL ELEMENTS It may be noted that there is a Zener diode 98 (FIG. 2) that is connected between the B+ voltage supply and ground. This is employed to regulate the amplitude of the B+ voltage and consequently a single electronic system may be used with different values of battery voltage.

It may be noted also that the diode 71 is provided for preventing voltage induced in the control winding 12 (FIGS. 1 and 2) from damaging the transistor 70 (FIG. 2) during the time that the Jensen type oscillator 11 (FIG. 1) is running.

While a particular embodiment of the invention haS been described in considerable detail above, in accordance with the applicable statutes, this is not to be taken as in any way limiting the invention, but merely as being descriptive thereof.

I claim:

1. In a.high frequency continuouswave ignition system for an internal combustion engine, said system employing a control winding for starting and stopping said high frequency continuous-wave energy, and having a shaft for timing said energy relative to said engine,

improved means for controlling current flow through said winding in accordance with a predetermined amount of shaft angle rotation, comprising in combination electromagnetic means associated with said shaft for providing an initial pulse of one polarity and a terminal pulse of the opposite polarity separated by a predetermined degree of shaft angle rotation and both pulses for each cylinder of said engine, and

bistable oscillator means actuated by both said pulses for cutting off said current flow when said initial pulse appears and for restoring said current flow when said terminal pulse appears.

2. The invention according to claim 1, wherein said electromagnetic means comprises a coil,

a rotor carried by said shaft, and

a stator,

said rotor and said stator providing a permeable magnetic flux path having a gap therein and said coil being located in inductive relationship to said flux, and wherein said electronic'means comprises a flip-flop circuit having said coil connected therein.

3. The invention according to claim 2, wherein said gap varies depending upon the angular position of said shaft from maximum to a predetermined minimum at the generation of one of said pulses and from said minimum back to maximum at the generation of the other of said pulses, and wherein said electronic means further comprises current flow control means in series with said control winding, and

circuit means for connecting said current flow control means to one branch of said flip-flop circuit.

4. The invention according to claim 3, wherein said minimum gap produces said initial pulse at the beginning and said terminal pulse at the ending thereof, and wherein said current flow means comprises a diode, and

a transistor, and wherein said circuit means comprises a PNP transistor connected to the base of said transistor.

5. The invention according to claim 4, wherein said flip-flop circuit comprises a pair of transistors.

6. The invention according to claim 2, further including ing b. a shaft for timing said energy relative to said engine,

improved means for controlling current flow through said winding (a) in accordance with a predetermined amount of shaft (b) angle rotation, comprising in combination c. a rotor of magnetically permeable material carried by said shaft (b) and having a plurality of radial projections with concentric arcuate extremities extending concentrically over an arc equal to said predetermined rotation angle,

d. a stator of magnetically permeable material including a permanent magnet and a closed path for the magnetic flux which includes said rotor (c),

e. a plurality of pointed projections on said stator ((1) matching in number of projections on said rotor (c) and forming a minimum air gap when in radial registration with said rotor projections throughout said arc,

f. a coil located in inductive relation with said magnetic flux,

g. a flip-flop circuit comprising a pair of transistors and having said coil (f) connected therein for switching same,

h. a diode and i. transistor connected in series with said control winding (a) for controlling current flow therethrough,

j. a PNP transistor connected to the base of said transistor (i),

k. a circuit for connecting said PNP transistor to one branch of said flip-flop circuit (g) for making said transistor (i) become non-conducting when said flip-flop (g) is in one state and return to being conducting when it (g) is in the other state, and

l. a unijunction transistor oscillator connected to one side of said flip-flop (g) for switching it (g) back to said other state after a predetermined time delay in case said engine stops with it (g) having been switched to said one state.

9. In a high frequency continuous-wave ignition system for an internal combustion engine, said system employing a control winding for starting and stopping said high frequency continuous-wave energy, and having a shaft for timing said energy relative to said engine, improved means for controlling current flow through said winding in accordance with a predetermined amount of shaft angle rotation, comprising in combination means associated with said shaft for providing an initial pulse of one polarity and a terminal pulse of the opposite polarity separated by a predetermined degree of shaft angle rotation and both pulses for each cylinder of said engine, and

bistable oscillator means actuated by both said pulses for cutting off said current flow when said initial pulse appears, and for restoring said current flow when said terminal pulse appears.

Claims

1. In a high frequency continuous-wave ignition system for an internal combustion engine, said system employing a control winding for starting and stopping said high frequency continuouswave energy, and having a shaft for timing said energy relative to said engine, improved means for controlling current flow through said winding in accordance with a predetermined amount of shaft angle rotation, comprising in combination electromagnetic means associated with said shaft for providing an initial pulse of one polarity and a terminal pulse of the opposite polarity separated by a predetermined degree of shaft angle rotation and both pulses for each cylinder of said engine, and bistable oscillator means actuated by both said pulses for cutting off said current flow when said initial pulse appears and for restoring said current flow when said terminal pulse appears.

2. The invention according to claim 1, wherein said electromagnetic means comprises a coil, a rotor carried by said shaft, and a stator, said rotor and said stator providing a permeable magnetic flux path having a gap therein and said coil being located in inductive relationship to said flux, and wherein said electronic means comprises a flip-flop circuit having said coil connected therein.

3. The invention according to claim 2, wherein said gap varies depending upon the angular position of said shaft from maximum to a predetermined minimum at the generation of one of said pulses and from said minimum back to maximum at the generation of the other of said pulses, and wherein said electronic means further comprises current flow control means in series with said control winding, and circuit means for connecting said current flow control means to one branch of said flip-flop circuit.

4. The invention according to claim 3, wherein said minimum gap produces said initial pulse at the beginning and said terminal pulse at the ending thereof, and wherein said current flow means comprises a diode, and a transistor, and wherein said circuit means comprises a PNP transistor connected to the base of said transistor.

6. The invention according to claim 2, further including timing means connected to one side of said flip-flop circuit for restoring said current flow after a predetermined delay in case said engine stops with said shaft between said initial and terminal pulses.

7. The invention according to claim 6, wherein said timing means comprises a unijunction transistor oscillator.

8. In a high frequency cOntinuous-wave ignition system for an internal combustion engine, said system employing a. a control winding for starting and stopping said high frequency continuous-wave energy, and having b. a shaft for timing said energy relative to said engine, improved means for controlling current flow through said winding (a) in accordance with a predetermined amount of shaft (b) angle rotation, comprising in combination c. a rotor of magnetically permeable material carried by said shaft (b) and having a plurality of radial projections with concentric arcuate extremities extending concentrically over an arc equal to said predetermined rotation angle, d. a stator of magnetically permeable material including a permanent magnet and a closed path for the magnetic flux which includes said rotor (c), e. a plurality of pointed projections on said stator (d) matching in number of projections on said rotor (c) and forming a minimum air gap when in radial registration with said rotor projections throughout said arc, f. a coil located in inductive relation with said magnetic flux, g. a flip-flop circuit comprising a pair of transistors and having said coil (f) connected therein for switching same, h. a diode and i. transistor connected in series with said control winding (a) for controlling current flow therethrough, j. a PNP transistor connected to the base of said transistor (i), k. a circuit for connecting said PNP transistor to one branch of said flip-flop circuit (g) for making said transistor (i) become non-conducting when said flip-flop (g) is in one state and return to being conducting when it (g) is in the other state, and l. a unijunction transistor oscillator connected to one side of said flip-flop (g) for switching it (g) back to said other state after a predetermined time delay in case said engine stops with it (g) having been switched to said one state.

9. In a high frequency continuous-wave ignition system for an internal combustion engine, said system employing a control winding for starting and stopping said high frequency continuous-wave energy, and having a shaft for timing said energy relative to said engine, improved means for controlling current flow through said winding in accordance with a predetermined amount of shaft angle rotation, comprising in combination means associated with said shaft for providing an initial pulse of one polarity and a terminal pulse of the opposite polarity separated by a predetermined degree of shaft angle rotation and both pulses for each cylinder of said engine, and bistable oscillator means actuated by both said pulses for cutting off said current flow when said initial pulse appears, and for restoring said current flow when said terminal pulse appears.