US3861370A

US3861370A - Breakerless distributor and ignition system utilizing same

Info

Publication number: US3861370A
Application number: US346346A
Authority: US
Inventors: Homer E Howard
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-03-30
Filing date: 1973-03-30
Publication date: 1975-01-21
Anticipated expiration: 1992-01-21

Abstract

An ignition system comprising at least one magnet and an electronic switch arranged so that the strength of the magnetic field at the electronic switch varies. The electronic switch is responsive to the magnetic field being of a first strength level for placing the electronic switch in a conductive state and responsive to the magnetic field being of a second strength level for placing the electronic switch in a nonconductive state. An ignition circuit is responsive to the state of the electronic switch for providing ignition sparks for the engine.

Description

[ 5] Jan. 21, 1975 United States Patent [1 1 Howard BREAKERLESS DISTRIBUTOR AND IGNITION SYSTEM UTILIZING SAME [76] Inventor: Homer E. Howard, 2024 Paloma Dr., Costa Mesa, Calif. 92627 [22] Filed: Mar. 30, 1973 [21] Appl. N0.: 346,346

[52] U.S. Cl. 123/148 E, 315/209 [51] Int. Cl. F02p 3/06 [58] Field of Search 123/148 E; 315/209 [56] References Cited UNITED STATES PATENTS 2,924,633 2/1960 Sichling et a1 123/148 E 3,161,803 12/1964 Knittweis 123/148 E 3,241,538 3/1966 Hugenholz.... 123/148 E 3,297,009 l/l967 Sasaki et a1, 123/148 E 3,316,448 4/1967 Hardin et al. 123/148 E 3,357,416 12/1967 Huntzinger 123/148 E 3,361,123 1/1968 Kasama et a1 123/148 E 3,373,729 3/1968 Lemen 123/148 E 3,517,260 6/1970 Oishi 3,587,551 6/1971 Harrow 123/148 E Primary ExaminerManuel A. Antonakas Assistant ExaminerJ Cranson Attorney, Agent, or FirmGord0n L. Peterson [57] ABSTRACT 4 Claims, 7 Drawing Figures Ignition Circui'l" Shmltt Tagger Patented Jan. 21,1975

Engine BREAKERLESS DISTRIBUTOR AND IGNITION SYSTEM UTILIZING SAME BACKGROUND OF THE INVENTION An internal combustion engine requires a timing device for timing the sparks supplied to the engine to ignite the fuel-air mixture. For many years, this timing function has been carried out by cam actuated breaker points in the distributor. Breaker points have numerous disadvantages. For example, the cam and cam actuator wear and require many readjustments during the normal life of the engine. The points are subject to bounce at high speeds thereby causing false ignition signals. The points also tend to pit and corrode and must be frequently replaced.

Several attempts have been made to obviate the problems noted above. For example, electro optical and magnetic pulse systems have been proposed. Unfortunately, the electro-optical system is subject to malfunction due to the optics becoming contaminated with dirt, oil, grease, etc. The magnetic pulse system is a rate of change device whose output is proportional to the speed at which it is driven, i.e., engine speed. Accordingly, these devices do not generate adequate energy at lower engine speeds and this causes excessive wear on the starter and battery. The shortcomings of these systems result in reduced engine performance, lower combustion efficiency, and greatly increased exhaust polluant emissions.

SUMMARY OF THE INVENTION The present invention provides a breakerless distributor which is not subject to the problems experienced with the above-described systems. The breakerless distributor of this invention employs an electronic switch which is operated magnetically at the desired rate to provide ignition timing signals. The ignition timing signals provided by the breakerless distributor are similar to the timing signals provided by the conventional breaker points. Accordingly, the breakerless distributor of this invention can be used with various kinds of ignition circuits including conventional ignition circuits and electronic ignition circuits.

The electronic switch is operated in response to the change in strength of a magnetic field. This can be implemented, for example, by employing a magnet and an electronic switch which is sensitive to changes in strength of the magnetic field. The magnet is a pennanent magnet and the change in strength of the magnetic field at the electronic switch can be brought about in different ways. In one preferred construction, the magnet is mounted on a rotor or rotatable element and rotation of this rotor changes the distance between the magnet and the electronic switch thereby varying the strength of the field at the electronic switch.

The electronic switch has conductive and nonconductive states. The electronic switch will assume one of its states when the field strength is below a predetermined level and will assume the other of its states when the field strength is above a predetermined level. The operation of the electronic switch causes a change of potential which constitutes timing signals of the type provided by a conventional breaker point system.

The electronic switch may take the form of a signal generator having several components. For example, the portion of the magnetic switch which is sensitive to change of strength of the magnetic field may be a Hall generator. As is well known, a Hall generator provides an analog signal the amplitude of which varies with strength of the magnetic field. The analog signal is amplified and may be digitized by a Scmitt trigger. The digital signal is then amplified and used to control a driver which in turn provides the timing signals.

The typical automotive electrical system produces many transients. It is important that the components of the breakerless distributor be protected from these transients. To protect the electronic switch from positive voltage spikes, a Zener diode is coupled in parallel with the electronic switch. To provide further protection for very short duration transients, a capacitor is coupled in parallel with the Zener diode. A diode is coupled between ground and the electronic switch to prevent negative transients from affecting the electronic switch.

The invention can best be understood by reference to the following description taken in connection with the accompanying illustrative drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic view of an ignition system constructed in accordance with the teachings of this invention.

FIG. 2 is a top plan view of the rotor.

FIG. 3 is a diagram showing voltage signals with respect to time at various location in the breakerless distributor.

FIG. 4 is a somewhat schematic elevational view showing another way of varying the strength of the magnetic field at the Hall generator.

FIG. 5 is a top plan view of the rotor employed in the embodiment of FIG. 4.

FIG. 6 is a view similar to FIG. 4 of still another way of varying the strength of the magnetic field at the Hall generator.

FIG. 7 is an elevational view of the rotor employed in the embodiment of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. 1, a distributor 11 is coupled to an ignition circuit 13 and to an engine 15. The distributor 11 and the ignition circuit 13 constitute an ignition system for the engine 15.

The distributor 11 includes a rotatable element or rotor 17, an electronic switch or signal generator 19, and a protective circuit 20. The rotor 17 is suitably mounted for rotation and is driven by the engine 15. A plurality of permanent magnets 21 are carried by, and embedded, in the rotor 17. Although the magnets 21 could be mounted on the rotor 17 in different ways, in the embodiment illustrated, each of the magnets terminates flush with the peripheral surface of the rotor. Similarly, any number of the magnets 21 may be provided so long as an appropriate relationship between engine rpm and speed of rotation of the rotor 17 is maintained. For example, one of the magnets 21 may be provided for each of the cylinders of the engine 15. As shown by way of example in FIG. 2, eight of the magnets 21 are carried by the rotor 17 and are equally spaced circumferentially.

The distributor 11 includes a conductor 23 coupled through a resistor 25 to the positive side of a battery 27 and a conductor 29 coupled to ground through a diode 31. The battery 27 may be the conventional automotive battery if the system of FIG. 1 is employed in an automotive vehicle.

The electronic switch 19 includes a Hall generator 33 which is coupled across the conductors 23 and 29 and which is located in close proximity to the rotor 17. As is well known, the Hall generator 33 provides an output voltage signal V1 (FIG. 3) which is proportional to the strength of the magnetic field at the Hall generator 33. Hall generators are commercially available. The Hall generator 33 is suitably fixedly mounted.

The analog voltage signal V1 is fed to an a amplifier 35 which is also shown as coupled across the conductors 23 and 29. The amplifier 35 provides an output voltage signal V2 (FIG. 3) which is analog in form and of greater amplitude than .the signal V1.

To cause the electronic switch 19 to operate in an onoff mode, the analog signal V2 is digitized by a Schmitt trigger 37. The Schmitt trigger 37 converts the analog input signal V2 into a square wave voltage output signal V3 (FIG. 3) in a well known manner. Specifically, the signal V3 is high whenever the signal V2 is above a predetermined threshold X (FIG. 3) and is low whenever the amplitude of the voltage signal V2 is below the threshold X. The signal V3 is amplified by an amplifier 39 to provide an amplified square wave voltage signal V4.

The amplified square wave signal V4 is applied to the base of a transistor or driver 41 which is coupled across the leads 23 and 29. A resistor 43 is coupled between the collector of the transistor 41 and the conductor 23. The transistor 41 conducts when the signal V4 is high and is nonconductive when the signal V4 is low. Accordingly, this provides a square wave voltage output signal V5 which is high when the signal V4 is low and is low when the signal V4 is high.

The signal V5 is applied to the ignition circuit 13. The signal V5 is substantially identical to the square wave signal which would result from opening and closing the conventional breaker points. Specifically, the leading edge 44 and the trailing edge 46 of each square wave correspond in time to closing and opening of the points, respectively, in a conventional breaker point system. Either or both of the leading and trailing edges of each square wave of the signal V5 may constitute a timing signal.

The ignition circuit 13 may be a capacitor discharge ignition circuit of the type shown in US. Pat. No. 3,704,699 or in my copending application Ser. No. 331,685. Alternatively, the circuit 13 may be an electronic or conventional ignition circuit. The ignition circuit 13 is coupled to the battery 27 and to the ground.

The ignition circuit 13 supplies electrical energy for an ignition spark to the engine 15 on each trailing and- /or leading edge of each square wave of the signal V5 depending upon the type of ignition circuit 13 employed. The engine 15 is of the internal combustion spark ignition type and utilizes such energy to provide sparks to ignite the fuel-air mixture in the cylinders thereof. The engine 15 may be used for various purposes including automotive, industrial, aircraft and marine purposes. In addition, the engine also drives the rotor 17 of the distributor 11 thereby assuring a proper timed relationship between rotation of the rotor and engine speed.

The electronic switch 19 and in particular the Hall generator 33 must be protected against voltage transients. To accomplish this, the protective circuit 20, which includes a Zener diode 45, a capacitor 47, the resistor 25, and the diode 31 is provided. The Zener diode 45 is in parallel with the electronic switch 19 and is arranged to operate in its reverse biased region. The resistor 25 and the Zener diode 45 limit the voltage across the conductors 23 and 29 regardless of variations in supply voltage from the battery 27. The capacitor 47 is coupled between the conductors 23 and 29 in parallel with the Zener diode 45 and the electronic switch 19. The capacitor 47 has a faster response than the Zener diode 45, and accordingly this protects against short duration voltage transients. The diode 31 is arranged with its anode coupled to the conductor 29 and its cathode coupled to ground. The diode 31 protects against negative spikes in that a negative voltage spike reverse biases the diode.

In operation, the engine 15 rotates the rotor 17. This sequentially brings the magnets 21 into close proximity to the Hall generator 33. As one of the magnets 21 approaches the Hall generator 33, the amplitude of the signal V1 increases. When the magnet 21 reaches its closest point to the Hall generator 33, the amplitude of the signal V1 is at a maximum. As the rotor 17 rotates this magnet 21 away from the Hall generator 33, the amplitude of the signal V1 diminishes to a value which may be substantially zero. Subsequently, a second of the magnets 21 is brought sufficiently close to the Hall generator 33 so that the strength of the magnetic field at the Hall generator initiates a new wave of the signal V1.

The signal V1 is amplified by the amplifier 35 to provide the signal V2 which in turn is converted to the square wave signal V3 by the Schmitt trigger 37. The signal V3 is amplified by the amplifier 39 to provide the signal V4 which in turn is used to control the transistor 41 to provide the signal V5. The signal V5 includes leading and trailing

edges

44 and 46, either or both of which may constitute a timing signal which may be used by the ignition circuit 13 to provide a spark for combustion within a cylinder of the engine 15. The protective circuit 20 functions as described above to protect the electronic switch 19 from transients.

FIGS. 4 and 5 show a modification of the present invention in which portions corresponding to portions shown in FIG. 1 are designated by corresponding reference numerals followed by the letter a. In the embodiment of FIG. 4, only one magnet 21a is provided. The magnet 21a is fixedly mounted on a suitable fixed base or supporting structure 49. The rotor 17a includes a shield or plate 51. The rotor 17a differs from the rotor 17 (FIG. 1) in that it carries no magnets and in that it has a plurality of radially opening slots 53 in the periphery of the shield 51. The slots 53 are equally spaced circumferentially. A portion of the shield 51 is interposed between the magnet 21a and the Hall generator 330. The Hall generator 33a is suitably fixedly mounted.

The shield 51 is constructed of a material such as a ferrous material which will shield the magnetic field produced by the magnet 21a from the Hall generator 33a. Accordingly, the strength of the magnetic field at the Hall generator 33a can be varied by rotation of the rotor 17a. The strength of the magnetic field at the Hall generator 33a will depend upon the extent to which, if any, one of the slots 53 is interposed between the magnet 21a and the Hall generator. The dimensions and number of the slots 53 and the speed of rotation of the rotor 17a can be selected to appropriately tailor the voltage signal V1 (FIG. 3) which is produced by the Hall generator 330.

FIGS. 6 and 7 show a second modification which is similar to the modification shown in FIG. 4. ln FIGS. 6 and 7 portions of the device corresponding to portions of the modification of FIGS. 4 and 5 are designated by corresponding reference characters except that the letter b is used in lieu of the letter a. The shield 51b includes a cylindrical flange 55 which is interposed between the magnet 21b and the Hall generator 33b, both of which are fixedly mounted on the fixed base 49b. The flange 55 of the shield 51b has downwardly opening slots 53b which are equally spaced circumferentially. Rotation of the rotor 17b varies the strength of the magnetic field at the Hall generator 33b in that the slots 53b are sequentially brought between the magnet 21b and the Hall generator. Thus, the modification of FIGS. 6 and 7 functions in the same manner as the modification of FIGS. 4 and 5.

The embodiments of FIGS. 4-7 may be identical to the embodiment of FIGS. 1-3 in all respects not specifically shown or described herein. The embodiment which is selected for a particular application will vary depending upon various requirements including the size and shape of the space available for the components.

Many changes, modifications, and substitutions may be made by one having ordinary skill in the art without necessarily departing from the spirit and scope of this invention.

I claim:

1. A breakerless distributor connectible to a source of electrical energy and to an ignition system for an engine comprising:

at least one magnet, said magnet providing a magnetic field;

rotatable means for varying the strength of the magnetic field at a predetermined location;

first and second conductors, said first conductor being couplable to the source of electrical energy;

a Hall generator coupled across said conductors and including means responsive to the strength of the magnetic field at said predetermined location for providing an analog signal, a characteristic of which is related to the strength of said magnetic field at said predetermined location;

first means coupled across said conductors and responsive to the analog signal for providing a square wave signal which is related to said analog signal; second means for applying the square wave signal to the ignition system with the square wave signal providing timing signals for the ignition system;

a Zener diode coupled across said conductors for use in limiting the voltage across said conductors; and

a diode coupled between the second conductor and ground to provide protection against reverse voltages.

2. A breakerless distributor as defined in claim 1 wherein said square wave signal is a first square wave signal, said first means includes a Schmitt trigger coupled across said conductors and to said Hall generator for providing a second square wave signal and a transistor coupled across said conductors and to said Schmitt trigger, said second square wave signal controlling said transistor to cause said transistor to provide said first square wave signal.

3. A breakerless distributor as defined in claim 2 including a capacitor coupled across said conductors for protecting said first and second means against short duration transients.

4. A breakerless distributor as defined in claim 3 wherein said rotatable means includes a rotatable shield interposed between the magnet and said predetermined location.

Claims

1. A breakerless distributor connectible to a source of electrical energy and to an ignition system for an engine comprising: at least one magnet, said magnet providing a magnetic field; rotatable means for varying the strength of the magnetic field at a predetermined location; first and second conductors, said first conductor being couplable to the source of electrical energy; a Hall generator coupled across said conductors and including means responsive to the strength of the magnetic field at said predetermined location for providing an analog signal, a characteristic of which is related to the strength of said magnetic field at said predetermined location; first means coupled across said conductors and responsive to the analog signal for providing a square wave signal which is related to said analog signal; second means for applying the square wave signal to the ignition system with the square wave signal providing timing signals for the ignition system; a Zener diode coupled across said conductors for use in limiting the voltage across said conductors; and a diode coupled between the second conductor and ground to provide protection against reverse voltages.