US 3923030 A
This invention relates to a contactless ignition timing system for an internal combustion engine wherein the timing signal is derived from the carrier signal of a modulated wave. The phase of the carrier signal is caused to change in magnitude and phase by the reaction of a toothed rotor with the magnetic field of a stator. A Hall element translates the changes in the magnetic field between the stator and rotor to a voltage output signal which produces a phase shift in the carrier frequency for each point of alignment of the rotor and stator. The change in phase is detected and used to trigger circuits to produce the H.V. ignition pulse.
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Description (OCR text may contain errors)
United States Patent 1 1 Luteran Dec.2, 1975 1 1 PHASE SENSITIVE IGNITION TIMING SYSTEM  Inventor: Frank Kenneth Luteran, 10 Charles St., Auburn, N.Y. 13021 221 Filed: Sept. 19,1974
211 Appl. 190.; 507,567
 References Cited UNITED STATES PATENTS 3,297,009 1/1967 Sasaki et al. 123/148 E 3,832 986 9/1974 Dogadko 123/148 E Primary ExaminerCharles J. Myhre Assistant Examiner.loseph Cangelosi [5 7] ABSTRACT This invention relates to a contactless ignition timing system for an internal combustion engine wherein the timing signal is derived from the carrier signal of a modulated wave. The phase of the carrier signal is caused to change in magnitude and phase by the reaction of a toothed rotor with the magnetic field of a stator. A Hall element translates the changes in the magnetic field between the stator and rotor to a voltage output signal which produces a phase shift in the carrier frequency for each point of alignment of the rotor 3,461,851 8/1969 Stephens 123/148 MCD and Stator The Change in Phase is detected and used 3,596,189 7/1971 Luteran 307 309 to igg r ir i to pr du he PIN. igni ion pulse. 3,738,339 6/1973 Huntzinger ct al... 123/148 E 3.831.571 8/1974 Weber 123/148 1-: 10 (318M514 Drawing Figures BATTER) W Z l 1 1- /1/UL7'/l//5647'0 SH/FTE? H.V. SWITCH CO/L --HJL5$ v 1 1 70 T- 82 DISTRIBUTOR w 8 22 1 /4 /r /a l U.S. Patent Dec. 2, 1975 Sheet 1 01 2 3,923,030
tLW l US. Patent Dec. 2, 1975 Sheet 2 of2 3,923,030
30 OUTPUT AMPL/F/ER /3 OUTPUT A/VD GATE Z9 OUTPUT 7 //VC'REA 5E CO/L 4Q CURRENT CO/L 44 CU/P/PE/VT PHASE SENSITIVE IGNITION TIMING SYSTEM BACKGROUND OF THE INVENTION The present invention relates to a contactless ignition system for use with internal combustion engines and chiefly for use with internal combustion engines for vehicles.
Many contactless or breakerless ignition systems are known. The inductive pickup is most common; a system of this type is represented by US. Pat. No. 3,749,974. Inductive systems require complex circuitry to process the trigger signals generated in the stator due to the dependence of the signal amplitude on rotor velocity. Other variations in trigger signal level occur due to changes in permanent magnetic field strength due to temperature and aging. An ignition system utilizing a Hall element is described in US. Pat. No. 3,297,009. The operation of the Hall element with permanent magnets again suffers from changes in the magnetic field due to temperature and aging effects. Also, the change in Hall characteristics with temperature and supply voltage variation produce timing errors that are not readily compensated for.
All known ignition systems utilizing a magnetic rotor to generate the timing signal suffer from timing errors due to changes in permanent magnet fields or changes in the operating points of the semiconductors caused by temperature and supply voltage changes.
SUMMARY OF THE INVENTION The present invention provides a new ignition system that generates ignition timing signals by measuring the phase shift of a carrier frequency signal that is modulated by a magnetic rotor. The phase shifted signal is generated when an alternating magnetic flux, impinging on a Hall element in a stator assembly, passes through the zero flux points. The resultant timing pulse is sensitive only to the instantaneous relative position of the rotor stator and the stator flux.
It is therefore a primary object of the invention to provide an ignition timing system that produces a timing signal that is dependent on the relative position of the rotor and stator.
Another object of the invention is to provide a system that produces a timing signal that is constant for all engine RPMs including cranking.
A further object of the invention is to provide a flux responsive timing system that does not require permenent magnets.
Yet another object of the invention is to provide an ignition timing signal that is insensitive to supply voltage and temperature variations.
And still another object of the invention is to provide an ignition system in which the timing signal can be advanced or retarded by electrically changing the stator flux field.
And yet an additional object of the invention is to provide a timing signal system in which AC coupling is used to effect signal coupling of all single ended signals throughout the signal processing circuits, thereby eliminating the dependence of the circuits on changing component values. I
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an electrical schematic diagram of the timing system.
FIG. 2 is a top view of acceptable rotor and stator members which may be used in this invention.
FIG. 3 illustrates the curves of signal voltages appearing at different points of the system illustrated.
FIG. 4 illustrates the advance-retard timing relationship of the stator coils currents.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings and more particularly to FIG. 1, the reference numeral 1 designates the negative terminal of the automobile battery and is the common connection for the circuits. Positive terminal 2 of the battery supplies the necessary electrical energy to all circuits. Multivibrator 3'generates a high frequency voltage waveform which is connected in push-pull arrangement through current limiting resistors 4 and 5 to control current inputs 6 and 7 of Hall element 8. The multivibrator signal is also connected to phase shifter 30. Hall element 8 is positioned in a magnetic field made up of positive field 9 and negative field 10. The fields 9 and 10 equally impinge on Hall element 8 so that when the fields are equal, the net magnetic field acting on element 8 is zero. The flux acts to develop a voltage across Hall signal outputs l1 and 12 which are coupled to differential amplifier 13. A portion of multivibrator 3 high frequency voltage is connected through potentiometer 33 to Hall signal output 11 and to differential amplifier 13. Potentiometer 33 provides a nulling signal to provide a zero differential Hall output to amplifier 13 when the net magnetic flux is zero. The amplified signal of differential amplifier 13 is coupled through capacitor 14 and limiting resistor 15 to clipping diodes l6 and 17. The diodes act to limit the amplitude of signals greater than the conduction voltage of the diodes and prevent overload of subsequent amplifier stages. The limited signal is coupled through capacitor l8 and input resistor 19 to operational preamplifier 20. Feedback resistor 21 is selected to set the gain of the preamplifier and diodes 22 and 23 and capacitor 24 act to prevent saturation of the amplifier by limiting the output swing to the conduction voltage of diodes 22 and 23. The preamplifier output is coupled through capacitor 25 and input resistor 26 to operational amplifier 27. Feedback resistor 22 is selected to set the gain of amplifier 27. The amplifier output is connected to AND gate 29. The output of phase shifter 30 is also connected to AND gate 29. The phase shifter provides a phase shift of the multivibrator high frequency signal equal to the phase shift produced by differential amplifier 13, preamplifier 20 and amplifier 27. AND gate 29 produces a timing output signal when both inputs are in phase and produces no output signal when the inputs are out of phase. The output of the AND gate activates switch 31 which supplies a current pulse to coil 32 which generates H.V. pulses which are connected to the distributor. The distributor provides the usual function of supplying the H.V. pulse to the proper engine cylinder.
In FIG. 2, rotor is affixed to distributor shaft 39 which rotates counterclockwise as shown by arrow 41. Rotor 40 has eight symmetrical lobes 42 equally spaced apart Stator 43 is positioned concentrically and planar with rotor 40. Advance coil 44 is wound on one leg of stator 43 and produces magnetic field 9 when current flows through coil 44 in the direction of arrow 45. Retard coil 46 is wound on the other leg of stator 43 and produces magnetic field when current flows in the direction of arrow 47. Current to advance coil 45 is supplied by advance current source 48 and current to retard coil 46 is supplied by retard current source 49 the current sources may be any transducers that provide a current output that relates the pulse timing of the engine to the engine operating conditions. Advance pole face 50 and retard pole face 51 of stator 43 are positioned so that the centerline through opposite lobes 42 intersects the outer edge of pole faces 50 and 51. Pole piece 52 is positioned perpendicular to a line drawn through the centers of pole faces 50 and 51 and intersecting the line at the midpoint. Pole piece 52 is adhesively attached to stator 43 by non-magnetic supports 53. Hall element 8 is inserted in the space between pole piece 52 and stator 43. The Hall element 8 is positioned so that magnetic fields 9 and 10 perpendicularly impinge on the active surface of the element. The Hall element produces an output voltage when the net magnetic field impinging on the element is not zero. A net magnetic field in the direction of field 9 produces a signal at Hall output leads l1, l2, and amplifier 27 that is in phase with phase shifter 30 output. A net magnetic field in the direction of field 10 produces a signal at the Hall output leads 11, 12, and amplifier 27 that is 180 out of phase with phase shifter 30 output.
In FIG. 3 the waveforms illustrate the signals that are generated for a rotation of the rotor 22Vz in either direction from the position shown in FIG. 2. The dashed line in FIG. 3 shows the output at the rotor 40 position shown in FIG. 2. Waveform 61 illustrates the phase shifter 30 output signal which has been phase shifted so that it can be either in phase or 180 out of phase with the output of amplifier 27 output depending on the direction of the net flux impinging on the Hall element. Waveform 62 shows the amplifier 13 output signal which has been both phase and amplitude modulated by the flux impinging on the Hall element. Waveform 63 illustrates the limited and amplified signal of amplifier 13 as it appears at the amplifier 27 output. Waveform 64 shows the output of AND gate 29 when the inputs are waveforms 61 and 63.
In FIG. 4, the relationship between differences in coil currents and the effect on timing signal advance and retard are graphically illustrated. The vertical scale shows the degrees CW and CCW at which the timing signal will occur for the rotor 40 position shown in FIG. 2 when the advance and retard coil currents are increased. Since the timing pulse is generated when the net flux through the Hall element passes from a maximum through zero, any action that changes the point at which the net flux goes from a maximum through zero will change the rotational position point at which a timing pulse is generated. An increase in advance coil 44 current will cause the net flux through Hall element 8 to be zero when the rotor is shifted CW from the position illustrated, thus the timing signal will occur in advance of the position where the timing pulse occurs for equal coil currents. An increase in retard coil 46 current will cause the net flux through Hall element 8 to be zero when the rotor is shifted CCW from the position illustrated, thus the timing signal will occur later or, retarded, from the position where the timing pulse occurs for equal coil currents.
In an operational system, the rotor lobes are selected to be equal to the number of cylinders in the IC engine or in the case of a rotary engine, three lobes per engine rotor. The stator is configured to provide two magnetic paths through the rotor and present a symmetrical magnetic circuit when the rotor is symmetrically positioned with respect to the stator.
Since the output of AND gate circuit consists of a series of high frequency pulses, the switch means can be triggered by only the first pulse or can be triggered by each pulse successively to provide multiple H.V. pulses. The capability of changing the timing pulse position electrically leads to possibilities of controlling the timing by an engine computer which will set the timing to be optimum for all engine conditions.
1. An ignition timing system for an internal combustion engine comprising:
a. an engine having a distributor shaft;
b. a magnetic permeable rotor with a plurality of lobes affixed to the distributor shaft;
c. a magnetic permeable stator with a plurality of poles concentrically positioned about the rotor;
d. energization coils wound on the stator and producing a magnetic field upon energization thereof;
e. electrical current sources means providing energization of the coils in accordance with the ignition timing requirements of the engine;
f. a Hall element attached to a pole piece of said stator and disposed in said magnetic field, said element having control input leads and output signals leads, generating an output signal of the same frequency as the control input signal, phase and amplitude modulated in accordance with the amplitude and direction of the instantaneous value of said magnetic field;
g. signal generator means producing a high frequency signal and connected to the control leads of the Hall element;
h. differential amplifier means connected to the output signal of the Hall element and producing an output signal;
i. amplifier means connected to the output of the differential amplifier and producing an amplitude limited output signal;
j. phase shifter means connected to the signal generator means and producing a high frequency output signal that is phase shifted an amount equal to the phase shift occurring in the differential amplifier and the amplifier;
k. an AND gate combining the amplifier output signal and the phase shifter output signal and producing a timing signal when the amplifier and phase shifter signals are in phase;
I. H.V. pulse generating means for producing an ignition pulse when the timing signal is generated.
2. A timing system according to claim 1 wherein the magnetic permeable rotor includes a plurality of uniformly, angularly spaced lobes, the number of which is directly related to the number of cylinders in the engine.
3. A timing system according to claim 2 wherein the magnetic permeable stator comprising a noncontiguous member with a pair of poles at each end of the discontinuity, the poles symmetrically aligned about the center line of the stator, a third pole space midway between the pair of poles and symmetrically aligned about the center line.
4. A timing system according to claim 1 wherein the energization coils comprise a retard coil and an advance coil the retard coil causing the timing pulse to be generated at a later position when the retard coil current is increased. the advance coil causing the timing pulse to be generated at an earlier position when the advance coil current is increased.
5. A timing system according to claim 1 wherein the amplifier means comprises an operational amplifier with a limiting circuit in the feedback loop, the limiting circuit including a pair of parallel opposing diodes in series with a capacitor.
6. A timing system according to claim 1 wherein the signal generator means comprises a transistorized multivibrator and is connected in push-pull arrangement to the control leads of the Hall element.
7. A timing system according to claim 6 wherein the signal generator means generates a non-symmetrical rectangular waveform.
8. A timing system according to claim 1 wherein the Hall element output signal is summed with a portion of the high frequency signal to produce a zero Hall output when the net magnetic field is zero.
9. A timing system for an internal combustion engine comprising;
a. an engine having a distributor;
b. a magnetic permeable stator and rotor, said rotor affixed to the distributor shaft. and said stator affixed to a non-rotating member of the engine in coaxial relationship to said rotor;
. magnetic means for producing two magnetic circuits in the rotor-stator combination. said magnetic circuits having a common path through the combination, the common path flux flowing through said rotor-stator combination being a function of the instantaneous rotor position and independent of said rotor rotational speed said common flux reversing direction during rotation through each rotor-stator symmetry point;
d. A Hall element disposed in said common flux responsive to the instantaneous amplitude and direction of said flux and producing a voltage level output dependent on said flux amplitude and a voltage polarity dependent on said flux direction;
e. gating means for producing a timing signal whenever the output signal of the Hall element changes phase. I
10. A timing system according to claim 8 wherein the rotor is comprised of the number of lobes as the number of engine cylinders.